Simulation and performance analysis of control mechanism in variable displacement swash plate compressor

The mathematical model of the control mechanism used in a variable displacement swash plate compressor (VDSC) is developed based on the force balance equation, mass and energy conservation equation. In order to verify the mathematical model, a test bench of control mechanism and test system of VDSC are established, and the simulated results agree well with the experimental data. With the mathematical model, the steady-state performance of control mechanism is simulated. The simulation results show that there is an inflection point (defined as the preset point) to divide the opening process of mass flow compensation control valve into a gradual opening stage and a quick opening stage. In the gradual opening stage, the swash plate case pressure goes down quickly and the mass flow rate rises along with the increase of suction pressure; in the quick opening stage, the swash plate case pressure goes up and the mass flow rate goes down along with the increase of suction pressure. The suction pressure at the preset point is linear inversely proportional to the discharge pressure.