6.3. Power supply system of diesel engines
General information
During the operation of the diesel engine in its cylinders external air which compresses to high pressure is soaked up. At the same time air temperature as a result of adiabatic heating rises to the level of 700-900 °C exceeding a point of ignition of diesel fuel. Fuel is injected into the cylinder with some advancing and ignites. Thus, need for use of spark plugs disappears.
As well as on petrol models the power supply system consists of two paths: supply of fuel and air supply; control of functioning of system is exercised by the special electronic module (ECM). In more detail the principle of functioning of a control system of the diesel engine / decrease in toxicity of the fulfilled gases is stated in the Section System of Self-diagnostics of Diesel Models (see the Part of the Control system of the engine and decrease in toxicity of the fulfilled gases).
System of air supply
The main features of a structure of the inlet air highway of the diesel engine considered in the present manual are use in it of the turbocompressor given to rotation by a stream of the fulfilled gases and lack of a drosselirovaniye on an admission (it is characteristic of the diesels equipped with TNVD of distributive type). Additional increase in a consumption of air of pressurization is provided due to its thermal compression in the heat exchanger of an intermediate cooler (Intercooler).
Structure of the inlet air highway of the diesel engine
|
|
|
|
1 — the Air cleaner |
3 — To system of production of the fulfilled gases |
Turbocompressor
For rotation of the compressor of system of pressurization the stream of the fulfilled engine gases given to the case of turbine assembly is used, - the driving wheel of the compressor is put on one shaft with a wheel of the turbine and the rotation provides compression of the air passing through the air cleaner and its giving under a pressure in the inlet pipeline of the engine. Such design of the compressor guarantees immediacy of reaction of system of pressurization to the change of loads of the engine outright connected with intensity of release of the engine.
Turbocompressor design
The structure of a turbocompressor switched on two sensors: temperatures (TA) and pressure of air of pressurization. On the basis of the analysis of the data arriving from these PCM sensors defines amount of the air coming to the engine.
Intermediate cooler (Intercooler)
The heat exchanger of an intermediate cooler which is switched on in an inlet air path of the turbocharged engine serves for compensation of effect of an adiabatic warming up of the air forced by the compressor. The heat exchanger is installed at the exit from the compressor and during the movement of the car continuously is blown by the running stream of the air taken by the air inlet formed in a cowl cover - when cooling air compresses that in addition increases efficiency of functioning of system of pressurization.
|
|
The heat exchanger of an intermediate cooler of system of pressurization is installed at the exit from a turbocompressor. |
Fuel supply system
The fuel supply system of diesel engines differs in high degree of reliability and at conscientious performing procedures of regular service with observance of requirements of Specifications of the Head of the Power supply system, management of engine/decrease in toxicity of the fulfilled gases and production of the fulfilled gases to type of the used fuel has to function regularly during all service life of the car.
|
|
As a result of long use internal components of nozzles can wear out. Performance of recovery repair of nozzles will be correct to charge to specialists of car service. |
Basic element of a fuel path of the diesel engine of the considered models is the pump of the high pressure (TNVD) of distributive type (VE) with electronic control which is carrying out absorption of fuel via the filter from the fuel tank located behind under the car and its dosed distribution through nozzles in engine combustion chambers.
Scheme of the organization of a fuel supply system of the diesel engine
Fuel Pump of High Pressure (FPHP)
The principle of absorption and compression of fuel in electronic TNVD is similar to the principle used in pumps of mechanical type. The main difference of the electronic pump is use instead of the centrifugal proofreader of the moments of injection of the electronic regulator with the hummock drive (instead of lever).
onstruktion of electronic TNVD of distributive type
Electronic regulator (GE)
The executive GE mechanism is fixed on the camera of the regulator in the top part of assembly of TNVD.
Design of the TNVD electronic regulator of distributive type
|
|
|
|
1 — the Coil |
5 — the Core |
The phenomenon of emergence of magnetic field when giving on a winding of the coil of electric current is the basis for functioning of the regulator. Tension of the induced field will be directly proportional to force of the current passed through a winding that provides a possibility of deployment of a rotor of the regulator in required position with overcoming the effort developed by a returnable spring, - due to rotation of a rotor controlled linear movement of the managing director of the coupling is provided.
|
|
Principle of functioning of the regulator. |
The magnetic filter which is a part of the regulator provides protection of working cameras of pump assembly against hit of foreign objects in them.
Valve of management of distribution of the moments of injection (TCV)
TCV is located between high-pressure and low pressure cameras and provides adjustment of pressure due to opening when giving power supply.
When food on the valve does not move, cameras remain isolated. Opening of TCV leads to their association, as a result the distributive piston is displaced under the influence of the effort developed by a spring in the situation providing alignment of pressure - correction of the moment of injection is carried out due to simultaneous turning of the roller holder.
The sensor of position of the operating coupling (CSP)
The sensor is located in the top part of assembly of the regulator and delivers to ECM information on position of the operating coupling which movement leads to turning on a certain corner of a sensitive element of the sensor due to change of a difference of induktivnost in its top and lower windings. ECM compares the obtained data with the required value and in case of need issues the command for performance of the corresponding adjustment by change of force of the current passed through windings.
|
|
The special fixed plate provides compensation of temperature changes of inductance. |
Sensor of position of the distributive piston (TPS)
TPS is connected to the low-voltage party of the distributing device, consists of the rod core and the reel and serves for the notification of ECM about movement of the distributive piston, - movement of the piston leads to change of inductance of the coil of the sensor as a result of the corresponding movement of the core.
Np
The Np sensor delivers to ECM information on TNVD turns. The sensor represents the solenoid reacting to passing by its magnet of each of 4 teeths of the rotating alarm plate. The alternating current developed when passing by teeths through magnetic field will be transformed to the pulse signals given on the module of management.