Patent ID: 8082747

Claim:
A refrigerant compressor assembly for a refrigeration circuit for controlling a temperature within a temperature controlled space, the refrigerant compressor assembly comprising: a compressor unit including: a housing; a drive member supported by the housing; an idler member supported by the housing and driven by the drive member to compress refrigerant defining a direction of increasing pressure, at least one of the housing, the drive member, and the idler member at least partially defining: a suction port; a first compression chamber disposed downstream of the suction port in the direction of increasing pressure; a second compression chamber disposed downstream of the first compression chamber in the direction of increasing pressure; a discharge port disposed downstream of the second compression chamber in the direction of increasing pressure; a first unloading valve in fluid communication with the first compression chamber; a first valve actuator coupled to the first unloading valve; a first valve control system in electrical communication with the first valve actuator, the first valve control system configured to adjust the first valve actuator via a pulse-width-modulated signal to control the first unloading valve between a closed position resisting flow from the first compression chamber through the first unloading valve and an open position allowing flow from the first compression chamber to an upstream location relative to the direction of increasing pressure; a second unloading valve in fluid communication with the second compression chamber; a second valve actuator coupled to the second unloading valve; and a second valve control system in electrical communication with the second valve actuator, the second valve control system configured to adjust the second valve actuator via a pulse-width-modulated signal to control the second unloading valve between a closed position resisting flow from the second compression chamber through the second unloading valve and an open position allowing flow from the second compression chamber to an upstream location relative to the direction of increasing pressure, wherein there is less than one pitch between the first unloading valve and the second unloading valve, and wherein there is less than one pitch between the second unloading valve and the discharge port.