FR2472827A1 - Snap action switch with mobile leaf - biassed against one of two contacts by two central arms sitting in notches in common terminal - Google Patents

Abstract

The switch has an insulating housing (2) through one end of which two parallel output contacts (5,6) project. One end of a mobile leaf (1) carries a contact located between the output contacts and normally biassed against one by two resilient leaf spring arms (1c,d) which extend towards one another from opposite ends of the leaf. The free ends sit in V notches in a common contact rod (3) passing through the housing base and between the two arms. The end of the arm opposite the output contacts abut a pushbutton (7) which, when depressed, causes the arm to snap over and its end to switch from one to the other output terminal. The arm returns when the button is released.

Description

 The present invention relates to snap action switches comprising, in a small closed housing, generally made of insulating material, means for ensuring, from a so-called "common" connection, electrical continuity alternately on two other separate connections depending on the position of a blade operated by means of a control button.

This type of switch, as described in the patent
US 2,486,033, has evolved over time so as to simplify it still further in order to lower the cost price while retaining a breaking capacity of the order of 15 A at 250 V AC.

 The switch object of the invention is of the type comprising a common lug serving as a support for a movable metal blade, subjected to a permanent stress by arming on said lug and being able to occupy two different positions bearing on two other distinct lugs according to the position d '' a control button, one end of which is accessible from outside the housing.

In this housing, the movable blade has been studied so that its shape allows easy mounting, manually or by automatic means, on the common terminal so as to minimize the assembly time of the various elements of the switch . Indeed, the movable blade has two rigid lateral arms and two central arms, one of which is for example hollowed out to increase its flexibility.

 The central arms are slid into two Vs provided in the common terminal, which has the effect of constraining the movable blade which then comes naturally to bear on the one hand on the control button and, on the other hand, on one of the two fixed terminals.

The lateral arms being located above the points of articulation formed by the two Vs, when one of the ends of the blade is moved using the control button, the other end comprising the electrical contact switches on the second fixed terminal, but this position is naturally reversed if the pressure on the control button is released.

 The attached drawing by way of example will make it easier to understand the operation and the advantage of the device.

 Figure 1 is an overview of the switch, Figures 2 and 3 show the movable blade in plan view and in elevation.

 As shown in FIG. 1, the switch comprises a body 2 molded from insulating plastic material, the edges of which are split at three points to allow the insertion and holding in place of the output lugs 5 and 6 and the common terminal 3. On this terminal 3, two Vs 3a and 3b have been machined over its entire width so that the two central arms lc and id of the movable blade can be easily slid into it. Once mounted in the body of the microswitch, the blade 1 and the terminal 3 are held in place by two bosses 4 arranged at the level of the two V's, one in the housing and the other in the cover.

 The arm lc is made more flexible than the arm id, for example by making recesses there and if, when cutting the blade in a beryllium bronze ribbon. This arm therefore arches more when the blade is armed on the two Vs, and, when the control button 7 is operated, the blade pivots on the arm id around the V 3a.

This has the effect of sliding the contact pad ig on the contact pads of the terminals 5 and 6, before the abrupt change of position of the blade, so as to shear any micro-welds generated by the electric arcs.

The two lateral arms la and lb of the movable blade are folded back to 900 so as to release the two central arms lc and id
This arrangement is provided to facilitate mounting of the blade on the terminal 3. Indeed, one can for example slide the blades on a template gradually arming the two arms ic and id until these arms come into place on the two Vs of the common terminal and this by fully automatic means.

 The present invention lends itself particularly well to the production of small industrial snap switches whose assembly can be automated.

Claims (3)

 1 - Snap-action switch of the type comprising a common terminal serving as a support for a movable metal blade subjected to a permanent stress giving it two positions of equilibrium against two other fixed lugs according to the position of a control button, characterized by fact that the movable blade has two lateral arms and two central arms, the latter being armed in two V openings arranged on the common terminal and that two bosses are provided on the internal face of the housing and of the cover to center said blade inside of the switch.  2 - Snap action switch according to claim 1, characterized in that the lateral arms 1a and 1b of the movable blade are folded to sufficiently release the central arms ic and id so that they can easily be slid into the two V 3a and 3b of the common terminal when mounting said switch.  3 - Switch, according to claims 1 and 2, characterized in that the central arm ic of the movable blade, located on the side of the electrical contact, has recesses so that it is more flexible than the other central arm id located on the side of the heel of the blade.