EP0245176A1 - Multipolar rotary switch, in particular a cam switch in the shape of stacked modules, and method for its production - Google Patents

Abstract

A multi-pole rotary switch, in particular a cam switch, is formed by a stack of wafers in which the contact and connection elements are housed in chambers comprised between end walls and intermediate walls. The end and intermediate walls are provided in the form of molded parts (16) made of thermoplastic material, which mechanically assemble with each other and are rigidly fixed together. On the molded parts (16) there are tabs (50) which, when assembled side by side, extend laterally on the adjoining molded parts and are inserted behind the projections (62) which are provided there. After embedding, the tabs (50) are welded to the side walls of the molded parts (16) in order to produce a very rigid assembly.

Description

The invention relates to a multi-pole rotary switch, in particular a cam switch in the form of stacked wafers, the fixed contact and connection elements of which are housed in chambers between end walls and intermediate walls in the form of parts. molded in plastic, juxtaposed and rigidly connected with each other in order to constitute a compact support block traversed longitudinally in the center by the control shaft, the molded parts having, for their junction during the mounting of the claws which are being 'assembly extend laterally on the neighboring molded parts and are inserted behind corresponding projections, and the invention also relates to a method of manufacturing such a switch.

Rotary switches of the type mentioned are already frequently used as control devices incorporated alongside other control and signaling units in switchboards, consoles or the like. In this case, the stack of molded wafers is generally fixed only by one of the ends to a load-bearing element and must therefore have sufficient own robustness and rigidity with regard to the stresses coming from the camshaft, to ensure flawless operation even after a long service life.

In rotary switches with wafers known up to now, this robustness and rigidity are obtained thanks to a very stiff connection of the molded elements formerly made of porcelain and more recently of plastic material, using threaded rods passing through the entire stack. as tie rods. Such a mechanical connection is however expensive in terms of material and labor, and subsequently requires a guarantee of correct screwing, which in addition to appropriate care also presupposes a subsequent check.

The object of the present invention is therefore to avoid these screw connections with what this entails in terms of material and work costs, and to produce a rigid connection of the various molded parts making up the stator of the rotary switch for a lower cost. in labor and costs.

According to the invention, this objective is achieved by the fact that the molded parts consist of a thermoplastic material, and that the tabs on the side walls of these molded parts, after insertion behind the projections of the adjoining molded parts, are welded in view a very rigid junction.

Thanks to the adoption of the known method of lugs which snap behind projections provided on the neighboring molded parts, the invention offers the advantage of an easier preliminary assembly without tools, while simultaneously creating the necessary condition for the consecutive final assembly of the parts, by welding these tabs to the side walls of the adjoining molded parts, all these parts thus forming a rigid block in itself. It is true that disassembly of the switch without destroying the molded parts is no longer possible. However, the cost saving thus achieved lowers the overall cost of the rotary switch to such an extent that, for the rare cases of modification or extension of the switching functions, previously achievable by reconstruction, outright exchange of the complete switch may to be taken into account.

According to a first advantageous execution characteristic of the invention, the claws are formed in the form of flat lugs carrying orifices at the ends for accommodating protrusions therewith sliding ramps. Such a design creates, as a result of the small thickness of the tabs, particularly favorable conditions for the prior mounting and the subsequent welding, which can be further improved, according to another characteristic of the invention, by the fact that the lateral surfaces of the molded parts have in the range covered by the legs, ribs oriented in the direction of sliding with intermediate grooves, which at the end of this sliding initially prevent complete embedding of the legs behind the projections and allow only this junction closes during welding after softening and fusion with the legs.

In the proposed embodiment of claws in the form of flat legs, it is particularly advantageous that each molded part has on one side two pairs of protrusions for the insertion of the legs of contiguous molded parts offset by 180 ° relative to the 'control shaft; it follows, from this embodiment that is obtained after the final assembly, smooth exterior surfaces on both sides of the stack. This is also favorable to the welding process, which in the embodiment according to the invention for the production of a multipolar rotary switch of the type indicated at the beginning, is preferably operated by ultrasound, since the surfaces external beams facilitate the installation of sonotrodes.

• Figure 1 - représente la vue en perspective d'un commutateur à cames réalisé sous forme de galettes empilées,
• Figure 2 - est la coupe du commutateur à cames dans la zone d'une chambre de coupure, avec les éléments de contact et de raccordement,
• Figure 3 - représente la vue en perspective de deux pièces moulées en matière plastique servant de parois entre les chambres et de support aux éléments de contact et de raccordement, juste avant leur assemblage, et
• Figure 4 - est la coupe partielle d'une paroi latérale d'une telle pièce moulée suivant la ligne IV-IV de la figure 3.

The invention will be explained in more detail in the following with the accompanying drawings, in which:

• FIG. 1 - represents the perspective view of a cam switch produced in the form of stacked wafers,
• Figure 2 - is the section of the cam switch in the area of a switching chamber, with the contact and connection elements,
• FIG. 3 - represents the perspective view of two molded plastic parts serving as walls between the chambers and as support for the contact and connection elements, just before their assembly, and
• Figure 4 - is a partial section of a side wall of such a molded part along the line IV-IV of Figure 3.

The cam switch illustrated in FIG. 1 is a 12-pole model and for this purpose comprises a block of modules 10 consisting of two end modules 12, 14, and five intermediate modules 16 of identical design. The end modules 12, 14, and the intermediate modules 16 are designed in the form of molded parts made of thermoplastic material and constitute end and intermediate walls for the chambers which they limit laterally (FIG. 2) and in which, as specified below, are housed the contact and connection elements as well as the cams 18 fixed firmly on a shaft of square section 20, carried by bearings in the two end modules 12, 14, and which can pivot together step by step in a known manner using a joystick 22.

As shown more clearly in FIG. 2, two contacts are provided in each of these chambers, which can be either opening or closing contacts, each contact consisting of two identical fixed elements 24 which are mechanically and electrically connected by conductive bars 26 to connection terminals 28, and to a movable contact bridge 30 carried by a pusher 32 whose inner end ending in point 34 is kept applied against the cam disc 18 which has a profiled recess 38, and whose the other end is under the influence of a helical compression spring 36. The connection terminals are provided with clamping screws 40.

As shown in Figure 3, the intermediate modules 16 have a basic shape in principle square or rectangular and have a central opening 42 housing the shaft of square section 20. The opening 42 is mainly located in a partition transverse 44 forming a separation and to which is attached to one of the ends a front wall 48 having two pairs of legs 50 directed in opposite directions. The front walls 46, 48 are connected on either side of the opening 42 by longitudinal walls 54 having recesses 52, the outer surface of which forms housings 56 receiving the connection terminals 28 by virtue of the ribbed webs 58.

The end modules 12, 14, are provided identical, on the side facing the intermediate modules, to the molded parts 16 and each carry in a similar manner on the wall corresponding to the frantal wall 48, only two legs 50.

The end modules 12, 14 and the intermediate modules 16 stacked between them are each offset augularly by 180 ° relative to the square section shaft 20 during assembly, so that two legs 50 of the same orientation of each of the molded parts 12, 14, 16, protrude from the front wall 46 of the contiguous molded part. It is obvious that the two legs 50 remaining available on each molded part extend in the same way on the front walls of the contiguous molded part on the other side.

The front walls 46 are provided, in the zones 60 covered by the legs 50, with a recess in which there are two pairs of projections 62 with sliding edges in the form of a ramp 64, on which the legs 50 of the intermediate molded parts 16 or end modules 12, 14 slide during assembly to finally be inserted behind the projections 62 through the orifices 66 in the tabs 50.

As is particularly visible in FIG. 4, there exist on two sides of a pair of projections 62, in the direction of sliding, ribs 68 and intermediate grooves 70 against which the tabs 50 rest behind the projections 62 by elastic force, after insertion of the legs 50. In this way, an integral locking is impossible at first.

When the modules 12, 14, 16, have been assembled mechanically with the legs imperfectly inserted behind the projections 62 as explained above, an ultrasound generator (not shown) is applied by its sonotrodes to the legs 50 and therefore , the thermoplastic material of the molded parts heats up in the region of the ribs 68 and the grooves 70 as well as the tabs 50 which are supported thereon, from where the material melts and welding. During this process, the material of the ribs 68 flows into the grooves 70 under the pressure of the legs 50, the latter then being able to fully relax and thus form a practically flat surface on both sides of the stack of modules, hence an assembly forming a rigid block which has, even in the case of a fairly large length, the robustness and stability required in the face of the stresses arising from the control of the switching contacts, throughout the lifetime of the switch.

The intermediate modules 16 have on two sides, and the end modules 12, 14, on one side each, pins 72 and orifices 74 arranged asymmetrically with respect to a median plane located between the walls 48 or 46 carrying the tabs 50 or the projections 62 respectively, so that they can only be inserted into one another after a 180 ° offset from the square drive shaft 20, of the molded parts neighbors. Thus, a correct arrangement of the molded parts between them is facilitated during assembly and an assembly error is eliminated.

As shown in Figure 1, the end module 14 is divided into two parts 14a and 14b by a joint line, forming between them in a known manner a chamber (not shown) intended to accommodate a notch mechanism for the control shaft, allowing indexing of the switch in well-defined positions, The joining of the parts 14a, 14b, is in principle carried out in the same way as for the modules 12,14, with the intermediate modules 16, being specified however that instead of the legs 50 arranged side by side, there are provided through legs 75 with three passages corresponding to the orifices 66, the median passage having no particular function.

Claims (7)

1. Multipolar rotary switch, in particular cam switch in the form of stacked wafers, the contact and connection elements of which are housed in chambers comprised between end walls and intermediate walls in the form of juxtaposed molded plastic parts and rigidly connected with each other in order to constitute a compact support block, traversed in its center by the control shaft, the molded parts having, for their coupling during assembly, claws which during the junction extend laterally over the neighboring molded parts and are inserted behind corresponding projections, characterized in that the molded parts (12, 14, 16) consist of a thermoplastic material and that the claws (50) on the lateral surfaces of the molded parts thus fitted are welded after their insertion behind the projections (62), in order to produce the rigid assembly. 2. Rotary switch according to claim 1, characterized in that the claws are in the form of flat legs (50) provided with holes (66) at the ends, to accommodate the projections (62) provided with sliding ramps (64 ). 3. Rotary switch according to claim 2, characterized in that on the side walls of the molded parts (12, 14, 16) the areas (60) covered by the tabs (50) carry grooves (70) and ribs (68 ) oriented in the sliding direction, and which at the end of this sliding initially prevent the complete embedding of the tabs (50) behind the projections (62) and only allowing this junction during the welding operation after softening and fusion with the legs (50). 4. Rotary switch according to claims 2 or 3, characterized in that each of the molded parts (16) forming the partitions has on one side two pairs of legs (50) in opposite directions, and on the other side two pairs of projections (62) for insertion into the tabs (50) belonging to the adjoining molded parts (12, 14, 16), offset by 180 ° relative to the control shaft of the switch. 5. Rotary switch according to claim 4, characterized in that the molded parts (12, 14, 16) have on their front ends pins (72) and orifices (74) arranged asymmetrically with respect to a median plane located between the walls carrying the legs (50) or respect. The projections (62), so that they can only be inserted into one another after an angular offset of 180 °, relative to the control shaft, of the molded parts (12, 14, 16) neighbors. 6. Rotary switch according to one of the preceding claims, in which one of the end modules is formed by two parts allowing the autonomous housing of a notch mechanism intended to angularly position the control shaft, characterized in that the junction between the two parts (14a, 14b) of the divided end module (14) is designed in the same way as between the end modules (12, 14) and the intermediate modules (16), or between the modules intermediaries (16) between them. 7. A method of manufacturing a rotary switch according to one of claims 1 to 5, characterized in that the welding of the claws or respectively of the tabs provided on the sides of the molded parts is carried out by means of ultrasound.

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