JP2018076991A - Operation method of refrigerator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a refrigerator which can surely perform defrosting of a cooling part by a defrosting heater even in the case where an ambient temperature surrounding the refrigerator is low, which can lower a refrigerant pressure in a refrigeration circuit even in the case where the ambient temperature is high, which can deal with a compressor whose starting torque is small, and which has suppressed manufacturing cost and power consumption cost low.SOLUTION: A refrigerator 10 comprises: a compressor 32 for compressing a refrigerant; a condenser 34 for condensing the refrigerant from the compressor 32; expansion means 36 for expanding the volume of the refrigerant from the condenser 34; an evaporator 18 for evaporating the refrigerant from the expansion means 36; an article storage chamber 14 cooled by the evaporator 18; a defrosting heater 22 for removing the frost which has grown in the evaporator 18; and a defrosting completion detection sensor 24 for detecting the completion of defrosting in the evaporator 18 by the defrosting heater 22. The defrosting completion detection temperature by the defrosting completion detection sensor 24 is varied according to an ambient temperature.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a refrigerator operation method, and more particularly, in a refrigerator in which an evaporator is defrosted by an electric heater during a defrosting operation, even if the starting torque of the compressor is small, it is not affected by fluctuations in the outside air temperature. The present invention relates to an operation control method for a refrigerator.

  A commercial refrigerator generally has a large internal volume of an article storage room and often stores a large amount of refrigerated goods. For this reason, a cooling load is greatly applied to the compressor of the refrigeration circuit in the refrigerator, and the startability of the compressor may deteriorate. Therefore, once a steady cooling operation is started, it is necessary to employ a compressor having a large starting torque in order to smoothly start a refrigerator storing a large cooling load, although the starting torque may not be so large. is there.

  Since the present invention is applied to a refrigerator in which the defrosting of the cooling section cooled by the evaporator is performed by an electric heater (hereinafter referred to as “defrosting heater”), the schematic structure of the refrigerator will be described first. Note that the refrigerator in the present invention is not only a model that refrigerates articles in the article storage room, but also a freezer that stores articles in a refrigerator in a freezer compartment, and uses the compartment as a freezer compartment and a refrigerator compartment, respectively. Also includes freezing and refrigerators that can be used.

  FIG. 4 is a schematic cross-sectional view of a large-capacity refrigerator 10 used for business purposes, and an article storage chamber 14 is defined inside the housing 12. A cooling unit 19 is disposed above the article storage chamber 14, and an evaporator 18 forming a part of a refrigeration circuit 16 (described later) is disposed in the cooling unit 19. In addition, an internal fan 20 for agitating the internal air is disposed in the vicinity of the cooling unit 19. Further, the cooling unit 19 cooled by the evaporator 18 is provided with a defrosting heater 22 for removing the frost because moisture contained in the internal air freezes and frost grows during the cooling operation. ing. Then, when the defrosting operation is started and the defrost heater 22 is energized and the frost attached to the cooling unit 19 is removed, the defrosting completion detection sensor 24 provided in the vicinity of the cooling unit 19 detects the defrosting. Detect completion. The defrosting completion detection sensor 24 employs mechanical detection means such as bimetal or shape memory alloy, or electrical detection means such as a thermistor or a thermocouple. Further, in the article storage chamber 14, an internal temperature detection sensor 26 that detects the internal temperature is disposed in the vicinity of the cooling unit 19.

  The refrigeration circuit 16 is housed in a machine room 28 provided above the housing 12. The refrigeration circuit 16 includes a compressor 32 that compresses the refrigerant, a condenser 34 that cools and condenses the compressed high-temperature refrigerant, expansion means 36 that expands the volume of the condensed refrigerant, and the evaporation. These members are connected by the pipe line 38 in the above-described order to constitute a refrigerant circulation system. Reference numeral 40 indicates a fan motor for air-cooling the condenser 34. The expansion means 36 uses a capillary tube in the illustrated example, but may be an expansion valve composed of an on-off valve.

  When the compressor 32 is started in the refrigeration circuit 16, the high-temperature refrigerant compressed and liquefied by the compressor 32 flows through the pipe line 38 and flows into the condenser 34, where it is cooled and then expanded. 36. The refrigerant expands in volume at the outlet of the expansion means 36 to become a vaporized refrigerant, and heat exchange is performed by the evaporator 18 to cool the cooling unit 19, thereby cooling the interior of the article storage chamber 14.

Japanese Patent No. 5008348

  In the commercial refrigerator 10 shown in FIG. 4, the defrost heater 22 is used because there is much frost on the cooling unit 19 cooled by the evaporator 18 as described above. In the so-called heater defrost method in which defrosting is forcibly performed by the defrosting heater 22, the completion of defrosting by the defrosting heater 22 is determined by the temperature change of the cooling unit 19 detected by the defrosting completion detection sensor 24. Yes. In the case of the heater defrost method, the defrost completion detection temperature by the defrost completion detection sensor 24 is set high. However, if the defrost completion detection temperature of the defrost completion detection sensor 24 is increased, the temperature of the cooling unit 19 rises during the defrosting operation, so that the refrigerant pressure in the refrigeration circuit 16 increases. This means that a large cooling load is applied to the compressor 32 of the refrigeration circuit 16, and therefore it is necessary to increase the starting torque of the compressor 32. That is, when the compressor 10 having a large starting torque is not required during the steady refrigeration operation, a large starting torque is required when the refrigerator 10 adopting the heater defrost method is shifted to the defrosting operation. Therefore, there is a request to provide a compressor 32 having a large capacity, which is uneconomical in terms of manufacturing cost and running cost.

  The present invention has been proposed in view of the above-described problems of the prior art, and is detected by a defrosting completion detection sensor 24 set in a defrosting heater, for example, in a commercial refrigerator that employs a heater defrost system. The said subject is solved by changing defrost completion detection temperature according to the external temperature of this refrigerator.

In order to solve the problem and achieve the intended object, the invention according to claim 1
A compressor for compressing the refrigerant; a condenser for condensing the refrigerant from the compressor; an expansion means for volume expansion of the refrigerant from the condenser; an evaporator for evaporating the refrigerant from the expansion means; and the evaporation In a refrigerator comprising an article storage room cooled by a vessel, a defrost heater that removes frost grown on the evaporator, and a defrost completion detection sensor that detects completion of defrosting of the evaporator by the defrost heater,
The gist of the invention is that the defrost completion detection temperature in the defrost completion detection sensor is changed according to the outside air temperature.
According to the first aspect of the present invention, since the refrigerator can be operated even when the starting torque of the compressor is small, it is not necessary to use a large capacity compressor, and the manufacturing cost and the power consumption cost can be suppressed. .

  The gist of the invention described in claim 2 is that when the outside air temperature is low, the defrost completion detection temperature of the defrost completion detection sensor is set high.

  The gist of the invention described in claim 3 is that the outside air temperature is detected by an outside air temperature detection sensor provided in the refrigerator.

According to a fourth aspect of the present invention, the condenser temperature detection sensor for monitoring the temperature of the condenser regards the temperature of the condenser detected while the compressor is stopped as the outside air temperature. And
According to the invention which concerns on Claim 4, since it can control using the condenser temperature detection sensor always provided in a condenser, without providing an outside temperature detection sensor, manufacturing cost can be held down low.

According to a fifth aspect of the present invention, the refrigerator includes a fan motor that cools the condenser, and when the outside air temperature is sufficiently low, the condenser fan motor is operated even during defrosting of the evaporator. The summary is as follows.
According to the invention which concerns on Claim 5, even if it is a case where outside temperature is quite low, it can respond with the compressor with small starting torque by rotating the fan motor which cools a condenser.

  According to the present invention, even when the temperature of the outside air surrounding the refrigerator is low, defrosting of the cooling unit by the defrosting heater can be reliably performed, which can lead to better customer service. Further, even when the outside air temperature is high, the refrigerant pressure in the refrigeration circuit can be lowered, and accordingly, a compressor with a small starting torque can be handled. For this reason, manufacturing cost and power consumption cost can be suppressed low.

It is a graph of the defrost operation of Example 1 and Example 2 by the refrigerator shown in FIG. 4, Comprising: The relationship between defrost completion detection temperature and outside temperature is shown. It is a graph of the defrost operation of Example 3 by the refrigerator shown in FIG. 4, Comprising: The relationship between defrost completion detection temperature and external temperature is shown. It is a graph of the defrost operation which shows the malfunction by the operation method of the refrigerator which concerns on Example 1, Comprising: The relationship between defrost completion detection temperature and external temperature is shown. It is a longitudinal cross-sectional view which shows schematic structure of the commercial refrigerator which employ | adopted the heater defrost system. It is a graph of the defrost operation conventionally implemented in the refrigerator shown in FIG. 4, Comprising: The relationship between defrost completion detection temperature and external temperature is shown. It is a time chart which shows starting the fan in a store | warehouse | chamber after carrying out the operating method of the refrigerator shown in FIG. 4 after a fixed time passes since starting of a compressor. FIG. 7 is a time chart showing that the internal fan is gradually activated while following the driving method shown in FIG. 6. FIG. It is a time chart which shows that the internal fan is started synchronizing with a compressor when implementing the operating method of the refrigerator shown in FIG. 8 is a time chart when the temperature of the cooling unit is further added to the control element in the operation method shown in FIG.

  Next, the operation method of the refrigerator which concerns on this invention is given below, giving suitable Examples 1-3. In addition, since the heater defrost type refrigerator to which each embodiment is applied is as described with reference to FIG. 4, the same members are denoted by the same reference numerals and description thereof is omitted.

[Example 1]
In the refrigerator 10 shown in FIG. 4, an outside air temperature detection sensor 30 that monitors the outside air temperature is disposed at an appropriate position of the housing 12, and the detection unit is exposed on the outer surface of the housing 12. In the first embodiment, the defrosting completion detection temperature detected by the defrosting completion detection sensor 24 is changed according to the outside air temperature detected by the outside air temperature detection sensor 30. Specifically, when the outside air temperature detected by the outside air temperature detection sensor 30 is low, the defrosting completion detection temperature to be detected by the defrosting completion detection sensor 24 is set high. The variation in the defrosting completion detection temperature may be continuously changed linearly or parabolically, or may be changed stepwise.

  Since the internal pressure (refrigerant pressure) of the refrigeration circuit 16 is lower than the saturation pressure of the lowest temperature part (condenser 34) in the refrigeration circuit 16, the higher the defrosting completion detection temperature, the more the condenser. The temperature of 34 continues to be low. For this reason, the pressure of the refrigerant in the refrigeration circuit 16 increases, and the torque required to start the compressor 32 increases. In other words, if the defrosting completion detection temperature set in the defrosting completion detection sensor 24 is the same, the internal pressure of the refrigeration circuit 16 becomes higher when the outside air temperature is higher. Therefore, in the embodiment of the present invention, in order to allow the starting torque of the compressor 32 to be small, when the outside air temperature is low, the defrosting completion detection temperature of the defrosting completion detection sensor 24 is increased, and the outside air When temperature is high, defrost completion detection temperature is made lower.

  The relationship described above will be described with reference to FIGS. FIG. 5 is a graph showing the conventional operation method in the refrigerator employing the heater defrost method in relation to the defrost completion detection temperature (° C.) and the outside air temperature (° C.). That is, conventionally, as shown in FIG. 5, the defrosting completion detection temperature set by the control circuit (not shown) of the defrosting completion detection sensor 24 is constant regardless of the outside air temperature. For this reason, the internal pressure (pressure before starting the compressor) of the refrigeration circuit 16 indicated by a two-dot chain line in FIG. 5 increases as the outside air temperature rises, resulting in an increase in the starting torque of the compressor described above. It was.

  However, in Example 1, as shown in FIG. 1, when the outside air temperature is low, the defrosting completion detection temperature is increased, and the defrosting completion detection temperature is set lower as the outside air temperature becomes higher. . As a result, the internal pressure (refrigerant pressure) of the refrigeration circuit 16 indicated by a two-dot chain line in FIG. 1 can be kept low throughout. In the embodiment of FIG. 1, the defrosting completion detection temperature is set so as to decrease stepwise as the outside air temperature increases. As described above, this defrosting completion detection temperature is linear or parabolic. It may be changed continuously.

  According to the invention of Example 1, when the outside air temperature is low in the heater defrost type refrigerator, the defrosting completion detection temperature of the defrosting completion detection sensor 24 is increased to surely defrost the cooling unit 19. Can do. Further, as shown in FIG. 1, when the outside air temperature is high, the internal pressure of the refrigeration circuit 16 can be similarly suppressed by lowering the defrosting completion detection temperature of the defrosting completion detection sensor 24. A small compressor 32 can be used. That is, even if the compressor 32 having a large capacity is not used, the compressor 32 having a small starting torque can be adopted, the manufacturing cost is reduced, the power cost is suppressed, and the energy saving is achieved.

[Example 2]
The proposal of the operation method according to the first embodiment is very excellent in that it is not necessary to improve the startability of the compressor and change to a compressor having a large starting torque. However, the invention of Embodiment 1 requires the above-described outside temperature detection sensor 30 in order to detect the outside temperature, and the manufacturing cost increases accordingly. Therefore, the invention of the second embodiment relates to a technique for reducing the manufacturing cost by eliminating the need for the outside air temperature detection sensor 30.

  As described with reference to FIG. 4, in the refrigerator 10, a condenser temperature detection sensor 31 is provided in the condenser 34 to protect the refrigeration circuit 16, and the temperature of the condenser 34 is constantly monitored. However, while the compressor 32 is stopped in the refrigeration circuit 16 as in the defrosting operation, the fan motor 40 of the condenser 34 is also stopped, so that the surface temperature of the condenser 34 becomes substantially equal to the outside air temperature. For this reason, it may be considered that the temperature detected by the condenser temperature detection sensor 31 is substantially the same as the outside air temperature. That is, the temperature detected by the condenser temperature detection sensor 31 when the compressor 32 is stopped can be regarded as the outside air temperature. Therefore, in place of the detection of the outside temperature by the outside temperature detection sensor 30 of the first embodiment, the operation control of the refrigeration circuit 16 is performed via the control circuit with the temperature detected by the condenser temperature detection sensor 31 in the second embodiment. is there. For this reason, the behavior which the driving method in Example 2 shows is the same as the graph of FIG. According to the invention of the second embodiment, since it is not necessary to use the outside air temperature detection sensor 30, the manufacturing cost can be reduced.

Example 3
The invention of Example 1 described above is extremely excellent in that the startability of the compressor in the heater defrost type refrigerator is improved. However, even if it is invention of Example 1, when outside temperature is quite low, there exists the following subject. That is, when the outside air temperature is low, it takes a long time to defrost the cooling unit 19. At this time, in order to surely defrost the cooling unit 19, the defrost completion detection temperature shown in FIG. However, if the defrosting completion detection temperature is set too high, the refrigerant pressure in the refrigeration circuit 16 becomes extremely high as shown in FIG. 3, and the starting torque of the compressor 32 may have to be increased.

  The third embodiment is for overcoming the above-mentioned drawbacks and is basically based on the invention of the first embodiment. However, when the outside air temperature is sufficiently low, the fan motor 40 of the condenser 34 is used. Is operated during the defrosting operation. That is, in the case of Example 1 shown in FIG. 3, the fan motor 40 of the condenser 34 is stopped during the defrosting operation. However, in Example 3 shown in FIG. 2, the fan motor 40 of the condenser 34 is rotated when the outside air temperature during the defrosting operation is considerably low. As a result, the internal pressure in the refrigeration circuit 16 is lower than the saturation pressure at the lowest temperature in the refrigeration circuit 16, so that the refrigerant in the refrigeration circuit 16 during the defrosting operation can be obtained even when the outside air temperature is low. Power can be kept low. Therefore, the defrost completion detection temperature when the outside air temperature is low can be further increased, and defrosting can be reliably performed, and complaints from suppliers can be reduced. Further, since the pressure of the refrigeration circuit 16 is further reduced, the starting torque of the compressor 32 can be reduced, and a cheaper compressor can be employed, thereby reducing costs and saving energy.

  As described above, the commercial refrigerator 10 often stores refrigerated items having a large cooling load in the article storage chamber 14. For example, a draft beer barrel before being connected to a beer server is a refrigerated product having a very large cooling load. Thus, when the cooling operation of the refrigerator 10 is started in a state where the refrigerated product having a large cooling load is stored in the article storage chamber 14, the compressor 32 is activated and the refrigerant pressure of the refrigeration circuit 16 is reduced. There are times when the cooling load is too large to reduce the refrigerant pressure. If the cooling load on the compressor 32 continues to be large, overcurrent continues to flow to the drive motor of the compressor 32, and finally an overcurrent detection sensor (not shown) is activated to stop the compressor 32. become. For example, as shown in FIG. 8, the internal temperature gradually decreases as the compressor 32 starts, but if there is a refrigerated product having a large cooling load such as a draft beer barrel, the internal temperature does not decrease moderately. If the state in which the refrigerant pressure does not decrease continues for a certain period of time, the overcurrent detection sensor operates as described above and the compressor 32 stops. Therefore, in order to quickly reduce the refrigerant pressure of the refrigeration circuit 16 even when the cooling load of the refrigerated product stored in the refrigerator 10 is large, a compressor 32 having a larger capacity is used. It is necessary to adopt. However, this causes an increase in manufacturing cost and power consumption is large and uneconomical. The internal fan 20 for diffusing the cold air from the cooling unit 19 into the article storage chamber 14 is activated in synchronization with the compressor 32.

  Therefore, as shown in FIG. 6, even if the compressor 32 is started, the internal fan 20 is not rotated until a predetermined time has elapsed. Then, since the air in the store | warehouse | chamber interior of the article | item storage chamber 14 is not stirred, articles | goods with a big cooling load like a draft beer barrel are cooled gradually. Then, after the cooling load becomes small after a predetermined time has elapsed, the low pressure of the refrigeration circuit 16 does not decrease and the load of the compressor 32 does not continue to be heavy by rotating the internal fan 20. It was.

  The proposal shown in FIG. 6 described above has a great advantage in that a smaller compressor 32 can be adopted. However, even if only the compressor 32 is started without moving the internal fan 20 and the internal fan 20 is moved after a certain time has passed and the cooling load of the draft beer barrel is reduced, the cooling load is still Since it is large, the low pressure of the refrigeration circuit 16 does not drop, and the compressor 32 may continue to be heavily loaded and become inoperable. Therefore, as shown in FIG. 7, while following the control shown in FIG. 6, the internal fan 20 is started intermittently and the air volume is increased. That is, the compressor 32 is moved first without moving the internal fan 20, and the internal fan 20 is activated so that the cooling load is gradually increased every predetermined time. The method for increasing the cooling load by the internal fan 20 may be intermittent operation, unit control (control the number of units to be operated when there are a plurality of units), rotational speed control, or damper control.

  In the operation control method of FIG. 7, the compressor 32 is moved while the internal fan 20 is stopped, and the internal fan 20 is moved so that the cooling load increases little by little at a predetermined time. is there. However, if the cooling load in the article storage chamber 14 is extremely large or articles having different load capacities are mixed, the low pressure of the refrigeration circuit 16 does not decrease, and the heavy load on the compressor 32 continues and the operation becomes impossible. It happened to be. Therefore, as shown in FIG. 9, if only the compressor 32 is moved without starting the internal fan 20 to detect the temperature of the cooling unit 19 and the temperature of the cooling unit 19 decreases, the cooling load increases little by little. The internal fan 20 is moved so that That is, the temperature of the cooling unit 19 or the like is added to the control system number. As described above, the method of increasing the cooling load by the internal fan 20 may be intermittent operation, number control, rotation speed control, or damper control. Moreover, the temperature of the cooling unit 19 may be the internal temperature instead of this. When the cooling load in the refrigerator is reduced, the temperature of the cooling unit 19 is also lowered, so that the low pressure of the refrigeration circuit 16 is not lowered, and the heavy load on the compressor 32 does not continue.

10 refrigerator, 14 article storage room, 18 evaporator, 22 defrost heater,
24 Defrosting completion detection sensor, 30 Outside air temperature detection sensor,
31 condenser temperature detection sensor, 32 compressor, 34 condenser, 36 expansion means,
40 fan motor

Claims (5)

A compressor (32) for compressing the refrigerant, a condenser (34) for condensing the refrigerant from the compressor (32), and an expansion means (36) for volume expansion of the refrigerant from the condenser (34), An evaporator (18) for evaporating the refrigerant from the expansion means (36), an article storage chamber (14) cooled by the evaporator (18), and removing frost grown on the evaporator (18). In the refrigerator (10) comprising the frost heater (22) and the defrost completion detection sensor (24) for detecting the defrost completion of the evaporator (18) by the defrost heater (22),
A method for operating a refrigerator, characterized in that the defrost completion detection temperature in the defrost completion detection sensor (24) is varied according to the outside air temperature.   The method of operating a refrigerator according to claim 1, wherein when the outside air temperature is low, the defrosting completion detection temperature of the defrosting completion detection sensor (24) is set high.   The method of operating a refrigerator according to claim 1 or 2, wherein the outside air temperature is detected by an outside air temperature detection sensor (30) provided in the refrigerator (10).   The condenser temperature detection sensor (31) for monitoring the temperature of the condenser (34) is regarded as the outside air temperature based on the temperature of the condenser (34) detected while the compressor (32) is stopped. The operation method of the refrigerator according to claim 1 or 2.   The refrigerator (10) includes a fan motor (40) for cooling the condenser (34), and when the outside air temperature is sufficiently low, the condenser (34) is defrosted even during the defrosting of the evaporator (18). The method for operating a refrigerator according to any one of claims 1 to 4, wherein the fan motor (40) is operated.

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