JP3021976B2 - Low temperature showcase controller - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control apparatus for a low-temperature showcase for displaying and preserving foods while cooling them.

[0002]

2. Description of the Related Art Conventionally, a low-temperature showcase of this type is installed in a store such as a supermarket, and displays products while cooling the inside of a refrigerator formed by heat insulating walls to a low temperature. Further, in such a showcase, since a thermal load is greatly penetrated from the front opening and it is extremely unstable to directly detect the inside temperature and perform temperature control, for example, Japanese Unexamined Patent Publication No. 54-99256 (F25D1)
In 1/00), the temperature of the discharged cool air discharged into the refrigerator is detected by inserting a temperature-sensitive tube into the cool air passage which is separated from the refrigerator in which the products are actually stored and is less affected by external temperature. And
A configuration for controlling the compressor while comparing with the set temperature of the discharged cool air is shown.

In such a low-temperature showcase, when the store is closed, such as at night, when the business is closed, the interior lighting of the low-temperature showcase is turned off simultaneously with the turning-off of the interior lighting. Therefore, after the store is closed, the temperature rise due to the heat generated by the internal lighting as a load disappears, but the temperature of the discharged cold air detected by the temperature-sensitive cylinder is the same as when the store is opened during the daytime when the internal lighting is turned on during business hours. Therefore, when the store is closed by an increase in temperature due to the lighting in the refrigerator, the temperature in the refrigerator decreases, and the product becomes too cold, and the operation rate of the cooling device becomes unnecessarily high, resulting in waste of power. In particular, in recent years, quality deterioration caused by cell membrane destruction due to freezing and thawing is prevented by storing food in a temperature range of 0 ° C. or lower and at which the food does not freeze, that is, an ice temperature range (about 0 ° C. to −3 ° C.) However, low-temperature showcases that realize long-term storage are increasing, and in such low-temperature showcases, if too cold occurs when the store is closed, the food is liable to freeze.

Therefore, according to the above publication, when the interior lighting is turned off when the store is closed at night or the like, the set temperature is changed at a predetermined rising width to change the interior temperature to the time when the interior lighting is turned on. It is configured so that it can be controlled to the same temperature. That is, the temperature control of the conventional low-temperature showcase will be described with reference to FIG. FIG. 4 shows a functional block diagram of a control device for a conventional low-temperature showcase disclosed in the above publication.
0, and the discharged cool air temperature TD is input to the measuring unit 101. The comparing unit 102 sets the upper limit temperature and the lower limit temperature with a predetermined differential width above and below the set temperature TDS based on the set temperature TDS from the setting unit 100, and the discharge cool air temperature TD from the measuring unit 101 reaches the upper limit temperature. Then, an output is generated at the output unit 103 and the compressor of the cooling device (not shown) is operated, or the electric valve for controlling the refrigerant flow is opened, and an output is generated at the output unit 103 when the discharge cool air temperature TD reaches the lower limit temperature. Then, the compressor is stopped or the electric valve is closed. As a result, the discharge cool air temperature TD is controlled to the set temperature TDS as an average.

On the other hand, the ON / OFF state of the interior lighting based on a switching operation of an interior lighting switch (not shown) is determined by a determination unit 104.
It is determined here whether the interior lighting is on or off. At the time of lighting, there is no need to change the set temperature TDS. Here, when the interior lighting is turned off by closing the store, a signal is sent from the determination unit 104 to the set temperature changing unit 105 (shown by a broken line in the figure), and the set temperature change unit 105 sends the set temperature to the setting unit 100 based on this signal. Command to change TDS in 3-6 ° C. increments. The setting unit 100 raises the set temperature to, for example, the above-mentioned TDS + 3 ° C. according to the command, so that the comparing unit 102 thereafter sets the raised set temperature T
The upper limit temperature and the lower limit temperature are newly set at a predetermined differential width above and below DS + 3 ° C.
When the discharge cool air temperature TD from 1 reaches the upper limit temperature, an output is generated at the output unit 103 to operate a compressor of a cooling device (not shown) or to open an electric valve, and the discharge cool air temperature T
When D reaches the lower limit temperature, an output is generated at the output unit 103 to stop the compressor or close the motor-operated valve. As a result, the discharge cool air temperature TD is increased by the decrease in the heat load in the refrigerator due to the turning off of the lighting in the refrigerator, thereby preventing the occurrence of overcooling when the lamp is turned off.

[0006]

By the way, in recent years, the illuminance of interior lighting (fluorescent lamp) can be changed by an electronic ballast composed of an inverter capable of changing a power supply frequency applied to the fluorescent lamp. It is becoming. Then, for example, when the weather is sunny during the daytime, the interior lighting is set to a bright state according to the brightness, and when it is cloudy, the interior lighting is darkened according to the outdoor darkening, so that the difference between the outdoor brightness and the outdoor brightness is reduced. It is possible to show the products in the warehouse to customers with more natural brightness at a minimum.

However, the amount of heat emitted from the interior lighting changes into the interior due to the change in the illuminance. Therefore, when the illuminance of the interior illumination is reduced, the amount of heat is reduced by the reduced amount of heat as in the case of turning off the light. There was a problem that the temperature in the refrigerator was unnecessarily lowered. The present invention has been made in order to solve the conventional technical problem, and provides a control device for a low-temperature showcase that can accurately control the temperature in the refrigerator even when the illuminance of the illumination in the refrigerator is changed. The purpose is to do so.

[0008]

The control device for a low-temperature showcase according to the present invention is applied to a low-temperature showcase that cools by discharging cold air, which has exchanged heat with a cooler included in a cooling device, into a refrigerator. , An illuminance changing means for changing the illuminance of the interior lighting, a discharge cold air temperature detecting means for detecting the temperature of the discharge cold air discharged into the refrigerator, and a temperature detected by the discharge cold air temperature detecting means. Control means for controlling the cooling device based on the set temperature of the discharged cold air, and set temperature changing means for changing the set temperature of the discharged cold air, wherein the set temperature changing means changes the illuminance when the interior lighting is turned on. When the illuminance of the interior lighting is reduced by the means, the set temperature is changed at a predetermined rising width.

[0009]

The control means controls the cooling device based on the temperature of the discharged cool air detected by the discharged cool air temperature detecting means and the set temperature of the discharged cool air. Then, when the illuminance of the interior lighting is reduced by the illuminance changing means when the interior lighting is turned on, the set temperature changing means changes the set temperature of the discharge cool air by a predetermined increase width. Thereby, the control means comes to control the cooling device based on the raised set temperature and the temperature of the discharged cold air, the temperature of the discharged cold air is raised by an amount corresponding to a decrease in the amount of heat from the interior lighting, and the temperature of the interior is reduced. Control is performed in the same manner as before the illuminance change.

[0010]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. FIG. 1 is a block diagram of the control device C of the low-temperature showcase 20, and FIG. 2 is a schematic longitudinal sectional view of the low-temperature showcase 20. In FIG. 2, a low-temperature showcase 20 is a so-called open showcase which is installed in a convenience store or a supermarket, and a cooler 2 constituting a cooling device is provided below a heat-insulating wall 1 having an open front surface. A cool air passage 5 is formed from a suction port 3 provided at a lower portion of the heat sink 2 to a cooler 2, an inner back surface of the heat insulating wall 1, and a discharge port 4 provided at an upper portion of the heat insulating wall 1. The cold air cooled by the heat exchange is circulated as shown by the arrows to supply the cool air to the inside of the refrigerator 7 and form an air curtain at the opening of the heat insulating wall 1 from the discharge port 4 to the suction port 3. The products displayed on the shelf 8 and the wire rack 9 for displaying the products in the refrigerator 7 are cooled to keep the products at a low temperature.
In order to enhance the display effect, the interior of the refrigerator 7 is provided with fluorescent lamps near the shelves 8 and the discharge ports 4.
Is provided.

In the control device C shown in FIG. 1, reference numeral 11 denotes a general-purpose microcomputer as control means, which is shown in FIG. 2 for switching the illuminance of the interior lighting 10 between light and dark. There is no illuminance setting switch 12, an interior lighting switch 14 provided on the lower surface of the reflector 13 of the low-temperature showcase 20 for switching on / off of the interior lighting 10, and an actual setting for setting the temperature of the interior 7. The discharge cold air temperature setting device 15 as the discharge cold air temperature setting means for setting the temperature of the discharge cold air flowing in the cold air passage 5 and the discharge as the discharge cold air temperature detecting means for detecting the temperature of the discharge cold air flowing in the cold air passage 5 Each output of the cool air temperature sensor 16 is input. The discharge cool air temperature setting device 15 is provided on the reflector 13, and its knob faces the lower surface of the reflector 13.

On the other hand, the output of the microcomputer 11 includes the compressor 18 and the blower 6 constituting the cooling device.
Is connected, and an electronic ballast 19 as an illuminance changing means including an inverter is connected.
The interior lighting 10 is connected to 9. The microcomputer 11 controls to turn on / off the interior lighting 10 based on the operation of the interior lighting switch 14 by the user. The microcomputer 11 changes the power frequency of the interior lighting 10 generated by the electronic ballast 19 based on the operation of the illuminance setting switch 12 by the user, and changes the interior lighting 10 to a high frequency, that is, a bright state. Switching control is performed to a low frequency, that is, a dark state.

Next, the temperature control operation of the low-temperature showcase 20 by the microcomputer 11 will be described with reference to the functional block diagram of FIG. FIG. 3 shows a functional block relating to the temperature control of the microcomputer 11. The set temperature TDS of the discharge cool air set by the discharge cool air temperature setting unit 15 is input to the setting unit 21 as a function of the microcomputer 11. The discharge cool air temperature TD detected by the discharge cool air temperature sensor 16 is input to the measuring unit 22. The comparing unit 23 as a function of the microcomputer 11 sets an upper limit temperature and a lower limit temperature with a predetermined differential width above and below the set temperature TDS based on the set temperature TDS from the setting unit 21, and discharges the cool air from the measuring unit 22. When the TD reaches the upper limit temperature, an output is generated at the output unit 24 to operate the compressor 18 (the blower 6 is continuously operated), and when the discharge cool air temperature TD reaches the lower limit temperature, an output is generated at the output unit 24. The compressor 18 is stopped. As a result, the discharge cooling air temperature TD is averaged to the set temperature TD.
Control to S. In the case where a plurality of low-temperature showcases 20 are installed, a condensing unit including the compressor 18 is separately provided, and the refrigerant flow to the cooler 2 of each low-temperature showcase 20 is controlled by an electric valve, the microcomputer 11 The open / close control of the electric valve is performed by comparing the temperature TD of the discharged cool air with the set temperature TDS.

On the other hand, the light / dark setting of the interior lighting 10 based on the switching operation of the illuminance setting switch 12 is input to a first determination unit 26 as a function of the microcomputer 11, where the interior lighting 11 is turned to a bright state. It is determined whether the setting has been made or the setting has been made in a dark state. The lighting / off state of the interior lighting 10 based on the switching operation of the interior lighting switch 14 is input to the second determination unit 27, where it is determined whether the interior lighting 10 is on or off. When the interior lighting 10 is turned on and the illuminance is set to a bright state, the setting temperature TDS does not need to be changed and does not act on the setting unit 21 (shown by a solid line in FIG. 3). .

Here, when the interior lighting 10 is turned off due to the closing of the store, a signal is sent from the second determination unit 27 to the set temperature changing unit 28 as a set temperature changing unit means (indicated by a broken line in FIG. 3), and the setting is performed. The temperature changing unit 28 receives the signal from the setting unit 2
1 is instructed to change the set temperature TDS in a range of 3 to 6 ° C. The setting unit 21 raises the set temperature to, for example, the above-mentioned TDS + 3 ° C. in accordance with the command, so that the comparing unit 23 thereafter sets the raised set temperature TDS + 3.
The upper limit temperature and the lower limit temperature are newly set above and below a predetermined differential width as described above, and when the discharge cool air temperature TD from the measuring unit 22 reaches the upper limit temperature, an output is generated at the output unit 24 to generate the compressor 18. , And discharge cold air temperature TD
When the temperature reaches the lower limit temperature, an output is generated at the output unit 24 and the compressor 18 is stopped. As a result, the discharge cool air temperature TD is increased by the amount of the decrease in the heat load in the interior 7 due to the turning off of the interior lighting 10, thereby preventing the occurrence of overcooling when the interior is turned off.

Next, when the interior lighting 10 is turned on and the user sets the interior lighting 10 to a dark state by the illuminance setting switch 12 due to, for example, darkening of the outside, the first determination unit 26 A signal is sent to the set temperature change unit 28 (shown by a dashed line in FIG. 3), and the set temperature change unit 2
8 instructs the setting unit 21 to change the set temperature TDS by 0.5 ° C. by this signal. Setting unit 2
1 sets the set temperature to TDS + 0.5 by the command.
° C, and thereafter the comparison unit 23 sets a new upper limit temperature and a lower limit temperature above and below the raised set temperature TDS + 0.5 ° C with predetermined differential widths as described above. When the temperature TD reaches the upper limit temperature, an output is generated at the output unit 24 to operate the compressor 18, and when the discharge cool air temperature TD reaches the lower limit temperature, an output is generated at the output unit 24 and the compressor 18 is stopped. I will be. As a result, the discharge cool air temperature TD is increased by an amount corresponding to a decrease in the heat load of the interior 7 due to a decrease in the illuminance of the interior lighting 10 (smaller than when the lamp is turned off). In addition, the operation rate of the compressor 18 is reduced, and the power consumption is reduced.

In the above embodiment, the set temperature is changed both when the interior lighting 10 is turned off and when the illuminance is reduced. However, the setting is performed only when the illuminance of the interior lighting 10 is reduced. Is also effective. Further, the values of the respective temperatures shown in the embodiment are not limited thereto, and needless to say, they can be appropriately changed based on the capacity and capacity of the low-temperature showcase 20.

[0018]

As described above, according to the present invention, when the illuminance is reduced while the low-temperature showcase interior lighting is turned on, the set temperature of the discharged cool air is increased by a predetermined increase width. Because of the change, it is possible to eliminate the overcooling of the internal temperature due to the decrease in the amount of heat due to the decrease in illuminance, and to enable appropriate temperature management of low-temperature showcases and also reduce power consumption. is there.

[Brief description of the drawings]

FIG. 1 is a block diagram of a control device for a low-temperature showcase of the present invention.

FIG. 2 is a schematic longitudinal sectional view of a low-temperature showcase.

FIG. 3 is a functional block diagram of a microcomputer.

FIG. 4 is a functional block diagram of a conventional low-temperature showcase control device.

[Explanation of symbols]

 2 Cooler 5 Cold air passage 7 Inside the warehouse 10 Inside the warehouse 11 Microcomputer 12 Illumination setting switch 15 Discharge cool air temperature setting unit 16 Discharge cool air temperature sensor 18 Compressor 19 Electronic ballast 20 Low temperature showcase C controller

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-5-180551 (JP, A) JP-A-5-60458 (JP, A) JP-A 1-159575 (JP, A) (58) Field (Int.Cl. ⁷ , DB name) F25D 11/00-13/00 F25D 27/00 A47F 3/04

Claims (1)

(57) [Claims] 1. A low-temperature showcase that cools by discharging cold air that has exchanged heat with a cooler included in a cooling device into a refrigerator and cooling the interior of the refrigerator and changing the illuminance of the illumination in the refrigerator. Illuminance changing means for detecting the temperature of the discharged cool air discharged into the refrigerator, and detecting the temperature of the discharged cool air, and performing the cooling based on the temperature detected by the discharged cool air temperature detecting means and the set temperature of the discharged cool air. Control means for controlling the device, and a set temperature changing means for changing the set temperature of the discharge cold air, the set temperature changing means when the illuminance of the interior lighting by the illuminance change means when the interior lighting is turned on. The control device for a low-temperature showcase, wherein the set temperature is changed at a predetermined increase width when the temperature is reduced.