A seal assembly capable of low temperature service is disclosed. It features upper and lower metallic backup rings that are specially shaped to act as a spring to keep the sidewalls of such rings in contact with the inside and outside surfaces to be sealed to prevent extrusion of the seal material even in low temperature situations. Inner and outer grooves are provided. O-ring seals, used for the ID of the seal, are manufactured to have a slightly greater diameter than the groove into which they will be installed. The greater length provides stored energy to promote sealing functionality in cold temperature situations. The O-rings used for the OD of the seal are manufactured to have a slightly smaller diameter than the groove into which they will be installed. The shorter length provides stored energy to promote sealing functionality in cold temperature situations.
1. A seal assembly for closing off an annular space between a first and second body and supported by at least one of said first and second bodies, comprising:
an annularly shaped body having an upper and a lower end and a longitudinal axis; and
at least one backup ring mounted on one of said ends of said body and having a relaxed dimension greater than the annular space between said first and second bodies so that opposed ends on said backup ring must be compressed to be inserted in the annular space, said backup ring further comprising a bend between said opposed ends to store a force created by insertion of said backup ring into the annular space and apply said force on said opposed ends against said first and second bodies;
said body comprises at least one first ring in a first groove, said first groove having a bottom and a first circumference at said bottom;
the circumference of said first ring at a location nearest said first circumference of said first groove differs before mounting from said first circumference of said first groove so as to apply a net radial force to said body in a direction substantially perpendicular to said longitudinal axis.
2. The assembly of claim 1 , wherein:
said first ring, when placed in contact with one of said first and second bodies, deforms said first groove to force said ends of said backup ring away from each other.
3. The assembly of claim 1 , wherein:
said first ring circumference is in the range of at least about 8-15% different from said groove in which it is installed.
4. The assembly of claim 1 , wherein:
said first ring is made from a material having a Durometer hardness of about 56-85.
5. The assembly of claim 1 , wherein:
said first ring contacts the one of said first and second bodies with the larger dimension;
said first ring, when said body is installed in the annular space, is in an interference fit with said one of said first and second bodies to an extent of at least about 20% of the cross-sectional diameter of said first ring.
6. The assembly of claim 5 , wherein:
said first ring is made from a material having a Durometer hardness of about 56-85.
7. The assembly of claim 1 , wherein:
said body further comprises at least one second ring in a second groove disposed on the opposite side of said body from said first ring;
said second ring contacts the one of said first and second bodies with the larger dimension;
said second ring, when said body is installed in the annular space, is in an interference fit with said one of said first and second bodies to an extent of at least about 20% of the cross-sectional diameter of said second ring.
8. The assembly of claim 7 , wherein:
said first ring is made from a material having a Durometer hardness of about 56-85.
9. The assembly of claim 2 , wherein:
said body has a longitudinal axis and said deformation results in said first ring deforming into an undulating wave pattern in an axial direction parallel to said longitudinal axis.
10. A seal assembly for closing off an annular space between a first and second body and supported by at least one of said first and second bodies, comprising:
an annularly shaped body having an upper and a lower end and a longitudinal axis;
said body comprises at least one first ring in a first groove, said first groove having a bottom and a first circumference at said bottom;
the circumference of said first ring at a location nearest said first circumference of said first groove differs before mounting from said first circumference of said first groove so as to apply a net radial force to said body in a direction substantially perpendicular to said longitudinal axis.
11. The assembly of claim 10 , wherein:
said first ring circumference is in the range of at least about 8-15% different from said groove in which it is installed.
12. The assembly of claim 11 , wherein:
said body further comprises at least one second ring in a second groove disposed on the opposite side of said body from said first ring;
said second ring, when said body is installed in the annular gap, is in an interference fit with said one of said first and second bodies to an extent of at least about 20% of the cross-sectional diameter of said second ring.
13. The assembly of claim 12 , wherein:
said first and second rings are made from a material having a Durometer hardness of about 56-85.
14. The assembly of claim 13 , further comprising:
at least one backup ring mounted on one of said ends of said body and having a relaxed dimension greater than the annular gap between said first and second bodies so that opposed ends on said backup ring must be compressed to be inserted in the annular gap, said backup ring further comprising a bend between said opposed ends to store a force created by insertion of said backup ring into the annular space and apply said force on said opposed ends against said first and second bodies.
15. The assembly of claim 14 , wherein:
said first ring, when placed in contact with one of said first and second bodies, deforms in a manner so as to force said ends of said backup ring away from each other.
16. The assembly of claim 15 , wherein:
said first ring contacts the one of said first and second bodies with the smaller dimension;
said body has a longitudinal axis and said deformation results in said first ring deforming into an undulating wave pattern in an axial direction parallel to said longitudinal axis.
17. The assembly of claim 1 , wherein:
said first ring is softer than said body.
18. The assembly of claim 10 , wherein:
said first ring is softer than said body.
19. A seal assembly for sealing an annular space between first and second bodies, comprising:
an annularly shaped body having first and second ends, and at least one notched portion disposed between the first and second ends;
at least one backup ring disposed on one of the first or second ends, the backup ring comprising:
a pair of loop ends extending toward the annularly shaped body and configured to secure the backup ring to the annularly shaped body;
an inflected portion located between the loop ends and in abutment with the annularly shaped body, wherein the inflected portion facilitates elastic deformation of the backup ring; and
a sealing ring disposed in the notched portion of the annular body and configured to provide a biasing force in a radially inward direction with respect to the annular body.