US3423949A - Automatic ice cube maker - Google Patents

Description

Jan- 28, 1969 M. G. LEEsoN ETAL.

AUTOMATIC ICE CUBE MAKER Filed April 28, 1967 Sheet GERALD LL'L-so/v HAROLD H. 5555/? 5 f7, 7%@

344 ,80 MEL 00N `iam. 28, 1969 M. G. LEEsoN ETAL 3,423,949

AUTOMATIC ICE CUBE MAKER Filed April 28. 1967' )NVE/vrom. Mano/v GERM@ E550/v Hmow H. 5555/? www United States Patent O 3,423,949 AUTOMATIC ICE CUBE MAKER Meldon Gerald Leeson, Berwyn, and Harold H. Esser,

Chicago, lll., assignors to Schneider Metal Manufacturing Co., Chicago, Ill., a corporation of Illinois Filed Apr. 2S, 1967, Ser. No. 634,606 U.S. Cl. 62-73 29 Claims Int. Cl. F25c 1/12, l/ZZ, 5/08 ABSTRACT OF THE DISCLOSURE An automatic ice cube maker having a grid for dissecting a slab of ice to form ice cubes, the grid consisting of a substantially monoplanar lattice of heated wires dening closed meshes so that the slab is cut through simultaneously along intersecting planes; a control system for timing and recycling ice production, the control system having an ice harvesting timing mechanism and a temperature sensor to override the timing mechanism when the full allotted time is not required for ice harvesting operations; and sensor means to term'mate further production of ice cubes when ice cuzbes accumulated in a storage bin exceed a predetermined level.

This invention relates to ice maker apparatus of the type which automatically produces ice cubes or cubelets. More particularly, the invention is directed to an improved cutting grid and to an improved cycling and control system for automatic ice cube makers.

Many ymachines for producing ice cubes automatically are known in the prior art, and these machines have taken various physical forms and have utilized various engineering mechanisms and techniques. Both mechanical and thermal means have been used to produce cubes of ice from larger lblocks or slabs. In ice cutting apparatus utilizing thermal means, electrically heated wires have been widely employed as the cutting elements, and these electrically heated Wires, or their functional equivalents, have been arranged in parallel arrays to dene blockor slab-cutting elements. In forming ice cubes from block ice, the cutting operations must be carried out in three planes at right angles to each other, and this operation has been achieved through the use of three separate sets of parallel wires, the wires of each set being positioned so as to cut the ice in the three planes at right angles to each other. In forming ice cubes from slabs of ice, the prior art technique has been to use two separate grids which are spaced from each other and which carry separate parallel arrays of wires disposed at right angles to one another. It is to a novel single grid slab-cutting apparatus, which constitutes a marked improvement over the above described two-grid systems, that one facet of the present invention is directed.

Ice maker apparatus of the type in which a slab of ice is formed on the evaporator plate as a result of owing water over the plate while the plate is suitably refrigerated is well known in the prior art. In such apparatus the slab forming refrigerated plate is conventionally slightly inclined facilitating the desired water flow and permitting the finished ice slab to slide downwardly, along the plate, when ulti-mately freed. In the prior art machines the released slab is guided to fall upon a grid of parallelly disposed cutting means such as electrically heated wires, and a second, separate grid spaced below the first grid and supporting an array of parallel wires disposed transversely of the rst set of wires completes the slab cutting means so that the slab may be cut into a plurality of discrete units constituting prisms, cubes, or the like.

While the improved grid or lattice of the present invention `finds utility in the ice slab-forming apparatus of the above described type, the present invention is described herebelow with reference to an ice maker in which the slab of ice to be transformed into cubes is formed on the underside of a refrigerated plate or an evaporator. Although the concept of forming an ice slab on the underside rather than on the top surface of an evaporator plate is not broadly new, the present invention includes important engineering advances in this type of ice maker.

It `will readily `be appreciated by those skilled in the art that in delivering a slab of ice from` the unders-ide of a freezing plate onto an ice cutting grid supported therebelow, the slab may be dropped directly downwardly onto the grid, thus obviating any need to shift the slab generally lhorizontally to clear the freezing plate, as required in the case of slabs formed on top surfaces of evaporator plates. That is, important space saving is achieved through the use of the apparatus of the present invention in which the slab is formed on the underside of an evaporator plate. Other advantages associated with this structure will become evident as the description proceeds.

One facet of the present invention is directed to a structure and technique Vby means of which a slab of ice may be simply and conveniently dissected or otherwise transformed into prisms or cubes in a single thermal cutting operation utilizing only a single grid, the cutting of the slab along transverse planes being effected simultaneously.

The release of slabs to fall upon wire grids supported therebelow has subjected these grids to life-shortening shocks and stresses. It is a featureof the present invention that the relatively heavy slab is delivered to interwoven or interlaced, or otherwise crossing interconnected weight-distributing ice cutting elements which constitute the improved slab cutting lattice of the invention. In a preferred embodiment of the invention, the ice cutting, lattice-forming elements which traverse and bridge the opening dened by their encircling frame are coupled to or otherwise attached to the lattice framing members through shock-absorbing structures such as spring means which maintain the cutting elements tensioned yet resiliently responsive to forces impinging thereon yieldingly to absorb these forces.

The force of the falling slab of ice, is, in accordance with the practice of the present invention, distributed substantially uniformly over the entire area of the ice cutting lattice, since one Set of parallelly .arrayed ice cutting elements is in direct physical contact with a second generally transversely disposed array of cooperating ice cutting elements.

It is a principal feature of the present invention that electrical energy is supplied to the grid across spaced parallelly extending bus bars in a manner to heat Simultaneously all segments of the lattice which define the closed meshes of the unitary grid structure. In a preferred embodiment of the improved ice cutting grid of the invention, the novel lattice grid comprises parallel electric-al circuits in which the conductive paths between opposed terminals are zig-Zag or saw-tooth in form.

Another feature of the invention is a control system which automatically frees the formed ice slab from the evaporator plate and deposits it on the ice cutting grid. An important feature of this control system comprises means for sensing that the ice has dropped off the evaporator plate and for immediately initiating the remaining phases of the harvesting and recycling operation. This novel feature eliminates any necessity for waiting out 4a fixed duration of the timed operation, and causes the machine to resume ice production quickly and efficiently. The advantages of a timed ice harvesting operation are retained with the improvement of la sens-or which overrides the timer to cut short the unneeded portion of the ice harvesting time period.

Yet another feature of the invention is a structural arrangement by means of which the level of ice cubes contained in a collector or storage bin disposed below the ice cutting grid may be sensed or detected when that level has reached a predetermined height, the sensing means being operative to effect termination of further freezing and ice 'cube making cycles so that ice cube production will not exceed the need.

Other features and advantages of the invention will become apparent from a reading of the following specication taken in conjunction with the drawing in which:

FIGURE l is a perspective View of an ice maker which includes a slab dissecting grid assembly embodying the invention;

FIGURE 2 is a top plan view of one embodiment of a grid or lattice having a structure in accordance with the teachings of the invention;

FIGURE 3 is an enlarged fragmentary view, partly in section, showing the portion of the grid circled in FIG- URE 2 and showing interlinked closed-mesh-dening wire elements and resilient grid wire anchoring means;

FIGURE 4 is a top plan view of a second preferred embodiment of the ice-slab-cutting grid of the invention;

FIGURE 5 is an enlarged fragmentary view, partly in section, showing the portion of the grid circled in FIG- URE 4 and showing an interwoven mesh structure, resilient support means, -and means connecting the ice-cutting wire to an electrical bus bar;

FIGURE 6 is a side elevational view of the ice-slabcutting grid assembly showing the mechanism for raising and lowering the grid assembly, and showing the ice cube detecting mechanism for suspending ice cube production when the ycubes have reached a predetermined level.

FIGURE 7 is a schematic diagram showing the electrical control circuit of the invention;

FIGURE 8 is a diagram showing the refrigeration and ice freezing system of the invention; and

FIGURE 9 is a front elevational view showing the cam for actuating controlling microswitches, which cam is driven by the grid gear motor.

Two preferred forms of the grid of the present invention, provided only for the purpose of illustrative disclosure and not by -way of limitation, are depicted in FIG- URES 2 and 3 and FIGURES 4 and 5. In the drawing, the perspective View, FIGURE l, shows an ice maker incorporating the features of the invention and including the novel grid structure. The ice maker 10 includes a refrigerated plate or evaporator plate 12, and a water jet tube 16 for supplying water to the underside 18 of the evaporator plate 12 to build `an ice slab 22 thereon. The freezing plate 12 is inclined downwardly from front t0- Ward the rear, and owing water 24 in excess of that transformed into ice on the evaporator plate 12 is received in a collecting trough 26 positioned below the evaporator plate at its lower end. The water collected in the Itrough is subsequently and continuously recirculated to the plate 12 through a pipe 32, by means of a suitable pump 36. In a preferred form of the invention the water recirculated is ultimately automatically discarded as waste so that build-up of objectionable solids in the Water system is avoided. Control is effected through water dump solenoid 37.

Refrigerant is supplied to the evaporator 12 through a suitable pipe 40 from a conventional refrigeration assembly (not shown). A slab of ice is built up upon the underside surface of the evaporator plate 12 yand when the ice slab 22 has reached the desired thickness, the plate is heated so that the slab 22 is freed and drops upon the frame-supported ice-cutting grid assembly 44 which is disposed below the plate 12 in substantial vertical correspondence therewith. While any preferred slab thickness sensing devices such as optical, mechanical or electrical sensors, or timers may be used, and while any preferred slab-freeing technique may be employed, in the preferred embodiment of the present invention a timer is used to control the ice thickness, and warm fluid is circulate-d through the evaporator plate to free the ice slab. The ice slab 22 is supported upon the heated ice-cutting means 48 which melt their Way into the ice slab, the slab advancing downwardly by gravity to pass through the grid 44 as the ice `slab 22 is dissected into discrete units such as prisms, cubes 50, or the like, the formed cubes falling into a storage receptacle or bin 54 below the ice cutting grid 44.

The ice slab cutting grid assembly 44 includes a frame 56 which is preferably generally rectangular in form and comprises a pair of rearwardly spaced parallel channel bar frame members 60 and 62 connected to one another at their respective ends by means of a transversely eX- tending pair of laterally spaced parallel frame members 66 and 68. The frame 56 is pivotally mounted by means of U-shaped slots 70 which Iare formed in plates 74 fastened to the frame 56 at opposed rearward lateral portions thereof, the slots 70 receiving therewithin cooperating pivot pins or hinge rods 78 so that the frame 56 is journalled for arcuate movement through a vertical plane. A frame-supporting link S0 provided with a slot 82 is coupled -at its lower end to a rod or pin 84 fastened to and extending laterally outwardly of the frame 56 at a position substantially midway along the length of the side framing member 68 as shown in FIGURE 6. At its upper end the link is fastened to and depends from a crank arm 88 fastened to the drive shaft 90 of a motor 92 through which assembly the frame 56 is pivoted between a lower, substantially horizontal position, to -a rearwardly tilted sloping position, as more fully described hereinbelow.

It is a most important facet of the inventive concept of this invention that electrically heated ice slab cutting elements form a substantially planar integral unit and dene a lattice of cutting segments the ends of which are in contact electricallyto provide an array of closed meshes. Within this novel .and inventive concept, it is contemplated that various structural arrangements may be used to provide lattices or grids operative in `accordance with the principles of the invention, one exemplary physical structure being illustrated in FIGURES 2 and 3, and a second embodiment being shown in FIGURES 4 and 5.

Referring more particularly to the drawing, and rst to FIGURES 2 and 3, there is shown, for the purpose of illustrative disclosure, one preferred form of the invention including a novel lattice structure. Opposed forward and rearward framing elements 60 and 62 of the frame 56 carry electrical terminal strips or bus bars and 102 which are electrically insulated from the Vframe 56, the terminal strips being connected to the secondary or output of a step-down transformer 110, the latter being indicated schematically in FIGURE 2 and serving to reduce a supply voltage, such as a conventional volts supply to a low value, which in the particular embodiment of the invention shown is conveniently in the range of about 3 volts. Electrically resistive ice-cutting elements or wires 114 provide conductive paths between the opposed terminal strips 100 and 102, the passage of current through the wires 114 effecting the required heating for cutting the ice slab, The lateral framing elements 66 and 68 of the grid frame 56 are insulated electrically from the terminal strips 100 and 102 and form no part of the electrically conductive circuit.

In the structures of FIGURES 2 and 3, the heated wires 114 which form the lattice execute zig-zag or sawtooth paths between the forward 100 and the rearward 102 conductors of the electrical supply system. As seen most clearly in the enlarged detail of FIGURE 3, a given wire element 118 is intercoupled or looped around its next adjacent cooperating element 120 in a manner suggestive of widely used linked wire fencing. The extreme lateral elements or runs are supported at linearly spaced positions along the side framing members 66 and 68, points of support along these framing members being electrically insulated from the frame itself, as shown in FIGURE 3. The points of support of the lattice along the forward and rearward framing elements 60 and 62 are connected electrically to respective bus bars 100 and 102 so that the overall lattice defines a plurality of parallel electrical networks extending between the opposed conductors 100 and 102. Through this novel arrangement all segments of the lattice are electrically heated to substantially the same temperature so that even cutting of or melt-through of the ice slab is achieved.

When freed from the underside 18 of the evaporator plate 12, the ice slab 22 drops downwardly onto the cutting grid 44 (FIGURE l). In a preferred embodiment of the present invention, in order to absorb the shock associated with the ice slabs falling onto the grid, the ice cutting means or grid wires 48 are resiliently mounted or tensioned on the grid frame 56, one preferred embodiment of a grid wired tensioning assembly being illustrated in FIG- URE 3. As shown, the tensioning and shock absorbing assembly 126 includes a rod 128 which extends through and is resiliently mounted against a side-wall 130 of the framing member 66. A anged insulating bushing or grommet 134 extending through an opening 136 in the side wall or web 130 isolates the wire tensioning assembly 126 electrically from the frame 56. At its inward end the rod 128 is provided with a slanted slot 140 into which the grid wire is inserted, and a spring 142 interposed between the insulating bushing 134 and a nut 144 threaded on the end 146 of the rod 128 resiliently urges the rod laterally outwardly from the frame to maintain the grid taut and tensioned. While in the particular wire-tensioning assembly illustrated the spring comprises a coiled element, other types of springs such as band or leaf springs 150 may be used. Such an arrangement is shown in FIGURE 5.

Referring now to FIGURES 4 and 5, there is shown a second mechanical embodiment of the improved grid structures of the invention. Whereas in the structure of FIG- URES 2 and 3 the conductive elements are intercoupled or interlinked at their contact points, the conductive elements 160 of the grid illustrated in FIGURE 4 and in the enlarged detail of FIGURE 5 form a woven lattice in which a given linearly extending wire element 164 follows a path which alternately goes over and then under cooperating wire elements 166 and 168 extending generally transversely of the given element. Notwithstanding the clearly evident mechanical differences in the two preferred embodiments of the invention shown, the equivalent electrical circuits of the two forms of the grid or lattice are the same. In 'both grid structures each incremental length of any given conductive element is heated to substantially the same temperature as other incremental potrions of the lattice so that the slab is cut through evenly.

The closed mesh lattices of the present invention may be fabricated using a single length, a double length, or any preferred number of separate wires. In order to provide a practical commercial structure and to simplify servicing and repair procedures, the lattices of the invention are preferably fabricated using a plurality of wires, and it is an important feature of preferred forms of the invention that is particular lattice configurations, all wires are of equal length. Referring first to FIGURES 2 and 3, each of the wires 114 defines a stepped, saw-tooth, or zig-zag configuration as it extends between the bus bars 100 and 102 and opposed parallel framing elements 60 and 62. In this 6 grid form, each wire is intercoupled or linked, alternately, with wires at either side (FIGURE 3). In the lattice of FIGURES 4 and 5, the ice cutting wires 160 extend along L-shaped paths the legs 164 and 16411 of which are angled with respect to the bus bars and to the opposed framing members to which ends of the wires are anchored, Al-

though for different wires the lengths of respective legs will differ, in each case the combined lengths of the legs is the same for each wire. It will be appreciated that the use of one wire length reduces stock requirements and greatly facilitates rep-lacement of any broken wires.

Any preferred mechanical means and technique may be used to connect the ice cutting means 48 to the currentsupplying bus bars and 102 one suitable arrangement being shown in FIGURE 5. The bus bar 100 is provided with linearly spaced lugs, posts, or bosses 172 extending perpendicular to a plane defined generally by the wire lattice. The ends of the wires are formed with closed loops 176, these looped portions being anchored over the posts 172, and the wire then passing through openings 178 in the frame element. Alternatively the anchored wires may be guided over a longitudinally extending edge of the bus bar.

While the use of wires as ice slab cutting elements constitutes a preferred mechanical means, the grids of the invention may be formed by other methods as well, such as by stamping, expanding techniques, electroplating, and through printed circuit techniques.

During ice cutting, as well as during intervals between ice slab cutting operations, or in its rest or standby position, the ice-cutting grid assembly 44 is supported over the ice storage bin 54 in a generally horizontal plane. While the heated grid is melting its way through the ice slab supported thereon, a second ice slab is being formed on the underside of the evaporator plate 12. The rate at which heat energy is supplied to the cutting wires of the grid is such that these wires will melt through an ice slab in somewhat less time than is required for a subsequent slab of the desired thickness to be produced. The cubes from the dissected slab pass through the grid and are deposited in the bin 56.

When the ice slab thickness control element, which is preferably a timer, but which may be an electrical or mechanical sensor, is actuated indicating that the new slab has reached a predetermined thickness, Warm gas or lluid is circulated through the channels of the evaporator plate to free the frozen slab. At the same time the motor 92 is energized to lift or pivot the grid 44 toward the evaporator plate so that the distance through which the freed slab falls is minimized. After the ice slab falls upon the grid, the motor 92 is actuated and the grid moves or pivots downwardly to assume a substantially horizontal position, this position being -maintained throughout the cutting operation so that right prisms are formed from the ice slab.

The preferred embodiment of the invention may be considered, for purposes of disclosure, as consisting of four cooperating systems: the refrigeration system, the water system, the ice cutting system, and the control system. The ice cutting system has been described above in detail, and the three remaining systems are described below.

The operation of the refrigeration system shown in FIGURE 8 is as follows: A compressor 202 circulates refrigerant through a condenser 204, a receiver tank 206, and a drier-strainer 208 and through an evaporator 212 to form an ice slab on the underside of the evaporator plate 12 of FIGURE 1. When an ice slab of predetermined thickness has formed on the evaporator plate 12, and upon command from the control system, the hot gas solenoid 210 opens to permit hot refrigerant gas to flow into the evaporator 212 directly from the compressor 202. The hot gas heats the evaporator plate 12, freeing the ice slab which then drops onto the frame-supported ice cutting grid assembly 44. When the ice separates from the evaporator plate 12, a thermostat switch 310 senses the hot refrigerant, closes the hot gas solenoid 210 and opens the expansion valve 209 to initiate a new freezing cycle.

Operation of the water system is described with reference to FIGURE 1. Water is introduced through a conventional float valve (not shown) into a collecting trough 26. A water pump 36 pumps water from the trough 26 through a conduit 32 to the higher end of evaporator plate 12, the water then flowing across the underside of the evaporator plate 12 whereby a portion of the water freezes to form a film of ice. The remaining water returns to the trough 26 to be recirculated. The process continues until a slab of the desired thickness is formed. At the beginning of the ice harvest cycle, a water dump solenoid 37 opens to effect discharge of the water in the trough 26 thereby eliminating all accumulated objectionable dispersed solids. The water pump 36 then turns off. At the end of the ice harvest cycle the water dump solenoid 37 closes and as the freezing cycle is reinitiated the water pump 36 is restarted.

The control system is illustrated schematically in FIG- URE 7. A source of electric current is fed through a main switch 302 to operate selected combinations of components to control the freezing and harvesting cycles. Time switches 306i, 306 and 306iz'z', of conventional design, are operated by the timer motor 308; and any selected switch may be actuated to provide a choice of a twenty-two minute, thirty minute, or forty-five minute ice production cycle followed by a 4 minute ice harvest cycle. The freezing operation is initiated by actuating one of the time switches 306. At the beginning of the freezing cycle, the following components are energized: the grid power transformer 110, the compressor motor, the timer motor 308, the condensor fan 95, and the water pump 36. At the beginning of the ice harvest cycle, the hot gas solenoid 210, the water dump solenoid 37 and the grid gear motor 92, are switched on, while the condensor fan 95 is switched off. The grid gear motor 92 raises the grid assembly 44 to receive the ice slab as water is drained, and heated refrigerant ows into the evaporator 212 to free the ice slab from the evaporator plate 12.

After the grid gear motor 92 has lifted the cutting assembly 44 to the up position, the grid gear motor 92 is switched off, as is the water pump 36. The ice drops yfrom the evaporator plate 12 onto the grid wires 114. After the ice is freed from the evaporator plate 12, or after a predetermined time, the grid gear motor 92 is again energized to lower the grid assembly 44. The hot gas solenoid and water dump solenoid 210 are closed, and the condenser fan 95 is again turned on to begin a new freezing cycle.

The prescribed sequential actuation of the above described components is accomplished by means of the novel control system shown schematically in FIGURE 7. A microswitch 312 controls the water pump 36, and `a second microswitch 314, the grid gear motor 92. Microswitches 312 and 314 are actuated by a cam 320 (FIG- URE 9) driven by the grid gear motor 92. It is an important feature of the invention that the evaporator thermostat switch 310 operates to override the four minute timer if the ice slab is freed from the evaporator plate 12 in less than four minutes. Thus, when the grid assembly 44 is raised to receive an ice slab, if the slab drops from the evaporator plate in a time less than four minutes, the evaporator thermostat switch 310 is actuated by the hot gas passing through the evaporator 12 to terminate the ice harvest cycle and resume the freezing cycle without waiting for the full four minute time period to elapse.

The operation of the control circuit is more clearly shown when the schematic circuit diagram of FIGURE 7 is considered in conjunction with Chart I which shows the position of the controlling switches at each phase of the freezing and ice harvesting operations.

CHART I.-SWITCH POSITIONS Switch Numbers Phase I: Freezing in progress; grid assembly in down position A A A B B A Phase II: Start of ice harvest; grid assembly going up A A B A B A Phase III: Ice harvest in progress; grid assemblyinup position A A B A A B Phase IV:

(a) Ice harvest ended by actuation of evaporator thermostat; grid assembly going down A A B B A B (b) Ice harvest ended by actuation of four minute timer A A A A B A Another important feature of this invention is an ice sensing system which operates to suspend ice production when the bin contains an adequate supply of ice cubes. As shown in FIGURE 6, an ice sensing b'ar 340 is fastened to and extends downwardly from the grid assembly 44, and an extension link 344, fastened to the grid assembly 44, extends upwardly thereof toward a microswitch 304-. If the ice cube level exceeds a predetermined maximum, when the grid assembly 44 is lowered, the ice sensing bar 340 will abut the stored ice cubes and the grid will stop i-ts downward travel. The slotted frame supporting link 80, and the microswitch 304 continue downwardly until the extension link 344 contacts and opens the microswitch 304 to turn off the machine. When the ice cube level drops, the microswitch 304 opens and the machine resumes ice production. This novel automatic cut-off systern precludes the possibility of turning off the machine while an ice slab remains on the evaporator plate 12 from which it could drop to damage the grid assembly 44. It also assures that the machine will restart each time on a full production cycle. Since this cut off system does not utilize a thermostat, it is not affected by ambient temperiature and would thus permit turning of the grid heating current during dormant periods.

It is to be understood that the specific embodiments of the invention shown in the drawings and described above are merely illustrative of the many forms which the invention may take in practice without departing from the spirit of the invention or from the scope of the invention as defined in the appended claims.

What is claimed is:

1. In an ice maker apparatus including means for forming a slab of ice and means for causing said slab to bear upon ice-cutting means for dissecting said slab, said icecutting means including a frame and frame-carried icecutting elements', the improvement wherein, in use, said ice-cutting elements define meshes of a lattice consisting of contacting, crossing, electrically connected and resistively heated ice-cutting segments; and electrical circuit means operatively coupled to said ice-cutting elements and developing resistively generated thermal energy therein for heating of said elements to cut through said slab of ice bearing thereon.

2. A lattice as set forth in claim 1 wherein said icecutting means comprise electrically heated wire means in electrical contact and lying in substantially the same plane, said ice-cutting means defining a grid for cutting said slab of ice bearing thereupon.

3. A lattice as set forth in claim 2 wherein said icecutting means comprises woven means forming a unitary grid of closed meshes within said frame.

4. The structure as set forth in claim 3 wherein said lattice comprises a plurality of separate Wires crossing and contacting one another and extending between framing members of said frame to define a grid of closed meshes.

5. The structure as set forth in claim 2 and further comprising anchor trneans resiliently mounting said wire means in said frame.

6. The structure as set forth in claim 3 wherein said wire means comprises electrically conductive wires interlinked to form a generally planar network of closed meshes.

7. The structure as set forth in claim 2 wherein said wire means of said lattice execute L-shaped paths within said frame, said fname being substantially rectangular in outline, and further comprising means anchoring opposite ends `of said wire means on corresponding opposite parallelly disposed frame members, and means supporting said wire means, intermediate ends thereof, on a frame member interconnecting and extending transversely of said parallelly disposed frame members.

8. The structure as set forth in claim 3 wherein said Wire means execute zig-zag paths between opposed parallel grid support members of said frame.

9. The structure as set forth in claim 2 wherein said frame defines a generally rectangular opening and wherein said wire means extend between and interconnect a pair Iof opposed grid-support members of said frame, said structure further comprising electrically conductive means connected to said wire means adjacent said opposed grid support members and adapted to deliverelectrical energy to said wire means to lheat said grid resistively.

10. The structure as set forth in claim 1 and further comprising means supporting said frame for movement through a vertical plane.

11. The structure as set forth in claim 1 and further comprising an ice-storage bin positioned below said frame to receive ice delivered therefrom, sensing means carried by said frame for movement therewith and extending downwardly of said frame-carried lattice and toward a top opening of said bin, said sensing means being operative to detect ice in said bin when ice accumulated therein fills said bin above a predetermined level, and

switch means coupled with and responsive to said sensing means to terminate freezing operations of said ice maker when the level of ice in said bin is above said predetermined level.

12. The structure as set forth in claim 11 and further comprising means supporting said frame for movement through a vertical plane extending upwardly of said bin, whereby upon movement of said frame downwardly toward said bin said sensing means enters said bin to detect ice present therein above said predetermined level.

13. The structure as set forth in claim wherein said means supporting said frame supports said frame for arcuate pivotal movement.

14. 'l'he structure as set forth in claim 12 wherein said means supporting said frame supports said frame for arcuate pivotal movement.

15. The structure as set forth in claim 13 and further comprising motor means for controlling the pivotal movement of said frame.

16. The structure as set forth in claim 14 and further comprising motor means for controlling the pivotal movement of said frame.

17. The structure as set forth in claim 15 and further comprising switch means responsive to separation of an ice slab from said ice forming means to actuate said motor means to pivot said frame toward said bin.

18. The structure as set forth in claim 16 and further comprising switch means responsive to separation of an ice slab fromsaid ice forming means to actuate said motor means to pivot said frame toward said bin.

19. The structure as set forth in claim 3 wherein said frame defines a generally rectangular `opening and wherein said wire means carried by said frame extend between a pair of spaced generally parallel opposed framing members and cross said opening to bridge said opening along paths which are greater in length than the distance between said opposed framing members.

20. The structure as set forth in claim 19 and further comprising circuit means suppling wire-heating current to said wire means along a conductive path generally parallelling `a pair of said opposed framing members of said frame.

21. In the method of forming ice cubes wherein a slab of ice is cut by heated slab-supporting ice-cutting means upon which said slab is brought to bear, and wherein the cutting operation is carried out so as to cut through said slab generally transversely of a principal face thereof, the steps comprising liowing water on a refrigerated plate to form a slab of ice thereon,

freeing said slab from said plate,

depositing said slab to bear on a lattice of ice cutting elements including electrically conductive crossing segments electrically connected at cross over points.

and lying substantially in the same plane and defining a grid of closed meshes,

applying electrical power to said lattice to heat said crossing segments resistively and to develop thermal energy in each of said ice cutting elements of said lattice upon which said slab is brought to bear, and

cutting said slab simultaneously along substantially coplanar intersecting lines defined by said grid of closed meshes to transform said slab, in a single cutting operation, into a plurality of discrete portions each of whose through thickness is correlated with and corresponds to a through thickness of said slab and each of whose dimensions in breadth and height are substantially less than breadth and height dimensions of the slab from which said portions are cut.

22. In an ice cube making machine including ice slab forming means and ice slab dissecting means,

a control system for sequentially cycling ice production and ice harvesting, said control system comprising:

timer means providing a first time period for production of ice on said ice slab forming means, and a second time period for freeing said ice from said ice slab forming means; and

temperature sensing and responsive means for detecting the freeing of said ice from said ice slab forming means, said' temperature sensing and responsive means being connected electrically in parallel with said timer means;

whereby said temperature sensing and responsive means, upon detecting the freeing of said ice from said ice slab forming means, operates to `override said timer means thereby terminating said ice harvesting prior to elapse of said second time period.

23. A control system as set forth in claim 22 wherein said timer means is a motor-driven electrical time switch, and wherein said temperature sensing and responsive means is a thermostatically controlled electrical switch.

24. A control system as set forth in claim 22 wherein said temperature sensing and responsive means `includes a thermostatically controlled electrical switch responsive to elevation in temperature of said ice slab forming means resulting from freeing of said ice from said ice slab forming means.

25. In an ice maker apparatus including means for forming a slab of ice and means for causing said slab to bear upon ice-cutting means for dissecting said slab, said ice-cutting means including a frame and frame-carried ice-cutting elements; the improvement wherein in use said ice-cutting elements define a lattice of electrically resistively heated wire means lying in substantially the same plane and comprising crossing wires electrically connected at crossover points and forming a network of closed meshes within said frame, and further comprising electrical circuit r-neans operatively coupled to said ice-cutting elements and developing resistively generated thermal energy therein for heating of said elements to cut through said slab of ice bearing thereon.

26. The structure as set forth in claim 1 and further comprising an evaporator plate, and means supplying water to an underside of said plate to form a slab ot' ice thereon.

27. The structure as set forth in claim 25 wherein said network defines a plurality of electrically conductive paths of substantially uniform voltage gradient; whereby lineally equal incremental segments of said wire means forming said network are electrically resistively heated to essentially the same temperature.

28. The structure as set forth in claim 25 wherein said network of closed meshes comprises a plurality of wires dening conductive paths in each of which there is substantially the same voltage gradient.

29. The structure as set forth in claim 1 wherein said lattice extends between two spaced substantially parallel References Cited UNITED STATES PATENTS 6/1954 Ayres et al 62-320 X 2/1962 Jaeger 62-347 X 1/ 1965 Swanson 62-320 11/ 1965 Cordes 62-233 X 4/ 1929 Brizzolara 62-62 10 ROBERT A. OLEARY, Primary Examiner.

W. E. WAYNER, Assistant Examiner.

U.S. Cl. X.R.

bus bars and wherein said ice cutting elements traverse 15 62-233, 320, 352; 219-201; 62--137 non-linear conductive paths between said bus bars.

UNITED STATES PATENT oFFICE CERTIFICATE 0F CORRECTION-- Patent No. 3,423,949 January Z8, 1969 Meldon Gerald Leeson et al.

It is certified that error appears in the above identified patent and that said Letters Patent are hereby corrected as shown below:

Column 5,

Column 1, line 56, "the" should read an line 62, "potrions" should read portions line 71, "is" should read in Column 8, line 64, after "woven" insert wire Signed and sealed this 31st day of March 1970.

(SEAL) Attest:

Edward M. Fletcher, Jr.

Commissioner of Patents Attesting Officer WILLIAM E. SCHUYLER, JR.

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