Torque converter lockup clutch slip control

Patent metadata

Field	Value
Publication number	US-9739371-B1
Application number	US-201615182104-A
Country	US
Kind code	B1
Filing date	Jun 14, 2016
Priority date	Jun 14, 2016
Publication date	Aug 22, 2017
Grant date	Aug 22, 2017

Abstract

A method and system are provided for operating a lockup clutch of a torque converter of a motor vehicle. The torque converter includes a pump rotatably driven by a drive unit, a rotatable turbine fluidly coupled to the pump and configured to drive an input shaft of a transmission, and a lockup clutch selectively engageable to non-fluidically couple the pump to the turbine to transmit torque from the drive unit to the transmission. The operation of the lockup clutch is controlled by the system in response to detecting that the motor vehicle is coasting.

First claim

The invention claimed is:

1. A system for a vehicle, the system comprising:
a drive unit configured to output torque, the drive unit including an output shaft,
a transmission configured to transmit torque output by the drive unit to a load, the transmission including an input shaft,
a torque converter coupled between the drive unit and the transmission, the torque converter including a pump coupled to the output shaft of the drive unit, a turbine coupled to the input shaft of the transmission, a lockup clutch selectively engageable to mechanically couple the pump to the turbine to transmit torque between the drive unit and the transmission; and
a torque converter controller having a processor and memory, the memory having instructions stored therein that are executable by the processor to cause the processor to (i) determine whether the vehicle is in a coasting condition, (ii) determine whether a rotational speed of the output shaft of the drive unit has reached a target speed above a reference threshold, and (iii) engage the lockup clutch to maintain the rotational speed of the output shaft above the reference threshold in response to a determination that the motor vehicle is in the coasting condition and that the rotational speed of the output shaft has reached the target speed.

2. The system of claim 1 , wherein the reference threshold defines a rotational speed of the output shaft of the drive unit associated with idle operation of the drive unit, and wherein to engage the lockup clutch to maintain the rotational speed of the output shaft above the reference threshold comprises to control slip between the turbine and the pump to maintain the rotational speed of the output shaft above the reference threshold to avoid fuel consumption during idle operation of the drive unit.

3. The system of claim 1 , wherein to engage the lockup clutch comprises to engage the lockup clutch to transmit torque from the turbine to the pump.

4. The system of claim 3 , wherein to engage the lockup clutch comprises to partially engage the lockup clutch to achieve slip between the turbine and the pump characterized by a rotational speed of the turbine being greater than a rotational speed of the pump.

5. The system of claim 1 , wherein to engage the lockup clutch comprises to receive a signal indicative of a rotational speed of the turbine and determine a target torque output by the pump based on the target speed of the output shaft of the drive unit and the signal.

6. The system of claim 5 , wherein to engage the lockup clutch comprises to receive a torque signal indicative of torque associated with the drive unit.

7. The system of claim 6 , wherein to engage the lockup clutch comprises to calculate a lockup clutch torque based on the determined target torque output by the pump and the torque signal.

8. The system of claim 1 , wherein to determine whether the vehicle is in the coasting condition comprises to determine whether the vehicle is in the coasting condition based on (i) a road grade signal indicative of a grade of a surface in contact with the vehicle, (ii) a torque signal indicative of torque associated with the drive unit, (iii) an accelerator pedal signal indicative of depression of an accelerator pedal of the motor vehicle, (iv) a brake pedal signal indicative of depression of a brake pedal of the motor vehicle, and (v) a user input signal indicative of activity performed by a user.

9. A control system for a vehicle, the vehicle including a drive unit, a transmission, and a torque converter having a lockup clutch selectively engageable to mechanically couple a pump of the torque converter to a turbine of the torque converter, the control system comprising:
a plurality of sensors configured to produce sensor data, wherein the sensor data is cooperatively indicative of a coasting condition of the vehicle;
a drive unit speed sensor configured to provide a signal indicative of a rotational speed of an output shaft of the drive unit, and
a torque converter controller coupled to each of the plurality of sensors and the drive unit speed sensor, the torque converter controller including a processor and memory, the memory having instructions stored therein that are executable by the processor to cause the processor to (i) determine whether the vehicle is in the coasting condition based on the sensor data produced by the plurality of sensors, (ii) determine whether the rotational speed of the output shaft of the drive unit has reached a target speed above a reference threshold based on the signal from the drive unit speed sensor, and (iii) engage the lockup clutch to maintain the rotational speed of the output shaft above the reference threshold in response to a determination that the vehicle is in the coasting condition and that the rotational speed of the output shaft has reached the target speed.

10. The control system of claim 9 , further comprising a turbine speed sensor coupled to the torque converter controller and configured to provide a signal indicative of a rotational speed of the turbine,
wherein to engage the lockup clutch comprises to determine a target torque output by the pump based on the target speed of the output shaft of the drive unit and the signal from the turbine speed sensor.

11. The control system of claim 10 , wherein the plurality of sensors includes a drive unit torque sensor configured to provide a signal indicative of torque associated with the drive unit and wherein to engage the lockup clutch comprises to receive the signal from the drive unit torque sensor.

12. The control system of claim 11 , wherein to engage the lockup clutch comprises to calculate a lockup clutch torque based on the determined target torque output by the pump and the signal from the drive unit torque sensor.

13. The control system of claim 12 , wherein to engage the lockup clutch comprises to engage the lockup clutch so that the calculated lockup clutch torque is transmitted to the output shaft of the drive unit.

14. The control system of claim 9 , wherein the plurality of sensors comprises (i) a road grade sensor configured to provide a signal indicative of a grade of a surface in contact with the vehicle, (ii) a drive unit torque sensor configured to provide a signal indicative of torque associated with the drive unit, (iii) an accelerator pedal sensor configured to provide a signal indicative of depression of an accelerator pedal of the vehicle, (iv) a brake pedal sensor configured to provide a signal indicative of depression of a brake pedal of the vehicle, and (v) a shift selector configured to provide a signal indicative of activity performed by a user.

15. The control system of claim 14 , wherein to determine whether the vehicle is in the coasting condition comprises to (i) determine whether the grade of the surface exceeds a reference road grade threshold for a reference time period based on the signal from the road grade sensor, (ii) determine whether the torque associated with the drive unit exceeds a reference torque threshold for a reference time period based on the signal from the drive unit torque sensor, (iii) determine whether the accelerator pedal is depressed for a reference time period based on the signal from the accelerator pedal sensor, (iv) determine whether the brake pedal is depressed for a reference time period based on the signal from the brake pedal sensor, and (v) determine whether activity is performed by the user based on the signal from the shift selector.

16. A method of operating a vehicle, the vehicle including a drive unit, a transmission, and a torque converter having a lockup clutch s

Assignees

• Allison Transm Inc

Inventors

• Byerly John
• Shultz Jeff

Classifications

• F16H61/143 Primary

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• F16H63/46

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• F16D48/06

  Control by electric or electronic means, e.g. of fluid pressure · CPC title

• Y02T10/60

  Other road transportation technologies with climate change mitigation effect · CPC title

• F16D2500/5043

  Engine fuel consumption · CPC title