Hydraulic pump work there are two kinds of power loss, a power loss is the volume loss, the other is a mechanical loss.
1, the cause of mechanical loss
① hydraulic pump work, the relative motion pieces, such as bearings and shafts, shaft and seal between the blade and the pump body wall between the mechanical friction, resulting in frictional resistance loss. This loss and the hydraulic pump output pressure, the higher the output pressure, the greater the frictional resistance loss.
②. Fluid flow in the pump, due to the viscosity of the liquid and produce viscous resistance, will result in mechanical loss. This loss is related to the viscosity of the oil and the speed of the pump. The more viscous the oil, the higher the pump speed, the greater the mechanical loss.
Due to the above reasons, the actual pump input power is greater than the theoretically required power. Hydraulic pump theoretical input power and the ratio of the actual input power is called mechanical efficiency, it shows the degree of power loss. Hydraulic pump output power and input power ratio is called the total efficiency of the hydraulic pump.
2, the cause of volume loss
①. Positive displacement hydraulic pump suction and discharge chambers are separated in the pump, but the relative movement with the existence of a certain gap, so the pump high pressure area of the oil through the gap will inevitably leak to the low pressure area . The lower the viscosity of hydraulic oil, the higher the pressure, the greater the leak.
②. Hydraulic pump in the oil absorption process, due to oil resistance is too large, the oil too sticky or pump shaft speed is too high and other reasons will cause the pump suction phenomenon, so that the sealed working volume can not be filled with oil, that is to say the hydraulic pump Work chamber is not fully utilized.
Due to the above reasons, the volume loss of the hydraulic pump.
However, as long as the pump is properly designed and used reasonably, the second reason is that the loss can be overcome, which can reduce the volume loss of the pump.
However, the volume loss caused by the leakage of the hydraulic pump during operation is inevitable, that is, the volume loss of the pump can be approximated as all caused by the leakage, so that the actual flow of the hydraulic pump is always less than the theoretical flow
The ratio of the actual flow to the average flow is called the volumetric efficiency, which indicates the degree of volume loss of the hydraulic pump. The volumetric efficiency of a hydraulic pump indicates the extent to which the volume of a hydraulic pump is lost.
