JPH0555793B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to a temperature control device used in a low-temperature show case or the like that is equipped with lighting inside the refrigerator.

(b) Prior Art A low-temperature display case in a supermarket or the like is a box for displaying products at a low temperature by cooling through a refrigeration cycle inside an insulated box.
That is, as shown in FIG. 1, a partition plate 40 is disposed along the inner surface of a heat insulating box 1 with one side open, and a cooler 2 consisting of an evaporator and a fan 6 constituting a cooling cycle are connected. At the same time, a discharge port 4 is provided along the upper edge of the opening, and a suction port 3 is provided along the lower edge of the opening. As shown, forced circulation is performed to form a cold air curtain in the opening from the discharge port 4 to the suction port 3 to cool the products displayed on the product display shelves 8 and wire racks 9 in the warehouse interior 7, Keeping products at low temperatures.
Incidentally, in the refrigerator interior 7, fluorescent lights 10 are provided near each shelf 8 and the discharge port 4 in order to enhance the display effect.

The required cooling capacity is determined for the low-temperature case, and a refrigerator consisting of a compressor, condenser, etc. corresponding to the required cooling capacity is installed, and the operation of the refrigerator is generally controlled by a thermostat that constitutes a temperature control circuit. Temperature control is performed so that the inside 7 of the refrigerator is maintained at a predetermined temperature. 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. And the thermostat is
As shown in FIG. 2, the thermostat main body 11
, there are temperature setting knobs 12 and 1 which serve as the temperature setting section.
A thermostat tube 14 serving as a temperature detection section is connected to the thermostat main body 11 via a capillary tube 15, and the measured temperature T _n detected by the thermostat tube 14 is Based on the comparison with the temperature set by the temperature setting _knob 12, an "open" or "close" signal is output to the output terminal 13,
Based on the signal, the electric motor of the compressor of the refrigerator is energized or de-energized via the temperature control device, and the refrigerator is driven or de-energized. Therefore, since the thermostat main body 11 has a unique on/off temperature difference _Td ,
The “open” signal is output to the output terminal 13 because
This is when T _s > T _n , and conversely, a “closed” signal is output when T _s + T _d < T _n .

Therefore, conventionally, a temperature control device for controlling the temperature of the inside of the refrigerator 7, as shown in FIG.
The temperature setting knob 12 provided on the reflector 16 above is protruded from the entire surface of the thermostat body 11 of the heat insulating box body 1, and the set temperature _Ts can be set to an arbitrary value, as shown in FIG. , is in charge of the circuit configuration of the temperature control device for the interior 7 of the refrigerator. That is, the electric motor 17 of the compressor of the refrigerator is connected to the overcurrent relay 19.
A defrost timer contact 21, a thermostat contact 11' that is opened and closed by the thermostat body 11, an internal thermostat 22, and an overcurrent relay contact 19' are connected to the three-phase power supply 20 through the contact 18 of the electromagnetic contactor 18. A series circuit of a high/low pressure switch 23 and an electromagnetic contactor 18 is connected to two phases of a power source 20 via a temperature control operating switch 23'.

Then, the temperature sensing cylinder 14 detects the temperature of the cold air 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. ” or “close” signal opens and closes the thermostat contact 11',
The electromagnetic contactor 18 is energized and de-energized, and the electromagnetic contactor 1
The temperature inside the refrigerator 7 is controlled by opening and closing the contacts 18' of 8, energizing and de-energizing the electric motor 17, and driving and de-energizing the refrigerator.

(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 lighting in the low-temperature show case is turned off at the same time as the store lights are turned off. Turn off the fluorescent lamp 10.
Therefore, when the store is closed, the heat generated by the fluorescent lamp 10 (refrigeration load)
Although the temperature of the product will not rise due to
The temperature of the cold air detected by the is the same as when the store is open during the daytime when the fluorescent lights 10 are on, so the temperature increase (△T°C) due to the fluorescent lights 10 is the same.
When the store is closed, the discharged cold air, that is, the temperature inside the warehouse 7, drops, causing the products to become too cold, which is not desirable from a product management standpoint, and also causing the operation rate of the refrigerator to be higher than necessary, resulting in a waste of electricity. Occur.

(d) Means for Solving the Problems In order to solve the above problems, the present invention provides a means for determining whether a fluorescent lamp is turned on or off, a temperature detection section for detecting the temperature of cold air, A temperature setting section sets a temperature as a control target, and the set temperature set by the temperature setting section has two control states, high and low, and while the fluorescent lamp is turned on, the lower set temperature is maintained. To provide a temperature control device comprising a control circuit that takes a control state and takes a control state of a higher set temperature while the fluorescent lamp is turned off.

(E) Effect According to the above means, while the fluorescent lamp is turned on,
The temperature can be controlled in a low-temperature control state that takes into account the heat generated by the fluorescent lamp, and while the fluorescent lamp is turned off, the temperature can be controlled in a high-temperature control state that eliminates the heat generated by the fluorescent lamp. The control target temperature can always be maintained constant regardless of whether the light is on or off.

(F) Examples The present invention will be described below with reference to FIGS. 1 to 3.
This will be explained based on the drawings from FIG. 4 onwards. Note that the same reference numerals as above indicate the same items.

In the conventional temperature control device shown in FIG. 3 in the low temperature show case of FIG. 1, the thermostat has a high temperature contact 30 for setting a high temperature and a low temperature control state as shown in FIG. A step thermostat with low temperature contact 31 for low temperature setting is used, and the switching contact is connected to high temperature contact 3.
The auxiliary relay 32 is constructed of The coil 35 constitutes a control circuit,
A changeover switch is interposed between the defrost timer contact 21 and the internal thermostat 22, and 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 T _h (T _h +△T) of the thermostat main body 11, which the high temperature contact 30 opens and closes, is set to the cold air temperature corresponding to the optimum temperature of the interior 7 at the time of closing the thermostat, which opens and closes the low temperature contact 31. The set temperature Tl (Tl=T _s ) of the main body 11 is set to a cold air temperature corresponding to the optimum temperature of the inside 7 of the refrigerator when the store is closed.

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 and the high temperature auxiliary contact 3
3 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 inside of the refrigerator 7 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 closes and the low temperature auxiliary contact 34 opens, and the opening and closing of the high temperature contact 30 causes an electromagnetic contact. Energization and de-energization of the device 18 are controlled. That is, the temperature control inside the refrigerator 7 is based on the apparent measured temperature difference ΔT between the set temperature T _s of the temperature setting knob 12.
This is done based on the set temperature T _h with ℃ added in advance, and the temperature inside the refrigerator 7 is the optimum temperature when closing (same as when opening).
will be maintained. In this embodiment, the auxiliary relay 3 is used as a means for determining whether the fluorescent lamp 10 is turned on or off.
2 is used.

In addition, in the above embodiment, the high temperature contact 30 and the low temperature contact 3
1 was connected in parallel, but as shown in Fig. 5, both contacts 30 and 31 were connected in series, and the auxiliary relay 3 was connected in series.
The auxiliary contact 36, which is the No. 2 a contact, may be connected in parallel to the high temperature contact 30 to eliminate the influence of opening and closing of the high temperature contact 30 at the time of opening.

(G) Effects of the Invention According to the present invention, a means for determining whether the illumination light of the show case is turned on or off is provided separately from the lighting circuit switch, and this means is used to determine the temperature inside the refrigerator when the illumination light is turned off. The temperature setting of the thermostat is changed to maintain the optimum temperature when the lamp was turned off, making it easy to control the thermostat circuit, which is installed separately from the lighting circuit. This also prevents damage to stored products.

[Brief explanation of the drawing]

Fig. 1 is a vertical cross-sectional view of the low-temperature show case, Fig. 2 is a front view of the thermostat main body, Fig. 3 is a wiring diagram of a conventional low-temperature show case control device, and Fig. 4 and the following drawings are the temperature control device of the present invention. FIG. 4 is a wiring diagram of one embodiment, and FIG. 5 is a wiring diagram of another embodiment. 10... Fluorescent light, 11... Thermostat body, 12... Temperature setting knob, 14... Temperature sensing tube,
30...High temperature contact, 31...Low temperature contact.

Claims (1)

[Claims] 1. In a temperature control device equipped with a thermostat that detects the temperature of cold air heat exchanged with a cooler installed in a cold air passage separated from the inside of the refrigerator and controls the temperature inside the refrigerator at a set temperature, Separately from the lighting circuit switch that controls whether the lighting light is turned on or off, a means for determining whether the lighting light is on or off is provided, and by this means, when the lighting light is turned off, the temperature inside the refrigerator can be determined as if the lighting light was on. A temperature control device characterized in that the temperature setting of the thermostat is switched so as to maintain the temperature at the optimum temperature when the temperature is set.