Figure 5.19. Fuel supply system: 1 – fuel pipes (plastic); 2 – fuel filter; 3 – fuel filter mounting bracket; 4 – fuel pump sealing ring; 5 – fuel pump; 6 – distance ring; 7 – fuel pump mounting clamp ring; 8 – filler pipe hose; 9 – Fuel tank filler cap; 10 – lining of the filler neck; 11 – clamp; 12 – fuel tank filler pipe; 13 – air bleed hose; 14 – fuel tank mounting clamp; 15 – connector (quick release connector); 16 – fuel tank; 17 – fuel pipes (metal); 18 – fuel supply hose; 19 – bracket; 20 – injectors; 21 – fuel rail
Fuel supply system, including fuel tank 16 (figure 5.19), fuel pump 5 with built-in fuel pressure regulator, fuel pipes 1 and 17, hose 18, fuel rail 2 (figure 5.20) with injectors 1, as well as fuel filter 2 (see figure 5.19);
Figure 5.20. Fuel rail and injectors: 1 – nozzle; 2 – fuel rail; 3 – sealing ring; 4 – nozzle retainer; 5 – fuel pressure control nipple cap
Figure 5.21. Air supply system: 1 – mass air flow sensor; 2 – sealing sleeve; 3 – air filter; 4 – throttle assembly; 5 – intake manifold; 6 – idle speed regulator or additional air regulator; 7 – hose clamps; 8 – thermostat; 9 – Coolant pump supply pipe; 10 – throttle body heating hoses; 11 – air supply hose; 12 – air supply hose fastening clamps
Air supply system consisting of air filter 3 (figure 5.21), air supply hose 11, throttle unit 4;
Figure 5.22. Fuel vapor recovery system: 1 – front steam pipe; 2 – adsorber and purge valve tube; 3 – adapter; 4 – hoses; 5 – purge valve of the adsorber; 6 – clamp; 7 – fuel drain pipe; 8 – separator bracket; 9 – valve gasket; 10 – gravity valve; 11 – fuel vapor separator; 12 – rear steam pipe; 13 – middle steam pipe; 14 – steam pipe; 15 – adsorber
Fuel vapor recovery system including adsorber 15 (figure 5.22), purge valve 5 of the adsorber, separator 11 of fuel vapors, gravity valve 10, connecting vapor lines 1, 2, 12, 13, 14 and hoses 4.
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 the engine electronic control unit (ECU), which continuously monitors the engine load, vehicle speed, engine thermal state, and the optimal combustion process in the engine cylinders using appropriate sensors.
The peculiarity of the injection system of the VAZ-2170 Lada Priora 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 or simultaneously, as in asynchronous injection systems. Each injector is activated after 720° of crankshaft rotation. However, in starting modes and in 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 oxygen concentration sensor in exhaust gases (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 engine management system of the VAZ-2170 Lada Priora is the presence, in addition to the control sensor, of a 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 16 (see figure 5.19) welded, stamped, installed under the body floor in its rear part and secured with two steel clamps 14. To prevent fuel vapors from entering the atmosphere, the tank is connected through a fuel vapor separator 11 (see figure 5.22) and gravity valve 10 steam lines 12, 13, 14 and 1 with adsorber 15. An electric module of the electric fuel pump is installed in the flange hole in the upper part of the tank (fuel pump) 5 (see figure 5.19), combining the pump itself, the fuel level indicator sensor and the fuel pressure regulator. At the rear of the tank there is a branch pipe for connecting the filler pipe 12. From the pump, fuel is supplied to the fuel filter 2, installed below on the base of the body, and from there it enters the fuel rail 21, fixed to the cylinder head of the engine. From the fuel rail, fuel is injected by injectors 20 into the intake channels of the cylinder head, 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 electric fuel pump module. This fuel pressure regulator installation scheme, in addition to eliminating the long return drain line, prevents the fuel temperature in the tank from rising, which causes excessive vaporization.
Fuel pump (electric fuel pump module) 5 (see figure 5.19) submersible, vortex type, with a coarse fuel filter. The 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. The fuel pump supplies fuel from the fuel tank through the main fuel filter to the injector rail under a pressure of more than 380 kPa.
Fuel filter 2 (see figure 5.19) fine cleaning - full-flow, fixed in bracket 3 on the base of the body next to the fuel tank. The filter is non-separable and has a steel body with a paper filter element.
Fuel rail 21 (see figure 5.19), which is a hollow tubular part, serves to supply fuel to the injectors and is fixed to the cylinder head. The engine uses a drainless fuel system; the pressure in the rail is maintained by a fuel pressure regulator installed in the electric fuel pump module. Injectors 20 are attached to the ramp with clamps 4 (see figure 5.20) through rubber sealing rings. To equalize the pressure in the injectors, fuel is supplied to the middle part of the ramp.
Nozzles with their nozzles they enter the holes located above the intake channels of the cylinder head. The nozzle holes are sealed 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 regulator is connected to the beginning of the supply line immediately after the fuel filter and is a bypass valve with a spring that has a strictly calibrated force.
Air filter 3 (see figure 5.21) mounted in the front of the engine compartment on three rubber mounts. The filter element is paper, flat, with a large filtering surface area. The filter is connected by a rubber corrugated air supply hose 11 to the throttle assembly 4. A mass air flow sensor 1 is installed between the hose and the filter (see "Electronic Engine Management System (EEMS)").
Throttle assembly 4 (see figure 5.21) is fixed to the intake manifold 5. It measures the amount of air entering the intake pipe. The air supply to the engine is controlled by a throttle valve connected to the accelerator pedal drive.
The throttle assembly includes 4 sensors (figure 5.23) throttle position and idle speed control 5. 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.
Idle speed controller 5 (see figure 5.23) regulates the crankshaft speed at idle speed by controlling the amount of air supplied bypassing the closed throttle valve. It 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 regulator 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 regulator 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 fuel system into the atmosphere, which have an adverse effect on the environment.
The system uses the carbon vapor absorption method adsorber 15 (see figure 5.22). It is installed in the engine compartment on the radiator trim panel and is connected by steam lines to the fuel vapor separator 11, installed in the niche of the left rear wheel, and to the purge valve 5 of the adsorber, located in the engine compartment on the decorative engine casing. The electromagnetic valve for purging the adsorber switches the operating modes of the system according to signals from the engine control unit.
Fuel vapors from the tank partially condense in separator 11, the condensate drains back into the tank through pipe 7. The remaining vapors pass through gravity valve 10 installed in the separator, through steam pipes 12, 13, 14, 1 and enter the adsorber 15. The second nipple of the adsorber is connected by a hose to the valve 5 for purging the adsorber, and the third one is connected to the atmosphere. When the engine is off, the third nipple is blocked by a built-in check valve, in which case the adsorber does not communicate with the atmosphere. When the engine starts, the ECU begins to send control pulses to the electromagnetic valve. The electromagnetic valve opens, and under the influence of the vacuum, the check valve in the adsorber also opens, due to which air from the atmosphere and fuel vapor from the separator enter the adsorber. At this time, the sorbent is purged: gasoline vapors are removed through hoses 4 and throttle assembly 4 (see figure 5.21) into the intake manifold 5.
Malfunctions of the fuel vapor recovery system lead to unstable idle speed, engine stalling, increased toxicity of exhaust gases and deterioration of the vehicle's driving performance.