US2813943A - Industrial snap switch - Google Patents

Description

Nov. 19, 1957" P. H. WINTER INDUSTRIAL SNAP SWITCH Filed April 25, 1955 '2 Sheets-Sheet 1 F I613 'INVENTQK 60 E A 0 PAUL H. WINTER .0 ""I; 60'

MMJW ATTORNEYS Nov. 19, 1957 Filed Ap ril 25, 1955 2 Sheets-Sheet 2 7/ 70 1 5 v huh i i 33 1"! r i 76 @4 35 g 1 "77 a F 6. 5 37 INVENTOR ATTORNEYS United States Patent INDUSTRIAL SNAP SWITCH Paul H. Winter, Syracuse, N. Y., assignor to Pass & Seymour, Inc., Syracuse, N. Y., a corporation of New York Application April 25, 1955, Serial No. 503,700 7 Claims. (Cl. 200-67) This invention relates to snap switches and more particularly to such switches for industrial and portable tool use.

It is a general object of the present invention to provide a novel and improved snap switch.

An important specific object of the invention consists in the arrangement in an over-center spring-snap yoke type of switch of means to delay movement of the yoke in contact-opening direction until the spring has passed well beyond the dead center position whereby a more rapid snap results.

Another important object of the invention consists in the provision of movable contact restraining means acting as secondary stationary contacts.

A further important object of the invention consists in a unique arrangement of the push button switch operator whereby it is guided in the housing against the lateral pull of the snap spring.

A still further important object of the invention resides in the arrangement of the single button switch operator with a return spring and housing attached guide means.

An important feature of the switch construction consists in the combination mounting bracket for the switch which includes guide means for the operating button and fulcra for the button-contacting operating lever.

Other and further objects and features of the invention will be more apparent to those skilled in this art upon a consideration of the accompanying drawing and following specification wherein are disclosed two exemplary embodiments of the present invention, with the understanding that such combinations, changes and modifications may be made therein as fall within the scope of the appended claims without departing from the spirit of the invention.

In said drawing:

Fig. 1 is a longitudinal central section through a switch assembly constructed according to the preferred embodiment of the present invention, the view being taken on the plane indicated by line 1--1 of Fig. 2;

Fig. 2 is a bottom plan view of the upper section of the switch housing and its assembled contacts;

Fig. 3 is a transverse section taken on the plane of line 33 of Fig. 1;

Fig. 4 is a transverse section through the operating button taken on line line 4-4 of Fig. 1;

Fig. 5 is a longitudinal section through a second embodiment of the invention, taken on broken line 5-5 of Fig. 6; and

Fig. 6 is a plan view of the lower section of the housing with movable switch parts shown in working positions.

The embodiment of the switch illustrated in Figs. 1 to 4, inclusive, is provided with a combined mounting and operating bracket intended for use on certain machines as automatic stop mechanism, but the principles of this embodiment, as well as the other, may be used independently of this mounting,

2,813,943 Patented Nov. 19, 1957 As seen, the switch parts are encased in housing 10 divided along the horizontal plane 11 into upper portion 12 and lower portion 13 each provided with appropriate compartments, recesses, channels and the like to accommodate the various working portions of the switch, as will be indicated as the description proceeds.

As seen in Fig. 2, housing portion 12 is provided with transverse channel 15 near one end thereof in the bottom of which is mounted a pair of stationary contact buttons 16 each positioned on the enlarged head 17 of a sheet metal terminal element 18, the tail of which is constructed to receive a conductor 19 which enters through the end wall of the housing. The channel 15 is substantially duplicated at 15 in the lower housing portion and may if desired be provided with identical contacts in order to provide a double throw switch, but as illustrated merely has a flat bottom wall 20 acting as a stop for the movable switch element, later to be described. The contacts and their sheet metal terminal parts are held closely in the bottom of their respective portions of channel 15 and longitudinal grooves 21 by small rectangles 22 of sheet insulating material whose side edges are housed in slots 23 in the housing material and whose upper edges are engaged by the face of the other housing portion to hold them in position. The contacts 16 may be provided with integral hollow rivets as seen in Fig. 3, which pass through appropriate holes in the terminal plates and housing portion 12 where they are headed over in counterbores. In case the lower housing is also fitted with contacts these insulation plates 22 may be long enough to extend from one contact terminal to the corresponding one in the opposite housing portion.

The switch is provided with snap mechanism having an overcenter spring, and the principal element of this construction is sheet metal yoke 25 of Y shape having arms 26 whose flat ends 27 bear against fulcra 2S molded in the two portions of the housing in the form of notches with end walls 29 cooperating with the edges of the yoke arms to prevent lateral movement. The narrow stem 30 of the yoke which projects into the transverse channel 15 is reduced in width to provide a shoulder and a split tongue. This tongue passes loosely through the transverse contact bar 32, or bridging member, and the tongue ends are oppositely bent over as seen in Fig. 3 to prevent the bridging member from becoming disengaged. The connection is sufficiently loose to be termed a floating one, so that the bar 32, which is of proper length, may provide a connection between the contacts 16 previously defined. Thus with one set of contacts 16 the switch is a single pole, double break type insuring even in its small size adequate breaking capacity.

To complete the snap mechanism a helical tension spring 33 connects the opening 34 near the fork of the yoke to the opening in the arm 35 of the operating element of the switch. This has a parallel arm 36 in 'W6ll 37 in the lower housing portion to resist the lateral pull of spring 33 and to prevent rotation of the button by meddlers. The transverse part 38 of the operating element carries a portion 39 parallel to 36 which is closely fitted in a bore 40 of cylindrical operating button, illustrated in Figs. 1 and 4. The larger diameter portion of the button passes through circular hole 41 in the upper housing top wall and a smaller diameter portion 42 joins it at shoulder 43. The switch is illustrated as intended to remain on until the button is pressed, which then carries the center line of the spring through the plane of the yoke and snaps it from the position illustrated in Fig. 1 to the off position in a well known manner, but when pressure is relieved from operating button 42 helical spring 44 housed in well 45 in the lower housing and compressed against the transverse part 38 of the operating member returns this latter to its upper position and o returns the switch to closed circuit condition. Obviously the operation may be reversed by having the contacts 16 at the bottom rather than at the top.

The mounting bracket for the switch is formed of sheet metal and performs a number of functions. It has a relatively flat portion t? adapted to overlie the top wall of the upper housing portion, as seen. It is provided with an opening freely clearing the larger diameter of the push button, and has a portion 52 turned over parallel to and spaced from 50 providing an opening 53 receiving the small diameter of the button. Thus the bracket is provided with a pair of guide apertures operating on two different diameters of the button to insure it against canting. Moreover the shoulder 43, when engaged with the overlying portion 52, limits the outward movement of the button under the action of its spring 44.

The plate 50 has a pair of arms (not shown) bent downwardly to pass through grooves 51 in the housing walls and secured to the bottom portion to hold the housing assembled. It also has a portion extending to the left which may be turned down for mounting against a suitable supporting surface. It also has a pair of upturned wings 54 transversely bored to receive pivot pin 55 passing through similar wings 56 on operating lever 57 which has a protuberance 58 for engagement with the top of button 42 and may have an operating surface anywhere to the right thereof engaging the part'whose movement controls the operation of the switch. To the left of wings 56 the lever has a projection 59 adapted to engage the upper edge of a wing 54 to limit the upward throw of the lever to determine the adjustment of button 42 independently of engagement of its shoulder 43 with overhang 52.

The conventional over-center switch is deficient in rate of contact separation because of the geometry of the snap mechanism. With the switch closed as seen in Fig. 1 the spring reaches dead center when the line between the holes to which its ends are secured coincides with the plane of the yoke. Any slight additional downward movement of the operator causes the start of snap action which throws the yoke to its opposite position, but the movement starts at a time when the spring provides a minimum force or separating moment so that the contacts are subject to destructive arcs from large or inductive loads which soon require replacement of the switch.

The present switch however is equipped with mechanism which holds the bridging bar in close engagement with its stationary contacts until the spring has passed well beyond the dead-center position and exerts a considerable force or lifting moment on the yoke, at which time it is snapped loose with celerity. The construction of the holding means is best illustrated, in Fig. 3. Thus each sheet metal part 17, 18 forming the terminal and base for a contact has an integral side arm 60 bent up. from the outer edge thereof and inwardly, as shown, and then provided with an outwardly deflected end 61 to provide for the ready entrance of the rounded ends 62 of the bar 32 when moving to on position. As seen in this figure, however, the points of inflection 60 of the springs 60 engage and slightly overlie the ends of the bridging bar so that they must be spread apart by the pull of spring 33 before the bridging bar is released, which requires that the spring be advanced well beyond its dead-center position so that its effective angle is increased. Thus when release is effected movement is extremely rapid since the spring is highly tensioned at the time. These auxiliary contact springs 60 perform a secondary function on the make for they prevent rebounding of the bridging bar after striking con tacts 16 and hence any possibility of arcing.

In addition to the arms formed integral with the bracket plate 50 which clamp the two halves of the housing together at the operator end, a rivet 63 passes through the two halves and the plate 50 in the area between the terminal plates and insures against any movement or separation of the parts of the housing at this end. A piece of insulating material 64 may be interposed to provide adequate electrical insulation between the contact rivets and the bracket plate (see Fig. 3).

The switch of Figs. 5 and 6 is equipped with the same operating mechanism and a similar housing, all of which have the same reference characters as the preferred embodiment. The metal cover plate 70, however, is only of the same dimension as the switch housing and has similar arms which pass through the slots 51 in the side walls thereof and are secured to the lower portion of the housing to hold the parts assembled and may be aided by a rivet near the other end as shown at 71.

Except for readily apparent minor differences the housing parts are similar to those in the preferred embodiment. The snap mechanism and the bridging contact 75 are the same with the same style of mounting.

This switch is preferably, but not necessarily, of the double throw type so that as shown the bridging contact is normally held against one set of stationary contact 76 in the upper housing section by its button return spring but can be snapped to engage the other like set of contacts 77 in the lower housing section.

In this construction the contacts are not secured to the housing sections by riveting but are each attached to a terminal plate 78 shaped to be received and held in a housing channel 79 against longitudinal withdrawal by interfitting engagement as shown. The terminal plates are held against the bottoms of their respective channels by small rectangles 80 of insulation edge-positioned in slots 81 and 82 in the side walls of the channels 79, each rectangle engaging the corresponding terminal plate in opposite housing portions. The outer ends of the terminal plates are appropriately shaped, bent and fitted with terminal screws as shown.

The stationary contacts may each be fitted with a holding spring as at in Fig. 3 but can be used in their absence and are so shown.

The operating button 42 in this construction is similar to that in the preferred construction but is retained and guided in position by the threaded sleeve 84 secured to the cover plate as seen at 85. This sleeve, fitted with a nut is used to mount the switch in a suitable hole in a plate or panel in an obvious manner.

I claim:

1. A snap switch of the type described having in combination, a yoke, fulcra for said yoke, a movable contact carried by said yoke, a switch operator movable between limits, an overcenter spring connecting the operator and yoke to move the latter from the former by over-center snap action, a stationary contact confronting said yokemoved contact for engagement thereby, and delay means for holding said contacts in close engagement until the spring has moved well past the over-center position comprising a leaf spring electrically connected to one of said contacts and positioned and formed to engage frictionally over the other, said leaf spring being sized to make -first and break last with the other contact.

2. A snap switch of the type described having in combination, a housing, a Y-shaped yoke, fulcra on said housing for the forked ends of said yoke, a transverse conductor having a limited floating connection with the single end of said yoke, a pair of button contacts on said housing to be bridged by and have face contact with said conductor in the on position of said yoke, a stop for the yoke in the off position, a push. type operator for said yoke slidably mounted in said housing for movement transverse to the axis of said fulcra and on the remote side thereof from said conductor, an over-center spring connecting the yoke intermediate its ends with said operator to provide snap action for the said conductor and means external to said housing guiding said operator at spaced positions to counteract the. lateral displacing force of said spring.

3. The switch of claim 2 in which the portion of said operator within said housing includes spaced prongs parallel to the axis of sliding, a return spring between said prongs and a well in said housing for one of said prongs to guide said operator.

4. The switch of claim 2 in which each housing mounted contact is provided with a leaf spring positioned to engage its end of said bar to frictionally resist movement toward open until the spring effort is substantially greater than at dead center.

5. A snap switch of the biased, single push button type having a housing provided with a top, a push button operable in said housing and projecting a substantial distance through said top near one end thereof, a mounting bracket assembly for said switch having a plate secured thereto against said top and perforated for the passage of said button, a portion of said plate extending backover and spaced from said top engaging portion and having a guiding opening for the passage of said button, wings on said plate remote from said button and a lever pivoted to said wings and extending over and in engagement with said button to operate the same.

6. The snap switch of claim 5 in which said lever and wings have mutually engaging parts adapted to hold the lever in engagement with the button.

7. A snap switch for motor control and the like having in combination, a Y-shaped yoke, fulcra for the ends of the arms of said yoke, a bridging contact bar loosely mounted on and transversely to the end of the leg of the yoke, a switch operator movable between limits, an over center spring interposed between the operator and yoke to move the latter on movement of the operator from one limit toward the other, a pair of stationary contact buttons spaced apart and positioned to be connected to each other by said bridging contact at and to act as one limit of its movement, a leaf spring electrically connected to each button, said springs being spaced apart slightly less than the length of said bridging contact and positioned to engage the ends thereof when it contacts the buttons whereby opening movement of the yoke is resisted until the spring has been moved well past dead center position, said springs making contact first and breaking it last with said bridging contact thereby protecting the contact buttons against damage by arcing.

References Cited in the file of this patent UNITED STATES PATENTS 1,724,675 Meuer et al Aug. 13, 1929 2,146,269 Puerner Feb. 7, 1939 2,191,859 Porter Feb. 27, 1940 2,201,972 Moutray et al May 21, 1940 2,570,281 Russell et al. Oct. 9, 1951

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