GB2431704A

GB2431704A - Removable hirth coupling

Info

Publication number: GB2431704A
Application number: GB0521787A
Authority: GB
Inventors: David J Abrahamian
Original assignee: Cooper Cameron Corp
Current assignee: Cameron International Corp
Priority date: 2005-10-26
Filing date: 2005-10-26
Publication date: 2007-05-02
Anticipated expiration: 2025-10-26
Also published as: GB2431704B; GB0521787D0

Abstract

An end element 20 for rotating equipment that is driven through a Hirth coupling 12,24 is manufactured independently of the Hirth coupling halves. In that manner, in the event maintenance or repair is required to the Hirth coupling halves 12,24 or the end element such as a turbine wheel or compressor impeller 20, only the structure needing maintenance or repair needs to be worked on rather than the entire assembly. End elements that previously came integrated to a half of a Hirth coupling can be retrofitted to mount a removable Hirth coupling half. In the process of machining away material from the end element to reduce running stresses, a boss can be created to mount the Hirth coupling half.

Description

REPLACEABLE HIRTH COUPLING COMPONENT

The field of this invention is the application of a Hirth coupling to drive rotating equipment and more particularly where the coupling components are made separately from the connected structures.

Hirth couplings feature form-locking teeth to safely transfer high torque without relying on friction between the contacting tooth surfaces. The serrations in a Hirth coupling are precisely machined with an orientation to the shaft centerline. Hirth couplings are used in high speed centrifugal compressors and in generator drives. In the past an impeller for a particular stage in a multistage compressor, for example had been machined as a single component from the impeller at one end to the Hirth coupling half at the other end. When wear or other service problems occurred with the Hirth coupling half integral to the impeller, the possibility existed for the entire impeller and integral coupling half requiring to be remanufactured at very high cost and very long lead time.

What was needed was a way to make the Hirth coupling halves independent from the driving and driven structures with which they interact. By doing that an inventory of Hirth couplings could be economically maintained for a variety of end use applications.

When a driven component needed repair, such repair becomes an independent event from the Hirth coupling halves. Additionally the driven component becomes simpler to design.

Existing integral assemblies can be retrofit for a separable Hirth coupling and the impeller can be reconfigured to reduce stresses and deformation at the blades. In so doing a boss can be created to retrofit a Hirth coupling half for a simplified assembly process.

These and other aspects of the present invention will become more apparent to those skilled in the art from a review of the description of the preferred embodiment and the claims, which appear below.

An end element for rotating equipment that is driven through a Hirth coupling is manufactured independently of the Hirth coupling halves. In that manner, in the event maintenance or repair is required to the Hirth coupling halves or the end element such as a turbine wheel or compressor impeller, only the structure needing maintenance or repair needs to be worked on rather than the entire assembly. End elements that previously came integrated to a half of a Hirth coupling can be retrofitted to mount a removable Hirth coupling half. In the process of machining away material from the end element to reduce running stresses, a boss can be created to mount the Hirth coupling half.

Figure 1 is a section view showing the Hirth coupling as a separate structure from the impeller that it drives.

Figure 1 shows a shaft 10 to which is connected a Hirth coupling half 12. A bore 14 is preferably shrink fit to a boss 16 on shaft 10. Thereafter bore 14 receives one or more pins that extend into boss 16 and bore 14 to hold the coupling half 12 in position on shaft 10.

An end element such as an impeller 20 is shown with a boss 22 that can be part of the original manufacture or a retrofit of an existing part. Coupling half 24 has a bore 26 that can be shrink fit over boss 22 and secured with one or more pins extending parallel to bore 26 and boss 22. Adjacent the boss 22 material is removed along a series of curved surfaces referred to generally as to limit stresses in the impeller 20 and/or to reduce its weight. In a retrofit application the removal of material to create the shape 30 also lends itself to the provision of a boss 22 onto which the I-Iirth coupling half 24 is mounted.

The advantage of being able to separate the Mirth coupling from the driver and driven component means lower initial manufacturing costs. It is simpler to manufacture these components separately because they each are smaller and specialty equipment use may be avoided in the manufacturing process allowing the components to be made at more facilities for a lower cost and a shorter delivery time. Existing integral assemblies of a driven component and a Hirth coupling half can be more quickly and economically repaired. If the Hirth coupling has failed do to fretting, a type of corrosion, or for any other reason, it can be cut off and the back end of the impeller 20 can be reconfigured to include the curved profile 30 and a boss 22 for mounting a Hirth coupling that can now be kept in storage because it can be applied to many different uses. This assembly of components described above does away with the need to manufacture unique assemblies of end elements and a Hirth coupling half integral with it. The overall cost is reduced as is delivery time. It is also simpler to perform the stress analysis on a single end component if it doesn't have the Hirth coupling half built into it integrally.

The foregoing disclosure and description of the invention are illustrative and explanatory thereof, and various changes in the size, shape and materials, as well as in the details of the illustrated construction, may be made.

Claims

CLAIMS

1. A rotating equipment assembly, comprising: a Hirth coupling having two engaging halves; an end component separately constructed and connected to one of said engaging halves.

2. The assembly of claim I, wherein: said engaging half is a shrink fit to said end component.

3. i'he assembly of either of claims I or 2, wherein: said engaging half is pinned to said end component.

4. The assembly of any preceding claim, wherein: said end component comprises a boss and said engaging half is mounted to said boss.

5. The assembly of claim 4, wherein: said engaging half is shrink fit to said boss.

6. The assembly of either of claims 4 or 5, wherein: said engaging half is pinned to said boss.

7. The assembly of any preceding claim, wherein: said end component is initially made integrally with one of said engaging halves and is then modified to produce a boss onto which a replacement engaging half can be mounted.

8. The assembly of any preceding claim, wherein: said engaging half is removably mounted to said end component.

9. The assembly of any of claims 4 to 6, wherein: said engaging half is removably mounted to said boss.

10. The assembly of claim 7, wherein: said engaging half is removably mounted to said boss.

11. The assembly of any of claims 4 to 6, wherein: said end component further comprises at least one curved surface extending from said boss.

12. The assembly of claim 7, wherein: said end component further comprises at least one curved surface extending from said boss.

13. A rotating equipment assembly substantially as hereinbefore described having reference to the accompanying figure.

14. A Hirth coupling substantially as hereinbefore described having reference to the accompanying figure.