# US 9,518,538 B2 · Variable restriction fuel vapor canister > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 9,518,538 B2 - Document ID: US9518538B2 - Status: Granted - Kind: B2 - Application number: 13/646,487 - Filed: 2012-10-05 - Published: 2014-04-10 - Granted: 2016-12-13 - Earliest claimed: 2012-10-05 - Assignees: Ford Global Technologies, LLC - Applicants: Ford Global Technologies, LLC - Inventors: Russell Randall Pearce - Web page: https://patentgrep.com/patent/US9518538B2 ## CPC - F02M 25/0818: {having means for pressurising the evaporative emission space} - F02M 25/0854: {Details of the absorption canister} - F02M 25/089: {Layout of the fuel vapour installation} - F02M: SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF ## Abstract Systems and methods for operating an engine with a fuel vapor recovery system are disclosed. In one example approach, a method for an engine with a fuel vapor recovery system comprises increasing an amount of flow restriction between storage material in a fuel vapor canister while maintaining a vent valve open during a fuel vapor purging event. ## Claims ### Claim 1 A system for an engine with a fuel vapor recovery system, comprising: a fuel vapor canister; a restriction valve disposed in a purge flow path between storage material in the fuel vapor canister; an atmosphere vent coupled to the fuel vapor canister and a vent valve disposed therein; a purge conduit coupled to the fuel vapor canister and an intake of the engine; a sensor arranged in the purge conduit; and a controller configured to: initiate a fuel vapor purging event, including adjusting a duty-cycle of a pump in the purge conduit to provide a first amount of vacuum to the fuel vapor canister and adjusting the restriction valve to provide a first amount of flow restriction between the storage material in the fuel vapor canister; determine, based on input from the sensor, an amount of fuel vapor purged from the fuel vapor canister; if the amount of fuel vapor purged from the fuel vapor canister is less than a first threshold, adjust the duty-cycle of the pump to increase an amount of vacuum provided to the fuel vapor canister to a second, higher amount of vacuum while maintaining the first amount of flow restriction between the storage material in the fuel vapor canister; and after adjusting the duty-cycle of the pump, determine, based on input from the sensor, the amount of fuel vapor purged from the fuel vapor canister, and if the amount of fuel vapor purged from the fuel vapor canister is less than a second threshold, adjust the restriction valve to increase the amount of flow restriction between the storage material in the fuel vapor canister from the first amount to a second, higher amount while maintaining the duty-cycle of the pump to continue providing the second amount of vacuum to the fuel vapor canister. ### Claim 2 (depends on 1) The system of claim 1, wherein the controller is further configured to open the vent valve to a fixed position in response to the initiation of the fuel vapor purging event and close the vent valve following the fuel vapor purging event. ### Claim 3 (depends on 1) The system of claim 1, where the controller is further configured to adjust the restriction valve to decrease the amount of flow restriction between the storage material in the fuel vapor canister and adjust the duty-cycle of the pump to decrease the amount of vacuum provided to the fuel vapor canister following the fuel vapor purging event. ### Claim 4 A system for an engine with a fuel vapor recovery system, comprising: a fuel vapor canister; a restriction valve disposed in a purge flow path between storage material in the fuel vapor canister; an atmosphere vent coupled to the fuel vapor canister and a vent valve disposed therein; a purge conduit coupled to the fuel vapor canister and an intake of the engine and having a purge valve arranged therein; a sensor arranged in the purge conduit; and a controller with instructions programmed therein to: initiate a fuel vapor purging event, the initiation including increasing opening of the purge valve to a first opening amount while maintaining the restriction valve fully open; determine, based on input from the sensor, an amount of fuel vapor purged from the fuel vapor canister; in response to the amount of fuel vapor purged from the fuel vapor canister decreasing below a first threshold, further increase the opening of the purge valve to a second opening amount while maintaining the restriction valve fully open; in response to the amount of fuel vapor purged from the fuel vapor canister decreasing below a second threshold, the second threshold lower than the first threshold, decrease opening of the restriction valve while maintaining the opening of the purge valve at the second opening amount; and maintain the vent valve open throughout a duration of the fuel vapor purging event. ### Claim 5 (depends on 4) The system of claim 4, wherein the controller further includes instructions to adjust the restriction valve to increase an amount of flow restriction in response to the amount of fuel vapor purged from the fuel vapor canister less than a threshold. ### Claim 6 (depends on 4) The system of claim 4, wherein the controller further includes instructions to adjust the restriction valve to decrease the amount of flow restriction between storage material in the fuel vapor canister following the fuel vapor purging event. ### Claim 7 (depends on 4) The system of claim 4, wherein the controller further includes instructions to adjust the purge valve in the purge conduit to increase an amount of vacuum provided to the fuel vapor canister before increasing an amount of flow restriction between storage material in the fuel vapor canister. ### Claim 8 (depends on 7) The system of claim 7, wherein the controller further includes instructions to adjust the purge valve in the purge conduit to increase the amount of vacuum provided to the fuel vapor canister in response to the amount of fuel vapor purged from the fuel vapor canister less than a threshold. ### Claim 9 (depends on 4) The system of claim 4, wherein the fuel vapor canister includes a first charcoal bed in communication with a second charcoal bed and wherein the controller further includes instructions to restrict communication between the first and second charcoal beds via the restriction valve. ### Claim 10 (depends on 4) The system of claim 4, wherein the controller further includes instructions to adjust the restriction valve to increase an amount of flow restriction between storage material in the fuel vapor canister by a first amount in response to a first event and increase the amount of flow restriction between storage material in the fuel vapor canister by a second amount in response to a second event, where the second event is subsequent to the first event and where the second amount is greater than the first amount. ### Claim 11 (depends on 10) The system of claim 10, wherein the first event is the initiation of the fuel vapor purging event and the second event is the amount of fuel vapor purged from the fuel vapor canister less than a threshold. ### Claim 12 (depends on 10) The system of claim 10, wherein the first event is the amount of fuel vapor purged from the fuel vapor canister less than the first threshold and the second event is the amount of fuel vapor purged from the fuel vapor canister less than the second threshold. ### Claim 13 A system for an engine with a fuel vapor recovery system, comprising: a fuel vapor canister; a restriction valve disposed in a purge flow path between storage material in the fuel vapor canister; an atmosphere vent coupled to the fuel vapor canister and a vent valve disposed therein; a purge conduit coupled to the fuel vapor canister and an intake of the engine and having a sensor arranged therein; and a controller with instructions programmed therein to: initiate a fuel vapor purging event; determine, based on input from the sensor, an amount of fuel vapor purged from the fuel vapor canister; adjust the restriction valve to restrict flow between the storage material in the fuel vapor canister by a first amount; in response to the amount of fuel vapor purged from the fuel vapor canister below a first threshold, adjust the restriction valve to restrict flow restriction between the storage material in the fuel vapor canister by a second amount, where the second amount is greater than the first amount; in response to the amount of fuel vapor purged from the fuel vapor canister below a second threshold, adjust the restriction valve to restrict flow restriction between the storage material in the fuel vapor canister by a third amount, where the third amount is less than the second amount; and throughout a duration of the fuel vapor purging event, adjust a purge valve in the purge conduit to adjust an amount of vacuum provided to the fuel vapor canister in response to the amount of fuel vapor purged from the fuel vapor canister. ### Claim 14 (depends on 13) The system of claim 13, wherein the controller further includes instructions to initiate the fuel vapor purging event by opening the vent valve coupled to the fuel vapor canister and maintaining the vent valve open at a fixed position throughout the duration of the fuel vapor purging event. ### Claim 15 (depends on 13) The system of claim 13, wherein the third amount of restriction is substantially the same as the first amount of restriction and flow restriction between the storage material in the fuel vapor canister is maintained at the first amount following the fuel vapor purging event. ### Claim 16 (depends on 13) The system of claim 13, wherein the controller further includes instructions to adjust the purge valve in the purge conduit to increase the amount of vacuum provided to the fuel vapor canister before restricting flow restriction between the storage material in the fuel vapor canister by the second amount. ### Claim 17 (depends on 16) The system of claim 16, wherein the controller further includes instructions to adjust the purge valve in the purge conduit to increase the amount of vacuum provided to the fuel vapor canister in response to the amount of fuel vapor purged from the fuel vapor canister below a third threshold. ### Claim 18 (depends on 13) The system of claim 13, wherein the fuel vapor canister includes a first charcoal bed in communication with a second charcoal bed and wherein the controller further includes instructions to restrict communication between the first and second charcoal beds. ### Claim 19 (depends on 4) The system of claim 4, wherein the controller further includes instructions to adjust a fuel injection amount in response to an adjustment to an amount of vacuum provided to the fuel vapor canister.