METHOD FOR DETECTING FUEL SYSTEM DEGRADATION

• US 20160341141A1
• Filed: 05/22/2015
• Published: 11/24/2016
• Est. Priority Date: 05/22/2015
• 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., Pearce, Russell Randall, Yang, Dennis Seung-Man
• Granted Patent: US 10,077,731 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: B60K 15/03504 adapted to avoid loss of fuel or fuel vapour, e.g. with vapour recovery systems
• CPC Class Codes: B60K 15/03519 Valve arrangements in the vent line
• CPC Class Codes: B60K 2015/03118 Multiple tanks, i.e. two or more separate tanks supplementary tanks inside the fuel tank B60K2015/03105
• CPC Class Codes: B60K 2015/03514 with vapor recovery means
• CPC Class Codes: F02D 2041/225 Leakage detection
• CPC Class Codes: F02D 33/003 Controlling the feeding of liquid fuel from storage containers to carburettors or fuel-injection apparatus control of electrical fuel pumps F02D41/3082, controlling fuel flow to a common rail F02D41/3845; Failure or leakage prevention; Diagnosis or detection of failure; Arrangement of sensors in the fuel system; Electric wiring; Electrostatic discharge
• CPC Class Codes: F02D 41/22 Safety or indicating devices for abnormal conditions in air/fuel ratio feedback systems F02D41/1495, in electric control linkage F02D11/107, in purge control systems F02M25/0809
• CPC Class Codes: F02M 25/0809 Judging failure of purge control system
• CPC Class Codes: F02M 25/089 Layout of the fuel vapour installation
• CPC Class Codes: F02M 37/0088 Multiple separate fuel tanks or tanks being at least partially partitioned
• CPC Class Codes: G01M 3/3209 Details, e.g. container closure devices
• CPC Class Codes: G01M 3/3245 using a level monitoring device G01M3/3272 takes precedence
• CPC Class Codes: G01M 3/3272 for verifying the internal pressure of closed containers
• CPC Class Codes: Y02T 10/40 Engine management systems

Abstract

Methods and systems are provided for detecting leaks in an engine fuel system coupled in a vehicle including a first fuel tank and a second fuel tank, and a canister coupled together via a three-way valve. A leak test may be initially performed on the first fuel tank by supplying vacuum to the first fuel tank. The second fuel tank may be tested for leaks immediately following the leak test on the first fuel tank by recycling vacuum from the first fuel tank.

Claims

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

applying vacuum to a first fuel tank to identify leaks in the first fuel tank; and

recycling the vacuum from the first fuel tank to a second fuel tank to identify leaks in the second fuel tank following identifying leaks in the first fuel tank.

2. The method of claim 1, wherein the first fuel tank has a lower fuel fill than the second fuel tank.

3. The method of claim 2, further comprising, responsive to the second fuel tank having a lower fuel fill than the first fuel tank, applying the vacuum at first to the second fuel tank to identify leaks in the second fuel tank, and then recycling the vacuum from the second fuel tank to the first fuel tank to identify leaks in the first fuel tank.

4. The method of claim 3, further comprising, when the first fuel tank and the second fuel tank have substantially equal fuel fill, selecting one of the first fuel tank and the second fuel tank based on one or more of fuel temperature, level of fuel slosh, etc., applying vacuum at first to the one selected fuel tank to identify leaks in the one selected fuel tank, and then recycling vacuum from the one selected fuel tank to a remaining fuel tank to identify leaks in the remaining fuel tank.

5. The method of claim 1, wherein the vacuum is applied via a vacuum source during a key-off condition, and wherein the vacuum source is a vacuum pump.

6. The method of claim 1, further comprising identifying leaks in a fuel system canister prior to applying the vacuum to the first fuel tank, and wherein each of the first fuel tank and the second fuel tank are isolated from the canister while identifying leaks in the fuel system canister by adjusting a valve to a first position, the valve coupled to each of the fuel system canister, the first fuel tank, and the second fuel tank.

7. The method of claim 6, wherein the applying of vacuum to the first fuel tank includes adjusting the valve to a second position to enable fluidic communication between the first fuel tank and the fuel system canister.

8. The method of claim 7, wherein recycling vacuum from the first fuel tank to the second fuel tank includes adjusting the valve to a third position to enable fluidic communication between the first fuel tank, the second fuel tank, and the fuel system canister.

9. The method of claim 6, wherein leaks in the fuel system canister, leaks in the first fuel tank, and leaks in the second fuel tank are identified using a common pressure sensor.

10. The method of claim 9, further comprising indicating a leak in the first fuel tank in response to a pressure in the first fuel tank being higher than a first threshold pressure.

11. The method of claim 10, further comprising indicating a leak in the second fuel tank in response to a pressure in the second fuel tank being higher than a second threshold pressure, the second threshold pressure being different from the first threshold pressure.

12. The method of claim 11, wherein the second threshold pressure is based on the vacuum recycled from the first tank to the second tank.

13. The method of claim 1, wherein the vacuum is applied via a vacuum source during a key-on condition, and wherein the vacuum source is one of intake manifold vacuum and a vacuum pump.

14. The method of claim 13, wherein the engine is fueled via the second fuel tank while identifying leaks in the first fuel tank, and wherein the engine is fueled via the first fuel tank while identifying leaks in the second fuel tank.

15. A method for a fuel system in an engine, comprising:

adjusting a three-way valve to fluidically couple a first fuel tank to a vacuum source via a fuel system canister, the vacuum source applying vacuum to the first fuel tank to diagnose the first fuel tank for leaks;

modifying the three-way valve to fluidically couple the first fuel tank to a second fuel tank after diagnosing the first fuel tank for leaks; and

transferring vacuum from the first fuel tank to the second fuel tank to diagnose the second fuel tank for leaks.

16. The method of claim 15, wherein the three-way valve blocks fluidic communication between the first fuel tank and the second fuel tank while diagnosing the first fuel tank for leaks, and wherein the second fuel tank is diagnosed for leaks sequentially after diagnosing the first fuel tank for leaks to distinguish degradation between the first fuel tank and the second fuel tank.

17. The method of claim 15, further comprising diagnosing the fuel system canister for leaks prior to diagnosing the first fuel tank for leaks, and wherein diagnosing the fuel system canister for leaks includes adjusting the three-way valve to decouple the fuel system canister from each of the first fuel tank and the second fuel tank.

18. A system, comprising:

an engine receiving fuel from each of a first fuel tank and a second fuel tank;

a canister for storing fuel vapors from each of the first fuel tank and the second fuel tank;

a common valve coupled to each of the canister, the first fuel tank, and the second fuel tank, the valve including a first solenoid and a second solenoid;

a fuel tank pressure sensor coupled to each of the canister, the first fuel tank, and the second fuel tank;

a first fuel level sensor coupled to the first fuel tank for estimating a fill level of the first fuel tank;

a second fuel level sensor coupled to the second fuel tank for estimating a fill level of the second fuel tank; and

a controller with computer readable instructions stored on non-transitory memory for;

responsive to a first condition,

energizing the second solenoid of the common valve while de-energizing the first solenoid of the common valve; and

connecting the first fuel tank to the canister while blocking connection between the second fuel tank and each of the first fuel tank and the canister via the common valve; and

in response to a second condition,

de-energizing the second solenoid of the common valve while maintaining the first solenoid de-energized; and

connecting the second fuel tank with each of the canister and the first fuel tank.

19. The system of claim 18, wherein the first condition includes performing a leak test with the first fuel tank having a lower fuel fill level than the second fuel tank, and wherein the second condition includes completion of the leak test on the first fuel tank and initiation of a subsequent leak test on the second fuel tank.

20. The system of claim 19, wherein the controller includes further instructions for:

responsive to a desired leak test with the second fuel tank having a lower fuel fill level than the first fuel tank,

energizing the first solenoid of the common valve while de-energizing the second solenoid of the common valve;

connecting the second fuel tank to the canister via the common valve while blocking connection between the first fuel tank and each of the canister and the second fuel tank via the common valve; and

in response to completing the leak test on the second fuel tank and initiating a subsequent leak test on the first fuel tank,

de-energizing the first solenoid of the common valve while maintaining the second solenoid de-energized; and

connecting the first fuel tank with each of the canister and the second fuel tank.