United States Patent Kimpelet al.

[451 Mar. 21, 1972 [54] ICEMAKER PROTECTION SYSTEM [72] Inventors: Frank A. Kimpel; William F. Markley,

[21] Appl.No.: 887,260

[52] U.S. Cl ..62/136, 62/354 [51] Int. Cl. ..F25c 7/00 [58] Field of Search ..62/136, 7, 342, 343, 4, 354, 62/136-138, 344

[56] References Cited UNITED STATES PATENTS 3,013,398 12/1961 Thomas ..62/136 3,365,901 H1968 Guard 3,553,975 1/1971 Sakamoto ..62/l56 Compressor 3,147,601 9/1964 Tacchella ..62/l36 3,511,059 5/1970 Hoenisch ..62/l38 Primary ExaminerMeyer Perlin Assistant Examiner-Ronald C. Capossela Attorney-Donald W. Banner, William S. McCurry and John W. Butcher 57 ABSTRACT An icemaker protection system for an auger type icemaking machine is disclosed, which system protects against damage to the icemaking auger or to the auger motor that may be occasioned by an excessive accumulation of ice within the auger unit. Control is effected by means of a relay actuated in response to the slowing down of the auger drive motor, which occurs upon excessive ice accumulation, and a thermostatic switch which subsequently keeps the system in the deenergized condition until the excessive ice accumulation has been dissipated.

6 Claims, 3 Drawing Figures PATENTEDMARZ] 1972 3,650,121

2 I4 24 Worer Compressor 42 S pp y 27 38 3O\32 "E E 36 34s 39\ v 7 34 I8 44 'U i 27 32 5 Freezing Evopororor 22 2O Chamber 26 EEIZ'I.

no. 2 CF 5 52 Compressor \R k MoTor 55 open- 76 SS closed- Run W|nd|ng only Inventors R. F? M.

FroncisA.Kimpe|,Sr. William FMorkley SrorT 8r Run Torque Ahorney Winding ICEMAKER PROTECTION SYSTEM FIELD OF THE INVENTION The present invention relates to icemaking machines and particularly to a protection system for an icemaking machine of the auger or scraper type.

BACKGROUND OF THE INVENTION In an icemaking machine destructive forces can be generated if the drive motor is caused to stall or the auger scraper device is subjected to excessive pressure or stresses caused by abnormal freezing of ice. The present invention provides a protection system that prevents this occurrence, while, at the same time, allowing normal operation to continue in an uninterrupted manner.

In prior systems for handling, making or dispensing ice, such as that taught in Reynolds U.S. Pat. No. 3,196,628, Mihalek U.S. Pat. No. 3,136,452 or Chaplik et al., U.S. Pat. No. 2,962,877; either no special provision is made for dealing with the problem of excessive ice buildup or binding in the auger or just one ice buildup problem is dealt with. In one case a provision is made for the running of the auger for some period of time immediately after shutdown so as to remove ice and water from the auger and to thereby prevent solid freezing of ice which might otherwise occur immediately after shutdown. However, such a provision does not allow for unusual buildup or binding during operation of the auger and provides no means whereby the ice buildup may be required to melt away.

If one relies on the relatively slow acting fuses or circuit breakers on auger motors, excessive forces may be generated in the auger mechanism and that mechanism damaged before these devices detect the problem and deenergize the auger motor. Of course, it is possible to construct augers of excessively high strength to meet the infrequent high stress caused by such ice-jam or freezeup situations but this normally requires use of higher cost elements and, often, elements of greater size and weight then would be otherwise required.

The present invention meets these problems by providing a quick acting ice-jam" and freeze-up protection system that reacts to sensed increases in auger forces to prevent damage to it and its motor. The present invention also provides for automatically dissipating the problem and for automatically restoring the icemaker to normal operation after the excess ice situation has been overcome.

SUMMARY OF THE INVENTION In accordance with the present invention an improved protection system for a scraper type of icemaker as, for example, an auger icemaker, includes means for sensing the speed of the scraper and for deenergizing the scraper and the chilling or refrigeration unit in response to an increase in scraper force. Said increase in force is indicated by a decrease in the speed of the scraper drive motor, to a predetermined level below the normal operating speed.

Also provided are means for, after a delay period, re-energizing the scraper drive and the chiller unit to restore normal operation in response to a temperature sensor indicating that the freezing surface is above the freezing point, thereby insuring that any excessive ice buildup that has slowed the scraper has dissipated.

BRIEF DESCRIPTION OF DRAWINGS The features of the present invention which are believed to be novel are set forth with particularity in the appended claims. The invention, together with further advantages thereof, may best be understood by reference to the following description taken in connection with the accompanying drawing, in the several figures of which like reference numerals identify like elements, and in which:

FIG. 1 is a schematic diagram of an icemaking machine, partially in sectional view incorporating the principals of the present invention;

FIG. 2 is a circuit diagram of the icemaking machine of FIG. 1; and

FIG. 3 is a graphical presentation of typical torque versus angular speed characteristics of a motor used in the embodiment of FIGS. 1 and 2.

DETAILED DESCRIPTION Referring to FIG. 1 there is depicted in schematic form an icemaker, generally designated 10, which is constructed in accordance with the principles of the present invention.

Although the invention may be employed with any chilling equipment, it is most likely to be commonly used with conventional vapor-compression equipment and for definiteness of disclosure will be so described. The icemaker 10 thus includes a refrigeration system which employs a conventional vaporcompression refrigeration cycle.

In such vapor-compression cycles equipment it is conventional to employ a closed loop processing of a refrigerant such as Freon. The refrigerant is continuously processed in a closed loop wherein it is compressed at one stage, liquefied by giving off heat at another stage, thereafter collected, and then evaporated to take on heat at another stage, and finally recompressed again.

Thus, a compressor unit 12 is provided and this unit is driven by an electric motor 14. The compressor electric motor 14 serves as the prime mover for the refrigeration system. From the compressor 12 the refrigerant is discharged, under pressure, through a line 16 to a condenser 18 where it liquefies. From there it flows to an expansion device, such as the valve 20, and then to an evaporator 22 which, in this case, is the outer jacket about a freezing chamber 26. The chamber 26 is preferably of a generally cylindrical shape and cooperates with a scraper unit 30. The liquid refrigerant, under low pressure in the evaporator, boils and extracts heat through the conductive walls 27 of the freezing chamber 26. The low pressure gas is returned from the evaporator 22 via a line 24 to the input of the compressor 12.

Although here described as conventional vapor-compression refrigeration cycle equipment, the cooling of the icemaker 10 may be provided in any other manner without departing from at least the broader principles of the present invention. The auger scraper unit 30 includes an auger scraper 32 which is rotated by an electric motor 34. The motor 34 is coupled through a speed reducer 36 to the auger 32. Water is supplied to the freezing chamber 26 from an inlet pipe 38 from a suitable supply 40 through a control valve 42.

Although here described in conjunction with a horizontal extending auger type ice scraper unit 30, other types of ice scraping units may be employed such as the vertical auger icemaker taught in the U.S. Pat. No. 3,371,505 to F. M. Raver and William F. Markley, one of the present inventors, entitled Auger Icemaker which was issued on Mar. 5, 1968 and is assigned to the same assignee as is the present invention. That patent employs a vertical auger to scrape ice off vertical side walls. The present invention may be employed with either type of auger icemaker and with other types of icemaking machinery.

Water is inserted from the source 40 to the valve 42 into the freezing chamber 26 and advanced along the auger and is chilled by the extraction of heat through the inside surfaces of the cylinder shaped walls 27 of the freezing chamber 26. This ice is scraped off of the walls 27 by the auger and advanced toward one extreme end 39 of the auger 32 from which small flakes and chunks of ice fall, by gravity, into an ice bin or chamber 43.

In accordance with one feature of the present invention an ice bin level detection device comprising a thermo-switch, indicated by numeral 42, is provided within the bin 43, and a temperature sensing unit 44 is provided as part of the evaporator 22 for sensing the temperature of the freezing chamber and especially the freezing surface temperature. The temperature sensing unit 44 is preferably also a thermo-switch so constructed as to open at temperatures approaching freezing or 32 F. Also, the electric motor 34 for operating the scraper or auger 32 is provided with a speed sensing or centrifugal switch 348. Each of these units are in themselves well-known and need not be here described in detail. These elements are combined into a protection system in a manner in accordance with the present invention, which manner of combining is better shown in FIG. 2.

Referring to FIG. 2 the electrical circuit for the protection system is there depicted. The power input lines 50, may be I volts 60 cycle AC lines that are commonly available in the United States and Canada or may be another electric power source as may be available including a DC power source. In accordance with the present invention between the individual electric power lines 50 is connected the series-connected compressor motor 14 and a relay switch 52. The relay switch 52 is controlled by a relay coil 54 which is associated with the scraper motor unit 34. For definiteness, a circuit for a typical AC scraper motor unit 34 is depicted in FIG. 2, it being understood that other electrical motors may be employed without departing from at least the broader aspects of the present invention.

The motor 34 comprises a running coil winding 34A and a start-up coil winding 348. The coil 34B is connected in series with a centrifugal or speed switch 348 as is conventional with this particular type of motor. The series connection of the start-up coil 34B and the speed switch 348 is connected across the main running'coil winding 34A.

One of the power input lines 50, designated 50A, is connected to one side of the motor 34. The other power input line, designated 50C, is connected through manually operative off-on switch 55, the bin thermo-switch 42 and the freezing chamber thermo-switch 44, all connected in series, to the other input of the motor 34. A second relay switch 56 also controlled by relay coil 54, is provided connected across the thermo-switch 44. The control relay coil 54 which controls both the switch 56 and the switch 52 is connected across the speed switch 345 and may be connected thereto through a series dropping resistor 58. The resistor 58 is shown in dashed lines to indicate that it is optional. Depending upon the type of a relay coil 54 employed this resistor 58 may be eliminated.

Before taking up the operation of the icemaker protection system and circuit of the present invention, the operating characteristics of the typical motor 34 will be considered. These characteristics are, in part, depicted in FIG. 3 which is a graph wherein the torque of the motor and its speed are compared under two sets of conditions. The first curve A, represents the condition when both the start-up and running windings 34A and 34B are in the circuit, as when the motor is being started up. Curve A represents the motors normal operation from zero speed to the point labeled 70. At the point 70, in the start-up operation of the motor, the speed switch 348, is opened. This causes the start-up winding 348 to be essentially deenergized and the operation of the motor reverts to curve B, which represents the relationship between torque and speed for operation with only the running winding 34A in the circuit. Thus, the normal start-up would operate along curve A until its speed reaches point 70 at which point it would transfer in torque to the point 72. For normal operation the motor will run on curve 8" between a maximum speed anda speed less than maximum but still somewhat above the speed corresponding to point 74, at which point the speed switch 348 recloses. Should the motor slow down to a speed below point 74, the start-up coil 348 would be added and the operation of the motor transferred to curve A (point 76) with a corresponding increase in torque. For more details and discussion of this particular type of motor reference may be had to the article Single Phase Production Motors appearing at pages 77-79 of Volume 7 of the McGraw-Hill Encyclopedia of Science and Technology and the references there cited. It should be noted that the split phase motor 34 may also be a capacitance motor with very little change in the above circuitry or operation. In the case of other types of electrical motors not normally equipped with a centrifugal speed switch, some similar means for sampling the motor torque output or speed may be added. To fulfill the requirements of this invention, in its broader aspects, it is only necessary that the relay coil be operated in response to motor or auger torque or speed.

OPERATION In overall operation, the protection system functions to interrupt operation of and to prevent re-starting of the motor when the auger is frozen or subject to excessive loading, as by excessive ice, and prevents over-loading or mechanical strain on the scraper 32, the speed reducer 36, the couplings therebetween and on the motor 34.

As explained before, the overall operation of the icemaker 10, during normal operation, is to produce, from the water from source 40, ice in the bin 43. It does this by progressively moving the water from the inlet about the chilled surface 27 to form ice thereon, and scraping that ice by the auger or scraper 32, which also moves the scraped ice to the end 39 from which it falls into the bin 40. When the level of the bin 40 reaches a desired maximum, the'ice reaches the position of the thermoswitch 42 causing that switch 42 to open. When ice is removed from or melted in the bin 40 so that it falls below the level of the switch 41, that switch closes to re-energize the icemaker to produce additional ice. During normal icemaking operation, the freezing surface temperature sensor, thermo-switch 44, adjacent the freezing chamber 26 is maintained open.

In the start-up of the system 10 either initially by the closure of the on-off switch or by the closure of the switch 42 indicating a lowering of bin level, the electric power from the 1 electric power lines 50 is applied (with the switches 42, 44 and 55 closed) across the electric motor 34. As, initially, the centrifugal or speed switch 348 is closed, the electric power is placed across the coil windings 34A and 343. The relay coil 54 is essentially short circuited by the speed switch 348 and therefore the relay switches 52 and 56 remain open at start-up of the icemaker 10. The switch 52, being open, prevents electric power from being communicated to the compressor motor 14.

As the speed of the auger motor 34 increases, following the curve A" of FIG. 3, it eventually reaches the point whereat the speed switch 348 is caused to open. When this occurs, the relay coil 54 is no longer shorted-out and electric current flows therethrough. Since the impedance of the relay coil 54 plus resistor 58 is large, the effect of the starting coil 34B is relatively minor and we can consider the motor 34 operating along curve B of FIG. 3.

The energizing of the coil 54 almost immediately closes the relay switches 52 and 56. Closure of relay switch 52 allows power to flow from lines 50A and 50C through the compressor motor 14 to operate the compressor and to start the refrigeration cycle. Closure of the relay switch 56 by-passes the thermo-switch 44, which is closed at time of system startup dueto there being no ice in the freezing chambenand allows the system to continue to operate when that switch 44 opens as the temperature within the freezing chamber 26 reaches freezing. Thus, the normal operating state of the system 10, with the switches 52, 55, 42, 56 closed, and switches 44 and 348 open, is reached.

When the ice in the ice bin reaches the level of the thermoswitch 42 that switch is caused to open. The opening of the switch'42 breaks the circuit through the auger motor coil windings 34A'and 34B and also removes the current from the relay coil 54. This causes relay switches 52 and 56 to open disconnecting the compressor motor 14 and ending the bypass current path around the thermo-switch 44. The ice auger32 stops. There may be water left in the'chamber 26 after shutdown of the auger and the low temperature of the evaporator 22 may'cause this 'water to freeze about the auger 32. In this state, were the motor 34 to become energized, as might result from the removal of ice in the ice bin and closure of the switch 42, the motor 34 might draw an excessive amount of current or damage the auger 32 or the speed reducer 36. But, the provision of the thermo-switch 44 prevents energization of the motor 34 until the freezing chamber temperature, as sensed by it, rises to a high enough level to cause any water therein to be in a liquid or slush state. Thus, despite any reactivation or closing of switch 42 as by the removal of ice from the bin, the auger motor 34 may not be started again until thermo-switch 44 is closed. That is, until the temperature of the freezing chamber 26 has risen above freezing. This prevents an exceptionally high start-up load from being placed upon the motor and, more importantly, prevents damage to the auger 32 and the speed reducer 36.

Assume the switch 42 has been closed (by the removal or melting of ice from the ice bin) and a period of time elapsed to allow the temperature in the freezing chamber 26 to rise to a point above freezing. This would close the thermo-switch 44 and would reactivate the motor 34. Once the auger motor 34 has reached sufficient speed (point 70 FIG. 3) the speed switch 348 opens. This causes the coil 54 to close switch 52 and the compressor motor 14 is activated. As the switch 56 is also now closed the activation of the refrigeration equipment does not cause shutdown of the icemaker when the chilling effected by that activation causes the therrno-switch 44 to open. Normal production of ice may thus start and continue.

Another abnormal overload condition may occasionally cause an ice buildup or an ice jam. This ice jam places an excessive load on the motor 34 and causes it to drop off in speed. As charted in FIG. 3 the motor speed would drop from its normal range to the point 74. At that point, the switch 348 would re-close. This shorts out the relay coil 54, thereby causing the relay switches 56 and 52 to open and, as the temperature in the freezing chamber 26 is below freezing and the switch 44 is open, remove power from both motors 34 and 14.

Again the motor 34 cannot be turned on until the temperature within the freezing chamber 26, as sensed by the thermoswitch 44, rises above freezing. When this occurs the ice jam which bound the auger 32 causing the initial problem has melted and the overload situation has, therefore, been dissipated. In this case the motor 34, and the entire system 10 may again resume normal functioning.

As should now be clear, a new and improved protection system for an icemaking machine has been described which provides positive protection against overloading of the electrical or mechanical portions of the icemaker which might result from excessive frozen ice either extraordinarily accumulating during normal operation or as caused by freezing of water present after shutting down of the icemaker. The protection system described is especially useful in auger motors of the split phase or capacitor type wherein parts, such as the centrifugal speed switch, are employed in the dual use of aiding in its conventional use and also in the unusual use of measuring excessive overloads.

The employment of the speed switch on the scraper motor to operate the higher power handling compressor relay switch, allows the operating switches such as the bin switch and the off-on switch to be placed in the lower current circuit, thereby decreasing the necessary current handling capacity of these elements and allowing the use of less expensive components.

The above described protection system allows for less massive and less costly scraper components and other parts to be employed as it materially decreases the peak stress placed upon such parts.

While particular embodiments of the invention have been shown and described, it will be obvious to those skilled in the art that changes and modifications may be made without departing from the invention in its broader aspects, and, therefore, the aim in the appended claims is to cover all such changes and modifications as fall within the true spirit and scope of the invention.

What is claimed is:

l. The improvement in a protection system fora scrapertype icemaker of the type having a freezing surface which is chilled by a cooling unit and a scraper which is driven across that surface at a speed within a normal range during icemaking to scrape office that is formed thereon, comprising:

means coupled to the scraper for sensing the force exerted thereagainst;

a temperature sensor coupled to the icemaker for sensing the temperature of the freezing surface;

means coupled to the force sensor for deenergizing the scraper in response to an increase in required scraper force beyond a predetermined level, after it has reached a predetermined normal operation speed;

means coupled to said temperature sensor for re-energizing the scraper after such a deenergization of the scraper when the sensed temperature exceeds a certain level that is above the freezing temperature of ice,

whereby an excessive ice buildup against the scraper causes said scraper to be deenergized before damage may occur to it, or to its drive, and the scraper is subsequently restored to normal operation.

2. The improvement in a protection system for a scrapertype icemaker of the type having a freezing surface which is chilled by a cooling unit and a scraper which is driven across that surface at a speed, within a normal range during icemaking, to scrape off ice that is formed thereon, comprising:

means coupled to the scraper for sensing the speed thereof;

a temperature sensor coupled to the icemaker for sensing the temperature of the freezing surface;

means coupled to the speed sensor for deenergizing the scraper and the cooling unit in response to a drop in scraper speed below a certain level below its normal range after having reached a predetermined speed;

means coupled to said temperature sensor for re-energizing the scraper and cooling unit after such a deenergization of the scraper and cooling unit when the sensed temperature exceeds a certain level that is above the freezing temperature of ice,

whereby an excessive ice buildup against the scraper causes said scraper to be deenergized before damage may occur to it, or to its drive, and the icemaker is subsequently restored to normal operation.

3. An icemaker protection system for protecting an icemaker of the type having a scraper which moves across an ice forming surface, and has a scraper motor for driving the scraper and a separately powered refrigeration system for chilling the ice forming surface, comprising:

means for sensing the speed of the scraper and temporarily deenergizing for a period the scraper motor and the refrigeration system in response to a drop in speed of the scraper, below a predetermined value that is below the normal operating speeds of the scraper, after it has reached a certain level; and

means for sensing the temperature of the freezing surface are provided which prevent starting-up of the ice-maker unless the freezing surface is at or above a predetermined temperature, which temperature is above freezing. 4. The icemaker protection system as claimed in claim 3, wherein:

said speed sensing and temporary deenergizing means include:

a centrifugal switch on said scraper motor;

a relay unit having a control coupled to said centrifugal switch and two controlled switching means, one coupled with the separately powered refrigeration system for the activation and deactivation thereof in response to the opening and closing of said centrifugal switch, the other one of said two controlled switching means being coupled to said temperature sensing means for overriding and not overriding said temperature sensing means in response to the opening and closing of said centrifugal switch.

5. The icemaker protection system as claimed in claim 4 wherein:

said temperature sensing means is a thermo-switch connected in series with said scraper motor;

said relay control is a relay coil'connected across said centrifugal switch;

said two relay switching means are relay switches and connected respectively in series with a compressor motor of the refrigeration system and across said thermo-switch; and

the scraper motor is of the type having a starting winding and a running winding and said centrifugal switch serves to both substantially remove the starting winding from electrical circuit at operating speeds and to control said relay unit.

6. An icemaker comprising:

a refrigeration system (14,16,18,20,22,24) including a compressor (12);

a compressor electric motor (14) mechanically coupled to said compressor for driving it and said refrigeration system; I

an auger ice scraper unit (30) including a freezing chamber (26) cooled by said refrigeration system, having a cylindrical freezing surface and an auger (32) mounted therein for scraping the surface to remove ice therefrom, said auger unit having an output from which ice is removed and an input through which water is controllably received;

a bin (43) for receiving the ice from said auger unit;

a two winding auger electric motor (34) having a centrifugal switch (348) in series with one winding (34B) thereof to interrupt the energization of that winding when said auger motor reaches a certain speed and for closing again when it falls below another speed;

a bin switch unit (42) connected in series with said auger motor and positioned in said bin to open in response to the ice therein reaching a predetermined level and to close for ice levels therebelow;

a thermo-switch (44) mounted in said auger unit for sensing the temperature of said freezing surface and for closing when the temperature is above a preselected temperature, which is above the freezing point, which themeswitch is connected in series circuit with said auger motor and said bin switch;

a control on-off switch (55) in series circuit connected with said auger motor, said bin switch and said thermo-switch; and

a relay unit (52,54,56) including a control coil and two controlled normally open switches, said control coil being connected in parallel across said speed switch to be energized by the opening of said speed switch, one of said two controlled switches being connected in series with said compressor motor to control its energization, and the other of said two controlled switches being connected across said thermo-switch.