How does the hydraulic pump/motor change with pressure and speed?

When hydraulic pumps, hydraulic motors and hydraulic cylinders transmit energy, there will be a certain energy loss. These losses also determine the efficiency and need to be taken into account in the calculations.

The overall efficiency depends to a large extent on the structure of the equipment, manufacturing accuracy, aging degree of the equipment and other operating parameters. In the actual calculation of hydraulic equipment, these parameters need to be considered.

Several inefficient meanings:

Volumetric efficiency ηv: related to internal and external leakage of hydraulic pump/hydraulic motor;

Hydraulic mechanical efficiency ηhm: related to friction loss of hydraulic pump/hydraulic motor;

Total efficiency ηt=ηv*ηhm: The overall loss of hydraulic pump/hydraulic motor during power transmission.

Figure 1 The relationship between pressure and efficiency at a fixed speed n

Figure 2 The relationship between speed and efficiency under a fixed pressure P

Figure 3 Variable displacement pump: at a fixed speed n and a fixed pressure P, the relationship between displacement V/maximum displacement Vmax and efficiency

Fig.4 The relationship between oil viscosity v and efficiency under fixed speed n and fixed pressure P