Structure and principle of HYDRAULIC GEAR PUMP

HYDRAULIC GEAR PUMP consists of a pair of gears installed in the housing. The two sides of the gear are covered by the end cover, and the housing, the end cover, and the interdental grooves of the gear form many sealed working chambers. Let's take a look at the structure of the HYDRAULIC GEAR PUMP and the possible leaks and solutions.

Here is the content list:

• Structure of HYDRAULIC GEAR PUMP

• POSSIBLE ROUTES OF HYDRAULIC GEAR PUMP LEAK

Structure of HYDRAULIC GEAR PUMP

When the gear rotates, the right oil suction chamber of the HYDRAULIC GEAR PUMP is gradually disengaged due to the gears meshing with each other, and the sealing working volume gradually increases to form a partial vacuum. Therefore, under the action of external atmospheric pressure, the oil in the oil tank enters the oil suction chamber through the oil suction pipe, fills the interdental grooves, and rotates with the gears to bring the oil to the oil pressure chamber on the left. On one side of the oil pressure area, since the gears of the HYDRAULIC GEAR PUMP are gradually engaged here, the volume of the sealed working chamber is continuously reduced, and the oil is squeezed out and sent from the oil pressure chamber to the oil pressure pipeline. Here, the tooth surface contact line at the meshing point has been playing the role of isolating the high and low-pressure chambers.

Ways and solutions that may cause leakage of HYDRAULIC GEAR PUMP

There are 3 main leakage paths when the HYDRAULIC GEAR PUMP is running. The first is the gap between the tooth top and the inner wall of the gear housing, which accounts for about 15% to 20% of the total leakage of HYDRAULIC GEAR PUMP. The second is the engagement point, which accounts for about 5% of the total leakage of HYDRAULIC GEAR PUMP. Finally, the gap between the tooth end face and the two end caps accounts for about 75% to 80% of the total leakage of HYDRAULIC GEAR PUMP. When the pressure increases, the first two do not change, but the deflection of the end cover increases greatly, which is the main reason for the leakage of HYDRAULIC GEAR PUMP, so external gear pumps are not suitable for high-pressure pumps. To solve the internal leakage problem of the HYDRAULIC GEAR PUMP and increase its pressure, the fixed side plate type HYDRAULIC GEAR PUMP has been gradually developed, and its maximum pressure can reach 7-10MPa; the movable side plate type HYDRAULIC GEAR PUMP is pushed inward when the pressure is high. Gear end face to reduce internal leakage at high pressure, the maximum pressure can reach 14-17MPa. In short, the higher the pump discharge pressure, the greater the leakage. During the operation of the involute HYDRAULIC GEAR PUMP, because the closed volume at the intersection of the gear changes with time, a part of the hydraulic oil is often sealed between the teeth, which we call the trapped oil phenomenon. Because the hydraulic oil is incompressible, it will cause great vibration and noise during the operation of external gear pumps, so unloading grooves must be provided on the side plates to prevent vibration and noise.

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