Liquid freezing device

Abstract

To perform control at a set upper limit temperature and a set lower limit temperature that are optimal corresponding to a set temperature of an antifreezing fluid when controlling the antifreezing fluid in a freezing tank to become in a temperature range between the set upper limit temperature and the set lower limit temperature of the set temperature by using a refrigeration device.SOLUTION: In a liquid freezing device 10, a control device 80 performs control to operate a compressor 31 of a refrigeration device 30 when a detection temperature obtained by a temperature sensor 28 becomes equal to or higher than an upper limit set temperature set by adding a predetermined addition value to a set temperature of an antifreezing fluid in a freezing tank 20, and to stop the operation of the compressor 31 of the refrigeration device 30 when the detection temperature obtained by the temperature sensor 28 becomes equal to or lower than a lower limit set temperature set by subtracting a predetermined subtraction value from the set temperature. At least one of the addition value and the subtraction value can be changed in accordance with the set temperature.SELECTED DRAWING: Figure 16

Description

[Technical field]

[0001] The present invention relates to a liquid freezing device that freezes food ingredients, food to be cooked, and other objects to be frozen using cooled antifreeze liquid. [Background technology]

[0002] Patent Document 1 discloses a food freezing device that freezes food ingredients, cooked foods, and other frozen objects with cooled antifreeze liquid. This food freezing device includes a freezing tank that stores antifreeze liquid, a freezing device that cools the antifreeze liquid by circulating a refrigerant sent from a compressor to an evaporator tube arranged in the freezing tank, and a temperature sensor that detects the temperature in the freezing tank. In this food freezing device, the operation of the compressor of the freezing device is controlled based on the temperature detected by the temperature sensor, and the antifreeze liquid in the freezing tank is cooled by the freezing device to a set temperature suitable for freezing the frozen objects. When the frozen objects are immersed in the antifreeze liquid in the freezing tank that has been cooled to a temperature suitable for freezing the frozen objects, the frozen objects are frozen through heat exchange with the cooled antifreeze liquid. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 8-298973 Summary of the Invention [Problem to be solved by the invention]

[0004] In the food freezing device (liquid freezing device) used in Patent Document 1, the operation of the compressor of the freezing device is controlled based on the temperature detected by the temperature sensor, and the antifreeze in the freezing tank (freezing tank) is cooled to a set temperature (e.g., -35°C) suitable for freezing the frozen object. In this type of food freezing device, when the operation of the freezing device is controlled based on the temperature detected by the temperature sensor, the compressor of the freezing device is operated when the temperature detected by the temperature sensor reaches an upper limit set temperature obtained by adding a predetermined additional value (e.g., 2°C) to the set temperature of the antifreeze in the freezing tank, and the operation of the compressor of the freezing device is stopped when the temperature detected by the temperature sensor reaches a lower limit set temperature obtained by subtracting a predetermined subtraction value (e.g., 2°C) from the set temperature of the antifreeze in the freezing tank, and the antifreeze in the freezing tank is controlled to be in the temperature range between the upper limit set temperature and the lower limit set temperature of the set temperature. In addition, in order to prevent the compressor of the freezing device from operating and stopping in a short time, it is necessary to set the temperature difference between the upper limit set temperature and the lower limit set temperature of the antifreeze in the freezing tank to a certain range.

[0005] In this type of food freezing device, if the antifreeze in the freezing tank is controlled to a set temperature suitable for freezing the object (e.g., -35°C) when the freezing tank is not being used to freeze the object, the operation time of the freezing tank will be longer and more power will be consumed. However, if the antifreeze in the freezing tank is left without being cooled by the freezing tank, the temperature of the antifreeze may rise to the volatilization temperature or ignition temperature. For this reason, when the freezing tank is not being used to freeze the object, it is preferable to cool the antifreeze to a set temperature (e.g., -10°C) at which the antifreeze does not volatilize. When the set temperature of the antifreeze in the freezing tank is set high, e.g., -10°C, the temperature of the antifreeze in the freezing tank drops quickly, whereas when the set temperature of the antifreeze in the freezing tank is set low, e.g., -35°C, the temperature of the antifreeze in the freezing tank drops slowly, and the temperature drop rate differs depending on the temperature of the antifreeze.

[0006] Therefore, when the set temperature of the antifreeze in the freezing tank is different, if the addition value for setting the upper limit set temperature of the antifreeze in the freezing tank and the subtraction value for setting the lower limit set temperature are constant, the operation time of the compressor of the refrigeration device may be excessively long or short. In particular, the antifreeze in the freezing tank tends to decrease in temperature slowly near -35°C, and if the lower limit set temperature for stopping the compressor of the refrigeration device is set using the same subtraction value as when the set temperature is -10°C, even if the temperature of the antifreeze is -35°C, which is a temperature that can sufficiently freeze the object to be frozen, the antifreeze in the freezing tank is difficult to cool to the lower limit set temperature, and the compressor of the refrigeration device may operate for a long time or continuously, which requires a lot of power consumption. The object of the present invention is to control the antifreeze in the freezing tank to the optimum upper limit set temperature and lower limit set temperature according to the set temperature of the antifreeze when the antifreeze in the freezing tank is controlled to be within the temperature range between the upper limit set temperature and the lower limit set temperature by the refrigeration device. [Means for solving the problem]

[0007] In order to solve the above problems, the present invention provides a liquid freezing device comprising a freezing tank which freezes an object to be frozen using an antifreeze stored therein, a refrigeration device which cools the antifreeze by circulating a refrigerant delivered from a compressor through an evaporator tube disposed in the freezing tank, a temperature sensor which detects the temperature of the antifreeze in the freezing tank, and a control device which controls the operation of the refrigeration device based on the temperature detected by the temperature sensor, the control device controlling the compressor of the refrigeration device to operate when the temperature detected by the temperature sensor becomes equal to or higher than an upper limit set temperature which is set by adding a predetermined addition value to the set temperature of the antifreeze in the freezing tank, and stopping the operation of the compressor of the refrigeration device when the temperature detected by the temperature sensor becomes equal to or lower than a lower limit set temperature which is set by subtracting a predetermined subtraction value from the set temperature, wherein at least one of the addition value and the subtraction value is changeable according to the set temperature.

[0008] In the liquid freezing device configured as described above, the control device operates the compressor of the refrigeration device when the temperature detected by the temperature sensor is equal to or higher than the upper limit temperature set by adding a predetermined addition value to the set temperature of the antifreeze in the freezing tank, and stops the operation of the compressor of the refrigeration device when the temperature detected by the temperature sensor is equal to or lower than the lower limit temperature set by subtracting a predetermined subtraction value from the set temperature, and at least one of the addition value and the subtraction value can be changed according to the set temperature. By changing at least one of the upper limit value and the lower limit value that set the upper limit temperature or the lower limit temperature, the compressor of the refrigeration device can be operated for an optimal operating time.

[0009] In the liquid freezing device configured as described above, a freezing operation mode is provided in which a freezing temperature suitable for freezing the antifreeze in the freezing tank is set as the set temperature, and a cold storage operation mode is provided in which a cold storage temperature higher than the freezing temperature is set as the set temperature, and it is preferable that the subtraction value when the freezing temperature is set as the set temperature is smaller than the subtraction value when the cold storage temperature is set as the set temperature. When the freezing temperature is set as the set temperature in the freezing operation mode, the operation of the compressor of the refrigeration device is stopped when the lower limit set temperature using a subtraction value smaller than the subtraction value when the cold storage temperature is set as the set temperature in the cold storage operation mode is reached, so that it is possible to make it difficult for the compressor of the refrigeration device to operate for a long time or continuously.

[0010] In the liquid freezing device configured as described above, it is preferable to make the subtraction value when the set temperature is below a predetermined temperature at which the rate of temperature drop of the antifreeze liquid in the freezing tank slows down smaller than the subtraction value when the set temperature is higher than the predetermined temperature. When the set temperature reaches a lower limit temperature that is smaller than the subtraction value when the set temperature is higher than the predetermined temperature, the operation of the compressor of the refrigeration device is stopped, making it difficult for the compressor of the refrigeration device to operate for long periods of time or continuously. [Brief description of the drawings]

[0011] [Figure 1] FIG. 1 is a perspective view of a liquid freezing device of the present invention. [Diagram 2] FIG. 2 is a longitudinal cross-sectional view of the liquid freezing apparatus taken along the front-rear direction at the center in the left-right direction. [Diagram 3] FIG. 2 is a perspective view of the door of FIG. 1 when it is opened. [Figure 4] FIG. 2 is a perspective view of the liquid freezing apparatus with the cover of the box-shaped casing portion removed. [Diagram 5] FIG. 3 is a partially enlarged cross-sectional view of the upper front part of FIG. 2. [Figure 6] 4 is a longitudinal cross-sectional view taken along the left-right direction at the center in the front-rear direction in the upper part of the liquid freezing device. FIG. [Figure 7] FIG. 2 is a schematic diagram of a liquid freezing device. [Figure 8] FIG. 3 is a partially enlarged cross-sectional view of the upper rear portion of FIG. 2. [Figure 9] 1A is a perspective view of a vertical cross section cut along the left-right direction at the rear position of the partition plate, and FIG. 1B is a perspective view of a vertical cross section of the device with the evaporator tube of FIG. [Figure 10] FIG. 5 is a perspective view of the state in which the stirring device in FIG. 4 has been removed to the upper side. [Figure 11] 1 is a perspective view of the storage basket with the mesh shelf pulled out forward. FIG. [Figure 12] 13 is an oblique view of the storage basket when the lower part of the movable frame part is rotated outward with the mesh shelf stored inside the storage basket. FIG. [Figure 13] 3 is a vertical cross-sectional view corresponding to FIG. 2 when the locking portion of the storage basket is locked to a hook at the opening of the freezing tank. FIG. [Figure 14] 13 is a perspective view showing the mesh shelf pulled out forward with the locking portion of the storage basket locked to the hook at the opening of the freezing tank. FIG. [Figure 15] FIG. 2 is a block diagram of a control device. [Figure 16] 11 is a time chart when switching from a freezing operation mode to a cold storage operation mode. [Figure 17] 11 is a time chart showing a case where a mode is switched from an energy saving mode to a normal freezing mode in a freezing operation mode. [Figure 18]11 is a time chart showing a case where the energy saving mode is switched to the normal freezing mode when the temperature sensor detects the temperature of the object to be frozen being input in the freezing operation mode. BEST MODE FOR CARRYING OUT THEINVENTION

[0012] An embodiment of the liquid freezing device of the present invention will be described below with reference to the attached drawings. The liquid freezing device 10 of the present invention is also called a liquid freezer, and uses an antifreeze liquid containing ethanol (57 wt%) to rapidly freeze food materials, food products, etc. The food materials, food products, etc. are mainly sealed in packaging bags using a vacuum packaging machine or the like, and are frozen in the liquid freezing device 10 and then frozen and stored in a freezer. As shown in Figures 1 and 2, the liquid freezing device 10 has a freezing tank 20 at the top and a machine room 12 at the bottom in a housing 11. As shown in Figures 2 and 3, a support plate 13 that supports an agitation motor 51 of an agitation device 50 (described later) is installed at the rear of the freezing tank 20, an opening 20a at the top of the freezing tank 20 is arranged on the top surface of the housing 11 except for the rear portion, and a box-shaped casing part 14 that rises upward is provided above the support plate 13 arranged on the rear upper surface of the housing 11.

[0013] As shown in Figs. 1, 2 and 4, the box-shaped casing 14 houses various devices including the stirring motor 51 of the stirring device 50 and a board 17 constituting the control device 80, which will be described later, and the box-shaped casing 14 is provided with a removable cover 15 covering the front and top. As shown in Fig. 4, the inside of the box-shaped casing 14 can be maintained by removing the cover 15 of the box-shaped casing 14. As shown in Figs. 1 and 3, the cover 15 covers the front and top of the box-shaped casing 14, and has an inclined surface 15c between the front surface 15a and the top surface 15b, which is inclined diagonally forward. An operation panel 16 is provided on the inclined surface 15c of the cover 15, and the operation panel 16 is provided with an operation section 16a using operation switches and the like for performing various operations of the liquid freezing device 10, and a display section 16b using a liquid crystal panel, lamps, and the like for displaying the temperature of the antifreeze in the freezing tank 20 and various information.

[0014] 2, 4 and 8, a partition member 18 is provided in the box-shaped casing portion 14 to separate the inside into a lower region and an upper region, an agitation motor 51 is disposed in the lower region of the box-shaped casing portion 14, and a base plate 17 is disposed in the upper region of the box-shaped casing portion 14. The base plate 17 disposed in the upper region of the box-shaped casing portion 14 is disposed away from the antifreeze cooled in the freezing tank 20, and is therefore less susceptible to the cold heat of the antifreeze in the freezing tank 20. In addition, the agitation motor 51 and part of the refrigerant piping of the refrigeration device 30 are disposed in the lower region of the box-shaped casing portion 14, and therefore the inside of the box-shaped casing portion 14 is warmed by the exhaust heat of the agitation motor 51 and the heat generated by the refrigerant passing through the refrigerant piping. A rear casing section 19 is provided at the rear of the housing 11, which houses the refrigerant piping of the refrigeration unit 30 that circulates the refrigerant from the machine room 12, which houses part of the refrigerant piping of the refrigeration unit 30, into the box-shaped casing section 14, and exhaust heat from the compressor 31 of the refrigeration unit 30 disposed in the machine room 12 is introduced into the box-shaped casing section 14 via the rear casing section 19. The base plate 17 in the box-shaped casing section 14 is not only located away from the antifreeze in the freezing tank 20, but also inside the box-shaped casing section 14, exhaust heat from the stirring motor 51 is generated and exhaust heat from the compressor 31 is introduced from the machine room 12, so that condensation is unlikely to occur on the base plate 17 at the top of the box-shaped casing section 14.

[0015] As shown in Figs. 2 and 3, the freezing tank 20 freezes the object to be frozen by the antifreeze liquid stored inside, and has a substantially rectangular parallelepiped shape with an opening 20a formed on the top surface for putting in and taking out the object to be frozen. A heat insulating material is provided on the outer peripheral surface of the freezing tank 20, and the heat of the antifreeze liquid stored in the freezing tank 20 is not easily released to the outside by the heat insulating material. As shown in Fig. 2, the freezing tank 20 has a main body 21 having a box shape with an open top and an upper side portion 22 provided on the upper side of the main body 21. As shown in Fig. 5, a mounting flange portion 21a extending outward is formed at the upper end of the main body 21, and a mounting flange portion 22a extending outward is formed at the lower end of the upper side portion 22. The mounting flange portion 22a of the upper side portion 22 is arranged so as to overlap the upper side of the mounting flange portion 21a of the main body portion 21, and a heat insulating material 23 such as a silicon sheet is interposed between the mounting flange portion 21a of the main body portion 21 and the mounting flange portion 22a of the upper side portion 22. The mounting flange portion 22a of the upper portion 22 is fixed to the mounting flange portion 21a of the main body portion 21 by rivets with the heat insulating material 23 interposed therebetween. Furthermore, the space between the mounting flange portion 21a of the main body portion 21 and the mounting flange portion 22a of the upper portion 22 is sealed by silicone caulking. Antifreeze is stored in the freezing tank 20 at a liquid level lower than the upper end of the main body portion 21, and the heat insulating material 23 makes it difficult for the cold heat of the antifreeze liquid in the main body portion 21 to be transmitted to the upper portion 22.

[0016] As shown in Fig. 2 and Fig. 3, flanges 24 are formed at the front and upper left and right sides of the freezing tank 20, and the inside of the flanges 24 forms an opening 20a on the top surface of the freezing tank 20. The flanges 24 have inclined portions 24a that incline obliquely outward from the side walls (front and left and right sides) around the upper portion 22, and horizontal portions 24b that extend outward in the horizontal direction from the upper end of the inclined portions 24a. The inclined portions 24a incline obliquely upward outward from the left and right side surfaces (left and right side surfaces of the main body 21 and the upper portion 22) that face each other in the left and right direction of the freezing tank 20. The flanges 24 have the function of receiving antifreeze that drips when the object to be frozen is lifted from the freezing tank 20, and the dripped antifreeze is guided from the flanges 24 into the freezing tank 20. The flange portion 24 has an inclined portion 24a formed therein, so that the area of ​​the horizontal portion 24b is small, and the antifreeze received by the flange portion 24 is easily returned to the freezing tank 20 by the inclined portion 24a. A heater 24c is provided below the horizontal portion 24b of the flange portion 24, and the heater 24c has the function of making it difficult for condensation to form on the upper surface of the horizontal portion 24b of the flange portion 24. The heater 24c is also provided below the box-shaped casing portion 14, so that the inside of the box-shaped casing portion 14 is warmed by the heater 24c, making it difficult for condensation to form on the substrate 17.

[0017] The inclined portions 24a on both the left and right sides of the flange portion 24 are provided with hooks 24d for supporting the lower portion of a storage cage 60 for immersing the object to be frozen in the freezing tank 20, and the storage cage 60 is supported by the hooks 24d at the opening 20a of the freezing tank 20 in a state separated from the liquid surface of the antifreeze in the freezing tank 20. Since the inclined portions 24a are inclined obliquely upward and outward from the left and right side surfaces facing each other in the left and right direction of the freezing tank 20, the hooks 24d attached to the inclined portions 24a are retreated outward from the vertical upper side of the left and right side surfaces of the freezing tank 20. Therefore, when the storage cage 60 is put in and taken out of the freezing tank 20, the storage cage 60 is unlikely to get caught on the hooks 24d. The hooks 24d are disposed at two positions spaced apart from each other in the front and rear on the inclined portions 24a on both the left and right sides. The hooks 24d disposed in the front and rear on each of the left and right inclined portions 24a may be disposed so as to be continuous from front to rear.

[0018] As shown in Figs. 1 to 3, a door (lid) 26 is provided at the opening 20a on the top surface of the freezing tank 20 so as to be freely opened and closed, and the door 26 is supported at the rear of the housing 11 so as to be rotatable about a horizontal axis. A heat insulating material is provided inside the door 26, and a packing 26a is provided on the lower surface of the door 26 to seal between the door 26 and the peripheral edge of the opening 20a of the freezing tank 20. An arm portion 27 is provided at the rear end of both the left and right sides of the door 26, which extends rearward when the door 26 is closed, and a tip portion of the arm portion 27 is supported rotatably on the side portion (side surface) 14a of the box-shaped casing portion 14. When the front portion of the door 26 is lifted to open the opening 20a of the freezing tank 20, the rear end of the door 26 is lifted by the arm portion 27, and the operation panel portion 16 provided on the box-shaped casing portion 14 is exposed from the front side. In this way, the operation section 16a and the display section 16b of the operation panel section 16 can be operated and viewed from the front side, not only when the door 26 is closed but also when it is open.

[0019] As shown in Fig. 2 and Fig. 6, a partition plate 25 is provided at the rear of the freezing tank 20, and the partition plate 25 divides the rear part of the freezing tank 20 into front and rear parts so that antifreeze liquid can pass through. As shown in Fig. 6, the partition plate 25 has a number of openings 25a through which antifreeze liquid can pass, and a passage 25b through which antifreeze liquid can pass is formed between the partition plate 25 and the bottom of the freezing tank 20. Inside the freezing tank 20, the front side of the rear part divided by the partition plate 25 is an immersion area 20b for immersing the object to be frozen in the antifreeze liquid, and the rear part of the freezing tank 20 is a cooling area 20c for cooling the antifreeze liquid. An upper limit liquid level indicator 25c for indicating the upper limit liquid level of the antifreeze liquid in the freezing tank 20 and a lower limit liquid level indicator 25d for indicating the lower limit liquid level of the antifreeze liquid in the freezing tank 20 are formed at the top of the partition plate 25. Each of these upper and lower limit liquid level indicators 25c, 25d is formed by a plurality of protrusions arranged in the left-right direction, and is disposed in a position that is easily visible from the front side of liquid freezing apparatus 10. As shown in Figures 6 and 7, a temperature sensor 28 is provided in freezing tank 20, and temperature sensor 28 detects the temperature of the antifreeze in freezing tank 20.

[0020] As shown in Fig. 2 and Fig. 7, the refrigeration device 30 includes an evaporator tube 34 that is spirally wound in the cooling region 20c, and the antifreeze in the freezing tank 20 is cooled by the refrigerant passing through the evaporator tube 34. As shown in Fig. 7, the refrigeration device 30 includes a compressor 31 that compresses the refrigerant, a condenser 32 that cools and liquefies the refrigerant pumped from the compressor 31, an expansion valve 33 that expands the liquefied refrigerant liquefied by the condenser 32 to produce a low-pressure liquefied refrigerant, and an evaporator tube 34 that vaporizes the liquefied refrigerant expanded by the expansion valve 33 to cool the antifreeze in the freezing tank 20. The refrigeration device 30 includes a refrigeration circuit in which the refrigerant circulates by connecting the compressor 31, the condenser 32, the expansion valve 33, and the evaporator tube 34 in a ring shape by a refrigerant tube. When the refrigerant in the refrigeration device 30 is circulated, the refrigerant pumped from the compressor 31 is cooled in the condenser 32 to become a liquefied refrigerant, and the liquefied refrigerant becomes a low-pressure liquefied refrigerant in the expansion valve 33. The low-pressure liquefied refrigerant cools the antifreeze in the freezing tank 20 by the heat of vaporization when it evaporates in the evaporator tube 34.

[0021] As shown in Fig. 7, the compressor 31 is provided with an overload relay 31a, which stops the compressor 31 in the event of an abnormality such as when the refrigerant liquid temperature is high or when an overcurrent flows. The refrigeration device 30 is provided with a pressure equalizing valve 35 in parallel with the compressor 31, which is used to eliminate the pressure difference between the refrigerant suction side and discharge side of the compressor 31 by opening the pressure equalizing valve 35. In addition, a discharge side temperature sensor 36 is provided on the refrigerant discharge side of the compressor 31, which detects the temperature of the refrigerant discharged from the compressor 31.

[0022] As shown in Figs. 2, 8 and 9, in the cooling area 20c of the freezing tank 20, an agitator blade 57 of the agitator 50 is disposed inside the spirally wound evaporator tube 34, and the antifreeze in the freezing tank 20 is agitated by the rotation of the agitator blade 57 of the agitator 50. As shown in Figs. 4 and 8, the agitator 50 is provided with an agitator motor 51 on the upper side of the support plate 13 installed at the rear of the freezing tank 20, and the agitator motor 51 is detachably fixed to the support plate 13 via a mounting plate 52. The agitator motor 51 is capable of changing the rotation speed, and by changing the rotation speed, the strength of the liquid flow of the antifreeze in the freezing tank 20 can be changed. As shown in Fig. 8, a spacer 53 using a heat insulating material made of a resin material is provided between the agitator motor 51 and the mounting plate 52, and the spacer 53 prevents the transfer of cold heat from the antifreeze in the freezing tank 20 to the agitator motor 51 via the support plate 13 and the mounting plate 52. In addition, a cylindrical insulator 54 and a fixed plate 55 are provided on the underside of the mounting plate 52, and the insulator 54 prevents the transfer of cold heat from the antifreeze in the freezing tank 20 to the mounting plate 52.

[0023] 2, 8 and 9, the rotating shaft 56 of the stirring motor 51 hangs down inside the evaporation tube 34 wound in a spiral shape in the freezing tank 20, and a stirring blade 57 is provided at the tip of the rotating shaft 56. When the rotating shaft 56 is rotated by the stirring motor 51, the stirring blade 57 at the tip of the rotating shaft 56 rotates inside the spiral evaporation tube 34 in the freezing tank 20. By rotating the stirring blade 57, the antifreeze liquid in the cooling region 20c is cooled as it passes inside the spiral evaporation tube 34, and the cooled antifreeze liquid is sent out through the bottom of the evaporation tube 34, and the sent antifreeze liquid flows through the passage 25b between the lower end of the partition plate 25 and the bottom wall of the freezing tank 20 to the immersion region 20b side. The antifreeze liquid delivered to the immersion area 20b flows from the opening 25a of the partition plate 25 toward the cooling area 20c, and the antifreeze liquid delivered to the cooling area 20c flows into the inside from the upper side of the spiral evaporator pipe 34. In this way, the antifreeze liquid in the freezing tank 20 is cooled by the evaporator pipe 34 as it circulates between the immersion area 20b and the cooling area 20c.

[0024] As shown in FIG. 2, FIG. 8 and FIG. 9, an air entrainment prevention plate 58 is provided on the upper side of the agitating blade 57 to prevent air from being entrained in the agitating blade 57. The air entrainment prevention plate 58 suppresses the generation of a vortex on the upper side of the agitating blade 57 when the agitating blade 57 is rotated, prevents air from being entrained in the agitating blade 57, and prevents the temperature of the antifreeze in the freezing tank 20 from increasing due to the entrained air. In this embodiment, the air entrainment prevention plate 58 includes two air entrainment prevention plates 58a and 58b, and the upper air entrainment prevention plate 58a is attached to the top of the partition plate 25, and the lower air entrainment prevention plate 58b is fitted and fixed to the rotating shaft 56. The upper air entrainment prevention plate 58a is formed with a cutout portion 58c that opens to the rear side and through which the rotating shaft 56 is inserted, and the rotating shaft 56 is inserted into the cutout portion 58c. The upper air entrainment prevention plate 58a is larger than the agitating blade 57 when viewed from above, making it difficult for air to be entrained into the agitating blade 57. The lower air entrainment prevention plate 58b is made of a circular resin member, and its center is fitted onto the rotating shaft 56 between the upper air entrainment prevention plate 58a and the agitating blade 57. Since the two air entrainment prevention plates 58a, 58b that prevent air entrainment are provided above the agitating blade 57, air is unlikely to be entrained into the agitating blade 57 when it rotates.

[0025] As shown in Figures 2, 8 and 9, a guide section 59 is provided at the bottom of the freezing tank 20 to guide the antifreeze in the cooling area 20c to the immersion area 20b. The guide section 59 is an inclined plate that is inclined downward from the cooling area 20c to the front side, which is the immersion area 20b side, below the stirring blade 57, and guides the antifreeze flowing downward by the stirring blade 57 inside the spirally wound evaporation tube 34 to the immersion area 20b through the passage 25b below the partition plate 25. In addition, a shielding section 59a that rises upward is provided on both the left and right sides of the guide section 59, and the shielding section 59a makes it difficult for the antifreeze flowing downward by the stirring blade 57 to flow in the left-right direction, which is perpendicular to the horizontal direction in which the immersion area 20b and the cooling area 20c are arranged. The shielding portion 59a makes it difficult for the antifreeze liquid in the freezing tank 20 to flow in the left-right direction from the inside of the spirally wound evaporation tube 34, and prevents the occurrence of a short cycle in which the antifreeze liquid flowing inside the evaporation tube 34 rises between the left-right outside of the evaporation tube 34 and the left and right side surfaces of the freezing tank 20 and flows back inside the evaporation tube 34, circulating in a narrow range inside and outside the evaporation tube 34. In this way, since the guide portion 59 for guiding the antifreeze liquid in the cooling region 20c to the immersion region 20b is provided at the bottom of the freezing tank 20, the antifreeze liquid in the freezing tank 20 circulates between the cooling region 20c and the immersion region 20b, and the object to be frozen immersed in the immersion region 20b is cooled by the antifreeze liquid cooled in the cooling region 20c.

[0026] All parts of the agitator 50, including the agitator motor 51, are fixed to a mounting plate 52, and the mounting plate 52 is removably fixed to the support plate 13 with screws. As shown in Fig. 10, when performing maintenance on the agitator 50, the cover 15 of the box-shaped casing portion 14 is removed to open the inside of the box-shaped casing portion 14, and after removing the screws that secure the mounting plate 52, the agitator 50 can be removed for maintenance by lifting up the agitator motor 51 together with the mounting plate 52.

[0027] The liquid freezing device 10 includes a storage basket 60 for storing food ingredients, food to be cooked, and other objects to be frozen and immersing them in the freezing tank 20. As shown in Fig. 11, the storage basket 60 is made by bending and bonding a plurality of wires (metal wires), and includes substantially rectangular front and rear frame parts 61, 62 spaced apart from each other at the front and rear, first to third connecting bars 63-65 connecting the front and rear frame parts 61, 62 while spaced apart, and a wire shelf 69 for arranging the objects to be frozen in multiple tiers up and down inside the storage basket 60. An opening 61a is formed inside the front frame part 61 because the first to third connecting bars 63-65 are not arranged, and the objects to be frozen can enter and leave the storage basket 60 through the opening 61a of the front frame part 61.

[0028] The front and rear frame parts 61, 62 are arranged at positions spaced apart from each other in the front-rear direction, and three first connecting bars 63 are provided between the front and rear frame parts 61, 62. The first connecting bars 63 are substantially U-shaped with the front side open, and connect the upper and lower parts of the front and rear frame parts 61, 62. Four second connecting bars 64 are provided between the front and rear frame parts 61, 62. The second connecting bars 64 are substantially L-shaped extending forward from the lower end extending vertically of the rear frame part 62 to the front frame part 61 side, and connect the lower parts of the front and rear frame parts 61, 62. The first and second connecting bars 63 and 64 are arranged alternately in the left-right direction. The first connecting bars 63 are arranged on the upper side, rear side, and lower side between the front and rear frame parts 61, 62, and have the function of preventing the frozen object in the storage basket 60 from escaping from the upper side, rear side, and lower side. The second connecting bar 64 is disposed on the rear and lower sides between the front and rear frame parts 61, 62, and has the function of preventing the frozen objects in the storage basket 60 from escaping from the rear and lower sides. Furthermore, an auxiliary bar 66 extending left and right is provided in the middle part in the vertical direction of the rear frame part 62, and the auxiliary bar 66 has the function of preventing the rear frame part 62 from bending left and right, and also prevents the frozen objects stored in the storage basket 60 from escaping from the rear side.

[0029] Third connecting bars 65 (65a, 65c) are provided at the top and bottom between the left and right side portions of the front and rear frame portions 61, 62. The upper third connecting bar 65a is generally U-shaped and opens downward and protrudes upward from the front and rear frame portions 61, 62. A support bar 65b extending in the front-rear direction is provided at the middle portion of the upper third connecting bar 65a in the up-down direction, and a movable frame portion 70 (described later) is supported on the support bar 65b so as to be rotatable about a horizontal axis in the front-rear direction. The upper third connecting bar 65a functions as a stopper for stopping the rotation of the lower portion of the movable frame portion 70, which is supported so as to be rotatable about a horizontal axis in the front-rear direction, at an angle at which it can be engaged with the hook 24d of the freezing tank 20. The lower third connecting bar 65c is generally U-shaped and opens inward and protrudes downward from the front and rear frame portions 61, 62. A leg 65d is provided at the bottom of the lower third connecting bar 65c, and the storage basket 60 is installed so as to be spaced apart from the installation surface by the leg 65d. Two support posts 67 are provided spaced apart in the front-rear direction on the support bar 65b of the upper third connecting bar 65a and the lower third connecting bar 65c, and these support posts 67 have the function of preventing the support bar 65b of the upper third connecting bar 65a from bending downward.

[0030] A pair of left and right support rails 68 supporting the mesh shelf 69 are provided on both left and right sides (both sides in the width direction of the storage basket 60) of the front and rear frame parts 61, 62, and in this embodiment, the support rails 68 are arranged in three tiers, one above the other, on both left and right sides of the front and rear frame parts 61, 62. The support rails 68 extend in the depth direction (front-rear direction) perpendicular to the width direction and horizontal direction of the storage basket 60, and include a lower rail 68a supporting the lower side of the left and right ends of the mesh shelf 69, and an upper rail 68b covering the upper side of the left and right ends of the mesh shelf 69. The lower rail 68a extends in the front-rear direction between the front frame part 61 and the rear frame part 62 while being curved inward of the storage basket 60, and is fixed to the front frame part 61 and the rear frame part 62. The upper rail 68b extends front-to-rear between the front support pillars 67 and the rear frame portion 62 while curving inwardly of the storage basket 60, and is fixed to the support pillars 67 and the rear frame portion 62. The upper rail 68b has the function of restricting the wire shelf 69 from moving upward when the frozen objects placed on the lower wire shelf 69 tend to float up in the antifreeze. The lower and upper rails 68a, 68b are positioned inwardly of the support pillars 67 in the width direction of the storage basket 60.

[0031] The wire shelf 69 is for arranging the objects to be frozen in multiple levels in the storage basket 60, and can be inserted and removed from the opening 61a at the front side of the storage basket 60. The wire shelf 69 is provided with a substantially rectangular shelf frame 69a, a loading bar 69b that extends in the front-rear direction inside the shelf frame 69a and places the objects to be frozen on it, and guides 69c provided on both sides in the width direction on the upper side of the shelf frame 69a. The outer diameter of the shelf frame 69a in the width direction is slightly smaller than the inner diameter of the front frame 61 in the width direction, and the wire shelf 69 can be inserted and removed from the storage basket 60 through the opening 61a. The width direction end of the shelf frame 69a of the wire shelf 69 is supported between the lower and upper rails 68a and 68b that constitute the support rail 68 so as to be slidable in the front-rear direction. The guides 69c extend along the depth direction of the storage cage 60, slightly inside the widthwise ends on both sides of the shelf frame portion 69a, and have the function of preventing the mesh shelf 69 from moving at an inclination to the left or right between the lower and upper rails 68a, 68b by engaging with the inner part of the storage cage 60 on the upper rail 68b when the mesh shelf 69 is slidably moved in the front-to-rear direction between the lower and upper rails 68a, 68b. The guides 69c allow the mesh shelf 69 to slide in the front-to-rear direction between the lower and upper rails 68a, 68b without shifting in the left-to-right direction, so that it does not get caught on the outer support portions 67 of the support rails 68.

[0032] As shown in Figs. 11 and 12, a substantially rectangular movable frame portion 70 is provided on both the left and right sides of the storage cage 60, and the movable frame portion 70 is supported by a support bar 65b provided on an upper third connecting bar 65a that connects the upper parts of both the left and right sides of the front and rear frame portions 61, 62 to be rotatable about a horizontal axis in the front-rear direction. An attachment shaft portion 70a extending forward and backward is provided at the upper portion of the movable frame portion 70 at a position below the upper end, and the movable frame portion 70 is supported by the attachment shaft portion 70a to be rotatable about the axis in the front-rear direction on the support bar 65b. The movable frame portion 70 has a handle portion 70b above the attachment shaft portion 70a, and the handle portion 70b is substantially U-shaped with the bottom side opening. The handle portion 70b of the movable frame portion 70 is used to hold the storage cage 60, and the storage cage 60 is inserted into and removed from the freezing tank 20 by holding the handle portion 70b. The movable frame portion 70 has a locking portion 70c extending forward and backward at its lower end, and the locking portion 70c is supported so as to be rotatable outward from the left and right sides of the front and rear frame portions 61, 62. When the locking portion 70c at the lower portion of the movable frame portion 70 is rotated outward from the left and right sides of the front and rear frame portions 61, 62, the locking portion 70c can be locked with a hook 24d provided at the opening 20a of the freezing tank 20. The rear side of the locking portion 70c is inclined obliquely upward, and with the locking portion 70c locked with the hook 24d provided at the opening 20a of the freezing tank 20, the storage basket 60 is supported at the opening 20a of the freezing tank 20 so that its rear side is tilted downward.

[0033] 11, when handle portion 70b above mounting shaft portion 70a stands upright, the portion below mounting shaft portion 70a hangs down along the left and right sides of front and rear frame portions 61, 62. In this state, the left and right movable frame portions 70 are fitted inside the left and right side surfaces of freezing tank 20, and storage basket 60 can be placed in freezing tank 20 and immersed in antifreeze. When the storage basket 60 is lifted above the opening 20a of the freezing tank 20, the handle portions 70b of the left and right movable frame portions 70 are moved toward each other until they engage with the upper third connecting bar 65c which acts as a stopper. This causes the locking portions 70c below the mounting shaft portion 70a to rotate outward so as to move away from the left and right sides of the front and rear frame portions 61, 62, and the locking portions 70c can be locked with hooks 24d provided on the opening 20a of the freezing tank 20.

[0034] As shown in Fig. 13, when the storage cage 60 is moved downward from above the opening 20a of the freezing tank 20, the locking portion 70c of the movable frame portion 70 is locked to the hook 24d provided at the opening 20a of the freezing tank 20. When the locking portion 70c of the movable frame portion 70 is locked to the hook 24d provided at the opening 20a of the freezing tank 20, the storage cage 60 is supported at the opening 20a above the liquid level of the freezing liquid in the freezing tank 20, and the antifreeze adhering to the storage cage 60 and the object to be frozen falls from the opening 20a into the freezing tank 20. As shown in Figs. 13 and 14, since the rear side of the locking portion 70c is inclined obliquely upward, when the locking portion 70c is locked to the hook 24d of the opening 20a, the rear side of the storage cage 60 is inclined downward at the opening 20a of the freezing tank 20, and the antifreeze adhering to the storage cage 60 and the object to be frozen is easily drained off. After the antifreeze adhering to the storage basket 60 and the objects to be frozen has fallen into the freezing tank 20, the mesh shelf 69 can be pulled forward as shown in FIG. 14 and the objects to be frozen can be removed from the storage basket 60.

[0035] 15, the liquid freezing device 10 includes a control device 80, which is connected to the operation panel unit 16, the temperature sensor 28, the refrigeration device 30, and the stirring motor 51. The control device 80 has a microcomputer (not shown), which includes a CPU, non-volatile memories (non-volatile storage units) such as RAM, ROM, and EEPROM, and a timer (all not shown), which are connected via a bus.

[0036] The ROM stores a program for a freezing operation mode in which the antifreeze in the freezing tank 20 is cooled to a freezing temperature suitable for freezing the object to be frozen, a cold storage operation mode in which the antifreeze in the freezing tank 20 is cooled to a cold storage temperature suitable for storing, and a maintenance operation mode in which the antifreeze in the freezing tank 20 is raised to a discharge temperature suitable for discharging. The programs for each mode can be executed by operating the operation unit 16a provided on the operation panel unit 16. In addition, by operating the operation unit 16a provided on the operation panel unit 16, it is also possible to control the operation so that the freezing operation mode and the cold storage operation mode are switched and executed at every set time by a timer. When the freezing operation mode, the cold storage operation mode, or the maintenance operation mode is executed, the nonvolatile memory stores the executed mode. Even if the power supply of the liquid freezing device 10 is turned off, the nonvolatile memory stores the executed mode, and the stored mode can be executed when the power supply of the liquid freezing device 10 is turned on.

[0037] A communication terminal 81 is connected to the control device 80, and the control device 80 can communicate with the Internet I, such as an external cloud, via the communication terminal 81. The Internet I, such as the cloud, can be communicated with from a terminal device P, such as an external personal computer or smartphone, and the terminal device P can be connected to the Internet and the control device 80 can be remotely operated via the communication terminal 81. By remotely operating the control device 80 from the terminal device P, it is possible to select a freezing operation mode, a cold storage operation mode or a maintenance operation mode and perform operations such as execution, execution stop or execution reservation at a location away from the installation site where the liquid freezing device 10 is installed.

[0038] In this liquid freezing device 10, the set temperature of the antifreeze in the freezing tank 20 is set independently for the freezing operation mode and the cold storage operation mode. In the freezing operation mode, the set temperature of the antifreeze in the freezing tank 20 is set to a freezing temperature suitable for freezing the object to be frozen, and in this embodiment, the set freezing temperature is set to -35°C as an example of a temperature that can quickly freeze the object to be frozen. In contrast, in the cold storage operation mode, the set temperature of the antifreeze in the freezing tank 20 is set to a cold storage temperature that is higher than the freezing temperature and suitable for storing the antifreeze, and in this embodiment, the cold storage temperature is set to -10°C as an example of a temperature lower than the volatilization temperature and ignition temperature of the antifreeze.

[0039] When controlling the cooling of the antifreeze in the freezing tank 20 to a set temperature, the control device 80 controls the compressor 31 of the refrigeration device 30 to operate when the temperature detected by the temperature sensor 28 is equal to or higher than the upper limit set temperature set by adding a predetermined addition value to the set temperature, and controls the compressor 31 of the refrigeration device 30 to stop operating when the temperature detected by the temperature sensor 28 is equal to or lower than the lower limit set temperature set by subtracting a predetermined subtraction value from the set temperature. The antifreeze in the freezing tank 20 tends to decrease in temperature as the temperature decreases. For this reason, if the addition and subtraction values ​​for setting the upper limit and lower limit temperatures are the same for all set temperatures when controlling the cooling of the antifreeze in the freezing tank 20 to a set temperature, the operation time of the compressor 31 of the refrigeration device 30 may be extended or the compressor 31 may repeatedly turn on and off in a short time.

[0040] When controlling the antifreeze in freezing tank 20 to a set temperature of -10°C in the cold storage operation mode, the temperature of the antifreeze in freezing tank 20 drops relatively quickly, and the addition value for setting the upper limit set temperature and the subtraction value for setting the lower limit set temperature are each set to 2°C. The upper limit set temperature in the cold storage operation mode is set to -8°C obtained by adding an addition value of 2°C to the set temperature of -10°C, and the lower limit set temperature in the cold storage operation mode is set to -12°C obtained by subtracting a subtraction value of 2°C from the set temperature of -10°C, and in the cold storage operation mode, the temperature of the antifreeze in freezing tank 20 is controlled to be within a range of ±2°C of the set temperature of -10°C.

[0041] In contrast, when controlling the antifreeze in the freezing tank 20 to a set temperature of -35°C in the freezing operation mode, the rate of decrease in the temperature of the antifreeze in the freezing tank 20 tends to be low. Even if the antifreeze is cooled to a temperature lower than -35°C, the temperature of the antifreeze is difficult to decrease below -35°C, and even if the lower limit temperature is set to a subtraction value of 2°C in the freezing operation mode as in the above-mentioned cold storage operation mode, the antifreeze in the freezing tank 20 is difficult to decrease to the lower limit temperature, and there is a risk that the compressor 31 of the refrigeration device 30 will operate for a long time. For this reason, when controlling the antifreeze in the freezing tank 20 to a set temperature of -35°C in the freezing operation mode, the addition value for setting the upper limit temperature is set to 2°C, and the subtraction value for setting the lower limit temperature is set to 1°C, which is lower than in the cold storage operation mode. Even when the set temperature in the freezing tank 20 is as low as -35°C, when the antifreeze in the freezing tank 20 is cooled by the refrigeration device 30, the refrigeration device 30 will not operate continuously or for a long time.

[0042] Next, the control in the freezing operation mode will be described. In the freezing operation mode, the antifreeze in the freezing tank 20 is cooled to a freezing temperature suitable for freezing the object to be frozen. As shown in FIG. 16, in the freezing operation mode, the control device 80 controls the operation of the refrigeration device 30 based on the temperature detected by the temperature sensor 28 so that the antifreeze in the freezing tank 20 has a freezing temperature suitable for freezing the object to be frozen, while the stirring motor 51 of the stirring device 50 is operated. As described above, the control device 80 controls the refrigeration device 30 to operate when the temperature sensor 28 detects the upper limit set temperature of the freezing temperature, and controls the refrigeration device 30 to stop operating when the temperature sensor 28 detects the lower limit set temperature of the freezing temperature, and the antifreeze in the freezing tank 20 is controlled to be in the temperature range between the upper limit set temperature and the lower limit set temperature, with the freezing temperature being the set temperature.

[0043] Furthermore, when the freezing operation mode is being executed, the control device 80 controls the agitation motor 51 of the agitation device 50 to rotate at a high rotation speed (3,000 rpm in this embodiment, shown as high speed in the figure) so that the objects to be frozen immersed in the antifreeze liquid in the freezing tank 20 can be frozen as quickly as possible. The objects to be frozen immersed in the antifreeze liquid in the freezing tank 20 are cooled by heat exchange with the antifreeze liquid that is cooled by the liquid flow when the agitation motor 51 is rotated at a high rotation speed.

[0044] Even when the freezing operation mode is being performed, when the object to be frozen is not immersed in the freezing tank 20, the antifreeze in the freezing tank 20 is not cooled by heat exchange with the object to be frozen, so there is no need to rotate the stirring motor 51 of the stirring device 50 at a high rotation speed. In the freezing operation mode, an energy-saving mode before the object to be frozen is immersed is set in addition to the normal freezing mode when freezing the object to be frozen, and when the energy-saving mode of the freezing operation mode is being performed, the control device 80 controls the stirring motor 51 to rotate at a low rotation speed (600 rpm in this embodiment, shown as low speed in the figure) even when the freezing operation mode is being performed. In this embodiment, the freezing mode and the energy-saving mode can be switched by appropriately operating the operation unit 16a of the operation panel unit 16.

[0045] As shown in Fig. 17, when the energy saving mode is selected in the freezing operation mode, the control device 80 controls the stirring motor 51 to rotate at a low rotation speed. When the object to be frozen is immersed in the antifreeze liquid in the freezing tank 20 and frozen, the control device 80 controls the stirring motor 51 to rotate at a high rotation speed when the operation unit 16a is operated to switch to the normal freezing mode. The object to be frozen immersed in the antifreeze liquid in the freezing tank 20 is cooled by heat exchange with the antifreeze liquid cooled by the liquid flow when the stirring motor 51 is rotated at a high rotation speed. After the object to be frozen is frozen, the control device 80 controls the stirring motor 51 to rotate at a low rotation speed when the operation unit 16a is operated to switch to the energy saving mode.

[0046] Also, the freezing operation mode may be switched from the energy saving mode to the normal freezing mode based on the temperature detected by the temperature sensor 28. As shown at the timing a in Fig. 18, when an object to be frozen is put into the antifreeze solution in the freezing tank 20, the temperature of the antifreeze solution begins to rise rapidly, and as shown at the timing b in Fig. 18, when the temperature sensor 28 detects the temperature at which the object to be frozen is put in when the object is immersed in the antifreeze solution in the freezing tank 20 (set to -30°C in this embodiment), the mode is switched from the energy saving mode to the normal freezing mode, and the stirring motor 51 is controlled to rotate at a high rotation speed (3,000 rpm in this embodiment). In this way, when the object to be frozen is not immersed in the antifreeze liquid in the freezing tank 20, the rotation speed of the stirring motor 51 of the stirring device 50 can be controlled to be low, thereby keeping the power consumption low when the stirring motor 51 of the stirring device 50 is operated, and when the object to be frozen is immersed in the antifreeze liquid in the freezing tank 20, the rotation speed of the stirring motor 51 of the stirring device 50 can be controlled to be high, thereby quickly freezing the object to be frozen immersed in the antifreeze liquid in the freezing tank 20.

[0047] In addition, when the freezing operation mode is being executed, the control device 80 may control the stirring motor 51 to rotate at a normal high rotation speed (3,000 rpm in this embodiment) until the temperature sensor 28 detects the temperature at which the object to be frozen is introduced when the object is immersed in the antifreeze in the freezing tank 20, and then control the stirring motor 51 to rotate at an even higher rotation speed (for example, 4,000 rpm in this embodiment) when the temperature sensor 28 detects the temperature at which the object to be frozen is introduced when the object is immersed in the antifreeze in the freezing tank 20. In this way, when the object to be frozen is immersed in the antifreeze in the freezing tank 20, the rotation speed of the stirring motor 51 of the stirring device 50 is controlled to be higher than the normal rotation speed, so that the object to be frozen immersed in the antifreeze in the freezing tank 20 can be frozen even more quickly.

[0048] Next, the control in the cold storage operation mode will be described. In the cold storage operation mode, the antifreeze in the freezing tank 20 is cooled to a cold storage temperature that is higher than the freezing temperature and suitable for storage, and the antifreeze in the freezing tank 20 is cooled so that it does not rise to a high temperature such as a volatilization temperature. Even in the cold storage operation mode, the control device 80 controls the operation of the refrigeration device 30 based on the temperature detected by the temperature sensor 28 so that the antifreeze in the freezing tank 20 is at a cold storage temperature suitable for storage, with the stirring motor 51 of the stirring device 50 in operation. As described above, the control device 80 controls the refrigeration device 30 to operate when the temperature sensor 28 detects the upper limit set temperature of the cold storage temperature, and controls the operation of the refrigeration device 30 to stop when the temperature sensor 28 detects the lower limit set temperature of the cold storage temperature, and the antifreeze in the freezing tank 20 is controlled to be in the temperature range between the upper limit set temperature and the lower limit set temperature, which is the cold storage temperature set temperature.

[0049] Since the cold storage operation mode is not intended to freeze the object to be frozen in the freezing tank 20, the control device 80 controls the agitation motor 51 of the agitation device 50 to rotate at a lower rotation speed (600 rpm in this embodiment) than the high rotation speed described above. In this way, the control device 80 controls the rotation speed of the agitation motor 51 of the agitation device 50 to be lower in the cold storage operation mode than when the freezing operation mode is being executed, and the power consumption when the agitation motor 51 of the agitation device 50 is operated can be kept low.

[0050] Next, the control in the maintenance operation mode will be described. In the maintenance operation mode, the antifreeze in the freezing tank 20 is raised to a discharge temperature suitable for discharge, and the temperature is not raised to a temperature at which the antifreeze in the freezing tank 20 will not freeze the tools used for discharge. In the maintenance operation mode, the control device 80 controls the stirring motor 51 of the stirring device 50 to rotate at a speed (3,000 rpm in this embodiment) without cooling by the refrigeration device 30. When the stirring motor 51 of the stirring device 50 is operated, the antifreeze in the freezing tank 20 is stirred and air is easily mixed in, and the temperature of the antifreeze in the freezing tank 20 is easily increased by the mixed air. The temperature of the antifreeze in the freezing tank 20 gradually rises, and when the temperature sensor 28 detects a temperature of 0°C or higher, which is set as the discharge temperature, the control device 80 controls the stirring motor 51 to stop operating. In addition, when the temperature detected by the temperature sensor 28 reaches 10°C or higher, the control device 80 preferably controls the refrigeration device 30 to operate and also controls the agitation motor 51 of the agitation device 50 to rotate, so as to prevent the antifreeze in the freezing tank 20 from reaching or exceeding its volatilization temperature or ignition temperature.

[0051] When the object to be frozen is frozen by this liquid freezing device 10, the operation unit 16a is operated to cause the control device 80 to execute the freezing operation mode. When the freezing operation mode is executed, the antifreeze liquid in the freezing tank 20 is cooled as it flows downward inside the spirally wound evaporation tube 34 in the cooling region 20c by the liquid flow generated by the rotation of the stirring blade 57 of the stirring device 50. The antifreeze liquid flowing downward inside the evaporation tube 34 is sent to the immersion region 20b through the passage 25b on the lower side of the partition plate 25 by the guide unit 59. The antifreeze liquid sent from the cooling region 20c to the immersion region 20b returns to the cooling region 20c from the opening 25a of the partition plate 25, and the antifreeze liquid returned to the cooling region 20c flows from the upper side of the spirally wound evaporation tube 34 to the inside and is cooled as it flows inside the evaporation tube 34.

[0052] When the storage cage 60 containing the objects to be frozen is immersed in the cooled antifreeze liquid in the immersion area 20b, the objects to be frozen in the storage cage 60 are cooled by heat exchange with the antifreeze liquid that circulates between the cooling area 20c and the immersion area 20b. After the time required to freeze the objects to be frozen has elapsed, the handles 70b are grasped to lift the storage cage 60 in the freezing tank 20 up to the upper side of the freezing tank 20, and the left and right handles 70b are moved in directions approaching each other (towards the inside of the storage cage 60), and the locking parts 70c at the bottom of the movable frame 70 rotate outward and can be locked by hooks 24d provided at the opening 20a of the freezing tank 20. When the storage cage 60 is moved downward from the upper side of the freezing tank 20, the locking portion 70c at the lower part of the movable frame portion 70 is locked with the hook 24d provided at the opening 20a of the freezing tank 20, and the storage cage 60 is supported by the opening 20a of the freezing tank 20. The antifreeze adhering to the storage cage 60 and the objects to be frozen in the storage cage 60 falls to the lower side, and the falling antifreeze is received in the freezing tank 20. After the antifreeze adhering to the storage cage 60 and the objects to be frozen in the storage cage 60 has been drained off, the frozen objects in the storage cage 60 are moved to a freezer for storage.

[0053] The liquid freezing device 10 configured as above includes a freezing tank 20 that freezes an object to be frozen with antifreeze stored therein, a refrigeration device 30 that cools the antifreeze by circulating a refrigerant sent from a compressor to an evaporation tube 34 disposed in the freezing tank 20, a temperature sensor 28 that detects the temperature of the antifreeze in the freezing tank 20, and a control device 80 that controls the operation of the refrigeration device 30 based on the detected temperature of the temperature sensor 28. In this liquid freezing device 10, the control device 80 controls the compressor 31 of the refrigeration device 30 to operate when the detected temperature of the temperature sensor 28 is equal to or higher than an upper limit set temperature set by adding a predetermined addition value to the set temperature of the antifreeze in the freezing tank 20, and to stop the operation of the compressor 31 of the refrigeration device 30 when the detected temperature of the temperature sensor 28 is equal to or higher than a lower limit set temperature set by subtracting a predetermined subtraction value from the set temperature.

[0054] In this liquid freezing device 10, a freezing operation mode is set to a freezing temperature suitable for freezing the antifreeze in the freezing tank 20, and a cold storage operation mode is set to a cold storage temperature higher than the freezing temperature suitable for storing the antifreeze. In this embodiment, the set temperature in the freezing operation mode is set to -35°C as a freezing temperature suitable for freezing the antifreeze, and the set temperature in the cold storage operation mode is set to -10°C as a cold storage temperature higher than the freezing temperature suitable for storing the antifreeze. The cooling speed of the antifreeze used in this liquid freezing device 10 tends to be fast in the temperature range around -10°C, which is the cold storage temperature, but slow in the temperature range around -35°C, which is the freezing temperature.

[0055] In this liquid freezing device 10, if the addition value for setting the upper limit temperature and the subtraction value for setting the lower limit temperature are the same for each of the freezing temperature and the cold storage temperature, the compressor 31 of the refrigeration device 30 may operate for a long time or continuously, or may repeatedly start and stop in a short time. For example, when the addition value and the subtraction value are set to 2°C in the cold storage operation mode to prevent the compressor 31 of the refrigeration device 30 from repeatedly starting and stopping in a short time, if the addition value and the subtraction value in the freezing operation mode are set to 2°C as in the cold storage operation mode, the temperature of the antifreeze in the freezing tank 20 will decrease in speed after it drops below -35°C, and the temperature of the antifreeze in the freezing tank 20 will not easily drop to the set lower limit temperature, and the compressor 31 of the refrigeration device 30 may operate for a long time or continuously.

[0056] On the other hand, when the addition value is set to 2°C and the subtraction value is set to 1°C in order to prevent the compressor 31 of the refrigeration device 30 from operating for a long time or continuously in the freezing operation mode, if the addition value and subtraction value in the cold storage operation mode are set to 2°C and 1°C as in the freezing operation mode, the temperature width (temperature range) between the upper limit temperature and the lower limit temperature of the set temperature becomes narrow, and the refrigeration device 30 may repeatedly start and stop operating in a short time. For this reason, in this liquid refrigeration device 10, at least one of the addition value for setting the upper limit temperature and the subtraction value for setting the lower limit temperature can be changed according to the set temperature. In this embodiment, the subtraction value in the cold storage operation mode is set to 2°C, while the subtraction value in the freezing operation mode is set to 1°C, so that it is possible to prevent the compressor 31 of the refrigeration device 30 from repeatedly starting and stopping in a short time in the cold storage operation mode or from operating for a long time or continuously in the freezing operation mode, and it becomes possible to operate the compressor 31 of the refrigeration device 30 at an optimal operating time.

[0057] As described above, the temperature of the antifreeze in the freezing tank 20 tends to decrease at a rate of decrease in the vicinity of -35°C. The subtraction value when the freezing temperature is set as the set temperature is smaller than the subtraction value when the cold storage temperature is set as the set temperature, so that the compressor 31 of the refrigeration device 30 can be prevented from repeatedly operating and stopping in a short period of time in the cold storage operation mode, or from operating for a long period of time or continuously in the freezing operation mode, and the compressor 31 of the refrigeration device 30 can be operated for an optimal operating time. In particular, the subtraction value when the set temperature is below -35°C as the predetermined temperature at which the rate of decrease in the temperature of the antifreeze in the freezing tank 20 decreases is set smaller than the subtraction value when the set temperature is higher than the predetermined temperature of -35°C, and by making the subtraction value smaller near or below the temperature at which the rate of decrease in the temperature of the antifreeze is particularly slow, the compressor 31 of the refrigeration device 30 can be reliably prevented from operating for a long period of time or continuously. In this embodiment, the subtraction value is 1° C. in the freezing operation mode and 2° C. in the cold storage operation mode, but it is not limited to this and at least one of the addition value and the subtraction value may be changed to another temperature depending on the set temperature. In this case, it is preferable to make the subtraction value when the freezing temperature is the set temperature smaller than the subtraction value when the cold storage temperature is the set temperature.

[0058] In this liquid freezing device 10, when attempting to cool uncooled room temperature antifreeze from the freezing device 30, such as when replacing the antifreeze in the freezing tank 20, the overload relay 31a of the compressor 31 may be activated and the compressor 31 may stop. In this case, the overload relay 31a automatically returns to normal, but if the pressure difference between the suction side and the discharge side of the compressor 31 is large, the compressor 31 cannot be started again. In this case, the pressure difference between the suction side and the discharge side of the compressor 31 can be eliminated by opening the pressure equalizing valve 35 provided in parallel with the compressor 31, but since it is not possible to directly detect that the overload relay 31a has been activated and the compressor 31 has stopped, there is a risk that the pressure equalizing valve 35 cannot be controlled to open.

[0059] For this reason, the temperature detected by the discharge side temperature sensor 36 while the compressor 31 of the refrigeration device 30 is operated to cool the antifreeze in the freezing tank 20 is stored over time as a threshold value for determining whether the compressor 31 has been stopped by the overload relay 31a. If the temperature does not fall below the previously stored threshold value even though the compressor 31 is operated under the control of the control device 80, the control device 80 determines that the overload relay 31a is operating, and controls the pressure equalizing valve 35 to open for a fixed time of 10 seconds. When the pressure difference between the suction side and the discharge side of the compressor 31 is eliminated, the overload relay 31a automatically returns to normal, and the refrigerant pumped from the compressor 31 begins to circulate again. The control device 80 repeatedly executes the above-mentioned control until the temperature of the antifreeze in the freezing tank 20 drops to a temperature that does not place an excessive load on the compressor 31, and the antifreeze in the freezing tank 20 drops to a temperature that does not place an excessive load on the compressor 31.

[0060] In the above-described embodiment, the various set temperatures such as the concentration of antifreeze, the freezing temperature of antifreeze, the cold storage temperature, the discharge temperature, the addition value of the set upper limit temperature, the subtraction value of the set lower limit temperature, and the rotation speed of the stirring motor 51 are only examples and are not limited to those described above. [Explanation of symbols]

[0061] 10...liquid freezing device, 20...freezing tank, 28...temperature sensor, 30...refrigeration device, 31...compressor, 34...evaporation tube, 80...control device.

Claims

1. a freezing tank for freezing objects by antifreeze stored therein; a refrigeration device that cools an antifreeze solution by circulating a refrigerant delivered from a compressor through an evaporator tube disposed in the freezing tank; a temperature sensor for detecting a temperature of the antifreeze solution in the freezing tank; a control device for controlling an operation of the refrigeration device based on a temperature detected by the temperature sensor, The control device controls the liquid freezing device so as to operate a compressor of the refrigeration device when the temperature detected by the temperature sensor becomes equal to or higher than an upper limit set temperature set by adding a predetermined addition value to a set temperature of the antifreeze liquid in the freezing tank, and to stop the operation of the compressor of the refrigeration device when the temperature detected by the temperature sensor becomes equal to or lower than a lower limit set temperature set by subtracting a predetermined subtraction value from the set temperature, A liquid freezing device, characterized in that at least one of the additional value and the subtraction value is changeable in accordance with the set temperature.

2. 2. The liquid freezing device according to claim 1, a freezing operation mode in which a freezing temperature suitable for freezing the antifreeze in the freezing tank is set as a set temperature, and a cold storage operation mode in which a cold storage temperature higher than the freezing temperature and suitable for storing the antifreeze is set as a set temperature, A liquid freezing device characterized in that the subtraction value when the freezing temperature is set to a set temperature is smaller than the subtraction value when the cold storage temperature is set to a set temperature.

3. The liquid freezing device according to claim 1 or 2, A liquid freezing device characterized in that the subtraction value when the set temperature is below a predetermined temperature at which the rate of temperature decrease of the antifreeze liquid in the freezing tank slows down is made smaller than the subtraction value when the set temperature is higher than the predetermined temperature.

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