JP2007046830A - Cooling storage - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cooling storage having high defrosting capacity and restrained from the excessive rise of temperature in a cooling chamber even in an abnormal current carrying time. <P>SOLUTION: A Stirling cooling storage comprises a cooling storage body having the cooling chamber, a low temperature side evaporator 11 for cooling the interior of the cooling chamber, and a heater 11A defrosting the low temperature side evaporator 11. A heater 11A has a glass tube heater 111A provided with a space from the low temperature side evaporator 11, and a PTC heater 112A provided near the low temperature side evaporator 11. The PTC heater 112A has a function of suppressing its output (a self-temperature control function) when the heater reaches a predetermined temperature. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a refrigerator, and more particularly to a refrigerator having a defrosting function.

Conventionally, a defrost heater used for defrosting a refrigerator is known.
For example, in Japanese Unexamined Patent Application Publication No. 2004-340402 (Patent Document 1), a defrost heater including a heater wire made of a metal resistor installed inside a glass tube and a tube covering the glass tube is disclosed. Yes. The defrost heater is formed so that the radiant heat has directivity.
JP 2004-340402 A

  When defrosting a cooler using a defrost heater, it is necessary to prevent the temperature in the cooling chamber from rising abnormally even when the heater is continuously energized due to an abnormality. For this reason, the heater output may not be set sufficiently high. As a result, the defrosting process takes a relatively long time, and the temperature of the cooling chamber may not be kept sufficiently low during the defrosting.

  The present invention has been made in view of the above-described problems, and an object of the present invention is a cooling system that has a high defrosting capability and suppresses an excessive increase in the temperature in the cooling chamber even during abnormal energization. Is to provide storage.

  A refrigerator according to the present invention includes a refrigerator main body having a cooling chamber, a cooler for cooling the cooling chamber, and a heater for defrosting the cooler, and the heater is provided apart from the cooler. And a second heater provided in the vicinity of the cooler, and the second heater has a self-temperature control function.

  Here, the self-temperature control function means a function of suppressing the output when the heater reaches a predetermined temperature.

  According to the above configuration, frost adhering to the cooler and its peripheral members is melted by radiant heat from the first heater separated from the cooler, and cooled by heat conduction from the second heater near the cooler to the cooler. The frost adhering to the vessel can be melted efficiently. Therefore, high defrosting capability is obtained. And defrosting time is shortened and the temperature in a cooling chamber can be kept low enough at the time of defrosting. On the other hand, when the heater is continuously energized due to an abnormality, the output of the second heater having the self-temperature control function is suppressed, so that the temperature in the refrigerator can be prevented from rising excessively.

  The cooler is preferably a Stirling engine having a high temperature part and a low temperature part, a condenser provided in the low temperature part of the Stirling engine, a condenser for condensing the refrigerant inside, and an evaporator for evaporating the refrigerant condensed in the condenser And the evaporator is used as the cooler.

  As a result, a Stirling cooler having a high defrosting capability and suppressing the temperature in the cooling chamber from excessively rising even during abnormal energization is obtained.

  ADVANTAGE OF THE INVENTION According to this invention, even when a heater will be in a continuous electricity supply state by abnormality, the defrosting capability by a heater can be improved, suppressing that the temperature in a cooling chamber rises too much.

  Below, the embodiment of the refrigerator based on this invention is described. Note that the same or corresponding portions are denoted by the same reference numerals, and the description thereof may not be repeated.

  In the specification of the present application, the “refrigerator” is a concept including all of “refrigerator”, “freezer”, and “refrigerator”.

  FIG. 1 is a piping system diagram of a Stirling cooler as an example of a cooler according to one embodiment of the present invention.

  As shown in FIG. 1, the Stirling refrigerator 1 includes a Stirling refrigerator 4 (Stirling engine) having a high temperature part 2 and a low temperature part 3, a high temperature side evaporator 5 attached to the high temperature part 2, and a high temperature side condenser. 7 and the first high temperature side circulation circuit (first circulation circuit) including the pipes 2A and 2B, and the second high temperature side circulation circuit including the high temperature side evaporator 5, the circulation pump 6, the dew prevention pipe 9 and the pipes 2C to 2E ( 2nd circulation circuit) and the low temperature side circulation circuit containing the low temperature side condenser 10 attached to the low temperature part 3, the low temperature side evaporator 11, and the pipes 3A and 3B. The first high temperature side circulation circuit cools the high temperature part 2 of the Stirling refrigerator 4, and the second high temperature side circulation circuit supplies heat to the dew condensation prevention pipe 9. The low temperature side circulation circuit exchanges heat between the air in the refrigerator and the low temperature part 3 of the Stirling refrigerator 4 via the low temperature side evaporator 11.

Water (H ₂ O) or the like is sealed as a refrigerant in the first and second high-temperature side circulation circuits. The refrigerant evaporated in the high temperature side evaporator 5 reaches the high temperature side condenser 7 via the pipe 2A (high temperature side conduit) (broken line arrow in FIG. 1). The refrigerant is condensed and liquefied by heat exchange with the outside air in the high temperature side condenser 7. In order to promote this heat exchange, a fan 8 that generates an air flow in the vicinity of the high-temperature side condenser 7 is provided. The liquefied refrigerant returns to the high temperature side evaporator 5 through the pipe 2B (high temperature side return pipe). In the first high temperature side circulation circuit, the heat generated in the high temperature part 2 can be transferred to the high temperature side condenser 7 by utilizing the natural circulation caused by the evaporation and condensation of the refrigerant. The side condenser 7 is disposed above the high temperature side evaporator 5. Further, in order to adjust the boiling point of the refrigerant, the pressure in the circulation circuit system is adjusted (reduced pressure from atmospheric pressure).

  On the other hand, a pipe 2 </ b> C is connected to the lower part of the high temperature side evaporator 5. Liquid phase refrigerant flows from the high temperature side evaporator 5 into the pipe 2C. The refrigerant flowing into the pipe 2 </ b> C reaches the circulation pump 6 positioned below the Stirling refrigerator 4. The refrigerant discharged from the circulation pump 6 is sent to the dew prevention pipe 9 via the pipe 2D. The refrigerant that has flowed through the dew condensation prevention pipe 9 returns to the high temperature side evaporator 5 through the pipe 2E. Thus, forced circulation by the circulation pump 6 is performed in the second high temperature side circulation circuit.

  Here, the refrigerant flowing in the dew condensation prevention pipe 9 is kept at a relatively high temperature by the heat given from the high temperature part 2 of the Stirling refrigerator 4. Therefore, the dew condensation prevention pipe 9 can be arranged in the front opening of the refrigerator to suppress the dew condensation at the door portion or the like.

  In addition, carbon dioxide, hydrocarbons, and the like are sealed as a refrigerant in the low-temperature side circulation circuit. The refrigerant liquefied in the low temperature side condenser 10 reaches the low temperature side evaporator 11 through the pipe 3A (low temperature side conduit). Heat exchange is performed by evaporating the refrigerant in the low temperature side evaporator 11. In order to promote this heat exchange, a fan 12 that generates an air flow in the vicinity of the low-temperature evaporator 11 is provided. After heat exchange, the vaporized refrigerant returns to the low temperature side condenser 10 via the pipe 3B (low temperature side return pipe). In the low-temperature side circulation circuit, the low-temperature side evaporation is performed so that the cold heat generated in the low-temperature part 3 can be transmitted to the low-temperature side evaporator 11 by utilizing natural circulation caused by the evaporation and condensation of the refrigerant. The vessel 11 is disposed below the low temperature side condenser 10. Further, the pressure in the circulation circuit system is adjusted in order to adjust the boiling point of the refrigerant.

  When the Stirling refrigerator 4 is operated, heat generated in the high temperature part 2 of the refrigerator 4 is exchanged with the outside air via the high temperature side condenser 7. On the other hand, the cold generated in the low temperature part 3 of the Stirling refrigerator 4 is heat exchanged with the air in the refrigerator through the low temperature side evaporator 11. The warmed airflow from the inside of the refrigerator is sent again to the vicinity of the low-temperature side evaporator 11 and repeatedly cooled.

  With the implementation of the cooling cycle described above, frost forms on the low temperature side evaporator 11. In the Stirling refrigerator 1, a heater 11A for defrosting is provided. The configuration and operation of the heater 11A will be described later.

  By performing defrosting of the low temperature side evaporator 11, defrosted water is generated. The defrost water is guided to the drain pan 12B (evaporating dish) installed at the lower part of the bottom surface of the refrigerator main body through the drain pipe 12A. A fan 12C is provided on the top of the drain pan 12B, and an air flow is formed in the vicinity of the surface of the defrost water accumulated in the drain pan 12B by the fan 12C, and relatively dry air is supplied onto the defrost water. Evaporation of defrost water is promoted.

  Next, an example of the structure of the Stirling refrigerator 4 and its operation will be described with reference to FIG.

  As shown in FIG. 2, the Stirling refrigerator 4 of the present embodiment is a free piston type Stirling engine, and includes a casing 30, a cylinder 13 assembled to the casing 30, and a reciprocating motion in the cylinder 13. Piston 14 and displacer 15, regenerator 16, working space 17 including a compression space 17 </ b> A and an expansion space 17 </ b> B, a high temperature portion 2, a low temperature portion 3, a linear motor 23 as a piston driving means, and a piston spring 24, a displacer spring 25, a displacer rod 26, and a back pressure space 27.

  In the example of FIG. 2, the outer shell (outer wall) of the Stirling refrigerator 4 is not constituted by a single container, but is positioned on the back pressure space 27 side and the casing 30 (vessel portion) and on the working space 17 side. The high-temperature part 2, the tube 18A, and the low-temperature part 3 are mainly configured. The casing 30 defines a back pressure space 27. Various parts including the cylinder 13, the linear motor 23, the piston spring 24, and the displacer spring 25 are assembled to the casing 30. The outer shell is filled with a working medium such as helium gas, hydrogen gas, or nitrogen gas.

  The cylinder 13 has a substantially cylindrical shape, and receives therein a piston 14 and a displacer 15 as a free piston so as to be capable of reciprocating. In the cylinder 13, the piston 14 and the displacer 15 are coaxially spaced apart, and the piston 14 and the displacer 15 divide the working space 17 in the cylinder 13 into a compression space 17 </ b> A and an expansion space 17 </ b> B. More specifically, the working space 17 is a space located closer to the displacer 15 than the end face of the piston 14 on the displacer 15 side, and a compression space 17A is formed between the piston 14 and the displacer 15, and the displacer 15 and the low temperature portion 3, an expansion space 17 </ b> B is formed. The compression space 17A is mainly surrounded by the high temperature part 2, and the expansion space 17B is mainly surrounded by the low temperature part 3.

  Between the compression space 17 </ b> A and the expansion space 17 </ b> B, a regenerator 16 in which a film is wound on the outer peripheral surface of the cylinder 13 with a predetermined gap is disposed. Thus, the compression space 17A and the expansion space 17B communicate with each other. Thereby, a closed circuit is formed in the Stirling refrigerator 4. The working medium sealed in the closed circuit flows in accordance with the operations of the piston 14 and the displacer 15, thereby realizing a reverse Stirling cycle described later.

  A linear motor 23 is disposed in the back pressure space 27 located outside the cylinder 13. The linear motor 23 includes an inner yoke 20, a movable magnet portion 21, an outer yoke 22 and a coil, and the piston 14 is driven in the axial direction of the cylinder 13 by the linear motor 23.

  One end of the piston 14 is connected to a piston spring 24 constituted by a leaf spring or the like. The piston spring 24 functions as an elastic force applying means for applying an elastic force to the piston 14. By applying an elastic force by the piston spring 24, the piston 14 can be reciprocated in the cylinder 13 more stably and periodically. One end of the displacer 15 is connected to a displacer spring 25 via a displacer rod 26. The displacer rod 26 is disposed through the piston 14, and the displacer spring 25 is constituted by a leaf spring or the like. The peripheral edge of the displacer spring 25 and the peripheral edge of the piston spring 24 are supported by a support member that extends from the linear motor 23 toward the back pressure space 27 of the piston 14 (hereinafter sometimes referred to as the rear).

A back pressure space 27 surrounded by a casing 30 is disposed on the opposite side of the piston 14 from the displacer 15. The back pressure space 27 includes an outer peripheral area located around the piston 14 in the casing 30 and a rear area located closer to the piston spring 24 (rear side) than the piston 14 in the casing 30. There is also a working medium in the back pressure space 27.

  The high temperature part 2 is attached to the casing 30 via the base member 30A. The high temperature part 2 and the low temperature part 3 are connected via the tube 18A. On the inner peripheral surfaces of the high temperature part 2 and the low temperature part 3, an internal heat exchanger 18 and an internal heat exchanger 19 are provided, respectively. The internal heat exchangers 18 and 19 perform heat exchange between the compression space 17A and the expansion space 17B and the high temperature part 2 and the low temperature part 3, respectively.

  A balance mass 29 is attached to the rear side of the casing 30 via a leaf spring 28. The balance mass 29 is a mass member that absorbs vibration of the casing 30 that is generated when the piston 14 and the displacer 15 vibrate. Specifically, when the vibration is generated in the casing 30 due to the vibration of the piston 14 or the displacer 15, the balance mass 29 is vibrated so as to follow the vibration of the casing 30, whereby the Stirling refrigerator 4. Vibration is reduced.

Next, the operation of the Stirling refrigerator 4 will be described.
First, the linear motor 23 is actuated to drive the piston 14. The piston 14 driven by the linear motor 23 approaches the displacer 15 and compresses the working medium (working gas) in the compression space 17A.

  When the piston 14 approaches the displacer 15, the temperature of the working medium in the compression space 17 </ b> A rises, but heat generated in the compression space 17 </ b> A by the high temperature portion 2 is released to the outside. Therefore, the temperature of the working medium in the compression space 17A is maintained almost isothermal. That is, this process corresponds to an isothermal compression process in a reverse Stirling cycle.

  After the piston 14 approaches the displacer 15, the displacer 15 moves to the low temperature part 3 side. On the other hand, the working medium compressed in the compression space 17A by the piston 14 flows into the regenerator 16, and further flows into the expansion space 17B. At that time, the heat of the working medium is stored in the regenerator 16. That is, this process corresponds to an isovolumetric cooling process in a reverse Stirling cycle.

  The high-pressure working medium that has flowed into the expansion space 17B expands when the displacer 15 moves to the piston 14 side (rear side). As the displacer 15 moves rearward in this way, the center portion of the displacer spring 25 is also deformed so as to protrude rearward.

  When the working medium expands in the expansion space 17B as described above, the temperature of the working medium in the expansion space 17B decreases, but external heat is transferred into the expansion space 17B by the low temperature portion 3, The inside of the expansion space 17B is kept almost isothermal. That is, this process corresponds to an isothermal expansion process of a reverse Stirling cycle.

  Thereafter, the displacer 15 starts to move away from the piston 14 (front side). Thereby, the working medium in the expansion space 17B passes through the regenerator 16 and returns to the compression space 17A side again. At this time, since the heat stored in the regenerator 16 is applied to the working medium, the working medium is heated. That is, this process corresponds to a constant volume heating process of a reverse Stirling cycle.

  By repeating this series of processes (isothermal compression process-isovolume cooling process-isothermal expansion process-isovolume heating process), an inverse Stirling cycle is configured. As a result, the low temperature part 3 is gradually lowered in temperature and has an extremely low temperature (for example, about −50 ° C.). On the other hand, the high temperature part 2 becomes gradually high temperature (for example, about 60 ° C.). As described above, the cold heat in the low temperature section 3 is supplied into the refrigerator through the low temperature side circulation circuit, and the heat in the high temperature section 2 is released to the outside of the refrigerator through the first and second high temperature side circulation circuits. Is done.

  FIG. 3 is a diagram for explaining a defrosting mechanism of the low-temperature side evaporator 11. Referring to FIG. 3, the defrosting mechanism of low temperature side evaporator 11 includes a heater 11 </ b> A and a defrosting thermistor 11 </ b> B as a “temperature sensor”. The heater 11A includes a glass tube heater 111A and a PTC (Positive Temperature Coefficient) heater 112A.

  The glass tube heater 111 </ b> A is located below the low temperature side evaporator 11 and is provided apart from the low temperature side evaporator 11. A heater cover 111B is provided on the glass tube heater 111A. On the other hand, the PTC heater 112A is attached to a secondary refrigerant pipe in the low temperature side circulation circuit. More specifically, the PTC heater 112 </ b> A is attached to the lower part of the low temperature side evaporator 11. However, the mounting position of the PTC heater 112A is not limited to the position shown in FIG. As long as the PTC heater 112 </ b> A is provided in the vicinity of the low temperature side evaporator 11, the PTC heater 112 </ b> A may be provided slightly apart from the low temperature side evaporator 11.

  According to the defrosting mechanism shown in FIG. 3, the frost adhering to the low temperature side evaporator 11 and its peripheral members is melted by the radiant heat from the glass tube heater 111A spaced from the low temperature side evaporator 11, and the low temperature side evaporation is performed. The frost adhering to the cooler can be efficiently melted by heat conduction from the PTC heater 112A in the vicinity of the cooler 11 to the low temperature side evaporator 11. Therefore, high defrosting capability is obtained. And defrosting time is shortened and the temperature in a cooling chamber can be kept low enough at the time of defrosting.

  FIG. 4 is a timing chart for explaining the normal operation of the defrosting mechanism shown in FIG. Referring to FIG. 4, energization to glass tube heater 111 </ b> A and PTC heater 112 </ b> A is started and turned on (output: 100 W), whereby defrosting of low-temperature side evaporator 11 is started. In the example of FIG. 4, the glass tube heater 111A and the PTC heater 112A are simultaneously turned on. However, the PTC heater 112A may be turned on after the glass tube heater 111A is turned on, or the PTC heater 112A is turned on. After that, the glass tube heater 111A may be turned on. In the example of FIG. 4, the output of the glass tube heater 111A and the glass tube heater 112A is 100 W, but the output is not limited to 100 W, and may be 150 W or 170 W, for example. Further, the output of the glass tube heater 111A and the output of the PTC heater 112A may be different.

  As shown in FIG. 4, after the glass tube heater 111A and the PTC heater 112A are turned on, the temperature detected by the defrosting thermistor 11B rises. This means that the low temperature side evaporator 11 and its surroundings are heated and defrosted by the glass tube heater 111A and the PTC heater 112A. When the temperature detected by the defrosting thermistor 11B reaches a predetermined temperature set in advance (15 ° C. in the example of FIG. 4), the energization to the glass tube heater 111A and the PTC heater 112A is stopped. Thereby, a defrost operation is complete | finished. Thereafter, the temperature detected by the defrosting thermistor 11B decreases. The above defrosting operation is performed every predetermined time set in advance.

  FIG. 5 is a timing chart for explaining the operation when the defrosting mechanism shown in FIG. 3 is abnormal. Here, it is assumed that the heater 11A (the glass tube heater 111A and the PTC heater 112A) is continuously energized due to an abnormality. Referring to FIG. 5, when heater 11A is continuously energized, the temperature detected by defrosting thermistor 11B rises to a predetermined temperature (15 ° C. in the example of FIG. 5) or higher. When such a state continues, there is a concern that the temperature in the cooling chamber rises abnormally.

  On the other hand, in the Stirling refrigerator 1 according to the present embodiment, a PTC heater 112A having a self-temperature control function is used. In other words, the PTC heater 112A has a property that when the temperature becomes equal to or higher than the Curie temperature (for example, about 40 ° C. to 60 ° C., 60 ° C. in the example of FIG. 5), the resistance rapidly increases and the output becomes almost zero. Therefore, even when the glass tube heater 111A and the PTC heater 112A are continuously energized, the output of the PTC heater 112A is suppressed at a certain temperature or higher, and only the glass tube heater 111A is output. An increase in temperature is suppressed. In the example of FIG. 5, the temperature detected by the defrosting thermistor 11 </ b> B converges to about 70 ° C.

  The above contents are summarized as follows. That is, the Stirling cooler 1 according to the present embodiment includes a cooler body having a cooling chamber, a low temperature side evaporator 11 as a “cooler” for cooling the cooling chamber, and a low temperature side evaporator 11. The heater 11A that performs frost is provided. The heater 11A includes a glass tube heater 111A as a “first heater” provided apart from the low-temperature side evaporator 11, and a PTC heater 112A as a “second heater” provided in the vicinity of the low-temperature side evaporator 11. The PTC heater 112A has a function (self-temperature control function) for suppressing the output when the heater reaches a predetermined temperature.

  More specifically, the Stirling refrigerator 1 is provided in a Stirling refrigerator 4 as a “Stirling engine” having a high-temperature part 2 and a low-temperature part 3, and the low-temperature part 3 of the Stirling refrigerator 4. A low-temperature side condenser 10 for condensing and a low-temperature side evaporator 11 for evaporating the refrigerant condensed in the low-temperature side condenser 10 are provided. The low temperature side evaporator 11 is used as a “cooler” for cooling the cooling chamber.

  Although the embodiments of the present invention have been described above, the embodiments disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

It is a piping distribution diagram of an example of a refrigerator concerning one embodiment of the present invention. It is sectional drawing which showed the Stirling refrigerator in the Stirling refrigerator shown by FIG. It is a figure explaining the defrost mechanism of the low temperature side evaporator in the Stirling refrigerator shown by FIG. It is a timing chart explaining the operation | movement at the time of the normal of the defrost mechanism shown by FIG. It is a timing chart explaining the operation | movement at the time of abnormality of the defrost mechanism shown by FIG.

Explanation of symbols

  1 Stirling cooler, 2 high temperature section, 2A-2E pipe (high temperature side circulation circuit), 3 low temperature section, 3A, 3B pipe (low temperature side circulation circuit), 4 Stirling refrigerator, 5 high temperature side evaporator, 6 circulation pump, 7 High temperature side condenser, 8 fan, 9 Condensation prevention pipe, 10 Low temperature side condenser, 11 Low temperature side evaporator, 11A heater, 11B Defrosting thermistor, 12 fan, 12A drain pipe, 12B drain pan, 12C fan, 111A glass tube Heater, 111B heater cover, 112A PTC heater.

Claims (2)

A refrigerator body having a cooling chamber;
A cooler for cooling the cooling chamber;
A heater for defrosting the cooler,
The heater is
A first heater provided apart from the cooler;
A second heater provided in the vicinity of the cooler;
The second heater is a refrigerator having a self-temperature control function. A Stirling engine having a high temperature portion and a low temperature portion;
A condenser that is provided in a low temperature part of the Stirling engine, and that condenses an internal refrigerant;
An evaporator for evaporating the refrigerant condensed in the condenser;
The refrigerator according to claim 1, wherein the evaporator is used as the cooler.

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