Title of Invention

SHROUD LOCKING MECHANISM IN SWITCHING DEVICE

Abstract

Shroud locking mechanism in a switching device adapted to provide total safety to the operator comprises shroud (3) adapted to cover switch body and secure other current carrying parts with the switch being in ON position, latching elements (1) adapted to mechanically lock the said shroud (3), means (4) adapted to actuate the said latching elements (1) housed in the switching device, guide means (9) being located on the phase barriers (7) erected between the said shrouds (3) and adapted to provide guided motion to the latching elements (1) and means (6) provided on either side of the shroud adapted for operative disposition of the latching element (1) inside it thereby locking the shroud (3).`

Full Text

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. - SHROUD LOCKING MECHANISM IN SWITCHING DEVICE 2. Applicant (a) NAME : LARSEN & TOUBRO LIMITED (b) NATIONALITY : 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 Invention The present invention relates to a shroud locking mechanism. More particularly, the invention relates to a shroud locking mechanism in a switching device comprising moving element adapted for providing total safety to the operator and apparent indication of the locking or unlocking state of the shroud. Background Art Electrical switches in general serve the purpose of protection and isolation of the load for maintenance and safety. There is a risk of human contact with the live parts during work, which necessities the use of protective shrouds on the switches. It is also known that such safety shrouds are mounted on the switches by providing a locking mechanism, which would deter the operator from opening the switch covers or shrouds when the switch is in ON condition or the current carrying path inside the switch is live. US Patent No. 5686708 discloses a fuse shield cover wherein the shield cover is hinged on the switch, prevents access to the fuses when the switch is in closed position and permitting access when the switch is in open position, by means of interlock rod connected to the lever within the housing of the disconnect switch. Thus there is a need to provide a shroud locking mechanism in switching device comprising moving element adapted for providing total safety to the operator and apparent indication of the locking or unlocking state of the shroud. 2 Object of Invention Thus the basic object of the present invention is to achieve the locking of the shroud by the actuating motion of the moving element. Yet another object of the present invention is to give an apparent indication of locked position of the shroud. The other object of the present invention is to positively lock the shroud even if the contacts get welded. Summary of Invention Thus according to the basic aspect of the present invention there is provided a shroud locking mechanism in a switching device adapted to provide total safety to the operator and apparent indication of locking, the said mechanism comprising: (i) shroud adapted to cover switch body and secure other current carrying parts with the switch being in ON position; (ii) latching elements operatively disposed in the said shroud adapted to mechanically lock the shroud; (iii) means adapted to actuate the said latching elements housed in the switching device; (iv) guide means being located on the phase barriers erected between the said shrouds and adapted to provide guided motion to the latching elements; and (v) means provided on either side of the shroud adapted for operative disposition of the latching element inside it thereby locking the shroud. 3 Detailed description of Invention The present invention is related to the safety feature associated with the switching device wherein protection is provided to the operator when the switch is in ON condition by mechanically locking the shrouds. The shroud locking mechanism of the present invention comprises latching elements adapted for mechanically locking the shroud by getting protruded out of the cavities provided in the shroud wherein the said shroud is adapted as protective means for securing the switch body and other current carrying parts, which become live when the switch is in ON condition. The said latching element comprises of spring loaded restrainers, which is further slided by guide means. The said guide means comprises protrusions on the phase barrier erected between two shrouds fitted on to the front housing. The means adapted for actuating the said spring loaded restrainers comprises moving bridge element housed in the switching device. The said moving bridge element derives its motion from the operating shaft located in the switch in a manner that it is adapted for guiding the restrainers deterring it from being lifted when an attempt is made to remove the shroud when switch is in ON position. The moving bridge element being positioned at a pre-determined distant from the front housing such that there is no physical contact between the cam profile on the moving bridge element and the cam profile of restrainer, when the switch is in OFF condition. Due to this the said restrainers are not protruding out of the cavities which are provided on the shroud thus allowing the shroud to get pulled out when switch is in ON position, thus providing access to the operating personnel to the internal parts of the switch in OFF condition. Further, when the switch is in transition from OFF position to ON position, the gap between the said moving bridge and the said restrainer is reduced, due to this movement the said 4 cam profile of the moving bridge touches the cam profile of the restrainer and further movement of the moving bridge to achieve its corresponding position in ON condition causes the lateral movement of the restrainers in either directions to lock the shroud. The front housing comprises of cover adapted for housing spring means and part of the restrainers. The said spring means comprises compression springs, which are housed in the cover and located in operative connection with the restrainer such that it is adapted for exerting force on to the restrainer when switch is in OFF position. Due to this force exerted form compression springs, the restrainers do not create any interference with the shroud making the upward movement of the shroud possible allowing the shroud to be lifted when the switch is in OFF position. The moving bridge element comprises cam-like profile adapted for generating force as the moving bridge element comes in contact with the restrainer. The cam profile being provided such that force so generated resolve in two directional component; one is vertically upward (towards cover) and one is in lateral direction (towards restrainer). The upward acting force tries to lift the said restrainer, but since the cover is so fitted on the front housing that the said upward acting force is neutralized not having virtually ariy effect on the restrainer. However, the lateral force, which is generated in the direction of the restrainer has a tendency to move the restrainer towards the cavity on the shroud. As restrainers are free to travel in these opposite directions their translational movements continue till the moving bridge reaches the ON position, wherein the cam profile of the restrainer completely resets on that of the moving bridge. The distance traveled by two restrainers in opposite directions is sufficient enough to create an interference with shroud. The restrainer comprises protrusions out of the shroud from either end is adapted to give an apparent indication to the operator that the shrouds are locked and the switch is in ON condition. 5 Further, the guide is so provided on the phase barrier for the restrainer, that it is adapted for obstructing, not allowing the restrainer to get lifted when an attempt is made to remove shroud from its ON position, thereby providing secured locking. In case, the moving contact gets welded due to excessive current flow in abnormal conditions, and during this course if an attempt is made to switch OFF the switching device, some motion transferring mechanical components of the switch can fail and the switch may show wrong position but since the actuating motion in present invention is derived from the bridge itself the said restrainers will continue to lock the shroud providing positive locking. Brief description of the accompanying figures Figure 1 illustrates an isometric view of the shroud mechanism when mounted on the switching device. Figure 2A illustrates the shroud mechanism when the switching device is in switched OFF condition. Figure 2B illustrates the shroud mechanism when the switching device is in switched ON condition. Detailed description of the accompanying figures In figure 1 an isometric view of the shroud mechanism when mounted on the switching device is illustrated. In the figure restrainer (1) being operatively connected to the guide (9) (also shown in figure 2A) provided in the front housing (8) adapted for creating interference with the shroud (3). The cover (2) is adapted to house the compression springs (5) (shown in figure 2A) and part of the restrainer (1). The shroud (3) on its either side comprises of the cavity (6) 6 adapted for popping up action of the restrainer (1) and creating interference. The phase barrier (7) is located between two shrouds (3) fitted on to the front housing (8). In figure 2A the shroud mechanism when the switching device is in switched OFF condition is illustrated. In OFF condition the moving bridge (4) being located at a pre-determined distant position from the front housing (8) in a manner that there is no contact of cam profile (10b) on the moving bridge (4) with that of cam profile (10a) of restrainer (1). The compression spring (5) being is in operatively connection with the restrainers (1). The shroud (3) comprises of the cavities (6) wherein the restrainer (1) is operatively disposed. In figure 2B the shroud mechanism when the switching device is in switched ON condition is illustrated. In the figure the upward position of the moving bridge (4) from its OFF position (referring to figure 2A) is realizable. The restrainer (1) is moved towards the cavity (6) by the action of the lateral force. The guide (9) is so provided on the phase barrier (7) for the restrainer (1), also acts as an obstruction and adapted not allowing the restrainer (1) to be lifted up when an attempt is made to remove shroud (3) from its ON position, thereby providing secured locking. 7 We Claim 1. A shroud locking mechanism in a switching device adapted to provide total safety to the operator and apparent indication of locking, the said mechanism comprising: (i) shroud adapted to cover switch body and secure other current carrying parts with the switch being in ON position; (ii) latching elements operatively disposed in the said shroud adapted to mechanically lock the shroud; (iii) means adapted to actuate the said latching elements housed in the switching device; (iv) guide means being located on the phase barriers erected between the said shrouds and adapted to provide guided motion to the latching elements; and (v) means provided on either side of the shroud adapted for operative disposition of the latching element inside it thereby locking the shroud. 2. Shroud locking mechanism as claimed in claim 1, wherein the latching element comprising of spring loaded restrainers; said restrainers having cam profile being located such that they can be adapted to slide along with the guide means to lock the shroud. 3. Shroud locking mechanism as claimed in claim 2, wherein the spring loaded restrainers comprising protrusions being operatively disposed out of the shroud from either ends in a manner that there is an apparent indication to the operator that the shrouds are locked and the switch is in ON condition. 4. Shroud locking mechanism as claimed in claims 2 to 3, wherein the said restrainers is adapted to persist locking condition of the shroud even if an 8 attempt is made to switch OFF the switching device at times when the contacts get welded due to excessive current flow in abnormal conditions. 5. Shroud locking mechanism as claimed in claim 1, wherein the means to actuate the spring loaded restrainers comprises moving bridge element; said bridge element having cam-like profile being positioned at a pre-determined distant from the front housing such that there is no physical contact between the cam profile on the moving bridge element and the cam profile of restrainer when the switch is in OFF condition. 6. Shroud locking mechanism as claimed in claim 5, wherein the said cam-like profile adapted to generate force on contact of the moving bridge element with the spring loaded restrainer is provided such that the resolution of the generated force comprises two directional components; wherein the said components comprises vertically upward force adapted for lifting the said restrainer and the lateral directive force adapted for sliding the restrainer towards either sides of the shroud. 7. Shroud locking mechanism as claimed in claim 1, wherein the guide means comprises protrusions on the phase barrier erected between two shrouds fitted on to the front housing guiding the restrainers and deterring it from being lifted when an attempt is made to remove the shroud when switch is in ON position. 8. Shroud locking mechanism as claimed in claim 1, wherein the means provided on either side of the shroud adapted for operative disposition of the latching element inside it thereby locking the shroud comprises cavities provided on the shroud thus allowing the shroud to get pulled out when switch is in ON position thereby providing access to the operating personnel to the internal parts of the switch in OFF condition. 9 9. Shroud locking mechanism substantially as herein described and illustrated with reference to the accompanying figures. 10 ABSTRACT Title: Shroud Locking Mechanism in Switching Device Shroud locking mechanism in a switching device adapted to provide total safety to the operator comprises shroud (3) adapted to cover switch body and secure other current carrying parts with the switch being in ON position, latching elements (1) adapted to mechanically lock the said shroud (3), means (4) adapted to actuate the said latching elements (1) housed in the switching device, guide means (9) being located on the phase barriers (7) erected between the said shrouds (3) and adapted to provide guided motion to the latching elements (1) and means (6) provided on either side of the shroud adapted for operative disposition of the latching element (1) inside it thereby locking the shroud (3). Figure 2A

Documents:

0715-MUM-2005-CORRESPONDENCE 1-8-2008.pdf

715-mum-2005-abstract(granted)-(11-8-2010).pdf

715-mum-2005-abstract.doc

715-mum-2005-abstract.pdf

715-mum-2005-claims(granted)-(11-8-2010).pdf

715-mum-2005-claims.doc

715-mum-2005-claims.pdf

715-mum-2005-correspondance-received-ver-080705.pdf

715-mum-2005-correspondance-received-ver-110705.pdf

715-mum-2005-correspondance-received.pdf

715-MUM-2005-CORRESPONDENCE(15-2-2010).pdf

715-MUM-2005-CORRESPONDENCE(16-6-2010).pdf

715-MUM-2005-CORRESPONDENCE(19-2-2009).pdf

715-MUM-2005-CORRESPONDENCE(20-7-2009).pdf

715-mum-2005-correspondence(23-4-2008).pdf

715-MUM-2005-CORRESPONDENCE(26-7-2010).pdf

715-mum-2005-correspondence(ipo)-(11-8-2010).pdf

715-mum-2005-description (complete).pdf

715-mum-2005-description(granted)-(11-8-2010).pdf

715-mum-2005-drawing(granted)-(11-8-2010).pdf

715-mum-2005-drawings.pdf

715-mum-2005-form 1(8-7-2005).pdf

715-mum-2005-form 18(17-9-2007).pdf

715-mum-2005-form 2(granted)-(11-8-2010).pdf

715-mum-2005-form 2(title page)-(17-6-2005).pdf

715-mum-2005-form 2(title page)-(granted)-(11-8-2010).pdf

715-mum-2005-form-1.pdf

715-mum-2005-form-2.doc

715-mum-2005-form-2.pdf

715-mum-2005-form-26.pdf

715-mum-2005-form-3.pdf

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