Refrigerator

Abstract

To provide a refrigerator capable of efficiently defrosting an evaporator without providing an additional facility.SOLUTION: A refrigerator includes: an evaporator 20 having a cooling tube 24 in which a refrigerant flows and a cooling fin 26 mounted to the cooling tube 24; and a defrosting heater 30 that is disposed below the evaporator 20, heats the cooling fin 26 and the cooling tube 24 to melt frost adhered and emits light having a wavelength from a visible light range to a near infrared ray range or an infrared ray range. At least a part of a surface of the cooling fin 26 is coated with a photocatalyst that activates by using light emitted from the defrosting heater 30.SELECTED DRAWING: Figure 3B

Description

[Technical Field]

[0001] The present invention relates to a refrigerator equipped with an evaporator, and more particularly to defrosting of the evaporator. [Background technology]

[0002] In refrigerators, defrosting to remove frost that has adhered to the surfaces of the evaporator's cooling fins is important to maintain the cooling performance of the evaporator. To perform defrosting efficiently, refrigerators have been proposed in which a visible-light-reactive photocatalytic film is applied to the surfaces of the evaporator's cooling fins (see, for example, Patent Document 1). In the refrigerator described in Patent Document 1, the photocatalytic film is activated by exposure to visible light, making it superhydrophilic. Because the photocatalytic film applied to the cooling fins is superhydrophilic, frost formation and granulation of ice are suppressed, and melting is leveled, allowing the defrosting action to proceed. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2010-261669 Summary of the Invention [Problem to be solved by the invention]

[0004] However, the refrigerator described in Patent Document 1 needs to be provided with a defrost heater that heats the evaporator, as well as a light source that irradiates the photocatalyst with visible light above the evaporator, which increases manufacturing costs, restricts the flow path space through which the cool air that has passed through the evaporator flows, and makes control more complicated.

[0005] Therefore, an object of the present invention is to solve the above-mentioned problems and to provide a refrigerator that can efficiently defrost an evaporator without providing any additional equipment. [Means for solving the problem]

[0006] In order to achieve the above object, the first aspect of the present invention is an evaporator having cooling tubes through which a refrigerant flows and cooling fins attached to the cooling tubes; a defrosting heater disposed below the evaporator, for heating the cooling fins and the cooling tubes to melt frost that has adhered thereto, the defrosting heater emitting light with a wavelength ranging from the visible light region to the near-infrared region or the infrared region; Equipped with In the refrigerator, at least a part of the surface of the cooling fin is coated with a photocatalyst that is activated by light emitted from the defrost heater.

[0007] In this embodiment, the defrost heater that heats the evaporator to defrost emits light with a wavelength ranging from the visible light region to the near-infrared region or the infrared region, and the photocatalyst coated on the cooling fins of the evaporator is activated by the light emitted from the defrost heater, becoming superhydrophilic and promoting defrosting. Thus, the evaporator can be defrosted efficiently without the need for additional equipment such as a light source.

[0008] In addition, a second aspect of the present invention is the first aspect, a drip-proof cover is disposed above the rod-shaped defrost heater along the longitudinal direction of the defrost heater; When viewed from the side in the longitudinal direction, the refrigerator has a reflective surface disposed in the area above that is not covered by the drip-proof cover, which reflects light emitted from the defrost heater upward.

[0009] A drip-proof cover is disposed above the defrost heater to prevent defrost water, which melts frost adhering to the evaporator, from falling and hitting the defrost heater. Light emitted upward from the defrost heater is blocked by the drip-proof cover and does not reach the photocatalyst coated on the cooling fins. However, in this embodiment, reflective surfaces are disposed in the outer regions on both sides that are not covered by the drip-proof cover. These reflective surfaces can reflect light emitted from the defrost heater laterally or obliquely to the side upward, allowing the reflected light to hit the photocatalyst coated on the cooling fins or the like and activate it.

[0010] In addition, a third aspect of the present invention is the first aspect, a drip-proof cover is disposed above the rod-shaped defrost heater along the longitudinal direction of the defrost heater; In a side view seen from the longitudinal direction, the thin plate constituting the drip-proof cover has a downwardly convex shape with the center of the defrost heater as its lowest point.

[0011] In this aspect, in a side view seen from the longitudinal direction, the thin plate constituting the drip-proof cover arranged above the defrost heater has a downwardly convex shape with its lowest point at the center of the defrost heater. Therefore, light emitted from the defrost heater travels upward along the lower surface of the drip-proof cover, the outer side of which is higher, and can travel above the drip-proof cover without being interfered with by the drip-proof cover. The light traveling upward is reflected by the inner wall of the cooling flow path, etc., and hits and activates the photocatalyst coated on the cooling fins, etc.

[0012] Moreover, a fourth aspect of the present invention is the third aspect, In a side view from a direction perpendicular to the longitudinal direction, the upper surface of the drip-proof cover has a slope that is higher in the center and lower at both ends, or higher at one end and lower at the other end.

[0013] The drip-proof cover of the third aspect has a downwardly convex shape with the center as its lowest point, which may cause defrost water dripping from the evaporator to accumulate on the top surface of the drip-proof cover. To address this issue, in this aspect, the top surface of the drip-proof cover is formed with a slope that is higher in the center and lower at both ends, or higher at one end and lower at the other, when viewed from the side perpendicular to the longitudinal direction. This allows defrost water dripping from the evaporator to flow outward along the slope and outward.

[0014] In addition, a fifth aspect of the present invention is the first aspect, a drip-proof cover is disposed above the rod-shaped defrost heater along the longitudinal direction of the defrost heater; 2. The refrigerator according to claim 1, wherein the drip-proof cover is translucent.

[0015] In this embodiment, since the drip-proof cover is translucent, the light emitted upward from the defrost heater is not blocked by the drip-proof cover, but passes through the drip-proof cover and travels upward, where it hits the photocatalyst coated on the cooling fins, etc., and is activated. [Effects of the Invention]

[0016] As described above, in this aspect, it is possible to provide a refrigerator that can efficiently defrost the evaporator without providing any additional equipment. [Brief explanation of the drawings]

[0017] [Figure 1] 1 is a perspective view schematically illustrating an example of the external shape of a refrigerator according to an embodiment of the present invention. [Figure 2] FIG. 2 is a diagram showing a cross section AA in FIG. 1, and is a side cross-sectional view that schematically shows the internal structure of a refrigerator. [Figure 3A] 3 is a side view schematically showing the defrosting mechanism according to the first embodiment of the present invention, with the area of ​​the evaporator and the defrost heater shown in FIG. 2 enlarged. FIG. [Figure 3B] FIG. 3B is a side view showing the arrow CC in FIG. 3A. [Figure 4A] 3B is a side view of the same area as in FIG. 3A, seen from the same direction, and is a diagram schematically showing a defrosting mechanism according to a second embodiment of the present invention. FIG. [Figure 4B] FIG. 4B is a side view taken along the arrow DD in FIG. 4A. [Figure 4C] 4B is a side view taken along the arrow DD in FIG. 4A, showing a modified example of the second embodiment. FIG. [Figure 5] 3B is a side view of the same area as in FIG. 3A, seen from the same direction, and is a side view schematically showing a defrosting mechanism according to a third embodiment of the present invention. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0018] Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. In each drawing, corresponding components having the same function are assigned the same reference numerals. For convenience, the embodiments may be shown separately in consideration of ease of explanation or understanding of the main points, but partial substitution or combination of configurations shown in different embodiments is possible. In the embodiments described below, descriptions of matters common to the above-mentioned embodiments will be omitted, and only differences will be described. In particular, similar effects due to similar configurations will not be mentioned sequentially in each embodiment. The size and positional relationship of components shown in the drawings may be exaggerated for clarity of explanation. In the drawings and the following description, the refrigerator is placed on a horizontal surface, the side with the door is the front side, the opposite side is the rear side, and left and right are indicated when facing the door.

[0019] (Refrigerator according to an embodiment of the present invention) First, an overview of a refrigerator according to an embodiment of the present invention will be described with reference to Fig. 1 and Fig. 2. Fig. 1 is a perspective view that schematically shows an example of the external shape of a refrigerator according to an embodiment of the present invention. Fig. 2 is a view showing section AA of Fig. 1, and is a side cross-sectional view that schematically shows the internal structure of the refrigerator. Note that Fig. 2 illustrates an example in which the refrigerator has a defrosting mechanism shown in Figs. 3A and 3B.

[0020] A refrigerator 2 according to an embodiment of the present invention includes a freezer compartment 6A below a housing 4A and a refrigerator compartment 6B above the housing 4A. An openable lower door 8A is provided at the front opening of the freezer compartment 6A. An openable upper door 8B is provided at the front opening of the refrigerator compartment 6B.

[0021] A cooling flow path 4B separated by a partition plate is disposed at the rear of the interior of the refrigerator 2. An evaporator 20 and a cooling fan 40 that circulates the gas cooled by the evaporator 20 inside the interior of the refrigerator are disposed in the cooling flow path 4B. Furthermore, dampers 42A and 42B are disposed to switch between allowing or preventing the gas cooled by the evaporator 20 from flowing into the freezer compartment 6A and the refrigerator compartment 6B.

[0022] The compressor 10 and the condenser 12 that constitute the refrigeration circuit 50 are disposed in a machine room 4C located at the lower rear of the refrigerator 2. Furthermore, a fan for cooling the compressor 10, the condenser 12, etc. is also disposed in the machine room 4C. The condenser 12 and the evaporator 20 are connected by a capillary tube 14, and the evaporator 20 and the compressor 10 are connected by a suction pipe 16. As described above, the refrigeration circuit 50 of the refrigerator 2 according to this embodiment is mainly composed of the compressor 10, the condenser 12, the capillary tube 14, the evaporator 20, the suction pipe 16, and other pipes that connect these components.

[0023] The cooling cycle in which refrigerant circulates through the cooling circuit 50 to cool the evaporator 20 is as follows: High-temperature, high-pressure gaseous refrigerant discharged from the compressor 10 flows through the condenser 12. The refrigerant's temperature drops due to heat dissipation in the condenser 12, becoming a liquid or a gas-liquid mixture. This liquid or gas-liquid mixture flows through the capillary tube 14, where it is decompressed and enters the evaporator 20 as a low-temperature, low-pressure gas-liquid mixture. This refrigerant vaporizes between the cooling fins of the evaporator 20, absorbing heat from the gas flowing around the cooling tubes. The cooled air, cooled as it flows between the cooling fins, flows into the freezer compartment 6A and the refrigerator compartment 6B, cooling the storage areas. The vaporized refrigerant in the evaporator 20 returns to the suction side of the compressor 10 through the suction pipe 16, and this cooling cycle is repeated.

[0024] (Defrosting mechanism according to an embodiment of the present invention) Next, a general description of a defrosting mechanism according to an embodiment of the present invention will be given with reference to Figures 3A and 3B. Figure 3A is a side view schematically showing a defrosting mechanism according to a first embodiment of the present invention, with an enlarged view of the evaporator and defrost heater shown in Figure 2. Figure 3B is a side view taken along the arrow CC in Figure 3A. Figures 3A and 3B are views showing the defrosting mechanism according to the first embodiment, but first, matters common to all of the first to third embodiments will be described with reference to Figures 3A and 3B.

[0025] <Evaporator> First, the structure of the evaporator 20 will be described with reference to FIG. 3B. As shown in FIG. 3B, cooling tubes 24 are attached to the left and right frames 22 so as to extend vertically and snake laterally. A plurality of thin cooling fins 26 are attached to the cooling tubes 24. The cooling tubes 24 and the cooling fins 26 are formed of a metal material with high thermal conductivity. A cooling circuit 50 causes a refrigerant to flow through the cooling tubes 24. The refrigerant flows from top to bottom while snaked laterally through the cooling tubes 24, makes a U-turn at the lowest position, and flows from bottom to top while snaked laterally through the cooling tubes 24 before flowing out of the evaporator 20. In FIG. 3, the cooling tubes 24 through which the refrigerant flows from top to bottom and the cooling tubes 24 through which the refrigerant flows from bottom to top are shown overlapping.

[0026] When the gas inside the refrigerator is moved by the cooling fan 40 and passes between the multiple cooling fins 26, it is cooled by exchanging heat with the cooling fins 26 and the cooling tubes 24. When the gas inside the refrigerator flows between the cooling fins 26 of the evaporator 20, the moisture contained in the gas freezes and becomes frost, which adheres to the surfaces of the cooling fins 26 and the cooling tubes 24. If a lot of frost accumulates on the evaporator 20 in this way, the gas cooling efficiency decreases. For this reason, it is preferable to make it difficult for frost to accumulate on the evaporator 20, and it is necessary to periodically defrost the evaporator 20 using a defrost heater.

[0027] <Defrost heater> A rod-shaped defrost heater 30 is disposed below the evaporator 20 to melt frost adhering to the cooling fins 26 and the cooling tubes 24. The defrost heater 30 has a structure in which a heating element is disposed inside a rod-shaped quartz glass tube. The defrost heater 30 is disposed so as to cover the entire left-right area of ​​the evaporator 20. By turning on the defrost heater 30, the evaporator 20 is heated and the frost adhering to the evaporator 20 can be melted.

[0028] A liquid receiving surface 44 is disposed below the defrost heater 30 to receive defrost water generated when frost adhering to the cooling fins 26 and cooling tubes 24 of the evaporator 20 melts. A drain pipe 46 is attached to an opening provided in this liquid receiving surface 44, and the lower end of the drain pipe 46 opens above an evaporation tray disposed in the machine room 4C. As a result, the defrost water that has been melted by the defrost heater 30 and dropped from the cooling fins 26 and cooling tubes 24 of the evaporator 20 flows into an evaporation tray 48 via the drain pipe 46. The defrost water that has flowed into the evaporation tray 48 evaporates into the atmosphere.

[0029] <Waterproof cover> In addition, a drip-proof cover 32 is arranged above the rod-shaped defrost heater 30 along the longitudinal direction of the defrost heater 30. The drip-proof cover 32 prevents defrost water that drops from the cooling fins 26 and cooling tubes 24 of the evaporator 20 from hitting the defrost heater 30 and causes it to fall onto the liquid-receiving surface 44 below. This prevents the defrost heater 30 from being damaged when it becomes hot.

[0030] The drip-proof cover 32 can be formed, for example, from a thin metal plate such as aluminum. As shown in FIG. 3A , in a side view of the rod-shaped defrost heater 30 in the longitudinal direction (left-right direction), the thin plate constituting the drip-proof cover 32 has an upwardly convex curved shape with the center at the top. Note that the drip-proof cover 32 may also have an upwardly convex shape formed by an inclined surface that is nearly flat. As a result, defrost water dropping from the cooling fins 26 and cooling tubes 24 of the evaporator 20 flows outward (to the front and rear) along the upper surface of the drip-proof cover 32 and falls onto the liquid-receiving surface 44 below. Because the drip-proof cover 32 is not translucent, the radiant heat from the defrost heater 30 to the evaporator 20 is partially blocked by the drip-proof cover 32, but sufficient heating can be achieved, including by convective heat transfer. The drip-proof cover 32 of the first embodiment shown in FIG. 3A is similar to a conventional drip-proof cover, whereas drip-proof covers 70 (70′), 80 of the second and third embodiments described below are different from conventional drip-proof covers.

[0031] <Photocatalyst> As described above, in order to maintain high cooling efficiency by the evaporator 20, it is desirable to make it difficult for frost to adhere to the evaporator 20 and to perform efficient defrosting by the defrost heater 30. To address this, in this embodiment, the surfaces of the cooling fins 26 and the cooling tubes 24 are coated with a photocatalyst.

[0032] The photocatalyst used in this embodiment is activated by light with a wavelength ranging from visible light to the near-infrared or infrared region. Here, near-infrared light has a wavelength of approximately 700 to 2500 nm, while infrared light has a longer wavelength. Examples of photocatalysts that are activated by light with a wavelength ranging from visible light to the near-infrared or infrared region include tungsten oxide, or a composite of black phosphorus, gold nanoparticles, and lanthanum titanate.

[0033] In the illustrated example, the entire surfaces of the cooling fins 26 and the cooling tubes 24 are coated with the photocatalyst, but this is not limited to this. For example, only the cooling fins 26 may be coated, or partial areas of the cooling fins 26 and the cooling tubes 24 may be coated, or only partial areas of the cooling fins 26 may be coated. In this embodiment, at least a portion of the surface of the cooling fins 26 is coated with the photocatalyst to promote defrosting of the evaporator 20.

[0034] By coating at least a portion of the surface of the cooling fins 26 with the above-described photocatalyst, the photocatalyst can be activated by light with wavelengths ranging from the visible light region to the near-infrared light region or the infrared light region emitted from the defrost heater 30. Activation of the coated photocatalyst makes it superhydrophilic. Therefore, effective defrosting of the evaporator 20 can be achieved by heating with the defrost heater 30. However, if the cooling fins are coated with a conventional photocatalyst that is activated by visible light, the light emitted from the defrost heater 30 will not make them superhydrophilic.

[0035] As described above, the refrigerator 2 according to the embodiment of the present invention having the above-described defrosting mechanism comprises an evaporator 20 having cooling tubes 24 through which a refrigerant flows and cooling fins 26 attached to the cooling tubes 24, and a defrost heater 30 that is disposed below the evaporator 20 and heats the cooling fins 26 and the cooling tubes 24 to melt any frost that has adhered thereto, and that emits light having a wavelength ranging from the visible light range to the near-infrared range or the infrared range, and at least a portion of the surface of the cooling fins 26 is coated with a photocatalyst that is activated by the light emitted from the defrost heater 30.

[0036] The defrost heater 30, which heats the evaporator 20 to defrost it, emits light with a wavelength ranging from the visible light region to the near-infrared region or the infrared region, and the photocatalyst coated on the cooling fins 26 and the like of the evaporator 20 is activated by the light emitted from the defrost heater 30 and becomes superhydrophilic, thereby accelerating defrosting of the evaporator 20. Therefore, it is possible to provide a refrigerator 2 that can efficiently defrost the evaporator 20 without providing any additional equipment.

[0037] (Defrosting mechanism according to the first embodiment of the present invention) Next, a defrosting mechanism according to a first embodiment of the present invention will be described with reference to Figures 3A and 3B. In the first embodiment, at least a portion of the surface of the cooling fins 26 is coated with a photocatalyst that is activated by light emitted from the defrost heater 30. In addition, a drip-proof cover 32 similar to that of a conventional device is disposed above the defrost heater 30 along the longitudinal direction (left-right direction) of the defrost heater 30.

[0038] 3A, in a side view seen from the longitudinal direction (left-right direction) of the defrost heater 30, a reflecting member 60 having a reflecting surface 62 that reflects light emitted from the defrost heater 30 upward is disposed in an area not covered by the drip-proof cover 32 above as indicated by arrow B. The reflecting member 60 is preferably formed from a metal plate such as aluminum that has high heat resistance and high reflectivity.

[0039] The illustrated reflecting surface 62 is disposed at an elevation angle of approximately 45 degrees relative to the horizontal plane. However, the elevation angle can be selected at any angle depending on the arrangement of the evaporator 20, the defrost heater 30, and the drip-proof cover 32. For example, an elevation angle ranging from 20 degrees to 70 degrees can be exemplified. In the drawing, the reflecting surface 62 has a flat shape, but this is not limited thereto. The reflecting surface 62 may have a curved shape or a surface shape that is a combination of a flat shape and a curved shape.

[0040] In the illustrated example, individual reflective members 60 are arranged in the outer region not covered by the drip-proof cover 32, but both reflective members 60 may also have an integrated structure in which they are connected. In that case, a structure may be considered in which a member is provided that connects both reflective members 60 partially in the longitudinal direction (left-right direction) of the defrost heater 30 so that defrost water dropping from the evaporator 20 can pass through. Also considered are a structure in which the member connecting both reflective members 60 has a plurality of through-holes that allow defrost water dropping from the evaporator 20 to pass through, or a structure in which both reflective members 60 are connected by a mesh-like member.

[0041] 3A, light emitted upward from the defrost heater 30 hits and is reflected by the upper drip-proof cover 32. However, light emitted sideways or diagonally to the side from the defrost heater 30 hits and is reflected by a reflecting surface 62 arranged in an outer area (see arrow B) not covered by the drip-proof cover 32 and travels upward. By setting an appropriate elevation angle of the reflecting surface 62, the reflected light can be made to reach the evaporator 20 arranged above the drip-proof cover 32.

[0042] Therefore, the photocatalyst coated on the surfaces of the cooling fins 26 can be activated by irradiating it with light emitted upward from the defrost heater 30. This makes the surfaces of the cooling fins 26 superhydrophilic, facilitating defrosting of the evaporator 20.

[0043] As described above, in the defrosting mechanism according to the first embodiment of the present invention, a drip-proof cover 32 is arranged above the rod-shaped defrost heater 30 along the longitudinal direction (left-right direction) of the defrost heater 30, and in a side view from the longitudinal direction (left-right direction), a reflective surface 62 that reflects light emitted from the defrost heater 30 upward is arranged in the area not covered by the drip-proof cover 32.

[0044] Such a reflecting surface 62 can reflect the light emitted from the defrost heater 30 upward, and the reflected light can be incident on the photocatalyst coated on the cooling fins 26 or the like to activate it.

[0045] (Defrosting mechanism according to a second embodiment of the present invention) Next, a defrosting mechanism according to a second embodiment of the present invention will be described with reference to Figures 4A, 4B, and 4C. Figure 4A is a side view of the same area as in Figure 3A, seen from the same direction, and is a diagram schematically showing a defrosting mechanism according to the second embodiment of the present invention. Figure 4B is a side view taken along the arrow DD in Figure 4A. Figure 4C is a side view taken along the arrow DD in Figure 4A, and is a diagram showing a modified example of the second embodiment.

[0046] In the second embodiment as well, at least a portion of the surface of the cooling fin 26 is coated with a photocatalyst that is activated by light emitted from the defrost heater 30. In the first embodiment, a drip-proof cover 32 of a similar shape to the conventional one is provided above the defrost heater 30 along the longitudinal direction (left-right direction) of the defrost heater 30, but in the second embodiment, a drip-proof cover 70 (70') of a different shape from the conventional one is provided. On the other hand, the second embodiment does not include a reflective member 60 as in the first embodiment.

[0047] In the second embodiment, as shown in FIG. 4A, in a side view seen from the longitudinal direction (left-right direction), the thin plate constituting the drip-proof cover 70 (70') has a downwardly convex shape with its lowest point at the center of the defrost heater 30. In other words, it has a convex shape that is upside down compared to the conventional drip-proof cover 32. The drip-proof cover 70 can also be formed from a thin metal plate such as aluminum. Note that although the drip-proof cover 70' represents a modification of the second embodiment, the drip-proof cover 70 and the drip-proof cover 70' have similar shapes in a side view seen from the longitudinal direction (left-right direction).

[0048] With the drip-proof cover 70 (70') having such a shape, as shown schematically by the dotted arrow in Fig. 4A, light emitted diagonally upward from the defrost heater 30 travels along the lower surface of the drip-proof cover 70, the outer side of which is higher, and can travel above the drip-proof cover 70 without being interfered with by the drip-proof cover 70. The light traveling upward is reflected by the inner wall of the cooling flow path 4B, etc., and can reach the photocatalyst coated on the cooling fins 26, etc.

[0049] In the illustrated example, the drip-proof cover 70 has a downwardly convex shape with a flat inclined surface, but this is not limited to this. The drip-proof cover 70 may also have a curved surface or a surface shape that is a combination of a flat surface and a curved surface.

[0050] 4A, reflective members 72 having reflective surfaces 74 can be disposed on both the left and right sides of the evaporator 20. In this case, light that travels above the drip-proof cover 70 can be more efficiently reflected by the reflective surfaces 74 of the reflective members 72 and directed toward the photocatalyst coated on the cooling fins 26, etc.

[0051] The downward convex shape of the drip-proof cover 70 (70') as shown in Figure 4A allows the light emitted from the defrost heater 30 to be directed at the photocatalyst coated on the cooling fins 26, etc., but with this shape, there is a risk that the defrost water that falls from the evaporator 20 will not flow downward and will accumulate on the upper surface of the drip-proof cover 70.

[0052] To address this issue, in this embodiment, as shown in Fig. 4B, the upper surface of the drip-proof cover 70 is inclined so that it is higher in the center and lower at both ends when viewed from the side in a direction perpendicular to the longitudinal direction (front-rear direction). As schematically shown by the dashed-dotted arrows in Fig. 4B, the defrost water that drops from the evaporator 20 flows to both the left and right sides and drops from both ends of the drip-proof cover 70 onto the liquid-receiving surface 44 below.

[0053] The structure for draining the defrost water dropped from the evaporator 20 is not limited to this. For example, as in a modified example shown in Fig. 4C, the upper surface of the drip-proof cover 70 can be formed so as to have an inclination in which one end (left end) is higher and the other end (right end) is lower in a side view seen from a direction perpendicular to the longitudinal direction (front-rear direction). As a result, as schematically shown by the dashed-dotted arrow in Fig. 4C, the defrost water dropped from the evaporator 20 flows from the left to the right and falls from the right end of the drip-proof cover 70 onto the liquid-receiving surface 44 below. Note that the direction of the inclination may be reversed.

[0054] In Fig. 4B, the upper surface of the drip-proof cover 70 has a curved shape, but this is not limited thereto, and the upper surface of the drip-proof cover 70 may have a flat shape or a surface shape that is a combination of a flat shape and a curved shape. In Fig. 4C, the upper surface of the drip-proof cover 70' has a flat shape, but this is not limited thereto, and the upper surface of the drip-proof cover 70' may have a curved shape or a surface shape that is a combination of a flat shape and a curved shape.

[0055] As described above, in the second embodiment, the drip-proof cover 70 (70') is arranged above the rod-shaped defrost heater 30 along the longitudinal direction (left-right direction) of the defrost heater 30, and when viewed from the side in the longitudinal direction (left-right direction), the thin plate constituting the drip-proof cover 70 (70') has a downwardly convex shape with its lowest point at the center position of the defrost heater 30.

[0056] Therefore, the light emitted from the defrost heater 30 travels upward along the underside of the drip-proof cover 70 (70'), which has a higher outer surface, and can travel above the drip-proof cover 70 (70') without being interfered with by the drip-proof cover 70 (70'). The light that travels upward is reflected by the inner wall of the cooling flow path 4B and the reflecting surface 74 of the reflecting member 72, and can be activated by hitting the photocatalyst coated on the cooling fins 26, etc.

[0057] The drip-proof cover 70 (70') according to the second embodiment has a downwardly convex shape with the center position as the lowest point, and therefore there is a risk that defrost water dropping from the evaporator 20 may accumulate on the upper surface of the drip-proof cover 70 (70'). To address this issue, in the present embodiment, when viewed from the side in a direction perpendicular to the longitudinal direction of the defrost heater 30 (front-rear direction), the upper surface of the drip-proof cover 70 has an inclination that is higher in the center and lower at both ends (see FIG. 4B), or the upper surface of the drip-proof cover 70' has an inclination that is higher at one end and lower at the other end (see FIG. 4C). This allows the defrost water dropping from the evaporator 20 to flow along the inclination and discharge downward.

[0058] (Defrosting mechanism according to a third embodiment of the present invention) Next, a defrosting mechanism according to a third embodiment of the present invention will be described with reference to Fig. 5. Fig. 5 is a side view of the same area as Fig. 3A, seen from the same direction, and is a side view that schematically shows the defrosting mechanism according to the third embodiment of the present invention.

[0059] In the third embodiment as well, at least a portion of the surface of the cooling fin 26 is coated with a photocatalyst that is activated by light emitted from the defrost heater 30. Also in the third embodiment as well, a drip-proof cover 80 is arranged above the defrost heater 30 along the longitudinal direction (left-right direction) of the defrost heater 30, but does not include a reflective member 60 as in the first embodiment.

[0060] The drip-proof cover 80 of the third embodiment has an upwardly convex shape with the uppermost point at the center, similar to the conventional drip-proof cover 32 shown in Fig. 3A, in a side view seen from the longitudinal direction (left-right direction) of the defrost heater 30. Therefore, the defrost water that drops from the evaporator 20 flows outward along the slope of the drip-proof cover 80, and can be discharged downward.

[0061] Furthermore, the drip-proof cover 80 is translucent. As a result, as schematically shown by the dotted arrow in Fig. 5 , light emitted upward from the defrost heater 30 can pass through the upper drip-proof cover 80 and reach the evaporator 20.

[0062] Since the drip-proof cover 80 is disposed near the defrost heater 30, it is preferable to form it from a light-transmitting quartz glass material, for example, taking heat resistance into consideration. However, the material is not limited to this, and it can also be formed from a light-transmitting heat-resistant resin material. The drip-proof cover 80 can be transparent or slightly colored.

[0063] As described above, in the third embodiment, the drip-proof cover 80 is disposed above the rod-shaped defrost heater 30 along the longitudinal direction (left-right direction) of the defrost heater 30, and the drip-proof cover 80 is translucent. This allows light emitted upward from the defrost heater 30 to pass through the drip-proof cover 80 without being blocked by it, and to travel upward, where it hits the photocatalyst coated on the cooling fins 26 and the like, and is activated.

[0064] Although the embodiments and modes of implementation of the present invention have been described, the disclosed contents may vary in the details of the configuration, and changes in the combination and order of elements in the embodiments and modes of implementation may be realized without departing from the scope and spirit of the claimed invention. [Explanation of symbols]

[0065] 2. Refrigerator 4A housing 4B Cooling channel 4C Machine room 6A Freezer 6B Refrigerator Doors 8A and 8B 10 Compressor 12 Condenser 14 Capillary tube 16 Suction pipe 20 Evaporator 22 frames 24 cooling tubes 26 Cooling fins 30 Defrost heater 32 Drip-proof cover 40 Cooling fan 42A, 42B damper 44 Liquid receiving surface 46 Drain pipe 48 Evaporating dish 50 Cooling circuit 60 Reflective material 62 Reflective surface 70,70' Drip-proof cover 72 Reflective material 74 Reflective surface 80 Drip-proof cover

Claims

1. an evaporator having cooling tubes through which a refrigerant flows and cooling fins attached to the cooling tubes; a defrosting heater disposed below the evaporator, which heats the cooling fins and the cooling tubes to melt frost that has adhered thereto, and which emits light with a wavelength ranging from the visible light region to the near-infrared region or the infrared region; Equipped with A refrigerator characterized in that at least a part of the surface of the cooling fin is coated with a photocatalyst that is activated by light emitted from the defrost heater.

2. a drip-proof cover is disposed above the rod-shaped defrost heater along the longitudinal direction of the defrost heater; The refrigerator according to claim 1, characterized in that, in a side view from the longitudinal direction, a reflective surface that reflects light emitted from the defrost heater upward is disposed in an area not covered by the drip-proof cover above.

3. a drip-proof cover is disposed above the rod-shaped defrost heater along the longitudinal direction of the defrost heater; The refrigerator according to claim 1, wherein, in a side view from the longitudinal direction, the thin plate constituting the drip-proof cover has a downwardly convex shape with its lowest point being the center position of the defrost heater.

4. The refrigerator according to claim 3, wherein, in a side view from a direction perpendicular to the longitudinal direction, the upper surface of the drip-proof cover has a slope that is higher in the center and lower at both ends, or a slope that is higher at one end and lower at the other end.

5. a drip-proof cover is disposed above the rod-shaped defrost heater along the longitudinal direction of the defrost heater; 2. The refrigerator according to claim 1, wherein the drip-proof cover is light-transmitting.

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