An Experimental Study of the Shaft Oil Supply Mechanism of a Rotary Compressor

This paper describes the experimental study of the shaft oil feed mechanism of a rotary compressor. The oil contained in the shaft in which an oil pump is inserted is fed to the respective sliding surfaces of the subbearing section, eccentric section and main bearing section of the shaft by centrifugal force of shaft rotation. The oil feed pressure of shaft rotation is approximately 0.1 kg/cm2 . In addition, the oil slot of the main bearing acts as a viscous pump and its oil feed capacity is only a fraction of the capacity of the shaft. In a compressor, oil is forced to the respective sliding surfaces by the centrifugal oil feed pressure of the shaft. The oil slots of the subbearing section, eccentric section and main bearing section of the shaft, and the clearances between the sliding surfaces of the compression chamber act as resistance to the oil flow. If oil leakage into the compression chamber is excessively large, the amount of oil fed to other sliding surfaces will decrease. Therefore, the amount of oil leakage into the compression chamber must be considered in regard to the oil feed capacity of the shaft. INTRODUCTION A rotary compressor is characterized by its small size, light weight, low cost, high performance and high reliability and has been generally utilized for household air conditioners. The high performance and high reliability of a rotary compressor greatly depends on the oil feed performance of the shaft. If an excessively small amount of shaft oil feed is fed, it will cause insufficient oil sealing of the compression chamber and heavy metal contact. If the amount of shaft oil feed is excessively large, the discharge of oil from the compressor housing will increase and the oil level in the compressor housing will be reduced. 383 However, very few studies regarding such shaft oil feed have been carried out. The principal aims of this paper are as follows: A. To theoretical and experimentally clarify the oil feed characteristics of the shaft and main bearing under the nonload pneumatic operating condition and B. To theoretical and experimentally clarify the oil feed characteristics of the main bearing under dynamic condition of a assembled compressor FEATURES OF A ROTARY COMPRESSOR Structure In a hermetic rotary compressor, the motor drive unit is located at the top of the shell and the compression mechanism unit is located on the bottom of the shell. These two units are fixed directly to the shell and the respective rotary portions of each are connected together by the shaft. The lubricating oil charged in the bottom of the shell flows in the shaft lower end and is fed through the oil path to the sliding surfaces and sealing portions of the compression mechanism. A roller is mounted on the eccentric section of the shaft and rotates at the center of the cylinder. A suction pipe is directly inserted into the suction cham~er, and compressed gas at high-temperature and high-pressure is discharged once into the shell.