Patent ID: 6872050

Claim:
A diffuser system for a variable capacity centrifugal compressor for compressing a fluid, the compressor having a housing and an impeller, the impeller being rotatably mounted in the housing, the system comprising: a nozzle base plate connected to the housing adjacent the impeller, the nozzle base plate having an elongated surface that cooperates with an opposed interior surface on the housing to define a diffuser gap, the elongated surface of the nozzle base plate having a groove adjacent the diffuser gap; a plurality of support blocks mounted to a back side of the nozzle base plate opposite the diffuser gap; a drive ring rotatably mounted to the support blocks and movable between a first position and a second position, the drive ring including a plurality of cam tracks positioned on a circumference of the drive ring, at least two of the plurality of cam tracks aligned with at least two of the plurality of support blocks; an actuating means attached to the drive ring and movable between a first axial position and a second axial position to move the drive ring between the first position and the second position; a plurality of drive pins, each drive pin extending through a corresponding support block and the nozzle base plate, each drive pin having a first end and a second end opposite the first end, the first end of the drive pin including a cam follower mounted into a cam track on the drive ring and the second end of the drive pin extending through the nozzle base plate into the groove on the surface of the nozzle base plate; a diffuser ring mounted on the second end of each of the plurality of drive pins, the drive pins extending into the groove on the nozzle base plate surface; wherein the rotational movement of the drive ring between a first position and a second position moves the cam followers in the cam track which axially moves the drive pins, the axial movement of the drive pins moves the diffuser ring between a retracted position in which the diffuser ring resides in the groove on the nozzle base plate and an extended position in which the diffuser ring substantially closes the diffuser gap to reduce fluid flow through the diffuser gap.