System and method for detecting vehicle clutch touch point

• US 9,381,912 B2
• Filed: 03/26/2015
• Issued: 07/05/2016
• Est. Priority Date: 03/13/2013
• Status: Active Grant

• Current Assignee: Allison Transmission Incorporated (Allison Transmission Holdings Incorporated)
• Original Assignee: Allison Transmission Incorporated (Allison Transmission Holdings Incorporated)
• Inventors: West, Stephen T., Perry, Carl E.
• Primary Examiner(s): Badii, Behrang
• Assistant Examiner(s): TESTARDI, DAVID A
• Application Number:
  US14/669,099
• Publication Number:
  US 20150197245A1
• Time in Patent Office: 467 Days
• US Class Current: 1/1
• CPC Class Codes: B60K 2006/268 Electric drive motor starts the engine, i.e. used as starter motor
• CPC Class Codes: B60K 2006/4825 Electric machine connected or connectable to gearbox input shaft
• CPC Class Codes: B60K 6/387 Actuated clutches, i.e. clutches engaged or disengaged by electric, hydraulic or mechanical actuating means
• CPC Class Codes: B60K 6/40 characterised by the assembly or relative disposition of components
• CPC Class Codes: B60K 6/48 Parallel type
• CPC Class Codes: B60W 10/02 including control of driveline clutches
• CPC Class Codes: B60W 10/06 including control of combustion engines
• CPC Class Codes: B60W 10/08 including control of electric propulsion units, e.g. motors or generators
• CPC Class Codes: B60W 20/00 Control systems specially adapted for hybrid vehicles hybrid vehicle design, B60K6/00; electric vehicles B60L
• CPC Class Codes: B60W 20/40 Controlling the engagement or disengagement of prime movers, e.g. for transition between prime movers power-up or power-down of the driveline B60W30/192
• CPC Class Codes: B60W 2050/0011 Proportional Integral Differential [PID] controller
• CPC Class Codes: B60W 2050/0087 Resetting start and end points of actuator travel
• CPC Class Codes: B60W 2510/0216 Clutch engagement rate
• CPC Class Codes: B60W 2510/0275 Clutch torque
• CPC Class Codes: B60W 2510/083 Torque
• CPC Class Codes: B60W 2710/027 Clutch torque
• CPC Class Codes: B60W 2710/081 Speed
• CPC Class Codes: B60W 2710/083 Torque
• CPC Class Codes: B60W 50/045 Monitoring control system parameters
• CPC Class Codes: F02N 11/0851 characterised by means for controlling the engagement or disengagement between engine and starter, e.g. meshing of pinion and engine gear
• CPC Class Codes: F16D 2500/1066 : Hybrid
• CPC Class Codes: F16D 2500/50245 : Calibration or recalibration of the clutch touch-point
• CPC Class Codes: F16D 2500/50281 : Transmitted torque
• CPC Class Codes: F16D 2500/50883 : Stop-and-go, i.e. repeated stopping and starting, e.g. in traffic jams
• CPC Class Codes: F16D 2500/525 : Improve response of control system
• CPC Class Codes: F16D 2500/7027 : Engine speed
• CPC Class Codes: F16D 2500/7041 : Position
• CPC Class Codes: F16D 2500/70626 : PID control
• CPC Class Codes: F16D 48/06 : Control by electric or electronic means, e.g. of fluid pressure
• CPC Class Codes: Y02T 10/62 : Hybrid vehicles
• CPC Class Codes: Y10S 903/93 : Conjoint control of different elements

Abstract

A hybrid system and method is configured to achieve and maintain a touch point for a clutch so as to allow an engine to rapidly restart. The hybrid system includes an eMachine configured to start the engine. The clutch is configured to operatively connect and disconnect the eMachine and the engine. A motor torque PID controller is configured to operate the eMachine at a desired speed by regulating torque of the eMachine. A clutch pressure PID controller is configured to actuate the clutch to a touch point by regulating clutch pressure. The motor torque PID controller and the clutch pressure PID controller include a compensation function to account for a change in torque caused by actuation of the clutch by the clutch pressure PID controller.

Claims

1. A method, comprising:

controlling speed of an eMachine in a hybrid system to a desired speed with a motor torque PID controller that regulates torque of the eMachine, wherein the eMachine is operatively connected to an engine via a clutch;

actuating the clutch to a touch point by regulating clutch pressure with a clutch pressure PID controller;

adjusting the desired speed for the motor torque PID controller by a compensation function, wherein the compensation function changes the desired speed to account for a change in torque caused by said actuating the clutch; and

maintaining the clutch at the touch point with the clutch pressure PID controller before starting the engine.

2. The method of claim 1, further comprising:

issuing a command to open the clutch;

stabilizing the speed of the eMachine by said controlling the speed of the eMachine after said issuing;

confirming the clutch is open; and

achieving a motor speed droop by said adjusting.

3. The method of claim 1, further comprising:

closing the clutch after said actuating the clutch; and

restarting an engine with the eMachine after said closing the clutch.

4. The method of claim 1, wherein the motor torque PID controller and/or the clutch pressure PID controller include a PID controller that operates in accordance with the following equation:

5. The method of claim 1, wherein the motor torque PID controller incorporates an error function in accordance with the following equation:

e(n)=X_ref−

K_droopy_i−

X

where;

e=error;

X_ref=eMachine desired speed;

X=eMachine measured speed;

K_droopdroop tuning parameter; and

y_i=integral output value.

6. The method of claim 1, wherein the compensation function is a linear function of the speed and the torque of the eMachine.

7. The method of claim 1, wherein said adjusting the desired speed by the compensation function adjusts in accordance with the following equation:

X=X_ref−

K_droopy(n)

where;

X=eMachine measured speed;

X_ref=eMachine desired speed;

K_droop=droop tuning parameter; and

y(n)=eMachine motor torque.

8. The method of claim 1, wherein the clutch pressure PID controller incorporates an error function in accordance with the following equation:

e(n)=X_open−

C_refK_droop−

X

where;

e=error;

X_open=open clutch eMachine speed;

C_ref=desired clutch torque;

K_droop=droop tuning parameter; and

X=measured eMachine speed.

9. The method of claim 8, wherein the desired clutch torque is 25 Nm.

10. The method of claim 1, wherein the motor torque PID controller and/or the clutch pressure PID controller is a discrete PID controller.

11. The method of claim 1, wherein the clutch includes a hydraulic clutch.

12. The method of claim 1, wherein the touch point is where clutch plates in the clutch first contact one another.

13. A hybrid system, comprising:

an eMachine configured to start an engine;

a clutch configured to operatively connect and disconnect the eMachine and the engine;

a motor torque PID controller configured to operate the eMachine at a desired speed by regulating torque of the eMachine;

a clutch pressure PID controller configured to hold the clutch to a touch point while transmitting clutch torque by regulating clutch pressure before the engine needs to be restarted; and

wherein the motor torque PID controller and the clutch pressure PID controller include a compensation function, wherein the compensation function changes the desired speed to account for the transmitted clutch torque caused by actuation of the clutch by the clutch pressure PID controller.

14. The hybrid system of claim 13, further comprising:

one or more computers incorporating the motor torque PID controller and the clutch pressure PID controller.

15. The hybrid system of claim 14, wherein the one or more computers include a transmission/hybrid control module (TCM/HCM).

16. The hybrid system of claim 14, wherein the motor torque PID controller and the clutch pressure PID controller are in the form of software.

17. The hybrid system of claim 13, wherein the motor torque PID controller and/or the clutch pressure PID controller include a PID controller that operates in accordance with the following equation:

18. The hybrid system of claim 13, wherein the compensation function is a linear function of the speed and the torque of the eMachine.

19. The hybrid system of claim 13, wherein motor torque PID controller configured to make adjustments in accordance with the following equation:

X=X_ref−

K_droopy(n)

where;

X=eMachine measured speed;

X_ref=eMachine desired speed;

K_droop=droop tuning parameter; and

y(n)=eMachine motor torque.

20. The hybrid system of claim 13, wherein the clutch pressure PID controller incorporates an error function in accordance with the following equation:

e(n)=X_open−

C_refK_droop−

X

where;

e=error;

X_open=open clutch eMachine speed;

C_ref=desired clutch torque;

K_droop=droop tuning parameter; and

X=measured eMachine speed.

21. The hybrid system of claim 13, wherein the clutch includes a hydraulic clutch.

22. The hybrid system of claim 13, wherein the touch point is where clutch plates in the clutch first contact one another.

23. A method, comprising:

controlling speed of an eMachine in a hybrid system to a desired speed with a motor torque PID controller that regulates torque of the eMachine, wherein the eMachine is operatively connected to a clutch;

actuating the clutch to a touch point by regulating clutch pressure with a clutch pressure PID controller to achieve a motor speed droop set in accordance with a desired clutch torque;

adjusting the desired speed for the motor torque PID controller by a compensation function, wherein the compensation function changes the desired speed to account for a change in torque caused by said actuating the clutch; and

maintaining the clutch at the touch point with the clutch pressure PID controller.

24. The method of claim 23, further comprising:

issuing a command to open the clutch;

stabilizing the speed of the eMachine by said controlling the speed of the eMachine after said issuing;

confirming the clutch is open;

achieving a motor speed droop by said adjusting; and

maintaining the clutch at the touch point with the clutch pressure PID controller.

25. The method of claim 23, further comprising:

closing the clutch after said actuating the clutch; and

restarting an engine with the eMachine after said closing the clutch.

26. The method of claim 23, wherein the compensation function is a linear function of the speed and the torque of the eMachine.