US3277661A - Ice cube making machine - Google Patents

Description

Oct.

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i I a g 6/ ICE CUBE MAKING MACHINE T. A. DWYER S Sheets-Sheet l /4 H "m 7 .26 fl z i f I 22 6/ 32 5-:- za-z I: Z /3 5mm 2529 l 39 "ll I I I I 56 i 55 55 38 i 46 E i J; lllh W THO/MA o H. o mom F/ G. 3 BY Gag 3.141%? ATTORNEY Oct. 11, 1966 Filed April 20, 1965 T. A. DWYER ICE CUBE MAKING MACHINE 5 Sheets-Sheet 2 THmmsA. OWYfR BY M ATTORNEY Oct. 11, 1966 T. A. DWYER 3,277,661

ICE CUBE MAKING MACHINE Filed April 20, 1965 5 Sheets-Sheet S 8/4 74 65 48a 43 V 4L2 4a m 64 INVENTOR. THaMAs'A. Dwyfl? ATTORNEY United States Patet 3,277,661 ICE CUBE MAKING MACHINE Thomas A. Dwyer, New York, N.Y., assignor to Square Cube Corp., Long Island City, N.Y., a corporation of New York Filed Apr. 20, 1965, Ser. No. 449,437 1 Claim. (Cl. 62135) This invention relates in general to ice cube making machines and more particularly to a novel control device for automatically cyclically producing ice cubes in an ice cube making machine.

Machines have been provided which produce ice cubes in a periodic manner by going through respective freezing and harvesting cycles; during the former operation the ice cubes are produced and during the latter operation the cubes are discharged by the machine into an appropriate receptacle. In machines of the type described it is essential to accurately initiate and terminate the respective freezing and harvesting cycles to insure optimum operation. Various types of control devices have been suggested for ice making machines. For example, in the machine disclosed in Patent No. 3,009,336, issued to I. R. Bayston et al. on November 21, 1961, the duration of the freezing cycle is related to the circulating water in the system.

More particularly, in the machine described in the aforementioned patent the circulating water system includes a nozzle connected to the water supply line. The nozzle ejects a stream of water in an arc-the radius of the arc varies with the pressure of the water. The path of the circulating water additionally includes orifices in the ice cube freezing compartments. As the cubes are produced the orifices are progressively covered by the cubes thereby increasing the pressure in the system. Thus, the water stream issuing from the nozzle at the beginning of the freezing cycle (at low pressure) is directed in a recirculating path in the system; when the water pressure reaches increased values at the end of the freezing cycle the water stream is then directed to a drain. As the water in the system is drained out of a reservoir, a switch, which is responsive to the water level in the reservoir, is actuated to terminate the freezing cycle. This latter operation is accomplished by biasing the armature of the switch to a normally closed position by a spring. A pilot tank, which reflects the Water level in the reservoir, is similarly connected to the armature of the switch and is adapted to actuate the armature to open the switch when the water level in the pilot tank is above a predetermined height. In other words, the force of the spring is balanced against the weight of water in the pilot tank.

A severe disadvantage has been encountered in this type of arrangement because the force exerted by the spring varies with ambient temperature, age and other environmental factors, thereby giving rise to irregularities in the control of the machine by producing freezing cycles of varying duration rather than a set and fixed duration. Accordingly, the ice making machine of the aforementioned patent requires substantial maintenance and repair since the tension in the spring must be constantly adjusted. Thus, the machine is extremely inefficient in operation and uneconomical in use.

It is an object of the present invention to provide an improved control device for controlling the duration of the freezing cycle in an automatic ice cube making machine.

It is another object of the present invention to provide a control device for controlling the duration of the freezing cycle in automatic ice cube making machines which is efficient in operation and economical to manufacture.

A preferred embodiment of the control device of the present invention for use in automatic ice cube making machine comprises first and second serially connected thermostatically actuated switches. When the temperature of the freezing compartment which produces the ice cubes reaches a first predetermined temperature of approximately 55 F. the first thermostatically actuated switch is operated to initiate the freezing cycle. During the freezing cycle the first thermostatically actuated switch is again operated (when the temperature of the freezing compartment drops to approximately 30 F.) to connect a source of potential across the second thermostatically actuated switch. When the temperature of the freezing compartment drops to approximately 10 F., at which time the ice cubes will be completely formed, the second thermostatically actuated switch is operated to terminate the freezing cycle and initiate the harvest cycle by applying the potential across a pair of solenoids; one of said pair of solenoids controlling the entrance of water into the reservoir for the production of a new batch of ice cubes and the other of said pair of solenoids allowing hot gas to fiow through the evaporator coil to warm the freezing chamber. The second thermostatically actuated switch is adapted to open the series circuit when the temperature of the freezing compartment reaches approximately 50 F. The first thermostatically actuated switch is adapted to be operated to again initiate the freezing cycle when the temperature of the freezing compartment reaches approximately 55 F. whereupon the cycle will repeat itself automatically.

It is a feature of the present invention to provide serially connected thermostatically actuated switches to accurately control the duration of the freezing cycle in an automatic ice making machine.

Additionally, by utilizing the control device of the present invention, the volume of water required at the beginning of the freezing cycle need not be more than the volume of Water actually frozen. This is to be contradistinguished from prior art type of ice making machines wherein a volume of water in excess of the volume of water actually frozen is utilized and the excess water is drained off at the termination of the freezing cycle.

Thus, it is another feature of the present invention to provide a control device for automatic ice making machines wherein the cycles of operation are of substantially shorter duration than in ice making machines used heretofore since less water need be recirculated in the present invention.

The above and other objects and features of the present invention will become more apparent from a consideration of the following detailed description when taken in conjunction with the drawings in which:

FIG. 1 is a perspective view of an ice making machine having the improved control means of the present invention therein;

FIG. 2 is a vertical sectional view of the ice making machine shown in FIG. 1 during the harvest cycle;

FIG. 3 is a vertical sectional view of the ice making machine shown in FIG. 1 during the freezing cycle;

FIG. 4 is a front elevational view of the machine shown in FIG. 1 during the harvest cycle with the cover plate removed;

FIG. 5 is a view similar to FIG. 4 but showing the arrangement of the machine during the freezing cycle;

FIG. 6 is a fragmental detail sectional view through a cell of the freezing chamber with the parts in position during the freezing cycle;

FIG. 7 is a detailed sectional view of the freezing chamber taken along line 77 of FIG. 6;

FIG. 8 is a schematic diagram of the refrigeration and water circulation systems used in the machine shown in FIG. 1; and

FIG. 9 is a schematic circuit wiring diagram of the control device of the present invention.

The control device of the present invention is adapted to control the operation of an ice making machine similar to the type disclosed in the aforementioned patent to Bayston et al. and shown herein in FIGS. 18. Thus, as shown in FIG. 1, the automatic ice making machine 19 comprises an upper freezing portion 11 and la base portion 12. Machine is provided with side walls 13 and a top Wall 14. It is to be understood that the walls of the machine may be lined with a suitable insulating material (not shown) in the conventional manner. Base portion 12 is provided with a swinging insulated door 15 which is connected to machine 10 by suitable hinges (not shown). A handle 16 is provided to facilitate opening and closing door 15. The interior of base portion 12 comprises a bin 17 which receives and stores the ice manufactured in freezing portion 11. Bin 17 is provided with a pivoted front plate 18 which is engaged by brackets 19 on the inner surface of door 15 for tilting the front of the ice bin upward to facilitate removal of the ice cubes within bin 17.

Freezing portion 11 of the machine, as shown in FIGS. 2-5, is provided with a back wall 20, which extends between side walls 13, and a front wall 21. A partition 22 extends between rear wall 20 and front wall 21 and divides freezing portion or unit 11 into a freezing section 23 and a compressor section 24.

The freezing apparatus of automatic ice making machine 10 includes an evaporator unit denoted generally by the numeral 25. More particularly, evaporator or freezing chamber 25 comprises a top plate 26 and perpendicularly downwardly laterally and longitudinally extending partitions 27 which form a plurality of individual open-bottom, freezing cells 28. It is to be understood that the cells 28 defined by top plate 26 and partitions 27 are cubicals in which the ice cubes are produced.

A closure plate 29, which is mounted in a frame 30, is adapted to close the open bottoms of freezing cells 28, as shown in FIG. 3. Frame 30 is pivotable about a pivot pin 31 and is connected thereto by a bracket 32. Thus, closure plate 29 may be respectively raised to a cell closing position during the freezing cycle of operation, as shown in FIG. 3, or may be lowered to an ice dispensing position during the harvest cycle of operation, as shown in FIG. 2, to permit discharge of the ice cubes from cells 28. A motor 33 (shown in the schematic circuit wiring diagram of FIG. 9 only) is operable to raise and lower closure plate 29. The output shaft 34 (FIGS. 25) of motor 33 may be rotated in either the clockwise or the counter-clockwise direction to effect raising and lowering of plate 29. The links 35 are fixedly connected to the ends of shaft 34 and are rotatable therewith. A spring 36 is connected between the lower end of each link 35 and frame 30, as shown in FIGS. 25. Shaft 34 may be supported in freezing section 23 by any conventional means as by cars (not shown) depending from top wall 14 and rotatably receiving shaft 34 therethrough. Clockwise rotation of shaft 34-, as taken in FIGS. 2-5, will cause frame 30 to pivot about pin 31 to thereby raise closure plate 29 into abutment with partitions 27 to close the open bottoms of cells 28. Springs 36 will be tensioned, as shown in FIG. 5, to maintain closure plate 29 tightly against the bottoms of partitions 27. The leading face 35a of one of the links 35 is adapted to move the arm of a toggle switch 37 when link 35 is rotated to the position shown in FIG. 5. Counter-clockwise rotation of shaft 34, as taken in FIGS. 2-5 will cause links 35 to rotate counter-clockwise to lower frame 30 to again open the bottoms of cells 28 and allow the ice cubes to be released therefrom. Cubes 39 will be released from cells 28 and strike plate 29 to thereupon slide down plate 29 into chute 38 which communicates with bin 17. An extension bar 40 (FIG. 4) which extends outwardly from link 35, is adapted to communicate with toggle switch 37 4; when the link is in the down position to move the arm of toggle switch 37 as described in more detail hereinbelow. It is to be noted that link 35 is provided with a cam surface 3512 which is adapted to abut against and strike closure plate 29 to facilitate the opening of cells 28 after the ice cubes have been produced.

Machine 10 is provided with a connection 41 which is adapted to be connected to a source of water to provide the fluid necessary for the production of the ice cubes. Connection 41 is connected, through a solenoid actuated valve 42 (FIGS. 4 and 5) to a line 43 which discharges onto closure plate 29 through a header 43a. Thus, the water will flow down plate 29 and through holes 45 in closure plate 29 into a reservoir 46 which depends from frame 30. The leading edge 46a of reservoir 46 projects outwardly of plate 29 to define a marginal opening 46b therebetween. Hence, in addition to entering reservoir 46 through holes 45, the water will also enter the reservoir through opening 461). Connection 41 is also connected,

through a line 47 (FIG. 8) and a pressure controlled.

valve 48, to a tube 49 in an auxiliary water-cooled heat exchanger 50 as described more fully hereinbelow. Water flowing through tube 49 is discharged through an outlet tube 51 into the drain of the machine (not shown). As is conventional, the operation of valve 48 is dependant upon refrigerant pressure and is connect-ed to a refrigerant reservoir 52 through a pressure control line 53. Thus, valve 48 will open and supply cold water to cooler 50 when the refrigerant pressure in control line 53 reaches a pre-set limit.

As shown in FIGS. 6 and 7, top plate 26 is provided with bores 44 therethrough which communicate with cells 28 to thereby provide air vents for the cells. Reservoir or tank 46 is supplied with a predetermined volume of water prior to the actual freezing cycle. This water is recirculated through the freezing chambers, as noted below, until the ice cubes are produced. As one of the features of the present invention the volume of water introduced into the tank is substantially equal to the amount of water required to produce the ice cubes thereby eliminating the draining of excess water after the freezing cycle has been completed. Thus, since substantially less Water is recirculated through the system in the machine described, the freezing cycle may be of shorter duration than the freezing cycles of machines utilized heretofore.

Prior to the initiation of the freezing cycle, water is allowed to flow into tank 46 by the method described below when the tank is in the down position. An overflow tube 55 in reservoir 46 communicates with a drain tube 56 which, in turn, is adapted to be connected to a drain external of the machine. Thus, Water will flow into tank 46 until the level of the water in the tank reaches the top of drain tube 55 at which time the water will overflow into drain tube 55 thereby assuring that the water in the tank remains at a predetermined level. In the present invention this predetermined level of water, as noted above, corresponds to the exact volume of Water required to produce the ice cubes in cells 28. It is to be noted that the front Wall 4611 of tank 46 includes a top edge which extends substantially above tube 55 when the tank is in the down position to assure that the water will remain in tank 46 during the filling operation.

A water pump 54 is connected to tank 46 and includes an inlet which communicates with the bottom of tank 46. The outlet of pump 54 is connected to a feeder pipe 56, as shown in FIGS. 2 and 3. Feeder pipe 56 communicates with the circular water supply tubes 57 which extend longitudinally below closure plate 29. Each of the water supply tubes 57, as shown in FIGS. 6 and 7, are provided with the central transverse apertures 58 which are in alignment with the corresponding apertures 59 in plate 29. It is to be noted that a plurality of such apertures 58 and 59 are provided and are positioned so each aperture 58 and 59 will be approximately centrally located in the bottom of a cell 28 when the closure plate is in bottom-closing position. When pump 54 is operating, water will be pumped through feeder pipe 56 into tubes 57 and through apertures 58 and 59 into the cells 28. Thus, the water will spurt up through closure plate 29 and will begin to form the ice cubes on the walls of cells 28. The water which is not immediately frozen will fall through holes 45 in plate 29 back into tank 46 to be recirculated again. Thus, the water in tank 46 will be recirculated until frozen into ice cubes. The end of pipes 57 are provided with a transverse aperture 60 (FIG. 6) so the water which does not reach cells 28 will fall back into the tank 46.

The refrigeration system of ice making machine is illustrated in detail in schematic form in FIG. 8 and the compressor portion of the system is indicated generally by the numeral 61 in FIGS. 25. Compressor 62 compresses the gaseous refrigerant which fiows through a compressor outlet 63 to a condensing coil 64. A fan 65, contained within compartment 24, is positioned to blow air across the condensing coil 64 in a conventional manner. The refrigerant, which leaves condensing coil 64 as a liquid, flows through a pipe 100 and auxiliary heat exchanger 50 which consists of the double coil, as noted above, wherein water is passed through the complementary coil to remove heat from the refrigerant. A pipe 66 connects auxiliary heat exchanger 50 to an inlet on the refrigerant reservoir 52. As is conventional in machines of this type, a line 67 extends from the outlet of reservoir 52, through a heat exchanger 68 and an expansion valve 69 to a serpentine evaporator coil 70 which is mounted on the top plate 26 of the evaporator unit. The refrigerant is returned to an inlet 71 on compressor 62 via the return line 72 which extends through heat exchanger 68. Expansion valve 69 is controlled by a thermostat 73, located on the return line 72, in the conventional manner. A hot gas bypass pipe 74 extends from outlet 63 on compressor 62, through a hot gas solenoid actuated valve 75 to evaporator coil 70.

The operation of the above-described system is conventional. Thus, the liquified cooled refrigerant entering reservoir 52 will be supplied, through heat exchanger 68, to expansion valve 69. The expansion valve will supply the refrigerant to the evaporator coil 70 in the form of a gas which will cool the freezing compartment containing the cells 28 therein thereby producing the ice cubes. After the freezing cycle is terminated, solenoid actuated valve 75 will be operated to allow hot gases to enter the coil 70 to facilitate warming of the freezing chamber and release of the ice cubes therefrom. It is to be understood that after termination of the freezing cycle the closure plate will have been lowered to allow the ice cubes falling thereupon to be dispensed from the freezing portion 11 of machine 10.

Control system As noted above, automatic ice making machines used heretofore have included inaccurate control devices for determining the duration of the freezing cycle. One such device included the use of a pilot tank and pressure nozzle system wherein the pressure was dependent upon the ice cubes being formed in the freezing unit of the machine. However it was found that this was an extremely inaccurate and ineflicient device.

In accordance with the present invention, the control system, as illustrated in FIG. 9, includes leads 77 and 78 which may terminate in a conventional male plug end which are adapted to be connected to a conventional wall outlet. Thus, the source of potential is represented by generator 103. Compressor 62 and fan 65 are connected across leads 7 and 8 by the respective leads 79 and 80. Lead 77 is connected to terminal 1 of a toggle switch 76. The armature of toggle switch 76 is connected to terminal 1 and is movable between terminals 2 and 3.

A biasing spring 82 normally biases the armature of switch 76 into contact with terminal 3 thereby connecting terminals 1 and 3 together. A thermostatically controlled switch 81 is serially connected in lead 77 between source 103 and circuit elements 62 and 65. The thermostat 81a is located adjacent the top of bin 17 of ice machine 10 and, when the ice cubes reach the level of the thermostat 81a the thermostat will be actuated to open switch 81 and prevent further operation of the machine until a sufiicient amount of cubes have been removed from the bin to allow the thermostat to warm up.

A lead 83 connects terminal 3 of switch 76 to one terminal of the solenoid 42 which controls the activation of the water valve; the other terminal of solenoid 42 is connected to lead 78. Solenoid 75, which controls the flow of hot gases to evaporator coil 70, is connected between lead 83, by a lead 84, and lead 78. Water pump 54 is connected between terminal 2 of switch 76, by a lead 85, and lead 78. Toggle switch 76 is actuated when frame 30 is moved to the upper or bottom-closing position. Thus, a bracket 85 (FIGS. 4 and 5) is connected to frame 30 as by screws 86 and is positioned so when the frame 30 is moved to the upper position the top edge of bracket 85 will engage the arm of toggle switch 76 to thereby move the armature of toggle switch 76 to connect terminals 1 and 2 together. When frame 30 is lowered, biasing spring 82 will again cause terminal 1 to be connected to terminal 3.

Toggle switch 37 comprises two single-pole doublethrow switches mounted on a common base. Terminals 1, 2 and 3 comprise one switch and terminals 4, 5 and 6 comprise the other switch. Terminal 2 is adapted to be connected to either terminal 1 or terminal 3 and terminal 5 is adapted to be connected to either terminal 4 or terminal 6. When the frame 30 is in the lower or ice dispensing position toggle switch 37 will be in the position shown in FIG. 9; that is, terminals 2 and 5 will respectively be connected to terminals 1 and 6. When frame 30 is raised to the upper position switch 37 will be actuated by edge 35a of link 35 to throw the armatures of the switches comprising toggle switch 37 to the other position whereupon terminal 2 will be connected to terminal 3 and terminal 5 will be connected to terminal 4. It is to be understood that when the frame is again lowered, extension 40 will re-set toggle switch 37 to the position shown in FIG. 9. Terminal 6 is connected, through a field widing 87 of motor 33 to motor 33. The other end of motor 33 is connected to lead 78 by a lead 88. The common terminal 5 of switch 37 is connected to a terminal 3 of a thermostatically actuated switch 89 by a lead 90. Terminal 4 is unconnected. Terminal 3 of switch 37 is connected through another field winding 87a of motor 33 to the same terminal of motor 33 that field winding 87 is connected to. A lead 102 is connected between terminal 3 of toggle switch 37, through a normally open push button 91, to a lead 92 which in turn is connected to lead 84. Common terminal 2 of toggle switch 37 is connected to lead 102 between push button 91 and lead 92 by a lead 93. Terminal 1 of switch 37 is unconnected. When current flows through field winding 87, motor 33 will be actuated to raise frame 30 and a tank 4-6 so closure plate 29 seals the bottom of cells 28. When field winding 87a is energized motor 33 will be operable to lower frame 30 to allow the ice cubes to be discharged from cells 28. When both fields are energized the frame will remain in its lower position.

The thermostat bulb 89a of thermostatically controlled switch 89 is located on the evaporator unit 25 of the ice machine. Switch 89 comprises three terminals respectively marked 1, 2 and 3 and includes an armature which is connected to terminal 2 and which is movable to connect terminal 2 to either terminal 1 or to terminal 3 in response to controls from thermostat bulb 89a. Thus, in the present embodiment terminal 2 is adapted to be connected to terminal 3 when the temperature of the evaporator unit reaches approximately 55 F. On the other hand, terminal 2 is adapted to be connected to terminal 1 when the temperature of the evaporator unit 25 is lowered to approximately 30 F. Terminal 2 is connected directly to lead 77 by a lead 94. Terminal 1 of switch 89 is serially connected to one terminal of a two terminal thermostatically controlled switch 95. The operation of switch 95 is controlled by a thermostat bulb 95a which is similarly located on unit 25. The other terminal of switch 95 is connected to lead 92. Switch 95 is adapted to connect terminal 1 to terminal 2 when the temperature of the evaporator unit 25 reaches approximately F. and is further adapted to break the circuit between terminals 1 and 2 of switch 95 when the temperature of the unit 25 reaches approximately 50 F.

In describing the operation of the present control system it is to be assumed that the device has been in operation for an interval of time and that the harvest cycle has just been initiated so ice cubes 39 are being discharged and the hot gas is beginning to flow through evaporator coil 70 to heat up evaporator unit 25. It

is further to be understood that frame 30 is in its lower position so terminal 1 of toggle switch 76 is connected to terminal 3 and terminals 2 and 5 of toggle switch 37 are respectively connected to terminals 1 and 6. However, terminal 2 of switch 89 will be connected to terminal 1 and terminal 1 of switch 95 will be connected to terminal 2 of switch 95 since the freezing chamber has not heated sufliciently to cause switches 89 and 95 to be operated to their other positions. For this case solenoids 42 and 75 will be actuated to operate their respective values to respectively allow water to flow into tank 46 and hot gas to flow into evaporator coil 70. That is, the source of potential across leads 77 and 78 will be applied to solenoid 42 through lead 77, terminals 1 and 3 of switch 76, lead 83, and lead 78. Similarly, the source of potential will be applied to solenoid 75 through lead 77, terminals 1 and 3 of switch 76, lead 83, lead 84, and lead 78. It is assumed for all these cases that bin switch 81 is closed. When the temperature of evaporator unit reaches approximately 50 F. switch 95 will be actuated to break the circuit between terminals 1 and 2. Further heating of the unit will cause thermostat bulb 89a to actuate thermostatically controlled switch 89 to connect terminals 2 and 3 together thereby energizing motor 33 through the circuit comprising lead 77, lead 94, terminals 2 and 3 of switch 89, lead 90, terminals 5 and 6 of toggle switch 37, field 87, motor 33 and leads 88 and 87. This will cause frame to be raised to the upper position wherein closure plate 29 seals the bottom of cells 28. It is to be noted that the time interval required for the harvesting cycle (i.e., the time required to heat up thermostat bulb 89a sufficiently to connect terminals 3 and 2) will be greater than the time interval required to fill tank 46 with the required volume of fluid. In other words at the time switch 89 is actuated to cause the tank to be raised water will be overflowing through the overflow pipe 55 thereby insuring that the required volume of water has been received in tank 46. When frame 30 has been moved to the upper position toggle switch 76 will be actuated by bracket 85 to connect terminal 1 to terminal 2 thereby breaking the connection between terminals 1 and 3 and deenergizing solenoids 42 and 75 to respectively stop the flow of water into the system and cut-off the hot gases flowing through evaporator coil 70. Moreover, toggle switch 37 will be actuated by the leading edge a of link 35 to connect terminal 2 to terminal 3 and terminal .5 to terminal 4. However, field 89 will not be energized at this time since there is no connection between terminal 2 of switch 37 and the source of potential.

Pump 54 will be energized through the circuit comprising lead 77, terminals 1 and 2 of switch 76, lead 85, and lead 78 to thereby begin to recirculate the water in the system. As the refrigerent flows through evaporator coil 70, the temperature in. unit 25 begins to decrease and the 8 ice cubes will be formed within cells 28 in the aforementioned manner. Switch 89 will be actuated when the temperature reaches approximately 30 F. to thereby connect terminals 1 and 2 of switch 89 together. In accordance with the present embodiment, ice cubes will be completely formed by the time the temperature in unit 25 reaches approximately 10 F. Thus, when the evaporator unit does reach the aforementioned 10 F. switch will be actuated to connect terminal 1 to terminal 2. When the aforementioned operation occurs, the freezing cycle will be terminated and the harvesting cycle will be initiated because motor 33 will be energized through the circuit comprising lead 77, lead 94, terminals 1 and 2 of switch 89, lead 96, terminals 1 and 2 of switch 95, lead 92, lead 102, lead 93, terminals 2 and 3 of toggle switch 37, field 89, motor 33 ,and leads 88, and 78 to lower plate 29. Moreover, solenoids 42 and 75 will be energized through the circuit comprising energized lead 92, lead 84, and leads 83 and 78. As frame 30 is lowered the armature of switch 76 will be biased to connect terminal 1 to terminal 3 thereby directly connecting solenoids 42 and 75 across the source of potential through the circuit noted above. Moreover extension 40 will connect terminals 2 and 5 of toggle switch 37 to the respective terminals 1 and 6. However, field winding 87 will not be energized at this time since terminal 2 of switch 89 is connected to terminal 1. The cubes will then be discharged in the above described manner and the hot gas flowing through evaporator coils 70 will again heat up the chamber. When the temperature reaches approximately 50 F. switch 95 will open and when the temperature further increases to 55 F. switch 89 will be actuated to connect terminal 2 to terminal 3 thereby again initiating the freezing cycle.

The above described operation has assumed that the machine has been working for an interval of time; how ever, if the machine is first plugged in then an additional step must initially be performed before the machine can begin its automatic operation. If it is assumed that the conditions of the control system are as shown in FIG. 9 then as soon as the machine is connected across a source of potential frame 30 will tend to rise since winding 87 of motor 33 will be energized through the aforenoted circuit before any water has been introduced into the machine. To prevent this occurrence push-button 91 is operated to thereby energize winding 89 through the circuit comprising lead 92, lead 102, push-button 91, field winding 89, motor 33 and lead 88. Thus, both field windings 87 and 89 will be energized thereby preventing the motor from operating frame 30 to the upper position. That is, when both field windings are energized the weight of frame 30 and the elements connected thereto will maintain the plate in the lower position. The plate will also move to the lower position if both field windings are energized if the plate is in any interemdiate position between the lower and the upper position or even in the upper position. Thus, the operator will maintain button 91 closed until he observes water flowing out of the overflow pipe 55 thereby signifying that the required volume of water has been received in tank .6. Thereupon, pushbutton 91 may be released and the freezing cycle will be initiated and the operation of the machine will be as noted above.

Thus, a control system for an ice making machine has been provided which eliminates the pilot tank and double chambered receptacle heretofore used and the attendant inaccuracies in the freezing cycle which was associated with these devices and has substituted therefor an accurate and economical control device for maintaining a freezing cycle of fixed duration.

While a preferred embodiment of the present invention has been described, it will become obvious to those skilled in the art that minor modifications may be made therein without departing from the spirit or scope of the present invention.

What is claimed is:

An automatic ice cube making machine of the type including a freezing chamber having a plurality of open bottom individual cells in heat exchange relation with a refrigerant evaporator; a closure plate movable between a cell-closing position whereby the closure plate substantially closes the open bottom of said plurality of cells during the freezing cycle of the evaporator and an ice cube discharge position whereby the closure plate opens the bottom of the plurality of cells during the harvest cycle of the machine; motor means for moving said closure plate between cell-closure position and ice cube discharge position; tank means for holding a volume of water substantially equal to the volume of water required for producing the ice cubes, overflow means in said tank for maintaining the volume of water at said predetermined limit; supply means for controlling the supply of water to said tank; recirculation means for recirculetting the water in said tank through the plurality of cells during said freezing cycle; a source of potential; and control means responsive to a predetermined temperature in said freezing chamber for terminating the freezing cycle of said evaporator and connecting said source of potential across said motor means to energize said motor means to move said closure plate to said ice cube discharge position, wherein said control means includes a first thermostatically actuated switch connected to said source of potential and a second thermostatically controlled switch serially connected between said first thermostatically controlled switch and said motor means, whereby said first thermostatically controlled switch connects said source of potential across said second thermostatically controlled switch when the temperature in said freezing chamber reaches a first temperature above said predetermined temperature, and said second thermostatically controlled switch connects said source of potential across said motor means When the temperature in said freezing chamber reaches said predetermined temperature.

References Cited by the Examiner UNITED STATES PATENTS 2,687,019 8/1954 Swenson 62l35 X 3,009,336 11/1961 Bayson et al. 62347 X 3,045,439 7/ 1962 Alt 62-348 X 3,045,440 7/ 196-2 McGraty et al 62-347 X ROBERT A. OLEARY, Primary Examiner. W. E. WAYNER, Assistant Examiner.

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