Idle speed control for lean burn engine with variable-displacement-like characteristic

• US 7,069,903 B2
• Filed: 07/08/2004
• Issued: 07/04/2006
• 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, Smith, Stephen B.
• Primary Examiner(s): HUYNH, HAI H
• Application Number:
  US10/888,713
• Publication Number:
  US 20040244770A1
• Time in Patent Office: 726 Days
• Field of Search: 123/399, 123/396, 123/299, 123/300, 123/481, 123/492, 123/493, 123/436, 123/352, 123/692, 701103-105, 701/110, 701/112
• US Class Current: 123/339.19
• CPC Class Codes: F02D 2200/1004 Estimation of the output torque
• 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 41/0087 Selective cylinder activation, i.e. partial cylinder operation deceleration cut-off F02D41/123
• CPC Class Codes: F02D 41/1456 with sensor output signal being linear or quasi-linear with the concentration of oxygen
• CPC Class Codes: F02D 41/1482 Integrator, i.e. variable slope
• CPC Class Codes: F02D 41/1497 With detection of the mechanical response of the engine
• CPC Class Codes: F02D 41/2461 by learning a value and then controlling another value

Abstract

A method is disclosed for controlling operation of a 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: auto speed control, sensor diagnostics, air-fuel ratio control, adaptive learning, fuel vapor purging, catalyst temperature estimation, and default operation. In addition, the engine control method also disables the split air/lean operating mode under preselected operating conditions.

Claims

1. A method for controlling an engine having a first and second group of combustion chambers, comprising:

inducting air and injecting fuel into the first combustion chamber group at a first average air-fuel ratio;

inducting air and not injecting fuel into the second combustion chamber group;

controlling airflow to at least both said first and second group via an electronically controlled throttle plate of the engine, and

adjusting both said injected fuel to the first combustion chamber group and the throttle plate based on a desired engine torque so that an actual speed approaches a desired speed and an air-fuel ratio is controlled within a preselected range.

2. The method recited in claim 1 wherein said first average air-fuel ratio is leaner than stoichiometry.

3. The method recited in claim 1 wherein said desired speed is a desired engine idle speed.

4. The method recited in claim 1 wherein said desired speed is a desired vehicle speed.

5. The method recited in claim 1 wherein said determined speed is a measured engine speed from a sensor coupled to a crankshaft of the engine.

6. The method recited in claim 1 wherein said determined speed is an estimated engine speed based on a sensor coupled to the engine.

7. The method recited in claim 1 wherein said injected fuel is injected directly into a cylinder of the engine.

8. The method recited in claim 1 wherein said injected fuel is injected into an intake port of an engine manifold coupled to an engine cylinder.

9. The method recited in claim 1 wherein said engine transitions to operating with injected fuel in said second group and adjusts said injected fuel to the first and second combustion chamber group and the throttle plate based on said desired engine torque so that said actual speed approaches said desired speed during an operating condition.

10. A method for controlling an engine having first and second groups of combustion chambers, comprising:

controlling airflow to the first and second group of the engine via an electronically controlled throttle plate in an intake of said engine;

operating the engine in a first operating mode where air and substantially no injected fuel is provided to the first combustion chamber group, and both air and injected fuel are provided to the second combustion chamber group, and both injected fuel to the second combustion chamber group and the throttle plate are adjusted to vary engine torque so that a determined actual speed approaches a desired speed and an air-fuel ratio is controlled within a preselected range; and

operating the engine in a second mode where both air and injected fuel are provided to both the first and second combustion chamber groups, and said air and said injected fuel provided to both said first and second combustion group is adjusted to vary engine torque so that said determined actual speed approaches said desired speed.

11. The method recited in claim 10 wherein when the engine is operating in said first operating mode, the second combustion chamber group is operated at an air-fuel ratio leaner than about 18:

1.

12. The method recited in claim 10 wherein said desired speed is a desired engine idle speed.

13. The method recited in claim 10 wherein said desired speed is a desired vehicle speed.

14. The method recited in claim 10 wherein said injected fuel is injected directly into a cylinder of the engine.

15. The method recited in claim 10 wherein said injected fuel is injected into an intake port of an engine manifold coupled to an engine cylinder.

16. A method for controlling a vehicle having an engine having first and second groups of combustion chambers, the method comprising:

controlling airflow to the first and second group of the engine via an electronically controlled throttle plate in an intake of said engine

during at least some operation in a speed control condition;

inducting air and injecting fuel into the first group of combustion chambers, inducting air and injecting substantially no fuel into the second group of combustion chambers, and adjusting said injected fuel to the first combustion chamber group and the throttle plate so that a determined speed approaches said desired speed and an air-fuel ratio is controlled within a preselected range; and

;

during at least some operation in a preselected condition other than said speed control condition;

determining a desired engine output torque based on a driver actuated element and adjusting at least one of fuel injected or air inducted to both cylinder groups based on said desired engine output torque.

17. The method recited in claim 16 wherein said injected fuel is injected directly into a cylinder of the engine.