SHIFTER WITH ACTUATOR INCORPORATING SHAPE MEMORY ALLOY

• US 20080006112A1
• Filed: 07/03/2007
• Published: 01/10/2008
• Est. Priority Date: 07/05/2006
• Status: Active Grant

• Current Assignee: GHSP Incorporated (JSJ Corporation)
• Original Assignee: Grand Haven Stamped Products Company (JSJ Corporation)
• Inventors: Mitteer, David
• Granted Patent: US 7,814,810 B2
• Time in Patent Office: Days
• US Class Current: 074/473.1
• CPC Class Codes: F16H 59/10 comprising levers
• CPC Class Codes: F16H 61/22 Locking of the control input devices constructional features of locking or disabling mechanisms F16H63/34
• CPC Class Codes: Y10T 74/20018 Transmission control
• CPC Class Codes: Y10T 74/20085 Restriction of shift, gear selection, or gear engagement
• CPC Class Codes: Y10T 74/20091 Prevention of reverse shift
• CPC Class Codes: Y10T 74/20098 Separate actuator to disengage restrictor
• CPC Class Codes: Y10T 74/22 Miscellaneous

Abstract

A shifter includes an actuator incorporating a shape memory alloy wire to control movement of lever-position-controlling components of a vehicle transmission shift lever. In one arrangement, the actuator controls movement of a cam to prevent moving a pawl out of park position until predetermined vehicle conditions are met. Alternatively, the actuator can be directly attached to the pawl itself for controlling movement of the pawl, or connected to a toggle linkage arrangement for controlling movement of the pawl. In still another arrangement, a magnet arrangement is used to motivate a pawl-blocking member. When necessary, a mechanical fuse is operably connected to the system to prevent damage to the shape memory alloy wire where there is risk of the pawl being frictionally stopped from movement despite the contraction of the shape memory alloy wire actuator.

Claims

1. In a park lock/brake transmission shift interlock apparatus including a base, a shift lever pivoted to the base for movement between a plurality of gear positions including a park position, a pawl on the shift lever selectively engageable with notches on the base to control movement of the shift lever between the gear positions, a lever-position-controlling component, and a control circuit for controlling operation of the shifter based on predetermined vehicle conditions being met, an improvement comprising:

an actuator for operating the lever-position-controlling component, the actuator incorporating shape memory alloy wire operably connected to the control circuit and to the lever-position-controlling component for locking the shift lever in a selected one of the gear positions until the predetermined vehicle conditions are met.

2. The apparatus defined in claim 1, wherein the actuator is operably connected to the pawl for moving the pawl between a locking position where the pawl is engaged with a selected one of the notches, and a release position where the pawl is permitted to retract to allow movement of the shift lever between the gear positions.

3. The apparatus defined in claim 2, wherein the lever-position-controlling component includes a linkage for moving the pawl between a first position where the pawl engages a selected one of the notches, and a second position disengaging the pawl to allow movement of the pawl and hence movement of the shift lever between the gear positions, the actuator being connected to the linkage for actuating the linkage.

4. The apparatus defined in claim 1, wherein the lever-position-controlling component includes a blocking member for abuttingly locking the pawl in a selected position, the actuator being connected to the blocking member for moving the blocking member between a locking position retaining the pawl in a selected one of the notches and a release position allowing movement of the pawl out of the selected one notch to allow the shift lever to move between the gear positions.

5. The apparatus defined in claim 1, wherein the lever-position-controlling component includes a blocking member for abuttingly holding the shift lever in a selected position, the wire being connected to the blocking member for moving the blocking member between a locking position engaging the shift lever to retain the shift lever in a selected one of the gear positions and a release position allowing movement of the shift lever between the gear positions.

6. The apparatus defined in claim 1, including a mechanical fuse connected to the wire to prevent damage to the wire when the actuator is energized to move the lever-position-controlling component at a time when the lever-position-controlling component cannot move.

7. The apparatus defined in claim 6, wherein the mechanical fuse is connected to the pawl and includes a pawl housing, a first spring biasing the pawl to extend from the pawl housing, and a second spring operably connected between the wire and the pawl, the second spring being configured to compress when the wire is operated to retract the pawl at a time when the pawl cannot be retracted.

8. The apparatus defined in claim 1, including a compensating device associated with the wire and configured to allow the wire to change length without forcing movement of the lever-position-controlling component.

9. The apparatus defined in claim 8, wherein the compensating device is configured to store energy from the wire until such time as the stored energy can be used to move the lever-position-controlling component.

10. The apparatus defined in claim 8, wherein the compensating device includes an arrangement of magnets.

11. A method of controlling a shifter having lever-position-controlling components, comprising a step of:

passing controlled amounts of electrical current through a shape memory alloy wire actuator to change a length of the wire actuator based on current flow and material phase change in order to control a position of at least one of the lever-position-controlling components.

12. The method defined in claim 11, including connecting a mechanical fuse to the wire actuator to protect the wire actuator even when the wire actuator is operated to change a length of the wire actuator at a time when the at least one lever-position-controlling component cannot move.

13. The method defined in claim 11, including an arrangement of magnets arranged to absorb energy when the shape memory alloy wire actuator is energized at a time when the one lever-position-controlling component cannot move.

14. An actuator for an apparatus including a blocking member movable between a locked first position and an unlocked second position, and a drive mechanism for motivating the blocking member, comprising:

at least two permanent magnets, a first one of the magnets being affixed to the blocking member, a second one of the magnets being operably connected to the drive mechanism;

an actuator including at least one shape memory alloy wire coupled to the drive mechanism to move the second magnet when a length of the wire changes; and

a circuit connected to the actuator for applying electrical current through the wire to energize the wire and cause a material phase transition so that the wire changes length to move the second permanent magnet to a position where the second magnet magnetically biases the first permanent magnet, thereby causing the blocking member to move between the first position and the second position.

15. The actuator of claim 14, wherein the second magnet is rotatably supported to rotate between 30 and 180 degrees.

16. The actuator of claim 14, wherein the first and second magnets are positioned to magnetically repel each other when the wire is in a de-energized state, and to magnetically attract each other when the drive mechanism is actuated by the wire.

17. The actuator of claim 14, wherein the first and second magnets are positioned to magnetically attract each other when the wire is in a de-energized state, and to magnetically repel each other when the drive mechanism is actuated by the wire.

18. The actuator of claim 14, wherein the circuit includes a power cutoff switch constructed to remove electrical power from the wire after the drive mechanism has reached a predetermined position.

19. The actuator of claim 18, wherein the cutoff switch is a hall effect sensor.

20. The actuator of claim 14, wherein at least one of the magnets is a rare earth magnet selected from a group consisting of neodymium type magnets and samarium cobalt type magnets.

21. The actuator of claim 20, wherein the at least one magnet is a neodymium N42 type magnet.

22. An improved actuator for an apparatus including a blocking member for blocking movement of another component and a drive mechanism for motivating the blocking member to move between a locked first position and an unlocked second position, comprising:

at least three permanent magnets, a first one of the magnets being affixed to the blocking member, second and third of the magnets being affixed to the drive mechanism and being offset from each other, with the second magnet being in magnetic communication with the first magnet when the blocking member is in the first position;

a carrier for the magnets; and

a circuit including at least one length of shape memory alloy wire coupled to the carrier, the circuit being configured to apply current to energize the shape memory alloy wire when predetermined conditions are met, the shape memory alloy wire when energized undergoing a length change, resulting in the carrier moving, which in turn places the third magnet into magnetic communication with the first magnet on the blocking member in a manner causing the blocking member to move between the first position and the second position.

23. The actuator of claim 22, wherein the first and second magnets repel each other when the shape memory alloy wire is in a de-energized state, and wherein the first and third magnets attract each other when the drive mechanism is actuated by the shape memory alloy wire.

24. The actuator of claim 22, wherein the first and second magnets attract each other when the shape memory alloy wire is in a de-energized state, and wherein the first and third magnets repel each other when the drive mechanism is actuated by the shape memory alloy wire.

25. The actuator of claim 22, including a power cutoff switch to remove power from the shape memory alloy wire after the drive mechanism has reached a predetermined position.

26. The actuator of claim 25, wherein the cutoff switch is a hall effect sensor.

27. The actuator of claim 26, wherein the hall effect sensor is triggered by a permanent magnet housed in the drive mechanism.

28. The actuator of claim 26, wherein the hall effect sensor is triggered by the permanent magnet attached to the blocking member.

29. The actuator of claim 22, wherein the magnets are rare earth magnets selected from a group consisting of neodymium type magnets and samarium cobalt type magnets.

30. The actuator of claim 29, wherein the magnet is a neodymium N42 type magnet.

31. An actuator comprising:

a drive mechanism;

a blocking member arranged to block movement of a lock mechanism; and

at least three permanent magnets, a first one of the magnets being affixed to a shaft member of the drive mechanism, the other two magnets being offset from each other and affixed to the blocking member;

a circuit including at least one length of shape memory alloy wire coupled to the drive mechanism so that a change in length of the shape memory alloy wire causes the shaft member to move, thereby moving the first permanent magnet between a first position in magnetic communication with the second magnet, and a second position in magnetic communication with the third magnet, such that the blocking member is magnetically driven by the driving mechanism between the first position and the second position.

32. The actuator of claim 31, wherein the circuit includes a power cutoff switch to remove power from the shape memory alloy wire after the drive mechanism has reached a predetermined position.

33. The actuator of claim 32, wherein the cutoff switch is a hall effect sensor.

34. The actuator of claim 33, wherein the hall effect sensor is triggered by sensing a position of the first permanent magnet.

35. The actuator of claim 33, wherein the hall effect sensor is triggered by one of the other two magnets on the blocking mechanism.

36. The actuator of claim 31, wherein the drive mechanism rotates the magnet between 30 and 180 degrees.