Temperature compensations seal

A temperature-responsive actuator for a sealing assembly comprises first and second annular members each having a camming surface for engagement with one another, the first and second annular members being positioned against each other so that they are nested and together exhibit a height "h" at ambient temperatures, the first annular member having a coefficient of thermal contraction less than the coefficient of thermal contraction of the second annular member so that when the thermal actuator is subjected to temperatures less than ambient temperatures, the first and second annular members contract different amounts such that the "effective" height of the actuator becomes "h+.tangle-solidup.h".

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to thermally responsive sealing assemblies, 
and more particularly to a temperature responsive sealing assembly for 
effecting a fluid tight seal between fluid containing members, the 
assembly including thin nested actuators, each having a unique coefficient 
of thermal contraction and possessing a cam surface positioned for camming 
engagement with a corresponding cam surface on a neighboring actuator for 
altering the overall physical dimensions of the assembly in response to 
temperature changes. 
2. Description of the Related Art 
In the past, a variety of seals capable of functioning effectively at 
ambient temperatures, as temperatures above ambient temperature, were 
well-known. 
However, finding a seal which functioned below, as well as at, ambient 
temperature posed a major problem due to the fact that materials of which 
resilient seals could be composed had characteristics that were 
detrimental to the sealing efficiency as the temperature decreased. 
For example, the shrinking of a sealing ring caused by exposure to extreme 
cold temperatures, as encountered in cryogenic applications where the 
temperatures range well below -200.degree. F. created a tendency for the 
sealing ring to pull away from the walls of the members between which the 
ring was disposed, unless the sealing ring was preloaded into sealing 
engagement with sufficient force to resist the inherent shrinkage. 
However, such preloading was detrimental to the sealing ring when 
operating at ambient temperature or subambient temperature. 
OBJECTS OF THE INVENTION 
In view of the foregoing, it is an object of the present invention to 
provide a sealing assembly having elements which respond to changes in 
temperature to alter the overall physical dimensions of the assembly and 
thereby vary the force which loads surfaces of the sealing assembly 
against a component on which the sealing assembly surfaces bear. 
Another object of the present invention is to provide a seal that is 
responsive to temperature changes such that the seal is initially 
preloaded into sealing engagement with the walls of a component so as to 
effective a seal at an ambient temperature, whereas in response to a 
reduction in temperature the seal is progressively more forcefully loaded 
into sealing contact with the walls of the component. 
Still another object of the present invention is to provide a thermally 
responsive actuator which when exposed to subambient temperatures effects 
an increase in the overall dimensions of the actuator, and which can be 
housed in a jacket configured as, or covered with a material that can be 
used as, a seal, an electrical contact of a switch, or as a means for 
maintaining electrical circuit continuity. 
These and other objects are accomplished through the use of a 
temperature-responsive actuator assembly disposed within a non-metallic 
covering. In one embodiment, the covering comprises a plastic jacket or 
flexible housing. The assembly includes two rings of substantially the 
same diameter, each having a camming surface positioned adjacent the 
other. The two rings are designed to be nested together. Each ring has a 
distinct coefficient of thermal contraction, so that when the nested rings 
are subjected to substantial temperature changes from ambient, the 
individual rings contract at different rates to cause not only a change in 
effective width of the nested rings but also a change in effective height 
of the nested rings. The rings are snugly contained within the housing or 
jacket, so that overall changes in the dimensions of the nested rings 
result in actual changes in the overall dimensions of the housing or 
jacket. Preferably, the housing or jacket includes a resilient ridge or 
protrusion on each of the upper and lower surfaces thereof. This 
configuration thus forces the ridges or protrusions into sealing contact 
with an adjacent component surface when the overall dimensions of the 
assembly changes. 
Alternative embodiments contemplate alternate cross-sections for the 
actuators. Such sectional shapes include tear drop, oval, arcuate, round, 
or semi-circular. 
For electrical applications, the jacket or housing is an electrically 
conductive material, or an electrically conductive coating applied 
directly to and carried by the actuators. Materials useful in this 
application include electrically conductive elastomers and piezoelectric 
materials. 
Other objects, advantages, and novel features of the present invention will 
become apparent from the following detailed description of the invention 
when considered in conjunction with the accompanying drawings.

DETAILED DESCRIPTION OF THE INVENTION 
Referring now to FIG. 1a of the drawings, the temperature-responsive 
actuator mechanism of the sealing assembly of the present invention is 
shown to include a first ring member 20 and a second ring member 30. 
Preferably the first ring member 20 comprises a first material having a 
first coefficient of thermal expansion, while the second ring member 30 
comprises a second material having a different, coefficient of thermal 
expansion. Preferably, the first coefficient of thermal expansion is 
smaller than the second coefficient of thermal expansion. 
Each of the ring members possess an upper surface (22,32), a lower surface 
(24,34), and a camming surface (28,38) disposed on a solid portion (26,36) 
located at the extreme radial region of the respective ring member. As 
shown in FIG. 1a, the solid portion 26 of ring member 20 exhibits a 
triangular cross-section, with a vertical wall 29 being located on the 
inner side of the solid portion 26. The solid portion 36 of ring member 30 
also exhibits a triangular cross-section, with a vertical wall 39 being 
located on the outer side of the solid portion 36. 
Referring now to both FIGS. 1a and 1b, the two ring members 20 and 30 are 
seen to be disposed relative to one another such that the camming surfaces 
28 and 38 are juxtaposed, one with the other, and the two ring members are 
arranged so that one is nested one within the other. In this manner, when 
the ring members are exposed to an ambient temperature environment, they 
are positioned so that the overall diameter of the ring members is 
diameter "d" and the two solid portions combine to form a square section 
of height "h". When the temperature environment is lowered, the upper of 
the ring members contracts at a different rate than the rate of 
contraction of the lower ring member (i.e., as a function of the 
decreasing temperature). The ring members remain in nested relationship, 
but now the camming surfaces of the upper and lower ring members permit 
the lower ring member, which has a greater coefficient of thermal 
contraction, to contract at a faster rate than the upper ring member. 
Thus, the lower ring member camming surface moves under the upper ring 
member camming surface so that the overall "effective" diameter of the 
two, nested, ring members becomes "d-.tangle-solidup.d" and the overall 
"effective" height of the two solid sections becomes 
"h+.tangle-solidup.h". 
The invention contemplates using the annular members shown in FIGS. 1a and 
1b as the temperature-responsive actuator mechanism without more. The ring 
or annular members are configured to be maintained in their nested 
relationship by their interaction with the components that are in proximal 
contact with them. 
FIGS. 2a and 2b illustrate an alternative configuration in which a jacket 
or housing 50 surrounds the ring members and has an upper wall 52 
including a portion covering the solid portions of the ring members, a 
lower wall 56 including a portion covering the solid portions of the ring 
members, and side walls 51 of a height greater than the height "h" of the 
combined ring members when they are at ambient temperature. Disposed on 
the upper and lower wall portions of the housing 52 are upraised 
protrusions 54,58 which are provided for engagement with surfaces of the 
structures located above and below the sealing mechanism. The protrusions 
transfer a greater sealing force to the structure surfaces created by the 
ring members of the actuator mechanism as the temperature is lowered below 
the ambient. 
The upper and lower wall portions of the housing 52 may extend across the 
entire diameter of the ring members as shown in FIG. 2a, or they may 
include an opening located to the interior of the protrusions as shown in 
FIG. 2b. 
In addition, the invention contemplates more than one annular protrusion 
disposed on the upper or the lower surface of the housing 52. Preferably, 
the jacket 52 of the invention comprises a plastic material, such as 
Teflon or filled Teflon, and may comprise an electrically conductive 
polymer, so that the protrusion(s) not only perform a sealing function, 
but also perform the function of making or maintaining electrical contact 
between two conductive components. 
FIG. 3 depicts a variation 60 of the actuator members of the invention 
including the upper ring member which has been replaced with a spring 
element having an overall diameter "d". The spring element includes a 
first circular or annular, substantially horizontal, leg portion 64 and a 
second circular or annular, radially inwardly directed leg portion 66 
which makes an acute angle .varies. with the first annular leg portion. 
The lower ring member is of the same configuration as described for the 
lower ring member shown in FIGS. 1a and 1b, and is comprised of a material 
having a coefficient of thermal contraction greater than that the upper 
spring element. 
FIGS. 4 and 5 illustrate other embodiments of the actuator mechanism of the 
invention. In FIG. 4, the upper and lower ring members 20',30' are nested 
and have cooperating camming surfaces 28',38' of the type and 
configuration shown in FIGS. 1a and 1b. However, in this embodiment, the 
actuator members are used together without a housing or jacket, and the 
ring members themselves are coated with a material layer L which enables 
additional compliance at cryogenic temperatures, as for example, Teflon, 
lead, gold and silver. 
In FIG. 5, the upper and lower ring members 20",30" are nested and include 
cooperating camming surfaces of the type and configuration shown in FIGS. 
1a and 1b. In this embodiment, however, one or both of the members are 
provided with an annular ridge R raised relative to the respective sealing 
surface of the member. The actuator members may be used together without a 
housing or jacket, and the ring members themselves can be coated with a 
material layer L which enables additional compliance at cryogenic 
temperatures, as for example, Teflon, lead, gold and silver. 
The embodiments of FIGS. 3 and 5 make use of the resilient properties of 
the upper annular member to also achieve and/or maintain positive contact 
between the jacket (FIG. 3) or the sealing surface itself (FIG. 5) during 
relative movement between the component surfaces being sealed. The range 
of movements contemplated are within the deflection capabilities of the 
particular spring element used. 
The range of temperatures at which the sealing assembly exhibits its range 
of optimum sealing capabilities is between ambient temperature and 
-459.degree. F. 
Obviously, many modifications and variations of the present invention are 
possible in light of the above teachings. It is therefore to be understood 
that, within the scope of the appended claims, the invention may be 
practiced otherwise than as specifically described.