Scroll type compressor with variable displacement mechanism

Abstract

A variable displacement type compressor is disclosed. The compressor includes a housing having fluid inlet and fluid outlet ports. A fixed scroll is fixed within the housing and has a circular end plate from which a first spiral element extends. The end plate of the fixed scroll partitions the inner chamber of the compressor housing into a front chamber connected to the fluid inlet port and a rear chamber. The rear chamber is divided into a discharge chamber connected to the fluid outlet port and an intermediate pressure chamber. The end plate of the fixed scroll has at least two holes which connect the fluid pockets to the intermediate pressure chamber. The end plate also has a communicating channel which connects the front chamber to the intermediate chamber. A control device controls the communication between the front chamber and intermediate pressure chamber. The control device is disposed on the intermediate pressure chamber, and a valve element of the control means is operated by pressure from the discharge chamber.

We claim: 
     
       1. In a scroll type compressor including a housing having an inlet port and an outlet port, a fixed scroll fixedly disposed within said housing and having a circular end plate from which a first spiral element extends into the interior of said housing, an orbiting scroll having a circular end plate from which a second spiral element extends, said first and second spiral elements interfitting at an angular and radial offset to make a plurality of line contacts and define at least one pair of fluid pockets within the interior of said housing, a driving mechanism operatively connected to said orbiting scroll to effect the orbital motion of said orbiting scroll, a rotation preventing mechanism for preventing the rotation of said orbiting scroll during the orbital motion, said circular end plate of said fixed scroll dividing the interior of said housing into a front chamber and a rear chamber, said front chamber communicating with said inlet port, and said rear chamber being divided into a discharge chamber which communicates between said outlet port and a central fluid pocket formed by both said scrolls and an intermediate pressure chamber, the improvement comprising: at least one pair of holes formed through said circular end plate of said fixed scroll forming a fluid channel between the fluid pockets and said intermediate pressure chamber, a communication channel formed through said circular end plate of said fixed scroll to form a fluid channel between said intermediate pressure chamber and said front chamber, control means disposed on a portion of said intermediate pressure chamber for controlling fluid communication between said intermediate pressure chamber and said front chamber, said control means comprising a .[.valve element operated by the compressed fluid in said discharge chamber, and a.]. cylinder .Iadd.connected with said intermediate pressure chamber, said front chamber and said discharge chamber.Iaddend., a piston slidably disposed within said cylinder .Iadd.and operated by the compressed fluid from said discharge chamber.Iaddend., and a control valve element.[., a top portion of said cylinder being connected to said discharge chamber, said control valve element.]. controlling the communication between said discharge chamber and said front chamber.   
     
     
       2. A scroll type compressor according to claim 1 wherein said .Iadd.control .Iaddend.valve element is disposed in said piston. .Iadd.3. A scroll type compressor according to claim 1 wherein said control valve element comprises a bellows and a valve operated by said bellows, said piston including a first opening facing a portion of said cylinder in communication with said discharge chamber and a second opening facing a portion of said cylinder in communication with said front chamber, said bellows being located within said piston and being responsive to the pressure in said front chamber to operate said valve to open and close said first opening to thereby control communication between said discharge chamber and said front chamber. .Iaddend. .Iadd.4. A scroll type compressor according to claim 3 wherein a lower portion of said cylinder communicates with said intermediate pressure chamber and said front chamber, communication between said intermediate pressure chamber and said front chamber being controlled by the sliding operation of said piston, a top portion of said cylinder being connected with said discharge chamber. 
     
     
        .Iaddend. .Iadd.5.  A scroll type compressor according to claim 4 wherein the top portion of said cylinder and said discharge chamber are connected through a fluid channel including a constricted conduit disposed in a 
     
     
        portion thereof. .Iaddend. .Iadd.6.  A scroll type compressor according to claim 1 wherein a lower portion of said cylinder communicates with said intermediate pressure chamber and said front chamber, communication between said intermediate pressure chamber and said front chamber being controlled by the sliding operation of said piston, a top portion of said cylinder being connected with said discharge chamber. .Iaddend. .Iadd.7. A scroll type compressor according to claim 6 wherein said control valve element controls the sliding operation of said piston in response to the pressure in said front chamber to thereby control communication between said intermediate pressure chamber and said front chamber to vary the 
     
     
        compression ratio of said compressor. .Iaddend. .Iadd.8.  A scroll type compressor according to claim 7 wherein, in the event the pressure in said front chamber is less than a predetermined pressure, said control valve element opens communication between said discharge chamber and said front chamber and said piston slides upward in said cylinder to open communication between said intermediate pressure chamber and said front chamber to thereby decrease the compression ratio. .Iaddend. .Iadd.9. A scroll type compressor according to claim 8 wherein, in the event the pressure in said front chamber is greater than the predetermined pressure, said control valve element closes off communication between said discharge chamber and said front chamber and said piston slides downward in response to the pressure from said discharge chamber to close off communication between said intermediate pressure chamber and said front chamber to 
     
     
        thereby increase the compression ratio. .Iaddend. .Iadd.10.  In a scroll type compressor including a housing having an inlet port and an outlet port, a fixed scroll fixedly disposed within said housing and having a circular end plate from which a first spiral element extends into the interior of said housing, an orbiting scroll having a circular end plate from which a second spiral element extends, said first and second spiral elements interfitting at an angular and radial offset to make a plurality of line contacts and define at least one pair of fluid pockets within the interior of said housing, a driving mechanism operatively connected to said orbiting scroll to effect the orbital motion of said orbiting scroll, a rotation preventing mechanism for preventing the rotation of said orbiting scroll during the orbital motion, said circular end plate of said fixed scroll dividing the interior of said housing into a front chamber and a rear chamber, said front chamber communicating with said inlet port, and said rear chamber being divided into a discharge chamber which communicates between said outlet port and a central fluid pocket formed by both said scrolls and an intermediate pressure chamber, the improvement comprising: at least one pair of holes formed through said circular end plate of said fixed scroll forming a fluid channel between the fluid pockets and said intermediate pressure chamber, a communication chamber formed by a further division of said rear chamber, a communicating channel formed through said circular end plate of said fixed scroll forming a fluid channel between said front chamber and said communication chamber, a first opening formed through a wall of said communication chamber forming a fluid channel between said communication chamber and said intermediate pressure chamber and thereby forming a continuous fluid channel between said front chamber and said intermediate pressure chamber, control means disposed on a portion of said intermediate pressure chamber for controlling fluid communication between said intermediate pressure chamber and said front chamber, said control means comprising a cylinder including a top portion connected to said discharge chamber by a conduit for communicating fluid therebetween, a side portion connected to said wall of said communication chamber with said first opening formed therethrough for communicating fluid therebetween, and a bottom portion connected with said intermediate pressure chamber, a piston slidably disposed within said cylinder and operated by the compressed fluid from said discharge chamber, and a control valve element controlling the communication between said discharge chamber and said front chamber and operated by the compressed fluid from said communication chamber. .Iaddend. .Iadd.11. A scroll type compressor according to claim 10 wherein said control valve element is disposed in   
     
     
        said piston. .Iaddend. .Iadd.12.  In a scroll type compressor including a housing having an inlet port and an outlet port, a fixed scroll fixedly disposed within said housing and having a circular end plate from which a first spiral element extends into the interior of said housing, an orbiting scroll having a circular end plate from which a second spiral element extends, said first and second spiral elements interfitting at an angular and radial offset to make a plurality of line contacts and define at least one pair of fluid pockets within the interior of said housing, a driving mechanism operatively connected to said orbiting scroll to effect the orbital motion of said orbiting scroll, a rotation preventing mechanism for preventing the rotation of said orbiting scroll during the orbital motion, said circular end plate of said fixed scroll dividing the interior of said housing into a front chamber and a rear chamber, said front chamber communicating with said inlet port, and said rear chamber being divided into a discharge chamber which communicates between said outlet port and a central fluid pocket formed by both said scrolls and an intermediate pressure chamber, the improvement comprising: at least one pair of holes formed through said circular end plate of said fixed scroll forming a fluid channel between the fluid pockets and said intermediate pressure chamber, a communication chamber formed by a further division of said rear chamber, a communicating channel formed through said circular end plate of said fixed scroll forming a fluid channel between said front chamber and said communication chamber, first control means disposed on a portion of said intermediate pressure chamber for controlling fluid communication between said communication chamber and said intermediate pressure chamber, conduit means connected between said first control means and said discharge chamber for communicating fluid therebetween, said first control means operated by the compressed fluid from said discharge chamber, second control means associated with said first control means for controlling fluid communication between said discharge chamber and said communication chamber, said second control means operated by changes of the fluid pressure in said communication chamber. .Iaddend. .Iadd.13. A scroll type compressor according to claim 12 wherein said first control means comprises a cylinder connected with said intermediate pressure chamber, said communication chamber and said conduit means, and a piston slidably disposed within said cylinder.   
     
     
        .Iaddend. .Iadd.14.  A scroll type compressor according to claim 12 wherein said conduit means comprises a fluid channel including a 
     
     
        constricted conduit disposed in a portion thereof. .Iaddend. .Iadd.15.  A scroll type compressor according to claim 13 wherein said second control means comprises a control valve element disposed in said piston. .Iaddend. .Iadd.16. A scroll type compressor according to claim 15 wherein said control valve element comprises a bellows and a valve operated by said bellows, said piston including a first opening facing a portion of said cylinder in communication with said conduit means and a second opening facing a portion of said cylinder in communication with said communication chamber, said bellows being responsive to the pressure in said communication chamber to operate said valve to open and close said first opening and thereby control communication between said discharge chamber and said front chamber. .Iaddend. .Iadd.17. A scroll type compressor according to claim 16 wherein a lower portion of said cylinder communicates with said intermediate pressure chamber and said communication chamber, communication between said intermediate pressure chamber and said communication chamber being controlled by the sliding operation of said piston, a top portion of said cylinder being connected with said conduit means. .Iaddend. .Iadd.18. A scroll type compressor according to claim 17 wherein said control valve element controls the sliding operation of said piston in response to the pressure in said communication chamber to thereby control communication between said intermediate pressure chamber and said communication chamber to vary the compression ratio of said compressor. .Iaddend. .Iadd.19. A scroll type compressor according to claim 18 wherein, in the event the pressure in said communication chamber is less than a predetermined pressure, said control valve element opens communication between said communication chamber and said discharge chamber through said conduit means and said piston slides upward in said cylinder to open communication between said intermediate pressure chamber and said communication chamber to thereby decrease the compression ratio. .Iaddend. .Iadd.20. A scroll type compressor according to claim 19 wherein, in the event the pressure in said communication chamber is greater than the predetermined pressure, said control valve element closes off communication between said conduit means and said communication chamber and said piston slides downward in response to the pressure from said conduit means to close off communication between said intermediate pressure chamber and said communication chamber to thereby increase the compression ratio. .Iaddend.