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
A double ceramic vacuum interrupter and a method of manufacturing the same
INVENTOR
Dhasal Anil Raghunath, an Indian national and of Crompton Greaves Limited, S6-Engineering Department, D-2 MIDC, Waluj, Aurangabad 431 136, Maharashtra, India
APPLICANTS
Crompton Greaves Limited, CG House, Dr Annie Besant Road, Prabhadevi,
Mumbai 400030, Maharashtra, India, an Indian Company
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 THE INVENTION
This invention relates to a double ceramic vacuum interrupter and a method of manufacturing the same
PRIOR ART DESCRIPTION
A vacuum interrupter (V I) is a switching device used for interruption of fault current in power supply systems. A vacuum interrupter generally comprises a fixed side subassembly and a moving side subassembly vacuum tight brazed at the opposite ends of a ceramic bottle which may be single ceramic or double ceramic. It also comprises a centre shield located around the fixed side electrode of the fixed side subassembly and brazed to the fixed side endplate of the fixed side subassembly. The centre shield is fixed to the ceramic bottle with the help of a centre flange which generally comprises a cylindrical portion and an outwardly extending portion. In the case of a vacuum interrupter comprising a double ceramic vacuum bottle, the cylindrical portion of the centre flange is brazed to the centre shield with the help of a brazing ring and the outwardly extending portion of the centre flange is located between the ceramic bottle portions and brazed thereto. The brazing ring is generally made of copper nickel alloy and the brazing of the cylindrical portion of the centre flange is carried out in a vacuum furnace. Brazing consumes considerable energy and is expensive and cumbersome to carry out. Brazing is also time consuming and reduces productivity.


OBJECTS OF THE INVENTION
An object of the invention is to provide a method of making a double ceramic vacuum interrupter which eliminates brazing and energy consumption in the fixing of the centre shield and centre flange and is economical and which reduces production time and increases productivity
Another object of the invention is to provide a double ceramic vacuum interrupter which is simple in construction and economical.
DETAILED DESCRIPTION OF THE INVENTION
According to the invention there is provided a method of manufacturing a double ceramic vacuum interrupter, the method comprising mechanical fixing of the centre flange of the vacuum interrupter onto the centre shield thereof.
According to the invention there is also provided a double ceramic vacuum interrupter, wherein the centre flange of the vacuum interrupter is fixed to the centre shield of the vacuum interrupter by mechanical fixing means.
The following is a detailed description of the invention with reference to the accompanying drawings, in which:
Fig 1 is a crosssectional view of a double ceramic vacuum bottle of the vacuum interrupter according to an embodiment of the invention; and


Fig 2 is an enlarged view at A in Fig 1.
The double ceramic vacuum bottle 1 as illustrated in Fig 1 and 2 of the accompanying drawings comprises ceramic bottle portions 2a and 2b. 3 is a centre shield and 4 is a centre flange comprising a cylindrical portion 4a and an outwardly extending portion 4b. The lower end of the cylindrical portion is located against a step 5 formed on the outer surface of the centre shield and the upper end of the cylindrical portion is pinned onto the centre shield. The pinned portion or lance formed on the centre shield is marked 6. The cylindrical portion of the centre flange is firmly located between the step 5 and pinned portion 6 so as to hold the centre shield. The outwardly extending portion of the centre flange is brazed between the bottle portions. According to the invention the brazing ring and brazing of the cylindrical portion of the centre flange onto the centre shield have been eliminated. Instead, the centre shield is easily and conveniently supported on the cylindrical portion of the centre flange by locating the lower end of the cylindrical portion of the centre flange against the step on the centre shield and pinning the upper end of the cylindrical portion onto the centre shield. As the brazing of the centre flange onto the centre shield has been eliminated fixation of the centre shield onto the centre flange does not require furnace treatment and energy. Fixation time is reduced considerably and productivity of the vacuum interrupter is correspondingly increased. There is also considerable cost benefit besides simplifying the construction and manufacture of the vacuum interrupter. The invention is essentially in the mechanical fixing of the centre flange to the centre shield. The centre flange geometry and


configuration can be different. The scope of the invention should be construed and understood accordingly.

We claim:
1. A method of manufacturing a double ceramic vacuum interrupter, the method comprising mechanical fixing of the centre flange of the vacuum interrupter onto the centre shield thereof.
2. The method as claimed in claim 1, wherein the centre flange comprises a cylindrical portion and an outwardly extending portion and mechanical fixing comprises location of the lower end of the cylindrical portion against a step on the centre shield and pinning of the upper end of the cylindrical portion onto the centre shield.
3. A double ceramic vacuum interrupter, wherein the centre flange of the vacuum interrupter is fixed to the centre shield of the vacuum interrupter by mechanical fixing means.
4 The double ceramic vacuum interrupter as claimed in claim 3, wherein the lower
end of the cylindrical portion is located against a step formed on the outer surface of the centre shield and the upper end of the cylindrical portion is pinned to the centre shield.



Abstract
A double ceramic vacuum interrupter (1) and a method of manufacturing the same. The centre flange (4) of the vacuum interrupter is fixed to the centre shield (3) of the vacuum interrupter by mechanical fixing means (5, 6) (Fig 2).