Prediction of the Valve Stresses of Rotary Compressor Using the Finite Element Method

In this study we analyzed both bending and impact stress of the discharge valve of the rotary compressor using a commercial FEM program MSC/NASTRAN and predicted the amount of maximum stress and the location it occurred. We measured the maximum stress of the valve in bolt case compressor using the resistance type strain gages. Good agreement was made by the comparison between the numerical analysis and exP€rlment To judge the reliability of the discharge valve, the comparison between the maximum stress and the fatigue strength of the valve materials was accomplished. Also using the numerical analysis , we can reduce the time for the design of the valve and estimate the service life of it . INTRODUCUTION Recently the technology of the compressor has rapidly advanced for the home appliances like refrigerator and air conditioner. Especially rolling piston type rotary compressors are more widely used than reciprocating compressor. The advantages of the rolling piston type rotary compressor are higher efficiency, compact size, and light weight etc. The behavior of the discharge valve of the rotary compressor has effect on performance of it. Also the valve is subjected to the fluctuating bending and impact load about 60 cycles per second. Therefore we have to design the discharge valve in considering both the performance and the service life of the compressor. To prevent the break of the discharge valve and improve the reliability of the compressor we should find the highest stress of the valve during operation and the location of it. In order to reduce the time for design of the valve we predict the stress using the numerical methcx:l and we prove the accuracy of the numerical stress analysis by experiment. We compare the maximum stress of the valve with the fatigue strength of the valve material to assess the reliability of the valve. ANALYSIS 1. The behavior of the discharge valve Three states of discharge valve stress are considered in the present study to analyze the stress of the valve, shown in Fig.1. Fig.l(a) shows the valve which is contact to the backer. In this case the valve is subjected to the bending stress and impact stress. In Fig.l(b) the valve is contact to the valve seat after the refrigerent gas is discharged through the discharge port of the compressor. The valve comes to this position by the spring back of the valve itself. Fig.l(c) shows the valve is subjected to the inflexural force. This force is the results of the difference of the pressure between muffler and cylinder of the compressor. Fig. 2 shows the shape of the discharge valve. 1. Senior Research Engineer, Corporate Technical Operations, Samsung Electronics Co., KOREA 2. Research Engineer, Corporate Technical Operations, Sarnsung Electronics Co., KOREA