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

Types of power systems

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

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

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

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

Purpose and composition of the fuel mixture

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

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

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

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

General arrangement of the power system

The engine power system has the following main parts:

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

Carburetor fuel supply system

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

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

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

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

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

Details about the injection system

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

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

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

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

In order for any engine to run like clockwork in perfect condition should be all of its details. Moreover, the systems that ensure its functioning cannot fail. Failure of at least one of them will lead to unstable operation of the device. In the worst case scenario, this can lead to an accident.

One of the most important systems maintenance of the internal combustion engine is the power system. It delivers the fuel inside, where it ignites and turns into mechanical energy.

There are a lot of ICEs. During the development of the automotive industry, scientists came up with many designs, each of which represented another round of industry development. Very few of them went into mass production. Nevertheless, over almost a hundred years of continuous evolution, the following main structures have been identified:

• diesel,
• injection,
• carburetor.

Each of them has its own advantages and disadvantages, moreover, the power supply system of the internal combustion engine in each design is different.

Diesel

Diesel engine power supply system

When the fuel enters the combustion chamber, the power supply system for the diesel engine creates the necessary pressure. Also included in her scope of work are:

• fuel dosage;
• injection of the required amount of fuel liquid for a certain time period;
• spraying and distribution;
• filtering the fuel fluid before entering the pump.

To better understand the structure of the power system diesel engine, you need to know what is diesel fuel by itself. According to its structure, it is a mixture of kerosene and diesel fuel after special treatment. These substances are formed when gasoline is released from oil. In fact, these are leftovers from the main production, which automakers have learned to use effectively.

Diesel fuel circulating in the internal combustion engine system has the following parameters:

• octane number,
• viscosity,
• pour point,
• purity.

Diesel fuel in the internal combustion engine system is divided into three grades depending on the parameters described above:

• summer,
• winter,
• arctic.

In fact, classification can occur according to several criteria and be much deeper. Nevertheless, if we take into account the generally accepted standard, then it will be just that.

Now let's take a closer look at the structure of the internal combustion engine system, it consists of the following elements:

• fuel tank,
• pump,
• high pressure pump,
• nozzles,
• pipelines with low and high pressure,
• outlet pipeline,
• air filter,
• muffler.

All these elements make up common system supply, which ensure stable operation of the engine. If we take into account the design, then it is divided into two subsystems: the one that provides air supply, and the other that implements the flow of fuel.

Fuel circulates through two lines. One has low blood pressure. It stores and filters the fuel fluid, after which it is sent to the high pressure pump.

Fuel enters the combustion chamber directly through a high-pressure line. It is through it that at a certain moment the fuel substance is injected into the chamber.

Important! The pump has two filters. One provides coarse cleaning, and the second fine.

The injection pump supplies power to the injectors. The mode of its operation directly depends on the mode of operation of the engine cylinders. The fuel pump always has an even number of sections. Moreover, their number directly depends on the number of cylinders. More precisely, one parameter corresponds to another.

The injectors are installed in the cylinder heads. It is they who feed the combustion chamber by spraying the fuel substance inside. But there is one small nuance. The fact is that the pump delivers much more fuel than it needs. In other words, the amount of food is too large. In addition, air gets inside, which can interfere with all work.

Attention! To avoid malfunctions, there is a drainage pipeline. It is he who is responsible for ensuring that the air is discharged back into fuel tank.

Injectors in the design responsible for powering the internal combustion engine can be closed and open. In the first case, the openings are closed due to the locking needle. To make this possible, the internal cavity of the parts is connected to the combustion chamber. That's just happening this is when injecting liquid.

The main element in the design of the nozzle is the atomizer. It can have either one or several nozzle holes. Thanks to them, the power structure of the internal combustion engine creates a kind of torch.

To increase power, a turbine is added to the power supply system of the internal combustion engine. It allows the car to gain momentum much faster. By the way, earlier such devices were installed only on racing and trucks. But modern technologies have made it possible not only to make the product many times cheaper, but also significantly reduced the dimensions of the structure.

The turbine is able to supply air through the internal combustion engine power system into the cylinders. The turbocharger is responsible for boost. For its work, it uses exhaust gases. Air enters the combustion chamber under pressure from 0.14 to 0.21 MPa.

The role of a turbocharger is to fill the cylinders with the volume of air necessary for operation. If we talk about power characteristics, then this element in the power supply system of the internal combustion engine allows you to achieve an increase of up to 25-30 percent.

Important! The turbine increases the load on the parts.

Possible malfunctions

Despite a number of visible advantages of the internal combustion engine power supply system, it still has a number of significant drawbacks that can result in a number of malfunctions, the most common ones include:

1. The engine does not want to start. Usually such a malfunction indicates a malfunction in the fuel priming pump. But other options are also possible, for example, improper condition of the nozzles, ignition system, plunger pairs or discharge valve.
2. Uneven engine operation indicates a problem with individual injectors. A leak in the valve can lead to the same results. Also, during the operation of the car, a loosening of the plunger fastening can be observed.
3. The engine does not give the power declared by the manufacturer. Most often, this defect is associated with the fuel priming pump. Nozzles and a broken nozzle can lead to the same result.
4. Knocking when the engine is running, smoke from under the hood. This happens when the fuel is supplied into the system too early, or it does not correspond to the cetane number declared by the manufacturers.
5. Silent pops. The reason for such a malfunction in the internal combustion engine power supply system lies in air leakage.
6. Clutch knock. This happens if the parts of the device are too worn out and there is a strong shrinkage of the springs.

As you can see, malfunctions of the internal combustion engine system can be more than enough. That is why, in order to accurately determine what the matter is, it is necessary to conduct a comprehensive diagnosis. Moreover, some manipulations require special equipment.

Almost all of the problems described above can be corrected. Complete replacement ICE power supply systems are needed only in extreme cases. Moreover, even simple adjustment can fully restore the performance of the automotive unit.

Methods for restoring an internal combustion engine running on a diesel engine

To restore the device to working capacity, it is necessary to clean the purge windows from soot, if it is present there. Check if there is enough grease inside the clutch. If the amount of lubricant is minimal, add it to an acceptable volume.

Most often, the engine knocks and smokes in cases where the fuel you fill has a low cetane number. Fortunately, the recipe for getting out of this situation is quite simple. It is enough to change the fuel fluid to one in which this indicator will be more than 40.

injection engine

Injection engine power system

Injection power systems began to be used in the early 80s of the last century. They replaced designs with carburetors. In a device that works with an injector, each cylinder has its own nozzle.

The injectors are attached to the fuel frame. Inside this design, the fuel fluid is under pressure, which is provided by the pump. The longer the period of time the injector is open, the more fuel is injected inside.

The period that the nozzles are in the open position is controlled by an electronic controller. This is a kind of control unit with a clearly built control algorithm. It coordinates the moment of opening with the readings of the sensors. The work of the electronic filling does not stop for a second. This ensures a stable fuel supply.

Important! A special sensor is responsible for the air flow. It is by cycles that the filling of the cylinders is calculated.

The throttle load is determined by a separate sensor. In fact, he does the math. After that, it sends the data to the controller, where reconciliation takes place and adjustments are made if necessary.

If we talk about the injection power supply system of the internal combustion engine, then it almost completely works due to the indicators of many sensors. The most important are the sensors responsible for the following parameters:

• temperature,
• position crankshaft,
• oxygen concentration,
• ignition knock control.

Moreover, these are only the main sensors. In reality, there are many more of them in the ICE power supply system.

Faults

As mentioned above, the internal combustion engine power system is almost entirely based on the operation of sensors. The greatest harm can be caused by a breakdown of the sensor responsible for the crankshaft. If that happens, you won't even make it to the garage. The same will happen if the fuel pump fails.

Important! If you are going on a long trip, take a spare fuel pump with you. This is the second heart of your car.

If we talk about the safest malfunctions of the internal combustion engine power system, then this, of course, is a breakdown of the phase sensor. This defect will cause the least damage to the car. In addition, repairs will take a minimum of time.

Important! About a malfunction of the phase sensor says unstable work nozzles. Usually this is evidenced by a sharp jump in gasoline consumption.

Carburetor engines

Supply system

The first carburetor engine was created in the last century by Gottlieb Daimler. The power supply system of a carburetor engine is not particularly complex and consists of such elements as:

• fuel tank,
• pump,
• fuel line,
• filters,
• carburetor.

The tank capacity is usually about 40-80 liters in cars with carburetor power systems for internal combustion engines. This device is in most cases mounted at the rear of the machine for greater safety.

From the fuel tank, gasoline enters the carburetor. The fuel line connects these two devices. She goes under vehicle. During transportation, the fuel passes through several filters. The pump is responsible for supply.

Faults

The design is the oldest of all three. Despite this, its simplicity helps to significantly reduce the risk of any breakdown. Unfortunately, not a single internal combustion engine power system, including a carburetor, is insured against malfunctions, such defects can occur with it:

• lean fuel mixture
• cutting off the fuel supply
• gasoline leak.

Leaks are easily visible to the naked eye. Stopping the supply of fuel fluid will not allow the car to budge. If the carburetor sneezes, then the fuel mixture is lean.

Results

Over the years of development of the automotive industry, many internal combustion engine power systems have been created. The first was the carburetor. She is the most simple and unpretentious. Its successors are diesel and injection.

Gasoline engine fuel supply system⭐ is designed to accommodate and purify fuel, as well as prepare a combustible mixture of a certain composition and supply it to the cylinders in the required amount in accordance with the engine operating mode (with the exception of direct injection engines, the power system of which ensures that gasoline enters the combustion chamber in the required amount and under sufficient pressure).

Petrol, like diesel fuel, is a product of the distillation of oil and consists of various hydrocarbons. The number of carbon atoms in gasoline molecules is 5 - 12. Unlike diesel engines in gasoline engines, fuel should not be intensively oxidized during compression, as this can lead to detonation (explosion), which will adversely affect performance, efficiency and power engine. The knock resistance of gasoline is measured by the octane number. The larger it is, the higher the knock resistance of the fuel and the allowable compression ratio. Modern gasolines have an octane rating of 72-98. In addition to anti-knock resistance, gasoline must also have low corrosivity, low toxicity and stability.

The search (based on environmental considerations) for alternatives to gasoline as the main fuel for internal combustion engines has led to the creation of ethanol fuel, consisting mainly of ethyl alcohol, which can be obtained from plant biomass. Distinguish pure ethanol (international designation - E100), containing only ethyl alcohol; and a mixture of ethanol with gasoline (most often 85% ethanol with 15% gasoline; designation - E85). In terms of its properties, ethanol fuel approaches high-octane gasoline and even surpasses it in octane number (more than 100) and calorific value. So this species fuel can be successfully used instead of gasoline. The only disadvantage of pure ethanol is its high corrosiveness, which requires additional protection against corrosion of the fuel equipment.

High requirements are imposed on the units and components of the fuel supply system of a gasoline engine, the main of which are:

• tightness
• fuel dosing accuracy
• reliability
• serviceability

Currently, there are two main methods for preparing a combustible mixture. The first of them is associated with the use of a special device - a carburetor, in which air is mixed with gasoline in a certain proportion. The second method is based on the forced injection of gasoline into the engine intake manifold through special nozzles (injectors). Such engines are often referred to as injection engines.

Regardless of the method of preparing a combustible mixture, its main indicator is the ratio between the mass of fuel and air. The mixture, when ignited, should burn very quickly and completely. This can be achieved only with good mixing in a certain proportion of air and gasoline vapors. The quality of the combustible mixture is characterized by the excess air coefficient a, which is the ratio of the actual mass of air per 1 kg of fuel in this mixture to the theoretically necessary one, which ensures complete combustion of 1 kg of fuel. If 14.8 kg of air falls on 1 kg of fuel, then such a mixture is called normal (a \u003d 1). If there is a little more air (up to 17.0 kg), the mixture is lean, and a = 1.10 ... 1.15. When there is more than 18 kg of air and a > 1.2, the mixture is called lean. Reducing the proportion of air in the mixture (or increasing the proportion of fuel) is called its enrichment. At a = 0.85 ... 0.90 the mixture is enriched, and at a< 0,85 - богатая.

When a mixture of normal composition enters the engine cylinders, it works stably with average power and economy. When running on a lean mixture, engine power is slightly reduced, but its efficiency is noticeably increased. On the lean mixture the engine is unstable, its power drops, and the specific fuel consumption increases, so excessive lean mixture is undesirable. When an enriched mixture enters the cylinders, the engine develops highest power but fuel consumption also increases. When running on a rich mixture, gasoline burns incompletely, which leads to a decrease in engine power, an increase in fuel consumption and the appearance of soot in the exhaust tract.

Carburetor power systems

Let us first consider carburetor power systems, which until recently were widespread. They are simpler and cheaper than injector ones, do not require highly qualified maintenance during operation, and in some cases are more reliable.

Carburetor engine fuel supply system includes fuel tank 1, coarse 2 and fine 4 fuel filters, fuel priming pump 3, carburetor 5, inlet pipeline 7 and fuel lines. When the engine is running, fuel from tank 1 is supplied by pump 3 through filters 2 and 4 to the carburetor. There it is mixed in a certain proportion with the air coming from the atmosphere through the air cleaner 6. The combustible mixture formed in the carburetor through the intake manifold 7 enters the engine cylinders.

fuel tanks in power plants with carburetor engines, they are similar to the tanks of diesel fuel systems. The difference between the tanks for gasoline is only their better tightness, which does not allow gasoline to leak out even if the vehicle rolls over. To communicate with the atmosphere, two valves are usually installed in the tank filler cap - inlet and outlet. The first of them provides air to the tank as the fuel is consumed, and the second, loaded with a stronger spring, is designed to communicate the tank with the atmosphere when the pressure in it is higher than atmospheric (for example, at high ambient temperature).

Filters for carbureted engines similar to filters used in diesel fuel systems. Lamellar-slit and mesh filters are installed on trucks. For fine cleaning cardboard and porous ceramic elements are used. In addition to special filters, individual units of the system have additional filter screens.

Fuel pump serves to force the supply of gasoline from the tank to the float chamber of the carburetor. Carburetor engines usually use an eccentric-driven diaphragm pump. camshaft.

Depending on the engine operating mode, the carburetor allows you to prepare a mixture of normal composition (a \u003d 1), as well as a lean and enriched mixture. At low and medium loads, when you do not need to develop maximum power, you should cook in the carburetor and apply a lean mixture to the cylinders. At high loads (the duration of their action, as a rule, is short), it is necessary to prepare an enriched mixture.

Rice. Scheme of the fuel supply system of the carburetor engine:
1 - fuel tank; 2 - filter by fuel cleaning pipe; 3 - fuel priming pump; 4 - fine filter; 5 - carburetor; 6 - air cleaner; 7 - intake manifold

In the general case, the composition of the carburetor includes the main metering and starting devices, systems idle move and forced idling, an economizer, an accelerator pump, a balancing device and a limiter for the maximum speed of the crankshaft (for trucks). The carburetor may also contain an econostat and a height corrector.

Main dosing device functions in all main modes of engine operation in the presence of vacuum in the diffuser of the mixing chamber. Main constituent parts The devices are a mixing chamber with a diffuser, a throttle valve, a float chamber, a fuel jet and atomizer tubes.

Launcher devices o is designed to ensure the start of a cold engine, when the speed of the crankshaft rotated by the starter is low and the vacuum in the diffuser is small. In this case, for a reliable start, it is necessary to supply a highly enriched mixture to the cylinders. The most common starting device is air damper installed in the intake pipe of the carburetor.

Idle system serves to ensure the operation of the engine without load with a low crankshaft speed.

Forced idle system allows you to save fuel while driving in engine braking mode, i.e. when the driver releases the accelerator pedal associated with the carburetor throttle while in gear.

Economizer designed for automatic enrichment of the mixture when the engine is running at full load. In some types of carburetors, in addition to the economizer, an econostat is used to enrich the mixture. This device delivers additional fuel from float chamber into the mixing room only with a significant vacuum in the upper part of the diffuser, which is possible only with the throttle valve fully open.

accelerator pump provides forced injection into the mixing chamber of additional portions of fuel with a sharp opening of the throttle. This improves the throttle response of the engine and, accordingly, the vehicle. If accelerator pump was not in the carburetor, then with a sharp opening of the damper, when the air flow is growing rapidly, due to the inertia of the fuel, the mixture at the first moment would be very depleted.

Balancing device serves to ensure the stability of the carburetor. It is a tube connecting the intake pipe of the carburetor with the air cavity of a sealed (not communicating with the atmosphere) float chamber.

Engine speed limiter mounted on truck carburetors. The most widely used restrictor is the pneumatic centrifugal type.

Fuel injection systems

Injection fuel systems are currently used much more often than carbureted ones, especially on gasoline engines cars. Gasoline injection into the intake manifold of an injection engine is carried out using special electromagnetic nozzles (injectors) installed in the cylinder head and controlled by a signal from the electronic unit. This eliminates the need for a carburetor, since the combustible mixture is formed directly in the intake manifold.

There are single and multi-point injection systems. In the first case, only one nozzle is used to supply fuel (with its help, a working mixture is prepared for all engine cylinders). In the second case, the number of nozzles corresponds to the number of engine cylinders. Injectors are installed in close proximity to the intake valves. Fuel is injected in a finely atomized form onto the outer surfaces of the valve heads. Atmospheric air entrained in the cylinders due to vacuum in them during intake washes away fuel particles from the valve heads and contributes to their evaporation. Thus, the air-fuel mixture is prepared directly at each cylinder.

In an engine with multi-point injection, when power is supplied to the electric fuel pump 7 through the ignition lock 6, gasoline from the fuel tank 8 through the filter 5 is fed into the fuel rail 1 (injector rail), common to all electromagnetic injectors. The pressure in this rail is regulated by regulator 3, which, depending on the vacuum in the inlet pipe 4 of the engine, sends part of the fuel from the rail back to the tank. It is clear that all injectors are under the same pressure, equal to the pressure of the fuel in the rail.

When it is required to supply (inject) fuel, an electric current is supplied to the solenoid coil of the injector 2 from the electronic unit of the injection system for a strictly defined period of time. The core of the electromagnet, connected to the nozzle needle, is retracted, opening the way for fuel into the intake manifold. The duration of the electric current supply, i.e. the duration of the fuel injection, is controlled by the electronic unit. The program of the electronic unit in each mode of engine operation ensures optimal fuel supply to the cylinders.

Rice. Scheme of the fuel supply system of a gasoline engine with multipoint injection:
1 - fuel rail; 2 - nozzles; 3 - pressure regulator; 4 - inlet pipe of the engine; 5 - filter; 6 - ignition switch; 7 - fuel pump; 8 - fuel tank

In order to identify the operating mode of the engine and, in accordance with it, calculate the injection duration, in the electronic unit signals are received from various sensors. They measure and convert the values ​​of the following engine operation parameters into electrical impulses:

• throttle angle
• degree of vacuum in the intake manifold
• crankshaft speed
• intake air and coolant temperature
• exhaust oxygen concentration
• Atmosphere pressure
• battery voltage
• and etc.

Engines with gasoline injection into the intake manifold have a number of undeniable advantages over carbureted engines:

• the fuel is distributed more evenly over the cylinders, which increases the efficiency of the engine and reduces its vibration, due to the absence of a carburetor, the resistance of the intake system is reduced and the filling of the cylinders is improved
• it becomes possible to slightly increase the compression ratio of the working mixture, since its composition in the cylinders is more homogeneous
• the optimal correction of the composition of the mixture is achieved when switching from one mode to another
• provides better engine response
• exhaust gases contain less harmful substances

At the same time, power systems with gasoline injection into the intake manifold have a number of disadvantages. They are complex and therefore relatively expensive. Maintenance of such systems requires special diagnostic tools and devices.

The most promising fuel supply system gasoline engines At present, a rather complex system with direct injection of gasoline into the combustion chamber is considered, which allows the engine to operate for a long time on a very lean mixture, which increases its efficiency and environmental performance. At the same time, due to the existence of a number of problems in the system direct injection have not yet been widely adopted.

Purpose, arrangement and operation of the fuel supply system

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

An all-mode centrifugal direct-acting speed controller is installed on the KamAZ engine. It is located in the collapse of the injection pump housing, and the control is displayed on the pump cover.

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

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

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

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

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

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

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

Fuel supply is controlled by foot and hand drives.

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

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

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

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

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

An increase in the sensitivity of the regulator is ensured by high-quality processing of the rubbing surfaces of the moving parts of the regulator and the pump, their reliable lubrication and an increase in the angular velocity of rotation of the cargo clutch by a factor of two in relation to the camshaft of the pump due to gear ratio governor drive gears.

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

For everyone modern cars mobiles With gasoline engines a fuel injection system is used, since it is more advanced than a carburetor, despite the fact that it is structurally more complex.

The injection engine is not new, but it became widespread only after the development of electronic technology. This is because it was very difficult to mechanically organize the control of a system with high accuracy. But with the advent of microprocessors, this became quite possible.

The injection system is different in that gasoline is supplied in strictly specified portions forcibly into the manifold (cylinder).

The main advantage that the injection power system has is the observance of the optimal proportions of the constituent elements of the combustible mixture in different operating modes. power plant. This results in better power output and economical petrol consumption.

System device

The fuel injection system consists of electronic and mechanical components. The first controls the parameters of work power unit and on their basis gives signals for actuation of the executive (mechanical) part.

The electronic component includes a microcontroller (electronic control unit) and a large number of tracking sensors:

• crankshaft position;
• mass air flow;
• throttle position;
• detonation;
• coolant temperature;
• air pressure in the intake manifold.

Injector system sensors

Some cars may have a few more additional sensors. All of them have one task - to determine the parameters of the power unit and transfer them to the computer

As for the mechanical part, it includes the following elements:

• electric fuel pump;
• fuel lines;
• filter;
• pressure regulator;
• fuel rail;
• nozzles.

Simple fuel injection system

How it all works

Now consider the principle of operation of the injection engine separately for each component. With the electronic part, in general, everything is simple. Sensors collect information about the speed of rotation of the crankshaft, air (entered the cylinders, as well as its residual part in the exhaust gases), throttle position (associated with the accelerator pedal), coolant temperature. These data are constantly transmitted by the sensors to the electronic unit, due to which a high accuracy of gasoline dosing is achieved.

The ECU compares the information coming from the sensors with the data entered in the cards, and already on the basis of this comparison and a number of calculations, it controls the executive part. The so-called cards with optimal parameters the operation of the power plant (for example, for such conditions it is necessary to apply so much gasoline, for others - so much).

First injection engine 1973 Toyota

To make it clearer, let's consider in more detail the algorithm of the electronic unit, but according to a simplified scheme, since in reality a very large amount of data is used in the calculation. In general, all this is aimed at calculating the temporal length of the electrical pulse that is applied to the injectors.

Since the circuit is simplified, we assume that the electronic unit only calculates according to several parameters, namely the base time pulse length and two coefficients - the coolant temperature and the oxygen level in the exhaust gases. To obtain the result, the ECU uses a formula in which all available data are multiplied.

To obtain the base pulse length, the microcontroller takes two parameters - the speed of rotation of the crankshaft and the load, which can be calculated from the pressure in the manifold.

For example, the engine speed is 3000, and the load is 4. The microcontroller takes this data and compares it with the table entered on the map. In this case, we get a base time pulse length of 12 milliseconds.

But for calculations, it is also necessary to take into account the coefficients, for which readings are taken from the coolant temperature sensors and the lambda probe. For example, the temperature is 100 degrees, and the oxygen level in the exhaust gases is 3. The ECU takes this data and compares it with several more tables. Assume that the temperature coefficient is 0.8 and the oxygen coefficient is 1.0.

Having received all the necessary data, the electronic unit performs the calculation. In our case, 12 is multiplied by 0.8 and by 1.0. As a result, we get that the impulse should be 9.6 milliseconds.

The described algorithm is very simplified, but in fact, more than a dozen parameters and indicators can be taken into account in the calculations.

Since the data is constantly sent to the electronic unit, the system almost instantly responds to changes in the engine operating parameters and adjusts to them, ensuring optimal mixture formation.

It is worth noting that the electronic unit controls not only the fuel supply, its task also includes adjusting the ignition angle to ensure optimal performance motor.

Now about the mechanical part. Everything is very simple here: a pump installed in the tank pumps gasoline into the system, and under pressure to ensure forced supply. The pressure must be certain, so a regulator is included in the circuit.

On the highways, gasoline is supplied to the ramp, which connects all the nozzles. An electrical impulse supplied from the computer leads to the opening of the nozzles, and since gasoline is under pressure, it is simply injected through the opened channel.

Types and types of injectors

There are two types of injectors:

1. With single injection. Such a system is obsolete and is no longer used on cars. Its essence is that there is only one nozzle installed in the intake manifold. This design did not provide an even distribution of fuel over the cylinders, so its operation was similar to a carburetor system.
2. Multi-point injection. On modern cars, this type is used. Here, each cylinder has its own nozzle, so this system is characterized by high dosing accuracy. Nozzles can be installed both in the intake manifold and in the cylinder itself ( injector).

On a multi-point fuel injection system, several types of injection can be used:

1. Simultaneous. In this type, the impulse from the ECU goes to all the injectors at once, and they open together. Now such an injection is not used.
2. Paired, he is pairwise-parallel. In this type, the nozzles work in pairs. It is interesting that only one of them supplies fuel directly in the intake stroke, while the second cycle does not match. But since the engine is 4-stroke, with a valve gas distribution system, the injection mismatch in cycle does not affect the performance of the engine.
3. Phased. In this type, the ECU sends open signals for each injector separately, so the injection occurs with the same stroke.

It is noteworthy that a modern fuel injection system can use several types of injection. So, in normal mode, phased injection is used, but in the event of a transition to emergency operation (for example, one of the sensors failed), the injection engine switches to paired injection.

Sensor Feedback

One of the main sensors, on the basis of which the ECU regulates the opening time of the injectors, is a lambda probe installed in the exhaust system. This sensor determines the residual (not burned) amount of air in the gases.

The evolution of the lambda probe from Bosch

Thanks to this sensor, the so-called "feedback" is provided. Its essence is this: the ECU did all the calculations and gave an impulse to the injectors. Fuel entered, mixed with air and burned. The resulting exhaust gases with unburned particles of the mixture are removed from the cylinders through the exhaust system exhaust gases in which the lambda probe is installed. Based on his readings, the ECU determines whether all calculations were carried out correctly and, if necessary, makes adjustments to obtain the optimal composition. That is, on the basis of the already completed stage of fuel supply and combustion, the microcontroller makes calculations for the next one.

It should be noted that during the operation of the power plant there are certain modes in which the readings oxygen sensor will be incorrect, which may disrupt the operation of the motor or a mixture with a certain composition is required. In such modes, the ECU ignores information from the lambda probe, and it sends signals for the supply of gasoline based on the information stored in the maps.

In different modes, the feedback works like this:

• Starting the motor. In order for the engine to be able to start, an enriched combustible mixture with an increased percentage of fuel is needed. And the electronic unit provides this, and for this it uses the given data, and it does not use information from the oxygen sensor;
• Warming up To make the injection engine gain faster operating temperature The ECU sets the engine speed to high. At the same time, it constantly monitors its temperature, and as it warms up, it adjusts the composition of the combustible mixture, gradually depleting it until its composition becomes optimal. In this mode, the electronic unit continues to use the data specified in the cards, still not using the readings of the lambda probe;
• Idling. In this mode, the engine is already fully warmed up, and the exhaust gas temperature is high, so the conditions for the correct operation of the lambda probe are met. The ECU is already starting to use the readings of the oxygen sensor, which allows you to set the stoichiometric composition of the mixture. With this composition, the greatest power output of the power plant is provided;
• Movement with a smooth change in engine speed. To achieve economical fuel consumption at maximum power output, a mixture with a stoichiometric composition is needed, therefore, in this mode, the ECU regulates the supply of gasoline based on the readings of the lambda probe;
• A sharp increase in turnover. In order for the injection engine to respond normally to such an action, a slightly enriched mixture is needed. To provide it, the ECU uses card data, and not lambda probe readings;
• Motor braking. Since this mode does not require power output from the motor, it is enough that the mixture simply does not allow the power plant to stop, and a lean mixture is also suitable for this. For its manifestation, the readings of the lambda probe are not needed, so the ECU does not use them.

As you can see, although the lambda probe is very important for the operation of the system, the information from it is not always used.

Finally, we note that the injector, although a structurally complex system and includes many elements, the failure of which immediately affects the operation of the power plant, but it provides a more rational consumption of gasoline, and also increases the environmental friendliness of the car. Therefore, there is no alternative to this power system yet.

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