Refrigeration device

Abstract

[Problem] To provide a refrigeration device that freezes an object to be cooled by bringing the object into contact with a cooling liquid, and that is capable of easily detecting the state of the cooling liquid in real time. [Solution] A refrigeration device (1) comprises: a cooling tank (3) in which a cooling liquid (L) is stored; a temperature sensor for detecting the temperature of the cooling liquid (L); and a specific gravity detecting device (40). The specific gravity detecting device (40) comprises: a guide shaft (41); float members (50A to 50C) capable of moving along the guide shaft (41); and a limit switch (44) for detecting floating or sinking of each of the float members (50A to 50C). An upper limit value detection float member (50A) has a specific gravity equal to an upper limit value of the specific gravity of the cooling liquid (L), a control standard value float member (50B) has a specific gravity equal to a control standard value of the specific gravity of the cooling liquid (L), and a lower limit value detection float member (50C) has a specific gravity equal to a lower limit value of the specific gravity of the cooling liquid (L).

Description

Refrigeration equipment

[0001] The present invention relates to a liquid freezing type refrigeration device for quickly freezing food or other objects to be cooled, and in particular to an improvement that enables appropriate maintenance and management of the condition of the cooling liquid used in the refrigeration device.

[0002] Known refrigeration devices (freezers) for rapidly freezing food or other objects include air-cooled devices that blow cold air into a cooling chamber in which the object is placed, and liquid-freezing devices that immerse the object in a low-temperature liquid (coolant). While air-cooled refrigeration devices have traditionally been the norm, liquid-freezing devices, which can achieve higher quality freezing more quickly, have recently been attracting attention. For example, Patent Document 1 proposes an invention in which the cooling efficiency of a liquid-freezing device is improved by moving the object up and down in the coolant.

[0003] Patent No. 6668563

[0004] In liquid-freezing refrigeration systems, the composition (brine concentration) of the coolant (brine) is constantly changing due to factors such as the evaporation of brine components and the condensation of moisture in the air. This change in composition affects the performance of the refrigeration system. For example, when an alcohol-based solution (e.g., an ethanol-based solution) is used as the coolant, a decrease in the alcohol concentration in the solution leads to a decrease in performance due to an increase in the solution's viscosity. In the worst case, the solution may no longer be able to function as a liquid heat transfer medium, potentially causing the refrigeration system to malfunction or break down. On the other hand, if the alcohol concentration in the solution increases beyond a specified limit, the solution becomes a hazardous material under the Fire Service Act, which limits the amount that can be stored and requires special safety management. Therefore, the coolant requires maintenance (regular checks) to maintain its proper composition.

[0005] Conventionally, such coolant maintenance management has been performed by first sampling the coolant from a refrigeration unit, leaving or heating the sampled coolant until the temperature reaches or exceeds freezing, measuring the temperature of the sampled coolant, measuring the composition (brine concentration) of the coolant using various measuring devices (e.g., hydrometer, refractometer, vibratory density meter), and adjusting the brine concentration of the coolant in the refrigeration unit based on the measurement results. Thus, conventional methods of coolant maintenance management require numerous complex steps, which are time-consuming and labor-intensive. Furthermore, due to the time lag between sampling the coolant and actually measuring its composition, accurate management based on real-time measurements is not possible. Furthermore, various devices are required for measuring the composition, which increases maintenance costs.

[0006] The present invention has been made in response to these problems, and aims to provide a refrigeration device that freezes objects by bringing them into contact with a coolant, and that can easily detect the state of the coolant in real time.

[0007] The present invention relates to a refrigeration device that freezes an object to be cooled by bringing it into contact with a cooling liquid, and includes a cooling tank in which the cooling liquid is stored, a temperature sensor that detects the temperature of the cooling liquid, and a specific gravity detection device installed in the cooling tank, wherein the specific gravity detection device includes a float member having a predetermined specific gravity, a holding means that holds the float member so that it can move in a floating or sinking direction, and a detection means that detects the floating or sinking of the float member.

[0008] The specific gravity detecting device may include, as the float member, an upper limit detection float member having a specific gravity equal to an upper limit of the specific gravity of the coolant at a reference temperature of the coolant.

[0009] The upper limit value may be a specific gravity at which the coolant begins to solidify at the reference temperature.

[0010] The freezing machine of the present invention may further include an emergency stop means for stopping operation of the freezing device when the specific gravity detection device detects that the specific gravity of the cooling liquid has exceeded an upper limit value.

[0011] The specific gravity detecting device may include, as the float member, a control reference value detecting float member having a specific gravity equal to the control reference value of the specific gravity of the coolant at the reference temperature of the coolant.

[0012] The specific gravity detecting device may include, as the float member, a float member for detecting a lower limit value, which has a specific gravity equal to a lower limit value of the specific gravity of the coolant at a reference temperature of the coolant.

[0013] The freezing machine of the present invention may further include a stirring means for stirring the cooling liquid in the cooling tank.

[0014] According to the present invention, a refrigeration system (e.g., refrigeration system 1) includes a specific gravity detector (e.g., specific gravity detector 40), which includes a float member (e.g., float members 50A-50C) having a predetermined specific gravity and a detector (e.g., limit switch 44) for detecting the floating or sinking of the float member. Therefore, by setting the specific gravity of the float member equal to a reference value for detecting the state of the coolant, the detector can easily detect the current state of the coolant, such as its composition (e.g., the ethanol concentration in an ethanol aqueous solution), in real time. This allows for timely and accurate responses to changes in the state of the coolant, thereby maintaining the properties (e.g., viscosity) of the coolant in an appropriate state and improving the performance of the refrigeration system. Furthermore, continuous, constant monitoring of the state of the coolant can be performed extremely easily and automatically, without the need for processes such as collecting the coolant from a cooling tank (e.g., cooling tank 3) or heating the coolant. This significantly reduces the effort and time required for refrigeration system maintenance and management. Furthermore, the specific gravity detection device has a simple configuration and can be provided at low cost, which reduces the cost required for maintaining and managing the refrigeration device.

[0015] By providing an upper limit detection float element (e.g., upper limit detection float element 50A) having a specific gravity equal to the upper limit of the specific gravity of the coolant, it is possible to detect in real time when the specific gravity of the coolant exceeds the upper limit, and appropriate measures can be taken promptly.

[0016] If the upper limit value is set to the specific gravity at which the coolant begins to solidify, the possibility of the coolant solidifying can be detected quickly, and the coolant can be appropriately prevented from solidifying.

[0017] By providing an emergency stop means (e.g., control device 9) that stops the operation of the refrigeration device when it is detected that the specific gravity of the cooling liquid has exceeded the upper limit, it is possible to prevent the refrigeration device from continuing to operate when the cooling liquid has solidified, thereby appropriately preventing malfunction or failure of the refrigeration device.

[0018] By providing a float element for detecting the control standard value (e.g., float element 50B for detecting the control standard value) having a specific gravity equal to the control standard value of the specific gravity of the coolant, it is possible to perform detailed maintenance management according to various needs by appropriately setting the control standard value.

[0019] By providing a float member for detecting a lower limit value (e.g., float member for detecting a lower limit value 50C) having a specific gravity equal to the lower limit value of the specific gravity of the coolant, it is possible to detect in real time that the specific gravity of the coolant has fallen below the lower limit value, and appropriate measures can be taken promptly.

[0020] If a stirring means (e.g., stirring unit 23) is provided to stir the coolant in the cooling tank, the state of the coolant in the cooling tank can be kept uniform throughout the tank, minimizing variations in the specific gravity of the coolant depending on the detection location within the cooling tank and improving measurement accuracy. Therefore, accurate specific gravity detection can be performed even with a single specific gravity detection device.

[0021] Fig. 1 is a front view showing a refrigeration device in an embodiment of the present invention. Fig. 2 is a front view showing the refrigeration device, showing a state in which a storage unit is immersed in a cooling liquid. Fig. 3 is a perspective view showing a storage unit. Fig. 4 is a plan view showing an agitation unit. Fig. 5 is a front view showing a specific gravity detection device. Fig. 6 is a diagram showing the relationship between temperature, ethanol concentration, and specific gravity in an ethanol aqueous solution.

[0022] An embodiment of the present invention will now be described with reference to the accompanying drawings. Figures 1 and 2 show a refrigeration system 1 according to the embodiment of the present invention. As shown in the figures, the refrigeration system 1 includes a base 2 that serves as a platform for supporting various components of the refrigeration system 1, a cooling tank 3 provided within the base 2, cooling pipes 4 arranged within the cooling tank 3, a refrigerant supply unit 5 that supplies a refrigerant (primary refrigerant) to the cooling pipes 4, a storage unit 6 capable of storing objects to be cooled, a vertical drive mechanism 7 that drives the storage unit 6 up and down, an elevation mechanism 8 that drives the vertical drive mechanism 7 up and down, a control device (control panel) 9 that controls the operation of each component of the refrigeration system 1, a temperature sensor (not shown) that detects the temperature of the cooling liquid L in the cooling tank 3, and a specific gravity detection device 40 that detects the specific gravity of the cooling liquid L in the cooling tank 3.

[0023] 1 shows the storage unit 6 waiting above the cooling tank 3, and Fig. 2 shows the storage unit 6 lowered into the cooling tank 3 and immersed in the cooling liquid L. In Figs. 1 and 2, only the cooling tank 3 portion of the base 2 is shown in partial cross section.

[0024] The cooling tank 3 is a tank for cooling items to be cooled (items to be frozen), such as food, and includes a storage section 3A for storing cooling liquid L. The top of the cooling tank 3 (storage section 3A) has an opening 3B for loading and unloading a storage unit 6. As shown in Figure 2, when a storage unit 6 is loaded into the cooling tank 3, the opening 3B is closed by a lid 11 that descends along with the storage unit 6. This keeps the contents of the storage section 3A of the cooling tank 3 cold.

[0025] The cooling liquid (brine) is a refrigerant for cooling the object to be cooled. As the cooling liquid, for example, an alcohol aqueous solution (e.g., an ethanol aqueous solution) or saline solution, or other liquid that does not freeze at the set temperature (reference temperature) for cooling the object to be cooled, can be used. In this embodiment, an ethanol aqueous solution is used as the cooling liquid.

[0026] The temperature of the coolant (ethanol aqueous solution) is detected by a temperature sensor and controlled to a predetermined reference temperature (for example, approximately −35° C.). The composition of the coolant (the mixture ratio of water to ethanol in the ethanol aqueous solution (ethanol concentration)) is adjusted to a predetermined ratio. In this embodiment, the composition of the coolant is controlled based on the detection of the specific gravity of the coolant by the specific gravity detection device 40, which will be described in detail later.

[0027] The cooling pipe 4 is a heat exchanger for cooling the cooling liquid L in the cooling tank 3, and is made up of a pipe through which the refrigerant flows (in this embodiment, a coil-shaped pipe surrounding the storage unit 6). The refrigerant supply unit 5 is configured to introduce the refrigerant into the cooling pipe 4 and includes refrigerant pipes (refrigerant gas pipe 5A and refrigerant liquid pipe 5B) and various valves (solenoid valves, not shown, etc.).

[0028] The storage unit 6 is a storage shelf in which objects to be cooled are stored, and includes a frame 21 that forms an outer frame, a plurality of loading trays 22 arranged within the frame 21, and an agitation unit 23 that is arranged at the lower end of the frame 21. As will be described in detail later, the agitation unit 23 constitutes agitation means for agitating the cooling liquid L in the cooling tank 3 in the refrigeration device 1.

[0029] The vertical drive mechanism 7 includes a housing 12, a drive means (e.g., an electromagnetic motor, not shown) disposed within the housing 12, and a support arm 13 linked to the drive means. The support arm 13 supports the frame 21 of the storage unit 6 from above. As a result, the drive means causes the support arm 13 to move up and down (extend and retract), thereby moving the storage unit 6 up and down. The stroke and speed of the vertical movement of the storage unit 6 are appropriately controlled by the control device 9.

[0030] Note that Figure 1 shows a state in which the support arm 13 does not extend from the housing 12 and the storage unit 6 is on the upper side of the vertical movement, and Figure 2 shows a state in which the support arm 13 extends downward from the housing 12 and the storage unit 6 is on the lower side of the vertical movement.

[0031] During the freezing process of the object to be cooled, the storage unit 6 repeatedly moves up and down at a stroke and speed appropriately controlled by the control device 9. Therefore, the object to be cooled held in the storage unit 6 is not simply immersed in the cooling liquid, but is also moved up and down in the cooling liquid, which increases the fluidity of the cooling liquid around the object to be cooled, thereby accelerating the cooling speed of the object to be cooled.

[0032] The lifting mechanism 8 includes a vertically long housing 14 attached to the base 2, a lifting drive mechanism (e.g., a power cylinder, not shown) provided within the housing 14, and a support arm 15 linked to the lifting drive mechanism. The support arm 15 is connected to the housing 12 of the vertical drive mechanism 7 and supports the housing 12 from the side. With this configuration, as the vertical drive mechanism 7 is driven by the lifting drive mechanism to move up and down, the storage unit 6 also moves up and down, allowing it to move from the upper standby position shown in Figure 1 to the cooling position in the cooling tank 3 shown in Figure 2.

[0033] In addition, the lid 11 of the cooling tank 3 is attached integrally to the underside of the support arm 15 (or the housing 12 of the up-down drive mechanism 7), and when the storage unit 6 moves into the cooling tank 3, the lid 11 also descends to close the opening 3B of the cooling tank 3.

[0034] The specific gravity detector 40 is placed in a predetermined position in the cooling tank 3 (in this embodiment, near the side surface of the cooling tank 3) while being housed in a protective cage 19. The protective cage 19 has, for example, a lattice-shaped outer wall surface, which allows the coolant L to freely enter the protective cage 19 while preventing foreign matter from entering the protective cage 19, thereby protecting the specific gravity detector 40. Details of the specific gravity detector 40 will be described later with reference to FIG. 5.

[0035] FIG. 3 shows the storage unit 6 in detail. As shown, in the storage unit 6, multiple identically shaped loading trays 22 are stacked within a frame 21. Each loading tray 22 has a substantially rectangular bottom 22A and wall sections 22B at the front and rear of the bottom 22A. The bottom 22A serves as the loading section on which the object to be cooled is placed. The bottom 22A is made of a mesh-like material (e.g., wire mesh), allowing the coolant to flow through the mesh. The upper portion of the storage unit 6 is an open section 24 that allows the coolant to flow freely in both the vertical and horizontal directions within the storage unit 6.

[0036] The front and rear walls 22B serve as walls that close the front and rear of the storage unit 6 (loading tray 22). Also, side walls 25 that close the left and right sides of the storage unit 6 are provided on the left and right sides of the storage unit 6. This prevents almost no coolant from flowing into the storage unit 6 from the sides.

[0037] 4 shows the stirring unit 23 in detail. As shown in the figure, the stirring unit 23 includes a substantially rectangular outer frame 31 and a plurality of opening and closing flaps 32 arranged in parallel within the outer frame 31. Each opening and closing flap 32 is an elongated plate-shaped (blade-shaped) member and is rotatably supported on the outer frame 31 around a rotation shaft 33. As a result, the opening and closing flaps 32 are arranged substantially horizontally and can be opened and closed between a closed position that prohibits the flow of coolant and an open position that rotates downward and allows the flow of coolant between adjacent opening and closing flaps 32.

[0038] With this configuration, as the storage unit 6 moves up and down during the cooling process, the cooling liquid in the cooling tank 3 is stirred by the stirring unit 23. To explain in more detail, when the storage unit 6 is raised, the opening and closing flap 32 of the stirring unit 23 is set to the open position by water pressure from above, allowing the cooling liquid to flow up and down through the storage unit 6.

[0039] On the other hand, when the storage unit 6 is lowered, the opening / closing flap 32 is closed by water pressure from below. As a result, the coolant below the storage unit 6 (agitation unit 23) is pushed downward as the storage unit 6 is lowered, rises from the bottom to the side of the cooling tank 3, and flows back to the upper side of the storage unit 6. As a result, the coolant in the cooling tank 3 is appropriately agitated.

[0040] 5 shows the specific gravity detection device 40 in detail. As shown in the figure, the specific gravity detection device 40 includes a guide shaft 41, which is an elongated cylindrical shaft member, and three float members (floating members), namely, an upper limit value detection float member 50A, a control reference value detection float member 50B, and a lower limit value detection float member 50C.

[0041] The guide shaft 41 extends vertically through the three float members 50A to 50C, and the float members 50A to 50C are held so as to be able to move up and down along the guide shaft 41. When the specific gravity detection device 40 is installed in the cooling tank 3, the guide shaft 41 is arranged to extend in the up-down direction (vertical direction). The float members 50A to 50C are arranged so that they are entirely immersed in the coolant L (see FIGS. 1 and 2).

[0042] The guide shaft 41 is provided with upper stoppers 42 and lower stoppers 43, which are arranged above and below each of the float members 50A to 50C. The upper stoppers 42 and lower stoppers 43 have a disk shape with a central hole, and are fixed at predetermined positions on the outer circumferential surface of the guide shaft 41, with the guide shaft 41 passing through the central hole. As a result, the movement range of the float members 50A to 50C is limited between the upper stoppers 42 and lower stoppers 43.

[0043] The hollow portion of the guide shaft 41 accommodates three limit switches 44 corresponding to the float members 50A to 50C, and lead wires 45 that electrically connect each limit switch 44 to the control device 9 and an alarm device (not shown). The guide shaft 41 is sealed at its lower end 41A to prevent coolant from flowing into the hollow portion.

[0044] The limit switches 44 are detection means for detecting the floating or sinking (up and down movement) of the corresponding float members 50A to 50C, and are disposed adjacent to the corresponding float members 50A to 50C. The detection signal from the limit switches 44 is transmitted via lead wires 45 to the control device 9 and an alarm device (not shown).

[0045] The alarm device is a device that notifies the detection result by the limit switch 44 by voice (alarm, etc.) or various visual displays (lamp lighting, screen display, etc.), and is composed of, for example, a speaker, lamp, monitor, etc.

[0046] The float members 50A to 50C have a similar structure made up of the same components (the only difference being that each has its own specific gravity, as will be described later). As shown representatively in Figure 5 with float member 50C, each of the float members 50A to 50C comprises a hollow outer shell 51, a sleeve 52 attached to the outer shell 51, and a magnet 53 and a weight 54 attached to the sleeve 52.

[0047] The sleeve 52 is a cylindrical member that is fixed to the outer shell portion 51 so as to vertically penetrate the center of the outer shell portion 51, while being slidably fitted onto the guide shaft 41. This allows the float members 50A to 50C to move along the guide shaft 41. A sealed space 55 is formed between the outer shell portion 51 and the sleeve 52, and a predetermined gas is sealed within this space 55.

[0048] The magnet 53 is a component used in combination with the limit switch 44 to turn the limit switch 44 on and off, and is attached at a predetermined position on the outer periphery of the sleeve 52. When the float members 50A to 50C float up and down and move along the guide shaft 41, the position of the magnet 53 relative to the limit switch 44 fixed to the guide shaft 41 changes, and the limit switch 44 turns on and off according to the positional relationship between the limit switch 44 and the magnet 53. This allows the limit switch 44 to detect the floating and sinking of the float members 50A to 50C.

[0049] The weight 54 is a member for adjusting the weight of the float members 50A to 50C, and is attached at a predetermined position on the outer periphery of the sleeve 52. The specific gravity of each of the float members 50A to 50C is determined by its weight (the total weight of all components, i.e., the outer shell 51, the sleeve 52, the magnet 53, the weight 54, and the gas sealed in the space 55) relative to its volume (the volume defined by the outer shell 51 and the sleeve 52), but by setting the weight 54 of each of the float members 50A to 50C to an appropriate weight, it can be adjusted to a specific value.

[0050] The specific gravity of each float member 50A-50C is set to a value equal to a specific gravity value (reference specific gravity value) that serves as a judgment standard for detecting the state of the coolant. In this embodiment, the reference specific gravity values ​​for managing the specific gravity of the coolant are an upper specific gravity value (a reference specific gravity value that is the upper limit of the range that the specific gravity of the coolant must satisfy), a control reference value (a reference specific gravity value that is the standard for managing the specific gravity of the coolant), and a lower specific gravity limit (a reference specific gravity value that is the lower limit of the range that the specific gravity of the coolant must satisfy). The upper limit detection float member 50A is assigned a specific gravity equal to the upper limit, the control reference value detection float member 50B is assigned a specific gravity equal to the control reference value, and the lower limit detection float member 50C is assigned a specific gravity equal to the lower limit. With this configuration, by detecting the floating or sinking of each float member 50A-50C in the coolant, it is possible to detect in real time how the specific gravity of the coolant in the cooling tank 3 is related to each reference specific gravity value.

[0051] As shown in FIG. 6 , there is a certain relationship between the specific gravity of the coolant (ethanol aqueous solution) and its composition (ethanol concentration). That is, since the specific gravity of ethanol is smaller than the specific gravity of water (=1), as the ethanol concentration decreases, the specific gravity of the ethanol aqueous solution increases, and as the ethanol concentration increases, the specific gravity of the ethanol aqueous solution decreases. Therefore, the composition of the coolant can be determined based on the specific gravity of the coolant. Therefore, based on the specific gravity of the coolant, a treatment for improving the composition of the coolant can be selected, and the composition of the coolant can be adjusted so that the performance (e.g., viscosity) of the coolant is maintained at an appropriate level.

[0052] As shown in Fig. 6, for a given ethanol concentration, the specific gravity of an aqueous ethanol solution increases as the temperature decreases. Therefore, each reference specific gravity value is set as a value at a predetermined reference temperature (the temperature at which the coolant is set when the refrigeration device 1 is in use). In Fig. 6, the boundaries corresponding to each reference specific gravity value (upper limit, control reference value, lower limit) are indicated by thick lines.

[0053] Next, we will explain specific examples of setting each standard specific gravity value and details of coolant maintenance management based on each standard specific gravity value. The upper limit is the standard specific gravity value that is the upper limit of the range that the coolant's specific gravity must satisfy. At a temperature of -35°C, an ethanol solution begins to solidify at an ethanol concentration of 45 wt% and a specific gravity of 0.96. Therefore, in this embodiment, the upper limit is set to 0.96 to appropriately prevent the coolant from solidifying.

[0054] When the specific gravity of the coolant is lower than the upper limit (=0.96), the upper limit detection float member 50A sinks to a position where it contacts the lower stopper 43. In this state, the limit switch 44 is turned off, and it is detected that the specific gravity of the coolant is normal and lower than the upper limit.

[0055] On the other hand, when the specific gravity of the coolant exceeds the upper limit (=0.96), the upper limit detection float member 50A floats to a position where it comes into contact with the upper stopper 42. This turns on the limit switch 44, and it is detected that the specific gravity of the coolant has exceeded the upper limit, resulting in an inappropriate state.

[0056] If it is detected that the specific gravity of the coolant has exceeded the upper limit, in order to prevent the coolant from freezing, the control device 9 will make an emergency stop of the operation of the refrigeration device 1. This prevents the refrigeration device 1 from breaking down if the refrigeration device 1 continues to operate in a state where the coolant has frozen (for example, by moving the storage unit 6 up and down in frozen coolant).

[0057] The alarm device also issues an alarm to notify the operator of the refrigeration system 1 of the risk of the coolant freezing and to take appropriate measures to replenish the coolant with ethanol.

[0058] The control reference value is a reference specific gravity value that serves as a standard for controlling the specific gravity of the coolant. As described above, the refrigeration system 1 is controlled so that the coolant temperature is at a reference temperature of −35°C. However, considering actual use of the refrigeration system 1, the temperature of the heat exchanger (cooling pipe 4) needs to be approximately −40°C in order to maintain the coolant temperature in the cooling tank 3 at −35°C. Therefore, in order to reliably avoid freezing of the coolant and ensure safe and stable use of the refrigeration system 1, it is desirable to maintain a certain margin, for example, by controlling the specific gravity of the ethanol aqueous solution to 0.95 or less (ethanol concentration of 52 wt% or more). Therefore, in this embodiment, the control reference value for the specific gravity of the coolant is set to 0.95.

[0059] When the specific gravity of the coolant is lower than the control reference value (=0.95), the float member 50B for detecting the control reference value is in a submerged state. In this state, the limit switch 44 corresponding to the float member 50B for detecting the control reference value is off, and it is detected that the specific gravity of the coolant is normal and lower than the control reference value.

[0060] On the other hand, when the specific gravity of the coolant exceeds the control standard value (=0.95), the float member 50B for detecting the control standard value becomes floating and the limit switch 44 turns on, detecting that the specific gravity of the coolant has exceeded the control standard value.

[0061] When it is detected that the specific gravity of the coolant has exceeded the control standard value, the alarm device notifies the operator (manager) that the ethanol concentration in the coolant is decreasing and that ethanol needs to be replenished (for example, by emitting an alarm sound). This allows the operator (manager) of the refrigeration system 1 to know the decrease in the ethanol concentration in the coolant in real time, and allows the coolant to be replenished with ethanol at the appropriate time.

[0062] By setting appropriate control standards in this way, the condition of the coolant can be managed more precisely, and appropriate measures can be taken at an earlier stage, thereby maintaining high quality of the coolant performance (e.g., viscosity).

[0063] The lower limit is a reference specific gravity value that is the lower limit of the range that the specific gravity of the coolant must satisfy. If the ethanol concentration in the ethanol aqueous solution becomes too high, various dangers increase during handling. In particular, if the ethanol concentration exceeds 60 wt%, it becomes a hazardous material under the Fire Service Act, which increases the burden of handling and management. Here, referring to FIG. 6, when the temperature of the ethanol aqueous solution is −35°C and the ethanol concentration is 60 wt%, the specific gravity is 0.9334. Therefore, in this embodiment, the lower limit of the specific gravity of the coolant is set to 0.94.

[0064] When the specific gravity of the coolant is greater than the lower limit (0.94), the float member 50C for detecting the lower limit floats. In this state, the limit switch 44 is off, and it is detected that the specific gravity of the coolant is normal and greater than the lower limit.

[0065] On the other hand, when the specific gravity of the coolant falls below the lower limit (0.94), the float member 50C sinks, turning on the limit switch 44 and detecting that the specific gravity of the coolant has fallen below the lower limit.

[0066] When it is detected that the specific gravity of the coolant is lower than the lower limit, the alarm device notifies the user that the ethanol concentration in the coolant is too high (for example, by sounding an alarm). As a result, the operator (manager) of the refrigeration system 1 can be notified of the increase in the ethanol concentration in the coolant in real time, and can replenish the aqueous ethanol solution with water at the appropriate time.

[0067] In this way, maintenance and management of the coolant condition (composition) can be performed appropriately based on the detection of the floating / sinking of the float members 50A to 50C. The floating / sinking of the float members 50A to 50C depending on the coolant condition can be summarized as follows: First, when the coolant is in a normal condition, the float members 50A and 50B are in a submerged state, and the float member 50C is in a floating state.

[0068] On the other hand, if the specific gravity of the coolant increases and exceeds the control standard value (when ethanol needs to be replenished), the float member 50B for detecting the control standard value will first float, so the float member 50A will sink and the float members 50B and 50C will float. If the specific gravity of the coolant increases further and exceeds the upper limit value (when there is a risk of the coolant freezing), the float member 50A for detecting the upper limit will also float, so all of the float members 50A to 50C will float.

[0069] On the other hand, if the specific gravity of the coolant falls below the lower limit (if the ethanol concentration of the ethanol aqueous solution becomes so high that it is classified as a dangerous substance), the float member 50C for detecting the lower limit will also sink, and all of the float members 50A to 50C will be in a sinking state.

[0070] As described above, the refrigeration system 1 of this embodiment is provided with a specific gravity detection device 40 having an upper limit value detection float member 50A, a control standard value detection float member 50B, and a lower limit value detection float member 50C, and the floating and sinking of the float members 50A to 50C is detected by a limit switch 44. This makes it possible to detect in real time whether the state (composition) of the coolant (brine) is normal, and enables quick and appropriate action to be taken in response to changes in the state of the coolant.

[0071] Furthermore, the condition of the coolant can be easily monitored based on detection by the specific gravity detection device 40. Furthermore, the process from specific gravity detection by the specific gravity detection device 40 to notification by the notification device can be automated, so continuous, automated monitoring of the condition of the coolant can be achieved. Therefore, the effort and time required to detect the condition of the coolant can be significantly reduced.

[0072] Furthermore, the specific gravity detection device 40 has a simple configuration and can be provided at low cost, which significantly reduces the cost of managing the state of the coolant.

[0073] Furthermore, if the upper limit detection float member 50A detects that the specific gravity of the coolant has exceeded a predetermined upper limit, the operation of the refrigeration device 1 is stopped immediately, thereby preventing malfunction or failure of the refrigeration device 1 caused by the refrigeration device 1 continuing to operate with the coolant frozen.

[0074] Furthermore, since the refrigeration system 1 is provided with stirring means (stirring unit 23) for stirring the coolant in the cooling tank 3, the state of the coolant in the cooling tank 3 is kept uniform throughout the cooling tank 3. Therefore, when detecting specific gravity using the specific gravity detecting device 40, variation depending on the detection location within the cooling tank 3 can be minimized, improving measurement accuracy. Furthermore, accurate specific gravity detection can be performed even with a single specific gravity detecting device 40.

[0075] Although the embodiments of the present invention have been described above, the present invention is not limited to the above embodiments and can be modified as appropriate within the scope of the claims. For example, in the above embodiment, a specific gravity detection device 40 is provided with three float members 50A to 50C, but the present invention is not limited to this configuration. The number of float members provided in the specific gravity detection device and the specific gravity (reference specific gravity value) of each float member can be set arbitrarily depending on the required management content.

[0076] For example, the float element in the specific gravity detector may be the float element 50B for detecting the control standard value, allowing for minimal and simple control. Alternatively, two float elements, an upper limit float element 50A and a lower limit float element 50C, may be used to detect only whether the coolant is within an upper or lower range. Furthermore, four or more float elements may be provided for even more detailed control.

[0077] Furthermore, in the above embodiment, a configuration in which a single specific gravity detection device 40 is provided in the refrigeration device 1 is exemplified, but the present invention is not limited to such a configuration, and the accuracy of specific gravity detection may be further improved by arranging multiple specific gravity detection devices 40 at various locations in the cooling tank 3.

[0078] In the above embodiment, the agitation unit 23 is used as the agitation means for the coolant, but the present invention is not limited to this. Any agitation means may be used, such as an agitation device that agitates the coolant with a propeller that rotates around an axis.

[0079] INDUSTRIAL APPLICABILITY The present invention can be used to appropriately manage the state of a cooling liquid in a refrigeration device for quickly freezing an object to be cooled, such as food.

[0080] DESCRIPTION OF SYMBOLS 1 Refrigeration device 2 Base 3 Cooling tank 3A Storage section 3B Opening 4 Cooling pipe (heat exchanger) 5 Refrigerant supply section 6 Storage unit 7 Up / down drive mechanism 8 Lifting mechanism 9 Control device 21 Frame of storage unit 22 Loading tray 22A Bottom surface of loading tray 22B Wall of loading tray 23 Stirring unit 24 Opening section 25 Side wall of storage unit 31 Outer frame of stirring unit 32 Opening / closing flap 33 Rotating shaft 40 Specific gravity detection device 41 Guide shaft 42 Upper stopper 43 Lower stopper 44 Limit switch 45 Lead wire 50A Float member for detecting upper limit value 50B Float member for detecting control standard value 50C Float member for detecting lower limit value 51 Outer shell 52 Sleeve 53 Magnet 54 Weight 55 Space part

Claims

1. A refrigeration system that freezes an object to be cooled by bringing it into contact with a cooling liquid, comprising: a cooling tank in which the cooling liquid is stored; a temperature sensor that detects the temperature of the cooling liquid in the cooling tank; and a specific gravity detection device installed in the cooling tank to measure the specific gravity of the cooling liquid in the cooling tank, wherein the specific gravity detection device comprises: a float member having a predetermined specific gravity; holding means that holds the float member movable in a floating / sinking direction within the cooling tank; and detection means that detects the position of the float member in the floating / sinking direction.

2. A refrigeration system as described in claim 1, wherein the specific gravity detection device is provided with an upper limit detection float member having a specific gravity equal to the upper limit of the specific gravity of the cooling liquid at the reference temperature of the cooling liquid.

3. The refrigeration device according to claim 2, wherein the upper limit value is the specific gravity at which the cooling liquid begins to solidify at the reference temperature.

4. A refrigeration system according to claim 3, further comprising an emergency stop means for stopping operation of said refrigeration system when said specific gravity detection device detects that the specific gravity of said cooling liquid has exceeded said upper limit value.

5. A refrigeration system as described in claim 1, wherein the specific gravity detection device is provided with a float member for detecting a control reference value, the float member having a specific gravity equal to the control reference value of the specific gravity of the cooling liquid at the reference temperature of the cooling liquid.

6. A refrigeration system as described in claim 1, wherein the specific gravity detection device is provided with a float member for detecting a lower limit value, the float member having a specific gravity equal to the lower limit value of the specific gravity of the cooling liquid at the reference temperature of the cooling liquid.

7. The refrigeration system according to claim 1, further comprising a stirring means for stirring the cooling liquid in the cooling tank.

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