Vehicle Launch Using a Transmission Input Clutch

• US 20090186743A1
• Filed: 01/17/2008
• Published: 07/23/2009
• Est. Priority Date: 01/17/2008
• Status: Active Grant

• Current Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Original Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Inventors: Jiang, Hong, Hrovat, Davor D., Oldknow, Ian, Asgari, Jahan, Fodor, Michael G.
• Granted Patent: US 7,998,026 B2
• Time in Patent Office: Days
• US Class Current: 477/86
• CPC Class Codes: B60W 10/02 including control of driveline clutches
• CPC Class Codes: B60W 30/18027 Drive off, accelerating from standstill
• CPC Class Codes: F16D 2500/30406 Clutch slip
• CPC Class Codes: F16D 2500/30421 Torque of the output shaft
• CPC Class Codes: F16D 2500/3144 Accelerator pedal position
• CPC Class Codes: F16D 2500/50287 Torque control
• CPC Class Codes: F16D 2500/7044 Output shaft torque
• CPC Class Codes: F16D 2500/70605 Adaptive correction; Modifying control system parameters, e.g. gains, constants, look-up tables
• CPC Class Codes: F16D 2500/7082 of the clutch
• CPC Class Codes: F16D 48/06 Control by electric or electronic means, e.g. of fluid pressure

Abstract

A method for controlling a transmission input clutch during a vehicle launch includes selecting a subject device that transmits torque between an input and an output, a providing a mathematical model of the subject device, such that the model employing only static relationships of engine speed and transmission input speed to a desired magnitude of torque produced by the subject device, using the model, the current engine speed and the current engine speed to determine the desired torque produced by the subject device, and adjusting the torque capacity of the clutch to the desired torque of the subject device determined from the model.

Claims

1. In a vehicle powertrain that includes an engine, a transmission and a clutch that transmits torque between the engine and a transmission input, a method for controlling a transmission input clutch during a vehicle launch comprising the steps of:

(a) selecting a subject device that transmits torque between an input and an output;

(b) a providing a first model of the subject device, such that the model employing only static relationships of engine speed and transmission input speed to a desired magnitude of torque produced by the subject device;

(c) using the first model, the current engine speed, and the current transmission input speed to determine the desired torque produced by the subject device; and

(d) adjusting the torque capacity of the clutch to the desired torque of the subject device determined from the model.

2. The method of claim 1 wherein the subject device is selected based on accelerator pedal position.

3. The method of claim 1 wherein the method further comprises the step of:

preventing an increase in the torque capacity of the clutch, if an accelerator pedal position is decreasing.

4. The method of claim 1 wherein step (b) further comprises:

including in the model the relation T_desired=k(N_eng−

N_trans) wherein T_desired is the desired torque produced by the subject device, N_eng is engine speed, N_trans is transmission input shaft speed, and k is an adjustable proportionality constant.

5. The method of claim 1 wherein step (b) further comprises:

including in the model the relations T_desired=[N_eng/R]² and R=fn[N_eng/N_trans] wherein T_desired is the desired torque produced by the subject device, N_eng is engine speed, N_trans is transmission input shaft speed, and R is a capacity factor of the selected device.

6. The method of claim 1 wherein step (a) further includes selecting one of a viscous damper and a fluid coupler.

7. The method of claim 1 further comprising the steps of:

providing a supervisory controller that includes a second model for producing an ideal engine speed during the vehicle launch,

determining an engine speed error by comparing the ideal engine speed and the actual engine speed;

using the engine speed error to correct the desired clutch torque produced by the first model toward an ideal clutch torque produced by the supervisory controller.

8. The method of claim 1 wherein step (b) further comprises:

providing a first model that produces a desired torque produced by the selected device in response to engine speed, and that is unresponsive to an engine speed error with respect to an engine speed target.

9. In a vehicle powertrain that includes an engine, a transmission and a clutch that transmits torque between the engine and a transmission input, a method for controlling a transmission input clutch during a vehicle launch comprising the steps of:

(a) selecting a subject device that transmits torque between an input and an output;

(b) a providing a first model of the subject device, such that the model employing only static relationships of engine speed and transmission input speed to a desired magnitude of torque produced by the subject device;

(c) providing a supervisory controller that includes a second model for producing an ideal clutch torque response during the vehicle launch;

(d) using the first model to determine the desired torque produced by the subject device; and

(e) using the second model to correct the desired clutch torque produced by the model toward the ideal clutch torque response produced by the supervisory controller.

10. The method of claim 9 wherein the method further comprises the step of:

preventing an increase in the torque capacity of the clutch, if an accelerator pedal position is decreasing.

11. The method of claim 9 wherein step (b) further comprises:

including in the model the relation T_desired=k(N_eng−

N_trans) wherein T_desired is the desired torque produced by the subject device, N_eng is engine speed, N_trans is transmission input shaft speed, and k is an adjustable proportionality constant.

12. The method of claim 9 wherein step (b) further comprises:

including in the model the relations T_desired=[N_eng/R]² and R=fn[N_eng/N_trans] wherein T_desired is the desired torque produced by the subject device, N_eng is engine speed, N_trans is transmission input shaft speed, and R is a capacity factor of the selected device.

13. The method of claim 9 wherein step (a) further includes selecting one of a viscous damper and a fluid coupler.

14. The method of claim 9 wherein step (e) further comprises the steps of:

providing a supervisory controller that includes a second model for producing an ideal engine speed during the vehicle launch,

determining an engine seed error by comparing the ideal engine speed and the actual engine speed; and

using the engine speed error to correct the desired clutch torque produced by the model toward an ideal clutch torque produced by the supervisory controller.

15. The method of claim 9 wherein step (b) further comprises:

providing a first model that produces a desired torque produced by the selected device in response to engine speed, and that is unresponsive to an engine speed error with respect to an engine speed target.