FORM 2
The Patents Act 1970
(39 of 1970)
&
The Patent Rules 2003
COMPLETE SPECIFICATION
(See Section 10 and rule 13)
TITLE OF THE INVENTION:
SLIDER BASED TORSION SPRING MECHANISM FOR CIRCUIT
BREAKERS
APPLICANT: LARSEN & TOUBRO LIMITED
L&T House, Ballard Estate, P.O. Box No. 278,
Mumbai, 400 001, Maharashtra
INDIA.
PREAMBLE OF THE DESCRIPTION:
THE FOLLOWING SPECIFICATION PARTICULARLY DESCRIBES THE
INVENTION AND THE MANNER IN WHICH IT IS TO BE PERFORMED

A) TECHNICAL FIELD
[0001] The present invention generally relates to circuit breakers and particularly relates to a spring mechanism for circuit breakers. The invention more particularly relates to torsion spring mechanism for the circuit breakers.
B) BACK GROUND OF THE INVENTION
[0002] Circuit breakers are the mechanical switching devices capable of making, carrying, and breaking currents under normal circuit conditions and also making. carrying for a specified time, and breaking currents under specified abnormal conditions. A circuit breaker basically consists of a pair of separable contacts and an interrupting medium. The function of the contacts is to conduct the electrical current when the breaker is closed and withstand the arcs while interrupting. Generally, the electrical contacts have a stationary part and a moving part. By bringing the moving contact to touch the stationary contact, electric current flows and the breaker is closed. By driving the moving contact away from the stationary contact the electric arc develops and by quenching it the current stops flowing and the breaker is open. [0003] In the existing technique, the short circuit current is sensed automatically and the signal is provided to the mechanism as a TRIP command which in turn leads to opening of the contacts. However, during normal ON-OFF and OFF-ON operation, the input to the mechanism is given through the rotation of a knob manually. [0004] In all the three cases, the contact velocity is independent of speed at which the Knob is rotated. The rotation of Knob leads to storing potential energy in the spring member while restricting the contact movement during the charging operation. Further at a specified instance the potential energy of spring is released in the form of kinetic energy through mechanical linkages which in turn leads to rotation of the contacts at high velocity.
[0005] Further in the existing techniques, the mechanism used in circuit breakers uses an extension Spring as energy means. The spring potential energy is transferred

to movable contacts through Linkages. This leads to utilization of only a component
of spring energy for imparting kinetic energy to the contacts.
[0006] Hence there is a need to provide a spring mechanism in circuit breakers
for a complete utilization of spring energy to provide kinetic energy of the contacts.
[0007] The above mentioned shortcomings, disadvantages and problems are
addressed herein and which will be understood by reading and studying the following
specification.
C) OBJECT OF THE PRESENT INVENTION
[0008] The primary object of the present invention is to provide a spring
mechanism for circuit breakers to operate the circuit breaker in at least one of an OFF
condition, an ON condition and a TRIP condition.
[0009] Yet another object of the present invention is that the main mechanism
spring is designed in such a way that a spring energy generated is completely utilized
for operating the circuit breaker.
[0010] Yet another object of the present invention is that the spring potential
energy is completely utilized and is converted to kinetic energy of the contacts.
[0011] Yet another object of the present invention is that the spring mechanism
has a higher contact opening velocity.
[0012] Yet another object of the present invention is that the spring mechanism
provides three distinct stable states of the circuit breaker such as an ON, an OFF and
a TRIP state.
D) SUMMARY OF THE INVENTION
[0013] The various embodiments of the present invention provide a spring mechanism for circuit breakers. The spring mechanism includes a contact link, an upper slider connected to the contact link, a lower slider connected to the contact link, an upper slider box housing the upper slider, a lower slider box housing the lower slider, a knob and a main mechanism spring. The main mechanism spring generates

the required spring energy based on sliding operation of the upper slider and the
lower slider when the knob is rotated to operate the circuit breaker in at least one of
an ON, OFF and a TRIP condition.
[0014] According to one embodiment of the present invention, the upper slider
facilitates locking or unlocking of the contact link by sliding the upper slider into the
upper slider box.
[0015] According to one embodiment of the present invention, the main
mechanism spring facilitates the ON or the OFF operation of the contact link based
on sliding operation of the upper slider and the lower slider. According to one
embodiment of the present invention, the main mechanism spring is a torsion spring
which is helical in shape. According to one embodiment of the present invention, the
main mechanism spring gets charged during the operation of the circuit breaker in the
ON condition.
[0016] According to one embodiment of the present invention, the knob is
mounted on a main shaft in the circuit breaker.According to one embodiment of the
present invention, the knob and the contact link are in ON condition during the
operation of the circuit breaker in the ON condition.
|0017] According to one embodiment of the present invention, the upper slider
locks the contact link when the circuit breaker is in the OFF condition. According to
one embodiment of the present invention, the upper slider slides in an upper slider
box due to a cam action by at least one of the fork or the contact Hnk.According to
one embodiment of the present invention, the lower slider slides in a lower slider box
due to a cam action by at least one of the fork or the contact link.
[0018] According to one embodiment of the present invention, the mechanism
includes a trip spring that is actuated when the circuit breaker is in the TRIP
condition. According to one embodiment of the present invention, the mechanism
includes a push button that is pressed to operate the circuit breaker in the TRIP
condition.

[00] 9] These and other objects and advantages of the present invention will become readily apparent from the following detailed description taken in conjunction with the accompanying drawings.
E) BRIEF DESCRIPTION OF THE DRAWINGS
[0020] The other objects, features and advantages will occur to those skilled in
the art from the following description of the preferred embodiment and the
accompanying drawings in which:
[0021] FIG. 1 illustrates an isometric view of the circuit breaker with a torsion
spring mechanism, according to one embodiment of the present invention.
[0022] FIG. 2 illustrates a detailed view of the circuit breaker mechanism,
according to one embodiment of the present invention.
[0023] FIG. 3 illustrates the perspective view of the mechanism in different
orientations in circuit breakers, according to one embodiment of the present
invention.
[0024] FIG.4 illustrates the perspective view of the spring mechanism when the
circuit breaker is in an ON condition, according to one embodiment of the present
invention.
[0025] FIG.5 illustrates the perspective view of the spring mechanism, when the
circuit breaker is in OFF condition, according to one embodiment of the present
invention.
[0026] FIG.6a illustrates the perspective view of the spring mechanism, when the
circuit breaker is in OFF condition, according to one embodiment of the present
invention.
[0027] FIG.6b illustrates the perspective view of the spring mechanism showing
the directions of motion of a Push button, Trip Lock and Trip link when the circuit
breaker is in TRIP condition, according to one embodiment of the present invention.

[0028] FIG.7 illustrates a perspective view of the mechanism showing the
positions of the contact link, upper slider and the lower slider during the circuit
breaker ON condition, according to one embodiment of the present invention.
[0029] FIG.8 illustrates a perspective view of the mechanism showing the
positions of the contact link, upper slider and the lower slider during the circuit
breaker OFF condition, according to one embodiment of the present invention.
[0030] Fig. 9a shows Circuit Breaker in ON condition and Main mechanism
spring in Released condition and Contact link locked by Lower slider, according to
one embodiment of the present invention.
[0031] Fig. 9b shows Knob rotating and thus charging the Main mechanism
spring while moving from ON to OFF state, according to one embodiment of the
present invention.
[0032] Fig. 10a shows positions of a knob, a contact Link, a trip link, a lock link
in TRIP state, according to one embodiment of the present invention.
[0033] Fig. 10b shows positions of a knob, a contact Link, a trip link, a lock link
in different orientation, according to one embodiment of the present invention.
[0034] Fig. 10c shows positions of a knob, a contact Link, a trip link, a lock link
in RESET state, according to one embodiment of the present invention.
[0035] Although the specific features of the present invention are shown in some
drawings and not in others. This is done for convenience only as each feature may be
combined with any or all of the other features in accordance with the present
invention.
F) DETAILED DESCRIPTION OF THE INVENTION
[0036] In the following detailed description, a reference is made to the
accompanying drawings that form a part hereof, and in which the specific embodiments that may be practiced is shown by way of illustration. These embodiments are described in sufficient detail to enable those skilled in the art to practice the embodiments and it is to be understood that the logical, mechanical and

other changes may be made without departing from the scope of the embodiments. The following detailed description is therefore not to be taken in a limiting sense. |0037] The various embodiments of the present invention provide a spring mechanism for circuit breakers. The mechanism includes a contact link, an upper slider connected to the contact link, a lower slider connected to the contact link, an upper slider box housing the upper slider, a lower slider box housing the lower slider, a knob and a main mechanism spring. The main mechanism spring generates the required spring energy based on sliding operation of the upper slider and the lower slider when the knob is rotated to operate the circuit breaker in at least one of an ON, OFF and a TRIP condition.
|0038] FIG. 1 illustrates an isometric view of the circuit breaker with a torsion spring mechanism, according to one embodiment of the present invention. The isometric view of the circuit breaker mechanism includes a knob 102, a side plate 104, a reset link 106, a push button 108, a push button box 110, and a spacer shaft 112. The knob 102 is rotated to operate the circuit breaker in at least one of an ON, OFF and a TRIP condition.
[0039] The side plate 104 houses a torsion spring mechanism in the circuit breaker. The knob 102 is the spring actuating device and facilitates the ON-OFF operation of the circuit breaker. The reset link 106 is actuated during the RESET condition of the circuit breaker by the knob 102.
[0040| The reset link 106 rotates, when the knob is rotated to operate the circuit breaker in at least one of an ON condition, an OFF condition and a TRIP condition. The rotation of the reset link 106 in turn actuates a TRIP link and brings the TRIP link to an original position.
[0041] The push button 108 is an actuating component and is pushed to TRIP the circuit breaker. The push button 108 is housed in the push button box 110. The push button box is the outer casing which guides the push button and the actuating spring. The mechanism also includes the spacer shaft 112 to maintain the spacing between the side plates 104.

[0042] FIG. 2 illustrates a detailed view of the circuit breaker mechanism. according to one embodiment of the present invention. The mechanism includes a trip spring 202, an upper slider box 204, a lower slider box 206, a contact link 208, and a slot 210. The trip Spring 202 is a torsion spring which is assembled in charged condition and is actuated only when the TRIP signal is received through the push button. The upper slider box 204 is the outer casing which houses an upper slider and an actuating spring. The lower slider box 206 is the outer casing which houses a lower slider and the actuating spring. The contact link 208 is the link on which the electrical contacts are mounted. The rotation of the contact link facilitates the making or breaking of the circuit.
[0043] FIG. 3 illustrates the perspective view of the mechanism in different
orientations in circuit breakers, according to one embodiment of the present
invention. The mechanism includes the knob 102, the trip spring, a main shaft 302,
and a main mechanism spring 304. The knob is rotated in anticlockwise direction to
change the circuit breaker state from the ON to the OFF condition. The knob is
mounted on the main shaft 302. The knob is attached with the main mechanism
spring 304. One end of the main mechanism spring includes a torsion spring fixed
arm and another end of the main mechanism includes a Torsion spring moving arm.
[0044] When the knob 102 is moved from ON to OFF condition or vice versa.
the torsion spring fixed arm remains fixed on to the knob I due to a spring stopper
Link. The torsion spring moving arm is attached to the contact link and is in locked
state due to which the main mechanism spring 304 remains in released condition.
[0045| FIG.4 illustrates the perspective view of the spring mechanism when the
circuit breaker is in an ON condition, according to one embodiment of the present invention, while FIG.5 illustrates the perspective view of the spring mechanism, when the circuit breaker is in OFF condition, according to one embodiment of the present invention. With respect to FIG.4 and FIG.5, the spring mechanism includes the knob 102, a lower slider 502. and the contact link 208.

(0046] When the circuit breaker is in the ON condition, both the knob 102 and the contact link 208are in the ON condition. Further the main mechanism spring is in released condition. The main mechanism spring is charged when the circuit breaker is in the ON condition. The circuit breaker is in the OFF condition with the contact link 208 is in the open condition. Further the contact link 208 in the open condition is locked by an upper slider.
[0047] When the knob 102 reaches an end position, the knobl02 is locked by the lower slider. Further before reaching the end position, the knob 102 pushes the lower slider 502 backwards and thereby unlocks the contact link 208. The unlocking of the contact link 208 is shown in Fig.5. When the contact link 208 reaches the end position, then the knob 102 is unlocked from the lower slider 502 and thereby releasing the Knob 102 for subsequent operations.
|0048] FIG.6a illustrates the perspective view of the spring mechanism, when the circuit breaker is in OFF condition, according to one embodiment of the present invention, while FIG.6b illustrates the perspective view of the spring mechanism showing the directions of motion of a Push button, Trip Lock and Trip link when the circuit breaker is in TRIP condition, according to one embodiment of the present invention. With respect to FIG.6a and FIG.6b the spring mechanism includes a trip link 602, a trip lock 604 and the push button 108. The contact link is in the open condition, when the knob 102 is in the intermediate position between the ON and the OFF condition.
[0049] The trip link 602 once released from the trip lock 604 rotates in an anticlockwise direction due to discharging of a trip spring. Further when the trip link 602 moves in anticlockwise direction, the contact link is also moved along with the trip link 602 to the open position. The trip link 602 is released from the trip lock 604 due to the downward movement of the push button.
[0050] FIG.7 illustrates a perspective view of the mechanism showing the positions of the contact link, upper slider and the lower slider during the circuit breaker ON condition, according to one embodiment of the present invention, while

FIG.8 illustrates a perspective view of the mechanism showing the positions of the
contact link, upper slider and the lower slider during the circuit breaker OFF
condition, according to one embodiment of the present invention. With respect to
FIG.7 and FIG.8, the mechanism includes the upper slider 702. the knob 102, and the
contact link 208.
[0051] The upper slider 702 slides in an upper slider box due to cam action by
the contact link. The upper slider 702 facilitates the locking or unlocking of the
contact link 208 based on sliding operation of the upper slider 702. The knob 102 is
rotated which in turn leads to sliding of the upper slider 702 and operates the circuit
breaker in at least one of the ON, the OFF and the TRIP condition.
[0052] The knob 102 is rotated which is mounted on main shaft in N
anticlockwise direction which in turn leads the main mechanism spring to gel
charged. The torsion spring moving arm remains locked with the contact link 208 and
the torsion spring fixed arm rotating with the Knob 102.
[0053] Fig. 9a shows Circuit Breaker in ON condition and Main mechanism
spring in Released condition and Contact link locked by Lower slider, according to
one embodiment of the present invention, while Fig. 9b shows Knob rotating and thus
charging the Main mechanism spring while moving from ON to OFF state, according
to one embodiment of the present invention. With respect to FIG.9a and FIG.9b, the
mechanism includes a torsion spring fixed arm 902, a torsion spring moving arm 904,
and the reset link 106.
[0054) When the knob 102 is moved from ON to OFF condition or vice versa.
the torsion spring fixed arm 902 remains fixed on to the Knob 102 due to a spring
stopper link. The torsion spring moving arm 904 is attached to the contact link 208
and is in locked state due to which the main mechanism spring remains in released
condition.
[0055] Fig. 10a shows positions of a knob, a contact Link, a trip link, a lock link
in TRIP state, according to one embodiment of the present invention, while Fig. 10b
shows positions of a knob, a contact Link, a trip link, a lock link in different

orientation, according to one embodiment of the present invention, while Fig. 10c shows positions of a knob, a contact Link, a trip link, a lock link in RESET state, according to one embodiment of the present invention. With respect to FIG.lOa-lOc, the mechanism includes the knob 102. the contact link 208. a spring stopper link 1002, the Trip link 602, and the Trip lock 604.
[0056| The spring Stopper Link 1002 is a link that arrests one end of the main
mechanism spring while moving the Knob 102 from the ON to OFF condition and vice versa. The spring stopper link 1002 is actuated, when the TRIP signal is received to open the slot on the knob 102 for discharging the main mechanism Spring. The push button is pressed to operate the circuit breaker in the TRIP condition. [0057] The knob 102 is rotated in clockwise direction which in turn rotates the reset Link in anticlockwise direction thereby pushing the trip link 602 downwards. The trip link 602 rotates in an anticlockwise direction due to the pushing of the trip link 602 downwards and which in turn leads to the mechanism come to a reset state.
G) ADVANTAGES OF THE INVENTION
[0058] The present invention provides for full utilization of spring potential energy to be converted in Kinetic Energy of the contacts. Further the mechanism provides for three distinct stable states for the circuit breaker namely ON, OFF & TRIP conditions. A higher contact opening velocity is also achieved by the spring mechanism discussed herein.
[0059] Although the invention is described with various specific embodiments, it will be obvious for a person skilled in the art to practice the invention with modifications. However, all such modifications are deemed to be within the scope of the claims.
[0060] It is also to be understood that the following claims are intended to cover
all of the generic and specific features of the present invention described herein and all the statements of the scope of the invention which as a matter of language might be said to fall there between.

CLAIMS
What is claimed is:
1. A slider based torsion spring mechanism for circuit breakers, the mechanism
comprising:
a contact link;
an upper slider connected to the contact link to lock and unlock the contact link;
a lower slider connected to the contact link;
an upper slider box housing the upper slider;
a lower slider box housing the lower slider;
a knob; and
a main mechanism spring;
Wherein the main mechanism spring generate spring energy based on sliding
operation of the upper slider and the lower slider when the knob is rotated to
operate the circuit breaker in at least one of an ON, OFF and a TRIP condition.
2. The mechanism according to claim 1. wherein the upper slider facilitates locking or unlocking of the contact link by sliding the upper slider into the upper slider box.
3. The mechanism according to claim 1. wherein the main mechanism spring is a torsion spring which is provided to operate the contact link in at least one of the ON position or the OFF position based on the sliding operation of the upper slider and the lower slider.
4. The mechanism according to claim 1, wherein the main mechanism spring is helical in shape.
5. The mechanism according to claim 1, wherein the knob is mounted on a main shaft in the circuit breaker.
6. The mechanism according to claim 1, wherein the knob and the contact link are in ON position during the operation of the circuit breaker in the ON condition.
7. The mechanism according to claim 1, wherein the upper slider locks the contact link when the circuit breaker is in the OFF condition.

S. The mechanism according to claim ), wherein the upper sJider shdes in the upper slider box and the lower slider slides in the lower slider box due to a cam action by at least one of the fork or the contact link.
9. The mechanism according to claim 1, further comprises a trip spring which is actuated when the circuit breaker is in the TRIP condition.
10. The mechanism according to claim 1, further comprises a push button to operate the circuit breaker in the TRIP condition.