GB2102203A - Electrical switches - Google Patents

Abstract

A switch comprises a movable contact disk (13) which is resiliently biased against a terminal (8) and against a ridge (11) of the switch body, and which is pivotable about an axis passing through the terminal (8) and ridge (11) into and out of engagement with fixed contacts (9, 10). A pushbutton (16) is provided with two guide rods (20, 21) which pass through two openings (25, 26) in the movable contact (13). Two springs (27, 28) are mounted about the guide rods (20, 21) so as to extend between the inner surface of the pushbutton (15) and the movable contact (13). The two springs (27, 28) are disposed on opposite sides of the pivot axis so that the contact (13) is pivoted when the pushbutton (15) is actuated. A finger (22) is provided on the pushbutton (15) for breaking contact welds. <IMAGE>

Description

SPECIFICATION A pushbutton electric inverter-switch The present invention relates to an electric inverter-switch provided with a cylindrical body defining a coaxial housing in which are to be found: -pushbutton mobile in said housing along the axis thereof between a position of rest provided by a return resilient member applied against said pushbutton and an operative position provided by the pressure exerted on an upper position of the pushbutton, in the vicinity of an upper portion of said body opposed to terminals, on the one hand, - an inverter member adapted to tilt about a pivot permanently connected to a feed terminal and applied either against a rest contact or an operative contact, said contact being connected to a rest terminal and an operative terminal, respectively, through movement transmitting members arranged between said pushbutton and said inverter member, on the other hand.

Such switches are used in particular on control boards or in control boxes and, in view of their number and of the usually small area available, it is imperative to reduce their dimension substantially; moreover, a very simple construction is usually required from such apparatus, both in order to provide same with an excellent reliability and to allow a fast assembly of the elements thereof during manufacture.

Apparatus of the prior art meeting the abovementioned requirements frequently makes use of an inverter contact mounted on a resilient blade, or leaf, requiring a special operation for its assembly with the feed terminal, also called common terminal, said blade being mounted either transversally with respect to the pushbutton direction movement, or in parallel relationship therewith.

In the first instance, the transverse dimensions of the switch casing should be pretty large, whereas, in the second instance, it is necessary to provide rubbing surfaces, the satisfactory cooperation of which makes it necessary to stick to a relatively close manufacturing tolerance.

The object of the present invention is to provide an electric inverter switch exempt from the abovementioned drawbacks and of simple construction, which facilitates its assembly and makes it perfectly reliable.

According to the present invention, the above object is achieved in view of the following features: - the feed terminal, the rest terminal and the operative terminal comprise flat blades, or leaves, parallel to the axis having a first, second and third extremity, respectively, mounted in the housing; in addition, in the plane transverse with respect to said axis, a protruding ridge mounted in said housing is situated between said plane and the body upper portion; - the inverter member is constituted by a conductive disk resiliently resting, first, permanently on said ridge and on said first extremity both situated on a first line and, secondly, either on said second or said third extremity, said second and third extremities being situated on a second line substantially at right angles to the first line, these three extremities and said ridge being in register with the disk periphery, and said return resilient member comprises two compression springs parallel to said axis, said springs being mounted between an inner upper portion of the pushbutton and two resting points for the disk on both sides of the first line, these arrangements being such that the compression forces transmitted to both springs when the pushbutton is being pushed submits said disk to two torques of opposite directions, said torques providing a resultant torque the direction of which changes between the position of rest and the operative position.

Other features and advantages of the present invention will appear from the following description, being merely given by way of example, with respect to the accompanying drawings, in which: Figs. 1, 2 and 3 are full or partial actual sections of the switch in the rest, intermediate and operative positions, respectively, and, Fig. 4 is a partial view from above of the apparatus, in cross-section along plane RR' at right angles to the axis.

An electric inverter switch visible in particular in Fig. 1 is provided with a hollow cylindrica hody (1), having an axis XX', said body having an upper portion (2) adapted to come into contact with the surface of a wall not shown when a bottom portion (3) of said body is inserted in an opening of said wall.

A generally cylindrical housing (4) coaxial with said body is adapted to receive a feed terminal (5), a rest terminal (6) and an operative terminal (7); said terminals, each of which is fixed to the body bottom portion (3) defining housing (4) and is constituted by a flat blade, or leaf, parallel to axis XX', are provided in said housing a first (8), a second (9) and a third (10) extremity, respectively; these three blades are preferably similar; the three extremities are in the same plane P transverse with respect to the axis, e.g. at right angles to the latter.

A ridge (11) protruding in said housing and turned towards opening (12) of housing (4), is situated between plane P and the opening turned towards the upper portion (2) of the body. A conductive disk (13), the diameter of which is smaller than that of housing (4), is mounted in the latter and is permanently in resilient contact with ridge (11) and with the first extremity (8) by means of members to be specified later on, on the one hand, and in contact with said second (9) or with said third (10) extremity, on the other hand.

Such an alternation, due to the tilting movement of the disk about a line D1 passing through the ridge and through said first extremity, induces the expected electric inversion effect, by means of a resilient effect to be explained hereunder.

Referring to Fig. 4, it is to be noted that a second line D2 passing through second (9), and third (10) extremities, is substantially at right angles to the first line Dl; in the illustrated embodiment, in which the three extremities are in register with the periphery (14) of disk (13) said extremities are regularly spaced by angles substantially equal to 1200.

As can be seen from Fig. 1, a pushbutton (15) is mounted in the housing and is mobile along axis XX' between the rest position, viz the one shown in the figure, and an operative position shown in Fig. 3.

Said pushbutton comprises an upper portion (16), level with the upper portion of the body, a guiding skirt (1 7) sliding in the housing, a hook (18) engaged in a lateral groove (19) of said body, two guiding rods (20, 21) integral with said upper portion and parallel with the axis, and a finger (22), again parallel with said axis but the length of which is smaller than that of said guiding rods.

The length of said rods, the extremities (23, 24) of which are turned towards bottom portion (3) is such that, even when the pushbutton is at its position of rest, said extremities are through two openings (25, 26 respectively) of the disk without coming into contact with said bottom portion, said opening being situated on both sides of line D1 (see also Fig. 4); the disk is preferably obtained by a mere cutting operation.

Finally, two compression springs (27, 28 respectively) are mounted about the guidings rods and are applied on the upper inner surface (29, 29') of the pushbutton, on the one hand, and at two rest points (30, 31 respectively) of the disk, on the other hand, in view of an initial compression giving the latter the position shown in Fig. 1, said initial compression developing the return resilient force required for driving said pushbutton to its position of rest.

It can be seen from Fig. 1 to 4 that said two springs have different lengths and diameters on the one hand, and that the two rest points (30, 31) are at different distances (e1, e2) from straight line Dl. In addition, line D3 passing through the rest points, is substantially at right angles to line D1; in the embodiment described merely by way of example, said straight line D3 passes through axis XX' and in all cases, said line D3 should preferably be situated between line D2 and extremity (8).

Torques C1 and C2, transmitted to the disk as a result of the spring forces (f 1, f2) applied at distances (e1, e2) from the pivoting axis D1, are antagonistic torques, so that the resultant torque C3 transmitted to the inverter disk is equal to the difference between said two torques; since forces f1 and f2 undergo unequai increases while the pushbutton is moving towards its operative position, because of different stiffnesses of the two springs and of the values given to el and e2, the resultant torque can be nil at the position shown in Fig. 2, at which said pushbutton is situated between the rest and the operative positions, and said resultant torque changes it direction immediately after, as the pushbutton is moving on.

When the extremities (23,24) of the rods reach the bottom portion, at the operative position shown in Fig. 3, said resultant torque causes said disk to be resiliently applied against the third extremity (8). When the pushbutton is released, the reverse operations are obtained.

However, should there be a weld between the surface of disk (13) and the second extremity (9), and should the resultant torque be so weak as to be able to induce the rupture of said weld, finger (22) would come into contact with said disk before the rest position of the pushbutton is reached, thus inducing a mechanical, and no longer resilient, separation of the surfaces in contact, at the accidentally maintained position of rest.

The relative arrangement of the just-mentioned parts implies that the pushbutton and the switch body be enabled to rotate with respect to each other about axis XX'; thus a permanent position can be provided by any means ensuring cooperation between the pushbutton and said body, and it can be obtained, e.g. through the engagement of hook (18) in groove (19), thus simultaneously rendering the pushbutton perfectly tight.

Claims (4)

1. A switch comprising a casing defining a housing in which are mounted a so-called "rest" first fixed contact part, a so-called "operative" second fixed contact part, a third fixed inverter contact part provided with a ridge, a mobile contact part applied on two ridges and capable of oscillating about the line passing through the latter ridges between position of rest and an operative position at which said part comes into contact with the "rest" fixed contact or the "operative" contact, respectively, a contact being each on both sides of said line, on the one hand, and a pushbutton mobile along an axis at right angles to said line between the rest position and an active position, said pushbutton being provided with two resilient positions of rest each of which makes use of a spring, the pushing direction of which on said mobile contact is parallel to said axis, said direction passing on both sides of said line so that, at said position of rest, a first spring is applied against said mobile contact part so as to maintain the latter at its position of rest, whereas, at said active position, said second spring is in its turn applied against said mobile contact part so as to cause it to be tilted to the operative position, characterized in that one of said ridges is represented by the extremity of a flat blade, or leaf, parallel to axis XX', constituting said inverter contact fixed part, whereas said other ridge is constituted by an inner protrusion, or boss, in the housing of casing, the inner surface of pushbutton turned towards the contact being provided with two guiding rods parallel to axis XX' about which are mounted two springs respectively, directly applied against said surface and on a flat disk constituting said inverter mobile contact, said guiding rods having extremities respectively, passing through two openings of said disk.

2. A switch according to claim 1, characterized in that said openings are at an equal distance from line D1.

3. A switch according to claims 1 or 2, characterized in that said fixed contacts are on a straight line D2 substantially parallel to a straight line D3 passing through the centres of said openings, the latter straight line D3 passing substantially through the centre of disk between said straight line D2 and the ridge carried by said inverter fixed contact.

4. A switch as claimed in any one of claims 1 to 3 substantially as described herein with reference to the accompanying drawings.