Method and system for operating variable displacement internal combustion engine

• US 6,499,449 B2
• Filed: 01/25/2001
• Issued: 12/31/2002
• Est. Priority Date: 01/25/2001
• Status: Active Grant

• Current Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Original Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Inventors: Okubo, Shunsuke, Michelini, John Ottavio, Cooper, Stephen Lee
• Primary Examiner(s): Denion, Thomas
• Assistant Examiner(s): CORRIGAN, JAIME W
• Application Number:
  US09/769,156
• Publication Number:
  US 20020096134A1
• Time in Patent Office: 705 Days
• Field of Search: 123/90.15, 123/90.16, 123/90.17, 123/90.18, 123/481, 123/198.F, 123/406.23, 123/399, 123/361, 123/436, 701/110, 701/115
• US Class Current: 123/90.15
• CPC Class Codes: F02D 13/0234 changing the valve timing only
• CPC Class Codes: F02D 2041/001 for engines with variable valve actuation
• CPC Class Codes: F02D 2041/002 by simultaneous control of throttle and 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

Abstract

A method of operating an internal combustion engine having a variable cam timing mechanism in cooperation with a plurality of deactivatable cylinders and corresponding intake valves includes the steps of scheduling a transition mode of the engine, determining a desired engine torque during the transition mode, determining a VCT phase angle based on the desired engine torque and operating the variable cam timing mechanism in accordance with the VCT phase angle to provide the desired engine torque during the transition mode.

Claims

1. A method of operating an internal combustion engine having a variable cam timing (VCT) mechanism in cooperation with a plurality of deactivatable cylinders and corresponding intake valves, comprising:

scheduling a transition mode of the engine from a first cylinder mode to a second cylinder mode;

determining a desired engine torque during the transition mode;

determining a VCT phase angle based on the desired engine torque;

operating the VCT mechanism in accordance with the VCT phase angle to provide the desired engine torque during the transition mode; and

limiting one or both of a rate of change of the VCT phase angle and a magnitude of the VCT phase angle.

2. The method according to claim 1, wherein said step of determining the desired engine torque comprises the step of determining a desired cylinder air charge required to produce the desired engine torque.

3. The method according to claim 2, wherein the VCT phase angle is a function of the cylinder air charge.

4. The method according to claim 1, further comprising. the step of applying a spark retard to provide the desired cylinder air charge during the transition mode.

5. An article of manufacture for operating an internal combustion engine having an intake manifold, an electronic throttle, an ignition system and a variable cam timing mechanism in cooperation with a plurality of deactivatable cylinders, the article of manufacture comprising:

a computer usable medium; and

a computer readable program code embodied in the computer usable medium for directing a computer to control the steps of scheduling a transition mode of the engine, determining a desired engine torque during the transition mode, determining a VCT phase angle based on the desired engine torque, operating the VCT mechanism in accordance with the VCT phase angle to provide the desired engine torque during the transition mode, and limiting one or both of a rate of change of the VCT phase angle and a magnitude of the VCT phase angle.

6. A method of transitioning operation of a variable displacement internal combustion engine from a first cylinder mode to a second cylinder mode, the engine having an electronic throttle, an ignition system and a variable cam timing (VCT) mechanism in cooperation with a plurality of deactivatable cylinders and corresponding intake valves, the method comprising;

scheduling a transition from the first cylinder mode to the second cylinder mode;

determining a cylinder air charge required to produce a desired engine torque output during the transition;

operating the electronic throttle to provide the desired cylinder air charge during the scheduled transition;

determining a VCT phase angle, based on the desired cylinder air charge, required to maintain the desired engine torque output during the transition; and

applying the VCT phase angle to the VCT to maintain the desired engine torque output during the transition.

7. The method according to claim 6, further comprising the steps of:

determining an actual engine torque output based at least in part on the applied VCT phase angle;

determining a torque adjustment equal to the difference between the desired engine torque output and the actual engine torque output;

operating the ignition system as required to provide the torque adjustment.

8. The method according to claim 6, further comprising the step of limiting a rate of change of the VCT phase angle.

9. The method according to claim 6, further comprising the step of limiting a magnitude of the VCT phase angle.

10. A system for operating an internal combustion engine having an intake manifold, an electronic throttle, an ignition system and a variable cam timing mechanism in cooperation with a plurality of deactivatable cylinders, the system comprising:

at least one sensor for providing signals indicative of engine manifold absolute pressure (MAP); and

a controller coupled to the sensor for receiving a signal from the MAP sensor, said controller comprising;

means for scheduling a transition mode of the engine;

means for determining a desired engine torque during the transition mode;

means for determining a VCT phase angle based on the desired engine torque; and

means for operating the VCT mechanism in accordance with the VCT phase angle to provide the desired engine torque during the transition mode.

11. The system according to claim 10, wherein said controller further comprises means for limiting a rate of change of the VCT phase angle.

12. The system according to claim 10, wherein said controller further comprises means for limiting a magnitude of the VCT phase angle.

13. The system according to claim 10, wherein said controller further comprises:

means for determining an actual engine torque output based at least in part on the applied VCT phase angle;

means for determining a torque adjustment equal to the difference between the desired engine torque output and the actual engine torque output;

means for operating the ignition system as required to provide the torque adjustment.

14. The system according to claim 10, wherein the VCT phase angle is a function of cylinder air charge.

15. The system according to claim 14, wherein the said function is a third-order polynomial having coefficients dependent on engine speed and MAP.