Experimental investigation on the characteristics of variable displacement swash plate compressor

This paper is on a new device developed to measure the piston stroke length (PSL) of the variable displacement swash plate compressor (VDSC), with which the test bench for the VDSC and test system for automotive air conditioner with VDSC is constructed. The volumetric efficiency, PSL and displacement control, and transient behavior along with air conditioning load or compressor rotary speed are investigated experimentally. The experiment results show that the volumetric efficiency of the VDSC is directly proportional to the PSL due to the constant absolute clearance at different piston stroke lengths. When the air conditioning load keep constant, the PSL and displacement of the VDSC are regulated to meet the air conditioning load at different compressor rotary speeds or vehicle speeds. When the air conditioning load changes gradually, the PSL has a number of small step changes so that the refrigerating capacity of the VDSC can well fit the air conditioning load. When the compressor rotary speed changes abruptly, the piston stroke length, refrigerant mass flow rate, and other parameters change with a very short time delay to ensure a nearly constant refrigerating capacity of compressor.