Change in Oil Pressure in Piston Chamber of a Radial Piston Pump Pre-compression Area When Considering the Compressibility of Oil

Abstract

The mathematical model of the change in oil pressure in the piston chamber of the radial piston pump pre-compression area and the CFD geometric model for field simulation were set up considering the compressibility of oil, and the variation curves for pressure were obtained by the two methods. The conclusion obtained from the variation curve and the contours of pressure and velocity vector is that the oil pressure is gradually increased under the action of mechanical compression and flow from the damping groove, and the oil flow to the piston chamber from the outlet port before reaching the discharge oil pressure. It is found that the trend change of the two curves is the same, and the value of the relative error between the CFD model and the mathematical model is large in the middle, small at both ends, and less than 5%. Then two oil pressure gradients obtained from the two methods, respectively, are calculated for the pre-compression area and the curves are plotted. It can be seen that the pressure gradient of the two curves is equal at 10.1 degrees, and the relations are different before and after 10.1 degrees. Finally, the influence of the bottom edge length of the cross section of the triangular groove and the span angle of the triangular groove on the oil pressure in the pre-compression area is analyzed. The law in effect is that the two parameters for oil pressure in the piston chamber are opposed such that the value of the length of the bottom edge and the span angle of triangular groove should be comprehensively considered in order to decrease the impact of the pressure. The value of the length of the bottom edge can not be too large and the value of the span angle can not be too small.