Mechanical assemblies

Patent metadata

Field	Value
Publication number	US-9366277-B2
Application number	US-201314036424-A
Country	US
Kind code	B2
Filing date	Sep 25, 2013
Priority date	Oct 1, 2012
Publication date	Jun 14, 2016
Grant date	Jun 14, 2016

Abstract

A mechanical assembly such as a torque transfer strut for a rotating superconducting machine. The torque transfer strut includes a composite tube having a first end received in a clamping fitting, which may include an end housing or lug, a clamping wedge screwed onto a threaded end housing, and an annular clamping member applying a radial clamping force to the first end of the composite tube at ambient temperature. When cooled, shrinkage of the end housing in the axial direction causes the annular clamping member to maintain or increase radial clamping force, causing the clamping wedge to apply increasing radial force to an inner member deflecting outwardly a plurality of axial fingers. The first end of the composite tube remains clamped between the inner member and an outer member, together defining an annular channel receiving the first end of the composite tube.

First claim

What is claimed is:

1. A mechanical assembly, comprising:
an elongated member having a first end; and
a clamping fitting to apply an outward radial clamping force to the first end of the elongated member when the mechanical assembly is at an ambient temperature, the clamping member including:
an annular clamping member composed of a material having a first coefficient of thermal expansion, with at least an inner member thereof secured to secured to the first end of the elongated member;
an end housing operatively coupled to the annular clamping member, and composed of a material having a second coefficient of thermal expansion different than the first coefficient of thermal expansion; and
a clamping wedge secured to the end housing such that an outer surface thereof is slidably engaged with the inner member of the annular clamping member,

wherein when the mechanical assembly is cooled below ambient temperature, shrinkage of the end housing in the axial direction due to cooling causes the clamping wedge to move towards the first end, thereby pressing the inner member of the clamping member outward so as to substantially maintain or increase the radial clamping force that the clamping fitting applies to the first end of the elongated member.

2. The mechanical assembly according to claim 1 , wherein the elongated member is a tube made of a composite material.

3. The mechanical assembly according to claim 1 , wherein the annular clamping member comprises a radially inner member and a radially outer member spaced apart in a radial direction to define an annular channel into which the first end of the elongated member is received.

4. The mechanical assembly according to claim 3 , wherein the radially inner member comprises a plurality of circumferentially-spaced axial slots that extend from a base part of the annular clamping member and define a plurality of circumferentially-spaced axial fingers.

5. The mechanical assembly according to claim 1 , wherein the end housing comprises a connector part that allows the mechanical assembly to be connected to another component.

6. The mechanical assembly according to claim 1 , wherein the end housing comprises a screw-threaded part.

7. The mechanical assembly according to claim 6 , wherein the clamping wedge has a complementary internal screw thread to be screwed onto the screw-threaded part of the end housing.

8. The mechanical assembly according to claim 7 , wherein the clamping wedge is sized and shaped to be a contact fit within an open annular end of the inner member of the annular clamping member.

9. The mechanical assembly according to claim 7 , wherein one or both of the outer surface of the clamping wedge and an inner surface of the annular clamping member are angled relative to a longitudinal axis of the mechanical assembly such that the clamping wedge applies a progressively increasing radial force to the inner member of the annular clamping member as the clamping wedge moves in a first axial direction relative to the annular clamping member.

10. The mechanical assembly according to claim 9 , wherein the clamping fitting is configured such that when the mechanical assembly is cooled, shrinkage of the end housing causes the clamping wedge to move in the first axial direction relative to the annular clamping member to apply a progressively increasing radial force to the inner member of the annular clamping member.

11. The mechanical assembly according to claim 1 , further comprising one or more bolts received in internally screw-threaded openings in the end housing or an adjustment nut screwed onto an externally screw-threaded part of the end housing.

12. The mechanical assembly according to claim 1 , being a torque transfer strut for a superconducting rotating electrical machine.

13. A method of using a mechanical fitting, the method comprising:
providing a mechanical assembly according to claim 1 at ambient temperature;
selectively adjusting the clamping fitting to apply a radial clamping force to the first end of the elongated member to secure the clamping fitting to the first end of the elongated member; and
cooling the mechanical assembly to below to ambient temperature.

14. The method according to claim 13 , wherein cooling the mechanical assembly comprises cooling the mechanical assembly to a cryogenic temperature.

15. A mechanical assembly, comprising:
an elongated member; and
a clamping fitting to apply a clamping force to the elongated member when the mechanical assembly is at an ambient temperature, the clamping member including:
a clamping member having an inner member and an outer member spaced apart in a radial direction to define an annular channel into which the elongated member is received, the clamping member being composed of a material having a first coefficient of thermal expansion;
an end housing operatively coupled to the clamping member, and composed of a material having a second coefficient of thermal expansion different than the first coefficient of thermal expansion; and
a clamping wedge secured to the end housing such that an outer surface thereof is slidably engaged with the inner member of the clamping member,

wherein when the mechanical assembly is cooled below ambient temperature, shrinkage of the end housing in an axial direction due to cooling causes the clamping wedge to move towards the elongated member, thereby pressing the inner member of the clamping member outward so as to substantially maintain or increase the clamping force that the clamping fitting applies to the elongated member.

Assignees

• Ge Energy Power Conversion Technology Ltd

Inventors

• Ingles Martin Richard
• Eugene Joseph
• Swaffield David John

Classifications

• F16B39/01

  specially adapted to prevent loosening at extreme temperatures · CPC title

• F16B4/00 Primary

  Shrinkage connections, e.g. assembled with the parts at different temperature; Force fits (restricted to metal parts or objects B23P11/02); Non-releasable friction-grip fastenings (F16B2/00 takes precedence) · CPC title

• F16B4/006 Primary

  Shrinkage connections, e.g. assembled with the parts being at different temperature · CPC title

• Y10T403/21

  Utilizing thermal characteristic, e.g. , expansion or contraction, etc. · CPC title