10.7.1. Features of a design
The engine established on cars Chevrolet Lanos, is equipped by an electronic control system of the engine with the distributed injection of fuel. This system provides performance of modern norms on toxicity of emissions and evaporations at preservation of high road performance and the low expense of fuel.
The actuation device in system is the electronic block of management (ECU). On the basis of the information received from gauges, ECU counts parametres of regulation of injection of fuel and management of a corner of an advancing of ignition. Besides, according to put algorithm ECU operates work of the electric motor of the fan of system of cooling of the engine and electromagnetic муфты inclusions of the compressor of the conditioner, carries out function of self-diagnostics of elements of system and notifies the driver on the arisen malfunctions.
At failure of separate gauges and executive mechanisms EBU includes the emergency operation providing working capacity of the engine.
The quantity of the fuel submitted atomizers, is defined by duration of an electric signal from ECU. The electronic block traces the data about an engine condition, counts requirement for fuel and defines necessary duration of giving of fuel atomizers (duration of a signal). For increase in quantity of submitted fuel duration of a signal increases, and for reduction of giving of fuel — decreases.
The control system of the engine along with the electronic block of management includes gauges, actuation mechanisms, sockets and safety locks.
The electronic block of management (ECU) is connected by electric wires with all gauges of system. Receiving from them the information, the block carries out calculations according to parametres and algorithm of the management, stored in memory of a programmed constant memory (ППЗУ), and operates system actuation mechanisms. The variant of the program which have been written down in memory ППЗУ, is designated by number appropriated given updating ECU.
The management block finds out malfunction, identifies and remembers its code even if refusal is unstable and disappears (for example, because of bad contact). The alarm lamp of malfunction of a control system of the engine in a combination of devices dies away through 10 with the ambassador of restoration of working capacity of the refused knot.
After repair stored in memory of the block of management the malfunction code is necessary for erasing. For this purpose disconnect a block food on 10 with (take out a safety lock of a feed circuit of the electronic block of management or disconnect a wire from the plug "minus" of the storage battery).
The block feeds with a direct current pressure 5 and 12 In various gauges and control system switches. As electric resistance of feed circuits high, the control lamp connected to conclusions of system, does not light up. On conclusions ECU it is necessary to apply the voltmeter to definition of pressure of a food with internal resistance not less than 10 МОм.
ECU it is not suitable for repair, in default it is necessary to replace it.
The diagnostic socket serves for a conclusion from memory ECU of codes of the malfunctions revealed at work of a control system by the engine. The designation and an arrangement of conclusions in a diagnostic socket is shown on fig. 10.6.
Appointment of conclusions:
And – "weight";
B — a diagnostic conclusion;
Е — a conclusion "plus".
Fig. 10.6. A diagnostic socket
The diagnostic socket is located in car salon in a niche for feet of the driver on the right side under the panel of devices. The self-diagnostics mode joins at conclusion connection "In" (a diagnostic conclusion) with a conclusion "And", connected to "weight", and ignition inclusion (the engine should not work). It is possible to connect the scanner which reads out the information from a consecutive line of the data To a diagnostic socket.
The gauge of temperature of a cooling liquid is established in system of cooling of the engine. A sensitive element of the gauge is термистор which electric resistance changes in inverse proportion to temperature. At low temperature of a cooling liquid (–40 °С) resistance термистора makes nearby 100 clod, at rise in temperature to +130 °С — decreases to 70 Ohm.
The electronic block feeds a chain of the gauge of temperature with constant basic pressure. Pressure of a signal of the gauge as much as possible on the cold engine also decreases in process of its warming up. On value of pressure the electronic block defines temperature of the engine and considers it at calculation of adjusting parametres of injection and ignition. At refusal of the gauge or infringements in a chain of its connection ECU establishes a code of malfunction and remembers it. For malfunction elimination check up reliability of contact connections in conducting to the gauge or replace the gauge.
The gauge of temperature of air on an admission (it is pasted in воздухоподводящий a sleeve) is similar on a design to the gauge of temperature of a cooling liquid, in it also is used термистор, changing the resistance depending on temperature.
Resistance термистора makes 100 clod at temperature–40 °С, and at rise in temperature to +130 °С decreases to 70 Ohm.
ECU feeds a gauge chain with constant basic pressure. Pressure of a signal of the gauge as much as possible when air in an inlet pipe cold, also decreases in process of increase of its temperature. On value of pressure ECU defines air temperature on an admission and introduces corrective amendments at calculation of a corner of an advancing of ignition. At refusal of the gauge or infringements in a chain of its connection ECU establishes a code of malfunction and remembers it. If ECU continues to give out a malfunction code at serviceable contact connections in conducting, replace the gauge of temperature of air.
The gauge of position of a cranked shaft of inductive type is intended for synchronisation of work of the electronic block of management with ВМТ pistons of 1st both 4th cylinders and angular position of a cranked shaft.
The gauge is established in a forward part of the engine opposite to a setting disk on a pulley of a cranked shaft. The setting disk represents a cogwheel with равноудаленными hollows. Two teeth is cut off for creation of an impulse of synchronisation ("a basic" impulse) which is necessary for the coordination of work of the block of management with ВМТ pistons in 1st and 4th cylinders.
At rotation of a cranked shaft teeths change a gauge magnetic field, directing impulses of pressure of an alternating current. The management block on gauge signals defines frequency of rotation of a cranked shaft and gives out impulses on atomizers.
At refusal of the gauge engine start-up is impossible.
The gauge of position throttle заслонки is established sideways on throttle knot and connected with an axis throttle заслонки.
The gauge represents a potentiometer on which one end "plus" of pressure of a food (5) moves, and other end is connected to "weight".
From the third conclusion of a potentiometer (from a toddler) there is a target signal to the electronic block of management.
When throttle заслонка turns (from influence on a management pedal), pressure on a gauge exit changes. At closed throttle заслонке it below 0,5 V.Kogda заслонка opens, pressure on a gauge exit grows, at completely opened заслонке it should be more than 4 Century
Tracing target pressure of the gauge, the controller corrects giving of fuel depending on a corner of opening throttle заслонки (i.e. at will of the driver).
The gauge of position throttle заслонки does not demand adjustment as the management block perceives idling (i.e. full closing throttle заслонки) as a zero mark.
The gauge of absolute pressure in an inlet pipe will transform depression in this pipe to electric pressure on which value the electronic block of management defines engine loading. The gauge is established in a motor compartment, fixed on a board partition передка and connected to an inlet pipe a rubber tube. Target pressure of the gauge changes according to pressure in an inlet pipe — from 4,9 In (at completely opened заслонке) to 0,3 In (at closed заслонке). At the idle engine the management block on pressure of the gauge defines atmospheric pressure and adapts parametres of regulation of injection for concrete height above sea level. The values of atmospheric pressure stored in memory, periodically are updated at uniform movement of the car and during full opening throttle заслонки.
The gauge of speed of the car is established on a transmission. The principle of action of the gauge is based on effect of the Hall. The gauge gives out on the electronic block of management rectangular impulses of pressure with the frequency proportional to speed of rotation of driving wheels.
The gauge of concentration of oxygen (ljambda-probe) will screw in a carving aperture of a final collector. In a metal flask of the gauge the galvanic cell washed by a stream of fulfilled gases is located. Depending on the oxygen maintenance in the fulfilled gases as a result of combustion топливовоздушной mixes pressure of a signal of the gauge changes.
The information from the gauge arrives in the block of management in the form of signals low (from 0,1) and high (to 0,9) level. At a signal of low level the management block receives the information on the high maintenance of oxygen and, hence, about mix pauperisation. The signal of high level testifies to the low maintenance of oxygen in the fulfilled gases and, hence, about mix reenrichment.
Constantly tracing pressure of a signal of the gauge, the management block corrects quantity of fuel injected by atomizers. At low level of a signal of the gauge (poor топливовоздушная a mix) the quantity of submitted fuel increases, at high level of a signal (a rich mix) – decreases.
1. Before to remove any knots of a control system of fuel injection, disconnect a wire from the plug "minus" of the storage battery.
2. Do not start up the engine if tips of wires on the storage battery are badly tightened.
3. Never disconnect the storage battery from an onboard network of the car at the working engine.
4. At gymnastics of the storage battery disconnect it from an onboard network of the car.
5. Do not subject ECU to temperature above 65 wasps in working order and above 80 wasps in non-working (for example, in сушильной to the chamber). It is necessary to remove ECU from the car if this temperature is exceeded.
6. Do not disconnect from ECU and do not attach to it a wire at the included ignition.
7. Before carrying out of electrowelding works on the car disconnect wires from the storage battery and колодки a plait of wires from ECU.
8. All measurements of pressure carry out the digital voltmeter with internal resistance not less than 10 МОм.
9. The electronic knots applied in system of injection of fuel, are calculated on very small pressure, can be therefore easily damaged the electrostatic category. Not to admit damage ECU, do not touch with hands its conclusions.
10. For diagnostics of a control system by the engine in all cases the special scanner is required, therefore at occurrence of malfunctions of system address on specialised service.