Causes of volume loss

1. Although the oil absorption cavity and drain cavity of the volume hydraulic pump are separated in the pump, there is always a certain gap in the relative motion, so the oil in the high pressure area of the pump must leak into the low pressure area through the gap. The lower the viscosity of hydraulic oil, the higher the pressure, and the greater the leakage.

2. In the process of oil absorption, because the oil absorption resistance is too large, the oil is too sticky or the pump shaft speed is too high, the pump suction phenomenon will be caused, so that the sealed working volume can not be filled with oil, that is to say, the working cavity of the hydraulic pump has not been fully utilized.

Due to the above reasons, the hydraulic pump has volume loss. However, as long as the design of the pump is correct and the use is reasonable, the loss caused by the second reason can be overcome, that is, the volume loss of the pump can be reduced. However, the volume loss caused by leakage is inevitable when the hydraulic pump works, that is to say, the volume loss of the pump can be approximately regarded as all caused by leakage, so that the actual flow rate of the hydraulic pump is always less than the theoretical flow rate. The ratio of actual flow to theoretical flow is called volume efficiency, which represents the degree of volume loss of hydraulic pump.

Causes of mechanical loss

1. When the hydraulic pump works, there is mechanical friction between the relative moving parts, such as between the bearing and the shaft, between the shaft and the seal, and between the blade and the inner wall of the pump body, resulting in friction resistance loss. The loss is related to the output pressure of the hydraulic pump. The higher the output pressure is, the greater the friction resistance loss is.

2.  When the oil flows in the pump, the viscous resistance is generated due to the viscosity of the liquid, and the mechanical loss can be caused. This loss is related to the viscosity of the oil and the speed of the pump, the more viscous the oil, the higher the speed of the pump, and the greater the mechanical loss.