- fuel supply system, including fuel tank 7 (figure 4.11), fuel pump 9 with built-in fuel pressure regulator, pipelines 1, 4 and 5, fuel rail 5 (figure 4.12) with injectors 1, as well as fuel filter 6 (see figure 4.11);
- air supply system including air filter 6 (figure 4.13), air supply pipe 4, throttle assembly 7;
- fuel vapor recovery system including adsorber 1 (figure 4.14), purge valve 7 of the adsorber, separator 9 of fuel vapors, gravity valve 11 and connecting pipelines 4, 5, 6 and 14.
The functional purpose of the fuel supply system is to ensure the supply of the required amount of fuel to the engine in all operating modes. The engine is equipped with an electronic control system with distributed fuel injection. In the distributed fuel injection system, the functions of mixture formation and metering of the fuel-air mixture supply to the engine cylinders are separated: the injectors perform metered injection of fuel into the intake pipe, and the amount of air required at each moment of engine operation is supplied by a system consisting of a throttle assembly and an idle speed regulator. This control method makes it possible to ensure the optimal composition of the combustible mixture at each specific moment of engine operation, which allows for maximum power with the lowest possible fuel consumption and low toxicity of exhaust gases. The fuel injection system and ignition system are controlled by an electronic engine control unit, which continuously monitors the engine load, vehicle speed, engine thermal state, and the optimal combustion process in the engine cylinders using appropriate sensors.
A special feature of the vehicle's fuel injection system is the synchronicity of the injectors' operation in accordance with the valve timing (the engine control unit receives information from the phase sensor). The controller turns on the injectors sequentially, and not in pairs, as in asynchronous injection systems. Each injector is activated after 720° of crankshaft rotation. However, in starting modes and dynamic engine operating modes, an asynchronous method of fuel supply is used without synchronization with the rotation of the crankshaft.
The main sensor for the fuel injection system is the exhaust gas oxygen concentration sensor (lambda probe). It is installed in the engine exhaust manifold and, together with the engine control unit and injectors, forms a control circuit for the composition of the fuel-air mixture supplied to the engine. Based on the sensor signals, the engine control unit determines the amount of unburned oxygen in the exhaust gases and, accordingly, evaluates the optimal composition of the fuel-air mixture entering the engine cylinders at each moment in time. Having recorded a deviation of the composition from the optimal 1:14 (fuel/air), to ensure the most efficient operation of the catalytic converter of exhaust gases, the control unit changes the composition of the mixture using injectors. Since the oxygen concentration sensor is included in the feedback circuit of the engine control unit, the control loop for the air-fuel mixture composition is closed. A special feature of the car engine management system is the presence (in addition to the control sensor) the second, diagnostic oxygen concentration sensor, installed at the outlet of the neutralizer. The composition of the gases that pass through the neutralizer determines its efficiency.
Fuel tank 7 (see figure 4.11) welded, stamped, installed on the vehicle under the body floor in its rear part and secured with two steel clamps 15. To prevent fuel vapors from entering the atmosphere, the fuel tank is connected through a separator 9 (see figure 4.13) fuel vapors and gravity valve 11 pipeline 14 with adsorber 1. A protective screen 16 is installed under the fuel tank (see figure 4.11). An electric fuel pump 9 is installed in the flange opening in the upper part of the fuel tank, combining the fuel pump itself, the fuel level indicator sensor and the fuel pressure regulator in a single module. At the rear of the fuel tank there is a branch pipe for connecting the filler pipe 12. From the fuel pump, fuel is supplied to the fuel filter 6, installed at the bottom of the fuel tank, and from there it enters the fuel rail 5 (see figure 4.12), fixed to the engine intake pipe. From the fuel rail, fuel is injected by injectors 1 into the intake pipe, with the fuel spray directed at the intake valve. Excess fuel is drained into the fuel tank through the fuel pressure regulator installed in the fuel pump. This fuel pressure regulator installation scheme, in addition to eliminating the long return drain line, prevents the fuel temperature in the fuel tank from rising, which causes excessive vaporization.
Fuel pump 9 (see figure 4.11) submersible, electric-driven, rotary type, with a coarse fuel filter. The fuel pump supplies fuel and is installed in the fuel tank, which reduces the possibility of vapor lock, since the fuel is supplied under pressure, and not under vacuum. From the fuel tank, fuel is supplied through the main fuel filter to the injector rail under a pressure of more than 380 kPa.
Fuel filter 6 (see figure 4.11) fine cleaning - full-flow, fixed in bracket 3 on the fuel tank. The fuel filter is non-separable, with a steel housing and a paper filter element.
Fuel rail 5 (see figure 4.12), which is a hollow tubular part, serves to supply fuel to the injectors and is fixed to the inlet pipe. The engine uses a drainless fuel system. The pressure in the fuel rail is maintained by a fuel pressure regulator installed in the electric fuel pump module. Injectors 1 are attached to the fuel rail with clamps 2 through sealing rubber rings 3. To equalize the fuel pressure in the injectors, fuel is supplied to the middle part of the fuel rail, and not to one end, as in previous VAZ injection engines.
Nozzles with their nozzles they enter the holes of the intake pipe. The injectors are sealed in the inlet pipe openings with rubber sealing rings. The injector is designed for metered injection of fuel into the engine cylinders and is a high-precision electromechanical valve in which the shut-off valve needle is pressed against the seat by a spring. When an electrical impulse is applied from the control unit to the electromagnet winding, the needle rises and opens the nozzle hole, through which fuel is supplied to the engine intake pipe. The amount of fuel injected by the injector depends on the duration of the electrical pulse.
Fuel pressure regulator is installed in the fuel pump module and is designed to maintain constant fuel pressure in the fuel rail. The fuel pressure regulator is connected to the beginning of the supply line (immediately after the fuel filter) and is a relief valve with a spring that has a strictly calibrated force.
Air filter 6 (see figure 4.13) mounted in the front of the engine compartment on three rubber mounts. The air filter element is paper, flat, with a large filtering surface area. The air filter is connected to the throttle assembly 7 by a rubber corrugated air supply pipe 4. A mass air flow sensor 5 is installed between the pipe and the filter, see. "Electronic engine management system (fuel injection system)".
Throttle assembly fixed to the intake module. It controls the amount of air entering the intake manifold. The air supply to the engine is controlled by a throttle valve connected to the accelerator pedal drive.
The throttle assembly includes a throttle position sensor and an idle speed control valve. In the flow part of the throttle assembly (before and after the throttle valve) there are vacuum extraction holes required for the operation of the crankcase ventilation and fuel vapor recovery systems.
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Idle speed control valve regulates the crankshaft speed in idle mode by controlling the amount of air supplied bypassing the closed throttle valve. The idle speed controller consists of a two-pole stepper motor and a cone valve connected to it. The valve extends or retracts according to signals from the engine control unit.
When the idle speed control needle is fully extended (which corresponds to 0 steps), the valve completely blocks the air passage. When the needle is pushed in, an air flow is provided proportional to the number of steps the needle moves away from the seat.
By changing the opening and closing of the idle speed control valve, the control unit compensates for a significant increase or decrease in the amount of air supplied, caused by its suction through a leaky intake system or, conversely, a clogged air filter.
Fuel vapor recovery system prevents fuel vapors from escaping from the engine's fuel system into the atmosphere, which have an adverse effect on the environment.
The fuel vapor recovery system uses a carbon adsorber method of vapor absorption 1 (see figure 4.14). The carbon adsorber is installed on the fuel tank and is connected by pipelines to the fuel vapor separator 9, installed in the niche of the right rear wheel, and to the adsorber purge valve 7, located in the engine compartment. The electromagnetic valve for purging the carbon adsorber switches the operating modes of the system based on signals from the engine control unit.
Fuel vapors from the fuel tank are partially condensed in separator 9, the condensate is drained back into the fuel tank via pipeline 12. The remaining vapors pass through gravity valve 11, installed in the separator, into adsorber 1 via pipeline 14. The second nipple of the adsorber is connected by a hose to valve 7 for purging the adsorber, and the third one is connected to the atmosphere. When the engine is not running, the third nipple is closed by an electromagnetic valve, in which case the adsorber does not communicate with the atmosphere. When the engine is running, the engine control unit begins to send control pulses to the valve.
The valve connects the adsorber cavity with the atmosphere, and the sorbent is purged: gasoline vapors are discharged through hose 6 and throttle assembly 8 into the intake module.
Malfunctions of the fuel vapor recovery system lead to unstable idle speed, engine stalling, increased toxicity of exhaust gases and deterioration of driving performance of the vehicle.
Figure 4.11. Fuel supply system: 1 - fuel supply line; 2 - bracket; 3 - fuel filter mounting bracket; 4 - middle fuel line; 5 - fuel line from the filter to the fuel pump; 6 - fuel filter; 7 - fuel tank; 8 - fuel pump sealing ring; 9 - fuel pump; 10 - fuel pump mounting clamping ring; 11 - Fuel tank filler cap; 12 - Filler pipe seal; 13 - fuel tank filler pipe; 14 - air bleed hose; 15 - fuel tank mounting clamp; 16 - Fuel tank protective screen; 17 - protective screen of fuel lines
Figure 4.12. Fuel rail and injectors: 1 - nozzle; 2 - nozzle retainer; 3 - sealing ring; 4 - fuel pressure control nipple; 5 - fuel rail
Figure 4.13. Air supply system: 1 - coolant pump supply pipe; 2 - throttle body heating hoses; 3 - air supply pipe mounting clamps; 4 - air supply pipe; 5 - mass air flow sensor; 6 - air filter; 7 - throttle assembly; 8 - throttle assembly sealing gasket; 9 - intake module; 10 - engine cooling system outlet pipe; 11 - hose clamp
Figure 4.14. Fuel vapor recovery system: 1 - adsorber; 2 - fuel tank; 3 - bracket; 4 - steam pipe from the adsorber to the purge valve; 5 - steam pipe; 6 - pipeline hose from the purge valve to the throttle assembly; 7 - purge valve of the adsorber; 8 - throttle assembly; 9 - fuel vapor separator; 10 - valve gasket; 11 - gravity valve; 12 - fuel vapor supply hose to the separator; 13 - fuel tank filler pipe; 14 - steam line from separator to adsorber