Low-pressure fuel pump of diesel engine: main features and function

The car's engine is often compared to the human heart. And there is a certain similarity. Thanks to the heart man can live, and the car thanks to the motor - to move. The heart pumps blood in the body - it circulates to all key organs. In the engine, this function is performed by the fuel system. Today we will consider the features and purpose of the low-pressure pump. This element is a very important part of the food system. TNDS is necessary for fuel supply to the injection pump. Often it is installed next to the injection pump. Both mechanisms are connected by means of pipes, through which circulation is carried out. At the same time, the fuel passes through the filters, where it is purified.

What is the task of the TNS in the fuel system

The low-pressure fuel pump of a diesel engine solves an important task. The fuel, which is supplied under low pressure, is subject to boiling. As a result, steam jams are formed. Vapors of a pair of light fractions and a thicker fuel are separated. This means that a low-pressure pump will begin to get fluid, the viscosity of which is constantly changing. It is not necessary to talk about fuel injection with the help of high-pressure pump in normal mode. The torch is constantly changing and will not fall into the normal parameters.

How is TINN

The low-pressure fuel pump of the diesel engine consists of the drive shaft. Pumping is carried out using a special rotor, which has blades. Also in the construction there is a stator, a distribution disk and a drive gear. When the rotor is activated, its blades are coming closer to the stator. Then, the chambers are formed due to the effect of centrifugal force. Since voltage is generated in the cavity of the pump, the fuel comes directly from them to the injection pump. To do this, there are channels in the distribution disk. A small amount of diesel will fall into the reduction valve, if the pressure is greater than necessary. Both devices are interconnected, so a special drain choke is used to create and maintain the right conditions. This is a jet that is screwed into a high-pressure pump. This creates conditions in the chambers, depending on how fast the drive shaft rotates.

The device of the pumping pump

The low-pressure fuel pump or low-pressure fuel pump (TIRN) in diesel power units has a simple design. It consists of two gears, which are constantly in clutch with each other. During the rotation, the teeth of these gears create a fuel flow through the fuel system to the high-pressure pump. The main element of the pump pump design is a piston that pumps fuel. For the supply of diesel, two modes of operation of the piston are necessary. This is a working stroke and an auxiliary one.

Varieties of TNRD

The low-pressure fuel pump of a diesel engine is just one kind of these mechanisms. In addition to diesel, these devices can be found in other engines, regardless of the model of the engine or the year of its production. Without a pump can not do - it is necessary to supply fuel from the fuel tank and transfer it further through the system. In the case of carburetor gasoline engines, relatively weak mechanical pumps are used. On units equipped with an injector power system, as well as on diesel power units, an electric fuel pump is used.

Mechanical TННД

This system is installed directly on the cylinder block and fixed with ordinary screws. The operation of such a pump is provided by means of a crankshaft with an eccentric. If you press the eccentric cam, the cuts are created inside. So fuel is fed through the power system. In order that fuel does not get back, the pump is equipped with a special valve. The rest of the pressure on the cam sends petrol to the carburetor. If the vehicle is fitted with a mechanical-type fuel pump, then it is easy to start the engine with it even if long idle time is taken into account. To do this, simply swap the pumping mechanism manually.

Electric

On modern cars use an electric fuel pump of low pressure of the diesel engine and the petrol injection motor. It was simply impossible to use a mechanical device. He, due to lower power, could not cope with the tasks. It does not create the necessary pressure inside the fuel system. In a simpler form, the device is the pump element itself and the electric motor enclosed in one housing. There is also a filter for cleaning fuel, a fuel intake and a fuel flow sensor. The scheme and principle of operation are similar to the algorithm of operation of a mechanical unit. The only difference is that an electric motor is used to pump the liquid. In gasoline engines, the TNS is located directly inside the fuel tank. Most car owners are confident that this is not entirely safe. In fact, there is no danger in this. In the case of gasoline, the fuel in the pump is prone to overheating because of the heat that the engine generates. On electrical analogs, such a problem is completely absent. Fuel without interruptions moves along the nozzles of the system and does not allow the pump to overheat to the critical point. In diesel engines, the electric thrust pump is often combined with a fuel pump. This can be explained by the need to constantly supply fuel. This ensures stable operation of the engine at various speeds.

The fuel pump of a high pressure (ТНВД)

This device is considered one of the most difficult in a diesel engine. Its main task is to ensure the supply of diesel to combustion chambers under high pressure. Feed is provided not just under certain pressure, but at the right time. Portion is very accurately measured by electronics and fully corresponds to the level of load on the unit. There are several types of devices by type of injection. These are units with a battery injection system and with direct action. The arrangement of the fuel pump of a high-pressure diesel engine, in which the direct operating principle is applied, differs in that the design uses a plunger equipped with a mechanical type of drive. So, injection and injection are performed simultaneously. In each combustion chamber, a separate section of the pump atomizes its fuel dose. The necessary pressure is provided by the movement of the plunger mechanism.

Accumulator fuel pumps and their features

Pumps equipped with a battery injection have a difference. Thus, the compressed plunger will be driven by pressurized gases in the engine cylinders. Also, the impact can be provided by means of springs. Devices with a hydraulic type accumulator are now common. They are installed in high-powered engines, operating primarily at low revs.

The basic malfunctions of TNND

The main problem is the decrease in the productivity of the device and the drop in the level of injection that was provided by the low-pressure fuel pump of the diesel engine. It can be determined using a pressure gauge or a pressure sensor that is installed at the inlet. Most often, the reasons for the lowering of the productivity of the TNS are the blockage and jamming of the working element. As for the first reason, diesel fuel may contain various impurities, which, although passing through the filter elements, nevertheless still accumulate in the valve. It is also possible that the elasticity of the element return spring has decreased.

How to repair TNRN

In the event that the efficiency of the unit has fallen, the low-pressure fuel pump of the diesel engine must be dismantled and audited. Often, the productivity rises again after washing and cleaning the working cavities and elements of the device. It will also be superfluous to drain garbage and tar from the drainage compartments. For more serious repairs repair kits are used, which are now produced in Chinese factories that manufacture spare parts for car engines.

Knowing how the low-pressure fuel pump of a diesel engine is arranged, the operating principle of the device can easily be repaired or replaced.