Claims
- 1. A variable cam timing (VCT) control system used in an internal combustion engine, said system having a dual dependent cam shaft configuration, wherein an intake cam shaft is dependent upon an exhaust cam shaft, comprising:
a) an exhaust phaser engaging said exhaust cam shaft; b) an intake phaser engaging said intake cam shaft, the movement of said intake cam shaft being dependent upon the movement of said exhaust cam shaft; c) a first feedback loop for correcting errors relating to the intake phaser, said first feedback loop including a measured intake phase signal, being used to compare with a local intake set point and being used to generate an error signal used by the first feedback loop; and d) a second feedback loop for correcting errors relating to the exhaust phaser, said second feedback loop including a measured exhaust phase signal.
- 2. The system of claim 1, wherein the error signal is used by a control law to generate a first control signal.
- 3. The system of claim 2, wherein said measured exhaust phase signal is used to compare with an exhaust setpoint and generate said error signal that is used by said control law to generate said second control signal.
- 4. The system of claim 3, wherein said second control signal is also used to compare with said global intake set point to generate said local intake setpoint.
- 5. The system of claim 1 further comprising a controller for controlling inputs to both the first feedback loop and the second feedback loop.
- 6. The system of claim 1 further comprising a crankshaft coupled with said exhaust cam shaft.
- 7. The system of claim 6 further 1 further comprising coupling means for coupling said exhaust cam shaft to said crank shaft.
- 8. The system of claim 1 further comprising coupling means for coupling said exhaust cam shaft to said intake cam shaft.
- 9. In a variable cam timing (VCT) control system used in an internal combustion engine, said system having a dual dependent cam shaft configuration, wherein an intake cam shaft is dependent upon an exhaust cam shaft, a method comprising the steps of:
providing an exhaust phaser engaging said exhaust cam shaft; providing an intake phaser engaging said intake cam shaft, the movement of said intake cam shaft being dependent upon the movement of said exhaust cam shaft; providing a first feedback loop for correcting errors relating to the intake phaser, said first feedback loop including a measured intake phase signal, being used to compare with a local intake set point and being used to generate an error signal used by the first feedback loop; providing a second feedback loop for correcting errors relating to the exhaust phaser, said second feedback loop including a measured exhaust phase signal; and using said measured exhaust phase signal, correcting both a global intake set point and an exhaust set point, thereby providing a more accurate correction to said dual dependent variable cam timing system.
- 10. The system of claim 9, wherein the error signal is used by a control law to generate a first control signal.
- 11. The system of claim 10, wherein said measured exhaust phase signal is used to compare with an exhaust setpoint and generate said error signal that is used by said control law to generate said second control signal.
- 12. The system of claim 11, wherein said second control signal is also used to compare with said global intake set point to generate said local intake setpoint.
- 13. The method of claim 9 further comprising controlling inputs to both the first feedback loop and the second feedback loop using a controller.
- 14. The method of claim 9 further comprising coupling said exhaust cam shaft with a crank shaft.
- 15. The method of claim 9 further comprising coupling said exhaust cam shaft with said intake cam shaft.
REFERENCE TO RELATED APPLICATIONS
[0001] This application claims an invention which was disclosed in Provisional Application No. 60/389,187, filed Jun. 17, 2002, entitled “CONTROL METHOD FOR DUAL DEPENDENT VARIABLE CAM TIMING SYSTEM”. The benefit under 35 USC §119(e) of the United States provisional application is hereby claimed, and the aforementioned application is hereby incorporated herein by reference.
Provisional Applications (1)
|
Number |
Date |
Country |
|
60389187 |
Jun 2002 |
US |