FUEL SYSTEM DEGRADATION TEST USING TWO FUEL TANKS

• US 20140107906A1
• Filed: 10/17/2012
• Published: 04/17/2014
• Est. Priority Date: 10/17/2012
• Status: Active Grant

• Current Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Original Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Inventors: Jentz, Robert Roy, Bohr, Scott A., Pearce, Russell Randall, Dudar, Aed M.
• Granted Patent: US 9,086,040 B2
• Time in Patent Office: Days
• US Class Current: 701/102
• CPC Class Codes: B60W 20/18 for avoiding ageing of fuel
• CPC Class Codes: B60W 2530/211 Fuel quality, e.g. water content due to age of fuel
• CPC Class Codes: F02D 2041/225 Leakage detection
• CPC Class Codes: F02M 25/08 adding fuel vapours drawn from engine fuel reservoir electrical control of purge system F02D41/003
• CPC Class Codes: F02M 25/0809 Judging failure of purge control system
• CPC Class Codes: F02M 25/0818 having means for pressurising the evaporative emission space
• CPC Class Codes: F02M 37/0088 Multiple separate fuel tanks or tanks being at least partially partitioned
• CPC Class Codes: F02M 37/18 characterised by provision of main and auxiliary pumps
• CPC Class Codes: G01M 3/00 Investigating fluid-tightness of structures
• CPC Class Codes: G01M 3/02 by using fluid or vacuum

Abstract

Embodiments for monitoring fuel system degradation are provided. In one example, a method for a vehicle comprises evacuating fuel from a first fuel tank to a second fuel tank, and indicating fuel system degradation in response to a change in fuel system pressure following the evacuation of fuel. In this way, fuel system degradation may be indicated without use of a separate pressure building device.

Claims

1. A method for a vehicle, comprising:

evacuating fuel from a first fuel tank to a second fuel tank; and

indicating fuel system degradation in response to a change in fuel system pressure following the evacuation of fuel.

2. The method of claim 1, further comprising activating a fuel pump in the first fuel tank to transfer fuel to the second tank.

3. The method of claim 1, further comprising applying negative pressure to first fuel tank and positive pressure to second fuel tank by evacuating the fuel.

4. The method of claim 3, further comprising monitoring a change in negative pressure built in the first fuel tank, and if pressure increases by greater than a threshold rate, then indicating fuel system degradation.

5. The method of claim 3, further comprising monitoring a change in positive pressure built in the second fuel tank, and if pressure decreases by greater than a threshold rate, then indicating fuel system degradation.

6. The method of claim 1, further comprising sealing off the first fuel tank from the second fuel tank prior to evacuating the fuel.

7. The method of claim 1, wherein the fuel comprises ethanol.

8. A method for a vehicle having a fuel system, comprising:

during an engine off condition, applying pressure to the fuel system by transferring fuel from a first fuel tank to a second fuel tank; and

once a threshold pressure in the fuel system is reached, indicating fuel system degradation in response to a subsequent change in fuel system pressure.

9. The method of claim 8, wherein indicating fuel system degradation in response to a subsequent change in fuel system pressure includes indicating a fuel system leak based on an absolute rate of change in the fuel system pressure being higher than a threshold rate.

10. The method of claim 9, wherein an orifice size of the fuel system leak is based on a difference between the absolute rate of change in the fuel system pressure and the threshold rate.

11. The method of claim 8, wherein the fuel system pressure is a fuel tank pressure of the first fuel tank estimated by a pressure sensor of the first fuel tank.

12. The method of claim 8, wherein the fuel system pressure is a fuel tank pressure of the second fuel tank estimated by a pressure sensor of the second fuel tank.

13. The method of claim 8, wherein the vehicle is a hybrid vehicle, and wherein the engine off condition comprises a battery operation mode of the hybrid vehicle.

14. A vehicle fuel system, comprising:

a first fuel tank including a fuel pump;

a second fuel tank;

a fuel vapor canister coupled to the first fuel tank; and

a controller including instructions to;

manipulate a vapor space of the first fuel tank to apply pressure to the fuel system; and

indicate a leak in the fuel system based on a change in pressure of the fuel system following the application of pressure.

15. The vehicle fuel system of claim 14, wherein the controller includes further instructions to activate the fuel pump to transfer fuel from the first tank to the second fuel tank to manipulate the vapor space of the first fuel tank.

16. The vehicle fuel system of claim 15, wherein an amount of negative pressure applied to the first fuel tank is proportional to an amount of fuel transferred from the first fuel tank.

17. The vehicle fuel system of claim 15, wherein an amount of positive pressure applied to the second fuel tank is proportional to an amount of fuel transferred to the second fuel tank.

18. The vehicle fuel system of claim 14, wherein the first fuel tank and the second fuel tank are contained in a common fuel tank.

19. The vehicle fuel system of claim 14, wherein the fuel comprises ethanol.

20. The vehicle fuel system of claim 14, wherein the controller includes further instructions to manipulate the vapor space of the first fuel tank during an engine off condition.