Generally, an automobile air-conditioner accommodating a refrigerant compressor uses a refrigerant gas containing therein a mist-like lubricant oil, i.e., oil fine particles. The lubricant oil is needed for lubricating the compressor. Nevertheless, when the lubricant oil is adhered to an evaporator arranged in the refrigerating circuit of the air-conditioner, the evaporator is unable to conduct an effective thermal exchange, and accordingly, the refrigerating efficiency of the air-conditioner is lowered. Further, when an increase in the amount of the lubricant oil contained in the refrigerant gas flowing in the refrigerating circuit occurs, the amount of the lubricant oil remaining inside the compressor is accordingly reduced, and therefore, the internal movable elements of the compressor suffer from a lack of lubrication. Accordingly, the adoption of a method of separating the mist-like lubricant oil from the refrigerant gas is required when the oil-containing refrigerant gas enters the compressor to be compressed therein.
One typical conventional swash plate type refrigerant compressor is provided with an internal construction such that a small hole is formed in a cylinder block of the compressor, to allow a communication between a suction passageway and a swash plate chamber and thereby permit a flow of the refrigerant gas from the swash plate chamber when a pressure of the refrigerant gas in the swash plate chamber becomes excessively high due to a bleeding of a blow-by refrigerant gas from cylinder bores into the swash plate chamber. In this compressor, a small amount of lubricant oil separated from the refrigerant gas, due to an impingement of the oil-containing refrigerant gas upon the internal wall of the suction passageway when entering the compressor from an external refrigerating circuit, is allowed to enter the swash plate chamber through the above-mentioned small hole. Nevertheless, such a small hole is unable to positively separate the lubricant oil from the lubricant oil-containing refrigerant gas, to thereby draw the lubricant oil into the swash plate chamber. This is because the small hole has different action from that of a baffle plate, and cannot function to deaden the flow inertia of the lubricant oil-containing refrigerant gas when it enters the compressor from the outside. Namely, the small hole of the typical conventional swash plate type compressor cannot function to separate the oil component from the refrigerant gas.