US2524784A

US2524784A - Snap switch

Info

Publication number: US2524784A
Application number: US643081A
Authority: US
Inventors: Albert E Franks; Mervin B Arisman
Original assignee: CHICAGO TELEPHONE SUPPLY CO
Current assignee: CHICAGO TELEPHONE SUPPLY Co
Priority date: 1946-01-24
Filing date: 1946-01-24
Publication date: 1950-10-10
Anticipated expiration: 1967-10-10

Description

Oct. l0, 1950 A E. FRANKs Erm. 2,524,784

SNAP SWITCH Filed Jan. 24, .1946 2 Sheets-Sheet l 0d l0,A 195() A. E. FRANKs Erm.. 2,524,784

' SNAP swrrcn Filed Jan. 24, 1946 2 sheets-sheet 2 bmx/Mw Patented x Oct. 10, i950 UNITED; STATE Albert E. Franks,

' B. Arisman, Elkhart, Ind.1, asaignoi'stoy 1 g Chicago Telephone j Supply .-Company',

Y linka corporation of Rawlings'andf' 'Y application Januaryfzi, 194s; serial No.' 643.1231'V iclaimnfwizoo-s'n.

This invention relates to elcctricswitches and vThe. accompanying drawingsV illustrate Y one refers more particularly tofsnapswltches of the type mounted on the backl of volume controls for radio equipment as in Patent No. 2,286,162 issued to N. C. Schellenger, June 9, 1942. Switches of this type are of necessityquite small. They are generally housed in small diameter, shallow casings and as a consequence, there are definite design limitations making it exceedingly difllcult to obtain suilicient spring action or spring range. The samel limitations make it difcult to achieve desirable wiping action between the contact surfaces. Both of these features are of great importance in snap switches and to a large degree determine the stability of the electrical contact during the life of the switch.

With a view toward achieving optimum satisfaction as to both these features in a small snap switch, it is an object of this invention to provide a switch wherein the necessary spring action is obtained through use of a novel combination terminal and stationary contact member.

In this connection it is more speciiically another object of this invention to provide a snap switch wherein the stationary contacts consist essentially of spring fingers anchored at one end to the base and adapted to flex freely across the face of the base in consequence to engagement of the contactor therewith.

Another object of this invention is to provide I a novel combination terminal and stationary contact for use in switches of the character described, which is so designed that its contact portion can be readily shaped and formed to secure maximum compactness without in anywise affecting or sacrificing its spring properties.

Another object of this invention is to provide a switch wherein the actual make and break between the movable contactor and the stationary contacts occurs at areas spaced from the surfaces which are engaged in the closed condition of the switch so that the ill effects of any arcing which may take place during opening and closing of the switch does not affect the areas where final conv complete example oi.' the v'physical embodiment 'o1' the invention constructed accordingV to the ing a switch embodying this invention mountedl on the back of a volume control;

Figure 2 is a cross sectional view taken through Figure 1 on the plane of the line 2`2 and looking into the switch, the switch being shown in open position; y

Figure 3 is a view similar toFigure 2 but showing the `switch closed;

Figure 4 is an enlarged detail sectional view taken through Figure 2 on the plane of the line 4 4;

Figure 5 is an enlarged cross sectional view taken through Figure 1 on the plane of the line 5-5 and showing the manner in which the con- -tacts engage during closure of the switch; and

Figure 6 is a perspective view of one of the combination terminal and stationary contact members.

Referring now particularly to the accompanying drawing in which like numerals indicate like parts, the numeral 5 designates the base oi' the switch which consists of a circular disc of suitable insulating material and closes one end of a cylindrical metal shell 6. The base and the shell thus constitute a substantially' cup-shaped switchhousing. Fixed to the base and projecting from the inner flat surface thereof is a pivot post 1. This post, which is located near one edge of the base, has a ilat switch arm 8 of insulating material p ivoted thereon to swing edgewise acro the base but in spaced relation thereto.

Also mounted on the pivot post 1 is an actuating cam 9. Inasmuch as this invention does not concern the construction of the actuating cam and as this element is similar to that of the aforesaid patent and other prior art, it is sufilcient to point out that the cam is adapted to be swung between deilned limits by a. driver I0 carried by the rotatable structure ofthe. volume control or other similar unit, indicated generally by numeral Il, on the back of-which the switch is mounted.

The= actuator 9 is drivingly connected with the switch arm Il through a toggle spring 9 which snaps the switch larm from one position to the other as the actuator is rocked about the pivot .post 1. The limits of movement of the switch arm are defined by the engagement of its opposite edges with the side of the metal shell I as will be Ireadily apparent from a comparison oi.' FiguresZ and 3.

interposed between the base 5 and switch arm 8 are the stationary contacts I2 of the switch. The present embodiment of the invention being a double pole single throw switch. there are four of these stationary contacts, arranged in two pairs each adapted to be electrically bridged by one of two contactors I3 xed to the underside of the switch arm.

The contactors I3 consist of stubby cylindrical studs I4 having a rivet portion I5 by which the contactors are anchored to the switch arm as clearly shown in Figure 4. Thus the motion of the contactors is constrained to a defined arc concentric to the axis of the pivot post 1. The arcs of motion of the two contactors may coincide or be concentric depending upon the nature of the switch and the most suitable arrangement of stationary contacts. In the present double pole, single throw switch, the arcs of movement of the two contactors coincide.

The stationary contacts I2, in which the chief novelty of the present invention resides, are actually combination terminal and contact members. Their specific shape may vary but all of the combination terminal and contact members are formed as stampings and have a flat body portion I2' with parallel side edges I8 and I1. A tongue I8 projects from the edge I1 of the body portion. This tongue is abruptly reduced in width at a point spaced fromthe edge I1 a distance substantially equal to the thickness of the base, to form shoulders I9 and an extended terminal portion 20.

The tongue I8 passes through a slot 2I in the base where it is secured by peening or swedging over the shoulders I9 as at 22. Attention is directed to the fact that the side edges of the tongue I8 are tapered so that as the tongue is driven into the slot 2I to bring the edge I7 of the body portion flat against the inner surface of the base the tongue becomes wedged into the slot to hold the same against edgewise displacement. Also the peening and swedging 22 not only extends over the ends of the slot 2I but spreads sidewise or laterally over the edges of the slot to thus firmly anchor the combination terminal and contact member to the base with its body portion I2' disposed edgewise and perpendicular to the flat inner face of the base.

The edges I6 of all of the body members lie in a common plane and being located at various points on the base provide a support for the switch arm 8 to hold the same in proper parallel spaced relation to the base. Projecting from one end of the body portion I2' of each of the combination terminal and contact members is a blade-like spring nger 23. These spring fingers, as clearly shown in Figure 4, are of less height than the body portions and are clear of the base and switch arm so as not to be frictionally restrained from free resilient flexure in a plane parallel to the base.

The spring fingers of each pair of stationary contacts are opposite each other and their free end portions converge to terminate in almost parallel portions 24. These end portions 24 are spaced apart a distance less than the diameter of the contactor studs I4. Thus, as best shown in Figure 5, when the switch is closed and the contactors are brought into engagement with their respective spring fingers, the contactors are wedged between the spring fingers with a wiping engagement.

In addition, the areas of the contactors and spring fingers between which initial make and final break occurs are spaced from the areas of the contactors and spring fingers which are engaged when the switch is closed. Therefore, any pitting which might result from possible arcing will not interfere with the contact resistance of the switch in its closed position.

From the foregoing description taken in connection with the accompanying drawings, it will be readily apparent to those skilled in the art that this invention provides an exceedingly compact switch construction and that the nature of the combination terminal and stationary contact members achieves exceptional iiexibility in design enabling the salient features of the invention to be embodied in single pole, double throw, and single pole, single throw switches as readily as in the present disclosed double pole, single throw, adaptation.

What we claim as our invention is:

1. In an electric switch: a at base of insulating material; a stationary contact mounted on the base, said stationary contact having a rigidly xed mounting portion projecting up from the base with its top edge parallel to the base and a spring finger extending from the mounting portion and adapted to be exed in a plane parallel to the base; a at switch arm of insulating material resting on the top edge of the xed mounting portion of the stationary contact to be guided thereby for edgewise movement across the base in a plane parallel thereto but spaced therefrom; means constraining such edgewise movement of the switch arm to an arcuate motion between deiined limits; the switch arm having substantial area and riding on the top edge of the xed mounting portion throughout its entire range of motion; the spring linger having less height than said mounting portion and being spaced from the top edge thereof and from the base sothat flexure of the spring finger in a plane parallel to the base is not frictionally restrained; snap acting driving means above the switch arm and connected thereto for swinging the switch arm from one position to the other with a snap action; and a contactor carried by the switch arm and movable thereby into switch closing engagement with the spring finger, the path of movement of the contactor with respect to location of the stationary contact being such that the spring nger is tensioned during closure of the switch.

2. In an electric switch: a flat base; a plurality of stationary contacts mounted on the base and each having a rigidly fixed mounting portion projecting up from the base and a spring linger extending laterally from the mounting portion, all of the mounting portions have the same height and the top edges thereof being parallel to the base; a flat switch arm pivoted to swing edgewise across the base and riding on said top edges of the mounting portions to be guided thereby, said switch arm riding on the top edges of the mounting portions throughout its entire range of motion; the spring lingers being of less height than the mounting portion and being spaced from the base and the switch arm so that flexure of the spring fingers in a plane parallel with the base is not frictionally restrained; and contactors carried by the switch arm and movable thereby across the base to and from bridging engagement, each with a pair of said spring lingers.

3. In an electric switch: a flat base; a pair of stationary contacts mounted on the base and each having a rigidly fixed mounting portion pro- `jecting up from the base with its top edge parallel ing portions to be guided thereby for edgewise movementl across the base in a plane parallel thereto but spaced therefrom; means constraining such edgewise movement of the switch arm to a deiined path between denite limits, the switch arm having substantial area. and riding on the top edges of the fixed mounting portions throughout its entire range of motion; the spring fingers being of less height than the mounting portion and being spaced from the base and the switch arm so that exure of the spring iingers in a plane parallel with the base is not frictionally restrained; a contactor carried by the switch arm at the underside thereof and movable thereby to and from bridging engagement with the spring ngers; and snap acting driving means above the switch armand connected thereto for moving the switch arm from one position to the other with a snap action, the insulated switch arm-by virtue of its substantial area and disposition between the contacts and driving means-serving as an insulating shield between the switch contacts and the snap acting driving means.

4. In an electric switch: a base having a at top surface; a pair oi' stationary contacts mounted on the base and each having a rigidly ilxed mounting portion projecting up from the base with its top edge parallel to the at top surface of the base, and a blade-like spring'flnger extending therefrom and resiliently yieldable in a. direction parallel with the at top surface of the base; a flat switch arm of insulating material resting on thetop edges of the fixed mounting portions of the stationary contacts to be guided thereby for edgewise movement across the base in a plane spaced therefrom but parallel to its `flat top surface; the spring fingers being of less height than the mounting portion and being spaced from the base and the switch arm so that flexure of the spring iingers in a plane parallel with the base is not frictionally restrained; said spring ngers being opposite each other and oonverging towards but spaced from each other; a

cylindrical contactor of a diameter greater thanv the minimum distance between the spring fingers; means securing the cylindrical contactor to the underside of said switch arm; means constraining edgewise movement of the switch' arm to a deined path between xed limits with the cylindrical contactor moving across the base with the axis of the contactor perpendicular to the fiat top surface of the base and travelling along a line which lies between the spring fingers so that the contactor is brought into bridging engagement with the spring fingers as the switch arm is moved in one direction and vice versa; and means disposed above the switch arm and connected thereto for moving the same back and forth.

ALBERT E. FRANKS. HARVILLE LEES RAWLINGS. MERVIN B. ARISMAN.

REFERENCES CITED The following references are of record in the iile of this patent:

UNITED STATES PATENTS