# US 8,770,014 B2 · System for detecting hydraulic fluid leaks > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,770,014 B2 - Document ID: US8770014B2 - Status: Granted - Kind: B2 - Application number: 11/685,718 - Filed: 2007-03-13 - Published: 2008-09-18 - Granted: 2014-07-08 - Earliest claimed: 2007-03-13 - Assignees: GM Global Technology Operations LLC - Applicants: Mike M. McDonald; William C. Albertson - Inventors: Mike M. McDonald; William C. Albertson - Web page: https://patentgrep.com/patent/US8770014B2 ## CPC - G01M 3/2876: {for valves (G01M3/30 takes precedence)} - G01M 3/2815: {using pressure measurements} - G01M: TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR ## Abstract A control system and method for detecting a hydraulic system leak in an engine includes a pressure sensor that senses a first pressure reading of a hydraulic fluid supply at a first time and a second pressure reading of said hydraulic fluid supply at a second time. A comparison module calculates a pressure ratio based on the first and second pressure readings and signals a fault condition based on a relationship between the pressure ratio and a pressure threshold. ## Claims ### Claim 1 A control system for detecting a hydraulic system leak in a vehicle powertrain, comprising: a filtering module that outputs filtered pressure values by filtering a pressure signal output by a pressure sensor to remove high frequency content from said pressure signal, wherein said pressure sensor senses pressures of a fluid within a gallery of a hydraulic system of said vehicle powertrain; a pressure reading module that determines a first pressure reading based on a first one of said filtered pressure value output before a valve of said hydraulic system is actuated and that determines a second pressure reading based on a second one of said filtered pressure values output after said valve is actuated; and a comparison module that calculates a pressure ratio of said first and second pressure readings and that signals a fault condition indicative of said hydraulic system leak based on a relationship between said pressure ratio and a pressure threshold, wherein said valve controls an active fuel management event of an engine of said vehicle powertrain, said active fuel management event includes deactivating a set of cylinders of said engine, and said first one of said filtered pressure values is output before said active fuel management event and said second one of said filtered pressure values is output after said active fuel management event. ### Claim 2 (depends on 1) The control system of claim 1 wherein said pressure ratio is said second pressure reading divided by said first pressure reading and wherein said comparison module signals said fault condition when said pressure ratio falls below said pressure threshold. ### Claim 3 (depends on 1) The control system of claim 1 wherein said comparison module stores said fault condition as a fault code. ### Claim 4 (depends on 1) The control system of claim 1 wherein said pressures are sensed upstream of said valve. ### Claim 5 A method for detecting a hydraulic system leak in a vehicle powertrain, comprising: outputting filtered pressure values by filtering a pressure signal output by a pressure sensor to remove high frequency content from said pressure signal, wherein said pressure sensor senses pressures of a fluid within a gallery of a hydraulic system of said vehicle powertrain; determining a first pressure reading based on a first one of said filtered pressure values output before a valve of said hydraulic system is actuated; determining a second pressure reading based on a second one of said filtered pressure values output after said valve is actuated; and calculating a pressure ratio of said first and second pressure readings and signaling a fault condition indicative of said hydraulic system leak based on a relationship between said pressure ratio and a pressure threshold, wherein said valve controls an active fuel management event of an engine of said vehicle powertrain, said active fuel management event includes deactivating a set of cylinders of said engine, and said first one of said filtered pressure values is output before said active fuel management event and said second one of said filtered pressure values is output after said active fuel management event. ### Claim 6 (depends on 5) The method of claim 5 further comprising signaling said fault condition when said pressure ratio falls below said pressure threshold, wherein said pressure ratio is said second pressure reading divided by said first pressure reading. ### Claim 7 (depends on 5) The method of claim 5 wherein said fault condition is stored as a fault code. ### Claim 8 (depends on 5) The method of claim 5 wherein said pressures are sensed upstream of said valve. ### Claim 9 A control system for detecting a hydraulic system leak in a vehicle powertrain, comprising: a pressure sensor that senses pressures of a fluid within a gallery of a hydraulic system of said vehicle powertrain and outputs a pressure signal based on said pressures; a filtering module that outputs filtered pressure values by filtering said pressure signal to remove high frequency content from said pressure signal; a pressure reading module that determines a first pressure reading based on a first one of said filtered pressure values output before a valve of said hydraulic system is actuated and a second pressure reading based on a second one of said filtered pressure values output after said valve is actuated; and a comparison module that calculates a pressure ratio of said first and second pressure readings and that signals a fault condition of said hydraulic system leak based on a relationship between said pressure ratio and a pressure threshold, wherein said valve controls an active fuel management event of an engine of said vehicle powertrain, said active fuel management event includes deactivating a set of cylinders of said engine, and said first one of said filtered pressure values is output before said active fuel management event and said second one of said filtered pressure values is output after said active fuel management event. ### Claim 10 (depends on 9) The control system of claim 9 wherein said pressure ratio is said second pressure reading divided by said first pressure reading and wherein said comparison module signals said fault condition when said pressure ratio falls below said pressure threshold. ### Claim 11 (depends on 9) The control system of claim 9 wherein said pressures are sensed upstream of said valve.