6.1.3. Principle of functioning of a control system of fuel injection
Fuel is sucked in from the fuel tank by the electric fuel pump and moves via the fuel filter to the fuel distributive highway. The regulator of pressure provides maintenance of pressure in fuel system in the range of 3.0 ÷ of 3.4 atm.
Through the electrooperated injectors fuel pulsewise is injected into the inlet pipeline located just before inlet valves of the engine. The control unit of the engine makes consecutive management of injectors according to an ignition order, regulates injection time and by that amount of injectable fuel.
The air necessary for formation of fuel mix is sucked in by the engine via the air filter and arrives through a butterfly valve, the air distributor and the inlet pipeline to inlet valves. The amount of the soaked-up air is regulated by a butterfly valve. The volume of the soaked-up air is defined by the measuring instrument of amount of air (MAF) located on an air cleaner cover.
The control unit of the engine is in the lower right part of the dashboard. The control unit defines optimum time of ignition, the moment of injection and amount of injectable fuel. At the same time there is a coordination of operation of the control unit with other systems of the car.
Information from other sensors and the operating tension arriving to executive bodies ensures optimum functioning of the engine in any situation. If some sensors fail, the control unit switches in the mode of the emergency program to exclude possible damage of the engine and to provide the further movement of the car.
Short description of the principles of functioning of some of sensors and actuation mechanisms of a control system of the engine
The sensor of provision of a butterfly valve (TPS) is built in in the executive mechanism of a butterfly valve and issues information on the current coal of provision of a butterfly valve on the module of management (ECM). The second potentiometer reports to ECM data on basic value and forms the duplicating signal at failure of a potentiometer of a butterfly valve.
The sensor of provision of a bent shaft (CKP) is installed on the block of cylinders at a flywheel. It transfers to the control unit information on the speed of a bent shaft and finding of the piston of the first cylinder to VMT.
The sensor of position of the camshaft (CMP) is located in an end face of a cover of a head of cylinders. He together with the sensor of provision of a bent shaft transfers to the control unit information on VMT of the piston of the first cylinder. It serves for synchronization of the moment of ignition and the sequence of ignition.
The sensor of temperature of cooling liquid (ECT) is located in a reception branch pipe of the cooling system (see illustrations Components of installation of the thermostat and Location of D/V No. 1 and No. 2 ECT). It represents the resistor with negative temperature coefficient which resistance decreases with growth of temperature.
The sensor of measurement of mass of air (MAF) represents the termoanemometrichesky measuring instrument which is built in to the inlet air highway of the engine. In the case of the measuring instrument the thin, electrically warmed touch film cooled by the passing stream of the soaked-up air is located. The electric current heating a film is regulated by a control system so that to maintain temperature a constant film. If, for example, the amount of the soaked-up air increases, temperature of the heated film begins to decrease. At the same time the size of electric current at once increases to keep temperature of a plate invariable. Fluctuations of electric current indicate to the control unit of the engine its loading that allows to define amount of injectable fuel correctly. Information issued by the sensor is used by ECM when determining parameters of a dosage of air-fuel mix.
The sensor of a detonation (KS) is rolled directly in the block of cylinders and serves for prevention of emergence of dangerous shock combustion of fuel mix, allowing to hold installation of the moment of ignition on detonation border when efficiency of return of the engine is maintained at the maximum level at the minimum fuel consumption.
The system of ventilation of a fuel tank / catching of fuel evaporations (EVAP) consists of a coal adsorber and the electromagnetic valve of management of a purge of the last. In an adsorber the fuel vapors which are formed as a result of its heating accumulate. During the operation of the engine the fuel evaporations which accumulated in an adsorber are extended to the inlet highway and go to combustion chambers.
Lambda probes measure the content of oxygen in the fulfilled gases (FG) before and after catalytic converters and transmit the corresponding signals to the control unit of the engine.