In today's air-conditioner, the rolling piston type rotary compressors are widely used. Induction motors are generally used to drive these types of compressors. Therefore, the maximum operating speed is about the same as the electric source frequency (example, 50Hz or 60Hz). We are now able to vary the rotational speed of the rolling piston type rotary compressor with the aid of an inverter control that controls the power source frequency instead of using an on - off control. The purpose of this is to increase heat pump capacity during high speed operation when the load is large and decrease heat pump capacity during low speed operation when load is small. The rolling piston type rotary compressors, which have a rather large degree of eccentric mass at the roller and the eccentric section of the shaft, would have problems such as the distortion of the shaft and its support system at high speed operation and would cause too much bearing load. We are going to discuss the problems of bearing loads of compressors during high speed operation. Countermeasures for reducing compressor bearing loads during high speed operation are as follows; (1) Reduction of eccentric mass (2) Reduction of balancer weight of rotor (3) Increase shaft rigidity (4) Reduction of rotor stack hight (5) Reduction of discharge pressure.
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