Variable displacement engine control for fast catalyst light-off

• US 6,389,806 B1
• Filed: 12/07/2000
• Issued: 05/21/2002
• Est. Priority Date: 12/07/2000
• Status: Expired due to Term

• Current Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Original Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Inventors: Michelini, John Ottavio, Glugla, Christopher P.
• Primary Examiner(s): Denion, Thomas
• Assistant Examiner(s): NGUYEN, TU MINH
• Application Number:
  US09/732,347
• Publication Number:
  US 20020069638A1
• Time in Patent Office: 530 Days
• Field of Search: 602/74, 602/76, 602/84, 602/85, 602/86, 123/692, 123/697
• US Class Current: 60/284
• CPC Class Codes: F01N 13/009 having two or more separate purifying devices arranged in series
• CPC Class Codes: F01N 13/011 having two or more purifying devices arranged in parallel
• CPC Class Codes: F01N 13/107 More than one exhaust manifold or exhaust collector
• CPC Class Codes: F01N 2430/02 by cutting out a part of engine cylinders
• CPC Class Codes: F01N 2430/06 by varying fuel-air ratio, e.g. by enriching fuel-air mixture
• CPC Class Codes: F01N 2430/08 by modifying ignition or injection timing
• CPC Class Codes: F01N 3/20 specially adapted for catalytic conversion F01N3/22 takes precedence; Methods of operation or control of catalytic converters
• CPC Class Codes: F02B 2075/184 ten
• CPC Class Codes: F02B 75/22 with cylinders in V, fan, or star arrangement
• CPC Class Codes: F02D 17/02 Cutting-out cutting-out engines in multiple engine arrangements F02D25/04
• CPC Class Codes: F02D 41/0087 Selective cylinder activation, i.e. partial cylinder operation deceleration cut-off F02D41/123
• CPC Class Codes: F02D 41/024 to increase temperature of the exhaust gas treating apparatus
• CPC Class Codes: F02D 41/1443 with one sensor per cylinder or group of cylinders
• CPC Class Codes: Y02A 50/20 Air quality improvement or preservation, e.g. vehicle emission control or emission reduction by using catalytic converters
• CPC Class Codes: Y02T 10/12 Improving ICE efficiencies

Abstract

A system and method for controlling a variable displacement engine include starting the engine with at least one bank of cylinders deactivated to increase load on at least one other bank of activated cylinders and reduce time required for an engine and/or vehicle component to reach a desired operating temperature. In one embodiment, ignition timing or spark is retarded and air/fuel ratio is biased lean for the activated cylinder bank during and shortly after starting to further reduce the time required for catalyst light off and closed loop operation. During activation of a deactivated bank of cylinders, air/fuel ratio of one or more activated cylinders is biased rich with air/fuel ratio of the deactivated cylinders biased lean. In addition, spark is retarded during activation of the deactivated cylinders to reduce the time necessary for components associated with the deactivated cylinders to reach desired operating temperatures.

Claims

1. A method for controlling an internal combustion engine having a plurality of cylinders, at least some of which are selectively deactivated in a variable displacement operating mode, the method comprising:

controlling the engine during starting to deactivate at least one cylinder; and

biasing air/fuel ratio lean relative to stoichiometry for the activated cylinders until an exhaust gas oxygen sensor reaches a desired operating temperature for closed loop control of the engine.

3. The method of claim 1 wherein the steps of controlling and biasing are performed until a catalyst reaches light-off temperature.

2. A method for controlling an internal combustion engine having a plurality of cylinders, at least some of which are selectively deactivated in a variable displacement operating mode, the method comprising:

controlling the engine during starting to deactivate at least one cylinder;

retarding ignition timing for the activated cylinders; and

biasing air/fuel ratio lean relative to stoichiometry for the activated cylinders to reduce time required for at least one engine component to reach a desired operating temperature.

4. A method for controlling an internal combustion engine having a plurality of cylinders, at least some of which are selectively deactivated in a variable displacement operating mode, the method comprising:

controlling the engine during starting to deactivate at least one cylinder;

biasing air/fuel ratio lean relative to stoichiometry for the activated cylinders; and

biasing air/fuel ratio lean for at least one deactivated cylinder and

biasing air/fuel ratio rich relative to a stoichiometry for the activated cylinders during activation after at least one emission control device associated with the activated cylinders has reached a desired operating temperature.

5. A method for controlling an internal combustion engine having a plurality of cylinders, at least some of which are selectively deactivated in a variable displacement operating mode, the method comprising:

deactivating at least one cylinder during starting;

biasing air/fuel ratio lean relative to stoichiometry for the activated cylinders;

activating the deactivated cylinders and controlling air/fuel ratio to the cylinders during activation to provide a lean air/fuel ratio; and

controlling air/fuel ratio for a corresponding number of activated cylinders during activation of the deactivated cylinders to provide a rich air/fuel ratio.

6. The method of claim 5 further comprising retarding ignition timing for the at least one deactivated cylinder during activation.

7. A method for controlling a variable displacement internal combustion engine having cylinders grouped into first and second banks with associated separate first and second upstream emission control devices and first and second exhaust gas oxygen sensors and at least a third downstream emission control device, at least one bank being selectively activated and deactivated to provide variable displacement, the method comprising:

deactivating the second bank during and after starting until the first emission control device and first exhaust gas oxygen sensor reach associated desired operating temperatures.

8. The method of claim 7 further comprising retarding ignition timing for the first bank during and after starting.

9. The method of claim 7 further comprising biasing air/fuel ratio lean for the first bank during and after starting.

10. The method of claim 7 wherein the third downstream emission control device is a shared emission control device positioned downstream of both upstream emission control devices.

11. The method of claim 7 further comprising:

activating the second bank after the first emission control device and first exhaust gas oxygen sensor reach associated desired operating temperatures until the second emission control device and second exhaust gas oxygen sensor reach associated desired operating temperatures.

12. The method of claim 11 further comprising:

biasing air/fuel ratio rich for the first bank and lean for the second bank until the second emission control device and second exhaust gas oxygen sensor reach associated desired operating temperatures.

13. The method of claim 11 further comprising:

retarding ignition timing for the second bank until the second emission control device and second exhaust gas oxygen sensor reach associated desired operating temperatures.

14. A system for controlling an internal combustion engine having at least first and second cylinder banks, at least one of which is selectively deactivated in a variable displacement operating mode, the system comprising:

first and second upstream emission control devices;

first and second exhaust gas oxygen sensors having associated heaters and positioned downstream relative to the first and second upstream emission control devices, respectively;

at least a third emission control device positioned downstream relative to at least one of the first and second upstream emission control devices; and

an engine controller for deactivating the first bank after starting the engine until the second upstream emission control device and the second exhaust gas oxygen sensor have attained minimum desired operating temperatures.

15. The system of claim 14 wherein the controller retards ignition timing for the second bank during and after starting.

16. The system of claim 14 wherein the controller biases air/fuel ratio lean for the second bank during and after starting.

17. The system of claim 14 wherein the controller:

activates the first bank after the second emission control device and second exhaust gas oxygen sensor reach associated desired operating temperatures until the first emission control device and first exhaust gas oxygen sensor reach associated desired operating temperatures.

18. The system of claim 14 wherein the controller activates the first bank after the second upstream emission control device and the second exhaust gas oxygen sensor have attained minimum desired operating temperatures, and biases air/fuel ratio rich for the second bank and lean for the first bank until the first emission control device and first exhaust gas oxygen sensor reach associated desired operating temperatures.

19. The system of claim 18 wherein the controller retards ignition timing for the first bank until the first emission control device and first exhaust gas oxygen sensor reach associated desired operating temperatures.

20. A computer readable storage medium having stored data representing instructions executable by a computer to control a variable displacement internal combustion engine having cylinders grouped into first and second banks with associated separate first and second upstream emission control devices and first and second exhaust gas oxygen sensors and at least a third downstream emission control device, at least one bank being selectively activated and deactivated to provide variable displacement, the computer readable storage medium comprising:

instructions for deactivating the first bank after starting the engine until the second upstream emission control device and the second exhaust gas oxygen sensor have attained minimum desired operating temperatures.

21. The computer readable storage medium of claim 20 further comprising instructions for retarding ignition timing for the second bank during and after starting.

22. The computer readable storage medium of claim 20 further comprising instructions for biasing air/fuel ratio lean for the second bank during and after starting.

23. The computer readable storage medium of claim 20 further comprising:

instructions for activating the first bank after the second emission control device and second exhaust gas oxygen sensor reach associated desired operating temperatures until the first emission control device and first exhaust gas oxygen sensor reach associated desired operating temperatures.

24. The computer readable storage medium of claim 21 further comprising:

instructions for activating the first bank after the second upstream emission control device and the second exhaust gas oxygen sensor have attained minimum desired operating temperatures and biasing air/fuel ratio rich for the second bank and lean for the first bank until the first emission control device and first exhaust gas oxygen sensor reach associated desired operating temperatures.

25. The computer readable storage medium of claim 24 further comprising:

instructions for retarding ignition timing for the first bank until the first emission control device and first exhaust gas oxygen sensor reach associated desired operating temperatures.