JP5261099B2 - Low temperature showcase - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an open showcase allowing the stable execution of energy-saving operation when an opening is blocked with a night cover. <P>SOLUTION: This low-temperature showcase 1 includes: a refrigerant circuit 25 including a compressor 26, a condenser 47 and a cooler 46; and a condensing fan 43 for air-cooling the compressor 26 and the condenser 47. Based on an energizing current of the compressor 26 detected by a current sensor 56, the control device 20 reduces the rotating speed of the condensing fan 43 when the energizing current is low, and increases the rotating speed of the condensing fan 43 when the energizing current of the compressor 26 is high. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a low-temperature showcase including a refrigerant circuit including a compressor, a condenser, and a cooler, and a condensing fan for air-cooling the compressor and the condenser.

  Conventionally, showcases installed in stores such as supermarkets and convenience stores have been formed with storage rooms for displaying products inside, and the storage rooms are composed of compressors, condensers, coolers, etc. The cooling device is cooled to a predetermined temperature. In an open showcase with a large opening, a cold air curtain is formed in the opening to suppress the intrusion of outside air into the storage room, but during the daytime when many customers come to the store, customers and shop assistants etc. Since disturbance occurs, cold air is likely to leak, and outside air enters the storage chamber. This makes it difficult to maintain the temperature in the storage chamber at a predetermined cooling temperature. Therefore, in the cooling operation at the time of opening a store such as in the daytime, a cooling target temperature is set and maintained at a predetermined cooling temperature in consideration of a temperature increase due to disturbance.

On the other hand, at night or when the store is closed, the disturbance due to the traffic of customers and the like is reduced, so that the leakage of cold air is reduced. Moreover, since the front opening part of an open showcase is obstruct | occluded with a night cover, the penetration | invasion of external air and the leakage of cold air are suppressed. Therefore, since the heat load in the storage chamber is reduced, the operation rate of the compressor is reduced, and energy saving operation can be executed.
JP 2002-257451 A

  However, even in such a case, the condensing fan for forcibly cooling the compressor and the condenser has always been operated at a constant speed. Therefore, as the operating rate of the compressor decreases, the heat generated by the compressor Even when the amount was reduced, it was operated in the same manner as a normal cooling operation.

  For this reason, the condensing fan is operated more than necessary, and effective energy-saving operation cannot be realized. Further, since the opening is normally blocked by the night cover at night, the night The noise caused by the operation of the condensing fan was a problem.

  The present invention has been made in order to solve the conventional technical problems, and can control the operation of the condensing fan in accordance with the operation state of the compressor to perform the energy-saving operation. Provide a case.

The low-temperature showcase of the present invention includes a refrigerant circuit including a compressor, a condenser, and a cooler, and a condensing fan for air-cooling the compressor and the condenser, and cool air exchanged with the cooler is provided in an opening of the storage chamber. Cooling the storage chamber while forming a cool air curtain by discharging, a night cover covering the opening of the storage chamber, current detection means for detecting the energization current of the compressor, compressor, condensing fan A control device that controls the operation of the storage device, and when the control device determines that the opening of the storage chamber is covered by the night cover , the control device is energized based on the energization current of the compressor detected by the current detection means. When the current is low, the rotational speed of the condensing fan is reduced, and when the energization current of the compressor is high, the rotational speed of the condensing fan is increased.

The low-temperature showcase of the invention of claim 2 includes a lighting device that illuminates the storage chamber in the above invention, and the control device is that the lighting device is turned off or that the temperature in the storage chamber is stable, Alternatively, it is determined that the opening of the storage chamber is covered by the night cover when the operating frequency of the compressor is lower than a predetermined low operating frequency, and the condensing fan is normally operated at the maximum rotation speed. If it is determined that the opening of the storage chamber is covered by the cover, the rotational speed control of the condensing fan according to the energization current of the compressor should be executed between the maximum speed and the minimum speed. Features.

The low-temperature showcase of the present invention includes a refrigerant circuit including a compressor, a condenser, and a cooler, and a condensing fan for air-cooling the compressor and the condenser, and cool air exchanged with the cooler is provided in an opening of the storage chamber. Cooling the storage chamber while forming a cool air curtain by discharging, a night cover covering the opening of the storage chamber, current detection means for detecting the energization current of the compressor, compressor, condensing fan A control device that controls the operation of the storage device, and when the control device determines that the opening of the storage chamber is covered by the night cover , the control device is energized based on the energization current of the compressor detected by the current detection means. If current is low to reduce the rotational speed of the condensing fan, so when energization current of the compressor is high and to increase the rotational speed of the condensing fan, Knight By opening is covered by a bar, the thermal load of the refrigerator is reduced, if the energization current of the compressor is lowered, it is possible to reduce the rotational speed of the condensing fan accordingly.

As a result, compared to the conventional case where the condensing fan is operated at a constant speed, power consumption can be reduced, energy-saving operation can be realized , and noise reduction at the time of closing the store can be achieved. It can be realized.

According to the second aspect of the invention, in the above invention, an illumination device for illuminating the storage compartment, the control device, the lighting device is turned off, or, the temperature of the storage compartment is stable, or, When the operating frequency of the compressor is lower than the predetermined low operating frequency, it is judged that the opening of the storage room is covered by the night cover, and the condensing fan is normally operated at the maximum rotation speed. When it is determined that the opening of the storage chamber is covered , the rotation speed control of the condensing fan is executed between the maximum rotation speed and the minimum rotation speed in accordance with the energization current of the compressor . , To accurately determine that the opening of the storage room has been closed by the night cover, and to control the rotational speed of the condensing fan according to the waste heat of the compressor at the time of closing without trouble It can become.

  Next, embodiments of the present invention will be described in detail with reference to the drawings. 1 is a perspective view of a low-temperature showcase 1 to which the present invention is applied, and FIG. 2 is a longitudinal side view of the low-temperature showcase 1 of FIG.

  The low-temperature showcase 1 of the present embodiment is a vertical open showcase that is installed in a store such as a supermarket, for example, and has a substantially U-shaped heat insulating wall 2 that opens to the front, and the heat insulating wall 2 at the installation site. It is comprised from the heat insulating side plates 5 and 5 attached to the side surface.

  An inner wall 4 is attached to the inside of the heat insulating wall 2 of the showcase 1 with a predetermined interval, and a partition wall 40 is attached between the inner wall 4 and the heat insulating wall 2 with an interval therebetween. An inner layer duct 41 is formed between 4 and the partition wall 40, and an outer layer duct 42 is formed between the partition wall 40 and the heat insulating wall 2. In front of the lower end of the back inner wall 10 constituting the inner wall 4, a bottom plate 9 is attached with a gap for a duct between the bottom wall 2 </ b> A of the heat insulating wall 2, and the inside of the inner wall 4 and the bottom plate 9 is disposed inside. A storage room 11 is provided.

  In addition, in the storage chamber 11, the height and the mounting angle can be changed, and a pair of brackets 31 attached to a column (not shown) on the back of the storage chamber 11 and a shelf plate 32 that constitutes a shelf device together with these brackets 31. It is constructed over several stages. A price rail 34 formed of hard synthetic resin is attached to the front edge of the shelf board 32, and the price rail 34 also serves as a decorative body for the shelf board 32. Further, a predetermined interval is formed between the front wall of the shelf board 32 and the price rail 34, and a guard 35 for preventing the products on the shelf board 32 from falling is provided at the interval. It is attached. In addition, an illuminating device (for example, a fluorescent lamp) 36 for illuminating commodities displayed on the lower shelf 32 is disposed in front of the lower surface of each shelf 32.

  An inner layer outlet 16 and an outer layer outlet 17 to which honeycomb materials 13 and 14 are respectively attached are arranged in parallel at the upper edge of the front opening (opening) 12 of the heat insulating wall 2. The outlet 17 communicates with the inner layer duct 41 and the outer layer duct 42, respectively. The inner layer outlet 16 and the outer layer outlet 17 are partitioned by a partition member 45 at the front end of the partition wall 40. On the other hand, an inner layer suction port 18 and an outer layer suction port 19 are arranged in parallel at the lower edge of the opening 12. An illuminating device (for example, a fluorescent lamp) 39 for illuminating the interior of the storage chamber 11 from above is provided on the top inner wall 8 of the inner layer outlet 16 on the storage chamber 11 side.

  In addition, a panel 33 is attached to the front end of the ceiling wall 2B of the heat insulating wall 2, and illumination for attaching an illumination device (for example, a fluorescent lamp) 37 located behind the panel 33 inside the panel 33. A reflector 50 is attached.

  In addition, an air outlet outer wall 52 that extends downward and is positioned on the front side of the outer layer air outlet 17 and closes the front end of the outer layer duct 42 is attached to the front end of the top wall 2B of the heat insulating wall 2. Note that the blower outlet outer wall 52 is formed with an engaging portion (not shown) whose lower end is folded back to the rear side, and the front end of the honeycomb material 14 attached to the outer layer blower outlet 17 is supported by the engaging portion. The And on the upper surface of this blower outlet outer wall 52, the roll-up type night cover 51 is accommodated in the front end of the top wall 2B of the heat insulation wall 2.

  The night cover 51 is wound around a torsion bar attached to a holder (not shown) and is urged in a direction in which the night cover 51 is always taken up. The night cover 51 can be drawn downward from the front end of the lower surface of the holder. When it is pulled out, it also has a stopper function that stops at a position halfway between full open and full close. This stopper function is released by a predetermined operation of pulling downward and is wound up. As a result, the night cover 51 can be drawn / wound freely on the holder.

  Further, the lateral width of the night cover 51 is substantially equal to the width dimension of the opening 12 in the embodiment. An edge member made of hard resin stretched to the left and right is attached to the front end (lower end) of the night cover 51, and a handle is formed at the center of the edge member. The fixing member formed on the edge member or the handle can be detachably attached to the locking member on the upper end of the front wall at the lower part of the heat insulating wall 2.

  On the other hand, a plurality of internal fans 27 and 28 (shown only in FIG. 4) corresponding to the inner layer duct 41 and the outer layer duct 42 are installed on the bottom wall 2A of the heat insulating wall 2 at the lower rear portion of the bottom plate 9. A cooler 46 (only FIG. 3 is shown) of the cooling device is vertically installed in the inner layer duct 41 behind the back inner wall 10. The DC compressor 26 (only FIG. 3 is illustrated), the condenser 47, the condensing fan 43 (only FIG. 3 is illustrated), etc., which constitute the refrigeration cycle together with the cooler 46, are provided separately from the showcase 1, for example, in stores. It is provided in the machine room inside.

  Here, the refrigerant circuit 25 constituting the refrigeration cycle in the present embodiment will be described with reference to the refrigerant circuit diagram of FIG. A condenser 47 is connected to the piping 48 on the discharge side of the compressor 26. An expansion valve 29 as a pressure reducing device is connected to the outlet side of the capacitor 47. The expansion valve 29 is connected to a cooler 46, and the outlet side of the cooler 46 is connected to the compressor 26 to constitute an annular refrigeration cycle. The compressor 26, the internal fans 27 and 28, the condensing fan 43, and the expansion valve 29 are connected to the control device 20 described later, and the cooling operation is controlled as will be described in detail later.

  Next, the control device 20 will be described in detail with reference to FIG. FIG. 4 shows a block diagram of the control device 20 of the showcase 1. The control device 20 is constituted by a general-purpose microcomputer and includes a timer 21 as a time limit means. And the input of this control apparatus 20 performs lighting / extinguishing of the temperature sensor 22 which detects the temperature in the storage chamber 11, the power switch 23, and the illuminating devices 36, 37 and 39 which illuminate the interior of the storage chamber 11. For this purpose, an illumination switch 24 is connected to a current sensor (current detection means) 56 that detects an energization current to the DC compressor 26. In addition, the temperature sensor 22 is attached to the ceiling part in the storage chamber 11, for example.

  On the other hand, the output of the control device 20 includes a compressor motor 26M that drives the DC compressor 26, fan motors 27M and 28M that drive the internal fans 27 and 28, and a fan motor 43M that drives the condensing fan 43, respectively. A solenoid valve 29 and lighting devices 36, 37, and 39 are connected. Here, the compressor motor 26M is connected via the inverter device 53, whereby the operating frequency of the compressor motor 26M can be arbitrarily changed. The fan motors 27M and 28M of the internal fans 27 and 28 are connected to each other via a drive circuit 54 such as a chopper circuit, so that the rotational speeds of the fan motors 27M and 28M can be arbitrarily changed. ing. Similarly, the fan motor 43M of the condensing fan 43 is connected via a drive circuit 55 such as a chopper circuit, whereby the rotational speed of the fan motor 43M can be arbitrarily changed.

  The operation of the showcase 1 according to the embodiment of the present invention will be described with the above configuration. First, when the power switch 23 is turned on, the control device 20 starts a cooling operation and activates the compressor 26 and the internal fans 27 and 28. When the compressor 26 is started, the cooler 46 provided vertically in the inner layer duct 41 exhibits a cooling action. The cold air that has exchanged heat with the cooler 46 is raised in the inner layer duct 41 by the operation of the internal fan 27 and blown out from the inner layer outlet 16 toward the inner layer inlet 18. The cold air sucked from the inner layer suction port 18 is accelerated again by the internal fan 27. Thereby, a cold air curtain is formed in the opening 12.

  On the other hand, when the internal fan 28 corresponding to the outer layer duct 42 is operated, the protective airflow in the outer layer duct 42 is raised in the outer layer duct 42 and blown out from the outer layer air outlet 17 toward the outer layer air inlet 19. Then, the air sucked from the outer layer suction port 19 is accelerated again by the internal fan 28. As a result, a protective air curtain is formed outside the cold air curtain in the opening 12, and a front and rear double air curtain is formed in the opening 12. Then, a part of the inner cool air curtain is circulated in the storage chamber 11 to cool the storage chamber 11.

  The control device 20 continuously operates the internal fans 27 and 28 and continuously operates the condensing fan 43 at the maximum rotational speed. The rotation speed of the compressor 26 is controlled by the inverter device 53 based on the output of the temperature sensor 22. That is, when the temperature in the storage chamber 11 detected by the temperature sensor 22 is equal to or higher than a predetermined upper limit temperature (for example, + 6 ° C.) set above a predetermined cooling set temperature (for example, + 5 ° C.), the compressor The number of revolutions of 26 is operated as the maximum number of revolutions. When the detected temperature is lower than the upper limit temperature and higher than a predetermined lower limit temperature (for example, + 4 ° C.) set below the set temperature, the rotational speed of the compressor 26 is increased as the temperature increases. As the temperature decreases, the rotational speed of the compressor 26 is decreased. That is, the rotational speed of these compressors 26 is adjusted according to the change in temperature detected by the temperature sensor 22. When the detected temperature is equal to or lower than the lower limit temperature, the operation of the compressor 26 is stopped. In this case, when the temperature in the storage chamber 11 detected by the temperature sensor 22 rises above the predetermined upper limit temperature, the compressor 26 is started and operated at the maximum rotational speed.

  In the above-described embodiment, the control is performed in the range of the differential 2 deg of the cooling set temperature, but is not limited to this.

  As a result, the inside of the storage chamber 11 is cooled to a refrigeration temperature of average + 5 ° C. In the present embodiment, the temperature control in the storage chamber 11 is performed only by the operation control of the compressor 26, but is not limited to this, and in addition to this, the opening degree control by the electromagnetic valve 29 is performed. By doing so, temperature control may be performed.

  Next, the cooling operation when the opening 12 is closed by the night cover 51 as described above will be described with reference to the control flowchart of FIG. First, in step S1, the control device 20 measures an energization current value of the DC compressor 26 and stores the energization current value. Thereafter, in step S2, the control device 20 determines whether or not the illumination switch 24 is turned off. For example, when the store is open, the lighting switch 24 is turned on and the night cover 51 is wound around the holder. Therefore, in the open state where the opening 12 is opened, the control device 20 performs the rotational speed control of the compressor 26 as described above based on the temperature in the storage chamber 11 detected by the temperature sensor 22. The interior of the storage chamber 11 is maintained at a predetermined cooling set temperature. In this case, the condensing fan 43 performs constant speed operation at a predetermined maximum rotational speed. Thereafter, the process returns to step S1.

  When closing the store, the night cover 51 is pulled out from the holder and lowered, and a handle or the like is locked to a locking member formed at the upper end of the front wall of the heat insulating wall 2 to cover the opening 12 outside the cold air curtain. . Thereby, during the closing of the store, the opening 12 is closed with the night cover 51, whereby the cool air in the storage chamber 11 can be retained in the storage chamber 11, and the cooling efficiency is improved.

  At this time, when the store is closed, the lighting switch 24 is turned off, and the lighting devices 36, 37, and 39 are turned off. Therefore, in step S2, since the illumination switch 24 is turned off, it is considered that the opening 12 is closed by the night cover 51, and the process proceeds to step S4, and the energy saving operation of the condensing fan 43 is executed.

  In step S4, since the lighting switch 24 is OFF, the control device 20 replaces the condensing fan 43 that has been operating at a constant maximum speed up to that time with the energization current value of the compressor 26. Rotational speed control based on That is, the control device 20 controls the rotational speed of the condensing fan 43 as shown in FIG. 6 based on the energization current value of the compressor 26 detected by the current sensor 56 in step S1.

  In the present embodiment, when the energization current value of the compressor 26 is a predetermined high current value, for example, 5.0 A or more, the compressor 26 is operated at a predetermined maximum rotational speed, and a predetermined low current value, for example, 3.5 A. In the following cases, the vehicle is operated at a predetermined minimum rotational speed. When the current value is between the high current value and the low current value, as shown in FIG. 6, the rotational speed determined based on the current value (the rotational speed that increases at a predetermined rate as the current value increases ( Operate between the maximum and minimum speed))).

  Thereby, in the energy saving operation, the amount of waste heat that varies depending on the operation state of the compressor 26 is estimated from the energization current value of the compressor 26 that varies depending on the operation state, and thereby the rotational speed of the condensing fan 43 is controlled. Therefore, compared with the conventional case where the condensing fan is operated at a constant speed, the amount of power consumption can be reduced, and energy saving operation can be realized.

  In this case, since the disturbance is reduced by the illumination device 43 being turned off and the opening 12 being closed by the night cover 51, the heat load in the storage chamber 11 is reduced and the temperature rise is also reduced. Even if the rotational speed of the condensing fan 43 is reduced in accordance with the value of the energization current to the compressor 26, it is possible to maintain the ability to cool the interior of the storage chamber 11 without hindrance.

  By performing the energy saving operation at night, such as when the opening 12 is closed by the night cover 51, noise generation can be suppressed and noise reduction can be achieved.

  In addition to this, the energy saving operation of the condensing fan 43 may be performed. Hereinafter, as another example, other embodiments will be described with reference to the control flowchart of FIG. 7 and the control flowchart of FIG.

  In the control flowchart of FIG. 7, similarly to the above embodiment, in step S <b> 1, the energization current value of the DC compressor 26 is measured and the energization current value is stored. Thereafter, in step S <b> 5, the control device 20 determines the temperature stability in the storage chamber 11.

  In the stability determination of the temperature in the storage chamber 11, the determination is made based on whether or not a predetermined time has elapsed for a stable time during which the temperature change detected by the temperature sensor 22 is within a predetermined value. In this case, the time required for determination is, for example, 10 minutes. Therefore, in step S5, it is determined whether or not 10 minutes (predetermined time) has elapsed since the temperature change detected by the temperature sensor 22 is within a predetermined value of 1 to 3 degrees, for example, within 2 degrees.

  When the predetermined time has not elapsed, it is determined that the amount of waste heat due to the operation of the compressor 26 is large, and the routine proceeds to step S6 where the condensing fan 43 is continuously operated at the maximum rotation speed. Execute control. Then, it returns to step S1.

  In step S5, when the predetermined time has elapsed, the control device 20 determines that the amount of waste heat due to the operation of the compressor 26 is reduced, for example, the opening 12 is closed by the night cover 51, and the storage room 11, it is considered that the temperature change is stable, and the process proceeds to step S <b> 4, and the energy saving operation of the condensing fan 43 is executed in the same manner as in the above embodiment.

  Thereby, by judging the stability of the temperature in the storage chamber 11, the amount of waste heat due to the operation of the compressor 26 is reduced, for example, the opening 12 is closed by the night cover 51, or the opening Even if 12 is opened, it is understood that the temperature change in the storage chamber 11 is stabilized by the external environment, and the amount of waste heat due to the operation of the compressor 26 is reduced. As shown in FIG. 6, the rotational speed of the condensing fan 43 can be controlled on the basis of the energization current value of the compressor 26 detected by the current sensor 56 in step S1.

  Therefore, in such energy-saving operation, the amount of waste heat that varies depending on the operating condition of the compressor 26 is estimated from the energization current value of the compressor 26 that varies depending on the operating condition, and thereby the rotational speed of the condensing fan 43 is controlled. Therefore, compared with the conventional case where the condensing fan is operated at a constant speed, the amount of power consumption can be reduced, and energy saving operation can be realized.

  In the control flowchart of FIG. 8, similarly to the above embodiment, in step S <b> 1, the energization current value of the DC compressor 26 is measured and the energization current value is stored. Thereafter, in step S7, the control device 20 determines whether or not the operating frequency of the compressor 26 is a predetermined low operating frequency.

  In such an embodiment, it is determined whether or not the operating frequency of the compressor 26 is lower than a predetermined operating frequency, for example, 20 Hz. When the operating frequency of the compressor 26 is equal to or higher than the predetermined low operating frequency, the control device 20 determines that the amount of waste heat due to the operation of the compressor 26 is large, moves to step S6, and performs the above-described operation. As in the example, normal control is performed in which the condensing fan 43 is continuously operated at the maximum rotational speed. Then, it returns to step S1.

  When the operation frequency of the compressor 26 is lower than the predetermined low operation frequency in step S7, the control device 20 causes the opening 12 to be opened by the night cover 51 in a situation where the amount of waste heat due to the operation of the compressor 26 is reduced. It is considered that the temperature change in the storage chamber 11 is stabilized, and the process proceeds to step S4, and the energy saving operation of the condensing fan 43 is executed as in the above embodiment.

  Thereby, by determining the operating frequency of the compressor 26, the amount of waste heat due to the operation of the compressor 26 is reduced, for example, the opening 12 is closed by the night cover 51, or the opening 12 is opened. However, it is understood that the temperature change in the storage chamber 11 is stabilized by the external environment, and the amount of waste heat due to the operation of the compressor 26 is reduced, whereby the condensing fan 43 is set in step S1. 6, the rotational speed of the condensing fan 43 can be controlled as shown in FIG. 6 based on the energization current value of the compressor 26 detected by the current sensor 56.

  Therefore, in such energy-saving operation, the amount of waste heat that varies depending on the operating condition of the compressor 26 is estimated from the energization current value of the compressor 26 that varies depending on the operating condition, and thereby the rotational speed of the condensing fan 43 is controlled. Therefore, compared with the conventional case where the condensing fan is operated at a constant speed, the amount of power consumption can be reduced, and energy saving operation can be realized.

It is a perspective view of a showcase. It is a vertical side view of the showcase of FIG. It is a refrigerant circuit diagram. It is an electrical block diagram of a control apparatus. It is a flowchart of control. It is a figure which shows the rotation speed of the condensing fan with respect to the electricity supply electric current value of a compressor. It is a flowchart of control of other examples. It is a flowchart of control of other examples.

DESCRIPTION OF SYMBOLS 1 Open showcase 2 Heat insulation wall 9 Bottom plate 10 Back inner wall 11 Storage room 12 Front opening (opening part)
16 Inner layer outlet 17 Outer layer outlet 20 Control device 21 Timer 22 Temperature sensor 23 Power switch 24 Illumination switch 25 Refrigerant circuit 26 Compressor 36, 37, 39 Illumination device 40 Partition wall 41 Inner layer duct 42 Outer layer duct 43 Condensing fan 46 Cooling 47 Capacitor 48 Refrigerant piping 51 Night cover 53 Inverter device 54 Drive circuit 55 Drive circuit 56 Current sensor (current detection means)

Claims (2)

A cold air curtain comprising a refrigerant circuit including a compressor, a condenser and a cooler, and a condensing fan for air-cooling the compressor and the condenser, and discharging cool air heat exchanged with the cooler to an opening of a storage chamber In a low temperature showcase that cools the storage chamber while forming
A night cover that covers the opening of the storage chamber, current detection means for detecting an energization current of the compressor, and a control device that controls the operation of the compressor and the condensing fan,
When it is determined that the opening of the storage chamber is covered by the night cover , the control device is based on the energizing current of the compressor detected by the current detecting means, and the energizing current is low. A low-temperature showcase, wherein the rotational speed of the condensing fan is reduced, and when the energization current of the compressor is high, the rotational speed of the condensing fan is increased. An illumination device for illuminating the storage compartment,
The control device allows the night cover by turning off the lighting device, stabilizing the temperature in the storage chamber, or lowering the operating frequency of the compressor below a predetermined low operating frequency. While judging that the opening of the storage room is covered,
Usually, the condensing fan is operated at the maximum rotation speed, and when it is determined that the opening of the storage chamber is covered by the night cover, between the maximum rotation speed and the minimum rotation speed, The low-temperature showcase according to claim 1, wherein the rotational speed control of the condensing fan is executed in accordance with an energization current of the compressor.

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