GB1582784A - Push-button electric switch for opening electric circuits - Google Patents

Abstract

The push-button switch (1) has a contact bridge (16) which, in the closed position, lies against current-carrying contacts (4, 5) and which can be adjusted by means of a button (15) inserted in a housing (11) so that it can be displaced against spring force. One or more intermediate components (22) which can be actuated by the button (15) are disposed between the latter and the contact bridge (16), by means of which components the adjustment movement of the button (15) can be deflected in such a way that the contact bridge (16) can be adjusted fully or partially against the adjustment movement (A) of the button (15) towards the latter. The intermediate component may comprise one or two rectangular levers (22) lying diametrically opposite one another, pivotably mounted in the housing (11) of the push-button switch (1), whose one end (23) interacts with projections (30) of the button and whose other end (24) interacts with the contact bridge (16). As a result of the deflection of the adjustment movement of the button (15), the contact bridge is lifted off the contacts (4, 5). This ensures high operational reliability, in particular constant perfect contact making in a small structure. <IMAGE>

Description

(S4) PUSH-BUTTON ELECTRIC SWITCH FOR OPENING ELECTRIC CIRCUITS (71) We, RAFI GmbH & Co., ELEK TROTECHNISCHE SPEZIALFABRIK, of 128-134 Ravensburger Strasse, 7981 Berg bei Ravensburg, Federal Republic of Germany, a German Kommanditgesellschaft, 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:- This invention relates to a push-button electric switch for opening electric circuits, of the kind having a contact bridge which, in the closed position, is in contact with currentbearing contacts and which is actuated by means of a push-button slidably mounted in a casing for movement in opposition to a spring force.

In previously known push-button switches of this kind, a contact angle piece is fitted at the respective contacts inside the casing, projecting in each case in the direction of the push-button, the ends of which contact angle piece are connected conductively by the contact bridge. In this arrangement, on depression of the push-button the contact bridge.

is pushed away from the contacts in the same direction as the button is depressed to open the circuit.

In accordance with existing regulations, however, a specified clearance must be maintained with these push-button devices between the contact bridge and the perpendicular sides of the contact angle piece and also, when the contact is pressed down, between it and the contact surfaces of the contact angle piece, and so a relatively large amount of space is needed with this construction. Consequently, owing to the requisite clearances between the current-carrying parts, this construction is impracticable where the internal diameters of the casing are rather small. Moreover, in this arrangement the contact angle pieces are clamped on to the casing which is made from plastics material. Since plastics material shrinks in the course of time, high contact resistances and damaged contacts may result.

It is accordingly the aim of the invention to provide a push-button switch for opening electric circuits of the kind hereinbefore mentioned which does not suffer from these disadvantages. Furthermore the invention aims to make it possible, even with the smallest amount of constructional space, for the necessary clearances to be maintained between the contact bridge and the contact when the push-button switch is depressed and that, above all, good contact is made even if the connections are loosely in position. In addition, the construction is of a simple design, thus permitting low production costs.

To this end, the present invention consists in a push-button switch for opening electric circuits of the kind hereinbefore set forth, wherein at least one intermediate member is pivotally mounted on a fixed pivot between the contact bridge and the push-button and is actuated by the latter, by means of which intermediate member the direction of movement of the contact bridge relative to the push-button to open the circuit is reversed, so that the contact bridge is actuated in opposition to the movement of the push-button wholly or partially towards the latter.

The intermediate member acting on the contact bridge is advantageously formed from one or two bell-crank levers situated diametrically opposite one another and mounted in the casing of the push-button switch so as to swivel about an axis running perpendicularly to the adjusting movement of the pushbutton, said levers co-operating by one end with the push-button and by the other end with the contact bridge. It is convenient, here, if the contact bridge is in the form of a Z, on the outwardly projecting arms of which the bell-crank levers act in opposition to the force of a spring and in opposition to the direction of movement of the push-button.

In another embodiment, the intermediate member may consist of a forked or angular lever which is mounted in the casing so as to swivel about an axis running perpendicularly to the direction of movement of the push-button a connecting arm of which, or an inwardly cranked arm of which engages under the plate shaped contact bridge.

It is moreover convenient to mount the levers constituting the intermediate members in dished recesses in the casing, in each case by means of an outwardly directed collar or boss which is moulded on to them and is preferably offset, so that said levers are capable of swivelling. Moreover the push-button should be rotationally fast in the casing, for example it could be held by means of moulded-on flanges guided in grooves in the casing, and the push-button should have projections acting on the ends of the levers constituting the intermediate members. The spring acting on the contact bridge may be constructed as a compression spring which is disposed concentrically, braced on the push-button, or as a tension spring supported on the casing.

A push-button switch for opening electric circuits, constructed according to the invention, is characterised not only by its simplicity of construction which makes its manufacture economic, but mainly by its great operational dependability. For example, as the movement of the contact bridge relative to the push-button is reversed by means of the intermediate members disposed between it and the contact bridge, the latter is lifted off the contacts by the depression of the pushbutton so that contact angle pieces are no longer needed. Thus there is no need to maintain a lateral clearance with respect to current-carrying components and indeed the contact bridge can be carried directly in the casing of the push-button switch and so it is possible to produce designs for constructions having very small diameters and heights.

Furthermore, by the reversal of the movement by means of the intermediate members it is possible to maintain the required clearances between the contact bridge and the contacts without any difficulty.

Furthermore, with the construction according to the invention it is no longer necessary to clamp components in plastics material.

Thus the contacts can be fixed very simply in the casing by interlacing. Even if the live connecting components should be loose there is nevertheless a satisfactory making of contact since the contact bridge is pressed against them by spring force. Thus the pushbutton switch according to the invention fulfils all the relevant regulations and can be manufactured cheaply and fitted easily, so that its wide and economic application is ensured.

In order that the invention may be more readily understood, reference is made to the accompanying drawings which illustrate diagrammatically and by way of example two embodiments thereof and in which: Figure 1 is an axial section of a pushbutton switch with two bell-crank levers as intermediate members; Figure 2 is a cross-section taken on the line II-II of Fig. 1; Figure 3 is an axial section of another embodiment of push-button switch; and Figure 4 is a cross-section taken on the line IV-IV of Fig. 3.

The push-button switch 1 shown in the drawings is used for opening an electric circuit the live leads of which are connected to contacts 4 and 5 of the switch. The pushbutton switch 1 is mounted in a hole 3 in a plate 2.

As shown in Figure 1, the push-button switch 1 consists essentially of a sleeve-type casing 11, on the outer surface of which a screw thread 12 is cut, and a push-button 15 which is slidably inserted in the casing and by means of which a contact bridge 16 can be actuated which establishes the electrically conducting connection between the contacts 4 and 5. The push-button switch 1 is held in the plate 2 by means of a collar 13 and a threaded ring 14 which can be screwed on to the casing 11.

In the construction of Fig. 1, the contact bridge 16 is constructed substantially in the form of a Z. Its middle portion 19 is acted upon by a compression spring 17 which is guided by means of a cam 27, formed on the middle portion and in a recess 18 in the pushbutton 15 on which components it is stressed.

The outwardly projecting arms 20 and 21 of the contact bridge 16 co-operate respectively with bell-crank levers 22, as the intermediate members under the influence of the pushbutton 15, which levers are disposed diametrically relative to one another and are held in the casing 11 so as to be capable of rocking. In addition the levers 22 are each provided with a shouldered extension 25 which is mounted in a dished recess 26 moulded into the casing 11.

One end 23 of eaach of the levers 22 respectively co-operated with projections 30 attached to the push-button 15 which is guided, non-rotationally, by means of flange 28 engaging in a groove 29 in the casing 11, while the other ends 24 of the levers 22 engage respectively under the outwardly extending arms 20 and 21 of the contact bridge, so that the movement initiated by way of the ends 23 is reversed.

If the push-button 15 is pressed down in the direction A, the projections 30 come into contact with the ends 23 of the levers 22 after first overcoming a dead motion. If the adjustning movement of the push-button 15 is continued further the levers 22 are swung by the projections 30 round the axes of the extensions 25 and by means of their ends 24 the contact bridge 16 is lifted off the contacts 4 and 5 so that the circuit is broken. In this way the adjusting movement of the contact bridge 16 is reversed relative to the push button and accordingly the contact bridge 16 is not moved in the same direction as the pushbutton 15 but in the opposite direction, towards the latter. In this way the clearance required to break the circuit can be produced without difficulty between the contacts 4 and 5.

In the construction shown in Figures 3 and 4 a push-button 35 which acts on a contact bridge 36 is again inserted in a casing 31, which is held in the recess 3 of the plate 2 by means of a collar 33 and a threaded ring 34 which can be screwed on to the external thread 32, the push-button being adjustable in the direction A. The push-button can be slid in opposition to the force of a compression spring 37 disposed in a recess 38.

For transmitting the adjusting movement of the push-button 35 to the contact bridge 36, by which the two contacts 4 and 5 are conductively interconnected, the intermediate member in this case is a forked lever 42, on the lever ends of which 43 a projection 47 moulded on the push-button 35 acts and over the connecting arm 44 of which the contact bridge 36 engages. The lever 42 is mounted by means of moulded bilateral extensions 45 so as to be capable of swivelling in dished recesses 46 in the casing 31.

When the push-button 35 is depressed the ends 43 of the lever 42 are moved in the same direction by the projections 47. However, owing to the rotational mounting of the lever 42 in the recesses 46, the connecting arm 44 is lifted in opposition to the adjusting movement A, so that the contact bridge 36 is lifted off the contact 4 by the lever 42 in opposition to the force of a tension spring 41 attached to said contact bridge. Here a recess 39 formed into the contact bridge 36 acts as a bearing, round which the contact bridge 36 is swung up. As soon as the face 40 of the contact bridge 36 has been lifted off the contact 4 by actuation of the push-button 35, the conductive connection between the contacts 4 and 5, and thus the circuit, is broken.

WHAT WE CLAIM IS: 1. A push-button switch for opening electric circuits of the kind hereinbefore set forth, wherein at least one intermediate member is pivotally mounted on a fixed pivot between the contact bridge and the push-button and is actuated by the latter, by means of which intermediate member the direction of movement of the contact bridge relative to the push-button to open the circuit is reversed, so that the contact bridge is actuated in opposition to the movement of the push-button wholly or partially towards the latter.

2. A push-button switch as claimed in claim 1, wherein the intermediate member consists of a bell-crank lever, mounted in the casing for rocking movement about an axis extending normal to the direction of movement of the push-button, one end of said lever cooperating with the push-button and the other end cooperating with the contact bridge.

3. A push-button switch as claimed in claim 2, having two bell-crank levers disposed diametrically opposite one another in the casing.

4. A push-button switch as claimed in claim 2 or 3, wherein the contact bridge is of Z-shaped configuration, the bell-crank lever(s) acting on the outwardly projecting arms of the Z-shaped bridge and against the action of a spring and against the direction of movement of the push-button.

5. A push-button switch as claimed in claim 1, wherein the intermediate member consists of a forked or angular lever which is mounted in the casing for rocking movement about an axis extending normal to said direction of movement of the push-button, a connecting arm of which, or an inwardly cranked arm of which, engages under the contact bridge.

6. A push-button switch as claimed in any of claims 2 to 5, wherein the levers constituting the intermedaite members are each mounted for rocking movement in a dished recess in the casing by means of an outwardly directed collar or boss formed on the lever.

7. A push-button switch as claimed in any of claims 1 to 6, wherein the pushbutton is held rotationally fast in the casing by means of flanges moulded-on which are guided in to the push-button grooves complementary formed or provided in the casing.

8. A push-button switch as claimed in any of claims 2 to 7, wherein the push-button is provided with projections acting on the ends of the levers constituting the intermediate members.

9. A push-button switch as claimed in any of claims 1 to 8, wherein the spring acting on the contact bridge is constructed as a concentrically disposed compression spring braced on the push-button or as a tension spring braced on the casing.

10. A push-button switch for opening electric circuits substantially as hereindescribed with reference to and as shown in Figs. 1 and 2 and Figs. 3 and 4 of'the accompanying drawings.

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

Claims (10)

**WARNING** start of CLMS field may overlap end of DESC **. without difficulty between the contacts 4 and 5. In the construction shown in Figures 3 and 4 a push-button 35 which acts on a contact bridge 36 is again inserted in a casing 31, which is held in the recess 3 of the plate 2 by means of a collar 33 and a threaded ring 34 which can be screwed on to the external thread 32, the push-button being adjustable in the direction A. The push-button can be slid in opposition to the force of a compression spring 37 disposed in a recess 38. For transmitting the adjusting movement of the push-button 35 to the contact bridge 36, by which the two contacts 4 and 5 are conductively interconnected, the intermediate member in this case is a forked lever 42, on the lever ends of which 43 a projection 47 moulded on the push-button 35 acts and over the connecting arm 44 of which the contact bridge 36 engages. The lever 42 is mounted by means of moulded bilateral extensions 45 so as to be capable of swivelling in dished recesses 46 in the casing 31. When the push-button 35 is depressed the ends 43 of the lever 42 are moved in the same direction by the projections 47. However, owing to the rotational mounting of the lever 42 in the recesses 46, the connecting arm 44 is lifted in opposition to the adjusting movement A, so that the contact bridge 36 is lifted off the contact 4 by the lever 42 in opposition to the force of a tension spring 41 attached to said contact bridge. Here a recess 39 formed into the contact bridge 36 acts as a bearing, round which the contact bridge 36 is swung up. As soon as the face 40 of the contact bridge 36 has been lifted off the contact 4 by actuation of the push-button 35, the conductive connection between the contacts 4 and 5, and thus the circuit, is broken. WHAT WE CLAIM IS:

1. A push-button switch for opening electric circuits of the kind hereinbefore set forth, wherein at least one intermediate member is pivotally mounted on a fixed pivot between the contact bridge and the push-button and is actuated by the latter, by means of which intermediate member the direction of movement of the contact bridge relative to the push-button to open the circuit is reversed, so that the contact bridge is actuated in opposition to the movement of the push-button wholly or partially towards the latter.

2. A push-button switch as claimed in claim 1, wherein the intermediate member consists of a bell-crank lever, mounted in the casing for rocking movement about an axis extending normal to the direction of movement of the push-button, one end of said lever cooperating with the push-button and the other end cooperating with the contact bridge.

3. A push-button switch as claimed in claim 2, having two bell-crank levers disposed diametrically opposite one another in the casing.

4. A push-button switch as claimed in claim 2 or 3, wherein the contact bridge is of Z-shaped configuration, the bell-crank lever(s) acting on the outwardly projecting arms of the Z-shaped bridge and against the action of a spring and against the direction of movement of the push-button.

5. A push-button switch as claimed in claim 1, wherein the intermediate member consists of a forked or angular lever which is mounted in the casing for rocking movement about an axis extending normal to said direction of movement of the push-button, a connecting arm of which, or an inwardly cranked arm of which, engages under the contact bridge.

6. A push-button switch as claimed in any of claims 2 to 5, wherein the levers constituting the intermedaite members are each mounted for rocking movement in a dished recess in the casing by means of an outwardly directed collar or boss formed on the lever.

7. A push-button switch as claimed in any of claims 1 to 6, wherein the pushbutton is held rotationally fast in the casing by means of flanges moulded-on which are guided in to the push-button grooves complementary formed or provided in the casing.

8. A push-button switch as claimed in any of claims 2 to 7, wherein the push-button is provided with projections acting on the ends of the levers constituting the intermediate members.

9. A push-button switch as claimed in any of claims 1 to 8, wherein the spring acting on the contact bridge is constructed as a concentrically disposed compression spring braced on the push-button or as a tension spring braced on the casing.

10. A push-button switch for opening electric circuits substantially as hereindescribed with reference to and as shown in Figs. 1 and 2 and Figs. 3 and 4 of'the accompanying drawings.