EP0147293B1 - Electrical switching device - Google Patents

Description

The present invention relates to an electrical switching device comprising at least two stationary contact elements constituted by elongated conductive parts, folded to have the general shape of a U and implanted in a printed circuit board so as to be each in electrical contact with a conductive track of the plate, and a movable contact element disposed on translation means displacing, on command, the contact element perpendicular to its length.

The prior documents FR-A-2 461 980, DE-A-2 657 546 and DE-A-2 403 108 describe electrical switching elements comprising stationary contact elements which are elongated conductive parts, folded to have the shape general of a U and located in a printed circuit board, so as to be each in electrical contact with a conductive track carried by the board. In these various documents, the movable contact element moves perpendicular to the plane of the stationary contact elements.

The switching device according to the invention is characterized in that the movable contact element is moved in the plane of the stationary contact elements and in that the translation means comprise a cursor arranged on a slide and carrying the movable contact, stop means being provided to define precise stop positions of the cursor.

Such a type of linear motion multiple switch finds particular application in the field of measuring devices.

According to another characteristic of the invention, the stop means comprise a rack integral with the slide cooperating with a ball pushed by a spring and carried by the slider.

The slide can be a molded part attached to the printed circuit board and comprising at least one imprint ending in perforations, arranged so as to receive one of the stationary contact elements which will pass through the slide to be implanted in said plate.

In one embodiment, each stationary contact element is a section of wire, strip or profile, made at least in part of a conductive metal such as copper or a copper alloy.

Each stationary contact element can be placed on the printed circuit board by an automatic implantation machine for components and soldered like these, for example by wave soldering.

In order to improve the performance of the device, each stationary contact element is coated, at least where the movable contact element comes to rest, with a precious metal such as silver or an alloy of this metal.

According to one embodiment at least two stationary contact elements are arranged side by side and in that the movable contact element is an elastic contact blade which is subdivided into two strips by a partial longitudinal slot, the respective dimensions being such that each strip is supported independently of the other on one of the stationary contact elements.

• - la figure 1, la forme générale d'un élément de contact stationnaire conçu selon la présente invention;
• - la figure 2, un agencement de dispositif de commutation à deux éléments de contact stationnaires côte à côte;
• - la figure 3, un agencement de dispositif de commutation à deux éléments de contact stationnaires dans le prolongement l'un de l'autre;
• - la figure 4, une variante dans laquelle l'élément de contact mobile est un fusible cylindrique;
• - la figure 5, une vue en plan d'un dispositif de commutation conçu selon l'invention;
• - la figure 6, une vue en coupe du curseur du dispositif de commutation de la figure 5 et des pièces avoisinantes.

The various objects and characteristics of the invention will now be detailed in the description which follows, given by way of nonlimiting example, with reference to the appended figures which represent:

• - Figure 1, the general shape of a stationary contact element designed according to the present invention;
• - Figure 2, an arrangement of switching device with two stationary contact elements side by side;
• - Figure 3, an arrangement of switching device with two stationary contact elements in the extension of one another;
• - Figure 4, a variant in which the movable contact element is a cylindrical fuse;
• - Figure 5, a plan view of a switching device designed according to the invention;
• - Figure 6, a sectional view of the cursor of the switching device of Figure 5 and neighboring parts.

Figure 1 shows a stationary contact element 1 designed in accordance with the present invention.

This stationary contact element 1 is a section of copper wire bent to have the general shape of a U and comprising two legs 2 and 3 which pass through a printed circuit board 4, by perforations 5 and 6 made in this plate 2 , and the ends 7 and 8 of which are folded inwards and taken up in drops of solder 9, 10 secured to welding platforms 11, 12.

The stationary contact element is thus mechanically fixed to the plate 4. It is electrically connected to a printed circuit track comprising, for example, the platform 11.

The plate 4 is seen in section to the right of the element 1 and we also see in the figure a support element 13 also seen in section at this location. The surface opposite to the plate 4 of this support element 13 is in fact an open angle formed by slightly inclined ramps 14 and 15. The contact element takes on such a shape, the utility of which will be seen later.

In practice, such a stationary contact element can be easily produced using an automatic component implantation machine provided with the appropriate settings and supplied with wire of appropriate diameter. The machine cuts a section, folds it into a U, presses it against the support element 13 and folds the ends 7 and 8. It is no more and no less than a strap, component that the machine is intended to set up like the other components, and which will later be welded with these in a wave welding machine.

Figures 2, 3 and 4 offer, as an example ple, several modes of construction of a switching device according to the invention.

In the example of Figure 2, two stationary contact elements 16 and 17 similar to that of Figure 1 are arranged side by side. A movable contact element 18, in the form of an elastic blade of conductive metal can be moved in both directions according to arrow 19, that is to say transversely and come to bear on the stationary contact elements 16 , and 17. To facilitate this, this blade is provided with a slot 20 formed from its end on the side of the stationary contact elements and running over their entire length, in order to subdivide it into two strips which are supported respectively on the elements of stationary contact 16 and 17, independently of each other, to a certain extent at least.

In the example of FIG. 3, the stationary contact elements 21 and 22 are arranged in the extension of one another and the movable contact element 23, also movable transversely, comes to rest on them by its two ends.

In these two cases, so that the elastic blade rests on the stationary contact elements, a vertical pressure from top to bottom is exerted on it by means not shown and, as can be seen in the drawings somewhat exaggerated, the blade flexes. In order for this blade to come into best contact with the stationary contact elements, these conform to a ramp (15 in FIG. 1) and are, at the point of contact, over a long length, roughly parallel to the movable contact blade.

FIG. 4 illustrates another embodiment of the invention in which two pairs of stationary contact elements side by side (24, 25; 26, 27) are arranged in the extension of one another. The movable contact element is a cylindrical element internally comprising a fusible wire and the two ends 29 and 30 of which each rest on a pair of stationary contact elements. A fuse circuit breaker is thus produced. Of course means not shown must maintain with sufficient pressure the fuse against its supports.

Figure 5 provides an illustration of an embodiment of the switching device of the invention in which we will find the stationary contact element of Figure 1, the movable contact element of Figures 2 and 3 and even the variant of Figure 4.

Indeed, on a printed circuit board 4 is disposed a molded part 31 serving as a slide and comprising a rack. This part comprises centering pins, not shown, on its face facing the plate 4, and which correspond to holes in this plate, with a view to placing them in precise mutual position. Other pieces can also be used to seal the two pieces together.

This part 31 comprises, along its lower edge (in FIG. 5), a series of locations of stationary contact elements, only one of them being shown at 1. By examining the neighboring location 32, we sees that it comprises an opening 33 through the part 31. Between this opening 33 and the lower edge 34, a hollow imprint forms the ramps 14 and 15 of FIG. 1, at the bottom of a shallow groove, so that the stationary contact element 1 is projecting relative to the main surface of the part 31.

A cursor 35 comprising an operating button 36 carries an elastic blade 23. It moves transversely, sliding on guide surfaces by means of guide wings 37, 38, 39, 40, 41, 42.

In the present example, which corresponds to that of FIG. 3, the elastic blade 23 serving as a movable contact element comes to bear on only one of the stationary contact elements at a time. Its width and the spacing of these elements have been chosen for this purpose. However, when changing position; the blade 23 is wide enough to be still supported by a stationary contact element when it reaches the next, in most cases. When this is not the case, the plate comprises, between the more distant stationary contact elements, a boss 43, 44 which lifts the blade 23 by its stop 45 and then lets it fall back at the level of the contact by its flank 46.

The other end of the blade 23, under the main part of the cursor 35 is not visible. It is intended to rest on other stationary contact elements, but, unlike Figure 3, these are not arranged in the extension of those of the lower edge, which would nevertheless be possible, although too expensive, but perpendicular to them, that is to say parallel to the movement of the cursor. There are, eri effect, in room 31, other openings 47, 48, between which is formed a flat bottom groove 49, 50 narrow and shallow, to receive a stationary contact element of the kind of those of the figure 4. Note that to avoid punctual wear of the blade 23, the elements located in the indentations 49, 50 are arranged in several lines.

The different stop positions that the slider 35 can take are defined by a rack 51 having recesses 52 and projections 53. An elastic member, such as a ball pushed by a spring is provided in the body of the slider 35 for s '' press against the rack 51.

Each of the stationary contact elements, such as that which appears in 1 being welded, through the part 31 to the plate 4 being in electrical conductivity with a conductive track 54, the displacement of the cursor driving the blade 23 selectively brings the electrical circuit associated with one of the lower contact elements such as 1 and that which is associated with one of the upper contact elements such as that which can be installed at 49.

In addition, still with regard to FIG. 5, one can recognize at the right end a fuse 28 (see FIG. 4) carried by elements of stationary contacts located at 24, 25, 26, 27. This fuse is retained in position and pressed against the contacts by an elastic tab 55, coming from molding.

Figure 6 is a partial section along the axis of the cursor 35. It can be recognized therein the plate 4, the part 31, a stationary contact element 1 and a stationary contact element 56 perpendicular to the previous one. The blade 23, simply slid between the wings 41 and 42 (fig. 5) can be retained longitudinally by any means.

We also see the rack 51 against which the ball 57 is pushed by the spring 58 housed in a recess 59 closed by a plug 60. A notch 61 projecting (see also Figure 5) can be used for a visual indication of the position cursor.

It will be noted how the wings 37, 38 and 41, 42 combine with the protruding shapes 62, 63, 64 to retain and guide the cursor on the part 31 which serves as its slide and how the rack 51, perpendicular to the plane of the plate 4 contributes to the rigidity of the assembly.

Claims (10)

1. An electrical switching device comprising at least two fixed contact elements (1) formed by elongated conducting parts bent into the general shape of a «U» and inserted in a printed circuit board (4) so as to be in electrical contact with a conducting track (54) of the printed circuit board, and further comprising a movable contact element (18, 23) arranged at means for translation moving the contact element perpendicularly to its length, characterized in that the movable contact element being displaced in the plan of the fixed contact elements and that the means of translation are comprising a cursor (35) arranged on a slide (31) and bearing the movable contact element, and stop arrangements being provided to define the precise stopping positions of the cursor.

2. A switching device according to Claim 1 characterized in that the stop arrangement comprises a rack (51, 52), integral with the slide, engaging with a spring (58) loaded ball (57) carried by the cursor (35).

3. A switching device according to Claim 1 or Claim 2 characterized in that the slide is a moulded part connected to the printed circuit board and containing at least one groove (49, 50) terminating in openings arranged so as to accept the fixed contact elements that are to be inserted and which will pass through the slide (31) in the board (4).

4. A switching device according to one of the preceeding claims characterized in that the fixed contact element (1) is a piece of wire, strip or profiled section, made, at least partially, of a conduc- five metal such as copper or a copper alloy.

5. A switching device according to one of the preceeding claims characterized in that the fixed contact element (1) is inserted in the printed circuit board by an automatic component insertion machine and soldered by wave soldering, for example, like the other components.

6. A switching device according to one of the preceeding claims, characterized in that the fixed contact element (1) is coated with a precious metal such as silver or an alloy of this metal, at least in the region which will be in contact with the movable contact.

7. A switching device according to one of the preceeding claims, characterized in that two fixed contact elements (16, 17) are positioned side by side, in that a flexible blade (18) is split into two strips by a partial longitudinal slot (20) and in that each strip bears independently of the other on one of the fixed contacts.

8. A switching device according to one of the preceeding claims, characterized in that two fixed contact elements are positioned in line with each other, the length of the blade being such that it is able to bear upon both.

9. A switching device according to Claim 5 or 6, characterized in that at least one of the fixed contact elements is parallel to the direction of motion of the blade (23) and at least one other fixed contact element (56) is arranged in such a manner that the blade (23) comes to bear upon each of them respectively, by its two ends. 10. A switching device according to one of the claims 1 to 6, characterized in that two pairs of side by side, fixed contact elements (24, 25-26,

27) are positioned in line with each other and the movable contact element (28) is a cylindrical fuse wire element, retaining arrangements being provided to press each of its ends against the two elements of the same pair.

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