FORM 2
THE PATENTS ACT, 1970
(39 OF 1970)
As amended by the Patents (Amendment) Act, 2005
&
The Patents Rules, 2003
As amended by the Patents (Amendment) Rules, 2006
COMPLETE SPECIFICATION
(See section 10 and rule 13)
TITLE OF THE INVENTION
Circuit interrupter
APPLICANTS
Crompton Greaves Limited, CG House, Dr Annie Besant Road, Worli, Mumbai 400 030, Maharashtra, India, an Indian Company
INVENTORS
Jamdhade Gaurav of Crompton Greaves Ltd, S3 Division.. Switchgear Complex, Ambad, Nashik, Maharashtra, India, Indian National
PREAMBLE TO THE DESCRIPTION
The following specification particularly describes the nature of this invention and the manner in which it is to be performed.

FIELD OF INVENTION
This invention relates to a circuit interrupter. More specifically, the present invention relates to a circuit interrupter housing having an integrally formed body.
BACKGROUND OF INVENTION
A circuit interrupter comprises a movable contact and a fixed contact operatively connected through a collapsible mechanical linkage, where the mechanical linkage guides the movement of the movable contact against the fixed contact to establish an electric connection therein. Example of collapsible mechanical linkage includes, but is not limited to, a scissor linkage assembly.
A typical circuit interrupter housing comprises a movable contact holding pipe and a fixed contact holding portion joined together through a threaded connection. The movable contact holding pipe comprises a hollow cylindrical body and the fixed contact holding portion comprises a central hole and a pair of aligned linkage holders on opposite sides of the central hole.
When the movable contact holding pipe and the fixed contact holding portion are fastened together through a threaded connection, the fixed contact may be disposed in the central hole, the movable contact assembly may be disposed at an end of the hollow cylindrical body, two ends of a scissor linkage assembly may be attached to the movable contact assembly and other ends may be pivoted to the pair of linkage holders. Operationally, when the movable contact moves towards the fixed contact, the scissor linkage assembly collapses, and vice versa.
The fixed contact holding portion and the movable contact holding pipe are individually designed in such a manner that they become concentric when joined together. The concentricity between them is essential to maintain proper alignment between the

movable and fixed contacts. However, when the fixed contact holding portion and the movable contact holding pipe are joined through a threaded connection, there is a possibility that they remain non-concentric and the scissor link mounting position may not be achieved. When they are non-concentric and the scissor link mounting position not achieved, the fixed and movable contacts become misaligned and there is a possibility that the scissor link assembly hit the walls of movable contact pipe.
To avoid non-concentricity between the fixed contact holding portion and the movable contact holding pipe, there have been attempts to weld the two. However, the welding distorts the shape of the movable contact holding pipe, resulting into further lack of concentricity.
In addition to lack of concentricity, manufacturing two pieces of interrupter housing and then joining them is time consuming and expensive. Further, a housing with a joint has less strength as compared to a joint less housing. However, it is difficult to cast the fixed contact holding portion and the movable contact holding pipe in single piece due to the precision required in creating central hole and the pair of linkage holders in the fixed contact holding portion.
Therefore, there is a need for a circuit interrupter housing which is inexpensive, takes less time in manufacturing and should have proper concentricity between the stationary contact holding portion and the movable contact holding portion.
OBJECTS OF INVENTION
An object of invention is to provide a circuit interrupter having proper concentricity between the fixed contact holding portion and the movable contact holding portion.

Another object of the invention is to provide a circuit interrupter having a joint less movable contact holder.
Yet another object of the invention is to provide a circuit interrupter which is cost effective.
Yet another object of the invention is to provide a movable contact holder takes less time in manufacturing.
DETAILED DESCRIPTION OF THE INVENTION
According to the invention, there is provided a circuit interrupter comprising a housing enclosing a fixed contact and a movable contact operatively coupled together through a collapsible mechanical linkage, the housing comprising an integrally formed body having a movable contact holding portion and a fixed contact holding portion disposed in a spaced apart relationship with each other and joined together by at least a pair of spaced ribs, the fixed contact holding portion comprising a means for holding the fixed contact and means for holding the mechanical linkage at an inner surface thereof and the movable contact holding portion comprising a through opening at the center thereof for housing the movable contact.
Preferably, the means for holding the fixed contact comprises a central hole concentric with the through opening and the means for holding the collapsible mechanical linkage comprises a pair of aligned linkage holders on opposite sides of the central hole.
Preferably, the integrally formed body is made by making an intermediate housing through metal casting and machining the intermediate housing to form the central hole and the pair of aligned linkage holders.
Preferably, the collapsible mechanical linkage comprises a scissor linkage assembly.

These and other aspects, features and advantages of the invention will be better understood with reference to the following detailed description, accompanying drawings and appended claims, in which,'
Fig 1 illustrates an isometric view of housing of a circuit interrupter in accordance with an embodiment of the present invention;
Fig. 2 illustrates an isometric view of an intermediate housing of the circuit interrupter in accordance with an embodiment of the present invention;
Fig. 3 illustrates an isometric view of arrangement of contacts and scissor link assembly inside the housing of Fig.l in accordance with an embodiment of the present invention; and
Fig. 4 illustrates another isometric view of arrangement of contacts and scissor link assembly inside the housing of Fig.l in accordance with an embodiment of the present invention.
Fig. 1 illustrates a housing 100 of a circuit interrupter for enclosing a fixed contact and a movable contact operatively coupled together through a collapsible mechanical linkage. The housing 100 is an integrally formed body having a movable contact holding portion 1 and a fixed contact holding portion 2 disposed in a spaced apart relationship with each other and joined together by at least a pair of spaced ribs 3 and 4. The fixed contact holding portion 2 comprises a means 7 for holding the fixed contact and means 8 and 9 for holding the mechanical linkage at an inner surface 5 thereof. The movable contact holding portion 1 comprises a through opening 6 at the center thereof for housing the movable contact.
The means 7 for holding the fixed contact is a central hole 7 concentric with the through opening 6 and the means 8 and 9 for holding the collapsible mechanical linkage comprises a pair of aligned linkage holders 8 and 9 on opposite sides of the central hole 7, the aligned linkage holders 8 and 9 being equidistant from the central hole 7.

Preferably, the mechanical linkage is a scissor linkage assembly which comprises scissor links which may be pivoted to the linkage holders 8 and 9.
It may be apparent from the figure, that the housing 100 for circuit interrupter is an integrated cylindrical body, in which the movable contact holding portion 1 is a hollow cylindrical portion through which the whole assembly including fixed contact, movable contact and the mechanical linkage assembly may be disposed and fitted inside the housing 100.
Fig. 2 illustrates an isometric view of an intermediate housing 200 in casting stage before machining. The intermediate housing 200 is an integrated single cylindrical body of definite size and comprises movable contact holding portion 1, fixed contact holding portion 2, through opening 6, an inner surface 20 and a pair of aligned projections 21 and 22 on the inner surface 20 for pivoting scissor links.
The intermediate housing 200 may be manufactured through metal casting processes. In an embodiment of the present invention, the intermediate housing 200 may be casted in materials such as Aluminum, Alloys LM25, and LM09, etc.
In various embodiments of the present invention, machining processes are performed on the intermediate housing 200 to obtain the housing 100. For instance, the inner surface 20 may be machined to form a central hole 7 and the projections 21 and 22 may be machined to form the pair of aligned linkage holders 8 and 9 respectively. The machining/milling operation may be done with a wood rough cutter. Thus, in this manner, an integrated single body housing 200 is obtained which is jointless, takes less time in manufacturing, has better strength, and in which proper concentricity is maintained between the movable contact holding portion 1 and the fixed contact holding portion 2.

With reference to Figs. 3 and 4, the arrangement of contacts and corresponding scissor linkage assembly inside the circuit interrupter housing 100 is illustrated. The fixed contact 30 is disposed and fitted into the central hole 7 of the fixed contact holding portion 2, whereas the movable contact 31 is disposed in the movable contact holding portion 1. A pair of scissor links 32 and 33 of the scissor linkage assembly are pivoted together in the linkage holder 8 and the pair of scissor links 34 and 35 are pivoted together in the linkage holder 9 through nuts, bolts, screws, etc.
It may be noted that in order to form a collapsible mechanical linkage, the scissor links 32 and 33 may be cascaded to scissor links 41, 42, and 43 in a direction towards the movable contact 31. Similarly, the scissor links 34 and 35 may be cascaded to scissor links 44, 45, and 46 in a direction towards the movable contact 31. The cascaded scissor links may be ultimately pivoted to a scissor link retaining portion 40, which is connected to the movable contact 31. When the movable contact 31 moves towards the fixed contact 30, the scissor link assembly collapses and when the movable contact 31 move away from the fixed contact 32, the scissor link assembly expands. The distance between the portions 1 and 2 is set in such a manner so as to provide better clearance for the movement of the scissor links & the movable contact 31.
Although the invention has been described with reference to a specific embodiment, this description is not meant to be construed in a limiting sense. Various modifications of the disclosed embodiment, as well as alternate embodiments of the invention, will become apparent to persons skilled in the art upon reference to the description of the invention. It is therefore contemplated that such modifications can be made without departing from the scope of the invention as defined in the appended claims.

We claim:
1. A circuit interrupter comprising a housing enclosing a fixed contact and a movable contact operatively coupled together through a collapsible mechanical linkage, the housing comprising an integrally form casted body having a movable contact holding portion and a fixed contact holding portion disposed in a spaced apart relationship with each other and joined together by at least a pair of spaced ribs, the fixed contact holding portion comprising a means for holding the fixed contact and means for holding the mechanical linkage at an inner surface thereof and the movable contact holding portion comprising a through opening at the center thereof for housing the movable contact.
2. The circuit interrupter as claimed in claim 1, wherein the means for holding the fixed contact comprises a central hole concentric with the through opening and the means for holding the collapsible mechanical linkage comprises a pair of aligned linkage holders on opposite sides of the central hole.
3. The circuit interrupter as claimed in claim 2, wherein the integrally formed body is made by making an intermediate housing through metal casting and machining the intermediate housing to form the central hole and the pair of aligned linkage holders,
4. The circuit interrupter as claimed in claim 2, wherein the collapsible mechanical linkage comprises a scissor linkage assembly.