US3256406A - Single-curved vane-type thermally actuated switch - Google Patents

Single-curved vane-type thermally actuated switch Download PDF

Info

Publication number
US3256406A
US3256406A US275718A US27571863A US3256406A US 3256406 A US3256406 A US 3256406A US 275718 A US275718 A US 275718A US 27571863 A US27571863 A US 27571863A US 3256406 A US3256406 A US 3256406A
Authority
US
United States
Prior art keywords
leaf
pull member
posture
end portions
switch
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US275718A
Other languages
English (en)
Inventor
Wojcik Edward
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Parker Hannifin Corp
Original Assignee
Ideal Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Ideal Corp filed Critical Ideal Corp
Priority to US275718A priority Critical patent/US3256406A/en
Priority to GB11207/64A priority patent/GB1041368A/en
Priority to SE4707/64A priority patent/SE321885B/xx
Priority to NL6404354A priority patent/NL6404354A/xx
Priority to FR972344A priority patent/FR1391442A/fr
Priority to DE19641465723 priority patent/DE1465723A1/de
Application granted granted Critical
Publication of US3256406A publication Critical patent/US3256406A/en
Assigned to PARKER-HANNIFIN CORPORATION reassignment PARKER-HANNIFIN CORPORATION MERGER (SEE DOCUMENT FOR DETAILS). Assignors: IDEAL CORPORATION
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H43/00—Time or time-programme switches providing a choice of time-intervals for executing one or more switching actions and automatically terminating their operations after the programme is completed
    • H01H43/30—Time or time-programme switches providing a choice of time-intervals for executing one or more switching actions and automatically terminating their operations after the programme is completed with timing of actuation of contacts due to thermal action
    • H01H43/301—Time or time-programme switches providing a choice of time-intervals for executing one or more switching actions and automatically terminating their operations after the programme is completed with timing of actuation of contacts due to thermal action based on the expansion or contraction of a material
    • H01H43/302—Time or time-programme switches providing a choice of time-intervals for executing one or more switching actions and automatically terminating their operations after the programme is completed with timing of actuation of contacts due to thermal action based on the expansion or contraction of a material of solid bodies
    • H01H43/303—Time or time-programme switches providing a choice of time-intervals for executing one or more switching actions and automatically terminating their operations after the programme is completed with timing of actuation of contacts due to thermal action based on the expansion or contraction of a material of solid bodies of one single solid body, e.g. hot wire
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H37/00—Thermally-actuated switches
    • H01H37/02—Details
    • H01H37/32—Thermally-sensitive members
    • H01H37/46—Thermally-sensitive members actuated due to expansion or contraction of a solid
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H61/00—Electrothermal relays
    • H01H61/06—Self-interrupters, i.e. with periodic or other repetitive opening and closing of contacts
    • H01H61/066—Self-interrupters, i.e. with periodic or other repetitive opening and closing of contacts making use of an extensible wire, rod or strips

Definitions

  • One important object of the invention is to provide a snap action switch suitable for use as a flasher switch or the like, having desired operating characteristics which are not substantially affected by normally occurring variations in the dimensions or properties of the component materials or in the processing and assembly of these materials to produce the switch, so that the switch may be manufactured reliably in large quantities by automatic machinery and with minimum need for adjustments by hand.
  • Another object of the invention is to provide a switch construction for use in flasher circuits or the like which enables improved control of the relative duration of the flash and olf times of the circuits and will operate advantageously with little or no perceptible difference between the duration of the first flash and that of succeeding flashes.
  • a further object is to provide a snap action switch which may be readily adjusted to vary its operating characteristics.
  • Still another object is to provide a snap action switch of the vane type having a simple and yet durable construction giving is a relatively long service life.
  • the switches provided according to the present invention make use of an electro-thermally or thermally actuated switching element composed of a resilient vane member of distinctive construction coacting with a thermally expansible pull member so as to be constrained to one switching position when the pull member is cool and to switch itself to another position when the pull member is suitably heated, as by the passage of an electrical current through it to heat it by electrical resistance.
  • the vane member comprises a body leaf of suitably thin and resilient sheet metal or the like, which by being suitably pre-stressed or formed to a naturally curved shape is intrinsically biased toward a natural posture in which it is bowed relative to one axis only into a curvature, preferably having substantially the form of a minor sector of a cylinder, that protrudes to one side of a plane intersection opposite end portions of the leaf.
  • the resilient leaf has the thermally expansible pull member so tensioned over its naturally convex side that the pull member normally constrains it, against its intrinsic bias, into an inverted posture in which it is bowed elastically relative to one axis only into a curve protruding to the other side of a plane intersecting said end portions.
  • the intrinsic bias of the leaf and the expansibility of the pull member are selected so that upon a heating of the pull member to relax its tension, such as by passing an electrical current through it, the pull member no longer can constrain the inversely bowed leaf to its inverted posture; so the leaf then inverts itself toward its natural posture.
  • each inversion of the leaf is readily utilized to effect a switching action.
  • the switching element can be caused to switch quickly from a normal or cool position to a second position in which the leaf has assumed or approached its natural posture.
  • the pull member lies flush against the naturally convex side of the leaf; so the pull member is then cooled and contracted quickly by conduction of heat into the relatively cool body of the leaf. In this way the leaf is returned quickly to its inverted posture for the completion of a switching cycle that can 'be repeated reliably time after time over prolonged periods of time.
  • the inversions of the bowed leaf and the attendant switching motions are caused to take place in each instance with an advantageous snap or toggling action, by providing the vane member with suitable means acting on the opposite ends of the leaf to resist spreading of the leaf so that it must buckle or toggle upon being inverted across the plane intersecting its ends.
  • the vane member may be formed with a side strip joining the ends of the bowed leaf in chordal relation to the leaf at a location adjacent to at least one of its side edges.
  • the strip can be formed out of the same piece of sheet metal as the leaf.
  • the action of the switching element can be easily modified or controlled by making the side strip or strips stretchable under a certain tension applied thereto by the leaf so that a certain desired resistance will be imposed to each inversion of the leaf.
  • FIGS. -1 and 2 are isometric views taken from opposite sides of a snap action switch embodying the invention
  • FIG. 3 is a schematic edge view of the vane member employed in the switch of FIGS. 1 and 2;
  • FIGS. 4-7 are schematic views illustrating successive stages in the snapping movement of the switching element between contact open and contact closed positions.
  • the basic switching element of the switch shown includes a vane member 10 made from a generally rectangular piece of relatively stiff thin sheet metal such, for example, as spring steel in sheet or strip form of about .005 inch thickness.
  • the piece is slotted along one side edge thereof to provide therealong a side strip 16 separated from a relatively wide body leaf 14 by a slot 12, with the side strip joined integrally at its ends to opposite end portions 15 and 17 of the leaf.
  • the body leaf 14 is permanently stressed or set to a substantially cylindrically curved natural posture toward which it is always biased by its intrinsic resiliency. In that posture it is bowed relative to one axis only into a curve protruding to one side of a plane intersecting the end portions 15 and 17, for example, to one side of the plane occupied by strip 16 as indicated schematically in FIG. 3.
  • the side strip 16 is crimped as indicated at 18, so that its normal length corresponds substantially to that of a chord joining the ends of the bowed leaf 14.
  • the vane member when in its natural or unconstrained condition indicated in FIG. 3, it resembles an archery bow having a relatively thin and wide bowed body with the bowstring disposed at one edge of the body, but with the body holding itself bowed instead of being bowed by tension in the string, or side strip 16.
  • the side strip resists spreading of the end-portions 15 and 17 where it joins them together but does not prevent inversion of the curvature of the body leaf 14.
  • the basic switching element includes also an expansible pull member 20 that is trained over and governs the postures of the vane member 10.
  • the pull member preferably is a thin narrow band or wire of an electrical resistance alloy, such, for example, as a flat chromiumnickel alloy wire of the type known as Nichrome, havcurvature inverse to the pre-set natural bowing or curvature thereof.
  • the pull member 20 normally lies substantially in a chordal plane interconnecting the end portions and 17 of the inversely bowed leaf, thus extending over the side 14B thereof substantially as illustrated in FIG. 4 and acting, much as the string of an archery bow, to hold the leaf bowed elastically in the direction opposite to the natural or pre-set bowing thereof, against the intrinsic bias thereof.
  • the length and the electrical resistance and thermal expansion properties of the pull member are readily selected so that when the temperature of this member is increased, as by the passage of an electrical current through it, the pull member Will expand to relax its tension and the bending moment which it exerts upon the ends of the body leaf. The pull member then will no longer overpower the intrinsic bias or shape restoring force of the body leaf, whereupon the latter inverts itself and returns to its own natural or preferred posture.
  • the intrinsic bias of the body leaf applies an increasing tension to the side strip 16, which strip by resisting this tension resists spreading of the end portions 15 and 17 and flattening of the leaf 14 in the course of the return of the latter to its normal posture.
  • the return movement of the leaf therefore is accompanied by a buckling of its thin body, which begins on one side of the plane of the tension of strip 16, as illustrated schematically in FIG. 5, and which upon progressing sufliciently to the other side of that plane causes the leaf to snap with a toggling action to its natural posture, whereby the switching element shown is moved to its preferred position illustrated schematically in FIG. 6.
  • a similar buckling and toggling action in reverse direction occurs upon a contraction of the length of the pull member 20, such as that brought about by a cooling of it from the elevated temperature at which it allowed the body leaf to assume its natural posture. curvature of the leaf is inverted, again with a snap action, and the switching element takes the position to which it is biased by the pull member 20, as illustrated schematically in FIG. 4.
  • the vane member 16 and pull member 20 constitute an effective snap action switching element suitable for many uses. It is particularly suitable for use as the working element of an improved flasher switch such as that shown in FIGS. 1 and 2.
  • the flasher switch includes a circular frame or base 26 of electrical insulating material, to which are secured a prong or terminal 28 and also, as by a rivet 29, a bracket 30 having one end bent downwardly and passed through the base 26 to form a second prong or terminal 32.
  • the other end 34 of bracket 30 is enlarged and supports a mounting element 38.
  • This mounting element is electrically insulated from the bracket, as by suitable dielectric sheet material 36, and is formed with an upstanding arm 40.
  • the switching element is mounted on the free end of the upstanding arm 40, as by a rivet or a spot weld at 42 which fixes the body leaf 14 to the arm at a point disposed toward One end of the leaf 14, considerably to one side of the apex or center of the pre-set curvature thereof.
  • An electrical contact element 48 is fixed to the leaf 14 at a location thereon disposed away from the mounting point 42, advantageously toward the other end of the In this way the bowing or l leaf at a considerable distance to the other side of the apex or center of said curvature.
  • the contact element 48 coacts with a mating contact element 46 which is mounted on the free end of a finger 44 struck upwardly from one side of the bracket 30. The finger 44 so positions contact element 46 that when the pull member 20 is in its normal or cold condition, the body leaf 14 then being held in its reversely bent or inverted posture, the two contact elements 46 and 48 are pressed firmly together in circuit closing relation to form a closed path for conducting electrical current between the terminals 28 and 32 through the thermally expansible pull member 20.
  • the contact elements then connect the vane member 10 with bracket 30, thus with terminal 32.
  • the vane member is at all times connected electrically with terminal 28 through the expansible pull member 20, as by a conductor 50 of low electrical resistance which is secured at one end, as by welding, to substantially the midpoint of the pull member 20 and is secured at its other end, as by welding, to a finger 28a on the upper end of the prong or terminal 28.
  • one end of the conductor may be secured to a tab formed integral with the pull member; or a conductor formed as one piece with the pull member may be provided to connect member 26 with terminal 28.
  • a lesser length of the pull member may be caused to contact the leaf surface, as by forming the end portions 15 and 17 with raised corner portions over which the pull member will extend from its fixed ends 22 and 24.
  • the described coaction of the hot pull member and the relatively cold leaf provides important advantages in the use of the switch.
  • the time required for the cooling or open circuit stage of the switch operation can be made shorter than would otherwise be the case.
  • the length of this interval can be selected and kept in any of various desired relationships to the time provided for the flashing or closed circuit stage of the operation. In other words, various desired combinations of flash and off times can be provided.
  • the switch will operate in the first of its cycles with very nearly the same flash and off times as in succeeding cycles, which contributes to the effectiveness of its use as a flasher switch for the control of warning signals of atuomobiles or other vehicles.
  • the leaf of the vane member Since the leaf of the vane member is devoid of vpre-set crimps or bosses and undergoes its inverting move-
  • the crimping of the side strip 16 in addition to shortening it to approximately the chordal length of the bowed body leaf, gives the side strip longitudinal stretchability and the effect of a tension spring imposing, a certain resistance to the inversions of the curvature of the leaf.
  • the magnitude of this resistance can be set at any of a variety of desirable values by control of the stretch resistance of the crimped side strip. In this way the operating characteristics of the switch can be readily fixed and controlled, as desired in manufacturing practice, without being substantially altered by minor variations commonly encountered in the dimensions or properties of the materials used for the manufacture of the switch or in the precision of assembly of its parts.
  • the switch therefore, can be manufactured to high performance standards with the use of automatic machinery.
  • the crirnped construction of the side strip 16 provides a convenient and easy means of adjusting the operating characteristics of a given switch.
  • a switch made according to the invention is found to operate otherwise than in accordance with prescribed specifications, it may be made to meet such specifications by an alteration of the crimping of the side strip.
  • the mounting point 42'and the contact element 48 may be located at any of a variety of points over its area, provided only that they are spaced apart longitudinally of the vane member so as to give the required separating movement of the two contact elements.
  • the extent of ⁇ this movement can be selected as desired by selection of the longitudinal spacing of point 42 and element 48 on the leaf 14..
  • the pressure of element 48 against element 46 in the closed position of the switch and the motion of element 48 relative to element 46 as these elements make and break contact, can each be similarly selected and controlled.
  • the snap action switch of the invention will thus be seen to provide many distinct advantages in ease and cost of production and in efficiency and durability of operation.
  • a switching element including a vane member comprising a resilient leaf intrinsically biased over substantially its entire area between opposite end portions of the leaf toward a natural posture in which it is bowed in a single-curved form only to one side of a plane intersecting said opposite end portions, and
  • a switching element including a vane member comprising a resilient leaf intrinsically biased over substantially its entire area between opposite end portions of the leaf toward a natural posture in which it is bowed in a single-curved form only to one side of a plane intersecting said opposite end portions, and
  • a switching element including a vane member comprising a resilient leaf intrinsically biased over substantially its entire area between opposite end portions of the leaf toward a natural posture in which it is bowed in a single-curved form only to one side of a plane intersecting said opposite end portions, and
  • said pull member comprising a wire stretched diagonally over said leaf between diagonally opposite corners of the leaf.
  • a switching element including (a) a vane member comprising (1) a resilient leaf intrinsically biased over substantially its entire area between opposite end portions of the leaf toward a natural posture in which it is bowed in a single-curved form only to one side of a plane intersecting said opposite end portions, and (2) strip means extending between said end portions in chordal relation to said bowed lea-f adjacent to at least one side edge thereof to resist spreading of the leaf so that the leaf will buckle upon being inverted across said plane, and (b) a thermally expansible pull member tensioned between said end portions over the naturally convex side of said leaf and normally constraining said leaf against its intrinsic bias into an inverted posture in which it is bowed elastically to the other side of said plane in a single-curved form only from one to the other of said end portions,
  • a switching element according to claim 4 said strip means being stretchable by the tension applied thereto by said leaf as said pull member expands, whereby the in version of the leaf is controlled by the stretch resistance of said strip means.
  • a switching element including a vane member in the form of a unitary piece of uniformly thin resilient sheet metal slotted along a side edge thereof to provide therealong a side strip joining opposite end portions of a relatively wide body leaf formed by the remainder of said piece,
  • said leaf having from end to end thereof an intrinsic substantially uniform curvature biasing it toward a natural posture in which it is bowed between its ends in a single-curved form only protruding to one side of said side strip, said side strip being crimped to shorten it and render it stretchable elastically by the intrinsic bias of the bowed leaf, and a thermally expansible electrical resistance wire tensioned over the naturally convex side of said leaf between opposite end portions thereof and normally constraining said leaf against said bias into an in- Y verted posture in which it is bowed elastically in a single-curved form only protruding to the opposite side of said strip,
  • said bias and the expansibility of said wire being sufficient that upon a heating of said wire by passage of an electric current through it said leaf will invert itself and snap toward said natural posture.
  • said wire being flat and lying in face to face contact with said naturally convex side when said leaf approaches said natural posture, whereby the Wire is then cooled and contracted quickly byconduction o-f heat into the leaf so as to return the leaf quickly to said inverted posture.
  • a snap action switch comprising a switching element as defined in claim 6,
  • first and second terminals a first contact element and a mounting element, all carried by said base
  • said first contact element being electrically connected to said first terminal and said mounting element being electrically insulated from said terminals
  • said switching element being fixed to said mounting element at a point on said leaf toward one end of said left whereby said switching element is movable angularly relative to said mounting element by inversion of the bowing of said leaf,
  • said leaf carrying at a point toward the other end thereof a second contact element bearing against said first contact element when said leaf is in said inverted posture
  • a switching device comprising a resilient vane of electrically conductive material

Landscapes

  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Thermally Actuated Switches (AREA)
  • Breakers (AREA)
US275718A 1963-04-25 1963-04-25 Single-curved vane-type thermally actuated switch Expired - Lifetime US3256406A (en)

Priority Applications (6)

Application Number Priority Date Filing Date Title
US275718A US3256406A (en) 1963-04-25 1963-04-25 Single-curved vane-type thermally actuated switch
GB11207/64A GB1041368A (en) 1963-04-25 1964-03-17 Vane type flasher switch
SE4707/64A SE321885B (enrdf_load_stackoverflow) 1963-04-25 1964-04-16
NL6404354A NL6404354A (enrdf_load_stackoverflow) 1963-04-25 1964-04-21
FR972344A FR1391442A (fr) 1963-04-25 1964-04-24 Interrupteur à action brusque notamment pour dispositifs à éclairs lumineux
DE19641465723 DE1465723A1 (de) 1963-04-25 1964-04-25 Schaltelement fuer eine automatische Schaltvorrichtung fuer Lichtreklame oder Blinkzeichengabe

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US275718A US3256406A (en) 1963-04-25 1963-04-25 Single-curved vane-type thermally actuated switch

Publications (1)

Publication Number Publication Date
US3256406A true US3256406A (en) 1966-06-14

Family

ID=23053522

Family Applications (1)

Application Number Title Priority Date Filing Date
US275718A Expired - Lifetime US3256406A (en) 1963-04-25 1963-04-25 Single-curved vane-type thermally actuated switch

Country Status (5)

Country Link
US (1) US3256406A (enrdf_load_stackoverflow)
DE (1) DE1465723A1 (enrdf_load_stackoverflow)
GB (1) GB1041368A (enrdf_load_stackoverflow)
NL (1) NL6404354A (enrdf_load_stackoverflow)
SE (1) SE321885B (enrdf_load_stackoverflow)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3350527A (en) * 1966-03-21 1967-10-31 Lehigh Valley Ind Inc Fixed load thermomotive flasher with normally engaged contacts

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4434414A (en) 1980-08-04 1984-02-28 Technar, Inc. Snap-acting thermal relay

Citations (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2363280A (en) * 1941-05-14 1944-11-21 Westinghouse Electric & Mfg Co Circuit controller
US2537485A (en) * 1949-04-28 1951-01-09 Tung Sol Lamp Works Inc Control means
US2574869A (en) * 1947-12-10 1951-11-13 Pye Ltd Switch
US2700083A (en) * 1952-03-22 1955-01-18 Fred J Burt Flasher switch
US2712045A (en) * 1953-08-18 1955-06-28 Signal Stat Corp Snap action vane
US2834853A (en) * 1957-04-12 1958-05-13 Essex Wire Corp Snap-acting bimetal device
US2861149A (en) * 1956-02-09 1958-11-18 Sylvania Electric Prod Snap action switch
US2870292A (en) * 1957-06-06 1959-01-20 Hoda Corp Snap action device
US2878340A (en) * 1956-07-05 1959-03-17 Littlefuse Inc Snap acting flasher switch
US3057982A (en) * 1959-09-01 1962-10-09 Grover Products Corp Electric snap switch
US3080464A (en) * 1959-08-06 1963-03-05 Tung Sol Electric Inc Snap acting switch blade
US3098139A (en) * 1961-07-27 1963-07-16 Signal Stat Corp Current operated flasher with voltage and temperature compensation

Patent Citations (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2363280A (en) * 1941-05-14 1944-11-21 Westinghouse Electric & Mfg Co Circuit controller
US2574869A (en) * 1947-12-10 1951-11-13 Pye Ltd Switch
US2537485A (en) * 1949-04-28 1951-01-09 Tung Sol Lamp Works Inc Control means
US2700083A (en) * 1952-03-22 1955-01-18 Fred J Burt Flasher switch
US2712045A (en) * 1953-08-18 1955-06-28 Signal Stat Corp Snap action vane
US2861149A (en) * 1956-02-09 1958-11-18 Sylvania Electric Prod Snap action switch
US2878340A (en) * 1956-07-05 1959-03-17 Littlefuse Inc Snap acting flasher switch
US2834853A (en) * 1957-04-12 1958-05-13 Essex Wire Corp Snap-acting bimetal device
US2870292A (en) * 1957-06-06 1959-01-20 Hoda Corp Snap action device
US3080464A (en) * 1959-08-06 1963-03-05 Tung Sol Electric Inc Snap acting switch blade
US3057982A (en) * 1959-09-01 1962-10-09 Grover Products Corp Electric snap switch
US3098139A (en) * 1961-07-27 1963-07-16 Signal Stat Corp Current operated flasher with voltage and temperature compensation

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3350527A (en) * 1966-03-21 1967-10-31 Lehigh Valley Ind Inc Fixed load thermomotive flasher with normally engaged contacts

Also Published As

Publication number Publication date
DE1465723A1 (de) 1969-04-30
GB1041368A (en) 1966-09-07
SE321885B (enrdf_load_stackoverflow) 1970-03-16
NL6404354A (enrdf_load_stackoverflow) 1964-10-26

Similar Documents

Publication Publication Date Title
US6239686B1 (en) Temperature responsive switch with shape memory actuator
US2777032A (en) Snap switch and blade therefor
US6943653B2 (en) Bistable electric switch and relay with a bi-stable electrical switch
US3707694A (en) Thermally sensitive circuit control apparatus
US4088976A (en) Thermally operated bimetal actuator
US2496135A (en) Electric momentary switch
US3256406A (en) Single-curved vane-type thermally actuated switch
US3699292A (en) Slidable contact member for minature switch
CA1160663A (en) Creepless, snap action thermostat
US3339048A (en) Switch having improved multiple blade assembly
US2861149A (en) Snap action switch
US4398071A (en) Snap-action switch
US2756304A (en) Snap-action device
US3539742A (en) Electrical snap switch having stressed blade
US2834853A (en) Snap-acting bimetal device
US3256413A (en) Wafer thin thermostat
US2706228A (en) Snap action valve
US2513748A (en) Electric switch
US3205328A (en) Thermally actuated single-throw snap-action switch
US4318071A (en) Interface relay for high current equipment
US3288967A (en) Electric switch having improved calibration and adjusting means
US3712970A (en) Single spring switch with wiping action
US2706227A (en) Snap action vane
US3555228A (en) Contact spring synchronizing switch assembly
US2727962A (en) Thermostatic element and switch