Fuel oxidation reduction for hybrid vehicles

Patent metadata

Field	Value
Publication number	US-9488136-B2
Application number	US-201314035840-A
Country	US
Kind code	B2
Filing date	Sep 24, 2013
Priority date	Sep 24, 2013
Publication date	Nov 8, 2016
Grant date	Nov 8, 2016

Abstract

Systems and methods to control fuel tank pressure to reduce fuel oxidation in plug-in hybrid electric vehicles are disclosed. A method comprises routing vapors from a fuel system canister to the fuel tank to maintain the fuel tank pressure at a desired pressure. In this way, the engine may be maintained off for greater durations while still retaining fuel quality of fuel stored on-board the vehicle.

First claim

The invention claimed is:

1. A method, comprising:
responsive to fuel tank pressure below a threshold, routing fuel vapors from a fuel system canister to the fuel tank to maintain the fuel tank pressure at a desired pressure;
sensing hydrocarbon concentration of the fuel vapors exiting the canister and entering the fuel tank; and
stopping the routing responsive to an indication that atmospheric air comprising oxygen is being introduced into the fuel tank.

2. The method of claim 1 , wherein routing fuel vapors from the fuel system canister comprises activating a vapor pump to evacuate the fuel system canister; and wherein
stopping the routing comprises controlling the vapor pump such that oxygen is not introduced into the fuel tank.

3. The method of claim 1 , wherein routing fuel vapors from the fuel system canister to the fuel tank comprises actuating open a diverter valve between the canister and atmosphere in a diverter line stemming off the canister to draw air into the fuel system canister pushing fuel vapors into the fuel tank; and wherein
stopping the routing comprises actuating closed the diverter valve.

4. The method of claim 1 , wherein the desired pressure includes fuel tank pressure above the threshold, and wherein the routing is stopped responsive to fuel tank pressure above the threshold.

5. The method of claim 1 , wherein the routing reduces fuel oxidation and chemical degradation of fuel system components.

6. A system for reducing fuel oxidation, comprising:
a fuel tank;
a pressure sensor to sense vapor pressure within the fuel tank;
a vapor canister coupled to atmosphere via a diverter line and coupled to the fuel tank via a vapor line;
a fuel tank isolation valve positioned in the vapor line;
a diverter valve positioned in the diverter line;
a hydrocarbon sensor positioned between the fuel tank and the fuel vapor canister; and
a controller storing instructions in non-transitory memory, that when executed, cause the controller to:
responsive to an indication that fuel tank pressure is below a threshold, actuating open the diverter valve to pull air into the canister, pushing hydrocarbon vapors into the fuel tank to mitigate negative fuel tank pressure;
monitor a hydrocarbon concentration in the vapor line via the hydrocarbon sensor; and
in a first condition, close the diverter valve responsive to fuel tank pressure above the threshold; and
in a second condition, close the diverter valve responsive to hydrocarbon concentration below a threshold;
wherein closing the diverter valve responsive to hydrocarbon concentration below the threshold prevents atmospheric air comprising oxygen into the fuel tank.

7. The system of claim 6 , further comprising an expandable foam within the fuel tank; and wherein
the foam expands responsive to negative fuel tank pressure to keep the fuel tank pressure within predetermined thresholds.

8. The system of claim 6 , further comprising a contractible inner skin within the fuel tank, the inner skin lining the fuel tank within a rigid body outer fuel tank; and wherein
the inner skin contracts in the presence of vacuum to keep the fuel tank pressure within predetermined thresholds.

9. The system of claim 6 , further comprising a portion of a fuel tank wall comprised of a contractible material, the contractible material attached to rigid material comprising the fuel tank wall; and wherein
the contractible material contracts inward in the event of negative pressure in the fuel tank.

10. The system of claim 6 , further comprising a contractible bladder within the fuel tank that expands responsive to negative fuel tank pressure to keep the fuel tank pressure within predetermined thresholds; and wherein
the contractible bladder contains an inert gas.

11. The system of claim 6 , wherein the vapor canister is part of a non-integrated refueling canister only system.

Assignees

• Ford Global Tech Llc

Inventors

• Pearce Russell Randall
• Kuenzel Kenneth J

Classifications

• F02M25/0809 Primary

  Judging failure of purge control system · CPC title