COORDINATION OF VARIABLE CAM TIMING AND VARIABLE DISPLACEMENT ENGINE SYSTEMS

• US 20100211297A1
• Filed: 02/17/2009
• Published: 08/19/2010
• Est. Priority Date: 02/17/2009
• Status: Active Grant

• Current Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Original Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Inventors: Rollinger, John Eric, Doering, Jeffrey Allen
• Granted Patent: US 8,150,605 B2
• Time in Patent Office: Days
• US Class Current: 701/112
• CPC Class Codes: F02D 13/06 Cutting-out cylinders
• CPC Class Codes: F02D 2041/001 for engines with variable valve actuation
• CPC Class Codes: F02D 2250/21 during a transition between engine operation modes or states
• CPC Class Codes: F02D 37/02 one of the functions being ignition
• CPC Class Codes: F02D 41/0087 Selective cylinder activation, i.e. partial cylinder operation deceleration cut-off F02D41/123
• CPC Class Codes: Y02T 10/12 Improving ICE efficiencies

Abstract

Systems and methods are provided for operating an internal combustion engine including a variable cam timing (VCT) mechanism in cooperation with a plurality of deactivatable cylinders, each cylinder with a plurality of cylinder valves. One example method comprises, operating at a first cylinder valve timing before a transition of reactivating deactivated cylinders, and, before the transition, advancing cylinder valve timing from the first valve timing, where after the transition the cylinder valve timing remains at a second valve timing, the second valve timing advanced relative to the first valve timing.

Claims

1. A method of operating an internal combustion engine including a variable cam timing (VCT) mechanism in cooperation with a plurality of deactivatable cylinders, each cylinder with a plurality of cylinder valves, the method comprising,

operating at a first cylinder valve timing before a transition of reactivating deactivated cylinders;

and

before the transition, advancing cylinder valve timing from the first valve timing, where after the transition the cylinder valve timing remains at a second valve timing, the second valve timing advanced relative to the first valve timing.

2. The method of claim 1 further comprising, compensating torque disturbances caused by the advancing of cylinder valve timing.

3. The method of claim 2 wherein compensating torque disturbances includes compensating with spark timing adjustments.

4. The method of claim 1 wherein the first valve timing and the second valve timing are retarded from a nominal valve timing, the second valve timing less retarded than the first valve timing, and where an amount of retard of the second valve timing is based on a combustion stability limit in the reactivated condition.

5. The method of claim 4 wherein the reactivated condition is a full cylinder activation condition.

6. A system, comprising:

an engine having a plurality of cylinders, each cylinder with a plurality of cylinder valves;

a deactivation mechanism for deactivating at least one cylinder valve;

a variable cam timing mechanism for adjusting a timing of at least one cylinder valve;

a control system configured to,

operate the engine at a first cylinder valve timing before and after a first transition that changes the number of active cylinders to maintain a desired engine torque when the first cylinder valve timing after the transition is within a combustion stability valve timing limit; and

operate the engine at a second, less retarded, cylinder valve timing before and after a second transition when the first cylinder valve timing after the transition is outside the combustion stability valve timing limit.

7. The system of claim 6 wherein the control system is further configured to compensate torque disturbances caused by the second cylinder valve timing.

8. The system of claim 7 wherein torque disturbance compensation includes spark timing adjustments.

9. The system of claim 6 wherein the transition is a transition of reactivating deactivated cylinders, and the second cylinder valve timing is advanced relative to the first cylinder valve timing.

10. The system of claim 6 wherein the combustion stability valve timing limit is based on engine load.

11. The system of claim 6 wherein the combustion stability valve timing limit is based on atmospheric pressure.

12. The system of claim 9 wherein the combustion stability valve timing limit limits cam timing retard of a dual equal variable cam timing system.

13. The system of claim 12 wherein the first and second transitions each occur under similar speed and load conditions, but at different temperatures.

14. The system of claim 12 wherein the first and second transitions each occur under similar speed and load conditions, but at different barometric pressures.

15. A method of operating an internal combustion engine having a variable cam timing (VCT) mechanism in cooperation with a plurality of deactivatable cylinders, each cylinder with a plurality of cylinder valves, the method comprising,

during a first transition, adjusting cylinder valve timing within a first range to maintain engine torque during and after the transition;

and

during a second transition, limiting the cylinder valve timing adjustment to be within a second, more limited range, the second range limited by at least a combustion stability valve timing limit after the transition, adjusting cylinder valve timing within the limits during and after the transition, and compensating torque disturbances caused by the limited valve timing adjustment.

16. The method of claim 15 wherein compensating torque disturbances includes compensating with spark timing adjustments.

17. The method of claim 15 wherein the first and second transitions each include activating deactivated cylinders.

18. The method of claim 15 wherein the first and second transitions occur under similar engine load, but at different intake air temperatures.

19. The method of claim 15 wherein the first and second transitions occur under similar engine speed and load, but at different barometric pressures.