- fuel supply system, including the fuel tank, fuel module, fuel filter and fuel pressure regulator (are part of the fuel module), fuel lines and fuel rail with injectors;
- air supply consisting of an air filter, air supply hose and throttle assembly;
- fuel vapor recovery system, which includes an adsorber, an adsorber purge valve and connecting pipes.
Note: The fuel vapor recovery system is described in a separate subsection (see Fuel vapor recovery system), since it serves only to meet environmental requirements for reducing toxicity.
Functional purpose fuel supply systems – ensuring 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 fuel injection into the intake pipe, and the required amount of air at each moment of engine operation is supplied by the throttle unit. This control method makes it possible to ensure the optimal composition of the combustible mixture at each specific moment of engine operation, which allows obtaining maximum power with the lowest possible fuel consumption and low toxicity of exhaust gases. The fuel injection system and the ignition system are controlled by an electronic engine control unit, which continuously monitors the engine load, vehicle speed, engine thermal state, and optimization of the combustion process in the engine cylinders using appropriate sensors.
The peculiarity of the injection system of the Opel Astra J is the synchronicity of the injectors' operation in accordance with the valve timing (the engine control unit receives information from the phase sensors). The control unit switches on the injectors sequentially, and not in pairs, as in asynchronous injection systems. Each injector is switched on after 720° of crankshaft rotation. However, in starting modes and dynamic engine operation modes, an asynchronous fuel supply method is used without synchronization with crankshaft rotation.
The main sensor for ensuring an optimal combustion process is oxygen concentration control sensor in exhaust gases (lambda probe). It is installed in the exhaust manifold of the exhaust system, combined with the exhaust gas neutralizer (catcollector), 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 optimality of the composition of the fuel-air mixture supplied to the engine cylinders at each moment in time. Having recorded a deviation of the composition from the optimal 1:14 (fuel/air), which ensures 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 circuit for the composition of the fuel-air mixture is closed.
The peculiarity of the engine management system of the Opel Astra J is that in addition to the control sensor, there is a second one, diagnostic oxygen concentration sensor, installed in the exhaust system's inlet pipe. Based on the composition of the gases that have passed through the neutralizer, it determines the efficiency of the engine management system. If the engine control unit, based on the information received from the diagnostic oxygen concentration sensor, detects that the exhaust gas toxicity standard has been exceeded, which cannot be eliminated by calibrating the control system, it turns on the exhaust toxicity indicator lamp in the instrument cluster and stores the error code in the memory for subsequent diagnostics.
Fuel tank, molded from special impact-resistant plastic, is installed under the body floor in its rear part and secured with clamps. To prevent fuel vapors from entering the atmosphere, the tank is connected by a pipeline to the adsorber of the fuel vapor recovery system. An electric fuel pump is installed in the flange opening in the upper part of the tank, and in the rear part there are branches for connecting the filler pipe and ventilation hose. From the pump, which includes a fuel filter, fuel is fed to the fuel rail, fixed to the engine intake pipe. From the fuel rail, it is injected by nozzles into the intake pipe.
Fuel lines combined power supply systems in the form of interconnected steel pipelines and plastic hoses.
Fuel module includes an electric pump, fuel pressure regulator, fuel filter and fuel level indicator sensor.
The fuel module supplies fuel and is installed in the fuel tank, which reduces the likelihood of vapor locks, since the fuel is supplied under pressure, not under vacuum. Lubrication and cooling of the fuel pump parts are also improved.
Submersible fuel pump, rotary type, with electric drive.
Fuel pressure regulator is installed in the fuel 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 relief valve with a spring, the force of which is strictly calibrated.
Fuel rail 2 (Fig. 1) is a hollow part with holes for injectors 3, with a nipple for connecting the high-pressure fuel line, a diagnostic nipple 5 for checking the fuel pressure and brackets for fastening to the inlet pipe. The injectors are sealed in the ramp holes and in the inlet pipe sockets with rubber rings 4 and secured with spring clamps 1. The ramp assembly with injectors is inserted with the injector tails into the inlet pipe holes and secured with two bolts.
Fig. 1. Fuel rail: 1 – nozzle retainer; 2 – ramp; 3 – nozzle; 4 – injector sealing ring; 5 – diagnostic connector
The injectors (Fig. 2) are attached to the ramp from which fuel is supplied to them, and their sprayers enter the openings of the intake pipe.
Fig. 2. Fuel injection system injector: 1 - Upper sealing ring; 2 - plug-in terminals of the electromagnet winding; 3 - lower sealing ring
The injectors are sealed with rings in the ramp and intake pipe openings 1 and 3. The injector is designed for metered injection of fuel into the engine cylinder and is a high-precision electromechanical valve. Fuel under pressure comes from the ramp through the channels inside the injector body to the shut-off valve. The spring presses the needle of the shut-off valve to the hole of the spray plate, holding the valve in the closed position. Voltage supplied from the engine control unit through the plug terminals 2 on the injector electromagnet winding, creating a magnetic field in it, drawing the core together with the shut-off valve needle into the electromagnet. The annular hole in the spray plate opens, and fuel is injected through the holes in the spray body into the intake channel of the cylinder head and then into the engine cylinder. After the electrical impulse ceases, the spring returns the core and the shut-off valve needle to their original state - the valve is closed. The amount of fuel injected by the injector depends on the duration of the electrical impulse.
Air filter is mounted in the right front part of the engine compartment on the engine mudguard. The filter inlet pipe is connected to the intake noise resonator mounted under the right front fender, which in turn is connected to the air duct mounted under the upper cross member of the radiator frame.
Rubber corrugated air supply hose connects the filter to the throttle assembly.
Air filter element paper, flat, with a large filtering surface area.
Throttle assembly, which is the simplest control device, is designed to change the amount of main air supplied to the engine intake system, is installed on the inlet flange of the intake pipe and secured with bolts. A molded rubber air supply sleeve is put on the inlet pipe of the throttle assembly, secured with a clamp and connecting the throttle assembly with the air filter.
The throttle assembly includes a throttle position sensor and a stepper motor for controlling the throttle valve. There is no mechanical connection between the throttle assembly and the throttle valve control pedal. The so-called "electronic" throttle valve control pedal transmits information about the degree of pressure on the pedal to the electronic engine control unit, which, in turn, taking into account the vehicle speed, the gear engaged, the engine load and the rotation frequency of its crankshaft, opens the throttle valve to the required angle.
Intake pipe equipped with a variable intake tract length system, which allows for increased power to be developed at high engine crankshaft speeds (minimum intake tract length) and maximum torque in the low and mid-range speed range (increased length of the intake tract). The length is changed by the signal from the engine control unit by turning the valve inside the intake pipe using a pneumatic chamber (shown in the photo by an arrow), which is connected to the engine vacuum system via a solenoid valve.
Text copied from a web portal: Opelbook.ru
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