Software fuel volatility measurement

• US 7,059,313 B2
• Filed: 01/26/2005
• Issued: 06/13/2006
• Est. Priority Date: 10/09/2002
• Status: Active Grant

• Current Assignee: Ford Motor Company
• Original Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Inventors: Lippa, Allan J.
• Primary Examiner(s): HUYNH, HAI H
• Application Number:
  US11/044,790
• Publication Number:
  US 20050133013A1
• Time in Patent Office: 503 Days
• Field of Search: 123/518, 123/519, 123/520, 701/103, 701/107, 731/181, 731/182, 731/19.A
• US Class Current: 123/685
• CPC Class Codes: F02D 19/0665 Tanks, e.g. multiple tanks
• CPC Class Codes: F02D 19/084 Blends of gasoline and alcohols, e.g. E85
• CPC Class Codes: F02D 19/088 by estimation, i.e. without using direct measurements of a corresponding sensor
• CPC Class Codes: F02D 2200/0611 Fuel type, fuel composition or fuel quality
• CPC Class Codes: F02D 41/0025 Controlling engines characterised by use of non-liquid fuels, pluralities of fuels, or non-fuel substances added to the combustible mixtures
• CPC Class Codes: F02P 5/1502 using one central computing unit
• CPC Class Codes: F02P 5/1506 with particular means during starting
• CPC Class Codes: Y02T 10/30 Use of alternative fuels, e.g. biofuels
• CPC Class Codes: Y02T 10/40 Engine management systems

Abstract

A system is described using a fuel quality sensor or an estimate of fuel volatility for controlling various aspects of engine operation. For example, improved fuel tank leak detection may be achieved using an estimate of fuel volatility obtained from fuel purging operation.

Claims

1. A method of determining degradation of a fuel system including a fuel tank of a vehicle having an engine, the method comprising:

purging fuel vapors generated in the tank in the engine;

determining an indication of fuel volatility during said purging operation; and

enabling detection of degradation of the fuel system after the engine is stopped based on said indication.

2. The method of claim 1 wherein said purging is performed during engine operation.

3. The method of claim 1 further comprising, during purging, adjusting a fuel injection amount based on feedback from an exhaust gas oxygen sensor in an engine exhaust to obtain a desired air-fuel ratio.

4. The method of claim 3 wherein said indication is based on said feedback.

5. The method of claim 1 wherein said indication is based on a rate of change of estimate fuel vapors.

6. The method of claim 1 wherein said indication is adjusted based on mass air flow.

7. The method of claim 1 wherein said indication is affected by a purge valve position.

8. The method of claim 1 wherein degradation detects a leak in said fuel system based on changes in pressure in said fuel system after the engine is stopped.

9. The method of claim 8 wherein said degradation further includes closing a valve in said fuel system.

10. A method of determining degradation of a fuel system including a fuel tank of a vehicle having an engine, the method comprising:

purging fuel vapors generated in the tank in the engine;

determining an indication of fuel volatility during said purging operation that is affected by a rate of change of fuel vapor during said purging; and

adjusting engine operation based on said indication, wherein said adjusting engine operation includes enabling detection of degradation of the fuel system after the engine is stopped.

11. The method of claim 10 wherein said adjusting engine operation includes adjusting a fuel injection amount during engine starting.

12. A method of determining degradation of a fuel system including a fuel tank of a vehicle having an engine, the method comprising:

purging fuel vapors generated in the tank in the engine when fuel vapor entering the engine from a fuel system canister are below a threshold;

determining an indication of fuel volatility during said purging operation; and

enabling detection of degradation of the fuel system after the engine is stopped based on said indication.

13. A system for a mobile vehicle having an engine, comprising

a fuel tank;

a fuel system valve coupled to the fuel tank, said valve coupled between an environment of the vehicle and said tank;

a fuel system canister coupled in the system;

an exhaust gas sensor coupled in an engine exhaust; and

a controller for purging fuel vapors generated in the tank in the engine while the engine is performing combustion, determining an indication of fuel volatility based on said purging operation; and

enabling detection of degradation of the fuel system after the engine is stopped based on said indication.

14. The system of claim 13, wherein during said determining, said fuel system canister is blocked from the engine.