Electronic Locking Differential

• US 20110022279A1
• Filed: 07/23/2009
• Published: 01/27/2011
• Est. Priority Date: 07/23/2009
• Status: Active Grant

• Current Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Original Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Inventors: Saieg, John R., Povirk, Jacob M., Pietrzyk, Gary M.
• Granted Patent: US 8,265,842 B2
• Time in Patent Office: Days
• US Class Current: 701/68
• CPC Class Codes: B60K 23/04 for differential gearing
• CPC Class Codes: F16H 2048/205 using the steering as a control parameter
• CPC Class Codes: F16H 48/24 using positive clutches or brakes
• CPC Class Codes: F16H 48/30 using externally-actuatable means

Abstract

A method for controlling a clutch of an electronic locking differential for a vehicle includes determining either that a speed of the vehicle is less than a reference speed or that a desired state of the clutch is a disengaged state, determining that an angular displacement of a steering wheel from a centered position is less than a first reference angle, and disengaging the clutch.

Claims

1. A method for controlling a clutch of an electronic locking differential for a vehicle, comprising the steps of:

(a) determining either that a speed of the vehicle is greater than a reference speed or that a desired state of the clutch is a disengaged state;

(b) determining that an angular displacement of a steering wheel from a centered position is less than a first reference angle;

(c) disengaging the clutch.

2. The method of claim 1, further comprising:

(d) determining that the angular displacement of the steering wheel changes from greater than to less than a second reference angle; and

(e) disengaging the clutch when a first period expires.

3. The method of claim 1, wherein step (a) further comprises:

using a manually operated switch to indicate the desired state of the clutch.

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

determining that said displacement is maintained for a length of a second period.

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

disconnecting a source of electric power from an electromagnetic coil that actuates the clutch.

6. The method of claim 1, wherein step (d) further comprises:

determining that said displacement is maintained for a length of a third period.

7. A method for controlling a clutch of an electronic locking differential for a vehicle, comprising the steps of:

(a) determining either that a speed of the vehicle is greater than a reference speed or that a desired state of the clutch is a disengaged state;

(b) determining that an angular displacement of a steering wheel from a reference position is less than a first reference angle;

(c) disengaging the clutch;

(d) if neither the speed of the vehicle is greater than the reference speed nor the desired state of the clutch is the disengaged state, determining that the displacement of the steering wheel changes from greater than a second angle to less than the second angle;

(e) disengaging the clutch after a first period expires.

8. The method of claim 7, wherein step (a) further comprises:

using a manually operated switch to indicate the desired state of the clutch.

9. The method of claim 7, wherein step (b) further comprises:

determining that said displacement is maintained for a length of a second period.

10. The method of claim 7, wherein step (c) further comprises:

disconnecting a source of electric power from an electromagnetic coil that actuates the clutch.

11. The method of claim 7, wherein step (d) further comprises:

determining that said displacement is maintained for a length of a third period.

12. A system for controlling an electronic locking differential for a vehicle, comprising:

a clutch that alternately locks and unlocks the differential;

a spring that urges the clutch to unlock;

an electric power source;

an electromagnetic coil that urges the clutch to lock in response to current applied to the coil from the electric power source; and

a controller configured to determine either that a speed of the vehicle is less than a reference speed or that a desired state of the clutch is a disengaged state, determine that an angular displacement of a steering wheel from a centered position is less than a first reference angle, and allow the clutch to unlock by opening an electric connection between the coil and the electric power source.

13. The system of claim 12, wherein:

the controller is further configured to determine that the displacement of the steering wheel changes from greater than a second angle to less than the second angle, if neither the speed of the vehicle is less than the reference speed nor the desired state of the clutch is the disengaged state, and disengage the clutch after a first period expires.