ТНВД the diesel engine. High-pressure fuel pump

The main difference between diesel engines and petrol ones is the other device of the fuel system and the injection system. The most important element in the design is the fuel pump of a diesel engine. This is a high pressure fuel pump .

What is injection pump

This equipment is considered one of the most complicated among other units of diesel power units. The device performs the main function. It supplies fuel to the combustion chambers under very high pressure. This is necessary to supply the combustible mixture to the combustion chambers of the engine at a certain pressure, and only at the right moment for this. The portion of the feed is very accurately measured by electronics. Also, the portion corresponds to the load.

Evolution of injection pump

The government of many countries in the world has significantly tightened the environmental standards for the emission of harmful substances. This led to the fact that the mechanical fuel pump of a diesel engine was gradually replaced by electronic equipment. The mechanics could not cope with the correct metering of the fuel mixture in the required accuracy. In addition, the mechanics could not respond quickly to every change in the operating mode of the power unit.

The most famous manufacturers of electronics offered modern control systems for the supply of a combustible mixture. The introduction of electronics allowed to reduce the instability of fuel combustion, and also reduced the unevenness of idling.

Some devices had in their design a special valve for quick action. This led to the separation of the process of feeding the fuel mixture into the chambers into two parts. This technology has significantly reduced the rigidity of combustion.

Accuracy in injection control also allowed to reduce emissions of toxic substances into the atmosphere. In new engines the mixture burns completely, and the increased efficiency has allowed to increase the efficiency and increase the total output.

Electronic equipment is equipped with distribution equipment. The electronics adjust the position of the dispenser. Also in the structure there is a special valve, which allows to outrun the process of injection.

Types of injection pump

There are several types of pumps by type of injection. So, there are devices for direct action, as well as battery equipment. In the latter systems, the torque adjustment processes are assigned directly to the injectors and electronic control systems.

Direct Pump

The injection pump of a diesel engine with direct action has a mechanical device. The drive is based on the plunger and bushing. This is called the plunger pair. Any processes on this type of equipment are carried out at the same time. In each combustion chamber of the diesel engine, a separate part of the pump supplies the fuel in the required dose. As for the pressure, it is created by the movement of the pump plunger. This equipment is equipped with a lot of diesel cars. Also there is a diesel injection pump of a diesel engine (Volkswagen is not an exception) on this principle.

Accumulator fuel pump

Here, the difference from the traditional pump is that the plunger drive is pressurized directly in the cylinder itself. But in addition, this effect can be provided by means of special springs. There are also devices with hydraulic accumulators, which are installed most often on powerful, but low-speed engines.

It is necessary to say that pumps with a hydraulic accumulator are distinguished by separate injection and injection processes. The combustible mixture under high pressure is pumped into the accumulator and only then it enters the combustion chambers. This campaign allows for more efficient spraying, as well as optimum blend formation, which is excellent for any load. Among the minuses of such a system, you can highlight the even greater complexity of the equipment, which does not contribute to popularity. Modern engines use equipment based on electromagnetic valves and electronic control system.

The distributive pump

These elements, in comparison with in-line, are equipped with one or two plungers, which serve all combustion chambers. The weight and overall dimensions of these devices are much smaller. The quality of their work is much higher. But these systems are characterized by low durability. Often it was necessary to repair the fuel pump of diesel engines. This determined the use of equipment - cars.

Series pumps

This equipment is equipped with plunger pairs. There are as many as the cylinders in the engine. These parts are mounted in a housing where there are special channels for pumping and discharging diesel fuel. To drive the plunger into motion, a special cam shaft is used, which is driven from the crankshaft. In order for the pump to work, the plunger pairs must be pressed against the cams. This is realized by means of springs.

When the cam shaft moves, the cam locks on the pusher, which at this moment moves along its bushing. When the element moves, it opens and closes the openings for the intake and exhaust of fuel. Thus, pressure appears in the system. As a result of this, the pressure valves are opened and the fuel moves along the fuel line to the injectors. This is the work of the diesel injection pump.

For adjustment, the plunger rotates in its bushing. In order to perform this turn, the device has a special gear that is meshed with the rack. The latter is directly connected to the accelerator pedal. The upper part of the plunger is inclined. When turning, you can change the amount of diesel fuel.

This design of in-line pumps has made it possible to provide high reliability. Mechanisms are lubricated by means of motor oils from the lubrication system of the unit. Therefore, you can use fuel of a rather low quality. These pumps are used on large trucks, and on cars they were used until 2000.

The device of high pressure pump of the diesel engine

On the example of a prognostic fuel pump, you can consider the basic device. So, pumps are single-plunger or two-plunger pumps. In this case, one section of the apparatus can supply a combustible mixture to several injectors.

Thus, the equipment consists of a pressure reducing valve, an all-regulator, a drainage connection, a pump section housing together with a plunger pair and valves. In addition, as part of the devices there is a fuel pumping element, an injection timing hatch, a body, a solenoid valve and a plunger drive device.

Apparently, the equipment has a complex device. In the event of a breakdown, diagnosing a fuel pump for a diesel engine will be a difficult task. And it will be very difficult to repair the system even in a garage.

Causes of malfunctions

The cost of these devices is quite high, and the pump itself is very demanding on the quality of fuel and lubricating fluids. If a diesel car is used on bad fuel, then it must contain various solid particles. All this affects the operation of the plunger pair, which has a minimum tolerance. Also, low-quality "diesel" easily disables injectors. Given the complexity of modern diesel injection pump, the price of refueling with low-quality fuel can be very expensive. By the way, the pump costs about 300 dollars.

Among the most popular failures of the pump and nozzles are the following:

• Increased consumption;
• Smoke in the exhaust;
• Noise and other extraneous sounds;
• Power drop;
• Difficult launch.

Naturally, these failures can be caused by other reasons. And to find out whether repair of high-pressure diesel engines is necessary, a special stand is needed. This equipment is only on the SRT, which specialize in similar equipment. Modern pumps do not have those adjustments that would allow to perform diagnostics. Therefore, it is necessary to take the help of professionals.

Repair apparatus

The need for repair can be caused by a variety of reasons. Many failures can not be eliminated with their own hands. However, if repairs are reduced to replacing worn parts, this is easily done in the garage. But you still have to adjust the equipment on a specialized stand.

So, one of the reasons is the wear of the fuel pump of a diesel engine. To define this is quite simple. The power plant will work too unevenly and loudly. Start-up and power loss are also more complicated. About low quality fuel is already said. Still on serviceability influences electronics. For repairs, you often just need to replace what's worn out. But for this it is necessary to disassemble the device. You can do it yourself, but without proper knowledge it's better to turn to professionals.

So, we found out what kinds of high-pressure fuel pumps there are and considered the reasons for their failure.