TEMPERATURE ADAPTIVE RADIAL SHAFT SEAL ASSEMBLIES USING SHAPE MEMORY ALLOY ELEMENTS

• US 20110187054A1
• Filed: 04/11/2011
• Published: 08/04/2011
• Est. Priority Date: 09/28/2006
• Status: Active Grant

• Current Assignee: Alan L. Browne, Chandra S. Namuduri, Nancy L. Johnson
• Original Assignee: Alan L. Browne, Chandra S. Namuduri, Nancy L. Johnson
• Inventors: Browne, Alan L., Johnson, Nancy L., Namuduri, Chandra S.
• Granted Patent: US 8,602,419 B2
• Time in Patent Office: Days
• US Class Current: 277/300
• CPC Class Codes: F16J 15/164 the sealing action depending on movements; pressure difference, temperature or presence of leaking fluid
• CPC Class Codes: F16J 15/3212 with metal springs

Abstract

A dynamic shaft seal assembly for sealing a rotating or reciprocating shaft includes an elastic seal member having at least a portion thereof in sealing communication with the rotating or reciprocating shaft. A shape memory alloy element is in contact with the elastic seal member, the shape memory alloy element being discontinuously disposed about the elastic seal member, and being configured to i) directly apply a compressive force in a radial direction on the seal member against the rotating or reciprocating shaft, and ii) maintain the compressive force on the seal member as a function of temperature. The seal assembly is adapted to seal at a temperature ranging from about −55° C. to about 250° C. Methods including the seal assembly are also disclosed.

Claims

1. A dynamic shaft seal assembly for sealing a rotating or reciprocating shaft, the seal assembly comprising:

an elastic seal member having at least a portion thereof in sealing communication with the rotating or reciprocating shaft; and

a shape memory alloy element in contact with the elastic seal member, wherein the shape memory alloy element is discontinuously disposed about the elastic seal member, and is configured to i) directly apply a compressive force in a radial direction on the seal member against the rotating or reciprocating shaft, and ii) maintain the compressive force on the seal member as a function of temperature;

wherein the seal assembly is adapted to seal at a temperature range from about −

55°

C. to about 250°

C.

2. A method of mounting the dynamic shaft seal assembly of claim 1 onto the shaft, wherein the shaft has an outer diameter larger than an inner diameter of the dynamic shaft seal assembly, the method comprising:

mounting the dynamic shaft seal assembly onto the shaft, wherein the shape memory alloy element is in an austenite phase, wherein mounting the dynamic shaft seal assembly onto the shaft stretches the elastic seal member and the shape memory alloy element to superelastically deform the shape memory alloy element and change the shape memory alloy element to a martensite phase; and

reverting the shape memory alloy element to the austenite phase and a smaller diameter once deforming stresses are removed.

3. The method of claim 2 wherein the shape memory alloy element includes axial portions.

4. A method of sealing the rotating or reciprocating shaft using the dynamic shaft seal assembly of claim 1, the method comprising:

mounting the seal assembly onto the shaft; and

operating the seal assembly in an environment having a temperature differential of at least 50°

C. and at a temperature range from about −

55°

C. to about 250°

C.

5. A method of using the dynamic shaft seal assembly of claim 1, wherein the shaft has an outer diameter larger than an inner diameter of the seal assembly, the method comprising:

mounting the seal assembly onto the shaft, wherein the shape memory alloy element is in an austenite phase, wherein mounting the seal assembly onto the shaft stretches the elastic seal member and the shape memory alloy element, and wherein the shape memory alloy element exhibits a stress induced change to a martensite phase and deforms superelastically;

operating the seal assembly in an environment having a temperature differential of at least 50°

C. and at a temperature range from about −

55°

C. to about 250°

C.; and

maintaining a constant sealing force over a range of moduli exhibited by the elastic seal member.

6. A dynamic shaft seal assembly for sealing a rotating or reciprocating shaft, the seal assembly comprising:

an elastic seal member having at least a portion thereof in sealing communication with the rotating or reciprocating shaft; and

a shape memory alloy element in contact with the elastic seal member, wherein the shape memory alloy element has a geometry selected from a crown shape or a sinusoidal shape, and is configured to i) directly apply a compressive force in a radial direction on the seal member against the rotating or reciprocating shaft, and ii) maintain the compressive force on the seal member as a function of temperature;

wherein the seal assembly is adapted to seal at a temperature range from about −

55°

C. to about 250°

C.

7. A method of mounting the dynamic shaft seal assembly of claim 6 onto the shaft, wherein the shaft has an outer diameter larger than an inner diameter of the seal assembly, the method comprising:

mounting the dynamic shaft seal assembly onto the shaft, wherein the shape memory alloy element is in an austenite phase, wherein mounting the seal assembly onto the shaft stretches the elastic seal member and the shape memory alloy element to superelastically deform the shape memory alloy element and change the shape memory alloy element to a martensite phase; and

reverting the shape memory alloy element to the austenite phase and a smaller diameter once deforming stresses are removed.

8. The method of claim 7 wherein the shape memory alloy element includes axial portions.

9. A method of sealing the rotating or reciprocating shaft using the dynamic shaft seal assembly of claim 6, the method comprising:

mounting the seal assembly onto the shaft; and

operating the seal assembly in an environment having a temperature differential of at least 50°

C. and at a temperature range from about −

55°

C. to about 250°

C.

10. A method of using the dynamic shaft seal assembly of claim 6, wherein the shaft has an outer diameter larger than an inner diameter of the seal assembly, the method comprising:

mounting the seal assembly onto the shaft, wherein the shape memory alloy element is in an austenite phase, wherein mounting the seal assembly onto the shaft stretches the elastic seal member and the shape memory alloy element, wherein the shape memory alloy element exhibits a stress induced change to a martensite phase and deforms superelastically;

operating the seal assembly in an environment having a temperature differential of at least 50°

C. and at a temperature range from about −

55°

C. to about 250°

C.; and

maintaining a constant sealing force over a range of moduli exhibited by the elastic seal member.

11. A dynamic shaft seal assembly for sealing a rotating or reciprocating shaft, the seal assembly comprising:

an elastic seal member having at least a portion thereof in sealing communication with the rotating or reciprocating shaft; and

a shape memory alloy element in contact with the elastic seal member, wherein the shape memory alloy element comprises a plurality of wires circumferentially disposed about the portion of the elastic seal member, each of the plurality of wires having a different transformation temperature configured to increase a stiffness of the elastic seal member in steps as temperature is increased, and is configured to i) directly apply a compressive force in a radial direction on the seal member against the rotating or reciprocating shaft, and ii) maintain the compressive force on the seal member as a function of temperature;

wherein the seal assembly is adapted to seal at a temperature range from about −

55°

C. to about 250°

C.

12. A method of mounting the dynamic shaft seal assembly of claim 11 onto the shaft, wherein the shaft has an outer diameter larger than an inner diameter of the seal assembly, the method comprising:

mounting the dynamic shaft seal assembly onto the shaft, wherein the shape memory alloy element is in an austenite phase, wherein mounting the seal assembly onto the shaft stretches the elastic seal member and the shape memory alloy element to superelastically deform the shape memory alloy element and change the shape memory alloy element to a martensite phase; and

reverting the shape memory alloy element to the austenite phase and a smaller diameter once deforming stresses are removed.

13. The method of claim 12 wherein the shape memory alloy element includes axial portions.

14. A method of sealing the rotating or reciprocating shaft using the dynamic shaft seal assembly of claim 11, the method comprising:

mounting the seal assembly onto the shaft; and

operating the seal assembly in an environment having a temperature differential of at least 50°

C. and at a temperature range from about −

55°

C. to about 250°

C.

15. A method of using the dynamic shaft seal assembly of claim 11, wherein the shaft has an outer diameter larger than an inner diameter of the seal assembly, the method comprising:

mounting the seal assembly onto the shaft, wherein the shape memory alloy element is in an austenite phase, wherein mounting the seal assembly onto the shaft stretches the elastic seal member and the shape memory alloy element, wherein the shape memory alloy element exhibits a stress induced change to a martensite phase and deforms superelastically;

operating the seal assembly in an environment having a temperature differential of at least 50°

C. and at a temperature range from about −

55°

C. to about 250°

C.; and

maintaining a constant sealing force over a range of moduli exhibited by the elastic seal member.