Methods and Systems for Variable Displacement Engine Control

• US 20120285161A1
• Filed: 05/12/2011
• Published: 11/15/2012
• Est. Priority Date: 05/12/2011
• Status: Active Grant

• Current Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Original Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Inventors: Kerns, James Michael, Uhrich, Michael James, Smith, Stephen B., Banker, Adam Nathan
• Granted Patent: US 8,919,097 B2
• Time in Patent Office: Days
• US Class Current: 60/598
• 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: F02B 37/00 Engines characterised by provision of pumps driven at least for part of the time by exhaust
• CPC Class Codes: F02D 2200/0802 Temperature of the exhaust gas treatment apparatus
• CPC Class Codes: F02D 35/027 using knock sensors
• CPC Class Codes: F02D 41/0087 Selective cylinder activation, i.e. partial cylinder operation deceleration cut-off F02D41/123
• CPC Class Codes: F02D 41/027 to purge or regenerate the exhaust gas treating apparatus
• CPC Class Codes: F02P 5/152 dependent on pinking detecting or indicating knocks in internal-combustion engines G01L23/22
• CPC Class Codes: Y02T 10/40 Engine management systems

Abstract

Methods and systems are provided for selecting a group of cylinders for selective deactivation, in a variable displacement engine system, based at least on a regeneration state of an exhaust catalyst. The position of one or more valves and throttles may be adjusted based on the selective deactivation to reduce back-flow through the disabled cylinders while also maintaining conditions of a downstream exhaust catalyst. Pre-ignition and knock detection windows and thresholds may also be adjusted based on the deactivation to improve the efficiency of knock and pre-ignition detection.

Claims

1. A method of operating a boosted engine with selectively deactivatable cylinders, comprising:

adjusting a window and a threshold for pre-ignition detection based on a number of deactivated cylinders.

2. The method of claim 1, wherein the adjustment includes widening the window as the number of deactivated cylinders increases.

3. The method of claim 2, wherein the adjustment further includes increasing the threshold as the number of deactivated cylinders increases.

4. The method of claim 1, further comprising, adjusting a window and a threshold for knock detection based on the number of deactivated cylinders.

5. The method of claim 4, wherein the window for knock detection and the window for pre-ignition detection are partially overlapping, and wherein an amount of overlap between the windows is increased as the number of deactivated cylinders increases.

6. The method of claim 1, wherein the engine includes a first group of cylinders coupled to a first catalyst and a second group of cylinders coupled to a second catalyst, and wherein the number of deactivated cylinders is based on a regeneration state of the first catalyst relative to the second catalyst.

7. The method of claim 6, wherein the number of deactivated cylinders is further based on a temperature of the first catalyst relative to the second catalyst.

8. A method of operating a boosted engine, comprising:

selecting one of a first and a second group of cylinders for deactivation based on a regeneration state of a first catalyst relative to a second catalyst;

deactivating one or more cylinders of the selected group of cylinders; and

adjusting a window and a threshold for each of knock and pre-ignition detection in the engine based on a number of deactivated cylinders.

9. The method of claim 8, wherein the deactivation includes turning off fuel injectors and continuing to open or close intake and exhaust valves to pump air through the selected group of cylinders.

10. The method of claim 8, wherein the selection includes, selecting the first group of cylinders if the first catalyst is less regenerated than the second catalyst, and selecting the second group of cylinders if the second catalyst is less regenerated than the first catalyst.

11. The method of claim 8, wherein the adjustment includes, increasing the window for each of knock and pre-ignition as the number of deactivated cylinders increases.

12. The method of claim 11, wherein the window for knock partially overlaps the window for pre-ignition, and wherein increasing the window for each of knock and pre-ignition includes increasing an overlap between the window for knock and the window for pre-ignition.

13. The method of claim 11, wherein the adjustment further includes, increasing the threshold for each of knock and pre-ignition as the number of deactivated cylinders increases.

14. The method of claim 8, wherein the window for pre-ignition and the window for knock are crank angle windows.

15. An engine system, comprising,

an engine;

a turbocharger configured to provide a boosted intake aircharge to the engine;

a first group of cylinders coupled to a first catalyst;

a second group of cylinders coupled to a second catalyst;

one or more knock sensors; and

a control system with computer readable instructions for,

selecting one of the first or the second group of cylinders for deactivation based on an operating condition of the first catalyst relative to the second catalyst;

estimating an output of the one or more knock sensors relative to a first knock threshold in a first knock window, and relative to a second pre-ignition threshold in a second pre-ignition window, the first and second windows and the first and second thresholds adjusted based on the deactivation; and

indicating cylinder knock and/or pre-ignition based on the estimation.

16. The system of claim 15, wherein the selection includes, selecting the first group of cylinders for deactivation when the first catalyst is less regenerated than the second catalyst, and selecting the second group of cylinders for deactivation when the second catalyst is less regenerated than the first catalyst.

17. The system of claim 16, wherein the deactivation includes, turning off fuel injectors while continuing valve operation of one or more cylinders in the selected group of cylinders.

18. The system of claim 17, wherein the adjustment includes, widening the first and second windows while increasing the first and second thresholds as a number of deactivated cylinders increases.

19. The system of claim 17, wherein the one or more knock sensors include a first knock sensor coupled to the first group of cylinders and a second knock sensor coupled to the second group of cylinders, and wherein the adjustment includes,

adjusting the first and second thresholds based on an output of the first knock sensor but not the second knock sensor when the second group of cylinders is deactivated, and based on an output of the second knock sensor but not the first knock sensor when the first group of cylinders is deactivated.

20. The system of claim 17, wherein the adjustment includes,

adjusting the first and second thresholds based on an average output of the first and second knock sensor when neither group of cylinders are deactivated.