Hill detection and grade percent estimation logic for an all-wheel drive system

• US 9,758,167 B1
• Filed: 03/08/2016
• Issued: 09/12/2017
• Est. Priority Date: 03/08/2016
• Status: Active Grant

• Current Assignee: GKN Driveline North America Incorporated (Melrose Industries Plc)
• Original Assignee: GKN Driveline North America Incorporated (Melrose Industries Plc)
• Inventors: Pandit, Chinmay M., Luba, Heather M., Withorn, Bradford A., Ocker, Keith E., Priemer, Douglas J.
• Primary Examiner(s): Wright, Dirk
• Application Number:
  US15/063,546
• Publication Number:
  US 20170259823A1
• Time in Patent Office: 553 Days
• Field of Search: None
• CPC Class Codes: B60K 17/348 having differential means for driving one set of wheels, e.g. the front, at one speed and the other set, e.g. the rear, at a different speed B60K17/346 takes precedence
• CPC Class Codes: B60K 23/0808 for varying torque distribution between driven axles, e.g. by transfer clutch
• CPC Class Codes: B60W 10/14 Central differentials for dividing torque between front and rear axles
• CPC Class Codes: B60W 2552/15 Road slope, i.e. the inclination of a road segment in the longitudinal direction
• CPC Class Codes: B60W 2720/403 between front and rear axle
• CPC Class Codes: B60W 30/18009 related to particular drive situations
• CPC Class Codes: B60W 30/188 Controlling power parameters of the driveline, e.g. determining the required power
• CPC Class Codes: B60W 40/076 Slope angle of the road
• CPC Class Codes: F16H 37/0806 with a plurality of driving or driven shafts

Abstract

Example methods for distributing torque in a driveline, and driveline systems are disclosed. In one approach, a baseline torque split may be employed, e.g., in a drive unit. The method may further include detecting a first gradient of a first driving surface that exceeds a threshold amount while the driveline is traversing the first gradient using the baseline torque split. The method may further include modifying the second share of torque with respect to the first share of torque in response to the detection of the first gradient. In some examples, a modification may include increasing an amount of torque being distributed to a secondary axle of the vehicle, while in others a torque bias between the primary and secondary axle may be reduced.

Claims

1. A vehicle driveline system, comprising:

a drive unit configured to divide torque between a primary axle and a secondary axle of a vehicle, wherein the drive unit is configured to employ a first torque split for traversing level surfaces below a threshold vehicle speed, wherein a first share of the torque is distributed to the primary axle of the vehicle, and a second share of the torque is distributed to the secondary axle of the vehicle;

wherein the drive unit is configured to detect a first gradient while the vehicle driveline system is traversing the first gradient using a baseline torque split, the first gradient having a positive grade exceeding a grade threshold, the drive unit configured to modify the second share of torque with respect to the first share of torque in response to the detection of the first gradient while traversing the first gradient below the threshold vehicle speed.

2. The vehicle driveline system of claim 1, wherein the drive unit is configured to employ the baseline torque split while traversing a second driving surface having a grade below a predetermined magnitude.

3. The vehicle driveline system of claim 1, wherein the second share of torque is determined from at least a magnitude of the positive grade.

4. The vehicle driveline system of claim 1, further comprising the primary and secondary axles.

5. The vehicle driveline system of claim 4, wherein the primary and secondary axles each are configured to impart rotational motion to at least one wheel.

6. The vehicle driveline system of claim 5, further comprising a driveshaft configured to impart rotational motion from the drive unit to a differential, the differential actuating the secondary axle of the vehicle.

7. The vehicle driveline system of claim 1, wherein the drive unit is a power transfer unit.

8. A vehicle driveline, comprising:

a primary axle configured to impart rotational force to a first set of vehicle wheels;

a secondary axle configured to impart rotational force to a second set of vehicle wheels, wherein the primary and secondary axles are configured to distribute torque using a first torque split for traversing level surfaces below a threshold vehicle speed, wherein a first share of the torque is distributed to the primary axle and a second share of the torque is distributed to the secondary axle; and

a controller configured to detect a first gradient while the vehicle driveline is traversing the first gradient using a baseline torque split, the first gradient having a positive grade exceeding a grade threshold, the controller configured to modify the second share of torque with respect to the first share of torque in response to the detection of the first gradient while traversing the first gradient below the threshold vehicle speed.

9. The vehicle driveline of claim 8, wherein the controller is configured to employ the baseline torque split while traversing a second driving surface having a lower coefficient of friction than the first driving surface, and the second driving surface having a grade below a predetermined magnitude.

10. A method of managing torque imparted to a vehicle driveline, comprising:

determining a baseline torque split for traversing level surfaces below a threshold vehicle speed, wherein a first share of torque is distributed to a primary axle of the vehicle driveline, and a second share of torque is distributed to a secondary axle of the vehicle driveline;

detecting a first gradient of a first driving surface while the vehicle driveline is traversing the first gradient using the baseline torque split, the first gradient having a positive grade exceeding a grade threshold; and

modifying the second share of torque with respect to the first share of torque in response to the detection of the first gradient while traversing the first gradient below the threshold vehicle speed.

11. The method of claim 10, further comprising employing the baseline torque split while traversing a second driving surface having a lower coefficient of friction than the first driving surface, and the second driving surface having a grade less than the grade threshold.

12. The method of claim 10, wherein modifying the second share of torque with respect to the first share includes increasing the second share of torque with respect to the first share of torque.

13. The method of claim 10, wherein modifying the second share of torque with respect to the first share of torque includes decreasing the second share of torque with respect to the first share of torque.

14. The method of claim 10, wherein modifying the second share of torque with respect to the first share of torque includes reducing a bias in favor of the primary axle of the vehicle driveline.

15. The method of claim 10, wherein modifying the second share of torque with respect to the first share of torque includes selectively reducing a control of one of driveline noise and driveline oscillation.

16. The method of claim 10, further comprising detecting a slippage of a wheel supported by the secondary axle.

17. The method of claim 10, further comprising determining the first gradient from a longitudinal component and a lateral component with respect to the vehicle driveline.

18. The method of claim 10, further comprising using the baseline torque split in response to a detection of a lateral gradient exceeding a threshold lateral grade magnitude.

19. The method of claim 10, further comprising enabling detection of the first gradient in response to a satisfaction of a plurality of entry conditions.

20. The method of claim 19, wherein each of the plurality of entry conditions provides an indication that the first gradient can be determined accurately when the entry condition is satisfied.

21. The method of claim 19, further comprising disabling detection of the first gradient when at least one of the plurality of entry conditions is not satisfied.