5.4.2. Basic elements of electronic diesel system (EDS)
The control unit (fig. 4.69) is mounted on the right side of the unit. It carries out the following functions: ensuring necessary amount of fuel, maintenance of speed, management tempomaty, diagnostics, control of the admission release function and definition of extent of faulty work of system.
Fig. 4.70. Elements of electronic system upravleniya:1 – the control unit; 2 – TNVD; 3 – control lamp of an operating mode; 4 – sensor of the indication of an arrangement of a bent shaft; 5 – stoplight; 6 – the sensor of temperature of the soaked-up air; 7 – fuel supply sensor; 8 – safety relay; 9 – the valve of removal of the fulfilled gases; 10 – sensor of temperature of cooling liquid; 11 – switch of a signal of blocking and backing
Entrance signals arrive from sleduyushchikhdatchik (fig. 4.70): the index of provision of a bent shaft (at a starter), positions of a working gear wheel of a starter (in the bottom of a transmission case), the sensor of positioning and the sensor of provision of a pedal of an accelerator, the absorption pressure sensor, the sensor of temperature of the soaked-up air, the sensor of temperature of cooling liquid, the sensor of temperature of the forced fuel (in the pump), a stoplight, the sensor of operation of a signal of ABS, the sensor of a condition of work of a starter in the mode of the started engine (at automatic transmissions).
Output signals of these sensors operate: a stop, adjustment of turns, the switching of the ARF valve, positioning of the delivery valve switching by the valve in the automatic transmission, a condition of an operating mode of the diesel EDC (a lamp on the dashboard), control of the conditioner and characteristics of malfunctions at connection of the device of diagnostics.
All problems in work of system are noted by system of self-diagnostics in memory of the computer. If the malfunction proceeds long time, then control lamps on the dashboard work. The control system can correct separate "errors", but in memory of the computer it will remain. The control unit in a critical situation itself will muffle it or will establish optimum turns for continuation of the movement. If the lamp of "EDS" lights up, it is necessary to go to auto repair shop as only there make high-quality diagnostics and repairs.
All models are equipped with new systems which cope a microcomputer in interaction with the so-called CAN tire (Controller Area Network) which carries out a role of "the calculating and distributive device" and gives signals on the computer. Electronic control is a basic element in the Common Rail system which will work trouble-free at regular service.
The sensor of temperature of cooling liquid is screwed in a forward part of a head of the block of cylinders and shows temperature of cooling liquid. Resistance at +80 °C makes 300 Ohms, at +20 °C – 2,5 kOhm.
The fuel temperature sensor in model 220-D is located on TNVD and built in in section of the sensor of positioning of a dividing shaft. At the 5-cylinder diesel it is on the stop mechanism. This sensor determines fuel temperature for the subsequent calculation of its density. Also it forms a signal at failure of the sensor of temperature of cooling liquid.
Fig. 4.71. Knots of control of system of an intake of air: 1 – pressure valve case; 2 – a valve shaft with the lever; 3 – the sensor of temperature of the soaked-up air; 4 – vacuum chamber of the adjusting valve; 5 – the vacuum chamber of removal of the fulfilled gases (ARF)
The signal from the sensor of temperature of the soaked-up air (fig. 4.71) serves for calculation of mass of air at adjustment of amount of injectable fuel, smoking correction, removal of the fulfilled gases and adjustment of pressure of the forced air. Resistance at +20 °C — about 6 kOhm, at +40 °C — about 2,6 kOhm.
Measuring instrument of a mass consumption of air (CDI). Information on mass of the soaked-up air is necessary for calculation of fuel mix on injection. Irrespective of air temperature measurement is performed as follows. In system of absorption the reception element (the heated plate) which is cooled with a reception stream of air is built in. Depending on stream force it changes the temperature and resistance. Electrical quantity of change of resistance is given in the control unit.
The sensor of provision of a bent shaft serves for determination of speed and the provision of a bent shaft. It is located on the transmission case over a starter.
Four (five at 5-cylinder engines) a segment on a flywheel during the operation of the engine give alternating voltage on the sensor. The more speed — the is more tension. If the segment passes the sensor the forward edging, there is a jump of positive tension if the back edging — negative.
The sensor of provision of the leading gear wheel of a starter is installed only at 5-cylinder models and specifies speed. It is located from below transmission cases.
Sensor of supply of fuel (fig. 4.72). TNVD has no direct connection with an accelerator pedal. The sensor of supply of fuel is installed in the protective case and connected to a pedal the flexible drive. In the sensor are mounted: potentiometer of turns, contact of idling and returnable spring. On models with the automatic transmission the valve of the modulated gear shifting pressure is also installed.
Braking signal switch. When braking the control unit receives a signal, switches off темпомат and gives the command for the termination of the maximum supply of fuel. It allows to avoid car "run" even by wrong pressing an accelerator pedal. Same occurs when pressing a coupling pedal.
The switch on a coupling pedal. At 5-cylinder diesel engines when pressing a coupling pedal the control unit signals about the course of gear shifting and activization of a quencher of fluctuations.
The sensor of pressure of the soaking-up pipeline is on the left side of a motor compartment and through a hose connects to the soaking-up pipeline. Pressure on the soaking-up pipeline is necessary for the following functions: restriction of the maximum loads, removal of the fulfilled gases (ARF) and adjustment of pressure of the soaked-up air. Besides on E 290 TD it shows information for adjustment of the forced turbocompressor air.
The regulator of the forced air (290 TD) works with the help of the electric air valve. Principle of action: the magnetic valve of restriction of the forced air is operated a stream of compressed air via the valve on the compressor — when opening the valve pressure falls.
The sensor of position of the TNVD camshaft (the 4-cylinder diesel engine) reacts to the longitudinal shift of the camshaft of rather power shaft and consists of the coil with the core.
The core is screwed in the hollow camshaft. At shift of a shaft the core changes inductance of the coil. It is the important characteristic for adjustment of number of supply of fuel.
The sensor of provision of a cam washer (the 4-cylinder diesel engine) also consists of the coil with the core. The core is inserted into the piston. The coil is built in in the case of distributive TNVD. A cam washer, rotating, makes progress back and forth thereof inductance of the coil changes and the signal operating fuel forcing adjustment is given.
The lath course sensor (the 5-cylinder diesel engine) transfers data on the provision of a lath of regulation of supply of fuel to the control unit. The sensor is built in in the regulator of speed of line TNVD. At inclusion of ignition the lath takes a "starting" position (the maximum length of the course of a lath – 19,5 mm). At change of provision of a lath the distance between the coil and a short-circuited washer changes owing to what inductance changes.