Temperature adaptive radial shaft seal assemblies using shape memory alloy elements

Abstract

A dynamic radial shaft assembly and methods of use for rotating or reciprocating shafts include 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 adapted to change a shape orientation and or modulus property as a function of temperature change so as to change or maintain a compressive force and/or sealing area of the seal member portion against the rotating or reciprocating shaft at temperatures from −55° C. to about 250° C.

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 adapted to change a shape orientation and/or modulus property as a function of temperature change so as to change or maintain a compressive force and/or sealing area of the seal member against the rotating or reciprocating shaft at temperatures from −55° C. to about 250° C.   
     
     
         2 . The dynamic shaft seal assembly of  claim 1 , wherein the shape memory alloy element is discontinuously disposed about the elastic seal member. 
     
     
         3 . The dynamic shaft seal assembly of  claim 1 , further comprising a dust lip extending from the elastic seal member and contacting the rotating or reciprocating shaft. 
     
     
         4 . The dynamic shaft seal assembly of  claim 1 , wherein the elastic seal member is formed of an elastomer. 
     
     
         5 . The dynamic shaft seal assembly of  claim 1 , further comprising a rigid casing in structural communication with the elastic seal member. 
     
     
         6 . The dynamic shaft seal assembly of  claim 5 , wherein the rigid casing includes an axial portion and a radial portion. 
     
     
         7 . The dynamic shaft seal assembly of  claim 1 , wherein the shape memory alloy element is seated within a recess at about the portion of the elastic seal member in sealing communication with the rotating or reciprocating shaft. 
     
     
         8 . The dynamic shaft seal assembly of  claim 1 , wherein the shape memory element includes axial portions. 
     
     
         9 . The dynamic shaft seal assembly of  claim 1 , wherein the shape memory alloy element comprises a plurality of wires having different transformation temperatures, wherein the wires are circumferentially disposed about the portion of the elastic seal member in sealing communication with the rotating or reciprocating shaft. 
     
     
         10 . A temperature adaptive seal, comprising:
 an elastomeric seal body; and   a shape memory alloy element in compressive contact with the elastomeric seal body, wherein the shape memory alloy element is adapted to change a shape orientation and/or modulus property as a function of temperature change so as to change or maintain the compressive contact force and/or sealing area of the seal member portion against a component when the component is exposed to ambient temperatures of about −55° C. to about 250° C.   
     
     
         11 . The temperature adaptive seal of  claim 10 , wherein the shape memory alloy element is discontinuously disposed about the elastomeric seal body. 
     
     
         12 . The temperature adaptive seal of  claim 10 , wherein the elastomeric seal body defines a selected one of an O-ring, a V-ring, and U-ring. 
     
     
         13 . The temperature adaptive seal of  claim 10 , wherein the shape memory alloy element is embedded within the elastomeric body. 
     
     
         14 . A method of mounting a radial shaft seal assembly onto a shaft, wherein the shaft has an outer diameter larger than an inner diameter of the seal assembly, the method comprising:
 mounting a seal assembly onto the shaft, the seal assembly comprising a shape memory element in compressive communication with an elastic seal body portion, wherein the shape memory element is in an austenite phase, wherein mounting the seal assembly onto the shaft stretches the elastic seal body portion and the shape memory alloy element to superelastically deform the shape memory element and change to a martensite phase; and   reverting to the austenite phase and a smaller diameter once the deforming stresses are removed.   
     
     
         15 . The method of  claim 14 , wherein the shape memory alloy element comprises a plurality of wires having different transformation temperatures, wherein the wires are circumferentially disposed about the portion of the elastic seal member in sealing communication with the shaft. 
     
     
         16 . The method of  claim 14 , wherein the shape memory element includes axial portions. 
     
     
         17 . A method of sealing a rotatable or reciprocating shaft, comprising:
 mounting a seal assembly onto the shaft, the seal assembly comprising a shape memory element in compressive communication with an elastic seal body portion, wherein the shape memory alloy element is adapted to change a shape orientation and or modulus property as a function of temperature change so as to change or maintain a compressive force and/or sealing area of the seal member portion against the rotating or reciprocating shaft; and   operating the seal assembly in an environment having a temperature differential of at least 50° C. and within a temperature range of about −55° C. to about 250° C.   
     
     
         18 . The method of  claim 17 , wherein the shape memory alloy element comprises a plurality of wires having different transformation temperatures, wherein the wires are circumferentially disposed about the portion of the elastic seal member in sealing communication with the rotating or reciprocating shaft. 
     
     
         19 . The method of  claim 17 , wherein the shape memory element includes axial portions. 
     
     
         20 . The method of  claim 17 , wherein the shape memory element is discontinuously disposed about the elastic seal body portion. 
     
     
         21 . A method of mounting a radial shaft seal assembly onto a shaft, wherein the shaft has an outer diameter larger than an inner diameter of the seal assembly, the method comprising:
 mounting a seal assembly comprising a shape memory element in compressive communication with an elastic seal body portion, wherein the shape memory element is in an austenite phase, wherein mounting the seal assembly onto the shaft stretches the elastic seal body portion and the shape memory alloy element, wherein the shape memory element exhibits a stress induced change to the martensite phase and deforms superelastically; and   maintaining a constant sealing force over a range of moduli exhibited by the elastic seal body portion.   
     
     
         22 . The method of  claim 21 , further comprising operating the seal assembly in an environment having a temperature differential of at least 50° C. and
 within a temperature range of about −55° C. to about 250° C.