Tandem compressors with pulse width modulation suction valve

Abstract

A refrigerant system is provided with tandem compressors. A tandem compressor arrangement includes at least two compressors operating in parallel and having at least one common manifold. A control may operate the compressors either simultaneously, or in some predetermined sequence to provide control over refrigerant system capacity. At least one of the tandem compressors is provided with a pulse width modulation control on a suction line. In this manner, the amount of refrigerant, compressed by the compressor, can be precisely controlled to exactly meet thermal load demands in the conditioned space.

1 . A refrigerant system comprising:
 at least two compressors operating in parallel to compress refrigerant and deliver refrigerant downstream to at least one condenser, at least one expansion device positioned downstream of said at least one condenser, and at least one evaporator positioned downstream of said at least one expansion device; and   refrigerant returning from said at least one evaporator through at least one suction line to said at least two compressors, and a suction valve provided between said evaporator and at least one of said at least two compressors, said suction valve being provided with a pulse width modulation control to control the amount of refrigerant being delivered to said at least one of said at least two compressors.   
     
     
         2 . The refrigerant system as set forth in  claim 1 , wherein at least two of said at least two compressors have at least one common manifold. 
     
     
         3 . The refrigerant system as set forth in  claim 2 , wherein said at least one common manifold is a suction manifold. 
     
     
         4 . The refrigerant system as set forth in  claim 2 , wherein said at least one common manifold is a discharge manifold. 
     
     
         5 . The refrigerant system as set forth in  claim 1 , wherein at least two of said at least two compressors deliver refrigerant to a single condenser. 
     
     
         6 . The refrigerant system as set forth in  claim 1 , wherein a single expansion device receives refrigerant from at least two of said at least two compressors. 
     
     
         7 . The refrigerant system as set forth in  claim 1 , wherein a single evaporator delivers refrigerant to a suction manifold returning refrigerant to at least two of said at least two compressors. 
     
     
         8 . The refrigerant system as set forth in  claim 7 , wherein said suction valve is provided on said suction manifold, and thus regulates the flow of refrigerant to at least two of said at least two compressors. 
     
     
         9 . The refrigerant system as set forth in  claim 7 , wherein said suction valve is provided downstream of said suction manifold and on a line delivering refrigerant to at least one of said at least two compressors. 
     
     
         10 . The refrigerant system as set forth in  claim 1 , wherein there are at least two of said condensers separately receiving refrigerant from said at least two compressors. 
     
     
         11 . The refrigerant system as set forth in  claim 10 , wherein each of said at least two condensers is provided with a separate expansion device. 
     
     
         12 . The refrigerant system as set forth in  claim 1 , wherein there are at least two evaporators, and said at least two evaporators separately returning refrigerant to said at least two compressors. 
     
     
         13 . The refrigerant system as set forth in  claim 12 , wherein at least two expansion devices are provided and separately pass refrigerant to said at least two evaporators. 
     
     
         14 . The refrigerant system as set forth in  claim 1 , wherein at least one of said at least two compressors is provided with a bypass function. 
     
     
         15 . The refrigerant system as set forth in  claim 14 , wherein at least one of said at least two compressors is provided with a bypass function and said at least one compressor is associated with said suction valve. 
     
     
         16 . The refrigerant system as set forth in  claim 1 , wherein at least one of said at least two compressors is provided with an economizer cycle. 
     
     
         17 . The refrigerant system as set forth in  claim 16 , wherein at least one of said at least two compressors is provided with an economizer cycle and said at least one compressor is associated with said suction valve. 
     
     
         18 . The refrigerant system as set forth in  claim 16 , wherein more than one of said at least two compressors is provided with an economizer cycle and these economized compressors are sharing at least one of the economizer branch components. 
     
     
         19 . The refrigerant system as set forth in  claim 1 , wherein at least one of said at least two compressors is a compressor bank and said suction valve is associated with at least one compressor in the bank. 
     
     
         20 . The refrigerant system as set forth in  claim 1 , wherein at least one of said at least two compressors is selected from a set of a scroll compressor, a rotary compressor, a screw compressor, and a reciprocating compressor. 
     
     
         21 .- 39 . (canceled)