COOLING FAN ASSISTED ENGINE-OFF NATURAL VACUUM TEST

• US 20150120133A1
• Filed: 10/29/2013
• Published: 04/30/2015
• Est. Priority Date: 10/29/2013
• 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., Jentz, Robert Roy, Yang, Dennis Seung-Man, Pearce, Russell Randall
• Granted Patent: US 9,140,627 B2
• Time in Patent Office: Days
• US Class Current: 701/34.4
• CPC Class Codes: F02M 25/00 Engine-pertinent apparatus for adding non-fuel substances or small quantities of secondary fuel to combustion-air, main fuel or fuel-air mixture adding secondary air to fuel-air mixture F02M23/00; adding exhaust gases F02M26/00; fuel-injection apparatus operating simultaneously on two or more fuels or on a liquid fuel and another liquid F02M43/00
• CPC Class Codes: F02M 25/0809 Judging failure of purge control system
• CPC Class Codes: F02M 31/20 for cooling F02M31/005 takes precedence; use of cold F02M17/52; cooling of charging-air or of scavenging-air F02B29/04
• CPC Class Codes: F02M 65/00 Testing fuel-injection apparatus, e.g. testing injection timing testing of ignition F02P17/00; measuring fuel consumption G01F9/00; Cleaning of fuel-injection apparatus
• CPC Class Codes: F02M 65/006 Measuring or detecting fuel leakage of fuel injection apparatus
• CPC Class Codes: G01M 17/007 Wheeled or endless-tracked vehicles G01M17/08 takes precedence
• CPC Class Codes: Y02T 10/12 Improving ICE efficiencies

Abstract

A method for a vehicle fuel system, comprising: during an engine-off condition, including an ambient temperature within a threshold range, operating a cooling fan to increase a fuel tank vacuum; and indicating leaks in the vehicle fuel system based on the increased vacuum. In this way, an EONV test may be run at mild ambient temperatures which would not otherwise result in the development of adequate fuel tank vacuum to pass the EONV test.

Claims

1. A method for a vehicle fuel system, comprising:

during an engine-off condition, including an ambient temperature within a threshold range, operating a cooling fan to increase a fuel tank vacuum; and

indicating leaks in the vehicle fuel system based on the increased vacuum.

2. The method of claim 1, where operating the cooling fan to increase the fuel tank vacuum includes operating the cooling fan for a first test duration, the first test duration based on an amount of stored battery charge.

3. The method of claim 2, further comprising:

in response to a fuel tank vacuum increasing above a vacuum threshold during the first test duration, indicating that no leak has been detected.

4. The method of claim 2, further comprising:

in response to a fuel tank vacuum failing to reach a vacuum threshold during the first test duration, indicating that a leak has been detected.

5. The method of claim 2, further comprising:

following an engine-off event, sealing the vehicle fuel system and monitoring a fuel tank pressure for a second test duration.

6. The method of claim 5, further comprising:

in response to the fuel tank pressure increasing above a pressure threshold during the second test duration, indicating that no leak has been detected.

7. The method of claim 5, further comprising:

in response to the fuel tank pressure failing to reach a pressure threshold during the second test duration, unsealing the vehicle fuel system and allowing the fuel tank pressure to equilibrate to atmospheric pressure.

8. The method of claim 7, further comprising:

in response to fuel tank pressure equilibrating to atmospheric pressure, sealing the vehicle fuel system and assessing the ambient temperature.

9. The method of claim 8, further comprising:

in response to an ambient temperature being outside of the threshold range, not operating a cooling fan to increase the fuel tank vacuum to identify leaks in the vehicle fuel system.

10. A method for a vehicle fuel system, comprising:

sealing a fuel tank and monitoring a fuel tank pressure after an engine-off event; and

in response to a change in fuel tank pressure during a monitoring period being less than a fuel tank pressure threshold,

unsealing the vehicle fuel system and allowing the fuel tank pressure to equilibrate to atmospheric pressure;

assessing an ambient temperature;

in response to the ambient temperature being within a threshold range,

sealing the vehicle fuel system; and

operating a cooling fan to increase a fuel tank vacuum to identify leaks in the vehicle fuel system.

11. The method of claim 10, further comprising:

in response to the ambient temperature being outside of the threshold range,

sealing the vehicle fuel system; and

not operating a cooling fan to increase the fuel tank vacuum to identify leaks in the vehicle fuel system.

12. The method of claim 11, where operating a cooling fan to increase a fuel tank vacuum to identify leaks in the vehicle fuel system further includes:

operating a cooling fan for a vacuum test duration, the vacuum test duration based on an amount of stored battery charge.

13. The method of claim 12, further comprising:

in response to a fuel tank vacuum increasing above a vacuum threshold during the vacuum test duration, indicating that no leak has been detected.

14. The method of claim 13, further comprising:

in response to the fuel tank vacuum failing to reach the vacuum threshold during the vacuum test duration, indicating that a leak has been detected.

15. The method of claim 10, wherein the vehicle fuel system includes a fuel tank coupled to a canister, the canister coupled to an engine intake via a canister purge valve and further coupled to atmosphere via a canister vent valve, and wherein sealing the vehicle fuel system includes closing each of the canister vent valve and canister purge valve.

16. The method of claim 15, where unsealing the vehicle fuel system includes opening the canister vent valve.

17. The method of claim 10, wherein the fuel tank pressure threshold is based on one or more of a vapor pressure of fuel vapors in a vapor space of the fuel tank and a fill level of the fuel tank.

18. The method of claim 14, wherein the vacuum threshold is based on a fill level of the fuel tank.

19. A vehicle system, comprising:

an engine including an intake;

a fuel system including a fuel tank, a fuel vapor canister, a first valve coupling the fuel vapor canister to the intake, and a second valve coupling the fuel vapor canister to atmosphere;

a pressure sensor coupled to the fuel tank for estimating a fuel tank pressure;

a temperature sensor externally coupled to the vehicle system for estimating ambient temperature;

an engine cooling system including one or more cooling fans; and

a control system including executable instructions stored in non-transitory memory for;

during an engine-off condition, in response to an ambient temperature being within a threshold temperature range;

closing the first valve and the second valve;

activating the one or more cooling fans; and

monitoring a fuel tank vacuum for a vacuum test duration to identify leaks in the fuel system.

20. The vehicle system of claim 19, where monitoring a fuel tank vacuum to identify leaks in the fuel system further comprises:

in response to a fuel tank vacuum increasing above a vacuum threshold during the vacuum test duration, indicating that no leak has been detected; and

in response to the fuel tank vacuum failing to reach the vacuum threshold during the vacuum test duration, indicating that a leak has been detected.