CANISTER PURGE VALVE SELF-CLEANING CYCLE

• US 20140311461A1
• Filed: 04/18/2013
• Published: 10/23/2014
• Est. Priority Date: 04/18/2013
• Status: Active Grant

• Current Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Original Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Inventors: Dudar, Aed M., Yang, Dennis Seung-Man, Pearce, Russell Randall, Peters, Mark W., Plymale, Kevin William
• Granted Patent: US 9,243,592 B2
• Time in Patent Office: Days
• US Class Current: 123/520
• CPC Class Codes: F02D 41/004 Control of the valve or purge actuator, e.g. duty cycle, closed loop control of position
• CPC Class Codes: F02M 25/0818 having means for pressurising the evaporative emission space
• CPC Class Codes: F02M 25/089 Layout of the fuel vapour installation

Abstract

A method for a fuel system coupled to an engine comprising: under vacuum conditions, opening the fuel vapor canister purge valve, and generating pressure pulsations in a conduit coupled to the fuel vapor canister purge valve by opening and closing a fuel vapor canister vent valve one or more times while maintaining the fuel vapor canister purge valve open. In this way, contaminants and/or debris that may prevent the canister purge valve from closing completely may be dislodged and evacuated to the intake manifold.

Claims

1. A method for a fuel system coupled to an engine, comprising:

under predetermined engine operating conditions, opening a canister purge valve; and

while maintaining the canister purge valve open, pulsing a canister vent solenoid valve open and closed one or more times to generate pressure pulsations in a conduit coupled to the canister purge valve.

2. The method of claim 1, where the predetermined engine operating conditions include only when a manifold absolute pressure is greater than a predetermined threshold.

3. The method of claim 2, where the predetermined engine operating conditions further include a previously detected, but unconfirmed, evaporative emission system leak.

4. The method of claim 1, further comprising:

following pulsing the canister vent solenoid valve open and closed one or more times, performing an evaporative emission system leak test.

5. The method of claim 4, further comprising:

only following the evaporative emission system leak test, actuating a malfunction indicator in response to a positive leak detection test.

6. The method of claim 4, further comprising:

following the evaporative emission system leak test, resetting the leak detection status in response to a negative leak detection test and maintaining non-actuation of a malfunction indicator.

7. The method of claim 1, where opening the canister purge valve includes opening the canister purge valve at 100% duty cycle.

8. The method of claim 1, where the engine is included in a hybrid-electric vehicle.

9. The method of claim 8, where the predetermined engine operating conditions include an engine-on condition.

10. The method of claim 9, further comprising:

prior to opening the canister purge valve, closing a fuel tank isolation valve and maintaining the fuel tank isolation valve closed until after the canister vent solenoid valve has been pulsed open and closed one or more times.

11. A method for cleaning a fuel vapor canister purge valve, comprising:

under vacuum conditions, opening the fuel vapor canister purge valve; and

generating pressure pulsations in a conduit coupled to the fuel vapor canister purge valve by opening and closing a fuel vapor canister vent valve one or more times while maintaining the fuel vapor canister purge valve open.

12. The method of claim 11, where the vacuum conditions include a manifold absolute pressure that is greater than a predetermined threshold.

13. The method of claim 12, where the vacuum conditions include closing a fuel tank isolation valve prior to opening the fuel vapor canister purge valve, and maintaining the fuel tank isolation valve closed until after the fuel vapor canister vent valve has been pulsed open and closed one or more times.

14. The method of claim 11, where opening the fuel vapor canister purge valve includes opening the fuel vapor canister purge valve at 100% duty cycle.

15. The method of claim 11, further comprising:

following pulsing the fuel vapor canister vent valve open and closed one or more times, performing an evaporative emission system leak test.

16. A fuel system for a vehicle, comprising:

a fuel tank for storing fuel used by a vehicle engine;

a fuel vapor canister coupled to the fuel tank for receiving and storing fuel tank vapors;

a fuel vapor canister purge valve coupled between the fuel vapor canister and an engine intake manifold for delivering stored fuel tank vapors from the fuel vapor canister to the engine;

a fuel vapor canister vent solenoid valve coupled between the fuel vapor canister and atmosphere; and

a controller including computer readable instructions for,

in response to a manifold absolute pressure being higher than a threshold during engine-on conditions,

opening the fuel vapor canister purge valve for a predetermined duration,

while maintaining the fuel vapor canister purge valve open, pulsing the fuel vapor canister vent solenoid valve open and closed one or more times to generate pressure pulsations in a conduit coupled to the canister purge valve.

17. The fuel system of claim 16, where opening the fuel vapor canister purge valve for a predetermined duration includes opening the fuel vapor canister purge valve at 100% duty cycle.

18. The fuel system of claim 16, further comprising a fuel tank isolation valve coupled between the fuel tank and the fuel vapor canister, and wherein the controller includes further instructions for closing the fuel tank isolation valve prior to opening the fuel vapor canister purge valve, and maintaining the fuel tank isolation valve closed until after the fuel vapor canister vent solenoid valve has been pulsed open and closed one or more times.

19. The fuel system of claim 18, where the vehicle engine is a hybrid-electric engine.

20. The fuel system of claim 16 where the controller is includes further instructions for following pulsing the fuel vapor canister vent solenoid valve open and closed one or more times, performing an evaporative emission system leak test.