Systems and methods for vehicle evaporative emissions system diagnostics

Patent metadata

Field	Value
Publication number	US-10100782-B2
Application number	US-201615169915-A
Country	US
Kind code	B2
Filing date	Jun 1, 2016
Priority date	Jun 1, 2016
Publication date	Oct 16, 2018
Grant date	Oct 16, 2018

Abstract

Methods and systems are provided for conducting a diagnostic routine of the fuel vapor system using pressure generated by raising or lowering a vehicle body element such as a hood or a trunk. In one example, by utilizing lift gate cylinders coupled to the hood or trunk, during raising a hood or trunk, the fuel vapor system may be evacuated and during lowering the hood or trunk, the fuel vapor system may be pressurized. A change in vacuum or higher pressure in the fuel vapor system may be monitored over a time period to detect any undesirable evaporative emissions from the fuel vapor system.

First claim

The invention claimed is:

1. A method comprising:
adjusting pressure in a vehicle evaporative emissions system by raising or lowering a vehicle body element; and
conducting a test in the evaporative emissions system for detection of evaporative emissions based on the adjusted pressure,
wherein the vehicle body element includes a hood, a trunk, and/or a door.

2. The method of claim 1 , wherein the adjusting includes raising one or more of the hood, the trunk, and the door to evacuate air from the evaporative emissions system, and wherein the vehicle body element opens at least partially vertically, and where the opening is assisted or damped via a piston-cylinder element.

3. The method of claim 2 , wherein the adjusting includes lowering one or more of the hood, the trunk, and the door to pressurize the evaporative emissions system.

4. The method of claim 3 , further comprising:
indicating no evaporative emissions responsive to a pressure bleed-up rate lower than a first predetermined threshold bleed-up rate after evacuating air from the evaporative emissions system; and
indicating no evaporative emissions responsive to a pressure bleed-down rate lower than a second predetermined threshold bleed-down rate after pressurizing the evaporative emissions system.

5. The method of claim 3 , wherein raising or lowering one or more of the hood, the trunk, and the door includes actuating one or more lift gate cylinders, the one or more lift gate cylinders coupling a body of a vehicle to one or more of the hood, the trunk, and the door, the one or more lift gate cylinders further coupled to the evaporative emissions system via a hose.

6. The method of claim 5 , wherein the hose couples the one or more lift gate cylinders to a vent of the evaporative emissions system at a location between a fuel system canister and a canister vent valve, and wherein adjusting the pressure includes:
while actuating the one or more lift gate cylinders to raise one or more of the hood, the trunk, and the door, drawing air from the fuel system canister via the vent with the canister vent valve closed to lower an evaporative emissions system pressure; and
while actuating the one or more lift gate cylinders to lower one or more of the hood, the trunk, and the door, compressing air into the fuel system canister via the vent with the canister vent valve closed to raise the evaporative emissions system pressure.

7. The method of claim 1 , further comprising:
sealing the evaporative emissions system from each of atmosphere and an engine intake manifold responsive to an indication of one or more of the hood, the trunk, and the door being raised or lowered.

8. The method of claim 7 , further comprising:
prior to the sealing, depressurizing the evaporative emissions system and conducting the test responsive to an indication that a vehicle is not occupied; and if the vehicle is occupied, delaying conducting the test.

9. A method for a fuel vapor system of a vehicle, comprising:
during a first condition, applying negative pressure on the fuel vapor system via the raising of a trunk or a hood of the vehicle;
during a second condition, applying positive pressure on the fuel vapor system via the lowering of the trunk or hood of the vehicle; and
during both the first and the second condition, conducting a test including indicating presence of evaporative emissions responsive to a change in fuel vapor system pressure following the applying of positive or negative pressure.

10. The method of claim 9 , wherein during both the first and the second condition, the vehicle is unoccupied.

11. The method of claim 9 , wherein indicating the presence of evaporative emissions in the fuel vapor system responsive to the change in fuel vapor system pressure includes:
during the first condition, indicating presence of evaporative emissions in the fuel vapor system responsive to higher than threshold rate of pressure bleed-up after applying the negative pressure and indicating absence of evaporative emissions in the fuel vapor system responsive to lower than threshold rate of pressure bleed-up after applying the negative pressure; and
during the second condition, indicating the presence of evaporative emissions responsive to higher than threshold rate of pressure bleed-down after applying the positive pressure and indicating absence of evaporative emissions responsive to lower than threshold rate of pressure bleed-down after applying the positive pressure.

12. The method of claim 9 , further comprising:
in response to the trunk or hood being lowered before the conducting test is completed during the first condition, aborting the test and disregarding the change in fuel system pressure; and
in response to the trunk or hood being raised before the test is completed during the second condition, aborting the test and disregarding the change in fuel system pressure.

13. The method of claim 9 , wherein the fuel vapor system includes a fuel vapor canister coupled to atmosphere via a vent line having a vent valve, the canister coupled to an engine intake manifold via a purge line having a purge valve, the method further comprising, during both the first and second conditions, responsive to an indication that the trunk or hood is being raised or lowered, sealing the fuel vapor system from the atmosphere by closing the vent valve and the purge valve.

14. The method of claim 13 , further comprising, in response to the indication of presence of evaporative emissions, closing an isolation valve coupling the canister to a fuel tank.

15. The method of claim 13 , wherein raising the vehicle hood or trunk includes actuating a lift gate cylinder to a first position where a clearance between a lift gate piston and a cylinder head is larger, and wherein lowering the vehicle hood or trunk includes actuating the lift gate cylinder to a second position where the clearance between the lift gate piston and the cylinder head is smaller, wherein the lift gate piston is coupled to the vent line of the fuel vapor system, between the canister and the vent valve, via a hose.

16. The method of claim 15 , wherein applying negative pressure on the fuel vapor system via the raising during the first condition includes drawing air out of the vent line while actuating the lift gate cylinder to the first position, and wherein applying positive pressure on the fuel vapor system via the lowering during the second condition includes forcing air into the vent line while actuating the lift gate cylinder to the second position.

17. A fuel system for a vehicle engine, comprising:
a fuel tank;
a fuel vapor canister coupled to the fuel tank via an isolation valve;
a canister purge valve positioned in a purge line between the fuel vapor canister and an engine intake manifold;
a canister vent valve positioned in a vent line between the fuel vapor canister and atmosphere;
one or more lift gate cylinders connecting each of a hood and a trunk of a vehicle to a body of the vehicle;
a sensor for receiving operator input regarding a target position of the hood and/or the trunk of the vehicle;
a conduit coupling the lift gate cylinders to the vent line between the fuel vapor canister and the canister vent valve, the conduit including a lift gate valve; and
a controller storing instructions in non-transitory memory that, when executed, cause the controller to:
in response to operator input requesting the hood and/or the vehicle trunk opening, actuating the lift gate cylinder to open the hood or trunk;
closing each of the vent valve and the purge valve;
opening the lift

Assignees

• Ford Global Tech Llc

Inventors

• Lucka Kevin
• Yang Dennis Seung-Man
• Dudar Aed M
• Aghili Mohammad R

Classifications

• F04B35/008

  the means being a fluid transmission link · CPC title

• F02D2041/225

  Leakage detection · CPC title

• F04B39/12

  Casings; Cylinders; Cylinder heads; Fluid connections · CPC title

• F02M25/0854

  Details of the absorption canister · CPC title

• G01M3/025

  Details with respect to the testing of engines or engine parts · CPC title