Vane pumps are mostly used as medium and low hydraulic pressure sources. Pay attention to the viscosity of hydraulic oil during use. It is recommended to use oil with a viscosity of 2.5 ~ 5 ° C EVA50 and check the oil or composition regularly; the capacity of the oil tank should be 3 ~ 6 times the flow rate of the pump per minute. Pay attention to prevent bearing axial force, otherwise it will cause early wear of the oil distribution pan, causing a drop in pressure and efficiency. The vane pump inlet pipe must not leak air. Pay attention to the following two points during installation and use.
① The rotational speed of the vane pump is high. When the rotational speed is too low, the vane pump cannot be close to the inner surface of the stator, and the pressure cannot be established. If the rotational speed is too high, the pump will not suck enough oil and cause a vacuum.
②The anti-pollution ability of the vane pump is worse than that of the gear pump. For this reason, the accuracy of the oil filter in the oil inlet should be set to 30 mm.
Hitachi excavator vane pump failure and troubleshooting are as follows.
1. The pump does not produce oil, the pressure gauge shows no pressure
①The liquid level of the fuel tank is too low. Add hydraulic oil to the tank.
② The dirt of the oil suction pipe or the oil filter is blocked. Remove dirt.
③ Leakage in the oil suction chamber (oil seal, pump body suction pipe joint). If there are troughs or air holes in the oil suction chamber, replace the pump body; if there are cracks in the oil suction pipe, whether the pipe joint nut is tightened, check the sealing performance and quality of the oil seal.
④ The blade is stuck in the rotor slot and cannot be thrown out at all, or the blade is broken, causing the high and low pressure chambers to communicate. The blade and the groove are too tightly fitted, and the clearance should be 0.015 ~ 0.02mm, and should be deburred.
⑤ Defective oil distribution pan and poor contact between the oil distribution pan and the pump body cause the sealed area to be communicated, and the side of the oil distribution cap is slightly deformed. Trim the contact surface between the oil pan and the rotor.
⑥ The motor reverses. Rotate the motor forward.
⑦ The speed of the pump is too low. Adjust the speed or replace the motor.
⑧ The viscosity of the oil is too high. Use oil of appropriate viscosity instead.
⑨The connection key is not installed or the spline shaft does not rotate or the spline shaft twists. Install the connecting key and replace the spline shaft.
⑩ The suction pipe is too long. Bring the pump closer to the oil tank, which shortens the length of the oil inlet pipe accordingly.
? The quality of the pump body is not good, there are trachoma, air holes, etc. Replace the new pump body.
2. The volumetric efficiency is low, the pressure is not high
①The blades or rotors are reversed. correct.
② The clearance between the blade and the blade groove is too large. The blade is re-formed according to the blade groove size. The gap between the blade and the blade groove should be controlled within the range of 0.013-0.018mm.
③The stator oil suction cavity is seriously worn, the blade tip is missing or brushed. The stator can be turned 180 ° to make the oil suction chamber and the oil pressure chamber interchangeable, and the positioning hole can be reprocessed; the tip of the blade can be trimmed or replaced.
④ The inner curve of the pump stator wears. Grind or exchange on a dedicated grinder.
⑤The axial clearance is too large, and the internal leakage is serious. Repair stator, rotor, blades, control the axial gap between 0.04 ~ 0.07mm.
⑥The oil intake is not smooth. Clean the filter and replace the working fluid.
⑦ Poorly installed or damaged oil seal. Refit or replace.
The system is leaking. Check the leakage of pipes, pipe joints and valves in the system.
