US1972363A - Snap-acting switch - Google Patents

Description

Sept' 4, 1934 J. A. SPENCER 1,972,363

SNAP ACTING SWITCH Filed April 4. 1932 Patented Sept;`

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John A.Spencer,` Newtonville, Mass., assignorto General Plate Company, Attleboro, Mass., a cof-'- poration of Massachusetts switch,.which iseconomical in manufacture and simple and positive in action. Other objects will 1`6 be in part obvious and in part pointed out hereinafter.

" v Ihe invention accordingly comprises the 4ele.

'ments and, combinations of elements, features of construction, and arrangements of parts which will be exempliiiedin the structure hereinafterv described, and-the -scope of the application of which will'be, indicated inthe following claims.

In the accompanying drawing, in which illustrated several of'various possible embodiments of 25.' the invention,

Fig. 1 .is a plan view of a snapacting switch j embodying .the invention;

Fig. 2 is a cross-section taken substantially on line'2'-2 of Fig;1; and,. Fig-3 is a cross-section taken substanuaiiy on 'line 3 3 of Fig. 1.

Similar reference characters indicate -corre spending parts throughout the vseveral views of the drawing,

In my Patent No. 1,895,590, dated January 81, .1933, fo'r Snap-acting devices (application for which was filed July 26, 1930, and which was thus copending herewith), I have'show-nv an improved form of snap-acting devicel which includes as a 40 feature, radial .corrugations, whereby an increased amount of resilient material is present .in theregion where displacements take place .under change' from one to another position. The present .invention -comprises an electric switch including a thermostat which is an improvement over the radially corrugated device illustrated in said copending application. .The invention will be described principally' by reference to its thermstatic embodiment, that is,` where it performsink response to temperature changes. However, it

will be understood that, even as a'thermostat,

. the invention is fundamentally a snap-acting device.

Referring now .more particularly to Fig. 1, there is illustrated at numeral 1, the interior, dished or` cup or concave 'radially corrugated region comprising. the operative portion of athermostatic embodiment of the present invention. This portion 1 is .preferably formed from a seamless cylinder o'f composite thermostatic metal in 601 the manner. set -forth in said copending applica'- A tion, which comprises, brieily, longitudinally corrugating a cylinder of thermostatic metal and constricting said corrugated cylinder at one end. as well as compressing longitudinally until substantially a truncated concor dished disc is-k obtained.

The .term composite thermostatic metal.is used herein.to dei-lne adnaterial composed of materials having relatively different coeflicients of. thermal-expansion. type of thermostat is frequently termed. bimetallic, The principle' upon which the thermostat operates is that under varying conditions of'hot andcoldone layer of the composite metal will exhibit a relatively greater or less tendency to expand than the other layer, and thereby build up a stress in the bodywhich the two metals form.'

The-stress'thus set up grows with increased temperature until'strains are. effected whereby the disc reverses curvature witha snap. That is, if the Ydisc'or dish xor the like was originally con-1 cave, relative to its original conformation it becomes convex, or viceversa. v

' The 'radial 'corrugations in the present thermo- 8.5

stat; as in the thermostat of said copending application, are advantageous -in that they provide -an increased amount of thermostatic metal in the central portion. of said disc, and, when the thermostat is brought to a condition in which it'is aboutto snap, it eiects an increase in the amount of displaeementthrou'gh which the vcenter of 'the thermostat operates. This increased displace'- ment is highly 'advantageous when the thermostat is utilized, forjexample, in electrical equip- .95. ment, for making and breaking electrical con--` tacts.

- The present invention contemplates the forma-Y tion of a radially corrugated disc such vas illustrated in my copending application, and the 10Q provision thereon -ofA a substantially at, or un-. corrugated rim or circumferential portion 3.. 'A theremostat produced according to the present invention has theiollowing advantages: First, the inherent tendency of the thermostat 105 to expand radially, and thereby to decrease its' kinematic eiciency, is limited and controlled'by the relatively non-expansible rim or conning portion 3. That is, with thermostats of the type a shown in said copending. applicatiom'there is a 110.

tendency upon heating for straightening of the sinuous edge, with the result that the constrictive function of the periphery is reduced a's snap action occurs. Hence the thermostat functions more sluggishly than if the edge were to maintain a more constant restrictive characteristic. The flat rim portion 3 of the present invention, having no corrugations therein, has substantially no tendency to stretch, and it accordingly better serves as a restricting or confining or binding means for the remainderof the thermostat. That is to say, there are no undulations in the periphery to provide resiliency.

The thermostatic element as thus described is provided with certain adjunctive elements for converting it into an electric switch. As shown in the present drawing, these adjunctive elements are analogous to those shown in my Patent No'. 1,718,716, dated June 25, 1929, and comprise a bottom supporting plate 12, and a top supporting plate 1 3, each'having a central aperture there.

through, within which there is located a tubular clamping member 14. The clamping member 14 is provided with an annular shoulder at the bottom thereof and is made substantially longer than the combined thickness of the two plates 12 and 13, to secure the two plates in proper operative position in face to face relation. The periphery of the upper end of the tubular member 14 is compressed to provide an annular portion 15 overf hanging the top plate 13.

The plate 12 is provided with a plurality of spaced openings 16, and the plate 13 is provided with a plurality of spaced'openings 17, the openings 17 being coaxial with lthe openings 16, and of smaller diameter. (See Fig. 3).

A plurality of contact plates 27, 28, 29 and 31 are operatively supported by the supporting plate assembly and are located against the outer surrivet members 32 having an enlarged head 33, andl extending through the respective coaxial openings 16 and 17 in the plates 12 and 13, adisc 34 of electric insulating material, such as mica, serving to insulate the head 33 from the plate 13, and serving also to position the body of the rivet 32 lin the opening 17 and to maintain it coaxial therewith. This construction is more particularly shown in Fig. 3 in the drawing.

The cooperating, or circuit completing contacts 4are mounted on the broad, nat rim portion 3 of the thermostatic disc 1.

The disc 1 is adjustably mounted in substantially parallel-spaced relation tothe supporting plate assembly. This mounting comprises a lshouldered screw-threaded stud 36 that projects through the internally screw-threaded tubular clamping membery 14 and that has a flanged member 37 located close to one end thereof. A nut 38 is provided adjacent to,A

but spaced from, the ange'37, and the disc 1 is loosely mounted between the nut 38 and flange 37 to permit of a turning movement of the stud rela--- vof a stud member 4,3.

order to permit of holding the stud 36 while a lock-nut 41 is tightenedto prevent any further turning movement of the stud 36 -after proper adjustment has once been. made.

A plurality of contact bridging members 42 are supported by the thermostatic disc 1, by means members 42 is adequately described in said Patent 1,718,716, and requires no particularization herein.

To align the disc and base members, a stud 53 is mounted in said base members and projects through an opening 55 in the rim 3 of the disc 1. The contacting members 42 are thus maintained in proper relationship to bridge the members 27,

The construction of the 28, 29, and 31 when the disc 1 snaps to contactclosing position. l

It is to be understood that I am aware that a substantially at rim has a slight capacity to stretch but it is to be noted that such capacity is much less than the corresponding capacity in an undulatory or sinuous rim. In thecase of the flat rim the stretch eiects only a tensile stress,

i whereas in the undulatory'rim a bending moment as for instance independent bindingrims, wires andthe like. It also includes integral and other rims wherein the material is disposed notquite atly but in such a manner that peripheral or lateral stretching at the outer ends of the radial or other corrugations is substantially reduced. For instance, the peripheral band 3 may have stiffening bulges or indentations or the likel which are independent of the radial corrugations. However, the form disclosed is preferable in the present embodiment.

If the invention is to be employed as a simple mechanical snap-acting or overcentering switch, or spring-type switch, it will readily be seen that the use of composite metal is unnecessary, although possible. In such instances, sheet of single resilient metal may be used with success. The action of the device as an overcentering switch needs no further description, as it varies from the thermostatic switch only in that applied external forces replace the self-engendered thermostatic forces in effecting the change of shape desired.

In` view of the above, it will be vseen that the several objects of theinvention are achieved and other advantageous results attained.

As many changes could be made in carrying outthe above constructions without departing" from the scope of the invention, it -is intended that all matter contained in-the above description or shown in the accompanying drawing shall be interpreted as illustrative and not ina hunting sense.

I- claim:

1. A switch including a radially corrugated,

snap-acting thermostat having a relatively nat' peripheral region andv contacting buttons carried on said relatively at portion.

2. -A thermostatic switch unit comprising a radially corrugated sheet of composite thermostatic material, said sheet being provided with an integral confining rimof substantially flat material and contacting buttons carriedon said rim,

3. In an electric switeh, a thermostatic actuator comprising a sheet ofcomposite thermostatic metal having corrugations therein', and means coniining expansion along said corrugations, said means carrying contacting buttons adapted to make and breakelectrical connections according to the relative position of said -actuator.

4. In an electric switch, a thermostatic actu-` ator comprising a disc of composite thermostatic metal, said disc having radial corrugat'ions therein, and an uncorrugated rim portion on said disc, said rim portion carrying contacting buttons adapted to make and break electrical connections according to the relative position of said actuator.

5. An electric switch comprising a base mem ber, terminal pieces arranged on said base member, a thermostatic actuator comprising a sheet of composite thermostatic metal having corrugations therein and formed to have two positionsof stable equilibrium, and having an uncorrugated conning rim portion, means mounting said actueral, uncorrugated rirn portion, means mounting said actuator in spacedrelationship to said base member, and one or more contacting buttons carried on said rim portion and positioned to 1 complete an electric circuit between said terminals on said base portion.

7. An electric switch comprising a base member, terminal pieces arranged on said base member, a thermostatic actuator comprising a sheet of composite thermostatic metal having corrugations therein and formed to have two positions of stable equilibrium, means mounting said actuator in spaced relationship to said base member, and one or more contacting buttons carried on said actuator and positioned to complete an electrical circuit between said terminals on said base portion.

8. An electric switch comprising a base member, terminal pieces arranged on said base meinber, a thermostatic actuator comprising a disc or composite thermostatic metal having radial corrugations therein and formed to have two positions of stable equilibrium, means' mounting said 80 actuator in spaced relationship to said base member, and one or more vcontacting buttons carried on said actuator and positioned to complete an electrical circuit between said terminals on said base portion.

9. In a snap-acting electric switch, a snap-aoting actuator comprising a disc of resilient material having radial corrugations therein, the plane of the central portion .of said disc being displacedy from the plane of the peripheral -portion thereof, the said disc being suitably resilient, whereby upon suitable actuation thereof, it overcenters to assume a position of opposite configuration, and electrical contacting means carried by said disc.

l0. In a snap-acting electric switch, a snap- '95 acting actuator comprising a disc of resilient material1 having radial ,corrugations therein, lthe plane of the central portion of said disc being d isplaced from the plane of the peripheral portion thereof, the said disc being suitably resilient, whereby upon suitable actuation thereof, it overcenters to assume-a position of opposite configuration, and means conning expansion along said corrugations, said means carrying electrical contacting means adapted to make and break electrical connections .according to the relative position of said actuator.

ll. An electric switch comprising a base member, at least one terminal piece arranged on said base member, a snap-acting actuator comprising a disc of resilient materialhaving radial corruga- -tions therein, the plane of the central portion of said disc being displaced from the plane of the peripheral portion thereof, said disc being suitably resilient, whereby upon suitable actuation thereof, it overcenters to assume a position of opposite configuration, means mounting said actuator in spaced relationship to said base member, and at least one electrical contacting means carried on said actuator and positioned to cooperate with f the terminal piece on said base member to control an electrical circuit.

JOHN a. SPENCER.

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