EP1294001A2

EP1294001A2 - Device for actuating an electrical double snap-action switch

Info

Publication number: EP1294001A2
Application number: EP02019977A
Authority: EP
Inventors: Marco Barile; Paolo Ballatore
Original assignee: Bitron SpA
Current assignee: Bitron SpA
Priority date: 2001-09-14
Filing date: 2002-09-05
Publication date: 2003-03-19
Anticipated expiration: 2022-09-05
Also published as: ES2527689T3; BRPI0203968B1; EP1294001A3; EP1294001B1; BR0203968A; ITTO20010877A0; ITTO20010877A1; MXPA02008955A

Abstract

Described herein is a device for actuating a double snap-action switch for controlling electrical apparatus of a motor vehicle, said device comprising a pushbutton and a container body, in which there move at least two mobile contacts designed to perform a travel to reach either of two positions of arrest with closing of first and second fixed contacts of a printed circuit, said mobile contacts being moved by an elastic-snap-action element on which there acts a pair of rigid bars each controlled by a pair of prods that act on them in a misaligned way, said prods and said rigid bars being made of a single piece out of plastic material and with a hinge designed to enable conversion of the rectilinear movement of thrust on the prod into a movement of rotation and translation of the bar.

Description

The present invention relates to an electrical double snap-action switch, for example for controlling car-window regulators or else other facilities present on a motor vehicle, and more particularly the invention relates to the device for actuating said switch.
Current double snap-action switches, are made up of an actuating push-button, which also has an aesthetic function and is fitted on a supporting body by means of a hinge connection, which enables its relative movement of rocking. The rocking motion of the push-button is converted into linear motion by the actuating system, which comprises two pointed elements (hereinafter referred to as prods) that act on a rigid bar, which in turn impinges upon a pair of snap-action elements, also referred to as "bubbles", made of silicone rubber. The hinge connection between the prods and the rigid bar enables a motion of rotation and translation of the aforesaid bar. Said motion is governed by the collapse of the silicone rubber bubbles, which occurs in succession as a consequence of the fact that the point of contact between the prod and the rigid bar is not equidistant from the points of application of the reactions of the bubbles on said bar.
Embedded within the silicone, in pre-defined points, are particles of electrically conductive material which enable, once the bubble has "snapped", closing of the contacts of the underlying printed circuit.
The switch according to the prior art has, however, constructional features which increase the costs involved, both on account of a larger number of assembly operations, and on account of delicate and hence very costly machining processes. In greater detail, the prod and the rigid bar are two pieces that are produced separately and subsequently assembled on the body of the switch with two distinct operations, which could be reduced to just one if the two pieces were produced as a single body.
The purpose of the present invention is to provide an actuating system for a snap-action switch, which is inexpensive and which will overcome the drawbacks mentioned above.
The aforesaid and other purposes and advantages are achieved by an actuating system for a snap-action switch for controlling electrical devices of a motor vehicle, comprising a push-button and a container body in which there move at least two mobile contacts designed to perform a travel to reach either a first position of arrest, with closing of a first part of fixed contacts of a printed circuit, or a second position of arrest, with closing of a second part of fixed contacts of said printed circuit, said mobile contacts being moved by an elastic snap-action element made of silicone material, on which there acts a pair of rigid bars, each controlled by a prod, which pushes on them in a misaligned way, so causing the snapping in succession of the part of the elastic-snap-action element underlying the ends of said bars, with consequent closing of said fixed contacts. The said actuating system is characterized in that said prods and said rigid bars are made of a single piece of plastic material and with a hinge designed to enable conversion of the rectilinear movement of thrust exerted on the prod into a movement of rotation and translation of the bar.
There now follows a description of the structural and functional characteristics of a preferred, but nonlimiting, embodiment of the switch according to the invention, with reference to the attached drawings, in which:

Figure 1 is a side elevation of a switch according to the invention;
Figure 2 is an exploded view of the switch of Figure 1;
Figures 3 and 4 are front views of two different embodiments of a detail of the switch of Figure 1;
Figures 5a, 5b and 5c are partially cross-sectional views of the mechanism of the switch of Figure 1 in its three operating positions.

With reference to the figures, number 1 designates as a whole the outer body of a switch, for example one for controlling the motors of car-window regulators, formed by a cover or lid 2 and by a base 3, and provided with an oscillating control button 4 connected, in 5, to the lid 2. The body 1 is snap-fixed onto a part of the passenger compartment of a motor vehicle (not illustrated). The push-button 4 is mobile between two positions, for controlling, in the example illustrated, closing or opening of the car windows.
Located on the base 3 of the body of the switch is the printed circuit 7, together with the connectors 8 for its connection to the electrical system. Anchored on the printed circuit, which is provided with special fixing pins, is a lamina 10 made of an elastic metal material, which is a conductor of current. The lamina has supporting strips 12 in a position such as to be located, when the switch is assembled, at a point corresponding to one of the silicone bubbles 14 made out of a single elastic element 15, referred to as "mat" in the technical terminology of the branch, set in a position overlying said lamina 10. The silicone bubbles have the function of providing the sensation of actuation of the switch. In particular, they follow a non-linear curve of the strength of the bubble versus the travel, the said curve rising up to the point where the bubble reaches an unstable geometrical condition, beyond which there occurs collapse with sudden reduction of the strength and consequent increase in the speed of motion of the system. In this way, the classic snap-action of the switch is obtained. A second function of the silicone bubbles is to provide the compressive strength of the contact elements, in particular the contacts between the lamina 10 and the printed circuit 7, which is necessary for implementation of the electrical function of the switch.
A pair of rigid bars 17 and 18 is set in a position above the mat, and each bar is supported on a pair of silicone bubbles on one and the same side of the mat, so as to exert pressure on them as a consequence of the actuation of the oscillating control 4. The action of said control is transmitted to the rigid bars by means of a pair of prods 19 and 20 each associated to a single bar, in a point which is not equidistant from the points of application of the reactions of the silicone bubbles on the rigid bars, so that the linear motion of the prods as they are pushed downwards (with respect to Figure 2) will be converted into a motion of rotation and translation of said rigid bars.
The prods 19 and 20 are connected to the rigid bars 17 and 18 by hinges, which in one of the possible embodiments of the invention, are represented by flexible elements in the form of springs 22, which are S-shaped and are made of a single piece with the prod and the rigid bar, by means of a process of injection moulding. The wedge 24 on the prod and the seat 25 on the bar (Figure 3) which concur to form the hinge between the two components, in the moulding stage, are separated by a minimum distance, which is eliminated at the moment of assembly in the switch, when the two parts are in contact, thanks to the deformability of the springs 22, so creating the desired hinge.
A second embodiment, illustrated in Figure 4, is made by means of injection moulding of the prod of the bar in a single piece. In this case, it is made up of two elements 26, 27 shaped like rectangular parallelepipeds. These are connected crosswise together so that a side face of one element is set at right angles to a side face of the other element, the two elements intersecting at the centre of their side faces so as to form, in top plan view, a right-angled cross at the point of intersection.
This connection succeeds in providing the section of minimum joining in a point corresponding to the fulcrum. The said geometry enables the axial loads involved to be supported, and at the same time allows freedom of rotation with respect to one another of the two plane elements 26 and 27, of which one has the function of prod, and the other of connection to the rigid bar.
For the embodiment of the switch, it is possible to use other forms of coupling between the prod and the rigid bar, without thereby departing from the scope of the invention, as this is defined in the attached claims.
The switch according to the present invention functions in the way described hereinafter, with particular reference to Figures 5a, 5b and 5c.
When a pressure or a tensile stress is exerted on the push-button 4, causing its rotation about the fulcrum 5, there is, in any case, exerted a pressure on the central portion of one of the two rigid bars 17, 18, by means of the prods 19, 20. In the case described with reference to Figures 5a to 5c, the bar subjected to the said pressure moves downwards, starting from its resting position (Figure 5a).When it exceeds the first point of equilibrium, corresponding to the collapse of one of the bubbles, there is a first snap (Figure 5b), which brings the first contact of the lamina 10 to rest on the printed circuit 7, so closing the first control circuit. Proceeding in the action on the push-button, the rigid bar 17, 18 is further compressed and thus reaches the second point of collapse of the underlying bubble, bringing about the second snap, which causes the second contact of the lamina 10 to close the second control circuit on the printed circuit (Figure 5c).

Claims

A device for actuating a snap-action switch for controlling electrical apparatus of a motor vehicle, comprising a push-button (4) and a container body, in which there move at least two mobile contacts (10) that are designed to perform a travel to reach both a first position of arrest with closing of a first part of fixed contacts of a printed circuit and a second position of arrest with closing of a second part of fixed contacts of said printed circuit, said mobile contacts being moved by an elastic snap-action element made of silicone material (15), on which there acts a pair of rigid bars (17, 18), each of which is controlled by a prod (19, 20), which acts on them in a misaligned way, causing the snapping in succession of the part of the elastic snap-action element underneath the ends of said bars (17, 18), with consequent closing of said fixed contacts, the said device being characterized in that said prods and said rigid bars are made of a single piece of plastic material and with a hinge designed to enable conversion of the rectilinear movement of thrust on the prod into a movement of rotation and translation of the bar.
The device according to Claim 1 characterized in that said hinge is made up of at least one pair of S-shaped springs (22), which are connected at one end to the rigid bar and at the other end to the prod.
The device according to Claim 1, characterized in that the prod is made up of two elements (26, 27) shaped like rectangular parallelepipeds which are connected crosswise together so that a side face of one element is set at right angles to a side face of the other element, the two elements intersecting at the centre of their side faces so as to form, in top plan view, a right-angled cross at the point of intersection.