Refrigeration circuit

Abstract

Provided is a freezing circuit capable of stably generating a magnetic field in the coil of a magnetic field generator for a long time.　The present invention is provided with a compressor (11), a condenser (12), an expansion valve (13), and an evaporator that are connected by refrigerant piping (10). The evaporator is formed from a coil (14) that is wound in a solenoidal shape with a rectangular cross section and formed with a plurality of through holes (21) through which a refrigerant flows, and generates a magnetic field from the coil (14). This allows the coil (14) to serve as an evaporator and to be efficiently cooled by the refrigerant, thereby stably generating a strong magnetic field for a long time.

Description

[Technical Field]

[0001] The present invention relates to a refrigeration circuit, and more particularly to a refrigeration circuit capable of generating a magnetic field stably for a long period of time. [Background technology]

[0002] Alternating magnetic field therapy, which uses heating by an alternating magnetic field to kill tumor cells, has been known (for example, Patent Document 1). Coils that use the principle of induction heating, such as induction heaters, generate heat by themselves when a large current is passed through them. Therefore, it is known to cool the coil by running cooling water through it.

[0003] FIG. 11 is a diagram showing a conventional cooling system 501. Referring to FIG. 11, the cooling system 501 is configured to cool a conventional coil 502 with cooling water. A pipe formed into a coil shape is used as the coil 502. Water can be made to flow inside the pipe of the coil 502. A high-frequency current generator 503 is connected to the coil 502.

[0004] Cooling system 501 is configured with a path 504 for flowing cooling water to coil 502. Path 504 is provided with a tank 505 for storing cooling water, a pump 506 for sending cooling water from tank 505 and circulating it through path 504, and a radiator 507 for cooling the cooling water circulating through path 504. The cooling water flowing through path 504 flows inside the pipe of coil 502. This cools coil 502. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Special Table 2018-510700 Summary of the Invention [Problem to be solved by the invention]

[0006] When a current is passed through a coil to generate a magnetic field, Joule heat is inevitably generated due to the coil's electrical resistance. For example, when a large current of about 100 A is passed through a coil as a high-frequency alternating current, the resistance component becomes large.

[0007] Therefore, for example, if the resistance is 1 Ω, the heat generated will be 1 Ω x 100 A x 100 A = 10,000 W. If this is cooled with water, to keep the temperature rise of the cooling water to 10°C, the following must be satisfied: 10 kW = 4.18 J / kg°C x 10°C x mass flow rate M (kg / s). In other words, if we convert the mass flow rate M to satisfy this requirement into a volumetric flow rate, we need to supply circulating water at a rate of 14 L / min.

[0008] However, the coils that generate a strong magnetic field need to have an extremely small coil pitch, which results in a huge pressure loss when circulating water, as mentioned above, and requires a large-scale water pump for cooling.

[0009] The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a refrigeration circuit for a magnetic field generator that can efficiently cool a coil using a useful cooling method and can stably generate a strong magnetic field for a long period of time. [Means for solving the problem]

[0010] The refrigeration circuit of the present invention includes a compressor, a condenser, an expansion valve, and an evaporator, which are connected via a refrigerant pipe. The evaporator is formed from a coil in which a coil base material having a plurality of through holes formed therein for allowing the refrigerant to flow is wound in a solenoid shape. The coil generates a magnetic field. The coil substrate has a rectangular cross section, and is wound in a cylindrical spiral shape with the long side of the cross section facing the winding diameter direction of the coil and the short side of the cross section running along the cylinder, and the through holes are aligned in the winding diameter direction of the coil in the cross section. It is characterized by: [Effects of the Invention]

[0011] The refrigeration circuit of the present invention includes a compressor, a condenser, an expansion valve, and an evaporator, all connected via a refrigerant pipe. The evaporator is formed from a coil in which a coil substrate having a plurality of through holes formed therein for refrigerant flow is wound in a solenoid shape. With this configuration, the coil can be used as an evaporator of the refrigeration circuit and efficiently cooled by the refrigerant. The refrigeration circuit of the present invention generates a magnetic field from the coil. Therefore, a strong magnetic field can be generated stably for a long period of time from the cooled coil.

[0012] According to the refrigeration circuit of the present invention, the through holes may be arranged in a radial direction of the coil in a cross section of the coil substrate, thereby shortening the length of the coil in the axial direction and enabling a strong magnetic field to be generated with high performance using a compact coil.

[0013] According to the refrigeration circuit of the present invention, the coil substrate may have a rectangular cross section and be wound such that the long side of the cross section faces the radial direction of the coil, thereby shortening the length of the coil in the axial direction and enabling a compact coil to generate a strong magnetic field with high performance.

[0014] According to the refrigeration circuit of the present invention, the coil may be covered with an insulating material, thereby allowing the coil to be efficiently cooled by the evaporating refrigerant.

[0015] The refrigeration circuit of the present invention may further comprise a high-frequency current generator connected to the inlet and outlet sides of the coil to apply an alternating current, thereby enabling a highly efficient generation of a magnetic field from the cooled coil.

[0016] Furthermore, in the refrigeration circuit of the present invention, the inlet and outlet joints of the coil may be connected to the refrigerant pipe via an insulating material, thereby preventing electrical leakage from the coil to the refrigerant pipe. This allows a high current to be safely passed through the cooled coil, and a high-performance magnetic field to be safely generated.

[0017] Furthermore, in the refrigeration circuit of the present invention, the refrigerant may be a hydrofluorocarbon, a hydrofluoroolefin, carbon dioxide, or a mixture thereof, which allows the coil to be cooled efficiently by utilizing the evaporation of the refrigerant, thereby enabling a strong magnetic field to be generated stably for a long period of time. [Brief explanation of the drawings]

[0018] [Figure 1] FIG. 1 is a diagram showing a refrigeration circuit according to an embodiment of the present invention. [Figure 2] FIG. 2 is a diagram showing a coil of a refrigeration circuit according to an embodiment of the present invention. [Figure 3] FIG. 3 is a pH diagram showing the state in which the coil is cooled in the refrigeration circuit according to the embodiment of the present invention. [Figure 4] FIG. 4 is a diagram showing the configuration of the vicinity of the end of the coil in the refrigeration circuit according to the embodiment of the present invention. [Figure 5] FIG. 5 shows (A) a plan view and (B) a cross-sectional view of a coil of a refrigeration circuit according to an embodiment of the present invention. [Figure 6] FIG. 6 is a cross-sectional view of a coil substrate of a refrigeration circuit according to an embodiment of the present invention. [Figure 7] FIG. 7 is a cross-sectional view of a coil substrate of a refrigeration circuit according to another embodiment of the present invention. [Figure 8] FIG. 8 is a cross-sectional view of a coil substrate of a refrigeration circuit according to another embodiment of the present invention. [Figure 9] FIG. 9 is a cross-sectional view of a coil substrate of a refrigeration circuit according to another embodiment of the present invention. [Figure 10] FIG. 10 is a cross-sectional view of a coil substrate of a refrigeration circuit according to another embodiment of the present invention. [Figure 11] FIG. 11 is a diagram showing the circuit configuration of a conventional cooling system. DETAILED DESCRIPTION OF THE INVENTION

[0019] Hereinafter, a refrigeration circuit according to an embodiment of the present invention will be described in detail with reference to the drawings as appropriate. Note that the illustrated embodiments do not limit the present invention, but merely exemplify the present invention.

[0020] Fig. 1 is a diagram showing a schematic configuration of a refrigeration circuit 1 according to an embodiment of the present invention. Referring to Fig. 1, the refrigeration circuit 1 has a coil 14 that generates a magnetic field, and has a basic circuit configuration in which the coil 14 is cooled by a refrigerant. The refrigeration circuit 1 constitutes a magnetic field generating device that can stably generate a strong magnetic field from the coil 14 for a long period of time.

[0021] Coil 14 is compact, for example, about the size of a human head. Refrigeration circuit 1 is particularly useful when a strong magnetic field needs to be generated by passing a large current through coil 14. Refrigeration circuit 1 is suitable for treating areas where conventional surgery is difficult or impossible, such as brain tumors and breast cancer.

[0022] Specifically, the refrigeration circuit 1 includes a compressor 11, a condenser 12, an expansion valve 13, and a coil 14 as an evaporator, which are connected via a refrigerant pipe 10, and constitutes a vapor compression refrigeration cycle circuit that cools the coil 14 by evaporation of the refrigerant.

[0023] The compressor 11 is a device that compresses the refrigerant and sends it to the condenser 12. As the compressor 11, various types of compression devices such as rotary type, scroll type, reciprocating type, screw type, and the like can be used.

[0024] In particular, the rotary compressor 11 is suitable for configuring a compact refrigeration circuit 1 with a small cooling capacity. The compressor 11 may also be a two-stage compression type. The use of a two-stage compression type as the compressor 11 is suitable for compressing a high-pressure carbon dioxide refrigerant.

[0025] The condenser 12 is, for example, an air-cooled heat exchanger in which air that exchanges heat with the refrigerant is blown by a blower fan. For example, although not shown, the condenser 12 may be a fin-and-tube heat exchanger. That is, the condenser 12 has a plurality of tubes, such as copper tubes, through which the refrigerant flows, and a plurality of aluminum fins arranged in parallel, and the tubes are inserted into holes formed in the fins.

[0026] The condenser 12 may be a water-cooled heat exchanger. Also, various types of heat exchangers, such as a plate type, a shell-and-tube type, and a double-tube type, can be used as the condenser 12. In particular, a plate type heat exchanger is preferable because it has high heat exchange efficiency and allows the condenser 12 to be made compact.

[0027] Expansion valve 13 reduces the pressure of the refrigerant liquid that has passed through condenser 12. Expansion valve 13 also has the function of adjusting the flow of the refrigerant. Various types of expansion valves, such as electronic expansion valves, thermostatic expansion valves, and capillary tubes, can be used as expansion valve 13. By using an electronic expansion valve as expansion valve 13, it is possible to control the cooling of coil 14 with high efficiency, and to improve magnetic field generation performance.

[0028] Coil 14 is a component for generating an alternating magnetic field, for example, as indicated by arrow B, and also functions as an evaporator in the refrigeration cycle. As an evaporator, coil 14 is cooled by the refrigerant. This prevents coil 14 from becoming too hot even when a high current flows through it, and allows it to stably generate a strong magnetic field for a long period of time. Details of coil 14 will be described later.

[0029] The refrigeration circuit 1 has an electric circuit for operating the coil 14. The electric circuit is provided with a high-frequency current generator 35. The high-frequency current generator 35 is connected to the inlet side 22 of the coil 14 via wiring 38 and to the outlet side 23 of the coil 14 via wiring 39, and passes an alternating current through the coil 14. With this configuration, a magnetic field can be generated from the cooled coil 14 with high efficiency.

[0030] 1 shows a refrigerant path of a refrigeration cycle circuit formed by refrigerant piping 10, i.e., a refrigerant circulation path. The refrigerant flows in direction A within the refrigerant piping 10 and circulates through the refrigerant path. Specifically, the refrigerant compressed by the compressor 11 is sent to the condenser 12 via the refrigerant piping 10 and is cooled by the condenser 12.

[0031] The refrigerant cooled in the condenser 12 flows through the refrigerant pipe 10 to the expansion valve 13, where it is decompressed. The refrigerant is then decompressed by the expansion valve 13 to become a low-temperature gas-liquid mixed fluid, which is then introduced into the coil 14 through the refrigerant pipe 10.

[0032] The refrigerant sent to the coil 14 is vaporized by utilizing the heat generated by the current in the coil 14 as latent heat of vaporization. That is, the refrigerant evaporates inside the coil 14 and removes heat from the coil 14.

[0033] Next, the refrigerant evaporated in the coil 14 returns to the compressor 11 via the refrigerant pipe 10 and is compressed again. The above process is then repeated. That is, a circulating flow of refrigerant is formed that cools the coil 14 by sequentially passing through the compressor 11, the condenser 12, the expansion valve 13, and the coil 14 serving as an evaporator.

[0034] The refrigerant used in the refrigeration circuit 1 is, for example, hydrofluorocarbon, hydrofluoroolefin, carbon dioxide, or a mixture thereof. This makes it possible to efficiently cool the coil 14 by utilizing the latent heat of evaporation of the refrigerant, and to generate a strong magnetic field stably for a long period of time.

[0035] The condenser 12 may be a gas cooler in which the condensation of the refrigerant is not clearly evident. That is, fluorocarbon refrigerants such as typical refrigerants HFC-32 and HFC-404A are condensable in the normal operating environment of the condenser 12, which is approximately -20°C to 42°C. However, in the case of a carbon dioxide refrigerant, the condenser 12 operates in the supercritical region, and therefore is called a gas cooler. Even if the condenser 12 is a gas cooler, it is still a mechanism for cooling the refrigerant.

[0036] Fig. 2 is a diagram showing a schematic configuration of the coil 14 of the refrigeration circuit 1. Referring to Fig. 2, the coil 14 is a member that generates a magnetic field when a current flows through it, and is wound in a solenoid shape. As described above, the coil 14 constitutes an evaporator of the refrigeration cycle.

[0037] Specifically, coil 14 is formed by winding a long flat plate or the like made of a good conductor such as silver, aluminum, copper, or a copper alloy into a coil shape. More specifically, coil 14 is made of a flat plate having a substantially rectangular cross section, and is wound in a substantially spiral shape such that the long side of the cross section corresponds to the radial direction of coil 14 and the short side corresponds to the winding axis direction of coil 14. In other words, coil 14 is wound so that the short side of the substantially rectangular cross section follows the shape of a substantially cylinder.

[0038] Coil 14 has a structure in which a plurality of minute through-holes 21, i.e., microchannels, penetrate through it, and a refrigerant can flow through the through-holes 21. Specifically, a plurality of minute through-holes 21 that penetrate the flat plate that is the material for coil 14 in the longitudinal direction of the flat plate are formed. That is, coil 14 has a plurality of through-holes 21 formed therein that serve as flow paths through which the refrigerant flows. Note that coil 14 may be an induction coil.

[0039] 1, the voltage of the drive power supply for coil 14 is preferably, for example, 12 V to 440 V, and more preferably 12 V to 100 V. This allows a magnetic field suitable for the treatment area to be generated. For example, if an effective voltage of 50 V is applied to coil 14 and a current of 100 A is passed through it, the DC resistance component of coil 14 is 0.5 Ω, and heat generation is 5 kW.

[0040] Fig. 3 is a ph diagram (pressure-specific enthalpy diagram) showing the state of cooling the coil 14 in the refrigeration circuit 1. With reference to Figs. 1 and 3, the refrigerant is compressed to a high pressure by the compressor 11 in a compression process S1, and is cooled by the condenser 12 in a heat dissipation process S2. The refrigerant is then decompressed by the expansion valve 13 in an expansion process S3, and is evaporated in the coil 14 in an evaporation process S4 to cool the coil 14.

[0041] For example, a refrigeration cycle is configured in which the refrigerant evaporates at a temperature of 15°C inside the coil 14 and condenses at a temperature of 35°C inside the condenser 12 using HFC-32, a hydrofluorocarbon refrigerant commonly used in air conditioners. That is, a refrigeration cycle is configured in which the evaporation temperature T1 of the refrigerant in the evaporation process S4 is 15°C, and the condensation temperature T2 of the refrigerant in the heat release process S2 is 35°C.

[0042] At this time, cooling is possible with a refrigerant circulation rate of 0.01861 (kg / s), as shown in Table 1. To achieve this refrigerant circulation rate, the displacement volume of compressor 11, which runs on a 50 Hz commercial power supply, only needs to be 10.6 (cc), which can be achieved with a small compressor.

[0043] [Table 1]

[0044] 1, a refrigerant flows through the coil 14, and at the same time, an electric current flows through the coil 14. In the refrigeration circuit 1, in order to pass an electric current through the coil 14, electrodes 36 and 37 are provided near two ends of the coil 14, i.e., on the inlet side 22 and the outlet side 23.

[0045] One output terminal of the high-frequency current generator 35 is connected to an electrode 36 on the inlet side 22 of the coil 14 via a wiring 38, and the other output terminal is connected to an electrode 37 on the outlet side 23 of the coil 14 via a wiring 39.

[0046] The refrigerant pipes 10 that form the refrigerant path through which the refrigerant flows are made of, for example, copper pipes or steel pipes. Because the refrigerant pipes 10 are made of highly conductive materials such as copper or iron, there is a risk that the current from the coil 14 will flow into the refrigerant path formed by the refrigerant pipes 10. In this case, there will be problems with current leakage to the drive devices for the compressor 11, the expansion valve 13, etc., and to the outside of the refrigeration circuit 1.

[0047] Fig. 4 is a diagram showing the configuration near the end of the coil 14 in the refrigeration circuit 1. To solve the above-mentioned problem of electrical leakage, in the refrigeration circuit 1, as shown in Fig. 4, the connection part 25 between the coil 14 and the refrigerant pipe 10 is connected via an insulating material 31.

[0048] Specifically, an insulating material 31 is provided between the coil side flange 27, which is the flange portion of the coil side joint 26, and the piping side flange 29, which is the flange portion of the piping side joint 28. That is, the coil side flange 27 and the piping side flange 29 are connected via the insulating material 31.

[0049] The insulating material 31 is formed of, for example, a synthetic resin such as polytetrafluoroethylene (PTFE) that has excellent insulating properties. The insulating material 31 may include a base material such as paper, cloth, or various other synthetic fibers. The insulating material 31 may also be an insulating paint. By providing the insulating material 31 between the coil side flange 27 and the piping side flange 29 in this way, it is possible to prevent leakage current due to contact between the coil side flange 27 and the piping side flange 29.

[0050] Furthermore, the coil-side joint 26 and the pipe-side joint 28 are fixed together by a support member 33 such as a bolt and a nut. Therefore, it is necessary to prevent current from flowing from the coil 14 to the refrigerant pipe 10 through the support member 33.

[0051] Therefore, a coil side insulating material 30 is provided between the coil side flange 27 and the support member 33 , and a pipe side insulating material 32 is provided between the pipe side flange 29 and the support member 33 .

[0052] The coil-side insulating material 30 and the pipe-side insulating material 32 are made of synthetic resin or the like having excellent insulating properties. The coil-side insulating material 30 and the pipe-side insulating material 32 may also contain a base material such as paper or cloth. By providing the coil-side insulating material 30 and the pipe-side insulating material 32 in this manner, leakage of electricity through the support member 33 can be prevented.

[0053] In this way, the refrigeration circuit 1 can prevent current from flowing from the coil 14 through the refrigerant pipe 10 to the outside, etc. Therefore, a high current can be safely passed through the cooled coil 14, and a high-performance magnetic field can be safely generated.

[0054] Hydrofluorocarbons, hydrofluoroolefins, and carbon dioxide, which are used as refrigerants, have good insulating properties. Carbon dioxide, in particular, is a non-polar molecule, making it an extremely useful refrigerant for this application.

[0055] Fig. 5 is a diagram showing a schematic configuration of the coil 14 of the refrigeration circuit 1. Fig. 5(A) is a plan view, and Fig. 5(B) is a cross-sectional view taken along line CC shown in Fig. 5(A). As shown in Fig. 5, the coil 14 has the coil substrate 20 portion covered with an insulating material 24 almost entirely.

[0056] The insulating material 24 is molded from a synthetic resin material such as ABS (acrylonitrile butadiene styrene) or PP (polypropylene). Alternatively, a ceramic material may be used as the material for the insulating material 24. Alternatively, the insulating material 24 may be formed by painting with an insulating paint. By covering almost the entire coil 14 with the insulating material 24 in this manner, it is possible to prevent current from leaking from the coil 14 to the human body or surrounding structures.

[0057] As mentioned above, the coil 14 functions as an evaporator in the refrigeration cycle. That is, the refrigerant evaporates as it flows through the coil 14, thereby cooling the coil 14. A typical evaporator in the prior art is designed to generate cold. In other words, a typical evaporator exists to produce cold air, as in an air conditioner, or to make ice, as in a refrigerator. Therefore, a conventional evaporator cannot fulfill its role if it is completely covered, as in the coil 14 according to the present embodiment.

[0058] However, in the coil 14 serving as an evaporator according to this embodiment, the refrigerant only needs to remove the heat generated by the coil 14 itself, and there is no need to cool the outside. Therefore, there is no problem even if the entire surface of the coil 14 is covered with the insulating material 24, and the coil 14 has a useful structure that can be appropriately designed to provide insulation and heat insulation against the human body and surrounding structures. This allows the evaporating refrigerant to efficiently cool the coil 14, enabling stable generation of magnetic force.

[0059] Fig. 6 is a cross-sectional view showing the coil 14 of the refrigeration circuit 1. More specifically, Fig. 6 shows a cross-section of the coil substrate 20 of the coil 14. As shown in Fig. 6, the cross-section of the coil 14, i.e., the cross-section of the coil substrate 20, is substantially rectangular. In other words, the coil 14 is formed from a plate-shaped coil substrate 20. Note that the short sides of the cross-section of the coil 14 may be formed in a curved shape, such as a substantially arc-shaped shape.

[0060] As shown in FIG. 2, the coil 14 is formed by winding the short side of a rectangular cross section along a substantially cylindrical shape. This forms a solenoid that generates a magnetic field. To generate a strong magnetic field in a substantially spirally wound structure such as a solenoid, it is desirable to have a large number of turns per unit length. To achieve this, as shown in FIG. 6, the coil 14 has a substantially rectangular cross section, and the length of the short side of the cross section, i.e., the thickness t1 of the coil substrate 20, is formed to be small.

[0061] 6, the thickness t1 of the coil substrate 20 is approximately 1 to 10 mm, and preferably approximately 3 mm. The refrigerant flow paths, i.e., through holes 21, formed in the coil 14 having such a thin, strip-like rectangular cross section are minute, substantially circular holes with an inner diameter d1 of approximately 1 mm.

[0062] Generally, if water is flowed through such tiny holes, the flow resistance becomes extremely high. Even a small amount of contamination or foreign matter can clog the holes, causing localized cooling problems. In the worst case scenario, there is a risk of the coil melting. The through holes 21 in the compactly molded coil 14, which generates a strong magnetic field, are so tiny that conventional water cooling is impossible.

[0063] On the other hand, refrigerant has a viscosity much lower than water, and generally can easily flow through holes with an inner diameter d1 of about 1 mm. Therefore, coil 14 functions as an evaporator in the refrigeration cycle and utilizes the latent heat of evaporation of the refrigerant, so that high-performance cooling performance can be obtained despite the compact configuration with fine through-holes 21, and as a result, high-performance magnetic field generation capability can be obtained.

[0064] As mentioned above, the coil 14 is made of a good conductor such as silver, aluminum, copper, or a copper alloy. Copper or a copper alloy is the most desirable material for the coil 14. This provides low electrical resistance, allowing a high current to flow, and high thermal conductivity for optimal cooling by the evaporation of the refrigerant, making it possible to stably generate a strong magnetic field for a long period of time.

[0065] Next, as modified examples of the embodiment, coil substrates 120, 220, 320, and 420 in which the configuration of the coil substrate 20 is modified will be described in detail with reference to Figures 7 to 10. Note that components other than the coil substrates 120, 220, 320, and 420 showing modified examples in Figures 7 to 10 are the same as or similar to those in the already described embodiments, and therefore description thereof will be omitted.

[0066] FIG. 7 is a cross-sectional view showing a coil substrate 120 of a coil 14 according to another embodiment of the present invention.1 7 shows a cross section of the through hole 121. As shown in FIG.

[0067] For example, the through-holes 121 may be minute, approximately rectangular holes with a long side length, i.e., a height h1, of about 1 mm. Even with this configuration, the same effects as the coil 14 formed from the coil substrate 20 shown in FIG. 6 can be obtained. In addition, a large heat transfer area for the evaporator can be ensured, resulting in even better cooling performance. As a result, excellent magnetic field generation capability can be obtained. The through-hole 121 is not limited to the above-mentioned shape, and may have, for example, another polygonal shape.

[0068] Fig. 8 is a cross-sectional view showing a coil substrate 220 of a coil 14 according to another embodiment of the present invention. That is, Fig. 8 shows a transverse cross section of the coil substrate 220. As shown in Fig. 8, the coil substrate 220 has through holes 221 formed in multiple rows substantially along the long side of the cross section.

[0069] Specifically, the coil substrate 220 has a configuration in which another refrigerant flow path, that is, the through-hole 221, is formed between the through-hole 221, which serves as a refrigerant flow path, and the outer wall surface of the coil substrate 220. Even with this configuration, it is possible to achieve the same effects as the coil substrate 20 shown in FIG.

[0070] Furthermore, the coil substrate 220 can have a larger surface area than the coil substrate 20 and the coil substrate 120 shown in Fig. 7. That is, the through holes 221 of the coil substrate 220 are configured to be provided in multiple rows, and therefore have a larger total circumferential area than the through holes 21 of the coil substrate 20 (see Fig. 6) and the through holes 121 of the coil substrate 120 (see Fig. 7).

[0071] Increasing the surface area in this way improves the magnetic field generation performance of coil 14. More specifically, coil substrate 220 is a component for passing a high-frequency current to generate a magnetic field. The current that generates the magnetic field tends to flow unevenly on the surface of coil substrate 220 due to the skin effect of the high-frequency current. Therefore, a configuration in which micropores, i.e., through-holes 221, are formed to increase the surface area is beneficial for improving the flow of high-frequency current and generating a strong electric field.

[0072] In other words, in the coil 14 made of the coil substrate 220 through which high frequency current flows, the surface area is increased by forming the through holes 221 as micropores in multiple layers, which has the advantage of effectively suppressing an increase in the DC resistance component of the impedance of the coil 14.

[0073] If the coil 14 were to cool the outside, a configuration in which the through holes 221 are formed in multiple rows would be disadvantageous in terms of heat transfer. In other words, because it is necessary to transfer the heat inside the through holes 221 to the outside of the coil substrate 220, a configuration in which other through holes 221 exist between the through holes 221 that form the refrigerant flow paths and the outer wall surface of the coil substrate 220 that forms the surface to be cooled cannot be adopted. This is because the other through holes 221 that exist between the through holes 221 and the outer wall surface of the coil substrate 220 would inhibit heat transfer.

[0074] In contrast, the refrigeration circuit 1 according to this embodiment is not intended to cool the outside, but rather to cool the coil 14, which generates a magnetic field and generates heat. Therefore, as described above, it is possible to adopt a configuration for the coil base material 220 in which the through holes 221 are formed in multiple rows, thereby achieving excellent magnetic field generation performance. In other words, it is possible to obtain a compact refrigeration circuit 1 that can stably generate a strong magnetic field for a long period of time. The through holes 221 are arranged in a generally staggered pattern, but other arrangements may also be employed.

[0075] Fig. 9 is a cross-sectional view showing a coil substrate 320 according to another embodiment of the present invention. Fig. 9 shows a transverse cross section of the coil substrate 320 of the coil 14. As shown in Fig. 9, the coil substrate 320 has a plurality of rows of through holes 321 each having a substantially triangular shape.

[0076] Specifically, a large number of through holes 321 formed in a substantially triangular shape are arranged so that their sides are parallel and close to each other. The coil base material 320 may be formed in an arrangement such that another through hole 321 exists between the outer wall surface of the coil base material 320 and one of the through holes 321.

[0077] Even with this configuration, excellent magnetic field generation performance can be obtained, similar to the coil substrate 220 already described and shown in Fig. 8. Furthermore, the through hole 321 of the coil substrate 320 can have a larger area than the through hole 221 of the coil substrate 220. Therefore, a high-performance refrigeration circuit 1 that can generate a magnetic field more efficiently can be obtained.

[0078] In the above example, the cross-sectional shape of the through holes 321 is substantially triangular, but the cross-sectional shape and arrangement of the through holes 321 are not limited to this. The cross-sectional shape of the through holes 321 can be a square, a rectangle, a trapezoid or other quadrangular shape, a pentagon, a hexagon, an ellipse, or various other shapes. Furthermore, various forms can be used for the number and arrangement style of the through holes 321.

[0079] Fig. 10 is a cross-sectional view showing a coil substrate 420 of a coil 14 according to another embodiment of the present invention. Fig. 10 shows a transverse cross section of the coil substrate 420. As shown in Fig. 10, the coil substrate 420 has a plurality of circular pipe portions 419 joined thereto.

[0080] Specifically, the circular pipe portions 419 are formed in a substantially circular pipe shape, and through holes 421 with a substantially circular cross section are formed in each of the circular pipe portions 419. The coil base material 420 is formed by joining a plurality of circular pipe portions 419 in parallel. That is, the through holes 421 are aligned in the radial direction of the winding of the coil 14 in the cross section of the coil base material 420.

[0081] 6 to 9, this configuration also allows the length of the coil 14 in the winding axis direction to be shortened, resulting in a compact, high-performance coil 14 that can generate a strong magnetic field. Because the cross section of the through hole 421 is substantially circular, it can withstand the high pressure that occurs when carbon dioxide is used as a refrigerant.

[0082] Furthermore, the circular pipe portions 419 may be joined to each other by brazing or the like after being processed into a circular pipe shape, which makes it easier to process the coil 14 and improves the productivity of the refrigeration circuit 1.

[0083] 10, the through holes 421, i.e., the circular pipe portions 419, may be arranged in a single row, or may be arranged in multiple rows (not shown). By providing multiple rows of the circular pipe portions 419, the total area of ​​the through holes 421 can be increased. Therefore, the coil 14 can generate a magnetic field more efficiently. The cross section of the circular pipe portion 419 may be circular, oval, elliptical, square pipe, or other shapes.

[0084] As described above, this embodiment has the following features. (1) A structure in which an electric current and a coolant are passed through a coil 14 having a cross-sectional shape in which through-holes 21, 121, 221, 321, 421 are formed as a plurality of minute holes that allow the coolant to circulate in a narrow area.

[0085] (2) A cooling method in which the coolant in (1) above is a hydrofluorocarbon-based or hydrofluoroolefin-based refrigerant, or carbon dioxide as a single refrigerant, or a mixture thereof.

[0086] (3) A circuit configuration of the refrigeration circuit 1 that circulates the refrigerant of (2).

[0087] (4) The configuration of the connection portion 25 between the coil 14 and the refrigerant pipe 10, which allows the refrigerant and electric current to flow.

[0088] Although not shown in the drawings, the coil 14 may be wound in a conical shape. This increases the magnetic field generated inside the conical shape relative to the current flowing through the coil 14. This allows the current flowing through the coil 14 to be relatively small, further simplifying the configuration of the refrigeration circuit 1 that cools the coil 14.

[0089] As described above, according to the embodiment of the present invention, the refrigeration circuit 1 has a structure and circuit configuration that allows the refrigerant to directly cool the coil 14. Therefore, even if a large current flows through the coil 14, it is possible to efficiently perform cooling suitable for generating a magnetic field, thereby realizing a magnetic field generator that can stably generate a predetermined magnetic field.

[0090] The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention. [Explanation of symbols]

[0091] 1 Refrigeration circuit 10 Refrigerant piping 11 Compressor 12 Condenser 13 Expansion valve 14 coils 20, 120, 220, 320, 420 coil substrate 21, 121, 221, 321, 421 through holes 22 Entrance side 23 Exit side 24 Insulating materials 25 Connection 26 Coil side joint 27 Coil side flange 28 Pipe side joint 29 Piping flange 30 Coil side insulation 31 Insulation material 32 Pipe side insulation 33 Support member 35 High frequency current generator 36 electrodes 37 electrode 38 Wiring 39 Wiring 419 Circular pipe section d1 Inner diameter t1 thickness h1 height T1 Evaporation temperature T2 condensation temperature S1 compression process S2 Heat dissipation process S3 Expansion process S4 Evaporation process

Claims

1. The compressor includes a condenser, an expansion valve, and an evaporator, which are connected via a refrigerant pipe. The evaporator is formed from a coil in which a coil base material having a plurality of through holes formed therein for allowing a refrigerant to flow is wound in a solenoid shape, The coil generates a magnetic field, the coil substrate has a rectangular cross section, and is wound in a cylindrical spiral shape such that a long side of the cross section faces a winding diameter direction of the coil and a short side of the cross section extends along a cylinder; The refrigeration circuit is characterized in that the through holes are aligned in the radial direction of the coil in the cross section.

2. 2. The refrigeration circuit according to claim 1, wherein the coil is covered with an insulating material.

3. 3. The refrigeration circuit according to claim 1, further comprising a high frequency current generator connected to the inlet and outlet sides of said coil for passing an alternating current.

4. 4. The refrigeration circuit according to claim 1, wherein joints on the inlet and outlet sides of the coil are connected to the refrigerant pipes via insulating materials.

5. 5. The refrigeration circuit according to claim 1, wherein the refrigerant is a hydrofluorocarbon, a hydrofluoroolefin, carbon dioxide, or a mixture thereof.

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