GB2199623A

GB2199623A - A device for sealing-tight installation of an electrical apparatus in an opening in a switchboard

Info

Publication number: GB2199623A
Application number: GB08729832A
Authority: GB
Inventors: Francois Rabou; Michel Rochard
Original assignee: La Telemecanique Electrique SA
Current assignee: Telemecanique SA
Priority date: 1987-01-09
Filing date: 1987-12-22
Publication date: 1988-07-13
Anticipated expiration: 2007-12-22
Also published as: DE3800374A1; GB2199623B; IT1212013B; JPS63174502A; JPH0510002B2; DE3800374C2; FR2609579A1; GB8729832D0; SG38391G; HK96691A; FR2609579B1; IT8748765A0

Description

A DEVICE FOR SEALING-TIGHT INSTALLATION OF AN ELECTRICAL APPARATUS IN AN

OPENING IN A SWITCHBOARD 2199623 The invention relates to a device by means of which an electric control and/or signalling apparatus can be installed in sealing-tight manner in an aperture formed in a plate of an electric switchboard, the device comprising a tubular bushing means comprising a neck mounted throu gh the aperture in the plate and a collar secured to the neck and forming toward the neck a transverse portion bearing against an outer, surface of the plate with interposition of sealing means and of the periphery of an aperture in a tag, sign-plate or the like adapted to have a pre-set orientation when in operation. The device also comprises means adapted to bear against an inner surface of the plate in order to urge the collar towards the plate and thus axially compress the sealing means.

The electric apparatus which can be installed by means of the device, and which are used on a large scale in all industrial installations, cover all means of dialogue used between an operator and an installation, e.g. push-button or rotary-key switches, visual or other indicators of state, and devices comprising switching and indicating means.

In the previously known devices, various methods have been used for obtaining the required sealing-tightness and holding the tag.

In one method, a tag having an opening substantially equal in diameter to the opening in the switchboard, is directly pressed against the external surface of the switchboard, and the sealing means comprise an e.g. toric elastomeric seal placed between the outer surface of the tag and an annular surface of the collar projecting beyond the openings. When suitable means are clamped, the seal is compressed and simultaneously presses the tag against the switchboard.

This device has a disadvantage in that it cannot be guaranteed that efficient sealing-tightness will exist or be maintained between the outer surface cif the switchboard and the surface of the tag pressed against it. It is also a trial-and error business to give the tag the required annular orientation relative to the switchboard or the collar of the device, when the device has to be oriented relative to the switchboard.

In another construction, the opening in the tag surrounds a seal which is disposed in an annular groove in the collar and is placed between it and the outer surface of the switchboard. When the seal is compressed, it deforms without changing its volume and presses simultaneously against the collar, the neck, the outer surface and the edge of the opening in the tag.

In this method, the volume of the seal and the spaces which it enters must correspond perfectly to the anticipated theoretical volumes, The tag is difficult to centre, and this reduces the reliability of the resulting sealing-tightness.

This method also requires manual adjustment of the tag and there may also be gaps in sealing-tightness when, as frequently occurs, the opening in the plate has an indexing notch provided for any appropriate purpose.

This method also prevents use of the indexing-notch, since it is covered by the seal.

The invention therefore aims to improve a device of the construction indicated in the preamble so as to improve the sealing-tightness and enable the tag to be positively adjusted.

To this end, according to the invention, the sealing means are moulded on the tag so as to present an annular sealing-tight bearing surface on the collar and an annular sealing-tight bearing surface on the outer wall of the plate.

This considerably facilitates assembly, since there is no need to handle the seal separately, which is always awkward. Sealing-tightness is also achieved in a very reliable manner, both between the collar and the tag and between the tag and the plate. Also, there is no fundamental obstacle to using an indexing notch, on the opening in the plate.

Other features and advantages of the invention will be clear from the following description.

1 1 V 1 The accompanying drawings are given by way of non-limitative In the drawines:

examples.

Fig---1 is a diagrammatic view of a device according to the inventi.on, showing the plate in section and the device in axial half-section, the electrical apparatus being represented by chain-dotted lines., Fig. 2 is a partial front view of the plate Fig. 3 is a larger-scale exploded view of the device in Fig.

1; Figs. 4a and 4b are partial views of the tag in perspective, without the seals or with seals cut away, respectively;.

Fig. 5 is a view of the tag, an the side pressed against-the plate during operation; Fig. 6 is an elevation of a second embodiment of the invention; Fig. 7a and 7b are diagrammatic views in axial section of two other embodiments of the invention, and Fig. 8 is a diagrammatic view in partial axial section of a fifth embodiment of the invention.

A device for sealing-tight installation of a control or monitoring or signalling apparatus 1 shown chain-dotted in Fig. 1 comprises inter alia a projecting collar 2 secured to a neck 3 and co-operating therewith to form a tubular bushing component having a shape of revolution around the axis W.

The collar has an outer diameter D, so that an annular shoulder or transverse bearing portion 4 connects it to the neck, which has a diameter d slightly less than the diameter p of a circular opening 5 drilled or cut in a metal plate 6 having a thickness e, measured along axis W, which is less than the axial dimension of neck 3.

In principle, plate 6 has a number of openings 5, each containing a device according to the invention which in turn has a bushing 2, 3 receiving an apparatus such as a control knob or signal lamp, the assembly forming a switchboard.

Each opening 5 frequently has a notch 5a for adjusting the angle of apparatus 1 around axis XX1 (compare Fig. 2).

One end 7 of neck 3 has means 8 which bear against the rear surface ga of plate 6 so as to urge shoulder 4 towards the front surface ga of the switchboard.

Neck 7 can e.g. have an outer thread 10 adapted to receive a clamping nut 11 having a surface lla facing plate 6 and pressing against the rear surface ga of the plate. Alternatively, pressure screws 12a, 12b screwed in a terminal flange 12c in neck 3 can be used to press the collar against the front surface, by bearing against the rear surface (see Fig. 6).

A tag 15 having a small thickness i is disposed between the collar and the front surface 9b of the plate and is formed with an opening 16 having a diameter equal to the diameter of the neck and the opening 5 in the switchboard (see Figs. 1 and 3).

An outer portion 15a of the tag surface bears any sign, text or symbol necessary for identifying a function or apparatus or one or more states of an apparatus, e,g. the various angular positions of a rotary control knob.

The tag needs to be given a preset orientation relative to the switchboard, for aesthetic reasons and in order to read information on the tag. This can be done by notch 5a cooperating with a lug belonging to the neck or collar, thus giving means for orientating the tag relative to the collar. Alternatively, the notch can cooperate directly with a lug belonging to the tag.

In both cases, of course, there will be a certain correspondence between the orientation of the text, symbol or diagram on the tag and the position of the orientation means.

The apparatus illustrated in Figs. 1 - 5 mainly uses the second possibility. A lug 17 on tag 15 in the in diate neighbourhood of the periphery of its opening 16 on the surface remote from collar 2 extends into notch 5a.

1 - 5 1 In order to obtain sealing-tightness between the interior and exterior of plate 6, each side of the tag'bears a seal surrounding the opening 16. One seal 21 has an annular surface for bearing in sealing-tight manner against the outer surface 9b of plate 6, whereas the other seal 22 has an annular surface for bearing in sealing-tight manner against the bearing portion 4 of collar 2 (see Fig. 3).

To prevent the notch from causing a gap in sealingtightness, seal 21 is given a shape 19 (Fig. 5) which is locally enlarged or radially offset towards the exterior near lug 17 so as to surround it, i.e. flank it via its radially exterior side (compare Fig. 4a).

Advantageously, the user or fitter should not have to join a number of thin components (i is approximately I mm). Accordingly, the two seals 21, 22 are moulded in an annular region 20 of the tag immediately adjacent the opening 16.

To enable the moulding to help in efficiently holding the two seals, the annular region 20 of the tag surrounding the opening 16 is crossed by openings such as 25 (see Fig. 4b) through which a single mass of elastoneric material forming both seals forms a number of elementary bonds 23 or bridges between the seals, parallel to the axis, during the moulding operation.

Advantageously, region 20 is made thinner at 20c symmetrically with respect to the central plane of the tag, leaving a thickness j of e.g. 0. 4 to 0.6 mm and forming two opposite recesses or gaps 20a, 20b for the seals.

The total thickness g of the seal (comprising the two elementary seals) 21, 22 is e.g. approximately 1.5-mm, to ensure that the.volume of compressed elastomeric naterial is sufficient. To ensure a seal of continuous thickness, recess 20a has been extended to a depth h in a region 24 surrounding the root 17a of the lug and adapted to receive the offset edge 19 of seal 21.

A device such as a push-button or visual indicator mounted in-the collar opening on the side remote from the switchboard, may not need to have to be orientated, if the orientation is unnoticeable from the exterior owing to the shape of the devices, which is generally a shape of revolution. In any case, some orientation is made instinctively or necessarily by the fitter, since the operative device such as a switch 30, 30a, 30b secured to the neck and disposed towards the interior relative to plate 6, is frequently a solid of prismatic shape disposed at an angle which inevitably follows from the proximity of other apparatus such as la (see Fig. 1).

In the embodiment shown in Fig. 7a, however, the advantages of automatic orientation of the tag are used in order automatically to orientate the collar 2 and consequently the operative part 30. To this end, the surface 31 of tag 32 facing the collar 35 of a device 36 has one or more projecting orientation lugs or hooks such as 33 and 34, Diametrically opposite hooks 33, 34 extend into indexing notches 37, 38 terminating at the periphery and on the transverse portion 39 of the collar. They lightly grip the collar between them so as to secure the tag to the collar before assembly. To reinforce this effect, the surfaces in contact between the hooks and notches are inclined in directions converging in the opposite direction to plate 6, so as to have an elastic snap-engagement or retaining effect.

The hooks are preferably disposed outside seal 22 so as to co-operate with recesses at the periphery of the collar. if necessary, however, they can be disposed inside the seal (Fig. 7b).

In that case, ribs such as 41 and 42 of a tag 40 co-operate with notches 43, 44 formed on the collar in the immediate neighbourhood of neck 45. No gaps in sealing-tightness can occur when the notches do not open at the periphery of the collar and the seal 22a flanks their radially exterior side as shown.

In this embodiment, it is more difficult to mould the collar to obtain inclined surfaces adapted to have the same retaining or 1 1 1 1 7 - i snap-engagement effect as mentioned In connection with the embodiment in Fig. 7a.

Retaining by clamping, however, is possible if the dimensions of the ribs are closely adapted to the notches.

Advantageously, the tags are made of a thermoplastic material during a single moulding operation for forming the opening, the lugs, the ducts and the regions receiving the seals, which latter are then moulded.

In the embodiment shown inter alia in Fig. 1, a projecting region 15a. of the tag is used for holding texts, signs or symbols 13.

Fig. 8 shows an embodiment corresponding in other respects to Fig. 7a but taking advantage of the fact that tag 50 is obtained by moulding, a cage 49 having a height greater than the thickness being formed in an outer region 51 with a recess 52 which is partly accessible from the side 53 facing the plate but on the other side has an opening 54 which is smaller in order to receive and, by snap-engagement action, retain a removable component or plate 55 bearing signs 56 as required on its upper surface 57; clearly the direction of the sign or signs or symbols or texts is orientated relative to the position of lugs such as 17 and/or 33, 41 by suitably orientating the recess 52.

In another embodiment, recess 5a can be occupied by a lug on the neck or collar, whereas the tag does not have an angular positioning means except for one or more lugs extending into recesses of the collar.

Claims

C L A I M S

1. A device by means of which an electric control and/or signalling apparatus (1) can be installed in sealing-tight manner in an aperture (5) formed in a plate (6) of an electric switchboard, the device comprising a tubular bushing means comprising a neck (3) mounted through the aperture (5) in the plate (6) and a collar (2) secured to the neck and forming toward the neck a transverse portion (4) bearing against an outer surface (9b) of the plate (6) with interposition of sealing means (21, 22) and of the periphery of an aperture (16) in a tag or the like (15) adapted to have a pre-set orientation when in operation, the device also comprising means (8) adapted to bear against an inner wall (9a) of the plate (6) in order to urge the collar (2) towards the plate (6) and thus axially compress the sealing means (21, 22), characterised in that the sealing means (21, 22) are moulded an the tag (15) so as to present an annular sealing-tight bearing surface on the collar (2) and an annular sealing-tight bearing surface on the outer wall (9b) of the plate (6).

2. A device according to claim 1, characterised in that the sealing means comprise two annular seals (21, 22) each bearing one of the annular sealing surfaces, the seals being interconnected by bridges (23) occupying orifices (25) in the tag distributed around the aperture (16) therein.

3. A device according to claim 2, characterised in that each seal (21, 22) occupies a recess (20a, 20b) in the tag (15).

4. A device according to claim 2 or 3 for a plate having a circular aperture enlarged by a notch (5a), characterised in that the tag, on its surface facing away from the collar (2), has a lug (17) disposed near the aperture (16) and adapted to enter a notch (5a) in the aperture (5) in the plate (6), and the seal (21) bearing the sealing surface remote from the collar extends round a radially external side of the lug (17).

1 XI -

5. A device according to any of claims 1 to 4, characterised in that the tag (15) and the collar (2) have mutual angular positioning means-(33, 37; 41 to 44, 50).

6. A device according to claim 5, characterised in that the mutual angular positioning means comprise at least one lug (33, 34; 41, 42; 50) extending into a corresponding recess (37, 38, 43, 44).

7. A device according to claim 5, characterised in that the positioning means comprise at least two lugs extending into corresponding recesses and in that the lugs and recesses are shaped and/or positioned so as to retain the tag (31) on the collar (36) during assembly.

8.- A device according to claim 6, in which the sealing means comprise two annular seals (21, 22) each bearing one of the sealing surfaces, characterised in that the lug of the mutual angular positioning means is borne by the tag near the edge of the opening therein, and the seal adjacent the collar extends round a radially external side of the lug.

9. A device in accordance with Claim 1, substantially as hereinbefore described with reference to, and as shown in, Figures 1 to 5 of the accompanying drawings.

10. A device in accordance with Claim 1, substantially as hereinbefore described with reference to, and as shown in, Figure 6 of the accompanying drawings.

11. A device in accordance with Claim 1, substantially as hereinbefore described with reference to, and as shown in, Figure 7a of the accompanying drawings.

12. A device in accordance with Claim 1, substantially as hereinbefore described with reference to, and as shown in, Figure 7b of the accompanying drawings.

13. A device in accordance with Claim 1, substantially as hereinbefore described with reference to, and as shown in, Figure 8 of the accompanying drawings.

14. Any novel feature or combination of features described herein.

Published 19SP- at The Patent Office, State House, 6671 High Holborn, London WClR 4TP. Further copies may be obtained from The Patent Office, Sales Branch, St M&U Cray, Orpington, Kent BRS 3RD. Printed by Multiplex techniques ltd. St Mary Cray, Kent. Con. 1/87.