JP7321297B2 - Showcase - Google Patents

Description

The present disclosure relates to showcases installed in stores such as supermarkets or convenience stores.

Stores such as supermarkets and convenience stores are equipped with refrigerated or frozen showcases. 2. Description of the Related Art Conventionally, there is a refrigeration system that includes one heat source device and a plurality of indoor units, and the indoor units are connected to the heat source device via refrigerant pipes (see Patent Document 1, for example). In Patent Document 1, the heat source device functions as a refrigerating device, and the indoor unit functions as a showcase.

Here, the Fluorocarbon Emission Control Law enacted in April 2015 stipulates that the global warming potential of refrigerants used in refrigeration equipment connected to showcases must be reduced to 1500 or less by 2025. ing. Hydrofluorocarbon-based mixed refrigerants such as R404A are used as refrigerants used in the above refrigeration systems. It's becoming In addition, R410A is used as a refrigerant in the above refrigeration system, and the global warming potential of R410A is 2090, which is higher than the numerical value specified by the Freon Emission Control Law. Therefore, it is necessary to reduce the total value of the global warming potential as soon as possible.

JP-A-4-297733

When propane, which is a flammable refrigerant, is used instead of R404A as the refrigerant used in the refrigeration system of Patent Document 1, the global warming potential of propane is 3.3, so the numerical value specified by the Freon Emission Control Law fit. However, in Patent Document 1, since a plurality of indoor units functioning as showcases are connected to the heat source unit, the amount of propane charged is several tens of kg. Since propane is a flammable refrigerant, the higher the amount of propane charged, the higher the possibility that the refrigerant concentration will exceed the lower combustion limit in the event of refrigerant leakage. Conventionally, there is a showcase equipped with a switch means such as an earth leakage breaker that can generate sparks when opened and closed. There was a risk that the component parts could become an ignition source.

The present disclosure has been made to solve the above problems, and provides a showcase that can improve safety against refrigerant leakage while conforming to the numerical values stipulated by the Freon Emission Control Law. It is an object.

A showcase according to the present disclosure includes a refrigerant circuit in which a compressor, a condenser, an expansion device, and an evaporator are connected by piping, and a refrigerant having a global warming potential of 1500 or less circulates, and the evaporator. A storage chamber that is cooled using cold air, a housing provided inside with a machine room with an air passage formed inside, a switch means that can generate sparks when opening and closing, and the compressor. wherein the condenser is arranged on the air passage in the machine room, and the machine room is provided with a first intake port for air passing through the air passage. and a second surface formed with an outlet for the air that has passed through the air passage. is arranged on the first surface side, and the control device is arranged on the lee side of the condenser .

According to the showcase according to the present disclosure, since a refrigerant with a global warming potential of 1500 or less is used in the refrigerant circuit, it is possible to conform to the numerical values stipulated by the Fluorocarbon Emission Control Law. In addition, switch means that can generate sparks when opening and closing is installed, and the switch means is located at a position where the refrigerant concentration is unlikely to increase and the lower limit of combustion is unlikely to be exceeded. It is arranged closer to the first surface than the end on the second surface side. Therefore, when refrigerant leakage occurs, the switching means is prevented from becoming an ignition source, and safety against refrigerant leakage can be improved.

2 is a schematic diagram showing the internal structure of the showcase according to Embodiment 1. FIG. 1 is a schematic diagram showing a drain water evaporator for a showcase according to Embodiment 1. FIG. FIG. 3 is a schematic diagram showing a condenser of the showcase according to Embodiment 1; FIG. 4 is a schematic diagram showing the positional relationship between the condenser and the condenser blower of the showcase and the arrangement of the earth leakage breaker according to the first embodiment; FIG. 4 is a diagram showing an operation pattern of the showcase according to Embodiment 1; FIG. FIG. 4 is a schematic diagram showing a concentration measurement position of an earth leakage breaker when refrigerant leaks from the showcase according to Embodiment 1; FIG. 4 is a schematic diagram of a concentration measurement point viewed from the front side of the showcase when refrigerant leaks from the showcase according to Embodiment 1; FIG. 4 is a schematic diagram of a concentration measurement point viewed from the upper surface side of the showcase when refrigerant leaks from the showcase according to Embodiment 1; FIG. 5 is a schematic diagram showing the internal structure of a showcase according to Embodiment 2;

Embodiments of the present disclosure will be described below with reference to the drawings. It should be noted that the present disclosure is not limited by the embodiments described below. Also, in the following drawings, the size relationship of each component may differ from the actual size.

Embodiment 1.
FIG. 1 is a schematic diagram showing the internal structure of a showcase 1 according to Embodiment 1. FIG. FIG. 2 is a schematic diagram showing the drain water evaporation device 22 of the showcase 1 according to the first embodiment. FIG. 3 is a schematic diagram showing the condenser 3 of the showcase 1 according to the first embodiment.

The configuration of the showcase 1 according to Embodiment 1 will be described below. In the following description, terms representing directions, such as "up", "down", "right", "left", "front", "back", etc., are used as appropriate for ease of understanding. These terms are for the purpose of description and are not intended to be limiting of the embodiments. Further, in the first embodiment, "top", "bottom", "right", "left", "front", "back", etc. are used when the showcase 1 is viewed from the front.

A showcase 1 according to Embodiment 1 is of a refrigerator built-in type. The showcase 1 is a vertical open showcase as shown in FIG. A housing 7 is composed of the heat insulating wall 8 and the inner layer partition plate 9 . Side plates (not shown) are provided on both left and right sides of the heat insulating wall 8 . In addition, an inner layer duct 10 is formed between the heat insulating wall 8 and the inner layer partition plate 9, and inside the inner layer partition plate 9, a storage chamber 11 is formed.

In the storage room 11, a plurality of shelves 12 for displaying merchandise are provided, for example, four stages. Here, the first shelf, which is the uppermost shelf, is the shelf 12a, the second shelf is the shelf 12b, the third shelf is the shelf 12c, and the fourth shelf is the shelf 12d. Light-emitting units 13 such as fluorescent lamps for illumination are provided on the lower front surfaces of the shelves 12a, 12b, and 12c and on the ceiling surface of the storage room 11, respectively. A bottom partition plate 19 is provided below the bottom surface of the storage chamber 11, and a bottom duct 14 communicating with the inner layer duct 10 is formed between the bottom surface of the storage chamber 11 and the bottom partition plate 19. . That is, the bottom partition plate 19 constitutes the bottom surface of the bottom duct 14 .

An internal fan 15 is provided in the bottom duct 14 . In addition, the evaporator 5 is vertically provided in the lower portion of the inner layer duct 10 located on the back side of the storage chamber 11 . The evaporator 5 exchanges heat between the air and the refrigerant to evaporate the refrigerant. The air whose heat is absorbed by the refrigerant in the evaporator 5, that is, the cool air generated in the evaporator 5 is blown out from the inner layer duct 10 into the storage chamber 11, thereby cooling the storage chamber 11. FIG.

An air outlet 17 is formed at the upper edge of a front opening 16 formed in the front of the storage chamber 11 , and a suction port 18 is formed at the lower edge of the front opening 16 . A machine room 20 is formed below the bottom partition plate 19 . In addition, the thin arrow of FIG. 1 has shown the flow direction of air.

A drain pan 21 for receiving drain water such as defrosted water generated from the evaporator 5 is provided on the bottom partition plate 19 . The drain pan 21 is provided with a drain port 21a for dropping the drain water toward a drain water evaporator 22 which is arranged in the machine room 20 and evaporates the drain water.

As shown in FIG. 2, the drain water evaporator 22 includes an evaporating plate 23 for storing drain water dropped from the drain port 21a, a plurality of evaporating plates 24 for evaporating the drain water, and a plurality of evaporating plates 24 integrally. and a plurality of supporting members 27 for supporting. The thin arrows in FIG. 2 indicate the direction of air flow, and the plurality of evaporating plates 24 are arranged parallel to the direction of air flow. A plurality of evaporating plates 24 are arranged on the evaporating dish 23 . The evaporating plate 24 is made of, for example, a non-woven fabric in which PET (polyethylene terephthalate) and glass fibers are integrated, or a porous resin molding.

As shown in FIG. 1, each shelf 12 incorporates a heater 28 . Further, the machine room 20 is provided with a compressor 2, a condenser 3, an expansion device 4, and a condenser blower 6 (see FIG. 4 described later), which constitute a refrigerating device. Further, the machine room 20 is provided with a control device 40, a high pressure switch 30, and an earth leakage breaker 32 (see FIG. 4, which will be described later).

The compressor 2 sucks a low-temperature, low-pressure refrigerant, compresses the sucked refrigerant, and discharges a high-temperature, high-pressure refrigerant. The compressor 2 is, for example, an inverter compressor or the like whose capacity, which is the output amount per unit time, is controlled by changing the operating frequency.

The condenser 3 performs heat exchange between the air and the refrigerant to condense and liquefy the refrigerant. As shown in FIG. 3, the condenser 3 includes a plurality of fins 3a arranged at regular intervals and a plurality of heat transfer tubes 3b perpendicular to the fins 3a. A U-shaped hairpin portion 3c is formed on one end side of the heat transfer tube 3b, and a U vent tube 3d connecting adjacent heat transfer tubes 3b is provided on the other end side of the heat transfer tube 3b. Here, the U vent pipe 3d is connected to the heat transfer pipe 3b by brazing or the like. Note that the fins 3a at the central portion of the condenser 3 are omitted in FIG. Further, thin arrows in FIG. 3 indicate the flow direction of the coolant.

The expansion device 4 reduces the pressure of the refrigerant to expand it. The throttle device 4 is, for example, an electronic expansion valve capable of adjusting the opening degree of the throttle.

The control device 40 is, for example, dedicated hardware or a CPU (also referred to as a central processing unit, a processing unit, an arithmetic unit, a microprocessor, a microcomputer, or a processor) that executes a program stored in a storage unit. It is configured. The control device 40 executes predetermined arithmetic processing based on input values from sensors (not shown) such as a temperature sensor, and controls each constituent device such as the compressor 2 and the condenser blower 6 .

The high pressure switch 30 is connected to the discharge side of the compressor 2, and stops the compressor 2 as a protection operation when the pressure discharged from the compressor 2, that is, the high pressure exceeds a set value.

As shown in FIG. 1, the showcase 1 includes a refrigerant circuit 50 in which a compressor 2, a condenser 3, an expansion device 4, and an evaporator 5 are sequentially connected by piping, and refrigerant circulates. Regarding the flow of refrigerant in the refrigerant circuit 50 , the refrigerant discharged from the compressor 2 is cooled in the condenser 3 by radiating heat to the outside air blown by the condenser blower 6 , and is decompressed by the expansion device 4 . The depressurized refrigerant is evaporated in the evaporator 5, sucked into the compressor 2, and then discharged from the compressor 2 again. When the pressure discharged from the compressor 2, that is, the high pressure exceeds the set value, the compressor 2 is stopped by the protection operation of the high pressure switch 30. FIG.

Further, as shown in FIG. 1, an operation panel 26 for user operation is provided on the outer side of the canopy 25 provided on the upper front side of the heat insulating wall 8 . For example, the operating pattern of the showcase 1 is input from the operation panel 26 . Details of the operation pattern will be described later.

FIG. 4 is a schematic diagram showing the positional relationship between the condenser 3 and the condenser blower 6 of the showcase 1 and the arrangement of the earth leakage breaker 32 according to the first embodiment. In addition, FIG. 4 is the figure which planarly viewed the inside of the machine room 20. As shown in FIG.
The condenser blower 6 blows air to cool the condenser 3, and as shown in FIG. , and discharged to the outside from the right side (hereinafter referred to as the second side 20c). That is, an air passage 20 a is formed in the machine room 20 by the condenser blower 6 . The condenser 3 is arranged on the air passage 20 a inside the machine room 20 . In addition, an inlet 20d is formed on the first surface 20b of the machine chamber 20, and an outlet 20e is formed on the second surface 20c.

A partition plate 33 composed of a first partition plate 33a and a second partition plate 33b is provided in the machine room 20 . A first partition plate 33a is provided on the front side (hereinafter referred to as the third surface 20f) of the condenser 3, and a second partition plate 33a is provided on the back side (hereinafter referred to as the fourth surface 20g) of the condenser 3. A partition plate 33b is provided. Specifically, the first partition plate 33 a is provided from the third surface 20 f of the showcase 1 to the front surface of the condenser 3 . Further, the second partition plate 33b is provided from the fourth surface 20g of the showcase 1 to the rear surface of the condenser 3. As shown in FIG. By providing the partition plate 33 in this manner, the air taken into the machine room 20 is reliably passed through the condenser 3 .

A discharge pipe 34 is connected to the compressor 2 , and the discharge pipe 34 is also connected to the condenser 3 . That is, the refrigerant discharged from the compressor 2 flows into the condenser 3 through the discharge pipe 34 . The machine room 20 is partitioned into a space with the discharge pipe 34 and a space without the discharge pipe 34 by the first partition plate 33a, the condenser 3, and the second partition plate 33b. It is difficult for the leaked refrigerant to reach the space without the refrigerant, and the concentration of the refrigerant does not increase.

An earth leakage breaker 32 is provided in the machine room 20 to detect an earth leakage and interrupt the flow of electricity. The earth leakage breaker 32 is switch means that can generate sparks when opened and closed. Three earth leakage breakers 32 are shown in FIG. The earth leakage breaker 32b according to Embodiment 1 is arranged on the third surface 20f side and the first surface 20b side of the machine room 20, and is arranged on the fourth surface 20g side and the first surface 20b side in the machine room 20. What is shown is the earth leakage breaker 32c according to the first embodiment. The earth leakage breaker 32b may be arranged closer to the second surface 20c than the first partition plate 33a (see the dashed square Y1 in FIG. 4), and the earth leakage breaker 32c may be arranged closer to the second surface 20c than the second partition plate 33b. It may be arranged on the second surface 20c side (see broken-line square Y2 in FIG. 4). That is, the ends of the earth leakage breakers 32b and 32c closest to the second surface 20c side are closer to the first surface 20b than the ends of the condenser 3 closest to the second surface 20c (see broken line Y in FIG. 4). It is sufficient if they are arranged so as to be Further, the earth leakage breaker 32a is arranged at a position where it can be operated by removing a front lower panel (not shown) provided at the front lower part of the showcase 1. As shown in FIG. 4 and FIG. 6, which will be described later, show an earth leakage breaker 32a.

Compressor 2 and control device 40 are arranged on the right side of condenser 3 . Also, parts (not shown) included in the control device 40 are structured so as not to become an ignition source. Also, with regard to the earth leakage breaker 32, the arc that occurs when the contacts are opened when a large current is cut off from the main contact is extinguished by being extended by the multistage barrier plates. Structural gaps are provided to prevent parts from breaking. Therefore, it is difficult to structure the earth leakage breaker 32 so that it does not become an ignition source. It is also possible to cover the earth leakage breaker 32 with a container made of steel so that it does not become an ignition source. increase. Therefore, it is necessary to improve the safety against refrigerant leakage by another method.

Moreover, the power supply specification of the showcase 1 is single-phase 100V. Therefore, almost no electrical work is required at the place where the showcase 1 is installed, and the showcase 1 can be used simply by inserting the power plug of the showcase 1 into an outlet, which is convenient for use at special events, spots, refurbishment, and the like.

Next, the refrigerant, which is the working fluid of the showcase 1 according to Embodiment 1, will be described.
In showcase 1 according to Embodiment 1, a flammable refrigerant such as propane and isobutane, which is an HC refrigerant having a global warming potential of 1500 or less, is used as the refrigerant circulating in refrigerant circuit 50 . Propane has a global warming potential of 3.3 and isobutane has a global warming potential of 4. In the technical field, the global warming potential is also abbreviated as GWP.

The showcase 1 according to Embodiment 1 is of a type with a built-in refrigerating device, and since the refrigerating device and the evaporator 5 are integrated, the size can be reduced. Therefore, the amount of refrigerant to be charged can be reduced. For example, in the case of propane, the liquid density is low, so the amount to be charged can be reduced to about 500 g. Here, the IEC (International Electrotechnical Commission) deregulated the upper limit of the amount of flammable refrigerant charged in household and commercial refrigeration equipment, and expanded it from 150 g to 500 g. Therefore, even if a flammable refrigerant such as propane with a global warming potential of 1500 or less is used, the showcase 1 that satisfies the safety standards against refrigerant leakage can be obtained.

Next, the operation of showcase 1 according to Embodiment 1 will be described.
As shown in FIG. 1, when the internal blower 15 is driven, the air in the bottom duct 14 is blown out toward the inner layer duct 10 on the back side, heat exchanged in the evaporator 5, and then blown up. The blown air is then blown out from the outlet 17 formed at the upper edge of the front opening 16 toward the suction port 18 formed at the lower edge of the front opening 16 .

As a result, a cool air curtain is formed in the front opening 16 formed in the front of the storage chamber 11 . Therefore, the cold air curtain prevents or suppresses the intrusion of outside air from the front opening 16, and part of the air forming the cold air curtain circulates in the storage chamber 11, thereby cooling the storage chamber 11. be done. When the store in which the showcase 1 is installed is closed, the night cover 31 is hung over the showcase 1 and the front opening 16 is closed by the night cover 31 .

In addition, the air blown out from the outlet 17 forms a cool air curtain or cools the inside of the storage chamber 11, then returns to the bottom duct 14 from the suction port 18 and is sucked into the inside fan 15 again. .

During the operation of the showcase 1, drain water such as defrosted water from the evaporator 5 drops to the drain pan 21, then drops to the evaporation plate 24 of the drain water evaporator 22 from the drain port 21a, and accumulates in the evaporation plate 23. . Drain water accumulated in the evaporating plate 23 is sucked up by the evaporating plate 24 by capillary action and is contained in the evaporating plate 24 . As a configuration for soaking drain water in the evaporating plate 24 , the drain water accumulated in the evaporating plate 23 may be sucked up by a pump or the like and sprinkled from above the evaporating plate 24 .

Then, the air from the condenser blower 6 passes through the condenser 3 and is heated, and then flows toward the drain water evaporation device 22 . The warm air flowing toward the drain water evaporator 22 hits the evaporator plate 24 of the drain water evaporator 22, whereby the drain water contained in the evaporator plate 24 is evaporated.

The water adhering to the evaporator 5 forms frost on the evaporator 5 when the temperature inside the showcase 1 is about 10° C. or less while the showcase 1 is in operation. As the frost formation on the evaporator 5 progresses, the heat exchange amount of the evaporator 5 decreases and the evaporation performance deteriorates. A method for detecting the degree of frost formation on the evaporator 5 is, for example, the operating time of the compressor 2 . In that case, the defrosting of the evaporator 5 is started after the compressor 2 has been operated for a predetermined period of time. A heater (not shown) is provided in the evaporator 5, and defrosting is performed by energizing the heater for a predetermined time. When defrosting is performed, the drain water drops into the drain pan 21 as described above, then drops onto the evaporation plate 24 of the drain water evaporator 22 through the drain port 21a, and accumulates in the evaporation plate 23. Note that the evaporating dish 23 may be provided with a float switch (not shown) for detecting the amount of drain water.

FIG. 5 is a diagram showing an operation pattern of showcase 1 according to the first embodiment.
The first shelf 12a, the second shelf 12b, the third shelf 12c, and the fourth shelf 12d can be used for both hot (heating) and cold (cooling). The control device 40 has a plurality of operation patterns. As shown in FIG. 5, there are four operating patterns: "all hot", "2nd stage hot", "1st stage hot", and "all cold".

In "all hot", as shown in FIG. 5, all the shelves 12 are hot, the first shelf 12a, the second shelf 12b, the third shelf 12c, and the fourth shelf 12d are all heated by turning on each heater 28 .

In "two-stage hot" and "one-stage hot", as shown in FIG. 5, the shelf 12 corresponding to hot is heated by turning on the corresponding heater 28, and the shelf 12 corresponding to cold is heated. It is cooled by cold air produced by the evaporator 5 .

In "all cold", as shown in FIG. 5, all the shelves 12 are cold, the first shelf 12a, the second shelf 12b, the third shelf 12c, and the fourth shelf All of 12d are cooled by cold air produced by evaporator 5.

In addition, there is also a "stop" in the operation pattern. “Stop” is an operation pattern instructed when stopping the operation of the compressor 2 .

In the first embodiment, the case where the number of shelves 12 is four has been described, but the present invention is not limited to this, and other numbers such as three or five may be used. Also, the number of operation patterns is determined by the number of shelves 12 . Further, the internal blower 15 is driven except for "all hot", and is stopped in "all hot".

FIG. 6 is a schematic diagram showing the concentration measurement positions of the earth leakage breaker 32a when refrigerant leaks from the showcase 1 according to the first embodiment. In addition, FIG. 6 is the figure which planarly viewed the inside of the machine room 20. As shown in FIG.
Next, a refrigerant leakage test from the discharge pipe 34 according to Embodiment 1 will be described.
As shown in FIG. 6, 500 g of refrigerant, which is the allowable filling amount, is leaked from the leak point Z of the discharge pipe 34 of the compressor 2 at a leak rate of 7.5 kg/h for the four-minute total amount. Here, the lowest concentration at which combustible gas mixed with air causes combustion upon ignition is called the lower flammable limit (LFL). For propane, the lower flammability limit is 2.1 vol%.

In the refrigerant leakage test from the discharge pipe 34, it was found that the refrigerant concentration around the earth leakage breaker 32a was 2.1 vol % or more, which is the lower combustion limit of propane. When the earth leakage breaker 32a was opened and closed in an atmosphere of 4 vol %, which is equal to or higher than the lower combustion limit of propane, no combustion was observed when the load current of the showcase 1 was about 5A. However, when the load current of the showcase 1 exceeded 5A, combustion was observed, and the outside of the earth leakage breaker 32a also burned. On the other hand, it was found that the refrigerant concentration around the earth leakage breakers 32b and 32c is less than 2.1 vol %, which is the lower combustion limit of propane. Therefore, the position of the earth leakage breakers 32b and 32c on the windward side of the condenser 3 can improve safety more than the position of the earth leakage breaker 32a on the leeward side of the condenser 3. Even if the earth leakage breakers 32b and 32c are not positioned on the windward side of the condenser 3, if they are positioned on the first surface 20b side of the end of the condenser 3 closest to the second surface 20c side, the same safety can be achieved. can be improved. In addition, the U vent pipe 3d of the condenser 3 is connected to the heat transfer pipe 3b by brazing or the like, and there is a risk of refrigerant leakage from the connecting portion between the U vent pipe 3d and the heat transfer pipe 3b. Therefore, by arranging the earth leakage breakers 32b and 32c on the side of the hairpin portion 3c where there is no connecting portion of the condenser 3, safety can be further improved.

Here, in the machine room 20, the earth leakage breaker 32a is located in the space on the side where the discharge pipe 34 is arranged with the first partition plate 33a, the condenser 3, and the second partition plate 33b as boundaries. The earth leakage breakers 32b and 32c are located in the space on the side where the discharge pipe 34 is not arranged. In other words, the position of the earth leakage breaker 32a is close to the leakage point Z of the discharge pipe 34, and the leaked refrigerant tends to accumulate and the concentration of the refrigerant increases. On the other hand, the positions of the earth leakage breakers 32b and 32c are separated from the space where the discharge pipe 34 is located by the first partition plate 33a, the condenser 3, and the second partition plate 33b. difficult to increase.

As described above, the portion of the inner layer partition plate 9 located in front of the evaporator 5 has a plurality of holes ( not shown) are formed. Therefore, when the refrigerant leaks from the evaporator 5, the leaked refrigerant leaks into the storage chamber 11 from a plurality of holes formed in the inner layer partition plate 9 as indicated by arrows EE and FF in FIG. It may leak out of the showcase 1 from there.

Also, the refrigerant leaking from the evaporator 5 may leak into the machine room 20 from the drain port 21 a of the drain pan 21 . The light-emitting part 13, the internal air blower 15, and the heater 28, which are components in the showcase 1, can be structured so as not to become an ignition source. However, refrigerant leaking out of the showcase 1 may become an ignition source outside the showcase 1, such as an outlet. Therefore, it is important to reduce the concentration of the refrigerant outside the showcase 1 even when refrigerant leakage occurs.

Next, a refrigerant leakage test was conducted using propane as the refrigerant circulating in the refrigerant circuit 50 of the showcase 1 .

FIG. 7 is a schematic diagram of the concentration measurement point seen from the front side of the showcase 1 when the refrigerant leaks from the showcase 1 according to the first embodiment. FIG. 8 is a schematic diagram of the concentration measurement point seen from the upper surface side of the showcase 1 when refrigerant leaks from the showcase 1 according to the first embodiment.

A, B, C, D, and E in FIG. 7 indicate refrigerant concentration measurement points specified in IEC60335-2-89:2019. AFV in FIG. 7 shows the front of the showcase 1 . APB in FIG. 8 shows the upper surface of the showcase 1 . R in FIG. 8 indicates the walls of the test chamber. X in FIG. 8 indicates the larger value of the distance from the wall R specified by the manufacturer of the showcase 1 and 50 mm from the wall. FL in FIG. 7 indicates the floor of the test room. Z in FIG. 8 indicates a refrigerant leak location of the evaporator 5 .

A method of simulating refrigerant leakage from the refrigerant circuit 50 when the refrigerant leaks from the showcase 1 is described in JISC9335-2-24 or JISC9335-2-89. Conduct a refrigerant leakage test by the method of JISC9335-2-24 or JISC9335-2-89, and measure the concentration of the refrigerant at the concentration measurement points E, C, and D where the leakage concentration is high shown in IEC60335-2-89:2019. carried out. The refrigerant concentration was measured in each of the operation patterns "all cold", "all hot", "two-stage hot", and "one-stage hot".

In addition, as the condenser blower 6, a brushless blower equipped with a DC (Direct Current) brushless motor having no brush structure and no internal contact structure is used. Refrigerant concentration was measured in the case of Similarly, a DC brushless fan was used as the indoor fan 15, and the concentration of the refrigerant was measured at "full speed", "medium speed", and "stopped". Here, the rotation speeds of the condenser blower 6 and the inside blower 15 are full speed>medium speed.

In the case of a blower equipped with a brush motor with a brush structure, the brush part electrically opens and closes during the rotation of the coil, so sparks may fly, so be careful when using a flammable refrigerant. need. On the other hand, a DC brushless fan equipped with a DC brushless motor has no rotating coil and does not have a brush, so it does not electrically open and close, and is safe even when using a flammable refrigerant.

The amount of refrigerant is set to 500 g, which is the allowable filling amount of combustible refrigerant revised by IEC60335-2-89:2019, and the leak rate is set to 7.5 kg/h for a four-minute total leak rate. The lower combustion limit is defined as the lowest concentration at which a combustible gas mixed with air causes combustion upon ignition. For propane, the lower flammability limit is 2.1 vol%.

When the operation pattern is "all hot", the inside of the storage chamber 11 is not cooled, so the condenser blower 6 is normally stopped. be. In addition, if the refrigerant leaks from the evaporator 5 and the condenser blower 6 is stopped when the operation pattern is "stop", the refrigerant concentration at the concentration measurement points E, C, and D may exceed the lower combustion limit of propane. have a nature.

Even if the refrigerant leaks from the condenser 3, if the condenser blower 6 is stopped when the operation pattern is "all hot", the refrigerant concentration at the concentration measurement points E, C, and D may exceed the lower combustion limit of propane. have a nature. Therefore, when the operation pattern is "all hot" or "stop", it is necessary to drive the condenser fan 6 even if the condenser fan 6 is normally stopped. When the operation pattern is "all hot" or "stopped" and the condenser blower 6 is in operation, the refrigerant concentrations at the concentration measurement points E, C, and D are the lower limit of propane combustion. Less than 1 vol%.

The refrigerant leaks through a plurality of holes (not shown) in the inner layer partition plate 9 formed in front of the evaporator 5, and the refrigerant leaking from the evaporator 5 through the holes As indicated by arrows EE and FF in 1, there are cases where the liquid leaks out of the showcase 1 from inside the storage room 11 . In this case, when the condenser blower 6 is driven, the leaked refrigerant is agitated, and the refrigerant concentrations at the concentration measurement points E, C, and D become low. Refrigerant that may leak into the machine room 20 from the drain port 21a of the drain pan 21 is also agitated when the condenser blower 6 is driven. Also, when the refrigerant leaks from the compressor 2 or the condenser 3 in the machine room 20 , the leaked refrigerant is agitated by the condenser blower 6 . Then, the refrigerant gradually leaks out of the showcase 1 through the gaps of the housing 7 forming the machine room 20 . At the positions of the earth leakage breakers 32b and 32c measured at the same time as this test, it was found that the refrigerant concentration did not exceed 2.1 vol %, which is the lower combustion limit of propane.

As described above, in the showcase 1 according to Embodiment 1, the compressor 2, the condenser 3, the expansion device 4, and the evaporator 5 are connected by piping, and the refrigerant circuit in which the refrigerant having a global warming potential of 1500 or less circulates. 50, a storage chamber 11 that is cooled using the cold air generated by the evaporator 5, and a housing 7 provided therein with a machine room 20 in which an air passage 20a is formed, and an opening and closing and switch means that can generate a spark when the spark is generated. The condenser 3 is arranged on an air passage 20a in a machine room 20. The machine room 20 includes a first surface 20b formed with an intake port 20d for air passing through the air passage 20a, a wind and a second surface 20c formed with an outlet 20e for air passing through the passage 20a. The switch means is arranged in the machine room 20 closer to the first surface 20b than the end of the condenser 3 closest to the second surface 20c.

According to the showcase 1 according to the first embodiment, since the refrigerant circuit 50 uses a refrigerant having a global warming potential of 1500 or less, it is possible to comply with the numerical values stipulated by the Fluorocarbon Emission Control Law. In addition, the condenser in the machine room 20 is equipped with switch means that can generate sparks when opened and closed, and the switch means is located at a position where the refrigerant concentration is unlikely to increase and the lower limit of combustion is unlikely to be exceeded. 3 is disposed closer to the first surface 20b than the end portion of 3 closest to the second surface 20c. Therefore, when refrigerant leakage occurs, the switching means is prevented from becoming an ignition source, and safety against refrigerant leakage can be improved. Furthermore, when the switch means is not arranged on the air passage of the condenser 3, the switch means itself can be prevented from causing a pressure loss, and adhesion of dust to the switch means can be prevented. can.

Further, in the showcase 1 according to Embodiment 1, the discharge pipe 34 is provided in the machine room 20, is connected to the compressor 2 and the condenser 3, and causes the refrigerant discharged from the compressor 2 to flow into the condenser 3. and a partition plate 33 that divides the machine chamber 20 into a space with the discharge pipe 34 and a space without the discharge pipe 34, and the switch means is arranged in the space without the discharge pipe 34.

According to the showcase 1 according to Embodiment 1, the switch means is arranged in the space without the discharge pipe 34, which is the space in the machine room 20 where the refrigerant concentration is less likely to increase and the lower limit of combustion is less likely to be exceeded. . Therefore, it is possible to further suppress the switching means from becoming an ignition source when refrigerant leakage occurs, thereby further improving the safety against refrigerant leakage.

Further, in the showcase 1 according to Embodiment 1, the condenser 3 includes a plurality of fins 3a arranged at regular intervals and a plurality of heat transfer tubes 3b orthogonal to the plurality of fins 3a. A U-shaped hairpin portion 3c is formed on one end side of the heat transfer tube 3b, and a U vent tube 3d connecting the adjacent heat transfer tubes 3b is provided on the other end side of the heat transfer tube 3b. is arranged on the side of the hairpin portion 3c.

According to the showcase 1 according to Embodiment 1, the switch means is arranged on the side of the hairpin portion where there is no connecting portion of the condenser 3, so safety can be further improved.

Further, in showcase 1 according to Embodiment 1, the power supply specification is single-phase 100V. According to the showcase 1 according to Embodiment 1, since the power supply specification is single-phase 100 V, almost no electrical work is required at the installation site, and the showcase 1 can be used simply by inserting the power plug into an outlet. , special events, spots, renovation use, etc.

Moreover, in the showcase 1 according to Embodiment 1, the load current is 5 A or less. According to the showcase 1 according to Embodiment 1, since the load current is 5 A or less, safety can be further improved.

Further, the showcase 1 according to the first embodiment is provided in the machine room 20, and includes the condenser blower 6 forming the air passage 20a, the plurality of shelves 12 provided in the storage room 11, and the shelves 12 and a controller 40 having an operation pattern of "all hot" to turn on all the heaters 28 and "stop" to stop the compressor 2. Then, the controller 40 drives the condenser fan 6 when "all hot" or "stopped".

According to the showcase 1 according to the first embodiment, even when the condenser blower 6 is driven even in the "all hot" or "stopped" state, even if refrigerant leakage occurs, the machine room It is possible to agitate the refrigerant that has leaked inside 20 and outside the showcase 1 . Therefore, the concentration of the refrigerant inside the machine room 20 and outside the showcase 1 is less likely to increase, and the safety against refrigerant leakage can be improved.

In the first embodiment, refrigerant leakage from the discharge pipe 34 was described, but refrigerant leakage also occurs in a suction pipe (not shown) that is connected to the compressor 2 and causes refrigerant to flow into the compressor 2. Possibly, the description of the discharge tube 34 above could be replaced by a suction tube.

Embodiment 2.
The second embodiment will be described below, but the description of the parts that overlap with those of the first embodiment will be omitted, and the same reference numerals will be given to the same or corresponding parts as those of the first embodiment.

In Embodiment 1, the condenser 3 and the condenser blower 6 are arranged in a direction that is 90° with respect to arrows EE and FF, which are refrigerant leak directions, as shown in FIGS. 1 and 4 . That is, the condenser 3 and the condenser blower 6 are arranged so as to take air into the machine room 20 from the side of the showcase 1 . The reason why the condenser 3 and the condenser blower 6 are arranged in this way is to enable maintenance of the drain water evaporation device 22 from the front of the showcase 1 .

FIG. 9 is a schematic diagram showing the internal structure of the showcase 1 according to the second embodiment. The thin arrows in FIG. 9 and the thick arrows in the machine room 20 indicate the direction of air flow.
On the other hand, in the second embodiment, the condenser 3 and the condenser blower 6 are arranged in the same direction as the arrows EE and FF, which are the refrigerant leak directions, as shown in FIG. That is, the condenser 3 and the condenser blower 6 are arranged so as to take air into the machine room 20 from the front side of the showcase 1 . By arranging the condenser 3 and the condenser blower 6 in this way, the leaked refrigerant can be easily sucked and agitated, and the rotation speed of the condenser blower 6 may be reduced. Since the refrigerant leaks from the machine room 20 and the evaporator 5, an upper cover 35 is provided on the upper part of the canopy 25 provided above the machine room 20 and the evaporator 5. An earth leakage breaker 32d, which is a switch means that can generate sparks, may be provided.

As described above, in the showcase 1 according to the second embodiment, the compressor 2, the condenser 3, the expansion device 4, and the evaporator 5 are connected by piping, and the refrigerant circuit in which the refrigerant having a global warming potential of 1500 or less circulates. 50, a storage room 11 that is cooled by using cold air generated by the evaporator 5, and a machine room 20 located below the storage room 11 and having an air passage 20a formed therein. and switch means that can generate sparks when opened and closed. The evaporator 5 is formed on the rear side of the housing 7 relative to the storage chamber 11 and is arranged in an inner layer duct that blows cold air to the storage chamber 11. are also arranged above.

According to the showcase 1 according to the second embodiment, since the refrigerant circuit 50 uses a refrigerant having a global warming potential of 1500 or less, it is possible to meet the numerical values stipulated by the Fluorocarbon Emission Control Law. In addition, the storage chamber 11 and the evaporator 5 are equipped with switch means that can generate sparks when opening and closing, and the switch means is located at a position where the refrigerant concentration is unlikely to increase and the lower limit of combustion is unlikely to be exceeded. is also arranged upward, it is possible to improve safety against refrigerant leakage.

In Embodiments 1 and 2, an example in which the showcase 1 is a multistage open showcase is shown, but the same applies to the flat single-sided type, the flat double-sided type, the reach-in type, and the like.

1 showcase, 2 compressor, 3 condenser, 3a fin, 3b heat transfer tube, 3c hairpin portion, 3d U vent pipe, 4 expansion device, 5 evaporator, 6 blower for condenser, 7 housing, 8 heat insulating wall, 9 Inner layer partition plate 10 Inner layer duct 11 Storage room 12 Shelf 12a Shelf 12b Shelf 12c Shelf 12d Shelf 13 Light emitting part 14 Bottom duct 15 In-fridge blower 16 Front opening 17 Air outlet 18 Suction port 19 Bottom partition plate 20 Machine room 20a Air passage 20b First surface 20c Second surface 20d Suction port 20e Discharge port 20f Third surface 20g Fourth surface 21 Drain pan 21a Drainage port , 22 drain water evaporator, 23 evaporation dish, 24 evaporation plate, 25 canopy, 26 operation panel, 27 support member, 28 heating heater, 30 high pressure switch, 31 night cover, 32a earth leakage breaker, 32b earth leakage breaker, 32c earth leakage Breaker 32d Earth leakage breaker 33 Partition plate 33a First partition plate 33b Second partition plate 34 Discharge pipe 35 Top cover 40 Control device 50 Refrigerant circuit.

Claims (11)

a refrigerant circuit in which a compressor, a condenser, a throttle device, and an evaporator are connected by piping, and a refrigerant having a global warming potential of 1500 or less circulates;
A housing provided therein with a storage room that is cooled by using the cold air generated by the evaporator, and a machine room with an air passage formed inside;
switch means capable of generating sparks when opened and closed;
and a control device that controls the compressor ,
The condenser is arranged on the air passage in the machine room,
The machine room has a first surface formed with an intake port for the air passing through the air passage and a second surface formed with an outlet port for the air passing through the air passage,
The switch means is
is arranged in the machine room on the first surface side of the end of the condenser closest to the second surface,
The controller is located downwind of the condenser
Showcase. a refrigerant circuit in which a compressor, a condenser, a throttle device, and an evaporator are connected by piping, and a refrigerant having a global warming potential of 1500 or less circulates;
A housing provided therein with a storage room that is cooled by using the cold air generated by the evaporator, and a machine room with an air passage formed inside;
switch means capable of generating sparks when opened and closed,
The condenser is arranged on the air passage in the machine room,
The machine room has a first surface formed with an intake port for the air passing through the air passage and a second surface formed with an outlet port for the air passing through the air passage,
The switch means is
is arranged in the machine room on the first surface side of the end of the condenser closest to the second surface,
The condenser includes a plurality of fins arranged at regular intervals and a plurality of heat transfer tubes perpendicular to the plurality of fins, and one end of the heat transfer tube is formed with a U-shaped hairpin portion, The other end of the heat tube is provided with a U-bent tube that connects adjacent heat transfer tubes,
The switch means is arranged on the hairpin portion side of the condenser.
showcase . A control device that controls the compressor,
The showcase according to claim 2 , wherein the control device is arranged downwind of the condenser. Looking at the machine room from the front,
The showcase according to any one of claims 1 to 3 , wherein the first surface is one side surface of the machine room, and the second surface is the other side surface of the machine room. a discharge pipe provided in the machine room, connected to the compressor and the condenser, and allowing refrigerant discharged from the compressor to flow into the condenser;
a partition plate that divides the machine room into a space with the discharge pipe and a space without the discharge pipe,
The showcase according to any one of claims 1 to 4 , wherein the switch means is arranged in a space without the discharge pipe. a condenser blower provided in the machine room and forming the air passage;
a plurality of shelves provided within the storage chamber;
and a heater provided on each shelf,
The control device is
It has an operation pattern of "all hot" that turns on all of the heaters and "stop" that stops the compressor,
6. A showcase as claimed in claim 4 or 5 as dependent on claim 1 or claim 3 , wherein the condenser blower is driven when "all hot" or "stopped". a refrigerant circuit in which a compressor, a condenser, a throttle device, and an evaporator are connected by piping, and a refrigerant having a global warming potential of 1500 or less circulates;
a storage chamber that is cooled using cold air generated by the evaporator; and a housing located below the storage chamber and provided with a machine room having an air passage formed therein;
switch means capable of generating sparks when opened and closed;
a condenser blower provided in the machine room and forming the air passage;
a plurality of shelves provided within the storage chamber;
a heater provided on each shelf;
A control device having an operation pattern of "all hot" that turns on all of the heaters and "stop" that stops the compressor,
The evaporator is formed on the rear side of the housing relative to the storage chamber, and is arranged in an inner layer duct that blows cold air into the storage chamber,
The switch means is arranged above the machine room and the evaporator,
The controller activates the condenser blower when "all hot" or "stopped"
Showcase. The switch means is
The showcase according to claim 7, arranged outside the inner layer duct. The switch means is
The showcase according to claim 8, wherein the showcase is arranged in an upper cover provided on the upper part of the inner layer duct. The showcase according to any one of claims 1 to 9, wherein the power supply specification is single-phase 100V. The showcase according to any one of claims 1 to 10, wherein the load current is 5A or less.

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