6.2. Power supply system of petrol engines
Principles of functioning of a control system of the petrol engine
Since the power supply system is a part of the control system uniting also systems of ignition and decrease in toxicity of the fulfilled gases (FG) it is not possible to consider them separately. The description of a control system of the engine is given below.
Components of electronic control by the engine in the ME-Motronic system
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 at the level of 3.5 atm.
Through the electrooperated injectors fuel pulsewise is injected into the inlet ports located just before inlet valves of the engine. The control unit of the engine (ECM) defines the optimum moments of ignition and injection, and also amount of injectable fuel in coordination with other systems of the car. High voltage for sparking on a signal of ECM is generated by the ignition coils installed over spark plugs.
The sensor of provision of a bent shaft (CKP) gives the control unit information on the speed of a bent shaft and its exact situation. This information is used for definition of the moments of injection and ignition. The CKP sensor is located on the back party of the engine and works at a basis of effect of Hall, scanning teeth of the rotor established on cranked to a shaft.
The sensor of position of the camshaft (CMP) is located at an end face of a head of cylinders and works similar to the CKP sensor, scanning a gear rotor on the end of the inlet camshaft. The CMP sensor together with the CKP sensor is used for definition of VMT of the piston of the first cylinder, dynamic adjustment of phases GRM (by means of Ý/m the valve and the regulator of phases of inlet valves), selective regulation of a detonation in cylinders and for definition of the sequence of injection.
The air necessary for formation of working mix is sucked in by the engine via the air filter and arrives through a butterfly valve and the inlet pipeline to inlet valves. The amount of the soaked-up air is regulated by a butterfly valve with э / the drive operated on signals from the sensor of position of the accelerator pedal. Thanks to electronic control the mass consumption of air in the inlet pipeline can be established irrespective of position of the accelerator pedal, and on single turns the butterfly valve opens on the corner necessary for installation of the required frequency of rotation of a bent shaft. The mass of the soaked-up air decides by the MAF sensor on the built-in sensor of temperature of the soaked-up air (IAT).
The sensor of a detonation (KS) is screwed sideways in the block of cylinders and interferes with emergence of shock combustion of fuel. Thanks to it the moment of ignition keeps on detonation border that provides the best use of energy of fuel and, thereby, decrease in its expense.
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. In emergency operation injectors work at the same time, 2 times for a running cycle.
The system of ventilation of the fuel tank consists of an absorber of vapors of gasoline and Ý/m the valve. In an absorber the fuel vapors which are formed in a tank as a result of fuel heating concentrate. In operating time of the engine fuel vapors are pumped over from an absorber and participate in formation of working mix.
Decrease in toxicity of OG is carried out by means of the 3-functional catalytic converter and a lambda probes (before and after the catalytic converter).
Also the system of ventilation of crankcase gases (PCV) is applied to elimination of leak of not burned down hydrocarbons in the atmosphere. The gases and vapors of oil which are formed in a case get to the inlet pipeline (at the expense of pressure difference – in a case it higher) and burn down in cylinders together with fuel.
In order that numerous electronic control units could exchange with each other data, these blocks are united by the high-speed tire of data transmission of CAN. Sheena CAN consists of two lines that allows to reduce quantity of an electrical wiring. Each control unit can transfer and accept at the same time data, however each concrete block reads out from CAN tire only data necessary for it.