JP7346901B2 - Showcase - Google Patents

Description

This invention relates to a showcase.

When the detected internal temperature of the storage room containing stored items continues to exceed the warning temperature, which is higher than the set internal temperature, for a predetermined period of time, the condenser fan is controlled in a leakage warning mode that maintains operation, and leakage is detected. A cooling storage is known that maintains the operation of a condenser fan at the normal rotation speed or the maximum rotation speed even during defrosting operation during operation in the warning mode (see, for example, Patent Document 1).

JP 2017-219278 Publication

As described above, the system disclosed in Patent Document 1 operates in a leak warning mode when a refrigerant leak is suspected, and forces the condenser fan to operate constantly regardless of the operating state of the compressor, etc. be done. However, in order to maintain the operation of the condenser fan at the normal rotation speed or the maximum rotation speed during defrosting operation, unnecessary heat exchange is promoted in the condenser, resulting in a decrease in defrosting efficiency.

This invention was made to solve such problems. The purpose of this is to minimize the decline in defrosting efficiency while also making it possible to diffuse the leaked refrigerant in the event that it leaks during defrosting operation. The objective is to provide a showcase that can suppress the formation of

A showcase according to the present invention includes a casing in which a machine room and a storage room are formed, and a first air path that is disposed in a first air passage formed inside the machine room, through which a refrigerant heavier than air flows. a second heat exchanger disposed in a second air passage communicating with the inside of the storage chamber via an air outlet, through which the refrigerant flows; a first fan that generates an air flow in the air passage, and a second fan that generates an air flow in the second air passage, and the first fan is connected to the first heat exchanger. When the refrigerant condenses in the second heat exchanger and the refrigerant evaporates in the second heat exchanger, the refrigerant operates at the first air volume, and the refrigerant evaporates in the first heat exchanger and the second heat exchanger evaporates. When the refrigerant is condensed in the refrigerant , the refrigerant is operated at a second air volume that is smaller than the first air volume and is not zero .

According to the showcase according to the present invention, when refrigerant leaks during defrosting operation, it is possible to diffuse the leaked refrigerant while suppressing a decrease in defrosting efficiency as much as possible. This has the effect of suppressing the formation of a region with a concentration higher than a certain level.

1 is a cross-sectional view schematically showing the overall configuration of a showcase according to Embodiment 1 of the present invention. 1 is a block diagram showing the configuration of a control system of a showcase according to Embodiment 1 of the present invention. FIG. FIG. 2 is a flow diagram showing an example of the operation of the showcase according to the first embodiment of the present invention. FIG. 3 is a sectional view schematically showing a modification of the structure of the machine room of the showcase according to Embodiment 1 of the present invention. FIG. 3 is a sectional view schematically showing a modification of the structure of the machine room of the showcase according to Embodiment 1 of the present invention. FIG. 2 is a cross-sectional view schematically showing the overall structure of a showcase according to Embodiment 2 of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Modes for carrying out the invention will be described with reference to the accompanying drawings. In each figure, the same or corresponding parts are given the same reference numerals, and overlapping explanations will be simplified or omitted as appropriate. Note that the present invention is not limited to the following embodiments, and can be modified in various ways without departing from the spirit of the present invention.

Embodiment 1.
Embodiment 1 of the present invention will be described with reference to FIGS. 1 to 5. FIG. 1 is a sectional view schematically showing the overall structure of the showcase. FIG. 2 is a block diagram showing the configuration of the control system of the showcase. FIG. 3 is a flow diagram showing an example of the operation of the showcase. 4 and 5 are cross-sectional views schematically showing modified examples of the structure of the machine room of the showcase.

The showcase 100 according to this embodiment is an open showcase that is installed in a supermarket, convenience store, etc., and stores and displays drinks, foods, and the like. Note that the showcase 100 may be a closed (reach-in) showcase equipped with a door that opens and closes the storage room.

As shown in FIG. 1, the showcase 100 includes a housing 1. As shown in FIG. The housing 1 has a rectangular box shape as a whole. A storage room 3 and a machine room 2 are formed in the housing 1 . The storage chamber 3 is arranged on the upper side of the housing 1. The lower side of the housing 1 is a machine room 2.

The storage room 3 is a space in which beverages, fresh foods, etc. to be cooled can be stored. A plurality of display shelves 4 for displaying fresh foods and the like are attached to the storage room 3 and arranged in a vertical direction. An opening 5 is formed in at least one surface of the storage chamber 3. In the configuration example described here, there is an opening 5 in the front of the storage chamber 3. Through this opening 5, food can be taken out and placed on the display shelf 4.

The showcase 100 includes a refrigerant circuit. As shown in FIG. 1, the refrigerant circuit includes a compressor 11, a condenser 12, an expansion valve 13, and an evaporator 14, which are cyclically connected in this order by a refrigerant pipe 17. A refrigerant circuit including the refrigerant pipe 17 and the like is filled with refrigerant. A four-way valve 18 is provided in the refrigerant pipe 17 between the compressor 11, the condenser 12, and the expansion valve 13. By switching the four-way valve 18, the direction of the refrigerant flowing in the refrigerant circuit can be reversed.

From the viewpoint of protecting the global environment, it is desirable to use a refrigerant with a small global warming potential (GWP) as the refrigerant sealed in the refrigerant circuit. Furthermore, the refrigerant sealed in the refrigerant circuit is flammable. This refrigerant has a higher average molecular weight than air. That is, the refrigerant has a higher density than air and is heavier than air at atmospheric pressure. Therefore, refrigerant has the property of sinking downward in the direction of gravity in air.

Specific examples of such refrigerants include tetrafluoropropene (CF3CF=CH2:HFO-1234yf), difluoromethane (CH2F2:R32), propane (R290), propylene (R1270), ethane (R170), and butane (R600). ), isobutane (R600a), 1.1.1.2-tetrafluoroethane (C2H2F4:R134a), pentafluoroethane (C2HF5:R125), 1.3.3.3-tetrafluoro-1-propene (CF3- A (mixed) refrigerant consisting of one or more refrigerants selected from CH=CHF:HFO-1234ze), carbon dioxide (CO2:R744), etc. can be used.

The compressor 11 compresses the refrigerant to increase the pressure and temperature of the refrigerant. The compressed refrigerant is discharged from the compressor 11. As the compressor 11, for example, a rotary compressor, a scroll compressor, a reciprocating compressor, etc. can be used.

The condenser 12 exchanges heat between the refrigerant discharged from the compressor 11 and surrounding air, radiates heat from the refrigerant, and condenses the refrigerant. The condenser fan 15 sends out air heated by the condenser 12 and also sends new air around the condenser 12, thereby promoting heat exchange in the condenser 12.

The expansion valve 13 expands the refrigerant condensed in the condenser 12 and reduces the pressure of the refrigerant. The expansion valve 13 is, for example, a linear electric expansion valve (LEV) or a capillary tube. The capillary tube is a thin copper tube with an inner diameter of about 0.6 to 2 mm. By using a capillary tube for throttle expansion, it is possible to lower the pressure and temperature of the refrigerant at a lower cost than LEV.

The evaporator 14 exchanges heat between the refrigerant whose pressure has been reduced by the expansion valve 13 and the surrounding air, causing the refrigerant to absorb heat and evaporate it. At this time, the air that has exchanged heat with the refrigerant is cooled. That is, the evaporator 14 functions as a cooler. The evaporator fan 16 sends out air cooled by the evaporator 14 as a cooler, and also sends new air around the evaporator 14 to promote heat exchange in the evaporator 14.

A vapor compression refrigeration cycle is realized by circulating the refrigerant through the refrigerant circuit configured as described above. The refrigeration cycle realized by this refrigerant circuit functions as a heat pump that transfers heat between the evaporator 14 side and the condenser 12 side. Note that the evaporator fan 16 and the condenser fan 15 are, for example, a propeller fan, a line flow fan, a sirocco fan, or the like.

A compressor 11, a condenser 12, a condenser fan 15, and a four-way valve 18 are housed inside the machine room 2. The machine room 2 has an air supply port 31 and an air exhaust port 32 formed therein. The air supply port 31 is an opening for introducing outside air into the machine room 2. The exhaust port 32 is an opening for exhausting the air that has passed through the condenser 12 to the outside of the machine room 2. In the configuration example described here, the air supply port 31 is arranged on the same side as the opening 5 of the storage chamber 3, that is, on the front surface of the housing 1. The exhaust port 32 is arranged on the opposite side of the air supply port 31, that is, on the back surface of the housing 1.

A first air path leading from an air supply port 31 to an exhaust port 32 is formed inside the machine room 2 . The condenser 12 and condenser fan 15 are arranged in this first air path. The condenser 12 is a first heat exchanger that is disposed in a first air path formed inside the machine room 2, and through which a refrigerant heavier than air flows. The condenser fan 15 is then a first fan that generates airflow in the first air path.

A blowout port 22 and a suction port 21 are formed in the storage chamber 3 . The casing 1 is provided with a second air path extending from the inlet 21 to the outlet 22. This second air path is separated from the storage room 3. An evaporator 14, an evaporator fan 16, and an expansion valve 13 are housed in the second air path. When the evaporator fan 16 is driven, the cold air generated after passing through the evaporator 14 is blown out from the outlet 22 into the storage chamber 3 . The air outlet 22 opens downward at the front end of the upper inner wall surface of the storage chamber 3 so as to face the storage chamber 3 . The cool air blown out from the air outlet 22 descends along the opening surface of the opening 5. As a result, an air curtain of cold air is formed in the opening 5 of the storage chamber 3.

A part of the air in the storage chamber 3 is sucked in through the suction port 21. The air sucked in from the suction port 21 is cooled by the evaporator 14 while passing through the second air path, and is blown out into the storage chamber 3 from the blow-off port 22 again. The evaporator 14 is a second heat exchanger that is disposed in a second air path that communicates with the inside of the storage chamber 3 via the outlet 22, and through which a refrigerant heavier than air flows. The evaporator fan 16 is then a second fan that generates airflow in the second air path.

Next, the configuration of the control system of the showcase 100 of this embodiment will be described with reference to FIG. 2. As shown in the figure, the showcase 100 includes a control device 50. The control device 50 controls the overall operation of the showcase 100. Specifically, the control device 50 controls the operations of the compressor 11 , condenser fan 15 , evaporator fan 16 , and four-way valve 18 .

When performing normal refrigeration or freezing operation (hereinafter also simply referred to as "normal operation"), the control device 50 controls the refrigerant discharged from the compressor 11 in the order of the condenser 12, the expansion valve 13, and the evaporator 14. Set the direction of the four-way valve 18 so that it passes through. The controller 50 then operates the compressor 11, condenser fan 15, and evaporator fan 16. In this normal operation, the refrigerant is condensed in the condenser 12, which is the first heat exchanger, and evaporated in the evaporator 14, which is the second heat exchanger.

When normal operation continues, moisture in the air adheres to the surface of the fins of the evaporator 14 and becomes dew. This dew is cooled by the evaporator 14 and turns into frost, covering the surface of the fins of the evaporator 14. If the surface of the fins of the evaporator 14 is covered with frost, the heat exchange efficiency in the evaporator 14 will be reduced. Therefore, the showcase 100 of this embodiment is capable of performing a defrosting operation to remove the frost from the evaporator 14.

When performing a defrosting operation, the control device 50 sets the direction of the four-way valve 18 so that the refrigerant discharged from the compressor 11 passes through the evaporator 14, the expansion valve 13, and the condenser 12 in this order. The controller 50 then operates the compressor 11 and condenser fan 15. In this defrosting operation, the refrigerant is evaporated in the condenser 12, which is the first heat exchanger, and is condensed in the evaporator 14, which is the second heat exchanger. Therefore, the refrigerant condensed in the evaporator 14 radiates heat, and the evaporator 14 is heated. By heating the evaporator 14, frost attached to the evaporator 14 can be melted and removed.

During the defrosting operation, the control device 50 makes the air volume of the condenser fan 15 smaller than during normal operation. That is, the aforementioned first fan operates at the first air volume when the refrigerant is condensed in the aforementioned first heat exchanger and the refrigerant is evaporated in the aforementioned second heat exchanger. The first fan operates at the second air volume when the refrigerant evaporates in the first heat exchanger and condenses in the second heat exchanger. The second air volume is smaller than the first air volume.

By doing so, it is possible to reduce heat exchange with air in the condenser 12 during defrosting operation than during normal operation, and to maintain an air flow in the machine room 2 even during defrosting operation. Therefore, if refrigerant leaks from the condenser 12, refrigerant piping 17, etc. in the machine room 2 during defrosting operation, it is possible to diffuse the leaked refrigerant and prevent the leaked refrigerant from staying in the machine room 2. It is possible to suppress the formation of a region where the refrigerant concentration exceeds a certain level. Further, by reducing heat exchange with air in the condenser 12 during defrosting operation compared to during normal operation, it is possible to suppress a decrease in defrosting efficiency as much as possible.

Note that, as described above, the refrigerant used in this configuration example is flammable. Therefore, the second air volume of the condenser fan 15 during defrosting operation is smaller than the first air volume during normal operation, and the concentration of the leaked refrigerant is lower than the LFL (LFL = Lower Flammable Limit) of the refrigerant. ) It is recommended to set the air volume so that no area where the concentration exceeds the concentration occurs. Specifically, for example, if the first air volume is 0.18 [m^3/h], the minimum air volume that can prevent the leaked refrigerant from forming an area with a concentration higher than the LFL concentration is 0.03 [m^3]. /h]. In this case, the second air volume of the condenser fan 15 during the defrosting operation is set to be 0.03 [m^3/h] or more and less than 0.18 [m^3/h]. Specifically, for example, the second air volume is set to 0.04 [m^3/h]. If the second air volume is determined in this way, while minimizing the decline in defrosting efficiency, if refrigerant leaks during defrosting operation, the air will be stirred to diffuse the leaked refrigerant, and the LFL concentration will be higher than the LFL concentration. The formation of this region can be suppressed.

Next, an example of the operation of the showcase 100 configured as described above will be described with reference to the flowchart in FIG. 3. First, in step S1, the showcase 100 is in normal operation. The air volume of the condenser fan 15 at this time is the first air volume described above.

In subsequent step S2, the control device 50 checks whether the defrosting operation start condition is satisfied. The contents of the defrosting operation start condition are set in advance. The defrosting operation start condition is satisfied, for example, when at least one of the following (A) and (B) is satisfied.

(A) The cumulative time of normal operation is greater than or equal to the first reference time (B) The temperature of the evaporator 14 is less than or equal to the first reference temperature

Note that specific values of the first reference time and the first reference temperature are each set in advance. Further, the temperature of the evaporator 14 is detected, for example, by a temperature sensor (not shown). When the defrosting operation start condition is not satisfied, that is, when neither of the above (A) and (B) is satisfied, the process returns to step S1 and normal operation is continued. On the other hand, when the defrosting operation start condition is satisfied, that is, when one or both of the above (A) and (B) is satisfied, the process proceeds to step S3.

In step S3, the control device 50 performs a defrosting operation of the showcase 100. In this defrosting operation, the air volume of the condenser fan 15 becomes the second air volume described above. In subsequent step S4, the control device 50 checks whether the defrosting operation termination condition is satisfied. The contents of the defrosting operation end condition are set in advance. The defrosting operation termination condition is satisfied, for example, when at least one of the following (C) and (D) is met.

(C) The elapsed time after starting the defrosting operation is equal to or greater than the second reference time. (D) The temperature of the evaporator 14 becomes equal to or greater than the second reference temperature.

Note that specific values of the second reference time and the second reference temperature are each set in advance. Here, the second reference temperature is higher than the first reference temperature described above. If the defrosting operation termination condition is not satisfied, that is, if neither of the above (C) and (D) is satisfied, the process returns to step S3 and the defrosting operation is continued. On the other hand, if the defrosting operation end condition is met, that is, one or both of (C) and (D) above, the process returns to step S1, and the control device 50 ends the defrosting operation. , start normal operation.

Next, a modification of the showcase 100 configured as described above will be described with reference to FIGS. 4 and 5. In this modification, in addition to the first air path described above, another third air path is formed inside the machine room 2. In the first air path, as shown by the arrow in FIG. This is an air path for exhausting air outside the machine room 2.

As shown by the arrow in FIG. 5, the third air path allows air taken into the machine room 2 from the air supply port 31 to bypass the condenser 12 and condense without passing through the condenser 12. This is an air path that passes through the machine fan 15 and is discharged from the exhaust port 32 to the outside of the machine room 2. That is, inside the machine room 2, a third air path is formed that does not pass through the condenser 12, which is the first heat exchanger described above.

Further, as shown in FIGS. 4 and 5, in this modification, an air path changing plate 41 is provided inside the machine room 2. The air path change plate 41 is an air path switching device that switches the air path through which the air flow generated by the condenser fan 15, which is the first fan described above, passes between the first air path and the third air path. It is.

The air path changing plate 41 is provided so as to be movable between the position shown in FIG. 4 and the position shown in FIG. When the air path changing plate 41 is in the position shown in FIG. 4, the air path changing plate 41 closes the aforementioned third air path and opens the first air path. Further, when the air path changing plate 41 is in the position shown in FIG. 5, the air path changing plate 41 is arranged between the condenser 12 and the condenser fan 15. Then, the first air passage is closed by the air passage changing plate 41, and the third air passage is opened.

During normal operation, the control device 50 places the air path changing plate 41 in the position shown in FIG. 4 . Therefore, during normal operation, the third air path is closed by the air path changing plate 41 and the first air path is opened. That is, the above-mentioned air path switching means is configured to switch between the first The air path through which the airflow generated by the condenser fan 15, which is the fan, passes is defined as the first air path.

Further, during the defrosting operation, the control device 50 sets the air path changing plate 41 to the position shown in FIG. 5 . Therefore, during the defrosting operation, the first air path is closed by the air path changing plate 41, and the third air path is opened. That is, the air path switching means is the first fan when the refrigerant evaporates in the condenser 12, which is the first heat exchanger, and condenses in the evaporator 14, which is the second heat exchanger. The air passage through which the air flow generated by the condenser fan 15 passes is set as the third air passage.

By doing so, the air flow generated by the condenser fan 15 can be prevented from passing around the condenser 12 while the condenser fan 15 is operated during the defrosting operation. Therefore, heat exchange between the condenser 12 and the air during the defrosting operation can be further suppressed, and the refrigerant leaked during the defrosting operation can be diffused while suppressing a decrease in defrosting efficiency.

Embodiment 2.
Embodiment 2 of the present invention will be described with reference to FIG. FIG. 6 is a sectional view schematically showing the overall structure of the showcase.

In Embodiment 2 described here, the direction of the airflow blown out from the outlet of the storage room during the defrosting operation is directed to the outside of the storage room, so that the airflow exists outside the showcase during the defrosting operation. It is something. The showcase according to the second embodiment will be described below, focusing on the differences from the first embodiment. The configuration whose description is omitted is basically the same as that of the first embodiment.

The showcase 100 according to this embodiment is an open showcase. That is, an opening 5 is formed in at least one surface of the storage chamber 3. In the configuration example described here, the opening 5 is provided in the front surface of the storage chamber 3 as in the first embodiment. This opening 5 is always open.

As shown in FIG. 6, the air outlet 22 is provided with a louver 23. The louver 23 is a wind direction changing means that changes the direction of the wind blown out from the air outlet 22. That is, by changing the direction of the louver 23, the direction of the air blown out from the air outlet 22 can be changed. Changing the orientation of the louver 23 is controlled by a control device 50. During normal operation, the control device 50 adjusts the orientation of the louver 23 so that the direction of air blown out from the air outlet 22 is directly downward. Therefore, during normal operation, the cold air blown out from the air outlet 22 descends along the opening surface of the opening 5. As a result, an air curtain of cold air is formed in the opening 5 of the storage chamber 3. A part of the cold air blown out from the outlet 22 remains in the storage chamber 3, and the storage chamber 3 is cooled.

In this embodiment, the control device 50 operates the evaporator fan 16 also during the defrosting operation. During the defrosting operation, the control device 50 adjusts the direction of the louver 23 so that the direction of the air blown out from the air outlet 22 is directed toward the opening 5 side. That is, the above-mentioned wind direction changing means operates when the refrigerant evaporates in the condenser 12, which is the first heat exchanger, and condenses in the evaporator 14, which is the second heat exchanger. Direct the wind blowing from the opening 5 side.

By doing so, the wind blown out from the air outlet 22 reaches the outside of the storage room 3 through the opening 5, and an air current is generated in the front side of the showcase 100. Therefore, when a refrigerant leak occurs in the showcase 100 during defrosting operation and the leaked refrigerant flows out to the outside of the showcase 100, the air in the indoor space where the showcase 100 is installed is removed from the air outlet 22. It is possible to diffuse the leaked refrigerant by stirring the refrigerant, and it is possible to prevent the leaked refrigerant from staying in the machine room 2 and forming a region where the refrigerant concentration exceeds a certain level.

In addition, in this embodiment, the condenser fan 15 may be stopped or may be operated during the defrosting operation. By stopping the condenser fan 15 during defrosting operation, if refrigerant leaks during defrosting operation, it is possible to diffuse the leaked refrigerant without reducing the defrosting efficiency, and the leaked refrigerant is prevented from stagnation. Thus, formation of a region where the refrigerant concentration exceeds a certain level can be suppressed.

However, as in the first embodiment, during the defrosting operation, it is more desirable to operate the condenser fan 15 at the second air volume described above. Furthermore, as shown in FIG. 6, during defrosting operation, when the condenser fan 15 generates an airflow in which the side where the opening 5 is formed is the downstream side, that is, an airflow from the exhaust port 32 toward the air supply port 31. good. That is, when the refrigerant evaporates in the condenser 12, which is the first heat exchanger, and the refrigerant condenses in the evaporator 14, which is the second heat exchanger, the condenser fan 15, which is the first fan, It is preferable to generate an airflow in which the side where the opening 5 is formed is on the downstream side.

By doing this, if refrigerant leaks in the machine room 2 during defrosting operation, the leaked refrigerant can be discharged to the front side of the showcase 100 where the air is being stirred by the wind blown out from the outlet 22. . Furthermore, the air in front of the showcase 100 can be more strongly agitated by both the wind from the blow-off port 22 and the wind from the condenser fan 15.

1 Housing 2 Machine room 3 Storage room 4 Display shelf 5 Opening 11 Compressor 12 Condenser 13 Expansion valve 14 Evaporator 15 Condenser fan 16 Evaporator fan 17 Refrigerant piping 18 Four-way valve 21 Suction port 22 Air outlet 23 Louver 31 Supply Air port 32 Exhaust port 41 Air path change plate 50 Control device 100 Showcase

Claims (4)

A casing in which a machine room and a storage room are formed;
a first heat exchanger disposed in a first air path formed inside the machine room, through which a refrigerant heavier than air flows;
a second heat exchanger disposed in a second air path communicating with the interior of the storage chamber via an outlet, and through which the refrigerant flows;
a first fan that generates airflow in the first air path;
a second fan that generates airflow in the second air path,
The first fan is
operating at a first air volume when the refrigerant condenses in the first heat exchanger and evaporates in the second heat exchanger;
When the refrigerant evaporates in the first heat exchanger and the refrigerant condenses in the second heat exchanger , it operates at a second air volume that is smaller than the first air volume and is not zero. Showcase. A third air path that does not pass through the first heat exchanger is formed inside the machine room,
Further comprising an air path switching means for switching an air path through which the air flow generated by the first fan passes between the first air path and the third air path,
The air path switching means is
When the refrigerant condenses in the first heat exchanger and the refrigerant evaporates in the second heat exchanger, an air path through which the airflow generated by the first fan passes is set to the first fan. Make it a wind path,
When the refrigerant evaporates in the first heat exchanger and the refrigerant condenses in the second heat exchanger, the air path through which the airflow generated by the first fan passes is set to the third fan. 2. The showcase according to claim 1, which has an air passage. Further comprising a wind direction changing means for changing the direction of the wind blown out from the air outlet,
The housing has the storage chamber formed with an opening on at least one surface,
The wind direction changing means directs the wind direction blown out from the outlet toward the opening side when the refrigerant evaporates in the first heat exchanger and the refrigerant condenses in the second heat exchanger. The showcase according to claim 1 or claim 2 . The first fan generates an airflow in which the side where the opening is formed is the downstream side when the refrigerant evaporates in the first heat exchanger and the refrigerant condenses in the second heat exchanger. The showcase according to claim 3, which generates a showcase.

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