US2250437A

US2250437A - Refrigerator control switch

Info

Publication number: US2250437A
Application number: US124661A
Authority: US
Inventors: Lawrence M Persons
Original assignee: AUTOMATIC CONTROL CORP
Current assignee: AUTOMATIC CONTROL Corp
Priority date: 1937-02-08
Filing date: 1937-02-08
Publication date: 1941-07-22
Anticipated expiration: 1958-07-22

Description

July 22s 1941 L M. PERsoNs 2,250,437

REFRIGERATOR CONTROL SWITCH Filed Feb. 8, 1937 4 Sheets-Sheet 1 July 22, 1941. L M. PERSONS 2,250,437

REFRIGERATOR CONTROL SWITCH Filled Feb. e, 1937 sheets-sheet s- /N VEN fof?. LAWRENCE M PERS OMS,

4/65 5)/ MAW froPA/EK July 22, 1941. M PERSONS 2,250,437

REFRIGERATOR CONTROL SWITCH Filed Feb. 8, 1937 4 Sheets-Sheet 4 Patented July UNITED s'rs'rissu PATENT ori-ics 4:esima-i BEli'IGEBA'loB` CONTROL SWITCH Lawrence M. Persons, St. Louis, Mo., assigner, by

menne assignments, to Automatic Gontlol Corporation,y St. Louis, Mo., a corporation of Del- Application February s, 1937, sei-isi No. 124,661

'(c1.-. zooss) y $8 Claims. Thepresent invention relates to heat-responsive switches in general, and .in particular to y switches for use on refrigerator controls.

This present switch includes a mlnuteiy adjustable heat-responsive device oi the diaphragm, solid-charge type. The heat-responsivev mechanism operates a switch thatis desiened to. control a cooling unit. interrelated with the mechanism just recited is a further control which has several stages in which it operates. It-operat lto an oiP' position wherein it acts' as a complete may be held constant but that of the oth varied.

It is a further object to provide means to attain the last-named adjustment by large increcut-out maintaining the4 main switch open; it

' operates to an intermediate or "on" position whereinthe main switch is responsive only tothe heat-responsive device and it operates to a de anisms together with their several adjustments ments, and also a line degree of change,

whereby the may be set quickly and It is. a further object to combine in a mechanism oi' this kind a switch providing inherently a temperature diilerentlal between its point o! opening and point of closing.

It is a further vobject of the invention to provide a diil'erential screw adjustment in connection th the solid-charge diaphragm by heat-re- Italia further object of the invention to providesmechanismmaintaining the switchinone position ot its operation. together with mechaare combined into a single. small andI compact housing made possible by theirparticular construction.

It is an object ofthe invention to provide in a single instrument a.- switch normally controlled by a heat-responsive 'device with supplemental means selectively to maintain the switch at in-` I' A operative position, to permit it to'operate or tol maintain it subject to an additional operation of the heat-responsive means, after whichkaddil tional operation, it is automatically released.

It is a further object 'of the invention-to provide a switch of the type describedhaving a mechanism. o o It is a further object of the invention to provide a switch ot this type with the 'diaphragmheat-responsive mechanism, together with' ii means disconnected from said diaphragm, but adapted to be actuated thereby, and an adjust- F18. 4. v. ns-

diaphragm .type solid-charge heat-responsive 49 nism interrelated with said heat-responsive means automatically to release said mst-named mechanism upon a predetermined temperature condition.

Otherobjects will appear in the description to ensue. Y Fig. 1 is a iront elevation oi the switch.

Fig. 2 isa view iron thetop, with a casing partly broken away. V

Fig. 3 is a horizontal section on the line 3-3 oi ls a vertical section on the line 4 4 ot is another vertical section on the line l: txs'ansverse vertical section on the line a view o f the cams taken on the line Fig. 6. Fig. 8 is a plan view with the casings in section. Fig. 9 is a transverse, vertical sectiontalreny on the line 9 9 otFlg. 8. Fig. l0 is a section on the line l-lll o! Fig. 9. Fig.` 11 is a lsectiorion the line Ii-l-Ii of Fig. 9. Fig. 12 lis-a view of one of the cams taken from the iront side.

Fig. 13 is an edge view oi' said cam. Fig.' 14 is a view o! the'cam taken from the back side of the device.u

both actuated by the heat-responsive means, with y means to adjust both together so that both opr- 'ate-:stt temperatures varied by the same amount,

or to adjust one of them relative to the other, so

that the temperature of operation oi one of the'm Fig. 15 isa view oi the defrost switch in defrosting position.

Fig. 16 is a view of the switch similar to Fig. 8 but in defrost position with the switch locked open, as indicated .by the line lS-IB of Fig. 15. Fig. 17 is a front view of the switch knob in the off position.

Fig. 18 is a view similar to Fig. 3 but with the switch locked in ofi position. v

Fig. 19 is a section on the line |9|9 of Fig. 3.

The device embodies a front. panel 25 having an inset 2| therein projecting behind it. To this panel is secured the front plate 22 of the switch proper, which front plate has an inset 23 adapted to lie against the inset 2| of the panel 20. To this frontplate 22 is secured a main housing 24 of the switch in a manner to be described. A diaphragm heat-responsive means 25, to be described in detail, is secured to the back of the housing 24. A huid-containing tube 25 extends from the diaphragm means 25 and has a bulb 21 at the outer endthereof. An electric circuit plug 28 is likewise secured to the back of the housing 24 and has two

terminals

29 and 30 that run through a switch inside the device, as will be described.

The inset 2| has therein a dial 3|, this dial, the panel 20, and the front plate 2l all being held .together by screws 32. This dial plate has operating therefrom two

knobs

33 and 34 that have pointers or

indicators

35 and 36, respectively, on them. 'I'he indicator 35 on the switch knob 33 operates to the positions designated ofl 011, and defrost, as shown. The indicator 35 on the adjusting knob 34 operates over a cooling speed scale 31. These operations will be explained more in detail hereafter.

Within the outer housing 24 there is located a thereof, is a U-shaped switch contact element 83. The connecting portion of the U-shaped contact element is shown turned at a sharp angle to the legs thereof, as at 84." On the free leg of the element 83 is a contact point 85 giving a limited movement against the inherent resilience of the element 53. The rivet 5| establishes electrical contact between the terminal 38 and the switch contact element 53.

'raus it may be seen that the semmai u is in electric circuit with the U-shaped switch element be domed as at 1|, and corrugated. Screws 12 bridge 48 consisting of side panels 4| and 42, and

a back panel 43. This bridge is open at its ends and the side panels are secured to the iront plate 22 by turned-over lugs 44 that project through the plate. A plug socket 45 is secured at one end ofl the back panel 43. 4The plug socket 45 fits through a cut-away portion 48 in the outer casing 24. The bridge 40 has an opening therethrough slightly smaller than the outer dimensions of the socket 45. I'he socket 45 has a cutaway portion providing a shoulder 41 that engages against the end of the bridge 48 bordering the opening therethrough. Reference to Fig. 6

will show that the socket 45 extends laterally be- 545 yond the limits of the opening in the bridge 48 so as to rest on the bridge. l

An insulating plate 48 is located inside the back plate 43 of the bridge 45. plate and the bridge is an insulating shield or liner 49 having a depending projection 50 thereextend through the flanges' of the member 1|) through suitable holes in the outer casing 24 and are threaded into back panel 43 of the bridge 40. Closely fitted within the 'member 18 is a flexible cup-like member 13, the lateral walls of which are welded to the lateral walls of the cup-shaped member 18 so that the top part forms a flexible diaphragm. The tube 28 extends in through a corner of the cup-shaped member 15 and thereby communicates with the space between the member 18 and the flexible diaphragm element 13. As will be understood, the bulb 2 1, the tube 25 and this space between the member 18 and the diaphragm are completely iilled with fluid, preferably liquid. Normally the diaphragm 13 is contiguous throughout with the cup-shaped member 18 except when forced away by increase in the volume of the liquid.

Between this on, for a purpose to b e described. A pair oi' rivets 5| extend through the socket 45, the in sulating plate 48, and the liner 49, clamping them together and holding them all rigidly against the bridge 40.

The underside of the socket 45 is cut out, as at 52. It likewise has

holes

53 and 54 extending vthrough it. The terminal 28 extends through the hole 53 and through a corresponding opening 55 in the switch plate 48 where it merges with the switch member .56 from which it is stamped and of which it is an integral part. 'Ihis switch member 55 is U-shaped in cross-section (Fig. 8) and is secured rigidly to the plate 48 by a rivet 51, this rivet obviously supporting the terminal 28.

The other terminal 38 has a laterally extending base into which it merges as an integral part. 'I'his base is mounted on the outer face of the switch plate 48 by means of rivets 5| and 52. i

The cut-out portion 52 in the socket 45 provides room for the base 60 of the terminal 35 and the several rivets described. O`n the inner face of the switch plate 48 and maintained thereagainst by the rivet 8| passing through one of the legs Opposite the power means 25, there is an inset portion 15 formed on the front plate 22. This inset portion has an opening 15 therethrough. Seated within the inset 15 is a plate 11 having

arcuate slots

18 and 18 therein. Screws 88 and v8| are threaded into the portion 15 and hold the plate 11 in position, it being adiustably rotatable by virtue ofthe arcuate slots, The plate 11 has a central non-circular opening 82 therein, here shown as hexagonal. A hexagonal internally` threaded sleeve 83 fits snugly within the opening 82 and is thereby prevented from rotat.- ing. This sleeve nts freely and rotatably through the opening 15 in the inset portion 15 of the front plate 22.

An externally threaded hollow differential screw hasv threads 85 engageable with the internal threads on the sleeve 83. The screw projects beyond the sleeve 83 and on this project-A ingportion has external threads 81 that have slightly less pitch than the threads 85. 'Ihe threads 81 engage on corresponding internal threads on a sleeve 88. The said sleeve 88 passes through a flanged hole 88 in a cup-shaped member 85 that has a pressed fit in the back panel 48 of the bridge 48, it overhanging the portion 43 by a flange 8|.

'I'he sleeve 88 has a flanged head 82 threaded to receive a correspondingly threaded plug 88 having a kerf 84, by means of which it may be adjusted. The screw 85 and .sleeve 88 being hollow, access to the kerf 84 is had through them after removal of the knob 84 which is fastened to the outer end ofthe screw 35 by means of a set screw. The sleeve 88 is slotted as at 85. It likewise is slotted as at 85 whereby a tool may be inserted for its removal. Adjacent its inner end the sleeve 88 has opposed dat

portions

91 and 98 that slip within the correspondingly shaped flanged opening 89 on the cup 90 thereby being prevented from rotary motion relative thereto although not precluded from axial mo.-

tion. Between the iianged head 96 of the sleeve 88 and the cup 90 is a compressionspring 99 acting to force the sleeve 88 outward, and, as will be shown, to cause the screw 93 to contact with the flexible member 13.

From the foregoing it will be seen that the relation between the ilexible member 13 and the assembly, including the plug 93, the lsleeve 88 and the screw 81, is controlled by set screw 93 and the handle 34.

As shown in Fig. 10 the inset 15 on the front plate 22 has extending therefrom a prong |00. This prong has an upstanding end that is engageable within an arcuate groove |02 (Fig. 11) within the handle 34. This groove is somewhat less than 360 in extent and permits the handle to turn within the range and compass by the grooves |-1 of the dial 31, but stops the adjustment at these two extremes.

The'sleeve 83 hasa rounded end over which ts a correspondingly rounded washer |05. The washer thus may be seated against the sleeve at various positions. A main lever |06 has upturned ears |01 through which extends a pivot shaft |08 secured to the side walls of the bridge 40. This lever |06 has-upstanding abutments "|09 pressed therein, they extending upwardly from opposite sides of a hole |'|0 that fits around the screw 81 whereby the lever |06 crosses the screw. The

abutments |09 on the lever |06 rest against the washer |05 and are held there by means to be described. Thus, as the screw 85 moves downwardly, in Fig. 3, the washer |05 is withdrawn and, by means to be described, the lever 06 is caused to follow this washer. In the showing of Fig. 3, the lever is in its downward position.

Extending from the lever |06 and forming a part thereof is an insulating plate 'I'his plate has at the outer end thereof a U-shaped bracket ||2 .threaded to receive a set screw ||3. The bracket ||2 is secured to the lever4 by the bent over prongs shown in Fig. 4.

'I'he previously mentioned switch plate 56, being U-shaped, has thereon upstanding ears ||5. A switch blade member 6 of U-shaped crosssection (Fig. 6) has an opening ||1 therein whereby the member ts over the switch plate 56. A blade is secured to the member ||6 and forms part thereof. The opening |1 provides an internal edge ||8 engageable in opposed notches |9 in the flanges ||5 of the switch plate 56. 'I'he blade of thev member ||6 extends between the two 'flanges |5 and carries at its outer end a contact point |20 that is movable through an opening in the top of the member I6. The contact point |20 hasv a head |2| that limits the movement of the blade away from. the member ||6. opposed notches |23 in the iianges ||5 opposite the notches I9, and at its other end by a tongue and slot connection, fits in a turned up end |24 on the member ||6. The member |24 is of such length that it will strike a stop element |25 secured to and extending from the insulating plate the securing means comprising a rivet |26. An insulating element |21 is secured also by the rivet |26 and has a projecting portion extending A bow .spring |22 engages at one end in upwardly adjacent the insulating member 50.

It may be seen from the foregoing that when the lever |06 pivots in a clockwise direction in the drawings the screw 3 presses on the member ||6 at a point very close to the pivot edges within the notches ||8. This action tends to lift the contact point |2| away from the contact point 65, the action being opposed by the bow spring |22. When the contacts are freed a suitable amount, the extension |24.will strike the stop |25 and stop the movement. The details of this operation will be given subsequently.

The foregoing description relates to the main switch operation in response to increase of fluid volume back of the diaphragm 13. The additional control, including the defrost switch mechanism will now be described.

A second lever |30 has turned up ears |3| through which extends a pivot shaft |32 secured to the side walls 4| and 42 of the bridge member. This lever |30 has an enlarged opening |33 therein permitting the lever to pass across the sleeve 85. This lever has upstanding abutments |36 pressed therefromon opposite sides of the opening |33. The abutments |36 extend oppositely to the abutments |09 on the main lever |06 and contact the lower end of the sleeve 88. A coil spring |31 surrounds the sleeve 85 and is disposed between the levers |06 and |30 to hold them apart. This arrangement maintains the abutments 09 against the washer |05, as previously intimated, and causes the lever |06 to follow outward movement of the sleeve 83 produced by expansion of the diaphragm 13. Outward movement of the sleeve 88, that is to say, toward the front of the device, by virtue of its contact with the abutments |36, forces the lever |30 in a clockwise direction. Movement in the reverse direction of the sleeve 88 permits the lever |30 to move in a counterclockwise direction under influence of the spring |31.

The lever |30 has a turned down end |40, this end appearing on a projection |4| extending laterally from the end of the lever. A third lever |42 is pivoted to the side walls 42 of the bridge by means of a pivot |43. A spacer element |44 maintains the lever outwardly from the wall. The pivot |43 has a headed extension |45 thereon around which are disposed convolutions of a coil spring |46. One end of this spring rests against the back 43 of the bridge as at |41. The opposite end of the spring engages in a notch |48 of the lever |42. The spring is so tensioned as to urge the lever |42 in a counterclockwise direction, referring to Fig. 16. Or, in other words, it is urged'so that its free end is at all times as far toward the front plate 22 as possible. 'I'he lever is bent and oil'set, as shown in Figs. 4 and 16, so as to clear the other mechanisms. At its free end the lever has a down-turned point |56 having a. sloping edge 5| and opposite thereto an inturned prong |52.

A iianged opening |53 is formed in the front plate 52. 'I'he knob 33 has a projection |54 thereon that extends into the opening |53. This projection is provided with a rst shoulder |55 onto which is 'tted a cam |56. There is a second shoulder |51 about which fits a second cam |58. This latter cam is shown in detail in Figs. 12-14. A headed screw |58 is threaded into the projection |54 and holds the several members in place on the knob. The cam |56 is iixed to the knob 33 to rotate therewith. whereas the cam |58 is rotatable relative to the knob. A lug |60 is struck up from the front plate 22 and engages in a slot |6| within the cam |56, thus limiting the rotation thereof. The cam |56 has at one point of the periphery thereof a depending ear or dog |62, for a purpose to be described.

The cam |58 is likewise provided with two oppositely upstanding cam edges |61 and |68. The cam face |61 has an increasing height as shown in Fig. 2. The cam face |68 slopes as shown particularly in Fig. 3 and has a notch |69 at the apex thereof. This cam likewise has a radial edge |10 that, upon rotation of the knob, is adapted to pass ahead of the inturned end |52 on the lever |42 to permit the lever to drop, as shown in Fig, 16. A coil spring |12 surrounds the hanged opening |53. As shown in Fig. 'I this coil spring has opposite ends |13 and |14, the ends being overlapped so that there is always a tendency for them to come together. In the neutral or on position, shown in Fig. '1, the two ends are on opposite sides of the lug |60 on the front plate 22. These ends, however, project out; far enough so that they may engage the lugs |62 and |63 on the two cams in a manner to be described.

By reference to Fig. 4 it may be seen that the front cam |56 is somewhat larger than the back cam |58. The cam |56 is provided with an edge |15 substantially radial which provides an arcuate section shown at |16 and terminating approximately at the down-turned lug |62, which section |16 is of lesser radial extent than the remainder of the cam. 'Ihis provides a space into which the point |50 of the lever |42 may drop in one'position of operation, as shown in Fig. 16. The other end of the cut-away portion |16 likewise permits relative movement between the two cams since the downturned lug |63 of the cam |58 may move within the space thus provided.

Referring to Fig. 4 and remembering that the rotation of the cam |58 is limited by the action of the xed lug |60 within the slot |6|, it will be observed that the slot and lug are so related as to permitv slightly over 90 movement of the cam |56 ineither direction from the position of Fig. 4. Rotating the knob 33 counterclockwise in Fig. 4 first will carry the cams |56 and |58 to such a point that the edge |15 of the cam |56 is behind the sloping portion and the point |50 of the lever |42. It will be observed that at this portion the periphery at |11 of the inside cam |58 is inside the periphery of the cam |56. Consequently, the cam |58 will not affect the point |50 of the lever. Upon continued counterclockwise rotation of the knob 33, the edge of the cam |58 will pass behind the projection |52 of the lever |42. When this occurs the action of the spring |31 will cause the lever to drop, whence it will act as a lock to hold the cams in this position upon release of the knob.

Reverting to the neutral position shown in Fig. 4, if the knob 33 is turned clockwise therefrom the cam |56 will be moved approximately 90 and will carry with it the cam |58. When the cam face |68 of the cam |58 comes into contact with the projection |80 of the lever the cam |58 will temporarily be stopped. The cam |56 will continue until the pin |65 engages the other end of the slot |64 after which further motion of the knob 33 will force the cam |58 to follow. By this means the cam. edge |68 will be moved under the projection |80 until the projection engages within the notch |69. It will be held in this position until released by rotating the knob 33 counterclockwise. During this lastnamed operation the cam |56 will constantly be beneath the point |50 of the lever |42 so that the said lever is maintained in its upper position.

As has been stated, the spring |12 urges the cams to the neutral position shown in Fig. 7. One of the two ends of this spring is always hooked over the lug |60. When the knob 33 is rotated clockwise, referring to Fig. 4 (counterclockwise in Fig. '7), the lug |62 on the cam |56 draws the end |14 clockwise while the end |13 is maintained against the xed lug |60. Consequently, there is a constant urge by this spring to return the knob to its neutral position. If this clockwise rotation is continued until the notch |68 is engaged over the projection |80 the switch will remain in the position thus attained, since the strength of the coil spring |12 is insuflicient to withdraw the notch from the projection. When the knob is turned counterclockwise in Fig. 4, the lug |62 on the cam |56 will carry the end |13 with it while the end |14 is maintained against the lug |60 so that the spring again urges the cams to the neutral position. However, when this action is carried to the point that the extension |52 Aon the lever |42 engages over the edge |10 of the cam |58, the spring will be held inactive, since it is of insunicient strength to overcome this lock. When the lever |42 is released, the spring immediately returns the knob to the neutral position.

'I'he operation of the entire mechanism is as follows:

If the switch is mounted on a refrigerator thc bulb 21 will be located at a-point, the temperature of which is to be controlled. The switch may be mounted at a convenient, accessible point in the refrigerator. A circuit to a compressor motor or other suitable part of the refrigerating mechanism is connected to the

terminals

28 and 30 so that these terminals and the switch are in series with such circuit.

It will be understood that this switch is operated within a certain fixed temperature range. The various adjustments provided, including the knob 34, do not widen or narrow this range. but shift it bodily up or down, as the case may be. The particular point within the range at which the switch will operate is determined by the setting of the knob 34.

The adjustments or calibrations of the instrument are arranged as follows. If it be desired to have the main switch close at 30 and the defroster to release at 40, the knob 33 is then moved to the defrost position, locking the switch open. The bulb 21 is then brought to 40, the temperature at which the defroster should release. With the knob 34 removed, a screw driver is inserted through the screw 65 and the sleeve '86, and the set screw 93 is turned in or. out until the lever |30, acting upon the lever |42, just trips the latter, relieving the cam |56 so that the knob 33 returns to the on position, allowing the switch to be free. Following this, the bulb is reduced to 30, the temperature of operation of the main switch for a given setting of the knob 34. vThen the plate 11 is turned to rotate the sleeve 83 in or out until the washer |05, against which the lever |06 is urgedby the spring |31, just permits the lever |06 to open the switch. The screws 80 are then tightened to maintain this adjustment. The knob 34 is secured to the screw 85 with its index 36 atthe proper graduation.

' Should subsequent adjustments be necessary the switch setting may be changed by moving the plate 11, this not changing the temperature at which the defrost releaseoperates. As soon as the plate 11 isvflxed, and save for the operation of the knob 34, the temperature difference between the switch and the defrost is iixed. If the screw 93 is then moved both the defrost and switch temperatures of operation are changed together, by the same amount, their diiference not altering. If the defrost is to be changed and the switch be held at the same value, the screw 93 is adjusted, and then the plate 1,1 turned to .offset the change produced on the switch by adjusting the screw 93. ,Y

After these adjustments are made to set the device it is evident that the temperature at which the switchoperates may be changed by turning the vknob 34. 'I'his operation, however, does not change the defrost setting. It is also evident that the adjustment of the switchalone may be effected by removing the knob 34, and turning the screw 85 until the washer |05 attains the proper position, after which the knob is replaced. This operation'is the same as that of the plate 11, in that it produces relative rotation between the sleeve 83 and the screw 35. This manner of adjustment is more micrometric than merely moving the plate, since it works through the diierential screw and may beaised to obtain ,a tine setting supplemental to that produced by adjusting the plate 11.

The set screw I3 on the switch is preferably adjusted as the device is originally assembled. Ii!

subsequent adjustment is necessary the outer housing 24 can be removed by removal of the several screws 12 and a wrench or ratchet screw driver may be applied to the set screw.

Let it be assumed that the device is cold and the switch open. Then, if the liquid heats, expanding the diaphragm frontward, the washer |05 will be withdrawn from the lever |06, so that the spring |31 moves the lever. This'correspondingly withdraws the screw H3, whereupon the bow spring |22 moves the switch blade ||6 toward closing the contact |2| with the contact 65. l

As the blade closes the moment produced by the spring |22 increases, whereby the switch seeks to close more rapidly. The moment tends to act backwardly against the leverl |03 and with great magnitude, owing to the large .mechanical advantage in reversing the levers ||6 and |03. As it is an increasing force, it produces more movement than is permitted by the movement of the washer |05, and this movement is absorbed by the inherent resilience of the lever |06-l so that this lever is deformed by a certain amount.

This capacity of the lever |06-| to absorb the movement of the blade 6 permits the switch to close with a snap action. After the switch closes further movement of the washer |05 relieves the internal stresses in the lever |06| As the switch closes the contact |2| is forced against the top of blade ||6, displacing the end of the blade ||8 deforming the same against its resiliency, i

With the switch closed the refrigerator unit will operate, it being in ser-ies with the switch. As soon as the mechanism is cooled to its desired limit, as determined by the setting of the knob 34, the switch will again open. In this action the diaphragm 13 moves backward, as does the screw 85and-the washer |05. The lever |06 will be moved, forcing the screw ||3 against the switch blade ||6 and tending to open the contacts, This action is resisted by the movement y of the bow spring |22, now at its maximum value.

As thewasher |05 acts uponthe lever |06-||| against this resistance the resilience of the lever permits it to absorb some of this movement, un-

y til the inherent righting force of the lever, times itsflever arm, equals the moment of the spring |22 at this, its maximum, value. Further movement of the lever |06 will thendisplace the blade I i6 and remove the contact |2| from the contact y 65. As thelever ||6 moves away the moment of the spring |22 decreases Iby virtue of a reducing lever area, whereupon the stored energy in the lever |06-|j| releases to open the switch with a snap action, until the depending end |24 strikes the stop |25, this being prior to dead center. Hencethe spring |22 always applies some closing moment to the switch.

If the points 65 and '|2| are welded, the opening action will part them. In this action the initial movement of the blade I|6 does not move the contact |2|, since the latter is mounted-on the blade H8, and lost motion is provided between them. The blade 6 is then permitted to get a running start, whereby the increased energy of motion is applied to break the contacts. Additionally, the mounting of the'contact 05 on the free leg of the U-shaped member 63 permits it to follow the contact |2| a short distance. In so doing, however, the member 53 is deformed so as to set up torsional and shearing forces in addition to tension, that readily break the weld. Since the weld causes greater resistance to opening, added energy will be stored in the lever |06|||, so that, when the break `does occur, the opening will occur with a v ery rapid action.

It is necessary in a switch of this type to have a differential between the temperature oi opening and that of closing. In the present device,

the forces acting on the contact |2| are dynamic rather than static. Furthermore, the principally applied force from the diaphragm, in opening the switch is constantly decreasing the amount of energy that can be absorbed by the lever whereas, in opening, the applied force is constantly withdrawing and hence the amount of energy that can be absorbed by the' lever is constantly being increased by virtue of the fact that it is constantly relieved.

t may then be seen that it requires more energy to open the switch than to close it. Hence, f

the lever |06 will move further before the switch opens than it will to close the same.

This being true, let it be assumed that the switch is open, and is to close at 30. As the diaphragm 13 expands, the screw 85 will move forward to a certain point representative of 30. At this point sufficient energy is available to close the switch, which event will occur. lecting override, let it be assumed that the temperatureis progressively lowered. Since it requires more energy to open the switch than to close it, thescrew 85 will have 'to move backward beyond the opening point before sufilcient energy' is stored to break the contacts. Hence, the switch will not open until some lower temperature, such as 28 is reached.

When the knob 33 is turned to the defrost position the cam |56 drops from beneathV the point |50, and the extension |52 on the lever |42 drops behind the edge |10 on thecam |58. Thus the lever |42 rotates in a counterclockwlse direction, referring to Fig. 16, and to the position shown in this gure, under the inuence of the spring |46. This turning of thefknob 33 simultaneously causes the cam edge IB? to act upon the abutment |80 on the lever iii to o n and hold open the switch. Consequently, the cornpressor is held inoperative. However, when the diaphragm 13 is moved to a certain high point, the sleeve 88 acting upon the abutments i oi' the lever |30 will move this lever about its pivot. After this motion reaches a certain amount the edge |40 of the lever will act upon the contact end of the lever |42 to rotate the same clockwise, as seen in Fig. 16. the extension |52 and the point |56 free of the cams, whereupon the end |13 of the spring |12 immediately causes the knob 33 to return to neutral position or the position designated on This rotation of the knob frees the cam edge` |51 from the abutment |80 and permits the switch to close immediately, which it will do, since the temperature is above the normal temperature at which the switch is closed. In this operation the mechanism is permitted to override the normai operating temperature of the' switch without damage because the connection between the diaphragm and the lever |06 is ultimately effected through the spring |31 which merely compresses to a greater degree when' the defrost switch is set. By this means the operator may set the switch to defrost position and then, when the unit reaches a certain high temperature at which defrosting may be completed automatically, it will. be shifted back to normal operating conditions.

With the switch in defrost position, if it is desired to revert it to normal, prior to its automatic return, such may be done by merely turning the knob 33. In this action the cam |55 moves relative to the cam |58, which latter is held from motion by the engagement of the extension |52 over the edge |10. As this movement of ,the cam |56 proceeds the edge |15 strikes the slope |5| of the lever |42 and by riding on this slope 1ifts the lever until the extension |52 is free of the cam |58. As soon as this'is This liftsy Then, neglock the lockable member and main:L

done the knob 38 may be released and the spring |12 will return it to the on position.

When it is desired manually to open the switch and hold it open it is necessary only to turn the knob 38 to the off position which brings the cam edge |88 into position so that the projection is engaged in the notch |68. In this position the mechanism is rendered entirely inoperative until it is manually changed from this oiT' position.

From the above it may be seen that the switch device includes many advantages within a compact structure, being complete in desired iunctions, simple to operate, and fully adjustable.V

Although it has been, described for use on a refrigerator, such is merely one of its applications. Also, while the structure is particularly valuable when used in a diaphragm-type temperature responsive mechanism, it is readily adapted to other similar uses. It is not limited to use an electric switch and, where the term switclr' is used in the claims, such is understood to be merely representative of mechanisms operable by this type of movement.

What is claimed 1. In a device of the kind described, a switch, means responsive to physical conditions, means adapted to operate said switch at a predetermine condition of said responsive means including lockable member, separate means shifta'ce switch against operating movement ar movable independently oi said lockable f interconnecting said separate means and s? sponsive means to release said separate means when said responsive means attains a preebermined condition. -r

2. In a device ci the kind described, a means responsive to changes in physical co tions, means adapted to operate said switcl;d predetermined condition of said responsive means including a lockable member, means to loc: the lockable member to maintain the switch against operation, means movable independently of said lockable member interconnecting the last-named means and the responsive means 'to release the former upon the responsive means attaining a predetermined condition, and means to adjust one oi said predetermined conditions without affecting the other.

3. In a device of the kind described, a switch, power means tooperate said switch at a predetermined condition including a lockable member, releasable means to lock said member and maini tain said switch against operation, means sep-l arate from said lockable member and connected' with said power means to release said reieasable means when said power means attains a predetermined condition, means to adjust both said predetermined conditions while maintaining the difference between them, and means 'for adjusting one of said predetermined conditions relative to the other.

4. In a device o the kind described, a frame, a power means mounted on the frame, mechanism adapted to be moved by said power means, said mechanism including two separate members movable relative to each other and to the frame, two abutments on said mechanism, means inging said members against said abutments to move together upon movement of said mechanism, one of said abutments being adjustable relative to the mechanismwhereby'to vary the movement of one of said members relative to said power means. l

5. In a device of the kind described,l a power means, a mechanism adapted to be moved by said power means, said mechanism including two abutments on said mechanism, a pair of separate movable members, one engageable' with Aeach 5 of said abutments relative to the other.

6. In a device of the kind described, a frame, a power means, a ilrst element adapted to be moved by said power means, a second element, and means connecting said second element to said nrst element .for movement therewith, said conl5 necting means adjustably engaging both elements and adapted in said adjustment to produce a movement of said elements relative to each other equal to a fractional part of the movement or said connecting means relative to each of them,

and said connecting means extending through the frame to be accessible from the outside thereof for effecting said adjustment.

7. In a device of the kind described, a frame,

a power means, a rst element adapted to be moved by said power means, a screw threadedly engaging said iirst element on one side of the frame, a second element differentially threadedly engaging said screw, and a member adapted to be moved with said second element upon movement thereof in response to movement of said rst element by said power means, and said screw projecting through the frame to be accessible on the other side thereof for eilecting said adjustment. l 3

8. In a device of the kind described, a solidcharge actuated diaphragm, a tlrst element adapted to be moved by saiddiaphragm, a second element, a diirerential screw adjustably connecting said elements for movement together, said screw, upon being turned, producing micrometric movement of said second element relative to the rst, and means for turning said screw, said screw extending beyond the same side of both elements to be accessible for effecting its rotation.

9. In a device of the kind described, a powerk means including an element to be displaced upon changes of physical conditions, a first threaded element adapted to be moved by said means. a

second threaded element, diierential screw 50 means adjustably connecting-said elements, a' rst member adapted to be moved by said firstthreaded element, and a second member adapted 'to be moved with said second threaded element,

rotation of said screw adjusting the point of 55 movement of said second member relative tb said power means, but not altering said nrst member.

10. In a'device of the kind described, a frame,

a power means mounted on said frame. a ilrst element, an adjustable abutment between said ilrst element and said power means, a second element, differential screw means connecting said elements flor adjustment relative to each other and for movement together by said powa' means,

and two movable members mounted on the frame, o5

one adapted to be moved with each of said elements. A

11. In a ldevice of the kind described, a power means mounted thereon, a hollow, internally threaded sleeve, a hollow screw engageable with the threads on said sleeve, an abutment adapted to/ be adjusted Yby said screw, a member adapted to be moved by said abutment, and a set-screw means between said power means and-said sleeve, adjustable through the hollow screw and sleeve.

12. In a device o! the kind described, 'a trame, a power means on said frame, a rst sleeve maintained on said frame for axial movement but against rotary movement, spring means urging a power means on said frame, a first sleeve adapted to be moved by said power means, means on said frame preventing rotation of said sleeve but permitting axial movement thereof, a screw engaging said sleeve, a second sleeve threadedly engaging said screw, means on said trame preventing rotation of said second sleeve but permitting axial movement thereof, a lever. resilient means urging vsaid lever against said second sleeve, and a switch adapted to be actuated byv said lever.

14. In a device of the kind described, a frame, a power means on said frame, a first sleeve adapted to be movedby said power means. means on said frame preventing rotation of said sleeve but permitting axial movement thereof. a

engaging said sleeve, a second sleeve threadedly mitting axial movement thereof, a lever, resilient means urging said lever against said second 5 sleeve, a switch adapted to be actuated by said lever, a secondlever adapted to be actuated by said ilrst sleeve, lock means releasably maintaining said switch against operation, and means actuated by said second lever to Arelease said lock means upon movement of said power meansA and said tir/st sleeve a predetermineddistance.

15. In a device of the` kind described, a power means, a pair oi' members adapted to bef`moved lby said power means, a switch adapted tobe actuated by one 'of said members after movement orsaid power means as muchas a predetermined distance, releasable lock means preventing actuatlonfof said switch by its member. and means operated by said second member to release said lock means upon movement ot said power means a predetermined greater distance, whereby said rst member may then actuate said switch.

adapted to be actuated by said resiiiently conf nected member upon movement or said power means as far as a predetermined distance, means locking said switch against such actuation t whereby the force of said power means is stored in said resilient connection, means operated by said second member to release said lock means upon movement of said power means a predetermined greater distance, whereby the force stored in said resilient means may/then actuate said switch.

17. A device as set forth in claim `15, with means to adjust the position of said power means relative to the switch at which said switch normally operates.

18. A device as set forth inl claim 15, with means to adjust the position of said power means operates.

19. A device as setiorth in claim 15, with a single means to adjust the position of said power means relative to the switch at which both said members normally operate.

20.`A device as set forth in claim 15, with means to adjust the position of said power means relative to the switch at which each member is moved, whereby theposltion of each may be determined separately.

21. In a device of the kind described, a frame, a power means thereon, a nrst threaded sleeve, resilient means urging said sleeve toward said power means whereby the same is moved by said means, an adjustable abutment between said power means and sleeve, a screw engageable with said sleeve, a second threaded sleeve engageable over said screw, means preventing rotation of said second sleeve but permitting axial movement thereof, said last-named means being mounted on said frame for adjustment relative thereto, a iirst movable member engageable withv said rst sleeve for movement thereby, a second movable member engageable with said second sleeve for movement thereby, said adjustable abutment being adapted to alter the relation of both sleeves relative to the power means, and said means preventing rotation of said second sleeve being adjustable to alter the relation of said second sleeve relative to the power means and said lrst sleeve.

22. In a device of the kind described, power means, a switch, an actuating member for said switch, means moved by said power means for operating said actuating member, lock means to prevent operation of the switch, having an element engageable with the actuating member to stop the same, means normally urging said element from said actuating member, means holdlng the same in engagement with said member, and means separate from said actuating member operated by said power means for releasing said last-named holding means. l

23. In a device of the kind described, means responsive to changes in physical conditionsl a switch, an actuating member for said switch, means for locking said switch against operation including an element engageable with said actuating member,.means normally urging said element out ci locking position, a lever for holding said element in locking engagement, and means separate from said actuating member causing said first-named means to release said lever upon occurrence of a predetermined physical condition whereby said element removes from locking position.

D 24. In a device of the kind described, power means, a switch, an actuating member for said switch and adapted to be moved by said power means, a rotatable member having a handle thereon, means normally urging said rotatable member into a normal position, a second rotatable member limitedly oscillatable relative to said rst rotatable member, an element on said second rotatable member engageable with said actuating member to stop movement thereof, said element being thus engageable when said rotatable member is displaced from its normal position, a lever, said second rotatable member having an edge engageable with a portion of said lever when said stop element is against said actuating member, said rst rotatable member being then adapted, when said handle is turned,

relative to the switch at which said release means to engage said lever and lift it from said edge of said second rotatable member.

25. In a device of the kind described, a frame, a solid-charge thermal element including a diaphragm, on said frame, a first threaded sleeve, means urging said sleeve toward said diaphragm, an abutment on said sleeve and engageable with said diaphragm, a differentially threaded screw threadedly connected with said sleeve, a second sleeve connected to said screw, whereby rotation of said screw produces micrometric movement of said second sleeve relative to said iirst sleeve, a rst lever, a second lever, a spring between said levers urging the ilrst lever against the first sleeve and the second lever against the second sleeve, a switch adapted to be actuated by said second lever, a rotatable knob on said trame, an element mounted on said knob for rotation therewith, two cams on said element adapted to engage said second lever to hold the same against rotation, and automatic means for releasing one of them, said automatic means including a spring normally urging said rotatable member to rotate so as to remove such cam from said lever, and said element having an edge engageable with said rst lever to hold the element against such rotation by the spring, the movement of the diaphragm shifting the iirst sleeve to lift the ilrst lever from said rotatable element and permit said spring to `remove said cam, upon occurrence of a predetermined temperature.

26. In a device of the kind described, a diaphragm adapted to be moved by fluid pressure. a switch including a blade, resilient means urging said blade in one direction with decreasing effect as the blade is moved in the opposite direction, means connecting said diaphragm to said blade including a lever having a short powerreceiving arm and a long power take-off arm, which latter is connected with said blade, said lever having inherent resilience to store in itself by deformation certain of the applied forces whereby said blade moves with a snap action, and closes at a different position of said diaphragm from that at which it opens.

2'7. In a mechanism of the kind described, a power means, an element moved thereby to several positions, a switch, a first member controlling operation of the switch and adapted to be moved by said element, said switch being actuated when said first member is moved by movement of the element to a rst position, means to lock said first member against movement, a second member adapted to be moved by said element, and means actuated by the second member to release said lock means when said second member is moved a predetermined distance by the movement of the element to a second position.

28. In a mechanism of the kind described, a power means, an element moved thereby to several positions, a switch, a iirst member controlling operation o'f the switch, resilient means interposed between the element and the iirst member normally to cause the member to be moved upon movement of the element but permitting movement of the element when the member is locked, means to lock the member and thereby to hold the switch, a second member moved by movement of the element, and means operated by the second member to release the lock meam after the element has been moved a predetermined distance by the power means.

29. In a mechanism of the kind described, a power means, an element moved by the power first member, and'means A v 2,250,437 means, a pair of oppositely faced abutmentson said element, a pair of members between said abutments, spring means urgingl the first member against its abutment, a lock means for said member to prevent its movement by said spring whenits abutment is `withdrawn by movement of the Ypower means and element, the second member being moved by its abutment, and means actuated by said second member when it has been moved a predetermined distance to release said lock means and to permit the spring to urge the llrst member toward its abutment. 30. In a mechanism of the kind described,4 a

power means, an element moved by the power imeans, il. pair of oppositely faced abutments on the element, a pair of members extending between said abutments, a spring between the members and,ur'ging them oppositely against their abutments, whereby both of them are movable with the element, one bydirect contact withits abutment, and the other by being urged ward its abutment by the springfa switch contolled by the'v one lof said members moved through the spring,"a. lock means preventing movement of said member whereupon movement of said element s tores'energy in the springn and means operated by the other member after it moves a predetermined distance, to release said lock means.

31. In a mechanisnnof the kind described, a power means, a switch,. an element moved by the power means, a first member moved by the element and controlling the switch, lock means movable to position to engage the mst member and thereby to hold the switch, said lock means including a leverplvotable into one position to hold the lock means and into another position to release -the lock means, a second mber 32. In a mechanism of the kind described, a

- being inherently resiiien means moves,a part of its movemt may be t movable member, a locking device therefor, said locking device including a rotatable shaft, a pair of discs on said shaft, one of which is iixed .thereon and the other of which is rotatable thereon, means connecting the discs to permit only a limited relative rotation between them,

a latch, the movable disc having an edge thereon to be engaged by the latch whereby to be held ln a predetermined position, and an abutment on the movable disc carried against the movable member when said disc is rotated to position to engage the latch, the connection between the discs thereafter permitting said limited relative movement whereby the fixed disc may be moved without disturbing the latched movable one, the xed disc having an edge engageable with the latch upon such limited movement to remove the same from latching engagement and to permit withdrawal of the abutmentfrom the member.

35. In a meohanism'of the kind described, a device movable invariably in response to changes in physical conditions, a shaft adapted to be moved thereby, means urging said shaft toward the 'movable device, a member adapted to be actuated by the shaft, the shaft having an axial opening therethrough, and anvunyieldable abutment adjustably secured in said opening and interposed between the shaft and the device, the adjustment .of the abutment being eectible throush the axial opening.

\ y'36..In a device of the kind described, a solid- Ielent and lever -to actuate the lever upon movements of the element, and a switch at one end of the lever, and a mechanical means actfing on the switch end of the lever to urge it in' one direction and to resist movements in the other, the lever between the mechanical means and the .point at which ttho element is connected whereby as the power power means, a switch, a first vmember moved stored as latent energy in the lever, and finally by thepower means and controlling the switch, a separately movable abutment means*A adapted toen'gage theiirstmemberandlockitagainst movement, means normally urging said abutment away from said member, a latch engageable with the abutment means when' the same is moved `the switch will be actuated with a sudden move-l 1 ment.

37.Inamechanismofthekinddescribed,a

4 power means, a movable member, resilient means to locking position, to maintain it insuch posi- `tion, and -a second membermioved by the power means, said second member being adapted to trip the latch to release theabutment means and, enable it to remove from locking position.

33. Ina mechanismof the kind described,

34. In a mechanism or the maacnboa, a 1p connecting the power means to the movable member, a shiftable device movable into two po sitions to lock the member against movement, and means operable by the power means to relas'e the shiftable device from one of said positions.

38. In a device of the kind described, a cutofi', powermeansmovable to diii'erent positions in response to changes in physicaly conditions, mechanism interconnecting said power :means and cut-of! to operate said cut-off at predetermined an'd variable positions of said power means relativeeto saidv switch, said-mchanism including a member to be moved, a screw, means for displacing the screw relative to the power means .upon rotation thereof, an abutment engageable with the moved member butffree for independent movement relative to the moved member, vand means displacing the abutment a lesser amount upon said rotation of the screw.

g LAWRENCE M. PERSONS.