WO1992014289A1

WO1992014289A1 - Enclosure for miniature circuit breakers

Info

Publication number: WO1992014289A1
Application number: PCT/FI1992/000034
Authority: WO
Inventors: Matti Makkonen
Original assignee: Fibox Oy Ab
Priority date: 1991-02-08
Filing date: 1992-02-06
Publication date: 1992-08-20
Also published as: DE4290308T1; FI910639A; AU1192192A; DE4290308C2; FI87286C; FI910639A0; FI87286B

Abstract

The invention relates to a box for automatic fuses, to contain preferably at least two sets (2, 3) of automatic fuses (5) positioned adjacent to each other, which fuses are fastened to a DIN rail of standard type, which box of automatic fuses comprises a box with a bottom (10) and two sidewalls (12, 13) opposite to each other, which sidewalls comprise several guide ribs (14) extending perpendicularly towards the bottom of the box and positioned at equal distance from each other for guiding the sets of automatic fuses to a desired place against the bottom of the box as well as means (14, 15) for fastening the sets of automatic fuses in the desired final position in the box. In order that the cables, which shall be connected to the sets of automatic fuses, can be connected easily and quickly, the box for automatic fuses comprises quick-fastening devices (14, 15) for placing the sets (2, 3) of automatic fuses in a mounting position, which is at a considerably larger distance from the bottom (10) of the box than the final installed position of the sets of automatic fuses.

Description

Enclosure for miniature circuit breakers.

The present invention relates to a box for automatic fuses, to contain at least one set, pre- ferably at least two sets, of automatic fuses posi¬ tioned adjacent to each other, which fuses are fas¬ tened to a DIN rail of standard type. The box for automatic fuses comprises a box with a bottom and two side walls opposite to each other, which side walls comprise several guide ribs extending perpendicularly to the bottom of the box and positioned at equal dis¬ tance from each other for guiding the set (sets) of automatic fuses to a desired place against the bottom of the box in order to facilitate the installation of the set (sets) of automatic fuses and means for fas¬ tening the set (sets) of automatic fuses in the de¬ sired final position in the box.

Boxes for automatic fuses of this kind are very common at different industrial installations, in which they are used e.g. in connection with electric motors and ■ contact clocks. The sets of automatic fuses are installed in the box at a standardized dis¬ tance of 125 mm from each other and they are fastened with screws to holes in the bottom of the box, which holes are arranged in a row along the two opposite edges of the box. The distance between two adjacent holes (in the same row) is standardized to 25 mm. The number of fuses in a set of automatic fuses is 12. It is usual that the box contains three sets of automa- tic fuses.

When mounting the boxes for automatic fuses ready for use, the traditional procedure is such that the necessary sets of automatic fuses are at first put in order, whereby automatic fuses of a desired size are positioned adjacent to each other and fas- tened to a DIN rail by means of quick-fastening, by pressing them securely on the rail. After this the sets of automatic fuses are dropped against the bot¬ tom of the box and fastened with screws to the DIN rail in the final position. The bottom of the box is then normally in a horizontal position. After this the electric cables are mounted in place in such a way that each fuse to be used will be connected. When installing, the first ends of the cables are connec - ed to respective automatic fuse and the second ends of the cables are connected to a so-called terminal strip, which is also fastened to said hole in the bottom of the box. The problem with the procedure described is that the cables, several tens in number, are difficult to connect: according to directions, the cables to be connected must be drawn below the sets of automatic fuses, i.e. between the sets of automatic fuses and the bottom of the box, where there is only little room. It is difficult to work with the hands in the tiny space being at disposal and the connecting procedure will not be only diffi¬ cult but also time-consuming. Correspondingly, the connecting procedure will be difficult in the common situation when it is necessary to make changes in the sets of automatic fuses later on, when it is, for in¬ stance, necessary to connect further automatic fuses for use, which previously have been standby fuses only, or when a change of the type of automatic fuse is desired. A box for automatic fuses is known, which com¬ prises special-constructed side walls in order to remedy said problem. In two opposite side walls of this known box, a recess directed towards a cover of the box is provided substantially along the whole length of the side walls, the depth of which recess is several centimetres, whereby the cover of the box has been lengthened correspondingly at the recesses to maintain the density required of the box. The ob¬ ject of the recesses is that it shall be easier to reach the area below the sets of automatic fuses in the purpose of not being difficult to mount the cables. Only a slight improvement in the mounting procedure is attained by this known box for automatic fuses and the improvement is restricted to the mount- ing of those cables only which shall be connected to the fuses which are positioned closest to the edges of the box. Due to said recesses, however, this known box for automatic fuses is impaired by sealing prob¬ lems, which do not exist in conventional fuse boxes: it is difficult and technically complicated to get the cover well-sealed against the side walls of the box.

The object of the present invention is to pro¬ vide a box for automatic fuses which do not show the problems described above. To achieve this object the box for automatic fuses of the invention is mainly characterized in that it comprises quick-fastening devices for placing the set (sets) of automatic fuses in a mounting position which is at a considerably larger distance from the bottom of the box than the final installed position of the set (sets) of automa¬ tic fuses. The mounting position permits that the hands get well at the cables in order to draw them to their respective places. The quick-fastening devices preferably consist of fastening parts and recesses, which fastening parts comprise support surfaces, which have been formed for receiving one end of the DIN rail, as well as projections, which are meant to engage with the recesses which have been made in the guide ribs. Such fastening parts make it possible to use standard DIN rails, and a fastening by means of projections and recesses is simple to provide in practice, as far as manufacture is concerned, and it allows a firm fastening. It is especially preferable that each fastening part comprises a frame portion, preferably of plastic, which is surrounded by two elastic arms, which are fastened to the frame portion and which are provided with projections, whereby the projections engage with the recesses of the guide ribs by the aid of the spring back property of the arms, when the fastening part is brought into such a position that the projections and recesses will be adjacent to each other. On account of such a fasten¬ ing part with two projections, the fastening by means of projections and recesses can be manufactured of plastic in a small size, at the same time as the fas¬ tening becomes firm enough to hold the quite heavy set of automatic fuses at desired height in the box. The distance between the arms is preferably such that the outer lateral surfaces of the arms are provided with minimum play in order . to be guided against the guide surfaces of the guide ribs and that the projec¬ tions are arranged at a distance from these lateral surfaces in order to make it possible that the fas- tening part is guided along the whole length of the lateral surfaces. Such a construction provides a good guidance for the set of automatic fuses, when it is displaced along the walls of the box perpendicularly to the bottom: the set of automatic fuses does not tilt to either side, and thus, the so-called bureau shelf effect is avoided, which means that the fasten¬ ing part gets stuck to the guide surfaces of the ribs, the way a bureau shelf tends to get stuck to the side walls of a bureau. Preferable embodiments of the invention are presented in the enclosed claims 2 to 12.

The advantages of the box for automatic fuses of the invention are that the cables, which shall be connected to the sets of automatic fuses, can be con- nected easily and quickly without needing to make any changes whatsoever in the standard components, i.e. the automatic fuses, the DIN rail and the terminal strip, which are used in the box for automatic fuses. In addition, the box can be manufactured by normal manufacturing techniques and it can be made tight without difficulties. A preferable embodiment, which is presented in claim 8, allows that the conventional holes and fastening screws can be omitted.

The invention will be described in the follow- ing by means of a preferable embodiment with refer¬ ence to the enclosed drawing, in which

Figure 1 shows the box mounted ready for use,

Figure 2 shows the inside of the box and only partially mounted, Figure 3 shows a set of automatic fuses to be placed in the box; - ^{• ■}-

Figure 4 visualizes how the fastening part and the set of automatic fuses are joined to each other,

Figure 5 shows the box in mounting position, Figure 6 shows the DIN rail on which the auto¬ matic fuses are mounted,

Figures 7 to 11 show the fastening part of Fig¬ ure 4 in detail and

Figure 12 visualizes the elastic properties of the fastening part and how it is displaced with re¬ spect to the guide ribs of the box.

The box for automatic fuses in Figure 1 com¬ prises three sets 1, 2, 3, of automatic fuses, posi¬ tioned in a row above each other and consisting of several automatic fuses 5 or other components 6 posi- tioned adjacent to each other. The sets 1 to 3 of automatic fuses lie behind a cover 7 of the box, which cover is manufactured transparent, so that the sets 1 to 3 and indications 8, which state the con- tents of the fuses 5 and the other components 6, can be seen without having to open the lock.

Figure 2 shows two sets 2 and 3 of automatic fuses and a terminal strip 9 placed in the box in final installed position. The distance X between the sets 2, 3 is 125 mm. In Figure the cables have not been mounted, which cables shall be connected between the individual fuses 5 and the terminal strip 9. These cables, which have not been drawn in the figure either, shall be, when installed, below the sets 2, 3, close to the bottom 10 of the box. The bottom 10 of the box comprises two rows of holes 11 running along two opposite edges of the box, the distance Y between the holes being 25 mm. The holes 11 exist for fastening the sets 2, 3 and the terminal strip to the bottom 10 by means of screws.

From Figure 2 is seen that two opposite side walls 12 and 13 of the box comprise several guide ribs 14 extending perpendicularly to the bottom of the box and positioned at equal distance from each other for guiding the sets 2, 3 of automatic fuses and the terminal strip 9 to a place desired against the bottom 10 of the box. For guiding are used fas¬ tening parts 15, which are positioned at the ends of the sets 2, 3 and the terminal strip 9. Figure 3 shows a set 3 of automatic fuses, which is ready to be placed in the box. The fuses of the set 3 have been mounted on a DIN rail 16 of stan¬ dard type and the fastening parts 15 receive the ends of the DIN rail. Figure 4 shows a fastening part 15 separate from the set 3 of automatic fuses and another fasten¬ ing part 15 mounted at the terminal strip 9. The fas¬ tening part 15 is mounted to the set 3 quite simply by bringing the fastening part towards the DIN rail 16 in the direction of the arrow, whereby support surfaces, which have been formed at the fastening part, receive the end of the DIN rail.

Figure 5 shows how a set 3 of automatic fuses has been placed in mounting position by means of the fastening part 15 and the guide ribs 14. In the mounting position shown, the set 3 lies at such a great distance from the bottom 10 of the box that the cables (not shown), which shall be connected to the individual automatic fuses 5 and to the terminal strip, can be easily drawn by hand between the set 3 and the bottom 10. From the Figure is seen that the set 3 of automatic fuses with the DIN rail is held in the mounting position shown by means of projections 17 existing at the fastening part 15 and recesses 18 provided in the guide ribs, which projections engage with the recesses. - -

From Figure 5 is also seen that further reces¬ ses 19 have been provided in the guide ribs 14 at a distance closer to the bottom 10 of the box than the recesses 18 for bringing the set 3 of automatic fuses into mounting level. The further recesses 19 have such a distance from the bottom 10 of the box that they receive the projections 17 of the fastening part 15, when the set 3 of automatic fuses is in its final installed position with the cables (not shown) con¬ nected. Thanks to the fact that there are recesses 19 also on a level close to the bottom 10 of the box, the sets of automatic fuses can be held in the final installed position without the need of the customary screws (not shown), by means of which the sets and the terminal strip are conventionally fastened to the holes 11 in the bottom 10 of the box. In order to secure a very firm fastening of the sets of automatic fuses, screws (or the like) are preferably used in a known manner. For this purpose, the fastening parts are provided with a through hole 20 (see Figure 10).

In Figure 6, the DIN rail 16 generally used in boxes for automatic fuses is shown, on which rail the fuses 5 and possible other components (6) are posi- tioned. The holes 21 in the rail 16 are for screws

(not shown) by which the rail can be fastened to the holes (11) in the bottom (10) of the box.

Figures 7 to 11 show the fastening part 15 more accurately from different angles (from the front, from the side, from behind, above and below). From the figures is seen that the fastening part 15 com¬ prises a frame portion 22, which is surrounded by two arms 23, 24, which are fastened below to the frame portion 22. The fastening part 15 is manufactured of plastic in such a way that the frame portion 22 and the arms—23, 24 form one piece. The previously men¬ tioned projections 17 have been positioned at the ends of the arms 23, 24 facing away from the frame portion 22. As can be seen from Figure 8, the arms 23, 24 are bent back in unloaded state, which pro¬ vides the fastening part with a prestress of some kind. When the fastening part 15 is manufactured of plastic, the arms 23, 24 become elastic, which means that when the fastening part 15 is loaded in the mounting position (cf. Figure 5), the arms 23, 24 get straightened, and due to that, the projections 17 will bear against the bottom of the recesses 18 of the guide ribs 14, thanks to the tendency of the arms 23, 24 to spring back. Said "prestress" does that the fastening part 15 engages firmly with the guide ribs 14. A lateral displacement of the fastening part 15 on the level of the side wall 12 (parallelly with the bottom 10) is prevented by the fact that the distance between the arms 23, 24 is such that outer lateral surfaces 25 of the arms have been provided with little or minimum play to be guided towards nearby guide surfaces of the guide ribs 14. Thanks to the fact that the projections 17 have been positioned at a distance Z from these lateral surfaces 25 (see Fig- ure 10), the fastening part 15 will be guided along the whole length of the lateral surfaces 25 (see Fig¬ ure 7). Through this is provided a continuous exact guidance for the fastening part 15 when this is pushed down and up along the lateral walls (12, 13) of the box. From Figure 9, for instance, is seen that the frame portion 22 comprises a central longitudinal groove 26 for receiving one guide rib (guide rib 14' in Figure 5 ) of the box with little play. The groove 26 helps to provide the fastening part 15 with an exact guidance.

At their ends facing away -from the--frame por¬ tion 22, the arms 23, 24 of the fastening part 15 have been connected with each other by means of a bridge 27, which forms that portion of the fastening part by means of which a displacement of the set of automatic fuses along the guide ribs can be carried out easily: the bridge 27 is pressed with the fingers in the direction of the set 3 of automatic fuses (see Figure 5), after which the projections 17 are releas- ed from the recesses 18 and the fastening part (and the set of automatic fuses at the same time) can be displaced easily, controlled by the finger tips.

The DIN rail 16 has been drawn in Figures 7 to 11 with a broken line to illustrate the fact that it is supported both on horizontal 28 and perpendicular 29 support surfaces of the frame portion 22 (cf. Fig¬ ure 7), which support surfaces prevent the DIN rail from being displaced with respect to the fastening part in a direction other than the mounting direction of the fastening part on the DIN rail, see Figure 4.

Figure 12 illustrates the elastic properties of the fastening part 15 and shows that the fastening part is guided by the whole length of the lateral surfaces 25 (thanks to the displacement Z, see Figure 10). From the figure is also seen that the fastening part 15 comprises a wall portion 30 facing the set 3 of automatic fuses, which wall portion bears against the farthest fuse of the set to bring the set to an exact final position between the opposite side walls of the box, in which position the DIN rail can be fastened to the holes of the bottom of the box. Thanks to the wall portion 30, the set 3 of automatic fuses will also be guided precisely so that the far¬ thest fuses do not get stuck to the side walls of the box when introducing the sets into the box and the f-use -sets will be placed in a correct position with respect to the cover 7 of the box.

From Figure 12 is also seen that the guide rib 14 comprises wedge-shaped guide surfaces 31, 32 in the vicinity of the recesses 18, 19, on both sides of these, which wedge-shaped guide surfaces face the set 3 of automatic fuses and bear against the projections 17 of the fastening part when the set of automatic fuses is pushed along the side walls (12, 13) of the box. Thanks to the wedge-shaped guide surfaces 31, 32, the displacement of the fastening part at the area of the recesses 18 will be easily controllable and the lateral surfaces of the arms guide the fas¬ tening part along the whole length of the lateral surfaces. The invention has above been illustrated by means of only one preferable embodiment. Therefore, it shall be noted that individual details of the in¬ vention can be realized in many ways within the scope of the claims enclosed. In this connection, it is stated that the fastening part can be considered to comprise only one elastic arm in order to stand in functional relation to one guide rib or several guide ribs; the guide ribs need not necessarily be provided with further recesses in the bottom of the box; the prestress of the fastening part need not be realized in the described integrated manner by shaping the fastening part, even if this manner is to be recom¬ mended due to its simplicity; the guide ribs need not comprise wedge-shaped guide surfaces (31), even if these are to be preferred, because they facilitate the displacement of the sets of automatic fuses along the guide ribs to a great extent.

It shall also be noted that the box for automa- tic fuses described is in principle suited for con¬ taining electric components other than automatic fuses, which electric components have the way of fas¬ tening similar to that of the automatic fuses.

Claims

Claims :

1. A box for automatic fuses, to contain at least one set, preferably at least two sets (1 to 3), of automatic fuses (5) positioned adjacent to each other, which fuses are fastened to a DIN rail (16) of standard type, which box for automatic fuses com¬ prises a box with a bottom (10) and two side walls (12, 13) opposite to each other, which side walls comprise several guide ribs (14) extending perpendi¬ cularly to the bottom of the box and positioned at equal distance from each other for guiding the set of automatic fuses to a desired place against the bottom of the box in order to facilitate the installation of the set (sets) of automatic fuses and means (15, 19) for fastening the set (sets) (1 to 3) of automatic fuses in the desired final position in the box, c h a r a c t e r i z e d in that the box for auto¬ matic fuses comprises quick-fastening devices (15, 18, 19) for placing the set (sets) (1 to 3) of auto¬ matic fuses in a mounting position which is at a con¬ siderably larger distance from the bottom (10) of the box than the final installed position of the set (sets) of automatic fuses.

2. A box for automatic fuses according to claim

1, c h a r a c t e r i z e d in that the quick-fas¬ tening devices consist of fastening parts (15) and recesses (18, 19), which fastening parts comprise support surfaces (28, 29), which are for receiving one end of the DIN rail (16), as well as projections (17), which have been formed to engage with the re¬ cesses provided in the guide ribs (14).

3. A box for automatic fuses according to claim

2, c h a r a c t e r i z e d in that each fastening part (15) comprises a frame portion (22), which is surrounded by two elastic arms (23, 24), which are fastened to the frame portion and which are provided with projections, whereby the projections engage with the recesses (18, 19) of the guide ribs (14) by the aid of the spring back property of the arms, when the fastening part is brought into a such position that the projections and recesses will be adjacent to each other.

4. A box for automatic fuses according to claim 3, c h a r a c t e r i z e d in that, in unloaded state, the arms (23, 24) of the fastening part (15) are bent back with respect to the rest of the frame portion (22) in order to be straightened when loaded, after the fastening part has been mounted in the box, and thus to make the projections (17) of the fasten¬ ing part bear against the bottom of the recesses (18, 19), after the fastening part has been mounted in the box.

5. A box for automatic fuses according to claim 3 or 4, c h a r a c t e r i z e d in that the pro¬ jections (17) are positioned close to the ends of the arms (23, 24) facing away from the frame portion (22).

6. A box for automatic fuses according to claim 3 or 4, c h a r a c t e r i z e d in that the ends of the arms (23, 24) facing away from the frame por¬ tion (22) are connected with each other by means of a bridge (27), which forms that portion of the fasten¬ ing part (15) by means of which the displacement of the set of automatic fuses along the guide ribs (14) is carried out.

7. A box for automatic fuses according to claim 3 to 6, c h a r a c t e r i z e d in that the dis¬ tance between the arms (23, 24) is such that outer lateral surfaces (25) of the arms are provided with minimum play to be guided against adjacent guide sur¬ faces of the guide ribs (14) and that the projections (17) are positioned at a distance from these lateral surfaces to make it possible that the fastening part 15 is guided along the whole length of the lateral surfaces.

8. A box for automatic fuses according to one of the claims 2 to 4, c h a r a c t e r i z e d in that further recesses (19) are provided in the guide ribs (14) at a distance closer to the bottom (10) of the box than the recesses (18) to bring the set (1 to 3) of automatic fuses to the mounting level, which further recesses have such a distance from the bottom of the box that they receive the projections (17) of the fastening part (15) when the set of automatic fuses is in its final installed position.

9. A box for automatic fuses according to one of the claims 2 to 8, c h a r a c t e r i z e d in that the guide ribs (14) are provided with wedge- shaped guide surfaces (31) in the vicinity of the recesses (18, 19) on both sides of these, which wedge-shaped guide surfaces face the set (1 to 3) of automatic fuses and bear against the projections (17) of the fastening part (15) when the set of automatic fuses is displaced along the side walls (12, 13) of the box.

10. A box for automatic fuses according to one of the claims 3 to 6, c h a r a c t e r i z e d in that the frame portion (22) of the fastening part (15) comprises a central longitudinal groove (26) for receiving one guide rib (14' ) of the box with little play.

11. A box for automatic fuses according to one of the claims 2 to 6, c h a r a c t e r i z e d in that the fastening part (15) comprises a wall portion (30) facing the set (1 to 3) of automatic fuses to bring the set of automatic fuses into an exact final position between said opposite side walls (12, 13) of the box.

12. A box for automatic fuses according to one of the claims 2 to 8, c h a r a c t e r i z e d in that the fastening part (15) is manufactured of plas¬ tic in one piece.