Diesel, injection, carburetor power supply systems for internal combustion engines. Power system What is included in the power system

Often, when booking a hotel, tourists are faced with incomprehensible abbreviations and wonder what is RO, BB, HB, BF, AI, UAI? It's simple - these are the types of food in hotels, their decoding and detailed description from www.site, see below: Power RO (room only), RR (room rate), OB (Only Bed), AO (Accommodation Only) such abbreviations in the hotel mean accommodation in a room without meals. The most common is RO. Meals BB (bed breakfast), means "bed and breakfast", i.e. when staying at the hotel on the BB system, a bed in a room and breakfast are provided. Breakfast, as a rule, is supposed to be in the form of a "buffet" and the abundance of dishes depends on the level of the hotel and the country of residence. For example, a BB breakfast in Central Europe is significantly inferior to the BB accommodation option in Greece or the UAE. Power HB (half board), which means "half board" - breakfast and dinner. Some expensive hotels offer free champagne for breakfast. As a rule, meals are organized according to the "buffet" system. Non-alcoholic drinks under the HB system are free, you can order paid alcoholic drinks with payment on the spot or on the room. Power supply HB+ (half board plus) same half board but HB+ option includes some complimentary alcoholic drinks, usually locally produced. Food FB (full board), or "full board". Meals breakfast, lunch and dinner, as a rule, according to the buffet system. The FB system does not provide free spirits, with the exception of champagne for breakfast in some expensive hotels. FB alcoholic drinks can be ordered for dinner for additional fee. Power FB+ (full board plus)- similar to FB, but FB+ means some free alcoholic drinks, usually locally produced. AI meals (all inclusive)" ", multiple meals without restrictions. Depending on the level of the hotel, AI can range from three meals a day to multiple meals throughout the day - restaurants, barbecues, grills, night bars, etc. Complimentary local and lesser alcoholic drinks imported production. Imported spirits and cocktails under the AI ​​system are free only in expensive hotels, in simpler hotels, imported alcoholic drinks are subject to an additional charge and subject to availability. Meals AIP (all inclusive premium)"all inclusive premium" - is rare. AIP is similar to AI, but with great choice alcoholic beverages. Meals UAI (ultra all inclusive, UALL) type of food according to the "ultra all inclusive" system - multiple meals throughout the day at will in restaurants of different cuisines of the world, grill bars, night bars, etc., ice cream and sweets throughout the day. UAI means free non-alcoholic and alcoholic drinks of local and foreign production. What is a buffet? Website www.site prompt - buffet this is a type of self-service, in which there are several large tables and / or closed trays in the hall, which are displayed according to the types of dishes - salads, side dishes, fish, meat, desserts and fruits. Passing by the tables you need to choose dishes that you like and put on your plate. Expensive hotels have restaurants A la Carte (A-lacarte), often thematic and differing in the cuisines of the world. Everything here is like in a regular restaurant - you choose dishes from the menu and the waiter brings you orders. Depending on the type of food at the hotel, "A la Carte" restaurants can be both paid and free. It happens that if an "A la Carte" restaurant is paid (which is rare with paid AI or UAI meals), and you have paid HB or FB meals, you can dine at such a restaurant with a discount on the buffet dinner. It is important to remember that you can dine in such restaurants only by appointment, and if the restaurant is good, then it is better to do this a few days before visiting it. A

The vehicle's power system is used to prepare fuel mixture. It consists of two elements: fuel and air. The engine power system performs several tasks at once: cleaning the elements of the mixture, obtaining the mixture and supplying it to the engine elements. Depending on the vehicle power system used, the composition of the combustible mixture varies.

Types of power systems

There are the following types of engine power systems, which differ in the place where the mixture is formed:

1. inside the engine cylinders;
2. outside the engine cylinders.

The fuel system of a car, when a mixture is formed outside the cylinder, is divided into:

• fuel system with carburetor
• using one nozzle (with mono injection)
• injector

Purpose and composition of the fuel mixture

For uninterrupted operation A car engine needs a specific fuel mixture. It consists of air and fuel mixed in a certain proportion. Each of these mixtures is characterized by the amount of air per unit of fuel (gasoline).

An enriched mixture is characterized by the presence of 13-15 parts of air per part of the fuel. This mixture is fed at medium loads.

A rich mixture contains less than 13 parts of air. Used for heavy loads. There is an increase in fuel consumption.

A normal mixture is characterized by the presence of 15 parts of air to part of the fuel.
The lean mixture contains 15-17 parts of air and is used at medium loads. Provides economical fuel consumption. lean mixture contains more than 17 parts of air.

General arrangement of the power system

The engine power system has the following main parts:

• fuel tank. It serves to store fuel, contains a pump for pumping fuel and sometimes a filter. Has a compact size
• fuel line This device ensures the supply of fuel to a special mixture-forming device. Consists of various hoses and tubes
• mixing device. Designed to obtain a fuel mixture and supply to the engine. Such devices can be injection system, single injection, carburetor
• control unit (for injectors). Consists of an electronic unit that controls the operation of the mixing system and signals any malfunctions that occur
• fuel pump. Required for fuel to enter the fuel line
• cleaning filters. Necessary to obtain pure components of the mixture

Carburetor fuel supply system

This system is distinguished by the fact that mixture formation occurs in a special device - a carburetor. From it, the mixture enters the engine in the right concentration. The device of the engine power system contains the following elements: a fuel tank, fuel cleaning filters, a pump, an air filter, two pipelines: inlet and outlet, carburetor.

The scheme of the engine power system is implemented as follows. The tank contains fuel that will be used to supply to. It enters the carburetor through the fuel line. The feeding process can be realized with a pump or in a natural way using gravity.

In order for the fuel supply to be carried out by gravity into the carburetor chamber, it (the carburetor) must be placed below the fuel tank. Such a scheme is not always possible to implement in a car. But the use of a pump makes it possible not to depend on the position of the tank relative to the carburetor.

The fuel filter cleans the fuel. Thanks to him, mechanical particles and water are removed from the fuel. Air enters the carburetor chamber through a special air filter that cleans it from dust particles. In the chamber, the two purified components of the mixture are mixed. Once in the carburetor, the fuel enters the float chamber. And then it goes to the mixture formation chamber, where it combines with air. Through the throttle valve, the mixture enters the intake manifold. From here it goes to the cylinders.

After working off the mixture, the gases from the cylinders are removed using the exhaust manifold. Further from the collector, they are sent to the muffler, which suppresses their noise. From there, they enter the atmosphere.

Details about the injection system

At the end of the last century, carburetor power systems began to be intensively replaced by new systems operating on injectors. And not just like that. Such a device of the engine power system had a number of advantages: less dependence on the properties of the environment, economical and reliable performance, the exhaust is less toxic. But they have a drawback - this is a high sensitivity to the quality of gasoline. If this is not observed, then malfunctions in the operation of some elements of the system may occur.

"Injector" is translated from English as a nozzle. A single-point (single-injection) scheme of the engine power system looks like this: fuel is supplied to the nozzle. The electronic unit sends signals to it, and the nozzle opens at the right time. The fuel is directed to the mixing chamber. Then everything happens as in a carburetor system: a mixture is formed. Then it passes the intake valve and enters the engine cylinders.

The device of the engine power system, organized with the help of injectors, is as follows. This system is characterized by the presence of several nozzles. These devices receive signals from a special electronic unit and open. All these injectors are connected to each other with a fuel line. It always has fuel available. Excess fuel is removed through the fuel return line back to the tank.

The electric pump supplies fuel to the rail, where excess pressure is formed. The control unit sends a signal to the nozzles, and they open. Fuel is injected into the intake manifold. Air passing throttle assembly, gets there. The resulting mixture enters the engine. The amount of mixture required is regulated by opening throttle valve. As soon as the injection stroke ends, the injectors close again and the fuel supply stops.

The electronic unit is a kind of "brain" element of the system. This complex mechanism processes the signals coming to it from various sensors. This is how all devices of the fuel system are controlled. Such a scheme of the engine power system allows the driver to learn about malfunctions in time, since the control unit signals them using a special lamp and error codes. These codes allow specialists to quickly identify problems. To do this, they just need to connect an external diagnostic device that can recognize the problems that have arisen and name them.

Ministry of Education of the Russian Federation

Saint Petersburg State University

service and economy

Vehicles

"The design and operation of the power system gasoline engine»

Completed by a 3rd year student

Specialty 100.101

Ivanov V.I.

Saint Petersburg

Introduction

1. The operation of engines on the working mixture

2. The power supply system of the carburetor engine

3. Design and operation of the carburetor engine power system

4. The power supply system of a gasoline engine with fuel injection

5. Safety

List of used literature

Introduction

The power system is a set of devices and devices that supply fuel and air to the engine cylinders and remove exhaust gases from the cylinders.

The power supply system is used to prepare the combustible mixture necessary for the operation of the engine.

combustible is called a mixture of fuel and air in certain proportions.

1. The operation of engines on the working mixture

working called the mixture of fuel, air and exhaust gases formed in the cylinders during engine operation.

Depending on the place and method of preparing the combustible mixture, car engines can have different power systems (Fig. 1).

Rice. 1. Types of engine power systems classified according to various criteria

The power supply system with the preparation of a combustible mixture in a special device - a carburetor - is used in gasoline engines, which are called carburetor. For the preparation of a combustible mixture in a carburetor, a spray method is used. With this method, droplets of gasoline, falling from the atomizer into an air stream moving at a speed of 50 ... 150 m / s in the mixing chamber of the carburetor, are crushed, evaporate and, mixing with air, form a combustible mixture. The resulting combustible mixture enters the engine cylinders.

The fuel system with the preparation of a combustible mixture in the intake manifold is also used in gasoline engines. To prepare a combustible mixture, finely atomized fuel is injected from the injectors into the rapidly moving air stream in the intake manifold under pressure from the nozzles. The fuel is mixed with air, and the formed combustible mixture enters the engine cylinders.

The power supply system with the preparation of a combustible mixture directly in the engine cylinders is used in both diesel and gasoline engines. The preparation of a combustible mixture occurs inside the engine cylinders by injection of finely atomized fuel from nozzles under pressure into the air compressed in the cylinders. At the same time, if self-ignition of the formed working mixture from compression occurs in diesel engines, then in gasoline engines working mixture in the cylinders is ignited forcibly by spark plugs. The fuel injection system provides better filling of the engine cylinders with a combustible mixture and better cleaning of exhaust gases. At the same time, fuel injection allows you to increase the compression ratio and maximum power for gasoline engines, reduce fuel consumption and reduce exhaust emissions. However, fuel-injected power systems are more complex in design and maintenance in operation.

2. The power supply system of the carburetor engine

Fuel. Gasoline is the fuel for gasoline car engines. various brands- A-80, AI-93, AI-95, AI-98, where the letter A means automobile; I - method for determining the octane number of gasoline (research); 93, 95, 98- octane number, which characterizes the resistance of gasoline against detonation. The higher the octane number, the higher the compression ratio of the engine can be.

Detonation - the process of combustion of the working mixture with the explosion of its individual volumes in the engine cylinders with a flame propagation speed of up to 3000 m / s, while during normal combustion of the working mixture, the flame propagation speed is 30 ... 40 m / s. Combustion during detonation becomes explosive. The shock wave propagates in the engine cylinders at supersonic speed. The gas pressure rises sharply and the performance of the engine in terms of power and efficiency deteriorates. There are ringing knocks in the engine, black smoke from the muffler, and the engine overheats. At the same time, the parts of the crank mechanism quickly wear out and the valve heads burn.

To improve the anti-knock properties, tetraethyl lead, an anti-knock TES, is added to gasolines. Such gasolines are called leaded, they have a distinctive designation and color - AI-93-ethyl (orange-red) and AI-98-ethyl (blue). Leaded gasolines are very poisonous, and care must be taken when handling them - do not use for washing hands and parts, do not suck in the mouth when pouring, etc.

The use of leaded gasolines for vehicles in major cities forbidden.

3. Design and operation of the carburetor engine power system

The power supply system of a car engine consists of a fuel tank, fuel pump, air filter, carburetor, fuel lines, intake and exhaust pipes, muffler pipes, main and additional mufflers (Fig. 2).

Fuel from tank 6 is supplied by pump 7 through fuel lines 5 to the carburetor 4. Through the air filter 1 air enters the carburetor. The combustible mixture prepared in the carburetor is fed into the engine cylinders through the inlet pipeline 2. Exhaust gases are discharged from the engine cylinders to the environment through the exhaust pipe 3, pipe 8 mufflers, main 10 and additional 9 mufflers.

Rice. 2. Engine power system:

1 - air filter; 2,3 - pipelines; 4 - carburetor; 5 - fuel line; 6 - tank; 7 - pump; 8 - pipe; 9, 10 - mufflers

A filter is often installed in the engine power system fine cleaning fuel. The fuel tank is connected by a hose to a separator (a special device) used to condense gasoline vapors, and a drain pipe to the carburetor. Check valves are installed on the separator hose and drain pipe. One valve prevents fuel from draining from the tank through the carburetor when the car rolls over, and the other valve connects the internal cavity of the tank with the atmosphere. Fuel is supplied to the system with part of it drained back from the carburetor (through a calibrated hole) into the fuel tank, which ensures constant fuel circulation in the system. Constant fuel circulation eliminates air locks in the system, improves its operation and contributes to additional engine cooling.

Fuel tank serves to store the fuel supply required for a certain vehicle mileage. Vehicles use welded, stamped steel fuel tanks coated with lead to prevent corrosion, or plastic. A tank filled with gasoline provides a vehicle mileage of 350 ... 400 km.

The fuel tank (Fig. 3) is welded from two trough-shaped halves 1. In the upper part, the tank has a filler neck, consisting of a receiving 13 and bulk 10 pipes with seal 8 and rubber connecting hose 11. The filler neck is closed with a threaded hermetic plug 6 with gasket 7. At the bottom of the tank is drainer with screw plug 14. The amount of fuel in the tank is controlled by a pointer, a sensor 3 which is installed inside the tank. Fuel is taken from the tank through the fuel receiving tube 2, which has a strainer, and through the hose 4 and fuel line 5 enters the fuel pump. The connection of the internal cavity of the tank with the environment and its ventilation are carried out through the air 12 and ventilation 9 tubes.

Rice. 3. Fuel tank:

1 - half a tank; 2, 9, 12 - tubes; 3 - sensor; 4, 11 - hoses; 5 - fuel line; 6, 14 - traffic jams; 7 - gasket; 8 - sealant; 10, 13 - pipes

In the fuel tanks of cars, there are often special baffles to increase rigidity and reduce fuel fluctuations when driving inside. In addition, an anti-drainage device is placed in the lower part of the tank, made in the form of a glass with a diameter of 150 and a height of 80 mm. This device is designed to prevent interruptions in the operation of the engine and its stop during a sharp start or hard braking, as well as when the car is moving at high speeds when cornering.

The shape of the fuel tank largely depends on its placement on the vehicle. The tank can be located under the body floor, in the trunk, under the rear and behind back seat, i.e. in places more protected from impacts in collisions. The fuel tank is attached to the car body.

Fuel pump serves to supply fuel from the fuel tank to the carburetor. Self-regulating, diaphragm-type fuel pumps are installed on car engines.

In the fuel pump (Fig. 4) between the top 7 (with a cover 9) and bottom 1 diaphragm block is installed by parts of the body 3, which is connected to the stem 11. The rod is covered by the forked end of the balancer 15 lever 16 pump drive. A spring is installed on the stem 2 diaphragm block. At the top of the pump housing are the suction 10 and delivery 4 valves. The pump is driven by a pusher from the eccentric of the oil pump drive shaft. Under the influence of the eccentric, the pusher presses the upper part of the lever 16, and the balancer 15 through stem 11 moves the aperture block 3 down. At the same time, the spring 2 shrinks. The volume of the cavity above the block of diaphragms increases, and the fuel under the action of vacuum from the tank enters the pump through the suction pipe 8, strainer b and suction valve 10. The discharge valve of the pump is closed. Up the diaphragm unit moves under the action of a spring 2, when the balancer 15 does not hold stock 11.

Rice. 4. Fuel pump:

1,7 - body parts; 2, 13 - springs; 3 - diaphragm block; 4, 10 - valves; 5, 8 - branch pipes; 6 - filter; 9 - lid; 11 - stock; 12, 16 - levers; 14 - eccentric; 15 - balancer

Fuel pressure opens the delivery valve 4, and fuel through the discharge pipe 5 enters the carburetor. The suction valve is then closed. When the float chamber of the carburetor is full, the float shut-off needle will block the flow of fuel into the carburetor. In this case, the fuel pump diaphragm unit will remain in the lower position, and the lever 16 with a balancer will move idly. Lever arm 12 with spring 13 serves for manual pumping of fuel into the carburetor before starting the engine. It affects the balance 15 through the eccentric 14. The pump is self-regulating - at low fuel consumption, the stroke of the diaphragm block is underused, and the stroke of the mechanical fuel pumping lever with a balancer will be partially idle. The fuel pump is mounted on a special tide on the engine block and is attached to it with two studs.

Fuel fine filter cleans the fuel entering the carburetor from mechanical impurities. Fuel cleaning is necessary so that the channels and jets of the carburetor, which have small sections, do not become clogged. The fuel fine filter can be made non-separable (Fig. 5, A). Paper filter element 3 such a filter is located in the housing 2 with a lid, which are made of plastic and are welded together by currents high frequency or ultrasonic welding. Fuel enters the filter from the pump through the nozzle 4, passes through the filter element, is cleaned in it and through the nozzle 1 enters the carburetor.

Collapsible filters are also used for fine purification of fuel.

Collapsible filter (Fig. 5, b) consists of body 2, sump 5 and filter element 3. The filter element is made of a brass mesh wound in two layers on an aluminum alloy cup, which has fins and holes for fuel passage on the side surface. The mesh on the glass is held by a spring, put on the outside of the filter element. filter element 3 is located inside the sump 5 and is pressed by a spring 6 to the filter housing through the sealing gasket.

Rice. 5. Fuel filters:

A - non-separable; b- collapsible; 1, 4 - branch pipes; 2 - frame; 3 – filter element; 5 - sump; 6 - spring

When cleaning, the fuel first enters the sump, where the largest particles of impurities are deposited, and then it is cleaned, passing through the mesh into the glass of the filter element.

Fuel filters are usually installed between the fuel pump and the carburetor.

Air filter cleans the air entering the carburetor from dust and other impurities. The dust contains the smallest hard quartz crystals, which, settling on the lubricating surfaces of the rubbing engine parts, cause their intense wear.

On car engines, dry-type air filters with replaceable paper or cardboard filter elements are mainly used.

Air filter (Fig. 6, A) consists of body 1, cover 7 and filter element 3. The steel stamped case has a branch pipe 10 cold air intake from the engine compartment, branch pipe 2 fence warm air from the air intake to the exhaust pipe, the exhaust manifold of the crankcase ventilation system and the axis of the reinforcement cover. The filter housing is mounted on the carburetor and attached to it on four studs with self-locking nuts. Filter housing cover - steel, stamped, has a baffle 8, depending on the location of which seasonal adjustment of the temperature of the air entering the engine is provided. In summer, the filter cover is installed so that the baffle 8 covers the branch pipe 2, and cold air enters the engine. In winter, the cover is set to a position in which the partition 8 covers the branch pipe 10, and warm air enters the engine. The tightness of the connection between the cover and the filter housing is ensured by a rubber gasket 6. filter element 3 has a cylindrical shape. It consists of a pleated cardboard filter 5 and a pre-cleaner lining 4 from non-woven synthetic material(layer of synthetic wool). The pre-cleaner lining acts as an air pre-cleaning element and increases the dust capacity of the filter. The air entering the filter first passes through the pre-cleaner, and then through the cardboard filter element.

The air filter shown in fig. 6, b, has a thermostat. Frame 22 caviar 7 filters - steel, stamped. The housing contains a cardboard filter element. 19 with an outer layer of synthetic wool for preliminary air purification, increasing the dust capacity of the filter. The filter element is tightly pressed against the body with a cover, which is attached to the body with a stud 20 nut and four latches 21. The pin is installed in a bracket welded to the body. The tightness of the cover with the body is ensured by a sealing gasket 18. The filter housing is mounted on the carburetor and attached to it through the plate 23 and rubber gasket 24 on four studs with self-locking nuts. The housing has a suction port on the bottom. crankcase gases, and on the side - a branch pipe 16 air intake, on which the thermostat is fixed with a coupling bolt 13. The thermostat provides a constant supply of heated to a temperature of 25 ... 35 °С air. It has a plastic housing with a pipe 12 cold air inlet and spigot 11 with hose 14 warm air supply. There is a damper inside the thermostat. 25 driven by a thermal force element 15, which allows you to automatically maintain the required temperature of the air entering the air filter.

Rice. 6. Air filters:

O - without thermostat; b- with thermostat; 1, 22 - corps; 2, 10, 11, 12, 16 - branch pipes; 3, 19 - filter elements; 4 - lining-precleaner; 5- filter; 6, 18, 24- gaskets; 7, 17- covers; 8- partition; 9 – axis; 13 - thermostat; 14 - hose; 15 - thermal power element; 20 - hairpin; 21 - latch; 23 - plate; 25 - damper

At an air temperature below 25 ° C, the damper closes the branch pipe 12 cold air supply, and enters the filter through the pipe 11 warm air from the engine exhaust pipe area. At an air temperature of more than 35 ° C, the damper closes the branch pipe 11, and through the tube 12 cold air enters from the engine compartment. Intermediate positions of the thermostatic damper provide a mixture of warm and cold air, which contributes to better mixture formation, more complete combustion mixture and, as a result, reduce the toxicity of exhaust gases and reduce fuel consumption.

The dry type air filter with a replaceable paper filter element is shown in fig. 7. The filter consists of a housing 6, cover 5 and filter paper element 7 cylindrical. The plastic housing of the filter has a branch pipe 8, through which it is connected by a rubber corrugated hose to the carburetor air intake. A special device is installed in the plastic cover of the filter housing 4 with damper 3, depending on the location of which seasonal adjustment of the temperature of the air entering the engine is provided. In summer, the damper is set to the lower position, blocking the pipe 1, and cold air enters the engine. In winter, the damper is set to the upper position, blocking the pipe 2, and warm air enters the engine.

Carburetor serves to prepare a combustible mixture (gasoline with air) in quantities and composition corresponding to all engine operating modes.

The carburetor is mounted on the intake manifold of the engine.

The simplest carburetor (Fig. 8) consists of a float chamber 8 with float 9 and needle valve 10 and a mixing chamber containing a diffuser 3, spray 4 with jet 7 and throttle valve 5.

The float chamber contains gasoline necessary for the preparation of a combustible mixture. A float with a needle valve keeps the gasoline in the float chamber and atomizer at Constant level- 1...1.5 mm below the end of the atomizer. This level provides good suction of gasoline and eliminates the leakage of fuel from the atomizer when the engine is not running.

If the level of gasoline drops, then the float with the valve is lowered and gasoline enters the float chamber. If the level of gasoline has reached normal, the float pops up and the valve closes the access of gasoline to the float chamber.

The atomizer delivers gasoline to the center of the mixing chamber of the carburetor. The atomizer is a tube that enters the mixing chamber and communicates with the float chamber through the jet.

The jet passes a certain amount of gasoline, which enters the sprayer. The jet is a plug with a calibrated hole.

The mixing chamber is used to mix gasoline with air. The mixing chamber is a branch pipe, one end of which is connected to the engine inlet pipeline, and the other - to the air filter.

The diffuser serves to increase the air flow rate in the center of the mixing chamber. It creates a vacuum at the end of the atomizer. The diffuser is a branch pipe narrowed inside.

The throttle valve regulates the amount of combustible mixture coming from the carburetor into the engine cylinders.

The carburetor works as follows.

At intake strokes to the mixing chamber 6 air enters. in diffuser 3 the air speed increases, and at the end of the atomizer 4 a vacuum is formed. As a result, gasoline is sucked out of the atomizer and mixed with air. The resulting combustible mixture enters the cylinders 12 engine through the intake manifold P.

When the engine is running, the driver of the car controls the throttle valve 5. The control is made from the cab using the pedal. The throttle valve is set to various positions depending on the required load on the engine. In accordance with the position of the throttle valve, a different amount of combustible mixture enters the engine cylinders.

Rice. 8. Scheme of the device and operation of the simplest carburetor:

1 - fuel line; 2 - air connection hole; 3 - diffuser; 4 - spray; 5 - damper; 6 - mixing chamber; 7 - jet; 8 - float chamber; 9 - float; 10 - valve; 11 - pipeline; 12 - engine cylinder

As a result, the engine develops different power, and the car moves at different speeds.

The car engine has the following five modes of operation: start, idle, medium (partial) loads, a sharp transition from medium load to full and full load.

At each operating mode, the engine cylinders must receive a combustible mixture in a different quantity and quality of different composition. Only in this case the engine will work stably and have the best performance in terms of power and efficiency.

In all the indicated engine operating modes, the simplest carburetor cannot provide the engine with a combustible mixture. required quality and in the required quantity. Therefore, the simplest carburetor is equipped with additional devices that provide normal work engine in all modes.

The main additional devices of the carburetor include a starting device (choke), a system idle move, main dosing device, accelerator pump and economizer.

The starting device ensures the supply of fuel from the atomizer in the amount necessary to start the engine.

The idling system allows the engine to operate without load at low engine speeds.

The main metering device ensures engine operation at partial (average) engine loads.

The accelerator pump is used to automatically enrich the combustible mixture during a sharp transition from partial to full load in order to quickly increase engine power,

The economizer serves for automatic enrichment of the combustible mixture at full engine load.

The design and operation of carburetor accessories are discussed below.

On car engines, two-chamber balanced carburetors with a falling mixture flow are used. The carburetors have two mixing chambers, which are put into operation sequentially - first, the main chamber (primary), and with an increase in engine load, an additional chamber (secondary). This allows you to increase engine power as a result of better dosage and distribution of the combustible mixture over the engine cylinders. The flow of the combustible mixture in the carburetor chambers moves from top to bottom, which improves the filling of the cylinders with the mixture. The float chamber of carburetors is balanced (balanced), as it is connected to the atmosphere through an air filter. This ensures that the carburetors prepare a combustible mixture that does not depend in its composition on the degree of clogging of the air filter. The float chamber is located in front of the carburetors (in the direction of the car), which eliminates the re-enrichment of the combustible mixture during braking and increases the fuel level in the atomizers when driving on slopes to enrich the combustible mixture and increase engine power.

A car carburetor usually consists of three main parts: the body, the cap, and the throttle body. They contain all the systems and devices of the carburetor, which ensure the preparation of a combustible mixture under various engine operating modes and reduce the toxicity of exhaust gases.

Consider the design of a modern carburetor (Fig. 9). In case 43 and lid 44 placed float chamber 16 with float 24 and needle valve 17, primary I and secondary II mixing chambers, as well as systems and devices that provide the preparation of a combustible mixture.

Rice. 9. Carburetor scheme:

I, II - mixing chambers; 1 - pneumatic element; 2 - stock; 3 - channel; 4, 10, 17, 23, 40 - valves; 5, 22, 25, 26, 28, 38 - fuel jets; 6, 7, 14, 15 - air jets; 8, 30, 32 - flaps; 9, 11, 12, 13 – sprayers; 16 - float chamber; 18, 20, 36, 37 - branch pipes; 19 - filter; 21 - economizer; 24 - float; 27, 39 - tubes; 29, 33 – holes; 31 - gap; 34 - heating block; 35 - screw; 41 - diaphragm; 42 - lever arm; 43 - frame; 44 - lid

The carburetor is equipped with: heating unit 34, through which the coolant of the engine cooling system circulates; crankcase exhaust system, including a pipe 36 and calibrated hole; a system for draining part of the fuel from the carburetor into the fuel tank, including a pipe 18 and calibrated hole. It has a secondary camera lock. The lock does not allow opening the throttle valve of the secondary chamber in any engine operating mode if the air damper is not fully open. This prevents the operation of the secondary chamber when the engine is cold. Fuel enters the carburetor through the nozzle 20 and filter 19, and through the tube 37 the carburetor is connected to a vacuum ignition regulator.

The main dosing system prepares a lean combustible mixture (up to 16.5 kg of air per 1 kg of gasoline) when the engine is running at medium (partial) loads. The prepared mixture in different quantities is close to economical in composition over the entire range of medium loads, the value of which is up to 85% of the full engine load. Only with this preparation of a combustible mixture by a carburetor does the engine work most economically.

The main metering systems of the primary and secondary chambers include the main fuel jets 38 And 28, emulsion wells with emulsion tubes 39 and 27, main air jets 6 And 14, atomizers 9 And 12. When opening the throttle 32 primary chamber fuel from the float chamber 16 through the main fuel jet 38 enters the emulsion well. In it, the fuel is mixed with air coming out of the emulsion tube holes. 39, in which air enters through the main air jet 6. Emulsion through a sprayer 9 enters the small and large diffusers of the primary chamber and mixes with the air passing through the diffusers, where a combustible mixture is formed. The main dosing system of the secondary chamber works similarly to the main dosing system of the primary chamber. throttle valve 30 the secondary chamber is connected mechanically to the throttle valve 32 primary chamber in such a way that it begins to open when the throttle valve of the primary chamber is open to 2/3 of its value.

Throttle valves have a mechanical (cable) drive from the control pedal located in the passenger compartment. The amount of combustible mixture entering the engine cylinders is controlled by the opening of the throttle valves. In medium load modes, the primary chamber of the carburetor operates mainly, ensuring engine operation in a wide range of partial loads.

The starting device ensures the preparation of a rich combustible mixture (less than 13 kg of air per 1 kg of gasoline) when starting a cold engine. The combustible mixture enters the engine cylinders in large quantities so that even with a cold engine, light fractions of gasoline evaporate in the amount necessary to start the engine.

The starting device consists of an air damper 8 and associated pneumatic element 1. air damper through stem 2 connected to the diaphragm of the pneumatic element and acted upon by a return spring. When starting a cold engine, the throttle 32 the primary chamber opens. At the same time, the return spring, acting on the lever of the air damper axis, holds it in the closed position. The amount of air entering the primary chamber decreases, the vacuum in the diffusers increases, and the fuel, flowing out of the atomizer 9, ensures the formation of a combustible mixture. At the first flashes and subsequent engine idling, the vacuum from under the throttle 32 transmitted over the channel 3 into the pneumatic element 1. Its diaphragm flexes and the stem 2 opens the air damper to allow access required amount air, and the choke return spring is stretched. Therefore, when starting a cold engine and warming it up, the air damper is automatically set to a position that excludes excessive enrichment or depletion of the combustible mixture. As the engine warms up, the choke valve opens fully through cable drive starter control handle located under the instrument panel.

The idle system prepares an enriched combustible mixture (up to 13 kg of air per 1 kg of gasoline). When the engine is idling, a small amount of rich mixture enters the engine cylinders so that the engine runs stably.

The idle system includes: a fuel channel originating from the emulsion well of the primary chamber; fuel jet 5; air jet 7; emulsion channel; mix quality (composition) screw 35; mix amount screw; outlet 33. At idle throttle 32 ajar. At the same time, the transition gap 31 idle system is located above the upper edge of the throttle valve. The air damper is fully open. Under the action of vacuum, the fuel from the emulsion well through the channel enters the idle fuel jet 5, where it mixes with the air entering through the idle air jet 7. The resulting emulsion is mixed with air passing through the transition slot 31, and goes under the throttle 32 through the hole 33. gap 31, located above the throttle valve, provides the flow of emulsion under the throttle valve for smooth transition engine from idle to partial loads. When the engine is idling, the quality of the mixture is regulated by a screw 35, and the quantity - with the mixture quantity screw, when screwed in, the throttle valve opens slightly. When the ignition is turned off, the solenoid valve is turned off. 4. Its needle, under the action of a spring, locks the fuel jet 5 and excludes the operation of the idling system when the ignition is off. The idling system has a primary chamber of the carburetor, and the secondary chamber is equipped with an adapter system.

The transition system smoothly activates the secondary chamber of the carburetor with small openings of its throttle.

The secondary chamber transition system includes a fuel jet 26 with tube, air jet 15 and emulsion channel with outlets 29. At the start of throttle opening 30 in front of holes 29 a large vacuum is created. As a result, through the fuel jet 26 fuel is supplied, and through the air jet 15 - air. The resulting emulsion is fed through the channel to the outlets. 29, through them enters the throttle valve 30 and enriches the combustible mixture. As a result, a smooth inclusion in the work of the secondary chamber of the carburetor is ensured.

The accelerator pump enriches the combustible mixture during an abrupt transition of the engine from medium to full load (overtaking, driving after stopping at a traffic light, etc.).

The accelerator pump increases the throttle response of the engine, i.e. the ability to quickly develop maximum power.

Accelerator pump - diaphragm, mechanically driven. Fuel enters the pump from the float chamber through the inlet ball valve 40, With a sharp opening of the throttle valve of the primary chamber of the carburetor, a special cam mounted on the valve axis acts on the lever 42 pump drive that presses on the diaphragm 41. The diaphragm, overcoming the force of the return spring, bends and pushes the fuel through the channel, the discharge valve 10 and atomizer 11 An accelerator pump into the primary and secondary chambers, while enriching the combustible mixture. The inlet valve of the accelerator pump is closed at this moment.

Econostat serves for additional enrichment of the combustible mixture at full engine load. Econostat is an economizer device. Econostat includes a fuel jet 25 with tube, fuel channel and nozzle 13. The secondary chamber of the carburetor is equipped with an econostat. It comes into operation at wide open throttle and maximum engine speed. In this case, fuel from the float chamber flows through the fuel jet 25 and fuel channel to the atomizer 13 econostat and from it into the secondary chamber of the carburetor, enriching the combustible mixture.

The power mode economizer eliminates the change in the degree of enrichment of the combustible mixture due to vacuum pulsation under the throttle valves of the carburetor. The process of suction of a combustible mixture into the engine cylinders is intermittent, and its pulsation (vacuum pulsation) increases with a decrease in the crankshaft speed. In this case, the vacuum pulsation is transmitted to the main dosing system, reducing its efficiency of automatic control of the composition of the combustible mixture. Economizer 21 power modes - diaphragm type. It is connected to the main dosing system of the primary chamber by a fuel channel in which a fuel jet is installed. 22 economizer, and through the ball valve 23 - with float chamber 16. The economizer is also connected by an air channel to the under-throttle space. With slight throttle opening 32 ball valve 23 closed as the economizer diaphragm is held by vacuum under the throttle. With a significant opening of the throttle valve, the vacuum decreases, the economizer diaphragm with the needle flexes under the action of the spring and opens the valve 23. Fuel from the float chamber passes through the open valve, the fuel jet 22 and fuel channel to the emulsion well with a tube 39. It is added to the fuel leaving the main fuel jet of the primary chamber and enters through the atomizer 9 into the primary chamber of the carburetor, aligning the composition of the combustible mixture.

The forced idle economizer provides a reduction in fuel consumption and reduces the toxicity of exhaust gases in the forced idle mode of the engine.

The forced idle economizer consists of a limit switch mounted on the idle mixture amount adjusting screw, an electromagnetic shut-off valve 4 and electronic control unit. In forced idle mode (engine braking, downhill driving, when shifting gears), the throttle valves of the primary and secondary chambers of the carburetor are closed, the throttle control pedal is released. In this case, the carburetor limit switch is closed, the solenoid valve 4 turns off, its needle locks the idle fuel jet 5, and the fuel supply to the idle system stops.

Rice. 10. Inlet and outlet pipelines:

1, 5 - pipelines; 2, 4,6,7- flanges; 3 - a tube; 8 - hairpin

Inlet and outlet pipelines provide the supply of a combustible mixture to the cylinders and the removal of exhaust gases. The inlet pipeline serves to uniformly supply the combustible mixture from the carburetor to the engine cylinders.

On car engines, an intake manifold cast from an aluminum alloy is used. For better evaporation of the fuel deposited on the walls, the pipeline has a heater (jacket), in which the liquid of the engine cooling system circulates. The exhaust pipeline is designed to remove exhaust gases from the engine cylinders. Cast iron exhaust pipes are installed on car engines. Inlet pipeline 5 motor (fig. 10) has flanges 4 And 6. Flange 4 designed to install a carburetor, and the flange 6 - for connection with the cylinder head.

exhaust pipeline 1 has flanges 2 and 7 flange 2 serves for fastening the exhaust pipe of silencers, and flange 7 - for connection with the cylinder head. Inlet and outlet pipes are secured with studs 8 to the cylinder head through metal-asbestos gaskets, ensuring the tightness of their connection.

Muffler reduces noise during the release of exhaust gases from the engine cylinders. On cars usually two mufflers (main and secondary) are installed, which ensures double expansion of the exhaust gases and more effective reduction of exhaust noise. Both mufflers have the same device and differ only in size and materials used for them.

Rice. 11. Silencers:

1 - main muffler; 2, 3, 7, 8 - pipes; 4, 6 - partitions; 5 - additional muffler

All parts of the main muffler 1 (Fig. 11) are made of corrosion-resistant steel, and parts of the additional muffler 5 are made of carbon steel. Silencers are non-separable, welded from two stamped halves. There are pipes inside the mufflers 3 and 7 with a lot of holes, as well as baffles 4 And 6. Exhaust gases from exhaust pipes 8 into the mufflers, first into the additional 5, and then in the main 1, they expand, change direction and, passing through the holes in the pipes, sharply reduce their speed. This leads to a reduction in exhaust noise through the pipe. 2. Silencers reduce the noise of exhaust gases emitted into the environment by up to 78 dB. The loss of engine power to overcome the resistance of the mufflers is approximately 4%. Silencers on the car are attached to the floor of the body with rubber parts.

4. The power supply system of a gasoline engine with fuel injection

The power supply system of a fuel injected engine includes a fuel tank, a fuel pump, fuel filter, air filter, injectors, fuel pressure regulator, engine fuel line, intake and exhaust pipes, fuel lines, muffler exhaust pipes, resonators and muffler.

On fig. 12 shows a diagram of a part of the engine power supply system with fuel injection, which supplies fuel and air to the cylinders and prepares the combustible mixture necessary for all engine operating modes.

Fuel from the tank 6 through the fuel filter 8 and fuel lines are supplied by pump 7 to the fuel line 2 engine, which is installed on the intake pipe 4 and in which the nozzles are fixed 3.

Rice. 12. The scheme of the power supply system of the engine with fuel injection:

1 - damper; 2 - engine fuel line; 3 - nozzles; 4 - inlet pipeline; 5 - pressure regulator; 6 - tank; 7 - pump; 8 - filter

Clean air enters the intake manifold from the air filter, the amount of which is regulated by the air throttle 1. Regulator 5, when the engine is running, maintains fuel pressure in the fuel line 2 engine and injectors 3 within 0.28 ... 0.33 MPa. During the intake stroke, into the air flow moving at high speed in the intake manifold 4, under pressure from nozzles 3 finely atomized fuel is injected. The fuel is mixed with air, and the resulting combustible mixture from the inlet pipeline enters the engine cylinders in accordance with the engine operation order.

Exhaust gases are discharged from the engine cylinders through the exhaust pipeline, resonators and muffler into the environment.

Consider the device and operation of the devices of the engine power supply system with fuel injection.

Fuel pump(Fig. 13) is a centrifugal roller pump driven by an electric motor, which is mounted together with the pump in one sealed housing.

The centrifugal roller pump consists of a stator 3, the inner surface of which is slightly offset relative to the axis of the anchor 8 electric motor, cylindrical separator 16, connected to the armature of the electric motor, and rollers 17, located in the separator.

The separator with rollers is located between the base 2 and the cover 5 of the pump.

When the pump is running, fuel flows through the fitting 1 and channel 18 to the rotating separator 16, transported by rollers and through outlet channels 6 is fed into the cavity of the electric motor and further through the valve 11 and fitting 12 into the fuel line that supplies fuel to the fuel filter.

Rice. 13. Fuel pump:

1, 12 – fittings; 2 - base; 3 - stator; 4, 11 - valves; 5 - lid; 6, 18 - channels; 7, 9 - corps; 8 - anchor; 10 - collector; 13 - brush; 14 - clutch; 15 - shaft; 16 - separator; 17 - roller

The fuel entering the pump, passing through the electric motor, cools it. check valve 11 eliminates the draining of fuel from the fuel line and the formation air locks after turning off the fuel pump. Safety valve 4 limits fuel pressure, created by the pump, with its increase above the permissible - 0.45 ... 0.6 MPa. The fuel pump turns on when the ignition is turned on. The pump flow is 130 l/h.

Engine fuel line(Fig. 14) is used to supply fuel to the injectors. It is common to four nozzles. One end of the fuel line 4 screwed fitting 3 for supplying fuel from the pump, and a regulator is fixed at the other end 5 fuel pressure connected to the receiver and fuel tank. Injectors are fixed at one end in the fuel line of the engine 2, which are fixed at the other end in the inlet pipeline 1. The nozzle ends are sealed with O-rings. fuel line 4 fastened with two bolts to the inlet pipeline.

Fuel pressure control(Fig. 15) maintains the pressure in the fuel line and injectors of a running engine within 0.28 ... 0.33 MPa, which is necessary to prepare a combustible mixture of the required quality in all engine operating modes. The pressure regulator consists of a housing 1 and lids 3, between which the diaphragm is fixed 4 s valve 2. The internal cavity of the regulator is divided by a diaphragm into two cavities - vacuum and fuel.

Rice. 14. Engine fuel line:

1 - inlet pipeline; 2 - nozzle; 3 - union; 4 - fuel line; 5 - pressure regulator

Rice. 15. Fuel pressure regulator:

A- the valve is closed; 6 - the valve is open; 1 - body; 2 - valve; 3 - lid; 4 - diaphragm

The vacuum cavity is in the lid 3 regulator and is connected to the receiver, and the fuel cavity is in the housing 1 regulator and connected to the fuel tank.

When choke 1 is closed (see Fig. 12), the vacuum in the receiver increases, the regulator valve opens at a lower fuel pressure and bypasses excess fuel through the fuel return line to the fuel tank 6. At the same time, the fuel pressure in the fuel line 2 engine is lowered. When the air throttle valve is opened, the vacuum in the receiver decreases, the regulator valve opens already at a higher fuel pressure. As a result, the fuel pressure in the engine fuel line rises.

Nozzle(Fig. 16) is a solenoid valve. The nozzle is designed to inject a metered amount of fuel necessary for preparing a combustible mixture under various engine operating modes. The dosing of the amount of fuel depends on the duration of the electrical impulse entering the coil winding of the injector solenoid. Fuel injection nozzle is synchronized with the position of the piston in the engine cylinder.

Rice. 16. Nozzle;

1 - nozzle; 2 - needle; 3, 9 - cases; 4 - coil; 5 - filter; 6- lid; 7- spring; 8 - core

The nozzle consists of a body 3, lids 6, coils 4 electromagnet, core 8 electromagnet, needle 2 stop valve, body 9 spray nozzles 1 atomizer and filter 5,

When the engine is running, fuel under pressure enters the nozzle through filter 5 and passes to the shut-off valve, which is in the closed state under the action of spring 7.

When an electrical impulse enters the coil winding 4 electromagnet produces a magnetic field that attracts the core 8 and along with it the needle 2 stop valve. At the same time, the hole in the body 9 nozzle opens and pressurized fuel is ejected in atomized form.

After the cessation of the receipt of an electrical impulse in the winding of the electromagnet coil, the magnetic field disappears, and under the action of spring 7, the core 8 electromagnet and needle 2 shut-off valve return to its original position. Hole in the housing 9 nozzle closes and fuel injection from the injector stops.

5. Safety

Safety precautions when caring for the power supply system must be observed. So, when using leaded gasoline, you must be especially careful when handling it, since this gasoline is very poisonous.

When filling the fuel tank, inspecting and cleaning the power system, do not allow gasoline to come into contact with the skin. If leaded gasoline comes into contact with the skin, it should be washed with clean kerosene, and hands should be washed with soap and warm water and wiped dry.

Do not use leaded gasoline for washing parts and hands, as well as suck gasoline through a hose with your mouth when pouring and blow through the fuel lines with your mouth.

Do not allow the engine to operate in a closed room that is not equipped with special ventilation. This can cause poisoning of people in the room with exhaust gases.

During all work on the care of the power supply system, it is imperative to comply with fire safety regulations.

List of used literature

1. Sarbaev V.I. Car maintenance and repair. - Rostov n / a: "Phoenix", 2004.

2. Vakhlamov V.K. Technique of road transport. - M.: "Academy", 2004.

3. Barashkov I.V. brigade organization Maintenance and car repair. - M .: Transport, 1988.

TO category:

Operation device KAMAZ 4310

Purpose, arrangement and operation of the fuel supply system

The engine fuel supply system is designed to place the fuel supply on the vehicle, clean it, spray the fuel and evenly distribute it over the cylinders in accordance with the engine operation order.

The KamAZ-740 engine uses a separate fuel supply system (i.e., fuel pump functions high pressure and injectors are separated). It includes (Fig. 37) fuel tanks, a coarse fuel filter, a fine fuel filter, a low-pressure fuel priming pump *, a manual fuel pump, a high-pressure fuel pump (TNVD) with an all-mode regulator and an automatic fuel injection advance clutch, injectors, high and low pressure fuel lines and instrumentation.

The fuel from the fuel tank, under the action of the vacuum created by the fuel priming pump, is fed through the coarse and fine filters through the low pressure fuel lines to the high pressure fuel pump. In accordance with the order of operation of the engine (1-5-4-2-6-3-7-8), the injection pump supplies fuel at high pressure and in certain portions through the nozzles to the combustion chambers of the engine cylinders. Fuel is sprayed by nozzles. Excess fuel, and with it the air that has entered the system, is discharged into the fuel tank through the bypass valve of the high-pressure fuel pump and the jet valve of the fine filter. Fuel seeping through gap

Rice. 37. Engine fuel supply system:
1 - fuel tank; 2 - fuel line to the coarse filter; 3 - tee; 4 - coarse fuel filter; 5 - drain drain fuel line of injectors of the left row; 6 - nozzle; 7 - fuel supply line to the low pressure pump; 8 - high pressure fuel line; 9 - manual fuel priming pump; 10 - low pressure fuel pump; 11 - fuel line to the fine filter; 12 - high pressure fuel pump; 13 - fuel line to the solenoid valve; 14 - solenoid valve; / 5-drain drain fuel line of injectors of the right row; 16 - torch candle; P - drainage fuel line of the high pressure pump; 18 - fuel fine filter; 19 - fuel supply line to the high pressure pump; 20 - drainage fuel line of the fuel fine filter; 21 - drain fuel line; 22 - distribution valve

Rice. 38. Fuel tank:
1 - bottom; 2 - partition; 3 - body; 4 - drain cock plug; 5 - filling pipe; 6 - plug of the filling pipe; 7 - coupling tape; 8 - tank mounting bracket

Fuel tanks (Fig. 38) are designed to accommodate and store a certain amount of fuel on a vehicle. The KamAZ-4310 car has two tanks with a capacity of 125 liters each. They are located on both sides of the car on the side members of the frame. The tank consists of two halves, stamped from sheet steel and connected by welding; leaded on the inside to prevent corrosion.

There are two partitions inside the tank, which serve to mitigate the hydraulic shocks of the fuel against the walls when the car is moving. The tank is equipped with a filler neck with a retractable pipe, a filter mesh and a sealed lid. In the upper part of the tank, a rheostatic type fuel gauge sensor is installed, a tube that plays the role air valve. In the lower part of the tank there is a suction pipe and a fitting with a cock for draining the sludge. There is a strainer at the end of the intake tube.

The coarse fuel filter (Fig. 39) is designed for preliminary purification of the fuel entering the fuel priming pump. Installed on the left side of the vehicle frame. It consists of a housing, a reflector with a filter mesh, a distributor, a damper, a filter cup, inlet and outlet fittings with gaskets. The glass with the lid is connected with four bolts through a rubber sealing gasket. A drain plug is screwed into the bottom of the glass.

Fuel coming through the inlet fitting from the fuel tank is supplied to the distributor. Large foreign matter and water collect at the bottom of the glass. From the upper part, the fuel is supplied through a strainer to the outlet fitting, and from it to the fuel priming pump.

The fuel fine filter (Fig. 40) is designed for final purification of fuel before it enters the high pressure fuel pump. The filter is installed at the rear of the engine at the highest point in the fuel system. Such an installation ensures the collection of air that has entered the power system and its removal into the fuel tank through the jet valve. The filter consists of a housing

two filter elements, two caps with welded rods, a jet valve, inlet and outlet fittings with seals, sealing elements. The body is cast from aluminum alloy. It has channels for supplying and discharging fuel, a cavity for installing a jet valve and annular grooves for installing caps.

Replaceable cardboard filter elements are made of highly porous ETPZ type cardboard. The mechanical seal of the elements is carried out by upper and lower seals. A tight fit of the elements to the filter housing is ensured by springs mounted on the rods of the caps.

The jet valve is designed to remove air that has entered the power system. It is installed in the filter housing and consists of a cap, valve spring, plug, adjusting washer, sealing washer. The jet valve opens when the pressure in the cavity in front of the valve is 0.025 ... 0.045 MPa (0.25 ... 0.45 kgf / cm2), and at a pressure of 0.22 ± 0.02 MPa (2.2 ± 0.2 kgf / cm2) starts to bypass fuel.

Fuel under pressure from the fuel priming pump fills the internal cavity of the cap and is forced through the filter element, on the surface of which mechanical impurities remain. The purified fuel from the inner cavity of the filter element is supplied to the inlet cavity of the injection pump.

Rice. 39. Coarse fuel filter:
1 - drain plug; 2 - glass; 3 - calmer; 4 - filter mesh; 5 - reflector; 6 - distributor; 7- bolt; 8- flange; 9- sealing ring; 10 - body

The low-pressure fuel priming pump is designed to supply fuel through coarse and fine filters to the inlet cavity of the injection pump. Piston-type pump driven by the eccentric of the camshaft of the high-pressure fuel pump. Supply pressure 0.05…0.1 MPa (0.5…1 kgf/cm2). The pump is installed on the rear cover of the injection pump. The fuel priming pump (Fig. 41, 42) consists of a body, a piston, a piston spring, a piston pusher, a pusher rod, a pusher spring, a rod guide sleeve, an inlet valve, and a pressure valve.

Cast iron pump body. It has channels and cavities for the piston and valves. The cavities under the piston and above the piston are connected by a channel through the delivery valve.

The pusher is designed to transfer force from the camshaft eccentric to the piston. Roller type pusher.

The eccentric of the camshaft of the injection pump through the pusher and the rod informs the pump piston (see Fig. 41) reciprocating motion.

Rice. 40. Fuel fine filter:
1 - body; 2 - bolt; 3 - sealing washer; 4 - cork; 5, 6 - gaskets; 7 - filter element; 8 - cap; 9 - filter element spring; 10 - drain plug; 11 - rod

When the plunger is lowered, the piston moves down under the action of the spring. A vacuum is created in the suction cavity a, the intake valve opens and passes fuel into the over-piston cavity. At the same time, fuel from the sub-piston cavity through the fine filter enters the inlet channels of the high-pressure fuel pump. When the piston moves upwards, the inlet valve closes and fuel from the over-piston cavity through the discharge valve enters the cavity under the piston. When the pressure in the injection line b rises, the piston stops moving down after the pusher, but remains in a position that is determined by the balance of forces from the fuel pressure on one side and the spring force on the other. Thus, the piston does not make a full stroke, but a partial one. Thus, the performance of the pump will be determined by the fuel consumption.

The manual fuel priming pump (see Fig. 42) is designed to fill the system with fuel and remove air from it. The piston type pump is mounted on the fuel-priming pump housing through a sealing copper washer.

The pump consists of a housing, a piston, a cylinder, a piston rod and a handle, a support plate, an inlet valve (common with a fuel priming pump).

Filling and pumping of the system is carried out by moving the handle with the rod up and down. When the handle moves upwards, a vacuum is created in the under-piston space. The inlet valve opens and fuel enters the cavity above the piston of the fuel priming pump. When the handle moves down, the delivery valve of the fuel priming pump opens and fuel under pressure enters the delivery line. Then the process is repeated.

After pumping, the handle must be tightly screwed onto the upper threaded shank of the cylinder. In this case, the piston is pressed against the rubber gasket, sealing the inlet cavity of the fuel priming pump.

Rice. 41. Scheme of operation of the low pressure fuel priming pump and manual fuel priming pump:
1 - pump drive eccentric; 2 - pusher; 3 - piston; l - inlet valve; 5 - hand pump; 6 - discharge valve 4

The high pressure fuel pump (TNVD) is designed to supply metered portions of fuel under high pressure to the engine cylinders in accordance with the order of their operation.

Rice. 42. Fuel priming pump:
1 - pump drive eccentric; 2 - pusher roller; 3 - housing (cylinder) of the pump; 4 - pusher spring; 5 - pusher rod; 6 - stem bushing; 7 - piston; 8 - piston spring; 9 - high pressure pump housing; 10 - inlet valve seat; 11- case of low pressure fuel priming pump; 12 - inlet valve; 13 - valve spring; /4 - manual booster pump; 15 - washer; 16 - plug of the discharge valve; 17 - pressure valve spring; 18 - delivery valve of the low pressure fuel pump

Rice. 43. High pressure fuel pump: 1 - rear cover of the regulator; 2, 3 - drive and intermediate gears of the speed controller; 4 - driven gear of the regulator with a holder for weights; 5 - axis of the load; 6 - cargo; 7-coupling cargo; 8 - lever finger; 9 - corrector; 10 - regulator spring lever; 11 - rail; 12 - rack bushing; 13 - pressure reducing valve; 14 - rail plug; 15 - fuel injection advance clutch; 16 - cam shaft; 17, - pump housing; 18 - pump section

The pump is installed in the collapse of the cylinder block and is driven from the camshaft gear through the pump drive gear. The direction of rotation of the cam shaft from the drive side is right.

The pump consists of a housing, a camshaft (see Fig. 43), eight pump sections, an all-mode speed controller, a fuel injection advance clutch and a fuel pump drive.

The injection pump housing is designed to accommodate pump sections, a camshaft and a speed controller. Cast from aluminum alloy, it has inlet and cut-off channels and cavities for installation and fastening of pump sections, camshaft with bearings, governor drive gears, inlet and outlet fuel fittings. At the rear end of the pump housing, a regulator cover is mounted, in which a low-pressure fuel priming pump with a manual fuel priming pump is located. A fitting with an oil supply pipe is screwed on top of the cover for lubricating parts of the injection pump under pressure. Oil from the pump is drained through a tube connecting the lower opening of the regulator cover with a hole in the collapse of the block. The upper cavity of the injection pump housing is closed with a cover (see Fig. 44), on which the control levers for the speed controller and two protective covers are located fuel sections pump. The cover is mounted on two pins and fastened with bolts, and protective covers - with two screws. At the front end of the pump housing at the outlet of the cut-off channel, a fitting with a ball-type bypass valve is screwed in, maintaining an excess fuel pressure in the pump of 0.06 ... 0.08 MPa (0.6 ... 0.8 kgf / cm2). In the lower part of the pump housing there is a cavity for installing a camshaft.

The camshaft is designed to communicate movement to the plungers of the pump sections and ensure timely fuel supply to the engine cylinders. The cam shaft is made of steel. The working surfaces of the cams and bearing journals are cemented to a depth of 0.7…1.2 mm. Due to the K-shaped design of the pump, the camshaft is shorter and therefore more rigid. The shaft rotates in two tapered bearings, the inner clips of which are pressed onto the shaft journals. The camshaft axial clearance of 0.1 mm is regulated by gaskets installed under the bearing cover. To seal the camshaft in the cover there is a rubber cuff. At the front tapered end of the camshaft, an automatic fuel injection advance clutch is mounted on a segment key. At the rear end of the camshaft, a thrust sleeve, the drive gear of the regulator assembly are mounted, and on the feather key - the flange of the drive gear of the regulator. The flange is made together with the fuel priming pump drive eccentric. The torque from the camshaft to the drive gear of the regulator is transmitted through the flange by means of rubber crackers. When the cam shaft rotates, the force is transmitted to the roller pushers and through the heels of the pushers to the plungers of the pump sections. Each pusher from rotation is fixed with a cracker, the protrusion of which enters the groove of the pump housing. By changing the thickness of the heel, the start of the fuel supply is regulated. When installing a thicker heel, fuel starts to flow earlier.

Rice. 44. Regulator cover:
1 - starting feed regulation bolt; 2 - stop lever; 3 - bol * regulation of the stroke of the stop lever; 4 - bolt limiting the maximum speed; 5 - regulator control lever (fuel pump rail); 6 - bolt limiting the minimum speed; I - work; It - off

The pump section (Fig. 45, a) is a part of the high-pressure fuel pump that doses and supplies fuel to the nozzle. Each pump section consists of a casing, a plunger pair, a rotary sleeve, a plunger spring, a discharge valve, and a pusher.

The section housing has a flange, with which the section is mounted on studs screwed into the pump housing. The holes in the flange for the studs are oval. This allows the pumping section to be rotated to control the uniformity of the fuel supply by individual sections. When turning the section counterclockwise, the cyclic feed increases, clockwise it decreases. The section body has two holes for fuel passage from the channels in the pump to the holes in the plunger bushing (A, B), a hole for installing a pin that fixes the position of the bushing and plunger relative to the section body, and a slot for accommodating the rotary bushing driver.

Plunger pair (Fig. 45, b) - a pump section assembly directly designed for dosing and supplying fuel. The plunger pair includes a plunger sleeve and a plunger. They are a perfect pair. Manufactured from chrome molybdenum steel, hardened and then deep cold treated to stabilize the properties of the material. The working surfaces of the sleeve and plunger are nitrided.

Rice. 45. High pressure fuel pump section:
a - design; b - diagram of the upper part of the plunger pair; A - injection cavity of the fuel pump; B - cut-off cavity; 1 - pump housing; 2- section pusher; 3 - heel of the pusher; 4 - spring: 5, 14 - section plunger; 6, 13 - plunger bushing; 7 - discharge valve; 8 - fitting; 9 - section body; 10 - cut-off edge of the helical groove of the plunger; 11 - rail; 12 - plunger swivel sleeve

The plunger is a movable part of the plunger pair and acts as a piston. The plunger in the upper part has an axial drilling, two spiral grooves made on both sides of the plunger, and a radial drilling connecting the axial drilling and the grooves. The spiral groove is designed to change cyclic feed fuel due to the rotation of the plunger, and hence the groove relative to the cut-off hole of the plunger sleeve. The plunger is rotated relative to the sleeve by the fuel pump rail through the plunger spikes. There is a mark on the outer surface of one spike. When assembling the section, the mark on the plunger spike and the slot in the section body for installing the pivot bushing driver must be on the same side. The presence of the second groove provides hydraulic relief of the plunger from lateral forces. This increases the reliability of the pump section.

The seal between the bushing and the section body is provided by an oil and petrol resistant rubber ring installed in the annular groove of the bushing.

The discharge valve and its seat are made of steel, hardened and processed by deep cold. The valve and seat make up a precision pair, in which the replacement of one part with the same name from another set is not allowed.

The discharge valve is located at the upper end of the sleeve and is pressed against the seat by a spring. The discharge valve seat is pressed against the plunger bushing by the end surface of the fitting through a sealing textolite gasket.

Mushroom type discharge valve with cylindrical guide. A radial hole with a diameter of 0.3 mm is used to adjust the cyclic feed at a camshaft speed of 600 ... 1000 min-1. The adjustment is carried out by increasing the throttling action of the valve during the supply cut-off period, as a result of which the amount of fuel flowing from the high-pressure fuel line to the plunger space is reduced. Unloading of the fuel line from high pressure is carried out by moving the valve guide in the seat channel when landing. The upper part of the guide acts as a piston sucking fuel from the fuel line.

All-mode speed controller. Internal combustion engines must operate in a given steady state (equilibrium) mode, characterized by a constant crankshaft speed, coolant temperature and other parameters. This mode of operation can only be maintained if the engine torque is equal to the moment of resistance to movement. However, during operation, this equality is often violated due to changes in the load or the set mode, so the value of the parameters (speed, etc.) deviates from the specified ones. To restore the disturbed mode of operation of the engine, regulation is applied. Regulation can be carried out manually by acting on the control element (fuel pump rail) or using a special device called an automatic speed controller. Thus, the speed controller is designed to maintain the crankshaft speed set by the driver by automatically changing the cyclic fuel supply depending on the load.

The KamAZ engine is equipped with an all-mode centrifugal regulator speed of direct action. It is located in the collapse of the injection pump housing, and the control is displayed on the pump cover.

The regulator has the following elements (Fig. 46):
- master device;
– sensitive element;
- comparison device;
- actuating mechanism;
- Regulator drive.

The master device includes a regulator control lever, a spring lever, a regulator spring, a regulator lever, a lever with a corrector, speed limit adjusting bolts.

The sensing element includes the governor shaft with weight holder, weights with rollers, thrust bearing, clutch regulator with a fifth.

The comparing device includes the load clutch lever, with the help of which the movement of the regulator clutch is transmitted to the actuator (rails).

The actuator includes fuel pump racks, rack lever (differential lever).

The regulator drive includes the drive gear of the regulator, the intermediate gear 6, the regulator gear, made in one piece with the shaft of the all-mode regulator.

To stop the engine, there is a device that includes a stop lever, a stop lever spring, a starting spring, a stop bolt for adjusting the stroke of the stop lever, and a bolt for adjusting the starting feed.

Fuel supply is controlled by foot and hand drives.

The rotation of the drive gear of the regulator is transmitted through rubber crackers. Crackers, being elastic elements, dampen vibrations associated with the uneven rotation of the shaft. The reduction of high-frequency oscillations leads to a decrease in the wear of the joints of the main parts of the regulator. From the drive gear, rotation is transmitted to the driven gear through the intermediate gear.

The driven gear is made integral with the weight holder, which rotates on two ball bearings. When the holder rotates, the loads diverge under the action of centrifugal forces and the clutch is moved through the thrust bearing, the clutch, resting against the pin, in turn, moves the load clutch lever.

The cargo clutch lever is attached at one end to the axis of the regulator levers, the other end is connected to the fuel pump rail through a pin. The regulator lever is also attached to the axle, the other end of which moves all the way into the fuel supply adjusting bolt. The load clutch lever acts on the regulator lever through the corrector. The regulator control lever is rigidly connected to the regulator spring lever.

Rice. 46. ​​Speed ​​controller:
1 - back cover; 2 - nut; 3 - washer; 4 - bearing; 5 - adjusting gasket; 6 - intermediate gear; 7 - gasket for the rear cover of the regulator; 8 - retaining ring; 9- holder of goods; 10 - axis of the load; 11 - thrust bearing; 12 - clutch; 13 - cargo; 14 - finger; 15 - corrector; 16 - return spring of the stop lever; 17 - bolt; 18 - bushing; 19 - ring; 20 - regulator spring lever; 21 - drive gear: 22 - drive gear cracker; 23 - drive gear flange; 24 - adjusting bolt for fuel supply; 25 - starting lever

The start spring is connected to the start spring lever and the rack lever. The rails, in turn, are connected to the rotary bushings of the pump sections. The decrease in the degree of regulator unevenness at low crankshaft speeds is achieved by changing the shoulder for applying the force of the regulator spring to the regulator lever.

An increase in the sensitivity of the regulator is ensured by high-quality processing of the rubbing surfaces of the moving parts of the regulator and pump, their reliable lubrication and increase angular velocity rotation of the coupling of goods twice in relation to the cam shaft of the pump due to gear ratio governor drive gears.

The engine is equipped with a speed regulator with a smoke corrector, which is built into the load clutch lever. The corrector, by reducing the fuel supply, makes it possible to reduce engine smoke at a low crankshaft speed (1000 ... 1400 min).

Given speed mode engine operation is set by the regulator control lever, which rotates and increases its tension through the spring lever. Under the influence of this spring, the lever through the corrector acts on the clutch lever, which moves the rails associated with the rotary bushings of the plungers in the direction of increasing the fuel supply. The crankshaft speed increases.

The centrifugal force of the rotating weights is transmitted through the thrust bearing, the clutch and the cargo clutch lever to the fuel pump rail, which is connected to the other rail through the differential lever. Moving rails centrifugal force cargo causes a decrease in fuel supply.

The adjustable speed mode depends on the ratio of the regulator spring force and the centrifugal force of the weights at the set crankshaft speed. The more the regulator spring is stretched, the higher the speed, its weights can change the position of the regulator lever in the direction of limiting the supply of fuel to the engine cylinders. A stable mode of operation of the engine will be in the event that the centrifugal force of the loads is equal to the force of the regulator spring. Each position of the regulator control lever corresponds to a certain speed of the crankshaft.

At a given position of the regulator control lever, in the event of a decrease in the load on the engine (downhill movement), the rotational speed of the crankshaft, and hence the governor drive shaft, increases. In this case, the centrifugal force of the loads increases and they diverge.

The weights act on the thrust bearing and, overcoming the spring force set by the driver, turn the regulator lever and move the rails in the direction of decreasing the supply until the fuel supply is established, corresponding to the driving conditions. The set engine speed will be restored.

With an increase in load (lifting movement), the rotational speed, and, consequently, the centrifugal forces of the loads decrease. The force of the spring through the levers 31, 32, acting on the clutch, moves it and brings the loads together. In this case, the rails move in the direction of increasing the fuel supply until the crankshaft speed reaches the value specified by the driving conditions.

Thus, the all-mode controller supports any driving mode set by the driver.

When the engine is running at rated speed and full fuel supply, the L-shaped lever 31 rests against the adjusting bolt 24. If the load increases, the speed of the crankshaft and the governor shaft begins to decrease. In this case, the balance between the force of the regulator spring and the centrifugal force of its weights, reduced to the axis of the regulator lever, is disturbed. And due to the excess force of the corrector spring, the corrector plunger moves the clutch lever in the direction of increasing the fuel supply.

Thus, the speed controller not only maintains the engine at a given mode, but also ensures that additional portions of fuel are supplied to the cylinders when operating with an overload.

Turning off the fuel supply (stopping the engine) is carried out by turning the stop lever all the way into the stop lever stroke adjustment bolt. The lever, overcoming the force of the spring (installed on the lever), will turn the regulator lever by the finger. The rails move until the fuel supply is completely turned off. The engine stops. After stopping, the stop lever under the action of the return spring returns to the WORK position, and the starting spring through the rail lever will return the fuel pump rails to the side of the starting fuel supply (195 ... 210 mm3 / cycle).

Automatic fuel injection advance clutch. In diesel engines, fuel is injected into the air charge. The fuel cannot instantly ignite, but must go through a preparatory phase, during which the fuel is mixed with air and evaporated. When the auto-ignition temperature is reached, the mixture ignites and quickly begins to burn. This period is accompanied by a sharp increase in pressure and an increase in temperature. In order to get the most power, it is necessary that the combustion of the fuel occurs in a minimum volume, that is, when the piston is at TDC. To this end, fuel is always injected even before the piston reaches TDC.

The angle that determines the position of the crankshaft relative to TDC at the time the fuel injection starts is called the fuel injection advance angle. The design of the KamAZ diesel fuel pump drive provides fuel injection 18 ° before the piston arrives at TDC during the compression stroke.

As the engine speed increases, the time for the preparatory process decreases and ignition can begin after TDC, which will lead to a decrease in useful work. In order to receive the greatest work with an increase in the crankshaft speed, the fuel must be injected earlier, i.e., increase the fuel injection advance angle. This can be done by turning the camshaft in the direction of its rotation relative to the drive. For this purpose, a fuel injection advance clutch is installed between the camshaft of the injection pump and its drive. The use of a clutch significantly improves the starting qualities of a diesel engine and its efficiency at various speeds.

Thus, the fuel injection advance clutch is designed to change the timing of the start of fuel supply depending on the speed of the engine crankshaft.

On KamAZ-740, an automatic centrifugal type clutch of direct action is used. The fuel injection advance angle adjustment range is 18…28°.

The coupling is installed on the conical end of the injection pump camshaft on a segment key and fastened with a ring nut with a spring washer. It changes the moment of fuel injection due to the additional rotation of the camshaft of the pump during engine operation relative to the drive shaft of the high pressure pump (Fig. 47).

The automatic clutch (Fig. 47, a) consists of a housing, a driving half-coupling with fingers, a driven half-coupling with axes of loads, loads with pins, spacers, spring cups, springs, shims and thrust washers.

The clutch housing is cast iron. At the front end there are two threaded holes for filling the coupling with engine oil. The housing is screwed onto the driven coupling half and locked. The seal between the body and the drive half-coupling and the hub of the driven half-coupling is carried out by two rubber cuffs, and between the body and the driven half-coupling - by a ring made of oil and petrol resistant rubber.

The leading half-coupling is mounted on the hub of the driven one and can be rotated relative to it. The clutch is driven by drive shaft HPFP (Fig. 47, b). In the leading coupling half, two fingers are made, on which spacers are installed. The spacer rests with one end against the load pin, and with the other end slides along the profile ledge of the load.

The driven half-coupling is installed on the conical part of the injection pump camshaft. Two axles of weights are pressed into the coupling half and a mark is applied to set the fuel injection advance angle. The loads swing on the axes in a plane perpendicular to the axis of rotation of the coupling. The weights have profile projections and fingers. The forces of the springs act on the loads.

Rice. 47. Automatic fuel injection advance clutch:
a - automatic clutch: 1 - leading half-coupling; 2, 4 - cuffs; 3 - bushing of the leading coupling half; 5 - body; 6 - adjusting gasket; 7 - a glass of a spring; 8 - spring; 9, 15 - washers; 10 - ring; 11 - load with a finger; 12 - pro-rate with an axis; 13 - driven coupling half; 14 - sealing ring; 16 - cargo axis
b - drive of the automatic clutch and its installation according to the marks; 1 - mark on the rear flange of the coupling half; II - mark on the injection advance clutch; III - mark on the fuel pump housing; 1 - automatic injection advance clutch; 2 - driven coupling half of the drive; 3 - bolt; 4 - drive coupling half flange

At the minimum crankshaft speed, the centrifugal force of the weights is small and they are held by the force of the springs. In this case, the distance between the axes of the loads (on the driven half-coupling) and the pins of the leading half-coupling will be maximum. The driven part of the clutch lags behind the leading part by the maximum angle. Therefore, the fuel injection advance angle will be minimal.

With an increase in the frequency of rotation of the crankshaft, the loads under the action of centrifugal forces, overcoming the resistance of the springs, diverge. The spacers slide along the profile ledges of the weights and rotate around the axes of the weight fingers. Since the fingers of the leading coupling half enter the spacer hole, the divergence of the loads leads to the fact that the distance between the fingers of the leading half-coupling and the axes of the loads will decrease, i.e., the lagging angle of the driven half-coupling from the leading one will also decrease. The driven coupling half rotates relative to the leading one at a certain angle in the direction of rotation of the coupling (the direction of rotation is right). The rotation of the driven half-coupling causes the camshaft of the high-pressure fuel pump to turn, which leads to earlier fuel injection relative to TDC.

With a decrease in the frequency of rotation of the engine crankshaft, the centrifugal force of the loads decreases and they begin to converge under the action of the spring. The driven coupling half rotates relative to the leading one in the direction opposite to rotation, reducing the fuel injection advance angle.

The nozzle is designed to inject fuel into the engine cylinders, spray and distribute it throughout the volume of the combustion chamber. Nozzles are installed on the KamAZ-740 engine closed type with multi-hole atomizer and hydraulically controlled needle. The pressure of the beginning of the needle lift is 20 ... 22.7 MPa (200 ... 227 kgf / cm2). The nozzle is installed in the socket of the cylinder head and fastened with a bracket. The nozzle is sealed in the cylinder head seat in the upper zone with a rubber ring 7 (Fig. 48), in the lower zone - with a cone of the atomizer nut and a copper washer. The nozzle consists of a body 6, atomizer nut 2, atomizer, spacer 3, rod 5, spring, support and adjusting washers and a nozzle fitting with a filter.

The nozzle body is made of steel. Threaded holes are made in the upper part of the housing for installing a fitting with a filter and a drain pipe fitting (see Fig. 37). The housing has a fuel supply channel and a channel for removing fuel seeping into the internal cavity of the housing.

Rice. 48. Nozzle:
a - with adjusting washers; b - with external adjustment; 1 - sprayer body; 2 - atomizer nut; 3 - spacer; 4 - locating pins; 5 - rod; 6 - body; 7 and 16 - sealing rings; 8 - fitting; 9 - filter; 10 - sealing sleeve; 11 and 12 - adjusting washers; 13 - spring; 14 - spray needle; 15 - spring stop;. 17 - eccentric

The atomizer nut is designed to connect the atomizer to the nozzle body.

Atomizer - a nozzle assembly that atomizes and forms jets of injected fuel.

The atomizer body and needle make up a precision pair in which the replacement of any one part is not allowed. The body is made of chromium-nickel-vanadium steel and subjected to special heat treatment (carburizing, hardening followed by deep cold treatment) to obtain high hardness and wear resistance of working surfaces. The atomizer body has an annular groove and a channel for supplying fuel to the cavity of the atomizer body, as well as two holes for pins that secure the atomizer body relative to the nozzle body. Four nozzle holes are made in the lower part of the housing. Their diameter is 0.3 mm. To ensure uniform distribution of fuel throughout the volume of the combustion chamber, the nozzle holes are made at different angles. This is due to the fact that the nozzle relative to the axis of the cylinder is located at an angle of 21°.

The atomizer needle is designed to close the atomizing holes after fuel injection. The needle is made of tool steel and also subjected to special processing. In order to increase the service life of the atomizer and needle, the locking part of the needle is made two-conical.

The spacer is designed to fix the atomizer body relative to the nozzle body.

Rod - a movable part of the nozzle, designed to transfer force from the nozzle spring to the spray needle.

The nozzle spring is designed to provide required pressure lifting the needle. The tension of the spring is carried out by adjusting washers, which are installed between the support washer and the end face of the inner cavity of the nozzle body. A change in the thickness of the washers by 0.05 mm leads to a change in the pressure at the beginning of the needle lift by 0.3 ... 0.35 MPa (3 ... 3.5 kgf / cm2). In injectors of the second type (Fig. 48.6), the spring is adjusted by turning the eccentric 17.

Joint operation of the pump section of the high pressure fuel pump and the nozzle. The driver, acting on the fuel supply pedal through the system of rods and levers, the setting device of the all-mode regulator, fuel pump rails, rotary bushings, turns the plunger. This sets a certain distance between the cut-off hole and the cut-off edge of the helical groove, providing a certain cyclic fuel supply.

The plunger under the action of the camshaft performs a reciprocating motion. When the plunger moves down, the discharge valve, loaded with a spring, is closed and a vacuum is created in the cavity above the plunger.

After the upper edge of the plunger opens the inlet in the bushing, fuel from the fuel channel at a pressure of 0.05 ... 0.1 MPa (0.5 ... 1 kgf / cm2) from the fuel priming pump enters the space above the plunger (Fig. 49, a).

At the beginning of the upward movement (Fig. 49, b) of the plunger, part of the fuel is forced out through the inlet and cut-off openings of the bushing into the fuel supply channel. The moment when the fuel supply starts is determined by the moment when the inlet hole of the bushing is closed by the upper edge of the plunger. From this moment, when the plunger moves upwards, the fuel is compressed in the cavity above the plunger, and after reaching the pressure at which the discharge valve opens, in the high-pressure pipeline and the nozzle.

Rice. 49. Scheme of operation of the pump section:
a - filling the supra-plunger cavity; b - the beginning of the feed; c - end of feed

When the fuel pressure in the specified cavity becomes more than 20 MPa (200 kgf/cm2), the atomizer needle rises and opens fuel access to the atomizer nozzle holes, through which high-pressure fuel is injected into the combustion chamber.

When the plunger moves upwards, when the cut-off edge of the helical groove reaches the level of the cut-off hole, the moment of the end of the fuel supply comes (Fig. 49, a). With further movement of the plunger upwards, the over-plunger cavity communicates with the cut-off channel through a vertical channel, a diametrical channel, a helical groove. As a result, the pressure in the cavity above the plunger drops, the discharge valve, under the action of the spring and the fuel pressure in the pump fitting, sits in the saddle and the fuel supply to the nozzle stops, although the plunger can still move up. With a decrease in pressure in the fuel line below the force created by the spring, the atomizer needle goes down under the action of the spring and blocks the access of fuel to the nozzle openings of the atomizer, thereby stopping the fuel supply to the engine cylinder. The fuel that has leaked through the gap in the pair of the needle - the atomizer body is discharged through the channel in the nozzle body to the drainage pipeline and further to the fuel tank.

The change in the cyclic feed is controlled by turning the plunger. This sets different distances between the cut-off edge of the plunger and the lower edge of the cut-off hole. The plunger is turned by a rail moving under the action of an all-mode regulator.

The angular interval between the beginning of the delivery of successively operating sections of the fuel pump is provided by the relative turn of the profiles of the cams of these sections on the high-pressure fuel pump shaft.

It is a whole complex of devices. The main task is not just to supply fuel to injection nozzles, as well as high-pressure fuel supply. The pressure is necessary for high-precision metered injection into the combustion chamber of the cylinder. The diesel power system performs the following important functions:

• dosing of a strictly defined amount of fuel, taking into account the load on the engine in one or another mode of its operation;
• efficient fuel injection in a given period of time with a certain intensity;
• atomization and the most uniform distribution of fuel throughout the volume of the combustion chamber in the cylinders of a diesel engine;
• pre-filtration of fuel before supplying fuel to the pumps of the power system and injector nozzles;

Read in this article

Features of diesel fuel

Most of the requirements for the diesel engine power system are put forward taking into account the fact that diesel fuel has a number of specific features. Fuel of this kind is a mixture of kerosene and gas oil solar fractions. Diesel fuel is obtained after distillation of gasoline is realized from oil.

Diesel fuel has a number of properties, the main of which is considered to be the self-ignition index, which is estimated by the cetane number. Types for sale diesel fuel have cetane number at around 45-50. For modern diesel units, the best fuel is fuel with a high cetane number.

The power supply system of a diesel internal combustion engine ensures the supply of well-purified diesel fuel to the cylinders, the high-pressure fuel pump compresses the fuel to high pressure, and the nozzle delivers it in a form sprayed into the smallest particles into the combustion chamber. Atomized diesel fuel is mixed with hot (700–900 °C) air, which is heated to this temperature from high compression in cylinders (3–5 MPa) and ignites spontaneously.

Please note that the working mixture in a diesel engine is not ignited by a separate device, but ignites independently from contact with heated air under pressure. This feature greatly distinguishes a diesel engine from gasoline counterparts.

Diesel fuel also has a higher density compared to gasoline, and also has better lubricity. Not less than important characteristic viscosity, pour point and purity of diesel fuel. The pour point allows you to divide the fuel into three basic grades of fuel:.

Scheme of the device of the diesel engine power supply system

Supply system diesel engine consists of the following basic elements:

1. fuel tank;
2. coarse filters for diesel fuel;
3. fuel fine filters;
4. fuel pump;
5. high pressure fuel pump (TNVD);
6. injection nozzles;
7. low pressure pipeline;
8. high pressure line;
9. air filter;

Additional elements partially become electric pumps, exhaust gases, particulate filters, mufflers, etc. Power system diesel internal combustion engines It is customary to divide into two groups of fuel equipment:

• diesel equipment for fuel supply (fuel supply);
• diesel equipment for air supply (air supply);

Fuel supply equipment may have a different device, but today the most common system is a divided type. In such a system, the high pressure fuel pump (TNFP) and the injectors are implemented as separate devices. Fuel is supplied to the diesel engine through high and low pressure lines.

Diesel fuel is stored, filtered and supplied to the injection pump at low pressure through a low pressure line. In the highway high injection pump pressure raises the pressure in the system to supply and inject a strictly defined amount of fuel into the working combustion chamber of a diesel engine at a given moment.

There are two pumps in the diesel power system at once:

• fuel pump;
• high pressure fuel pump;

The fuel priming pump provides fuel supply from the fuel tank, pumps fuel through the coarse and fine filters. The pressure that the fuel priming pump creates allows fuel to be supplied through the low pressure fuel line to the high pressure fuel pump.

The injection pump supplies fuel to the injectors under high pressure. The supply occurs in accordance with the order of operation of the diesel engine cylinders. The high pressure fuel pump has a certain number of identical sections. Each of these sections of the injection pump corresponds to a specific cylinder of a diesel engine.

There is also a single-type diesel engine power supply system and is used on two-stroke diesel engines. In such a system, the high-pressure fuel pump and injector are combined in one device called a pump-injector.

These motors work hard and noisy, have a short service life. In the design of their power supply system, there are no high-pressure fuel lines. Specified ICE type is not widely distributed.

Let's return to the mass design of the diesel engine. Diesel injectors are located in the cylinder head () of the diesel engine. Their main task is to accurately atomize the fuel in the combustion chamber of the engine. The fuel priming pump delivers a large amount of fuel to the injection pump. The resulting excess fuel and the air entering the fuel supply system are returned to the fuel tank through special pipelines called drainage.

Injection diesel injectors are of two types:

• closed-type diesel nozzle;
• diesel nozzle of open type;

Four stroke diesel engines Predominantly, closed-type nozzles are obtained. In such devices, the nozzle nozzles, which are a hole, are closed with a special shut-off needle.

It turns out that the internal cavity located inside the body of the injector nozzles communicates with the combustion chamber only during the opening of the nozzle and at the moment of diesel fuel injection.

A key element in the design of the nozzle is the atomizer. The atomizer receives from one to a whole group of nozzle holes. It is these holes that form the fuel jet at the moment of injection. The shape of the torch depends on their number and location, as well as throughput nozzles.

Turbo diesel power system

Airing the diesel fuel system: signs of malfunction and diagnostics. How to independently find a place for air leakage, ways to solve the problem.

The design of a high pressure diesel fuel pump, potential malfunctions, scheme and principle of operation using the example of a fuel supply system device.