SHAPE MEMORY ALLOY (SMA) SYSTEM

• US 20080120976A1
• Filed: 06/26/2006
• Published: 05/29/2008
• Est. Priority Date: 06/26/2006
• Status: Active Grant

• Current Assignee: Lear Corporation
• Original Assignee: Lear Corporation
• Inventors: Nathan, John F., Kennedy, Karl, Maue, H. Winston
• Granted Patent: US 7,581,706 B2
• Time in Patent Office: Days
• US Class Current: 60/528
• CPC Class Codes: B60N 2/0806 with pin alignment systems, e.g. with at least one of a plurality of locking pins always aligned w.r.t. at least one of a plurality of pin-receiving elements
• CPC Class Codes: B60N 2/0875 in a vertical direction
• CPC Class Codes: F03G 7/065 using a shape memory element

Abstract

A shape memory alloy (SMA) system suitable for use in any number of environments, including but not limited to latching and unlatching vehicle seat tracks. The system including any number of configurations to support any number of operations, including but not limited to push-push, pull-pull, push-pull, and pull-push operations.

Claims

1. A shape memory system comprising:

a first shape memory alloy (SMA) element configured for excitation in a first direction;

a second SMA element in communication with the first SMA and configured for excitation in a second direction, the second direction being different than the first direction;

each SMA element connected to an electrical ground; and

a controller in communication with the first and second SMAs and configured to sequentially control current supplied to the SMA grounds, and thereby, excite the SMA elements in such as manner as to sequentially excite the first SMA in the first direction and thereafter excite the second SMA in the second direction so as to move the first SMA in the second direction.

2. The system of claim 1 wherein the controller is configured to limit excitation of the SMA elements as a function of temperatures of the elements.

3. The system of claim 1 wherein the controller is configured to excite the second SMA element during excitation of the first SMA element so as to control movement of the first SMA element in the first direction.

4. The system of claim 1 wherein the SMA elements are arranged with respect to the first and second directions such that the excitation of the same produces a push-pull, push-push, pull-push, or pull-pull operation.

5. The system of claim 1 further comprising a moveable member in communication with the first SMA element, the moveable member moveable in the first direction with excitation of the first SMA element and moveable in the second direction with excitation of the second SMA element.

6. The system of claim 5 wherein the moveable member is a positive engagement latch used for positioning a vehicle seat.

7. An electrically operable positive engagement latch for use in positioning a vehicle seat, the positive engagement latch comprising:

a locking mechanism for limiting movement of the vehicle seat relative to a vehicle seat track;

a first shape memory alloy (SMA) element in communication with the locking mechanism and configured for disengaging the locking mechanism so as to permit movement of the vehicle seat; and

a second SMA element in communication with the locking mechanism and configured for engaging the locking mechanism so as to prevent movement of the vehicle seat.

8. The latch of claim 7 wherein the locking mechanism includes a number of pins for receipt within apertures of the vehicle seat track, the pins being removed from the apertures when the locking mechanism is disengaged and the pins being inserted within the apertures when the locking mechanism is engaged.

9. The latch of claim 8 further comprising a cross-bar extending through an aperture in each of the pins, the SMA elements being connected to the cross-bar such that the SMA elements actuate the cross-bar in order to remove and insert the pins relative to the apertures.

10. The latch of claim 7 wherein the SMA elements are arranged to remove and insert the pins in a push-pull, push-push, pull-push, or pull-pull operation.

11. The latch of claim 7 further comprising an electrical ground for each of the SMA elements, the electrical ground configured to sink electrical current used to excite the SMA elements.

12. A seat track assembly for adjusting a seat assembly of a vehicle, the seat track assembly comprising:

a first track;

a second track that is moveable with respect to the first track; and

an electrically operable latch mechanism associated with the second track and being operative to inhibit relative movement of the tracks, the latch mechanism including multiple triggers that are moveable between a locked position in which the triggers are engaged with the first track and an unlocked position in which the triggers are disengaged from the first track.

13. The seat track assembly of claim 12 further comprising at least one shape memory alloy (SMA) element, the SMA element configured to facilitate electrically engaging and disengaging the triggers.

14. The seat track assembly of claim 13 further comprising at least one additional SMA element such that the assembly includes at least a first and second SMA element, the first SMA element associated with electrically disengaging the triggers and the second SMA element associated with electrically engaging the triggers.

15. The seat track assembly of claim 13 further comprising a controller for electrically controlling movement of the SMA elements, and thereby, movement of the triggers.

16. The seat track assembly of claim 15 wherein the controller is configured to control excitation of the SMA element through electrical stimulation.

17. The seat track assembly of claim 16 wherein the controller is configured to limit excitation of the SMA element as a function of temperatures of the elements.

18. The seat track assembly of claim 17 wherein the assembly includes at least a first and second SMA element and the controller is configured to excite the second SMA element during excitation of the first SMA element so as to counteract movement of the first SMA element.

19. The seat track assembly of claim 18 wherein the SMA element 2 are arranged such that the excitation of the same produces a push-pull, push-push, pull-push, or pull-pull operation.

20. The seat track assembly of claim 12 wherein the triggers are 2 pins that are moveable with movement of a cross-bar member connected thereto, the 3 cross-bar member connected to at least one electrically excitable shape memory 4 alloy (SMA) element.