FORM 2
THE PATENTS ACT, 1970 COMPLETE SPECIFICATION
(See Section 10)
CABINET LOCK WITH A SAFETY RELEASE
Numbered as dated
INVENTORS:
a) SHUBHO SANYAL
b) ROHIDASLASTE
APPLICANT:
M/s. LARSEN & TOUBRO LIMITED
L&T House, Ballard Estate, P.O. Box No 278,
Mumbai, 400 001, Maharashtra,
INDIA
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THE FOLLOWING SPECIFICATION PARTICULARLY DESCRIBES THE
NATURE OF THE INVENTION

CABINET LOCK WITH A SAFETY RELEASE
A) Technical field
[0001] The embodiments herein generally relate to enclosures, and more specifically to an enclosure and locking mechanism for mechanical, electrical, electronic components, and associated wiring and circuitry.
B) Background
[0002] Enclosures are commonly used to provide degree of protection to personnel against incidental contact with enclosed equipment and to provide a degree of protection against the surrounding environment for enclosed equipment. Typical enclosures include a box and a door hinged for frequent access to components within such enclosures for adjustments, maintenance, and inspection of components. Components within the enclosure may also be changed or replaced.
[0003] During enclosure installation, it is often desirable that settings of device and components remain undisturbed. Unauthorized or inadvertent changing of position of device or components may result in annoying interruptions to operation of device, serious damage to electrical apparatus, or even serious
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harm to person. For example, accidental actuation of a circuit breaker might result in shock to a workman performing electrical work or repair on equipment downstream from circuit breaker. Hence door should be securely locked while device is in operation. Door locking system should be full proof from accidental opening and only deliberate action should unable opening of door.
[0004] Device enclosed in this cabinet is required to protect electrical circuitry and equipment from damage due to abnormal condition, such as an overload condition or a relatively high level short circuit or fault condition. Electrical switching devices include, circuit switching devices and circuit interrupters such as circuit breakers, and other load controllers. In case of short circuit condition in distribution system, switching device cuts off supply, however separable contacts with switching device open up with an arc. These internal arc increases pressure within the enclosure. When pressure within the enclosure builds up, this may result in breaking the locking arrangement of the doors and bursting resulting in a potential accident.
[0005] The following U.S. patents and publications, the complete disclosures of which, in their entireties, are herein incorporated by reference provide some conventional solutions to coupling arrangement for the circuit breaker. U.S. Patent No. 6642446 discloses an enclosure for electrical components including a box with a hinged door or fastener attached cover and an interchangeable component management system and an interchangeable fastening system. U.S. Patent No. 4683736 discloses a cabinet lock with recessed handle.
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[0006] While the conventional solutions are advantageous for their intended purposes, the existing state of the art generally does not provide adequate solutions for lock mechanism that would prevent over-pressurization of a closed system to protect electrical circuitry and equipment from damage.
[0007] Hence, there is a need to develop a locking mechanism which would provide a locking mechanism to overcome over-pressurization of closed system due to overload condition or a relatively high level short circuit or fault condition.
C) Object of the invention
[0008] An object of the embodiment is to provide an enclosure for mechanical, electrical, electronic components, and associated wiring and circuitry
[0009] Another object of the embodiment is to provide a locking mechanism to overcome over-pressurization of closed system due to overload condition or a relatively high level short circuit or fault condition.
[0010] Another object of the embodiment is to provide an enclosure for protection of personnel against incidental contact with enclosed equipment and to provide protection against surrounding environment for enclosed equipment.
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[0011] Yet another object of the embodiment is to provide a lock assembly that would release excess pressure built in case on internal arc which causes potential accident due to bursting of the door or enclosure.
D) Summary
[0012] The embodiments herein provide a lock assembly for protection of personnel against incidental contact with enclosed equipment and to provide protection against the surrounding environment for enclosed equipment. The embodiments also provide a locking mechanism to overcome over-pressurization of closed system due to overload condition or a relatively high level short circuit or fault condition.
[0013] The embodiment provides enclosure and locking assembly that prevents accidental, intentional, non-intended access to any mechanical, electrical, electronic components, and associated wiring and circuitry housed.
[0014] While opening locking system a user has to push and then rotate actuator there by having an element of deliberate action for access within. The two actions need to be performed in synchronous to open door of enclosure. In case of short circuit condition in distribution system, switching device cuts off supply, however separable contacts with switching device open up with an arc. These internal arc increases the pressure within the enclosure. When
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pressure within the enclosure builds up, this may result in breaking the locking arrangement of the doors and bursting that might result in accident. In this case pressure developed inside the enclosure is released due to constructional arrangement, preventing the pressure inside to shoot up.
[0015] These and other aspects of the embodiments herein will be better appreciated and understood when considered in conjunction with the following description and the accompanying drawings. It should be understood, however, that the following descriptions, while indicating preferred embodiments and numerous specific details thereof, are given by way of illustration and not of limitation. Many changes and modifications may be made within the scope of the embodiments herein without departing from the spirit thereof, and the embodiments herein include all such modifications.
E) Brief description of the drawings
[0016] The embodiments herein will be better understood from the following detailed description with reference to the drawings, in which:
[0017] FIG. 1 illustrates a complete layout of enclosure;
[0018] FIG.2 illustrates a general isometric view of lock assembly;
[0019] FIG.3 illustrates top view of entire assembly in open condition;
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[0020] FIG.4 illustrates a top view of entire assembly in closed condition;
[0021] FIG.5 illustrates top view of entire assembly in a situation of an internal arc;
[0022] FIG.6 illustrates isometric view of lock assembly with alternatives of the access knob;
F) Detailed description of the Invention
[0023] The embodiments herein and the various features and advantageous details thereof are explained more fully with reference to the non-limiting embodiments that are illustrated in the accompanying drawings and detailed in the following description. Descriptions of well-known components and processing techniques are omitted so as to not unnecessarily obscure the embodiments herein. The examples used herein are intended merely to facilitate an understanding of ways in which the embodiments herein may be practiced and to further enable those of skill in the art to practice the embodiments herein. Accordingly, the examples should not be construed as limiting the scope of the embodiments herein.
[0024] A preferred embodiment provides a locking assembly for protection of personnel against incidental contact with enclosed equipment and to provide protection against surrounding environment for enclosed equipment. The embodiment provides a locking mechanism to overcome over-pressurization of
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closed system due to overload condition or a relatively high level short circuit or fault condition.
[0025] While opening locking system a user has to push and then rotate actuator there by having an element of deliberate action for access within. The two actions need to be performed in synchronous to open the door of the enclosure. In case of short circuit condition in distribution system, switching device cuts off the supply however separable contacts with switching device open up with an arc. These internal arc increases the pressure within the enclosure. When pressure within the enclosure builds up, this may result in breaking the locking arrangement of the doors and bursting resulting in a potential accident. In this case pressure developed inside the enclosure is released due to constructional arrangement, preventing pressure inside to shoot up.
[0026] FIG. 1 illustrates a complete layout of enclosure. Enclosure consists of four channel member 102a, 102b, 102c, 102d fixed with each other to form a skeleton of enclosure. To channel skeleton, five metallic plates 104a, 104b, 104c, 104d, 102e are screwed from all sides to make it a completely covered except one face as shown in the FIG. 1. A door 106 is hinged by a suitable hinge 108 at one end. The door 106 can swivel about door axis enabling access to the inside enclosure while it is open. Lock assembly 110 is mounted on free end of door 106. The entire door 106 has a rubber beading 112 that acts as a gasket and ensures no gap between the enclosure walls and door 106 once door 106 is closed.
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[0027] FIG.2 illustrates a general isometric view of lock assembly 110. Assembly 110 consists of a housing barrel 114 intended to house entire assembly, an access knob 116, a compression spring 118, a locking lever 120, a pin 122, a fixing nut 128, a stopper pin 130. Access knob 116 is used to lock and unlock door 106 by rotating it 90 degrees clockwise. The rotation of access knob 116 is directly coupled to the locking lever 120 that gets trapped behind channels once it is rotated by 90 degrees clockwise. On reverse rotation by 90 degrees anticlockwise, lever 120 gets out of channel member and enables door 106 to be opened. Access knob 116 rests on housing barrel 114 over compression spring 118 which is intended to release pressure in case of internal arc. Access knob 116 and locking lever 120 get connected by pin 122 with compression spring 118 sandwiched in between. Housing barrel 114 is characterized by two slots 124 and 126. Slot 124 is intended for locked state of lock assembly 110 where after quarter turn rotation pin 122 it rests in slot 124 Slot 126 is allowable portion for pin 122 to rotate by quarter turn. Pin 122 can not move beyond this and hence access knob 116 also can not move. This ensures proper 90 degree rotation for opening and closing of panel door 106. Entire lock assembly 110 is screwed to door 106 from back by fixing nut 128. Stopper pin 130 controls axial movement of locking lever 120 into barrel 114.
[0028] FIG.3 illustrates top view of the entire assembly in open condition. Lock assembly 110 is open that enables door 106 to swivel and allow access to the components, switching devices for installation, checking, replacement etc.
[0029] FIG.4 illustrates a top view of entire assembly in closed condition. For
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locking the door 106, entire door 106 needs to be swiveled back to close it against channel and access knob 116 needs to be rotated by 90 degrees. With rotation of knob 116, the locking lever 120 also gets rotated an equal angle and goes behind channel 102b. Access knob 116 cannot be rotated further as pin's 130 further rotation is blocked by housing and slot 124 thereto. Once the actuation force is relieved, compression spring 118 tries to expand to its initial state thus pulling in lock lever 120 and hence creating a pull which enables door 106 to be held up strongly against the rubber beading 112. In the locked state, lock mounted on door 106 tries to pull locking lever 120 engaged against channel member 102b thus holding up door 106 strongly against rubber beading 112. The mechanism also ensures a high degree to ingress protection to the enclosure.
[0030] Since locking lever 120 has a free movement in a perpendicular direction to face of enclosure, a slight dimensional mismatch is also taken care of between door 106 and channel members 102a, 102b, 102c, 102d of enclosure, without effecting ingress protection.
[0031] To open door 106, access knob 116 needs to be pushed so that pin 122 clears slot 124 and then rotates which then disengages locking lever 120 from channel 102b. Opening of door 106 is characterized by first pushing access knob 116 and then by rotating it. This makes opening difficult for any unauthorized person and also makes it proof against accidental actuation.
[0032] FIG.5 illustrates top view of the entire assembly in a situation of an
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internal arc. In case of internal arc, pressure inside the enclosure increases. This in turn forces volume inside to increase and hence forces all enclosure surfaces to move apart. Due to the pressure door 106 gets pushed out compressing the spring 118 further allowing gases to escape out from the enclosure thus maintaining a certain intended pressure inside.
[0033] FIG.6 illustrates isometric view of the lock assembly with alternatives of the access knob. The present modular design and arrangement allows various alternatives to access knob for specific use by a user.
[0034] In one embodiment, lock assembly 132 has a knob with a slot which is intended to be operated by a tool and hence operation by anyone without a tool is prohibited by design itself.
[0035] In second embodiment, lock assembly 134 has an operating knob which could be gripped by fingers and operated by fingers.
[0036] In third embodiment, lock assembly 134 has a key lock that provides an additional measure of safety with a specific key.
[0037] The foregoing description of the specific embodiments will so fully reveal the general nature of the embodiments herein that others can, by applying current knowledge, readily modify and/or adapt for various applications such specific embodiments without departing from the generic concept, and, therefore, such adaptations and modifications should and are
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intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Therefore, while the embodiments herein have been described in terms of preferred embodiments, those skilled in the art will recognize that the embodiments herein can be practiced with modification within the spirit and scope of the appended claims.
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CLAIMS
What is claimed is:
1. A lock assembly for an enclosure to provide degree of protection to personnel against incidental contact with enclosed electrical equipment and for protection of enclosed electrical equipment against the surrounding environment, wherein locking assembly is mounted on door, with said door is hinged at one end of said enclosure and is swingable about a vertical axis enabling access to the inside enclosure while it is open, said lock mechanism further comprises: a housing barrel that houses entire lock assembly;
an access knob that is used to lock and unlock said door by rotating it 90 degrees clockwise;
a locking lever that gets tapped behind channel upon rotation of said access knob to 90 degrees clockwise;
a compression spring that releases excess pressure during short circuit; a pin that is used to connect said access knob and said locking lever with compression spring wherein said compression spring is sandwiched in between said access knob and said locking lever;
a stopper pin that controls axial movement of locking lever into barrel; a fixing nut;
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2. The system of claim 1, wherein said enclosure consists of four channel member fixed with each other to form a skeleton of said enclosure.
3. The system of claim 1, wherein said door has a rubber beading that acts as a gasket and ensures no gap between said enclosure walls and door once said door is closed.
4. The system of claim 1, wherein reverse rotation of said access knob by 90 degrees anticlockwise, enables lever to unlock said door.
5. The system of claim 1, wherein said stopper pin gets fixed into to slot provided in said housing barrel when said access knob is rotated 90 degrees clockwise.
6. The system of claim 1, wherein entire lock assembly is screwed to back side of said door by said fixing nut.
7. The system of claim 1, wherein a user has to push and then rotate said access knob at a same time to open said door .
8. The system of claim 1, wherein said door is pushed outside upon increase pressure within said enclosure due to overload condition or a relatively high level short circuit, wherein said spring compresses against
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locking lever during the pressure release allowing excess pressure to release outside said enclosure.
Dated this the 28TH day of March, 2007

Rakesh Prabhu,
Patent Agent, ALMT Legal,
No.2, Lavelle Road, Bangalore-560 001, INDIA
To,
The Controller of Patents, The Patent office,
At Mumbai
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Abstract
An enclosure and locking assembly for protection of personnel against incidental contact with enclosed electrical equipment and for protection of enclosed equipment against the surrounding environment. The locking assembly is mounted on the enclosure. The locking assembly consists of a housing barrel intended to house entire assembly, an access knob, a compression spring, a locking lever, a pin, a fixing nut, a stopper pin. Locking mechanism overcomes over-pressurization of enclosed electrical system due to overload condition or a relatively high level short circuit or fault condition. To open locking system a user has to push and then rotate actuator. In case of short circuit condition in distribution system, internal arc increases the pressure within the enclosure. The pressure developed inside the enclosure is released due to constructional arrangement of locking assembly and the door, preventing the pressure inside to shoot up.
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