US2617900A

US2617900A - Refrigerator defrosting timer

Info

Publication number: US2617900A
Application number: US152733A
Authority: US
Inventors: Morrison David
Original assignee: Paragon Electric Co Inc
Current assignee: Paragon Electric Co Inc
Priority date: 1950-03-29
Filing date: 1950-03-29
Publication date: 1952-11-11
Anticipated expiration: 1969-11-11

Description

NOV. 1l, 1952 D, MORRlsON 2,617,900

REFRIGERATOR DEFROSTING TIMER Filed March 29, 1950 2 Sl-IEETS--Sl-{EET l 2gjj Z8 d f l 1" l Y, M

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D. MORRISON REFRIGERATOR DEFROSTING TIMER Nov. ll, 1952 2 SHEETS-SHEET 2 Filed March 29, 1950 Marr/'son .and speed reducing unit I6.

Patented Nov. 11, 1952 REFRIGERATOR DEFROSTING TIMER David- Morrison, Manitowoc, Wis., assignor to Paragon Electric Company, Two Rivers, Wis., a corporation of Wisconsin Application March 29, 1950, YSerial No. 152,733

7 Claims. (Cl. 200-33) The present invention relates particularly to timers adapted to open and close the electrical circuits for refrigerators in order to effect automatic defrosting at regular intervals; although the use of the invention is not vlimited to this field.

In my prior application, Ser. No. 50,902, filed September 24, 1948, I have disclosed a defrosting system of the type just described. The present invention may be said to have for its object to produce a timer which is simpler in construction than that disclosed in the aforesaid application, and which is reliable, efficient in operation and very durable. Y e

The various features of novelty whereby the present'invention is characterized will hereinafter be pointed out with particularity in the claims, but, for a full understandingA of the inveritionV and of its objects and advantages. reference may be had to the following detailed description taken in Vconnection with the accompanying drawings, wherein: ,e y Figure lis a perspective View of a timer embodying the present invention, the conventional casing being omitted; Fig. 2 is a top plan view of a part-of the timer, with the combined knob and pointer omitted; Fig. 3 is a side elevational view of the timer as itappearsin and lookingrat it from below Fig; 2; Figs. 4 and 5 are views similar to Figs. 2 and 3, respectively, illustrating the conditions which exist at a different point in a cycle from that corresponding'to Figs. Zand 3; Figsf and 7 are also views similar to Figs. 2 and 3, respectively, illustrating another set of con.- ditions-at` still another point in such cycle; Fig. 8 is fa section on line 8 8 of Fig. 2; Fig. 9 isa perspective view` of the finger piece `for .adjusting one oi' two cams angularly with respect to the otherj Figs. l and 11 are `two perspective views of the cam to which the :linger piece is connected; and Fig. A12 is aperspective View ofthe second of the .two cams andthe shaft with which it is interlockedsc' as to be compelled to rotate therewith.

Referring to Fig. l of the drawings, I represents a flat plate on which the various parts of the timer'mechanism are mounted. On the under side of this plate is any suitable electric motor Above the plate is a large gear wheel Il in mesh with a pinion I8 that forms the last element in the gear train through which the timer mechanism proper is driven. A little above, and coaxial with, wheel Il is a somewhat smaller gear wheel I9, and above and near the latter wheel is a third gear Wheel 20, of the same diameter as and coaxial therewith. The number of teeth is not the same in gear wheels I3 and 20, as there must be at least one more tooth in one wheel than in the other. In the arrangement shown there are one hundred and twenty teeth in wheel I9, whereas there are only one hundredand nineteen teeth in wheel 2B. Gear wheel kI'l has on the upperside a pin or post 2I lon which is a looser pinion 22 that meshes with the teeth on each of the wheels i9 and 20. Above and coaxial with the gears are two

superimposed cams

23 and 24, preferably of insulating material, coaxial with the three gear wheels. Above thecams is a combined pointer and knob 25. Cam 23 has a Wide annular ange 23a that rests on the gear wheel or disc 20.

yPlate I5 has at one end two spaced', upturned parts .15a and I5`b. A slab 2,6 of insulating material spansthe space between saidV upturned parts,` and is xed to the latter. Carried-by member 26 is a switch adaptedto be controlled by the cams. The switch is shownV as comprising two

spring arms

21 and 28, each anchored atone end to the supporting member 26 and having portions thereof extending radially 0f the; gear Wheels over` ilange 23a. Switch arrn 2l isbent downwardly near its free end and then horizontally to provide a toepiece 29 that normally lies near the. flange` on cam 23. Arm 28, the radial portion of which liesdirectly lover thecorrespondingl part of arm 21, vis a straight piece. The switch arms are provided with .cooperating contacts 30 and 3|, respectively, inwardly .from their free. ends. When the switch is not under constraint, the contacts on the arms arepressed firmly into engagement with each other, through the spring action of the arms. In other words, theswitch is self closing. y u f, The details of essentialparts that have now been described in general terms, only..A are .illusitrated in Figs. 8-12. Y i

. As shown in Fig. 8, the large gear wheels are supported by a sturdy vertical column or post 32 fixed to and rising from plate, I5. The postis reduced in diameter a short-.distance above. the plate to providea` shoulder 33 on which gear wheel Il rests. At a little distanceaboveshoulder 33 there occurs a second reduction in'diameterv of the post to provide a shoulder 34 on which gear wheel IQ rests. A third reduction inthe diameter of the post, at a stillhigher level, provides a third annular shoulder 35 on which gear wheel 2 rests. There is a spacer 36 aroundthe post, between gear wheels I'l and I9. i

to the post byl pressing it on, or in ,any-other suitable way. l f 1 -Y The body portion of cam23 isan inverted cup the chamber 23b in which is substantiallylarger' in diameter than the upper end of the post. Gear wheel 20 has on the upper side a-tubular hub 3l that ts around the post and provides along bearing for this wheel. Surrounding' this" hub, and tting it closely, is a torsion spring 38 one end 39., ol' which, is engaged in a groove 23c1 opening out from one side of the chamber in cam 23. This arrangement constitutes a clutch that permits the cam and gear wheel 2 to turn freely, relatively to each other, in one direction, and prevent relative movement in the opposite direction. rlhe reason for having the clutch is to permit the cam to be turned by hand, relatively to gear wheel 29, for the purpose of selecting the point in time at which the switch shall open. In order that cam 23 may be turned by means of knob 25, I make `the post tubular in form to serve as a bearing and support for loose shaft ii. This shaft contains two circumferential grooves iii and #l2 that lie, respectively, immediately below and above the post. When fiat C-'shaped keys t3 are entered in these grooves, the shaft is held against lengthwise displacement, while free to rotate. That part -l of the shaft above groove 62 is iiattened so that, when it is slipped through a correspondingly shaped hole in the top wall of the chamber in cam 23 and through a hub 45 projecting up from the cam, the shaft and cam are securely interlocked against turning movements relatively to each other.

Shaft 40 extends up well above cam 23, and cam 24. Cam 2li and the shaft are not interlocked against relative angular movements. It will be seen from Figs. 10 and l1 that cam 24 has on its upper side a hub 46 in the form of a sleeve slotted from top to bottom at two diametrically opposed points. A finger piece 41, best shown in Fig. 9, is slipped on this hub. This linger piece is shown as being in the form of a metal disc i8 having a stem le that projects radially therefrom; the outer end of the stem being bent up at rightangles to the rest of the stem. The disc contains a central hole di) to receive the hub on the cam, together with two opposed lugs 5|, 5I that extend inwardly from the sides of the hole. These lugs enter the slots in the sleeve hub and interlock the cam and finger so that they must turn With each other. The shaft is provided with a groove 52, similar to grooves il and 42, pla-ced a little above the lower end of the hub 46. To apply the finger piece in the assembly, the hole in the finger piece is first registered with the upper end of the shaft, with the lugs 5| at the fiat sides of the latter. Then, after cam 2d has been turned with the slots in the hub registering with the lugs on the linger piece, the latter may be moved down over the hub until it reaches the level of the groove 52 in the shaft. Thereupon the finger piece may be turned until the lugs enter this groove and allow the nnger piece to turn freely on the shaft. By placing the groove a little above the top of the body portion of the cam member, room is provided between the finger piece and such body portion for a spring washer 53. In making the assembly, the washer is placed in position before the finger piece is applied, so that the washer mut be stressed somewhat to allow the finger piece to come down far enough to enter groove52. Thus the cams are yieldingly pressed together, so that the upper cam is frictionally held against turning on the lower cam.

As shown in Fig. l, the combined knob and pointer 25 has in the edge of its disc-like portion 54 a wide notch 55. The upwardly bent end of the stem member of the nger piece 4l lies in c this notch, so that the angular movement of the finger piece and the upper cam, relative to the lower cam, is limited to the angular width of the notch.

The details of the two cams are best shown in i Figs. 10, 11 and 12. Thus, as shown in Fig. l2, the lower cam has an arcuate ledge, the top of which is a cam track 23C, rising from the level of the top surface of the fiange to a high level of any desired angular length. Similarly, cam member 24 has an arcuate ledge of the same radius as the other ledge and provided with a cam track 24a that is much like the other track. Each of the two ledges terminates abruptly at the high end, and the cams are so disposed, that the high ends of both trail while the timer is operating. The parts are so proportioned that normally the free end of the lower switch arm lies below the level of the high portion of the lower cam track, and the free end of the upper arm of the switch lies below the level of the high part of the upper cam track. However, the free end of the lower switch arm lies above the level of the low advance end of the lower cam track. A further characteristic of the switch and cams is that the switch remains closed while both switch arms are above the high portions of the corresponding cam tracks. The camming ledge on the lower cam member is of greater angular length than :1 the ledge of the lower cam. This allows the low end of the lower track to be in advance of the corresponding end of the upper track at times when the trailing ends are in the same vertical plane.

Assuming that the timer has been set and that the motor is running, pinion 22 is continuously carried around the stationary gear wheel, and is thus compelled simultaneously to resolve about its own axis. The pinion also rolls along the toothed edge of of the upper gear wheel; but, be-

` cause of the difference in the number of teeth in the wheels, the loose, upper gear wheel 2!! completes a revolution after the pinion has engaged only one hundred and nineteen of the teeth in the stationary wheel. Therefore, wheel 2U is positively turned through an angle, corresponding to a single tooth, during each revolution of the pinion around the stationary gear wheel.

Where the timer is intended to control the defrosting of a refrigerator the mechanism may be calibrated to cause gear wheel 20 to revolve once in twenty four hours.

To determine the point in each twenty four hour cycle at which the switch opens, the combined knob and pointer 25 is turned to point to the desired hour and minute on the usual dial, not shown. To determine the length of time during which the switch remains open, linger piece 67 is shifted to adjust the positions of the cams relative to each other. When the finger piece is at one end of the notch in member 25 the switch will not open at any time; because the trailing end of the upper cam track is then directly above or, if desired, ahead of the trailing end of the lower track. When the nger piece leaves that end of the notch the cams are set to effect a switch opening once in each revolution of wheel 20, the length of time during which the switch remains open increasing as the finger piece is shifted Valong the notch.

rEhe manner in which the cams operate or control the switch is apparent from the drawings. Thusin Figs. i, 3 and 5 both switch arms are clear of the cam tracks and the switch is closed. In Fig. 5 the lower cam has flexed both switch rms upwardly, raising the upper arm to such a level that the upper cam need not exert any lifting eort; serving merely as a support for the upper switch arm after the lower arm drops olf the lower cam track at the traling end of the latter. Thus, with the parts in the positions Shawna, ne, 5, triestina wondere-nain @19ste even, thoughjthe lippen Cem' track were.notl D, ent.' onlywhen thelower armriahea'h @r9 ping, e,- poini While meppel: tratt still under? lies. theV upper. arm, as iniFig. 7, doesjthe upper ingfa slightly larger number ofteeth. than the` other, means for mounting. said Wheel Q11 the,

support in coaxial relationandneall.each other` to hold the lower. wheel stationary While the otherv is free to revolve, a pinion meshing with both gear wheels,'power means to carry said pinion bodily and continuously around said wheels, a switch mounted 'on the support and having two arms arranged one abovethe other and extend-V ing radially of the wheels at some distance above the upper wheel, two, ca -n1 devices composed of insulating material positioned one on top of the other, on and coaxial'with'Y the upper wheel and havingthereonupwardly facing switchen'.- ngmc )tracksV tol engage with the ef spp ding switcharrnsonc 'di/li: geach rjeyo tion ordis upper wnijtne lowers f j 'device having at the bottoma'n annular 'aange which at au times underlies the switch arms and prevents them from engaging the latter wheel, a one-way clutch between the upper wheel and the lower cam device, means frictionally holding the cam devices against relative rotary movements, and a. finger piece on the upper cam device to shift it angularly of the lower one.

2. A timer mechanism including a support, a stationary tubular post rising from the support, a shaft rotatably mounted in and projecting up from the post, two gear wheels surrounding the post in coaxial relation to each other, the lower wheel being xed to the post and the upper wheel being rota-table, one of the wheels containing slightly more teeth than the other, the upper wheel having a hub on the upper side, a pinion meshing with both wheels, power means to carry said pinion bodily and continuously around said wheels, a switch on said support beside the wheels, a switch actuating cam on, and rotatable with, the shaft just above the upper wheel and having thereon upwardly facing switch engaging cam tracks, said cam having in the under side a central cavity larger than said hub, a torsion spring in said cavity around the hub and anchored at one end to the cam to form a oneway clutch between the cam and the upper wheel, and a member on the upper end of the shaft for turning the shaft manually, in the direction permitted by the clutch, to shift the cam angularly relatively to the upper wheel.

B. A timer mechanism including a support, a stationary tubular post rising from the support, a shaft rotatable in and projecting up from the post, detachable key elements on the shaft above and below the post to hold the shaft in place, two gear wheels surrounding the post in coaxial relation to each other, the lower wheel being fixed to the post and the upper wheel being rotata- 6 ble, onefwoiA the ,wheels` ontaining slightly more een ih, ni. che "ther, the'. fumerKV wheerhvinea han, yon; merca side', pinion meshing winisotu" wheels, poyv mearsA toY carry said pirfi'iorlhodil'yV`V and continuously' around said wheelsfaswitchon ort besidejthe iifhe'e'ls,y a switcliactuat' on, ane4 rotatable with, me stair;andyhaving 'a enclosing said hub, said cam 'hav-1 ingu thereon upwardly facing cam"'tracks", and' meansV in he said cavity"cooperatingfwith the cani andthe hubto form a one-'way clutch bee post, 'one off'lfth'e two uppergearwheelscontai 4' a slightly greaternumbejrof t'eth'tha'n'the other, its lernst eter wheel being fafgf'di ameter than the others,V aVV pinion" rotatably mounted on lthe lcnvest ygear wheel and me'shi'rig'l with bothmof th'eothe'r wheels, power I'rearis't drive the lowest gear wheel, a switch op'atingrv lmean; composed of two nieibe'rsfoand ge K wheel and each having 'thereonn an'iipwar'ilyN facingY s); ch engaging cam' Ytrackfa 'oeway clutch be. en thecarnandtheupper'whel, Qi @remembers hating Alrlii'd*dellla-i' movement on the other and provided'withafln ger piece to turn the same, a spring pressing said members together to create frictional resistance to relative angular movements, a switch on said support beside the wheels having two arms each of which extends into the path of one of said cam members, and a member on the upper end of the shaft for turning the shaft manually.

5. In a timing mechanism, a self closing switch formed of two spring arms arranged one above the other and anchored at corresponding ends while the other ends are free, the arms tending constantly to contact each other, each arm having thereon a contact piece, at some distance from the free end, to engage with the contact on the other arm, the center lines of the portions of the arms from the contact pieces to the free ends being in the same vertical plane, an upright shaft, rotatable in one direction only,

, beside the switch, two cams, one above the other,

on and rotatable with the shaft; the lower cam having thereon an upwardly facing track that passes underneath the free end of the lower arm of the switch at a predetermined point in each revolution of the shaft, the track being so shaped that both arms are first stressed and raised while remaining in contact with each other, and are then released from this cam at a second predetermined point in each revolution of the shaft; the upper cam having thereon an upwardly facing cam track that passes under the upper switch arm, after the switch arms have been raised, this track being so shaped that it holds that arm up independently of the lower cam track during a portion of each revolution of the shaft and then releases it; and means to adjust the cams relatively to each other angularly of the shaft so as to determine the relative times at which the two cams release the corresponding switch arms.

"wan @ne snare just abete mej'pper" 6. In a timer mechanism, a rotatable shaft, a power-driven wheel supported independently of the shaft around and in coaxial relation thereto, said wheel having a central hub on the upper side thereof, a cam member in the form of an inverted cup on the Wheel and interlocked with the shaft for rotation therewith, with said hub housed in the cavity in the cam member, the diameter of the cavity being greater than that of the hub, a torsion spring surrounding and gripping the hub, one end of the spring being free in space and the other end being anchored to the cam member thereby forming a one-way clutch between the wheel and the cam member. an upwardly facing cam track on the exterior of the cup, a second cam member surrounding the shaft above the cup and interlocked with the shaft for limited movements re1- atively thereto, said second cam member also having an upwardly facing cam track, an element on the upper end of the shaft to turn the same manually in the direction permitted by the clutch, a nger piece on the second cam member for shifting it, and a switch provided with two elements one of which extends into operative relation to said cam track while the other extends into the path of the track on the second cam member.

7. In a timer mechanism, a rotatable shaft,

a power-driven wheel supported independently ,j

of the shaft around and in coaxial relation thereto, said wheel having a central hub on the upper side thereof, a cam member in the form of an inverted cup on the wheel and interlocked with the shaft for rotation therewith, with said hub housed in the cavity in the cam member, the diameter of the cavity being greater than that of the hub, a torsion spring surrounding and gripping the hub, one end of the spring being free in space and the other end being anchored to the cam member and thereby forming a oneway clutch between the wheel and the cam member, an arcuate cam track on the exterior of the cup, a second cam member, provided with an arcuate cam track, surrounding the shaft above the cup and interlocked with the shaft for limited movements relatively thereto, an element on the upper end of the shaft to turn the same manually in the direction permitted by the clutch, a finger piece on the second cam member for shifting it, and a self-closing switch composed of two spring arms arranged one above the other, anchor means iixedly supporting corresponding ends of the arms While the other ends stand free, said arms extending radially into the paths of the corresponding cam tracks.

DAVID MORRISON.

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

UNITED STATES PATENTS