Leakage causes and treatment methods of hydraulic pump

Leakage of hydraulic pump mostly refers to the leakage of hydraulic oil. In work engineering, almost all Hydraulic pumps will have similar problems. Its appearance will not stop the operation of mechanical equipment immediately, but will reduce the volume of hydraulic pump, reduce the working efficiency and limit the increase of rated pressure of hydraulic pump.

The main reason for leakage is that most of the relative moving parts in the hydraulic pump are sealed by clearance seal. When the hydraulic pump is working, the high-pressure oil in the pressure chamber must flow to the suction chamber and other low-pressure places through this clearance, resulting in leakage.

Therefore, controlling leakage and reducing leakage are one of the basic conditions to ensure the normal operation of hydraulic pump. The condition of hydraulic pump leakage is the existence of clearance and pressure difference, and its leakage is proportional to the third power of clearance value and the first power of pressure difference. The leakage of the pump is mainly analyzed from three aspects: the size of seal clearance, the pressure difference between the clearances and whether the movement increases the leakage or not.

As the annular clearance between the piston and the cylinder block bore is easily controlled and other clearances are easily compensated, the volumetric efficiency and rated pressure of the piston pump are both high. The main leakage clearance in Vane Pump is the end clearance between rotor and port plate, and the clearance between vane and vane groove of rotor, top of vane and inner ring of stator. In order to reduce leakage, some medium and high pressure double-acting vane pumps design the port plate as floating port plate to realize automatic compensation of end clearance.

The main leakage clearance of the piston pump is the annular clearance between the piston and the bore of the cylinder block, followed by the end clearance between the cylinder block and the port plate of the axial piston pump, and the plane clearance between the sliding track and the swash plate. For radial piston pumps, in addition to the annular gap between the piston and the bore of the cylinder block, there are also the radial gap between the cylinder block and the distribution shaft, and the gap between the sliding track and the inner stator ring.

Clearance, meshing clearance between two meshing teeth. Medium and high pressure gear pump end clearance is compensated by automatic floating compensation mechanism.

The main clearance of the external engagement gear pump is the clearance between the gear end face and the front and rear pump cover or the left and right side plates, and then the radial direction between the tooth top and the inner circle of the pump body.