Numerical Analysis on the Performance of Control Valve in Variable Displacement Wobble Plate Compressor

The performance of control valve is analyzed in this paper in order to study characteristics of the variable displacement wobble plate compressor. The forces acting on the control valve are analyzed and the mathematical model to analyze its performance is developed. A test bench is set up to get the steady and dynamic performance of control valve. The steady-state performances predicted by the mathematical model agree well with the experimental data while the predicted dynamic performances agree with the experimental results qualitatively. With the mathematical model, the steady-state performances of the control valve with four different preset control points and three different effective areas of the evacuated bellows have been analyzed, and the dynamic behavior of one type control valve has been studied. It is shown that: (1) the suction pressure at preset control point is inversely proportional to the discharge pressure; (2) the larger the starting force of spring in control valve or the smaller the effective area of evacuated bellows, the larger the suction pressure at preset control point; and the larger the starting force of spring in control valve and the smaller the maximum opening of ball valve, the more quickly the crankcase pressure changes and the smaller mass flow rate of control valve; the slope ratio of crankcase pressure to suction pressure cannot be influenced by the starting force of spring in control valve but can be influenced by the effective area of evacuated bellows; (3) the transition time of the crankcase pressure is about 1 s and can be neglected when working condition changes.