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
Double acting two-way mounting shock absorber of a circuit breaker
assembly
APPLICANT (S)
Crompton Greaves Limited, CG House, Dr Annie Besant Road, Worli, Mumbai 400 030, Maharashtra, India, an Indian Company
INVENTOR (S)
Desale Rajgopal Shivdas, Sonar Pankaj, and Kodte Sandeep; all of Crompton Greaves Ltd, S3, Switchgear Division, A3, MIDC Ambad, Nashik-422010, Maharashtra, India; all Indian Nationals
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 the field of mechanical engineering.
Particularly, this invention relates to circuit breakers and shock absorbing mechanisms, thereof.
Specifically, this invention relates to a double acting two-way mounting shock absorber of a circuit breaker assembly.
BACKGROUND OF THE INVENTION:
The term 'switchgear', used in association with the electric power system, or grid, refers to the combination of electrical disconnects, fuses and/or circuit breakers used to isolate electrical equipment. Switchgear is used both to de-energize equipment to allow work to be done and to clear faults.
An effective form of switchgear is gas insulated switchgear (GIS). In a GIS, there are a plurality of electrical components where the conductors and contacts are insulated by pressurized sulfur hexafluoride gas (SF6).
Circuit breakers are one type of switchgear component. A circuit breaker is an automatically operated electrical switch designed to protect an electrical circuit from damage caused by overload or short circuit. Its basic function is to interrupt continuity upon detection of a fault condition to immediately discontinue electrical flow. The circuit breaker must react to fault condition; in

low-voltage circuit breakers this is usually done within the breaker enclosure. Circuit breakers for large currents or high voltages are usually arranged with pilot devices to sense a fault current and to operate the trip opening mechanism. The trip coil that releases the latch is usually energized by a separate battery, although some high-voltage circuit breakers are self-contained with current transformers, protection relays, and an internal control power source.
Once a fault is detected, contacts within the circuit breaker must open to interrupt the circuit; some mechanically-stored energy (using something such as springs or compressed air) contained within the breaker is used to separate the contacts. Small circuit breakers may be manually operated; larger units have coils to trip the mechanism, and electric motors to restore energy to the springs.
The circuit breaker contacts must carry the load current without excessive heating, and must also withstand the heat of the arc produced when interrupting (opening) the circuit. Contacts are made of copper or copper alloys, silver alloys, and other highly conductive materials.
A trip coil is a type of solenoid in which the moving armature opens a circuit
breaker or other protective device when the coil current exceeds a
predetermined value. A closing coil is adapted to shut the circuit breaker
completely.
In its working mode, if a power surge occurs in the electrical system, the
breaker will trip. This means that a breaker that was in the "on" position will

flip to the "off position and shut down the electrical power leading from that breaker. Essentially, a circuit breaker is a safety device. When a circuit breaker is tripped, it may prevent a fire from starting on an overloaded circuit; it can also prevent the destruction of the device that is drawing the electricity.
Conventionally, damping elements or shock absorbers are known to be used along with a moveable contact of a circuit breaker. These shock absorbers of the prior art are double acting shock absorbers but can be mounted in one way only. The shock absorber functions along with trip spring action of the circuit breaker. The circuit breaker is open when trip spring is released, and the circuit breaker is closed when trip spring is tensioned. The shock absorber is adapted to play its shock absorbing role while opening and closing the circuit breaker. In this design of the prior art, the shock absorber can be mounted only on the rear side.
Due to rear mounting arrangement, it is difficult to mount the current shock absorber arrangement in a compact layout, thus increasing the bulk of the circuit breaker. There is difficulty in alignment of pole center and spring center of the circuit breaker while manufacturing due to unsuitability in manufacturing of a relatively bigger fixture. The spring mounting bracket should have higher strength due to more cantilever action.
Hence, there is a need for an improved damping or shock absorbing mechanism for the trip spring of a circuit breaker. OBJECTS OF THE INVENTION:

An object of the invention is to provide a damping or shock absorbing mechanism which does not exert pressure on contacts or components of circuit breaker assembly.
Another object of the invention is to provide a two-way acting shock absorbing mechanism.
Yet another object of the invention is to provide a dual way mounting shock absorbing mechanism.
Still another object of the invention is to provide a shock absorbing mechanism which reduces the bulk of the circuit breaker assembly.
An additional object of the invention is to provide a shock absorbing mechanism which is easier to mount.
Yet an additional object of the invention is to provide a shock absorbing mechanism with a mounting bracket which is relatively more rigid and having relatively higher strength.
SUMMARY OF THE INVENTION:
According to this invention, there is provided a double acting two-way mounting shock absorber of a circuit breaker assembly, said assembly comprises:

a. bell crank lever disposed in a manner such that its effort arm is operated
by a reciprocating first operating rod driven by a crankshaft and its load
arm is mechanically coupled with a second operating rod transversely
disposed in relation to said first operating rod, with said effort arm being
on the operative left hand side of said load arm from an operative front
face of the circuit breaker assembly, with an angular displacement, of
said lever, occurring in an operative anti-clockwise direction about its
pivoting point;
b. two-way piston being co-axially located within an inner cylinder, which
inner cylinder including a proximal end (with respect to said circuit
breaker assembly) and a distal end (with respect to said circuit breaker
assembly), said proximal end of said inner cylinder being fixed to said
circuit breaker assembly;
c. disengageable disc, at said distal end of said inner cylinder, adapted to
receive the distal end of said piston, in that, as said piston moves inwards
towards said circuit breaker assembly, said disc moves to rest against
said distal end of said inner cylinder, and as said piston moves outwards
away from said circuit breaker assembly, said disc moves to be
disengaged with respect to said distal end of said inner cylinder;
d. outer cylinder adapted to envelope said inner cylinder and said piston;
and
e. resilient means (spring) adapted to envelope said outer cylinder and be
mechanically coupled to said diengageable disc at its operative distal
end, in that, the operation of said first operating rod in an operative
downward direction causing said lever to move said second operating
rod and said piston in an operative outward direction, thereby causing

said disc to move away from the operative distal end of said inner cylinder and thus causing release of said spring to achieve open condition of said circuit breaker and further the operation of said first operating rod in an operative upward direction causing said lever to move said second operating rod and said piston in an operative inward direction, thereby causing said disc to move towards the operative distal end of said inner cylinder and thus causing tensioning of said spring to achieve closed condition of said circuit breaker.
Typically, said assembly includes a mounting bracket at the operative proximal end of said shock absorber assembly in order to mount said shock absorber assembly.
Typically, piston is a hydraulic piston with oil flowing in said inner cylinder to abet piston movement.
Typically, said assembly includes oil seals provisioned at two ends of said piston with respect to said inner cylinder.
According to one mounting embodiment, said assembly is a front mounting assembly with respect to said circuit breaker assembly.
According to an alternative mounting embodiment, said assembly is a rear mounting assembly with respect to said circuit breaker assembly.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS:
Figure 1 illustrates an isometric view of a circuit breaker assembly with a double acting one way shock absorber of the prior art;
Figure 2 illustrates a front view of the shock absorber assembly of the prior art mounted with the help of a bracket in a circuit breaker assembly;
Figure 3 illustrates a circuit breaker assembly in its closed condition with trip spring charged and the resulting position of the piston in the shock absorber assembly of the prior art; and
Figure 4 illustrates a circuit breaker assembly in its open condition with trip spring discharged and the resulting position of the piston in the shock absorber assembly of the prior art.
The invention will now be described in relation to the accompanying drawings, in which:
Figure 5 illustrates an isometric view of a circuit breaker assembly with a double acting two-way mounting shock absorber;
Figure 6 illustrates a front view of the double acting two-way mounting shock absorber assembly mounted with the help of a bracket in a circuit breaker assembly;

Figure 7 illustrates a circuit breaker assembly in its closed condition with trip spring charged and the resulting position of the piston in the shock absorber assembly; and
Figure 8 illustrates a circuit breaker assembly in its open condition with trip spring discharged and the resulting position of the piston in the shock absorber assembly.
DETAILED DESCRIPTION OF THE ACCOMPANYING DRAWINGS:
Figure 1 illustrates an isometric view of a circuit breaker assembly with a double acting one way shock absorber of the prior art. Figure 2 illustrates a front view of the shock absorber assembly of the prior art mounted with the help of a bracket in a circuit breaker assembly. Figure 3 illustrates a circuit breaker assembly in its closed condition with trip spring charged and the resulting position of the piston in the shock absorber assembly of the prior art. Figure 4 illustrates a circuit breaker assembly in its open condition with trip spring discharged and the resulting position of the piston in the shock absorber assembly of the prior art.
Reference numeral 12 (Figure 1) indicates a circuit breaker pole. A circuit breaker controls one "hot" leg of a circuit which is the pole. A "hot" wire, that is, the one that supplies the power, is fed through a circuit breaker before it goes through other appliances. A "neutral" or "return" line is connected to appliances and outlet receptacles to complete the circuit. When there is a "short" or a malfunction that tries to pull more current than the circuit has been

designed to safely handle, the circuit breaker will shut down all power to that circuit. Reference numeral 50 refers to a double acting one way shock absorber of the prior art installed in the circuit breaker.
Typically, this is an oil filled shock absorber. A single enclosure encloses an oil filled cylinder (21) with a co-axially movable piston (22) within. There are holes in the cylinder which allow passage of oil for actuation and co-axial displacement of the piston within the cylinder. The displacement of oil creates resistance and absorbs energy of the piston to some extent. An outer cylinder (23) enveloped the oil filled inner cylinder (21). Oil seals (29) prevent the leakage or expulsion of oil beyond the proximal and distal ends of the inner cylinder (21) which houses the piston (22). The piston (22) is connected to a bell crank lever (25) at its one end. A first end of the bell crank lever (25) is connected to an angularly operating rod (26) of the circuit breaker assembly. A second end of the bell crank lever (25) is connected to a linearly (axially) operating rod (28) of the circuit breaker assembly. The angular displacement of the first rod (26) effectively moves the arms of the bell crank lever (25) such that it causes a linear and axial simultaneous actuation of the second rod (28). The bell crank is used to convert the direction of reciprocating movement of the first rod. By varying the angle of the crank piece it can be used to change the angle of movement from 1 degree to 180 degrees. The bell crack lever (25), in the prior art, is so mounted that it causes a pushing action to the piston. A mounting bracket (27) is placed at an operative distal end of the mechanism so as to provide axial support to the axial movement of the piston. The piston includes a shoulder at its proximal end which co-operates with a spring (24) within which the outer cylinder (23) and inner cylinder (21) are ensconced. The

piston movement ends within the inner cylinder (21) and exerts pressure on the inner distal end of the inner cylinder (21) during the compression of the spring. The compression spring, tensioned and charged, is shown in Figure 3 of the accompanying drawings, wherein the piston (22) has travelled till the distal end of the inner cylinder (21) and is seen during the closed position of the circuit breaker assembly. The compression spring, released and discharged, is shown in Figure 4 of the accompanying drawings, wherein the piston (22) has travelled the length of the space on the inner cylinder (21) to the reach its proximal end and is seen during the open position of the circuit breaker assembly. This arrangement, of the prior art, does not provide for full absorption of the incumbent shock and, hence, may result in deformation of contacts or components of the circuit breaker assembly.
Here, the movement of the piston is towards the interior of the circuit breaker assembly, thereby requiring relatively greater space of the circuit breaker assembly, in order to allow leeway for movement equivalent to the length of the piston, within the circuit breaker assembly.
According to this invention, there is provided a double acting two-way mounting shock absorber (100) of a circuit breaker assembly.
Figure 5 illustrates an isometric view of a circuit breaker assembly with a double acting two-way mounting shock absorber. Figure 6 illustrates a front view of the double acting two-way mounting shock absorber assembly mounted with the help of a bracket in a circuit breaker assembly. Figure 7 illustrates a circuit breaker assembly in its closed condition with trip spring

charged and the resulting position of the piston in the shock absorber assembly according to this invention. Figure 8 illustrates a circuit breaker assembly in its open condition with trip spring discharged and the resulting position of the piston in the shock absorber assembly according to this invention.
In accordance with an embodiment of this invention, there is provided a bell crank lever (41) so disposed that its effort arm (41a) is operated by a reciprocating first operating rod (42) driven by a crankshaft (43) and its load arm (41b) is mechanically coupled with a second operating rod (44) transversely disposed in relation to the first operating rod (42). The tip of the effort arm (41a) is on the operative left hand side of the tip of the load arm (41b) from an operative front face of the circuit breaker assembly, as seen in Figure 5 of the accompanying drawings, with the angular displacement occurring in an operative anti-clockwise direction about the pivoting point (41c) of the bell crank lever (41).
In accordance with another embodiment of this invention, there is provided a two-way piston (45), in that, the piston is co-axially located within an inner cylinder (46), which inner cylinder (46) includes a proximal end (proximal with respect to the circuit breaker assembly) and a distal end (distal with respect to the circuit breaker assembly). The proximal end of the inner cylinder (46) is fixed to the circuit breaker assembly. The distal end of the inner cylinder (46) includes a disengageable disc (47) which receives the distal end of the piston (45), in that, as the piston (45) moves inwards towards the circuit breaker assembly, the disc (47) moves to rest against the distal end of the inner cylinder (46), and as the piston (45) moves outwards away from the circuit

breaker assembly, the disc (47) moves to be disengaged with respect to the distal eng of the inner cylinder (46). Thus, the movement of the piston (45) extends beyond the general circuit breaker assembly, into open space, and does not require the framework of the circuit breaker assembly to be bulky. The framework may, hence, be reduced in size, resulting in a compact assembly, which difference in size can be made out from Figure 5 of the accompanying drawings of the invention, with respect to Figure 1 of the accompanying drawings of the prior art.
The mounting bracket (48) is, now, at the operative proximal end of the shock absorber assembly as opposed to the operative distal end.
An outer cylinder (49) enveloped the inner cylinder (46) and the piston (45).
In accordance with yet another embodiment of this invention, there is provided a resilient means such as a spring (51) to envelope said outer cylinder and be mechanically coupled to the diengageable disc (47) at its operative distal end, in that, the operation of the first operating rod (42) in an operative downward direction causes the lever (41) to move the second operating rod (44) and piston (45) in operative outward direction, thereby causing the disc (47) to move away from the operative distal end of the inner cylinder (46) and thus causing release of the spring (51). This causes the spring (51) to get discharged as seen in Figure 8 of the accompanying drawings. Thus, the circuit breaker is now open. Consequently, the operation of the first operating rod (42) in an operative upward direction causes the lever (41) to move the second operating rod (44) and piston (45) in operative inward direction, thereby causing the disc

(47) to move towards the operative distal end of the inner cylinder (46) and thus causing tensioning of the spring (51). This causes the spring (51) to get charged as seen in Figure 7 of the accompanying drawings. Thus, the circuit breaker is now close.
The pistons (45) are hydraulic pistons with oil flowing in the inner cylinder (46) to abet piston (45) movement.
Oil seals (53, 55) are provisioned at two ends of the piston (45) with respect to the inner cylinder (46).
This new design helps in mounting the shock absorber in two ways (in front or in the rear); hence gives flexibility in structure design and resulting in a compact layout. Shock absorber is mounted on the structure with the help of smaller bracket due to less cantilever action. The mounting bracket is more rigid having higher strength. The shock absorber can be used with both end of piston rod thus making it easier to mount. It is relatively easy to manufacture a fixture for the alignment of the shock absorber with pole, while manufacturing of structure.
While this detailed description has disclosed certain specific embodiments of the present invention for illustrative purposes, various modifications will be apparent to those skilled in the art which do not constitute departures from the spirit and scope of the invention as defined in the following claims, and it is to be distinctly understood that the foregoing descriptive matter is to be interpreted merely as illustrative of the invention and not as a limitation.

We claim,
1. A double acting two-way mounting shock absorber of a circuit breaker assembly, said assembly comprising:
a. bell crank lever disposed in a manner such that its effort arm is operated
by a reciprocating first operating rod driven by a crankshaft and its load
arm is mechanically coupled with a second operating rod transversely
disposed in relation to said first operating rod, with said effort arm being
on the operative left hand side of said load arm from an operative front
face of the circuit breaker assembly, with an angular displacement, of
said lever, occurring in an operative anti-clockwise direction about its
pivoting point;
b. two-way piston being co-axially located within an inner cylinder, which
inner cylinder including a proximal end (with respect to said circuit
breaker assembly) and a distal end (with respect to said circuit breaker
assembly), said proximal end of said inner cylinder being fixed to said
circuit breaker assembly;
c. disengageable disc, at said distal end of said inner cylinder, adapted to
receive the distal end of said piston, in that, as said piston moves inwards
towards said circuit breaker assembly, said disc moves to rest against
said distal end of said inner cylinder, and as said piston moves outwards
away from said circuit breaker assembly, said disc moves to be
disengaged with respect to said distal end of said inner cylinder;
d. outer cylinder adapted to envelope said inner cylinder and said piston;
and

e. resilient means (spring) adapted to envelope said outer cylinder and be mechanically coupled to said diengageable disc at its operative distal end, in
that, the operation of said first operating rod in an operative downward direction causing said lever to move said second operating rod and said piston in an operative outward direction, thereby causing said disc to move away from the operative distal end of said inner cylinder and thus causing release of said spring to achieve open condition of said circuit breaker and further the operation of said first operating rod in an operative upward direction causing said lever to move said second operating rod and said piston in an operative inward direction, thereby causing said disc to move towards the operative distal end of said inner cylinder and thus causing tensioning of said spring to achieve closed condition of said circuit breaker.
2. An assembly as claimed in claim 1 wherein, said assembly includes a mounting bracket at the operative proximal end of said shock absorber assembly in order to mount said shock absorber assembly.
3. An assembly as claimed in claim 1 wherein, piston is a hydraulic piston with oil flowing in said inner cylinder to abet piston movement.
4. An assembly as claimed in claim 1 wherein, said assembly includes oil seals provisioned at two ends of said piston with respect to said inner cylinder.

5. An assembly as claimed in claim 1 wherein, said assembly is a front mounting assembly with respect to said circuit breaker assembly.
6. An assembly as claimed in claim 1 wherein, said assembly is a rear mounting assembly with respect to said circuit breaker assembly.