Method to control fuel vapor purging

• US 6,715,462 B2
• Filed: 06/04/2002
• Issued: 04/06/2004
• Est. Priority Date: 06/04/2002
• Status: Active Grant

• Current Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Original Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Inventors: Surnilla, Gopichandra, Bidner, David Karl
• Primary Examiner(s): Gimie, Mahmoud
• Application Number:
  US10/064,022
• Publication Number:
  US 20030221681A1
• Time in Patent Office: 672 Days
• Field of Search: 123/516, 123/518, 123/519, 123/520, 123/443, 123/198.F, 123/691, 123/481, 602/85, 602/90, 602/74, 602/76, 602/89, 602/83
• US Class Current: 123/198.00F
• CPC Class Codes: F02D 2200/0804 Estimation of the temperature of the exhaust gas treatment apparatus
• CPC Class Codes: F02D 31/003 for idle speed control
• CPC Class Codes: F02D 41/0042 Controlling the combustible mixture as a function of the canister purging, e.g. control of injected fuel to compensate for deviation of air fuel ratio when purging
• CPC Class Codes: F02D 41/0045 Estimating, calculating or determining the purging rate, amount, flow or concentration
• CPC Class Codes: F02D 41/0082 per groups or banks F02D41/0087 takes precedence
• CPC Class Codes: F02D 41/1456 with sensor output signal being linear or quasi-linear with the concentration of oxygen
• CPC Class Codes: F02D 41/222 relating to the failure of sensors or parameter detection devices
• CPC Class Codes: F02D 41/2448 Prohibition of learning
• CPC Class Codes: F02D 41/2454 Learning of the air-fuel ratio control

Abstract

A method is disclosed for controlling operation of an engine coupled to an exhaust treatment catalyst. Under predetermined conditions, the method operates an engine with a first group of cylinders combusting a lean air/fuel mixture and a second group of cylinders pumping air only (i.e., without fuel injection). In addition, the engine control method also provides the following features in combination with the above-described split air/lean mode: idle speed control, sensor diagnostics, air/fuel ratio control, adaptive learning, fuel vapor purging, catalyst temperature estimation, default operation, and exhaust gas and emission control device temperature control. In addition, the engine control method also changes to combusting in all cylinders under preselected operating conditions such as fuel vapor purging, manifold vacuum control, and purging of stored oxidants in an emission control device.

Claims

1. A method for operating an engine having a first and second group of cylinders, comprising:

operating in a first mode wherein the first cylinder group operates with air and substantially no injected fuel and the second cylinder group operates by combusting air and injected fuel;

providing a request for fuel vapor purging;

in response to said request, disabling said first mode of operation and operating the engine in a second mode of operation.

2. The method recited in claim 1, wherein said second mode of operation comprises operating both first and second cylinder groups with a combusted air-fuel mixture.

3. The method recited in claim 1 wherein said combustion in said second cylinder group in the first mode is lean of stoichiometry.

4. The method recited in claim 1 wherein said second mode of operation comprises operating both first and second cylinder groups with a combusted air-fuel mixture near stoichiometry.

5. The method recited in claim 1 wherein an emission control device is coupled to both said first and second group.

6. The method recited in claim 1 wherein an emission control device, capable of retaining NOx when excess oxygen is present and releasing and reacting said stored NOx when the exhaust mixture is rich or near stoichiometry, is coupled to said second group.

7. A method for operating an engine having a first and second group of cylinders, comprising:

operating in a first mode wherein the first cylinder group operates with air and substantially no injected fuel and the_second cylinder group operates by combusting air and injected fuel;

providing a request for fuel vapor purging;

in response to said request, if exhaust temperature is within a predetermined range, continuing operation of said first mode and enabling said fuel vapor purging.

8. The method recited in claim 7 wherein said request for fuel vapor purging is based on ambient temperature.

9. The method recited in claim 7 wherein said combusted air and injected fuel in the second group is lean of stoichiometry.

10. The method recited in claim 7 wherein said combusted air and injected fuel in the second group is near stoichiometry.

11. The method recited in claim 7 further comprising disabling said first mode if temperature is outside said predetermined range.

12. A method for operating an engine having a first and second group of cylinders, comprising:

operating in a first mode wherein the first cylinder group operates with air and substantially no injected fuel and the second cylinder group operates by combusting air and injected fuel;

providing a request for fuel vapor purging;

in response to said request, if exhaust temperature is within a predetermined range, continuing operation of said first mode and enabling said fuel vapor purging; and

if exhaust temperature is outside said predetermined range, disabling said first mode of operation and operating the engine in a second mode of operation.

13. The method recited in claim 12 wherein said temperature range is a temperature range of an emission control device coupled to the engine.