Composite metallic elastomeric sealing components for roller cone drill bits
View Patent ↗An earth boring bit has a bit body with a depending bearing pin, a cone rotatably mounted on the bearing pin, a seal gland between the cone and the bearing pin, and a seal assembly located in the seal gland. The seal assembly includes an annular metallic spring encircling the bearing pin. The spring has a geometric center line that extends in a circle around the bearing pin. The spring is elastically deformable in radial directions relative to the center line. An elastomeric layer is located on an exterior side of the spring and is biased by the spring against a surface of the seal gland.
1. A downhold well tool, comprising:
an inner member located within an outer member, one of the members being rotatable relative to the other of the members;
an annular seal gland located between the members;
a seal assembly locataed in the seal gland comprising;
an annular metallic spring, the spring having a cross section with a substantially constant inner radius from a geometric center line, the geometric centerline extending in a circle around the inner member, the spring being elastically deformable such that when installed in the seal gland, it will exert oppositely directed forces along radial lines from the center line; and
an elastomeric layer located on an exterior surface of the spring and being biased by the spring against a surface of the seal gland;
an annular gap formed in the spring and the elastomeric layer and extending completely around a circumference of the spring and the elastomeric layer, enabling the spring and the elastomeric layer to be resiliently squeezed to smaller diameters and narrowing the gap; wherein
an entire exterior surface of the elastomeric layer has a substantially constant radius from the geometric center line of the spring;
the spring is formed of a resilient material; and
the spring has a pre-installation inner diameter and an installed inner diameter when installed in the seal gland, the installed inner diameter being smaller than the pre-installation inner diameter, and wherein the installed inner diameter is substantially constant.
2. The well tool according to claim 1 , wherein the spring comprises a tube formed into annular configuration when viewed in a top view.
3. The well tool according to claim 1 , wherein the spring comprises:
a tube formed into a continuous annular configuration; and
a plurality of transverse slits formed in the tube transverse to the geometric center line, the transverse slits being circumferentially spaced apart from each other around the tube.
4. The well tool according to claim 1 , wherein the seal assembly further comprises:
a stationary and a rotating rigid face seal, one of the rigid face seals being mounted to one of the members for rotation therewith, and the other being mounted to the other of the members; and
the spring comprises an energizing member mounted in engagement with one of the rigid face seals for urging it into sealing engagement with the other rigid face seal.
5. A downhole well tool, comprising:
an inner member located within an outer member, one of the members being rotatable relative to the other of the members;
an annular seal gland between the members;
a seal assembly located in the seal gland, comprising:
an annular spring of a resilient, metallic material encircling the inner member, the spring having a tubular cylindrical configuration with a cylindrical interior surface and a cylindrical exterior surface;
an elastomeric layer bonded to the exterior surface of the spring and biased by the spring against a surface of the seal gland;
an annular gap formed in and extending completely around an annular circumference of the spring and of the elastomeric layer, enabling the cylindrical configuration of the spring to be resiliently squeezed to a smaller diameter; wherein
the elastomeric layer having a constant thickness around an entire extent of the circumference of the spring from one edge of the gap to an opposite edge of the gap; and
the spring has a pre-installation inner diameter and an installed inner diameter when installed in the seal gland, the installed inner diameter being smaller than the pre-installation inner diameter, and wherein the installed inner diameter is substantially constant.
6. The well tool according to claim 5 , further comprising a plurality of transverse slits in the spring, the slits being circumferentially spaced apart from each other around the spring.
7. The well tool according to claim 6 , wherein the elastomeric layer fills each of the transverse slits.
8. The well tool according to claim 5 , wherein the elastomeric layer on one part of the exterior surface has a different composition from the elastomeric layer on another part of the exterior surface.
9. The well tool according to claim 5 , wherein the seal assembly comprises a primary seal having one part of the elastomeric layer in sliding and sealing contact with one of the members and another part of the elastomeric layer in stationary sealing contact with the other of the members for rotation therewith.
10. The well tool according to claim 5 , wherein the seal assembly comprises:
a stationary and a rotating rigid face seal, one of the rigid face seals being mounted to one of the members for rotation therewith and the other to the other member; and
the spring comprises an energizing member biased against one of rigid face seals and urging it into sealing and sliding engagement with the other rigid face seal.