Heat responsive memory metal actuator

• US 5,107,916 A
• Filed: 06/05/1990
• Issued: 04/28/1992
• Est. Priority Date: 06/05/1990
• Status: Expired due to Fees

• Current Assignee: IPS BV (Total Webhosting Solutions BV)
• Original Assignee: IPS BV (Total Webhosting Solutions BV)
• Inventors: Besselink, Ir P., van Roermund, Ton
• Primary Examiner(s): Johnson, Blair M.
• Application Number:
  US07/533,453
• Time in Patent Office: 693 Days
• Field of Search: 160/6, 98/40.25
• US Class Current: 160/6
• CPC Class Codes: E06B 9/322 Details of operating devices, e.g. pulleys, brakes, spring drums, drives operating devices E06B9/68 ; devices of general interest specially adapted or mounted for storing and repeatedly paying-out and re-storing lengths of material B65H75/34
• CPC Class Codes: F24F 11/76 by means responsive to temperature, e.g. bimetal springs
• CPC Class Codes: F24F 13/15 with parallel simultaneously tiltable lamellae
• CPC Class Codes: G12B 1/00 Sensitive elements capable of producing movement or displacement for purposes not limited to measurement; Associated transmission mechanisms therefor

Abstract

An actuator which includes a memory metal element, a substantially constant force counteracting spring, and an actuated element. The memory metal transforms from a martensite structure to an austenite structure at a known temperature. The martensite structure is more easily deformed than the austenite structure. The force applied by the counteracting spring is sufficient to deform the martensite structure throughout the transformation temperature range but insufficient to deform the austenite structure such that at least a portion of the memory metal element undergoes a predetermined stroke in response to the transformation of the memory metal element between the martensite and austenite states. The actuated element is connected to the memory metal element to move therewith.

Claims

1. A temperature responsive actuator comprising:

a memory metal element, the memory metal element including memory metal which undergoes a predetermined transformation between a predetermined first structure and a predetermined second structure at a first predetermined temperature range and between the second structure and the first structure at a second predetermined temperature range;

a generally constant force spring element, the spring element being connected to the memory metal element so as to provide a generally constant deformation force to the memory metal element, the generally constant force provided by the spring element being selected to be less than the force required to deform the memory metal element at temperatures above the predetermined temperatures and greater than the force required to deform the memory metal element at temperatures below the predetermined temperatures, such that the spring element deforms the memory metal element at a temperature below the predetermined temperature range and the memory metal element returns to its undeformed state against the bias of the spring element at temperatures above the predetermined temperature; and

an actuated element connected to one of the memory metal element and the generally constant force spring element for movement in response to the change of shape of the memory metal element resulting from transformation of the memory metal between states.

2. The actuator of claim 1, wherein the actuated element is a control element for a venetian blind.

3. The actuator of claim 1, further comprising a mechanical movement device operably connected to said actuated element for converting said movement of the actuated element into a different type of movement.

4. The actuator of claim 3, wherein the mechanical movement device comprises a rack and pinion device.

5. The actuator of claim 3, wherein the mechanical movement device comprises a wire and drum, the wire having one end connected to the memory metal element and another end wrapped around and connected to the drum such that linear movement of the end of the wire connected to the memory metal element is converted into rotation of the drum.

12. The actuator of claim 1, wherein the memory metal is a nickel titanium alloy.

13. The actuator of claim 1, further comprising a controlled electrical heater for heating the memory metal element to cause actuation of the actuated element.

18. The actuator of claim 1, wherein the memory metal element is a straight tension wire.

19. The actuator of claim 1, wherein the memory metal element is a coiled spring.

6. A memory metal actuator for actuating a component in response to temperature change, the memory metal actuator comprising:

a memory metal element, the memory metal element being deformable between first and second predetermined shapes in response to temperature changes;

a generally constant force spring assembly, the constant force spring assembly comprising a first drum, a second drum, a strip stored on the first drum, the strip having an end attached to the second drum in such a way that when the strip unrolls from the first drum, it rolls upon the second drum, a wire stored on the drum attached to the memory metal element so as to apply a counteracting force to the memory metal element; and

an actuated element, the actuated element being connected to one of the memory metal element and the generally constant force spring assembly for movement in response to changes in the balance of forces between the memory metal and the generally constant force spring assembly.

7. The actuator of claim 6, wherein the actuated element is a control element for a venetian blind.

8. The actuator of claim 6, further comprising a mechanical movement device for converting the movement of the actuated element into a different type of movement.

9. The actuator of claim 8, wherein the mechanical movement device comprises a rack and pinion device.

10. The actuator of claim 8, wherein the mechanical movement device comprises a wire and a drum, the wire having one end connected to the memory metal element and another end wrapped around and connected to the drum such that linear movement of the end of the wire connected to the memory metal element is converted into rotation of the drum.

11. A temperature responsive actuator comprising:

a housing;

a memory metal element comprising a coiled spring located within the housing, the memory metal element having a composition such that the memory metal transforms from a martensite structure to an austenitic structure through a transformation range in response to a known increase in temperature;

a counteracting spring arranged within the housing and connected to the memory metal element at a point of connection so as to provide a force which is sufficient to deform the memory metal element in its martensitic state but insufficient to deform the memory metal in its austenitic state throughout the transformation range, such that when the memory metal is transformed from its martensitic state to its authentic state, the memory metal element shrinks and the point of connection moves during the transformation; and

an actuated element connected to one of the memory metal element and the counteracting spring such that the actuated element moves when the point of connection moves.

14. The actuator of claim 11, wherein the actuated element is a control element for a venetian blind.

15. The actuator of claim 11, further comprising a mechanical movement device for converting movement of the actuated element into a different type of movement.

16. The actuator of claim 15, wherein the mechanical movement device comprises a rack and pinion device.

17. The actuator of claim 15, wherein the mechanical movement device comprises a wire and a drum, the wire having one end connected to the memory metal element and another end wrapped around and connected to the drum such that linear movement of the end of the wire connected to the memory metal element is converted into rotation of the drum.

20. The actuator of claim 11, wherein the counteracting spring is a contestant force spring element.