Active material actuated headrest assemblies

• US 20070188004A1
• Filed: 10/31/2006
• Published: 08/16/2007
• Est. Priority Date: 11/04/2005
• Status: Active Grant

• Current Assignee: GM Global Technology Operations LLC (General Motors Company)
• Original Assignee: GM Global Technology Operations Incorporated (Motors Liquidation Co. GUC Trust)
• Inventors: Johnson, Nancy, Alexander, Paul, Browne, Alan, Khoury, James, Carpenter, Michael
• Granted Patent: US 7,556,313 B2
• Time in Patent Office: Days
• US Class Current: 297/391
• CPC Class Codes: A47C 7/38 for the head adjustable coupled to reclining or easy chairs A47C1/036
• CPC Class Codes: B60N 2/888 with arrangements for protecting against abnormal g-forces, e.g. by displacement of the head-rest

Abstract

A headrest assembly for a seat includes a body portion having at least one padded surface positioned in substantial alignment with a seated occupant'"'"'s head; and an active material in operative communication with the at least one padded surface of the body portion, the active material being operative to change at least one attribute in response to an activation signal, wherein a space between the occupant'"'"'s head and the at least one padded surface decreases with the change in the at least one attribute of the active material.

Claims

1. A headrest assembly for a seat, comprising:

a body portion having at least one padded surface positioned in substantial alignment with a seated occupant'"'"'s head; and

an active material in operative communication with the at least one padded surface of the body portion, the active material being operative to change at least one attribute in response to an activation signal, wherein a space between the occupant'"'"'s head and the at least one padded surface decreases and/or a compliance property of the headrest changes with the change in the at least one attribute of the active material.

2. The headrest assembly of claim 1, wherein the active material comprises a shape memory polymer, a shape memory alloy, an electroactive polymer, a magnetorheological elastomer, a piezoelectric material, a magnetostrictive material, an electrorheological elastomer, a ferromagnetic shape memory alloy, or a combination comprising at least one of the foregoing active materials.

3. The headrest assembly of claim 1, wherein the body portion is fixedly attached to at least one support post.

4. The headrest assembly of claim 1, wherein the activation signal comprises a thermal activation signal, a magnetic activation signal, an electrical activation signal, a chemical activation signal or a combination comprising at least one of the foregoing signals.

5. The headrest assembly of claim 1, further comprising at least one sensor and a controller in operative communication with the active material.

6. The headrest assembly of claim 1, wherein the body portion and the padded surface are configured to decrease the space in response to the activation signal to the active material.

7. The headrest assembly of claim 1, further comprising a unidirectional releasable ratchet mechanism in operative communication with the at least one padded surface and configured to prevent an increase of the space between the occupants head and the at least one padded surface once the active material is activated upon contact of the at least one padded surface with an object.

8. The headrest assembly of claim 1, wherein the change in the at least one attribute inflates a bladder in cooperative communication with the active material.

9. A headrest assembly for a seat, comprising at least one support post extending upwardly from the seat;

a headrest body attached to the at least one support post;

a padded portion in pivotal communication with the headrest body and substantially aligned with a seated occupant'"'"'s head; and

an active material actuator in a cooperative relationship with the padded portion, wherein the active material actuator is adapted to move the padded portion forward and/or upward relative to the headrest body upon receipt of an activation signal.

10. The headrest assembly of claim 9, wherein the active material actuator comprises an active material selected from a groups consisting a shape memory polymer, a shape memory alloy, an electroactive polymer, a magnetorheological elastomer, a piezoelectric material, a magnetostrictive material, an electrorheological elastomer, a ferromagnetic shape memory alloy, and combinations of at least one of the foregoing active materials.

11. The headrest assembly of claim 9, further comprising a ratchet mechanism in cooperative relationship with the padded portion and configured to permit forward movement of the padded portion while preventing backward movement.

12. The headrest assembly of claim 9, wherein the ratchet mechanism comprises an additional active material configured to selectively release the ratchet mechanism and permit the padded portion to be restored to an original position.

13. The headrest assembly of claim 9, wherein the padded portion is pivotally attached to the headrest body.

14. The headrest assembly of claim 9, further comprising a sensor in operative communication with an activation device for triggering the activation signal.

15. The headrest assembly of claim 9, wherein the padded portion in pivotal communication with the headrest body comprises a four bar link assembly and an active material based actuator configured for projecting the padded portion.

16. The headrest assembly of claim 15, wherein the active material based actuator comprises a bracket, an axle for rotatably supporting the bracket at each end, and a first shape memory alloy wire adapted to rotate the bracket upon activation of the first shape memory alloy wire.

17. The headrest assembly of claim 16, further comprising a second shape memory alloy wire configured to provide counter-rotation of the bracket upon deactivation of the first shape memory alloy wire.

18. The headrest assembly of claim 9, wherein the active material is configured to restrain forward movement during contact with the seated occupants'"'"' head.

19. A process for reducing a space between a headrest and an occupant'"'"'s head and/or changing the compliance of the headrest, the process comprising:

activating an active material based actuator disposed within a headrest supported by at least one support post projecting from a seat; and

moving a padded surface forward relative to the at least one support post upon activating the active material based actuator and reducing the space between the headrest and the occupant'"'"'s head.

20. The process of claim 19, wherein the active material comprises a shape memory polymer, a shape memory alloy, an electroactive polymer, a magnetorheological elastomer, a piezoelectric material, a magnetostrictive material, an electrorheological elastomer, a ferromagnetic shape memory alloy, or a combination comprising at least one of the foregoing active materials.

21. The process of claim 19, wherein the headrest comprises a padded portion in operative communication with the active material based actuator, wherein the padded portion provides the padded surface.

22. The process of 19, wherein moving the padded surface forward relative to the at least one support post upon activating the active material based actuator and reducing the space between the headrest and the occupant'"'"'s head is motion limited upon contact of the padded surface an the occupant'"'"'s head.