Volume ratio control system for a compressor

A heating, ventilation, air conditioning, and/or refrigeration (HVAC&R) system, comprising:

• a compressor configured to circulate a refrigerant through a refrigerant circuit;
• and
• a volume ratio control system configured to adjust a volume ratio of the compressor, wherein the volume ratio control system comprises:
• a chamber formed in a housing of the compressor, wherein a portion of the chamber is in fluid communication with a high pressure side of the compressor;
• a piston disposed within the chamber, wherein the piston comprises a cavity in fluid communication with a low pressure side of the compressor, and wherein the portion of the chamber and the cavity are fluidly separate from one another;
• and
• a biasing device disposed within the cavity, wherein the biasing device is configured to enable movement of the piston in response to a pressure differential between the low pressure side of the compressor and the high pressure side of the compressor falling below a threshold value wherein the threshold value is a variable threshold value.

A volume ratio control system for a compressor, comprising:

• a chamber formed within a housing of the compressor, wherein the chamber comprises a first portion in fluid communication with a high pressure side of the compressor and a second portion in fluid communication with a low pressure side of the compressor;
• a rod extending through an opening of the housing separating the first portion and the second portion of the chamber, wherein the rod is fixed within the chamber with respect to an axis defining a length of the chamber;
• a piston disposed within the first portion of the chamber, wherein the piston comprises a cavity in fluid communication with the second portion of the chamber, and wherein the rod is at least partially disposed within the cavity of the piston;
• and
• a biasing device disposed within the cavity between the rod and an interior surface of the piston, wherein the biasing device is configured to enable movement of the piston within the chamber in response to a pressure differential between the low pressure side of the compressor and the high pressure side of the compressor falling below a threshold value wherein the threshold value is a variable threshold value.