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Hydraulic pump leakage and treatment methods
Hydraulic pump leakage mostly refers to hydraulic oil leakage. In work projects, almost all hydraulic pumps will have similar problems. Its occurrence will not cause the mechanical equipment to stop working immediately, but it will reduce the volume of the hydraulic pump. It reduces the operating efficiency and limits the increase in the rated pressure of the hydraulic pump.
The main cause of leakage: Since most of the relatively moving parts in the hydraulic pump are sealed by gap seals, when the hydraulic pump is working, the high-pressure oil in the oil pressure chamber must flow through this gap to the oil suction chamber and other low-pressure places, thus causing leakage.
Therefore, controlling and reducing leakage is one of the basic conditions to ensure the normal operation of the hydraulic pump. The condition for hydraulic pump leakage is the existence of a gap and a pressure difference, and the leakage amount is proportional to the cubic value of the gap and proportional to the first power of the pressure difference. To analyze the leakage of the pump, we mainly start from three aspects: the size of the sealing gap, the gap pressure difference, and whether movement increases leakage.
Since the machining accuracy of the annular gap between the plunger and the cylinder hole is easy to control, and other gaps are easy to compensate, the volumetric efficiency and rated pressure of the plunger pump are both high. The main leakage gap in a vane pump is the end gap between the rotor and the distribution plate, followed by the gap between the blades and the rotor blade grooves, and the gap between the blade top and the stator inner ring. In order to reduce leakage in medium- and high-pressure double-acting vane pumps, some design the valve plate as a floating valve plate to realize automatic compensation of the end face gap.
The main leakage gap of the piston pump is the annular gap between the plunger and the cylinder hole, followed by the end gap between the axial piston pump cylinder and the valve plate, and the plane gap between the sliding shoe and the swash plate. For radial piston pumps, in addition to the annular gap between the plunger and the cylinder hole, there is also a radial gap between the cylinder and the distribution shaft, and a gap between the sliding shoe and the stator inner ring.
Clearance, the meshing gap between two meshing gear teeth. The end clearance of medium and high pressure gear pumps is compensated by an automatic floating compensation mechanism.
For external meshing gear pumps, the main clearance is the end clearance between the gear end face and the front and rear pump covers or the left and right side plates, followed by the radial clearance between the tooth top and the inner circle of the pump body.
