WO2004101364A2

WO2004101364A2 - Enclosures with positive internal locking arrangement

Info

Publication number: WO2004101364A2
Application number: PCT/IN2003/000332
Authority: WO
Inventors: Ramesh Roahan
Original assignee: Ramesh Roahan
Priority date: 2003-05-14
Filing date: 2003-10-13
Publication date: 2004-11-25
Also published as: AU2003272085A8; AU2003272085A1; WO2004101364A3

Abstract

This invention relates to enclosures, externally hinged and with positive internal locking mechanism/arrangement to ensure uniform sealing all around, between body and cover to provide high degree of ingress protection.

Description

ENCLOSURES WITH POSITIVE INTERNAL LOCKING

ARRANGEMENT

FIELD OF THE INVENTION:

BACKGROUND OF THE INVENTION:

Enclosures are used extensively to protect vital equipments, junctions, etc. from the environment. In the prior art, enclosures were made mostly from metals and comprise of a body having a plurality of at least four vertical walls with a bottom and joined together having an open top with a projection or tongue all around. The cover is provided with a groove all around to receive a sealing gasket at the matching centerline of the projection of body. When the body and cover are pressed and held together rigidly, the required level of ingress protection is achieved due to the effective sealing between body and cover at the matching centerline.

The cover is held rigidly on the body by means of screws provided on the cover, which bolt on to the nuts provided on the body, outboard of the sealing area. However, special care is to be taken to tighten screws with equal pressure sequentially to ensure good sealing.

Enclosure cover and body are also held together rigidly with hinges provided either outside or inside of the sealing area on one end and at the other end by means of internal or external locking arrangement/mechanism.

Hinges provided on the outer side of sealing area are preferred as the cover/door can open to required minimum 90 degree and more

Internal locking arrangement is the preferred means of locking as the locking arrangement is protected from the environment.

Enclosures are provided with standard locking arrangement and comprise of a lock usually a V* to ! turn, mounted on the cover to operate a central latch behind, to lock on to the body for smaller enclosures.

For larger enclosures, the locking arrangement also has a pinion attached between the central latch, driving up and down two sliding bars with gripping rollers at extreme ends that enable to effect a three point locking arrangement between body and cover, when the lock is engaged.

Enclosures are also available with such multi-point locking at three sides other than the hinge end, and are expensive, to permit wider usage. With availability of engineering plastics or composites in the last twenty years, composite enclosures are being used extensively to overcome problems encountered with metals like corrosion, manufacturing complexities, higher cost, etc.

In composite enclosures due to material composition and processing method, added with asymmetric shape with differential thickness resulting from design optimization and parts consolidation, create internal stress and cause particularly the shallow cover and to a certain extent the deeper body to warp. Warpage cause the body and cover to bend outwards. Unequal warpage cause twist, resulting in unequal bending outwards at extreme corners.

This warpage and twist is advantageously used for smaller enclosures when the cover is screwed down at the four corners on to the body. The outwardly warped and twisted cover and body straighten out and seal effectively by compressing the gasket in between uniformly.

Composite enclosures provided with hinges at one end and with only the central locking internal arrangement at the other end, do not seal at the corners due to the warp and twist, even for small enclosures. Only the hinge end seals well, as the warp and twist is straightened out by the rigidly fixed hinges.

For large enclosures, the distance between the central-latch to the top or bottom locking position is quite large, any warp and twist in the cover more than the desired limits may not engage the locking points at either extreme ends at top and/or bottom, though the central-latch may engage fully.

The other major problem encountered with enclosures from small to large is the mismatch between the centerline of sealing between body and cover caused by the collapse or bow inwards of the deeper and unsupported body walls having the projection/tongue, which results in poor sealing and reduced levels of ingress protection.

To reduce the bow to within acceptable limits, several post manufacturing operations are carried out especially in the case of composites, like over- jigging. This over-jigging may some times result in an outward bow, again causing mismatch at centerline of sealing.

The problem of warpage or twist, and bow in enclosures are quite common in composite enclosures and also prelevant in metal enclosures and add to cost of manufacture, affect quality of sealing by not being able to achieve desired level of ingress protection consistently.

OBJECT OF THE INVENTION:

The object of this invention is to provide an enclosure with external hinges at one end and a positive internal locking/latching arrangement at the other end, to compress the provided sealing gasket uniformly and positively between the body and cover all around by straightening out the warpage or twist between body and cover and to effect a sealing to desired levels of ingress protection and to do it consistently, in a cost effective manner.

The further objective of the invention is to provide such positive internal locking arrangement with multi-point locking/latching, if required to seal large enclosures at one end or on all three ends to achieve positive locking sequentially from center to the last point of latching at all the three ends, ensuring that the warp and twist on cover or door is pulled down in stages by such sequential locking/latching to achieve positive sealing all around.

It is the further objective of the invention to provide aligners between body and cover positioned suitably, to ensure that the center line of sealing between body and cover is maintained very accurately at all three ends, irrespective of bow on body walls, to ensure positive sealing.

DESCRIPTION OF THE INVENTION:

The enclosure according to the invention comprise of a body, cover or door wherein the cover or door has flat outside surface. In the further description the expressions cover and door are synonymous.

A sealing gasket is provided all around the inner periphery of the cover to receive the projection/tongue of body, to effect the desired airtight sealing when body and cover are held together rigidly. The enclosure according to the invention can be small to large enclosures with provision for hooks for lifting and with a base/pedestal for floor mounting, and of differing shapes of body and cover.

One end of the enclosure normally the larger end, is provided with hinges at sufficient positions between body and cover, outwards of the gasket area to enable the cover to open required minimum 90 degree or more. The rigidly mounted hinges help to maintain the centerline of sealing between body and cover at that end.

The other end opposite to the hinged end of the enclosure is provided with a standard lock on the cover. This lock operates an internal locking mechanism having a pinion moving sliding bars with racks up and down in both directions and with or without a central latch, provided on the inner side of the cover.

The lock may be key operated or with a handle and key for small to large enclosures, requiring higher locking force.

The lock with internal locking mechanism may be standard or specially made to suit different enclosure types.

The sliding bars are provided with rigidly mounted racks and are suitably positioned to operate rigidly pivoted latch with integral pinions, mounted on the inside of cover, to lock on to the body rigidly such that the seal provided on the cover is compressed uniformly by the projection/tongue of the body, effecting positive sealing all around.

The latch with integral pinions are rigidly mounted on to the cover at suitable positions on integral boss provided with integral nut, through spacer bush, washer and screw to enable the latch with integral pinion to freely rotate on its rigidly pivoted axis.

Means are provided on the integral boss, spacer bush and washer to ensure that the screw does not loosen during locking and opening, rotational movements of latch with integral pinion on its axis, over the pinion bush, boss and washer, when the internal locking mechanism is operated.

The locking takes place when the lock is operated, activating the sliding bars to move up words or outwards. These moving sliding bars with rigidly mounted racks, engage with the matching pinion on the latch with integral pinion and turns the latch with integral pinion to rotate on its rigidly mounted axis and clamp on to the body rigidly.

The lead angles provided on the latch with integral pinion pull down the warp and twist to desired levels, until final locking occurs at full engagement.

Similarly for lock opening, the sliding bars moving downwords or inwards carrying the racks engage with pinion of the latch with integral pinion and allows it to rotate on its axis back to the open position. Guides are provided to keep the sliding bars in position and to keep the rack and latch with integral pinion positively engaged during locking and opening sequence. These latch with integral pinion also help to hold in position, the rack carrying the sliding bars under locking and opening conditions, acting as a sliding and rigid retainer.

For small enclosures, usually two such latch with integral pinions provided at two extreme ends opposite to the hinged end is sufficient to seal the body and cover firmly while removing the warp and twist on the body and cover and effecting sealing to a high level of ingress protection as that achieved when screwed down from outside without requiring a central latch.

For medium to larger enclosures, to ensure that the warp and twist on cover is pulled down in stages for positive locking at the extreme ends, a central latch is provided on to the standard internal locking mechanism/arrangement, which has a larger locking width, and in addition, several such latch with integral pinions are positioned on both directions with progressively smaller widths and suitable lead angles, than the central latch.

As the lock is engaged, both the sliding bars move in opposite directions and simultaneously first the central latch engages on to the body and then the next set of latch with integral pinion in each direction engage on the body, then the second set, and so on, until the final set of latch with integral pinion engage. This sequential continuous latching/gripping allows the final span from center to ends of cover to be reduced progressively, such that by the time the last set of latch with integral pinion starts engaging, the cover warp is pulled down sufficiently to below desired levels, ensuring positive sealing between body and cover, at corners and all around.

The enclosures according to the invention may be used for large enclosures/control cabinets, wherein the positive internal locking arrangement comprise of a standard lock with handle provided on the cover. The inside of the cover is provided with a standard internal locking arrangement with standard sliding bars moving in opposite directions provided with several latch with integral pinions as described above, and optionally having standard gripping rollers at the extreme corners

The latching of cover may be directly on to body or on to specific clamping positions provided on body. The spacing between the latch with integral pinions can be reduced or increased depending on desired level of ingress protection.

When the door is closed and lock operated, the central latch first engages, and the moving sliding-bars with racks activate the first set of latch with integral pinion to lock on both direction and then the second set, and so on, until the gripping-rollers pulls the cover down rigidly to lock at both corners, opposite the hinged end. This sequential locking helps reduce the span from the center to the ends in steps, thereby reducing warpage and or twist on the door insteps to below desired levels to achieve positive locking at door corners.

By providing larger locking widths for the standard central latch and progressively smaller locking widths for pinion with integral-latches, and sufficient lead angles for all latches, smooth sequential locking is achieved.

For higher level of ingress protection and for large enclosures with large width, three side sequential locking is provided by using a 90 degree pivoted- bar-pusher at the top and bottom corners, which are rigidly pivoted on to mounting points/boss with integral nut provided at suitable positions near the inner corners of the cover at the internal locking mechanism end.

These pivoted bar pushers convert the up and down movement of the sliding- bars into a sideway movement of similar sliding-bars provided at the top and bottom width ends. The top and bottom bars also actuate similar rack and latch with integral pinion positioned at required intervals to effect positive sealing sequentially at the top and bottom ends.

For such enclosures with larger widths and with hinges provided for eg. at the left end and with the positive internal locking arrangement, ensure that the right, top and bottom corners of cover or door are sequentially locked . This sequential locking starting from the center to the top right corner and simultaneously from the left top corner to the right top corner and with similar simultaneous action taking place at the bottom right corner, ensure positive sealing all around, for large enclosures with multi-point locking on all three sides.

Sequential locking can also be achieved by having not only with latches with progressively lower widths from central latch but also by having latches of same width but allowed to engage one after another in sequence by matching the engagement of the rack and pinion of latch with integral pinion at suitable positions to effect such sequential locking.

To avoid mismatch, due to bow on body walls at centerline of sealing between projection/tongue of body and the sealing gasket on cover, an aligner arrangement is provided.

The aligner arrangement comprise of a tapered round dowel pin and a floating bush mounted rigidly on the cover and body respectively, suitably positioned to match the centerline of sealing, between body and cover.

When the cover is closed, the well-positioned aligner arrangement permits the dowel pin to enter the bush and align the centerline between the tongue on body and the sealing gasket on cover, well before the gasket is compressed to achieve positive sealing during the locking/latching operation. The other inherent advantages of the aligner arrangement is to lift into position the sagging end of door in alignment, if the doors are heavy and wide, and also holds the center line of gaskets in position during the swipe action of latching, which may sometimes shear and damage the gasket when being compressed, if tongue of body moves away during latching.

By providing required lead angles, and having a smooth hardened dowel and with a smooth rounded point contact on bush, helps in reducing the force required to close and open the door, while correcting mismatch to desired limits, even if bow on body is outwards.

The bush is allowed to float sufficiently but rigidly positioned such that it matches the cover/door closing swinging arc type movement.

If the bow is always inward, the aligner arrangement instead of comprising of a dowel pin and dowel bush can comprise of a rectangular tapered wedge/dowel pin and a rectangular slider with lead taper and are rigidly mounted to the cover and body respectively to correct the mismatch of centerline well before the sealing of gasket takes place.

This type of aligner is most suitable for the top and bottom ends requiring a sliding motion, during closing.

Enclosures having a larger width, can be provided with aligners at the central position on the top end and bottom end in addition to the central aligner provided near central latching area to ensure that the center line of sealing between body and cover at the three ends is perfectly matched ensuring desired high level of ingress protection, while the hinges provides desired sealing at the hinged end.

The preferred location of aligner arrangement is as close as possible to the central latch position, without interference to the lock-mechanism, and at the central area at the top and bottom ends.

A single aligner provided on each side is usually sufficient to correct this mismatch of gasket center line, more can be provided, if necessary at suitable positions and can be made to come into engagement one after another sequentially.

The enclosures according to the invention can have either an integral cover and body or can have cover and body made from several parts and joined together as described in International Patent publication no. WO 03/001637.

The cover and body are provided at specific intervals, mounting points like integral nuts or bolts, welded screws, etc. for rigidly mounting the latch with integral pinion, guides, dowel pins, pivot-bar-pushers, tapered wedges, sliders, etc.

The materials used for cover, body and all other parts can be either metals, engineering polymers, or composite plastics or any combinations of these. The preferred gasket to seal the body and cover is a seamless polyurethane elastomer, or any suitable synthetic elastomer to effect good sealing requiring minimum force for compressing the seals.

The invention will be described in detail with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS:

Fig. 1 is a perspective view of an enclosure according to the invention.

Fig. 2 is an inside plan view of an embodiment of the cover of the enclosure shown in figure 1.

Fig. 3 is an inside plan view of another embodiment of the cover of an enclosure according to the invention.

Fig. 4 is a partial plan view of the cover shown in figure 3, under lock open position.

Fig. 5 is a partial plan view of the cover shown in figure 3, under locking position.

Fig. 6 is a sectional view along ' AA' shown in Fig. 1 at hinge position. Fig. 7 is a sectional view along 'DD' shown in Fig.1 at top locking position.

Fig. 8 is an alternate sectional view along ΕE' shown in Fig. 1 with mismatch of central line of sealing with bow on body walls.

Fig. 9 is a sectional view along ΕE' shown in Fig. 1 at an aligner arrangement position of the desired embodiment.

Fig. 10 is an alternate sectional view of an aligner arrangement at the top and bottom side.

Fig. 11 is a perspective view of the rack to drive the latch with integral pinion

Fig. 12 is a perspective view of a latch with integral pinion at the extreme ends

Fig. 13 is a perspective view of a latch with integral pinion at an intermediate position

Fig. 14 is a perspective view of a central latch at central locking area

DETAILED DESCRIPTION WITH REFERENCE TO THE DRAWINGS: The preferred enclosure 1, according to the invention has a cover 2 and body 3 and is provided with a standard lock 4 mounted on cover 2₅ as shown in fig 1.

For larger enclosure of the preferred embodiment, pedestals 5 and lifting hooks 6 may be provided.

Fig. 2 shows the inside plan view of an embodiment of the cover of a medium sized enclosure comprising of a standard internal locking arrangement/ mechanism 7 with sliding bars 8 and 9 to move up and down in opposite directions and a central latch 10 with wider width, mounted directly on to the internal locking mechanism 7, and operated from outside with lock 4.

The sliding bars 8 and 9 are rigidly mounted with racks 13, which operate latch with integral pinions 11 and 12. The latch with integral pinion 11 and 12 have differing widths and lead angles to effect sequential latching. 14 are guides for keeping the sliding bars in position. 18 are guides for keeping the racks and latch with integral pinions engaged during opening and closing operation. 15 is a part of the aligner arrangement provided on cover 2. 16 are hinges provided on one end. 17 is the sealing gasket provided all around on cover between grooves to match the center line of the projection/tongue on body 3. For smaller enclosures, the internal locking arrangement 7 may comprise of only latch with integral pinion 12 at two extreme ends and without requiring the central latch 10. The tapered ends/lead angles of the latch with integral pinion 12 helps in pulling down the warped cover at the corners to effect a good sealing at the two corners, as good as that achieved when the body and cover are screwed from outside.

Fig. 7 is a sectional view along 'DD' of Fig.l at a top locking position wherein the tongue on body 3 is pressed against the gasket 17 provided on cover 2, by latch with integral pinion 12. The rack 13 is mounted on the sliding bar 9. The rack guide 18 keeps the rack engaged with the latch with integral pinion 12.

Latch with integral pinion 12 is allowed to pivot on its axis on pinion bush 29, by rigidly mounting the pinion bush 29 on to the integral nut 24 on boss 25 with washer 28 and screws 27.

Boss 25, Pinion bush 29 and washer 28 are provided with means on each other to prevent loosening of screw 27 during operation of latch with integral pinions 11 and 12.

The means to prevent loosening of screw 27, can comprise of a location on boss 25, and a matching relief on pinion bush 29, and with another location on the other end of pinion bush 29, matching a relief on washer 28, such that when screw 27, is tightened rigidly onto integral nut 24, thru' the washer 28, pinion bush 29 on boss 25, acts like an integral unit, and cannot unloosen by the rotational movement of the latch with integral pinion 11 and 12, provided in between during lock actuation.

The latch with integral pinions 11 and 12 also retain the sliding bars provided with rack 13 in position during locking and opening.

The movement of sliding bars up and down enables the rack 13 to actuate the rigidly pivoted respective latch with integral pinion to rotate clock-wise or counter clock-wise on its axis around the pivoting bush 29 to rigidly lock the cover 2 on to the body 3, or to open, as required.

Fig. 6 is a sectional view at 'AA' at the hinge end showing the tongue and groove sealing of gasket at the hinged end, wherein hinge 16 is rigidly mounted on the body and cover with screws and gasket 26. Several such hinges are mounted externally to rigidly hold the cover 2 against the body 3 at the hinged end. Gasket 17 is provided at the body tightening points of hinge 16 to ensure sealing at these positions.

Fig. 3 is an inside plan view of another embodiment of the cover of an enclosure in locked position, according to the invention having multi-point latching with gripping rollers 22 provided at two extreme ends and pivoted- bar-pusher 21, which is rigidly pivoted on to mounting points/integral boss with integral nuts, provided near the inner corners of cover 2 and converts the forward or backward movement of the sliding-bars 8 and 9 into a sideway movement of similar sliding-bars 19 and 20 provided at the top and bottom ends.

23 is the guide and positioner for the gripping rollers 22.

The internal locking mechanism 7 is shown, wherein the central latch 10 operates with the lock 4 from outside to operate the sliding bars 8 and 9 in opposite directions. Sliding bars 8, 9, 19 and 20 are provided with rack 13 at appropriate positions to operate latch with integral pinion 11 and 12 at all three ends.

The ends of the sliding bars 8 and 9 are provided with standard gripping rollers 22 at both ends. A gripping roller guide and positioner 23 is provided near top and bottom gripping rollers 22.

The central latch 10, the pinion with integral latches 11 and 12 have progressively lower widths. This differential widths permit engagement of latching/locking in steps.

Fig. 4 is a partial plan view of the cover 2 shown in fig. 3 at the top right corner, under lock open position showing the latches 10, 11 and 12 in open positions on one corner end. As the sliding bars 8 and 9 move, first the central latch 10 engage and continues to engage, then the latch with integral pinion 11 at all three ends engage and continue to engage and then the latch with integral pinion 12 at all ends engage and finally the gripping rollers 23 engage sequentially pulling down the warp and twist to within desired levels ensuring positive locking at all ends.

Fig. 5 is a partial plan view of the cover shown in figure 3 at the top right corner, under locking position, showing all the latches in fully engaged positions.

Depending on the length of the enclosure, several latch with integral pinions can be provided in between central latch 10 to the extreme latch 11 in each direction at required intervals, to effect sealing to desired levels of ingress protection.

Depending on the width of the enclosure, several latch with integral pinions can be provided in between latch 11 and 12 at the top and bottom ends.

The enclosure shown in fig.2 and fig. 3 can be provided with sequential locking by not only having latches with integral pinion having progressively smaller widths but also by having latches of same width like latch with integral pinion 12 at all positions and having them engaged one after another in required sequence to achieve sequential locking such that warp and twist on body and cover is pulled down in stages to achieve effective sealing to desired level of ingress protection. Fig. 11 is a perspective view of the rack to drive the latch with integral pinion wherein the rack 13 is provided with projections to clamp on to the sliding bars 8, 9, 19 and 20.

Fig. 12 is a perspective view of a latch with integral pinion 12 at the extreme ends

Fig. 13 is a perspective view of a latch with integral pinion 11 at an intermediate position

Fig. 14 is a perspective view of a central latch 10 with larger width and with square opening to directly mount on to the internal locking mechanism 7.

Fig. 8 is an alternate sectional view along 'EE' shown in Fig. 1 with mismatch on central line of sealing due to the bow on body walls, of an enclosure without provision for aligners.

Fig. 9 is a sectional view along 'EE' shown in Fig. 1 at an aligner arrangement position of the desired embodiment wherein 30 is a dowel pin with a tapered entry, which is rigidly mounted to the integral nut 24 on boss 25 on cover 2. Dowel bush 31 with a lead taper is mounted on to bush holding clamp 33, which is screwed on to body with screw 27, washer 28 and gasket 26. 'O' ring 32 allows the dowel bush 31 to float on its axis, permitting the dowel pin to complete the radial arc type movement of closing. 34 is a circular clip to keep the dowel bush 31 in position.

When the cover is closed on to the body, the dowel pin 30 with long sufficient lead taper, moves into dowel bush 31 with sufficient lead taper and with minimum contact point to minimize the force required to close and open the door.

When the cover 2 is pushed to the body for locking, the dowel pin 30 engage first on to the dowel bush 31 thereby aligning the center line of the tongue on body 3 with the center line of the gasket 17 on cover, by pulling the bow in or out of the walls of the body 3 to the center line with relatively very little applied force to straighten the bow.

The dowel pin 30 length is kept sufficiently long to ensure that the center line of the tongue on body and center line of the gasket 17 on the cover are aligned well before sealing of the gasket 17 takes place due to the locking action of the latches.

In addition, the aligner arrangement 15 helps in arresting the shearing force due to the swipe action of the latch, creating a lateral force, which may loosen the gasket from the groove. By having dowel pin 30 of larger diameters and longer lengths and matching dowel bush 31, even the sagging doors of larger enclosures can be aligned at the bottom and top ends in addition to maintaining the center lines, during sealing.

Fig. 10 is an alternative sectional view at an aligner position at the top or bottom side central area, comprising of a rectangular tapered wedge or a dowel pin 30, rigidly mounted on integral nut 24 or boss 25 on cover 2, and matching with a rectangular sliding bar with lead tapered 35 rigidly mounted to body 3 with screws 27, washer 28 and gasket 26. The dowel pin 30 can also be a rectangular tapered wedge.

Usually a single aligner arrangement 15 on any one side is sufficient. For larger enclosures with larger lengths and widths, one or more aligner arrangement 15 may be provided on each of the three sides as required and such aligners can have aligner dowel pin 30 of different engagement lengths, and positions to effect sequential engagement.

The innovative feature of this invention is to provide positive internal locking arrangement 7 to compress the seal uniformly between the body and cover for the enclosures, by straightening out the warpage or twist between body and cover, by providing positive internal locking/latching at extreme cover corners opposite to the hinged end and to effect a sealing as good as that achieved, when screwed down from outside, and to do it cost effectively. Another innovative feature of this invention is to use sequential positive internal locking/latching starting from center to the ends, wherein warp or twist is pulled down in steps such that when the last latching point is engaged, the warp or twist in cover is reduced to desired level to ensure positive locking all around for large enclosures.

Yet another innovative feature of this invention is to use sequential positive internal locking, at all three sides for enclosure, with large length and width, by using the standard locking mechanism operating the latch with integral pinions at required intervals, to effect desired sealing.

Yet another feature of this invention is to ensure positive internal locking by providing aligners to correct mismatch occurring at the centerline of sealing at the three ends due to the bow of body walls.

While specific embodiments of the invention have been described in detail, it will be appreciated by those skilled in the art that various modifications and alternatives to those details could be developed in the light of the overall teachings of the disclosure.

Claims

CLAIMS:

1. An enclosure comprising of a body (3) with at least one openable side (2) which is a cover or door provided with lock (4), the inside face of said openable side (2) being provided with a positive internal locking mechanism (7) consisting of at least a pair of sliding bars (8) and (9) each of them capable of moving up and down in opposite directions, and each said sliding bar being provided with at least one rack (13) rigidly mounted at suitable position and said rack (13) operating a rigidly mounted pivoted latch with integral pinion (11, 12) on inner side of cover (2), a plurality of hinges (16) provided along the length of the openable side (2) with the body (3), opposite to the internal locking mechanism (7) and a sealing gasket (17) seated all around the edges of the openable side (2) and receiving the edges of the body (3) to provide an air tight sealing between the openable side (2) and the body (3), when the said cover (2) is closed against said body (3) and lock (4) is actuated.

2. The enclosure as claimed in claim 1, wherein the said rigidly pivoted latches with integral pinion (11, 12) are provided with means to prevent loosening during operation of said internal locking mechanism (7)

3. The enclosure as claimed in claim 1, wherein the internal locking mechanism (7) is provided with a central latch (10).

4. The enclosure as claimed in any of the above claims, wherein the said enclosure is provided with sliding bars (19) and (20) at the top and bottom ends, and said sliding bars (19) and (20) at the top and bottom ends are actuated with a pair of pivoted bar pushers (21) provided at the inner corners of cover (2) for transmitting the up and down, sliding action of the sliding bars (8) and (9) to the edge near to the internal locking mechanism (7) to the edges perpendicular to the internal locking mechanism (7).

5. The enclosure as claimed in claim 4, wherein the said sliding bars (8) (9) (19) and (20) are provided with guides (14) and said racks (13) are provided with guides (18)

6. The enclosure as claimed in any of the above claims, being provided with at least one aligner (15) on at least one side of the enclosure.

7. The enclosure as claimed in claim 6, wherein said aligner (15) comprise of a dowel pin (30) rigidly fixed to an integral boss (25) on the cover (2) and passing through a dowel bush (31) held by a bush holding clamp (33) attached to the body (3).

8. The enclosure as claimed in claim 6, wherein the aligner (15) comprises of a rectangular tapered wedge/dowel pin (30) rigidly fixed to cover (2) and sliding on a rectangular tapered wedge (35) rigidly fixed on to body (3).

. The enclosure as claimed in claim 7 and 8, wherein aligners (15) are provided on top, bottom and central latching side of cover (2) and body (3).

10. The enclosure as claimed in claim 6, wherein said aligner (15) comprise of a dowel bush (31), which is capable to float on its axis.

1 l.The enclosure as claimed in claim 2, wherein the said central latch (10) and latch with integral pinion (11) have the same widths and lead angles and are positioned to operate one after another sequentially to effect airtight sealing between body (3) and cover (2).

12.The enclosure as claimed in claim 2, wherein the central latch (10) is provided with largest locking width and subsequent latches with integral pinions (11, 12) are provided with progressively smaller locking widths so that when the door is closed and lock is operated, the central latch (10) engages first and the remaining latches engages progressively to provide sequential locking.

13. The enclosure as claimed in claim 4, wherein the sliding bars (19) and (20) at the top and bottom ends are provided with latch with integral pinion (11,12) having progressively lower widths to effect sequential locking at the top and bottom ends also.

14. The enclosure as claimed in claim 1, wherein the three sides of the openable side (2) are provided with sliding bars (8, % 19, 20) and two pivoted bar pushers (21) for operating the sliding bars (19) and (20) at top and bottom sides of the openable side (2) to move back and forth while the lock is operated.

15. The enclosure as claimed in claim 11, wherein sliding bars (19) and (20) at top and bottom of the openable side (2) are provided with latches with integral pinions (11) and (12) for sequential engagement during locking.