FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
&
The Patents Rules, 2003
COMPLETE SPECIFICATION
(See section 10; rule 13)
1. Title of the invention. - A PADLOCKABLE PUSH BUTTON
2. Applicant
(a) NAME : LARSEN & TOUBRO LIMITED
(b) NATIONALITY : An Indian Company
(c) ADDRESS : L&T House, Ballard Estate, Mumbai 400 001,
State of Maharashtra, India
3. PREAMBLE TO THE DESCRIPTION
The following specification particularly describes the invention and the manner in which it is to be performed:

Field of the invention
The present invention relates to a padlocking assembly for push buttons in circuit breakers, switchgears and the like which are used to carry and break current supplies in normal and abnormal operating conditions. More particularly, the invention is concerned about a unique way of locking push buttons by plurality of padlocks so as to keep the OFF push button in the locked position as the application demands.
Background and the prior art
Generally, circuit breakers, switchgears are used to carry current at normal situation and identify disturbances / abnormal current situations and accordingly break the current supply. It turns off automatically whenever any abnormal condition occurs in the power system. Circuit breakers consist of the tripping releases for tripping under abnormal operating conditions.
Commonly, for the operation of circuit breaker there are two push buttons provided on the front facia, i.e. ON button, and an OFF button.
ON Push button as the name suggests, is for switching ON the power supply by making/closing of separable contacts within the circuit breaker or henceforward called as a switching device. The OFF Push button is for switching off the switching device.
As per normal requirement of its application for maintenance it is always essential to maintain the circuit breaker in OFF position. Although this can be done by the OFF push button, at times it is required that this position is maintained for some time and it is extremely dangerous to switch ON the switching device at this point of time. Such a situation is obtained if the OFF push
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button of the ACB remains in pressed condition. This can be provided by a Locking the push button in its pressed state. Locking of this OFF push button can be by either a cylindrical lock or by a pad lock as the application demands.
US5808252 describes a pad lockable emergency stop button used to stop the movement of the pushbutton by a push and unlocked by rotation. Such a design has serious limitation in terms of the space used and the number of padlocks that can be accommodated in the design. When used along with a switching device pulling/pushing of the blocking lever do consume some operational space/ volume. Also such a concept is side ways actuated is not suitable for a front locking arrangement i.e. when both the push button to be locked and the assembly used for locking are in the same plane.
US publication no. 2005/0133348 A1 discloses a pad lockable push button. Here the pad lock is directly on the collar of the push button, and differs from the one we are proposing in this invention. Here the pad lock getting directly mounted on the push button seriously damages the front of push button and is usually not a healthy design practice.
US5,945,648 describes a circuit breaker interlock mechanism interacts between the circuit breaker operating handle and circuit breaker closing button to prevent the closing button from operating to close the circuit breaker contacts when the circuit breaker is padlocked in the OFF condition. A slide plate mounted on the interior of the circuit breaker cover engages a blocking plate attached to the circuit breaker closing rod. The interlock serves further to prevent the circuit breaker from being padlocked on the ON condition in the event the contacts become welded together in the closed position. No such arrangements were known for locking OFF push button by plurality of padlocks and to accommodate various cylinder locks so as to achieve secured locking of the push button in the OFF state and simultaneously preventing the ON push button from being operated.
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Thus there is a need to provide for a unique way of locking push buttons by plurality of padlocks so as to keep the OFF push button in the locked position as the application demands.
The present inventors have now found that an innovative arrangement may be provided which could padlock the OFF push button and therefore prevents the closing of contactors even if the ON push button is pressed accidentally. This is would provide safety of operation to the user.
Objects of the invention
Accordingly one object of the present invention is to overcome the disadvantages of the prior art.
Another object of the present invention is to provide a unique padlocking assembly for OFF push buttons for use in the circuit breakers, switchgears and the like.
Another object of the present invention is to provide padlocking of OFF push buttons at its pressed position or state / actuated position or state.
Yet another object is to provide flexibility in using various types of cylindrical locks in the assembly.
Summary of the invention
Accordingly, the aspect of the present invention is to provide a padlocking assembly for locking OFF push buttons used in circuit breakers, switchgears and the like, said locking assembly comprising :
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fixed component comprising a pre-determined groove means and circular cut means
wherein the groove means being such that it accommodates a slider means and allows its reciprocating motion inside the groove, said slider means having an oblong hole, said slider comprising projection means located perpendicular to the fixed component, said projection means comprising a rounded portion and a narrower portion;
drum means comprising plural holes located circumferentially at pre-determined spacing from each other,
wherein said drum means comprises plunger means projecting upto a certain distance so as to get engaged with the oblong hole of slider means thereafter extending to rest in the circular cut means of the fixed component;
cover means concentric to the drum means in a manner to allow the drum means to have free rotational movement about its axis, wherein said cover means comprising plural holes located circumferentially at pre-determined spacing from each other
wherein the circular cut being such that by rotation the drum means can be displaced to appropriate angles
thereby moving the slider means in linear direction thus aligning holes of the drum means and the cover means so that padlocks and/or cylindrical locks can be slipped into both the holes for locking of OFF push button such that even if the ON push button is pressed contactors will not be closed;
compression spring engaged with projection means of the slider means in a manner so as to keep the slider means at its outermost state corresponding to
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the unlocked state of the assembly and to force the slider means to its original state when padlocks and or cylindrical locks are removed from the holes of the drum and the cover means.
Detailed description of the present invention
In the present invention padlocking assembly comprises a fixed component comprising a pre-determined groove means and circular cut means. The groove means is such that it accommodates slider means and allows its reciprocating motion inside the groove. The slider means has an oblong hole. The groove means comprises T-shaped channel to accommodate the slider. The circular cut of the fixed component comprises two notch-like profiles and a projection on which the plunger rests.
One embodiment of the present invention describes a drum means comprising plural holes located circumferentially at pre-determined spacing from each other. The drum means comprises plunger means projecting up to a certain distance. The plunger gets engaged with the oblong hole of slider means thereafter passing to circular cut means of the fixed component. Cover means are located concentric to the drum means in a manner to allow the drum means to have free rotational movement about its axis. The cover means is a cylindrical barrel, which comprises plural holes located circumferentially at pre-determined spacing from each other.
One embodiment of the invention describes the slider comprising a projection perpendicular to the fixed component. The projection comprises a rounded portion at its far end and narrower portion at its base fixing the adjoining the projection to the slider. The narrow portion is such that it just accommodates itself in the longitudinal channel of the T-shaped channel and supports the slider to perform the reciprocating motion during locking operation.
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The fixed component comprises the circular cut which is such that by rotation, the drum means can be displaced to appropriate angles thereby moving the slider means in linear direction thus aligning holes of the drum means and the cover means so that padlocks and/or cylindrical locks can be slipped into both the holes for locking of OFF push button such that even if the ON push button is pressed contactors will not be closed.
One embodiment of the invention describes a compression spring operatively located between the rounded portion of the projection of slider means and another rounded projection present in the fixed component
Brief description of the accompanying figures
Figure 1 shows the isometric view of entire assembly of the switching device.
Figure 2 shows the arrangement of the push button from the back.
Figure 3 shows an exploded view of the pad lock assembly of the present invention.
Figure 4 shows the back view of the entire pad lock assembly of the present invention.
Figures 5A and 5B show functionality of the pad lock assembly of the present invention.
Detailed description of the accompanying figures
Figure 1 shows the entire assembly the switching device (1). This for the ease of description is further splitted into two parts. (1A) Generally housing the contacts
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and the mechanism and (1B) generally referred to as the facia of the switching device.
In this figure are seen two push buttons identified as an ON push button (2) and an OFF push button (3). Along with the OFF push button seen is the pad lock assembly (4).
Figure 2 shows the arrangement of the push button from the back. Push button (2) and (3) have a plunger each that correspond to the mechanism placed inside. While these buttons are pushed this results in pushing a lever of the mechanism making it open and close, as be the situation. Hence to disable the operation of accidental switching ON of the device, it is essential to keep the OFF push button pressed. Under this condition the pressing of the ON push button doesn't close the separable contacts.
In figure 3 and 4 the assembly consists of five physical parts/components. It consists of a fixed component (5) which has a groove (10) in which a slider (6) reciprocates for locking the OFF Push button. Slider (6) has an oblong hole (6A) in which the plunger (7A) of a rotating cylindrical drum (7) gets engaged. The plunger (7A) passes through an oblong circular cut (5A) on the fixed component. The circular drum has at least one hole. Three circumferential hole (7B) are located on the circular drum. The slider (6) comprises projection (6B) which comprises rounded portion (6C) and narrower portion (6D). The fixed component comprises another rounded projection (5B). The circular cut of the fixed component comprises two notch-like profiles (5C) and a projection (5A) on which the plunger (7A) rests.
Drum (7) is free to rotate inside a barrel fixer (8). The barrel fixer (8) and the fixed component (5) is together screwed with the facia a screwing means from the front. The barrel fixed (8) has at least one hole. Three circumferential holes (8A)
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are located on the barrel. The switching device facia (1B) has a cut corresponding to the collar diameter of the component (8) and also holes corresponding to the fixing holes provided on the component (8) and (5).
Once assembled, collar of the component (8) comes out of the facia (1B). Mounting holes on component (5) and (8) gets aligned and gets fixed to the corresponding hole of the facia.
The cylindrical drum (7) is concentric to the barrel (8) with its plunger (7A) passing through the corresponding groove (5A) on the fixed element.
The cylindrical drum can rotate within the barrel and its motion is restricted the slot (5A) on the fixed component. The angular motion permitted for the rotation of the plunger (7A) is restricted to -45 degrees to +45 degrees as viewed from the front.
This plunger further engages itself with the oblong hole (6A) of the slider (6). The slider is free to slide within the fixed component and has a compression end attached to the end on it. This compression spring (9) keeps the slider in its outer most state corresponding to the unlocked state of the assembly.
Figure 5A shows, OFF state of the switching device and unlocked state of push button. In this case the OFF button is free to be pressed.
Also in this state, by design, the holes on the barrel (8) and circular drum (7) don't match with each other. In fact they are 90 degrees circumferentially apart. In this state, hence by design, pad locks cannot be slipped in since there is no clear through hole available for it.
In order to lock one needs to rotate the circular drum (7) so that the holes on it get aligned with the holes on the barrel (8). This rotation of the circular drum and hence the plunger (7A) makes the slider move in a corresponding slot provided on the OFF push button. While rotating the circular drum the OFF push button
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needs to be kept in pressed condition. This locks the OFF push button in its pressed state, as shown in Image 5B.
In this state all the three holes on the barrel and cylindrical drum gets aligned with each other and hence one or more pad lock can be slipped through the aligned holes of the barrel (8) and the circular drum (7). Till the locks are removed the barrel inside cannot rotate back to its original state and hence the OFF push button remains locked.
Once the lock/ locks are removed, the compression spring (9) forces the slider (6) to its original state and due to this the drum rotates back by 90 degrees to its original unlocked state.
This now frees the OFF push button and hence further operations may now be carried on the switching device.
The invention has been shown and described in a preferred form only and many variations may be made in the invention, which will still be comprised within its spirit. It is understood, therefore, that the invention is not limited to the details cited above. The circular cut angles, plunger, screwing means, no. of holes on the drum and the barrel as herein described do not limit the scope of the present invention. The same can be replaced by its technical equivalence and yet the invention can be performed. The structure thus conceived is susceptible of numerous modifications and variations, all the details may furthermore be replaced with elements having technical equivalence. In practice the materials and dimensions may be any according to the requirements, which will still be comprised within its true spirit.
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We claim
1. A padlocking assembly for locking OFF push buttons used in circuit breakers, switchgears and the like, said locking assembly comprising:
fixed component comprising a pre-determined groove means and circular cut means
wherein the groove means being such that it accommodates a slider means and allows its reciprocating motion inside the groove, said slider means having an oblong hole, said slider comprising projection means located perpendicular to the fixed component, said projection means comprising a rounded portion and a narrower portion;
drum means comprising plural holes located circumferentially at predetermined spacing from each other,
wherein said drum means comprises plunger means projecting up to a certain distance so as to get engaged with the oblong hole of slider means thereafter passing to circular cut means of the fixed component;
cover means concentric to the drum means in a manner to allow the drum means to have free rotational movement about its axis, wherein said cover means comprising plural holes located circumferentially at pre-determined spacing from each other
Wherein the circular cut being such that by rotation the drum means can be displaced to appropriate angles
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thereby moving the slider means in linear direction thus aligning holes of the drum means and the cover means so that padlocks and/or cylindrical locks can be slipped into both the holes for locking of OFF push button such that even if the ON push button is pressed contactors will not be closed;
compression spring engaged with projection means of the slider means in a manner so as to keep the slider means at its outermost state corresponding to the unlocked state of the assembly and to force the slider means to its original state when padlocks and or cylindrical locks are removed from the holes of the drum and the cover means.
2. A padlocking assembly as claimed in claim 1 wherein the drum means comprises at least one hole.
3. A padlocking assembly as claimed in claim 1 wherein the cover means is a cylindrical barrel.
4. A padlocking assembly as claimed in claim 3 wherein the barrel comprises at least one hole.
5. A padlocking assembly as claimed in claim 1 wherein the groove means comprises T-shaped channel.
6. A padlocking assembly as claimed in claim 1 wherein the circular cut comprises two notch-like profiles with a projection in between the notches so as to permit rotation of the drum whereby the plunger get located at appropriate angles.
7. A padlocking assembly as claimed in claim 6 wherein the angle ranges from -45° to + 45°.
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8. A padlocking assembly for locking OFF push buttons used in circuit breakers, switchgears and the like as herein substantially described and illustrated with reference to the accompanying figures.

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ABSTRACT
TITLE : A PADLOCKABLE PUSH BUTTON
The present invention relates to a padlocking assembly for locking OFF push buttons used in circuit breakers, switchgears and the like. The assembly comprises fixed component (5) comprising groove means (10) and cut means (7A), groove means (10) accommodates slider means (6) having an oblong hole (6A), slider comprises projection means (6B) comprising a rounded portion (6C) and a narrower portion (6D), drum means (7) with plunger means (7A) and plural holes (7B) located circumferentially at pre-determined spacing from each other, cover means (8) concentric to the drum means in a manner to allow the drum means (7) to have free rotational movement about its axis and the cover means (8) comprises plural holes (8A). The assembly comprises compression spring (9) engaged with projection means (6B) of the slider means (6).
Figure 4