GB2342780A

GB2342780A - Switch

Info

Publication number: GB2342780A
Application number: GB9924069A
Authority: GB
Inventors: Reinhold Barlian; Karl-Heinz Lux; Lothar Hezger
Original assignee: Bartec Componenten und Systeme GmbH
Current assignee: Bartec Componenten und Systeme GmbH
Priority date: 1998-10-13
Filing date: 1999-10-12
Publication date: 2000-04-19
Anticipated expiration: 2019-10-12
Also published as: GB2342780B; DE19846996A1; GB2342780A8; FR2784499B1; DE19846996C2; GB9924069D0; FR2784499A1

Abstract

A switch for an explosion-protected light with a visual position display comprises a housing 2, a spring biased actuator 7, plunger 13, contacts 22, 23 and terminals 27. Pressing the actuator 7 against spring 24 moves the contacts 22, 23 carried by plunger 13 into abutment with terminals 27 and closes the circuit. At the same time windows 33 in actuator 7 reveal different coloured areas 36, 37 on housing 2 which indicate the operating state of the switch.

Description

SWITCH The invention relates to a switch with the features of the preamble of claim 1.

Lights installed in an explosion-threatened environment, in particular lon-field lights, contain one or several switches or switching contacts, which, in the case of a change of ittuminant for examp'e, switch off the electric circuits in question when the light cover or transparent hood is opened. Thus, the activator of the switch is moved from the operating position to the idle position, whereby the switching contacts are disconnected. For this reason one or several switches or switching contacts are located in every light so that, in the event of the failure of one switch, for example if the switching contacts are welded together or the activator jams, the other switch guarantees the disconnection of the electric circuit. If, of course, both switches fail, there is a high risk of explosion since the mechanic does not notice the failure of the switches.

The task of the invention is to provide a switch with the features of the preamble of claim 1.

This task is solved by the characteristic features of claim 1 of the invention.

Appropriate versions and further developments of the invention are shown by the characteristics of the subclaims.

Further advantages and main details of the invention are provided in the foi'ow'ng description and drawing, which is a schematic representation of the preferred versions as exampies. To this end, F ! GURE 1 shows the switch of the invention in the idle position in side view, FIGURE 2 shows the switch of Figure 1 in the operating position, FIGURE 3 shows the switch of Figure 1 in a partially opened-up side view, FIGURE 4 is an"exploded"view of the switch of Figure 1, FIGURE 5 is another switch of the invention in the idle position and in a side view and FIGURE 6 shows the switch of Figure 5 in the operating position.

The switch of the invention shown in Figures 1 to 4 exhibits a housing with two top-rounded wall parts 3,4. The housing 2, which is preferably made of plastic, has a lettering field 5 and fastening holes 6.

Between the wall parts 3,4 a sliding activation hood 7 with an approximate U-shape is supported. This has two parallel side-pieces 8,9 and an arch 10 connecting them. Lying opposite each other two guide crosspieces 11 can be constructed on each of the side-pieces 8,9 and these are supported, largely without any play, in corresponding guide grooves 12 of the wall parts 3,4 so that easy-motion, exact and non closure displacement of the activation hood 7 is guaranteed.

The activation hood 7 is fastened to a plunger 13, which is supported, with axial displacement, in a guide box 14. The fastening can take the form of a supporting joint 15, whereby at least one supporting crosspiece 16 engages a groove 17. In this present example version two crosspieces 16 are formed at the activation hood 7, which engage, in a form-closure manner, in two grooves fying on top of each other, which are formed at the other end of the plunger 13.

At the lower end of the plunger 13 laying opposite the supporting joint 15 an approximately cube-shaped cage 18 can be located, which, in the example version here, exhibits two chambers 20,21 separated by a partition 19. At the lower end of the cage 18 there is a pin, on which a spring 24 is provided. The plunger 13 and the cage 18 with the partition 19 and the pin for the spring 24 can be made of a one-piece part of one and the same plastic. In the two chambers 20,21 electrical contact bridges 22, 23 can be positioned, to each of which a helical spring element is assigned.

In another version of the invention it is also possible not to provide the partition 19 at the cage 18 but to build it within a closure part 25.

The closure part 25 is in the lower part of the housing 2 and preferably consists of plastic. The closure part 25 may exhibit a supporting nose 26,whichengagesasupportingrecessformedinthewat!ofthe housing 2 so that the closure part 25 is held in the housing 2 The floor of the closure part 25 may exhibit, for example, four slot-shaped openings, in which the contact lugs 27 of electrical contacts 28 are supported. The contacts 28 with the contact lugs 27 are held by means of supporting projections 29, which may be formed on the walls of the closure part 25.

To the lower ends of the contact lugs 27 extending out of the closure part 25 electrical cables 30 can be connected, e. g. by soldering, welding or moulding. The housing 2 of the switch 1 is, following the assembly of the parts described above, hermetically cast to the underside of the closure part 25 with a casting resin, whereby the connections of the cables 30 at the contact lugs 27 are embedded in the casting resin and the cage 18 of the plunger 13 with the contact bridges 22,23 and the spring elements are located in a switch room 31, which corresponds with explosion regulations.

The switch 1 exhibits, moreover, a visual position display 32, which, in this example version, has windows 33 for example, one each of which is in the sides 8,9 of the activation hood 7. The windows 33 can, for example, be circumscribed downwards and upwards by inclined planes 34, 35 so that an extension of the window aperture outwards is provided for good viewing. Furthermore, the positional display 32 has display areas, which are provided at the narrow sides of the housing 2, against which the inner surfaces of the sides 8,9 of the ciamping hood 7 rest and which show the operating position 36 and the idle position 37 with different colours. Preferably the display surface for the operating position 36 is red and the display surface for the idle position 37 is green. In the operating position 36 the contact bridges 22,23 lie against the contacts 28 of the contact lugs 27 so that the electric circuit is closed. In the idle position 37 the contact bridges 22,23 are some distance above the contacts 28 so the electric current is interrupted. (FIG 3) In the case of a light installed in an environment threatened by explosion, the activation hood 7 is, with a closed light cover, in the operating position 36 shown in Figure 2, in which the red display surface can clearly be seen in the window 33. If now the light cover is to be opened for example, to change the illuminant, the spring 24 pushes the plunger 13 and the activation hood 7 upwards. If the switching contacts in the switch 1 do not separate, for example because they have been welded together, the activation hood 7 remains in this operating position 36 and the mechanic sees from the red display field that he must not open the light cover any further but must keep it closed because there is a fault.

Normally the switch 1 is in order and, when the light cover is opened further, the activation hood 7 moves into the idle position 37, as is shown in Figures and 3. The mechanic sees from the green display field that the switching contacts are open and that he can now change the illuminant without any danger, without having to switch off the entire light electric circuit that generally feeds several lights.

In the example version shown in Figures 5 and 6, the positional display 38 is formed directly at the plunger 39 without the aid of an activation hood inasmuch as the plunger end section 41 extending out of the housing 40 shows the idle position 42, the display surface of which is preferably green (Figure 5). This means that the mechanic can see immediately that the electric current in the switch 43, which largely has the same design as the example version shown above, has been interrupted.

When the mechanic closes the light hood of the light installed in an explosive environment, the plunger section 41 present and protected between the two wall parts 44,45 of the housing 40, is forced into the housing 40 (Figure 6) so that it is now in the operating position 46, in which the green display surface is no longer visible and the switching contacts come together, whereby the electric circuit is closed.

Furthermore, it is also within the framework of the invention to realise the visual positional display of the switching position in question (operating position or idle position) by ensuring that at least one wall of the switch housing is transparent in the area of the switching room so that the mechanic can easiiy see into the switching room. ! n this way he can immediately and directly see whether the switching contacts are in contact with one another so that the operating position is provided with a closed electric current or whether the switching circuits are at a distance from one another in the idle position and the electric current is interrupted. It is also within the framework of the invention to realise this transparent wall of the switch housing additionally at the function displays of the example versions described above.

Claims

CLAIMS 1. Switch for an explosion-protected electrical appliance, in particular a light switch, with a housing (2,40) and an activator which can be positioned between an idle position (37,42) and an operating position (36, 46), characterised by a visual positional display (32,38).
2. Switch in accordance with the previous claim, characterised in that the positionai displays (32, 38) for the idle position (37,42) and the operating position (36, 46) are of different colours.
3. Switch in accordance with one or several of the claims above, characterised in that the positional display (32,38) for the idle position (37, 42) is green.
4. Switch in accordance with one or several of the claims above, characterised in that the positional display (32) for the operating position (36) is red.
5. Switch in accordance with one or several of the claims above, characterised in that the activator exhibits a plunger (13,39).
6. Switch in accordance with one or several of the claims above, characterised in that the coloured positional display (38) is positioned on the plunger (39).
7. Switch in accordance with one or several of the claims above, characterised in that the positional display (38) of the plunger (39) is provided between two wall sections (44,45) of the housing (40).
8. Switch in accordance with one or severai of the claims above, characterised in that the activator exhibits a preferably approximately Ushaped activator hood (7), which has at least one window (33 ! for the positional display (32).
9. Switch in accordance with one or several of the claims above, characterised in that the activator hood (7) exhibits at least one incline surface (34,35) circumscribing the window (33).
10. Switch in accordance with one or several of the claims above, characterised in that the activator hood (7) is supported between the wall parts (3,4) of the housing (2).
11. Switch in accordance with one or several of the claims above, characterised in that the activator hood (7) exhibits at least one guidance crosspiece (11) which is guided in a guidance groove (12) of the housing (2).
12. Switch in accordance with one or several of the claims above, characterised in that the activator hood (7) is coupled with the plunger (13).
13. Switch ir* accordance w'th one or severa ! of the claims above, characterised in that the coupling between the activator hood (7) and the plunger (13) is a supporting joint (15).
14. Switch in accordance with one or several of the claims above, characterised in that the supporting joint (15) exhibits preferably at least one supporting crosspiece (16) located on the activator hood (7), which meshes into a groove (17) preferably formed on the plunger (13).
15. Switch in accordance with one or several of the claims above, characterised in that the plunger (13) exhibits a cage (18) with at least one chamber (20,21), in which a contact bridge (22,23) is supported, to which a spring element is assigned.
16. Switch in accordance with one or several of the claims above, characterised in that a partition (19) is formed between two contact bridges (22,23).
17. Switch in accordance with one or several of the claims above, characterised in that the partition (19) is formed on the cage (18).
18. Switch in accordance with one or several of the claims above, characterised in that the part of the partition (19) extending out of the cage (18ì is fcrmed on a closure part {25) of the housing (2).
19. Switch in accordance with one or several of the claims above, characterised in that the plunger (13) and the cage (18) are made in one piece from a plastic.
20. Switch in accordance with one or several of the claims above, characterised in that the closure par (25) has at least one lug (26) meshing into a recess of the housing (2).
21. Switch in accordance with one or several of the claims above, characterised in that contact lugs (27) of electrical contacts (28) are supported in openings of the closure part (25) and held by means of projections (29).
22. Switch in accordance with one or several of the claims above, characterised in that the cage (18) with the contact bridges (22,23) and the spring (24) are supported, after the casting of the housing (2), in a switch room (31), which meets the explosion regulations.
23. Switch in accordance with one or several of the claims above, characterised in that at least one wall of the switch room (31) is transparent and the position display is constituted by the appropriate position of the switching contacts (22,23,28) visible from outside.
24. A switch constructed and adapted to operate substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.