Automobiles have air conditioners for reducing the temperature of air in an automobile passenger compartment. The air conditioner operates by compressing refrigerant using a compressor, reducing the temperature of the compressed refrigerant, and then expanding (uncompressing) the refrigerant to reduce the refrigerant temperature. The expanded refrigerant then flows through an evaporator used to lower the temperature of the air in the passenger compartment. Variable displacement compressors adjust a compressor's displacement to varying a compressor's refrigerant discharge flow and thereby reduce energy consumption by the compressor during certain operating conditions. Under low refrigerant flow conditions, a suction valve in the compressor can flutter and thereby create pressure pulsations that propagate into the air conditioner evaporator. These pressure pulsations may be heard inside the vehicle passenger compartment.
Some variable displacement compressors have a suction shutoff valve (SSV) to restrict or prevent suction flutter noise, sometime known as suction reed valve noise, from communication from the suction valve to the evaporator. However, a SSV providing adequate restriction at low flow conditions has undesirable flow restriction and pressure loss at high flow rates. At high flow rates it is advantageous to minimize the restriction of refrigerant flow to maximize compressor efficiency. What is needed is a SSV that has adequate restriction to prevent noise propagation out of the compressor at low refrigerant flow rates and reduced restriction at high refrigerant flow rates so that compressor efficiency is increased.
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