US2174868A - Snap switch - Google Patents

Description

Oct. 3, 1939. J COFFEEN 2,l74,868

SNAP SWITCH Filed Dec. 12. 1936 INVENTOR da /v M COFFEEN A TTORNE Y Patented a. a, 1939 UNITED STATES.

PATENT OFFICE 2,114.80: sNsr swn'cn John M. oosesn. New York, N. 1:.

Application Deoember 1:, 1m, Serial No. 115,521;

10 Claims. (cl. zoo-o1 This invention relates to improvements in snap switches.

More particularly it relates to improvements in snap switches capable of making and breaking 5 either heavy or light electrical circuits very qulcklyand emciently, and to do this within very close operating limits.

In recent years there has been an extensive development of devices requiring pressure switches or switches in which relatively small differences in pressure or travel may be utilized as a circuit closing or opening medium.

It is an object of the present invention to provide a switch, of the snap type which lends itself to having the contacts in a non-corrosive and non-oxidizing atmosphere. In accomplishing this object the present invention provides astructure enclosing the contacts in a sealed chamber so that dust, dirt, fumes of various kinds, etc.,

cannot adversely reach the contacts, and a structure in which the enclosed chamber may be purged of oxygen, nitrogen and other adverse atmospheric elements, and, if desired, filled with an inert gas such as neon, argon, helium and the .25 like. A complemental object is to provide such a structure which will be rugged yet small in size.

Another object is the provision of a snap switch which requires but light pressure or very short travel of an actuator in order to be operated, and

80 which is highly responsive to slight differences in pressure or slight extents of travel.

A further object of the present invention is to provide a snap switch which may be produced economically, and which will be accurate and efas flcient over a long period of time and operation.

In a number of the snap switches of the general type and purpose here under consideration which were previously proposed the contacts are aflected by moisture, acid fumes and the like because of their open condition in industrial locations containing acid, moisture and the like. When such switches are corroded because of such factors, arcing takes place and a short life of the switch results.

It is an important object of the present invention to provide a snap switch in which the contacts will be thoroughly enclosed against acid fumes, moisture and the like, to prevent corrosion and arcing and to insure a long life to the snap switch.

It is a still further object of the invention to provide a snap switch of small size which may be of one-way or two-way circuit closing form, and in which either or both theone-way and two-way circuit control may be embodied in the one main out.

,Features of the present invention include the provision of a dished diaphragm peripherically held in a body, with the diaphragm flexed to one 6 side of a neutral point to normally close or open a circuit when an actuator is moved by slight. presure or a slight extent, and in which the diaphragm serves to enclose contacts in a chambered or cavity section of the body. Another feature is 10 the provision of a snap switch structure which may be easily and quickly assembled without critical adjustments, and which may be hermetically sealed if desired. A further feature is the provision of a chamber thoroughly enclosing the 15 contacts so that there is no danger of arcing contacts igniting gas or the like in atmosphere adjacent the snap switch.

Other objects, features and advantages will be apparent or will appear hereinafter. v 20 In the .drawing, which is merely illustrative of the present preferred forms of the invention:

Figure l is a cross-sectional view, taken on line i--l of Figs. 3 and 4.

Fig. 2 is a side view of the snap switch. 25'

Fig. 3 is a sectional view taken on line 33 of Figs. 1 and.2.

Fig. 4 is a plan view of the base member and diaphragm or the lower half of the snap switch.

8. 5 is a cross-sectional view of a modified form of snap switch.

Pig. 6 is a perspective view of a modified form of actuator.

Fig. discloses the diaphragm in various positions. 35

Before describing the present improvements and mode of operation thereof in detail it should be understood that the invention is not limited to the details of construction and arrangement of parts shown in the accompanying drawing, 40

which are merely illustrative of the present preferred embodiments, since the invention is capable of other embodiments, and the phraseol ogy employed is for the purpose of description and not of limitation. 5

Referring now in detail to the drawing, and

to the preferred form of the invention disclosed in Figs. 1 through 4 inclusive, the snap switch comprises a body ill, including a base member ll having a cavity I2 and inner shoulder I3, and so a top member I4 having a cavity I5. These cupped base and top members II and H are preferably made of Bakelite or other molded composition and house the various operating parts of the snap switch in a novel manner. 55

The base member I I is provided with a bore l6 adapted to receive a terminal l6 molded or forced into place with an integral flange 17 against the bottom I8 of the .cavity l2. A terminal screw I9 has a threaded connection 20 with'the terminal I6. A stationary contact 2| may be made integral with the terminal [6 or, as shown, may be in the form of a separate washer-like plate welded, soldered or otherwise secured to the terminal I6.

Another stationary contact 23 may be provided, as is shown best in Figs. 1 and 3, comprising a U-shaped plate resting upon a shoulder 13 in the cavity l2 with an associated terminal 25 projecting through a bore 26 in the side wall 2'! of the base member H. A terminal screw 28 is screw-threaded into the terminal 25. The contact 23 and terminal 25 may be made integral or, as shown, may be more economically made from two pieces soldered or otherwise secured together. If preferred the outer end of the stationary contact 23 may be secured to the base with a small screw 30.

The upper member is provided with an actuator 32, comprising a stud 33 extending through a bore 33' in the upper member I4 and having a screw-threaded connection 34 to a preferably inverted cup-shaped member 36 which is locked thereon by a nut 31. Figure 6 discloses a modifled form of actuator 320. like the form just described except that it is of one piece fibre or Bakelite construction. Intermediate the base member H and the top member I4 a dished diaphragm 38 is provided which is normally flexed to one side of a neutral point, as may be apparent by viewing Fig. 1. The diaphragm is peripherically secured to the body ID by the edges 39 and 40 of the members I I and M respectively when these members are secured together as by screws 42, extending through suitable bores 43 and 44, and associated nuts 45 which maintain the diaphragm in its original shape and set over a long period of time even though it is flexed and snapped in regular operation a great many times. The screws may be dispensed with and the members merely.cemented together as described hereinafter.

As may be seen best in Figs. 1 and 4 a terminal 46 is secured to the outer edge of the diaphragm as by a slot 41 and solder. A terminal screw 48 having a threaded connection 49 serves to conmeet any conventional current conducting wire to the terminal 46. A stud 50 is secured to the center of the diaphragm 38 as by riveting and at its lower end is provided with a movable contact 5| which, as shown, may also be held on as by riveting.

With that form of. the invention shown in Figs. 1 through 4 control of a two-way or three-wire electrical circuit may be advantageously accomplished. The diaphragm is normally flexed into the raised position shown in Fig. 1, whereupon through the stud 50 it carries and maintains the movable contact 5| in engagement with the stationary contact 23 to carry or conduct electrical current from the terminal 46 to the terminal 25 or vice versa, the current being transmitted through the diaphragm 38, stud 5B and contacts 23 and 5|. However, when a load or travel is imparted to the actuator 32 the inverted cup member 36 presses against the dished diaphragm causing it to assume the neutral or almost flat position. Instantly when the dished diaphragm is moved even an infinitesimal amount beyond the neutral position and while it is backed by the cup member 36 in this beyond the neutral position it snaps the movable contact 5| into engagement and into operative condition with respect to the stationary contact. 2|. In this position the circuit is closed between the terminals 46 and I6.

However, when pressure or travel on the actuator 32 is relieved suiiiciently to allow the lower edge 58 thereof to move upwardly beyond the neutral point the diaphragm because of its normal flexed condition immediately snaps the associaed movable contact 51 away from the stationary contact 2| (see Fig. '7)

By viewing Fig. 7 it will be noted that when the contacts engage each other the diaphragm is arrested in a position approximately half as bowed or dished as the normal position thereof, shown in dot-and-dash' lines, and therefore a full snap over which would tend to keep the diaphragm in the down position shown, which would require a. manual push or pull thereof to effect a return, cannot occur. Thus, with the present invention there is always a major force in the diaphragm tending to return it to the raised position. 'However, and of particular importance, when the snap over past the neutral position and toward the lowered position occurs there is a buckling of the diaphragm between the center and the periphery thereof toward the actuator, in the nature of a minor force, yieldingly maintaining the contacts in engagement even though the actuator is relieved thereon a slight extent. When the load on the actuator is relieved a predetermined extent the major force offsets the minor force and automatically returns the diaphragm to the inoperative position.

Thus, it will be seen that the present invention provides a simple and highlyefllcient apparatus to control two circuits, for example, to

effect high and low speed operation on an apparatus when a given set of conditions prevail with respect to the actuator 32. Because the edge 58 of thecupped member 36 on the actuator 32 engages the dished diaphragm 38 away from the center, near the outer edge thereof, relatively short travel of the actuator 32 efiects a considerable travel to the center and movable contact carrying section oi the diaphragm. Theperipherically held diaphragm is maintained in the normal flexed condition over long periods, even though it is snapped many times.

This same switch may be used to fully open and close the circuit; for example, if it is desired to have a circuit normally closed until a predetermined condition occurs current conducting wires are connected to the terminals 46 and 25 only (not to the terminal l6) whereupon the circult is closed all the time that the diaphragm 38 is normally flexed into the position shown in Figure 1. It is normally maintained in this condition until a predetermined pressure or travel is imparted to the actuator 32. When the movable contact 5! is snapped away from the stationary contact 23 the circuit between the terminals 46 and 25 is open.

Similarly if it is desired to have a normal open circuit until a predetermined'condition occurs wires are connected to the terminals 46 and I6 (and not to the terminal 25) whereupon the movable contact 5| is away from the stationary contact l6 providing a normally open circuit. However, when a predetermined pressure or travel is imparted to the actuator 32 the diaphragm 38 snaps the movable contact 5| from the raised position shown in Fig. 1 into engagement with the stationary contact H to close the circuit between the terminals 46 and I. As soon as a minute degree of lesser pressure or travel is imposed upon the actuator 32, allowing the edge I thereof to return an infinitesimal amount beyond the neutral point, the diaphragm and movable contact 5| snap from the stationary contact 2i, and

circuit closing position, back into the raised and circuit opening position.

The various views are of enlarged The entire switch may be made so that it is roughly only approximately an inch square. The diaphragm 3| serves very efiectively to cover the 'cavity i2 and to change the latter from a normally open cavity to an enclosed chamber protecting the various contacts from oxidizing fumes, moisture and other corroding mediums which would tend to cause the switch to arc and have a short life. After assembly of the snap switch is effected with the screws 42 and nuts 45 the assembly may be hermetically sealed by filling a channel Gil with a wax 6| or the like. Showing of the various parts in Fig. l is slightly exaggerated to better illustrate the present invention. In actual practice only a minute travel need be imparted to the actuator 32 in order to move the dished diaphragm to either side of the neutral point.

Lugs 62 may be provided on the base member II to accommodate screws II for connecting the snap switch at. any desired location.

Fig. 5 discloses a modified form of the present invention which is substantially the same as the form hereinbefore described in detail. This form of the invention differs from the former form primarily in the provision of a pivoted movable contact member 64 in the form of a bell crank having a pivot connection 65 on a terminal block 60. Top and bottom members ii and ll of slightly difierent form are provided merely to house the difierently shaped movable contact member 84. Also, the stationary contacts are of slightly modifled form including terminals 61 and 08 connected to springs 69 and I0. Whenthe diaphragm 38a is in the raised position, as shown in Fig. 5, the movable contact member 04 drops into engagement with the contact II to close a circuit between a terminal I! and spring contact ll. However, when the dished diaphragm Ila is pressed beyond the neutral point and snapped beyond the lower point by the actuator 32' it throws the movable contact member '4 into a raised position into engagement with the spring contact 69 to close the circuit between the terminals 12 and 61. As with the first form of the invention the current conducting wires may be connected to any or all of the terminals to pro vide a two-way closed circuit, or to provide an open and closed circuit condition in which the circuit is normally open or normally closed.

In its preferred form, the screws 41 and nuts 45 are dispensed with and the members of the body thoroughly secured and sealed together as by a Bakelite cement or a wax I in the channel 60. Also in this preferred form the sealing ispreferably first effected in the channel 80 approximately ninety per cent around the body, excepting only a space around the terminal 46 at which point oxygen, nitrogen and other adverse and corroding atmospheric elements are evacuated from the chamber housing the contacts, and the chamber in turn is filled with a non-corroding or non-oxidizing medium element, such as inert gases such as neon, argon, helium, either alone or in a combination whereupon the space around the terminal 46 is sealed with wax or cement ii a relatively short space.

to providea fully enclosed and gas-filled chamber for the contacts.

The form shown in Fig. 5 has the advantage of providing a greater extent of travel to the movable contact so that the snap switch may be used to control and carry heavier electrical loads than is possible with the form shown in Figs. 1 through 4 where the movable contact travels through only Also, it has the advantage of a slight resiliency between the movable contact and the stationary contacts so that the contacts remain together during the slight initial movement of the diaphragm before the snap-over occurs. However, the yielding type of contacts may' be also used in that form of the invention shown in Figs. 1 through 4 as will be readily appreciated by those familiar with the art to which this invention appertains.

Other variations and modifications may be made within the scope of this invention and portions of the improvements may be used without others.

Having thus described the invention what is claimed as new is:

1. In a snap switch the combination of a body formed by a pair of cupped members; a diaphragm having a snap action in two directions, normally flexed to one position at one side of its neutral point and exerting a continuous reaction to return thereto when moved to a position at the other side of the neutral point; means to peripherically secure said diaphragm to the cupped members and the latter together; a pusher member engaging said diaphragm, capa bio of pushing the diaphragm over the neutral point-when a predetermined pressure is applied thereto; and contacts electrically clcsed by said diaphragm when it ,is moved to a side of the neutral point.

2. In a snap switch the combination of a body; a terminal; a movable contact; a diaphragm, having a snap action in two directions, normally flexed to a position at one side of its neutral point and exerting a continuous reaction to return thereto when moved to a position at the other side of its neutral point, secured to said body, adapted to carry current from said terminal to said movable contact; a stationary contact;

. and an actuator adapted to operate said diaphragm and movable contact relative to said stationary contact.

3. In a snap switch the combination of a base member having a cavity; a stationary contact in said cavity; a movable contact in said cavity; a diaphragm, having a snap action in two directions, normally flexed to a position at one side of its neutral point and exerting a continuous reaction to return thereto when moved to a position at the other side of its neutral point, adapted to cover said cavity and convert it into a completely enclosed chamber, to protect the contacts therein; an actuator for operating said diaphragm and movable contact; a top member; and means for securing said diaphragm and top member to the base member.

4. In a snap switch the combination of a base member; a stationary contact; a movable contact; a dished diaphragm secured to the base member, having a snap action in two directions, normally flexed to a position at one side of its neutral point and exerting a continuous reaction to return thereto when moved to a position at the other side of its neutral point, and an actuator for operating said diaphragm and movable contact relative to the stationary contact.

5. In a snap switch the combination of a base member; a stationary contact; a movable contact member; a pivoted support for the movable contact; a diaphragm peripherically secured to the base member, having a snap action in two directions, normally flexed to a position at one side of its neutral point and exerting a continuous reaction to return thereto whenmoved to a position at the other side of its neutral point, and an actuator for operating said diaphragm and movable contact member.

6. In a snap switch the combination oi. a base member having a cavity; at least one stationary contact in said cavity; a movable contact; a dished diaphragm, having a snap action in two directions, normally flexed to a position at one side of its neutral point and exerting a continuous reaction to return thereto when moved to a position at the other side of its neutral point; means peripherically securing said diaphragm to the base member with the movable contact substantially at the center thereof, said diaphragm covering and converting said cavity into an enclosed chamber to protect the stationary and movable contacts; and an actuator engaging the diaphragm substantially midway between the center and peripherically held sections thereof to convert a relatively short movement thereof into a relatively long movement to the center of the diaphragm and asscciatedmovable contact.

7. In a snap switch the combination of a base member having a cavity; a fixed contact in said cavity and having a terminal extending through said base member; a current conducting dished diaphragm having a snap action in one direction when a predetermined load is applied thereto and having a snap action in the other direction when the load is partially released a predetermined amonnt, said diaphragm being peripheri-= cally secured to said base member to seal said cavity; a movable contact engageable with said fixed contact in the sealed cavity, movable with and electrically connected to said diaphragm; and an actuating: member for controlling the load on and action of diaphragm to thereby move the movable contact relative to the fixed contact.

8-. In a snap switch the combination a base member having a cavity therein; a fixed contact in said cavity; a dished diaphragm normally flexed to one position at one side 01' its neutral point, exerting a continuous reaction to return to said position when moved to a second position at the other side of its neutral point and having a snap action in two directions, said diaphragm being peripherically secured to said base; a movable contact engageable with said fixed contact in said cavity and movable by said diaphragm; and an actuating member engageable with said diaphragm at points spaced from the center' thereof to control the action of the diaphragm to thereby move the movable contact relative to the fixed contact.

9. In a snap switch the combination of a casing; circuit making and breaking means; a disc having a snap action into operative and inoperative positions in said casing to control said circuit making and breaking means; an actuator; and means for normally maintaining said disc in one of said positions, for maintaining the disc in the other of said positions only while a predetermined pressure is upon the actuator and for returning the disc automatically to the first position when less than said predetermined pressure is applied thereto.

10. In a snap switch the combination of a body; a movable contact; a stationary contact; an actuator; and a diaphragm for moving themovable contact relative to the stationary contact, having operative and inoperative positions, formed to have a major stored force normally urging the diaphragm to the inoperative position and to have a minor force yieldingly maintaining said contacts together when a predetermined force is applied to the actuator, and automatically loosing the minor force and allowing the major force to automatically return the diaphragm and movable contact to the inoperative position when less than the predetermined force is applied to the actuator JOHN Iii. COEFEEN.

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