Study On The Operating Characteristic Of Reed Valve In Rolling Piston Compressor For Household Air Conditioner

The reed valve with a circular arc lift limiter is widely used in rolling piston compressor for household air condition. Because of the differences of operating characteristic between rolling piston compressor and reciprocating compressor, the design method and operating characteristic of their reed valves are different. A circular arc lift limiter can reduce the stress of valve root, but the movement law of valve plate is approximated as a winding model, which is difficult to calculate by using the beam or plate model. Therefore, it is necessary to develop some methods for the design and operating characteristic study of the reed valve.In this paper, the reed valve with a circular arc lift limiter in a rolling piston compressor is designed, and formulas for calculating the average Mach number and resistance loss of gas flow in the valve play are derived. With the variation of free segment length of valve plate in the winding process, the equivalent motion mass and elastic force of valve plate is changing constantly. Then the stiffness curve of valve plate is found by static analysis. Based on a single mass model, stiffness curve of valve plate and the gas flow differential equation of discharge process, the mathematical model of reed valve is established, and then solved by using the Runge-Kutter method in the Visual Basic software. Comparative study on the movement law of valve plate with the circular arc lift limiter and the linear one at different rotation speed of compressor, the influence of rotation speed of compressor and the molded line of lift limiter are researched, then an improvement suggestion is gave for the vibration of the head of valve plate with a circular arc lift limiter. In order to calculate the initial velocity of valve plate impacting against the seat, the energy conservation principle is used between the impact kinetic energy and elastic energy of valve plate, and the elastic energy can be calculated when the valve plate is whole winding along the circular arc lift limiter. In order to study the impact stress and its distribution of valve plate against the seat, the equivalent mass coefficient, concentrated load coefficient and impact load coefficient are calculated by using the simplified impact model which is established on the Rally-finite element method. Then the nonlinear explicit dynamic analysis software ANSYS/LS-DYNA is used to simulate the impact process of reed valve against lift limiter and valve seat, and the effect of inertia to the wind model is analyzed. The dynamic responses of valve plate from the result of simulation verified that the winding model and Rally-finite element model are reliable for the study of the operating characteristic of reed valve in rolling piston compressor. Lastly, the calculation programs for the curve of stiffness, initial impact velocity, moment law, and energy consumption of valve plate are compiled with the Visual Basic software. It is convenient to develop the computer aided design and solve practical engineering problems.