JPH0228785B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (A) Field of Industrial Application The present invention relates to a method of operating 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, and maintains 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 of the low-temperature case is determined, and a refrigerating machine consisting of a compressor, condenser, etc. corresponding to the required refrigerating capacity is built in. Generally, the operation rate of the refrigerating machine is controlled by a thermostat, and the temperature inside the refrigerator 7 is controlled by a thermostat. is in control. In other words, the operating rate is the percentage of operating time of the refrigerator, and if the set temperature of the thermostat is set low, the operating rate increases and the products in the refrigerator compartment 7 are cooled well. If it is set high, the operating rate will decrease and the temperature of the product will increase. 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 device and protrudes to the outside, so that the set temperature Ts can be set to an arbitrary value, as shown in the circuit diagram of Fig. 3.
It constitutes an operating device that controls the temperature inside the refrigerator 7. That is, the electric motor 17 of the compressor of the refrigerator is
Contact 1 of overcurrent relay 19 and electromagnetic contactor 18
A defrost timer contact 21, a thermostat contact 11' opened and closed by the thermostat body 11, an internal thermostat 22, an overcurrent relay contact 19', and a high/low pressure switch 23 A series circuit of the electromagnetic contactor 18 and the electromagnetic contactor 18 is connected to two phases of the power supply 20 via a temperature control operation 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, after the store is closed, the temperature of the products will no longer rise due to the heat generated by the fluorescent lamps 10 (refrigeration load), but the temperature of the cold air detected by the thermosensor tube 14 will be lower than that during the daytime when the fluorescent lamps 10 are on. 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 problems, the present invention exchanges heat between a preset temperature and a cooler installed in a cold air flow path separated from the interior of the refrigerator. , the refrigerator is operated based on a signal from a temperature control device that compares the temperature of the cold air reaching the discharge port of the cold air flow path with the detected measured temperature, and when the fluorescent lamp for lighting the interior of the refrigerator is turned off, This is a method of operating a low-temperature show case, in which the set temperature set by the temperature control device is raised higher than when the fluorescent lamp is turned on, and the operating rate of the refrigerator is lowered.

(e) Effect The above technical means works as follows.

The inside of the cold air flow path, where the measured temperature obtained by the temperature control device is detected, is separated from the inside of the refrigerator, so it is almost unaffected by the temperature inside the refrigerator and the radiant heat of the fluorescent lights. Since the temperature of the cold air that is exchanged and reaches the discharge port is detected as the measured temperature, it is possible to detect the cold air temperature that is not affected by the outside air and has little temperature change. The refrigeration load caused by the heat generated by fluorescent lamps has been eliminated, and on the other hand, the set temperature when the lights are off is higher than the set temperature when the lights are on to match the refrigeration load caused by the heat generated. This will reduce the rate.

(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 reference numerals as above indicate the same items.

In the conventional operating 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 the 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 temperature sensing cylinder 14 has decreased by △T°C compared to when the store opened, and since the set temperature Ts of the temperature setting knob 12 is constant, the "close" of the thermostat body 11 is The signal output decreases, and the operating rate of the refrigerator decreases. The inside of the cold air flow path 5, which is the detection point of the measured temperature Tm obtained by the temperature sensing cylinder 14 of the thermostat main body 11, which is a temperature control device, is the inside of the refrigerator 7.
Because it is separated from the refrigerator, the temperature of the inside 7 and the radiant heat of the fluorescent lamp 10 have almost no effect, and the temperature of the cold air that is exchanged with the cooler 2 and reaches the discharge port 4 is detected as the measured temperature Tm. For this reason, it is possible to detect cold air temperature that is not affected by outside air and has little temperature change.

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, the set temperature Ts in any case. The interior of the refrigerator can be maintained at the same temperature as a reference, and power consumption can be reduced.

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/de-energization of the electromagnetic contactor 18 is controlled by opening and closing of the low-temperature contact 31. That is, the temperature control of the chamber interior 7 is performed based on the set temperature Tl,
The inside of the refrigerator 7 is maintained at the optimum 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. In other words, the temperature control inside the refrigerator 7 is performed by adjusting the apparent measured temperature difference △ to the set temperature Ts of the temperature setting knob 12.
This is done based on the set temperature Th to which T° C. is added in advance, and the interior 7 of the refrigerator is maintained at the optimum temperature at the time of closing (the same temperature as at the time of opening), and the operating rate of the refrigerator is reduced.

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 30 at the time of opening
The effects of the present invention can also be obtained by removing the effects of opening and closing.

(g) Effects of the invention The present invention described above produces the effects listed below.

When the fluorescent lamps are turned off, compared to when the fluorescent lamps are turned on, the refrigerator can be operated at a higher temperature setting that corresponds to the refrigeration load equivalent to the heat generated by the fluorescent lamps. The operating time of the refrigerator is shorter and the load is lighter than when the fluorescent lights are on, and the defrost cycle of the refrigerator can also be lengthened, which contributes to power savings and keeps the temperature inside the refrigerator constant. It also prevents the product from getting too cold.

The inside of the cold air flow path, where the measured temperature is detected, is separated from the inside of the refrigerator, so it is hardly affected by the temperature inside the refrigerator or the radiant heat of the fluorescent lights. Since the temperature of the cold air at a very low temperature is detected as the measurement temperature, it is possible to detect the temperature of the cold air unaffected by the outside air.As a result, a stable measurement temperature is always obtained regardless of whether the fluorescent lamp is on or off, and the control characteristics are improved. will improve.

[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 low-temperature show case operating device, and Fig. 4 and the following drawings are the low-temperature show case operating device of the present invention. FIG. 4 is a wiring diagram of a main part of one embodiment, FIG. 5 is a wiring diagram of another embodiment, and FIG. 6 is 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 tube, 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. Compare the preset temperature and the measured temperature of the cool air that has been heat exchanged in a cooler installed in a cold air flow path that is separate from the inside of the refrigerator and that reaches the discharge port of the cold air flow path. The refrigerator is operated based on a signal from the temperature control device, and when the fluorescent lamps for lighting the interior of the refrigerator are turned off, the set temperature set by the temperature control device is lower than when the fluorescent lamps are turned on. A method of operating a low-temperature case by increasing the operating rate of the refrigerator.