Refrigeration unit for automatic ice makers

Abstract

To provide a refrigeration system for an automatic ice maker that can stabilize ice-making performance while suppressing the temperature rise of the compressor. [Solution] A refrigerant circulation circuit is formed by a compressor 17, condenser 19, dryer 20, expansion valve 21, evaporator 12, and accumulator 23, which are connected by a discharge pipe 18 and a return pipe 22. A bypass pipe 28, which branches off from the discharge pipe 18 between the dryer 20 and the heat exchange unit 26, is connected to the return pipe 22 between the accumulator 23 and the heat exchange unit 26. A capillary tube 29 is installed in the bypass pipe 28. The liquefied refrigerant flowing into the bypass pipe 28 is depressurized in the capillary tube 29 and flows into the return pipe 22 on the outlet side of the accumulator 23, where it expands rapidly and evaporates, cooling the refrigerant drawn into the compressor 17.

Description

Technical Field

[0001] The present invention relates to a refrigeration device for an automatic ice maker that supplies ice-making water to an ice-making section cooled by circulating and supplying a refrigerant to an evaporator to produce ice cubes.

Background Art

[0002] An injection-type automatic ice maker (for example, see Patent Document 1) that freezes ice-making water in a large number of downwardly open ice-making compartments to continuously produce a large number of ice cubes (for example, cubed ice) is preferably used in tea shops, restaurants, and other kitchen facilities. In the automatic ice maker, an evaporator constituting a refrigeration device is closely arranged in a meandering manner on the upper surface of an ice-making section in which a large number of downwardly open ice-making compartments are defined. In the ice-making process, the ice-making section is cooled by vaporizing the refrigerant in the evaporator, and in the defrosting process, the ice-making section is heated by supplying hot gas to the evaporator.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In recent years, from the viewpoints of preventing ozone layer depletion and global warming, the movement to replace the refrigerant used in the refrigeration device with a refrigerant having a low global warming potential, for example, a single refrigerant or an azeotropic refrigerant (pseudo-azeotropic refrigerant), etc., has been accelerating. However, when a refrigerant with a low global warming potential is used, the discharge temperature of the compressor tends to rise, and parts such as the compressor may reach temperatures and pressures exceeding the specifications, leading to problems that cause failures. In addition, in an automatic ice maker, the difference between the load at the initial stage of ice making and the load immediately before the completion of ice making is large. In order to stabilize the ice-making performance, while the load at the initial stage of ice making is large, the refrigerant is supercooled upstream of an expansion valve provided in the refrigerant path between the compressor and the evaporator to maintain the inlet side of the expansion valve in a flooded state.

[0005] In view of the aforementioned problems inherent in the prior art, the present invention has been proposed to suitably solve these problems, and aims to provide a refrigeration device for an automatic ice maker that can stabilize ice-making performance while suppressing the temperature rise of the compressor. [Means for solving the problem]

[0006] In order to overcome the aforementioned challenges and achieve the intended objectives, the first means is: In a refrigeration system for an automatic ice maker, the system includes a compressor, a condenser that condenses the vaporized refrigerant discharged from the compressor, and an evaporator located in the ice-making section to which ice-making water is supplied during the ice-making process, and which evaporates the liquefied refrigerant liquefied in the condenser, and the system is configured such that the refrigerant returns from the evaporator to the compressor. A heat exchange unit that exchanges heat between the refrigerant flowing through the discharge-side refrigerant path connecting the condenser and evaporator, and the refrigerant flowing through the suction-side refrigerant path connecting the evaporator and compressor, A bypass path is provided, which branches off from upstream of the heat exchanger in the discharge-side refrigerant path and connects to the upstream side of the heat exchanger in the suction-side refrigerant path, allowing refrigerant to flow through it. The gist of the invention is that it is equipped with a throttling mechanism arranged in the bypass path. With this configuration, in the ice-making process, a portion of the liquefied refrigerant discharged from the compressor and passing through the condenser is bypassed via a throttling mechanism to the upstream side of the heat exchange section in the refrigerant path on the intake side. This causes re-evaporation at the inlet side of the heat exchange section, promoting a decrease in the temperature of the refrigerant flowing through the heat exchange section. In other words, the refrigerant flowing through the discharge-side refrigerant path can be cooled more in the heat exchange section, thus promoting supercooling of the refrigerant at the inlet side of the expansion valve. As a result, while the load is high in the initial stages of the ice-making process, the refrigerant can be supercooled upstream of the expansion valve, maintaining the inlet side of the expansion valve full of liquid, thereby stabilizing ice-making performance. Furthermore, since the temperature of the refrigerant returning to the compressor can be reduced, the temperature rise in the refrigerant path on the intake side and the compressor can be suppressed. In other words, the temperature rise of the compressor can be suppressed while maintaining supercooling at the inlet side of the expansion valve. Therefore, even when using a single refrigerant or azeotropic refrigerant (pseudoazeotropic refrigerant), which is preferable from an environmental standpoint, the temperature rise of the compressor can be suppressed and the ice-making capacity can be stabilized, providing an environmentally friendly refrigeration system.

[0007] The second means is that an accumulator is provided upstream of the heat exchange section in the refrigerant path on the intake side, The gist of this is that the bypass path is connected between the evaporator and the accumulator in the refrigerant path on the intake side. With this configuration, the liquefied refrigerant is bypassed in the refrigerant path on the refrigerant inlet side of the accumulator. This allows the accumulator to separate the liquefied refrigerant that did not evaporate in the refrigerant path, preventing it from returning to the compressor and thus preventing malfunctions, while also suppressing the rise in compressor temperature.

[0008] The third method essentially involves providing the bypass route with an opening / closing mechanism for opening and closing the route. With this configuration, the timing of bypassing the refrigerant path on the intake side with liquefied refrigerant can be controlled by the opening and closing mechanism, thus enabling an efficient ice-making and de-icing process. [Effects of the Invention]

[0009] According to the refrigeration system for an automatic ice maker of the present invention, it is possible to stabilize ice-making performance while suppressing the temperature rise of the compressor. [Brief explanation of the drawing]

[0010] [Figure 1] This is a schematic diagram showing the refrigeration system of the automatic ice maker in Example 1. [Figure 2] (a) is a graph showing the refrigerant temperature of a conventional refrigeration system, and (b) is a graph showing the refrigerant temperature of the refrigeration system of Example 1. [Figure 3] This is a schematic diagram showing the refrigeration system of the automatic ice maker in Example 2. [Figure 4] This is a schematic diagram showing the refrigeration system of the automatic ice maker in Example 3. [Modes for carrying out the invention]

[0011] Next, a preferred embodiment of the refrigeration apparatus for an automatic ice maker according to the present invention will be described below with reference to the attached drawings. [Examples]

[0012] Figure 1 is a schematic diagram showing the refrigeration system of an automatic ice maker according to Embodiment 1. The automatic ice maker has an ice-making section 10 located above an ice storage chamber (not shown) defined inside a housing (not shown), with a number of ice-making compartments 10a opening downwards. On the upper surface of the ice-making section 10, evaporators 12, which constitute the refrigeration system, are arranged in a serpentine manner so as to be located above each ice-making compartment 10a. The system is configured to vaporize the refrigerant supplied to the evaporators 12 during the ice-making process to forcibly cool each ice-making compartment 10a.

[0013] As shown in Figure 1, a water tray 13 is tiltably disposed below the ice-making unit 10, capable of closing the ice-making chambers 10a from below. An ice-making water tank 14 for storing a predetermined amount of ice-making water is integrally disposed below the water tray 13. The water tray 13 has injection holes protruding from it at positions corresponding to each ice-making chamber 10a of the ice-making unit 10. A circulation pump 15 for circulating ice-making water during the ice-making process is connected to the ice-making water tank 14 via an intake pipe 15a, and a discharge pipe 15b connected to the circulation pump 15 is connected to the water tray 13. During the ice-making process, the ice-making water supplied to the water tray 13 by the circulation pump 15 is injected into the corresponding ice-making chambers 10a through each injection hole, forming ice blocks in each ice-making chamber 10a. Furthermore, the water tray 13 has numerous return holes that open both upwards and downwards, and any unfrozen water that falls onto the upper surface of the water tray 13 without freezing in the ice-making unit 10 is collected into the ice-making water tank 14 through these return holes. In addition, the automatic ice maker supplies tap water from the external water system to the ice-making water tank 14 via the water tray 13 by opening the water supply valve WV located on the water supply pipe 16 connected to the external water system (external water source).

[0014] The water tray 13 is tilted by a tilting mechanism (not shown) between a closed position, which blocks the lower surface of each ice-making chamber 10a in the ice-making unit 10, and an open position, which is tilted away from the ice-making unit 10 and allows ice blocks to be released from the ice-making chambers 10a. The water tray 13 is held in the closed position during the ice-making process, held in the open position during the de-icing process, and returned to the closed position upon completion of the de-icing process.

[0015] As shown in Figure 1, the refrigeration system has a condenser 19, a dryer 20, and an expansion valve 21 connected in order to the refrigerant discharge side of the compressor 17 via a discharge pipe 18, and the expansion valve 21 is connected to the refrigerant inlet of the evaporator 12 via the discharge pipe 18. In addition, the refrigerant outlet of the evaporator 12 is connected to an accumulator 23 via a return pipe 22, and the accumulator 23 is connected to the refrigerant inlet of the compressor 17 via the return pipe 22. In other words, the compressor 17, condenser 19, dryer 20, expansion valve 21, evaporator 12, and accumulator 23, which are connected by the discharge pipe 18 and the return pipe 22, constitute a refrigerant circulation circuit. The vaporized refrigerant compressed by the compressor 17 is supplied to the condenser 19 where it condenses and liquefies. The liquefied refrigerant, dehumidified by the dryer 20, is depressurized by the expansion valve 21 and then flows into the evaporator 12, where it rapidly expands and evaporates, exchanging heat with the ice-making unit 10 and cooling it to below freezing point. The vaporized refrigerant evaporated in the evaporator 12 and the unevaporated liquefied refrigerant flow into the accumulator 23 in a gas-liquid mixed phase, where gas-liquid separation occurs. The vaporized refrigerant separated in the accumulator 23 is then drawn into the compressor 17, and the liquefied refrigerant is stored in the accumulator 23. The discharge pipe 18 refers to the refrigerant path on the discharge side from the refrigerant outlet of the compressor 17 to the refrigerant inlet of the evaporator 12, and the return pipe 22 refers to the refrigerant path on the suction side from the refrigerant outlet of the evaporator 12 to the refrigerant inlet of the compressor 17.

[0016] As shown in Fig. 1, a hot gas pipe 24 is branched and connected to a discharge pipe 18 connecting the compressor 17 and the condenser 19. This hot gas pipe 24 is connected to a discharge pipe 18 connecting the evaporator 12 and the expansion valve 21 via a hot gas valve HV. The hot gas valve HV is opened only during the defrosting process and is controlled to be closed during the ice-making process by control means not shown. That is, during the defrosting process, the hot gas valve HV is opened, and the hot gas discharged from the compressor 17 is bypassed to the evaporator 12 via the hot gas pipe 24, and the ice-making part 10 is heated to melt the freezing surface of the ice block generated in the ice-making chamber 10a, and the ice block is dropped by its own weight. Further, the hot gas flowing out from the evaporator 12 flows into the accumulator 23, heats and evaporates the liquefied refrigerant stored in this accumulator 23, and is sucked into the compressor 17 as vaporized refrigerant. In the figure, the reference sign FM indicates a fan motor for air-cooling the condenser 19, and the reference sign 25 indicates a strainer disposed upstream of the hot gas valve HV in the hot gas pipe 24 to prevent foreign matter from flowing into the hot gas valve HV. Further, the discharge pipe 18 connecting the drier 20 and the expansion valve 21 and the return pipe 22 connecting the accumulator 23 and the compressor 17 are arranged so as to contact each other over a predetermined length, and in a heat exchange part 26 where both pipes 18 and 22 contact each other, the refrigerant flowing through the discharge pipe 18 and the refrigerant flowing through the return pipe 22 are configured to be able to exchange heat.

[0017] As shown in Fig. 1, a temperature sensing cylinder 27 for detecting the refrigerant temperature is closely disposed on a return pipe 22 between the evaporator 12 and the accumulator 23, and the expansion valve 21 is configured to perform throttle control according to the refrigerant temperature information detected by the temperature sensing cylinder 27. That is, when the detected temperature of the temperature sensing cylinder 27 is low, the expansion valve 21 is controlled in the closing direction to suppress the circulation amount of the liquefied refrigerant to the evaporator 12, and when the detected temperature of the temperature sensing cylinder 27 is high, the expansion valve 21 is controlled in the opening direction to increase the circulation amount of the liquefied refrigerant to the evaporator 12.

[0018] As shown in FIG. 1, a bypass pipe (bypass path) 28 branched from the discharge pipe 18 between the dryer 20 and the heat exchange section 26 (upstream of the heat exchange section 26) is connected to the return pipe 22 between the accumulator 23 and the heat exchange section 26 (upstream of the heat exchange section 26). A capillary tube 29 is provided in the bypass pipe 28 as throttle means. The liquefied refrigerant flowing into the bypass pipe 28 is depressurized by the capillary tube 29, flows into the return pipe 22 on the outlet side of the accumulator 23, expands and evaporates here all at once, and cools the refrigerant sucked into the compressor 17. In the first embodiment, the capillary tube 29 is directly connected to the return pipe 22.

[0019] 〔Operation of the First Embodiment〕 Next, the operation of the refrigeration device of the automatic ice maker according to the first embodiment will be described.

[0020] In the refrigeration apparatus of Example 1, a bypass pipe 28 branched from the discharge pipe 18 is connected to the return pipe 22, and a capillary tube 29 is installed in the bypass pipe 28. As a result, in the ice-making process, a portion of the liquefied refrigerant discharged from the compressor 17 and passing through the condenser 19 is depressurized in the capillary tube 29 and flows into the return pipe 22 upstream of the heat exchange section 26. The liquefied refrigerant that flows into the return pipe 22 evaporates upstream of the heat exchange section 26, thus promoting a decrease in the temperature of the refrigerant flowing through the heat exchange section 26. In other words, the refrigerant flowing through the discharge pipe 18 can be cooled more in the heat exchange section 26, thus promoting supercooling of the refrigerant on the inlet side of the expansion valve 21. Furthermore, since the refrigerant is bypassed from the discharge pipe 18 to the return pipe 22, the amount of refrigerant drawn into the compressor 17 increases, and the low pressure of the compressor 17 can be increased. As a result, during the initial period of high load in the ice-making process, the refrigerant can be supercooled upstream of the expansion valve 21, maintaining the inlet side of the expansion valve 21 at full capacity, thereby stabilizing ice-making performance. Furthermore, the temperature of the refrigerant returning to the compressor 17 can be reduced, preventing components such as the return pipe 22 and the compressor 17 from exceeding their specified temperatures and pressures. In other words, a simple configuration in which a portion of the refrigerant flowing through the discharge pipe 18 is bypassed to the return pipe 22 by the bypass pipe 28 and capillary tube 29 allows for maintaining supercooling on the inlet side of the expansion valve 21 while suppressing the temperature rise of the compressor 17. Therefore, even when using a single refrigerant or azeotropic refrigerant (pseudoazeotropic refrigerant), which are environmentally friendly, the temperature rise of the compressor 17 can be suppressed, and the ice-making capacity can be stabilized, providing an environmentally friendly refrigeration system. Examples of single refrigerants include R134a, R290, R600a, and R32. Examples of azeotropic refrigerants (pseudoazeotropic refrigerants) include R404a, R410a, and R448a. In addition, various other refrigerants with low global warming potentials can be used.

[0021] [Regarding experimental examples] Figure 2 shows the results of measuring the refrigerant temperatures at the condenser outlet, return pipe, and expansion valve inlet for the refrigeration system of Example 1 shown in Figure 1 and a conventional refrigeration system (conventional example) that does not have the bypass pipe and capillary tube shown in Figure 1. Figure 2(a) shows the refrigerant temperature of the conventional refrigeration system, and Figure 2(b) shows the refrigerant temperature of the refrigeration system of Example 1.

[0022] In other words, the experiment showed that the refrigerant temperature in the return pipe 22 at maximum load during the ice-making process was approximately 41°C in the conventional example, compared to approximately 29°C in Example 1. This indicates that Example 1 can significantly lower the refrigerant temperature drawn into the compressor 17 compared to the conventional example. Furthermore, the difference between the refrigerant temperature at the condenser outlet and the refrigerant temperature at the expansion valve inlet was approximately 10°C in the conventional example, compared to approximately 13°C in Example 1. This indicates that Example 1 can achieve a greater degree of refrigerant subcooling upstream of the expansion valve 21 than the conventional example. [Examples]

[0023] Figure 3 shows the refrigeration system of the automatic ice maker of Example 2. Only the parts that differ from Example 1 will be described, and the same reference numerals will be used for the same components already mentioned in Example 1, and detailed descriptions will be omitted.

[0024] In the refrigeration apparatus of Example 2, a bypass pipe 28 branched from the discharge pipe 18 between the dryer 20 and the heat exchange unit 26 is connected to a return pipe 22 between the evaporator 12 and the accumulator 23. In Example 2, a capillary tube 29 is directly connected to the return pipe 22.

[0025] In the refrigeration apparatus of Example 2, in addition to the effects and benefits of the refrigeration apparatus of Example 1, the following effects and benefits can be obtained. In other words, the refrigerant bypassed to the return pipe 22 by the bypass pipe 28 returns to the compressor 17 via the accumulator 23. Therefore, any liquefied refrigerant that did not evaporate in the return pipe 22 is separated by the accumulator 23, preventing it from being drawn into the compressor 17. Consequently, it is possible to prevent the return of liquefied refrigerant to the compressor 17, thereby preventing malfunctions and suppressing the temperature rise of the compressor 17. [Examples]

[0026] Figure 4 shows the refrigeration system of the automatic ice maker of Example 3. Only the parts that differ from Example 1 will be described, and the same reference numerals will be used for the same components that appeared in Example 1, and detailed descriptions will be omitted.

[0027] In the refrigeration apparatus of Example 3, a solenoid valve 30 is provided between the branch from the discharge pipe 18 and the capillary tube 29 in the bypass pipe 28 of the refrigeration apparatus of Example 1, as an opening and closing means for opening and closing the pipeline (path). The solenoid valve 30 is controlled to open the pipeline during the ice-making process to supply the liquefied refrigerant branched from the discharge pipe 18 to the bypass pipe 28 to the return pipe 22, and to close the pipeline during the de-icing process to stop the supply of liquefied refrigerant to the return pipe 22.

[0028] In addition to the effects and benefits of the refrigeration apparatus of Example 1, the following effects and benefits can be obtained in the refrigeration apparatus of Example 3. In other words, during the de-icing process, the supply of liquefied refrigerant to the return pipe 22 via the bypass pipe 28 is stopped. This prevents the refrigerant temperature on the low-pressure side of the compressor 17 from decreasing and thus the hot gas temperature from decreasing, enabling an efficient ice-making and de-icing process.

[0029] [Another embodiment of Example 3] In the refrigeration apparatus of Example 3, the following alternative embodiment can be adopted as a method for controlling the opening and closing of the solenoid valve 30. (a) The solenoid valve 30 is operated to open the pipeline for a predetermined opening time from the start of the ice-making process, supplying the liquefied refrigerant branched from the discharge pipe 18 to the bypass pipe 28 to the return pipe 22, and is operated to close the pipeline after the opening time has elapsed, thereby stopping the supply of liquefied refrigerant to the return pipe 22. The opening time can be set to a time corresponding to the period when the ice-making load is large in the initial stages of ice making, and according to this alternative embodiment of (a), the ice-making capacity in the ice-making process can be further stabilized.

[0030] (b) An ice-making section temperature detection means is provided to detect the temperature of the ice-making section 10, and the solenoid valve 30, which opens the pipeline when the ice-making process starts, is operated to close the solenoid valve 30 when the temperature detected by the ice-making section temperature detection means reaches a preset closing temperature (for example, -5°C). (c) A condenser temperature detection means is provided to detect the temperature of the refrigerant passing through the condenser 19. The solenoid valve 30 is closed at the start of the ice-making process, and is operated to open when the temperature detected by the condenser temperature detection means begins to decline. The solenoid valve 30 is then operated to close after a preset opening time has elapsed. The opening time is set to the same time as in the other embodiment (a). According to the alternative embodiments in (b) and (c), the opening and closing of the solenoid valve 30 is controlled by the refrigerant temperature, so the amount of refrigerant bypassed to the return pipe 22 can be precisely controlled according to the refrigerant temperature, and the ice-making capacity can be further stabilized.

[0031] [Example of change] This application is not limited to the configurations of the embodiments described above, and other configurations can be adopted as appropriate. Furthermore, various embodiments can be adopted within the scope of the spirit of the present invention, not limited to the following modified examples, for the configurations described in each embodiment. (1) The throttling means installed in the bypass pipe may be an expansion valve or other known means instead of a capillary tube. (2) In each embodiment, the description was given using a so-called closed-cell type ice-making mechanism, which has a water tray that can open and close the ice-making chamber from below. However, the invention is not limited to this, and various mechanisms can be used, such as an open-cell type ice-making mechanism or a flow-type ice-making mechanism that supplies ice-making water to the ice-making surface of the ice-making plate. [Explanation of Symbols]

[0032] 10 Ice-making unit, 12 Evaporator, 17 Compressor, 18 Discharge pipe (refrigerant path on the discharge side) 19 Condenser, 22 Return pipe (refrigerant path on the intake side), 23 Accumulator 26 Heat exchange section, 28 Bypass pipe (bypass path) 29 Capillary tube (throttling mechanism), 30 Solenoid valve (opening / closing mechanism)

Claims

1. In a refrigeration system for an automatic ice maker, the system includes a compressor (17), a condenser (19) that condenses the vaporized refrigerant discharged from the compressor (17), and an evaporator (12) located in an ice-making section (10) to which ice-making water is supplied during the ice-making process, and which evaporates the liquefied refrigerant liquefied in the condenser (19), wherein the refrigerant is configured to return from the evaporator (12) to the compressor (17), A heat exchange unit (26) that exchanges heat between the refrigerant flowing through the discharge-side refrigerant path (18) connecting the condenser (19) and the evaporator (12) and the refrigerant flowing through the suction-side refrigerant path (22) connecting the evaporator (12) and the compressor (17), A bypass path (28) is provided, which branches off from upstream of the heat exchange unit (26) in the discharge-side refrigerant path (18) and connects to the upstream side of the heat exchange unit (26) in the suction-side refrigerant path (22), allowing refrigerant to flow through it. The system comprises a throttling means (29) arranged in the bypass path (28). A refrigeration device for an automatic ice maker, characterized by the following features.

2. An accumulator (23) is provided upstream of the heat exchange section (26) in the refrigerant path (22) on the intake side. The refrigeration system for an automatic ice maker according to claim 1, wherein the bypass path (28) is connected between the evaporator (12) and the accumulator (23) in the refrigerant path (22) on the suction side.

3. The refrigeration device for an automatic ice maker according to claim 1, wherein the bypass path (28) is provided with an opening / closing means (30) for opening and closing the path.

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