US3656079A - Thermostatic switch - Google Patents
Thermostatic switch Download PDFInfo
- Publication number
- US3656079A US3656079A US865793A US3656079DA US3656079A US 3656079 A US3656079 A US 3656079A US 865793 A US865793 A US 865793A US 3656079D A US3656079D A US 3656079DA US 3656079 A US3656079 A US 3656079A
- Authority
- US
- United States
- Prior art keywords
- contact
- temperature
- contact carrier
- heater
- mobile
- 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
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Classifications
-
- 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
- H01H37/52—Thermally-sensitive members actuated due to deflection of bimetallic element
- H01H37/54—Thermally-sensitive members actuated due to deflection of bimetallic element wherein the bimetallic element is inherently snap acting
Definitions
- a principal object of this invention is to provide a novel and high current capacity for its physical size.
- Another object of this invention is to provide such a switch which may be assembled in a convenient manner and which is rugged and durable in operation.
- FIG. 1 is a longitudinal sectional view of the present switch
- FIG. 2 is a plan view of the operating parts of this switch, taken along the line 2-2 in FIG. 1 and with certain parts omitted for clarity;
- FIG. 4 is a plan view taken along the line 4-4 in FIG. 3 and showing the base of the switch and the auxiliary heater;
- FIG. 5 is a fragmentary plan view taken along the line 5-5 in FIG. 3 and showing the mounting of the bimetallic member in thepresent switch;
- FIG. 6 is a section taken along the line 6-6 in FIG. 2 and 3 showing the mounting for the mobile contact carrier and the main heater in the switch.
- the present switch preferably is disposed within a housing or .body 10 of a suitable metal, preferably steel, which is closed at its left end in this Figure.
- the opposite end of the housing 10 is closed and sealed by a metal header 11 which carries three terminals 12, 13 and 14.
- Terminal 12 is spot welded to'the outer side of header ll.
- Terminals l3 and 14 extend through the header at conventional glass seals (not shown) which electrically insulate them from the header 11.
- the outer ends of terminals 12 and 13 are connected through conventional wire lugs 15 and 16 (FIG. 2) to individual lead-in wires 17 and 18.
- the outer end of terminal 14 is connected to a lead wire 19 (FIG. 2) by a splice 20 of known design.
- a sleeve 21 of suitable dielectric material extends from the header 11 to the right in FIG. 1 and a suitable potting compound 22, preferably epoxy resin, fills this sleeve to anchor in place the wire lugs 15, 16 and the splice 20.
- a suitable potting compound 22 preferably epoxy resin
- the switch assembly Inside the housing 10, the switch assembly includes a generally L-shaped steel base having a short transverse leg 24, which is spot-welded to the inner face ofthe header 11, and an elongated leg 25 extending perpendicularly away from the header toward the closed end of the housing 10.
- This base 24,25 provides a rigid physical support for the movable operating parts of the switch.
- the header 11- conductively connects the switch base 24, 25 and the switching housing 10 through terminal 12 to the lead wire 17, which is grounded. Consequently, both the switch base 24,25 and the housing 10 are grounded.
- the header 11 24,25 spaced from direct contact with the housing 10.
- a rigid support block'26 (FIGS. 1 and 5) of a suitable dielectric material is secured to the long leg 25 of the switch base by rivets 27 and 28 which are located near diagonally opposite corners of the support block, as best seen in FIGS. 2 and 5.
- the support block has a centrally located, rectangular opening 29 (FIGS. 1 and 5), extending up from the switch base and intersecting a slightly larger, shallow opening 30 at also supports the switch base its upper end. At the intersection of the openings 29 and 30 the support block presents an upwardly facing shoulder 31 which is rectangular in outline. This shoulder provides a seat for a heat-sensitive, snap acting dished bimetallic member 32, which controls the operation of the present switch.
- the top of the bimetal member is the high expansion side and the bottom is the low expansion side.
- the temperature of the member is below a predetermined critical value it has downwardly bowed curvature, as shown in FIG. 1, with its low expansion side convex and its high expansion side concave.
- the differential expansion of the op posite sides of the member causes it to undergo a curvature reversal toan upwardly bowed configuration with the center of the member moving upward from the FIG. 1 position, so that now the high expansion side of the member will be convex and the low expansion side will be concave.
- the member will not return to its original curvature until the temperature has dropped substantially below the value at which it snapped over.
- the bimetal member 32 is held seated on the shoulder 31 by a bowed retainer spring 33 which, as shown in FIG. 2, bears down against a pair of diagonally opposite corners of the member 32, and has ears 33A acting against the underside of the main heater 38, described below.
- a metal contact seat 34 extends up from the long leg 25 of the switch base, passing freely up within an arcuate recess 35 (FIG. 5) in the end edge of the support block.
- a stationary switch contact 36 is attached to the upper end of the contact seat 34 and it projects above the top of the support block 26.
- the contact seat 34 is spot welded to the switch base and the stationary contact 36 is spot welded to the contact seat, so that the contact 36 has an electrically conductive low resistance connection to the switch base.
- cantilevered leaf spring contact carrier 37 and one end of the main heater 38 are clamped conductively to each other and mechanically to the support block. As best seen in FIG. 6, this connection is effected by a shouldered rivet 39 and a pair of metal washers 40 and 41.
- the contact carrier 37 and the main heater 38 are clamped in metal-to-me'tal engagement with each other between the washer 40 and an enlarged annular shoulder 42 on the rivet.
- the shoulder 42 is clamped snugly against the top face 43 of the support block.
- the contact carrier 37 is bent downwardly at 44 in FIG. 3, so that the downwardly facing mobile contact 45 on its free end is resiliently biased into engagement with the stationary contact 36.
- the inherent spring bias of the contact carrier 37 normally maintains the switch contacts 45, 36 closed.
- the main heater 38 is positioned in spaced, generally parallel, heat-transmitting relationship to the bimetal member 32 between the latters high expansion side and the contact carrier 37.
- the main heater 38 is rectangular in plan view, having a substantial thickness and a width which is an appreciable fraction of its length so that it is capable of carrying high current on the order of I50 amperes.
- the main heater has an opening 47 (FIG. 1) which passes the mobile contact 45 freely toavoid metal-to-metal engagement between them.
- the left end of the main i heater is clamped to the cantilever-mounted end of the contact carrier 37.
- the right end of the main heater is spot welded at 46 (FIGS. 1 and 3) to the inner end of the lead-in terminal '13.
- Plunger 48 has a transverse collar 51 which normally rests on top of the main heater 38 around the latters opening 49, and
- the switch has a starting or auxiliary heater 53 (FIGS. 2 and 4) closely overlying the switch base 25, as shown in FIG. 1.
- the right end of this heater is spot-welded at 54 to the inner end of the terminal 14.
- the left end of heater 53 is attached to a projection 55 on the switch base 25, and adjacent this end it presents a generally U-shaped portion (FIG. 4), comprising parallel legs 56, 57 and a connecting bight segment 58, which extends beneath the low expansion side of the bi-metallic member 32 in spaced, generally parallel, heat-transfer relationship to this member.
- a dielectric shield 59 of mica or the like is mounted on the inner ends of the terminals 13 and 14.
- a flexible dielectric shield 60 overlies the operating parts of the switch to prevent their accidental engagement with the housing 10.
- the switch can be temperature calibrated before encapsulating it in the housing simply by trimming the length of the plunger 48 below its enlarged shoulder 49.
- the correct plunger length will provide a positive snap action in closing, as well as opening, the switch contacts 45, 36.
- the plunger length is adjusted so that the switch contacts open when the bimetal member 32 is heated to about 240 F. and they reclose after the temperature of member 32 drops to about 180 F.
- the switch contacts 45, 36 will be closed, completing a-current path through the main heater 38 between the lead-in wire 18 and ground by way of terminal 13, main heater 38, contact carrier 37, switch contacts 45, 36, contact seat 34, switch base 25, header l1 and the grounded lead-in terminal 12.
- the heat produced by the main heater 38 depends upon the magnitude of the current through this current path. This may be the current through the main winding of a motor, for example.
- the heating effect of the main heater 38 is supplemented by the auxiliary or starting heater 53,
- the novel structural arrangement of the present switch enables it to have a high current capacity and a small physical size.
- the positioning of the main heater 38 between the bimetallic member 32 and the contact carrier 37 enables the bimetal member to respond precisely and rapidly to a current overload condition.
- the use of the support block 26 to provide a physical support for the cantilever-mounted contact v carrier 37 and the main heater 38, as well as a support for the bimetallic member 32, contributes to the small size of the present switch.
- the switch Before the switch is'encapsulated in the housing 10, it may be temperature calibrated, as described, by trimming the plunger 48 to the correct length, and it can be checked for current tripping characteristics and ground clearances. After these checks have been made, the entire switch assembly, in-
- eluding base 25, support block 26, bimetallic member 32, main heater 38, auxiliary heater 53, contact carrier 37, switch contacts 45, 36 and header 11, maybe slid endwise into the housing 10, with the dielectric insulator 60 wedged between the top of this switch assembly and the housing 10 to prevent contact between them. Then the header 11 is 'welded to the housing 10, and the sleeve 21, potting compound 22 and sheath 23 are added to complete the assembly.
- auxiliary or starting heater 53 and its terminal 54 may be omitted at some loss in the speed of the switch response to over-heating.
- a mobile contact carrier carrying said mobile contact and biased to a predetermined position which established a preselected positional relationship of 'said mobile contact with respect to said fixed contact.
- a bowed snap-acting temperature-sensitive element which below a predetermined temperature is bowed in a predetermined direction and which reverses its bowed curvature with a snap action when heated above said predetermined temperature
- the improvement which comprises an electrically energizable heater positioned in direct heat-conducting relationship to said temperature-sensitive element between thelatter and said contact carrier and in direct metallic heat and electrical conducting relationship to said contact carrier,
- a mobile contact carrier carrying said mobile contact and biased to a predetermined position which establishes a preselected positional relationship of said mobile contact with respect to said fixed contact
- a bowed snap-acting temperature-sensitive element which below a predetermined temperature is bowed in a predetermined direction and which reserves its bowed curvature with a snap action when heated above said predetermined temperature
- the improvement which comprises an electrically energizable heater positioned in direct heat-conducting relationship to said temperature-sensitive element between the latter and said contact carrier,
- said temperature-sensitive element below said predetermined temperature is bowed to present a concave curvature at its high expansion side and a convex curvature at its low expansion side, and said high expansion side of the temperature-sensitive element faces toward the contact carrier,
- said temperature-sensitive element being a bimetallic member
- said heater having an opening therein
- said force-transmitting member being a plunger engaging said bimetallic member and passing through said opening in the heater
- said contact carrier being a cantilever-mounted leaf spring which is biased to normally position said mobile contact in engagement with said fixed contact
- a switch according to claim 1 dielectric support block supporting contact carrier and the heater and temperature sensitive element.
- a thermostatic switch comprising a. rigid metal base, a rigid dielectric support block on said base,
- a main heater disposed between said temperature-sensitive member and said mobile contact carrier in conducting heat-transfer relationship to the member
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- Physics & Mathematics (AREA)
- Thermal Sciences (AREA)
- Thermally Actuated Switches (AREA)
Abstract
Description
Claims (7)
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US86579369A | 1969-10-13 | 1969-10-13 |
Publications (1)
Publication Number | Publication Date |
---|---|
US3656079A true US3656079A (en) | 1972-04-11 |
Family
ID=25346238
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US865793A Expired - Lifetime US3656079A (en) | 1969-10-13 | 1969-10-13 | Thermostatic switch |
Country Status (1)
Country | Link |
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US (1) | US3656079A (en) |
Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4706152A (en) * | 1985-03-15 | 1987-11-10 | Texas Instruments Incorporated | Protected refrigerator compressor motor systems and motor protectors therefor |
US5729416A (en) * | 1995-05-30 | 1998-03-17 | General Electric Company | Motor starter and protector module |
US10548816B2 (en) | 2010-01-28 | 2020-02-04 | Art Healthcare Ltd. | Method and device of detecting and/or blocking reflux |
Citations (8)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2199638A (en) * | 1937-11-12 | 1940-05-07 | Westinghouse Electric & Mfg Co | Thermostat |
US2309207A (en) * | 1938-10-14 | 1943-01-26 | Honeywell Regulator Co | Electric switch |
US2375967A (en) * | 1941-01-24 | 1945-05-15 | Metals & Controls Corp | Circuits |
US2414531A (en) * | 1940-05-31 | 1947-01-21 | Westinghouse Electric Corp | Multiple heater thermal switch |
US2715168A (en) * | 1952-10-29 | 1955-08-09 | Stevens Mfg Co Inc | Electric switch |
US3004203A (en) * | 1959-03-16 | 1961-10-10 | Texas Instruments Inc | Overload protective apparatus |
US3248501A (en) * | 1962-07-05 | 1966-04-26 | Therm O Disc Inc | Thermostatic control having electrically insulated heater element |
US3431526A (en) * | 1967-01-03 | 1969-03-04 | Texas Instruments Inc | Miniature electrical switch |
-
1969
- 1969-10-13 US US865793A patent/US3656079A/en not_active Expired - Lifetime
Patent Citations (8)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2199638A (en) * | 1937-11-12 | 1940-05-07 | Westinghouse Electric & Mfg Co | Thermostat |
US2309207A (en) * | 1938-10-14 | 1943-01-26 | Honeywell Regulator Co | Electric switch |
US2414531A (en) * | 1940-05-31 | 1947-01-21 | Westinghouse Electric Corp | Multiple heater thermal switch |
US2375967A (en) * | 1941-01-24 | 1945-05-15 | Metals & Controls Corp | Circuits |
US2715168A (en) * | 1952-10-29 | 1955-08-09 | Stevens Mfg Co Inc | Electric switch |
US3004203A (en) * | 1959-03-16 | 1961-10-10 | Texas Instruments Inc | Overload protective apparatus |
US3248501A (en) * | 1962-07-05 | 1966-04-26 | Therm O Disc Inc | Thermostatic control having electrically insulated heater element |
US3431526A (en) * | 1967-01-03 | 1969-03-04 | Texas Instruments Inc | Miniature electrical switch |
Cited By (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4706152A (en) * | 1985-03-15 | 1987-11-10 | Texas Instruments Incorporated | Protected refrigerator compressor motor systems and motor protectors therefor |
US4713717A (en) * | 1985-03-15 | 1987-12-15 | Texas Instruments | Protected refrigerator compressor motor systems and motor protectors |
US5729416A (en) * | 1995-05-30 | 1998-03-17 | General Electric Company | Motor starter and protector module |
US10548816B2 (en) | 2010-01-28 | 2020-02-04 | Art Healthcare Ltd. | Method and device of detecting and/or blocking reflux |
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Legal Events
Date | Code | Title | Description |
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AS | Assignment |
Owner name: UNITED TECHNOLOGIES CORPORATION, A CORP OF DE Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNOR:ESSEX GROUP, INC.;REEL/FRAME:004371/0645 Effective date: 19840815 |
|
AS | Assignment |
Owner name: HAMILTON STANDARD CONTROLS, INC., ("HSCI"), A DE. Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:UNITED TECHNOLOGIES CORPORATION, (A DE. CORP.);REEL/FRAME:004983/0076 Effective date: 19881011 Owner name: HAMILTON STANDARD CONTROLS, INC., ("HSCI"), A DE. Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNOR:UNITED TECHNOLOGIES CORPORATION, (A DE. CORP.);REEL/FRAME:004983/0076 Effective date: 19881011 |
|
AS | Assignment |
Owner name: SENSORS AND SWITCHES, INC., A CORP. OF OH Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNOR:HAMILTON STANDARD CONTROLS, INC.;REEL/FRAME:005128/0415 Effective date: 19881013 |