The present invention relates to a control method for cooling devices wherein clear ice cubes are formed by fractional freezing in a vertical mold. In the fresh food compartment or in a separate ice making device in the thermally- insulated body of the cooling devices, clear ice pieces are produced by flowing water over a vertical metal mold connected to an evaporator and by cooling the metal surface. Clear ice pieces can be obtained by removing the air dissolving in the water and cleansing the water of foreign materials such as dust, chlorine, some minerals, etc. as much as possible during or before freezing the water. The ice obtained has a clear and aesthetic appearance to the extent that the air content in the crystallized ice is removed. The ice crystallizing while freezing transfers the air therein to the water. During the formation of ice, the air dissolving in the water accumulates in the remaining water and particularly in the thin layer just above the freezing surface. If the concentration of the dissolved air exceeds a certain value, bubble formation occurs. A large number of small bubbles are formed during quick freezing and the obtained ice has a foggy appearance.

It is possible to produce clear ice pieces by decreasing the freezing speed and thus removing the air in the water by diffusion. However, this process requires very long periods of time such as 6 to 10 hours. In order to obtain clear ice pieces in shorter periods of time, the water at the freezing surface must be in constant flow. This method is called fractional freezing method. The dissolved air separated from the ice when the water being frozen is not stagnant but flows is carried with the water and does not accumulate on the ice. Thus, bubble formation is prevented. In the devices producing clear ice by means of the fractional freezing method, various methods are used to decide whether sufficient amount of ice is produced and to terminate the ice making process. For example, the decision can be made based on the instantaneous temperature value on the evaporator. An additional electromechanical or optical component that measures the mass of the ice can be used. Another method is to estimate how much ice is produced based on how much the water in the tank lessens. However, due to space restrictions, error margin in the measurements of the water level in the water tank that has a shallow and broad structure is high. Therefore, the measurement must be performed at more than one point and this increases costs. The Patent Document No. EP0869321 discloses a method for freeze control by measuring the temperature of the refrigerant leaving the condenser of the cooling system at a predetermined time after initiation of the freeze cycle in clear ice production and correlating the duration of the freeze cycle with the measured temperature and for harvesting the formed ice cubes. The temperature of the refrigerant is measured again at a predetermined time before termination of the freeze cycle and the duration of the harvest cycle is inversely correlated to the second measured temperature.

The aim of the present invention is to measure the duration of ice cube collection in a simple manner with high precision in the production of clear ice. The present invention realized in order to attain the said aim is a cooling device comprising a thermally-insulated cabin; a clear ice mechanism that is provided in the cabin and that comprises an ice tray arranged such that the water supplied by a water distributor disposed thereabove passes through successive partitions thereon so as to flow longitudinally; an evaporator that is provided in the vicinity of the ice tray so as to cool the ice tray, and a temperature sensor that is provided in the vicinity of the evaporator. In the preferred embodiment of the present invention, the cooling device comprises a control unit that is operationally connected to the temperature sensor measuring the temperature in the vicinity of the evaporator at a predetermined period and that adds up all the active ice mass values calculated for each active temperature value provided by the temperature sensor in order to obtain the total ice mass and that generates a signal for activating a discharge mechanism to discharge the clear ice in the ice tray if the total ice mass exceeds a predetermined ice mass threshold value. With the temperature sensor periodically measuring the successive active temperature values, how much ice mass is produced can be calculated according to the temperature of the evaporator and taking the geometry of the ice tray into account. Thus, the most accurate ice mass collection is calculated for each active temperature value measurement and added to the previous active ice mass value, and the active temperature value measurement continues until the desired ice mass is reached. In a preferred embodiment, the control unit comprises a central processing unit (CPU) that is provided on the cabin.

In a preferred embodiment of the present invention, the temperature sensor is configured to provide data to the control unit at a period selected between 0.5 second to 5 seconds. This period is the most appropriate value for forming and growing ice crystals in the cooling device and for obtaining ice cubes with similar masses reaching the desired ice mass.

In a preferred embodiment of the present invention, the cooling device comprises a water container that is fluidly connected to the water distributor and a container temperature sensor that transmits the water temperature information of the water container to the control unit for controlling the freezing state by means of an operational connection. Upon detecting that the water to be delivered to the water distributor is frozen in the water container, the control unit prevents the system from operating unnecessarily.

In a preferred embodiment of the present invention, the cooling device comprises a memory module that is provided as operationally connected to the control unit and that stores the total ice mass value to which the active ice mass value is added until the thickness value threshold is exceeded. The memory module provides that the active temperature value information added at high frequency is controlled by the control unit at the end of each period by being compared with the previous value or the previous array of values and reported for maintenance if required. A preferred embodiment of the present invention realized in order to attain the said aims comprises the operational steps of resetting the total ice mass and active ice mass values as initial value by the control unit; measuring the active temperature value of the evaporator by the temperature sensor; calculating the active temperature value and the active ice mass generated between the previous total ice mass and the measurement period; adding the active ice mass to the previous total ice mass; comparing the total ice mass value with the predetermined ice mass threshold value, and activating the discharge mechanism if the ice mass threshold value is exceeded. This method allows the calculation of how much ice is produced in unit time. Thus, it can be determined with high precision and with the least error margin how much ice is collected in the ice tray connected to the evaporator by taking standard ice dimensions in the cooling devices into consideration. Moreover, by activating the discharge mechanism, a system ready for the next ice production process is obtained.

In a preferred embodiment of the present invention, the method of the present invention comprises the step of measuring the active temperature value at a period determined between 1 second to 2 seconds. The said values provides the collection of information at high frequency and the calculation of the most accurate total ice mass when the ice collection speed is taken into consideration.

A preferred embodiment of the present invention comprises the operational steps of determining the freezing state of the water in the water container by the control unit by means of the container temperature sensor at the start; generating an alarm signal in case freezing is detected, and terminating the process without proceeding to the following steps.

A cooling device realized in order to attain the aim of the present invention is illustrated in the attached figures, where:

Figure 1 - is the front perspective view of a cooling device comprising a representative embodiment of the clear ice making mechanism of the present invention.

Figure 2 - is the schematic view of a control system for the clear ice making mechanism of the present invention.

The elements illustrated in the figures are numbered as follows:

1 Cabin

2 Upper compartment 3 Lower compartment

4 Drawer

5 Ice receptacle

6 Control unit 7 Memory module

10 Clear ice mechanism 12 Ice tray 14 Partition 20 Water distributor 30 Evaporator

32 Temperature sensor

40 Water container

42 Container temperature sensor

50 Discharge mechanism Figure 1 shows the front perspective view of a thermally-insulated cabin (1) of a refrigerator comprising a clear ice mechanism (10). The cabin (1) is divided into two adjacent compartments, namely an upper compartment (2) and a lower compartment (3). In the lower compartment (3), an ice receptacle (5) extends over a drawer (4) in a detachable manner along the depth of the lower compartment (3). The upper part of the ice receptacle (5) is open and an ice tray (12) is vertically positioned so as to face the upper opening of the lower compartment (3), aligned with the upper opening of the ice receptacle (5). On the ice tray (12), partitions (14) suitable for ice cube production are arranged in the form of a matrix. The clear ice mechanism (10) comprises a water distributor (20) at the upper part thereof. The water distributor (20) supplies water at a low flow rate onto the ice tray (12) through the outlets arranged at the lower part thereof. Thus, a film- like water flow constantly passes over the partitions (14). Behind the clear ice mechanism (10), an evaporator (30) bears against the ice tray (12) so as to provide heat transfer. The ice tray (12) has a metallic structure. Thus, the water flowing over the partitions (14) efficiently cooled by the evaporator (30) by means of heat conduction starts to form ice mass.

Figure 2 shows the schematic view of the control system of the cooling device of the present invention. A circuit board (not shown in the figures) is provided on the cabin (1). The circuit board supports a processor (CPU) serving as a control unit (6) and a memory module (7) that is connected to the latter in signal transmission. By means of cables the control unit (6) is connected to a temperature sensor (32) that is adjacent to the evaporator (30). Similarly, a container temperature sensor (42) that is submerged into a water container (40) fluidly connected to the water distributor (20) is connected to the control unit (6) in signal transmission. A discharge mechanism (50) is provided on the ice tray (12). If needed, the control unit (6) activates the discharge mechanism (50) and enables the clear ice to be taken out of the ice tray (12). Various discharge mechanism (50) are present in the state of the art. The Patent No. US 7587905 B2 joined as a reference patent discloses such a discharge mechanism (50) in detail.

A sample structure for the control system operated by the control unit operates as described below. First, the constants and initial values are determined in the memory module (7). The table below shows the said values for the sample algorithm.

According to the data ent or not received from the container temperature sensor (42), the control unit continues or stops the clear ice production process. If the water in the water container (40) has a temperature value above the freezing temperature, the process is continued. The container temperature sensor (42) is an NTC sensor. First, the total ice mass (m _t ) value measured at the previous period by the control unit (6) is controlled from the memory module (7) and multiplied by the unit ice heat resistance coefficient (R_birim_buz). Thus, ice heat resistance values are obtained and added to the evaporator (30) heat resistance (R _ev ap), thus redefined by the control unit (6) as the total heat resistance (R total). After this operation, the control unit (6) reads the active temperature value (T _ac t) of the temperature sensor (32) as the absolute temperature (ΔΤ). The temperature sensor (32) is of the NTC type. Here, the heat transfer ratio (Qdot) is calculated by dividing the absolute temperature (ΔΤ) by the heat resistance (Rjotai) and the total ice mass (m _t ) is calculated using the below formulas.

Qjotal = Q_total + Q_dot x d _t / 1000 mact = Q_totai / (buz hfg + buz Cp x ΔΤ x 0,5) x 1000

Here, from the heat transfer tables, buz hf _g can be acquired as the evaporation rate of the water at a certain temperature and buz c _p as the evaporation heat capacity of the water in certain temperature ranges.

If the calculated active ice mass value (m _ac t) exceeds the cut-out mass (mkesme), the control unit (6) stops the freezing process and activates the discharge mechanism (50). Otherwise, the total ice mass (m _t ) is redefined by multiplying the active ice mass (mact) by the unit length (Lbirim) and used as an input in the next unit ice heat resistance coefficient (R bimn buz) calculation in the next temperature measurement.