Frangible Shape Memory Alloy Fire Sprinkler Valve Actuator

• US 20100025050A2
• Filed: 01/24/2008
• Published: 02/04/2010
• Est. Priority Date: 01/25/2007
• Status: Active Grant

• Current Assignee: TiNi Alloy Company
• Original Assignee: TiNi Alloy Company
• Inventors: Martynov, Valery, Gilbertson, Roger, Johnson, Alfred
• Granted Patent: US 8,684,101 B2
• Time in Patent Office: Days
• US Class Current: 169/19
• CPC Class Codes: A62C 37/16 with thermally-expansible links
• CPC Class Codes: B23P 15/001 valves or valve housings welding B23K; valve housings per se F16K
• CPC Class Codes: Y10T 137/1662 Tensile or sheer pin or bolt
• CPC Class Codes: Y10T 137/1797 Heat destructible or fusible
• CPC Class Codes: Y10T 29/49405 Valve or choke making
• CPC Class Codes: Y10T 29/49412 with assembly, disassembly or composite article making

Abstract

A temperature-activated valve for a conventional fire sprinkler utilizing a hyperelastic single-crystal shape memory alloy is described. The shape-memory element expands as it is heated, forcing a bolt to break, thereby opening the sprinkler valve. The devices described are less susceptible to accidental breakage than conventional actuators, and have fewer moving parts. Transition temperature of the shape memory alloy can be tuned to a narrow range.

Claims

1. A thermally-activated sprinkler valve assembly comprising:

a fluid passageway having an outlet and configured to connect to a source of pressurized fluid;

a valve over the outlet, the valve configured to releasably oppose the force of the pressurized fluid; and

a temperature-sensitive actuator coupled to the valve, the actuator comprising;

a frangible bolt; and

a shape-memory element capable of elongating at a pre-determined stress and temperature, wherein the frangible bolt applies compressive force to the shape-memory element;

wherein the temperature-sensitive actuator is configured to actuate the valve by breaking the frangible bolt when the temperature of the shape-memory element reaches or exceeds the pre-determined temperature.

2. The valve assembly of claim 1, further wherein the temperature-sensitive actuator is coupled to the valve through a linkage that is configured to oppose the force of pressurized fluid and thereby maintain the valve closed.

3. The valve assembly of claim 2, wherein the temperature-sensitive actuator is positioned in parallel with the linkage.

4. The valved assembly of claim 1, wherein temperature-sensitive actuator is configured so that force from the pressurized fluid is not substantially transmitted to the shape-memory element.

5. The valve assembly of claim 1, wherein the plateau stress of the shape-memory element is approximately the same as the ultimate tensile strength of the bolt.

6. The valve assembly of claim 1, further comprising a nut securing the frangible bolt to the shape-memory element.

7. The valve assembly of claim 1, further comprising a frame portion extending from the fluid passageway.

8. The valve assembly of claim 1, wherein the frangible bolt is notched.

9. The valve assembly of claim 1, wherein the frangible bolt is a titanium bolt.

10. The valve assembly of claim 1, wherein the shape-memory element is a single-crystal CuAlNi alloy or a single-crystal CuAlMn alloy.

11. The valve assembly of claim 1, wherein the shape-memory element is a tempered single-crystal shape memory alloy.

12. The valve assembly of claim 1, wherein the shape-memory element comprises a cylinder at least partially surrounding the frangible bolt.

13. A thermally-activated sprinkler valve assembly comprising:

a fluid passageway having a valved outlet and configured to connect to a source of pressurized fluid;

a linkage coupled to the valved outlet and configured to oppose the force of pressurized fluid and thereby maintain the valve closed; and

a temperature-sensitive actuator coupled to the linkage, wherein the temperature-sensitive actuator comprises;

a frangible bolt; and

a shape-memory element capable of elongating as much as eight percent at a pre-determined stress and temperature, wherein a length of the frangible bolt applies compressive force to the shape-memory element.

14. The valve assembly of claim 13, further comprising a nut securing the frangible bolt to the shape-memory element.

15. The valve assembly of claim 13, wherein the linkage comprises a bracket.

16. The valve assembly of claim 13, wherein the linkage comprises two T-shaped brackets.

17. The valve assembly of claim 13, wherein the frangible bolt is notched.

18. The valve assembly of claim 13, wherein the frangible bolt is a titanium bolt.

19. The valve assembly of claim 13, wherein the shape-memory element is a single-crystal CuAlNi alloy or a single-crystal CuAlMn alloy.

20. The valve assembly of claim 13, wherein the shape-memory element is a tempered single-crystal shape memory alloy.

21. The valve assembly of claim 13, wherein the shape-memory element comprises a cylinder at least partially surrounding the frangible bolt.

22. The valved assembly of claim 13, wherein temperature-sensitive actuator is configured so that force from the pressurized fluid is not substantially transmitted to the shape-memory element.

23. The valve assembly of claim 13, wherein the temperature-sensitive actuator is positioned in parallel with the linkage.

24. The valve assembly of claim 13, wherein the plateau stress of the shape-memory element is approximately the same as the ultimate tensile strength of the bolt.

25. A thermally-activated sprinkler valve assembly comprising:

a fluid passageway having a valved outlet and configured to connect to a source of pressurized fluid;

a linkage bracket coupled to the valved outlet and configured to oppose the force of pressurized fluid and thereby maintain the valve closed; and

a temperature-sensitive actuator coupled to the linkage bracket, wherein the temperature-sensitive actuator comprises;

a frangible bolt; and

a shape-memory element capable of elongating as much as eight percent at a pre-determined stress and temperature, wherein a length of the frangible bolt applies compressive force to the shape-memory element, an further wherein the plateau stress of the shape-memory element is approximately the same as the ultimate tensile strength of the bolt.

26. Method of making a thermally-activated sprinkler valve assembly comprising:

tuning a shape-memory element comprising single-crystal shape memory alloy to exert a pre-determined force at a pre-determined temperature;

forming a temperature-sensitive actuator by coupling a frangible bolt to the shape-memory element so that the shape-memory element is compressed; and

coupling the actuator to a linkage, wherein the linkage is configured to couple with the valve of a fluid passageway having a valved outlet to oppose fluid pressure and maintain the valve closed.

27. The method of claim 26, further comprising connecting the fluid passageway to a fluid source.

28. The method of claim 26, wherein the step of tuning comprises tempering the shape-memory alloy by a heat treatment process that causes controlled partial precipitation of Al.

29. The method of claim 26, further comprising coupling the linkage to the valve of the fluid passageway.

30. The method of claim 26, wherein the step of coupling the actuator to the linkage comprises coupling the actuator between two brackets forming the linkage.

31. The method of claim 26, further comprising matching the plateau stress of the shape-memory element to the ultimate tensile strength of the bolt.