Purpose and design of spark plugs literature. Why does a car need a spark plug?

The spark plug is the most important element of the engine ignition system, which directly carries out ignition air-fuel mixture in the combustion chamber. IN modern cars candles of various designs are used and operational parameters, but they all have a similar operating principle.

Device and role in the car

Spark plug design

The basic design of a candle includes the following elements:

• Metal body with printed outside thread for attaching the spark plug to the cylinder head. It also performs the function of removing excess heat and serves as a conductor from the “ground” to the side electrode.
• Insulator. It usually has a ribbed surface, which lengthens the actual path of surface currents and prevents breakdown along the surface.
• Central and side electrodes, between which a spark occurs, igniting the air-fuel mixture. The side electrode is made of steel alloyed with nickel and manganese. The central one is made of noble metals, which ensures the possibility of self-cleaning of the electrode.
• Contact terminal for attaching the spark plug to high voltage wires ignition systems. The connection can be threaded or snap-on.

A resistor may also be provided in the design of a car's ignition system spark plug. Its main task is to suppress interference created by the ignition system. Resistance can vary from 2 kOhm to 10 kOhm.

Spark plugs used in engines internal combustion, also called spark. They form a spark at each compression stroke (or compression and exhaust when using two-terminal ignition coils), igniting the air-fuel mixture at a certain moment throughout the entire operating time of the engine. As a rule, there is one spark plug per engine cylinder (with the exception of Twinspark engines), which is screwed into special holes in the cylinder head housing using threads. The working part is located in the combustion chamber of the engine, and its contact terminal is outside.

Incorrectly tightened spark plugs can lead to unstable engine operation. Insufficient tightening reduces compression in the combustion chamber. If tightened too tightly, mechanical deformation may occur.

Operating principle and characteristics

Spark formation on the electrodes

The main task of a spark plug is to generate a spark and maintain it for a period of time. required quantity time. For this low voltage from the car battery is converted into high voltage (up to 40,000 V) in the ignition coil, and then goes to the spark plug electrodes, between which there is a gap. The “plus” from the coil comes to the central electrode, the “minus” - to the side of the engine.

At the moment of voltage formation on the electrodes (“plus” from the coil on the central one and “minus” on the side one from the engine), sufficient to overcome (breakdown) the resistance of the medium in the gap, a spark occurs between them.

Spark gap value

Spark gap - main parameter spark plugs. It determines the minimum distance between the electrodes to ensure the formation of a spark of sufficient size and the possibility of breakdown of the corresponding layer of the medium (fuel-air mixture under pressure).

Spark gap

The gap size must be within the limits specified by the manufacturer. If the gap is too large, the spark discharge energy may not be enough to maintain the required burning time of the candle and the mixture may not ignite. On the other hand, too small a gap will lead to burnout of the electrodes and increased wear candles.

The size of the spark gap differs depending on the operating mode of the engine and its type and manufacturer. The lower threshold of the spark gap can be about 0.4 mm, and the upper threshold can reach up to 2 mm.

To check the size of the spark gap, use special tool- a probe that can be round or flat. The second type is easier to use, but gives an error because it does not take into account the wear of the electrode surface. The gap is adjusted to the required size manually by bending the side electrode.

What is heat number

Location of the spark plug in the engine

No less important parameter is the heat number. It determines the thermal properties of the structure and demonstrates at what pressure in the combustion chamber uncontrolled self-ignition of the fuel-air mixture (glow ignition) can occur. In simple words, the higher the glow number, the less the spark plug will heat up during engine operation.

Designs with different heat ratings are used according to the type of motor, mode and conditions of its operation. So, in summer time and under increased loads it is optimal to use structures with a high heat rating, and in winter or during quiet ride within the city limits - with less.

Spark plugs with a low heat rating are installed in engines with a low pressure level running on low-heat fuel. octane number. Designs with a high heat rating, on the contrary, are used in engines with high compression and high temperature load of the combustion chamber.

Types and markings

Spark plug markings

In order not to make a mistake when choosing a model, you should pay attention to the markings of the purchased spark plugs. Each manufacturer has its own.

The first parameter is usually the thread diameter and the shape of the supporting surface, demonstrating the ability to actually install the spark plug on a particular engine.

The symbol R (P) often indicates the presence of a resistor in the design. Next, the heat rating, the size of the spark gap and the material from which the electrodes are made are indicated.

Based on the number of electrodes, spark plugs are divided into two types:

• Single-electrode.
• Multielectrode - they have several side electrodes. The spark occurs with the one with the least resistance.

Depending on the heat value, candles are divided into:

• hot with a heat rating from 11 to 14;
• average - from 17 to 19;
• cold - from 20 and above;
• unified - from 11 to 20.

Spark plugs with different number electrodes

According to the type of material of the central electrode, spark plugs are distinguished:

• iridium;
• yttrium;
• tungsten;
• platinum;
• palladium

Iridium is considered the most durable and wear-resistant car spark plugs ignition They are used in engines high power, but when installed on conventional motors they do not create serious improvements.

Service life and common faults

In practice, you can determine when to change spark plugs by taking into account several aspects:

• Manufacturer's stated service life specific brand spark plugs. For example, the replacement frequency for standard models is up to 50 thousand kilometers, for platinum models this figure is 90 thousand kilometers, and the most expensive iridium spark plugs last up to 160 thousand kilometers.
• Terms of Use. When using low-quality fuel, the actual operating life will be 20% less than that declared by the manufacturer. In this case, iridium spark plugs are especially sensitive.
• Condition of the electrodes. They may burn out during long service life or as a result of violation of engine operating conditions. Electrodes can be cleaned mechanically or spontaneously (when high temperatures are reached). It is worth noting that iridium and platinum spark plugs cannot be cleaned mechanically.
• Condition of the insulator. It may be dirty or destroyed.

The correct start and power of the engine, fuel consumption and CO content in the engine depend on the performance of this seemingly simple element. exhaust gases, and therefore the answer to the question of why change spark plugs in a timely manner is quite obvious.

Spark plug- a device designed to ignite the fuel mixture entering the engine combustion chambers at the end of the compression stroke.

Operating principle

Electricity high voltage(up to 40,000 V) is supplied through high-voltage wires from the ignition coil, through the ignition distributor, to the spark plug. A spark discharge occurs between the central electrode of the spark plug (plus) and its side electrode (minus). This one ignites fuel mixture, located in the combustion chamber of the engine at the end of the compression stroke.

Types of spark plugs

Spark plugs come in spark plugs, arc plugs, and glow plugs. We will be interested in spark engines used in gasoline internal combustion engines.

Decoding the markings of domestically produced spark plugs

As an example, let's take the widely used A17DVRM candle.

A – thread M 14 1.25

17 – heat number

D – length of the threaded part 19 mm (with a flat seating surface)

B – protrusion of the thermal cone of the spark plug insulator beyond the end of the threaded part of the body

P – built-in noise suppression resistor

M – bimetallic central electrode

The date of manufacture, manufacturer, and country of manufacture may also be indicated.

Spark plug markings imported production does not have a unified decryption system. What it means for certain candles can be found on the websites of their manufacturers.

Spark plug device

Contact tip. Used for fastening high voltage wire on a candle.

Insulator. Made of high-strength aluminum oxide ceramics that can withstand temperatures up to 1000 0 and electricity voltage up to 60,000 V. Necessary for electrical insulation of the internal parts of the spark plug (central electrode, etc.) from its body. That is, the separation of “plus” and “minus”. It has several annular grooves in the upper part and a special glaze coating that serves to prevent current leakage. The part of the insulator on the side of the combustion chamber, made in the form of a cone, is called a thermal cone and can either protrude beyond the threaded part of the housing ( hot candle), and be drowned in it ( cold candle).

Spark plug body. Made of steel. Serves to screw the spark plug into the head of the engine block and remove heat from the insulator and electrode. In addition, it is the vehicle's ground conductor to the side electrode of the spark plug.

Central electrode. The tip of the central electrode is made of a heat-resistant iron-nickel alloy with a core of copper and other rare earth metals (the so-called bimetallic electrode). It conducts electric current to create a spark and is the most hot part candles.

Side electrode Made from heat-resistant steel with an admixture of manganese and nickel. Some spark plugs may have multiple side electrodes to improve sparking. There are also bimetallic side electrodes (for example, iron and copper) that have better thermal conductivity and an increased service life. The purpose of the side electrode is to provide a spark to the spark plug between it and the center electrode. Acts as a “mass” (minus).

Noise suppression resistor. Made from ceramic. Serves to suppress radio interference. The connection between the resistor and the central electrode is sealed with a special sealant. Not available on all spark plugs. For example, A17DV is not there, A17DVR is.

Sealing ring. Made of metal. Serves to seal the connection of the spark plug with the seat in the block head. Present on spark plugs with a flat contact surface. It is not present on spark plugs with a conical contact surface. The model shows a spark plug with a flat seating surface and an O-ring.

Gap between spark plug electrodes

Engine passenger car It works effectively only with a certain gap between the spark plug electrodes. The spark plug gap must comply with the requirements of the vehicle's factory operating instructions. With a smaller gap, the spark between the electrodes is short and weak, and the combustion of the fuel mixture worsens. With a larger gap, the voltage required to break through the air gap between the spark plug electrodes increases, and there may be no spark at all, or there will be one, but a very weak one.

The gap is measured using a round feeler gauge of the required diameter. It is not recommended to use a flat feeler gauge as the gap measurement will be inaccurate. This is explained by the fact that during the operation of the spark plug, metal is transferred from one electrode to another. Over time, a pit forms on one electrode, and a tubercle on the other. Therefore, only round feeler gauges are suitable for measuring gaps.

The gap between the spark plug electrodes is adjusted only by bending the side electrode.

With the onset of winter, to reduce the breakdown voltage, the normal gap can be reduced by 0.1 - 0.2 mm. When cranking the engine with the starter in cold weather, the engine will seize faster.

Heat number

The thermal characteristic of a spark plug (ability to withstand heat) is called heat rating. Each type of engine requires a spark plug with a specific heat rating. Candles are divided into cold (with a high heat rating) and hot (with a low heat rating).

The heat rating is determined by the material of the insulator and the length of its lower part (for hot spark plugs it is longer). Domestic candles have heat ratings from 11 to 23, foreign ones individually for each manufacturer.

With incorrectly selected spark plugs, glow ignition is possible, when the fuel mixture in the cylinders is ignited prematurely not by an electric spark that occurs between its electrodes, but by the red-hot body of the spark plug. In this case, the engine rings under load (detonation, “knocking fingers”), as if the ignition timing is incorrectly set, and also continues to operate for some time when the ignition is turned off. It is necessary to replace the spark plugs with cooler ones.

And, conversely, the presence of constantly occurring black deposits () on the electrodes of the spark plugs, when working engine, indicates that the spark plugs are cold and should be replaced with hotter ones.

Properly selected candles should have a light brown color at the bottom, as temperature regime such a candle is 600-800 0. In this case, the candle cleans itself, the oil that gets on it burns out, and carbon deposits do not form. If the temperature is below 600 0 (for example, when driving constantly in the city), then the spark plug very quickly becomes covered with soot, if above 800 0 (when driving in power modes) glow ignition occurs. Therefore, it is worth selecting spark plugs for your engine according to the recommendations of its manufacturer.

Checking the spark plugs

Unscrew the spark plugs and inspect their central electrodes. If they are black, the fuel mixture is over-rich; if they are light (light gray), the fuel mixture is lean.

We replace defective spark plugs. Read more about this on the page “Spark plug malfunctions”. Applicability of spark plugs for different engines can be viewed on the page “Applicability of spark plugs for VAZ car engines”

Without a spark plug, a modern gasoline engine would not be able to operate. In addition, the relatively inconspicuous part must withstand significant temperature and pressure. How do spark plugs work and what are their most common types? important characteristics?

The first practical use of a spark plug in an internal combustion engine is associated with the name of the Belgian Joseph Lenoir. This happened in 1860. He used such a device for ignition in his engine. But the spark plug was first patented some thirty-eight years later. And three inventors had something to do with this: Nikola Tesla, Frederick Richard Sims and Robert Bosch. Later, other famous names began to be associated with spark plugs. For example, Albert Champion is the founder famous company on their production.

Working conditions that you won't envy.

The spark plug may seem like a small part, but the conditions in which it must operate deserve at least some recognition. As the specific power of engines increases and at the same time efforts are made to extend the service life of products, increasingly higher demands are placed on them. However, judge for yourself.
Since the spark plug enters the engine's combustion chamber, it must be able to withstand rapid temperature changes ranging from approximately 2000 to 2500 degrees, and pressures up to 6 bar. At the same time, during intake, the pressure in the cylinder drops below atmospheric pressure and at the same time the temperature drops to approximately 80 degrees. But that's not all.

I wonder what for six-cylinder engine at 5000 rpm, 15,000 spark discharges are required every minute! In one minute, each candle ignites the mixture 2500 times, which is more than 40 times per second! The product is also subject to adverse chemical influences, since environment inside the combustion chamber is quite aggressive, not to mention different conditions engine operation. And also voltage surges in the range from 25 to 30 kV.

About the principle of discharge

The mixture is ignited by a spark plug due to the occurrence of a spark between the electrodes. We are talking about the so-called discharge between the electrodes. In fact, a spark occurs at the moment when the breakdown voltage between the central and side electrodes exceeds (there may be more of them). That is, the energy from the ignition coil is converted into an electric spark. The so-called arc flash voltage is assessed. Its value depends on the distance between the electrodes, the geometry of the electrodes, the pressure in the combustion chamber and the ratio of air and fuel at the moment of ignition - that is, on the saturation of the mixture. During engine operation, gradual wear of the device occurs, which is manifested by an increase in the distance between the electrodes, which leads to a gradual increase in the breakdown voltage.
How important is good insulation?

The structure of a spark plug

So, what does a spark plug consist of? The body of the product forms an insulator. Previously, mica was used, today ceramics, and more recently they began to use the so-called corundum or aluminum oxide. At the very top of the device there is a terminal for attaching an ignition cable or possibly housing an ignition coil (for direct FPS ignition with a separate coil for each spark plug). Next comes a metal body, part of which is a threaded connection, with its help the product is screwed into the cylinder head. An external (sometimes also called side) electrode is connected to it and, therefore, to the metal body. In the center of the spark plug there is a central positive electrode connected to a contact terminal for connecting the high-voltage cable of the ignition system and hermetically packaged in glass or silicon. The external electrode is electrically connected to the body vehicle, that is, the negative pole electrical system.

Types of spark plugs

There are many types of candles. At first glance you can see the differences in thread diameter: M18, M14, M12 and M10. At the same time, there is a different thread pitch: from a maximum of 1.5 to 1.25 and even 1.0 mm. Next, the shape of the supporting (sealing) surface of the spark plug in the cylinder head is distinguished. It can be conical or flat. There are candles with short and long threads.

Further division occurs according to the layout (structure) of the spark or the number of external electrodes, there can be up to four. In addition, spark plugs may differ in the material used to make the electrodes, the shape of the body and the level of interference.

To meet current and ever-increasing spark plug requirements, the choice of the right material for the electrode. Medium products are usually manufactured in such a way that a compromise is maintained between strength and material consumption. Alloys of tungsten, platinum and iridium are used. An alternative could be an alloy of chromium and iron. Better yet, silver, which has excellent properties in terms of thermal load, is wear-resistant and extends the life of the spark plug to 70,000 km. The downside is, of course, the price. In addition, platinum is used. It is more expensive, but it resists fading and corrosion well. Very often the central electrode consists of two various materials.

Features of spark plugs.

When considering spark plugs, there are, among other things, three important properties, on which their other characteristics depend.

• The first is the already mentioned distance between the electrodes, popularly called the gap. This is the minimum distance between the central and side electrodes. The shorter the distance, the less arc voltage (breakdown) is required to produce a spark. But at a short distance between the electrodes, the spark is short. As a result, little energy is released, which reduces the combustion of the mixture. Misfire occurs, the engine is noisier, and exhaust gas emissions deteriorate. Conversely, a longer distance requires a high ignition voltage and may result in misfire when high speed engine.
• The second feature is the position of the spark gap. This is the distance of the end of the central electrode from the front surface threaded connection spark plug. It is usually in the range from 3 to 5 mm. But for racing engines this value can even be negative. The central electrode is thus immersed in the threaded part.
• The third feature is the heat transfer value of the spark plug. This is a measure of the thermal load capacity of a product, which must therefore be adapted to the characteristics of the engine. The spark plug must not exceed a certain temperature zone during operation. And in practice, some devices may heat up excessively in one engine, while the operating temperature in another will be too low.

What is heat number

There are hot candles with high temperature, which they can withstand, and cold, their operating temperature, on the contrary, is lower. The heat transfer value of the spark plug mainly determines the surface size of the bottom of the insulator. If the leading edge of the insulator is long, the device will have a high temperature withstanding ability. On the other hand, the short leading edge of the insulator has a cold plug (with low temperature properties).

How to tell if spark plugs are suitable.

The qualities described above and the resulting differences between certain types spark plugs are interesting in terms of their use, but in practice, more precisely, in order to understand what spark plugs your car’s engine needs, this knowledge is not required at all. When purchasing products, the only important thing is correct labeling, which ensures that they are intended specifically for a specific engine.

Unfortunately, different manufacturers use different candle labeling methodologies. Luckily, there is a conversion chart that should be available from every auto parts dealer. It is interesting to note, for example, that the Bosch W7D product from Champion is listed as N9Y, while NGK calls it BPM7. Moreover, in terms of properties and characteristics, this is the same candle. What will happen next...

In a gasoline internal combustion engine (ICE), for ignition, a compressed piston fuel-air mixture An element called a spark plug is used. It was invented by Robert Bosch back in 1902, after which the company of the same name introduced it into.

What is its structure?

The basic design of a spark plug is approximately the same for any company that produces it. This is a metal body, electrodes, the number of which may vary depending on the brand, a ceramic insulator and a central insulator passing through it. contact rod. Then the differences begin.

The central contact rod, for example, may have a flat pad tip. But may have a U or V groove. It can be pointed - if it is made of iridium, like DENSO spark plugs. They even have a side electrode with a specially shaped profile. This company produces perhaps the most reliable spark plugs - iridium-platinum ones.

U individual models there may be no side electrode at all - in particular, SAAB engineers have developed a motor in which the piston itself has a pointed protrusion, the function of which is the same as that of the side electrode. When the piston is closest to the top dead center, a spark jumps between it and the central electrode, igniting the compressed fuel-air mixture.

The already mentioned two or more side electrodes are also changed in better side operating modes and parameters of the motor. At the same time, the requirements for working gaps are increasing, which are generally not recommended to be changed or touched in any way by bending or unbending, but only strictly maintaining the factory parameters of their manufacture.

At the same time, the principle of operation of a spark plug with two or more electrodes is simple; no technical tricks are required for its stable operation: when, as the electrode is depleted and “eaten up” by the spark, spark failures begin, it automatically appears on the unused electrode, and the process internal combustion engine operation continues without interruption.

The metal housing at the bottom with a thread for screwing into the cylinder head (cylinder head) has a flat or conical ring-shaped platform. Spark plugs with a flat platform are equipped with a crimp ring-washer made of soft metal, which prevents the compressed fuel-air mixture or combustion products from breaking out. For candles with a conical profile after threading, there is no need for such a ring; the conical profile itself reliably seals the top of the combustion chamber.

The central insulators in all models are made of heat-resistant ceramics. It is on this that the marking is applied with the type, name of the manufacturing company, etc. Inside, between the contact for the wire and the rod with the central contact, there is a resistor, the main function of which is to suppress radio interference that occurs during the spark discharge. Taking into account the development of radio and telecommunications and their implementation in vehicle systems, including electronic control injection, the placement of such a resistor has become mandatory in the spark plug design.

In the part that is screwed into the cylinder head, the central insulator has the shape of a gradually tapering cone - this is done in order to more effectively remove heat, preventing overheating.

View of a modern candle

Diversity technical solutions in development and production gasoline engines internal combustion also gave birth to many models of candles for them. Depending on the fuel used for the car, the compression ratio in the cylinder, and the method of ignition control (mechanical, using a distributor, or electronic), they can be divided into the following types.

Types of candles

They are divided according to several characteristics:

1. Heat number.
2. Number of electrodes.
3. Spark gap.
4. Temperature range.
5. Service life.
6. Heat resistance characteristics.

In addition, some types of spark plugs different years produced by the same company may differ in the length of the threaded skirt: early models cars had thinner cylinder heads, which were made of cast iron and, accordingly, shorter threads were required. With the transition to cylinder heads made of aluminum alloys, their thickness increased, and therefore the thread length in it also became longer.

An experienced motorist will always pay attention to the heat number at the beginning, which shows at what pressure the heat effect can occur, that is, the continuation of engine operation after the ignition circuit is broken, when the engine continues to operate from contact with an electrode heated to critical values.

At the same time, it is still permissible to use a spark plug with a heat rating higher than the recommended one, but with a lower one, operating the engine is prohibited! Otherwise, the unlucky driver will quickly face the problem of burnt pistons, valves and a breakdown of the cylinder head gasket.

For high-quality and stable spark formation, spark plugs with two, three and even four side electrodes have been produced over the last two decades.

But stability of operation can be achieved in another way: by placing auxiliary elements that play the role of these electrodes on the spark plug insulator itself. Several wandering rings appear around the central electrode electrical discharges, and thus the likelihood of engine failure is significantly reduced.

Sports Brisk candle with intermediate electrodes on an insulator

Let's give a few more important points in the characteristics of the candles:

• Violation of such a parameter as the spark gap will also negatively affect the operation of the motor;
• No less important is heat resistance, its temperature Range, meaning heating of the part that is immersed in the space between the piston and the cylinder head. The temperature range inside the working part normally lies within 500-900⁰С. Going beyond this range means a decrease in resource. In particular, for all types of spark plugs, a decrease in temperature leads to a rapid increase in soot;
• In a normally adjusted engine, performance depends on mileage and is approximately 30,000 km for spark plugs operating on a classic ignition circuit, and 20,000 on an electronic one. However, the highest priced (but also most reliable) DENSO spark plugs have a service life of up to 5-6 years. Or, in other words, they will provide mileage without replacement under standard operation for about 150,000 - 200,000 kilometers. True, the requirements for maintaining regimes according to instructions have been tightened. These requirements include the use of fuel with an octane number in no case lower than the recommended one, and their installation strictly according to the rules. In particular, it is not allowed to tighten them into the cylinder head with a force higher or lower than recommended, which may entail negating all their advantages;
• The thermal parameter shows the relationship between engine modes and the operating temperature of the spark plug. To increase it, the size of the thermal cone is increased, however, adhering to the recommended value of 900 degrees. Exceeding these limits increases the risk of glow ignition.

Precious metals in candle design

The gradation of species depends not only on the stated parameters. When describing the performance characteristics of a spark plug, you also need to take into account what material the electrode tips are made of.

The cheapest candles are nickel. The simplicity of the design also determines a short service life, so they are replaced often, after 15-18 thousand kilometers. Although in city conditions, taking into account the uneven operation (standing with the engine running in traffic jams, frequent alternation of acceleration and braking at traffic lights), this mileage can be safely divided into two, so the operating time of nickel spark plugs is normally no more than a year.

IN platinum candles Platinum soldering is done, which increases their service life to 50,000 kilometers. Look at the cost of platinum in any exchanger and you will understand why these solderings make them so expensive.

IN iridium spark plugs already two precious metal: iridium in the form of soldering on the tip of the central electrode and platinum on the side ones. Taking into account the cost of iridium, the price for them increases by 50-60% compared to nickel. But specifications Spark plugs with iridium are such that you can drive with them from 60 to 200 thousand kilometers.

Such candle parameters as: thread diameter; number of the key head for it; threaded skirt length; the gap between the electrodes also refers to their technical characteristics.

Conclusion

Progress does not stand still. New technologies have made it possible, for example, to increase the degree of purification of metals for electrodes to 99.999%. Iridium, platinum and even nickel of such purity can increase the service life of a spark plug by another 15-18%, let’s take as an example DENSO. In addition, engineering thought continued their development, proposing a torch and prechamber type of spark generation, which made the operation of the motors even more stable.

As for the inevitable price increase in this case, the very possibility of looking under the hood as little as possible during the operation of the car already justifies the purchase of each spark plug, even for 10-20 dollars apiece.

Good day! I welcome you to the pages of this blog. Far from it last place, in that the most complex mechanism, like a car, spark plugs occupy. Even more, it is one of the most important elements of the engine. And the quality of engine operation will depend on how well they work and how well they are looked after.

All about spark plugs: principle of operation, features of operation and care.

So. A spark plug is a device that ignites a mixture of fuel and air. gasoline type. Ignition is carried out by an electric charge arising between the electrodes and a voltage of several thousand volts.

Today, special requirements are placed on candles. After all, they are subject to a variety of loads. In particular, changes in operating mode, from driving along highways to full throttle, to quiet trips with frequent stops in city mode. And in the process of all this, thermal, mechanical and chemical loads take their toll.

Selection of spark plugs.

Requirements for modern devices:

1. Good insulating properties. Modern candles must operate at temperatures of 1000 degrees.

2. Reliable performance at high (up to 40,000 Volts) voltage.

3. Resistance to thermal shocks and chemical processes that occur in the combustion chamber.

4. The electrodes and insulator must have excellent thermal conductivity.

Candles should provide stable work engine in each mode: both idle and at maximum performance. Main spark plug characteristics , this is the glow number, operating temperature, thermal characteristics, self-cleaning, spark gap size and the number of side electrodes.

Heat number.

This characteristic shows at what pressure glow ignition occurs in the cylinder, that is, upon contact with the heated areas of the spark plug, and not from a spark. This parameter must clearly correspond to what is recommended for your engine. You can use candles with a slightly higher heat rating, and then only for a while, but in no case should you install candles with a lower value.

Operating temperature of the spark plug.

This indicates the temperature of the working part of the spark plug in a given engine mode. In all operating modes, the temperature should be in the range of 500-900 degrees. In any case, be it idling, or operating mode in full power, the temperature must remain within the specified limits.

Thermal characteristics.

Here we talk about the dependence of the thermal cone of insulation on the operating mode of the engine. To increase operating temperature, the thermal cone is increased. However, you cannot heat it above 900 degrees, as it will cause glow ignition.

Based on their thermal characteristics, candles can be divided into two types: cold and hot.

Cold spark plugs are used if the heating is less than the glow ignition temperature at maximum power engine. Such candles will last less if they are for of this engine“cold”, since they will not heat up to the temperature of self-cleaning from carbon deposits.

Hot spark plugs are intended for those engines that need to reach the decarbonization temperature at low thermal loads. If the spark plugs are “hotter” than necessary, they will cause glow ignition.

Self-cleaning candles.

Quantitative assessment this characteristic does not lend itself. Almost all manufacturers say that their products have the most high degree to self-purification. However, in theory, candles should not be covered with soot at all. But in real conditions this is almost impossible to achieve.

Number of side electrodes.

Typically, there are two electrodes on spark plugs: one central electrode and one side electrode. But now manufacturers have begun to produce four-electrode spark plugs. However, this does not mean that there will be four sparks. Their purpose is to produce stable sparking. This will increase the service life of the spark plugs and improve engine performance at low speeds.

Spark gap.

The spark gap is the distance between the side and central electrodes. Each type of spark plug has its own specific gap that cannot be adjusted. And if you manage to “change” this gap, then the only way to return everything to its place is to purchase new spark plugs.

Operation and care of spark plugs.

Caring for spark plugs is entirely related to the specific operation of the car. Let's look at the main points:

When installing spark plugs, tighten them only to the recommended torque. It's best to take torque wrench, they can limit the tension torque.

Check whether the car's ignition system is working properly. Later, or vice versa early ignition, bad contacts spark plug wires, problems in the high voltage circuit - all this can negatively affect not only the spark plugs, but also the overall operation of the engine.

The quality of the fuel plays a big role. Refuel only at proven gas stations, but only quality fuel. Since if there are iron impurities in gasoline, this will cause reddish soot on the spark plugs.

The average life of a spark plug is from 25,000 to 35,000 kilometers. And in order for them to serve all this time, as well as to ensure high-quality engine operation, they should be removed from time to time and inspected.

When inspecting, pay attention to the ignition cone; carbon deposits may form there, which can tell a lot about the condition of the engine. For example: if the soot is black and oily, it means there is too much oil in the crankcase. Black and dry means too long work on idle speed or insufficient load. White soot indicates overheating or too early ignition timing.

Next, you will have to clean this spark plug from carbon deposits. There are several cleaning methods: physical and chemical. During physical cleaning, carbon deposits are removed using emery cloth or a wire brush. In this case, you should not use any sharp objects, as they can damage the ceramic insulator of the spark plug, which will increase the formation of carbon deposits and cause the spark plug to fail prematurely.

At chemical cleaning the candles are kept in gasoline, dried, then kept in a solution of 20% acetate for half an hour. After this, they are cleaned with a brush, washed with water and dried. Acetic acid should be heated, but not more than 90 degrees. Do all this in a well-ventilated area and away from open flames, as gasoline and fumes acetic acid very dangerous.

After the spark plugs are cleaned, check the gap between the electrodes. You can find the recommended clearance for your vehicle in its owner's manual. You can check the gap size using a round feeler gauge. Well, the adjustment can be done by bending the side electrode. But this should be done carefully, since if the gap is insufficient, a short circuit between the electrodes is possible, and if it is excessive, there may be no spark or big loss its power.

Remember, the spark plug is one of the essential elements engine. And its malfunction will greatly affect its performance. And to prevent this, all the above measures should be followed. Good luck to you!