MULTI-PHASE ENGINE STOP POSITION CONTROL

• US 20110253099A1
• Filed: 04/14/2010
• Published: 10/20/2011
• Est. Priority Date: 04/14/2010
• Status: Active Grant

• Current Assignee: GM Global Technology Operations LLC (General Motors Company)
• Original Assignee: GM Global Technology Operations Incorporated (General Motors Company)
• Inventors: Han, Jun, Wang, Lan, Tamai, Goro
• Granted Patent: US 8,770,173 B2
• Time in Patent Office: Days
• US Class Current: 123/350
• CPC Class Codes: F02D 2041/0095 Synchronisation of the cylinders during engine shutdown
• CPC Class Codes: F02D 2200/101 Engine speed
• CPC Class Codes: F02D 41/0097 using means for generating speed signals
• CPC Class Codes: F02D 41/042 for stopping the engine
• CPC Class Codes: F02D 41/065 at hot start or restart F02D41/067 takes precedence
• CPC Class Codes: F02N 11/0814 comprising means for controlling automatic idle-start-stop
• CPC Class Codes: F02N 11/0818 Conditions for starting or stopping the engine or for deactivating the idle-start-stop mode
• CPC Class Codes: F02N 19/005 Aiding engine start by starting from a predetermined position, e.g. pre-positioning or reverse rotation
• CPC Class Codes: F02N 2019/008 the engine being stopped in a particular position

Abstract

A method is provided for controlling engine stop position in a vehicle having an engine with auto stop/auto start functionality. The method includes automatically ramping down engine speed upon initiation of an auto stop event, executing closed-loop speed control of the engine when the engine speed begins to ramp down, and for as long as the engine speed remains above a threshold engine speed while ramping down the engine speed; executing closed-loop position control of the engine while ramping down the engine speed once the engine speed is less than the threshold engine speed and greater than zero; and stopping the crankshaft to within a calibrated range of a targeted engine stop position. A controller is also provided that includes a hardware module and an algorithm adapted for executing the foregoing method, and a vehicle is provided having an engine with auto stop/start functionality and the controller noted above.

Claims

1. A method for controlling an engine stop position in a vehicle having an engine with auto stop/auto start functionality and a crankshaft, the method comprising:

automatically ramping down engine speed upon initiation of an auto stop event;

executing closed-loop speed control of the engine when the engine speed ramps down, and for as long as the engine speed remains above a threshold engine speed;

executing closed-loop position control of the engine while ramping down the engine speed when a predetermined condition is detected; and

stopping the crankshaft of the engine to within a calibrated range of a targeted engine stop position.

2. The method of claim 1, further comprising:

switching back to closed-loop speed control of the engine once the engine speed equals zero.

3. The method of claim 1, wherein the predetermined condition includes one of:

the engine speed being less than the threshold engine speed and greater than zero, and an engine profile position passing a calibrated trigger position.

4. The method of claim 1, further comprising:

calculating a changing angular value of the crankshaft; and

using the changing angular value of the engine as a closed-loop feedback variable during the closed-loop position control.

5. The method of claim 1, wherein the closed-loop controls are executed by a proportional-integral (PI) controller, the method further comprising:

setting an I-term of the PI controller as a function of at least a transmission state and vehicle speed upon transition from closed-loop speed control to closed-loop position control.

6. The method of claim 1, further comprising:

determining if a set of exit conditions is present when the engine is stopped; and

transitioning from closed-loop position control to closed-loop speed control only if the set of exit conditions is present.

7. A controller for use aboard a vehicle having an engine with a crankshaft and auto stop/auto start functionality, the controller comprising a hardware module and an algorithm adapted for controlling a cranking position of the engine during an auto stop event, wherein the algorithm is adapted for:

automatically ramping down engine speed upon initiation of an auto stop event;

executing closed-loop speed control of the engine when the engine speed begins to ramp down, and for as long as the engine speed remains above a threshold engine speed while ramping down the engine speed;

executing closed-loop position control of the engine while ramping down the engine speed when a predetermined condition is detected; and

stopping the crankshaft to within a calibrated range of a targeted engine stop position.

8. The controller of claim 7, wherein the algorithm is further adapted for switching back to closed-loop speed control of the engine once the engine speed equals zero.

9. The controller of claim 7, wherein the predetermined condition includes one of:

the engine speed being less than the threshold engine speed and greater than zero, and an engine profile position passing a calibrated trigger position.

10. The controller of claim 7, wherein the algorithm is further adapted for:

calculating a changing angular value of the crankshaft; and

using the changing angular value of the engine as a closed-loop feedback variable during the closed-loop position control.

11. The controller of claim 7, wherein the controller is configured as a proportional-integral (PI) controller, and wherein the algorithm is adapted for setting an I-term of the PI controller as a function of at least a transmission state and vehicle speed upon transition from closed-loop speed control to closed-loop position control.

12. The controller of claim 7, wherein the algorithm is further adapted for:

determining if a set of exit conditions is present when the engine is stopped; and

transitioning from closed-loop position control to closed-loop speed control only if the set of exit conditions is present.

13. A vehicle comprising:

an engine with a crankshaft and auto start/auto stop functionality; and

a controller adapted for controlling a cranking position of the engine during an auto stop event, wherein the algorithm is adapted for;

automatically ramping down engine speed upon initiation of an auto stop event;

executing closed-loop speed control of the engine when the engine speed begins to ramp down, and for as long as the engine speed remains above a threshold engine speed while ramping down the engine speed;

executing closed-loop position control of the engine while ramping down the engine speed when a predetermined condition is detected; and

stopping the crankshaft to within a calibrated range of a targeted engine stop position.

14. The vehicle of claim 14, wherein the algorithm is further adapted for switching back to closed-loop speed control of the engine once the engine speed equals zero.

15. The vehicle of claim 14, wherein the predetermined condition includes one of:

the engine speed being less than the threshold engine speed and greater than zero, and an engine profile position passing a calibrated trigger position.

16. The vehicle of claim 14, wherein the algorithm is further adapted for:

calculating a changing angular value of the crankshaft; and

using the changing angular value of the engine as a closed-loop feedback variable during the closed-loop position control.

17. The vehicle of claim 14, wherein the closed-loop controls are executed by a proportional-integral (PI) controller, the method further comprising:

setting an I-term of the PI controller as a function of at least a transmission state and vehicle speed upon transition from closed-loop speed control to closed-loop position control.

18. The vehicle of claim 14, wherein the algorithm is further adapted for:

determining if a set of exit conditions is present when the engine is stopped; and

transitioning from closed-loop position control to closed-loop speed control only if the set of exit conditions is present.