Operation method for automatic ice maker

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an operation method for an automatic ice maker.

2. Description of the Related Art

An automatic ice maker that automatically makes a lot of ice cubes has an ice-making unit provided with an evaporator which sticks out of a refrigeration apparatus having a compressor, a condenser and the like. The automatic ice maker produces ice cubes by supplying ice-making water to the ice-making unit forcibly cooled by a refrigerant circulating in the evaporator, and separates and collects the produced ice cubes from the ice-making unit. The automatic ice maker has an ice-making water tank provided below the ice-making unit to store a needed amount of ice-making water. The ice-making water is supplied to the ice making surface of the ice-making unit by pumping the ice-making water in the ice-making water tank by a circulation pump at the time of performing an ice-making operation. The ice-making water which has not been frozen in the ice-making unit is supplied to the ice-making unit again after being collected in the ice-making water tank.

When the ice-making operation continues and a predetermined time elapses, the automatic ice maker determines that ice making is completed, and shifts the operation to a deicing operation from the ice-making operation. In the deicing operation, a hot gas (high temperature, high pressure vaporized refrigerant) pumped out from the compressor is supplied to the evaporator by switching a hot gas valve in the refrigeration apparatus. Accordingly, tap water is supplied to the bottom sides of the ice-making plates as deicing water to cause liquefaction at the frozen surfaces between the ice cubes and the ice-making unit, thereby removing the ice cubes from the ice-making unit (see, for example, Japanese Patent Laid-Open Publication No. H5-45031).

There is a flow-down type ice maker as an automatic ice maker (see, for example, Japanese Patent Laid-Open Publication No. H10-170113). This flow-down type ice maker likewise causes liquefaction at the frozen surfaces between ice cubes and ice-making plates to remove the ice cubes therefrom by supplying a hot gas from the compressor and supplying water of normal temperature to the bottom sides of the ice-making plates.

A deicing detecting thermometer disposed at the outlet side of the evaporator detects a rise in the temperature of the hot gas circulating in the evaporator when ice cubes are removed from the ice-making plates in the deicing operation. When the deicing detecting thermometer detects a deicing completion temperature, the flow-down type ice maker terminates the deicing operation by stopping supplying the hot gas and the deicing water.

FIG. 13 is a timing chart illustrating ice-making and deicing operation cycles of a conventional flow-down type ice maker. In ice-making operation mode, a refrigerant is supplied to the evaporator (ON) and ice-making water is supplied to the ice making surfaces of the ice-making plates (ON). When ice making is completed, supply of the refrigerant and the ice-making water is stopped (OFF) to terminate the ice-making operation, and a hot gas and deicing water are supplied (ON) to start a deicing operation. Further, when the deicing detecting thermometer detects completion of deicing and the deicing operation is terminated and is shifted to the ice-making operation again, supply of the hot gas and the deicing water is stopped (OFF) and supply of the refrigerant and the ice-making water is started again. That is, as indicated by the broken-line part in FIG. 13, the flow-down type ice maker stops the hot gas and the deicing water and supplies the refrigerant and the ice-making water at the same time, when the operation is shifted to the ice-making operation from the deicing operation.

Such an automatic ice maker may shift the operation to the ice-making operation without removing all ice cubes in the deicing operation. In this case, new ice cubes are produced on ice cubes remaining at the ice-making unit, undesirably forming deformed ice cubes called “double ice cubes”. Further, the ice-making unit may be frozen by supercooling. As a solution to this problem, the set time of a timer (deicing completion detecting unit) which determines the completion of deicing of ice cubes from the ice-making unit is set longer so that the deicing operation becomes long enough for ice cubes to be completely removed. It is however pointed out that in this case, the deicing time becomes longer, thus lowering the ice making efficiency.

While the deicing operation is shifted to the ice-making operation when the deicing detecting thermometer detects the deicing completion temperature in the conventional flow-down type ice maker, the temperature to be detected is determined empirically. According to the conventional flow-down type ice maker, therefore, there may be a case where ice remains on the ice making surfaces of the ice-making plates when the deicing detecting thermometer detects the deicing completion temperature, so that ice cubes are not removed from the ice-making plates completely.

According to the conventional flow-down type ice maker, as mentioned above, the ice-making water and the refrigerant are supplied at the same time as the supply of the hot gas and the deicing water is stopped. When the deicing operation is terminated and is shifted to the ice-making operation with some ice cubes remaining on the ice-making plates, ice cubes are produced with the remaining ice cubes as cores (formation of double ice).

If the deicing completion temperature is set high, it is possible to achieve complete deicing. In this case, however, it is pointed out that the time needed for the deicing operation becomes longer, lowering the ice making performance per day becomes and thus increasing the amount of deicing water consumed.

SUMMARY OF THE INVENTION

Accordingly, it is an object of the invention to overcome the inherent problem of the conventional operation method for an automatic ice maker, and provide an operation method for an automatic ice maker capable of surely removing ice cubes from an ice-making unit to prevent double ice, and shortening the deicing time to improve the ice making efficiency.

To achieve the object, an operation method for an automatic ice maker according to the first aspect of the present invention comprises the steps of:

in an ice-making operation, cooling an ice-making unit by supplying a refrigerant to an evaporator of the ice-making unit and generating ice cubes by supplying ice-making water to the ice-making unit via a circulation pump;

in a deicing operation, supplying a hot gas to the evaporator and supplying deicing water to the ice-making unit from a deicing water supply unit to remove the ice cubes from the ice-making unit; and

driving the circulation pump to start supplying the ice-making water to the ice-making unit when a first set time elapses after a temperature detecting unit has detected a temperature of the evaporator having reached a predetermined set temperature.

To achieve the object, an operation method for an automatic ice maker according to the second aspect of the present invention comprises the steps of:

at a time of performing an ice-making operation, supplying ice-making water to top sides of ice-making plates by an ice-making water supply unit and supplying a refrigerant to an evaporator disposed in a zigzagged form between bottom sides of the ice-making plates;

when an operation shifts to a deicing operation upon detection of generation of ice cubes on the top sides of the ice-making plates, stopping supplying the ice-making water to the top sides of the ice-making plates, and supplying deicing water to the bottom sides of the ice-making plates after stopping supplying the refrigerant to the evaporator to thereby promote melt separation of the ice cubes from the ice-making plates; and

causing a controller to control the ice-making water supply unit in such a way as to supply the ice-making water to the top sides of the ice-making plates before terminating the deicing operation so that ice cubes remaining on the top sides of the ice-making plates are removed by the ice-making water.

According to the operation method for an automatic ice maker according to the first aspect of invention, the circulation pump is driven to start supplying the ice-making water to the ice-making unit in the deicing operation when the first set time elapses after the temperature detecting unit has detected the temperature of the evaporator having reached the predetermined set temperature. Because this can shorten the deicing time, it is possible to decrease the amount of deicing water needed can be reduced and increase the ice making efficiency.

According to the operation method, supply of the deicing water from the deicing water supply unit is stopped by driving the circulation pump, making it possible to make the amount of deicing water smaller.

According to the operation method, supply of the deicing water from the deicing water supply unit is stopped when a second set time set shorter than the first set time elapses after a temperature detecting unit has detected a temperature of the evaporator having reached the predetermined set temperature, making it possible to further reduce the amount of deicing water.

According to the operation method of the second aspect of invention, ice-making water is supplied to the top sides of the ice-making plates before the deicing operation is terminated, so that ice cubes remaining on the top sides are surely separated by the ice-making water, thus preventing double ice making. This makes it possible to produce high-quality ice cubes of uniform shape and shorten the deicing time.

In the second aspect of the invention, the controller controls the ice-making water supply unit to start supplying the ice-making water when an ice-making-water supply start detecting unit detects a preset ice-making-water supply start condition before a deicing completion detecting unit which detects completion of the deicing operation detects completion of deicing. Accordingly, liquefaction of ice cubes by ice-making water is suppressed as compared with a case of continuous supply of ice-making water, so that supply of the ice-making water can be carried out at a relatively early stage of the deicing operation. This operation method makes the deicing efficiency higher than that of the case of continuously supplying ice-making water in deicing operation mode, so that the deicing time can be made shorter, thus resulting in an improved ice making performance.

In the second aspect of the invention or the previously described modification thereof, in a case of supplying the ice-making water to the top sides of the ice-making plates before terminating the deicing operation, the controller controls the ice-making water supply unit to intermittently supply the ice-making water. This operation method can reduce the amount of ice-making water to be sprayed into the ice tank by intermittently supplying the ice-making water in deicing operation mode.

In any one of the second aspect of the invention and the previously described two modifications thereof, when supply of the ice-making water to the top sides of the ice-making plates is started before terminating the deicing operation, the controller controls the deicing water supply unit which supplies the deicing water ice-making water supply unit, thereby stopping supplying the deicing water to the bottom sides of the ice-making plates. This operation method can make the amount of ice-deicing water to be used in the deicing operation smaller than that conventionally needed by stopping supplying the deicing water to the bottom sides of the ice-making plates when supply of the ice-making water to the top sides of the ice-making plates is started before the deicing operation ends.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram showing an automatic ice maker according to a preferable first embodiment of the present invention;

FIG. 2 is a control block diagram of the automatic ice maker of the first embodiment;

FIG. 3 is a flowchart illustrating the first half of the procedures of the deicing operation of the automatic ice maker of the first embodiment;

FIG. 4 is a flowchart illustrating the second half of the procedures of the deicing operation of the automatic ice maker of the first embodiment;

FIG. 5 is a flowchart illustrating the second half of the procedures of the deicing operation of the automatic ice maker according to a second embodiment;

FIG. 6 is a control block diagram of an automatic ice maker according to a third embodiment;

FIG. 7 is a flowchart illustrating the second half of the procedures of the deicing operation of the automatic ice maker of the third embodiment;

FIG. 8 is a schematic structural diagram showing a flow-down type ice maker according to a fourth embodiment;

FIG. 9 is a flowchart illustrating an operation method for the flow-down type ice maker of the fourth embodiment;

FIG. 10 is a timing chart illustrating the operation cycle of the flow-down type ice maker of the fourth embodiment;

FIG. 11 is a flowchart illustrating an operation method for a flow-down type ice maker according to a fifth embodiment;

FIG. 12 is a timing chart illustrating the operation cycle of the flow-down type ice maker of the fifth embodiment; and

FIG. 13 is a timing chart illustrating the operation cycle of the conventional flow-down type ice maker.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Operation methods for an automatic ice maker according to preferred embodiments of the present invention will be described below referring to the accompanying drawings.

First Embodiment

FIG. 1 shows the schematic configuration of a flow-down type automatic ice maker as an automatic ice maker according to a first embodiment. The automatic ice maker has an evaporator 14 closely fixed to the backside of an ice-making unit 10 disposed approximately vertically in an ice-making room. The evaporator 14 is a tubular member sticking out from a refrigeration apparatus 30 to be described later and extending in a zigzagged form in the horizontal direction of the ice-making unit 10. The evaporator 14 forcibly cools down the ice-making unit 10 with a refrigerant supplied to the evaporator 14 in ice-making operation mode.

An ice-making water tank 20 which retains a predetermined amount of ice-making water is provided under the ice-making unit 10. In performing an ice-making operation, ice-making water is supplied to the ice making surface of the ice-making unit 10 via a circulation pump PM from the ice-making water tank 20 in the automatic ice maker. A guide plate 18 is disposed inclined directly below the ice-making unit 10. The guide plate 18 guides ice cubes M, which are separated from the ice-making unit 10 in a deicing operation, to a stocker 16 located below. The guide plate 18 has multiple through holes (not shown) bored therein. In the ice-making operation, the ice-making water supplied to the ice making surface of the ice-making unit 10 is collected into the ice-making water tank 20 through the through holes of the guide plate 18.

An ice-making sprinkler 24 is disposed above the ice-making unit 10. The ice-making sprinkler 24 is connected to an ice-making water supply pipe 22 extending out from the ice-making water tank 20 via the circulation pump PM. The ice-making sprinkler 24 has multiple spray holes (not shown) formed therein. In ice-making operation mode, the ice-making sprinkler 24 sprays ice-making water, pumped out from the ice-making water tank 20, to the ice making surface of the ice-making unit 10 cooled to the freezing temperature through the spray holes. As a result, ice cubes M are produced on the ice making surface of the ice-making unit 10.

A deicing water sprinkler (deicing water supply unit) 28 having unillustrated perforations is disposed above the ice-making unit 10. Tap water is supplied to the deicing water sprinkler 28 via a water supply pipe 26 connected to an external water source. A water supply valve (deicing water supply unit) WV is disposed in the water supply pipe 26 to be able to close the path of the water supply pipe 26 in an openable/closable manner. With the water supply valve WV opened in the deicing operation, deicing water is supplied to the deicing water sprinkler 28. At this time, as the deicing water is sprayed onto the bottom side of the ice-making unit 10 from the above-mentioned perforations, the temperature of the ice-making unit 10 cooled in the ice-making operation is increased by the deicing water. The deicing water is collected into the ice-making water tank 20 to be used as ice-making water in a next ice-making operation. An excess amount of the deicing water flown down to the ice-making water tank 20 that exceeds the pondage is discharged from an overflow pipe 21.

The evaporator 14 is provided with a temperature detecting unit TH which detects that the temperature of the evaporator 14 has reached a predetermined set temperature T1 since the initiation of the deicing operation. After a first set time which is before completion of the deicing operation elapses, the circulation pump PM is driven. As a result, the ice-making water is supplied to the ice-making unit 10 from the ice-making sprinkler 24, further promoting separation of ice cubes M.

The refrigeration apparatus 30 basically includes a compressor CM, a condenser CD, an expansion unit EV and the evaporator 14 provided at the bottom side of the ice-making unit 10 (see FIG. 1). The compressor CM, the condenser CD and the expansion unit EV are disposed in a mechanical chamber (not shown). The individual components of the refrigeration apparatus 30 are connected together by a refrigerant pipe 34, and the refrigerant circulates in the order of the compressor CM, the condenser CD and the expansion unit EV. That is, the vaporized refrigerant compressed by the compressor CM is condensed in the condenser CD to be liquefied. Thereafter, the liquefied refrigerant is depressurized by the expansion unit EV and flows into the evaporator 14. The liquefied refrigerant is expanded and vaporized by the evaporator 14, and exchanges heat with the ice-making unit 10 to forcibly cool the ice-making unit 10 down to the degree of frost. The vaporized refrigerant that has exchanged heat with the evaporator 14 is fed back to the compressor CM.

The refrigeration apparatus 30 has a bypass pipe 36 through which a hot gas can be supplied directly to the evaporator 14 from the compressor CM without going through the condenser CD and the expansion unit EV. Disposed in the bypass pipe 36 is a hot gas valve HV which closes the path of the bypass pipe 36 in an openable/closable manner. With the hot gas valve HV opened in the deicing operation, the temperature of the ice-making unit 10 is increased by the hot gas supplied to the evaporator 14. Reference numeral “FM” in FIG. 1 denotes a fan motor which is driven during the ice-making operation to cool down the condenser CD.

As shown in FIG. 2, the individual components constituting the refrigeration apparatus 30, such as the compressor CM, the fan motor FM and the hot gas valve HV, the circulation pump PM and the water supply valve WV are controlled by a controller C. The controller C has a timer TM and various counters, such as a water supply counter WI, a water supply end counter WF, a circulation pump counter PS, a deicing counter FD and a backup counter BU, which count by a predetermined value (“1” in the first embodiment) in response to the action of the timer TM. The water supply counter WI manages the water supply state in the deicing operation. The water supply end counter WF manages the timing for completing water supply and closes the water supply valve WV in the deicing operation. The circulation pump counter PS manages the timing for driving the circulation pump PM in the deicing operation. The deicing counter FD manages the timing for completing the deicing operation and serves as a deicing completion detecting unit which closes the water supply valve WV and the hot gas valve HV. The backup counter BU closes the water supply valve WV and the hot gas valve HV in emergency to avoid an abnormal deicing operation.

The controller C executes a “timer interruption program” by interruption every time the timer TM measures a predetermined time. Accordingly, a water supply count value WICT of the water supply counter WI and a backup count value BUCT of the backup counter BU are counted up by “1”. Likewise, a water-supply completion count value WFCT of the water supply end counter WF, a deicing count value FDCT of the deicing counter FD and a circulation pump count value PSCT of the circulation pump counter PS are counted up by “1”. When the count value of each counter reaches a set value previously set, each corresponding component performs a predetermined operation.

The temperature detecting unit TH is disposed in the refrigerant pipe 34 connected to the outlet side of the evaporator 14 (see FIG. 1). Detecting the temperature of the refrigerant flowing in the refrigerant pipe 34, the temperature detecting unit TH monitors the temperature of the evaporator 14 and determines the liquefaction state of ice cubes M in the deicing operation. The result of temperature detection by the temperature detecting unit TH is input to the controller C. When the temperature detection result is equal to or greater than the set temperature T1, the deicing counter FD and the circulation pump counter PS start counting. The circulation pump PM is driven after the first set time elapses after detection of the set temperature T1 by the temperature detecting unit TH, and ice-making water is sprayed to the ice-making unit 10. The first set time is the time at which the circulation pump count value PSCT has reached a set value CT101. When the deicing count value FDCT reaches a set value CT4 thereafter, the water supply valve WV and the hot gas valve HV are closed, stopping the deicing operation. The set temperature T1 is set to a temperature (e.g., 9° C. or so) just before ice cubes M on the ice making surface of the ice-making unit 10 starts melting and the temperature near the outlet of the evaporator 14 hardly changes (is saturated). The set value CT4 of the deicing count value FDCT is set larger than the count value CT101 of the circulation pump count value PSCT.

A temperature detection flag TFLG is set in the controller C. The temperature detection flag TFLG is changeover means which sets conditional branching for progressing or repeating the deicing operation based on the result of detection by the temperature detecting unit TH.

Operation of First Embodiment

An operation method for the automatic ice maker according to the first embodiment will be described below referring to flowcharts shown in FIGS. 3 and 4. When the automatic ice maker starts the ice-making operation, the ice-making unit 10 exchanges heat with the refrigerant circulating in the evaporator 14 to be forcibly cooled. The ice-making water is supplied to the ice making surface of the ice-making unit 10 from the ice-making water tank 20 by the circulation pump PM, and gradually starts being frozen on the ice making surface. The ice-making water which has not being frozen is collected into the ice-making water tank 20 via the through holes of the guide plate 18, and is supplied again to the ice-making unit 10 by the circulation pump PM. When completely producing ice cubes M on the ice making surface of the ice-making unit 10, the automatic ice maker stops the ice-making operation and shifts to the deicing operation. At this time, the compressor CM is kept driven, and the fan motor FM is stopped (step S1).

When the deicing operation starts, the circulation pump PM is stopped to stop supply of the ice-making water from the ice-making sprinkler 24. As the hot gas valve HV is opened, the hot gas is supplied to the evaporator 14 (step S2). At the same time, the water supply valve WV is opened to supply the deicing water to the bottom side of the ice-making unit 10 from the deicing water sprinkler 28, increasing the temperature of the ice-making unit 10 (step S2). As a result, liquefaction at the frozen surfaces of the ice cubes M formed on the ice making surface of the ice-making unit 10 gradually occurs.

The backup count value BUCT of the backup counter BU, the water supply count value WICT of the water supply counter WI and the water-supply completion count value WFCT of the water supply end counter WF are reset to “0”. Further, after the temperature detection flag TFLG is set to an initial value “0” (step S3), the operation goes to step S4. Each counter WI, WF, BU counts up the corresponding count value WICT, WFCT, BUCT by “1” every time the timer TM measures a predetermined time.

In step S4, it is determined whether or not the backup count value BUCT of the backup counter BU is equal to or greater than a set value CT2. The set value CT2 is set to a value equivalent to a time (e.g., 20 minutes or so) larger than the time needed for all the ice cubes M to be separated from the ice-making unit 10 in the normal deicing operation. When the backup count value BUCT is smaller than the set value CT2, the flow goes to a decision on the water supply count value WICT of the water supply counter WI (step S5). When the backup count value BUCT is equal to or greater than the set value CT2, on the other hand, the hot gas valve HV is closed to stop supplying the hot gas to the evaporator 14 (step S13). The deicing operation takes an emergency stop as the water supply valve WV is closed to stop supplying the deicing water to the ice-making unit 10 from the deicing water sprinkler 28 (step S13). At this time, the controller C may generate an alarm or the like. When the completion of deicing takes time and the backup count value BUCT becomes equal to or greater than the set value CT2, it is decided that some kind of abnormality has occurred, and the deicing operation is stopped. This prevents wasteful consumption of the deicing water and reduces the load of the compressor CM.

Next, it is determined whether the amount of the deicing water supplied to the bottom side of the ice-making unit 10 from the deicing water sprinkler 28 is large or small (step S5). In this step S5, the amount of the deicing water stored in the ice-making water tank 20 is determined by determining whether or not the water supply count value WICT of the water supply counter WI is equal to or greater than a set value CT6. The set value CT6 is set to a value equivalent to the time (e.g., 3 minutes or so) needed for filling up the ice-making water tank 20 with the necessary amount of the ice-making water in the normal deicing operation. When the water supply count value WICT is equal to or greater than the set value CT6, the flow goes to a decision on the water-supply completion count value WFCT of the water supply end counter WF (step S6). When the water supply count value WICT is smaller than the set value CT6, on the other hand, the flow returns to step S4 to repeat the processes of step S4 and step S5.

In step S6, it is determined whether or not the water-supply completion count value WFCT of the water supply end counter WF is equal to or greater than a set value CT3 previously set. When the time of the deicing operation becomes longer due to the ambient temperature, the temperature of the deicing water or the like in step S5, an excess amount of the deicing water is discharged from the overflow pipe 21 since a certain amount of the deicing water is stored in the ice-making water tank 20. When the water-supply completion count value WFCT is equal to or greater than the set value CT3 in step S6, it is determined that the supply time of the deicing water is abnormally long, so that the water supply valve WV is closed to stop supplying the deicing water from the deicing water sprinkler 28 (step S61). Then, the flow goes to step S7. Accordingly, the deicing water is not excessively supplied to the ice-making unit 10, saving the amount of the deicing water. When the water-supply completion count value WFCT is smaller than the set value CT3, the flow goes to step S7 with the water supply valve WV left open. The set value CT3 of the water-supply completion count value WFCT is set larger than the set value CT6 of the water supply count value WICT, e.g., 6 minutes or so.

In step S7, the flow branches depending on the value of the temperature detection flag TFLG. When the value of the temperature detection flag TFLG is the initial value “0”, the flow goes to a step of detecting the temperature of the evaporator 14 (step S8) by the temperature detecting unit TH. In step S8, when the temperature detected by the temperature detecting unit TH is equal to or greater than the set temperature T1, the deicing count value FDCT of the deicing counter FD and the circulation pump count value PSCT of the circulation pump counter PS are reset to “0”. In addition, the deicing counter FD and the circulation pump counter PS start counting and the temperature detection flag TFLG is changed from “0” to “1” (step S9), after which the flow returns to step S4.

When the temperature of the evaporator 14 has not reached the set temperature T1 yet, however, the deicing counter FD and the circulation pump counter PS are not activated. That is, the flow goes to step S4 without going through step S9, and steps S4 to S8 are repeated until the temperature detecting unit TH detects the set temperature T1. Solid lines (1), (2) and (3) in FIG. 3 connect to solid lines (1), (2) and (3) in FIG. 4, respectively.

When the temperature detecting unit TH detects the set temperature T1, the temperature detection flag TFLG is changed to “1”, shifting the process to step S10 from step S7, so that the deicing operation further progresses. That is, it is determined that as the temperature of the evaporator 14 rises to the set temperature T1, the frozen state between the ice-making unit 10 and the ice making surfaces of the ice cubes M is released to some extent. In step S10, the timing for spraying ice-making water to the ice-making unit 10 from the ice-making sprinkler 24 is determined. When the circulation pump count value PSCT of the circulation pump counter PS exceeds the first set time greater than the set value CT101, the circulation pump PM is driven (step S11). As a result, the ice-making water is pumped out from the ice-making water tank 20 and supplied to the ice-making unit 10 from the ice-making sprinkler 24. Then, the increased temperature of the ice-making unit 10 with the hot gas and the deicing water as well as the ice-making water flowing down the ice making surface of the ice-making unit 10 further promotes the separation of the ice cubes M from the ice-making unit 10. When the circulation pump count value PSCT is smaller than the set value CT101, on the other hand, the flow returns to step S4 and the processes of steps S4 to S7 are repeated to continue the deicing operation.

When the deicing count value FDCT of the deicing counter FD reaches the set value CT4, it is determined that all the ice cubes M are separated from the ice-making unit 10, and the deicing operation is completed (step S12). At this time, the water supply valve WV is closed to stop supplying the deicing water and the hot gas valve HV is closed to stop supplying the hot gas to the evaporator 14 (step S13), thereby stopping increasing the temperature of the ice-making unit 10. When the deicing count value FDCT has not reached the set value CT4, on the other hand, the flow returns to step S4 and the processes of steps S4 to S7 and step S10 are repeated. The set value CT4 of the deicing count value FDCT is set to a value (equivalent to one minute or so) greater than the set value CT101 of the circulation pump count value PSCT. That is, the set value CT4 is set in such a way that the ice-making water can be supplied to the ice-making unit 10 before the deicing operation is terminated.

Then, the automatic ice maker repeats the cycle of shifting to the ice-making operation again after going through a needed operation such as the water discharge operation.

In the deicing operation, the automatic ice maker drives the circulation pump PM to supply the ice-making water to the ice making surface of the ice-making unit 10 from the ice-making sprinkler 24 after the temperature detecting unit TH detects the set temperature T1. Accordingly, liquefaction at the frozen surfaces of the ice cubes M directly occurs, thus quickening the timing of separating the ice cubes M. That is, the set value CT4 of the deicing count value FDCT can be set small, making it possible to shorten the time to complete the deicing operation since the detection of the set temperature T1 by the temperature detecting unit TH. Therefore, the overall time of the deicing operation is shortened with the ice cubes M surely separated from the ice-making unit 10. This can reduce the amount of the deicing water needed and improve the ice making efficiency.

If the automatic ice maker supplies ice-making water to the ice making surface of the ice-making unit 10 immediately after the transition from the ice-making operation to the deicing operation, the ice-making water may be frozen. Because the ice-making water is supplied to the ice-making unit 10 which is warmed to some degree in the automatic ice maker of the first embodiment, however, it is possible to prevent the ice-making water from being frozen and adequately promote separation of the ice cubes M. In addition, as the ice-making water is supplied from the ice-making sprinkler 24 disposed above the ice-making unit 10, separation of the ice cubes M is promoted more adequately by the force of the ice-making water flowing down along the ice making surface. There may be a case where surface tension is generated by the liquefaction between the ice cubes M and the ice making surface, making it difficult for the ice cubes M to fall, during separation of the ice cubes M from the ice-making unit 10. Even in this case, the ice-making water whose temperature is relatively higher than the temperature of the ice cubes M is directly sprayed onto the ice cubes M, making it possible to reduce the surface tension and promote deicing.

The set value of each counter and the measuring time of the timer TM can be set arbitrarily according to the environmental condition, such as the ambient temperature or the temperature of the deicing water. In particular, because the count values of the individual counters can be changed collectively by changing the measuring time of the timer TM, the set values can be easily changed. Because the automatic ice maker can always perform the deicing operation under the optimal operational condition by adequately changing the operational condition, the ice making efficiency can be improved.

Second Embodiment

FIG. 5 is a flowchart illustrating an operation method for an automatic ice maker according to the second embodiment. Solid lines (1), (2) and (3) in FIG. 5 connect to solid lines (1), (2) and (3) in FIG. 3, respectively. The first half part of the deicing operation of the second embodiment is similar to the first half part of the deicing operation of the first embodiment explained referring to FIG. 3. That is, the fundamental portion of the second embodiment is similar to that of the first embodiment, so that only different portions will be described.

The automatic ice maker of the second embodiment supplies ice-making water to the ice-making unit 10 by driving the circulation pump PM after the first set time elapses since detection by the temperature detecting unit TH that the temperature of the evaporator 14 has reached the set temperature T1. At the same time, the water supply valve WV is closed to stop supplying the deicing water from the deicing water sprinkler 28. As shown in FIG. 5, when the temperature detecting unit TH detects the set temperature T1 (step S8), it may be determined that liquefaction of ice cubes M is progressing to some degree. Accordingly, the deicing counter (deicing completion detecting unit) FD and the circulation pump counter PS start counting the deicing count value FDCT and the circulation pump count value PSCT, respectively (step S9). In step S9, the temperature detection flag TFLG is switched to “1”, permitting the shifting from step S7 to step S10.

When the circulation pump count value PSCT reaches the set value CT101, the circulation pump PM is driven to spray the ice-making water to the ice making surface of the ice-making unit 10 from the ice-making sprinkler 24 (step S10). As the water supply valve WV is closed, the deicing water sprinkler 28 stops spraying the deicing water to the ice-making unit 10 (step S11a). When the set value CT101 is counted, the first set time is reached. When the deicing count value FDCT becomes the set value CT4, it is determined that all the ice cubes M are separated from the ice-making unit 10 (step S12). As a result, the hot gas valve HV is closed to stop supplying the hot gas to the evaporator 14 (step S13a), thereby stopping increasing the temperature of the ice-making unit 10.

The operation method for the automatic ice maker of the second embodiment has an operational advantage of being able to further reduce the amount of the deicing water to be used in the deicing operation as compared with the first embodiment, in addition to the operational advantages of the operation method of the first embodiment. The ice-making water supplied to the ice-making unit 10 from the ice-making water tank 20 by the circulation pump PM circulates in the automatic ice maker. The deicing water to be supplied from an external water source is discharged outside through the overflow pipe 21 if the amount of the deicing water exceeds the pondage of the ice-making water tank 20. That is, the discharge amount of the deicing water can be reduced by stopping the supply of the deicing water at the time of supplying the ice-making water to the ice-making unit 10 by means of the circulation pump PM. The ice-making water which directly contacts the ice cubes M is excellent in deicing efficiency than the deicing water which indirectly increases the temperature of the ice cubes M from the bottom side of the ice-making unit 10. Therefore, reduction in the deicing efficiency caused by stopping the supply of the deicing water is avoided.

Third Embodiment

FIG. 6 is a control block diagram of an automatic ice maker according to the third embodiment. A controller C2 of the third embodiment has a water supply valve counter WS added to the controller C described in the foregoing description of the first embodiment. The water supply valve counter WS manages the timing for stopping supplying the deicing water after the temperature detecting unit TH detects the set temperature T1. FIG. 7 is a flowchart illustrating an operation method for the automatic ice maker according to the third embodiment. Solid lines (1), (2) and (3) in FIG. 7 connect to solid lines (1), (2) and (3) in FIG. 3, respectively. The first half part of the deicing operation of the third embodiment is similar to the first half part of the deicing operation of the first embodiment explained referring to FIG. 3. That is, the fundamental portion of the third embodiment is similar to that of the first embodiment, so that only different portions will be described.

The automatic ice maker of the third embodiment supplies ice-making water to the ice-making unit 10 by driving the circulation pump PM after the first set time elapses since detection by the temperature detecting unit TH that the temperature of the evaporator 14 has reached the set temperature T1. When a second set time elapses after the detection of the set temperature T1 by the temperature detecting unit TH, the water supply valve WV is closed to stop supplying the deicing water from the deicing water sprinkler 28. The second set time is set shorter than the first set time so that supply of the deicing water is stopped before the circulation pump PM is driven.

As shown in FIG. 7, when the temperature detecting unit TH detects the temperature of the evaporator 14 having reached the set temperature T1 (step S8), it is determined that liquefaction of ice cubes M is progressing to some degree. Accordingly, the deicing counter (deicing completion detecting unit) FD, the circulation pump counter PS and the water supply valve counter WS start counting the deicing count value FDCT, the circulation pump count value PSCT and a water supply valve count value WSCT, respectively (step S9a). In step S9a, the temperature detection flag TFLG is switched to “1”, permitting the shifting of the deicing operation from step S7 (to step S102).

When the water supply valve count value WSCT of the water supply valve counter WS reaches a set value CT102 (step S102), the water supply valve WV is closed to stop spraying the deicing water from the deicing water sprinkler 28 (step S111). Then, the automatic ice maker goes to step S10. The set value CT102 is set to a value equivalent to the second set time.

When the circulation pump count value PSCT of the circulation pump counter PS reaches the set value CT101 (step S10), the circulation pump PM is driven to spray the ice-making water to the ice making surface of the ice-making unit 10 from the ice-making sprinkler 24 (step S112). Then, the automatic ice maker proceeds to step S12. The set value CT101 is set to a value equivalent to the first set time.

When the deicing count value FDCT becomes the set value CT4 in step S12, it is determined that all the ice cubes M are separated from the ice-making unit 10. As a result, the hot gas valve HV is closed to stop supplying the hot gas to the evaporator 14 (step S13a), thereby stopping increasing the temperature of the ice-making unit 10.

According to the operation method for the automatic ice maker of the third embodiment, because supply of the deicing water is stopped at an early timing after detection of the set temperature T1 by the temperature detecting unit TH, the amount of water to be used in the deicing operation can be reduced more than the second embodiment can. The operation method for the automatic ice maker of the third embodiment demonstrates the operational advantages of the operation method of the first embodiment or the second embodiment.

Fourth Embodiment

FIG. 8 shows the schematic configuration of a flow-down type ice maker 110 which executes an operation method for an automatic ice maker according to the fourth embodiment. An ice-making unit 111 of the flow-down type ice maker 110 has a pair of vertical ice-making plates 112, 112 arranged facing each other at a predetermined distance therebetween, and an evaporator 114 fixed between the opposing sides of the ice-making plates 112, 112. The evaporator 114 sticks out from the refrigeration system and extends in a zigzagged form in the horizontal direction of the ice-making plates 112. A guide plate 120 is disposed inclined directly below each ice-making plate 112. The guide plate 120 guides ice cubes M, which are separated from each ice-making plate 112 in a deicing operation, to a stocker 118 located below. Each guide plate 120 has a plurality of through holes 122 formed therein. In performing an ice-making operation, an unfrozen part of ice-making water 124 supplied to the ice making surface (top side) 132 of the ice-making plate 112 is collected into an underlying ice-making water tank 126 via the through holes 122. The ice-making water tank 126 collects deicing water 130 supplied to the bottom side, 128, of the ice-making plate 112 in the deicing operation.

A double pipe 138 is disposed above the ice-making unit 111. The double pipe 138 has an ice-making water spray pipe 134 which supplies the ice-making water 124 to the ice making surface 132 of each ice-making plate 112, and a deicing water spray pipe 136 which supplies the deicing water 130 to the bottom side 128. The ice-making water spray pipe 134 is connected to an ice-making water supply pipe 142 extending out from the ice-making water tank 126 via a circulation pump (ice-making water supply unit) 140 disposed in the ice maker. In ice-making operation mode, the ice-making water 124 is pumped out from the ice-making water tank 126 to each ice-making plate 112 by the circulation pump 140 and is sprayed onto the ice making surface 132 cooled down to the freezing temperature, thus forming hemispherical ice cubes M at the ice making surface 132. The circulation pump 140 is connected to the controller 144 which switches between supply of the ice-making water 124 and stopping supplying the ice-making water 124 in the ice-making operation and the deicing operation.

The deicing water spray pipe 136, provided inside the double pipe 138, sprays water of normal temperature (deicing water 130) to the bottom sides 128, 128 of both ice-making plates 112, 112 in deicing operation mode. The deicing water spray pipe 136 is connected to a deicing water supply pipe 148 connected to an external water source (not shown). A water supply valve (deicing water supply unit) 146 is disposed in the deicing water supply pipe 148. That is, in the deicing operation, a hot gas circulating in the evaporator 114 heats each ice-making plate 112 whose bottom side 128 is sprayed with the deicing water 130 from the deicing water spray pipe 136. As a result, liquefaction at the frozen surfaces between each ice making surface 132 and the ice cubes M occurs. The water supply valve 146 is connected to the controller 144 which switches between supply of the deicing water 130 and stopping supplying the deicing water 130 in the deicing operation.

A deicing thermometer 152 is tightly disposed at the outlet side of the evaporator 114. The deicing thermometer 152 is connected to the controller 144, and serves as the deicing completion detecting unit that detects the temperature of the hot gas circulating in the evaporator 114. When the deicing thermometer 152 detects that the temperature of the hot gas has reached a preset deicing completion temperature in the deicing operation, the controller 144 terminates the deicing operation and shifts to the ice-making operation. Note that the temperature of the hot gas rapidly increases when the ice cubes M are separated from each ice-making plate 112.

When the deicing thermometer 152 detects an ice-making water supply temperature (ice-making-water supply start condition) in the deicing operation, the controller 144 controls the circulation pump 140 to supply the ice-making water 124 to the ice making surface 132 from the ice-making water spray pipe 134. The ice-making water supply temperature is set to a temperature, for example, lower than the deicing completion temperature by about 10° C. to 20° C. That is, as the ice-making water 124 is supplied to the ice making surface 132 before deicing completes, the separation of the ice cubes M remaining on the ice making surface 132 is promoted. The deicing completion temperature and the ice-making water supply temperature have only to be set to adequate values according to the ice-making performance of the flow-down type ice maker 110, the site thereof, and the like. It is to be noted that if the ice-making water supply temperature is set considerably lower than the deicing completion temperature, the ice-making water 124 is supplied without liquefaction taking place between the ice cubes M and the ice-making plate 112. In this case, because the supply amount of the ice-making water 124 needed in completing deicing is increased, it is preferable that the ice-making water supply temperature should be set lower than the deicing completion temperature by 10° C. or so. In the fourth embodiment, the deicing thermometer 152 serves as the ice-making-water supply start detecting unit.

The refrigeration apparatus of the flow-down type ice maker 110 is basically the same as the conventional ice maker. In the refrigeration apparatus, the vaporized refrigerant compressed by a compressor 154 passes through a discharge pipe 168 to a condenser 156 where the refrigerant is liquefied. The liquefied refrigerant is dehumidified by a dryer 158 and is then depressurized by a capillary tube 160. The liquefied refrigerant flows into the evaporator 114 and is expanded and evaporated at a burst, exchanging heat with each ice-making plate 112 to thereby cool the ice-making plate 112 down to the degree of frost. The vaporized refrigerant vaporized in the evaporator 114 and the liquefied refrigerant unvaporized flow into an accumulator 162 in a gas-vapor phase, and is separated into a gas and a liquid therein. The vaporized refrigerant is fed back to the compressor 154 via a suction pipe 164, and the liquid-phase refrigerant is stored in the accumulator 162.

A hot gas pipe 166 is branched from the discharge pipe 168 of the compressor 154 in the refrigeration apparatus, and communicates with the inlet side of the evaporator 114 via the hot gas valve HV. The hot gas valve HV is controlled by the controller 144 in such a way as to be opened only during the deicing operation and closed in the ice-making operation. In performing the deicing operation, the hot gas expelled from the compressor 154 flows into the evaporator 114 via the hot gas pipe 166 and exchanges heat with each ice-making plate 112. The hot gas flowing out from the evaporator 114 flows into the accumulator 162, vaporizes the liquefied refrigerant remaining in the accumulator 162 to yield a liquefied refrigerant. Accordingly, the liquefied refrigerant is fed back again to the compressor 154 from the suction pipe 164.

Operation of Fourth Embodiment

An operation method for the flow-down type ice maker 110 of the fourth embodiment will be described below. As shown in FIG. 9, when ice making is completed, the controller 144 stops the circulation pump 140 to stop supplying the ice-making water 124 from the ice-making water spray pipe 134. In addition, the controller 144 opens the hot gas valve HV to stop supplying the refrigerant to the evaporator 114, and then terminates the ice-making operation (S201).

The controller 144 opens the water supply valve 146 to supply the deicing water 124 to the bottom side 128 of each ice-making plate 112 from the deicing water spray pipe 136. Further, opening the hot gas valve HV supplies the hot gas to the evaporator 114, starting the deicing operation (S202). As shown in FIG. 10, at the time of switching from the ice-making operation to the deicing operation, the supply of the refrigerant and the ice-making water 124 is stopped (OFF), and, at the same time, the supply of the hot gas and the deicing water is started (ON). The start of the deicing operation causes liquefaction to start taking place at the frozen surfaces of the ice cubes M frozen on the ice making surface 132 due to the hot gas and the deicing water 130 supplied.

In the deicing operation, as liquefaction at the frozen surfaces between the ice cubes M and the ice making surface 132 progresses, the temperature of the hot gas on the outlet side of the evaporator 114 gradually rises. When a predetermined time elapses since the start of the deicing operation and deicing approaches its completion, the deicing thermometer 152 detects the ice-making water supply temperature (S203). At this time, liquefaction at the frozen surfaces of the ice cubes M has made some progress, and some of the ice cubes M are separated from the ice-making plate 112 due to their own weight, or some are remaining thereon without being liquefied. When the deicing thermometer 152 detects the ice-making water supply temperature, the controller 144 activates the circulation pump 140 to pump out the ice-making water 124 to the ice-making water spray pipe 134 and starts supplying the ice-making water 124 to the ice making surface 132 (ON). Further, the controller 144 closes the water supply valve 146 to stop supplying the deicing water 130 from the deicing water spray pipe 136 (OFF) (S204).

That is, the liquefaction at the frozen surfaces between the ice cubes M and the ice-making plate 112 is accelerated by the ice-making water 124. Because the ice cubes M are separated from the ice-making plate 112 by the current of the ice-making water 24, double icing which is the conventional problem can be prevented, thus yielding good hemispherical ice cubes M. When all the ice cubes M are removed from both ice-making plates 112, 112, the temperature of the hot gas rises rapidly and the deicing thermometer 152 detects the deicing completion temperature (S205). At this time, the controller 144 closes the hot gas valve HV to stop supplying the hot gas to the evaporator 114 (S206) and terminates the deicing operation (S207). The controller 144 then starts the ice-making operation.

Because the ice cubes M can be removed from the ice-making plate 112 promptly this way, it is possible to shorten the deicing time to improve the daily ice making performance. Because the supply of the deicing water 130 is stopped before completion of the deicing operation as shown in FIG. 10, the amount of the deicing water 130 to be used can be reduced.

The operation method for the flow-down type ice maker 110 of the fourth embodiment stops supplying the deicing water 130 at the same time as supplying the ice-making water 124 before completion of deicing, as shown in FIG. 10. However, the supply of the deicing water 130 may be stopped when the deicing operation is terminated as the supply of the hot gas is stopped.

Fifth Embodiment

An operation method for an automatic ice maker according to the fifth embodiment will be described next. Because the configuration of the flow-down type ice maker to be used in the fifth embodiment is basically the same as the configuration of the fourth embodiment, only different portions will be described.

At the time of supplying ice-making water 124 upon detection of the ice-making water supply temperature by the deicing thermometer 152, the controller 144 of the fifth embodiment controls the circulation pump 140 so as to intermittently supply the ice-making water 124. When the deicing thermometer 152 detects the deicing completion temperature, the controller 144 controls the circulation pump 140 in such a way as to stop the intermittent supply of the ice-making water 124 and continuously supply the ice-making water 124.

The expression “intermittent supply” means that the supply/stop of the ice-making water 124 is executed periodically or non-periodically, and includes intermittent supply of the ice-making water 124 where the supply/stop of the ice-making water 124 is repeated at a given interval. The ice-making water supply temperature in the fifth embodiment is set lower than the ice-making water supply temperature in the fourth embodiment, e.g., a temperature lower than the deicing completion temperature by 25° C. to 35° C. or so.

As shown in the flowchart in FIG. 11, when ice making is completed, the controller 144 stops the circulation pump 140 to stop supplying the ice-making water 124 from the ice-making water spray pipe 134. At the same time, the hot gas valve HV is opened to stop supplying the refrigerant to the evaporator 114, thereby terminating the ice-making operation (S208). Then, the controller 144 opens the water supply valve 146 to supply the deicing water 130 to the bottom side 128 of each ice-making plate 112 from the deicing water spray pipe 136. At the same time, the controller 144 opens the hot gas valve HV to supply the hot gas to the evaporator 114 to start the deicing operation (S209).

As shown in the timing chart in FIG. 12, when the ice-making operation is shifted to the deicing operation, the supply of the refrigerant and the ice-making water 124 is stopped (OFF), and the supply of the hot gas and the deicing water 130 is started (ON). When the deicing operation is started, the frozen surfaces of the ice cubes M frozen on the ice making surface 132 start being liquefied by the hot gas and the deicing water 130 supplied. This gradually raises the temperature of the hot gas on the outlet side of the evaporator 114. When a predetermined time elapses since the start of the deicing operation, the deicing thermometer 152 detects the ice-making water supply temperature (S210).

When the deicing thermometer 152 detects the ice-making water supply temperature, the controller 144 controls the circulation pump 140 in such a way as to intermittently pump out the ice-making water 124 to the ice-making water spray pipe 134, starting the intermittent supply of the ice-making water 124 (initiation of the intermittent supply of ice-making water: S211). As shown in FIG. 12, specifically, when the ice-making water supply temperature is detected, the controller 144 executes a cycle where the supply and stop of the ice-making water 124 at a given interval, e.g., the supply of the ice-making water 124 for 5 seconds and then the stop of the supply of the ice-making water 124 for 5 seconds, are repeated.

The interval between the supply and stop of the ice-making water 124 is preferably 5 to 10 seconds or so, which is not restrictive. The supply and stop of the ice-making water 124 should not necessarily be executed at a given interval as per the fifth embodiment. For example, only the time of supplying the ice-making water 124 may be set longer, or the time of stopping supplying the ice-making water 124 may be set longer. The supply and stop times for the ice-making water 124 may be automatically changed according to the temperature detected by the deicing thermometer 152, so that the intermittent supply of the ice-making water 124 is executed according to the progressing state of deicing.

The operation method of the fifth embodiment demonstrates operational advantages similar to those of the fourth embodiment, and suppresses liquefaction of the ice cubes M by the ice-making water 124 as compared with the case of the continuous supply of the fourth embodiment. This makes it possible to supply the ice-making water 124 at a relatively early stage of the deicing operation. That is, the deicing efficiency becomes higher than that provided by the continuous supply of the ice-making water 124, thus shortening the deicing time and further improving the ice making performance. The intermittent supply of the ice-making water 124 in deicing operation mode can reduce the amount of the ice-making water 124 scattered in the stocker 118.

The ice-making water supply temperature has only to be set to an adequate value according to the ice making performance of the flow-down type ice maker 110, the site thereof and the like as per the fourth embodiment. The timing of starting the intermittent supply of the ice-making water 124 in deicing operation mode can be changed as needed. When the ice-making water supply temperature is set substantially lower than the deicing completion temperature, however, the ice-making water is supplied with liquefaction between the ice cubes M and the ice-making plate 112 hardly progressing. Accordingly, the supply amount of the ice-making water 124 needed to complete deicing increases. In this respect, it is preferable that the ice-making water supply temperature be set lower than the deicing completion temperature by 30° C. or so.

When deicing further progresses and all the ice cubes M are separated from the ice-making plate 112, the temperature of the hot gas rises rapidly, and the deicing thermometer 152 detects the deicing completion temperature (S212). At this time, the controller 144 terminates the intermittent supply of the ice-making water 124 (S213), and switches the operation to the normal operation of continuously supplying the ice-making water 124 to the ice making surface 132. At the same time, the controller 144 closes the hot gas valve HV to stop supplying the hot gas to the evaporator 114. The controller 144 closes the water supply valve 146 to stop supplying the deicing water 130 (S214) and terminates the deicing operation (S215).

Although the operation method for the flow-down type ice maker 110 of the fifth embodiment stops supplying the deicing water 130 when deicing is completed as shown in FIG. 12, the intermittent supply of the ice-making water 124 may be started with the supply of the deicing water 130 being stopped simultaneously as per the fourth embodiment.

Although the deicing thermometer serves as both the deicing completion detecting unit and the ice-making-water supply start detecting unit in the fourth and fifth embodiments, separate temperature sensors or the like may be used. Further, a timer which starts counting when the deicing operation is started can be used as the ice-making-water supply start detecting unit. At this time, the continuous supply or intermittent supply of the ice-making water should be started when the ice-making-water supply start time set in the timer (ice-making-water supply start condition) is reached. In this case, the ice-making-water supply start time is set shorter than the time needed to complete deicing. A temperature sensor (deicing thermometer) or a timer which measures the deicing completion temperature can be used as the deicing completion detecting unit in the case of using the timer.

The configuration of the ice-making unit is not limited to those of the embodiments 4 and 5, but an evaporator may be disposed at the bottom side of a single ice-making plate or the ice-making plate may be disposed inclined. Further, in a case where a deicing thermometer is used as the deicing completion detecting unit, the target whose temperature is to be detected by the thermometer is not limited to a hot gas, but the temperature of the ice-making plate itself which changes when the deicing operation completes may be detected.

Operation method for automatic ice maker

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CPC

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