JP2005098538A - Heat exchange unit and refrigerator with the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a heat exchange unit having safety and high defrosting performance even in the case of using combustible refrigerant, and to provide a refrigerator with the same. <P>SOLUTION: A defrosting heater 20 for melting the frost adhered and heaped on a heat exchanger 27 of a refrigeration cycle is fixed to a fin 28 of the heat exchanger 27. As the defrosting heater 20, a double-tube heater formed by coating a heater wire 21 of resistor with two tubes for multiple covering is used to lower surface temperature of an outside tube 24 in comparison with the case using a defrosting heater formed by covering the heater wire 21 with one tube, and furthermore, surface temperature can be reduced more by transmitting heat of the outside tube 24 to the heat exchanger 27. In the case of using this heat exchange unit for a refrigeration cycle filled with the combustible refrigerant, it is effective as a means for reducing surface temperature than igniting temperature of the combustible refrigerant, and even if the combustible refrigerant is leaked, danger of catching fire in a surface of the defrosting heater is eliminated to secure safety. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a heat exchange unit in which a heat exchanger and a defrosting heater are combined, and a refrigerator provided with the heat exchange unit.

  2. Description of the Related Art Conventionally, a heat exchanger unit for a refrigeration cycle in which a tubular defrost heater is fixed to a heat exchanger (see, for example, Patent Document 1) has been disclosed.

  Hereinafter, the conventional defrosting heater will be described with reference to the drawings.

FIG. 4 is a side view of a conventional heat exchanger 1, which includes fins 2 and refrigerant pipes 3, and a notch 4 that opens downward is provided in the lower part of the fins 2. Is arranged. As a result, the glass tube heater 5 is almost embedded in the heat exchanger 1 and can be downsized.
JP 2002-5553 A

  However, although the above-mentioned conventional configuration is excellent in terms of increasing the volumetric efficiency by disposing a defrost heater in the dead space of the heat exchanger, it is applied to a refrigeration cycle in which a flammable refrigerant that has become popular in recent years is enclosed. Therefore, no consideration is given to safety.

  In view of the above problems, an object of the present invention is to provide a heat exchange unit that is safe even under a flammable refrigerant and has a high defrosting capability.

  In order to solve the above-described problem, the present invention provides a heat exchange unit in which a defrost heater that melts frost attached to and accumulated on a heat exchanger of a refrigeration cycle is fixed to the heat exchanger. This is a multi-tube heater in which a heater wire made of a resistor is covered with multiple tubes with different diameters. The surface temperature of the outer tube is higher than that of a defrost heater with a heater wire covered with a single tube. In addition to lowering the surface temperature, the surface temperature can be further lowered by conducting heat from the outer tube to the heat exchanger.

  Thus, when applied to a refrigeration cycle in which a flammable refrigerant is sealed, it is effective as a means for lowering the surface temperature below the ignition temperature of the flammable refrigerant, and even if the flammable refrigerant leaks, the surface of the defrost heater It is safe from being ignited.

  According to the present invention, the surface temperature of the outer tube can be lower than that of a defrost heater in which the heater wire is covered with one tube, and the heat of the outer tube is transferred to the heat exchanger side. By making it, the surface temperature can be further lowered.

  Thus, when applied to a refrigeration cycle in which a flammable refrigerant is sealed, it is effective as a means for lowering the surface temperature below the ignition temperature of the flammable refrigerant, and even if the flammable refrigerant leaks, the surface of the defrost heater It is safe from being ignited.

  According to a first aspect of the present invention, there is provided a heat exchange unit in which a defrost heater for melting frost adhering / depositing on a heat exchanger of a refrigeration cycle is fixed to the heat exchanger. The heater wire made of a resistor is a multi-tube heater in which a plurality of tubes with different diameters are covered in multiple tubes, and the surface temperature of the outer tube is a defrost heater in which the heater wire is covered with a single tube. In addition to lowering the surface temperature, the surface temperature can be further lowered by conducting heat from the outer tube to the heat exchanger.

  Thus, when applied to a refrigeration cycle in which a flammable refrigerant is sealed, it is effective as a means for lowering the surface temperature below the ignition temperature of the flammable refrigerant, and even if the flammable refrigerant leaks, the surface of the defrost heater It is safe from being ignited.

  Next, the invention according to claim 2 is the invention according to claim 1, wherein the outer tube of the multi-tube heater is formed of a metal having high thermal conductivity, and the heat of the heated outer tube is reduced. By utilizing the high thermal conductivity of the tube itself, it can conduct heat to the heat exchanger and efficiently remove frost.

  Next, the invention according to claim 3 is the invention according to claim 1, wherein the outer tube of the multi-pipe heater is made of glass, whereby the outer tube is more heated than the heated inner tube. In addition to heating the heat exchanger by transmitting the radiated heat rays, the heat generated in the outer pipe is also conducted to the heat exchanger, so that the defrosting capability is further improved.

  Next, the invention according to claim 4 is the invention according to claim 2 or 3, wherein the outer tube is press-fitted into a notch provided in advance in the fin of the heat exchanger, As a result, the defrost heater can be easily attached to the heat exchanger, and workability is improved.

  Next, the invention according to claim 5 is the invention according to claim 2, wherein the outer tube is inserted into a through hole provided in advance in the fin of the heat exchanger, and the diameter is expanded. Thus, the outer tube is brought into close contact with the heat exchanger, whereby the thermal conductivity from the outer tube to the heat exchanger is increased, and the frost attached to the heat exchanger can be efficiently removed.

  Next, the invention according to claim 6 is a heat exchange unit in which a defrost heater that melts frost adhering to and accumulated on a heat exchanger of a refrigeration cycle is fixed to the heat exchanger, and the defrost heater includes: A heater wire made of a resistor is a multi-tube heater in which a plurality of tubes having different diameters are covered multiple times, and the outer tube of the multi-tube heater is cooled. The amount of frost that concentrates on the pipe and adheres to the heat exchanger can be suppressed, and the defrosting time is shortened.

  Next, the invention according to claim 7 is a refrigerator including the heat exchange unit according to any one of claims 1 to 6, and defrosts in a situation where a flammable refrigerant leaks into the refrigerator. Even if the heater generates heat, since the surface temperature is lower than the ignition temperature of the refrigerant, the leaked refrigerant is not ignited and is safe.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In addition, about the same structure as the past, the same code | symbol is attached | subjected and detailed description is abbreviate | omitted.

(Embodiment 1)
FIG. 1 is a partially broken front view showing a heat exchange unit according to Embodiment 1 of the present invention, and FIG. 2 is a perspective view of main parts showing a fixed state of a heat exchanger and a defrost heater in the same embodiment; FIG. 3 is a perspective view of relevant parts showing another fixing method of the heat exchanger and the defrosting heater in the same embodiment.

  In FIG. 1, a defrost heater 20 includes a heater wire 21 formed in a coil shape with a resistance wire as an effective heat generating portion, and a linear connection portion 21a is formed in the vicinity of both ends of the heater wire 21 instead of a coil shape. Yes.

  The stopper 22 is made of silicon rubber, covers an open end of a glass tube 23 to be described later, and holds both ends of the outer tube 24. The plug 22 is provided with a lead wire insertion hole 22a through which a later-described lead wire 25 passes.

  The inner tube 23 is a glass tube having a cylindrical shape with an outer diameter of about 10.5 mm opened at both ends, and covers the heater wire 21.

  The outer tube 24 is a tube body that covers the inner tube 23 and is formed of a material having high thermal conductivity, for example, a metal such as aluminum, and absorbs heat radiated from the heater wire on the inner surface and dissipates heat from the outer surface. To do.

  In the present embodiment, by setting the thickness of the outer tube 24 to 1 mm, the surface temperature of the outer tube 24 is set to 300 ° C. or lower during energization.

  The lead wire 25 is connected to the heater wire 21 through a lead wire insertion hole 22 a provided in the stopper 22. The heater wire 21 and the lead wire 25 are connected by a sleeve 26 made of a conductive member.

  The heat exchanger 27 includes a plurality of fins 28 and a refrigerant pipe 29 installed so as to pass through the fins 28, and the pipe 24 outside the defrosting heater 20 is held by the plurality of fins 28.

  Thus, the heat exchanger 27 and the defrost heater 20 are assembled in a good heat conductivity is the heat exchange unit 30.

  As shown in FIG. 2, the defrost heater 20 is fixed to the heat exchanger 27 by providing a through hole 28a (not shown) in advance in the fin 28 of the heat exchanger 27, and connecting the outer tube 24 to the through hole 28a. In the inserted state, the outer tube 24 can be brought into close contact with the fin 28 by performing a process of expanding the diameter from the inner surface to the outer surface of the tube.

  This method is effective when the outer tube 24 is made of metal. However, since it is necessary to enlarge the tube, it is desirable to fix the outer tube 24 to the fin 28 before assembling the internal components.

  As another fixing method, as shown in FIG. 3, a notch 38a is provided in advance in the fin 38 of the heat exchanger 37, and the outer tube 24 is press-fitted into the notch 38a to press the fin 38 into the fin 38. It can be adhered.

  Since this method can be inserted into the notch 38a in the state of the defrost heater 20, it is desirable to apply to the defrost heater 20 in which the outer tube 24 is formed of a glass tube.

  About the defrost heater comprised as mentioned above, the operation | movement is demonstrated below.

  When the heater wire 21 generates heat, the radiant heat ray passes through the inner tube 23 made of glass, and raises the temperature of the surface of the outer tube 24 made of aluminum.

  Since the outer tube 24 is held by the plurality of fins 28 of the heat exchanger 27, frost accumulated on the heat exchanger 27 is melted by heat conduction from the outer tube 24 heated by the radiant heat of the heater wire 21. ·Remove.

  Since the plug 22 holds both ends of the outer tube 24, the heat of the outer tube 24 is transmitted, but since the outer tube 24 is held by the fins 28 of the heat exchanger 27, most of the heat is transferred. Moves to the fins 28, so that there is no rapid temperature rise of the plug 22 and thermal degradation is suppressed.

  In this embodiment, since the heater wire 21 has a double structure that is covered with two pipes, the outer surface temperature can be reduced, and it is optimal as a defrosting heater for a refrigeration cycle in which a combustible refrigerant is sealed. The surface temperature of the outer tube 24 can be made lower than the ignition temperature of the flammable refrigerant without impairing the frost capacity.

  Further, the material of the outer tube 24 is not limited to aluminum, and may be copper, copper alloy, or glass having high transmittance with high thermal conductivity.

  When the outer tube 24 is made of glass, the heat rays radiated from the heater wire 21 and transmitted through the inner tube 23 further pass through the outer glass and reach the fins 28. Since the heat exchanger is heated, it can be efficiently defrosted.

  In the present embodiment, the outer pipe 24 and the refrigerant pipe 29 are separated from each other, but a part of the refrigerant pipe 29 may be brought into close contact with the surface of the outer pipe 24. In this case, the outer pipe 24 is cooled. Since the surface of the tube is also cooled, frost formation on the surface of the outer tube 24 is promoted, and conversely, frost formation on the fins 28 is suppressed, and frost adhering to the outer tube 24 is quickly melted during defrosting. As a result, the defrosting time is shortened to save power.

  Further, as a cooling method for the outer pipe 24, the outer pipe can be directly cooled by providing a refrigerant flow path in the outer pipe 24 in advance and piping the flow path to the refrigeration cycle.

  As described above, the heat exchange unit according to the present invention is highly reliable because the surface temperature of the heater can be lowered, and when applied to a refrigeration cycle in which a combustible refrigerant is sealed, It is highly safe even when leaked, and can be applied to a wide range of equipment including refrigerators equipped with a refrigeration cycle.

The partially broken front view of Embodiment 1 of the heat exchange unit by this invention The principal part perspective view which shows the fixed state of the heat exchanger and defrost heater of the embodiment The principal part perspective view which shows the other fixed state of the heat exchanger and defrost heater of the embodiment Side view of conventional heat exchange unit

Explanation of symbols

DESCRIPTION OF SYMBOLS 20 Defrost heater 21 Heater wire 22 Plug 23 Inner pipe | tube 24 Outer pipe | tube 27 Heat exchanger 28 Fin 28a Through-hole 30 Heat exchange unit 38a Notch

Claims (7)

In a heat exchange unit in which a defrost heater that melts frost adhered to and accumulated on a heat exchanger of a refrigeration cycle is fixed to the heat exchanger, the defrost heater has a heater wire made of a resistor having a different diameter. A heat exchange unit characterized in that it is a multi-tube heater having a structure in which multiple tubes are covered. 2. The heat exchange unit according to claim 1, wherein a tube outside the multi-tube heater is formed of a metal having high heat conductivity. The heat exchange unit according to claim 1, wherein a tube outside the multi-tube heater is formed of glass. The heat exchange unit according to claim 2 or 3, wherein the outer tube is press-fitted into a notch provided in advance in a fin of the heat exchanger. 3. The heat according to claim 2, wherein the outer pipe is inserted into a through-hole provided in advance in a fin of the heat exchanger, and then the diameter of the outer pipe is increased to be in close contact with the heat exchanger. Replacement unit. In a heat exchange unit in which a defrost heater that melts frost adhered to and accumulated on a heat exchanger of a refrigeration cycle is fixed to the heat exchanger, the defrost heater has a heater wire made of a resistor having a different diameter size. A heat exchange unit comprising a multi-tube heater having a structure in which a plurality of tubes are covered in multiple, and cooling a tube outside the multi-tube heater. The refrigerator provided with the heat exchange unit as described in any one of Claims 1-6.

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