- fuel supply, including a fuel tank, an electric fuel pump with a filter, a fuel pressure regulator, pipelines and a fuel rail with injectors;
- air supply, consisting of an air supply hose, air filter, throttle assembly, idle speed regulator;
- fuel vapor recovery system, which includes an adsorber, a control valve and connecting pipes.
The functional purpose of the supply subsystem is to ensure the supply of the required amount of fuel to the engine in all operating modes. The engines are equipped with an electronic engine control system with distributed fuel injection. In the distributed injection system, the functions of mixture formation and metering of the fuel-air mixture supply to the engine cylinders are separated: air is supplied by the air supply subsystem, consisting of a throttle assembly and an idle speed regulator, and the required amount of fuel at each moment of engine operation is injected by injectors into the intake pipe. 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. Controls the fuel injection system (as well as the ignition system) electronic unit (controller), continuously monitoring the engine load, vehicle speed, engine thermal state, and the optimal combustion process in the engine cylinders using appropriate sensors.
The 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 a method of vapor absorption by a carbon adsorber. It is installed in the niche of the right front wing and is connected by pipelines to the fuel tank and the inlet pipe. On the adsorber cover there is an electromagnetic valve for purging the adsorber, which switches the operating modes of the system according to signals from the engine control unit.
Fuel vapors from the fuel tank are constantly removed through a pipeline and accumulate in an adsorber filled with activated carbon (adsorbent). Regeneration occurs when the engine is running (recovery) adsorbent by purging the adsorber with fresh air entering the system under the action of the vacuum transmitted through the pipeline from the inlet pipe to the cavity of the adsorber when the valve opens. The magnitude of the valve opening, and therefore the intensity of the adsorber purging, depend on the opening angle of the throttle valve and are determined by the vacuum that occurs in the cavity of the inlet pipe of the running engine.
Fuel vapors from the adsorber enter the engine intake pipe through a pipeline and burn in the cylinders.
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.
Fig. 5.15. Scheme of the control circuit for the composition of the fuel-air environment: 1 - nozzle; 2 - exhaust manifold; 3 - control sensor of oxygen concentration in exhaust gases (lambda probe); 4 - engine; 5 - electronic engine control unit; 6 - catalytic converter of exhaust gases; 7 - diagnostic oxygen concentration sensor
Exhaust Gas Oxygen Sensor (lambda probe)is the main sensor for ensuring the optimal combustion process. It is installed in the exhaust manifold of the engine and, together with the electronic unit and injectors, forms a circuit for adjusting the composition of the fuel-air mixture supplied to the engine (Fig. 5.15). 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 the deviation of the composition from the optimal G. 14 (fuel and air respectively), ensuring the most efficient operation of the catalytic converter of exhaust gases, the control unit changes the composition of the mixture using injectors. As a result, the control circuit of the fuel-air mixture composition is closed.
The car has two oxygen concentration sensors: the first one is in the exhaust manifold, the second one is after the catalytic converter. The first sensor is the control one (based on its signal, the ECU adjusts the fuel supply), and the second is diagnostic (based on its signal, the ECU evaluates the efficiency of the catalytic converter).
Fuel tank, molded from gasoline-resistant plastic, is installed under the body floor in its rear part and is secured with two bolts and two nuts. In order to prevent fuel vapors from entering the atmosphere, the tank is connected by a pipeline to the adsorber. An electric fuel pump is installed in the flange opening in the upper part of the tank. From the pump, fuel is supplied through the pressure regulator to the fuel filter installed in the fuel module, and from there it enters the engine fuel rail, secured to the intake pipe. From the fuel rail, fuel is injected by injectors into the intake pipe.
Fuel lines of the fuel system are tubes that connect various elements of the system.
Warnings:
- It is prohibited to replace steel pipelines with hoses, copper or aluminum tubes, since only steel pipelines meet the conditions of operation under high pressure and vibration.
- Fuel system hoses are made using a special technology from oil- and petrol-resistant materials. Using hoses that differ in design from those recommended may result in fuel system failure and, in some cases, fire.
- Round sealing rings are used in pipeline connections with power supply system elements. The use of seals of other designs is prohibited.
Fuel pump module includes an electric pump...
...fuel pressure regulator...
...fine fuel filter...
...and the fuel level indicator sensor.
The fuel pump module delivers fuel and is located in the fuel tank, reducing the possibility of vapor lock as the fuel is delivered under pressure rather than vacuum.
[Text provided by an online resource: RenaultBook]
Fuel pump of submersible type, with electric drive, rotary type. The pump of non-separable design is not subject to repair, in case of failure it must be replaced.
Fig. 5.16. Injector ramp: 1 - nozzle retainer; 2 - ramp; 3 - nozzle; 4 - injector sealing ring; 5 - nipple for connecting the high-pressure fuel line
Ramp2 (Fig. 5.16) of the injectors is a cast hollow part with holes for installing the injectors 3 and with a supply nipple 5 for connecting the high-pressure fuel line. The injectors are sealed in their sockets with rubber rings 4 and secured with spring clamps 1. The ramp with the injectors in assembly is inserted with the tails of the injectors into the holes of the inlet pipe and secured with two bolts.
Nozzlesare attached to the ramp from which fuel is supplied to them, and their sprayers enter the holes of the inlet pipe. In the holes of the ramp and the inlet pipe, the injectors are sealed with rubber sealing rings A and B. 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 channels inside the injector body to the shut-off valve. The spring presses the needle of the shut-off valve to the conical hole of the sprayer plate, holding the valve in the closed position. The voltage supplied from the engine control unit through plug terminals B to the winding of the injector electromagnet creates a magnetic field in it, drawing the core together with the needle of the shut-off valve into the electromagnet. The conical annular hole in the sprayer plate opens, and fuel is injected through the diffuser of the sprayer body into the intake channel of the cylinder head and then into the engine cylinder. After the electrical impulse ceases to flow, the spring returns the core and the needle of the shut-off valve to their original state - the valve is closed. The amount of fuel injected by the injector depends on the duration of the electrical impulse.
Fuel pressure regulator, structurally combined with the fuel module storage glass, maintains constant fuel pressure in the engine fuel system in all engine operating modes. The supply of the electric fuel pump is greater than necessary to ensure the system's operability. Therefore, when the engine is running, part of the fuel is constantly drained into the fuel tank due to the pressure regulator.
Air filter k7J and K7M engines are installed in the center of the engine compartment.
Note.
- On cars with a K4M engine, the air filter is located near the throttle assembly.
Air filter element k7J and K7M engines paper, round, with a large filtering surface area.
Note.
- This is what the filter element of the K4M engine looks like.
Fig. 5.17. Throttle assembly: 1 - idle speed controller; 2 - throttle actuator lever; 3 - throttle valve; 4 - throttle position sensor; 5 - throttle body
Throttle assembly is the simplest control device and serves to change the amount of main air supplied to the engine intake system. It is installed on the inlet flange of the intake pipe. An air filter is put on the inlet pipe of the throttle assembly, the connections of the throttle assembly with the intake pipe and air filter are sealed with rubber gaskets.
The throttle body has a hole for supplying additional air to the idle speed regulator.
In the housing 5 (Fig. 5.17) a flap 3 is installed, rotating on an axis. At one end of the axis a sensor 4 of the throttle position of the engine management system is installed, at the other - a lever 2, to which an intermediate rod of the throttle drive is connected. On the housing 5 an idle speed regulator 1 is fixed, dosing the air flow with the throttle valve closed.
During operation, the throttle assembly does not require maintenance or adjustment; just monitor the condition of the rubber seals to avoid air leakage.
Idle speed control valve maintains a set engine idle speed with the throttle valve fully closed during starting, warming up and when changing the load when auxiliary equipment is turned on.
The regulator changes the amount of additional air supplied to the intake system in addition to the throttle valve, and is an electromechanical valve attached with two bolts to the flange of the throttle body. The regulator valve seat and channels made in the flange of the throttle assembly form a system for supplying additional air, bypassing the throttle valve.
Fig. 5.18. Idle speed controller: 1 - valve; 2 - regulator body; 3 - stator winding; 4 - lead screw; 5 - stator winding plug terminal; 6 - ball bearing; 7 - stator winding housing; 8 - rotor; 9 - spring
The engine control unit, having processed the signals from the sensors, determines the need to open valve 1 (Fig. 5.18) of the regulator and transmits pulses to plug terminal 5 of winding 3 of the stator of the regulator. With each control pulse, rotor 8 turns by a certain angle, moving valve 1 relative to the seat using lead screw 4. Additional air enters the intake pipe through channels in the throttle assembly. By determining the vacuum in the engine intake pipe, the control unit strives to maintain it at a given level, periodically opening and closing the idle speed regulator valve. This makes it possible to ensure the supply of a constant amount of additional air to maintain a constant idle speed. By changing the amount of 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, clogging of the air filter.
The inclusion of additional units causes an increase in engine load, accompanied by a decrease in idle speed and a change in the vacuum in the intake pipe, which is also compensated for by the control unit using the regulator.