VW Passat B5
since 1996 release
Repair and operation of the car
Foltsvagen Passat B5
+ Maintenance instruction
+ 1. Maintenance
+ 2. Engines
+ 3. Cooling system
- 4. Fuel system
4.2. Fuel pump / fuel level sensor
4.3. The fuel filter on models with petrol engines
4.4. Adjustment of a cable of an accelerator (petrol engine)
4.5. Additional adjustment (automatic transmission)
- 4.6. Fuel system of the diesel engine
4.6.2. General information
4.6.3. Check of system of preliminary heating of the diesel engine
4.6.4. Check of candles of an incandescence
4.6.5. Glow plugs
4.6.6. System of heating of fuel
4.6.7. Fuel nozzles
4.6.8. Main malfunctions of a control system of the engine
+ 5. Engine management
+ 6. Exhaust system
+ 7. Transmission
+ 8. Running gear
+ 9. Steering
+ 10. Brake system
+ 11. Body
+ 12. Heating, ventilation
+ 13. Electric equipment
Arrangement of elements of management of the diesel engine in a motor compartment
Arrangement of vacuum hoses in a control system of the diesel engine
This type of the engine received the name by name the German engineer Rudolf Diesel who constructed in 1897 the first engine with fuel spontaneous ignition. Structurally diesel engine is similar to the petrol engine: same cylinders, pistons, camshaft, valves. But there is also a number of differences from which the main thing, it is possible even to tell basic, is that ignition of fuel in the diesel engine is made not by a spark from a spark plug, and due to high temperature which is reached by air as a result of compression by its piston in the cylinder.
The second important point – a way of supply of fuel. In the petrol engine a working body is gasoline mix with air. Mix prepares in advance (in the carburetor) or directly at the time of its giving in cylinders (in systems of injection) – the main thing the fact that fuel moves together with air, and is set fire and stuffy mix burns down rather homogeneous топливовоз.
In the diesel engine supply of fuel and air happens separately. In the beginning in the cylinder air is soaked up, then it contracts, and fuel therefore it is not necessary to speak about homogeneous fuel-air mix is injected only after that. The injection is made at the end of a compression step, fuel and air actually do not mix up with each other, burning happens the fuel stream injected into compressed air at the front.
Spontaneous ignition of fuel is followed by sharp, spasmodic increase in pressure in the cylinder – usually noisy, rigid operation of the diesel engine is explained by it. In low-reverse diesel engines with the large working volume which are used by trucks this shortcoming is shown to a lesser extent, and with it are reconciled. In diesel engines of cars try to get rid of it use of the vortex camera, or precamera, – a small compartment of the combustion chamber into which fuel is injected. There it ignites, partially mixes up with air then the burning mix spreads on the main volume of the cylinder. This way reduces rigidity of operation of the engine a little, but reduces its thermal efficiency and fuel profitability. For smoother ignition of fuel the two-level injection and the difficult electronic scheme of management are used.
Characteristic of diesel engines is existence of firm particles in the fulfilled gases. Because of heterogeneity of process of burning on поверхнос ти separate particles of fuel some lack of oxygen therefore instead of their oxidation there is a partial thermal decomposition to formation of firm products – soot is always observed. Good combustion of diesel fuel requires considerable, even excess amount of air.
Also, extent of compression at the diesel engine is twice higher, than at the petrol engine. High, not less than 14 (reaches 25), extent of compression is necessary in order that air temperature in the cylinder rose up to the size sufficient for fuel ignition. Usually in diesel engines extent of compression makes 21–22 and is limited only to strength characteristics of the engine.
In diesel engines it is much more difficult than the device for supply of fuel, than in petrol. Their complexity determines ся first of all by what it is necessary to inject very small, only several milligram, portions of fuel on Wednesday with high pressure. These portions have to be very precisely measured – amount of the given fuel operation of the diesel engine copes. Shchy and exact nozzles are for this purpose necessary bystrodeystvy. High extent of compression demands application to a sootvetstvo of yushchy fuel pumps – pressure in a snivel of a nozzle has to reach several hundred bars. All this complicates and noticeably raises the price of a fuel supply system and, respectively, the diesel engine.
Fuel from the fuel tank gets the fuel pump of high pressure, and then under high pressure moves to fuel nozzles.
For reduction of amount of the harmful substances which are contained in exhaust gases on cars with diesel engines the oxidizing catalyst is installed. Also the system of admixture of exhaust gases to the fresh air coming to the engine therefore percentage of oxygen in air which will be burned in engine cylinders decreases is used. As a result of it temperature of combustion of fuel mix therefore the amount of the formed nitrogen oxides decreases decreases.
Three ways of injection of diesel fuel in engine cylinders are known. Through a forkamer, via the vortex camera and direct injection.
At injection of diesel fuel through a forkamer fuel is sprayed after a forkamer and instantly ignites. Due to insignificant amount of oxygen in a forkamer only a part of fuel burns down, and other fuel is forced out from forkamer in the engine cylinder where burns down completely.
At injection of fuel via the vortex camera process of combustion of fuel is made in the same way, as well as at injection of fuel through a forkamer. Difference consists in a form and the sizes of the channel connecting the vortex camera to the combustion chamber. At injection of fuel in the vortex camera occurs the best hashing of fuel with air is considerable, and process of combustion is carried out more smoothly.
At direct injection of fuel fuel moves directly in the combustion chamber. The fuel pump gives fuel under pressure of about 900 bars, and the injection of fuel is made in two stages.
Use of two-channel fuel nozzles the neznachitel gives the chance to make initial injection ache parts of fuel therefore fuel combustion process improves, and process of combustion proceeds more smoothly. The amount of injectable fuel is regulated by an electronic control system of the engine. The amount of injectable fuel is regulated by a control system on the basis of information from the following sensors:
The air coming to the engine in inlet canals twists on a spiral therefore process of combustion in engine cylinders improves. Also at the same time start of the cold engine is facilitated, and preliminary heating of the engine needs to be made at air temperatures lower than -10 °.
Before intake of fuel in the fuel pump of high pressure fuel passes through the fuel filter in which from it water which needs to be merged periodically also separates.
The drive of the fuel pump is carried out from a bent shaft of the engine through a gear belt. Internal mobile details of the fuel pump are greased with diesel fuel.