US2689287A - Multiple thermally-responsive overload relay unit - Google Patents

Description

Sept. 14, 1954 H. E. SCHLEICHER 2,689,287

MULTIPLE THERMALLY-RESPONSIVE OVERLOAD RELAY UNIT Filed March 20, 1953 Patented Sept. 14, 1954 MULTIPLE THERMALLY-RESPONSIVE OVERLOAD RELAY UNI T Harold E. Schleicher, West Hartford, Conn., as-

signor to The Arrow-Hart & HegemanElectric Company, Hartford, Conn., a corporation of Connecticut Application March 20, 1953, Serial No. 343,552

This invention relates to thermally-responsive relay switching devices; and more particularly to overload relays for a plurality of lines employing interchangeable heater elements in the different lines which influence identical bimetallic elements that may be separately adjusted and that act upon a single releasing member, individually or cooperatively.

An object of this invention is to provide a device of the above-mentioned type as an integral unit which can be connectible in the power lines and used as a component of electro-magnetic switching apparatus of either remote or adjacent control.

Another object is to provide a device of the aforesaid type wherein a single contact is released which acts also as the sole means to latch itself and the releasing member in tripped position.

Another object is to provide a device having theaforesaid characteristics which is of simple unitary construction, having a minimum number of parts and which can be economically manufactured and assembled.

Another object is to provide a device having the aforesaid advantages and characteristics which nevertheless will be accurate in operation and of rugged construction to stand heavy overloads through the heater elements without deleterious effect on its operation.

Another object is to provide a device as aforesaid in which the thermal generating parts of the several lines are interchangeable from the front and are also interchangeable for like parts of different rating, and which are nevertheless isolated from each other mechanically and electrically.

Another-object is to provide a device of the aforesaid type having manually resetting means readily available from the front of the device.

Other objects and advantages of the invention will become apparent as the invention is described in connection with the accompanying drawing.

In the drawing:

Fig. 1 is a plan view of a device embodying the invention.

Fig. 2 is a bottom view of the device of Fig. 1.

Fig. 3 is a transverse section view taken along line 3--3 of Fig. 1.

Fig. 4 is a perspective view of the rocker element used in the device of Figs. 1-3. V

Fig. 5 is a perspective view of the bimetallic element and shield used in the device of Figs. 1-3.

Fig. 6 is a perspective view of the manual reset button used in the device of Figs. 1-3.

12 Claims. (Cl. 200-116) Referring to the drawing, the parts are mounted in a molded insulating base In whichhas molded into its upper surface three parallel elongated cavities Illa, lob and "1c running from one end to the other of the base. The walls of the cavities serve to isolate each bimetal from its neighbor. Similar bimetallic strips 20 are mounted in the bottom of each cavity, one end of each strip being secured to a mounting bracket 22 which in turn is secured to the base by bolts. The mounting bracket 22 may be stamped from sheet metal into oblique angular shape as indicated in the Fig. 5 and may be provided with an adjustment screw 24 threaded into one leg. The end of the screwis adapted to press against one end of a small flat oblique-angled pivoted lever 23 set into a slot in the side of the base in such way that the other end of the lever is pressed against the underside of the bimetal strip 20 near the point of its securement to the mounting bracket 22. By tightening up or loosening the adjustment screw 24, the free end of the bimetal 20 is caused to move slightly and in that way its position may be adjusted.

At opposite ends of each cavity Hm, I [lb and H10 are located stamped sheet metal wire terminal members Ha, Ha, I2b, Mb etc. for connection to the power lines. Connected with one terminal located above the bimetal 20 in each cavity is a metallic plate [8 provided to shield the bimetal from a heater coil I1. Each coil may be located in a ceramic hood or housing It above the plate [8 in its own cavity. The heater coil and its housing are of usual construction and are connected across the terminals H11 and Ma, I22; and Nb, etc. The bimetallic elements 20 are preferably made identical so as to be mountable recessed to receive a rocker element 3!! of irregular form as illustrated best in Fig. 4. Preferably this rocker element 30 will be molded from insulating material and will be mounted upon a pivot pin 3| passing lengthwise through the rocker element and having its ends seated in 3 bearing recesses [r molded into the bottom base of the insulating base Ill.

The rocker element is provided with three spaced fingers 33a, 33b and 330 respectively extending laterally thereof in position to be engaged by the ends of the free bimetallic elements 20. The rocker element is normally biased in the direction opposite to the pressure exerted by the bimetallic elements when they bend.

Referring to Fig. 3, the right end of the bi metallic elements will bend downwardly when heated. This causes the rocker elements to pivot in a counterclockwise direction. tension spring 38 provides a bias for the rockor element 30 by having one end engaged with a spring anchor lug 32 molded upon the rocker element while the other end of the spring is anchored to a metal pin 39 molded into the insulating base and extending from the bottom face thereof;

The rocker elementis designed to cooperate with and cause operation ofa spring contact strip 0' which may be stamped from resilient conductive thin sheet metal. One end ofsaid resilient contact strip 40- (the left endin Fig. 211' is between the bottom of the base ill and a stamped sheet metal terminal bar 44 by a screw bolt 45 which passes through the endof the terminal and the end of the spring contact 40. A contact button 42- of good contact such as silver is mounted upon the spring contact 40 near its free end in position to engage acombined contact and terminal member 46 stamped from sheet metal L-sh-ape and secured to the bottom of the base ii by screw boltsc spring contact-40- is provided with a nor-- mal inherent bias away from the fixed content and terminal member 48-. In order tohold the spring. contact in engagement with the fined contact 48,. there isprovided upon the rocker member 30 ii -lateral extension designated gen erally by 34 and acts as holding element or latch. The latch- '34 is preferably molded" upon the rocker 3minthe form illustrated in Fig.4 with aheadportiomfli ataxia-shoulder adjacent there tohavinga top surface and a side surface 31. the: bimetallic members are cool and the movable contactstrip 40 has its button 4! in engagement with the fixed contact 46, the end at theoontaot strip will lie flat upon title surface 36 of the latch member 34a The side of the head 35 on the latch: member. prevents the spring. 88 from pulling the rocker member tar in clockwise direction (referring to Fig. 3%.. This clockwise rotation is also halted: by the engagement of the fingers 33d, 33b and 3h their respective bimetallic elements.

The terminals We and 14a; W2) and Nb etc. are=oonnecuibie in the power lines of an electriccircuit to'engage the coils H separately in each. line. The heat generated in each: coil by an overload current thus the bimetals with it. Upon the occurrence of an overloadin any one oi the 'threerlines'comn-ciled by, the device, or in all-three, the-coil W in the affected line or lines will up; The: heat will) be tmnsmitted thrwgh plate" 18 to the bimetallic element 20: Upon heating, thebl metallic element will: have its right and (referring. to Fig. 3) bend downwardly pressing against one-"or anotheror fire-imam "a; 88!) or 33c. Uponenent with tite f'mgca.

the rocker -30: will be caused to pivot iri coufiter .A coiied clockwise direction whereupon the surface 38 of the latch element 34 will move away from the end of the spring contact 40. Thereupon the spring contact due to its normal bias and resiliency will move away tram the fixedcontact IG breaking ihe circult controlled by thbse confacts. (See dotted position of Fig. 3). This circuit ordinarily will be a control or signal circuit not carrying full load current.

"is prevented from returning to its previous position, despite cooling of the bimetala by the engagement of the end of the movable contact strip 40 with the side surface 31 of the latch extension 34. This engagement prevents the biasing spring 38 from reversely moving the rocker 30. Hence the contact strip "40 not only functions as a movable contact but also as a latch in these circumstances.

In order to reset the device after the bimetallic elements have cooled, there is provided a manual reset button 56 which preferably is molded from insulating material in form as illustrated in Fig.6. The button has an upper portion which extends thrcugha passage molded through thebase from the top to the bottom surface. with the top end of the button ing above the top of the to be available from the front or top of the base. its bottom or inner end abuts the inner surface of the contact strip (0". Hence by pressing on button the contact 40 is moved toward and is caused to engage 'fi'xed contact-4t. At-thesame time the end of' the strip 46 moves over the side surface- 31 of the shoulder on the latch extension 34' until it reaches the top surface 38 otthe shoulder. Thereupon under theurge 0t spring 38' the rocker 3a snaps in clockwise direction (Fig. 33'. Thereafter the surface 36 holde-the contacts engaged as before.

In tripped pocition,- i e. the positionv (dotted in" Fig 3) after the rocker has caused to move by heating. of the bimetallic elements the spring contact 40 pressing. against the lower or inner end of the manual reset button causes that button to move upwardly. To limit the upward movement, the button 50 is provided at its mid-portion: with lateral enlargements formingshouldersil After the fixed-andmovqable contacts have separated; the shoulders I engage with ashoulder (not visible) withinthe Passage through which. the buttonpanel. In this way, the reset battomis kept fromm ingout of the base in an wawamd directiom-' It is likewise limited in its downward movement by engagement with-- the ccntactwr From the foregoing, it will be observed that it one or another ofthe bimetale under the effect of the/heat generated lathe heater mile 11,. the rocker element is caused to pivotband permit the-fixed and movable contact sweeperate; andtheyare held apart-by the rocker men It even; atter the binetale-cook After metals have cooled, the manual reset buttcnemdy be depressed to cause the fixed and-mcwable obnto; engage again. .At the same? time; the spring will cause the rocker 30 to -M ln clockwise direction (Flea 2 8811 3) caueing'ithe surface to overlie-the endot the movaiblecbntact 40, thus holding the contactr dofid when the manueL-reset button-"ls" released.

Thus, I havepmviuec wmpisrem er umt liremally l espflfime miafis'fliich unit-18 adapted to be asse tions iir' amj anciepuw simmer-circuits are uiilt connected to electmmag'fletw switching apparatus. The sevice is compact and similar parts in adjacent cavities are alike for manufacturing economy. Moreover, the heater coils may be interchanged with like parts of different current ratings, so that they may not only be interchanged from one cavity to another but may also be exchanged for differently rated coils. Thus, the heaters may be of the same or different rating in different lines to accommodate the unit to all variations of possible use. Further the device is made mainly from stamped parts which may be readily manufactured with a maximum of economy and may be assembled with ease. Moreover, the foregoing advantages are all achieved while reserving maximum accuracy with rugged construction. Since the current-carrying parts of the main lines are insulated physically and electrically from the current-carrying parts of the contacts of the auxiliary or control circuit 40 and 46, burnout damage to the heater coils from a short circuit in the main power lines may be accomplished without affecting their replacement and function of the device.

Although the contacts 40 and 46 are illustrated as being normally closed, it will be obvious to those skilled in the art that it is within the scope of the invention to apply it to normally open contacts which Would become latched closed upon the heating of the bimetallic elements.

Many modifications within the scope of the invention will occur to those skilled in the art. Therefore I do not limit the invention to the specific form of the embodiment illustrated and described.

What I claim is:

1. An electric relay switch comprising an insulating base, a plurality of thermally responsive elements in parallel arrangement on one side of said base in cavities, means on said base isolating each element from its neighbor, fixed and movable contacts on the opposite side of said base, a rockable member pivotally mounted on said opposite side of {said base and engaging with one of said contacts to hold it in one position, said rockable member being moved by one or more of said thermally responsive elements to release said contact when one or more of said elements are heated.

2. An electric relay switch comprising an insulating base, a plurality of thermally responsive elements on one side of said base, relatively movable contacts on the other side of said base normally biased into one position, a rockable member pivotally mounted on said other side of said base and movable in position to maintain one of said contacts in position against said bias, said rockable member being rockable by said thermally responsive members to release said contact, and means on said rockable member to maintain said contact in another position regardless of the condition of said thermally responsive members thereafter.

3. An electric relay switch comprising an insulating base, a plurality of thermally responsive elements on one side of said base, relatively movable contacts on the other side of said base, a rockable member having latching means thereon, means pivotally mounting said rockable member on said other side of said base, said rockable member being movable in position to latch one of said contacts in position againts said bias, said rockable member being rockable by said thermally responsive members to release said contact and latch it in another position regardless of the condition of said thermally responsive members thereafter.

4. An electric relay as claimed in claim 2 having manually operable resetting means to cause said rockable member to move into said positionagainst-said-bias.

5. An electric relay as claimed in claim 4 wherein the resetting means comprises a member passing through the base and accessible from said first-mentioned side of the base.

6. An electric switch as claimed in claim 3 having a manually operable resetting means to cause said rockable member to move in position to latch said one contact in said position-against-saidbias.

'7. An electric switch as claimed in claim 6 wherein the resetting means comprises a member passing through the base and accessible from said first-mentioned side of the base.

8. An electric relay switch comprising an insulating base, a plurality of thermally responsive elements on one side of said base, relatively movable contacts on the other side of said base, a rockable member pivotally mounted on said other side of the base and rockable to latch said contacts in one position, means biasing said rockable member toward said latching position, said thermally-responsive members when heated moving said rockable member from latching position, and one of said contacts engaging said rockable member after said movement from latching position to prevent said biasing means from retuming said rockable member to latching position.

9. An electric relay switch as claimed in claim v8 having manual resetting means extending through said base for said rockable member and contacts and accessible from the front.

10. An electric relay as claimed in claim 9 wherein the thermally responsive elements are separately connectible in different lines of an electric power line and the contacts are connectible in a control circuit, said base being formed to provide a shield between adjacent thermally responsive elements and between them and the contacts.

11. A compact electric relay unit as claimed in claim 8 wherein the thermally responsive elements are arranged in isolated parallel relation, and said base being formed to provide barriers between adjacent elements and a barrier between them and the contacts on the opposite side, and a resetting button for said contacts passing through said base between two adjacent thermal elements.

12. An electric relay switch as claimed in claim 8 having individual adjustment means for the individual thermal elements to move the ends of said thermal elements relatively to said rockable member, said adjustment means being available from the front of the base, and manual resetting means extending through said base for said rockable member and contacts and accessible from the front.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,108,812 Fisher et al. Feb. 22, 1938 2,286,965 Johnson June 16, 1942 2,418,537 Wood Apr. 8, 1947

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