Turf Maintenance Vehicle All-Wheel Drive System

• US 20090192691A1
• Filed: 01/27/2009
• Published: 07/30/2009
• Est. Priority Date: 01/28/2008
• Status: Active Grant

• Current Assignee: Textron Innovations Incorporated (Textron Inc)
• Original Assignee: Textron Inc
• Inventors: Merriweather, Gregory, O'Connor, Sean C., Carlson, Martin M., Wilson, Kenneth R., Derby, Harry L. V
• Granted Patent: US 8,521,384 B2
• Time in Patent Office: Days
• US Class Current: 701/90
• CPC Class Codes: A01D 34/006 Control or measuring arrangements
• CPC Class Codes: A01D 34/44 with two or more cutters
• CPC Class Codes: A01D 69/02 electric
• CPC Class Codes: A01G 20/30 Apparatus for treating the lawn or grass surface machines for aerating lawns A01B45/02
• CPC Class Codes: Y02T 10/72 Electric energy management in electromobility

Abstract

A turf maintenance vehicle all-wheel drive traction control system includes a primary wheel propelling the vehicle. A first motor rotates the primary wheel. A traction control system has a first portion communicating with the first motor to monitor either a first motor current demand or a rotational speed of the primary wheel or the first motor and generates a traction control value. A secondary wheel rotated by a second motor steers the vehicle in a vehicle non-slip condition. A traction control system second portion determines a secondary wheel steering angle value. A speed threshold limit stored in the traction control system compared to the traction control value generates a slippage occurrence message indicative of a primary wheel traction loss event. A second motor drive signal created by comparing the steering angle value and the slippage occurrence message energizes the second motor during the traction loss event.

Claims

1. A turf maintenance vehicle, comprising:

at least one primary wheel operating to propel the turf maintenance vehicle;

a first motor receiving current and operating to rotate the primary wheel;

a traction control system in communication with the first motor;

at least one secondary wheel operating to steer the turf maintenance vehicle; and

a second motor operable to rotate the at least one secondary wheel and energized by a current to rotate the at least one secondary wheel,

wherein the current to at least one the first motor is temporarily decreased and the second motor is temporarily increased by the traction control system in response to a wheel slip condition of the primary wheel.

2. The turf maintenance vehicle of claim 1, further including a first signal from the first motor monitored by the traction control system.

3. The turf maintenance vehicle of claim 2, further including a predetermined speed threshold limit saved in the traction control system, wherein occurrence of the wheel slip condition of the primary wheel is identified by the traction control system when the first signal exceeds the predetermined speed threshold limit.

4. The turf maintenance vehicle of claim 3, further including a rate of acceleration of the second motor sensed by the traction control system operating to increase the current to the second motor to recover from the wheel slip condition.

5. The turf maintenance vehicle of claim 2, further including a steering angle value of the secondary wheel provided as an input to the traction control system.

6. The turf maintenance vehicle of claim 2, wherein the first signal is a current demand value of the first motor.

7. The turf maintenance vehicle of claim 2, wherein the first signal is a motor rotational acceleration value of the first motor.

8. The turf maintenance vehicle of claim 1, further including a second portion of the traction control system operating to monitor a steering angle value of the secondary wheel and a second signal.

9. The turf maintenance vehicle of claim 8, wherein the current to the second motor decreases as the steering angle value decreases to a null position, and increases as the steering angle value increases with respect to the null position.

10. The turf maintenance vehicle of claim 8, wherein the second signal is a current demand value of the second motor.

11. The turf maintenance vehicle of claim 8, wherein the second signal is a motor rotational acceleration value of the second motor.

12. The turf maintenance vehicle of claim 1, wherein the current to the second motor is temporarily increased by the traction control system in response to a wheel slip condition of the primary wheel.

13. The turf maintenance vehicle of claim 1, wherein the second motor is continuously energized by a current to rotate the at least one secondary wheel.

14. A turf maintenance vehicle, comprising:

at least one primary wheel operating to propel the turf maintenance vehicle;

a first motor operating to rotate the primary wheel, the first motor producing a first signal;

a traction control system in communication with the first motor, the traction control system storing a speed threshold limit and a predetermined speed value;

a secondary wheel operable to steer the turf maintenance vehicle; and

a second motor operating to rotate the secondary wheel,

wherein at least one of a speed of the second motor is temporarily increased and a speed of the first motor is temporarily decreased by the traction control system when the speed threshold limit compared to the first signal exceeds the predetermined value indicating a wheel slip condition of the primary wheel.

15. The turf maintenance vehicle of claim 14, further comprising a slippage occurrence message indicative of a slip event of the primary wheel generated by the traction control system when the speed threshold limit compared to the first signal exceeds the predetermined value.

16. The turf maintenance vehicle of claim 14, further comprising a current to the second motor operating to continuously energize the second motor to rotate the at least one secondary wheel.

17. The turf maintenance vehicle of claim 16, wherein a speed of the second motor is temporarily increased by the traction control system when the speed threshold limit compared to the first signal exceeds the predetermined value indicating a wheel slip condition of the primary wheel.

18. A turf maintenance vehicle, comprising:

a continuously-driven primary wheel operating to propel the turf maintenance vehicle;

a first motor operating to rotate the primary wheel;

a traction control system having a first portion in communication with the first motor, the traction control system operating to monitor a first signal;

a secondary wheel operating to steer the turf maintenance vehicle;

a second motor operable to be energized to rotate the secondary wheel; and

a second portion of the traction control system operating to monitor a steering angle value of the secondary wheel and a second signal.

19. The turf maintenance vehicle of claim 18, further including a speed threshold limit stored in the traction control system.

20. The turf maintenance vehicle of claim 19, further including a slippage occurrence message indicating a slip event of the primary wheel is occurring generated by the traction control system.

21. The turf maintenance vehicle of claim 20, further including:

a current provided to the first motor;

a predetermined value per unit time; and

a current provided to the second motor to energize the second motor;

wherein when the traction control system operably compares the first signal to the speed threshold limit and identifies the speed threshold limit is exceeded by the predetermined value per unit time defining the slip event of the primary wheel, at least one of the current to the second motor is operably increased and the current to the first motor is operably decreased.

22. The turf maintenance vehicle of claim 21, wherein when the traction control system operably compares the first signal to the speed threshold limit and identifies the speed threshold limit is exceeded by the predetermined value per unit time defining the slip event of the primary wheel, the current to the second motor is operably increased.

23. The turf maintenance vehicle of claim 21, wherein the second motor is continuously energized to rotate the secondary wheel.

24. A method for controlling wheel traction of a turf maintenance vehicle, the vehicle having a primary wheel rotated by a first motor to propel the vehicle, a traction control system storing a speed threshold limit, a secondary wheel rotated by a second motor and used to both propel and steer the vehicle, and a second motor connected to rotate the secondary wheel, the method comprising:

monitoring a first signal of a first motor speed using the traction control system;

identifying that a slip condition is occurring when a speed difference determined by subtracting the speed threshold limit from the first signal is higher than a pre-determined value; and

calculating an increased current value to supply to the second motor and a reduced current value to supply to the first motor to reduce the slip condition.

25. The method of claim 24, further comprising querying a power steering control unit for a value of a steering angle of the second wheel.

26. The method of claim 25, further comprising determining the steering angle as an angle of wheel rotation measured from a null reference line.

27. The method of claim 25, further comprising including the steering angle in the calculating step.

28. The method of claim 24, further comprising monitoring a second signal indicative of a second motor speed using the traction control system.

29. The method of claim 28, further comprising temporarily increasing the second motor speed using the traction control system when the speed threshold limit compared to the first signal exceeds the predetermined value indicating a wheel slip condition of the primary wheel.

30. The method of claim 24, further comprising continuing to vary the decreased current value delivered to the first motor and the increased current value delivered to the second motor until the slip condition ends, defined when the speed difference is less than or equal to the predetermined value.

31. A method for controlling wheel traction of a turf maintenance vehicle, the vehicle having a primary wheel rotated by a first motor to propel the vehicle, a traction control system storing a speed threshold limit, a secondary wheel rotated by a second motor and used to both propel and steer the vehicle, and a second motor connected to rotate the secondary wheel, the method comprising:

monitoring a first signal of a first motor speed using the traction control system;

identifying that a slip condition is occurring when a signal indicating an acceleration change rate over a predetermined period of time of the first motor is higher than a threshold value; and

calculating an increased current value to supply to the second motor and a reduced current value to supply to the first motor to reduce the slip condition.