JPH0228786B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application This invention relates to a method for controlling the temperature of a low-temperature show case equipped with a fluorescent lamp for lighting the inside of a refrigerator.

(b) Prior Art In general, a low-temperature display case in a supermarket or the like is a box for displaying products at a low temperature by cooling the inside of the insulated box using a refrigeration cycle. That is, as shown in FIG. 1, a cooler 2 consisting of an evaporator constituting a refrigeration cycle is provided at the bottom of an insulating box 1 with one side open.
A cold air flow path 5 is formed from the suction port 3 provided at the bottom of the fan 6 to the cooler 2, the inner back surface of the heat insulating box 1, and the discharge port 4 provided at the top of the heat insulating box 1.
As a result, the cold air cooled in the cooler 2 is circulated as shown by the arrow, and the cold air is supplied to the inside of the refrigerator 7, and an air curtain is placed in the opening of the heat insulating box 1 from the discharge port 4 to the suction port 3. It cools the products displayed on the product display shelves 8 and wire racks 9 in the warehouse 7, thereby maintaining the products at a low temperature.
In addition, in the chamber 7, in order to enhance the display effect,
A fluorescent lamp 10 is provided near each shelf 8 and discharge port 4.

The required refrigerating capacity is determined for the low-temperature case, and a refrigerating machine consisting of a compressor, condenser, etc. corresponding to the required refrigerating capacity is built in. Generally, a thermostat controls the operating rate of the refrigerating machine, and Temperature control is performed. In other words, the operating rate is
It is the percentage of operating time of the refrigerator, and if the thermostat temperature setting is set lower, the operating rate will increase.
The products in compartment 7 cool well, and on the other hand, if you set the thermostat temperature high, the operating rate will decrease.
The temperature of the product becomes high. As shown in Fig. 2, the thermostat is connected to the thermostat main body 1.
1 is provided with a temperature setting knob 12 and one or more sets of output terminals 13, and a temperature sensing tube 14 is connected to the thermostat main body 11 via a capillary tube 15.
By comparing Tm with the temperature Ts set by the temperature setting knob 12, an "open" or "close" signal is output to the output terminal 13, and that signal causes the compressor to compress the refrigerator via the temperature control device in the refrigerator 7. The electric motor of the machine is energized and de-energized, and the refrigerator is driven and de-energized. Therefore, since the thermostat main body 11 has a unique on/off temperature difference Td, the output terminal 13
An “open” signal is output when Ts>Tm, and conversely, a “close” signal is output when
When Ts＋Td＜Tm.

Therefore, conventionally, the temperature control device for controlling the temperature of the inside of the refrigerator 7, as shown in FIG.
The thermostat main body 11 is installed in the heat insulating box body 1.
A temperature setting knob 12 is provided on the reflector 16 at the upper front of the refrigerator and protrudes to the outside, allowing the set temperature Ts to be set to an arbitrary value.As shown in FIG. ing. That is, the electric motor 17 of the compressor of the refrigerator is connected to the three-phase power supply 20 via the overcurrent relay 19 and the contact 18' of the electromagnetic contactor 18, and the defrost timer contact 21,
A thermostat contact 11' opened and closed by the thermostat main body 11, an internal thermostat 22,
Overcurrent relay contact 19', high/low pressure switch 2
3 and the electromagnetic contactor 18 are connected to two phases of a power supply 20 via a temperature control operating switch 23'.

Then, the temperature sensing cylinder 14 detects the cold air temperature in the cold air passage 5, and based on the detection signal, an "open" or "close" signal is output to the output terminal 13 of the thermostat main body 11, and the "open" or "close" signal is output to the output terminal 13 of the thermostat main body 11. ”, “close” signal causes
The thermostat contact 11' is closed and opened, the electromagnetic contactor 18 is energized and de-energized, and the contact 1 of the electromagnetic contactor 18 is turned on and off.
8' is opened and closed, the electric motor 17 is energized and de-energized, the refrigerator is driven and de-energized, and the temperature inside the refrigerator 7 is controlled.

(c) Problems to be solved by the invention By the way, in the conventional example described above, when used in a store such as a supermarket, when the store is closed at night, etc., when the store is closed, the lights in the low-temperature show case are switched off at the same time as the store lights are turned off. That is, the fluorescent lamp 10 is turned off. Therefore, when the store is closed, the temperature of the products will not rise due to the heat generated by the fluorescent lamps 10 (refrigeration load), but the temperature of the frozen product detected by the thermosensor tube 14 will be lower than that during the daytime when the fluorescent lamps 10 are on during business hours. etc., the temperature rise caused by the fluorescent lamp 10 (△T
℃), when the store is closed, the discharged cold air, that is, the temperature inside the warehouse 7, will drop, causing the products to become too cold, which is not desirable from a product management perspective, and the operating rate of the refrigerator will be higher than necessary, resulting in wasted electricity. A problem will occur.

(d) Means for Solving the Problems In order to solve the above-mentioned problems, the present invention provides a low-temperature show case equipped with a large number of fluorescent lights for illuminating the inside of the refrigerator, when the fluorescent lights are turned on. In order to maintain the temperature inside the refrigerator at the same temperature as the temperature inside the refrigerator when the lights are turned off, the measured temperature detected by the temperature control device is controlled by a cooler installed in the cold air flow path that is separate from the inside of the refrigerator. Obtained from the temperature of the cold air that is heat exchanged and reaches the discharge port of the cold air flow path, and when the fluorescent lamp is turned off, the temperature corresponding to the refrigeration load corresponding to the heat generated when the fluorescent lamp is turned on. To provide a temperature control method for a low-temperature show case by adding the above to the set temperature.

(E) Effect Inside the cold air flow path where the measured temperature Tm is detected,
Because it is separated from the inside of the refrigerator, there is little effect on the temperature inside the refrigerator, and since the temperature of the low-temperature cold air that is exchanged with the cooler and reaches the discharge port is detected as the measured temperature, it is not affected by the outside air. It is possible to detect cold air temperature with little change, and when the fluorescent lamp is off, there is no refrigeration load due to the heat generated by the fluorescent lamp compared to when it is on, and a temperature equivalent to this refrigeration load is added. By controlling the temperature inside the refrigerator at the set temperature, the temperature inside the refrigerator is always maintained at the same temperature.

(F) Embodiments The present invention will be described below with reference to FIGS. 1 to 3 and the drawings from FIG. 4 onwards. still,
The same number as above indicates the same thing.

In the conventional temperature control device shown in FIG. 3 in the low-temperature show case of FIG. 1, as shown in FIG. It is connected in series to a commercial power source 28 via a switch 27, and a control circuit constituted by an electric heater 29 wound around the temperature sensing tube 14 is connected in series via the lighting circuit switch 27. Note that the switching contact is a thermostat contact 11'.

When the lighting circuit switch 27 is closed at the time of store opening, the lighting circuit 26 is energized, and
Since the electric heater 29 is energized, the electric heater 2
9, the temperature sensing cylinder 14 is heated, and the measured temperature Tm of the cold air in the temperature sensing cylinder 14 becomes higher than the cold air temperature by ΔT°C. That is, the temperature sensing cylinder 14 detects cold air which is apparently higher than ΔT°C. Therefore, the set temperature Ts of the temperature setting knob 12 is set by △T from the cold air temperature corresponding to the desired temperature inside the refrigerator 7 at the time of opening.
Keep the temperature higher. When the store is closed, the lighting circuit switch 27 is opened, the lighting circuit 26 is de-energized, and the electric heater 29 is de-energized.
The temperature sensing tube 14 is no longer heated by the electric heater 29, and the measured temperature Tm of the temperature sensing tube 14 becomes equal to the temperature of the cold air. In other words, the measured temperature Tm of the cold air in the thermosensor tube 14 has decreased by △T°C compared to when the tube was closed, and since the set temperature Ts of the temperature setting knob 12 is constant, the “closed” state of the thermostat body 11 has decreased. The signal output decreases, and the operating rate of the refrigerator decreases.

Therefore, in response to the difference △T°C between the appropriate temperature of the chamber 7 at the time of opening and the appropriate temperature of the chamber 7 at the time of closing,
By setting the apparent measured temperature difference △T°C of the thermosensor tube 14 caused by the electric heater 29, it is possible to appropriately manage the temperature of products in the low-temperature show case in response to store openings and closings, that is, in any case, the set temperature Ts is the standard. The temperature inside the refrigerator can be maintained at the same level, and power consumption can be reduced.

The temperature sensing tube 14 of the thermostat main body 11 is
Since it is arranged between the cooler 2 in the cold air flow path 5 separated from the inside 7 of the refrigerator and the discharge port 4, it is not only affected by the temperature inside the refrigerator 7, but also by the radiant heat of the fluorescent lamp 10 and the outside air. Detects constant cold air temperature that is not affected by
A measured temperature Tm is applied to the thermostat main body 11.

Next, FIG. 5 showing another embodiment will be explained.

Similar to the embodiment described above, in the conventional temperature control device shown in FIG. 3 in the low temperature case of FIG. 1, the thermostat includes a step thermostat having a high temperature contact 30 for high temperature setting and a low temperature contact 31 for low temperature setting. Use the tatsuto to connect the switching contact.
A series circuit of the high temperature auxiliary contact 33 which is the b contact of the high temperature contact 30 and the auxiliary relay 32, and the low temperature contact 31
The control circuit is configured by the coil 35 of the auxiliary relay 32, and the changeover switch is connected to the defrost timer contact 21 and the parallel circuit. The lighting circuit 26 and the coil 35 of the auxiliary relay 32 are connected to the commercial power source 28 via the lighting circuit switch 27, respectively.

Then, the set temperature Th (Th = Ts + △T) of the thermostat main body 11 at which the high temperature contact 30 opens and closes,
The set temperature Tl (Tl = Ts) of the thermostat main body 11, which opens and closes the low temperature contact 31, is set to the cold air temperature corresponding to the optimal temperature of the refrigerator interior 7 when the store is closed, and the cold air temperature corresponding to the optimal temperature of the refrigerator interior 7 when the store is opened. Set each temperature.

Therefore, when the lighting circuit switch 27 is closed when the store is opened, the coil 35 of the auxiliary relay 32 is energized, so the coil 35 is activated, the high temperature auxiliary contact 33 is opened, and the low temperature auxiliary contact 34 is closed. The influence of opening and closing of the high-temperature contact 30 is eliminated, and energization and de-energization of the electromagnetic contactor 18 is controlled by opening and closing of the low-temperature contact 31. That is, the temperature control 7 is performed based on the set temperature Tl, and the interior 7 of the refrigerator is maintained at the optimal temperature at the time of store opening.

Next, when the lighting circuit switch 27 is opened at the time of closing, the coil 35 of the auxiliary relay 32 is not energized, so the high temperature auxiliary contact 33 is closed, and
The low-temperature auxiliary contact 34 opens, and the opening and closing of the high-temperature contact 30 controls whether or not the electromagnetic contactor 18 is energized. That is, the temperature control of the inside of the refrigerator 7 is carried out based on the set temperature Th, which is the set temperature Ts of the temperature setting knob 12 and the apparent measured temperature difference ΔT°C added in advance, and the inside of the refrigerator 7 is controlled at the temperature when the store is closed. Maintained at optimal temperature (same temperature as when the store opened).

In the above embodiment, the high temperature contact 30 and the low temperature contact 31 were connected in parallel, but as shown in FIG. The auxiliary contact 36 is connected in parallel to the high temperature contact 30, and the high temperature contact 3 at the time of opening
Even if the influence of opening and closing of 0 is removed, the effects of the present invention can be obtained.

(G) Effects of the Invention According to the present invention described above, the following effects are achieved.

When the fluorescent lamp is off, compared to when the fluorescent lamp is on, temperature control is performed using a set temperature that is added to a temperature that is sufficient to cover the refrigeration load equivalent to the heat generated by the fluorescent lamp. The operating time of the refrigerator is shorter than when the fluorescent light is on, contributing to power savings, and the temperature inside the refrigerator is always maintained at the same level to prevent products from getting too cold.

The inside of the cold air flow path, which is the detection point for the measured temperature, is separated from the inside of the refrigerator, so there is almost no influence of the temperature inside the refrigerator or the radiant heat of the fluorescent lamp. Because the measurement temperature is the temperature of low-temperature cold air that reaches Temperature control can be performed and control characteristics are improved.

[Brief explanation of drawings]

Fig. 1 is a sectional view of the low temperature show case, Fig. 2 is a front view of the thermostat, Fig. 3 is a wiring diagram of a conventional temperature control device for a low temperature show case, and Fig. 4 and the following drawings show the temperature of the low temperature show case of the present invention. Embodiments of the control method are shown, with FIG. 4 being a main part wiring diagram of one embodiment, FIG. 5 being a wiring diagram of another embodiment, and FIG. 6 being a partial wiring diagram of still another embodiment. 2...Cooler, 5...Cold air flow path, 7...Inside the refrigerator, 10...
Fluorescent lamp, 11... Thermostat body, 14... Temperature sensing cylinder, 17... Electric motor, 18... Magnetic contactor, 18'...
Contact, 20... Power supply, 26... Lighting circuit, 27... Lighting circuit switch, 28... Power supply, 29... Electric heater,
30...High temperature contact, 31...Low temperature contact, 33, 34,
36...Auxiliary contact, 35...Coil.

Claims (1)

[Claims] 1. In a low-temperature show case equipped with a large number of fluorescent lights illuminating the interior of the refrigerator, the temperature inside the refrigerator when the fluorescent lights are turned on and the temperature inside the refrigerator when the lights are turned off are maintained at the same temperature. In this case, the measured temperature detected by the temperature control device is obtained from the temperature of cold air that is heat exchanged with a cooler provided in a cold air flow path separated from the inside of the refrigerator and reaches the discharge port of the cold air flow path, and
A temperature control method for a low-temperature show case in which when the fluorescent lamp is turned off, a temperature corresponding to the refrigeration load equivalent to the heat generated when the fluorescent lamp is turned on is added to the set temperature.