GB2088133A

GB2088133A - Snap-action Switch

Info

Publication number: GB2088133A
Application number: GB8132393A
Authority: GB
Original assignee: Crouzet SA
Current assignee: Thales Avionics SAS
Priority date: 1980-11-03
Filing date: 1981-10-27
Publication date: 1982-06-03
Also published as: FR2493590B1; GB2088133B; IT8124690A0; IT1140469B; FR2493590A1; DE3142887A1

Abstract

A change-over snap action switch comprises a contact blade (1) having two arms which are positioned in V- shaped grooves of a partially silver- plated terminal portion (2), welded onto a terminal (3). The terminal portion (2) is formed by shearing a portion from a silver - plated section whereby the sheared side faces of the portion (2) are not coated with silver. This enables a saving in silver to be obtained. <IMAGE>

Description

SPECIFICATION Economical Snap-Switch and Method for Making Same The present invention relates to a snap-switch of the type comprising, in an insulating housing, a common terminal serving as support for a mobile metal blade subjected to a permanent tension giving it two possible positions of balance against two output terminals depending on the position of a control knob, the common terminal being made of two parts welded together.

This type of switch, as for example described in French Patent No. 1 509 025, is simple and inexpensive to manufacture and has a good cutoff power.

The electrical qualities are obtained by playing on various factors such as: contact pressure, kinematics of the blade so as to obtain shearing of the possible microwelds, and by improving the surface of the pieces having to ensure electrical continuity, by deposit of a noble metal. It is for this reason that the useful part of the common terminal of this type of switch is generally completely silver- or gold-plated, in order to improve the electrical conductivity between it and the elastic blade tensioned in two V-shaped grooves provided to this end.

Attempts have already been made to reduce the amount of silver or gold used in such switches. As the common terminal is made of two parts which are distinct but which are electrically and mechanically connected for example by welding, the part comprising the V-shaped grooves may be reduced to the strict minimum and it alone is silver-plated, whilst the second, larger part, acting as connecting terminal, is made of metal such as bronze or brass, without particular protection.

It is an object of the present invention to propose further savings in precious metal.

To this end, the present invention relates to a switch of the above-mentioned type, characterized in that one of the two parts of the common terminal is made of ordinary metal, in terminal form, and the other, serving as piecefor tensioning the mobile blade, is obtained by shearing a section coated with a noble metal, said section comprising two V-shaped grooves surmounted by a rounded part and at least one longitudinal element in relief to facilitate electric welding of said piece on the terminal.

From a section of appropriate shape, passed in a silver bath on leaving the die, smail portions are cut off and then electrically welded, by known means, on the actual terminal part.

The fact of shearing the portions from the section which is previously silver-plated is a very economical method. In fact, this avoids losses of material (no swarf) and the portion obtained is silver-plated only on the useful faces, particularly on the V-grooves, to the exclusion of the two side faces which have no electrical function in this type of switch.

The invention will be more readily understood on reading the following description with reference to the accompanying drawings, in which: Fig. 1 shows a diagram of the switch of the invention; Fig. 2 is a schematic view in section of the common terminal of the switch of Fig. 1, and Fig. 3 is a view in perspective of the portion of the terminal of Fig. 2.

Referring now to the drawings, the switch according to the invention comprises, in known manner, a housing 7 moulded from insulating material, in which is mounted the snap-device, i.e.

two output terminals 4 and 5, a common terminal 3, on which a piece 2 has been added as tension means for an elastic blade 1. A control knob 6 and a biasing spring 8 complete the device.

The feature of this switch, illustrated in Fig. 2, consists in that the portion 2 is added by electric welding on the terminal 3. Its free end 2a is rounded in form to facilitate automatic assembly, by force-fitting the arms 1 a and 1 b of the blade 1 in two V-shaped grooves 2b. This terminal-blade assembly is embedded in a slot, provided to this end on the edge of the housing, and its position is defined by stops, 7a, 7b and 7c also provided in the housing.

The portion, shown in Fig. 3, was previously cut out by shearing a silver-plated section, which avoids losses of material and is more economical from the standpoint of silver-plating, since the side faces, left after the portion has been cut off, are not coated with precious metal.

One or two elements in relief 2c are provided to facilitate electric welding of this portion on the terminal 3.

The device and the method according to the invention enable snap-switches to be produced which are economical and adapted to be automatically assembled.

Claims

1. A snap-switch of the type comprising, in an insulating housing, a common terminal serving as support for a mobile metal blade, subjected to a permanent tension giving it two possible positions of balance against two output terminals depending on the position of a control knob, the common terminal being made of two parts welded together, characterized in that one of the two parts of the common terminal is made of ordinary metal, in terminal form, and the other, serving as piece for tensioning the mobile blade, is obtained by shearing a section coated with a noble metal, said section comprising two Vshaped grooves surmounted by a rounded part and at least one longitudinal element in relief to

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

Claims

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Economical Snap-Switch and Method for Making Same The present invention relates to a snap-switch of the type comprising, in an insulating housing, a common terminal serving as support for a mobile metal blade subjected to a permanent tension giving it two possible positions of balance against two output terminals depending on the position of a control knob, the common terminal being made of two parts welded together. This type of switch, as for example described in French Patent No. 1 509 025, is simple and inexpensive to manufacture and has a good cutoff power. The electrical qualities are obtained by playing on various factors such as: contact pressure, kinematics of the blade so as to obtain shearing of the possible microwelds, and by improving the surface of the pieces having to ensure electrical continuity, by deposit of a noble metal. It is for this reason that the useful part of the common terminal of this type of switch is generally completely silver- or gold-plated, in order to improve the electrical conductivity between it and the elastic blade tensioned in two V-shaped grooves provided to this end. Attempts have already been made to reduce the amount of silver or gold used in such switches. As the common terminal is made of two parts which are distinct but which are electrically and mechanically connected for example by welding, the part comprising the V-shaped grooves may be reduced to the strict minimum and it alone is silver-plated, whilst the second, larger part, acting as connecting terminal, is made of metal such as bronze or brass, without particular protection. It is an object of the present invention to propose further savings in precious metal. To this end, the present invention relates to a switch of the above-mentioned type, characterized in that one of the two parts of the common terminal is made of ordinary metal, in terminal form, and the other, serving as piecefor tensioning the mobile blade, is obtained by shearing a section coated with a noble metal, said section comprising two V-shaped grooves surmounted by a rounded part and at least one longitudinal element in relief to facilitate electric welding of said piece on the terminal. From a section of appropriate shape, passed in a silver bath on leaving the die, smail portions are cut off and then electrically welded, by known means, on the actual terminal part. The fact of shearing the portions from the section which is previously silver-plated is a very economical method. In fact, this avoids losses of material (no swarf) and the portion obtained is silver-plated only on the useful faces, particularly on the V-grooves, to the exclusion of the two side faces which have no electrical function in this type of switch. The invention will be more readily understood on reading the following description with reference to the accompanying drawings, in which: Fig. 1 shows a diagram of the switch of the invention; Fig. 2 is a schematic view in section of the common terminal of the switch of Fig. 1, and Fig. 3 is a view in perspective of the portion of the terminal of Fig. 2. Referring now to the drawings, the switch according to the invention comprises, in known manner, a housing 7 moulded from insulating material, in which is mounted the snap-device, i.e. two output terminals 4 and 5, a common terminal 3, on which a piece 2 has been added as tension means for an elastic blade 1. A control knob 6 and a biasing spring 8 complete the device. The feature of this switch, illustrated in Fig. 2, consists in that the portion 2 is added by electric welding on the terminal 3. Its free end 2a is rounded in form to facilitate automatic assembly, by force-fitting the arms 1 a and 1 b of the blade 1 in two V-shaped grooves 2b. This terminal-blade assembly is embedded in a slot, provided to this end on the edge of the housing, and its position is defined by stops, 7a, 7b and 7c also provided in the housing. The portion, shown in Fig. 3, was previously cut out by shearing a silver-plated section, which avoids losses of material and is more economical from the standpoint of silver-plating, since the side faces, left after the portion has been cut off, are not coated with precious metal. One or two elements in relief 2c are provided to facilitate electric welding of this portion on the terminal 3. The device and the method according to the invention enable snap-switches to be produced which are economical and adapted to be automatically assembled. Claims

1. A snap-switch of the type comprising, in an insulating housing, a common terminal serving as support for a mobile metal blade, subjected to a permanent tension giving it two possible positions of balance against two output terminals depending on the position of a control knob, the common terminal being made of two parts welded together, characterized in that one of the two parts of the common terminal is made of ordinary metal, in terminal form, and the other, serving as piece for tensioning the mobile blade, is obtained by shearing a section coated with a noble metal, said section comprising two Vshaped grooves surmounted by a rounded part and at least one longitudinal element in relief to facilitate electric welding of said piece on the terminal.

2. A snap-switch substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.