A switch of this type, as is described, for example, in the US patent 4,758, 724, employs as its operating organ a lever that acts on the rocker arm in such a way as to make it oscillate between one and the other of its two stable positions. Also known are switches in which the organ that operates the rocker arm is a toggle element. In the present description the term switch is intended to designate both a device that opens and closes a single contact and a device that opens one contact and simultaneously closes'another contact, and vice versa (diverter switch).

In some applications, for example in lighting installations for dwellings and offices, there is felt the need for switches operated by a push-button rather than a lever or a toggle element.

The object of the invention is to propose a switch of the rocker-arm type, but operated by a push-button.

This object is attained by realizing the switch defined in general terms in Claim 1.

The invention will be understood more clearly from the following detailed description of three embodiments thereof, which is given by way of example and is not to be considered limitative in any way, the description making reference to the attached drawings, of which, Figure 1 is a side elevation of a first embodiment of the switch in accordance with the invention, Figure 2 is a view from below of the switch of Figure 1 in which some parts are shown as transparencies ; Figures 3a-3d schematically illustrate the switch of Figure 1 in four different operating positions, Figures 4 and 5 show, respectively, a side elevation in section and a perspective view with a part in section of a second embodiment of the switch in accordance with the invention, and Figure 6 shows a side elevation of a third embodiment of the switch in accordance with the invention.

The switch 1, which is shown in Figure 1 with the push-button dismantled, comprises a supporting structure 2 made of insulating material, plastics for example, having the form of a parallelepiped with two pairs of walls, respectively greater 12,13 and smaller 14,15, and a base wall 11. The supporting structure 2 is open,

i. e. it does not have a wall counterposed to the base wall 11. A contact-holder structure 16 made of insulating material is joined to the base wall 11 of the supporting structure 2. The structure 16 contains three connection terminals 21. 1, 21.2 21.3, screw clamps for example, accessible by means of two openings (not shown), one for accessing the screw of the clamp and the other for inserting an electric lead in the clamp. Two of the three connection terminals, 21.1, 21.2, are connected, in the present example as integral portions, to respective sheet-metal tags 24. 1,24. 2 situated within the structure 16 below the base wall 11. Each tag is provided at one of its ends with a fixed electric contact, respectively 3.1, 3.2, that can be accessed from inside the supporting structure 2 by means of a rectangular opening 25 provided in the wall 11. The third connection terminal 21.3 is connected, in the present example as an integral portion, to an L-shaped sheet-metal bar 27 arranged in the structure 16 at right angles to the longer side of the base wall 11 in such a way that its edge 26 emerges from the opening 25 in a central position with respect to the fixed electrical contacts 3.1, 3,2.

A metallic jumper element 4, which has the shape of a rocker arm with a rounded central profile, is arranged

on the inside of the supporting structure 2 in such a manner as to be capable of pivoting around an axis at right angles to the larger walls 12 and. 13. The jumper element 4 has a central seating part 30 in contact (through the opening 25) with the edge 26 of the bar 27 and two arms provided with electric. contacts 5. 1,5. 2 at their ends. The seating part 30 extends, transversely with respect to the arms, to form two metallic distance pieces 37 that are inserted between two pairs of counterforts 38 integral with the structure 16. The counterforts 38 only permit the jumper element 4 to perform an oscillatory motion about. the edge 26, but not a translatory motion.

A control element 47 is formed by a small block 6 made of insulating material and a spring-controlled pin 7. The small block 6 is mounted inside the supporting structure 2 in such a way as to be capable of pivoting around an axis a2 parallel to the axis of rotation of the jumper element 4. More particularly, on the walls 12,13 there are situated two opposite holes 33 that accommodate two opposite prominences 32 on the block 6 of the control element 47. The pin 7 has a rounded tip and is pushed by a spring (not visible in the figure) that is compressed in a cavity of the block 6 to constitute an elastic connection between the block 6 and

the metallic jumper element 4 below it. The upper part of the block 6 is designed in such a way as to have a cavity with surfaces 36 that are shaped substantially as steps and are symmetrical with respect to a plane containing the axis of rotation a2.

The supporting structure 2 is closed at the top by an operating organ 46 that is connected to the control element 47 and comprises a push-button 42 made of insulating material. In particular, the push-button 42 consists of a rectangular plate 9 and four coupling elements 45 that are integral with the plate. The elements 45 are formed by elastic. tongues 40 projecting at right angles from the plate 9 near the ends of its larger sides and guide teeth 41 projecting from the ends of the tongues. The operating organ 46 also comprises a pressure-transmission means 8, which has two ends 44 and a flat surface that faces the lower surface of the plate and is fixed below the plate 9 in such a way as to be capable of pivoting around a third axis a3 parallel to the two axes al and a2. Two foil springs 22 and 10 are arranged between the plate 9 and the pressure- transmission means 8 in such a way as to maintain the latter in a rest position in which its two ends 44 are at the same distance from the plate 9, and to maintain the plate 9 away from the supporting structure 2 when

the push-button is in its rest position. To fix the push-button 42 to the supporting structure 2, the teeth 41 are inserted into openings 43 in the larger walls 12 and 13 of the supporting structure 2 to form a tongue and groove joint. The openings 43 permit the teeth 41 to slide inside them and therefore a guided displacement of the push-button 42. The pressure-transmission means 8, the control element 47 and the jumper element 4 are each symmetrical with respect to a plane passing through their respective axes of rotation.

In an embodiment of the present invention the switch 1 is a modular electrical device having the function of a two-way switch, utilizable, for example, for switching the lines of domestic installations. For mounting purposes, the device is fixed to a supporting frame (not shown), usually with joint-type couplings. To this end prominences 17 are provided on the walls 14,15 of the container 2 and are shaped in such a way as to fit into complementary rebates of the frame.

Prior to every switching of the switch, the push- button 42 is in its rest position at a certain distance from the supporting structure. The pressure-transmission means 8 is likewise in its rest position, its plane of symmetry coinciding with the plane, indicated by the reference number 28, containing the axes of rotation al,

a2 and a3, due to the elastic action of the foil spring 22, which, in this particular embodiment of the invention, integral with the foil spring 10. At the same time, the block 6 of the control element 47 and the jumper element 4 are inclined in one of their two stable angular positions. For example, as shown in Figure 3a, when the block 6 is inclined towards the left, the jumper element 4 is inclined towards the right and the mobile contact 5.1 is pressed against the fixed contact 3.1. When a pressure greater than the elastic resistance of the spring 10 is applied to the plate 9, the operating organ 46 undergoes a downward displacement, the teeth 41 slide in their respective openings 43 and the right-hand end 44 of the pressure-transmission means 8 comes to bear against one of the step surfaces 36 of the block 6 and thus transfers to it the pressure applied to the plate 9. In particular, as shown in Figure 3b, the end 44 comes to bear against the bottom of the right-hand step surface 36, thus causing the block 6 to commence a rotation in the clockwise direction and the pressure-transmission means to rotate in the counter-clockwise direction; subsequently it will come into contact with the side of the step, thus transferring in a transverse direction the pressure applied vertically to the plate 9. As shown in Figure

3c, the transverse thrust causes the block 6 to rotate even further in the clockwise direction around its axis of rotation a2, until it eventually snaps it into its second stable position (Figure 3d) in which it is inclined towards the right. During the movement of the block 6, the pin 7 slides on the jumper element 4 from one end of the rounded profile to the other, causing the jumper element to rotate about its axis al, that is to say, around the edge 26 of the L-shaped bar 27, until it eventually snaps it into its left-hand stable position, in which the mobile contact 5.2 is pressed against the fixed contact 3.2. When the external pressure action terminates, the spring 10 brings the push-button 42 elastically back into its rest position, the pressure- transmission means 8 reacquires its rest position, while the block 6 and the jumper element 4 remain in the new positions they have assumed.

Since the various moving parts are symmetrical with respect to the plane 28, a further pressure applied to the plate 9 will bring both the block 6 of the control element 47 and the jumper element 4 into the positions they occupied prior to the first switching, i. e. with the block 6 inclined towards the left and the jumper element 4 inclined towards the right as shown in Figure 3a.

The second embodiment shown in Figures 4 and 5, in which equal or equivalent parts are indicated by the same reference numbers used for the first embodiment, differs from the first embodiment only on account of. some details. More particularly, the elastic element that maintains the pressure-transmission means 8 in position is constituted by two counterposed lamellae 22' that are symmetrical with respect to the plane of symmetry 28 and form an integral part of a structural element of the push button 46. According to a variant not shown in the figures, the elastic element is constituted by two counterposed foils forming an integral part of the pressure-transmission means 8 that rest with their ends against the internal surface of the push-button 46. The elastic element that maintains the push-button in its rest position is constituted by two helicoidal compression springs 10'and the coupling elements between the push-button 46 and the supporting structure 2 are constituted by small cylindrical columns 40'integral with the push-button 46 and corresponding cylindrical seatings 43'provided in the supporting structure 2.

The third embodiment, shown schematically in Figure 6, consists of the switch of Figure 1 modified in such a way as to permit its being used as a traditional push-

button, that is to say, as a switch with contacts that are normally open and are closed only while the operating organ is actually operated. To this end the switch comprises a compression spring 5. 0-arranged between the control element 47 and the base wall 11 of the supporting structure 2. When a pressure is applied to the push-button such as to'cause the closure of the right hand contact (as seen on the drawing), the spring 50 becomes compressed. As soon as the pressure is removed from the push-button, the spring 50 causes the control element 47 to rotate in the clockwise direction, thus causing the permanent opening of the right-hand contact. Clearly, the same structure. can. be used as a push-button switch with contacts that are normally closed by utilizing the left-hand contact, or applying the spring 50 on the right-hand side of the control element 47 rather than the left-hand side.

What has been explained above makes it clear that the switch described herein can be employed both as a one-way switch and as a diverter switch, i. e. as a two- way switch, and, with the sole addition of an elastic means, like the spring 50, that keeps a mobile contact (5.1) and a fixed contact (3.1) apart from each other, also as a traditional push-button.

Although only three embodiments of the present invention have here been illustrated and described, it is obvious that numerous variant and modifications are possible without overstepping the underlying inventive concept.