US3021687A

US3021687A - Ice tray drive assembly

Info

Publication number: US3021687A
Application number: US290A
Authority: US
Inventors: Robert H Dawson; Robert R Dahl
Original assignee: Dole Valve Co
Current assignee: Dole Valve Co
Priority date: 1960-01-04
Filing date: 1960-01-04
Publication date: 1962-02-20
Anticipated expiration: 1979-02-20

Description

Feb. 20, 1962 R. H. DAWSON ETAL 3,021,687

ICE TRAY DRIVE ASSEMBLY 5 Sheets-Sheet 1 Filed Jan. 4, 1960 illl (lr INVENTORS Robert flflawson Robert R. Dafi ATTORNEYS Feb. 20, 1962 R. H. DAWSON ETAL 3,021,687

ICE TRAY DRIVE ASSEMBLY Filed Jan. 4, 1960 5 Sheets-Sheet 2 INVENTORS Fain! 0411/5072 57% 2 Roert' R. Dad! ATTORNEYS Feb. 20, 1962 R. H. DAWSON ETAL 3,021,637

ICE TRAY DRIVE ASSEMBLY Filed Jan. 4, 1960 5 Sheets-Sheet 3 mo 707z 95/94 INVENTORS Robert A! Pains-an Ra) a Rflal w; fla zW/Z ATTORNEY! Feb. 20, 1962 R. H. DAWSON ETAL 3,021,687

ICE TRAY DRIVE ASSEMBLY Filed Jan. 4, 1960 5 Sheets-Sheet 4 A l l 1 l I 1 l l I a u i INVENTOR E I Ralert' 1% 04mm) k Aw; R. 042% ICE TRAY DRIVE ASSEMBLY 5 Sheets-Sheet 5 Filed Jan. 4, 1960 ATTORNEYJ 3,021,687 ICE TRAY DRIVE ASSEMBLY Robert H. Dawson, Lake Bluff, and Robert R. Dahl,

Lincolnwood, Ili., assignors to The Dole Valve Company, Morton Grove, 111., a corporation of Illinois Filed Fan. 4, 1960. Ser. No. 290 7 Claims. (Cl. 62-135) This invention is directed to an automatic ice making assembly of the type which is adapted to be mounted within the freezing compartment of the usual household refrigerator. More particularly, the invention is directed to an automatic ice making apparatus including a twosided pivotal ice tray and to a means for pivoting the ice tray and eflecting ejection of ice blocks therefrom as a function of the rate of freezing of water disposed within the ice tray. The invention is further directed to a means for controlling the operation of the ice making assembly as a function of the level of ejected ice blocks disposed within an ice block collection tray.

The mechanism which we have devised for controlling the operation of such a pivotal ice tray includes a thermal sensitive power unit of a type which is well known in the art and which has an element extensible therefrom upon predetermined ambient temperature conditions therearound. The power element is cooperable with a ratcheting mechanism and is effective to rotate a gear through a predetermined are upon extensible movement thereof from the power unit. A simple linkage arrangement is associated with the gear in such a manner as to effect pivotal movement of the ice tray upon rotatable movement of the gear.

The use of a thermal sensitive power unit for controlling the operation of an ice making assembly is quite advantageous inasmuch as it permits the filling of the ice tray and the ejection of ice blocks therefrom as a function of the rate of freezing of the fluid within the ice tray. While it has been possible to eflect rotation of a rotatable ice tray by means of an axially movable power element such as that which is associated with a thermal sensitive power unit, difliculties have been encountered in attempting to effect such pivotal movement through such a means. Some means have been devised for effecting such movement but have generally required complicated linkage arrangements or the usage of two or more thermal sensitive power units.

We have devised a simple linkage arrangement for transmitting axial reciprocable movement of the power element into the desired degree of pivotal movement for the ice tray.

It will of course be understood that the basic concept of the present invention may find utility in other fields than the ice making art, in which it is desirable to translate axial movement of a power member into pivotal movement of an associated shaft.

It is therefore a principal object of the present invention to provide a mechanism for translating reciprocable axial movement of a power member into pivotal movement of an associated output shaft.

Still further it is an object of the present invention to provide a control mechanism for a pivotal ice tray which includes a thermal sensitive power unit that is operable as a function of the rate of freezing of fluid within an ice tray and in which reciprocable axial move ment of the power member is translated into pivotal movement for a pivotal type ice tray.

Another object of the invention resides in the provision of a mechanical transducer in which axial movement of a power member is operable to effect rotation of a circular gear and in which rotation of the gear is o rable 3,921,681 Patented Feb. 20, 1962 EQQ 2 to, in turn, effect pivotal movement of a cooperating shaft.

These and other objects of the invention will appear from time to time as the following specification proceeds and with reference to the accompanying drawings,

wherein:

FIGURE 1 is a side elevational view of an ice tray and an associated control mechanism therefor which is tray is mounted and which shows the various cooperating.

elements in two extreme positions;

FIGURE 4 is a vertical sectional view through the control mechanism which is taken along lines IVIV of FIGURE 1;

FIGURE 5 is another vertical sectional view through the control mechanism which is taken along lines IV-- IV of FIGURE 1 but which shows the power member in an extended position;

FIGURE 6 is a fragmental side elevational view of a' portion of the control mechanisms which is illustrated in FIGURES 4 and 5 but which more clearly illustrates the means for effecting actuation of the switch for controlling energization of the power unit;

FIGURE 7 is a plan view of the control mechanism which illustrates the means for sensing the level of ice locks within a collection tray; and

FIGURE 8 is a diagrammatic view of a wiring circuit such as might be employed to control the operation of the ice making assembly herein illustrated and described.

Referring initially to FIGURES l and 2, an ice tray 10 is mounted on an output shaft 11 so as to be integral therewith while the shaft, in turn, is journalled within a pair of

spaced supports

12 and 13 Wh'ch are aflixed to the base wall 14 of the freezing compartment of a normal household refrigerator. The ice tray 10 includes a base wall 15 which is bent along its longitudinal axis as at 16 to form two legs 17 and 18. A common wall 19 (so called because it is common to the ice molds formed on opposite sides thereof) is aflixed to the base wall 15 at the axis 16 so as to constitute an obtuse bz'sectrix of the angle between the legs 17 and 18. A pair of

end walls

20 and 21 are formed integrally with the base wall 18 and serve to close the ends of the ice tray. A plurality of transverse partitions 22 are disposed within the ice tray at regular intervals so as to divide the tray into a plurality of indvidual ice molds. It will be noted in FIGURE 2 that the edges of the legs 17 and 18 are each turned outwardly as at 23 and 24 so as to be disposed in substantially parallel relation with the common wall 19.

The particular type of ice tray which is herein illustrated is of a type in which ejection of ice'blocks from a downwardly facing mold is effected by heat transfer through the walls of the ice tray from the water filling an upwardly facing mold. To this end the entire ice tray is preferably formed of a good heat conducting material having each of its several components secured together in good heat conducting relation. The ice tray is illustrated as being in one extreme position in FIGURE 2 and as being filled with water. It will be noted that if water is directed to one of the ice molds the water will flow from that mold to each of the other-molds within the ice tray through the trough 25 formed between the common wall 19 and the outer ends of the partition walls 22. Upon freezing of the fluid within the upwardly fac'ng molds the tray will be rotated in a clockwise direction until the common wall 19 is disposed spares":

at the same angle with respect to the horizontal as in the counterclockwise rotated position. Thereafter, upon filling of the upwardly facing ice molds with relatively warm water the heat from the water will be transferred through the

walls

17, 19 and 22 of the ice tray to melt the surfaces of the ice blocks within the downwardly facing molds.

Upon melting of the surfaces of the ice blocks the bond between the ice blocks and their respective molds will be broken and the ice blocks will fall into a collection tray 30 which is disposed beneath the ice tray ill and which rests on the base wall 14 of the freezing compartment. The water which drips oil the melting surfaces of the ice blocks will not fall into the collection tray but will be retained in the drip trough formed between the leg 17 and the outwardly turned edge 23 thereof. Thereafter, upon rotation of the ice tray 1!? back to the position illustrated in FIGURE 2 the water retained within the drip trough will fall back into the molds where it will again be frozen along with the water used for filling the molds. The drip troughs formed by the outwardly turned

edges

23 and 24 thus prevent water from flowing to the collection tray 39 to help prevent sticking of the ice blocks after they have been ejected from the ice tray 10.

As shown most clearly in the fragmentary illustration in FIGURE 3 the shaft 11, upon which the tray ltlis mounted, has a link arm 31 afiixed thereto for corotatable movement therewith. A drive link 32 is pivotally connected to the link arm 31 by means of a pivot pin 33 and is similarly pivotally connected at its oppos te end to a rotating link 34 by means of a pivot pin 35. The rotating link 34 is, in turn, secured to a circular peripherally toothed gear 36 for corotatable movement there with by means of a pin 37.

' It will be understood that locus of points described by the pin 35 as the link arm 34 rotates about the rotational axis of gear 36 never crosses the longitudinal axis of the link arm 31 and that the longitudinal axes of the link arm 31 and drive link 32 never cross one another so that rotation of gear 36 acts to oscillate the shaft 11.

From the foregoing it w'll be understood that rotatable movement of the gear 36 will act through the rotating link 34, drive link 32, and link arm 31 to effect pivotal movement of the shaft 11. Thus, when the gear 36 and rotating link 34 are disposed in the position illustrated in full lines in FIGURE 3, the ice tray (illustrated in phantom lines) will be disposed in the position illustrated in FIGURE 2. Thereafter, upon rotation of the rotating link 34 from the full line to the broken line position of FIGURE 3 the ice tray 10 will be rotated to the second phantom line position through the drive link 32 and the link arm 31. It will hereinafter become apparent that the ice tray 10 is adapted to be moved from one to the other of its two extreme positions during each 180 rotational cycle of the gear 36. Of course, the degree of pivotal movement of the shaft 11 which is effected during each half revolution of the gear 36 can be varied as desired by varying the lengths of the three cooperating

links

31, 32, and 34.

As shown most clearly in FIGURE 7, the pin 37, upon which the gear 36 is mounted, is journalled for rotatable movement within the support 13 and within another support 39 which is disposed in juxtaposition to the support 13 and which is rigidly secured thereto to mount various elements of the control mechanism.

A drive wheel 49 is disposed adjacent the gear 36 and has a pin 41 extending therefrom which is journalled for rotatable movement within the

mating supports

13 and 39. The drive wheel 40 comprises substant'ally a fiat circular metallic member which has a circular wall 42 formed about the periphery thereof. Gear teeth are formed along the inner margin of the wall 42 which are engageable with the peripheral gear teeth on the gear 36 so that rotation of the drive wheel 419 will act to rotatably drive the gear 36. It will here be understood that in the illustrated embodiment of the invention the gear 36 and drive wheel 44 have a gear ratio w.th respect to one another of 4 to 1. In this manner by rotating the drive wheel 40 through 45 the gear 36 will rotate through a 180 arc. rotation of the drive wheel 46 will act to pivot the link arm 31 and consequently the ice tray 10 from one extreme pivoted position to another.

Rotation of the drive wheel 40 is elfected through a temperature sensitive power unit 50 in a manner which will hereinafter be described. The thermal sensitive power unit 50 comprises generally a heat sensitive portion 51, a power element guide 52, and a power element 53 which is guided for reciprocable movement within the gmide 52. The heat sensitive portion 51 is encased within a cup shaped member 54 but is spaced from the outermost end thereof so as to form a chamber 55. The cup shaped member 54 is rigidly afilxed to a spring stir rup 56 which, in turn, is made integral with the heat sensitive portion 51 so that the heat sensitive portion 51, spring stirrup 56, and cup shaped member 54 comprise one structurally integral assembly.

A cylindrical guide 58 is mounted on the outwardly extending support 39 and is adapted to slidably receive the aforementioned structurally integral assembly. The inner end of the spring stirrup 56 is flanged as at 59 to serve as a support for a compression spring 69 which, in turn,

has its opposite end seated against a shoulder 61 formed adjacent the open end or" the guide 58.

The thermal sensitive power unit 5% is of a type which is well known in the art and contains a fusible thermally expansible material within the heat senstive portion 51. A diaphragm serves to confine the thermally expansible material within the heat sensitive portion 51 and is affixed to the innermost end of the piston or power member 53 so that upon heating and consequent expansion of the material within the heat sensitive portion 51 the diaphragm will move upwardly within or toward the guide 52 to force the power member 53 to move extensibly from the guide 52. Upon lowering of the ambient temperature about the heat sensitive portion 51 the thermally expansible material will contract and permit retractable movement of the power member 53.

As best shown in FIGURE 5 a second spring stirrup 63 is slidably mounted within an aperture 54 formed in the support 39 and also on the guide portion 52 of the power unit 56. The outermost end of the stirrup 63 is atiixed to the power member 53 so as to move axially therewith. A compression spring 65 has one end seated against the support 39 and has its opposite end seated against an outturned flange 66 of the stirrup 63 so that it normally tends to bias the stirrup 53 and consequently the power member 53 to a retracted position with respect to the guide 52.

It will then be understood that since the power unit 50 is disposed within the same freezing compartment as the ice tray 10, the power unit can be rendered sensitive to the freezing of water within the ice tray by filling or at least partially filling the chamber 55 with water and by selecting a temperature sensitive material for the unit having desired critical temperatures. wound about the cylindrical outer surface of the cup shaped member 54 to provide a means for heating the water within the chamber 55. coil 58 the water within chamber 55 will be heated to raise the ambient temperature about the heat sensitive portion 51 to eifect consequent extensible movement of the power member 53 from guide 52. deenergizing the coil 63 the water within chamber 55 will cool at approximately the same rate as the water disclosed within the ice tray It). By using a thermally expansible material within the power unit 54} having desired critical fusion temperatures the power unit 5t} may be made to operate in a manner such that retraction of the Thus, a 45",

A heater coil 68 is Upon energization of the Thereafter, by

spams? power member 53 to its fully retracted position will not be permitted until the water within chamber 55 has frozen. Since the water in chamber 55 is somewhat insulated from the freezing compartment by means of the cup member 54 it is assumed that the water within the ice tray will have frozen prior to the time when the water within chamber 55 has done so. It will then become apparent that by providing a switch mechanism which is operable to effect energization of the heater coil 68 only at that time when the power member 53 is positioned in its most retracted position, the power unit i may be rendered operable as a function of the rate of freezing of water within the ice tray Ill.

A snap action switch 79 is mounted on the outermost end of the spring stirrup 63 and is movable therewith. This switch is operable to control the encrgization of the heater coil 68 and is of a type which is well known in the art having a pair of stationary contacts 71 and 72- and having a pivotal snap blade which is cooperable with the contacts 71 and 72 to close a circuit therethrough. The pivoted snap blade 73 is pivoted from one position to another through an overcenter spring 74 which is connected to the blade 73 and which has its opposite end connected to a snap lever 75. As is well known in the art, when the snap lever moves past an overcenter position with respect to the snap blade 73 the spring 74 will act to snap the blade out of engagement with one of the stationary contacts and into an engagement with another of the contacts.

An elongated lever 76 is also affixed to the outer end portion of the spring stirrup 63 and has a stepped outer end portion '77 within which an adjustable screw 78 is threadedly mounted. The outermost end of the snap lever 75 is disposed in the path of movement of the adjustable screw 78 so that when the power member 53 and consequently the leg 76 is moved to a retracted position with respect to the guide 52 the adjustable screw 78 will contact the snap lever and pivot the lever to snap the blade 73 out of engagement with contact 71 and into engagement with contact 72. When the snap blade moves into contact with stationary contact 72 the heater coil 68 will be energized to, in turn, energize the power unit 56.

As shown most clearly in FIGURE 5, a finger 78 of the support 39 is received within an elongated slot 7? formed along the side wal of the spring stirrup 63 so as to limit the degree of axial movement of the power member 53 in either of two opposed directions. As a result, when the power member 53 has moved extensibly from the guide 52 to the extent illustrated in FIG- URE 5 its further extensible movement will be prevented. At such time the body of the power unit 55 will back off from the power member 53 (moving slidably within the guide 58) against the opposing biasing force of the compression spring 60. Such back-oft or overtravel is operable to etiect deenergization of the heater coil 68 in the following manner: Referring especially to FIGURES 47, a lever 80 is pivotally mounted on a supporting bracket 81 which, in turn, is affixed to the support 39. One end of the lever is disposed adjacent the free end of the snap lever 75 so that pivotal movement of lever 89 will act to pivot thelever 75 to move the snap blade 73, through overcenter spring 74, into engagement with the contact 71'. Pivotal movement of the lever 3 is effected by means of a curved finger 83 which extends outwardly from and which is formed integrally with the shell 56. Thus, when the power unit 59 moves into overtravel against the opposing biasing force of compression spring 60 the finger 83 will be moved downwardly to pivot the lever 80 to thereby consequently pivot the snap lever 75 to effect deenergization of the heater coil 63. Since retraction of power member 53 is determined by the temperature of water within chamber 55 and since the water within the chamber cools at about the same rate as the water within the ice tray 10, the

power unit 59 will be intermittently energized as a function of the freezing rate of water within the ice tray 10 and then deeriergized after the power member 53 has moved to the outer limit of its travel.

Axial movement of the power member 53 is transferred to the drive wheel 49 to effect rotatable movement thereof through a pawl which is pivotally mounted by means of a pin 86 to a bracket 87 secured to the leg 76. The pawl 85' has a finger 83 formed on the free end thereof which is adapted to engage each of a plurality of outwardly extending pins 89 which are equally radially spaced about the face of the drive wheel 4t). Thus, when the pawl 85 is positioned with its arm 83 in engagement with a pin %9 as is shown in FIGURE 4, extensible movement of the power member 53 will act to rotate the drive wheel ill in a counterclockwise direction. By exactly controlling the limit of extensible movement of the power member 53, the are through which the drive wheel 40 is rotated during any given power stroke of the power member 53 may be exactly determined.

A cam face 9% is formed on the outermost end of the arm 88 which is operable, upon retractable movement of the power member 63, to engage one of the pins 8? to pivot the pawl 85 around the pin until the finger 88 drops over that pin in the manner shown in FIGURE 4.

Eight pins are equally spaced about the face of the drive wheel til so that each power stroke of the power member 53 will be eiiective to rotate the drive wheel 40 through 45.

As hereinbefore mentioned with respect to FIGURE 3, rotation of the drive wheel 4t; through 45 will be effective to rotate the gear wheel 36 through 180 to thereby pivot the ice tray from one extreme rotated position to another.

FIGURE 8 illustrates diagrammatically a circuit which might be employed to control the operation of an ice making apparatus of the type herein shown and described. The resistor heater 68 is energized through the snap acting switch 79, a. selector switch 92, and a line switch 93 from a power source 94. A slug valve is diagrammatically illustrated as being energizable through one pole of the selector switch 92 and the line switch 93. The slug valve which is not illustrated in the other figures in the drawings may be of any type which is Well known in the art; generally comprising a means for collecting a predetermined volume of water and thereafter dispensing the same through a filler tube to the ice tray 15. It will however be understood from FIGURE 8 that filling of the ice tray upon energization of the slug valve 95 can never take place while the heater coil 63 is energized and while the ice tray is rotating. Conversely, rotation of the ice tray it; upon energization of the heater coil 68 cannot be effected while the slug valve 95 is energized.

Referring to FIGURES l, 4, 5 and 7, a horizontally movable ice sensing arm 10s is pivotally mounted by means of a pin 101 on a pair of spaced brackets 152 which are aflixed to the upstanding support 13. The line switch 3 is mounted on the opposite end of the leg 76 from the adjusting screw '78 and has a plunger 94 extending therefrom which extends through an aperture in the leg 76 to a point adjacent one end of the sensing lever 16%). The switch 93 is so arranged that the movable contact 105 thereof, which is normally biased to an open circuit position by spring 94a, is maintained in a closed circuit position as long as the plunger 94 is maintained in a depressed position. A spring lilo interconnects the leg 76 with the adjacent end of the ice sensing lever 16% to normally urge the lever 11% to hold the plunger 94 in a depressed position. It will be observed that when the power member 53 moves extensibly from the power unit St} the sensing lever will pivotally sweep horizontally across the upper surface of the collection tray 38 in a clockwise direction as viewed in FIG- URE 7. Upon retractable movement of the power memunset her 53 the sensing lever f ll) will then be urged to pivotally return in a counterclockwise direction through the spring res. However, if return pivotal movement of the sensing lever liltl is prevented due to an accumulation of frozen ice blocks in its path of return movement, the lever 1% and leg 76 will have relative movement away from one another against the opposing iasing force of Spring 196. Such relative movement between lever fill and leg 75 will permit the plunger 94 to move extensibly from its housing to break the circuit through the switch and thereby decnergize the entire ice making apparatus. Thus the ice making assembly can be controlled as a function of the level of ice blocks within the collection tray 30.

We have thus provided an automatic ice making assembly with a novel control mechanism tnerefor in which the ice making apparatus per se is operated as a function of the rate of freezing of water within the ice tray and as a function of the level of ice blocks within the collection tray.

t will be understood that this embodiment has been used for illustrative purposes only and that various modifications and variations in the present invention may be effected without departing from the spirit and scope of the novel concepts thereof.

We claim as our invention:

1. In combination with an ice making assembly including an ice tray adapted to be pivoted through an arc of less than 180 to effect ejection of ice blocks therefrom, the improvement of means for pivoting the ice tray comprising a link arm connected to the ice tray at the pivotal axis thereof and extending radially therefrom, a drive Wheel and gear wheel drivingly engaging one another, a link arm connected to said gear wheel and extending radially therefrom, a drive link pivotally interconnecting said link arms, so positioned that the point of connection of said drive link with said second mentioned link arm never crosses the longitudinal axis of said first mentioned link arm, and means energizable as a function of the temperature of fluid within the ice tray for effecting rotatable movement of said drive wheel.

2. In combination with an ice making assembly including an ice tray adapted to be pivoted through an arc of less than 170 to effect ejection of ice blocks therefrom, the improvement of means for pivoting the ice tray comprising a link arm connected to the ice tray at the pivotal axis thereof and extending radially therefrom, a drive wheel and gear wheel drivingly engaging one another, a link arm connected to said gear wheel and extending radially therefrom, a drive link pivotally interconnecting said link arms, so positioned that the point of connection of said drive link with said second mentioned link arm never crosses the longitudinal axis of said first mentioned link arm, and power means energizable as a function of the temperature of fluid within the ice tray having an element extensible therefrom upon energization thereof, and a mechanical transducer interconnecting said element with said drive wheel to effect rotation of said drive wheel upon extensible movment of said element from said power means.

3. In combination with an ice making assembly including an ice tray mounted within a freezing compartment and adapted to be pivoted through an arc of less than 180 to effect ejection of ice blocks therefrom, the improvement of means for pivoting the ice tray comprising a link arm connected to the ice tray at the pivotal axis thereof and extending radially therefrom, a drive wheel and a gear wheel drivingly engaging one another, a link arm connected to said gear wheel and extending radially therefrom, a drive link pivotally interconnecting said link arms, so positioned that the point of connection of said drive link with said second mentioned link arm never crosses the longitudinal axis of said first mentioned link arm, temperature sensitive power means having an element extensible therefrom upon predetermined ambient temperature conditions therearound mounted within the freezing compartment, a mechanical transducer interconnecting said element with said drive wheel to effect rotation of said drive wheel upon extensible movement of said ele ment from said power means, biasing means for urging said element to a retracted position with respect to said power means, and means for heating said power unit as a function of the position of said element with respect thereto.

4. In combination with an ice making assembly including an ice tray adapted to be pivoted through an arc of less than to effect ejection of ice blocks therefrom, the improvement of means for pivoting the ice tray comprising a link arm connected to the ice tray at the pivotal axis thereof and extending radially therefrom, a drive Wheel and a gear wheel drivingly engaging one another, a link arm connected to said gear wheel and extending radially therefrom, a drive link pivotally interconnecting said link arms, so positioned that the point of connection of said drive link with said second mentioned link arm never crosses the longitudinal axis of said first mentioned link arm, power means energizable as a function of the temperature of fluid within the ice tray having an element extensible therefrom upon energization thereof, a plurality of engagement means spaced about the axis of said drive wheel on one surface thereof, and a one-way drive connection between said element and said engagement means for effecting rotatable movement of said drive wheel upon movement of said element with respect to said power unit in at least one direction.

5. A control mechanism for pivoting a shaft comprising a rotatable wheel, link arms ailixed to said rotatable wheel and said shaft and extending radially therefrom, a drive link interconnecting said link arms wherein the components are so arranged that the longitudinal axis of said drive link never crosses the longitudinal axis of the shafts link arm, a power unit having an element extensible therefrom upon energization thereof, motion translation means interconnecting said element with said rotatable Wheel to effect rotatable movement thereof upon extensible movement of said element, means biasing said element to a retracted position with respect to said power unit, and means for controlling the energization of said power unit as a function of the position of said element with respect to said power unit.

6. In combination with a power unit having an element extensible therefrom upon energization thereof and having means biasing the said element to a retracted position with respect to the power unit, the improvement of means for controlling the energization of the power unit comprising a switch for controlling energization of the power unit, connected to the power element and movable therewith and having a movable contact member for operating the switch, and abutment means positioned in the path of movement of said movable contact to engage said contact and move same when said power element has reached its most extended and most retracted position with respect to said power unit to continuously effect intermittent energization and deenergization thereof.

7. In combination with an ice making assembly including an ice tray mounted within a freezing compartment and adapted to be pivoted through an arc of less than 180 to effect ejection of ice blocks therefrom, the improvement of means for pivoting the ice tray comprising a link arm connected to the ice tray at the pivotal axis thereof and extending radially therefrom, a drive wheel and a gear wheel drivingly engaging one another, a link arm connected to said gear wheel and extending radially therefrom, a drive link pivotally interconnecting said link arms, so positioned that the point of connection of said drive link with said second mentioned link arm never crosses the longitudinal axis of said first mentioned link arm, a power unit having an element mounted within the freezing compartment extensible therefrom upon energization thereof and having means biasing the said element to a retracted position with respect to said power unit, a mechanical transducer interconnecting said element with said drive wheei :0 effect rotatable movement of said drive wheel upon movement of said element with respect to said power means in at least one direction, a switch for controlling energization of said power unit connected to said element and movable therewith and having a movable contact member for controlling the operation thereof, and abutment means positioned in the path of movement of said movable contact to engage said contact and move same when said power element has reached its most extended and most retracted positions with respect to said power unit.

776,174 Dixon Nov. 29, 1904 France (Addition to No. 2,5 67)