JPH1023976A - Controller for warmer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stably control an inside temperature to a set temperature without being affected by the change an external air temperature by comparing the output of a differential amplifying means with that of sawtooth wave generating means and controlling the ON/OFF of electrification to a heater based on this compared output. SOLUTION: A controller 1 generates the output in proportion to the difference between the inside temperature detected by an inside sensor 6 and the temperature set by a setting circuit 11 through a differential amplifier circuit 8 and changes the amplification factor outputted by that differential amplifier circuit 8 through an external air temperature correction circuit 23 based on the output of an external air temperature sensor 13. Then, based on the output of that external air temperature sensor 13, the output of the differential amplifier circuit 8 is compared with the output of a sawttoth wave generating circuit 14 for generating sawtooth waves by a comparator circuit 12 and based on the output of this comparator circuit 12, the ON/OFF of electrification to a heater 17 is controlled by an SSR 16. Thus, the inside temperature is controlled to the set temperature without being affected by the change of the external air temperature.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for a refrigerator which heats the inside of the refrigerator by a heater.

[0002]

2. Description of the Related Art Conventionally, in a low-temperature showcase,
For example, Japanese Utility Model Publication No. 5-5429 (F25D23 / 0)
0) for the purpose of defrosting the cooler, or
A heater is attached for the purpose of preventing dew condensation.
A heater is attached to the storage to keep the temperature inside the storage at a set value.

[0003] When controlling the energization of the heater in the above-mentioned refrigerator, normally, proportional control based on the temperature in the refrigerator and the set temperature is performed. In this proportional control, a differential amplifier circuit that generates an output proportional to the difference between the internal temperature detected by the sensor and the set temperature, and a sawtooth wave generating circuit that generates a sawtooth wave are provided. And a sawtooth wave generated by the sawtooth wave generation circuit is compared by a comparison circuit, and the switching element is used to turn on the heater for a period when the output of the differential amplifier circuit is larger than the sawtooth wave, and to turn off the heater for a short period. A method of controlling the duty ratio of the heater by executing the control is adopted.

That is, the heater is continuously energized while the internal temperature is low and the output of the differential amplifier circuit is above the sawtooth wave. Then, when the internal temperature gradually rises and approaches the set temperature, the output of the differential amplifier circuit decreases,
At a certain temperature (proportional control start temperature), it crosses the sawtooth wave (that is, enters the proportional band). The proportional control was started from this point, and the heater duty ratio gradually decreased as the temperature approached the set temperature, and eventually converged on the set temperature.

[0005]

However, in an environment where the outside temperature is low (in winter), where the storage room is installed, heat loss from the box increases. Therefore, if the proportional control start temperature is set low, the energization rate to the heater is reduced from an earlier point in time, so that the internal temperature converges at a point lower than the set temperature.

On the other hand, if the proportional control start temperature is set high in order to prevent this, in an environment where the outside air temperature is high (summer season), the inside temperature exceeds the set temperature in the process of convergence, so-called overshoot. There was a problem that became large. The present invention has been made to solve such a conventional technical problem, and is capable of stably controlling the internal temperature to a set temperature without being affected by a change in outside air temperature. An object of the present invention is to provide a storage control device.

[0007]

A control device according to a first aspect of the present invention is applied to a warm storage which is formed by heating the inside of a refrigerator formed in a box by a heater, and detects the temperature in the refrigerator. Temperature detection means, an outside air temperature detection means for detecting an outside air temperature,
Control means for controlling the energization of the heater based on the output of each temperature detection means. The control means outputs an output proportional to the difference between the set temperature and the inside temperature detected by the inside temperature detection means. Amplifying means for generating, an outside air temperature correcting means for changing the amplification factor of the differential amplifying means based on the output of the outside air temperature detecting means, a sawtooth wave generating means for generating a sawtooth wave, and a differential amplifying means. A comparison means for comparing the output of the sawtooth wave generation means, and a switching means for controlling ON / OFF of energization to the heater based on the output of the comparison means.

According to the first aspect of the present invention, the differential amplifying means for generating an output proportional to the difference between the internal temperature detected by the internal temperature detecting means and the set temperature, and the sawtooth wave generating the sawtooth wave Means for turning on the power to the heater by the switching means based on the output of the comparing means for comparing the outputs of the differential amplifying means and the sawtooth wave generating means.
In the OFF control, the outside air temperature detecting means is provided, and the outside air temperature correcting means for changing the amplification factor of the differential amplifying means based on the output of the outside air temperature detecting means is provided.
The proportional control start temperature can be changed according to the outside air temperature at which the refrigerator is installed.

That is, the outside air temperature correction means increases the amplification factor to increase the proportional control start temperature under a low outside air temperature, and conversely lowers the amplification ratio under a high outside air temperature to reduce the proportional control start temperature. By changing the temperature to a lower temperature, the so-called overshoot in which the internal temperature converges at a temperature lower than the set temperature or greatly exceeds the set temperature is effectively eliminated, and stable temperature control is realized. Is possible.

According to a second aspect of the present invention, there is provided a control apparatus for a refrigerator, wherein the outside air temperature detecting means is constituted by a resistance temperature measuring element mounted on the substrate, and the substrate is a box body through which the outside air flows. It is attached to the part. According to the invention of claim 2, in addition to the above, the outside air temperature detecting means is constituted by a resistance thermometer mounted on the substrate, and the substrate is mounted on a part of the box through which the outside air flows. Thus, the cost can be reduced by reducing the number of circuit components while realizing efficient control.

A control device according to a third aspect of the present invention is applied to a warm storage which is formed by heating the inside of a refrigerator formed in a box body by a heater, and detects temperature inside the refrigerator, An outside air temperature detecting means for detecting a temperature; and a control means for controlling energization of the heater based on an output of each temperature detecting means. The control means includes an inside temperature detected by the inside temperature detecting means. Amplifying means for generating an output proportional to the difference between the temperature and the set temperature, a sawtooth wave generating means for generating a sawtooth wave, and outside air for changing the peak value of the sawtooth wave generating means based on the output of the outside air temperature detecting means. Temperature correction means;
A comparison means for comparing the outputs of the differential amplifying means and the sawtooth wave generating means, and a switching means for controlling ON / OFF of energization to the heater based on the output of the comparison means.

According to the third aspect of the present invention, the differential amplifying means for generating an output proportional to the difference between the internal temperature detected by the internal temperature detecting means and the set temperature, and the sawtooth wave generating for generating the sawtooth wave Means for turning on the power to the heater by the switching means based on the output of the comparing means for comparing the outputs of the differential amplifying means and the sawtooth wave generating means.
In the OFF control, an outside air temperature detecting means is provided, and an outside air temperature correcting means for changing the peak value of the sawtooth wave generating means based on the output of the outside air temperature detecting means is provided, so that a warm storage is provided. The proportional control start temperature can be changed according to the outside air temperature.

That is, under the low outside air temperature, for example, the peak value is lowered to increase the proportional control start temperature under the low outside air temperature, and conversely, under the high outside air temperature, the peak value is increased to increase the proportional control start temperature. By changing the temperature to a lower temperature, the so-called overshoot in which the internal temperature converges at a temperature lower than the set temperature or greatly exceeds the set temperature is effectively eliminated, and stable temperature control is realized. Is possible.

In the control device according to a fourth aspect of the present invention, the outside air temperature detecting means is constituted by a resistance temperature sensor mounted on the substrate, and the substrate is mounted on a part of a box through which the outside air flows. Things. According to the invention of claim 4,
In addition to the above, the outside air temperature detecting means is constituted by a resistance temperature detector mounted on the substrate, and the substrate is mounted on a part of a box through which the outside air flows, so that the circuit can be controlled while realizing stable control. The cost can be reduced by reducing the number of parts.

[0015]

Next, an embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 is a perspective view of a storage 40 to which the control device 1 of the present invention is applied, FIG. 2 is a schematic sectional view of the storage 40,
FIG. 3 is a block diagram of an electric circuit of the control device 1. The preservation cabinet 40 of the embodiment is for transporting, for example, cooked dishes and lunches while heating, and is configured by filling a heat insulating material 43 between an outer box 41 and an inner box 42 made of a steel plate. A box 44 made of a heat-insulating box, an inside 46 serving as a storage room formed in the box 44, and a door 47 (omitted in FIG. 2) for opening and closing the front of the inside 46 so as to be openable and closable. Are mounted on the four corners of the lower surface of the box 44.

The heater 17 composed of an electric heater is attached to the heat insulating material 43 side of the inner box 42 and the box 4
6, a machine room 52 for accommodating a substrate 51 on which circuit components of the control device 1 described later are assembled is formed. The outer box 41 corresponding to the machine room 52
Are formed with a plurality of ventilation holes 53, whereby external air is circulated in the machine room 52.

Next, in FIG. 3, the control device 1 is roughly divided into a temperature control unit 2 for performing a temperature control inside the storage 40,
And a protection circuit unit 3 for executing an abnormality alarm and a protection operation. The proportional control circuit 4 included in the temperature control section 2 is provided with an in-compartment sensor 6 (comprising a thermistor or the like) as an in-compartment temperature detecting means for detecting the temperature of the in-compartment 46.

The in-compartment sensor 6 is connected to an amplifier circuit 7 composed of an OP amplifier, and the output of the amplifier circuit 7 is supplied to a differential amplifier circuit 8 also composed of an OP amplifier as a differential amplifier. Connected to non-inverting input. The output of a setting circuit (setting the temperature in the refrigerator) 11 to which the terminal voltage of a temperature setting volume (variable resistor) 9 is connected is connected to the inverting input of the differential amplifier circuit 8.

Reference numeral 13 denotes an outside air temperature sensor as outside air temperature detecting means. The outside air temperature sensor 13 is connected to an outside air temperature correcting circuit 23 as outside air temperature correcting means.
This outside air temperature correction circuit 23 is connected to the differential amplifier circuit 8. The outside air temperature correction circuit 23 increases the amplification factor of the differential amplifier circuit 8 when the outside air temperature is low, based on the outside air temperature (the ambient temperature of the storage 40) detected by the outside air temperature sensor 13, and conversely increases the outside air temperature. Sometimes the differential amplifier circuit 8
It has the effect of lowering the amplification factor.

The output of the differential amplifying circuit 8 is connected to a non-inverting input of a comparing circuit 12 (comparator) which also comprises an OP amplifier. The inverting input of the comparison circuit 12 includes a PUT,
Also, the output of a sawtooth wave generation circuit 14 as a sawtooth wave generating means constituted by a resistor or the like is connected.
The output of the comparison circuit 12 triggers a solid state relay SSR16 as a switching means. This SSR 16 is a heater 17 for heating the inside of the warm storage 40.
And the commercial AC power supply AC. Further, a transistor 18 is connected between the output of the comparison circuit 12 and the ground.
Is connected.

On the other hand, the protection circuit section 3
A power supply voltage conversion circuit 24 having a current transformer (not shown) as current value detection means provided in the electric circuit of the heater 17 in the disconnection detection circuit 21. Is provided. The power supply voltage conversion circuit 24 converts the current flowing through the heater 17 detected by the current transformer into a voltage value and outputs the voltage value. The output of the power supply voltage conversion circuit 24 is connected to an inverting input of a comparison circuit (comparator) 26 composed of an OP amplifier. You. This comparison circuit 26
Is connected to a terminal voltage of a disconnection alarm current value setting volume (variable resistor) 27.

The output of the comparison circuit 26 is input to an AND circuit 28, and the output of the comparison circuit 12 is further input to the AND circuit 28 via a permission signal generation circuit 29. The permission signal generation circuit 29 includes a resistor,
The comparison circuit 12 includes a capacitor and a diode.
Is output to the AND circuit 28 by delaying the rise of the output and delaying the fall.

On the other hand, a delay circuit 31 is provided in the overcurrent detection circuit 22, and the output of the power supply voltage conversion circuit 24 is supplied to the comparison circuit (comparator) 3 via the delay circuit 31.
2 non-inverting inputs. A terminal voltage of a short-circuit alarm current value setting volume (variable resistor) 33 is connected to an inverting input of the comparison circuit 32. The AND of the comparison circuit 32 and the disconnection detection circuit 21
The output of the circuit 28 is input to an OR circuit 34, and the output of the OR circuit 34 is connected via a self-holding circuit 36 to a display lamp 37 as alarm means. The output of the self-holding circuit 36 is connected to the base of the transistor 18.

Next, the operation of the control device 1 having the above configuration will be described. The terminal voltage of the sensor 6 in the refrigerator changes in inverse proportion to the temperature in the refrigerator 40, which is amplified by the amplifier circuit 7 and input to the non-inverting input of the differential amplifier circuit 8. The set temperature set by the volume control 9 is input to the inverting input of the differential amplifier circuit 8 through the setting circuit 11, whereby the differential amplifier circuit 8 detects the set temperature and the internal sensor 6. Outputs the temperature difference (voltage).

Now, when the internal temperature is sufficiently lower than the set temperature, the output of the amplifier circuit 7 is larger than the output of the set circuit 11, so that the output V1 of the differential amplifier circuit 8 becomes
As shown in FIG. 4, the peak value of the sawtooth wave V2 generated by the sawtooth wave generation circuit 14 is higher than the peak value. Therefore, the output of the comparison circuit 12 is always high potential (hereinafter, referred to as “H”).
Therefore, the SSR 16 is constantly triggered to conduct, and the heater 17 is constantly energized, that is, 100% energized.

With such 100% power supply, the temperature in the refrigerator increases rapidly. As a result, the terminal voltage of the internal sensor 6 decreases, and the difference from the set temperature decreases, so that the output V1 of the differential amplifier circuit 8 also decreases. Then, when the peak value of the sawtooth wave V2 is reached, the proportional control is started. That is, when the output V1 of the differential amplifier circuit 8 becomes lower than the sawtooth wave V2, the output of the comparison circuit 12 becomes a rectangular pulse which becomes "H" only during the period when V1 is higher than V2.

In the SSR 16, the output of the comparison circuit 12 is "H".
(ON) only during the period where
(Referred to as “L”) during non-conduction (OFF),
The duty ratio of the heater 17 decreases (for example, 50
%). As a result, the amount of heat generated by the heater 17 decreases, and the degree of increase in the internal temperature becomes slow. Then, when the internal temperature further increases, the output V1 of the differential amplifier circuit 8 further decreases, whereby the duty ratio of the heater 17 also gradually decreases, but after the internal temperature reaches the set temperature, Each element is set so that the output V1 of the differential amplifier circuit 8 does not reach the lowest point of the sawtooth wave V2 even at the time when the heat leakage of the storage 40 and the calorific value of the heater 17 are balanced.

On the other hand, the outside air temperature correction circuit 23 increases the amplification factor of the differential amplifier circuit 8 under the low outside air temperature based on the outside air temperature detected by the outside air temperature sensor 13 as described above. The internal temperature that reaches the peak value of V2 increases. That is, since the proportional control start temperature is increased in the low outside air temperature environment, even in the winter season when heat leakage from the storage 40 is large, it is possible to prevent the temperature in the storage from converging at a temperature lower than the set temperature, and to surely prevent it. It becomes possible to converge to the set temperature.

Conversely, the outside air temperature correction circuit 23 lowers the amplification factor of the differential amplifier circuit 8 under a high outside air temperature, so that the output V
The internal temperature at which 1 reaches the peak value of the sawtooth wave V2 decreases. This makes it possible to effectively eliminate so-called overshoot in which the internal temperature greatly exceeds the set temperature in summer. On the other hand, the value of the current supplied to the heater 17 is detected by the current transformer of the power supply voltage conversion circuit 24, converted to a voltage value by the power supply voltage conversion circuit 24, and input to the inverting input of the comparison circuit 26.
At this time, if no abnormality (disconnection / short circuit) has occurred in the heater 17 and the supplied current value is the rated current, the disconnection alarm current value (threshold value voltage, here, set in the volume 27). The output of the comparison circuit 26 during the period in which the SSR 16 is conducting is “L”, and the conduction current is low. The period of zero is "H".

The output of the permission signal generation circuit 29 and the output of the comparison circuit 26 are input to the AND circuit 28 and the product thereof is taken. The output of the permission signal generation circuit 29 is The output is delayed with the rise of the output and hastened the fall. Therefore, in a state where the rated current is flowing through the heater 17, both outputs simultaneously become "H" and the
The output of the D circuit 28 does not become “H” and always becomes “L”.

Therefore, as long as the output of the comparison circuit 32 is "L", the output of the OR circuit 34 is "L", the self-holding circuit 36 does not generate an output, and the display lamp 37 does not operate. False alarms are avoided. Here, the output of the comparison circuit 12 is not manipulated by the permission signal generation circuit 29, and the comparison circuit 26 is
The output of the AND circuit 28 intermittently becomes "H" and a warning is issued when the product of the output of the AND circuit 28 and the output of the AND circuit 28 becomes "H" at the same time. Then, such inconvenience is resolved.

Next, when a break occurs in a part of the heater 17, the current value of the heater 17 detected by the current transformer becomes lower than the break alarm current value set by the volume 27. , The output of the comparison circuit 26 becomes “H” during the entire period in which the output of the comparison circuit 12 becomes “H” and the SSR 16 is conducting (ON), whereby the output of the AND circuit 28 becomes “H”. .

This output is input to the self-holding circuit 36 via the OR circuit 34 and is self-held, so that an alarm is continuously displayed on the display lamp 37 and the transistor 18 is turned on to turn on the comparison circuit. Twelve outputs are forced to zero. As a result, the SSR 16 becomes non-conductive, and the power supply to the heater 17 is cut off. In this way, when a disconnection occurs in a part of the heater 17, it is possible to quickly and accurately detect the disconnection based on the decrease in the energizing current and issue an alarm. Therefore, it is possible to prevent the occurrence of temperature abnormality and the normal deterioration of the heater 17 beforehand. In addition, the operation of the display lamp 37 is self-maintained, and the energization of the heater 17 is prohibited while the display lamp 37 is operating. Therefore, the alarm is stopped for some reason such as a fluctuation in the power supply voltage. Can be prevented. The self-holding of the alarm is canceled when the power supply is stopped.

The output of the power supply voltage conversion circuit 24 is delayed by the delay circuit 31 of the overcurrent detection circuit 22 and then input to the non-inverting input of the comparison circuit 32. At this time, if no abnormality (disconnection / short circuit) has occurred in the heater 17 and the supplied current value is the rated current, the short-circuit alarm current value (threshold voltage; here, the threshold value voltage set in the volume 33). , A predetermined value higher than the rated current), the output of the comparison circuit 32 becomes “L”. Therefore, as long as the output of the AND circuit 28 is “L”, the output of the OR circuit 34 is “L”, the self-holding circuit 36 does not generate an output, and the display lamp 37 does not operate.

Next, when a short circuit occurs in a part of the heater 17, the heater 17 detected by the current transformer
Is higher than the short-circuit alarm current value set by the potentiometer 33, the output of the comparison circuit 32 becomes “H”.
Becomes This output is input to the self-holding circuit 36 via the OR circuit 34 and is self-held, so that the alarm display 37
At the same time, the transistor 18 is turned on, and the output of the comparison circuit 12 is forcibly reduced to zero. As a result, the SSR 16 becomes non-conductive, and the power supply to the heater 17 is cut off.

As described above, the display lamp 37 is operated when the current supplied to the heater 17 exceeds a predetermined value. Therefore, when a short circuit occurs in a part of the heater 17, the current supplied increases. , The short circuit can be detected quickly and accurately, and an alarm can be issued.
Therefore, it is possible to prevent the occurrence of temperature abnormality and the normal deterioration of the heater 17 beforehand.

Here, in the embodiment, the power supply voltage conversion circuit 24
Is output by the delay circuit 31 and input to the comparison circuit 32. Therefore, even if the rise of the terminal voltage (reference voltage) of the variable resistor 33 is delayed when the power is turned on, a short circuit alarm may be issued. Is prevented. Next, FIG. 5 shows a block diagram of a control device 1 according to another embodiment of the present invention. The same reference numerals as those in FIGS. 1 to 4 denote the same parts. in this case,
The outside air temperature detecting means is replaced by a substrate 5 instead of the outside air temperature sensor.
Resistance thermometer (such as thermistor) 5 mounted on 1
The resistance thermometer 56 is connected to the outside air temperature correction circuit 23.

At this time, the ventilation holes 53
Since the outside air is circulated, the resistance temperature measuring body 56 on the substrate 51 can also accurately detect the outside air temperature. Further, according to such a configuration, the outside air temperature sensor 13 is
Circuit components such as a lead wire and a connector can be eliminated as compared with the case where the components are mounted on the outer surface, and cost can be reduced.

FIG. 6 shows a block diagram of another control device 1 of the present invention. In the drawings, the same reference numerals as those in FIGS. 1 to 5 have the same or similar functions. In this case, the outside air temperature correction circuit 23 to which the outside air temperature sensor 6 is connected is connected not to the differential amplification circuit 8 but to the sawtooth wave generation circuit 14. Then, based on the outside air temperature detected by the outside air temperature sensor 13, the outside air temperature correction circuit 23 lowers the peak value of the sawtooth wave V2 generated by the sawtooth wave generation circuit 14 under a low outside air temperature.

Thus, the output V1 of the differential amplifier 8 is
Reaches the peak value of the sawtooth wave V2. That is, since the proportional control start temperature is increased in the low outside air temperature environment, even in the winter season when heat leakage from the storage 40 is large, it is possible to prevent the temperature in the storage from converging at a temperature lower than the set temperature, and to surely prevent it. It becomes possible to converge to the set temperature.

Conversely, the outside air temperature correction circuit 23 detects the sawtooth wave V generated by the sawtooth wave generation circuit 14 at a high outside air temperature.
The peak value of 2 is increased, for example, from the state of FIG. 4 to the state of FIG. As a result, the internal temperature at which the output V1 of the differential amplifier circuit 8 reaches the peak value of the sawtooth wave V2 decreases, so that in summer, the so-called overshoot in which the internal temperature greatly exceeds the set temperature is effectively prevented. Can be resolved.

FIG. 8 is a block diagram showing a control device 1 according to another embodiment of the present invention shown in FIG. The same reference numerals as those in FIG. 6 denote the same parts. In this case, the outside air temperature detecting means is constituted by a resistance temperature sensor (thermistor or the like) 56 mounted on the substrate 51 instead of the outside air temperature sensor as described above. It is connected to the correction circuit 23.

At this time, since the outside air is similarly circulated through the ventilation holes 53 in the machine room 52, the resistance temperature measuring body 56 on the substrate 51 can also accurately detect the outside air temperature. Further, according to this configuration, circuit components such as a lead wire and a connector can be eliminated as compared with the case where the outside air temperature sensor 13 is attached to the outer surface of the box body 44, and cost can be reduced.

Although the embodiment has been described with reference to an example of a storage cabinet for transporting food, the present invention is not limited to this, and it is needless to say that the present invention is also effective for a storage cabinet or the like.

[0045]

As described in detail above, according to the first aspect of the present invention, the differential amplifier means for generating an output proportional to the difference between the internal temperature detected by the internal temperature detecting means and the set temperature, A sawtooth wave generating means for generating a wave, and based on an output of a comparing means for comparing an output of the differential amplifying means and an output of the sawtooth wave generating means, ON / OFF control of energization of the heater by the switching means. Since the outside air temperature detecting means is provided and the outside air temperature correcting means for changing the amplification factor of the differential amplifying means based on the output of the outside air temperature detecting means is provided, according to the outside air temperature at which the refrigerator is installed. The proportional control start temperature can be changed.

That is, the above-mentioned outside air temperature correction means raises the proportional control start temperature under a low outside air temperature and conversely lowers the proportional control start temperature under a high outside air temperature.
The internal temperature converges at a temperature lower than the set temperature, or
The so-called overshoot, which greatly exceeds the set temperature, can be effectively eliminated, and stable temperature control can be realized.

According to the second aspect of the present invention, in addition to the above, the outside air temperature detecting means is constituted by a resistance thermometer mounted on the substrate, and the substrate is mounted on a part of the box through which the outside air flows. Therefore, it is possible to reduce costs by reducing the number of circuit components while realizing stable control. According to the third aspect of the present invention, the differential amplifying means for generating an output proportional to the difference between the internal temperature detected by the internal temperature detecting means and the set temperature, and the sawtooth wave generating means for generating the sawtooth wave And based on the output of the comparing means for comparing the output of the differential amplifying means and the output of the sawtooth wave generating means, energizing the heater by the switching means.
In the N-OFF control, an outside air temperature detecting means is provided, and an outside air temperature correcting means for changing the peak value of the sawtooth wave generating means based on the output of the outside air temperature detecting means is provided. Thus, the proportional control start temperature can be changed according to the outside air temperature.

That is, the above-mentioned outside air temperature correction means raises the proportional control start temperature under a low outside air temperature and conversely lowers the proportional control start temperature under a high outside air temperature.
The internal temperature converges at a temperature lower than the set temperature, or
The so-called overshoot, which greatly exceeds the set temperature, can be effectively eliminated, and stable temperature control can be realized.

According to the invention of claim 4, in addition to the above, the outside air temperature detecting means is constituted by a resistance thermometer mounted on the substrate, and the substrate is mounted on a part of the box through which the outside air flows. Therefore, it is possible to reduce costs by reducing the number of circuit components while realizing stable control.

[Brief description of the drawings]

FIG. 1 is a perspective view of a storage cabinet to which a control device of the present invention is applied.

FIG. 2 is a schematic sectional view of the storage in FIG. 1;

FIG. 3 is a block diagram of an electric circuit of the control device of the present invention.

FIG. 4 is a diagram illustrating outputs of a differential amplifier circuit and a sawtooth wave generation circuit for explaining proportional control of a heater.

FIG. 5 is a block diagram of an electric circuit of a control device according to another embodiment of the present invention.

FIG. 6 is a block diagram of an electric circuit of another control device of the present invention.

FIG. 7 is a diagram illustrating outputs of a differential amplifier circuit and a sawtooth wave generation circuit for explaining another proportional control of the heater.

FIG. 8 is a block diagram of an electric circuit of a control device according to another embodiment of the invention shown in FIG. 6;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Control device 4 Proportional control circuit 6 Interior sensor 8 Differential amplifier circuit 12 Comparison circuit 13 Outside temperature sensor 14 Sawtooth wave generation circuit 16 SSR 17 Heater 18 Transistor 23 Outside temperature correction circuit 40 Hot storage 44 Box 46 Interior 51 Substrate 52 Machine room 53 Vent

Claims (4)

[Claims] 1. A temperature control device configured to heat the inside of a refrigerator formed in a box body by a heater, wherein a temperature inside the refrigerator detecting means for detecting a temperature in the refrigerator, and an outside air temperature detecting device detecting an outside air temperature. Control means for controlling energization to the heater based on the output of each temperature detection means, wherein the control means is proportional to a difference between the inside temperature detected by the inside temperature detection means and the set temperature. A differential amplifying means for generating an output; an outside air temperature correcting means for changing an amplification factor of the differential amplifying means based on an output of the outside air temperature detecting means; a sawtooth wave generating means for generating a sawtooth wave; A storage unit comprising: a comparison unit that compares the outputs of the dynamic amplification unit and the sawtooth wave generation unit; and a switching unit that controls ON / OFF of energization of the heater based on the output of the comparison unit. Warehouse Control device. 2. The outside air temperature detecting means comprises a resistance thermometer mounted on a substrate, and said substrate is mounted on a part of a box through which outside air flows. Control device for the refrigerator. 3. A warm storage which is configured by heating the inside of a refrigerator constituted by a box with a heater, wherein a temperature inside the refrigerator detecting means for detecting a temperature in the refrigerator, and an outside air temperature detecting means for detecting an outside air temperature. Control means for controlling energization to the heater based on the output of each temperature detection means, wherein the control means is proportional to a difference between the inside temperature detected by the inside temperature detection means and the set temperature. A differential amplifying means for generating an output, a sawtooth wave generating means for generating a sawtooth wave, an outside air temperature correcting means for changing a peak value of the sawtooth wave generating means based on an output of the outside air temperature detecting means, and the difference A temperature comparing means for comparing the output of the dynamic amplifying means with the output of the sawtooth wave generating means, and a switching means for controlling ON / OFF of energization of the heater based on the output of the comparing means. Inventory control device. 4. The apparatus according to claim 3, wherein said outside air temperature detecting means is constituted by a resistance thermometer mounted on a substrate, and said substrate is mounted on a part of a box through which outside air flows. Control device for the refrigerator.