# US 10,481,043 B2 · Method for small leak testing of an evaporative emissions system > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,481,043 B2 - Document ID: US10481043B2 - Status: Granted - Kind: B2 - Application number: 15/702,397 - Filed: 2017-09-12 - Published: 2019-03-14 - Granted: 2019-11-19 - Earliest claimed: 2017-09-12 - Assignees: GM Global Technology Operations LLC - Applicants: GM Global Technology Operations LLC - Inventors: Todd W Nelson - Web page: https://patentgrep.com/patent/US10481043B2 ## CPC - G01M 3/025: {Details with respect to the testing of engines or engine parts} - G01M 15/042: {by monitoring a single specific parameter not covered by groups G01M15/06 - G01M15/12} - G01M 3/26: by measuring rate of loss or gain of fluid, e.g. by pressure-responsive devices, by flow detectors - G01M 3/3272: {for verifying the internal pressure of closed containers} - G01M: TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR ## Abstract A method for small leak testing of an evaporative emissions system includes monitoring a vacuum pressure level of the evaporation emissions system with the engine on and actuating a canister vent valve to regulate the vacuum pressure level to a predetermined minimum vacuum pressure level. Upon turning the engine off, the canister vent valve and a canister purge valve are closed to seal the evaporative emissions system. Next, the vacuum pressure level is recorded over a predetermined time period after turning off the engine and a fault code is set when the vacuum pressure level becomes less than the predetermined minimum vacuum pressure level. ## Claims ### Claim 1 A method for small leak testing of an evaporative emissions system of an engine, the method comprising: monitoring a vacuum pressure level of the evaporation emissions system with the engine on; opening a canister purge valve and activating a pump, both of which are within the evaporative emissions system, to provide a vacuum pressure level; actuating a canister vent valve within the evaporative emissions system to regulate the vacuum pressure level to a predetermined minimum vacuum pressure level; closing the canister vent valve and the canister purge valve when the engine is turned off; deactivating the pump; recording the vacuum pressure level over a predetermined time period after the engine is turned off and the pump is deactivated; and setting a fault code when the vacuum pressure level becomes less than the predetermined minimum vacuum pressure level. ### Claim 2 (depends on 1) The method of claim 1 wherein monitoring further comprises monitoring the vacuum pressure level at a fuel tank within the evaporative emissions system using a pressure sensor. ### Claim 3 (depends on 1) The method of claim 1 wherein monitoring further comprises monitoring the vacuum pressure level at an evaporative emissions vapor canister within the evaporative emissions system using a pressure sensor. ### Claim 4 (depends on 1) The method of claim 1 wherein actuating further comprises opening and closing the canister vent valve with a variable pulse width modulated signal to regulate the vacuum pressure level. ### Claim 5 (depends on 1) The method of claim 1 wherein actuating further comprises actuating the canister vent valve between a fully open and a fully closed position to regulate the vacuum pressure level. ### Claim 6 (depends on 1) The method of claim 1 further comprises controlling duty cycle of a signal applied to the canister purge valve to regulate the vacuum pressure level when the canister vent valve is restricted. ### Claim 7 (depends on 1) The method of claim 1 wherein actuating further comprises actuating a purge pump to affect regulation of the vacuum pressure level. ### Claim 8 (depends on 1) The method of claim 1 wherein setting further comprises activating a malfunction indicator lamp when the vacuum pressure level becomes less than the predetermined minimum vacuum pressure level. ### Claim 9 A method for small leak testing of an evaporative emissions system of an engine, the method comprising: monitoring a vacuum pressure level of the evaporation emissions system with the engine on; opening a canister purge valve and activating a pump, both of which are within the evaporative emissions system, to provide the vacuum pressure level; actuating a canister vent valve within the evaporative emissions system with a variable pulse width modulated signal to regulate the vacuum pressure level to a predetermined minimum vacuum pressure level; closing the canister vent valve and the canister purge valve when the engine is turned off; deactivating the pump; recording the vacuum pressure level over a predetermined time period after the engine is turned off and the pump is deactivated; and setting a fault code when the vacuum pressure level becomes less than the predetermined minimum vacuum pressure level. ### Claim 10 (depends on 9) The method of claim 9 wherein monitoring further comprises monitoring the vacuum pressure level at a fuel tank within the evaporative emissions system using a pressure sensor. ### Claim 11 (depends on 9) The method of claim 9 wherein monitoring further comprises monitoring the vacuum pressure level at an evaporative emissions vapor canister within the evaporative emissions system using a pressure sensor. ### Claim 12 (depends on 9) The method of claim 9 wherein actuating further comprises actuating the canister vent valve between a fully open and a fully closed position to regulate the vacuum pressure level. ### Claim 13 (depends on 9) The method of claim 9 further comprises controlling duty cycle of a signal applied to the canister purge valve to regulate the vacuum pressure level when the canister vent valve is restricted. ### Claim 14 (depends on 9) The method of claim 9 wherein actuating further comprises actuating a purge pump to affect regulation of the vacuum pressure level. ### Claim 15 (depends on 9) The method of claim 9 wherein setting further comprises activating a malfunction indicator lamp when the vacuum pressure level becomes less than the predetermined minimum vacuum pressure level.