Hydraulic Pressure Transmission Structure of Diesel Generator

The structure of diesel engine fuel injection pump test-bed is mainly composed of hydraulic pressure transmission, gearbox, combustion system, oil measuring mechanism and power transmission system. This article is mainly about hydraulic pressure transmission.

(1) Hydraulic pressure transmission

The structure of diesel generator hydraulic pressure transmission is mainly composed of oil pump, hydraulic motor, oil pipe, oil suction valve, eccentric adjusting screw and so on. The structure of oil pump and hydraulic motor is the same, both of which are variable vane pumps.

Driven by the motor, the hydraulic oil pump sucks pressure oil from the hydraulic oil tank and the hydraulic motor, sends it to the hydraulic motor through the pipeline and pressure limit, drives the hydraulic motor to work against the resistance of the load, and then flows back to the hydraulic oil pump through the pipeline. The oil pump passes the hydraulic oil pump to the hydraulic horse, so as to form a closed circulating system.

When working in this closed circulation system, only a small amount of hydraulic oil leaks back to the tank from the gap between the oil pump and the hydraulic motor. The leaked hydraulic oil is compensated by the oil pump from the oil tank through the oil suction pipe and oil suction valve. The pressure limiting valve on the oil pipeline acts as a safety valve to prevent damage to the system due to excessive oil pressure.

(2) Gearbox

The gearbox is connected with the hydraulic motor of the hydraulic pressure transmission, and its input shaft is the output shaft of the hydraulic motor, and the output is the output shaft of the test-bed.

The gearbox has two gears: low speed and high speed. Low gear makes the output shaft speed decrease and the output torque increase, while high gear is the opposite. Therefore, during actual operation, the variable speed gear shall be selected according to the type of fuel injection pump being debugged. Generally, low gear is used to debug the fuel injection pump of low-speed high-power engine, while high gear is used to debug the fuel injection pump of High-Speed Low-Power engine.

A dial is installed on the output shaft of the test-bed to determine and adjust the injection starting time of the injection pump and the injection interval angle of each cylinder. At the same time, its inertia is used to stabilize the speed of the output shaft. The dial is equipped with a gapless shrapnel coupling, which is used to connect and drive the fuel injection pump under test.

Cause of issue:

(1) The fuel supply advance angle of the diesel engine is incorrect;

(2) The plunger in the high-pressure oil pump of the diesel engine is stuck and generates heat;

(3) There is no oil in the high-pressure oil pump and the governor, and dry friction occurs in various parts;

(4) The temperature of the body is too high, which causes the temperature of the high-pressure pump to be too high;

(5) In the fuel injector, the oil hole of the nozzle assembly is blocked, causing the diesel fuel sprayed by the high-pressure fuel pump to return to the high-pressure fuel pump under pressure, which will also cause the high-pressure fuel pump to generate heat.

Troubleshooting method:

(1) After the diesel engine stops running, check the fuel supply advance angle. During the inspection, it is found that the fuel supply advance angle is 5°, which becomes the normal value of 28° after adjustment;

(2) Check the oil in the high-pressure oil pump and the governor. It is found that the small scale of the high-pressure oil pump has no oil at the minimum. Open the governor cover and use a screwdriver of about 30cm to check that there is no oil in the governor. It is found that there is about 0.2 The oil height of cm, which does not meet the requirement that the governor should be filled with oil, re-add oil to the high-pressure pump assembly to the required standard;

(3) Start the diesel engine to run for about half an hour, and the heat of the high-pressure oil pump will decrease;

(4) Open the side cover of the high-pressure oil pump and use a flat-blade screwdriver to pry each plunger. It was found that two plungers were stuck when supplying oil. This may be the cause of the high temperature of the high-pressure oil pump (heat generated by friction):

(5)Replace the two plungers of the high-pressure oil pump, and after assembling, adjusting, and testing for 30 minutes, the heat of the high-pressure oil pump is balanced, and the fault with higher temperature is eliminated.

If you are interested in diesel generators, welcome to contact us by email dingbo@dieselgeneratortech.com.