There are more and more vehicles with automatic transmission every year. And, if here - in Russia and the CIS - "mechanics" still continues to prevail over "automatic", then in the West, cars with automatic transmission are now in the vast majority. This is not surprising if we take into account the undeniable advantages of automatic transmissions: simplification of driving, consistently smooth transitions from one gear to another, protection of the engine from overloads, etc. adverse operating conditions, increasing driver comfort while driving. As for the shortcomings of this transmission option, modern automatic transmissions, as they improve, gradually get rid of them, make them insignificant. In this publication - about the device of the "automatic" box and all its pluses / minuses in work.
An automatic transmission is a type of transmission that provides automatic, without direct driver intervention, the choice of gear ratio that best suits the current driving conditions of the vehicle. The variator does not apply to automatic transmission and is allocated to a separate (stepless) class of transmissions. Because the variator makes changes in gear ratios smoothly, without any fixed gear stages at all.
The idea of automating gear shifting, saving the driver from having to frequently depress the clutch pedal and “work” with the gear lever, is not new. It began to be introduced and perfected at the dawn of the automotive era: at the beginning of the twentieth century. Moreover, it is impossible to name any particular person or company as the sole creator of an automatic transmission: three initially independent lines of development led to the emergence of the classic, now widely used hydromechanical automatic transmission, which eventually merged into a single design.
One of the main mechanisms of the automatic gearbox is the planetary gear set. The first mass-produced car equipped with a planetary gearbox was produced back in 1908, and it was the Ford T. Although in general that gearbox was not yet fully automatic (the driver of the Ford T was required to press two foot pedals, the first of which shifted from lower to higher gear, and the second included reverse), it already made it possible to significantly simplify control, according to compared to conventional gearboxes of those years, without synchronizers.
The second important point in the development of the technology of future automatic transmissions is the transfer of clutch control from the driver to a servo drive, embodied in the 30s of the twentieth century by General Motors. These gearboxes were called semi-automatic. The first fully automatic gearbox was the Kotal planetary electromechanical gearbox introduced into production in the 1930s. It was installed on French cars of the now forgotten Delage and Delaye brands (they existed until 1953 and 1954, respectively).
The car "Deljazh D8" is a premium class of the pre-war era.
Other auto manufacturers in Europe also developed similar clutch and band systems. Soon, similar automatic transmissions were implemented in cars of several more German and British brands, the famous and now living of which is the Maybach.
Specialists from another well-known company, the American Chrysler, have gone further than other automakers by introducing hydraulic elements into the design of the gearbox, which replaced servo drives and electromechanical controls. Chrysler engineers developed the first ever torque converter and fluid clutch, which are now included in every automatic transmission. And the first ever hydromechanical automatic transmission, similar in design to the modern one, was introduced on production cars by the General Motors Corporation.
Automatic transmissions of those years were very expensive and technically complex mechanisms. In addition, not always distinguished by reliable and durable work. They could look advantageous only in the era of non-synchronized manual transmissions, driving a car with which was quite hard work, requiring a well-developed skill from the driver. When mechanical gearboxes with synchronizers became widespread, automatic transmissions of that level were not much better than them in terms of convenience and comfort. While manual transmissions with synchronizers had much less complexity and high cost.
In the late 1980s/1990s, all major automakers were computerizing their engine management systems. Systems similar to them began to be used to control the switching of speeds. Whereas previous solutions used only hydraulics and mechanical valves, now computer-controlled solenoids began to control fluid flows. This made shifting smoother and more comfortable, improved economy and increased transmission efficiency.
In addition, some cars were introduced "sports" and other additional modes of operation, the ability to manually control the gearbox ("Tiptronic", etc. systems). The first five- and more-speed automatic transmissions appeared. The improvement of consumables made it possible on many automatic transmissions to cancel the oil change procedure during the operation of the car, since the resource of the oil poured into its crankcase at the factory became comparable to the resource of the gearbox itself.
The design of the automatic transmission
A modern automatic transmission, or "hydromechanical transmission", consists of:
- torque converter (aka “hydrodynamic transformer, gas turbine engine”);
- planetary mechanism for automatic gear shifting; brake band, rear and front clutches - devices that directly change gears;
- control device (assembly consisting of a pump, valve box and oil collector).
A torque converter is needed to transmit torque from the power unit to the elements of an automatic transmission. It is located between the gearbox and the motor, and thus performs the function of a clutch. The torque converter is filled with a working fluid that captures and transfers engine energy to the oil pump, located directly in the box.
The torque converter consists of large wheels with blades immersed in a special oil. The transmission of torque is not carried out by a mechanical device, but by means of oil flows and their pressure. Inside the torque converter there are a pair of vane machines - a centripetal turbine and a centrifugal pump, and between them - a reactor, which is responsible for smooth and stable changes in torque on the drives to the wheels of the vehicle. So, the torque converter does not come into contact with either the driver or the clutch (it “is” the clutch itself).
The pump wheel is connected to the engine crankshaft, and the turbine wheel is connected to the transmission. When the pump wheel rotates, the oil flows thrown off by it spin the turbine wheel. So that the torque can be changed over a wide range, a reactor wheel is provided between the pump and turbine wheels. Which, depending on the mode of movement of the car, can be either stationary or rotate. When the reactor is stationary, it increases the flow rate of the working fluid circulating between the wheels. The higher the speed of the oil, the greater the effect it has on the turbine wheel. Thus, the moment on the turbine wheel increases, i.e. the device "transforms" it.
But the torque converter cannot convert the speed of rotation and the transmitted torque within all required limits. Yes, and to provide movement in reverse, he is also not in force. To expand these capabilities, a set of separate planetary gears with different gear ratios is attached to it. Like several single-stage gearboxes assembled in one case.
The planetary gear is a mechanical system consisting of several satellite gears that rotate around a central gear. The satellites are fixed together with the help of a carrier circle. The outer ring gear is internally meshed with the planetary gears. The satellites fixed on the carrier rotate around the central gear, like the planets around the Sun (hence the name of the mechanism - “planetary gear”), the outer gear rotates around the satellites. Different gear ratios are achieved by fixing different parts relative to each other.
Brake band, rear and front clutch - directly change gears from one to another. The brake is a mechanism that blocks the elements of the planetary gear set on the fixed body of the automatic transmission. The friction clutch blocks the moving elements of the planetary gear set among themselves.
Automatic transmission control systems are of 2 types: hydraulic and electronic. Hydraulic systems are used on obsolete or budget models, and are gradually being phased out. And all modern automatic boxes are electronically controlled.
The life support device for any control system can be called an oil pump. Its drive is carried out directly from the crankshaft of the engine. The oil pump creates and maintains a constant pressure in the hydraulic system, regardless of the engine speed and engine loads. If the pressure deviates from the nominal value, the operation of the automatic transmission is disrupted due to the fact that the gear shift actuators are controlled by pressure.
The shift point is determined by vehicle speed and engine load. To do this, a pair of sensors is provided in the hydraulic control system: a high-speed regulator and a throttle valve, or modulator. A high-speed pressure regulator or hydraulic speed sensor is installed on the output shaft of the automatic transmission.
The faster the vehicle travels, the more the valve opens, and the greater the pressure of the transmission fluid passing through this valve becomes. Designed to determine the load on the engine, the throttle valve is connected by a cable either to the throttle valve (if we are talking about a gasoline engine) or to the high pressure fuel pump lever (in a diesel engine).
In some cars, not a cable is used to supply pressure to the throttle valve, but a vacuum modulator, which is activated by a vacuum in the intake manifold (the vacuum decreases as the load on the engine increases). Thus, these valves create such pressures that will be proportional to the speed of the vehicle and the workload of its engine. The ratio of these pressures and allows you to determine the moments of gear shifting and blocking of the torque converter.
In the "catching the moment" of the gear shift, the range selection valve is also involved, which is connected to the automatic transmission selector lever and, depending on its position, allows or prohibits the inclusion of certain gears. The resulting pressure created by the throttle valve and the speed regulator causes the corresponding switching valve to actuate. Moreover, if the car accelerates quickly, then the control system will turn on the higher gear later than when accelerating calmly and evenly.
How it's done? The changeover valve is under oil pressure from the high-speed pressure regulator on one side, and from the throttle valve on the other. If the machine is accelerating slowly, then the pressure from the hydraulic speed valve builds up, which causes the shift valve to open. Since the accelerator pedal is not fully depressed, the throttle valve does not create much pressure on the shift valve. If the car accelerates quickly, then the throttle valve creates more pressure on the shift valve, and prevents it from opening. To overcome this opposition, the pressure from the high-speed pressure regulator must exceed the pressure from the throttle valve. But this will happen when the car reaches a higher speed than it does when accelerating slowly.
Each shift valve corresponds to a certain level of pressure: the faster the car moves, the higher the gear will be engaged. The valve block is a system of channels with valves and plungers located in them. The switching valves supply hydraulic pressure to the actuators: clutches and brake bands, through which the various elements of the planetary gear are blocked and, consequently, the switching on (off) of various gears.
Electronic control system just like hydraulic, it uses 2 main parameters for operation. This is the speed of the car and the load on its engine. But to determine these parameters, not mechanical, but electronic sensors are used. The main ones are working sensors: speed at the input of the gearbox; speed at the output of the gearbox; working fluid temperature; selector lever position; accelerator pedal position. In addition, the control unit of the "automatic" box receives additional information from the engine control unit, and from other electronic systems of the car (in particular, from ABS - anti-lock braking system).
This allows you to more accurately determine the moments of need for switching or locking the torque converter than in a conventional automatic transmission. Based on the nature of the change in speed for a given engine load, an electronic gearshift program can easily and instantly calculate the force of resistance to vehicle movement and, if necessary, adjust: introduce appropriate amendments into the shifting algorithm. For example, later include higher gears on a fully loaded vehicle.
In other respects, automatic transmissions with electronic control, just like conventional, "not burdened with electronics" hydromechanical gearboxes, use hydraulics to engage clutches and brake bands. However, with them, each hydraulic circuit is controlled by a solenoid valve, not a hydraulic valve.
Before the start of the movement, the pump wheel rotates, the reactor and turbine wheels remain stationary. The reactor wheel is fixed on the shaft by means of an overrunning clutch, and therefore it can only rotate in one direction. When the driver turns on the gear, presses the gas pedal, the engine speed increases, the pump wheel picks up speed and the turbine wheel spins with oil flows.
The oil thrown back by the turbine wheel falls on the fixed blades of the reactor, which additionally “twist” the flow of this liquid, increasing its kinetic energy, and direct it to the blades of the pump wheel. Thus, with the help of the reactor, the torque increases, which is what is required for the vehicle gaining acceleration. When the car accelerates and begins to move at a constant speed, the pump and turbine wheels rotate at approximately the same speed. Moreover, the oil flow from the turbine wheel enters the reactor blades from the other side, due to which the reactor begins to rotate. There is no increase in torque, and the torque converter goes into a uniform fluid coupling mode. If the resistance to the movement of the car began to increase (for example, the car began to go uphill), then the speed of rotation of the driving wheels, and, accordingly, the turbine wheel, falls. In this case, the oil flows again slow down the reactor - and the torque increases. Thus, automatic torque control is performed, depending on changes in the driving mode of the vehicle.
The absence of a rigid connection in the torque converter has both advantages and disadvantages. The advantages are that the torque changes smoothly and steplessly, torsional vibrations and jerks transmitted from the engine to the transmission are damped. The disadvantages are, first of all, in the low efficiency, since part of the useful energy is simply lost when the oil liquid is “shoveled” and is spent on driving the automatic transmission pump, which ultimately leads to an increase in fuel consumption.
But to smooth this shortcoming in the torque converters of modern automatic transmissions, a blocking mode is used. In the steady state of motion in higher gears, the mechanical blocking of the torque converter wheels is automatically activated, that is, it begins to perform the function of a conventional classic clutch mechanism. This ensures a rigid direct connection of the engine with the drive wheels, as in a mechanical transmission. On some automatic transmissions, the inclusion of the lock mode is also provided for in lower gears too. The movement with blocking is the most economical mode of operation of the “automatic” box. And when the load on the drive wheels increases, the lock is automatically turned off.
During the operation of the torque converter, a significant heating of the working fluid occurs, which is why the design of automatic transmissions provides for a cooling system with a radiator, which is either built into the engine radiator or installed separately.
Any modern “automatic” box has the following mandatory provisions on the cab selector lever:
- P - parking, or parking lock: blocking the drive wheels (does not interact with the parking brake). Similarly, as in the "mechanics" the car is left "at speed" when parked;
- R - reverse, reverse gear (it was always forbidden to activate it at the moment the car was moving, and then a corresponding lock was provided in the design);
- N - neutral, neutral gear mode (activated during a short stop or when towing);
- D - drive, forward movement (in this mode, the entire gear ratio of the box will be involved, sometimes two higher gears are cut off).
And it may also have some additional, auxiliary or advanced modes. In particular:
- L - "downshift", activation of the low gear mode (slow speed) for the purpose of movement in difficult road or off-road conditions;
- O/D - overdrive. Mode of economy and measured movement (whenever possible, the “automatic” box switches to the top);
- D3 (O / D OFF) - deactivation of the highest stage for active driving. It is activated by braking by the power unit;
- S - gears spin up to maximum speed. There may be the possibility of manual control of the box.
- The automatic transmission may also have a special button that prohibits shifting to a higher gear when overtaking.
Advantages and disadvantages automatic boxes
As already noted, the significant advantages of automatic transmissions, compared with mechanical ones, are: the simplicity and comfort of driving a vehicle for the driver: you do not need to squeeze the clutch, you also need to “work” with the gear lever. This is especially true when traveling around the city, which, in the end, make up the lion's share of the car's mileage.
Gear shifts on the "automatic" are smoother and more uniform, which helps protect the engine and the leading components of the car from overloads. There are no consumable parts (for example, a clutch disc or a cable), and therefore it is more difficult to disable the automatic transmission, in this sense. In general, the resource of many modern automatic transmissions exceeds the resource of manual transmissions.
The disadvantages of automatic transmissions include a more expensive and complex design than manual transmissions; the complexity of repair and its high cost, lower efficiency, worse dynamics and increased fuel consumption compared to manual transmission. Although, the improved electronics of the 21st century automatic gearboxes cope with the right choice of torque no worse than an experienced driver. Modern automatic transmissions are often equipped with additional modes that allow you to adapt to a specific driving style - from calm to "frisky".
A serious disadvantage of automatic gearboxes is the impossibility of the most accurate and safe gear shifting in extreme conditions - for example, in difficult overtaking; at the exit from a snowdrift or serious mud, by quickly shifting reverse and first gear (“in buildup”), if necessary, start the engine “with a pusher”. It must be admitted that automatic transmissions are ideal, mainly for ordinary trips without emergency situations. First of all - on city roads. “Automatic” boxes are not very suitable for “sports driving” either (acceleration dynamics lag behind “mechanics” in conjunction with an “advanced” driver) and for off-road rallying (it can’t always perfectly adapt to changing driving conditions).
As for fuel consumption, in any case, an automatic transmission will have more than a mechanical one. However, if earlier this figure was 10-15%, then in modern cars it has dropped to insignificant levels.
In general, the use of electronics has significantly expanded the capabilities of automatic transmissions. They received various additional modes of operation: such as economical, sports, winter.
The sharp increase in the prevalence of “automatic” boxes was caused by the appearance of the “Autostick” mode, which allows the driver, if desired, to independently select the desired gear. Each manufacturer gave this type of automatic transmission its own name: "Audi" - "Tiptronic", "BMW" - "Steptronic", etc.
Thanks to advanced electronics in modern automatic transmissions, the possibility of their “self-improvement” has also become available. That is, changes in the switching algorithm depending on the specific driving style of the "owner". Electronics has provided advanced features for automatic transmission self-diagnosis as well. And it's not just about remembering fault codes. The control program, controlling the wear of the friction discs, the oil temperature, promptly makes the necessary adjustments to the operation of the automatic transmission.
The device and principle of operation of the torque converter
The torque converter is a hydraulic mechanism that is connected between the engine and the vehicle's mechanical power transmission and provides automatic change in the torque transmitted from the engine in accordance with changes in the load on the driven shaft.
The simplest torque converter has three impellers with blades: rotating pump and turbine wheels and a fixed wheel - the reactor. Wheels are usually made by precision casting from light, strong alloys; blades are made curvilinear. From the inside, the blades of the wheels are closed with round walls, forming inside the wheels a small annular cavity of circular cross section of small diameter (torus). Nearby wheels with blades form an annular cavity closed around the circumference, in which the working fluid (special oil) poured into the torque converter circulates.
The impeller is connected to the housing (rotor) and through it to the crankshaft of the engine. The turbine wheel is connected through the driven shaft to the power transmission of the vehicle. The reactor is fixedly fixed on the sleeve connected to the crankcase. The torque converter rotor with impellers located in it is mounted on bearings inside a closed crankcase.
In order for the oil to constantly fill the working cavity of the wheels, as well as for cooling purposes, oil during the operation of the torque converter is continuously pumped from the oil reservoir into the working cavity of the wheels by a gear pump and drained back into the reservoir.
During the operation of the torque converter, the oil injected into the working cavity of the wheels is captured by the blades of the rotating pump wheel, is thrown by centrifugal force to the outer circumference, falls on the blades of the turbine wheel 3 and, due to the pressure created in this case, sets it in motion together with the driven shaft. Further, the oil enters the blades of the fixed wheel-reactor, which changes the direction of the fluid flow, and then again enters the pump wheel, continuously circulating in a closed circle of the inner cavity of the impellers (as indicated by arrows) and participating in the general rotation with the wheels.
The presence of a fixed wheel-reactor, the blades of which are located so that they change the direction of the fluid flow passing through it, contributes to the appearance of a certain force on the reactor blades, causing the appearance of a reactive moment acting through the liquid on the turbine wheel blades in addition to the moment transmitted to it from the pump wheels.
Thus, the presence of the reactor makes it possible to obtain a torque on the turbine wheel shaft that is different from the torque transmitted by the engine.
The slower the turbine wheel rotates compared to the pump wheel (for example, with an increase in the external load applied to the shaft of the turbine wheel), the more significantly the reactor blades change the direction of the liquid flow passing through it and the more additional torque is transferred from the reactor to the turbine wheel, as a result of which the torque increases. moment on its shaft.
Rice. 1. Schemes and characteristics of torque converters: a - single-stage; b - complex
The property of torque converters to automatically change (transform) the ratio of torques on the shafts depending on the ratio of the speeds on the driving and driven shafts (and, therefore, on the magnitude of the external load) is their main feature. Thus, the operation of a torque converter is similar to that of an automatic transmission.
The main indicators characterizing the properties of the torque converter are: the ratio of moments on the driven and driving shafts, estimated by the transformation ratio; the ratio of the number of revolutions on the driven and driving shafts, estimated by the gear ratio, and the efficiency of the torque converter.
The change in the main indicators of the torque converter depending on the number of revolutions of the driven shaft or depending on the value of the gear ratio i can be represented in the form of a graph called the external characteristic of the torque converter.
As can be seen from the external characteristics, with a decrease in the number of revolutions of the driven shaft u and a decrease in the gear ratio, the torque M2 increases significantly with a corresponding increase in the transformation ratio K. When the driven shaft is completely stopped due to a significant overload, the torque M2 on the driven shaft and, accordingly, the transformation ratio K reach the maximum value. This flow of torque M2 provides the machine on which the torque converter is installed, the ability to automatically adapt to changing loads and overcome them, replacing the action of the gearbox.
If a change in load and torque M2 on the driven shaft affects the magnitude of the engine torque Mx and the number of revolutions nx, and they change at different gear ratios, then such a torque converter is called transparent, in contrast to an opaque torque converter, in which a change in external load does not affect the operation of the engine.
On passenger cars, transparent torque converters are mainly used, since in the presence of a carburetor engine they provide the best traction and economic qualities of the car during acceleration and reduce engine noise due to a drop in its speed when starting the car.
On trucks with diesel engines, low-transparent torque converters are used.
The efficiency of the torque converter, as can be seen from the characteristic, does not remain constant under various operating modes and changes from zero with full braking of the driven shaft to a certain maximum value and again drops to zero with full unloading of the driven shaft.
The maximum efficiency value for existing designs of torque converters ranges from 0.85-0.92.
The considered nature of the change in the efficiency of the torque converter limits the zone of its action with low power losses and satisfactory efficiency values.
The main measure that improves the efficiency of a torque converter and increases the range of its operation mode at favorable values of efficiency is the combination of the properties of a torque converter and a fluid coupling in one mechanism. Such torque converters are called complex.
A design feature of the complex torque converter (Fig. 308, b) is that the reactor in it is not rigidly fixed on the fixed sleeve 6, but is mounted on a freewheel.
When the number of revolutions of the driven shaft is significantly less than the number of revolutions of the drive shaft, which corresponds to an increased load on the driven shaft, the fluid flow leaving the turbine wheel hits the reactor blades from the rear (with respect to the direction of rotation) side. At the same time, trying to rotate the wheel in the opposite direction from the general rotation, the flow, by the force created, jams the reactor motionless on the freewheel. When the reactor is stationary, the entire system works like a torque converter, providing the necessary torque transformation and helping to overcome changing loads.
With a decrease in the load on the driven shaft and a significant increase in the number of revolutions of the turbine wheel, the direction of the fluid flow coming from the turbine blades changes, and the fluid hits the front surface of the reactor blades, trying to rotate it in the direction of general rotation. Then the freewheel, wedging, releases the reactor, and it begins to rotate freely in the same direction as the pump wheel. At the same time, due to the absence of fixed blades in the path of the fluid flow, the transformation (change) of the moment stops, and the entire system works as a fluid coupling.
As a result of the combination in one mechanism of the properties of the torque converter and the fluid coupling, which come into action depending on the ratio of the revolutions of the driving and driven shafts, the characteristic of the complex torque converter is a combination of the characteristics of the torque converter and the fluid coupling.
Up to the ratio of the revolutions of the driving and driven shafts, determined by the gear ratio equal to approximately 0.75-0.85, i.e. until the moment when the driven shaft rotates slower than the driving one due to the load applied to it, the mechanism works as a torque converter with the corresponding law With an increase in the number of revolutions of the driven shaft, when there is no need to transform the torque due to a drop in load, the mechanism switches to the operating mode of the hydraulic coupling with the corresponding efficiency flow law and its increase at full unloading to values 0.97-0.98.
Thus, in a complex torque converter, the zone of operation of a mechanism with high efficiency values is significantly expanded, as a result of which the efficiency of the vehicle is increased, which is the main advantage of a complex torque converter.
To further expand the range of high efficiency values and maintain good transforming properties, complex torque converters with two reactors are used, which are switched off from operation in a certain sequence.
A torque converter with one turbine wheel is called a single stage. Torque converters are also used, in which two turbine wheels with their own reactors are installed, which increases the transforming properties of the torque converter, which in this case is called a two-stage one.
The maximum value of the transformation ratio for most of the (single-stage) torque converters, which are not very complicated in design, usually does not exceed 2.0-3.5.
To category: - Vehicle chassis
torque converter is the external assembly of the automatic transmission, whichtransferring torque from the engine to the transmission serves to acceleratewith the help of two turbines rotating in oil, driven and leading)and depreciation (and transformation) of torque from the engine.
The torque converter is often called by the name of its predecessor: "fluid coupling", because it connects the engine to the gearbox like a clutch (clutch). Locked using the clutch, the torque converter is switched off, transmitting torque directly, without loss of power.
In the slang of the masters, the torque converter is called " donut".
The torque converter, although moved outside the design of the automatic transmission, is part of the gearbox, because it is controlled by a valve body through a common hydraulic transmission system. And its malfunctions directly affect the operation of the oil pump, valve body and the resource of the entire box, as (more details -).
Torque converter functions:
Take care of the box during sudden acceleration and engine braking. (This work is done by the damper and the hydraulic fluid between the turbines)
Increasing torque. The very name "Torque Converter" orTorque Converter occurred from the fact that during acceleration there is an approximately 2-fold increase in torque due to the same multiple decrease in the speed of rotation on the output shaft.The higher the speed (and less acceleration) - the lower this multiplicity.
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If you delay replacing a worn torque converter lock-up clutch, then problems such as overheating of the hub, vibrations of the output shaft may appear, which trigger the next link of problems - oil pump. And the pump is the "heart" of the machine, which pumps oil into the "brains" () and to the "arms and legs" (clutch packs) of the automatic transmission. In more detail, the "symptoms of diseases" of automatic transmission are described. |
What work is carried out during the repair of the gas turbine engine?
A typical (minimum) repair of a torque converter includes: “opening” the body seam, revision and cleaning / washing of parts, replacement of the clutch clutch, oil seals, assembly and welding of the body seam.
To disassemble the unit, it is required to cut the assembly weld along the GDT equator on a lathe, and only after depressurization, diagnostics and replacement of consumables are performed. Below is the work on the bulkhead of this node.
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Hydro transformer carries out hydra strong clutch between engine and automatic transmission.Unlike mechanical clutch in the manual gearbox, the gas turbine engine transmits torque from the drive shaft to the driven onethrough the mechanical friction of the clutches, but through the hydraulic oil pressure. As the wind turns the wings of the windmill. 
Numerous video. When the speeds of rotation of the input and output shafts are equal (and this structurally occurs at a speed of 60-70 km / h), the mechanical blocking of the gas turbine engine is activated. With the help of the friction lining of the blocking piston, the rotation of the oil is stopped, and the input and output shafts of the gas turbine engine are blocked and the engine is connected to the transmission directly. The torque converter is switched off in this mode and already mechanically transmits 100% rotation without loss. Similar to depressing the clutch pedal on a manual gearbox. While the gas turbine engine is running, it spends kinetic energy from the engine on oil mixing and, as a result, on heat its friction. And at the moment of blocking, when the friction clutch touches the steel disk, the lining and the friction dust gets into the oil. These two side functions of the GDT are the main problems that negatively affect the health of the automatic transmission. |
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The average efficiency of typical 3- and 4-speed automatic transmissions of the 20th century in the "city driving" mode was from 75 to 85%. And the gas turbine engine used to automatically turn off at a speed of approx. 60 km/h. At the moment when the mechanical blocking is turned on, the efficiency of this node is immediately pulled up to 100%. Analogue of the closed clutch MCP. But as long as the rotating oil transfers the load from the engine to the transmission, the efficiency of this unit is sharply reduced. The faster the lock-up clutch closes and the shorter the period of operation of the gas turbine turbines, the higher the weighted average efficiency of the machine and the lower the fuel consumption and oil heating. In the 21st century for all 6s and 8s speed automatic transmissions with the start of using the on-board computer and (electrical regulators), the weighted average efficiency of the torque converter was brought to a record 94-95%. Optimization is achieved due to the fact that the lock-up clutch is engaged with slip for acceleration as early as possible (sometimes already from 2nd gear - left) and unlocks as late as possible when slowing down. Almost approaching the sport mode of the clutch pedal on the manual gearbox. Which leads to accelerated wear of the locking clutch. |
The "adjustable slip mode" of the locking clutch is when the clutch (or several of them - in a fashion introduced), controlled by a finely tuned and computer, is pressed by oil pressure to such a distance to the body that a thin film of oil remains in the gap between them, large enough to slip and temperature removal from surfaces, and thin enough to make the driven shaft rotate. It's like a dry clutch slipping during aggressive acceleration from a manual gearbox, or controlled deceleration of the wheels by a brake pad. Thus, the locking clutch, together with the turbine impellers, spins the transmission shaft. Joint work of mechanical and hydraulic acceleration. The programmers of some manufacturers have adjusted this effort in such a way that in "sport" acceleration modes up to 80% of the thrust falls on the friction clutch and the remaining 20-30% of all acceleration work is performed by oil and turbines. This increase in efficiency, although it reduces fuel consumption and oil heating, but leads to contamination of the oil with wear products of the friction clutch itself. It should be noted that this is an additional option for the operation of the gas turbine engine. If the gas pedal is pressed calmly, then the "slip mode" does not turn on and the "eternal" turbines and oil work to a greater extent. And the friction clutch in this mode of operation can live 300-400 tkm of run. If earlier the car was accelerated by the oil flow between the impellers of the turbines, and the lock-up clutch only helped a little at the end before blocking, then in the gas turbine engine of the 21st century it is the "slip" clutches that are increasingly accelerating the car, and the turbines only help. This is the idea of Mercedes - to shift most of the work to the clutches in modern stepwise. Thus, a revolutionary change in the very principle of the friction clutch has been introduced. If the clutches of the 20th century worked in the "On-Off" mode (the clutch was as short as possible, with a blow to speed up the gear shift), then the new generations of clutches of the gas turbine engine began to work in the "Regulator" mode, like wheel brake pads. () 
This resulted in the following features: 1. The material of the loaded lining is no longer the same as that of the "lazy" eternal paper friction linings of 4 mortars, but graphite "high-energy" compounds, which are distinguished by wear and temperature resistance and, most importantly, "stickiness" (left). It is this "stickiness" of the lining that allows you to transfer crazy torques from the roaring engine to the wheels. 
And as the reverse side of the coin, these super-resistant and super-adhesive microparticles, torn off from the friction clutch from many months of friction, travel along with oil and “spray” and are welded-pasted into all inconvenient places, from torque converter parts to spools and channels and. 2. The half-worn clutch of the gas turbine engine keeps contact less and less predictably, and most importantly - vibrates, heating the body of the "donut" and the oil itself even more. And the computer does not understand that the friction clutch is worn out and increases pressure on it, which leads to accelerated overheating and final wear of the lining to the adhesive layer. In the first place in the repair by a wide margin are the "bagels" 5HP19, which almost always come to the repair with an overheated pilot hub ( on right) . In order to cut out this section of the structural iron and weld in a new hub, each GDT service has special welding equipment. Pretty delicate and responsible work. 2A. The most unpleasant thing from a worn clutch is its remnants, that is adhesive layer, on which the overlay is glued to the metal. It is the clutch glue particles that are most harmful to the valve body and spool valves. Well, filters of course. Dirt sticks to these hot drops of glue that have fallen into the most important places and clogs the channels. Therefore, the developers of valve bodies and solenoids tearfully implore drivers to change the torque converter lining in a timely manner, without waiting for its final wear. 3. Overheated "donut" oil (over 140 °) in a few hours of such a boil kills the rubber of oil seals and seals, as well as the remains of friction clutches ( cellulose base is charred). And although in the new 6-speed automatic transmissions of German and American manufacturers, instead of a friction lining glued to the piston body, they began to use real carbon-based friction discs (see Fig. above left), an overheated clutch lasts longer, but the dirt from it is much more aggressive than the previous "paper" generation. Therefore, the planned replacement of torque converter clutches has become an obligatory routine work on automatic transmissions of Mercedes and ZF 6HP26 / 28. |
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1. If the pad is worn unevenly and vibrations are heard at a speed of 50-70 km, then this kills both the "donut" itself and the oil seal and oil pump. And the malfunctioning of the pump is similar to the problems of the heart and blood vessels, which lacks pressure on the "brain", causing senile dementia. 2. If the lining is worn down to zero (and this can come from 100 tkm to 250- ... tkm), then the friction clutch begins to “slow down” with the adhesive layer, and getting this glue into the “vessels” of the hydraulic brains leads to a “stroke” and problems with switching . If you notice this in time, then you can still repair the valve body, but if you ride for a month or two, then abrasive dust sticks to this adhesive coating, which eats up the body of the spools to the state of a comma: "it is impossible to repair , change". 3. When the adhesive layer is worn off and the piston brakes metal on metal, then in addition to increasing fuel consumption and reducing the power of the torque transmitted to the wheels, increased oil heating begins. And then wear occurs to such vibrations that a state arises: "change - cannot be repaired." And in this case, instead of the usual 7 tr for donut repair, the costs immediately increase significantly.
The quality of internal surfaces of gas turbine engines directly affects: Dynamic characteristics of acceleration and power loss ( imagine how the speed of a schooner with an uncleaned bottom drops) For oil heating the worst hydrodynamics of the parts overheats the oil faster) The imbalance of the turbines and the appearance of vibrations that kill the bushings and seals of the neighboring unit - the oil pump. (how does the balancing of a wheel change, on the rim of which frost has formed overnight) On oil contamination due to the above reasons, For excessive fuel consumption, and therefore, now the repair of the torque converter with cutting the body is considered a routine operation, like changing the engine oil, which must be done in order to replace the half-worn clutch and restore all joints. To clean this deposit with liquids without disassembly is a vain hope. Torque converter flushing without opening is a hobby to occupy a restless mind. Washing with solvents can lead to a final imbalance of the wheels and finish off the linings and seals. |
In addition, in the "donut" the surfaces of the turbines and the hull lose their smoothness over time due to plaque, as the bottom of the ship is overgrown with shells ( on right).
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Friction linings/ Friction clutches 
New torque converters 6+ speed cars have two modes of operation: 1. Calm. When the gas pedal accelerates the car in about the first third of its travel. Then the good old pair of turbines is mainly loaded, using an oil vortex, and the clutches of the gas turbine engine are connected at the moment of speed alignment (about 60 km / h) of rotation of both shafts by a quick clutch. 2. Aggressive/Sporty mode. When the gas pedal is pressed in the last third - near the floor. Then the friction clutches for blocking the gas turbine engine are connected to the case, pushing the hydraulic turbines aside and sliding, they transmit the torque of the roaring engine to the wheels. Imagine the area of these "slip" friction clutches of the gas turbine engine and the thrust force of the engine! The materials for this innovative graphite (or Kevlar) clutch have been modified many times (sparing oil and valve body) and now there are many types of them: HTE, HTS, HTL, XTL... ( see table on the left) for different torque, different computer settings and for a different driver ... The lockup clutch is usually eaten first in most types of torque converters. |
What wears out in torque converters? (Torque converter clutch lock-up clutch)
The problems of gas turbine engines can be represented as a pyramid:
The most common reason for the need to repair torque converters (bottom of the pyramid) is wear of the friction lining of the cylinder head blocking piston - brake . (on right)
When repairing, the old lining is removed, the installation site is cleaned of adhesive residue and a new clutch friction lining is glued on. This is an analogue of replacing the clutch in a car with a manual transmission.
Without this lining or working with a "eaten" clutch, the torque converter may well perform the main functions of acceleration, and few people notice the difference in blocking delay, or abnormal operation of the clutch or overheating of the oil, and even more so - oil pollution. And many are ready to endure an increase in fuel consumption for months just not to give the automatic transmission to doctors - what if they “heal”?
But if the lining is not replaced in time, then:
1. Worn and flaked friction and adhesive residues fall into the line and clog channels("brains"), leading to a chain reaction of oil starvation - heating - wear - combustion of couplings, hubs and bushings.
2. Slip "bald" lock-up clutch overheats housing and oil, which leads to numerous problems of both electricians (sensors and) and clutches.
3. The bald coupling, sliding by the inhomogeneously eaten friction clutch, begins to vibrate when blocked and, with these vibrations, break the adjacent components of the stuffing box and pump bushings. And these vibrations are already leading to an accelerated aging "iron".
4. Dirt and uneven wear cause damage to the turbines, and when a piece of metal comes off, the blades of all 3 wheels begin to collapse like an avalanche in this meat grinder. This is usually accompanied by rattles, rattling and other unpleasant sounds.
If you start repairs on time, you can save your native gas turbine engine quite cheaply. But more often you have to look for an expensive replacement.
Oil seals and gaskets
The following after the friction clutches in this pyramid of wear of the gas turbine engines are: - Oil seals(pump wheel, ...) due to wear and aging of the material (left), and Seals.
How much does an average Torque Converter repair cost?
The minimum amount of work with the revision and replacement of obligatory replacement consumables average cost... " " .
During the troubleshooting process, craftsmen can determine additional work that needs to be done. What happens infrequently, if the GDT has not turned into a "rattle". Here: - .
Rarer torque converter problems:
- broken wheel blades . (does not happen so often, but leads to a breakdown of the gas turbine engine). It is determined only at autopsy.
- overheating and destruction of the hub Noticeable when viewed .
- overrunning clutch release ,
- complete jammingfreewheel; (doesn't happen often, check)
- Replacing worn needle bearings. (it doesn’t happen often, but if they break down, the gas turbine engine itself is destroyed, check)
- replacement of a burned-out hub that transmits the rotation of the transmission. ( higher)
To repair torque converters, conventional factory turning or welding equipment is not enough. The service life of this complex AT unit depends on the quality and accuracy of processing, and all this requires the organization of a specialized workshop, the supply of spare parts and consumables, and the extensive experience of specialists - a separate business system.
Repaired gas turbine engines have the lowest possible percentage of defects and, as a rule, go up to 70-80% of their original resource. ANDAlwaysrepair is cheaper than replacing the gas turbine. Although in one case of one hundred thousands, it turns out that it is cheaper to replace a dead gas turbine engine with a used one than to repair it.
About the need for timely repair of a gas turbine engine, you should not convince someone who has already once "got" on the overhaul of the machine.
Typical list of works according to the GDT 5NR19, which is popular in repair, it costs 7-8 thousand rubles. and looks something like this:
In rare cases, after opening the gas turbine engine, it becomes clear that it is necessary to replace not consumables, but components, in this case the manager calls and agrees on the work and cost of repairs.
ATPShop after acceptance,
Troubleshooting / repair contacts the client, reports defects and replaced consumables,
Issues an invoice for payment, and after receiving payment, sends it back to the Transport Company.
(In most cases the repair is standard as described above)
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Signs of failure of the gas turbine engine can be found -.
A formal sign of wear of the clutch clutch of the gas turbine engine or overheating of the hub, and with it the pump itself, is oil leakage through the pump seal.
In the later and more serious stages of HDT disease, the following symptoms occur:
Extraneous vibrations and sounds,
Jerks when shifting gears, especially in the region of 60-70 km / h - either stops pulling after picking up speed or pulls unusually long before that, etc.
Increased fuel consumption, oil overheating (indirect signs)
It is practically impossible to accurately diagnose the wear of the gas turbine clutch without special equipment, which is most often the cause of failure of the automatic transmission valve body and, as a result, the transmission itself.
The more powerful the car, the shorter the average service life of the gas turbine engine before overhaul. And if after 150 tkm (and for indestructible 4 mortars - after 250 tkm) the pump seal starts to leak, then it's time to pay back your horse, to do a major overhaul.
Can I restore, clean or flush the torque converter myself?
The answer will probably be unpleasant, but the only one is NO, no one has yet been able to restore a torque converter without opening it. Rinse - it was possible, but this method of repair is like fighting the smell in the car by installing a freshener, instead of cleaning and rinsing the ashtray.
What not to do with "self-medication":
It is definitely not recommended to pour different solvents into the torque converter. Solvents, in addition to oil and soot, also dissolve rubber seals, which leads to accelerated death of nodes and the end of the GDT resource. And they do not dissolve the adhesive composition of the friction clutch, which is distributed from the piston evenly over all rotating parts. Self-healing is a hobby that will cost more than a full-time overhaul from someone who does this job every day.
Below - comparative statistics (for 2012) on the popularity of Torque Converters under repair:
The principle of operation of the automatic transmission The classic “automatic” includes several units, the main of which are a torque converter and a mechanical planetary gearbox.
The torque converter performs not only clutch functions, but also automatically changes the torque depending on the load and the speed of the vehicle's wheels. The torque converter consists of two bladed machines - a centrifugal pump, a centripetal turbine and a guide vane-reactor located between them. The pump and turbine are extremely close together, and their wheels are shaped to provide a continuous circle of circulation of the working fluid. As a result, the torque converter received minimal overall dimensions and, at the same time, energy losses for fluid flow from the pump to the turbine were reduced.
The pump wheel is connected to the crankshaft of the engine, and the turbine is connected to the gearbox shaft. Thus, there is no rigid connection between the driving and driven elements in the torque converter, and the transfer of energy from the engine to the transmission is carried out by the flow of the working fluid, which 
The vapor is thrown from the pump blades onto the turbine blades.
Actually, according to this scheme, a fluid coupling works, which simply transmits torque without transforming its value. To change the moment, a reactor is introduced into the design of the torque converter. This is also a wheel with paddles, but it is rigidly attached to the body and does not rotate (note: until a certain time). The reactor is located on the path through which the oil returns from the turbine to the pump. The reactor blades have a special profile, and the interblade channels gradually narrow. For this reason, the speed at which the working fluid flows through the channels of the guide apparatus gradually increases, and the fluid itself is ejected from the reactor in the direction of rotation of the pump wheel, as if pushing and urging it. There are two immediate consequences from this. The first is due to an increase in the speed of oil circulation inside the torque converter with a constant pump operation mode (read: engine, since the pump wheel, as mentioned above, is rigidly connected to the crankshaft), the torque on the output shaft of the torque converter increases. The second is that with the pump operating mode unchanged, the turbine operating mode changes automatically and steplessly depending on 
ti from the resistance applied to the turbine shaft (read: car wheels).
Let us clarify these axioms with concrete examples. Suppose a car that was moving along a flat section of the road has to climb uphill. Let's forget about the accelerator pedal for a while and see how the torque converter reacts to changing driving conditions. The load on the drive wheels increases, and the car begins to lose speed. This leads to a decrease in the turbine speed. In turn, the resistance to the movement of the working fluid in the circle of circulation inside the torque converter is reduced. As a result, the circulation speed increases, which automatically leads to an increase in torque on the turbine wheel shaft (similar to downshifting in manual transmissions) until there is an equilibrium between it and the moment of resistance to movement.
An automatic transmission works in a similar way when starting from a standstill. Only now is the time to remember about the gas pedal, pressing which increases the speed of the crankshaft, and hence the pump wheel, and about the fact that at first the car, and therefore the turbine, were in a stationary state, but the internal slip in the torque converter did not interfere with the engine idling (clutch pedal depressed effect). In this case, the torque is transformed as many times as possible. But when the required speed is reached, there is no need to convert the torque. The torque converter, by means of an automatically acting lock, turns into a link that rigidly connects its drive and driven shafts. Such blocking eliminates internal losses, increases the transmission efficiency value, reduces fuel consumption in the steady state of motion, and during deceleration increases the efficiency of engine braking. By the way, at the same time, in order to reduce all the same losses, the reactor is released and begins to rotate together with the pump and turbine wheels.
Why is a gearbox attached to a torque converter if it itself is able to change the amount of torque depending on the load on the drive wheels? Alas, the torque converter can change the torque with a coefficient not exceeding 2-3.5. Like it or not, such a range of gear ratio changes is not enough for the efficient operation of the transmission. In addition, no, no, yes, and there is a need to turn on the back 
its stroke or complete separation of the engine from the drive wheels.
Automatic transmissions are geared, but differ significantly from conventional manual transmissions, if only because the gears are shifted without interruption in the flow of power using hydraulically driven multi-plate friction clutches or band brakes. The required gear is selected automatically, taking into account the speed of the car and the degree of pressure on the gas pedal, which determines the desired intensity of acceleration. The hydraulic and electronic automatic transmission control units are responsible for gear selection. The driver, in addition to pressing the accelerator, can influence the process of changing gears by choosing a winter or sports shifting algorithm or by setting, for example, when driving in difficult conditions, the gearbox selector in a special position that does not allow automatic switching above a certain accelerating gear.
In addition to the torque converter and the planetary gear, automatic gearboxes include an oil pump that supplies the torque converter and the hydraulic control unit with the working fluid and provides lubrication for the box, as well as a radiator for cooling the working fluid, which tends to get very hot due to intensive “shoveling”.
Torque converter. General device and principle of operation
The torque converter (GT) (torque converter) is used to transmit torque directly from the engine to the elements of an automatic transmission (AT) and consists of the following main parts: 
Pump wheel or pump (pump);
- GT blocking plate (lock - up piston);
- turbine wheel or turbine (turbine);
- reactor;
- overrunning clutch (one - way clutch).
To illustrate the principle of operation of the GT as an element that transmits torque, we will use the example with two fans. One fan (pump) is connected to the network and creates an air flow. The second fan (turbine) is turned off, however, its blades, perceiving the air flow created by the pump, rotate. The speed of rotation of the turbine is less than that of the pump, it sort of slips in relation to the pump. If we apply this example in relation to GT, then in it the impeller of the pump wheel acts as a fan connected to the network (pump).
The impeller is mechanically connected to the motor. The turbine wheel acts as a switched off fan (turbine), connected through splines to the automatic transmission shaft. Like a fan - a pump, the impeller of the GT pump wheel, rotating, creates a flow, only not air, but liquid (oil). The flow of oil, as in the case of a fan-turbine, causes the turbine wheel of the GT to rotate. In this case, the GT works like an ordinary fluid coupling, only transferring torque from the engine to the automatic transmission shaft through the liquid, without increasing it. An increase in engine speed does not lead to any significant increase in the transmitted torque.
Let's go back to the fan illustration. The air flow that rotates the fan blades - turbines, is wasted in space. If this flow, which retains significant residual energy, is directed again to the fan-pump, it will begin to rotate faster, creating a more powerful air flow directed to the fan-turbine. That, respectively, will also begin to rotate faster. This phenomenon is known as torque conversion (increase).
In GT, in addition to the pump and turbine wheels, the torque conversion process includes a reactor that changes the direction of the fluid flow. Like the air that rotated the fan blades - turbines, the fluid (oil) flow that rotated the GT turbine wheel still has significant residual energy. The stator directs this flow back to the impeller, causing it to spin faster, thereby increasing torque. The lower the speed of rotation of the turbine wheel of the GT in relation to the speed of rotation of the pump wheel, the greater the residual energy of the oil returned by the stator to the pump, and the greater will be the moment created in the GT.
An automatic transmission works in a similar way when starting from a standstill. Only now is the time to remember about the gas pedal, pressing which increases the speed of the crankshaft, and hence the pump wheel, and about the fact that at first the car, and therefore the turbine, was stationary, but the internal slip in the torque converter 
did not prevent the engine from idling (the effect of a depressed clutch pedal). In this case, the torque is transformed as many times as possible. But when the required speed is reached, there is no need to convert the torque. The torque converter, by means of an automatically acting lock, turns into a link that rigidly connects its drive and driven shafts. Such blocking eliminates internal losses, increases the transmission efficiency value, reduces fuel consumption in the steady state of motion, and during deceleration increases the efficiency of engine braking. By the way, at the same time, in order to reduce all the same losses, the reactor is released and begins to rotate together with the pump and turbine wheels.
Left figure - GT reactor is held by freewheel; Right figure - GT stator rotates freely.
The turbine always has a rotation speed lower than the pump. This ratio of the speeds of rotation of the turbine and the pump is maximum when the vehicle is stationary and decreases with increasing speed. Since the reactor is connected to the GT through a one-way clutch, which can rotate only in one direction, due to the special shape of the reactor and turbine blades, the oil flow is directed to the reverse side of the reactor blades (Fig. 4), due to which the reactor is wedged and remains stationary, transferring to pump input is the maximum amount of residual oil energy remaining after the turbine has been rotated. This mode of operation of the GT provides maximum transmission of torque to them. For example, when starting off, the GT increases the torque by almost three times. 
As the car accelerates, the slippage of the turbine relative to the pump decreases and there comes a moment when the oil flow picks up the reactor wheel and begins to rotate it towards the freewheel of the overrunning clutch (see Fig. 5). GT ceases to increase torque and switches to conventional fluid coupling mode. In this mode, the GT has an efficiency that does not exceed 85%, which leads to the release of excess heat in it and, ultimately, an increase in fuel consumption by the engine of the car. 
car.
To eliminate this shortcoming, a blocking plate is used (Fig. a). It is mechanically connected to the turbine, however, it can move left and right. To shift it to the left, the oil flow that feeds the GT is fed into the space between the plate and the GT body, providing their mechanical decoupling, that is, the plate in this position does not affect the operation of the GT in any way.
When the vehicle reaches high speed, on a special command from the automatic transmission control device, the oil flow changes so that it presses the blocking plate to the right against the GT body (fig. b). To increase the adhesion force, a friction layer is applied to the inside of the housing. There is a mechanical blocking of the pump and turbine by means of a plate. GT ceases to perform its functions. The engine is rigidly connected to the input shaft of the automatic transmission. Naturally, at the slightest braking of the car, the lock is immediately turned off.
Many of you probably know elementary things about the structure of a manual transmission - you know that the engine is connected to the transmission by means of a clutch, because without this connection the car will not be able to come to a complete stop, of course, without killing the engine. But cars with automatic transmission don't have a clutch that disconnects the transmission from the engine. Instead, they use an amazing device called torque converter. Maybe its device will seem a little complicated to you, but what it does and what convenience it delivers is just very interesting!
In this article, we will learn why a car's automatic transmission needs a torque converter so much, how a torque converter works, and some of its disadvantages.
Torque Converter Basics
Just like with a manual transmission, an automatic transmission car needs to find a way to simultaneously keep the engine running (crankshaft spinning) and the wheels and gears in the gearbox stopped. Manual transmission vehicles use a clutch that is completely disconnects the engine from the gearbox, but the automatic transmission uses a torque converter.
A torque converter is a type of fluid coupling that allows the engine to rotate independently of the transmission. If the engine is turning slowly, such as when the car is idling at a red traffic light, the amount of torque that is transmitted through the torque converter is very small, and it is enough to hold the car in place with just light pressure on the brake pedal.
If you were to press on the gas pedal while the car was stopped, you would also have to apply more pressure on the brakes to keep the car from moving. This is because when you step on the gas, the engine speeds up, and the pump pumps more fluid into the torque converter due to this acceleration, causing more torque, which in turn is transmitted to the wheels.
As shown in the picture above, there are four components inside a very strong torque converter housing:
- Pump
- Turbine
- stator
- Transmission oil
The torque converter housing is bolted to the engine flywheel, meaning the housing always rotates at the same speed as the engine crankshaft. The fins that make up the torque converter pump are attached to the housing so they also rotate at the same speed as the engine. The torque converter cutaway in the figure below shows how it's all connected inside the torque converter.
The pump inside the torque converter is a type of centrifugal pump. As it rotates, the liquid moves in a direction from the center to the edges, much like the spinning drum of a washing machine during the spin cycle throws water and clothes along its walls. At the same time, as the liquid rushes away from the center, a vacuum is created in this center, which attracts even more liquid.
The liquid then enters the turbine blades, which is connected to the transmission. It is the turbine that makes the transmission spin, which basically drives your car. So how does the liquid (more precisely, oil) come from the pump to the turbine?! The fact is that while this liquid rushes from the center to the edges of the pump, it meets on its way the pump blades, which are directed in such a way that the liquid ricochets about them and is already directed along the axis of rotation of the pump away from it - to the turbine , which is just opposite the pump.
The turbine blades are also slightly curved. This means that the fluid that enters the turbine from the outside must change its direction, moving to the center of the turbine. It is this directional change that causes the turbine to rotate.
To make it even easier to imagine the principle of operation of a torque converter, let's imagine a situation with room fans located opposite each other at a short distance (say, about one meter) and directed opposite each other - if one of the fans is turned on, it will drive air away from itself due to its curved blades to the fan that stands opposite it, and that, in turn, will begin to rotate, because its blades are also curved and the air flow pushes them all in one direction (exactly in the direction in which the fan shaft starts to rotate) .
But we are still moving further: the fluid exits the turbine at its center, moving again in a different direction - the opposite direction from that in which it once entered the turbine - that is, again towards the pump. And here lies the big problem - the fact is that by their design (more precisely, by the design of their blades, the pump and the turbine rotate in opposite directions, and if the liquid is allowed to get back into the pump, it will greatly slow down the engine. Here why the torque converter has a stator which, due to its design, changes the direction of the oil flow, and thus the residual energy that returns from the turbine to the pump goes into action - helping the engine spin the pump a little.
It is important to note that the speed of rotation of the turbine will never be equal to the speed of rotation of the pump, and the efficiency in the torque converter will not even come close to mechanical gear mechanisms that transmit torque. That is why a car with automatic transmission has a significantly higher fuel consumption. To combat this effect, most vehicles have a torque converter fitted with a lock-up clutch. When it is required that the two halves of the torque converter (pump and turbine) rotate at the same speed (this happens, for example, when the car is moving at high speed), the lockup clutch locks them tightly together, which prevents the pump from slipping relative to the turbine and thus improves efficiency fuel consumption.
