Mercedes S-Class W-140
1991-1999 of release
Repair and car operation
+ Mercedes-Benz Cars of a class S (W-140)
+ Operation manual
+ Routine maintenance
+ Systems of cooling, heating
- Power supply system and release
+ the Power supply system and injection of fuel of the petrol engine - the general information
- System of injection of fuel of the diesel engine - the general information
Checks of system of injection of fuel
+ Control system of injection of fuel and HFM-SFI ignition (6-cylinder petrol engines)
+ Control systems of the LH-SFI and ME-SFI engine (8-cylinder petrol engines)
+ Control systems of injection of fuel and ME-SFI and LH-SFI ignition (12-cylinder petrol engines)
+ Control system of fuel injection (diesel engines of the Om603.971 series)
+ Control system of fuel injection (diesel engines of the Om606.961 series)
+ turbo-supercharging System - the general information
Systems of decrease in toxicity of release - the general information
System of production of the fulfilled gases - the general information
Catalytic converter (petrol models)
+ engine Electric equipment
+ gear shifting Box
+ Avtomaticheckaya transmission
+ Brake system
+ Suspension bracket and steering
+ Onboard electric equipment
System of injection of fuel of the diesel engine - the general information
Into structure of fuel system enter: established in a back part of the car (under a pillow of a back seat) a fuel tank, the fuel filter, nozzles, fuel tubes and hoses, the sensor of a stock of the fuel, located in a tank and the block of electronic control by the engine.
Fuel moves the special pump via the filter. In the filter dirt and the water containing in fuel settles.
At operation of the diesel engine in its cylinders clean air which is compressed to a high pressure is soaked up.
Thus air temperature rises to 700 - 900°С, exceeding temperature of ignition of diesel fuel. Fuel is injected into the cylinder with some advancing and ignites. Thus, spark plugs for ignition of fuel are not used.
For reduction of a share of harmful substances in the fulfilled gases diesel engines have the diesel oxidizing catalytic converter. At the same time the system of a retsirkulyatsiya provides essential decrease in the fulfilled gases the content of oxides of nitrogen. It is reached thanks to supply of the fulfilled gases to air soaked up by the engine that provides decrease in concentration of oxygen in the air arriving in cylinders of the engine. It leads to decrease in a delay of ignition and to lower temperature of combustion that as a result reduces formation of NOx. Process of a retsirkulyatsiya of the fulfilled gases should be dosed out precisely however, the maintenance of a soot otherwise increases in the fulfilled gases. For this purpose the amount of sucked-in air is defined by a measuring instrument that allows the electronic device to operate retsirkulyatsiya process.
Injection of fuel is carried out directly in the combustion chamber.
Function chart of system of injection of the diesel engine
Pneumoconnections on sensors
The engine copes the electronic system similar to a control system of petrol engines. The system operates operation of the engine, analyzing information arriving from a large number of sensors.
Scheme of laying of vacuum connectionsScheme of laying of vacuum lines (the turbodiesel engine of 3.0 l)
On diesel models there is no accelerator cable. Instead of it on a pedal the sensor of its situation is established.
The valve of an otsechka of fuel at switching off of ignition is absent. To muffle the engine at ignition switching off, the control unit the engine sends a signal which, in turn, stops supply of fuel to nozzles to the TNVD control unit.
The fuel system is designed so that not to allow «подсоса» some air in the absence of fuel in a tank. The control unit constantly checks fuel level in a tank, processing information arriving from the sensor of a stock of fuel, located in a tank. When falling a stock of fuel to a certain level the control unit lights warning lamp on a control panel then compulsorily causes admissions of supply of fuel, limiting to that the maximum speed. It proceeds until fuel level in a tank will not exceed an admissible mark.
Information on position of the crankshaft and speed of rotation of the engine arrives in the control unit from the sensor of position of the crankshaft (CKP). The inductive head of the sensor is located opposite to a flywheel and constantly scans special labels (36 pieces), put on its surface. When passing label by a sensor head it sends an impulse to the control unit. Labels are evenly put on a flywheel surface, but one label is passed. It should settle down in 90 ° to VMT of the first cylinder. At the moment of passing by a flywheel of this point the sensor does not send an impulse to the control unit. The block distinguishes this pause and precisely defines VMT moment. Duration of this pause is used for determination of speed of rotation of the engine.
Information on quantity and temperature of air arriving in the engine arrives from the sensor of absolute pressure the inlet pipeline (MAP) and air temperature sensors. The sensor of absolute pressure is connected to the pipeline a vacuum hose and measures pressure in it. Two sensors of air temperature are established. One is established before a turbokompressor, and another - after an interkuler. The temperature and pressure of air are used for calculation of exact amount of fuel which is necessary to fall to nozzles.
The traditional sensor of temperature of cooling liquid is replaced with the sensor of temperature of a head of the block. It takes temperature of a head and sends received information to the control unit. Analyzing this information, the control unit corrects structure and the moment of injection of a fuel mix, and also operates system of warming up of the cold engine.
The switch of stoplights and the sensor of a pedal of a brake informs the control unit on the current provision of a pedal of a brake. When receiving signals from these sensors the control system instantly transfers the engine to idling until will receive a signal from the sensor of provision of a pedal of an accelerator.
The cable of an accelerator is absent. Instead of it on the sensor of provision of a pedal of an accelerator is established. The sensor constantly informs the control unit on the provision of a pedal which, in turn, precisely counts injection parameters. Single turns also are regulated by the control unit and cannot be adjusted manually. Analyzing information arriving from various sensors, the control unit counts size of turns of idling, correcting them depending on load of the engine and its temperature.
The system of injection of fuel is system of direct injection. In the bottoms of pistons there are the vortical chambers providing a turbulence of combustion arriving in chambers of fuel. For optimization of combustion of fuel of a nozzle open in two stages (for this purpose in each nozzle there are two springs). When opening nozzle the small part of fuel gets on internal components of a nozzle, greasing them, and comes back to a fuel tank.
Management of warming up of the cold engine is carried out by the control unit the engine. At the cold engine the moment of injection is displaced by the control unit. The control unit the engine, in turn, operates work of candles of an incandescence. Glow plugs are established in each cylinder and join before engine start, I work during an engine provorachivaniye with a starter and some time after engine start. Candles considerably facilitate start of the cold engine. After ignition inclusion on a control panel the corresponding control lamp (address to the car Equipment, an arrangement of devices and governing bodies of Head the Operation manual), signaling about inclusion of candles of an incandescence lights up. As soon as the lamp will go out, you can start the engine. If air temperature very low, candles continue to work still some time after engine start. It reaches stable operation of the engine and decrease in harmful impurity in the fulfilled gases.
Owing to high starting qualities of the engine with direct injection in a cold condition preliminary heat is required only at temperature below - 10°С.
Fuel passes through the fuel filter. In the filter fuel separates from water and pollution. Therefore it is important to delete water from fuel and to make timely replacement of a filtering element.
The fuel system of diesel engines is very reliable. During the using of pure fuel and performance of regular service it should function regularly before the termination of service life of the car. After very big run internal components of nozzles can wear out, and they will be necessary for repairing. As the pump - nozzles have a difficult design, repair is recommended to be carried out in a specialized workshop.