Seals and method of manufacture thereof

Abstract

A method of manufacture of an annular seal element comprises the steps of providing an apertured backing ring with closely packed bristles extending radially outwardly from the circumference thereof, clamping the free ends of the bristle between a pair of co-axial rings and welding the rings and the outermost tips of the bristles into a unitary structure and subsequently machining away the original backing ring to leave the rings with radially inwardly extending bristles. The invention also includes a sealing element made by the method.

We claim: 
     
       1. A method of manufacturing a seal element comprising the steps of making a brush having a plurality of tightly packed bristles secured to and projecting from a surface of a backing member, clamping the free ends of the bristles between a pair of clamping members, integrally .[.joining.]. .Iadd.fusing .Iaddend.the clamping members and the tips of the bristles, and subsequently removing the backing member and the ends of the bristles attached thereto. 
     
     
       2. A method according to claim 1 and in which the bristles and clamping rings are metallic and are integrally .[.joined.]. .Iadd.fused .Iaddend.by welding, brazing of diffusion bonding. 
     
     
       3. A method according to claim 1 and wherein the bristles are made to project at an angle to the surface of the backing member, whereby in the finished seal element, the bristles project at an angle from the clamping members. 
     
     
       4. A method according to claim 1 and wherein the backing member is annular and the bristles project radially from the radially inner circumferential surface thereof, and the clamping members are co-axial rings which clamp the free radially outer ends of the bristles whereby the resulting seal element is annular and has radially inwardly extending bristles. 
     
     
       5. A method according to claim 1 and wherein the backing member is annular and the bristles project radially from the radially outer circumferential surface thereof, and the clamping members are co-axial rings which clamp the free radially outer ends of the bristles whereby the resulting seal element is annular and has radially inwardly extending bristles. 
     
     
       6. A seal element manufactured by the .[.method according to claim 1.]. .Iadd.steps comprising making a brush having a plurality of tightly packed bristles secured to and projecting from a surface of a backing member, clamping the free ends of the bristles between a pair of clamping members, integrally fusing the clamping members and the tips of the bristles and subsequently removing the backing member and the ends of the bristles attached thereto.Iaddend.. .Iadd. 7. A gas sealing element for reducing leakage of gas between two parts of a fluid flow machine, said element comprising an annular array of tightly-packed bristles sandwiched between a pair of side-plates and integrally fused therewith, said bristles projecting from between the side-plates with a circumferential component of direction. .Iaddend..Iadd. 8. A gas sealing element as claimed in claim 7, and in which the side-plates are annular and the bristles project in a generally radial direction. .Iaddend. .Iadd. 9. A gas sealing element as claimed in claim 8 and in which one of the side-plates has a greater radial depth than the other. .Iaddend..Iadd. 10. A gas sealing element as claimed in claim 9 and in which the bristles project radially inwardly from the inner circumferential side edges of the side-plates. .Iaddend. .Iadd. 11. A gas sealing element as claimed in claim 10 and in which the bristles are metallic. .Iaddend..Iadd. 12. A gas sealing element as claimed in claim 11 and in which the bristles are welded to the side-plates at the radially outer circumferential side edges of the side-plates. .Iaddend..Iadd. 13. A gas sealing element as claimed in claim 9 and in which the bristles project radially outwardly from the outer circumferential side edges of the side-plates. .Iaddend. .Iadd. 14. A combination of a gas sealing element and a fluid flow machine, the gas sealing element for reducing leakage of gas between two parts of the fluid flow machine, said sealing element comprising that claimed in claim 7 wherein the side plates are connected to one of the parts and the bristles extend into contiguous relationship with the other of the parts to effect a seal. .Iaddend. .Iadd. 15. A combination as claimed in claim 14 and in which one of the parts is rotatable, and the other part is static, the sealing element being connected to the static part, with the bristles oriented in the direction of rotation of the rotating part. .Iaddend..Iadd. 16. A combination as claimed in claim 15 and in which the sealing element is annular, and the bristles project in a generally radial direction from the entire circumference thereof. .Iaddend..Iadd. 17. A combination as claimed in claim 16 and in which the rotatable part includes a circumferential flange, and said bristles extend into contiguous relationship with said flange. .Iaddend..Iadd. 18. A combination as claimed in claim 17 and in which the bristles extend generally radially inwardly from said static part. .Iaddend..Iadd. 19. A combination as claimed in claim 17 and in which the bristles extend generally radially outwardly from said static part. .Iaddend..Iadd. 20. A combination as claimed in claim 16 and in which one of the side-plates has a greater radial depth than the other for thereby resisting flexing of the bristles due to a pressure difference across the seal. .Iaddend..Iadd. 21. A combination as claimed in claim 14 and in which the bristles are metallic. .Iaddend. .Iadd. 22. A gas turbine apparatus including two parts across which exists a gas pressure difference, and a gas seal for reducing leakage of gas between the two parts said seal comprising a sealing element as claimed in claim 7 wherein the side plates are connected to one of the parts and the bristles extend into contiguous relationship with the other of the parts to effect a seal. .Iaddend. .Iadd. 23. A gas turbine apparatus as claimed in claim 22 and in which one of the two parts is rotatable, and the other part is static, the sealing element being connected to the static part, with the bristles oriented in the direction of rotation of the rotating part. .Iaddend..Iadd. 24. A gas turbine apparatus as claimed in claim 23 and in which the sealing element is connected to the static part, the rotatable part includes a circumferential flange, and said bristles extend into contiguous relationship with said flange. .Iaddend..Iadd. 25. A gas turbine apparatus as claimed in claim 24 and in which the bristles extend generally radially outwardly from the static part. .Iaddend..Iadd. 26. A gas turbine apparatus as claimed in claim 24 and in which the bristles extend generally radially outwardly from the static part. .Iaddend..Iadd. 27. A gas turbine apparatus as claimed in claim 22 and in which one of the side-plates extends further along the lengths of the bristles towards the free ends thereof than the other side-plate for resisting flexing of the bristles under said pressure difference. .Iaddend..Iadd. 28. A gas turbine apparatus as claimed in claim 27 and in which the bristles are metallic. .Iaddend.