Design and Characteristic Research on Variable Displacement Mechanism of Two-Dimensional (2D) Bivariable Pump

In a hydraulic system, a micro variable pump is required to be high pressure and high speed, and this work presents a new type of 2D bivariable pump structure in which the worm gear and worm mechanism are used to rotate the cylinder block to change the flow distribution state of the cylinder window and the piston groove to change the displacement of the 2D pump. The flow–pressure mathematical model of the 2D variable pump is established to analyze the relationship between pump displacement and the pump cylinder rotation angle and the effects of variable displacement on pump pressure characteristics, flow characteristics, and volume efficiency in Matlab. During the experiment, we tested the change in the corresponding pump output flow when the cylinder rotation angle is 0~12°, which verifies the correctness of the variable calculation model. The experimental results indicate that the volume efficiency and mechanical efficiency of the single-piston 2D pump are reduced to different degrees after variable displacement, the volume efficiency is reduced by approximately 3% at most, and the mechanical efficiency is reduced by approximately 5% at most.