US20110138834A1

US20110138834A1 - Refrigerating apparatus and storge device using the same

Info

Publication number: US20110138834A1
Application number: US12/944,513
Authority: US
Inventors: Toshiki Maeda
Original assignee: Panasonic Corp
Current assignee: Panasonic Corp
Priority date: 2009-12-10
Filing date: 2010-11-11
Publication date: 2011-06-16
Also published as: CN102095300A; JP2011122762A

Abstract

A refrigerating apparatus is provided with a cooling unit whose height is greater than width when installed; and a defrosting device for defrosting frost formed on the cooling unit by heat, the defrosting device being in a straight pipe form, wherein the defrosting device is provided in a vertical direction on a side of the cooling unit. By providing the defrosting device in a straight pipe form in the vertical direction on the side of the cooling unit that is long in a longitudinal direction, it is possible to increase the length of the defrosting device and to lower a surface temperature of the defrosting device. Further, as the defrosting device is long, an amount of heat generation is large and defrosting efficiency is high. Moreover, it is possible to manufacture the defrosting device at a low cost as the defrosting device is in a straight pipe form.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention
The present invention relates to a refrigerating apparatus provided with a defrosting device, and a storage device utilizing the refrigerating apparatus.
2. Description of the Related Art
As an example of refrigerating apparatuses provided with a defrosting device, a refrigerating apparatus disclosed in Unexamined Japanese Patent Publication No. 2002-5553 is described. FIG. 9 shows a cross-sectional view of a main part of the refrigerator disclosed in Publication No. 2002-5553.
Referring to FIG. 9, refrigerator 120 is provided with freezing chamber 121 at its lowermost part. Freezing chamber door 122 is provided on a front side of freezing chamber 121. Refrigerating chamber 123 is disposed above freezing chamber 121. Refrigerating chamber door 124 is provided on a front side of refrigerating chamber 123.
Refrigerator 120 is provided with refrigerating apparatus 125 at its back side bottom (on a right side in FIG. 9). Fan 127 is provided above refrigerating apparatus 125. Glass tube heater 126 as a defrosting device is provided at a bottom of refrigerating apparatus 125. Metallic protective plate 128 is provided above glass tube heater 126.
Refrigerating apparatus 125 is cooled by circulation of a refrigerant encapsulated in refrigerating apparatus 125. By an operation of fan 127, a cold air near refrigerating apparatus 125 is blown to freezing chamber 121 and refrigerating chamber 123. In this manner, freezing chamber 121 and refrigerating chamber 123 are cooled.
Here, the air subject to heat exchange and cooling by refrigerating apparatus 125 is an internal air within freezing chamber 121 or refrigerating chamber 123, or an external air that enters while opening freezing chamber door 122 or refrigerating chamber door 124. The internal air is humid as it includes moisture evaporated from food reserved in freezing chamber 121 or in refrigerating chamber 123. Further, a temperature of the external air is higher than that of the internal air. By cooling the high-temperature external air or the high-humidity internal air, frost occurs and deposits on refrigerating apparatus 125. A phenomenon that the frost occurs and deposits is called as frost formation.
If the frost forms on refrigerating apparatus 125, in particular at its heat exchanging surface, the heat exchange, that is, the cooling of the air is hindered. The frost formation also hinders ventilation by fan 127, and an air volume decreases. This causes insufficient cooling. In order to solve the problem of insufficient cooling, the refrigerator disclosed in Publication No. 2002-5553 suppresses the occurrence of the frost, or defrosts the frost that has occurred using glass tube heater 126.
However, when the height of refrigerating apparatus 125 is high, time required for the heat of glass tube heater 126 to reach an upper part of refrigerating apparatus 125 increases. In other words, the time required for defrosting increases.
Further, if the refrigerant is a flammable refrigerant, a surface temperature of glass tube heater 126 is required to be under the ignition temperature of the flammable refrigerant. Lowering the surface temperature of glass tube heater 126 also decreases an amount of heat generation of glass tube heater 126. Consequently, the time required for defrosting further increases.
There is known a defrosting device with decreased time for defrosting, where a heater is provided along the heat exchanging surface of refrigerating apparatus 125. For such a heater, a pipe heater formed by inserting a wire heater into a metallic pipe and bending the metallic pipe is used, instead of glass tube heater 126. However, the pipe heater is expensive, as it requires a higher material cost and a processing cost.

SUMMARY OF THE INVENTION

An object of the present invention is to provide an inexpensive refrigerating apparatus with high defrost efficiency even when a surface temperature of a defrosting device is low.
A refrigerating apparatus according to the present invention is provided with a cooling unit whose height is greater than width when installed; and a defrosting device for defrosting frost formed on the cooling unit by heat, the defrosting device being in a straight pipe form, wherein the defrosting device is provided in a vertical direction on a side of the cooling unit. By providing the defrosting device in a straight pipe form in the vertical direction on the side of the cooling unit that is long in a longitudinal direction, it is possible to increase the length of the defrosting device and to lower the surface temperature of the defrosting device. Further, as the defrosting device is long, an amount of heat generation is large and defrosting efficiency is high. Moreover, it is possible to manufacture the defrosting device at a low cost as the defrosting device is in a straight pipe form.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 shows a front elevational view of a refrigerating apparatus according to a first embodiment of the present invention;

FIG. 2 shows a cross-sectional view of a defrosting device of the refrigerating apparatus according to the first embodiment;

FIG. 3 shows a front elevational view of another refrigerating apparatus according to the first embodiment;

FIG. 4 shows a cross-sectional view of a defrosting device of a refrigerating apparatus according to a second embodiment of the present invention;

FIG. 5 shows a cross-sectional view of a defrosting device of a refrigerating apparatus according to a third embodiment of the present invention;

FIG. 6 shows a front elevational view of a refrigerating apparatus according to a fourth embodiment of the present invention;

FIG. 7 shows a front elevational view of another refrigerating apparatus according to the fourth embodiment;

FIG. 8 shows a configurational diagram of a storage device according to a fifth embodiment of the present invention; and

FIG. 9 shows a cross-sectional view of a main part of the conventional refrigerator.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

First Embodiment

FIG. 1 shows a front elevational view of a refrigerating apparatus according to a first embodiment of the present invention. FIG. 2 shows a cross-sectional view of a defrosting device of the refrigerating apparatus.
Referring to FIG. 1, refrigerating apparatus 1 is provided with cooling unit 2 and defrosting device 5 in a straight pipe form. Cooling unit 2 is provided with a plurality of cooling fins 3 and refrigerant pipe 4. Specifically, cooling unit 2 is configured such that metallic cooling pipe 4 that is bent in a meandering manner passes through holes (not shown) provided for each cooling fin 3.
Cooling unit 2 is in a rectangular shape whose height A is 340 mm and width B is 240 mm. In other words, cooling unit 2 is longitudinally elongated. As shown in FIG. 1, cooling unit 2 is provided in the longitudinal direction, and defrosting device 5 is provided in a vertical direction. Defrosting device 5 is fixed by member 2 a at a predetermined interval from cooling unit 2.
Referring to FIG. 2, defrosting device 5 is provided with glass tube 6, wire heater 7 disposed within glass tube 6, leads 10 connected to wire heater 7, cap 11 covering an upper opening of glass tube 6, and cap 12 covering a lower opening of glass tube 6. Wire heater 7 includes heat generating unit 8 that is configured by a metal resistant body, and lead units 9. Heat generating unit 8 is configured by, for example, an iron chrome wire whose diameter is 0.21 mm and that is processed into a coiled form (i.e., spiral form). Further, heat generating unit 8 of wire heater 7 is electrically connected to leads 10 respectively via lead units 9. Here, cap 11 and cap 12 are heated by heat from wire heater 7. Cap 11 and cap 12 are disposed at a predetermined interval from heat generating unit 8 so that temperatures of cap 11 and cap 12 do not exceed an upper limit of an operating temperature of cap 11 and cap 12.
The following describes defrosting of cooling unit 2 by defrosting device 5. By conducting electricity to defrosting device 5 using leads 10, heat generating unit 8 of wire heater 7 generates heat. By transferring radiation heat from heat generating unit 8 to refrigerant pipe 4 or to cooling fin 3, the frost formed on cooling unit 2 melts, and thus the defrosting is carried out.
As shown in FIG. 1, defrosting device 5 is provided on a side of cooling unit 2 in the vertical direction (i.e., longitudinally provided). Total length C of heat generating unit 8 of wire heater 7 can be configured as high as height A of cooling unit 2. In contrast, if defrosting device 5 is transversely provided below cooling unit 2 as shown by dashed line X in FIG. 1, the total length of heat generating unit 8 of wire heater 7 is configured as long as width B of cooling unit 2. Here, height A of cooling unit 2 is longer than width B. Accordingly, providing defrosting device 5 in a straight pipe form on the side of cooling unit 2 is able to make total length C of heat generating unit 8 of defrosting device 5 longer as compared to the case in which defrosting device 5 is provided below cooling unit 2. Defrosting device 5 in which total length C of heat generating unit 8 of wire heater 7 is long provides the following advantageous effects.
As an amount of heat generation of wire heater 7 becomes larger, it is possible to decrease time required for defrosting and improve efficiency of defrosting device 5. In the meantime, a reference upper limit of operating temperature is set when designing wire heater 7. The reference upper limit of operating temperature affects life duration of wire heater 7. For example, if a high temperature is set as the reference upper limit of operating temperature, life duration of wire heater 7 becomes shorter. In this case, in order to increase the amount of heat generation of wire heater 7 within the limit of the reference upper limit of operating temperature, it is necessary to increase total length C of heat generating unit 8. Consequently, the life duration and the amount of heat generation are ensured with defrosting device 5 according to the first embodiment, as total length C of heat generating unit 8 is long.
Further, when the flammable refrigerant is used for cooling unit 2, the surface temperature of defrosting device 5 is required to be set low. For example, the surface temperature of defrosting device 5 is required to be lower than the ignition temperature of the flammable refrigerant by 100 K or more. According to defrosting device 5 of this embodiment, when isobutane whose ignition temperature is 494 degrees Celsius is used as a refrigerant, the reference upper limit of operating temperature is set such that the surface temperature of glass tube 6 of defrosting device 5 is lower than 394 degrees Celsius. Consequently, the amount of heat generation can be sufficiently ensured with defrosting device 5 according to the first embodiment, even when the surface temperature of glass tube 6 is required to be set low.
Moreover, as defrosting device 5 in a straight pipe form is provided on the side of cooling unit 2, a distance between defrosting device 5 and a part of cooling unit 2 at the most distant position from defrosting device 5 becomes shorter in cooling unit 2 whose height A is longer than width B, as compared to the case in which defrosting device 5 is provided below cooling unit 2. With this configuration, the heat from defrosting device 5 is easily transferred to an entirety of cooling unit 2.
Furthermore, according to the conventional refrigerator, as shown in FIG. 9, metallic protective plate 128 is provided between glass tube heater 126 and cooling unit 125. When water resulted from the defrosted frost is brought into contact with glass tube heater 126, the water evaporates and generates an evaporation sound. Metallic protective plate 128 prevents the water resulted from the defrosted frost from being brought into contact with glass tube heater 126. Therefore, metallic protective plate 128 is essential in the conventional structure in order to prevent the evaporation sound from being generated. In addition, the conventional structure requires a space for providing metallic protective plate 128. However, according to the first embodiment, defrosting device 5 is provided on the side of cooling unit 2. Consequently, even when the water resulted from the defrosted frost drops, the water is not brought into contact with defrosting device 5. Therefore, no evaporation sound is generated. In addition, it is not necessary to provide metallic protective plate 128. As a result, it is possible to manufacture refrigerating apparatus 1 at a low cost.
It should be noted that defrosting device 5 is configured by providing wire heater 7 within glass tube 6. A heat transmission ratio of glass is considerably higher than that of metals and such. Accordingly, defrosting device 5 using glass tube 6 efficiently generates radiation heat. In other words, cooling unit 2 is efficiently heated and defrosted by the radiation heat from wire heater 7.
Here, when transporting refrigerating apparatus 1, a force attributed to vibration due to the transportation is applied to wire heater 7. If strength of wire heater 7 is insufficient, the coiled form of heat generating unit 8 of wire heater 7 deforms due to the force. Heat generating unit 8 is biased toward the bottom when deforming due to its own weight. In other words, spiral pitches of heat generating unit 8 in the coiled form become uneven. The unevenness of the spiral pitches causes uneven heat generation, resulting in localized heating in glass tube 6. Further, the unevenness of the spiral pitches brings heat generating unit 8 into contact with glass tube 6, causing abnormal noise. According to the first embodiment, the strength of wire heater 7 can be ensured by setting the diameter of wire heater 7 to be equal to or grater than 0.21 mm. With this, it is possible to suppress the deformation of heat generating unit 8 in the coiled form, and to prevent the localized heating of glass tube 6 and the abnormal noise from being caused.
FIG. 3 shows a front elevational view of another refrigerating apparatus according to the first embodiment. A difference from the structure shown in FIG. 1 is that defrosting device 5 is fixed in contact with refrigerant pipe 4. Specifically, according to the structure shown in FIG. 1, the heat from defrosting device 5 is transferred to cooling unit 2 via the space as the radiation heat, as defrosting device 5 is fixed with the predetermined interval from cooling unit 2. In contrast, according to the structure shown in FIG. 3, as defrosting device 5 is fixed in contact with refrigerant pipe 4, the heat from defrosting device 5 is transferred to cooling unit 2 by thermal conduction in addition to the radiation heat. Further, using refrigerant pipe 4 as a thermal transfer unit efficiently transfers the heat from defrosting device 5 by a thermosyphon effect. In the structure shown in FIG. 3, a pitch between or a number of cooling fins 3 of cooling unit 2 is adjusted as needed in order to fix defrosting device 5 in contact with refrigerant pipe 4.

Second Embodiment

FIG. 4 shows a cross-sectional view of a defrosting device of a refrigerating apparatus according to a second embodiment of the present invention. Like components as described in the first embodiment are denoted and described by like reference numerals. A difference from the structure of defrosting device 5 shown in FIG. 2 is that wire heater 7 a of defrosting device 51 has different spiral pitches P1 and P2 as shown in FIG. 4. Here, spiral pitch P1 is smaller than spiral pitch P2.
Defrosting device 51 is fixed to cooling unit 2 such that a side of spiral pitch P1 comes upside. Specifically, defrosting device 51 is provided such that a side on which a coiled portion of heat generating unit 8 of wire heater 7 a is dense comes upside. When defrosting device 51 is fixed to cooling unit 2, the coiled form of heat generating unit 8 becomes wider toward downside due to its own weight. According to the first embodiment, by the coiled form of heat generating unit 8 being wider toward downside, the spiral pitches of entire heat generating unit 8 becomes substantially even.
By the spiral pitch of heat generating unit 8 becoming even, the amount of heat generation of wire heater 7 a per unit area becomes even. By the amount of heat generation becoming even, it is possible to suppress the unevenness of the defrosting and to improve the defrosting efficiency of defrosting device 51. In addition, with this configuration, it is possible to use wire heater 7 a whose diameter is small. It is appreciated that, while the above description is given regarding the example in which wire heater 7 a of defrosting device 51 includes two types of spiral pitches, wire heater 7 a can include three or more types of spiral pitches.

Third Embodiment

FIG. 5 shows a cross-sectional view of a defrosting device of a refrigerating apparatus according to a third embodiment of the present invention. Like components as described in the first embodiment are denoted and described by like reference numerals. As shown in FIG. 5, defrosting device 52 is provided with glass tube 6, carbon heat generator 8 a disposed within glass tube 6 and configured by a carbon fiber and whose both ends are respectively sealed and held by sealing bodies 8 b, leads 10 connected to carbon heat generator 8 a, cap 11 covering the upper opening of glass tube 6, and cap 12 covering the lower opening of glass tube 6.
Similarly to FIG. 1 and FIG. 3, defrosting device 52 is provided on the side of cooling unit 2 in the vertical direction. As defrosting device 52 according to the third embodiment uses carbon heat generator 8 a, radiation efficiency of infrared light is high. Therefore, the time required for defrosting is short and the defrosting efficiency is high. Further, as carbon heat generator 8 a does not have flexibility, any deformation due to vibration during transportation does not occur.

Fourth Embodiment

FIG. 6 shows a front elevational view of a refrigerating apparatus according to a fourth embodiment of the present invention. FIG. 7 shows a front elevational view of another refrigerating apparatus according to the fourth embodiment. Like components as described in the first embodiment are denoted and described by like reference numerals.
As shown in FIG. 6, cooling unit 2 is provided in the longitudinal direction similarly to the first embodiment. Defrosting device 5 is provided in the vertical direction. Defrosting device 5 is fixed by member 2 b at a predetermined interval from cooling unit 2. Horizontal distance D between cap 11, which is an upper side of defrosting device 5, and cooling unit 2 is shorter than horizontal distance F between cap 12, which is a lower side of defrosting device 5, and cooling unit 2. In other words, defrosting device 5 is disposed in a slanted manner so as to be gradually spaced away from cooling unit 2 toward downside.
The following describes defrosting of cooling unit 2 by defrosting device 5. Similarly to the first embodiment, by transferring the radiation heat from heat generating unit 8 of wire heater 7 to refrigerant pipe 4 or to cooling fin 3, the frost formed on cooling unit 2 melts, and thus the defrosting is carried out.
As defrosting device 5 is disposed in a slanted manner such that horizontal distance D is shorter than horizontal distance F, the radiation heat from wire heater 7 is directly transferred to drain pan 13 provided below cooling unit 2. In other words, the frost forming on drain pan 13 is defrosted. With this configuration, it is not necessary to separately provide a heater for defrosting drain pan 13. This allows an inexpensive structure. It is appreciated that defrosting device 51 or 52 described in the second embodiment or the third embodiment can also be used as defrosting device 5.
According to the structure shown in FIG. 6, the heat from defrosting device 5 is transferred to cooling unit 2 via the space as the radiation heat, as defrosting device 5 is fixed with the predetermined interval from cooling unit 2. In contrast, according to the structure shown in FIG. 7, as defrosting device 5 is fixed in contact with a part of refrigerant pipe 4, the heat from defrosting device 5 is transferred to cooling unit 2 by the thermal conduction in addition to the radiation heat. Further, using refrigerant pipe 4 as a thermal transfer unit efficiently transfers the heat from defrosting device 5 by a thermosyphon effect. In the structure shown in FIG. 7, a pitch between or a number of cooling fins 3 of cooling unit 2 is adjusted as needed in order to fix defrosting device 5 in contact with the part of refrigerant pipe 4.
Moreover, as shown in FIG. 7, in order to prompt the heat transfer from a part of defrosting device 5 that is distant from cooling unit 2, it is possible to provide heat transfer plate 2 c that thermally connects defrosting device 5 with refrigerant pipe 4. By heat transfer plate 2 c, the heat from defrosting device 5 is sufficiently transferred to a lower part of refrigerant pipe 4. It is appreciated that, while the plate fin tube heat exchanging unit is described by illustration as cooling unit 2 according to the first to fourth embodiments, it is possible to implement this embodiment using a heat exchanging unit of a different type as cooling unit 2.

Fifth Embodiment

FIG. 8 shows a configurational diagram of a storage device according to a fifth embodiment of the present invention. Referring to FIG. 8, storage device 21 is provided with first storage chamber 22 a and second storage chamber 22 b. Each of first storage chamber 22 a and second storage chamber 22 b includes an opening on a front side of the corresponding chamber, and is surrounded by a heat insulator other than the front side. On the front sides of first storage chamber 22 a and second storage chamber 22 b, first door 23 a and second door 23 b are respectively provided. First door 23 a and second door 23 b both have thermal insulation properties. Further, first storage chamber 22 a and second storage chamber 22 b are communicated through communicating channels 24 a and 24 b.
Storage device 21 is internally provided with compressor 25, condenser 26, decompressor 27, and refrigerating apparatus 1 according to one of the first to fourth embodiments. As described according to the first to fourth embodiments, refrigerating apparatus 1 is provided with defrosting device 5 and cooling unit 2. Compressor 25, condenser 26, decompressor 27, and cooling unit 2 of refrigerating apparatus 1 are coupled in a circular pattern by piping, thereby configuring a refrigeration cycle. According to the fifth embodiment, cooling unit 2 serves as an evaporator. Refrigerating apparatus 1 is disposed in first storage chamber 22 a. Further, drain pan 29 for receiving the water resulted from the defrosted frost is provided below refrigerating apparatus 1.
First storage chamber 22 a is provided with blower 28. Blower 28 circulates the cold air cooled by cooling unit 2 within first storage chamber 22 a as shown by arrow Y. Further, blower 28 circulates a part of the cold air of first storage chamber 22 a within second storage chamber 22 b through communicating channels 24 a and 24 b as shown by arrow Z. With this configuration, interiors of first storage chamber 22 a and second storage chamber 22 b are cooled.
It is possible for storage device 21 according to the fifth embodiment to efficiently defrost the frost formed on cooling unit 2 by using refrigerating apparatus 1 according to one of the first to fourth embodiments as the evaporator. Further, as the time required for defrosting is short, it is possible to suppress temperature rise in first storage chamber 22 a and second storage chamber 22 b. With this, it is possible to prevent deterioration of items stored in storage device 21. Moreover, by an improvement of the defrosting efficiency and reduction of the time for the defrosting operation, it is possible to improve efficiency of a cooling operation of storage device 21 and to reduce an amount of power consumption.

Claims

1. A refrigerating apparatus, comprising:

a cooling unit whose height is greater than width when installed; and

a defrosting device for defrosting frost formed on the cooling unit by heat, the defrosting device being in a straight pipe form, wherein

the defrosting device is provided in a vertical direction on a side of the cooling unit.

2. The refrigerating apparatus according to claim 1, wherein

the defrosting device includes:

a glass tube;

a wire heater disposed within the glass tube;

leads connected to the wire heater; and

caps respectively covering openings on both sides of the glass tube.

3. The refrigerating apparatus according to claim 2, wherein

the wire heater includes a heat generating unit in a coiled form that is configured by a metal resistant body, and

a diameter of the metal resistant body is equal to or greater than 0.21 mm.

4. The refrigerating apparatus according to claim 2, wherein

the heat generating unit has at least two types of spiral pitches, and is disposed such that a side with a smaller one of the spiral pitches comes upside.

5. The refrigerating apparatus according to claim 2, wherein

the wire heater includes a heat generating unit configured by a carbon fiber.

6. The refrigerating apparatus according to claim 1, wherein

the defrosting device is disposed in a slanted manner such that an upper side of the device is close to the cooling unit and a lower side of the device is gradually spaced away from cooling unit toward downside.

7. A storage device, comprising:

a refrigeration cycle including a compressor, a condenser, a decompressor, and an evaporator that are coupled in a circular pattern by piping;

a storage chamber; and

a blower for circulating a cold air that has been cooled by the evaporator in the storage chamber, wherein

the evaporator is used as the refrigerating apparatus according to claim 1.