The present invention relates to a compressor provided with a housing including a compression unit, which draws in refrigerant gas, compresses the refrigerant gas, and then discharges the refrigerant gas from a discharge chamber through an outlet and out of the housing, and an oil separation structure, which is arranged between the discharge chamber and the outlet to separate lubrication oil from the refrigerant gas.
A typical compressor for a vehicle air conditioner uses lubrication oil, which is suspended in a refrigerant gas, to lubricate parts such as a compression mechanism when the refrigerant gas circulates through the housing of the compressor. Thus, such a compressor includes an oil separation mechanism, which is arranged in a discharge line, to confine the lubrication oil to the compressor and prevent the lubrication oil from escaping into an external refrigerant circuit together with the refrigerant gas. Japanese Laid-Open Patent Publication No. 2005-320873 describes an example of a whirling type oil separation structure. Referring to FIG. 9A, in Japanese Laid-Open Patent Publication No. 2005-320873, an oil separator 80 is arranged in a compression casing 81 between a discharge chamber 82 and an outlet 83. The oil separator 80 includes a separation compartment 84 and a separation tube 85. The separation tube 85 is press-fitted into and fixed to the separation compartment 84. An annular void is formed between the wall surface of the separation compartment 84 and the outer surface of the separation tube 85. An oil passage 87, which is in communication with an oil reservoir 86, is formed below the separation compartment 84.
The refrigerant gas in the discharge chamber 82 enters the separation compartment 84 of the oil separator 80. The refrigerant gas then whirls around the outer surface of the separation tube 85 as it descends in the separation compartment 84. This applies centrifugal force to the refrigerant and separates lubrication oil from the refrigerant gas. The lubrication oil collects on the wall surface of the separation compartment 84. Then, the refrigerant gas flows through the separation tube 85 and is discharged out of the outlet 83.
Japanese Laid-Open Patent Publication No. 2009-235910 describes an example of an impingement type oil separation structure. Referring to FIG. 9B, a gas compressor 90 described in Japanese Laid-Open Patent Publication No. 2009-235910 includes a casing 91 that accommodates a compression mechanism (not shown) and a baffling passage 92, through which compressed refrigerant gas flows. The baffling passage 92 is formed by staggering a series of fin-shaped baffles 94 between the casing 91 and an opposing portion of a rear block 93. An oil reservoir (not shown) that accumulates separated lubrication oil is arranged between the casing 91 and the rear block 93.
When refrigerant gas flows through the baffling passage 92, the refrigerant gas repetitively impinges against bent portions 95 formed between the baffles 94. The difference in specific gravity separates lubrication oil from the refrigerant gas. The refrigerant gas is discharged out of the gas compressor 90, whereas the lubrication oil is accumulated in the oil reservoir.
In the whirling type oil separation structure such as the oil separator 80 of Japanese Laid-Open Patent Publication No. 2005-320873 that uses a separation tube 85, the separation tube 85 should have a particular length and diameter to whirl the refrigerant gas about the separation tube 85 in a preferable manner and obtain the required performance for separating lubrication oil. Thus, there is a tendency for the oil separation structure to be large, and the freedom of layout is thereby limited.
In the impingement type oil separation structure such as that of Japanese Laid-Open Patent Publication No. 2009-235910 that uses the baffling passage 92, the baffling passage 92 should have a particular length and a particular number of bent portions 95 to induce refrigerant gas impingement against the bent portions 95 a desired number of times. Thus, the oil separation structure tends to be large. Further, as the lubrication oil separated from the baffling passage 92 meanders through the baffling passage 92, the lubrication oil may fill the baffling passage 92. In this case, the lubrication oil may flow backward to the compression mechanism, and the lubrication oil may be carried by the refrigerant gas to the external refrigerant circuit.