US2420913A

US2420913A - Taper snap switch

Info

Publication number: US2420913A
Application number: US503876A
Authority: US
Inventors: Joseph H Schellman
Original assignee: Robert Hetherington & Son Inc
Current assignee: Robert Hetherington & Son Inc
Priority date: 1943-09-27
Filing date: 1943-09-27
Publication date: 1947-05-20
Anticipated expiration: 1964-05-20

Description

May 20, 1947- J. H. SCHELLMAMy 2,420,913

TAPER SNAP SWITCH Filed 4Sept.. 27, 1943 4 Sheets-Sheet 1 May 20, 1947. J. H. sci-lELLMm TAPER SNAP SWITCH Filed Sept. 27, 1943 4 Sheets-Sheet 2 @ge/wig n .2 w ,j A o Y A W & m

May 20, 1947- J.'H. scHELLMAN '2,420,913

' TAPER SNAP SWITCH Filed Sept. 27. 1943, 4 Sheets-Sheet 3 May 20, 1'947- J. H. SCHELLMAN 2,420,913

' TAVPER SNAP .SWITCH Filed Sept. 27, 1943 4 Sheets-Sheet 4 f, lim

, A-n- YL- aiented ay 20,

TAPER SNAP SWITCH lloseph H. Schellman, Ridley Park, Pa., assigner to Robert Hetherington & Son, Inc., Wilmington, Dei., a corporation of Delaware y Application September 27, 1943, Serial No. 503,876

My invention relates to a snap switch of the hill and valley type in which a shorting bar is snapped by a hill and valley plunger from open position in which the shorting bar or shuttle is disconnected from the contact terminals to a position in which the shorting bar closes a circuit or closes circuits, and in which the plunger may or may not be spring retracted.

A main purpose of the invention is to secure a very small, compact, reliable snap switch capable of carrying fairly highcurrents.

A further purpose is to provide a hill and valley plunger type of snap switch in which the slopes of the tapers on the plunger are different, providing for over-travel in one direction of movement and for a quick break of the circuit in the opposite direction.

A further purpose is to throw the shorting bar or shuttle of a hill and valley type snap switch by separate transverse operating springs held within the bar or shuttle by means effective at the ends of the springs.

A further purpose is to provide a shorting bar or shuttle for a hill and valley type snap switch in which opposite, transverse springs effecting the movement of the bar are anchored at their ends to theends of the bar.

A further purpose is to adapt my switch construction to either normally open or normally closed switch construction by merely reversing the direction of shorting bar contact parts and reversing the position of the contacts to be made by them.

A further purpose is to facilitate assemblage' of transverse springs in a shorting bar for a hill and valley type switch by dropping the springs into the' shorting bar laterally and holding them in by closures of the lateral space at the sides of the ends of the springs.

A further purpose is to hold springs which are transverse to the plunger of a hill and valley type switch in position by side contact with the ends. of the springs, determining the resistance to plunger travelby the distance and closeness with which the -ends of the springs are conned within the shorting bar, permitting the 'same structure to be used for switches having different plunger operating pressures by making a slight adjustment. A further purpose is to ground the shorting bar of a hill and valley type plunger switch so that two circuits maybe handled by the switch, be it normally open or normally closed.

A further purpose is to form a shorting bar of a hill and valley type plunger switch of a contact 4 Claims. (Cl. 20D- 76) 2 plate turned transversely to form the ends of the bar and of a second plate permissibly of insulation held in place by its engagement with the ends of the shorting bar.

Further purposes will appear in the specification and in the claims.

I have preferred to illustrate a few forms only y among many which are suitable for my purpose, selecting forms which are practical, effective, reliable and inexpensive and which at the same time well illustrate the principles of my invention. V

Figure 1 is a perspective view of one form of the invention.

modified form of the snorting bar structure of Figure 6.

Figure 8 is a section of Figure 7 taken between the springs, parallel to them and perpendicular to the frontv contact plate.

Figure 9 is a section of Figure 8 taken on line 9 9.

Figure 10 is e section correspondinggenerally with Figure 2 but showing a second desirable form,

Figures 11 and l2 are sections taken length-v wise through an operating button and a plunger showing variant forms. v

Figure 13 is an axial sectionof a sleeve showing a form differing from thatv seen in Figures 2 and 10 and suited to a two-circuit grounding switch.

Figure 14 is a diagrammatic view shovvingtwo circuits to be grounded.

Figure 15- is a perspective View of a modified i form of the invention.

Figures 16 and 17 are axial sections taken lat,

right angles to each other showingthe structure.v

of Figure 10.

Figure 18 is a transverse-section of Fiigurueil'iy taken upon lines l1-`-I1. Figure 19 is a perspective of. a rnodifiedior` the snorting bar or shuttle seenin\1 -igure..6 v.l.

'further .generally with Figure 6.

. Figure 25 is section showing the way in which any of my switches, with or without grounded plunger, can be made normally closed instead of normally open. by merely turning the shorting bar upside down and putting the contacts below the shorting bar.

The present invention relates particularly to snorting bar or shuttle mechanism and to the associated taper or plunger and other switch structure for use with hill-and-valley switches. In these switches a spring-retracted plunger carries a double operating taper engaged by inwardly pressing springs within a shuttle. The springs react upon opposite faces of the double wedge or taper on the plunger, each taper face in turn carrying the springs, and hence their associated shuttle, down the slope of the wedge after the hump or crest of the plunger wedge or taper shall have been pushed-or tretracted-past the springs. By reason of the double (wedge) taper carried by the plunger this plunger in its entirety is also called a taper. i

The structures of Figures 1 to 9 and 15 to 24 are single-throw switches which use the shuttle `or shorting bar to bridge across between contacts representing the opposite sides of the same switch gap. As a result, a circuit is opened and closed at two places. 'I'he structure of Figures 10-14 closes or opens a gap and grounds the circuits on opposite sides of the gap at the same time each at one point only. The switch is of single-throw type.

It makes no difference in this action whether the shorting bar close the circuit byupward movement or be turned upside down as in Figure 25 to normally close the circuit at the lower end of itsA stroke.

Describing the structure of Figure 1 to Figures 6 and 24, the casing 25 represents any suitable tubular casing. It may be metallic and electrically conducting if desired, so that it may be grounded and afford a ground for switch parts as in Figures 10-14. It is shown as separately or additionally insulated from the switch contacts to be "closed in any event. The exterior of this casing is nished at 26 and flanged at 21 for mounting purposes. The milled grooves 28 are for keycuits and is retracted forwardly to open the circuit or circuits.

Within thespace 35- a generally cylindrical in'- sulating sleeve or shell 36 protects the circuit contacts. The spring presses against a closed usually insulating (but in- Figures 10-14 electrically conducting) end 31 of the sleeve and compresses against it. T-he sleeve is a tight enough *it within the casing to stay in its place and may Y 4 be placed accurately in its position by engagement with a shoulder 38.

The plunger or taper 39 is xed rigidly at 40 within the insulating button and at its opposite (rear) end 4| is guided to slide within recess 42 in insulation block 43. A plate 44 insulates the rear edges of the casing. The insulation 43 carries a rib 45 projecting across the rear of the structure.

Electrical terminals 46 and 41 are threaded into the insulation block 43 and at their front ends are transversely turned to form

terminal contacts

48 and 49, or 48', 49' (Figure 25). At their outer threaded ends they receive nuts 5 6 against which outside circuit contact is made by conductors 5 I, 5 I held in position by nuts 52 and washers 53. l

kThe plunger or taper carries conical wedge faces 54 and 55, oppositely converging from bases at the crest 56. The rear wedge face 55 is of steeper slope than the front face 54. This provides for rapid switch breaking movement of the shorting bar or shuttle with slower switch closing movement and overtravel in the direction oi! closing movement. f

About the plunger is located a snorting bar, A

messenger or shuttle comprising a front plate-51, a. rear plate 58, connected to form a channel 59 between the two plates. The shuttle carries an electrically conducting annulus at its iront face 60 which is to connect across from one inwardly turned contact bar to the other.

The front plate andthe rear plate are connected by ends 6l, 62, bent rearwardly from the end ledges of the front plate 51 and cooperating with the rear plate 58 to hold the rear plate in position. The bent ends 6I, 62 can intert variously with the rear plate.

In the particular form shown the lateral edges of the ends are notched at v63 to receive projections 64, 65 from the sides of the rear preferably insulating plate 58 so that when the rear plate is in position and the ends of the front plate are bent rearwardly as seen in Figure 6, the notches in the ends receive the projections. The front plate ends lock the rear plate laterally by the projections 64, 65 and rearwardly by the parts 66 of the bent ends adjacent the notches.

Movement of the rear plate forwardly is' prevented by

lateial ears

61, 66 which are cut free from the ends at 69 and which in the blank before bending extend out farther laterally than the parts 66 of the ends.

The plunger or taper 39 moves through the openings 10, 1i in the front and rear plates, respectively, and between two generally parallel -spriral springs 12, 13 which are held so as to press against the tapered surfaces of the plunger in order that with plunger movement they may react to carry the shorting bar or shuttle .forwardly when'the plunger moves rearwardly and rearwardly when the plunges moves forwardly.

The generally parallel lengths of spiral springs 12 and 13 are retained within the groove of the snorting bar by means shown diierently in the various figures. In Figures 1 to 6 these spiral springs are heldin place by the

ears

61, 68, which limit the laterally outward movements of the ends of the springs and leave a predetermined intermediate length of each spiral spring which,

subject to the support of the ends by the ears,

'may bulge through the spac'e 14 between the ends of facing ears.

The generally parallel spiral springs may .be

not pressing against the inner faces of the ends of the bar, or may engage the inside faces of the ends -of the bar adjacent the attached ends of the ears. In assembly the springs may be put in position within the shorting bar as the ends 6|, 62 are being turned rearwardly or before they are turned rearwardly.

The

ears

61, 68 may be bent inwardly from the endswhen the sheet metal from which the front plate and ends are cut is being blanked out, or can quite obviously be bent inwardly after the ends have been bent down. In either case they can be placed so'as properly to hold the springs in position. The rear plate is put into position as the ends or at least as one end is being bent rearwardly.

As will be seen in Figure 6, the extent to which the ears from the same end are bent inwardly toward each other will determine the amount of laterally against it are used to furnish the impulse for the operation of the vshorting bar. These springs are stretched lengthwise and are fastened at their ends 'l'l to the ends of the shorting bar so yas to press laterally against one or other of the oppositely facing plunger wedge faces.

In this form as in the first form shown one transverse face of the shorting bar must be electrically conducting and for this reason is made a metal front plate. kThough metal would be entirely suitable for the rear plate of the bar here also in the normally closed circut formthe rear plate lis preferably made of insulating material which is quite stiff enough for the purpose but is much less expensive and much less scarce.

In Figure'? the rear plate is held at the rear by ears 18 pressed out of the ends of the front plate.

In Figure 10 an axial section corresponds generally with Figure 2 but shows a different form suited for grounding two circuits through the plunger.

The sleeve is in two parts. The cylindrical part of the sleeve is made of molded insulating material seen at 36' and the end 3l' is no longer insulating but is a separate part, an electrical conductor, a force t within the electricall'iv grounded metal casing. It is intended to make electrical contact at its outer circumference with the inside of the casing and at an intermediate position with the retraction spring 34'. The retraction spring connects electrically with the plunger 39' through the electrically conducting button 32'. The plunger engages transverse shorting bar springs, shorting bar front plate and the separate contacts, which are the terminals to be grounded.

flat strips, interlocking with the insulation block- 43'. They are molded into the insulation block and are laterally turned at their front ends. They are provided with apertured ends 8l in order that the connecting conductors leading to and from their circuits may be passed through these openings and soldered to the terminals.'

In Figure 10 the metal button is cast about a case-hardened steel taper, the boss 82-of the taper or plunger being encased in the metal of the button. In Figure 12 another way of fastening a chrome plated plunger is shown in that 'the boss 82' is a forced fit within an opening 83 in the metal button and the lower end of sleeve 84 is peened about the flange 85 to-hold the parts together. 'I'he plunger may be case hardened and the several parts may be brass plated or chrome plated or otherwise treated or coated as desired.

In Figure 11 a structure closely similar to that in Figure 10 is shown'in that the button is molded about a case-hardened steel taper. or plunger; differing from the button 32 and plunger construction of Figure 10 and from the button 322 ofl'Figure 12 323 is of insulating material and is made of molding compound.

In Figure 13 a separate view is shown ci the cylindrical insulated sleeve and'the separat(x metallic front end of the sleeve. The metalic iront end may be forced into the casing so as to make good electrical contact with the inside of the casing, using a shoulder 38 to limit its position as in the case of the front end of the sleeve in Figure 2. The ange 44' serves the purpose of the plate 44.

Figure 14 is a diagrammatic view illustrating the short circuiting of the two laterally turned ,

terminals

48 and 49 by the plunger so as to close and open two circuits at one point each, groundton electrically connected to the plunger.

The separate electrically conducting end for I I the insulating sleeve is flanged at 19 in order that The omission of the retracting spring requires that the plunger be moved by hand or by power in both directions of stroke. Asl shown, it is intended to be hand operated by button 324.

The-outer part of the casing is threaded at 86 and the electrical conductors are molded into the insulation block. 'I'he same general form of shorting bar is seen asin Figure 'l except that the ends of the. generally parallel operating springs are fastened to ribs 31 left between slits 88-cut in the rearwardly turned ends -of the shorting bar.-

In Figures 20, 21, 22 and 23 another form is shown which is operated by a cam lever and which is retained in closed switch position by the .the switch casing is omitted. The camlever 89 is pivoted at 90 and throws a cam face 9| .from the open switch position seen in Figure 21 to the closed switch position seen in Figure 22. The

l movement effected by the cam is communicated to the plunger through a cylindrical guide 92 which carries boss 93 which is surrounded by the retracting spring. The plunger is seated in the boss or in the cylindrical guide 92 or in both and the operation of the plunger and shorting bar are the'same as in Figures 2 and 10.

In operation, in Figures .2 and 16, the button is pushed against the resistance of the retraction spring, the limit of movement being conveniently s et either by the bottom of the press-button engaging the front of the sleeve or by the bottom of the plunger engaging the bottom ofI the recess in which the plunger operates. The transverse spiral springs have considerable lateral play` but they are held securely against undue lateral movement and furthermore are thus held to their duty to give reliable retracting pressure to the plunger,

The shorting bar cannot move downwardly in Figure 2 because of engagement of the edges 15 at instead of being flanged to iit within the sleeve, and may be electrically conducting for the grounded plunger form.

In Figure 25 the use of a plate 312 as the front end of the sleeve 362 permits either metal or insulation to be used for this front end as 4 preferred, the metal accommodating use with a of the ends with the insulation block and so the plunger moves through the springs stretching them laterally until the crest 56 of the double wedge passes the middle parts of the springs at which time the contraction of the springs causes the shorting bar to shift forwardly along the length of the plunger and until thefront plate of the shorting bar engages and cross connects the contact parts of the terminals d8 and I9. This closes the circuit between the Acontact at 48 and the front plate of the shorting bar and again beween the front plate of the shorting bar and the contact 49.

In the form of Figure 10, grounding of the plunger through the retraction spring, metal end of the sleeve and casing results in grounding the shorting bar at all times and two circuits are closed through the two contacts 48' and 49' and ground.

In the forms of Figures 16, 17 and 21, 22, special operating mechanism is shown but the principles of operation are the same.

It will be evident that whether the electrically conducting front end 'of the sleeve (31') being extended inwardly or not will depend upon .the amount of clearance between it and the contacts 48', 49', since this must not be short circuited. It does not make any difference in the normally closed form of this switch since thecontacts will be below (using the directions of Figure 10) the shorting bar. In the normally closed form (of the type of Figure 25) the extended edges 15 of the shorting bar will face upwardly and will use the front end of the sleeve as a step to their travel. 'Ihis will be permissible whether the front end be electrically conducting or insulating since the shorting bar will be disconnected from the contacts at the upper end of its stroke. The form of Figure 25 is. therefore, suitable for grounded plunger-and therefore grounded circuit through the plunger-use.

In Figure 25 the front end of the sleeve is made grounded plunger to ground the circuits and the insulation iitting in with the other forms. The contacts Maand 492 may be connected with any type of terminals and are intended of course to be diagrammatic only.

Having thus described my invention, what I claim as new and desire to protect by Letters Patent is:

1. A shorting bar for a. hill and valley switch comprising an apertured front contact plate, a rear insulating plate, connections between the two plates,'substantially parallel spiral springs lying between the two plates, and ears connected with the :front plate and restraining the outer sides of the ends of the springs to limit lateral distortion of the springs.

2. A shorting bar for a hill and valley switch comprising an apertured front contact plate, a rear insulating plate, connections between the two plates, substantially parallel spiral springs Lying between the' two plates. and adiustable lateral holding means engaging the sides of the ends of the springs, retaining the springs against lateral distortion to an extent depending upon the adjustment of the ears and limiting bulging of the springs between the ears.y

3. A shorting bar for a hill and valley plunger switch having an electrically conducting front face apertured for plunger passage, ends rearwardly turned from the front face,` a rear face similarly apertured inter-fitting with the ends,

ears extending'from the ends, and springs between the two faces held in place laterally by the'ears and adapted to engage the wedge faces of a hill and valley plunger.

4. In a hill and valley switch, a casing, insulation for the interior of the casing, electrical conductors entering the casing and insulated from it, transverse terminals from said conductors, a shorting bar having` transversely extending springs and an electrically conducting front plate, a plunger cooperating with the shorting bar and carrying oppositely facing wedge surfaces pressing against the springs, and means for holding the springs Within the bar, said means restraining the springs at their sides near the 'ends of the springs and determining the resistance of the springs to side distortion by the plunger by the extent of restraint given the springs.

JOSEPH H. SCHELLMAN.

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

, UNITED STA'IES PATENTS Number