JPS60122874A - Method and device for controlling temperature of low-temperature insulating 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 The present invention can maintain a constant temperature inside a cold showcase without being affected by changes in outside temperature.

Moreover, the present invention relates to a temperature control system for a cold storage showcase that has an excellent power saving effect.

Conventionally, temperature control of cold storage showcases for foods used in retail stores, etc., has been done by setting a constant target temperature, and when the target temperature exceeds one, the refrigerator is operated to cool it down, and when the temperature falls below the target temperature, the refrigerator is turned off. Stop and let the temperature rise. This was done using a so-called one-point setting method, but in this method, the refrigerator was frequently turned on and off, resulting in an enormous amount of power consumption due to the influence of inrush current at the start of the second operation.

Therefore, in order to save power, a method is used in which a timer is installed and the refrigerator is operated at regular time intervals to control the temperature inside the showcase.

However, in this method, the refrigerator is turned on.

Since the OFF time is set regardless of the outside temperature, the temperature inside the showcase will be affected by the outside temperature, and the temperature inside the case will change depending on the season, time of day and night, etc. It was difficult to maintain freshness.

This invention was made in order to eliminate the above-mentioned drawbacks, and sets an upper limit temperature and a lower limit temperature, and when the temperature inside the showcase reaches the upper limit temperature, the refrigerator is turned on, and when it reaches the lower limit temperature, it is turned off. do. In addition to adopting a so-called two-point setting control method, it detects the outside air temperature, and when the outside air temperature rises above a certain temperature, it automatically lowers the second temperature limit. When the temperature drops below the upper limit temperature, the refrigerator switches from two-point setting control to timer operation, making it possible to maintain the temperature inside the refrigerator showcase at a constant level without being affected by the outside temperature, while also saving energy. DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings and an excellent temperature control method for a cold storage showcase.

FIG. 1 is a block diagram showing one embodiment of the present invention. In the figure, 10 is a control circuit for performing two-point setting control, and the control circuit 1o is connected to a case internal temperature sensor 11. @
1 upper limit temperature setter 12, lower limit temperature setter 13. Second upper limit temperature setter 14. Switching circuit 15. It is constituted by comparators 16 and 17.

The case internal temperature detector 11 detects the temperature inside the showcase, and uses a thermistor.

The first upper limit temperature setter 12 sets the first upper limit temperature, which is the timing to turn on the refrigerator TA50, and the lower limit temperature setter 13 sets the lower limit temperature, which is the timing to turn off the refrigerator 5°. Temperature setting using a temperature setting device is as follows.

It is determined according to the product by taking into account the temperature range required to maintain the quality of the products displayed in the showcase.
The temperature inside the showcase repeatedly rises and falls within the set range.

The second upper limit temperature setting device 14 similarly sets the second upper limit temperature as the timing for turning on the refrigerator 5°, but the second upper limit temperature is set lower than the first upper limit temperature. The second upper limit temperature setting device 14 turns the refrigerator 5o on when the outside air temperature exceeds the environmental upper limit temperature set to 25°C, for example.
This serves to forcibly lower the timing of the N temperature from the first upper limit temperature to the second upper limit temperature, strengthen cooling, and prevent the temperature of the products in the showcase from rising.

The switching circuit 15 switches the connection between the first upper limit temperature setter 12 or the second upper limit temperature setter 14 and the comparator 1G, and is constituted by the relay. At that time, the contact A and the contact A of the relay are in contact to connect the first upper limit temperature setting device 12 and the comparator 16, but when a switching signal is generated from the switching signal generation circuit 20, which will be described later, the contact C side is connected. The configuration is such that the second upper limit temperature setting device 14 and the comparator 16 are connected.

The comparator 16 compares the case internal temperature detected by the case internal temperature detector 11 with the first upper limit temperature setter 12 or the second upper limit temperature setter 12.
Comparing the first upper limit temperature or the second upper limit temperature set by the upper limit temperature setting device 14, when the case internal temperature reaches the first lower limit temperature or the second upper limit temperature, the refrigerator 50 is operated. The comparator 17 outputs a signal to the drive circuit 40, and the comparator 17 compares the temperature inside the case with the lower limit temperature set by the lower limit temperature setter 13, and drives a stop signal when the temperature inside the case reaches the lower limit temperature. It is output to the circuit 40.

The switching signal generation circuit 20 includes an outside air temperature detector 21. which detects outside air temperature. Environmental upper limit temperature setting device 22 for setting the environmental upper limit temperature. and outside temperature.

a comparator 2 that compares the ambient temperature with the upper limit environmental temperature and outputs a switching signal to the switching circuit 5 when the outside air temperature exceeds the upper ambient temperature;
3.

Furthermore, the outside air temperature detector 21 is configured using a thermistor.

30, when the outside temperature falls below the first upper limit temperature,
This is a timer signal generation circuit for switching the refrigerator 50 to timer operation, and the outside air temperature detector 21. First upper limit temperature setter 12. A comparator that compares the outside air temperature detected by the outside air temperature detector 21 and the first upper limit temperature set by the first upper limit temperature setting device 12 and generates an output when the outside air temperature falls below the first upper limit temperature. 31° The comparator 31
The timer circuit 32 receives the output of the timer circuit 32 and outputs ON and OFF signals at fixed time intervals.

The reason for this timer operation is that as long as the outside air temperature is lower than the first upper limit temperature, the comparator 16 will not output an activation signal, and if left as is, the temperature inside the case will rise and the product temperature will also rise. This is to prevent this from happening.

Next, the operation of this embodiment will be described below at an outside temperature of θ1. First upper limit temperature θ
2. Lower limit temperature θ3. 2nd upper limit temperature θ4゜Environmental upper limit temperature θ
5. This will be explained with reference to FIG. 2 (al and FIG. 2 fb showing the ON/OFF operation of the refrigerator 51) which shows the relationship between the temperature inside the showcase θ6° and the product temperature θ7.

First, the first upper limit temperature θ2. Lower limit temperature θ3. Second upper limit temperature θ
4. The environmental upper limit temperature θ5 is set using each setting device, and the refrigerator 50 is powered on. If the case internal temperature θ6 detected by the case internal temperature detector 11 is higher than the first upper limit temperature θ2, an activation signal is output from the comparator 16 and the refrigerator 50 is activated. The temperature θ6 inside the showcase decreases due to the operation of the refrigerator 50, but when the temperature θ6 inside the case reaches the lower limit temperature θ3, the comparator 17 outputs a stop signal.

The refrigerator 50 stops, and the temperature θ6 inside the showcase increases. When the case internal temperature θ6 reaches the first upper limit temperature θ2,
An activation signal is output from the comparator 16, the refrigerator 50 is restarted, and the above operation is repeated (T1 period). Within the range of change of the case internal temperature θ6, the product temperature θ7 follows the case internal temperature θ6. It remains almost constant.

Next, when the outside air temperature θ1 rises and exceeds the environmental upper limit temperature θ5, a switching signal is output from the comparator 23, and the switching circuit 1
5 relay contact switches.

The second upper limit temperature setting device 14 and the comparator 16 are connected.

As a result, the timing for turning on the refrigerator 50 decreases from the first upper limit temperature θ2 to the second upper limit temperature θ4, and the refrigerator 50
is ON and O between the second upper limit temperature θ4 and the lower limit temperature θ3
FF is repeated (T2 period), so cooling is strengthened against a sudden rise in temperature inside the showcase.
The product temperature θ7 is maintained approximately constant.

When the outside air temperature θ1 falls below the environmental upper limit temperature θ5 again,
The switching signal of the comparator 23 disappears, the contact of the switching circuit 15 switches back to its original state, and the refrigerator 50 is turned on between the first upper limit temperature θ2 and the lower limit temperature θ3.

Repeat OFF (73 periods).

When the outside air temperature θ1 falls below the first upper limit temperature θ2, a small force is generated from the comparator 31, and this output causes the timer circuit 32 to generate a timer signal, and the refrigerator 50 switches to timer operation (period T4). Since the temperature θ1 is lower than the first upper limit temperature θ2, the case internal temperature θ6 does not rise above the upper limit temperature 62 even if the timer operation is performed, and the product temperature θ7 is maintained almost constant.

As explained above, the present invention performs temperature control using a two-point setting method by setting an upper limit temperature and a lower limit temperature, and
When the outside air temperature rises above a predetermined temperature, the upper limit temperature is forcibly lowered to strengthen cooling, and when the outside air temperature falls below the upper limit temperature, the refrigerator is operated on a timer.

Product temperature can be maintained almost constant regardless of outside temperature changes due to seasonal, hourly, store environment, etc., and product freshness can be maintained for a long period of time. Moreover, by adopting a two-point setting method for temperature control, the number of intermittent cycles of the refrigerator is drastically reduced.

It has a significant power saving effect compared to the conventional single point setting.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing one embodiment of the present invention. Figure 2 (al is a diagram showing the change characteristics of outside air temperature, temperature inside the showcase, and product temperature, Figure 2 + b) is when the refrigerator is turned on,
It is a figure showing OFF operation. 10--Control circuit 11--Case internal temperature detector 12--First upper limit temperature setter 13--Lower limit temperature setter 14--Second upper limit temperature setter 15--Switch circuit 20 -・-Switching signal generation circuit 21...-Outside temperature detector 22-Environmental upper limit temperature setter 16, 17.23.30-m-Comparator 30--Timer signal generation circuit 32--Timer circuit 4〇 - Drive circuit 50 - Refrigerator. Patent Applicant Hakko Electric Manufacturing Co., Ltd. Procedural Amendment (own ship March 12, 1981 Patent Application No. 231196 2-Name of invention Temperature control method and device for cold storage showcase 3-Person making the amendment) Relationship to the incident Patent applicant address 3055 Oaza Tokura, Togura-cho, Hanishina-gun, Nagano Name
Osamu Sakai, Representative of Tsumeko Electric Manufacturing Co., Ltd. - 4-Agent ■151 Application 6, Contents of amendment (1) On the right side of the title of the patent application, there is a message that says "Patent application pursuant to the proviso to Article 38 of the Patent Law". Write the characters. (2. The number of inventions stated in the claims is amended to 2.

Claims (1)

[Claims] (11 Set the upper limit temperature and lower limit temperature in the cold storage showcase, and when the temperature inside the case reaches the upper limit temperature, the refrigerator is operated, and when the lower limit temperature is reached, the refrigerator is stopped, and the outside air temperature reaches the predetermined temperature. If it exceeds, lower the upper limit temperature,
Temperature control method for a cold storage showcase characterized by switching the refrigerator to timer operation when the outside air temperature drops below the upper limit temperature (2) Setting the upper limit temperature and lower limit temperature in the cold storage showcase A setting device, a drive circuit that operates the refrigerator when the temperature inside the case reaches the upper limit temperature and stops the refrigerator when it reaches the lower limit temperature, and a drive circuit that operates the refrigerator to operate the refrigerator when the outside temperature exceeds a predetermined temperature. 1. A temperature control device for a cold storage showcase, comprising a switching circuit that switches to a lower upper limit temperature, and a timer that operates a refrigerator intermittently when the outside air temperature falls below the upper limit temperature.