JPS63135766A - Temperature controller for low-temperature showcase - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application This invention relates to a temperature control device for a low-temperature showcase equipped with a fluorescent lamp for illuminating the interior of the refrigerator.

(b) Prior Art Generally, a low-temperature showcase 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 installed at the bottom of an insulating box (1) with an open negative side.
and a suction port (3) provided at the bottom of the insulation box (1).
), a cold air flow path (5) is formed from the cooler (2), the inside back of the insulated box (1), and the discharge port (4) provided at the top of the insulated box (1), and the fan ( 6), the cooler (2
) is circulated as shown by the arrow, supplying cold air to the inside of the refrigerator (7), and
) to the suction port (3), an air curtain is formed at the opening of the insulated box (1), and the product display shelf (8) inside the refrigerator (7) is formed.
) and wire racks (9〉) to keep the products at a low temperature.In addition, in order to enhance the display effect, each shelf (8) and A fluorescent lamp (10) is provided near the outlet (4).

The required refrigerating capacity is determined for the low-temperature showcase, 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 inside (7 > temperature control. In other words, the operating rate is the percentage of operating time of the refrigerator, and if the temperature setting of the thermostat is set lower, the operating rate will increase and the products in the refrigerator (7) will be better. On the other hand, if you set the temperature of the thermostat higher, the operating rate will decrease and the temperature of the product will become higher.
As shown in Figure 2, in the thermostat body (11),
Temperature setting knob (12) and one or more sets of output terminals (1
3) is provided, and the temperature sensing tube (14) is connected to the thermostat main body (11) via the capillary tube (15), and the measured temperature T detected by the temperature sensing tube (14) and the temperature By comparing the set temperature T with the setting knob (12), a signal of "1 open" or "close" is output to the output terminal (13). The electric motor of the compressor of the machine is energized and de-energized, and the refrigerator is driven and de-energized. Therefore, since the thermostat body (11) has its own important temperature difference T4, " The “open” signal is output when
1',>T, and conversely, a "closed" signal is output when T,+TJ<T.

Therefore, conventionally, the temperature control device for controlling the temperature inside the refrigerator (7) described above has been designed to connect the temperature sensing tube (14) to the cold air flow inside the discharge port (4), as shown in FIG. (5), and the thermostat body (11) is installed on the front upper flap (16) of the insulating box (1) with a temperature setting knob (
12) is protruded to the outside so that the set temperature T can be set to an arbitrary value, and the circuit configuration of the temperature control device inside the refrigerator (7) is implemented as shown in FIG. 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 magnetic contactor (18), and the defrost timer contact (21), thermostat contact (11') that can be opened and closed by the thermostat body (11), internal thermostat (22), overcurrent relay contact (19'), high/low pressure switch (23), and magnetic contactor (18). The series circuit is connected to two phases of the power supply (20) via a temperature-controlled operating switch (23).

Then, the temperature-sensitive cylinder 14) detects the temperature of the cold air in the cold air flow path (5), and based on the detection signal, an "open" or "close" signal is sent to the output terminal (13) of the thermostat body (11). The thermostat contact (11') is opened and closed by the "open" and "close" signals, and the electromagnetic contactor (18)
is energized and de-energized, and the contact (18″) of the electromagnetic contactor (18)
), energizes the electric motor (17), drives the refrigerator, and controls the temperature inside the refrigerator (7).

(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, at the same time as the store lights are turned off, the low-temperature showcase is illuminated. 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 light (10) (refrigeration load), but the temperature of the cold air detected by the thermosensor tube (14) will be lower than when the fluorescent light (10) is turned on. Since this is the same as when the store opens during the daytime, when the store is open, the temperature of the discharged cold air, that is, the temperature inside the refrigerator (7), decreases by the amount of temperature increase (8T"C) caused by the fluorescent light (10) when the store closes. As a result, the product becomes too cold, which is not desirable from the standpoint of product management, and the operation rate of the refrigerator becomes higher than necessary, resulting in a problem of wasted power.

(d) Means for solving the problems The present invention aims to solve the above problems, and as a means for solving the problems, a temperature control device for a low-temperature showcase is provided.
There is a thermostat for controlling the temperature inside the refrigerator, which takes a high temperature control state with a higher set temperature when the store is closed, and a low temperature control state with a lower set temperature when the store is open. and a changeover switch that is opened to put the thermostat in a high-temperature control state when the store is open, and closed to put the thermostat in a low-temperature control state when the store is open. It is designed to change the temperature inside the refrigerator.

(*) EXAMPLES The present invention will be described below with reference to FIGS. 1 to 3 and 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 showcase of FIG.
A lighting circuit (26) configured by 5) is connected in series to a commercial power source (28) via a lighting circuit switch (27), and an electric heater (
29) are connected in series via the lighting circuit switch (27). Note that the switching contact is a thermostat contact (11').

When the store opens, when the lighting circuit switch (27) which also serves as the switching means of the thermostat main body (11) is closed, the lighting circuit (26) is de-energized and the low-temperature showcase becomes open, and the electric heater ( Since the electric heater (29) is energized, the thermosensor tube (14) is energized.
) is heated, and the temperature T of the cold air measured by the thermosensor tube (14) becomes higher than the cold air temperature by ΔT"C. In other words, the thermosensor tube (14) detects the cold air apparently higher by ΔT℃. .Therefore, the set temperature T of the temperature setting knob (12)
, is made higher by ΔT″C than the temperature of the cold air corresponding to the desired temperature inside the refrigerator (7〉) at the time of opening, and when closing, the lighting circuit switch (27〉) is opened and the lighting circuit (26
) becomes de-energized and the low-temperature showcase becomes non-operating, and at the same time, the electric heater (29) becomes de-energized, and the electric heater (29) no longer heats the temperature-sensitive cylinder (14). 14) Measured temperature T. is equal to the temperature of the cold air. That is, the measured temperature T of the cold air in the temperature sensing cylinder (14).

has decreased by ΔT"C compared to when the store opened, and since the set temperature T6 of the temperature setting knob (12) is constant, the "close" signal output from the thermostat body (11) decreases, and the refrigerator operation rate decreases.

Therefore, the temperature sensing tube (14) generated by the electric heater (29> By setting the apparent measured temperature difference ΔT″C, the temperature inside the refrigerator can be maintained at the same temperature based on the set temperature T in any case, in order to appropriately manage the temperature of the products in the low-temperature showcase in response to store opening and closing. In addition, it is possible to reduce power consumption.

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 showcase of FIG. 1, the thermostat has a high temperature contact (30) for setting a high temperature and a low temperature contact (31) for setting a low temperature. using a step thermostat having
), the low temperature contact (31) and the auxiliary relay (
It consists of a parallel circuit with the series circuit of the low-temperature auxiliary contact (34), which is a normally open contact of 32), and the auxiliary relay (34).
32〉 coil (35) constitutes a control circuit, a changeover switch is interposed between the defrost timer contact (21) and the internal thermometer (22), and the lighting circuit (26) and auxiliary relay ( The coils (35) of 32) are each connected to a commercial power source (28) via a lighting circuit switch (27).

Then, the set temperature r* (T*-r-+Δt) of the thermostat main body (11), which opens and closes the high-temperature contact (30), is set to the cold air temperature corresponding to the optimal temperature inside the refrigerator (7) at the time of closing. Thermostat body (11) that opens and closes contacts (31)
The set temperature rl (Tl-T, ) of the inside of the refrigerator at the time of opening (
Set the cold air temperature corresponding to the optimum temperature in 7).

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 (
33) is opened, the low-temperature auxiliary contact (34) is closed, the effect of opening and closing of the high-temperature contact (30) is eliminated, and the opening and closing of the low-temperature contact (31) causes the 'wt magnetic contactor (18) to be energized or de-energized. is controlled. That is, the temperature control inside the refrigerator (7) is performed based on the set temperature T1, and the temperature inside the refrigerator (7) is controlled based on the set temperature T1.
) is maintained at the optimum temperature at the time of opening.

Next, when the lighting circuit switch (27) is opened at the time of closing, the fill (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. By opening and closing the high temperature contact (3o), energization and de-energization of the electromagnetic contactor (18) can be controlled.

In other words, the temperature inside the refrigerator (7) is controlled by the temperature setting knob (
12) Set temperature T, apparent measured temperature difference T″C
This is done based on a preset temperature T, which is added in advance, and the inside of the refrigerator (7) is maintained at the optimum temperature when the store is closed (the same temperature as when the store is opened).

In addition, in the above embodiment, the high temperature contact (30) and the low temperature contact (3
1) are connected in parallel, but as shown in Figure 6, both contacts (30) and (31) are connected in series, and in addition, the auxiliary contact (36), which is the normally open contact of the auxiliary relay (32), is connected in series. of,
Connect in parallel to the high temperature contact (30), and connect the high temperature contact (3
Even if the influence of opening and closing of 0) is removed, the effects of the present invention can be obtained.

(f) Effect of invention According to the present invention described above, the following effects are produced.

■When the low-temperature showcase is closed and the fluorescent lights for interior lighting are turned off, the refrigeration load due to the heat generated by the fluorescent lights is lower than when it is open and the fluorescent lights for interior lighting are on. In other words, since the refrigerator is operated at the higher setting temperature of the thermostat, the operation time of the refrigerator is shortened, which contributes to power saving and prevents the products in the refrigerator from becoming too cold.

(2) Since the thermostat can be automatically switched from a high temperature control state to a low temperature control state or vice versa by means of switching means for setting the low temperature showcase to non-operation or operation, operation of the temperature control device is simplified.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of the low temperature showcase, Fig. 2 is a front view of the thermostat, Fig. 3 is a wiring diagram of the temperature control device of a conventional low temperature showcase, and Fig. 4 and the following drawings are the low temperature showcase of the present invention. Fig. 4 is a main part wiring diagram of one embodiment, Fig. 5 is a wiring diagram of another embodiment, and Fig. 6 is a partial wiring diagram of another embodiment. It is. (2)...Cooler, (5)...Cold air flow path, (7
)... Inside the refrigerator, (10>... Fluorescent light, (11)...
・Thermostat body, (14)... Temperature sensing tube, (1
7)...Electric motor, (18)...Magnetic contactor, (
18')... Contact, (20)... Power supply, (26
)...Lighting circuit, (27)...Lighting circuit switch.

Claims (1)

[Claims] 1. A thermostat for controlling the temperature inside the refrigerator, which takes a high temperature control state with a higher set temperature in a non-business state and a low temperature control state with a lower set temperature in a business state; and switching means for controlling the thermostat to take a low temperature control state in the operating state.