FORM 2
THE PATENT ACT 1970
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
(section 10 and rule 13)
1. TITLE OF THE INVENTION: "Integral Shaft for a circuit breaker"
2. APPLICANT:

(a) NAME: Larsen & Toubro Limited
(b) NATIONALITY: Indian Company registered under the
provisions of the Companies Act-1956.
(c) ADDRESS: Larsen & Toubro Limited
Electrical & Automation North Wing, Gate 7, Level 0, Powai Campus, Saki Vihar Road, Mumbai 400 072, INDIA
3. PREAMBLE TO THE DESCRIPTION:

COMPLETE
The following specification particularly describes the invention and the manner in which it is to be performed

Integral Shaft for a circuit breaker
Field of invention
The present invention relates to low voltage circuit breaker contact systems and more particularly, to a rotor or shaft arrangement in circuit breaker contact systems.
Background of the invention
In conventional circuit breakers, a rotor assembly is having two insulating halves within which the contact assembly components such as moving contact, springs, spring holder, pins, and shaft cover are contained. In these devices the rotor normally has two separate parts that tend to twist due to relative movement of the rotor halves during the operation of the rotor assembly.
One such example, as shown in EP 1454331 wherein a rotating contact supporting shaft for a low-voltage power circuit breaker, is disclosed. The circuit breaker particularity consists of the fact that it has a modular structure that comprises, along the rotation axis, at least one first and one second supporting module 10, 20, each module being functionally coupled to at least one corresponding moving contact 3 of the circuit breaker and being provided respectively with first and second means 22 for connection to at least one first interconnection module 30 the first interconnection module is interposed between the first and second supporting modules and is provided with third and fourth connection means 31 that are suitable to be coupled respectively to the first and second connection means the coupling between the first and third connection means and between the second and fourth connection means allows the functional connection between the first and second ; supporting modules and the direct structural connection of the interconnection module to the first and second supporting modules. A rotating contact supporting shaft for a low-voltage power circuit breaker, whose particularity consists of the fact that it has a modular structure that comprises, along the rotation axis, at least one

first and one second supporting module (10,20), each module being functionally coupled to at least one corresponding moving contact (3) of the circuit breaker and being provided respectively with first and second means (22) for connection to at least one first interconnection module (30); the first interconnection module is interposed between the first and second supporting modules and is provided with third and fourth connection means (31) that are suitable to be coupled respectively to the first and second connection means; the coupling between the first and third connection means and between the second and fourth connection means allows the functional connection between the first and second supporting modules and the direct structural connection of the interconnection module to the first and second supporting modules.
Further, US6960731 discloses a rotating contact supporting shaft for a low-voltage power circuit breaker, whose particularity consists of the fact that it has a modular structure that comprises, along the rotation axis, at least one first and one second supporting module (10, 20), each module being functionally coupled to at least one corresponding moving contact (3) of the circuit breaker and being provided respectively with first and second means (22) for connection to at least one first interconnection module (30); the first interconnection module is interposed between the first and second supporting modules and is provided with third and fourth connection means (31) that are suitable to be coupled respectively to the first and second connection means;; the coupling between the first and third connection means and between the second and fourth connection means allows the functional connection between the first and second supporting modules and the direct structural connection of the interconnection module to the first and second supporting modules.
One of the major drawbacks of these devices is that the relative movement between the two halves of the rotor frequently results in a relative twisting motion that is transmitted through the means of mechanical coupling amongst various poles of a circuit breaker. Also, the use of two separate parts of the rotor imparts difficulty in assembling. For example, these devices include more than one pins such that one pin around which the

moving contact is pivoted and additionally the pins act as pivots for the springs essentially required to generate contact pressure when a set of contacts mate against each other. These pins are very difficult to align when the two halves are closed during the assembly. Further, the rotating mechanism of these circuit breakers rotates the drive shaft that in turn compresses/extends the springs thereby generating contact pressure. This motion is transmitted across poles by a suitable coupling means like through pins. If the rotor comprises of two halves the problem of twisting and loss of motion gets worse.
Accordingly, there exists a need to provide a rotor or shaft arrangement which overcomes drawbacks of the prior art.
Objects of the invention
An object of the present invention is to provide a rotor/shaft in a circuit breaker which avoids twisting leading to loss of force/motion transmission.
Another object of the present invention is to provide a rotor/shaft in a circuit breaker which makes the shaft assembly easier.
Summary of the invention
Accordingly the invention provides an integral shaft assembly for a circuit breaker that includes an integral shaft assembly for a circuit breaker having an opposed pair of moving contacts positioned therein. The integral shaft assembly comprises an integral shaft having a first set of compression springs and a second set of compression springs. The first set of compression springs and the second set of compression springs are respectively positioned on an opposed pair of spring holders. The spring holders are having a plurality of spring pin slots defined thereon. The plurality of spring pin slots receives a respective plurality of spring pins entirely therein. The integral shaft is having a central pin slot that receives a central pin positioned entirely therein. The integral shaft

assembly includes an end cap that positions atop the integral shaft. The end cap prevents entry of a gaseous product from a top portion of the integral shaft. The integral shaft assembly includes a shaft cover that positions along a sidewall of the integral shaft. The shaft cover prevents entry of the gaseous product from a side portion of the integral shaft.
Brief description of the drawings
FIG. 1 is a front view of an integral shaft assembly of a circuit breaker constructed in accordance with the present invention;
FIG. 2 is a front view of the integral shaft assembly of the circuit breaker of FIG. 1 in an end cap removed position;
FIG. 3 is a front perspective view of the integral shaft assembly of the circuit breaker of FIG. 1;
FIG. 4 is a front view of an integral shaft assembly of a circuit breaker of FIG. 1; and
FIG. 5 is a side perspective view of the integral shaft assembly of the circuit breaker of FIG. 1.
Detailed description of the invention
The foregoing objects of the present invention are accomplished and the problems and shortcomings associated with the prior art, techniques and approaches are overcome by the present invention as described below in the preferred embodiments.
Accordingly, the present invention provides an integral shaft assembly of a circuit breaker that avoids twisting leading to loss of force/motion transmission. The present

invention also provides the integral shaft assembly that makes the assembly of the circuit breaker device easier.
Referring to FIG. 1, an integral shaft assembly 10 for a single pole circuit breaker is shown in accordance with a preferred embodiment of the present invention is shown. The integral shaft assembly 10 includes an integral shaft 12 that is positioned with an opposed pair of moving contact buttons 14. An end cap 16 is positioned atop the integral shaft 12. The end cap 16 prevents the gases from entering the shaft assembly 10. The integral shaft assembly 10 includes a pair of through pin holes 18. Each of the pin holes 18 facilitates through insertion of a pin within the integral shaft assembly 10 in order to transmit motion., there is no twisting or loss of motion on account of the same as the shaft rotates since the shaft is one integral entity.
As shown in FIGS. 2-5, the integral shaft assembly 10 includes a pair of compression springs mounted on a plurality of spring holders via a plurality of spring pins positioned in a plurality of spring pin slots defined on the spring holders. In this one preferred embodiment, the integral shaft assembly 10 includes a first compression spring 20 and a second compression spring 22. The integral shaft assembly 10 includes a first spring holder 24, a second spring holder 26, a third spring holder 28, and a fourth spring holder 30. The first spring holder 24 and the second spring holder 26 respectively include a first spring pin slot 32 and a second spring pin slot 34 that respectively accommodate through pins (not shown) to hold the first compression spring 20 in a first predefined position. The third spring holder 28 and the fourth spring holder 30 respectively include a third pin slot 36 and a fourth pin slot 38 for holding the second compression spring 22 in a second predefined position. The integral shaft assembly 10 includes a central pin slot 40 that receives a central pin (not shown). The central pin slot 40 facilitates linkage between the first compression spring 20 and the second compression spring 22. The integral shaft 12 is positioned with a shaft cover 42. The shaft cover 42 prevents a gaseous product from entering into a shaft region.

Referring again to FIGS. 1-5, in operation, the first compression spring set 20 and the second compression spring set 22 provide a rotating mechanism within the integral shaft assembly 10 to ensure adequate contact pressure at the electrical joints between fixed contact and the moving contact of the circuit breaker. It is understood here that the contact pressure is a force with which a set of contact buttons 14 are held against each other. It is also understood here that the contact pressure is sufficient enough to provide a low resistance of the circuit breaker. The individual integral shafts 12 are coupled by the . through pins. It is understood that a pole-wise construction is preferred in this one particular embodiment to facilitate modular construction for mass production with reduced variety. In operation, the rotor/shaft 12 is different for each pole. However, the integral shaft assembly 10 advantageously provides a low resistance in all the poles thereby providing essential contact pressure in all the poles during the conduction of normal current.
In operation, firstly an assembler needs to insert the moving contacts 14 in the integral shaft 12 followed by insertion of the spring pins and the shaft pins in respective slots 32-38. Subsequently, the first compression spring 20 and the second compression spring 22 are assembled on the respective spring holders 24-30. Further, the center pin is inserted through the center pin slot 40. Further, the end caps 16 are positioned on either ends of the integral shaft 12 by mounting means such as for example snap-fitting, riveting, screwing and welding. Finally, the shaft covers 42, having slots for inserting moving contacts, are placed in a groove on the surface of the shaft 12 to complete the integral shaft assembly 10 of the present invention.
Advantages of the present invention
1. The integral shaft 12 advantageously acts as a single component/ entity thereby eliminating the problem of the non alignment of the axes of the conventional non-integral shaft assemblies.

2. The integral shaft assembly 10 advantageously requires substantially less efforts in assembling in comparison to conventional non-integral shaft assemblies.
The foregoing descriptions of specific embodiments of the present invention have been presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the present invention to the precise forms disclosed, and obviously many modifications and variations are possible in light of the above teaching. The embodiments were chosen and described in order to best explain the principles of the present invention and its practical application, to thereby enable others skilled in the art to best utilize the present invention and various embodiments with various modifications as are suited to the particular use contemplated. It is understood that various omission and substitutions of equivalents are contemplated as circumstance may suggest or render expedient, but such are intended to cover the application or implementation without departing from the spirit or scope of the present invention.

We Claim:
1. An integral shaft assembly for a circuit breaker having an opposed pair of moving
contacts buttons positioned therein on limbs of a moving contact pivoted at the shaft, the
integral shaft assembly comprising:
an integral shaft having a first compression spring and a second compression spring, the first compression spring and the second compression spring respectively positioning on an opposed pair of spring holders, the spring holders having a plurality of spring pin slots defined thereon, the plurality of spring pin slots receiving a respective plurality of spring pins entirely therein, the integral shaft having a central pin slot receiving a central pin positioned entirely therein;
an end cap positioning atop the integral shaft, the end cap preventing entry of a gaseous product from a top portion of the integral shaft; and
a shaft cover positioning along a sidewall of the integral shaft, the shaft cover preventing entry of the gaseous product from a side portion of the integral shaft.
2. The integral shaft assembly as claimed in claim 1, wherein the first set of
compression springs and the second set of compression springs mutually provide a
rotating mechanism that ensures adequate contact pressure with a low resistance between
a fixed contact and a moving contact of the circuit breaker.