Electrical Device, in Particular Steering Column Switch for Automotive Vehicles

The present invention relates to an electrical device, in particular, a steering column switch for automotive vehicles.

Electrical devices, in particular steering column switches for automotive vehicles with a punched plate embedded in a plastic plate are disclosed in DE-OS 35 15 911 or DE-OS 37 17 743, for example. The punched plate which is fitted to the steering column switch is arranged in a plastic plate. The conductive contact elements of the punched plate are punched out such that they are still interconnected by small webs. In this condition, the punched plate is inserted into an injection mold, is cast in plastics and removed again from the injection mold. The webs interconnecting the single conductive contact elements are cut subsequently. The cutting operation can be performed prior to or after the insertion of the resulting plastic plate into the steering column switch. It is disadvantageous in this embodiment of the plate that those points where the individual conductive contact elements are isolated from each other, or the webs are cut, are open to the outside. Dust, small particles or even large particles or liquids may enter the electrical device at these points. These contaminants will frequently impair the function of the entire switch which is a shortcoming.

The object of the present invention is to improve upon the generic electrical device to such effect that the function is not impaired by contaminants collecting in the punched plate or the plastic housing.

This object is achieved by an electrical device, in particular, a steering column switch for automotive vehicles having a punched plate with at least two conductive contact elements embedded into a plastic plate. The conductive contact elements of the punched-out punched plate are still interconnected and the connection of the conductive contact elements is effected by a U-shaped tab, which, prior to the embedding operation, is open towards the conductive contact elements and is disposed roughly parallel to them, and which includes two legs and a transverse web, from which tab after embedding the punched plate into the plastics material of the plastic plate at least the transverse web is cut.

Providing the punched plate such that the connection of the conductive contact elements is effected by U-shaped tabs which are disposed roughly perpendicular to these, from which tabs, after the embedding into the plastics material of the plastic plate, at least the transverse web is cut off, results in that the plastic plate has no more holes through which contaminants can enter into the device. However, the stability of the punched plate is ensured nevertheless by these transverse links between the individual conductive contact elements prior to the embedding operation. Due to the connection between the conductive contact elements being provided by a U-shaped tab, the punching operation is not much more complicated than in a web-type connection. First, the tab is punched out in one plane with the conductive contact elements. Subsequently, it is bent to assume a position where it stands roughly perpendicular to the conductive contact elements. After the embedding operation, the part of the tab which projects from the surface of the plastic plate and is embedded in the plastics, preferably, is cut from the surface of the plate, being flush therewith. This way, the dimensions of the entire plastic plate are not increased.

According to a favorable embodiment, the U-shaped tab includes two parallel legs which are bent roughly perpendicularly from the conductive contact elements and are connected with these, and which are interconnected by a transverse web at their ends not connected to the conductive contact elements. This embodiment results in that, first of all, the punching operation of such a connection between two conductive contact elements is simple and, secondly, the stability of the entire punched plate is enhanced by the transverse-web connection of the two U-legs. Further, it is achieved by filling the space between the parallel legs of the U-shaped tab during the embedding operation with the plastics material that, on cutting the embedded part of the tab which projects from the surface of the plastic plate, the conductive contact elements are isolated from one another, although there is no hole in the entire plastic plate.

The present invention is explained in more detail by way of two embodiments with reference to the accompanying drawings. In the drawings:

FIG. 1 is a punched plate which is not embedded;

FIG. 2 is a view in the direction of the arrow Z in FIG. 1;

FIG. 3 is a view of an U-shaped tab according to FIG. 1 in the punched-out condition, not yet angled off;

FIG. 4 is a view of an U-shaped tab of a second embodiment in the punched-out condition, not yet angled off;

FIG. 5 is a cross-section taken through the embedded area of the U-shaped tab according to FIG. 2; and

FIG. 6 is an illustration according to FIG. 5, however, with the U-shaped tab cut from the plastic housing.

The punched plate according to FIGS. 1 to 3 includes conductive contact elements 1, 2, 3 and 4. The connection between the conductive contact elements 1 and 2 is provided by the U-shaped tab 5, while the connection between the conductive contact elements 4 and 1 is provided by the U-shaped tab 6, and the connection between the conductive contact elements 2 and 3 is provided by the U-shaped tab 7. In the illustrations according to FIGS. 1 and 2, the U-shaped tabs 5, 6, 7 after the punching operation are already angled off from the conductive contact elements 1, 2, 3, 4, approximately perpendicular to them. Each of the U-shaped tabs 5, 6 and 7 comprises two legs 8 and 9 extending parallel to one another, each of them at one end being connected with a lateral edge of a conductive contact element. At the other end, the legs 8 and 9 are interconnected by a transverse web 10 to a U-shaped configuration. The lateral edge of the one conductive contact elements, from which the one leg starts, is disposed on one line with the lateral edge of the conductive contact element, from which the other leg starts. As a result, the two legs 8 and 9 of each tab 5, 6 and 7 lie on the same side of the two interconnected conductive contact elements. Further, the transverse web 10 extends in parallel to the two lateral edges. As can be seen in FIGS. 1 and 2, the legs 8 and 9 of the tabs 5, 6 and 7 erect by following around a bending edge which is in parallel to the two lateral edges on which they are seated, the bending edge being arranged directly at the lateral edges.

In FIG. 4, the shape of the tab of the second embodiment after the punching operation is illustrated schematically. The U-shaped tab 25 interconnects the conductive contact elements 1 and 2 at two opposed lateral edges, in between which it is disposed. The tab comprises two legs 8, 9 which extend in parallel to each other and in parallel to the conductive contact elements 1, 2 and are connected with lateral edges of the conductive contact elements 1 and 2. At their other ends, which are not connected with the conductive contact elements 1, 2, the legs 8, 9 are interconnected by a transverse web 10, which extends perpendicular to the two lateral edges. The legs 8, 9 of the U-shaped tab 25 are connected with the conductive contact elements 1, 2 through projections 11, 12, which are opposite to each other and from which the legs 8 and 9 erect by following around a bending edge which extends perpendicular to the two opposed lateral edges of the conductive contact elements 1 and 2. After the bending operation of the U-shaped tab 25, that means after the tab has been caused to adopt a roughly perpendicular position to the conductive contact elements's plane, the open end of the U-shaped tab 25 faces the conductive contact elements 1, 2. The punched plate is inserted into a mold in this condition, and plastic is injected into the mold.

FIG. 5 illustrated the condition after the injection molding operation. The conductive contact elements 1, 2 are embedded in the plastics material 13. The tab 25, too, is embedded in the plastic material 13. More particularly, the plastic material is in the space 15 between the legs 8, 9. In the next step of the manufacturing process, the part 14 which projects from the surface of the plastic plate and in which also part of the U-shaped tab 25 is embedded, is cut from the plastic plate. Such a cutting operation can be effected by milling, for instance. As can be clearly seen in FIG. 6, the conductive contact elements 1 and 2 also are isolated from each other. The plastic disposed in the space 15 isolates the two conductive contact elements 1, 2 from one another and, additionally, establishes a connection to the surface of the plastic plate. Thus, the plate does not contain any holes or recesses, it is leak-proof and has a smooth unbroken surface.