US1679649A

US1679649A - Thermostatic control for electric switches

Info

Publication number: US1679649A
Application number: US723889A
Authority: US
Inventors: Joel R Cook
Original assignee: Westinghouse Electric and Manufacturing Co
Current assignee: CBS Corp
Priority date: 1924-07-03
Filing date: 1924-07-03
Publication date: 1928-08-07
Anticipated expiration: 1945-08-07

Description

Aug. 7, 1928. 1,679,649

J. R- COOK THERMOTATIC CONTROL FOR ELECTRIC SWITCHES Filed July 5, 1924 amoentoz pam m gmtw' Patented Aug. 7, 1928.

UNITED STATES PATENT OFFICE.

JOEL B. COOK, OI CLEVELAND, OHIO, ASSIGNOR, BY HESNE A SSIGNMENTS, TO WEST- INGHOUSE ELECTRIC & HANUFACTURIN G COMPANY, A CORPORATION OF PENN- BYLVANIA.

THERMOSTA'IIC CONTROL Application filed July 3,

This invention is concerned with the control of electric switches and has for its object the provision of a simple, compact and efiicient thermostatic control in an electric circuit breaker.

A more specific object of my invention is the provision of an electric current-carrying bimetallic thermostatic element to comprise a mechanical control for an electrical switch and to constitute, permanently, a part of the circuit controlled b the switch.

Other objects my invention will be hereinafter set forth in the following description referring to the accompanying drawings illustrating a preferred embodiment thereof. The essential characteristics are summarized in the claims.

In the drawings Fig. 1 is a plan View of a simple switch mechanism incorporating my thermostatic control; Fig. 2 is an enlarged side elevation of a thermostatic element; and Fig. 3 is a cross-sectional view taken through the base of the switch along the line 3-3 of 1 and illustrating. a convenient mounting for the thermostatic element.

My invention, as shown in the drawings, may-.be embodied in a switch or circuit breaker in a very simple manner to normally maintain the contacts of the switch closed by opposing the action of a switchopenin means, usually a spring. In Fig. 1, a switc or circuit breaker is shown of the general type disclosed and claimed in my prior application pertaining to an electric switch filed Sept. 18, 1922, Ser. No. 588,755 For convenience in illustration, the switch may comprise a base 6 formed of suitable insulating material and upon which are mounted stationary contacts 7 and 8 which may comprise L-shaped members having outwardly extending contacting portions 9 and 10, respectively. The contacting surfaces thereof may be radially disposed whereby movable contact members 11 and 12 may be mounted to swing about a pivotal center 13. The movable members 11 and '12:

may be mounted upon the free ends of a resilient bridging member 14 insulatingly secured at its center to a revoluble bridge-sup:

porting member16. The

free arms

14 and 14" of the bridging member may thus comprise a resilient supporting means for the r013. ELECTRIC swrrcnns.

1924. Serial No. 723,888.

movable contacts 11 and 12, respectively, to permit proper contact between the currentconductmg members 9, 11, and 12, respectively.

The supporting member 16 may be mounted upon a staff 18 pivotally supported by the base 6, the shaft being actuated in a well known manner by a handle or knob, not shown. To resiliently bias the member 16" spring member 20 may surround a hub portion 16 of the bridge-supporting member 16 with one end secured to the staif and the other end in engagement with an outwardly extendinglug on the supporting member 16. The spring 20 may be tensioned by the manual turning of the stafi' 18 to bring the contacts 11 and 12 into closing relationship with the stationar contacts 9 and 10 respectively. The mem er 16 may be maintained in such position by. the action of a deflectable current carrying bi metallic thermostatic member 25, which may be mounted to comprise a cantilever with the free end 26 thereof serving to engage a projecting member 27 insulatingly mounted upon the projecting lug 22 of the member 16.

The thermostatic member 25, as shown in Fig. 2, may be formed of a bi-metallicsheet to comprise a loop of U-shape, as shown, with the

ends

27 and 28 of the ends of the loop secured to supporting

members

30 and 31, respectively. The latter members may be of an L-shape, as shown in Fig. 3, with a suitable insulating member 34 disposed therebetween, whereby the looped thermostatic member may comprise a permanent part of the circuit controlled by the separable contacts. The mounting of the thermostatic member, as shown in Fig. 3, is accordingly such that lead wire 35 may be connected to a terminal-securing bolt 42 which serves to clamp the supporting members of the thermostatic element to the insulating base 6 with a nut 38 serving as a tightening or clamping medium. The current would thus come'into the switch through the line 35 through the securing bolt 42, through the member 31, traverse the lower. leg of the thermostatic element 25, as indicated by the arrow in Figs. 2 and 3, and return along the upper leg. The current would then pass to .the connected terminal support 30 and thence through the bolt 36 and to a line 39 connected to a securing bolt 41, which clamps the'stationar contact member 8 to the base, and therea terthrough the bridge member 14 to the stationary contact 7 and then out through the line 40 connected to a securing bolt 44.

The thermostat 25 may be formed from a bimetal sheet in a well known manner whereby the inner side may have a greater coefiicient of expansion than the outer side to cause the thermostat to curl or deflect outwardly. Hence, when an overload condition exists in the

line

35 and 40, the resistance of the bi-me-tal comprising the thermostatic element will cause the formation of sufficient heat in the element to effect its outward deflection to release the detent member 27 and permit the spring member 20 to swing the contact-supporting member 16 to open position, whereupon the thermostatic element 25 will immediately cool and assume. its normal position and, upon resetting of the contact supporting member 16, the member 27 will wipe over the inner face of the element, springing it outwardly until the end thereof is. passed by the detent member 27, whereupon it will spring inwardly and retain the element of the switch, as shown in Fig. 1, until 'another over-load condition occurs in the line.

It will be seen that the shape of the thermostatic element is such that current travber whereby thegthermostatic member will erses the length thereof in two directions and that there is no electrical connection between the element and movable parts of the switch where undue arcing or sparking might occur. The element remains connected in the circuit regardless of whether the switch is open or closed andis of such simple form that the resistance and corresponding deflecting characteristics may be accurately predetermined, permitting the element to be manufactured in large quantities without necessitating the calibration of each element to determine its resistance and defleetive characteristics.

I cla1m- 1. In an electric switch the combination of a bimetallic current carrying thermostatic member and a mounting therefor, said member being substantially U-shaped and the mounting comprising a base member and 'a pair of superposed current carrying members electrically insulated from each other and disposed at one side of the vU but in planes parallel therewith, one member being connected to'and supporting one leg and the other the other leg of the thermostatic memextend along the base.

2. In an electric switch the combination of stationary. contact members, swingable ontact members adaptedto bridge the staabutment substantially at right angles with relation to the abutting surface thereof to oppose the swinging movement of the supporting means.

3. In an electric switch, the combination of a bimetallic current-carrying thermostatic member and a mounting therefor, said member being loop shaped and the mounting comprising a base member and two currentcarrying members each being connected to a respective end of the loop member and being in superposed relation in planes parallel to the general plane of the loop whereby the thermostatic member may be suspended in ofiset substan ially parallel relation to the ase.

4. In an electric switch, the combination of a bimetallic current-carrying thermostatic member mounted to comprise a cantilever. said member being substantially U-shaped and the mounting comprising a pair of L shaped current-carrying members electrically insulated from each other and in superposed relation, each member supporting a leg of the thermostatic member in offset but substantially parallel relation to the base.

5. In combination, a thermostatic element forming part of the circuit of an electric switch comprising a looped bimetallic member having legs separated and lying in vertical alignment with reference to a common base, a pair of metallic supporting members individually secured to said le s at their ends and in. overlying relation but insulated from each other, and means passing through such supporting members and adapted to serve as an electric conductor lead for one-of them and to clamp both said members to such base.

6. In an electric switch, the combination of a base, a looped bimetallic member conneetedto permanently comprise a part of the switch circuit, means to 'hold the member with the legs of the loop in vertical alignment with reference to the base and serving to establish connections to the switch circuit whereby the bimetallic member is consignature.

; JOEL R. COOK.