AU749825B2 - Electric installation device with shape-retaining axial support - Google Patents

Description

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Certified translation Description ,i ELECTRIC INSTALLATION DEVICE WITH SHAPE-RETAINING AXIAL

SUPPORT

The present invention relates to an electric installation device according to the preamble of claim i.

Electric installation devices of this genre for mounting on top hat rails are in general safety cutouts or automatic cutouts (in the following shortly called automatic switches) having standardized mounting sections corresponding to the shape of the top hat rail and standardized electric connections to be used for so-called bus bars, however, having different release characteristics and nominal current intensities.

The prior art discloses an installation device of this genre which consists of an essentially rectangular flatly designed housing on the narrow front of which a manually operable switch means is provided. The narrow back is designed as a mounting section for fixing the housing on a top hat rail.

Normally, for reasons of insulation, the housing is made of a plastic material which is cast so as to form two housing halves which are joined together so as to define a housing cavity and which are interconnected for example by means of rivets. The inner sides of the housing halves are preformed according to the individual switch components or members which are accomodated in the housing cavity partially so as to be stationary and partially so as to be movable. More precisely, at the inner sides of the two housing halves, on the one hand, rib-like or ridge-like projections are provided which, upon joining of the housing halves, divide the housing cavity into plural differently dimensioned cavity areas for eiving the switch components. On the other hand, a number 2 of fastening bases is provided in each of which a blind hole is formed. Pivots required for pivotally supporting switch components such as coupling parts, contacts etc. are individually attached in the said blind holes by pressing or gluing. Simple steel rods on which the corresponding rotatable switch components are slidingly supported serve as pivots.

Now, it has become obvious that this variant of attaching the pivots includes the problem of a low mechanical and/or thermal stability and strength of the pivot bearings.

Automatic switches and/or their members partially heat up during operation, the heat being applied to the housing via the metal rods. Plastic material is not only an excellent electric insulator but also a bad heat conductor. I. e. heat within the housing is conducted outside only insufficiently, so that, in particular within the range of the pivot supports, temperature peaks in the housing may occur which cause a softening of the plastic material. In this state, the relative positions with respect to each other of the pivots may change and, due to this, operatability of the automatic switch may be impaired as a result of a reduced mobility of the rotatable switch components or their maladjustment. This change of the relative positions is supported by outside forces acting upon the pivots in particular when switch components are spring-biased. This is the case since, via the rotatable mechanical switch components which are supported on the pivots, a force resulting from e. g. a spring-biasing is applied to the pivots which is applied to the switch housing via the corresponding blind hole. If, now, the installation device is heated up the plastic material of the housing softens so that the pivots are shifted or deviated in the direction of the force. It has to be emphasized that automatic switches of this genre have numerous pivot groups whose switch components are biased in opposite directions, i.

Aq--which have to receive oppositely directed forces.

P:\WPDOCS\AMDANDREA\758408,0clais.doe-04/0402 -3- A further technical variant for the support of the rotatable switch components provides the arrangement of so-called sheet-bar locks where a plurality of through holes is bored in a metal plate, in which through holes the support pivots are placed in the form of steel rods.

Both variants, however, have the common disadvantage that they are relatively expensive and time-consuming. According to the first variant mentioned, every rod must be individually inserted and glued into the blind holes. According to the second variant mentioned, the arrangement of the metal plate increases material costs which is striking in particular in mass production.

In view of this problem, the invention seeks to provide an installation device of this genre whose operability is improved even under thermal and/or mechanical stress of its switch components without its manufacturing costs increasing compared to a conventional switch.

15 In a first broad form, the present invention provides an electric installation device having a :i housing made of a plastic material, in which a number of constituent members are accommodated which are mounted, so as to be capable of movement, on pivots attached in said housing, characterised in that at least two of said pivots are interconnected by a crossbar formed separately with respect to aid housing, and defining a u-shaped bride inserted into a groove correspondingly formed in said housing.

According to the invention, the installation device comprises a housing made of a plastic material in which a number of constituent members is accommodated which are mounted, e. so as to be capable of movement, on pivots attached in the housing. According to the invention, at least two pivots are interconnected by a crossbar, this crossbar being designed as a component located outside the housing. The advantage of this design consists in the o. •fact that forces acting upon the two pivots in essentially opposite directions are received by S the crossbar as forces of pressure or tensile forces, whereby the housing itself remains unstressed. Other forces whose directions do not follow the crossbar's alignment are distributed by the crossbar to interconnected pivots, i.e.

P:\WPDOCS\AMD\ANDREA\584080clan s.do-0404102 -4their application to the housing is effected via the at least two pivots and the crossbar disposed between them; thereby, the stress per unit of area can be considerably reduced and/or the area of application of force to the housing can be increased. Thus, a change of the original relative position of the pivots due to thermal and mechanical stress is effectively prevented. Besides, the housing is exposed to lower thermal stress peaks as, due to the crossbar and the consequently enlarged total surface of the pivot-crossbar subassembly, the thermal energy can be better distributed and conducted off.

Moreover, due to the shape of the crossbar according to the invention, only low extra expenditure of material is required which can be more than only compensated in that, when assembling the device, the two interconnected pivots are mounted simultaneously in one single step. This facilitates the mounting process of the pivots and reduces the total mounting time.

It is further provided that the two pivots and the crossbar define a U-shaped bridge, the •U-shaped bridge being an accordingly bent metal rod. This design has the advantage that the pivots can be produced very cheaply in one piece, that is by bending or pressing of a cheap material such as a metal wire.

In this case, according to a further development the insertion of the U-shaped bridge is effected in that the pivots interconnected by the crossbar carry members counteracting under the application of tensile or pressure force, wherein the crossbar allows a mutual o. support of the pivots so that the application of force to the housing is reduced. In other "r words, the crossbar extends along the opposite force directions which partially have to be expected and which act upon the interconnected pivots.

o o*• Also the design of the housing is simplified since not, as in the former prior art, a number of blind holes corresponding to the number of pivots but a reduced number of grooves has to be provided in which the crossbar of the U-shaped bridge is inserted and attached by pressing or gluing.

Further advantageous developments of the invention are described in the subclaims.

In the following, the invention is explained more precisely by using a preferred embodiment and by referring to the attached drawings.

Fig. 1 shows the perspective view of a housing half of an automatic switch with two shape-retaining axial supports in the form of two U-shaped bridges and Fig. 2 shows the arrangement of the switch components which are supported on the pivots of the two U-shaped bridges.

According to Fig. 1, the housing of an automatic switch consists of two housing halves which are cast and/or pressed of a plastic material and which are screwed together, thereby defining a housing cavity. The perspective view in Fig. 1 shows the inside of one of the housing halves 1. According to this figure, the housing cavity is divided into plural areas by ridge-like partition walls 2 which are formed integrally with housing halves 1. These partition walls 2 are adapted to the shape and function of the switch components which shall be accomodated in the individual cavity areas. Further, Fig.

1 shows two slit-like grooves 3, 4 which are provided in pedestal-like bases 5, 6 at the inside of the one housing half 1. In the grooves 3, 4, U-shaped bridges 7, 8 are inserted and fixed therein by pressing and/or gluing.

Each U-shaped bridge 7, 8 consists of a crossbar 9, ptegrally connecting two legs 11, 12; 13, 14 which form pivots for pivotally supporting switch components. The Ushaped bridges 7, 8 are made of metal rods which are bent so as to have the described shape. Alternatively, the U-shaped bridges 7, 8 can also be provided as stamped metal parts or can be composed of plural component parts e. g. by soldering or welding.

The depth of each groove 3, 4 in the housing 1 is selected so that, in the inserted state of the U-shaped bridges 7, 8, the end portions of the bridge legs 11, 12; 13, 14 on the crossbar side are embedded in the grooves 3, 4 over a certain length so that lateral forces acting upon the bridge legs 11, 12; 13, 14 can be received by the groove walls vertically to the crossbar direction. Additionally, the pedestal-like bases 6 in which the grooves 3, 4 are formed are interconnected as well as connected with the side walls of the shown housing half 1 by ribs 15 which are likewise formed integrally with the inside of the housing half 1. These ribs 15 serve for an additional reinforcement of the pedestal-like bases 5, 6.

In Fig. 2, the switch components of a plurality of further members specific for automatic switches (not further represented) are shown which are supported on the pivots formed by the two U-shaped bridges 7, 8 and/or their legs.

On the one pivot 11 provided on the housing edge side of the bridge 7 provided in the center portion of the housing, an actuating lever element 16 (shortly called toggle) is pivotally supported, consisting of a lever 17 projecting from the housing and a thick-walled cylinder 18 which simultaneously constitutes the hub for support on the pivot 11. In the cylinder wall, corresponding to an eccentric, an engagement member 19 is pivotally supported which is biased by a spring 20 in the cylinder's direction of rotation (according to Fig. 2 to the left). For doing so, the free end of the spring 20 is engaged with a pin 21 which is formed 4ntegrally with the housing half 1. Simultaneously, depending on the position of the toggle 16, the spring 20 applies a force to the engagement member 19 in the direction of rotation around its support on the toggle 16. The free end of the engagement member 19 (according to Fig. 2, right end) forms a peg which, vertically to the image plane according to Fig. 2, projects to the rear being capable of meshing with a notch 22 of a contact finger 23. This contact finger on its part is supported on an inner pivot 14 of the other bridge 8 according to Fig. 2 provided at the right side and is biased by a spring 25 in a direction where the contact finger 23 is not engaged with a stationary line contact 24, the free end of the shown spring 25 meshing with the other pivot 13 provided on the housing edge side of the same bridge Further, a release lever 26 in the form of a rocker is supported on the inner pivot 12 of the bridge 9 disposed in the center portion, whose one lever leg can be forced into engagement with the peg of the engagement member 19 in order to push same out of the notch 22 of the contact finger 23 and whose other lever leg can be forced into engagement with a bimetal element (not shown) for moving the release lever 26.

The exact functioning of the automatic switch only partially described above is sufficiently disclosed by the prior art so that corresponding publications can be referred to. Only for comprehension of the invention a general explanation of the motion cycle of the rotatable switch components as well as of the force distribution between the pivots as described is given in the following: In Fig. 2, the automatic switch according to the embodiment is shown in a switch position where a line contact is closed.

In this position, the toggle 16 is, according to Fig. 2, switched to the left, the engagement member 19 being, relative to the rotational axis 11 of the toggle 16, moved to the right so that the spring 20 acting upon the engagement &ber 19 is stretched. In this state, the peg of the engagement member 19 meshes with the notch 22 of the contact finger 23 and, consequently, presses same against the stationary line contact 24, wherein the shown flat spiral spring 25 is stretched for biasing the contact finger 23.

Further, in this switch position, the release lever 26 is not in contact with the engagement member 19.

The bimetal element which is not shown is electrically connected to the contact finger 23 via a cable (not shown either) so that, in the switch position according to Fig. 2, an electrical current is transmitted via the bimetal element, the cable and the contact finger 23 to the stationary line contact 24. Upon overstressing, the bimetal element heats up and becomes bent so that it meshes with the release lever 26 in order to move same. This causes the release lever 26 to come into contact with the engagement member 19 and pushes its peg out of the notch 22 of the contact finger 23. In this moment, the contact finger 23 is moved by the spring biasing, this interrupting the contact between the contact finger 23 and the stationary line contact 24.

In order to ensure a quick release of the automatic switch it is necessary to bias the contact finger 23 with a relatively high spring power. The arrangement of the bridge 8 according to Fig. 2 provided on the right side is chosen so that a part of the spring powers acting upon the housing edge side pivot of the bridge 8 is transferred via the crossbar 10 to the other inner pivot 14 on which the retractile forces of the flat spiral spring 25 act via the contact finger 23. As components of these forces are directed oppositely to each other they eliminate each other and are therefore no longer applied to the housing of plastic material 1. Other force components not eliminating each other are at least distributed to both pivots 13, 14 and applied to the housing 1 via these pivots 13, 14 and the crossbar 10. In this way, the surface of application of force in the housing is P:\WPDOCS\AMD\ANDREA\7584080clahns.do-O4/04/02 -9increased vis-A-vis e.g. one single rod as known from the prior art.

Besides, the U-shaped bridge 8 is used as a pivot in particular for the members which are exposed to thermal stress and, therefore, apply heat to the housing via the pivots. As a result of the increased surface of application of force, of course, also the surface portion is increased through which heat can be emitted to the housing 1. An increased heat emission consequently increases the cooling effect and local temperature peaks which may cause a softening of the plastic material of the housing 1 are reduced. For this reason, also during operation, the housing is still able to receive forces without plastic deformation. The bridge 7 is less stressed by forces and thermal energy. It is only provided to reduce mounting costs. The particularly high stress of the bridge 8 results from the fact that the contact finger 23 arranged thereon is metallically connected to the bimetal via a strand and, therefore, directly receives the heat of the bimetal element.

15 Moreover, by using the bridge 8, the entire contact mechanism supported on the bridge can be pre-mounted. This again allows a further reduction of the mounting costs.

Throughout this specification and the claims which follow, unless the context requires otherwise, the word "comprise", and variations such as "comprises" or "comprising", will 20 be understood to imply the inclusion of a stated integer or step or group of integers or steps S but not the exclusion of any other integer or step or group of integers or steps.

The reference to any prior art in this specification is not, and should not be taken as, an acknowledgement or any form of suggestion that that prior art forms part of the common general knowledge in Australia.

Claims (8)

1. An electric installation device having a housing made of a plastic material, in which a number of constituent members are accommodated which are mounted so as to be capable of movement on pivots attached in said housing, characterised in that at least two of said pivots are interconnected by a crossbar formed separately with respect to said housing, and defining a U-shaped bridge inserted into a groove correspondingly formed in said housing.

2. An electric installation device according to claim 1, characterised in that said U-shaped bridge is a suitably bent metal rod.

3. An electric installation device according to claim 1 or 2, characterised in that, on said pivots interconnected by said crossbar, constituent members counteracting under a tensile force or force of pressure are supported, wherein, via said crossbar, said pivots mutually support each other in such a way that essentially no force is applied to the housing.

4. An electric installation device according to claim 1 or 2, characteriaed in that said i 20 pivots interconnected by said crossbar serve to support a rotatable constituent member on the one pivot as well as to pivot a biasing means, preferably a spring, on the other pivot by means of which said constituent member is biased. An electric installation device according to any one of the preceding claims, characterised in that said groove which is formed in one housing half and in which said cross-bar is inserted, is slit-like.

P:\WPDOCS\AMD\ANDREA\7584080claims.doc-04/04/02 -11

6. An electric installation device according to claim 5, characterised in that the groove depth is selected so that an end portion of each of said pivots interconnected by said crossbar is embedded in said groove so that lateral force components acting upon said pivots vertically to said crossbar are received by the groove walls.

7. An electric installation device according to any one of the preceding claims, characterised in that said installation device is an automatic cutout and said constituent members are coupling parts and contacts.

8. An electric installation device substantially as herein described, having reference to the accompanying drawings DATED this 4 t h day of April, 2002 AEG NIEDERSPANNUGSTECHNIK 15 By Their Patent Attorneys DAVIES COLLISON CAVE.