Control system for differential of machine

• US 9,046,160 B2
• Filed: 04/03/2013
• Issued: 06/02/2015
• Est. Priority Date: 04/03/2013
• Status: Active Grant

• Current Assignee: Caterpillar Incorporated
• Original Assignee: Caterpillar Incorporated
• Inventors: Hoff, Brian D., Rettig, Mark E.
• Primary Examiner(s): YOUNG, EDWIN
• Application Number:
  US13/855,842
• Publication Number:
  US 20140303862A1
• Time in Patent Office: 790 Days
• Field of Search: 701/67, 475/86
• US Class Current: 1/1
• CPC Class Codes: B60K 2023/046 Axle differential locking means
• CPC Class Codes: B60W 10/12 including control of differentials
• CPC Class Codes: B60W 2510/104 Output speed
• CPC Class Codes: B60W 2510/105 Output torque
• CPC Class Codes: B60W 2540/18 Steering angle
• CPC Class Codes: B60Y 2200/41 Construction vehicles, e.g. graders, excavators
• CPC Class Codes: B60Y 2200/412 Excavators
• CPC Class Codes: F16D 25/12 Details not specific to one of the before-mentioned types
• CPC Class Codes: F16H 2048/205 using the steering as a control parameter
• CPC Class Codes: F16H 48/00 Differential gearings cooling or lubricating of differential gearing F16H57/04
• CPC Class Codes: F16H 48/22 using friction clutches or brakes
• CPC Class Codes: F16H 48/32 using fluid pressure actuators

Abstract

A method for controlling an operational state of a differential of a machine is disclosed. The method includes determining a transmission output speed, a transmission output torque and a degree of steering of the machine. The method further includes actuating a locking mechanism associated with the differential based on the transmission output speed, the transmission output torque, and the degree of steering.

Claims

1. A method for controlling an operational state of a differential of a machine, the method comprising:

determining a transmission output speed;

determining a transmission output torque;

determining a degree of steering of the machine; and

modulating a hydraulic pressure on a clutch pack of a locking mechanism associated with the differential based on a respective scale factor that provides a scalar adjustment to a maximum clutch pack hydraulic pressure associated with at least one of the transmission output speed, the transmission output torque, and the degree of steering.

2. The method of claim 1 further comprising:

determining a machine speed scale factor based on the transmission output speed;

determining a transmission output torque scale factor based on the transmission output torque; and

determining a steering angle scale factor based on the degree of steering of the machine.

3. The method of claim 2 further comprising determining a desired hydraulic pressure to be applied on the clutch pack based on at least one of the machine speed scale factor, the transmission output torque scale factor, steering angle scale factor, and a maximum hydraulic pressure.

4. The method of claim 3 further including generating a differential clutch command signal based on the determined desired hydraulic pressure.

5. The method of claim 4 further comprising modulating the hydraulic pressure on the clutch pack based on the differential clutch command signal.

6. The method of claim 1, wherein modulating the hydraulic pressure on the clutch pack comprising one of engaging and disengaging the clutch pack to control the operational state of the differential.

7. The method of claim 1 further comprising controlling the operational state of the differential below a threshold machine speed.

8. A control system for controlling an operational state of a differential of a machine, the control system configured to:

determine a transmission output speed;

determine a transmission output torque;

determine a degree of steering of the machine; and

modulate a hydraulic pressure on a clutch pack of a locking mechanism associated with the differential based on a product of a maximum hydraulic pressure and a scale factor corresponding to at least one of the transmission output speed, the transmission output torque, and the degree of steering.

9. The control system of claim 8 is configured to communicate with a transmission output shaft speed sensor to determine the transmission output speed, and a machine speed scale factor.

10. The control system of claim 8 is configured to communicate with a transmission output torque sensor to determine the transmission output torque, and a transmission output torque scale factor.

11. The control system of claim 8 is configured to communicate with a steering angle sensor to determine the degree of steering of the machine, and a steering angle scale factor.

12. The control system of claim 8 further configured to determine a desired hydraulic pressure on the clutch pack of the locking mechanism based on a machine speed scale factor, a transmission output torque scale factor, a steering angle scale factor, and a maximum hydraulic pressure.

13. The control system of claim 12 further configured to communicate with a control valve to apply the desired hydraulic pressure on the clutch pack of the locking mechanism based on a product of a maximum hydraulic pressure and at least one of the machine speed scale factor, a transmission output torque scale factor, and the steering angle scale factor.

14. A machine comprising:

a front section connected with a rear section by an articulated joint;

a ground engaging drive member;

a powertrain including;

an engine;

a transmission; and

a differential to transmit rotational power to the ground engaging drive member, the differential comprising a locking mechanism; and

a control system for controlling an operational state of the differential, the control system configured to;

determine a transmission output speed;

determine a transmission output torque;

determine a degree of steering of the machine; and

modulate a hydraulic pressure on a clutch pack of a locking mechanism associated with the differential based on a respective scale factor that provides a scalar adjustment to a maximum clutch pack hydraulic pressure associated with at least one of the transmission output speed, the transmission output torque, and the degree of steering.

15. The machine of claim 14, wherein the locking mechanism comprising:

the clutch pack;

a clutch actuator configured to modulate the hydraulic pressure on the clutch pack; and

a control valve configured to selectively supply and discharge fluid into the clutch actuator to modulate the hydraulic pressure on the clutch pack.

16. The machine of claim 15, wherein the control system is configured to communicate with a transmission output shaft speed sensor to determine the transmission output speed, and a machine speed scale factor.

17. The machine of claim 16, wherein the control system is configured to communicate with a transmission output torque sensor to determine the transmission output torque, and a transmission output torque scale factor.

18. The machine of claim 17, wherein the control system is configured to communicate with a steering angle sensor to determine the degree of steering of the machine, and a steering angle scale factor.

19. The machine of claim 18, wherein the control system is further configured to determine a desired hydraulic pressure on the clutch pack of the locking mechanism based on the machine speed scale factor, the transmission output torque scale factor, the steering angle scale factor, and a maximum hydraulic pressure.

20. The machine of claim 19, wherein the control system is configured to communicate with the control valve to apply the desired hydraulic pressure on the clutch pack of the locking mechanism.