US1674078A - Thermostatically-actuated switch - Google Patents

Description

June 19, 1928. 1,674,078

. G. o. wlLMs THERMOSTATICALLY ACTUATED SWITCH Filed July 6, 1925 Patented .lune 19, 1928i.

UNITED STATES PATENT OFFICE.

GUSTKAV O. WILMS, OF MILWAUKEE, WISCONSIN, ASSIGNOR TO THE BELIANCE COH- PANY, OF MILWAUKEE WISCONSIN, A CORPORATION vOF WISCONSIN.

THERMOSTATICALLY-ACTUATED SWITCH.

Application tiled July 6,

This invention hasas one of its objects the provision of an improved thermostatically actuated switch in which the thermostatic member is relieved of substantlally all work to thus insure absolute accuracy.

Another object of this invention resides in the provision of an improved thermostatically actuated switch in which a weight actuated by gravity trips or opens a springclosed contact.

A futher object of this invention resides in the provision ot' an improved thermostatically actuated switch in which a weight is supported by the thermostatic member and upon movement' of the thermostatic member from under the weight, due to a temperature change, the weight drops, striking a springclosed contact to break the circuit in which the same is incorporated.

A further object of this invention resides in the provision of an improved thermostatic switch member which is so arranged and included in the motor circuit that the heating element of the unit thereof is always of the same capacity as the'motor,

A still further object of this invention resides in the provision of an improved and 'simplified thermostatic switch device in which the heating element may be readily renewed and all parts are accessible for the purpose of repair or replacement.

lVith the above and other objects in view which will appear as the description proceedS, my invention resides in the novel construction, combination and arrangement of parts substantially as hereinafter described and more particularly defined by the appended claims, it being understood that such changes in the precise embodiment of the herein disclosed invention may be made as come within the scope of the claims.

In the accompanying drawings I have illustrated one complete example of the physical embodiment ot' my invention constructed according to the best mode I have so far devised for the practical application of the principles thereof, and in which:

Figure 1 is an elevational viewof a switch unit, with the enclosing housing' removed, embodying my invention;

Figure 2 is a diagrammatical showing of the wiring of the switch illustrated in Figure 1;

1925. Srial No. 41,676.

Figure 3 is a view, partly in elevation and partly in section, of the thermostatic switch unit in circuit closing position, said view being taken through Figure 1 on the plane of the line 3 3, and

Figure 4 is a view similar to Figure 3 illustrating the switch in open position.

Referring now more particularly to the accompanying drawing, in which like numerals designate like parts throughout the several views, the numeral 5 designates the panel or base member of a motor starting switch ot'that type in which movable contacts 6, 7 and 8 are suitably supported from an arm member 9 of insulating material and carried by an armature 10. The armature 10 is pivotally mounted from the base 5, as at 11, and cooperates with a magnetic coil 12, which, when energized, attracts the armature thereto and holds the movable contacts 6, 7 and 8 in electrical engagement with the stationarycontacts 13, 14 and 15 respectively.

' Lines L1, L2 and L3 are connected with the stationary contacts 13, 14 and 15, respectively, and the movable contacts 6, 7 and 8 are connected with the motor M by the lines M1, M2 and, M3 respectively. When it is desired to incorporate means within vthe motor circuit to break the continuity thereof upon the temperature of the motor exceedinga predetermined degree, the improved thermostatically actuated units 16 and 17 illustrated are included in the lines LP and M2, respectively.

The units 16 and 17 are identical in construction and are preferably mounted upon a single base 18 ot' insulating material, and each include a pair of spaced standards 19 suitably secured to the base by rivets or other means 20 and each having terminals 21 to facilitate the electricalv connection of the same in their respective motor lines. The outer ends of the standards are bent inwardly to form attaching lugs or flanges 22 to which heating elements 23 are electricallv connected.

Each heating element 23 is formed of a length of insulating material 24, preferably of an asbestos base and having a heat resisting wire 25 mounted thereon with its ends connected with terminals 26 secured in the ends of the base. The Wire 25 is preferably bent in the shape illustrated and forms the heating element proper and the terminals 26 provide openings through which attaching screws 27 pass to electricall connect the element to the tianges 22 of t e standard. The wire 25 is preferably coated with a suitable heat resisting cement 28.

Connectin but electrica ings 29, is a guide rod 30 on which a weight member is freely slidable. The weight 31 may be slightly cone-shaped and its bottom is'tapered upwardly and outwardly in the manner illustrated. The-wei ht 31 is freely movable on the guide rod an is adapted to be releasably held at the upper end thereof by a thermostatic member 32 preferably of the bimetallic type and so arranged that at normal temperatures its upper inturned end 33 engages behind the bottom of the weight adjacent to its peripheral edge.A The thermostatic strip is mounted from the lowermost standard 19 and has its lower end passed through an opening 34 therein and secured, as at 35, to a bracket or angular' member 36 fixed by the lowermost standard.

At illustrated, the bimetallic strip or thermostatic member is preferably parallel with the heatin element with its side having the lower coe cient of expansion there adjacent so that a change in the temperature of the element beyond a predetermined degree the standards 19 of each unit,

causes the strip to assume the shape 'illustrated in Figure 4, withdrawing its end 33 from behind the weight and permitting its fall by gravity. The underside of the weight being tapered and brightly polished permits the free movement of the thermostatic member frombehind the same.

As the weight 31 falls, it strikes the lower end 37 of an auxiliary switch, movable contact 38 to disengage its contact end 39 from a stationary contact 40 secured on the base 18 by a terminal bolt 41, breaking the continuity of the circuit, to be later described, in which the auxiliary switch is incorporated. The auxiliary switch member 38 is in electrical connection' with and pivotally supported from aA terminal member 42 fixed to the base member by a terminal bolt 43, and the contact end 39 thereof is normally urged to electrical engagement with the stationary contact by an expansile spring 44, confined between the end 37 of the movable contact and the base portion of the terminal 42, the spring 44, together with the pivotal connection of the contact 38 with the terminal 42, insuring the electrical connection between the movable contact and the terminal. The sprin 44 is held in place by a stud 45 threa ed in the terminal 42 and which provldes an adjustable stop for limiting the opening movement of ,the Contact 38.

ln the drawings, my improved thermoy insulated therefrom by bush- Leraars statically actuated switches have been illustrated as included only iny lines M1 and M2, and the two -switches are adapted to be reset as a single unit by a member 46 in the form of a transverse bar having apertures in its ends which receive the guide rods 30 to slidably mount the same. Fixed to the member 46 at a medial point is a rod 47 which passes outwardly of the housing, not shown, enclosing the complete switch construction so that movement of the rod 47 into the housing raises the weights 31 to permit the ends 33 of the thermostatic members to engage therebehind and hold the same free of the auxiliary switches until conditions within the circuits again flex or bend the thermo- Statie strips permitting the weights to fall by gravity, in the manner previously described.

ln Figure 2, one possible wiring diagram for the switch construction illustrated is shown wherein the stationary contact 40 of the unit 16 is connected with the lin'e L? by a conductor 48 and the terminal 42 of the movable contact 38 thereof is connected with one side of the magnetic coil 12 by a conductor 49. The other side of the magnetic coil 12 is connected with the movable con-y tact terminal 42 of the unit 17 by a conductor 50, and thev stationary contact 40 thereof is connected with the contact 51 of a push button switch 52 by a conductor 53( A conductor 54 leads from the line L2 to the cont-act 55 of an armature.actuated circuit closure from which a conductor 56 leads to a contact 57 of the push button Briefly described, the operation of the device according to theswitch is briefly as follows: With the movable contacts 6, 7 and 8 free of their respective contacts 13, 14 and 15, in which positions they are held either by gravity or other means, the button 60 of the switch 52 is depressed to bridge the contacts 57 and 59, as a result of which the magnetic coil 12 is connected across the lines4 L* and L2 and energized, attractinor the armature 10 thereto and engaging tlie contacts 6, 7 and 8 with their respective contacts 13, 14 and 15, and 'causing the contact 63 to bridge the contacts 62 and 55. The circuit forthe coil when the button 60 is depressed is from 'the line L1 through the conductor 48, the movable contact 38 and stationary contact 42 of the unit 16, conductor 49, coil 12, conductor 50, the movable contact 38 and stationary contact 40 of the unit 17, conductor 53, contact 5l, button `61, contact 59, button 6G, Contact 57, conductor 56, Contact and to the line L2, through the conductor 5i,

After the main line switch has been closed by depression of the but-ton 50, the continuity of the coil i2 is maintained, after the pressure on the button has been removedfrom the Contact 59, through the conductor 58, contacts 62, and 55 of the mature actuated circuit closure, and hence to the line L2 throagh'i-he conductor' Assuming the load on o motor itil shouid be increased to the point tvnere its heat exceeds a predetermined egree, the heatin n e V unit or one or both of t1 e thermostatic switches xviii renect the overload and cause the thermostat ins the itr l manner illustrated lin thermostatic strip of eac i un engaged om behind its adjacent Weight 5l, the same drops by gravity st i i 3T of the movable cori'acty from t f continuity the magnetic coil circuit. Upon deenergization of the coil, the armature 1G moves there-.trom

carrying with the contacts 5, 'i' and 8, and disengaging the contact 63 from the contacts 55 S2, so that upon the temperature of the motor resuming normal the circuits wili remain open until button {Si} is again depressed.

Assuming it is desirabley to stop the motor hi, the button 6l is depressed to brealr` the continuity of the magnetic coil circuit between the contacts 5l and 59, when the armature moves away from the coil, as previously described, disengaging its contacts 6, 7 and 8 from their respective contacts 13,14 and 15.

The heating elementsio the thermostatic switches are readily removable to permit their renewal when damaged or burned out, or to permit their replacement by an element suited for any desired need. It has been found from experience that the best results are Aobtained when the heatin element for any given job requires from iteen to twenty minutes to influence the -thermostatic strip suliiciently to actuate the switch with a twenty-five per cent overload, this relatively long-time element vbeingdesirable in order to accommodate thel customary overloads to which motors are subjected during starting and other running conditions. When the overload is six hundred per cent, however, the thermostatic unit should, for best protection, iniuence the thermostatic element suiiently within six to nine seconds to release the weight and actuate the auxiliary switch.

With the construction illustrated the thermostatic member 32 performs a ininimum of work as in its normal position its end 33 is engaged justiwithin the periphery of the Weight, the undersurface o-ivhieh,

main line rcuit is substantially siniulta y'iption teiten ir. nying drawing, to those skilled nvention oi this at have provided noveland improved ermostatic switch in which the bimetaliic strip or thermostatic member'is relieved of all work to insure ideal operating conditions and one which is reliable in operation, and so constructed as to permit the ready renewal of the heating elements or the changing of the element so that the only variance necessary in order to adapt the switch to motors of different capacities is to provide a heating element of the desired capacity.

What l claim my invention is:

l. ln a thermally actuated switch, a Weight guided for longitudinal movement, a thermostatic member, means mounting the thermostatic member with one end normally in the path of the Weight, the thermostatic member moving out ot the path of the weight upon a predetermined change in temperature to permit movement of the Weight, and a circuit closure adapted to be operated upon'movement of the Weight.

2. In a thermally actuated switch, a Weight guided for vertical movement, a thermostatic member having one end normally engaged behind the Weight to restrain the same against. movement, said thermostatic member being disengaged from behind the Weight upon a predetermined change in temperature to permit movement thereof, the portion of the Weight behind which the thermostatic member is engagedl being highly polished to offer a minimum of resistance to movement therebetween, and a circuit closure operable upon movement of the weight,

3. In a thermally actuated switch, a weight guided for vertical movement, a thermostatic member having one end normally engaged behind the weight to restrain the same against movement, said thermostatic member being disengaged from behind the weight upon a predelerminwl change in temperature to permit movement thereof, the portion of the. weight behind in `the art character appel th `L ell which the thermostatic member is engaged being highly polished and tapered to offer a minimum of resistance to movementv therebetween, and a circuit closure operable upon movement of the Weight. ,y

4. In a thermally actuated switch, a weight guided for vertical movement, a thermostatic member normall engageable behind the weight to releasab y secure the same at one of its limits of movement, the thermostatic member being disengaged from behind the weight upon a predetermined change in temperature to permit the movement thereof to its other limit, and a circuit controlling member' operable by thc weight as it approaches its other limit of movement.

5. In a thermally actuated switch, a weight guided for vertical movement between two points, a bimetallic thermostatic member, means rigidly mounting one end of said bimetallic member and the other end thereof being normally free and engageable behind the weight when at its uppermost point, .the ibimetallic thermostatic member flexing under predetermined temperature changes to disengage its free end from behind the weight and permit its dropping to its other point by gravity, and a circuit closure operable by the movement of said weight.

6. In a thermally actuated switch, a weight guided for vertical movement between two points, a bimetallic themostatic member, means rigidly mounting one end of said bimetallic member and the other end thereof being normally free and engageable behind the weight when at its uppermost point, the bimetallic thermostatic member flexing under predetermined temperature changes to disengage its, free end from behind the weight and permit its dropping to its other point by gravity, and a circuit closure operable by the movement of said weight, the bottom portion of said Weight being tapered upwardly and outwardly and highly polished whereby slippage of the frec end of thethermostatic member from 'behind the weight when influenced by temperature changes is unobstructed.

7. In a thermostatic switch, a movable contact member, .a weight normally held in an upper position and adapted, upon movement to a lower position, to engage the xmovable contact member and actuate the same, a thermostatic member, and stationary means mounting one end of the thermostatic member, the other end of the thermostaticmember being free and normally disposed under the weight when in uppermost position, the thermostatic member flexing under temperature changes to move free of the weight and permit its falling to actuate the movable contact.

8. In a thermally actuated switch, a pair of laterally projecting standards, a guide rod connecting the standards, a weight slidably mounted on the guide rod, a thermo static member normally having a portion thereof in the path of the weight whereby to engage therebehind and releasably secure the same in a position atI the upper end of the t guide rod, said thermostatic member being disengaged from behind the weight upon a predetermined temperature change to permit the dropping of the weight by gravity along the guide rod, and, a circuit rclosure engageable by the weight as it falls on the guide rod.

9. In a thermally actuated switch, a pair of laterally projecting standards, a. guide rod connecting the standards, a weight slidably mounted on the guide rod, a thermostatic member normally having a portion thereof in the path of the weight whereby to engage therebehind and releasably secure the same in a positionV at the upper end of the guide rod, said thermostatic member' being disen-v gaged from behind the weight upon' av pred'etermined vtemperature change to permit the dropping of the weight by gravity along the guide rod, and a medially pivoted contact member having one end normally within the path of the weight whereby the weight movesthe same on its pivot as it falls under the influence of gravity. f

10. In a thermally actuated switch, a pair of laterally projecting standards, a guide rod connecting the standards, a weight slidably mounted on the guide rod, a thermostatic member normally having a portion thereof in the path of the Weight whereby to engage therebehind and releasably lsecure the same in a position at the upper end of the guide rod, said thermostatic member being disengaged from behind the weight upon a predetermined temperature change to permit the dropping of the weight by gravity along the guide rod, a circuit closure engageable by the weight as it fallson the guide rod, and a heating element bridging said standards and arranged in thermal relation with the thermostatic member.

11. In athermally actuated switch, a base of insulating material, a pair of laterally -projecting arm members fixed to the base member in spaced relation, a-heating element connecting the outer ends of the arm members, a guide rod medially connecting the arml members, a Weight slidable on the guide rod,`,a bimetallic thermostatic member interposed between the weight and the heating element and having one end free and normally in the path of the weight member to engage therehehind when in a position at the upper end of the guide rod to hold the same against the influence of gravity, said thermostatic member u on the change in temperature of the heating element beyond the predetermined degree being exed out of IIN) members, a guide rod medially connecting the arm members, a Weight slidable on the guide rod, a bimetallic thermostatic member interposed between the weight and the heatmg element and having one end free and normally in the path ofthe weight member.

to engage therebehind when in. a position at the upper end of the guide rod to hold the same against the influence of gravity, said thermostatic member upon the change in temperature of the heating element beyond the predetermined degree being flexed out of the path of the weight to permit its dropping by gravity down the guide rod, a cir cuit closure interposed between the weight and the insulating base and having a part in the path of said weight and adapted to be engaged thereby asthe same falls, and means operable to move the weight upwardly on the guide rod to its normal position with the thermostatic member engaged therebehind.

13. In a thermally actuated switch, a base .of insulating material, a pair of laterally projecting arm members fixed to the base member in spaced relation, a heating ele-- ment connecting the outer ends of the arm members, a guide rod medially connecting the arm members, a weight slidable on the guide rod, a bimetallic thermostatic member interposed between the weight and the heating element and having one end free and normally in the path of the weight member to engage therebehind when in a position at the upper end of the guide rod to hold the same against the influence of gravity, said thermostatic member upon the change in temperature of the heating element beyond the predetermined degree being tlexed out of the path of the weight to permit its dropping by gravity down the guide rod, a fixed Contact member carried by the insulating base, a movable contact pivotally mounted and normally urged to engagement with the fixed contact, and a part carried by the movable contact and normally lying within the path of said weight to be engaged thereby as it falls on the guide rod whereby said movable contact is pivoted and disengaged from the stationary contact.

14. In a thermally actuated switch, a base or insulating material, apair of laterally projecting arm members xed to the base member in spaced relation, a heating element connecting the outer ends of the arm members, a guide rod medially connecting the arm members, a weight slidable on the guide rod, a bimetallic thermostatic member interposed between the weight and the heat- ,ing element and having one end free and normally in the path of the weight member to engage therebehind when in a position at the upper end of the guide rod to hold the same against the influence of gravity, said thermostatic member upon the change in temperature of the heating element beyond the predetermined degree being flexedout of the path of the weight to permit its dropping by gravity down the guide rod, a fixed Contact member carried by the insulating base, a movable contact pivotally mounted and normally urged to engagement with the fixed contact, a part carried by the movable contact and normally lying within the path 'of said weight to be engaged thereby as it falls on the guide rod whereby said movable Contact is pivotedv and disengaged from the stationary contact, and a member guided on the rod beneath the weight and operable t0 lift the weight beyond the free end of the thermostatic memberto secure thezsame in normal operative position.

In testimony whereof I aliix my signature.

GUSTAV C). WILMS.

Images