6.2.3. Principle of functioning of a control system and injection of the petrol engine
Fuel is sucked in from a fuel tank by the electric fuel pump and moves via the fuel filter to the fuel distributive highway. The regulator of pressure provides pressure maintenance in fuel system in a range of 3.2 ÷ 3.6 atm.
Through electrooperated injectors fuel impulsno is injected into the inlet pipeline located directly ahead of inlet valves of the engine. The control unit the engine makes consecutive management of injectors according to ignition order, regulates injection time and by that amount of injected fuel.
The air necessary for formation of a fuel 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 soaked-up air is regulated by a butterfly valve which moves the step-by-step electric motor operated by the control unit of the engine. At compressor engines soaked-up air is compressed by the compressor actuated from klinoremenny transfer. Then the compressed air is cooled in a cooler of forced air and arrives in the engine for formation of a fuel mix.
The volume of soaked-up air is defined by a measuring instrument of amount of air. The measuring instrument is located in the channel of soaked-up air. In the case of a measuring instrument the warmed touch plate cooled by a passable stream of soaked-up air is located thin, electricly. The electric current which is heating up a plate, is regulated by a control system so that to maintain temperature of a constant plate. If, for example, the amount of soaked-up air increases, the temperature of a heated-up plate starts to decrease. Thus the size of an electric current increases at once to keep temperature of a plate invariable. Fluctuations of an electric current of a plate indicate to the control unit by the engine its condition of loading that allows to define amount of injected fuel correctly.
The control unit the engine is in electronics box, at the left, about the tank of brake liquid or is direct on the engine. The control unit defines optimum time of ignition, the moment of injection and amount of injected fuel. Thus there is a coordination of operation of the control unit with other systems of the car, for example, to management of a transmission or anticreeping system.
Information from other sensors and the operating tension arriving to executive bodies, provides optimum operation of the engine in any situation. If some sensors fail, the control unit is switched in a mode of the emergency program to exclude possible damage of the engine and to provide further movement of the car. In this case the engine works non-uniformly and at increase in gas has tendency to a stop.
Structure and functioning principle
Location of separate elements of a control system on an example of separate models is shown by the engine on an illustration of the Detail of installation of the module of management of a forward door.
On considered models of a standard complete set of release on 12.2000 6-contact (A-F) the electronic module of management (ECM) of ME 2.0 is used. On models of a complete set of AMG, and also on standard models of release with 12.2000 the 5-contact (1-5) ME 2.8 module placed in an aluminum protective casing of tight execution is established.
Entrance signals of ECM
As entrance data of ECM uses signals from the following information sensors / actuation mechanisms:
- The sensor of temperature of cooling liquid (ECT);
- The Termoanemometrichesky sensor of weight of soaked-up air (MAF);
- The sensor of temperature of the soaked-up air (IAT), MAF built in assembly;
- Sensor of provision of a butterfly valve (TPS);
- Sensor of level/temperature/quality of impellent oil;
- The operating switch tempostata/Speedtronic 1);
- The pressure sensor in a fuel tank 1);
- The pressure sensor in the inlet pipeline 1) 2);
- The sensor of provision AT (PNP), - from the module of management of transmissions (ETC);
- Differential sensor of provision of a cranked shaft (CKP);
- The sensor of provision of a camshaft (CMP) on effect of the Hall;
- Oxygen sensors (lambda probes);
- Sensors of a detonation (KS);
- Sensor (potentiometer) of provision of a pedal of gas.
1) Models for the American market
2) Models of a complete set of AMG (ME 2.8 from 6.00)
Target signals of ECM
The target ECM teams treat:
- Signals of activation of coils of ignition (on one dual coil on each cylinder);
- Signals of activation of fuel injectors;
- Signals of activation of a drive of a butterfly valve;
- Signals of activation of the relay of the fuel pump;
- Target component of a signal of pulse-width modulation (ShIM) of a transdyuser of system of a retsirkulyatsiya of the fulfilled gases (EGR);
- Signals of activation of system of a podmeshivaniye of air;
- Signals of activation of a drive of switching of the inlet pipeline;
- Signals of activation of the relay of a starter;
- Signals of activation of a purge of a coal adsorber of system of catching of fuel evaporations (EVAP);
- Signals of activation of the valve of an otsechka of a coal adsorber 1);
- Signals of the line of the malfunctions given to memory.
1) Models for the American market
Information transferred on the tire of data exchange of CAN
- Working condition of a control system of transmission (ETC);
- Working condition of systems of dynamic stabilization of movement (BAS/ASR/ESP/ETC), - the management module;
- Working condition of an electronic pedal of gas
- Information on the AT current situation;
- Information on protection of transmission from overloads;
- Frequency of rotation of wheels (speed of movement and acceleration);
- Condition of the sensor switch of stoplights;
- Condition of measuring instruments/indicators of a combination of devices;
- To/in system condition (in working pressure in a refrigerator path);
- Switching signals tempostata/Speedtronic.
Short description of principles of functioning of some of sensors / actuation mechanisms of a control system
The sensor of provision of a butterfly valve (TPS) is built in in the executive mechanism of a butterfly valve and issues on the module of management (ECM) information on the current coal of provision of a butterfly valve. The second potentiometer reports ECM data on base value and forms a spare signal at failure of a potentiometer of a butterfly valve.
The sensor of level/temperature/quality of impellent oil is established in the pallet of a case of the engine and develops three information signals of the pulse-width modulation (ShIM), transferred to ECM and (on the tire CAN) on a combination of devices of the car.
Quality of oil is defined on the basis of data on term of performance of its last replacement.
The sensor of provision of a cranked shaft (CKP) will screw in the block of cylinders at a flywheel. It hands over to the control unit information on number of turns of the engine and position VMT of the piston of the first cylinder.
The sensor of provision of a camshaft (CMP) is located in an end face of a cover of a head of cylinders. It together with the sensor of provision of a cranked shaft hands over to the control unit information on VMT of the piston of the first cylinder. It serves for synchronization of the moment of ignition and sequence of ignition.
The executive mechanism of a butterfly valve consists of the electric motor and two potentiometers. The mechanism regulates the provision of a butterfly valve, providing stability of turns of idling, is not dependent on connection of additional consumers of energy, such as the steering amplifier or the К/В compressor.
The sensor of provision of a pedal of gas is located the region of an arrangement of feet of the driver directly on an axis of a pedal of gas. It gives the control unit information on the provision of a pedal. For safety reasons from the sensor of a pedal the additional signal, just as from a butterfly valve potentiometer undertakes.
The sensor of temperature of cooling liquid (ECT) is located in the thermostat case. It represents the resistor with the negative temperature factor (NTC) which resistance decreases with temperature growth.
The sensor of measurement of weight of air (MAF) represents the termoanemometrichesky measuring instrument which has been built in in an inlet air path of the engine. Information issued by the sensor is used by ECM at determination of parameters of a dosage of an air and fuel mix.
The sensor of temperature of soaked-up air (IAT), - the NTC resistor which has been built in assembly of the MAF sensor.
The system of ventilation of 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 pairs of fuel which are forming as a result of its heating accumulate. At operation of the engine the fuel evaporations which have accumulated in an adsorber are extended to the inlet highway and go to combustion chambers.
Lambda probes (oxygen sensors) measure the content of oxygen in the fulfilled gases before and after the catalytic converter and transmit the corresponding signals in the control unit the engine. One lambda probe another is located before, and after the catalytic converter.
The sensor (and) detonations (KS) is rolled directly in a body of the block of cylinders and serves for prevention of emergence of dangerous shock combustion of a fuel mix, allowing to hold installation of the moment of ignition on detonation border when efficiency of return of the engine is supported at a maximum level at the minimum fuel consumption.
The system of a podmeshivaniye of air consists of the power unit of the air pump established in a forward part and synchronously with it the functioning combined valves switches, pribolchenny in front to each of heads of cylinders.
System of a retsirkulyatsiya of the fulfilled gases. The combined EGR valve with an electronic vacuum transdyuser is established under the right number of cylinders. Transdyuser copes ShIM signal, ECM are developed. Podmeshivaniye to the inlet highway of the engine of a certain amount of the fulfilled gases promotes decrease in issue in the atmosphere of oxides of nitrogen (NOH). Opening of the valve is made at depth of depression of 80 ÷ 220 Mbar.