IPC분류정보
국가/구분 |
United States(US) Patent
등록
|
국제특허분류(IPC7판) |
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출원번호 |
US-0677544
(2012-11-15)
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등록번호 |
US-9932937
(2018-04-03)
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발명자
/ 주소 |
- Jentz, Robert Roy
- Peters, Mark W.
- Bohr, Scott A.
- Pearce, Russell Randall
- Dudar, Aed M.
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출원인 / 주소 |
- Ford Global Technologies, LLC
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대리인 / 주소 |
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인용정보 |
피인용 횟수 :
0 인용 특허 :
11 |
초록
▼
Methods and system are provided for distinguishing fuel tank vacuum generation due to canister purge valve degradation from vacuum generation due to canister vent valve degradation. A fuel tank vacuum level is monitored after sealing the fuel tank from the atmosphere following an engine pull-down. I
Methods and system are provided for distinguishing fuel tank vacuum generation due to canister purge valve degradation from vacuum generation due to canister vent valve degradation. A fuel tank vacuum level is monitored after sealing the fuel tank from the atmosphere following an engine pull-down. If there is an ensuing change in fuel tank vacuum, canister purge valve degradation is determined, else, canister vent valve degradation is determined.
대표청구항
▼
1. A method for an engine, comprising: via an engine controller: sealing a fuel system after an engine pull-down;distinguishing degradation of a canister vent valve from degradation of a canister purge valve based on a change in fuel system vacuum following the sealing;in response to canister vent v
1. A method for an engine, comprising: via an engine controller: sealing a fuel system after an engine pull-down;distinguishing degradation of a canister vent valve from degradation of a canister purge valve based on a change in fuel system vacuum following the sealing;in response to canister vent valve degradation being distinguished from the change, limiting subsequent fuel vapor purging via the canister purge valve;in response to canister purge valve degradation being distinguished from the change, closing the canister vent valve;monitoring fuel tank pressure during engine running conditions and wherein the distinguishing includes, in response to fuel system vacuum being higher than a threshold before the sealing and being lower than the threshold after the sealing, indicating canister purge valve degradation and not indicating canister vent valve degradation, and in response thereto, closing the canister vent valve;in response to fuel system vacuum being higher than the threshold before the sealing and after the sealing, actuating the canister purge valve closed while actuating the canister vent valve open, and indicating canister vent valve degradation but not canister purge valve degradation in response to the fuel system vacuum remaining higher than the threshold after the actuating and limiting subsequent fuel vapor purging in response to the indication of canister vent valve degradation; andindicating a blockage in a fresh air line in response to bleed-up of the fuel system vacuum from the threshold after the actuating,wherein sealing the fuel system includes closing the canister vent valve to seal the fuel system from atmosphere, and closing the canister purge valve to seal the fuel system from engine intake, the method further comprising indicating, via the controller, the distinguished degradation, wherein the controller receives the fuel system vacuum from a sensor coupled to a fuel tank of the fuel system, andwherein indicating canister vent valve degradation includes indicating that a canister vent valve solenoid is stuck closed. 2. The method of claim 1, wherein indicating canister purge valve degradation includes indicating that the canister purge valve is stuck open. 3. The method of claim 1, wherein the engine pull-down includes each of a vehicle key-off condition, a vehicle key-on engine idle-stop, and a vehicle key-on electric mode of operation. 4. The method of claim 3, further comprising maintaining the engine controller awake during the engine pull-down. 5. The method of claim 1, wherein the fuel system vacuum includes a fuel tank vacuum level. 6. A method for a vehicle fuel system, comprising: via a controller: sealing a fuel tank from atmosphere and engine intake after an engine pull-down;during a first condition, indicating canister purge valve degradation based on a change in fuel tank vacuum following the sealing;during a second condition, indicating canister vent valve degradation based on the change in fuel tank vacuum following the sealing;adjusting vehicle fuel system operation based on the indications; andmonitoring fuel tank pressure during engine running conditions, and wherein the sealing is performed in response to fuel tank vacuum being higher than a threshold during engine running, and further wherein the sealing is performed after the engine pull-down, the controller receiving fuel tank vacuum from a fuel tank pressure sensor coupled to the fuel tank. 7. The method of claim 6, wherein sealing the fuel tank from atmosphere and engine intake includes actuating a canister vent valve closed while maintaining a canister purge valve closed. 8. The method of claim 7, wherein, during the first condition, the indicating includes indicating that the canister purge valve is stuck open in response to the fuel tank vacuum being lower than the threshold following the sealing. 9. The method of claim 8, wherein, during the second condition, the indicating includes indicating that the canister vent valve is stuck closed in response to the fuel tank vacuum remaining higher than the threshold after the sealing, and also remaining higher than the threshold upon actuating the canister vent valve open, the method further comprising disabling purging in response to the canister vent valve indicated as stuck closed, and closing the canister vent valve in response to the canister purge valve indicated as stuck open. 10. The method of claim 9, further comprising, during a third condition, in response to fuel tank vacuum remaining higher than the threshold after the sealing, and bleeding up to atmospheric conditions upon actuating the canister vent valve, indicating no degradation of either the canister vent valve or the canister purge valve, and further indicating a blockage in a canister fresh air line, the method further comprising disabling purging operation in response to the indication of no degradation of either the canister vent valve or the canister purge valve and the indication of the blockage during the third condition. 11. A fuel system for a vehicle, comprising: a fuel tank for storing fuel used by a vehicle engine;a canister coupled to the fuel tank for receiving and storing fuel tank vapors;a canister purge valve coupled between the canister and an engine intake manifold for delivering stored fuel tank vapors from the canister to the engine;a canister vent valve coupled between the canister and atmosphere;a sensor indicating fuel tank vacuum; anda controller with computer readable instructions for, receiving information indicative of fuel tank vacuum from the sensor;in response to fuel tank vacuum being higher than a threshold during engine running, isolating the fuel tank after a subsequent engine pull-down;monitoring a change in fuel tank vacuum following the engine pull-down; anddistinguishing canister purge valve degradation from canister vent valve degradation based on the monitored change in fuel tank vacuum; andin response to canister vent valve degradation being distinguished, limiting subsequent fuel vapor purging via the canister purge valve; andin response to canister purge valve degradation being distinguished, closing the canister vent valve. 12. The system of claim 11, wherein the fuel tank being isolated after the engine pull-down includes the canister vent valve being actuated closed. 13. The system of claim 12, wherein the distinguishing includes indicating that the canister purge valve is stuck open in response to the fuel tank vacuum being lower than the threshold after the fuel tank is isolated, and indicating that the canister vent valve is stuck closed in response to the fuel tank vacuum remaining higher than the threshold after the fuel tank is isolated, and remaining higher than the threshold upon actuating the canister vent valve open. 14. The system of claim 13, wherein the controller includes further instructions for indicating a blockage in a fresh air line in response to bleed-up of the fuel tank vacuum from the threshold upon the actuating of the canister vent valve open. 15. The method of claim 6, wherein degradation of the canister vent valve is indicated based on whether excessive fuel tank vacuum persists in the sealed fuel tank after the engine pull-down, whereas degradation of the canister purge valve is indicated based on the fuel tank vacuum starting to bleed-up after the engine pull-down, the method further comprising disabling purging via the canister purge valve in response to the canister vent valve indicated as degraded, and closing the canister vent valve in response to the canister purge valve indicated as degraded.
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