GB1585025A

GB1585025A - Electrical switch

Info

Publication number: GB1585025A
Application number: GB14695/78A
Authority: GB
Original assignee: Individual
Current assignee: Individual
Priority date: 1977-04-16
Filing date: 1978-04-14
Publication date: 1981-02-18
Also published as: FR2387504A1; DE2716964C3; IT7822363A0; DE2716964B2; JPS53131485A; YU88678A; IT1094382B; FR2387504B3; DE2716964A1

Description

(54) ELECTRICAL SWITCH (71) We, KARL FISCHER, a German citizen of Am Gaensberg, 7519 Oberderdingen, Federal Republic of Germany, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: The invention relates to an electrical switch of the kind having a housing which comprises at least two housing portions each having a central opening and through which passes a rotary switch spindle, which housing accommodates resilient current-carrying contact blades which are actuated by the switch spindle by way of, for instance, cams, and which are fixedly arranged at one end thereof on the housing, while their other ends cooperate with a fixed counter-contact: the contact blades and the counter-contacts being fixed in the housing.

An electrical switch of this type is known from German Patent Specification No.

2,131,564. In this switch, it is possible to stack a plurality of housing portions one on top of the other and thus to provide ganged switches having widely differing numbers of contacts and combinations in a unitcomposed system. The contact blades are fixed in slots in the edge of the housing portion and are movable in a radial direction of the spindle. Two resilient contact blades are provided for each housing unit and are actuated by radially operating cams.

These slots have to be dimensioned very accurately, and the contact blades have to be inserted under a certain stress since they have to be self-retaining in the slots. This complicates automated assembly.

An object of the present invention is to further improve a switch of this type such that its construction and assembly are further simplified and such that the possibilities of varying the switch, and its compactness, are further improved.

The present invention resides in an electrical switch having a housing which comprises at least two housing portions, each of which has a base with a central opening therein, through which passes a rotary switch spindle, and lateral walls at least one of which has a castellated edge such that the two housing portions fit together with projections of the castellated edge of one housing portion engaged in mating recesses of the complementary castellated edge of the other housing portion, the switch also having contact blades and counter-contacts which are located in recesses of one castellated edge and are engaged by mating projections of the complementary castellated edge and which extend into the switch cavity defined by the two housing portions, the contact blades being deflectable in the axial direction of the switching spindle and the latter carrying a cam plate also located in the switch cavity, which cam plate has thereon cam surfaces defined by axial projections and/or axial recesses for the purpose of actuating the contact blade.

Thus, by virtue of the invention, there is provided an electrical cam switch which can be assembled from individual housng portions which inter-engage in the manner of inter-engaging teeth. The contact blades and counter-contacts, which may be in the form of simple members punched from sheet metal and which may also be inserted mechanically, are thereby fixed. An optional number of contact paths can be accommodated in a switch by appropriate stacking of housing portions. In particular, it is also possible to arrange a plurality of contact paths adjacent to one another and/or to provide, within a switch cavity formed by two adjacent recesses, two planes of contacts which are actuated by the two sides of the cam plate. Thus, when three contacts are located adjacent to one another in each case, six contact paths are combined in a minimum space with a height of, for example, only 20 millimetres.

The present invention will now be described, by way of example only, with reference to the accompanying drawings, in which: ,Figure'1 is an axial cross section through a switch of the present invention, comprising two housing portions, taken on the line I-I of Figure 2, Figure 2 is an inverted plan view of the upper housing portion of Figure 1, but with a switch spindle and a cam plate removed, Figure 3 is an elevation of the switch of Figure 1, viewed from the rear remote from the operating end, showing a detent member, not illustrated in Figure 1, for fixing the positions of the switch, Figure 4 is a further view of the switch of Figure 3, Figure 5 is a side elevation of the cam plate, Figure 6 is a plan view of the cam plate of Figure 5, Figure 7 is a side elevation of a further embodiment of a switch in accordance with the invention, having twenty-four poles, and Figure 8 is a detailed section, drawn to a layer scale, through a plug connection tang, taken on the line VIII-VIII of Figure 7.

The embodiment of a switch 11 shown in Figures 1 to 6 has two housing portions 12,13 which are made from plastics material and which are of identical construction, the basic shape of each housing portion being that of a square box having a base 14 and lateral walls which define a respective recess 46, such that the two recesses form the interior cavity 34 of the box. The lateral walls are of differing height, namely, there are two lower walls 16 and two higher walls 17, the walls of equal height being located opposite one another.

The outer edges of the lateral walls are castellated, that is, they have alternating projections 18 and recesses 19 which may also be slightly chamfered to facilitate the fitting together of a respective projection and respective recess. The castellation is such that, when two housing portions are assembled, each two identical parts respectively of the two housing portions are staggered in relatipn to one another, that is to say, a higher wall of one housing portion is positioned at a lower wall of the other housing portion. Furthermore, the projections 18 on the higher walls fit in the recesses 19 in the lower walls. The bottom surfaces 20 of the lateral walls of the two housing portions 12 and 13 in two different, i.e. axially spaced' planes.

In the illustrated embodiment, three recesses 19 and two projections 18 are provided adjacent to one another in each lower lateral wall 16, and, consequently, three projections and two recesses are provided on each higher lateral wall 17. The four corner portions are located approximately on a level with the bottoms of the recesses in the higher lateral walls 17 and with the end faces 47 of the projections on the lower lateral walls 16. Bores 21, extending in the axial direction of the switch, pass through the said corner portions and receive rivets 22 which hold the housing portions together.

In the region of the recesses 19 of the lower lateral walls 16, spigots 23 project from the bottom 20 of each recess and, in the illustrated embodiment, are cylindrical, although, alternatively, they may be of rectangular or other configuration. Comer plementary depressions or holes 24 are formed in the projections 18 on the higher lateral walls 17 and are located opposite the spigots 23.

A contact member is located in each depression in the lower lateral walls 16, namely, a fixed counter-contact 25 on one side and a contact blade 26 on the other side. In the illustrated embodiment, each contact blade comprises a plug connection tang 27 made from a somewhat thicker sheet metal of good conductivity than the rest of the blade and forming a so-called AMP flat plug pin which slopes in a direction away from the operating end above which an arrow 28 is shown. The plug connection tang 27 is in the form of a bent member and is connected by spot welds 29 to a spring blade portion 30 of the contact blade. The spring blade has a stiffening corrugation 31 and an indentation 32 (shown in Figure 1) which is directed towards the centre of the switch and which forms the actuating point of the contact blade. The spring blade and the plug tang 27 are interconnected in the fixing region, namely, where the contact blade extends out of the switch through the recess 19. In this region, the contact blade has a hole 33 which is engaged by a spigot 23 and is thus fixed in its exact position.

The counter-contacts 25 are made entirely from the material used for the plug tangs.

They are likewise angled and provide an end extending into the cavity 34 of the switch and at that end carry respective fixed contacts which co-operate with corresponding contacts at the ends of the contact blades. In the illustrated embodiment, two counter-contacts 25 (Figure 2) are interconnected by means of a strap 35 located outside the switch body, so that two counter-contacts are electrically inter-connected and can be supplied, by a common terminal.

In the region of the respective recess each counter-contact has, on each side, two edge notches 36 which form therebetween a sheet-metal tab 37 which is slightly bent in order to compensate for the difference in height relative to the contact blade side where the thickness of the blade is taken into account.

It will be seen in Figure 2, that the contact blades and the corresponding counter contacts are narrower than the plug tangs and, in the regions of this reduction in width, are offset transversely relative to the recesses 19. Furthermore, the central region -38 of the centre contact blade is of arcuate shape, so that it passes around the central axis of the switch at a distance therefrom.

Thus, it will be seen that the actuating points 32 of all three- adjacently located contact blades are at differing radial dis tances from the central axis 39 of the switch housing.

The base 14 of each housing portion has an opening 40 concentric with the central axis 39 and through which the switch spindle 41 extends. In the present instance, the switch spindle is a conventional spindle having a flat on one side in order to fix thereon, in a manner fixed against rotation relative thereto, an operating knob (not illustrated) at the operating end, a switching cam 42 and a detent star wheel 43 (Figure 3). The switch spindle extends forwardly th'rough an eyelet-like connection member 44 or, alternatively, through a connection member punched from sheet metal, in tended for the screwing-on of the switch.

The switching cam is located in the switch cavity 34 which is formed by the two recesses 46 by virtue of the fact that the two housing portions 12,13, staggered through 90" relative to one another, are joined together by their lateral walls such that the projections and recesses interengage and thereby in each case clamp the contact blades and the counter-contacts between the bottom 20 of a recess 19 and the end face 47 of the projection 18.

The switching cam has a hub 48 (Figure 5 and 6) through which the spindle passes, and a flat cam plate 49 which projects from the hub and whose two axially directed surfaces carry projections 50 forming the actual switching cam surfaces. It will be appreciated that, alternatively, the surface of the cam plate opposite the projections might be designated "depression".

These -switching projections are in the form of annular portions and are provided at three different radial distances corres ponding to the distances of the actuating points 32 of the contact blades from the central axis. Reference is made to Figures 5 and 6 in this connection.

The detent star wheel 43, shown in Figures 3 and 4, serves to fix the individual switching positions of the switch 11. The detent star wheel comprises a multi radiating star which co-operates with a bow-type spring or leaf spring 52 which is supported at each end on a sheet-metal member 51 riveted to the switch housing, and which has a central bow which engages the recesses in the detent star wheel 43.

Figure 3 also shows that two contacts located in two different planes can be bridged around a corner of the switch by means of a strap 35'.

Thus, a switch is provided which, in the embodiment of Figures 1 to 6, includes a switch cavity 34 in which six different contact paths are switched by means of a single switching cam 42. Three contact paths in each case are located in one plane on one side of the cam plate and their connections are located adjacent to one another on two opposite sides of the switch. The width of the entire body, including the connections, can be kept very small by angling the plug-connection tangs. It is particularly advantageous that the corresponding other connections come out on the other sides and their planes are offset relative to the first connections, so that the connections do not overlap and there is little risk of shortcircuiting. It will also be seen that the switch can be produced with a minimum of parts, particularly metal parts, and that the plastics material parts can be constructed in a very simple manner and can be readily removed from the moulds.

By way of example, the illustrated switch having a total of six contact paths might be used as a so-called "seven-position switch" for controlling hotplates, having three hot conductors, in six different switching steps (and "off"). Its size is only a fraction of the size of conventional seven-position switches. This is particularly important when fitting the switch into flat hobs etc.

However, a special advantage of the invention is that switches having a large number of poles, such as are required in a large number of domestic and kitchen appliances, can be combined in a very small space. This is shown by the switch of Figure 7 which as a total of twenty-four poles, that is, twenty-four contact paths with a total of forty-eight connections.

In the switch of Figure 1, all the housing portions were in the form of a box open at one side and, with appropriate assembly, formed the switching cavity 34 there be tween, while, in the switch of Figure 7, only the two end portions are constructed in this manner. Housing portions 54 are located therebetween and, instead of the base 14, have a central wall 55 (indicated by broken lines) from both sides of which extends a castellated edge which cooperates with correspondingly castellated portions of the adjacent portions of the housing. In this manner, the twenty-four pole switch can be constructed from only two outer and three central double-rimmed lateral-walled hous ing portions. It nevertheless includes a total of four switch cavities each having six contact paths.

Alternatively, however, it is possible to construct high switch columns, having a large number of contact paths, without the double-rimmed lateral-walled housing portions 54 by assembling a plurality of switches, of the construction of Figures 1 to 4, with their bases 14 abutting one against the other (wherein, of course, only one detent star wheel is in this case provided at the end).

This latter solution has the advantage that only a single type of construction of the housing portion is required for all the switches, so that a genuine module composed system is provided having only one basic module. Figure 7 also shows that the castellation does not necessarily have to be uniform. On the contrary, the offset required in the case of the central contact can also be taken into account in the castellation, so that the bend 38 does not need to be so pronounced.

A very simple construction of the contact members ensues when the plug tangs 27 are made from the same material as the spring blades 30. In this case, the material of the plug tangs would, of course, normally be too thin to effect proper clamping. Consequent ly, as is shown in Figure 8, the material of the contact tangs 27 can be corrugated in the region of the plug connection, thus provid ing the required total thickness. This con struction of the contact tang may also be used in the embodiment of Figures 1 to 6.

Of course, the contact surface is reduced by this construction. Another solution would be that of doubling the material by bending it in the connection and/or fixing region, this having been proved to be very advan tageous.

It will also be seen that an extremely compact and versatile switch is provided which is simple to manufacture and install.

In particular, the switch in accordance with the invention can have a very small overall height which, of course, always has to be calculated with the inclusion of the connec tions. Alternatively, the connections may be structurally combined at the back to form a cable which is guided away. Thus, by joining together the housing portions 12,13 and 54, the contact members are fixed in a clamped manner and at the same time extend out wardly through the switch at this location and carry the plug connections or other connections. By virtue of the spigots pro vided at this location. fixing in the longitu dinal direction of the contacts is effected. A minimum of components are required, this being contributed to by the fact that a switching cam. which comprises a simple small member made from plastics material, at the same time actuates six contact blades located in two planes which are spaced apart by only a small axial distance. By virtue of the arrangement staggered through 90 , not only is it possible to manufacture the switch with only a single standardized housing portion, but it is also possible to space the connections apart to an extent where they can be readily provided with cables and plug shoes.

WHAT WE CLAIM IS: 1. An electrical switch having a housing which comprises at least two housing portions, each of which has a base with a central opening therein, through which passes a rotary switch spindle, and lateral walls at least one of which has a castellated edge such that the two housing portions fit together with projections of the castellated edge of one housing portion engaged in mating recesses of the complementary castellated edge of the outer housing portion, the switch also having contact blades and counter-contacts which are located in recesses of one castellated edge and are engaged by mating projections of the complementary castellated edge and which extend into the switch cavity defined by the two housing portions, the contact blades being deflectable in the axial direction of the switching spindle and the latter carrying a cam plate also located in the switch cavity, which cam plate has thereon cam surfaces defined by axial projections and/or axial recesses for the purpose of actuating the contact blade.

2. A switch as claimed in claim 1, wherein the housing portions have spigots in the region of the bottoms of the depressions and/or at the end faces of the projections and, if required, depressions c-operating therewith, and the contact blades and counter-contacts have openings through which the spigots project.

3. A switch as claimed in claim 1 or 2, wherein the fixing of the contact blades and counter-contacts is effected by a clamping action produced when assembling the housing portions.

4. A switch as claimed in any preceding claim, wherein several contact blades are arranged in a radial plane of the switch spindle and their actuating points. with which the switch cam surfaces co-operate, are offset radially relative to one another with respect to the cam plate.

5. A switch as claimed in claim 4, wherein three contact blades are provided in said radial plane.

6. A switch as claimed in claim 5.

wherein the central contact blade is formed to pass round one side of the switch spindle.

7. A switch as claimed in any preceding claim. wherein two contact blades and counter-contacts are located in two axially spaced planes within the housing portions and are in each case arranged substantially

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. ing portions. It nevertheless includes a total of four switch cavities each having six contact paths. Alternatively, however, it is possible to construct high switch columns, having a large number of contact paths, without the double-rimmed lateral-walled housing portions 54 by assembling a plurality of switches, of the construction of Figures 1 to 4, with their bases 14 abutting one against the other (wherein, of course, only one detent star wheel is in this case provided at the end). This latter solution has the advantage that only a single type of construction of the housing portion is required for all the switches, so that a genuine module composed system is provided having only one basic module. Figure 7 also shows that the castellation does not necessarily have to be uniform. On the contrary, the offset required in the case of the central contact can also be taken into account in the castellation, so that the bend 38 does not need to be so pronounced. A very simple construction of the contact members ensues when the plug tangs 27 are made from the same material as the spring blades 30. In this case, the material of the plug tangs would, of course, normally be too thin to effect proper clamping. Consequent ly, as is shown in Figure 8, the material of the contact tangs 27 can be corrugated in the region of the plug connection, thus provid ing the required total thickness. This con struction of the contact tang may also be used in the embodiment of Figures 1 to 6. Of course, the contact surface is reduced by this construction. Another solution would be that of doubling the material by bending it in the connection and/or fixing region, this having been proved to be very advan tageous. It will also be seen that an extremely compact and versatile switch is provided which is simple to manufacture and install. In particular, the switch in accordance with the invention can have a very small overall height which, of course, always has to be calculated with the inclusion of the connec tions. Alternatively, the connections may be structurally combined at the back to form a cable which is guided away. Thus, by joining together the housing portions 12,13 and 54, the contact members are fixed in a clamped manner and at the same time extend out wardly through the switch at this location and carry the plug connections or other connections. By virtue of the spigots pro vided at this location. fixing in the longitu dinal direction of the contacts is effected. A minimum of components are required, this being contributed to by the fact that a switching cam. which comprises a simple small member made from plastics material, at the same time actuates six contact blades located in two planes which are spaced apart by only a small axial distance. By virtue of the arrangement staggered through 90 , not only is it possible to manufacture the switch with only a single standardized housing portion, but it is also possible to space the connections apart to an extent where they can be readily provided with cables and plug shoes. WHAT WE CLAIM IS:

1. An electrical switch having a housing which comprises at least two housing portions, each of which has a base with a central opening therein, through which passes a rotary switch spindle, and lateral walls at least one of which has a castellated edge such that the two housing portions fit together with projections of the castellated edge of one housing portion engaged in mating recesses of the complementary castellated edge of the outer housing portion, the switch also having contact blades and counter-contacts which are located in recesses of one castellated edge and are engaged by mating projections of the complementary castellated edge and which extend into the switch cavity defined by the two housing portions, the contact blades being deflectable in the axial direction of the switching spindle and the latter carrying a cam plate also located in the switch cavity, which cam plate has thereon cam surfaces defined by axial projections and/or axial recesses for the purpose of actuating the contact blade.

2. A switch as claimed in claim 1, wherein the housing portions have spigots in the region of the bottoms of the depressions and/or at the end faces of the projections and, if required, depressions có-operating therewith, and the contact blades and counter-contacts have openings through which the spigots project.

6. A switch as claimed in claim 5.

at right angles to one another.

8. A switch as claimed in claim 4, 5 or 6 or in claim 7 when dependent on claim 4,5 or 6, wherein sets of contact blades and counter-contacts are employed in different radial planes and the contact blades and counter-contacts in any one radial plane are fixed between the bottom of a recess in a castellated edge on one housing portion and the end faces of the projections on the complementary castellated edge of the other housing portion, while the contact blades and counter-contacts in an adjacent plane are fixed between the bottom of the recess in a castellated edge of the other housing portion and the end faces of the projections on the complementary castellated edge of the first housing portion.

9. A switch as claimed in any preceding claim, wherein switch cam surfaces are provided on each face of the cam plate to co-operate with respective contact blades.

10. A switch as claimed in any preceding claim, wherein the contact blades and counter-contacts between the bottoms of the recesses and the end faces of the projections extend through to the outside of the housing where they have plug connection tangs.

11. A switch as claimed in claim 10, wherein the plug connection tangs are angled to slope in the axial direction away from the operating end of the switching spindle.

12. A switch as claimed in claim 10 or 11, wherein the contact blades have, in the region in which they are fixed between the bottom of the recess and the end faces of the projections, a junction between a thinner spring blade and a thicker material for the plug connection tang.

13. A switch as claimed in claim 10 or 11, wherein the contact blades and their plug connection tangs are made from a common strip of flat material which is deformed in a corrugated manner in the region of the plug connection tangs.

14. A switch as claimed in any of claims 1 to 11 or in claim 13, wherein the countercontacts and/or the contact blades have, in the region in which they are fixed, a bend promoting the clamping action.

15. A switch as claimed in claim 10 or 11, wherein the contact blades and their plug connection tangs are made from a common strip of flat material which is doubled in the connection and, if required, in the fastening region, by bending of the material.

16. A switch as claimed in any preceding claim, wherein several groups of housing portions, each containing a switching cam, are assembled one behind the other in the axial direction of the switch spindle to form a multiple switch array.

17. A switch as claimed in any preceding claim wherein the housing portions have the shape of a box, open at one side, having high and low lateral walls which surround a central recess of the box and each of said lateral walls having a castellated edge defining projections and recesses.

18. A switch as claimed in claim 16, wherein the switch includes housing portions having a face wall transverse tb the switch spindle and high and low lateral walls towards each axial side of said base wall, which lateral walls each have a castellated edge defining projections and recesses.

19. An electrical switch constructed substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.