# US 12,000,398 B2 · Volume ratio control system for a compressor > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 12,000,398 B2 - Document ID: US12000398B2 - Status: Granted - Kind: B2 - Application number: 17/791,180 - Filed: 2021-01-07 - Published: 2023-02-02 - Granted: 2024-06-04 - Earliest claimed: 2020-01-07 - Assignees: Tyco Fire & Security GmbH - Applicants: Johnson Controls Tyco IP Holdings LLP - Inventors: Paul Nemit, Jr.; Angela Marie Comstock; Franklin Aaron Montejo - Web page: https://patentgrep.com/patent/US12000398B2 ## CPC - F04C 18/16: with helical teeth, e.g. chevron-shaped, screw type {(for non-parallel axes of movement F04C18/48)} - F04C 28/12: using sliding valves - F25B 41/39: Dispositions with two or more expansion means arranged in series, i.e. multi-stage expansion, on a refrigerant line leading to the same evaporator - F25B 2339/047: Water-cooled condensers - F25B 2400/13: Economisers - F25B 2600/0253: with variable speed - F04C: ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS (engines F03C); ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT PUMPS - F25B: REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS ## Abstract A volume ratio control system for a compressor includes a chamber formed within a housing of the compressor, a piston disposed within the chamber, where the piston is configured to separate the chamber into at least a first portion fluidly coupled to a low pressure side of the compressor and a second portion fluidly coupled to a high pressure side of the compressor, and a biasing device disposed within the chamber, where the biasing device is configured to adjust a position 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. ## Claims ### Claim 1 A volume ratio control system for a compressor, comprising: a chamber formed within a housing of the compressor; a piston disposed within the chamber, wherein the piston is configured to fluidly separate the chamber into at least a first portion fluidly coupled to a low pressure side of the compressor and a second portion fluidly coupled to a high pressure side of the compressor; and a biasing device configured to adjust a position 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. ### Claim 2 (depends on 1) The volume ratio control system of claim 1, wherein the low pressure side is a suction side of the compressor, and the high pressure side is a discharge side of the compressor. ### Claim 3 (depends on 1) The volume ratio control system of claim 1, wherein the biasing device is disposed within a cavity. ### Claim 4 (depends on 1) The volume ratio control system of claim 1, wherein the chamber comprises one or more openings formed in the housing, wherein the one or more openings are fluidly coupled to a compression chamber of the compressor. ### Claim 5 (depends on 4) The volume ratio control system of claim 4, wherein the biasing device is configured to adjust the position of the piston to expose at least an opening of the one or more openings in response to the pressure differential between the low pressure side of the compressor and the high pressure side of the compressor falling below the threshold value. ### Claim 6 (depends on 1) The volume ratio control system of claim 1, wherein the threshold value is a variable threshold value dependent on an amount of compression of the biasing device. ### Claim 7 (depends on 1) The volume ratio control system of claim 1, wherein the piston comprises a first segment having a first diameter and a second segment having a second diameter, wherein the first diameter is less than the second diameter. ### Claim 8 (depends on 1) The volume ratio control system of claim 1, wherein the piston is configured to separate the chamber into the first portion, the second portion, and a bypass portion, and the piston is configured to fluidly separate the first portion from the bypass portion. ### Claim 9 (depends on 8) The volume ratio control system of claim 8, wherein the bypass portion is fluidly coupled to the high pressure side of the compressor. ### Claim 10 (depends on 8) The volume ratio control system of claim 8, wherein the bypass portion is fluidly coupled to the second portion via a passage extending through the piston. ### Claim 11 (depends on 8) The volume ratio control system of claim 8, wherein the second portion is fluidly coupled to the high pressure side of the compressor and to a lubricant line of the compressor. ### Claim 12 (depends on 11) The volume ratio control system of claim 11, wherein the lubricant line is configured to supply a lubricant to the second portion of the chamber at a pressure substantially equal to a discharge pressure of the compressor. ### Claim 13 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; a piston disposed within the chamber, wherein the piston fluidly separates the chamber into at least a first portion fluidly coupled to a low pressure side of the compressor and a second portion fluidly coupled to a high pressure side of the compressor; and a biasing device disposed within the chamber, 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. ### Claim 14 (depends on 13) The HVAC&R system of claim 13, wherein the chamber is formed within a housing of the compressor. ### Claim 15 (depends on 14) The HVAC&R system of claim 14, wherein the chamber comprises one or more openings formed in the housing and fluidly coupled to a compression chamber of the compressor. ### Claim 16 (depends on 15) The HVAC&R system of claim 15, wherein the biasing device is configured to enable movement of the piston in a first direction to expose at least an opening of the one or more openings in response to the pressure differential between the low pressure side of the compressor and the high pressure side of the compressor falling below the threshold value. ### Claim 17 (depends on 16) The HVAC&R system of claim 16, wherein the biasing device is configured to enable movement of the piston in a second direction, opposite the first direction, in response to the pressure differential exceeding the threshold value. ### Claim 18 (depends on 13) The HVAC&R system of claim 13, wherein the compressor is a screw compressor. ### Claim 19 (depends on 13) The HVAC&R system of claim 13, wherein the volume ratio control system is configured to passively adjust the volume ratio of the compressor based on the pressure differential between the low pressure side of the compressor and the high pressure side of the compressor and based on the biasing device. ### Claim 20 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, a second portion, and a bypass portion, the first portion is fluidly coupled to a low pressure side of the compressor, the bypass portion is fluidly coupled to a high pressure side of the compressor, and the second portion fluidly coupled to the bypass portion and/or to a lubricant line; a piston disposed within the chamber, wherein the piston fluidly separates the first portion of the chamber from the second portion of the chamber; and a biasing device disposed within the chamber, wherein the biasing device is configured to direct 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. ### Claim 21 (depends on 20) The volume ratio control system of claim 20, wherein the piston comprises a first segment having a first diameter and a second segment having a second diameter, wherein the first segment is coupled to the biasing device, and wherein the first diameter is less than the second diameter. ### Claim 22 (depends on 21) The volume ratio control system of claim 21, wherein the first segment of the piston is disposed in at least the first portion of the chamber, and wherein the second segment of the piston is disposed in at least the second portion of the chamber. ### Claim 23 (depends on 22) The volume ratio control system of claim 22, wherein the second segment of the piston comprises a first surface facing the second portion of the chamber and a second surface facing the bypass portion of the chamber, and wherein the first segment of the piston extends from the second surface of the second segment.