JPH0776664B2 - Controller for food preservation in the chilled partial area - Google Patents

Description

TECHNICAL FIELD The present invention relates to a food storage control device for storing a water-containing food in a chilled partial temperature range.

[Conventional technology]

Cold storage is widely used as a method for holding food.
This low-temperature storage includes refrigerated storage and frozen storage. Refrigerated storage stores food by keeping the temperature of the refrigerator at 3 ° C to 5 ° C. In frozen storage, the temperature in the freezer is approximately -18.
The food is stored by controlling at ℃.

However, refrigerated storage has a problem that it is difficult to maintain a stable temperature and food cannot be stored for a long period of time.Frozen storage has an excessively low internal temperature, and the water content in the food is completely frozen. Therefore, there is a problem that the cells of the food are destroyed, the original state is not completely restored even when the food is thawed, and body fluid flows out to deteriorate the quality.

Recently, a food preservation method by chilled control and partial control, which eliminates the disadvantages of refrigerated storage and frozen storage and takes advantage of the respective advantages of refrigerated storage and frozen storage, is being adopted. The chilled control method stores the temperature in the refrigerator at around 0 ° C. and is suitable for storing foods such as yogurt and tofu that are not suitable for freezing. The partial control method controls the temperature in the refrigerator. It is stored at a temperature around -3 ° C and is suitable for storing freeze-dried foods such as meat and fresh fish. By performing such chilled / partial control, food can be stored for a relatively long time while maintaining freshness and quality.

This kind of chilled partial control is usually by arranging temperature sensors such as thermistors and thermocouples at multiple points inside the refrigerator, and based on the temperature detection signals from these temperature seans,
The temperature in the refrigerator is controlled to a chilled or partial set temperature.

[Problems to be Solved by the Invention]

However, in the method of storing food by detecting the temperature in the refrigerator, there is a lag between the temperature in the refrigerator and the temperature of the food actually stored, and the difference in temperature is the type and weight of the stored food and the water content. Since it depends on the state and heat transfer conductivity, it is difficult to store the food temperature at the chilled or partial set temperature because the temperature inside the food cannot be known only by detecting the temperature inside the refrigerator. It was

The present invention has been made in order to solve the above-mentioned conventional problems, and the object thereof is to preserve food in the chilled / partial region in which the food as the object to be detected can be accurately preserved by the set temperature of the chilled or partial. It is to provide the control device.

[Means for Solving the Problems]

The present invention is configured as follows to achieve the above object. That is, the device of the present invention is, firstly, an electrode detection unit for detecting vector impedance arranged in a storage provided with a heat source device capable of heating and cooling,
A vector impedance detector that receives a detection signal corresponding to the temperature change of the detection target placed on the upper side of the electrode detection unit from the electrode detection unit to detect the vector impedance of the detection target, and based on the detection signal of the vector impedance And a control unit for controlling the operation of the heat source device to keep the detected object at the set temperature of the chilled partial region. Further, the device of the present invention is secondly, the device of the present invention. In addition to the electrode detection unit and the vector impedance detector for detecting the vector impedance, a temperature sensor for detecting the temperature in the storage, a temperature detection signal of the temperature sensor and a vector impedance detection signal from the vector impedance detector are provided. It is equipped with a switch for extracting in time series, and is output in time series from this switch. It controls the operation of the heat source device based on the-vector impedance detection signal chilled the object to be detected
It is configured to have a control unit that keeps the temperature in the partial region at a set temperature and confirms the temperature inside the refrigerator by a temperature detection signal.

[Action]

In the present invention, the moisture-containing food is placed on the upper side of the electrode detection unit in the storage as a detection target, and when the temperature inside the storage is lowered by driving the heat source device, the dielectric constant and conductivity in the detection target are increased. The changes in the vector impedance that change and include these elements are detected by the electrode detector and these detection signals are applied to the vector impedance detector. The vector impedance detector constantly obtains the vector impedance based on the detection signal, and applies the vector impedance detection signal to the control unit. The control unit controls the operation of the heat source device by taking in the information of the detection signal of the vector impedance, and maintains the temperature chilled or partial control temperature of the detected object in the storage. Especially 0
Since the vector impedance remarkably changes in the vicinity of ° C, the chilled control can be reliably performed, and the temperature in the partial region of the vector impedance can be detected with reference to the changed temperature to hold the detected object in the partial state.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows the configuration of an embodiment of the device of the present invention.
In the figure, the storage 1 is provided with an opening / closing door (not shown), and the food can be taken in and out by opening and closing the door.

A heat exchanger 2 and a heater 3 are provided in the storage 1, the heat exchanger 2 is connected to a refrigerator 4, and the inside of the refrigerator is cooled by passing a refrigerant supplied from the refrigerator 4. Further, the heater 3 raises the temperature of the inside of the refrigerator by its heat generation, and the operations of the heater 3 and the refrigerator 4 are controlled by the control unit 5.

Further, a holding table 6 is provided inside the refrigerator. An electrode detection unit 7 is disposed on the upper side of the holding table 6, and a moisture-containing food such as meat storage, fresh fish, vegetables, etc., in this embodiment, meat storage is detected by directly contacting the upper side of the electrode detection unit 7. It is left standing as the body 8. A temperature sensor 13 including a thermistor and a thermocouple for detecting and confirming the temperature inside the storage 1 is further arranged in the storage 1.

The electrode detection unit 7 can be formed in various forms, one example of which is shown in FIG. The electrode detection section 7 is formed by forming a detection electrode 10 and a ground electrode 11 on a surface of a substrate 9 with a minute gap 12 therebetween, and the detected body 8 is placed over the detection electrode 10 and the ground electrode 11. Has been done.

The vector impedance detector 14, the analog switch 16, the A / D converter 17, and the microcomputer 18 process the detection signal of the electrode detection unit 7 and control the temperature inside the refrigerator.
And the control unit 5.

The dielectric constant and the resistance value of the detected object 8 change due to the temperature change. The vector impedance detector 14 is the detection electrode.
An electric field is generated between the earth electrode 10 and the earth electrode 11, and the detection electrode
There is a power supply device for supplying a constant current between the detection electrode 10 and the earth electrode 11, an electric field is generated between the detection electrode 10 and the earth electrode 11, and the electric field is passed through the inside of the detection object 8.
Of the sensing electrode according to the change of the whole dielectric constant including the inside and the surface of the
The change in capacitance between the ground electrode 10 and the ground electrode 11 and the change in resistance of the constant current flowing between the detection electrode 10 and the ground electrode via the detected object 8 are detected as a combined vector impedance, and the detection result is detected as a voltage. Output by value. FIG. 5 shows the relationship between the temperature change of the detected object 8 and the vector impedance. The vertical axis of FIG. 5 shows the vector impedance, the oblique horizontal axis shows the oscillation frequency of electric field generation, and the horizontal axis shows the temperature of the detected body 8. According to this figure, the vector impedance changes abruptly discontinuously at a position where the temperature is 0 ° C., which hardly depends on the oscillation frequency. This abrupt change point strictly indicates the point of 0 ° C., which means that the detection of the chilled temperature control point can be detected with high accuracy and high sensitivity. In the region where the temperature is lower than 0 ° C, the change mode of the vector impedance depending on the temperature varies depending on the oscillation frequency, but the oscillation frequency is selected, and the characteristic graph in which the vector impedance also changes continuously due to the continuous change in temperature is obtained. To be By using this graph, a one-to-one relationship between the vector impedance and the temperature can be obtained, and by detecting the vector impedance, the temperature of the detected object can be obtained, and the detected object can be maintained and controlled in the partial state.

The temperature detector 15 converts a temperature detection signal obtained by the temperature sensor 13 into a level voltage signal by a constant power supply circuit network or the like and outputs the level voltage signal to confirm the temperature in the refrigerator. The analog switch 16 switches the vector impedance detection (calculation) signal applied from the vector impedance detector 14 and the temperature detection signal applied from the temperature detector 15 by a switch, and alternately fetches them in chronological order. Add to / D converter 17. A / D converter
Reference numeral 17 is for converting an analog signal applied from the analog switch 16 into a digital signal and applying the digital signal to the microcomputer 18.

The microcomputer 18 is a microprocessor 20 in which a storage element 21, an arithmetic element 22, a display element (not shown), and the like are connected to the microprocessor 20 as required. The detected temperature of the detected object 8 is set in the microprocessor 20 for chilled / partial control. The program of the operating state of the control unit 5 is stored for saving. For example, as shown in FIG. 3, when the object to be detected is cooled from the initial state of room temperature to the set temperature T ₀ of the chilled or partial, in order to avoid damage to the object 8 to be detected, the room temperature should be kept as short as possible. From set temperature T ₀
It is desirable to quench rapidly. However, if it is overcooled too rapidly, the object 8 to be detected is completely frozen during the cooling, which causes a problem that the cells are destroyed and the quality is deteriorated. Therefore, when cooling the inside of the refrigerator, it is desirable to cool from the initial temperature state to the set temperature T ₀ of the chilled or partial as rapidly as possible in a state where cell destruction is not caused, and this preferable cooling operation state curve ( Program) is provided to the microprocessor 20.

The arithmetic element 22 performs the differential and integral operations necessary for controlling according to the program. For example, a differential operation of the change in vector impedance is performed during the cooling or heating process in the refrigerator, and the cooling or heating operation is stopped at 0 ° C where the differential value changes abruptly due to the sudden change in vector impedance, and the temperature inside the refrigerator is 0 ° C. Keep at temperature. Further, in the partial temperature control, the object to be detected can be accurately controlled by the partial temperature by performing the integral calculation of the vector impedance. That is, after detecting the temperature of 0 ° C., the temperature is cooled to the value of the vector impedance of the partial temperature, and heating and cooling are controlled so that the partial temperature maintains the value of the vector impedance. The partial temperature can be controlled. In this case, for example, an integrated value of N ₀ vector impedance values at the partial temperature control point (−3 ° C.) is given in advance in the storage element 21 as a reference integrated value, and the reference point at 0 ° C. is detected. Each time the vector impedance for N ₀ is obtained in time series, the integrated value is calculated, and the cooling and heating are controlled in the direction in which the calculated integrated value matches the reference integrated value. The detection body can be controlled to the partial temperature. As shown in FIG. 5, the change in the vector impedance in the partial temperature region is small, and it is difficult to detect the minute temperature change with high sensitivity by the vector impedance change. However, by comparing the integrated values, the minute change in the vector impedance is clear. And by performing the integral calculation,
It is possible to improve the control accuracy of the partial temperature.
Further, the storage element 21 also stores, for example, the detected temperature inside the refrigerator added from the temperature detector 15 and the control history of the cooling operation curve given by the program. Based on the above stored information,
The microprocessor 20 corrects the program and exerts a learning function to create a more suitable cooling operation curve in the refrigerator, taking into consideration the history such as when the door in the refrigerator is opened midway.

The microprocessor 20 controls the switching time of the analog switch 16 and also A / D converter 17
A vector impedance detection signal added from the above is taken in time series, and a control signal is added to the control unit 5 according to a program so that the temperature inside the refrigerator follows the optimum cooling temperature curve. The control unit 5 controls the operations of the refrigerator 4 and the heater 3 in accordance with the control signal applied from the microprocessor 20 to keep the detected object 8 at a desired control set temperature T ₀ of chilled or partial. The microprocessor 20 confirms from the temperature detection signal from the temperature detector 15 whether the inside of the refrigerator is under chilled or partial control.

According to the present embodiment, as described above, the temperature change of the detected object 8 is directly detected as the change of the vector impedance, and the detection result is incorporated to control the temperature inside the storage 1. Compared to the method in which the temperature inside the refrigerator is indirectly detected only by the temperature sensor and the temperature is controlled as in the device described above, it is possible to reduce the deviation of the temperature of the detected object from the set temperature. The accuracy of chilled or partial control of the detection object can be improved, and food can be stored in a state of high freshness and high quality. Moreover, when detecting the vector impedance, the electric field between the electrodes 10 and 11 enters the inside of the object to be detected 8. Therefore, comprehensive temperature information from the surface of the object to be detected 8 to the inside can be taken in, and the temperature control can be performed. The certainty can be further increased.

Further, since the vector impedance causes a rapid change at 0 ° C. of the object to be detected, it is possible to detect a sudden change in the vector impedance and use this as a reference point at 0 ° C. of the object to make a program for cooling operation. This makes it possible to control the chilled or partial temperature more effectively.

FIG. 4 shows the results of an experiment in which partial control was performed using the apparatus of this embodiment. In this experiment, pure water with a water level of 6 cm contained in a small container was used as the object to be detected, and temperature sensors were inserted at the bottom of the container, the middle part of the pure water, and the side surface of the pure water. The temperature inside the storage obtained by the sensor 13 and the temperature at each position of pure water are monitored with respect to the elapsed cooling time of the storage 1, and this is plotted on the vertical axis. According to the results of this experiment, after the temperature in the refrigerator is rapidly cooled to the set temperature for partial control,
The detected object gradually approaches the set temperature, and the elapsed cooling time is 3
At a position almost before time, the detected object enters the partial section of the pure water state from the state of pure water, and the temperature of each part of the detected object is cooled and stored with little variation,
We were able to confirm that it had very good controllability.

The present invention is not limited to the above embodiments, and various modes of implementation can be adopted. For example, in the above embodiment,
Although the output signal of the A / D converter 17 is guided to the microcomputer 18, if the control unit 5 includes a circuit such as the microprocessor 20, the signal from the A / D converter 17 is sent to the control unit. 5, the operation control of the refrigerator 4 and the heater 3 can be performed.

In the above embodiment, the A / D converter 17 converts the analog signal into a digital signal for signal processing.
The A / D converter 17 may be omitted and signal processing may be performed using an analog signal. In this case, for example, using the analog voltage level obtained from the analog switch 16,
The control unit 5 can perform on / off control depending on whether or not this level exceeds the threshold potential.

〔The invention's effect〕

Since the present invention is configured to directly detect the vector impedance of the object to be detected and perform the chilled or partial control of the storage using the information of the detection signal of the vector impedance, the water content stored in the storage It is possible to cool and store system foods without significantly deviating from the chilled or partial control set temperature.
This makes it possible to stably maintain the freshness and quality of the stored food.

Further, since the vector impedance of the object to be detected is directly detected and the temperature is controlled by using the information, the temperature of the object to be detected can be controlled with almost no deviation from the set temperature as described above. Since it is possible to easily provide a chilled partial control device that has no waste of control energy and has an energy saving effect, and has a simple device configuration, the excellent device of the present invention is provided at low cost. It becomes possible.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, and FIG.
FIG. 4 is a plan view showing an example of an electrode detection unit constituting the same embodiment, FIG. 3 is an explanatory view showing the operating state of the control unit with respect to the temperature inside the refrigerator, and FIG. 4 is pure water using the apparatus of the same embodiment. FIG. 5 is a graph showing the experimental result of the partial control, and FIG. 5 is a graph showing the relationship between the temperature of the object to be detected and the vector impedance. 1 ... storage, 2 ... heat exchanger, 3 ... heater, 4 ...
Refrigerator, 5 ... Control unit, 6 ... Holding stand, 7 ... Electrode detection part, 8 ... Meat storage (object to be detected), 9 ... Lid plate, 10 ...
… Detection electrode, 11 …… Ground electrode, 12 …… Small gap, 13…
… Temperature sensor, 14… Vector impedance detector,
15 …… Temperature detector, 16 …… Analog switch, 17 …… A /
D converter, 18 ... Microcomputer, 20 ... Microprocessor, 21 ... Memory element, 22 ... Operation element.

Claims (2)

[Claims] 1. An electrode detection unit for detecting vector impedance, which is arranged in a storage compartment equipped with a heat source device capable of heating and cooling, and an object to be detected placed above the electrode detection unit. A vector impedance detector that receives a detection signal corresponding to a temperature change from the electrode detection unit to detect the vector impedance of the object to be detected, and an object to be detected by controlling the operation of the heat source device based on the detection signal of the vector impedance. A control device for storing food in a chilled partial area, which has a control unit for maintaining a set temperature in the chilled partial area. 2. An electrode detection unit for detecting vector impedance, which is arranged in a storage compartment equipped with a heat source device capable of heating and cooling, and an object to be detected placed above the electrode detection unit. A vector impedance detector that receives a detection signal corresponding to a temperature change from the electrode detection unit to detect the vector impedance of the object to be detected, a temperature sensor that detects the temperature in the storage, a temperature detection signal of the temperature sensor, and the vector A switch for taking out the vector impedance detection signal from the impedance detector in time series, and controlling the operation of the heat source device based on the vector impedance detection signal output in time series from this switch to chill the detected object. A chilled unit having a control unit for maintaining the temperature set in the partial region and confirming the temperature inside the refrigerator by a temperature detection signal. Controller of food preservation in the partial area.