US2632825A - Temperature responsive switch - Google Patents

Description

March 24, 1953 J. A. SENN 2,632,825

TEMPERATURE RESPONSIVE SWITCH Filed-Nov. 2l, 1949 di B INVENToR. 5e x a flm aam i 8| J U R E A 5 E N N l76A A 72A mmm 64 35 ATTRNEYEI Patented Mar. 24, 1953 UNITED TEMPERATURE RESPONSIVE SWITCH Jurg A. Senn, Milwaukee, Wis., assigner to Perfex Corporation, Milwaukee, Wis., a corporation of Wisconsinl Application November 21, 1949, Serial N0. 128,552

11 Claims.

This invention concerns a type of temperature or pressure responsive switch which has for its main object the elimination of destructive 4arcing or frying of the :contacts thru the utilization of a novel latching arrangement.

In the past there has been developed many arrangements for coping with the destructive aroing resulting from slow make and break of contacts. Primarily, the def-ect is remedied by creating a swift or snap action Ito converge and separate the contacts. The over-center spring switch action has proven somewhat successful but is characterized by the requirement that the cut-in and `cut-out points be set relatively ywidely apart, i. e. that the differential setting be relatively large to insure proper Contact pressure, also these arrangementshave :a range of Vanishing contact pressure, for as the over-center spring is carried over center, Ithe conta-ct pressure is momentarily reduced to zero. For purposes of precise and sensitive control some form of latching arrangementhas been found to be more satisfactory.

lContactv arcing on contact separa-tion as such has no relation Ito the contact pressure preceding this event. But persistent high contact pressure up to the point of. contactv separation keeps the resistance of the junction low'and therefore also the voltage drop. Thus less wattage is develope-d at this junction anda colder'contact is the result, which in Iturn hasV .the effect of lreducing the thermal gradientv induced by the subsequent arc on the contacts;

This invention concerns a type' of switch latching mechanism that both eiects a switch open and switch yclosed latching arrangement butk at the same time' increases' the -contact pressure just vprior to attaining these changed positions.

It is a further object of this invention to 'illusf trate a latching arrangement thatis adaptable to many types of actuating mechanisms to pro-w vide a versatile and economical control underr varied conditions and requirements.

For .a more' complete understandingoff'the invention reference should now be had t" the draw ing" in which, l

Fig. 1 isa side view ofone' embodiment' of' the device shown' in switch .closed positionju'st priorV to being latched open;

Fig. 2 is a side view of the device of` Fig. 1 with the switch shown in open position;

Fig. 3 is a side view of a modification of Figs. 1 and 2;

Fig. 4; is a side view of a modification of Figs. 1, 2 and 3;

fiat spring hinge I2.

Fig. 5 is a sectional View taken :along linesV phr-agm assembly and Ia U-shaped spring, theV device itself is of the reverse' acting type, i. e. it closes its contacts on a temperature rise. (In

Figs. 3, 4, 5 :and 6 the actuating element of the device consists of a U-shap'ed bimeta-l.

Referring now to Figs. 1 and 2, the device shown comprises an insulation base 'IIJ having attachedv thereto a U-shaped structure Il by means of a fThe spring hinge I2 is held .to the base I0 by a connector plate I3, washer Iil and screw I5. The spring hinge I2 is biased in a' downward direction to move the U-shaped structurel I ina counterclockwise direction about the screw I-5. The structure II consists of -a U-shaped spring I6" attached to spring hinge I|2 by rivet I'I. .The U-shaped spring IB is biased to converge its ends. Between the leg-sof the U= shaped spring IIS is placed a sealed diaphragm I 8, having an upper .connecting rod lI B'secured -to the upper leg of spring |16k and a ball joint 20 secured to the lower leg of spring' I6, to control the position of the legs of U-shaped spring I6. This diaphragm structure is a sealed unit having a duid iill subject to temperature changes to eiect movement of .the Varm I9 and ball 20. fIhis diaphragm unit is explained 'in detail in application 4Serial Number 600,862, 'lled June'22, 1945, now' Patent Number 2,487,947.

At the left sidov of the base lo another fiatspring hinge 22 is fastened to the base and to al connectorV plate 23 by a washer 24 and a screw 25. The opposite' end of spring hinge 22 is fastened to a contact arm 26 having a contact 21 for engagement with contact 2I which is" fastened to the lower leg of 'spring I6. Spring hinge 22 is biased downwardly to pivot contact arm' 26`in a clockwise direction about the screw 25. Aiso' fastened to spring 22 is an insulatiopiece 28. The'v -v spring 22, contact arm 26 and insulation piece '28 are' secured together by rivet 29. Extending up= wardiy from" the pie-oo 2a is' o. latch 30 fastened byv rivet 3l. The insulation piece 2'8 electrically insulates the U-shaped spring I6 from the cntact circuit. The upper end of latch 3'0engage's with the end 33 of U-shaped spring I6 to rain'- tain the U -shaped' spring I6 in 'the' position shown in2 Fig. 1, holdingV againstl the bias of spiinghig'e Fastened tc the U-shaped spring" I6` by'rivetn I1 is a bracket 34 which supports a range adjusting screw 35. The function of screw 35 is to spread and converge the projecting legs of U-shaped spring I6 and thereby vary the operating or cut-in point of the device. There is also added in the base I6 a stop adjusting screw 36 to permit varying of the differential setting between the cut-in and cut-out points of the device. Two connecting screws 32 and 31 permit circuit connections to be made for a circuit to be controlled.

In the operation as shown in Fig. 1, a temperature decrease affecting the diaphragm I3 is reiiected in a converging action or the legs of U-shaped spring I5 thru the force exerted by the spring bias of spring I6. The leg 33, however, is restrained by the latch 39 from moving in a downward direction. The contact end 2i is free, however, and starts moving upwardly away from the stop 36. The end 2l, which is already in engagement with contact 21, will thereby move contact 21 and contact arm 26 upwardly. Fig. 1 shows this movement after a period of time has elapsed and the movement of contact end 2i has progressed from a point of rest on the stop 36 to the position shown. The quiescent position when contacts are closed has the portion of member I6 carrying Contact 2l abutting the stop 36. Note, that as contact arm 25 moves upwardly, `the spring 22 resists this movement thereby causing increased contact pressure between contacts 21 and 2|. The downward bias of spring I2 is a somewhat negligible factor at this time because it acts on the whole U-shaped structure I I which is not movable downwardly as a unit until the latch 30 releases the end 33. This is effected after a predetermined distance has been traversed by arm 26 and latch 33 is kicked out from under end 33 of spring I6. Then the U-shaped structure II moving as a unit under the bias of spring hinge I2 snaps downward until arm I6 en gages the stop 33. The contacts 2l and 21 snap open because latch arm 33 and arm 26 remain in their raised positions, held by end 33 abutting latch arm 39. Note that the action or breaking contact is accomplished at a point when contact pressure is at a maximum.

With the switch now in Ithe position as shown in Fig. 2 the reverse operation will now be described. In this position (Fig. 2) end 33 acts as the latch to hold the latch arm 39 against clockwise movement under the bias of spring 22. An increase in temperature will now result in an expansion of the diaphragm I3 and the resulting spreading of the legs 33 and I6 by the rod I9 and ball 29. But leg I6 and contact 2i are now abutting the stop 36, therefore movement of leg I6 downward is blocked. Thus the spreading action of ythe diaphragm I3, arm I9 and ball 23 is reflected only in the upward movement of end 33. As end 33 moves upwardly the contact arm 26 and arm 39 are moved slightly in a counterclockwise direction since arm 39 is inclined slightly to the right as viewed in Figs. 1 and 2, this further increases the Itension of spring 22. This action increases the bias of spring 22 in the clockwise ydirection but is not released until the latch 33 clears the latch arm 39 and the contacts 21 and 2 I snap closed.

In Figs. 3 and 5 is shown a modification of Figs. 1 and 2 whereby a U-shaped bimetal is substituted as the actuating mechanism for the diaphragm I8 and spring II of Figs. l and 2 and the device itself has the conventional sequence of operation, i. e. it opens its contacts on a tempera- Iture rise. In Figs. 3 and 5 the insulation base 31 has a U-shaped structure 38 pivotally attached thereto by a nat spring 39. The spring 39 is attached to the base 31 by a washer 40 and a screw CII. The bimetal 132 of the U-shaped structure 38 is secured to .the spring 39 by a rivet 43. The spring 39, like its counterpart in Figs. l and 2, spring I2, is biased in a downward direction.

At the left end of the base 31, two connector plates M and 43A (Fig. 5), two flat springs 45 and 45A (Fig. 5), an insulation piece 46, dat spring 41, and washer 43 are secured by screws 49 and 49A (not shown).

Note, that in Figs. 3, 4, 5 and 6 a contact bridge arrangement is used to eliminate current flow thru the bimetals. This is necessary because, as is well known, current now and the resulting generation of heat aects the operation of thermostatic bimetal.

As shown in Figs. 3 and 5, the lower contact arms 50 and 59A are attached to flat springs 45 and 45A respectively by rivets 5I (one of which is shown). The lower contact arms 56 and 59A are electrically separated but mechanically connected by an insulation bridge 52 which allows for their synchronous movement. The upper contact arms 53 (one of which is shown) are attached to flat spring 41. electrically and mechanically connects contacts 55 and 55A of contact arms 53. The contact bridge 55-5il-55A, engages with contacts 56 and 53A to complete the circuit traced as follows: connector 35, spring 45, contact arm 59, contact 56, contact 55, conductor 56, contact 55A, contact 56A, contact arm 53A, spring 45A and connector 55A. The contact arms 53 and 53A are joined and fastened to spring 41 by rivets 51. Extending upwardly from the rivet 51 is an extended portion 53 of arms 53. This portion 53 constitutes the latch for the end 59 of bimetal 42.

As can be seen in Fig. 5, the lower leg 69 of bimetal 32 coacts with the insulation bridge 52 to move the lower contact arms 59 and 59A in accordance with temperature changes affecting bimetal 42.

Attached to bimetal 42 by rivet 43 is a bracket 6I which serves as a support for a range or operating point adjusting screw 62. The screw 62 adjusts the operating point of the device by varying the distance between the bimetal legs 59 and 59 as does screw 35 in Figs. 1 and 2.

A stop adjusting screw 63 is provided to regulate the extremity of travel of leg and thereby provides a differential adjustment.

In operation, ambient temperature changes affecting the bimetal 42 cause the legs 59 and 65 to ilex in opposite directions for any given temperature change. By way of example, assuming -the fast expanding metal component of member 33 is located on the outside an increase in the temperature will cause leg 59 to flex downwardly and leg 5I) to flex upwardly. Leg 59 is restrained against downward movement by latch 53 but leg 65 will move upwardly engaging insulation bridge 52. Further movement of leg 60 will carry bridge 52 and contacts 56 and 56A upwardly pushing contacts 55 and 55A and their contact arms 53 upwardly. This movement will cause arms 53, and latch 58 to pivot counterclockwise around the point 49 which after a predetermined distance will disengage latch 5B from leg 59 causing the contacts to open with a snap. This operation of the latch mechanism is the same as that previously described in connection with Figs. 1 and 2 except that in Figs. 3 and 5 A conductor bridge 54 'a temperature increase causes the contacts to open while in Figs. l and 2 a temperature decrease causes the contacts to open. Note that in the modification shown in Figs. 3 and 5 no part of the current will flow thru the bimetal 38 because no contacts are mounted on the bimetal.

In the modification shown in Figs. 4 and 6 a bimetal is again utilized as the actuating element but the insulation and conduction bridges are reversed. The insulation base S4 has a flat spring S5 attached by a washer 66 and screw B1. A U- shaped bimetal 5S is fastened to the spring 65 by a rivet @9. Also attached to the bimetal 68 by rivet 69 is a bracket i8 supporting a range adjusting screw 'H similar to screws 35 and 52 of Figs. l, 2 and 3.

The left side of insulation base 54 has two connectors 'l2 and 12A (Fig. 6), two Lfiat springs I3 (one of which is shown) and two washers 74 (one of which is shown) held by screws 'l5 (one of which is shown). To the spring 'i3 is fastened contact arm l5. To one of the springs 73 is fastened contact arm A (Fig. 6). Attached across springs 'i3 is an insulation piece il held by rivets i8. Contact arms .'16 and 15A are fastened to contacts 'i9 and 79A (Fig. 6) respectively. These contacts, 'i9 and 19A, are located physically adjacent to a contact bridge comprised of contact 8%, conductor` 83A and contact SBB (Fig. 6). This contact bridge is insulated from the bimetal leg Si by an insulation strip S5.

Attached to the insulation piece 'Il by rivet S3 is a latch 2. The latch 82, as shown, engages the bimetal leg 84. A stop adjusting screw 85 periorins the same function as in Figs. l, 2, 3 and 5.

The operation of this modification (Figs. 4 and 6) is the same as `in Figs. 3 and 5 and therefore requires no further explanation. The contact structure Si? in this mcdication is physically mounted on the bimetal 8i but electrically insulated therefrom. The circuit to be controlled can be connected across terminals 'i2 and 72A. The circuit through the device can be traced as follows: terminal l2, spring '13, contact arm iii, contact i9, contact Sil, conductor 83A, contact 855B, Contact QA, contact arm SA, other spring 13 and terminal 72A.

From the foregoing description it will be readily apparent that many modifications of this invention are possible and I wish to be limited only by the scope of the appended claims.

What is claimed is:

l. A condition responsive switching mechanism including a base. a U-shaped member in spaced overlying relation to said base, the legs of said member being moveable relative to each other upon a condition change, a stop mounted on said base adjacent one leg of said U-shaped member, first biasing means biasing said U -shaped member against said stop, a first contact mounted for movement by said one leg, moveable means including a second contact engageable with said first contact and a latch member, said moveable means being moveable by said one leg from a iirst position wherein said latch member is in latching engagement with the other leg or" said U- shaped member and said contacts are closed to a second position wherein said contacts are open and said latching engagement is released, said other leg retaining said latch member in said second position, second biasing means biasing said moveable means into said first position, said one leg being moveable toward said other leg upon a change in said condition in one sense to .move

said moveable means from said first position to said second position against the force exerted by said second biasing means, said other leg being moveable upon a condition change in another sense to permit said second biasing means to move said moveable means back to said first position, and adjusting'means for manually adjusting the relative position of the legs of said U-shaped member.

2. A temperature responsive switching mechanism including a base, a U-shaped member in spaced overlying relation to said base, an expansible temperature responsive element mounted within the bight'ofsaid U-shaped memberto provide relative movement between the legs of said member, an adjustable stop mounted .on said base adjacent one leg of said U-shaped member, first biasing means biasing said U-shaped member against said stop, a first contact mounted for movement by said one leg, moveable means including a second contactengageable withsaid iirst contact and a latch member,fsaid moveable means being moveable by said one leg from a first position wherein said latch member is in latching engagement with the other leg Iof said U- shaped member andsaidcontacts are closed to a second position wherein said contacts are open and said latching engagement .is reelased, said other leg retaining saidlatch member in said second position, second biasing means biasing said moveable means into said first position, .said one legr being moveable toward said other leg upon `a decrease in the temperature affecting vsaid temperature responsive element to thereby move said moveable means from said first position to said second position against the force exerted by said second biasing means, said other leg being moveable upon an increase in said temperature to permit said second biasing means to move said moveable means back to said first position and adjusting means for manually adjusting the relative position of the legs of said U -shaped member.

3. A temperature responsive switching mechanism including a base, a U-shaped bimetal member in spaced overlying relation to said base, an `adjustable stop mounted on said base adjacent one leg of said member, first biasing means biasing said member against said stop, a rst contact mounted for movement by said one leg, movable means including a second contact engageable with said first contact and a latch member, said movable means being moveable by said one leg from a first position wherein said latch member is in latching engagement with the other leg oi said member and said contacts are closed to a second position wherein said contacts are open. and said latching engagement is released, said other leg retaining said latch member in said second position, second biasing means biasing said moveable means intosaid rst position, said one leg being movable toward said other leg upon a decrease in the temperature affecting said bimetal member to thereby move said moveable means from said first position tosaid rsecond position against the force exerted by said second biasing means, said 'other leg being movable upc-n an increase in said temperature to permit said second biasing means to move said moveable means back to said iirst position.

Li. A temperature responsive switching mechanism including a base, a U-shaped bimetal member in spaced overlying relation to said base, an adjustable stop mounted on said base adjacent one .leg of said member, first biasing means biasing said member against said stop, a first contact mounted 'for movement by said one leg, moveable means including a second contact engageable with said rst contact and a latch inember, said moveable means being moveable by said one leg from a rst position wherein said latch member is in latching engagement with the other leg of said member and said contacts are closed to a second position wherein said contacts are open and said latching engagement is released, said other leg retaining said latch member in said second position, second biasing means biasing said moveable means into said rst position, said one leg being moveable toward said other leg upon a decrease in the temperature affecting said bimetal member to thereby move said movable means from said first position to said second position against the force exerted by said second biasing mean, said other leg being movable upon an increase in said temperature to permit said second biasing means to move said moveable means back to said first position, and adjusting means for manually moving said legs relative to each other.

5. In a condition responsive switch, an insulation base having mounted thereon at one end a iirst spring member, a U-shaped spring biased to converge its extremities mounted on said nrst spring member and biased thereby in one direction, a stop on said base adjacent the lower leg of said U-shaped spring, a second spring member mounted on the other end of said base, a latch lever mounted on said second spring member' biased thereby in one direction and abutting the upper leg of said U-shaped spring, a movable contact arm mounted on said second spring member, adjusting means for manually adjusting the relative position of the legs of said U -shaped spring, a diaphragm assembly supported between the upper and lower legs of said U-shaped spring to move said legs relative to each other, a first contact mounted on the lower leg of said U- shaped spring for engagement with a second contact on said contact arm whereby converging movement of said diaphragm assembly causes said lower leg to move upwardly carrying said contact and said contact arm upwardly until said lever slips out from under said upper leg causing said contacts to open, and whereby diverging movement of said diaphragm assembly causes said upper leg to move upwardly until said upper leg releases said lever allowing the contact arm to spring downwardly closing the contacts.

6. In a condition responsive switch, an insulation base supporting a switch structure comprising, a first spring member biased in one directio-n, a second spring member biased in said one direction, a U-shaped spring member biased to converge its ends, a lever attached to said second spring member having a latch member abutting one end of said U-shaped spring member, adjusting means for manually -adjusting the relative position of the ends of said U-shaped spring member, a contact arm attached to said second spring member, a diaphragm structure operatively connected to said vU-shaped spring member to diverge its ends under the inuence of condition changes, a stop on said base adjacent one of the legs of said U-shaped spring member, a contact mounted on said U -shaped spring member for engagement with said contact arm whereby converging action of said U-shaped spring results in an upward movement of said contact and a pivotal movement of said contact arm and said lever, whereby said latch member disengages said U-shaped spring member to snap open said contact and said contact arm, and whereby diverging action of said U-shaped spring results in releasing said latch member to snap closed said contact and said contact arm.

'7. A temperature responsive switching mechanism including a. base, a U-shaped bimetal member in spaced overlying relation to said base, an adjustable stop mounted on said base adjacent one leg of said member, rst biasing means biasing said member against said stop, a rst contact movable by said one leg, movable means on said base including a second contact engageable with said first contact and a latch member, said movable means being movable by said one leg from a first position wherein said latch member is in latching engagement with the other leg of said member and said contacts are closed to a second position wherein said contacts are open and said latching engagement is released, said other leg retaining said latch member in said second position, second biasing means biasing said movable means into said first position, third biasing means biasing said first contact against said one leg, said one leg being movable toward said other leg upon a decrease in the temperature affecting said bimetal member to thereby move said movable means from said rst position to said second position against the force exerted by said second and third biasing means, said other leg being movable upon an increase in said temperature to permit said second biasing means to move said movable means back to said first position.

8. A temperature responsive switching mechanism including a base, a U-shaped bimetal member pivotally mounted on said base and biased in one direction, a first contact pivotally mounted on said base, movable means pivotally mounted on said base and biased in one direction, said movable means including a second contact engageable with said rst contact and a latch member, said latch member engageable with one leg of said U-shaped bimetal member, said contacts movable by the other leg of said U-shaped bimetal to effect contact action to a first latching position, and said contacts movable to a second position by reversed action of said U-shaped bimetal to effect contact action to a second latching position.

9. In a temperature responsive device', an insulation base having mounted thereon va U- shaped bimetal in spaced overlying relation to said base, a flrst biasing means biasing said bimetal against said base, a first contact mounted on said one leg and movable therewith, movable means carrying a second contact, second biasing means biasing said movable means against said rst contact, a latch member mounted on said movable means and engageable with the other leg of said U-shaped bimetal, and adjusting means for manually adjusting the relative position of the legs of said U-shaped bimetal.

10. A condition responsive switching mechanism including a base, a U-shaped member in spaced overlying relation to said base, the legs of said member being movable relative to each other upon a condition change, rst biasing means biasing said U-shaped member against said base, a nrst contact mounted for movement by one leg of said U-shaped member, movable means including a second contact engageable with said first contact and a latch member, said movable means being movable by said one leg from a rst position wherein said latch member is in latching engagement with the other leg of said U- shaped member and said contacts are closed to a second position wherein said contacts are open and said latching engagement is released, said other leg retaining said latch member in said second position, second biasing means biasing said movable means into said first position, said one leg being movable toward said other leg upon a change in said condition in one sense to move said movable means from said first position to said second position against the force exerted by said second biasing means, said other leg being movable upon a condition change in another sense to permit said second biasing means to move said movable means back to said rst position, and adjusting means for manually adjusting the relative position of the legs of said U- shaped member.

11. A condition responsive switching mechanism comprising a base, means including a condition responsive element mounted in spaced overlying relation to said base, a spring biasing said means toward said base, a contact-carrying lever pivotally mounted on said base, a member carried by said lever in engagement with a portion of said means when said lever is in a rst position and held in latching engagement by said spring, said means, upon a change in the condition moving said lever to a second position and into latching relation with said member for retaining said lever in said second position, and contacts one of which is moved by said lever another being moved by said means. said contacts being closed when said lever is in said first position and open when said lever is in said second position, and adjusting means for adjusting the magnitude of the condition change required to move said lever from said rst to said second position.

JU'RG A. SENN.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 1,728,785 Claytor Sept. 17, 1929 2,969,625 Rich Feb. 2, 1937 2,146,608 Welle Feb. 7, 1939

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