JP2023149545A - temperature control system - Google Patents

Abstract

To solve the problem that when a thermocouple is used by being connected to a controller, since a temperature sensing element for compensating a reference contact is built in a housing of the controller, an error occurs in the detected temperature due to heat generation from an internal power supply circuit or an electronic component, and there is a case of not being adaptable to the standard requiring highly accurate temperature control.SOLUTION: Provided is a temperature control system capable of highly accurate temperature control without depending on the accuracy of temperature compensation of a controller body by highly accurately converting a measured value from a thermocouple into the digital temperature data by a temperature converter. Further, by converting the temperature data into the digital temperature data, transmission of the temperature data to another device is facilitated.SELECTED DRAWING: Figure 1

Description

The present invention relates to a temperature control system that calculates control parameters based on measured values of thermocouples and controls the temperature of a controlled object.

Thermocouples are made by bonding two metals with different thermoelectric powers, and when the two junctions are brought to different temperatures, a current flows in a fixed direction and a thermoelectromotive force is generated (Seebeck effect). Measure. When measuring temperature using a thermocouple, the temperature of the reference junction (cold junction) to which the thermocouple is connected is detected by a temperature sensing element such as a diode, and the reference junction is always kept at 0°C. Compensation is performed electrically.

When a thermocouple is connected to a controller, the temperature-sensing element used to compensate for the reference junction is built into the controller's housing, so heat generated from the internal power supply circuit and electronic components may cause the detected temperature to rise. There was a problem that an error occurred.

Therefore, a technique has been disclosed in which a protective box surrounding the terminal portion and the temperature sensing element is provided to suppress the influence of heat from inside the controller on the input terminal and the temperature sensing element.

JP 2009-236681

However, if the input accuracy of the controller is ±0.1% and the R thermocouple is used at a measurement temperature of 1100°C, the temperature accuracy will be ±1.1°C, which does not meet the ±1.0°C requirement of class 1. . This controller cannot be used with advanced high temperature measurement standards for aerospace materials such as AMS (Aerospace Material Specification) 2750.

Therefore, by providing a temperature sensing element for compensating the reference junction outside the controller, it is prevented from being influenced by the inside of the controller. Furthermore, the temperature value measured by the thermocouple is output as digital data.

In order to achieve the above object, the temperature control system according to claim 1 of the present invention includes:
a temperature measurement unit that measures the temperature of the controlled object as analog temperature information;
an acquisition unit that acquires analog temperature information from the temperature measurement unit;
a temperature compensation section that determines the temperature of the reference junction;
a conversion unit that converts into digital temperature information based on the analog temperature information acquired by the acquisition unit and the temperature of the temperature compensation unit;
an output section that outputs digital temperature information to the control section;
a control unit that controls the temperature of the controlled object based on the digital temperature information output from the output unit;
It is characterized by consisting of.

The temperature control system according to claim 2 of the present invention is characterized in that the temperature measuring section is a thermocouple.

The temperature control system according to a third aspect of the present invention is characterized in that a data transmitting/receiving device is disposed between the converting section and the control section.

The present invention provides a temperature control system that enables highly accurate temperature control without depending on the accuracy of temperature compensation of the controller body.

A diagram showing an example of the configuration of the temperature control system of Example 1 Flow diagram showing the process flow of the temperature control system of Example 1 Conceptual diagram showing an example of the configuration of the temperature control system of Example 2 Example of attaching a temperature converter to a controller Example of incorporating a temperature converter as a controller module Comparison of temperature control with a controller alone and temperature control with a controller and temperature converter connected

Embodiments of the present invention will be described below with reference to the drawings. Note that the present invention is not limited to these embodiments in any way, and may be implemented in various forms without departing from the spirit thereof.

<Example 1>
<Functional configuration>
FIG. 1 shows a first embodiment and configuration of the present invention. The temperature control system includes a temperature measuring section 1100, a controlled object 1200, a temperature converter 1300, and a controller 1400.

A controlled object 1200 is a device that heats a workpiece or maintains the temperature at a predetermined temperature, and includes a control circuit 1201 and a temperature control device 1202. The temperature control device 1202 can be a heater, a lamp, a cooling fan, a water cooling device, or the like, depending on the purpose.

The temperature measurement unit 1100 is a temperature sensor that is installed inside the controlled object 1200 and measures the temperature inside the controlled object. Specifically, a thermocouple or a resistance temperature detector is used.

When the temperature measurement unit is a thermocouple, the temperature converter 1300 includes an acquisition unit 1301 that acquires analog data sent from the temperature measurement unit, a conversion unit 1302 that converts analog temperature data into digital temperature data, and a reference to the conversion unit. It has a temperature compensation section 1303 that provides contact temperature, and an output section 1304 that outputs the digital temperature data converted to digital data to the outside.

When the temperature measurement unit is a resistance temperature detector, the measurement value obtained by the acquisition unit 1301 is converted into digital temperature data by the conversion unit 1302 without using the reference junction temperature from the temperature compensation unit 1303, and the output unit 1304 converts the measured value obtained by the acquisition unit 1301 into digital temperature data. It is possible to send it to the outside from there.

The control unit 1400 includes an input unit 1401 that receives digital temperature data, a calculation unit 1402 that uses the digital temperature data as an input value to calculate control parameters of a controlled object, and an output unit 1403 that outputs the calculated control parameters to the outside. A controller is used for the control section. In addition to controllers that operate independently, modular controllers can also be used in which modules can be added to increase the number of connection terminals.

<Processing flow>
FIG. 2 is a flowchart showing the process flow of the temperature control system according to the first embodiment.

(S2101) The temperature is measured by the temperature measuring unit. When using a thermocouple, the measured value is output as analog current data.

(S2201) The output from the temperature measuring section is input to the temperature converter.

(S2202) The temperature compensation unit measures the reference junction temperature.

(S2203) The analog temperature data is converted into digital temperature data based on the temperature of the reference junction measured by the temperature compensator.

(S2204) The digital temperature data value is sent to the controller serving as the control unit. The temperature converter and controller are connected through serial communication such as RS-485. Furthermore, since digital temperature data can be handled in the same way as normal data, it can also be transmitted using various communication means such as wired LAN, wireless LAN, and mobile phone lines.

(S2301) A controller serving as a control unit receives digital temperature data.

(S2302) Control parameters are calculated based on the digital temperature data and the controller program.

(S2303) Control parameters are transmitted to the controlled object.

(S2401) The controlled object receives the control parameters calculated by the controller serving as the control unit.

(S2402) Control parameters are executed. Specifically, control circuit 1201 in FIG. 1 operates temperature control device 1202 according to control parameters.

If control is to be performed subsequently, the temperature based on the control result is measured by the temperature measuring section, and processing is performed.

<Example 2>
<Functional configuration>
FIG. 3 shows a second embodiment and configuration of the present invention. The temperature control system includes a temperature measuring section 3100, a controlled object 3200, a temperature converter 3300, a data transmitting/receiving device 3400, a control section 3500, and an upper control device 3600.

In the second embodiment as well, the analog current value measured by the temperature measurement unit 3100 is converted to digital temperature data by the temperature converter, the control unit 3500 calculates control parameters based on the digital temperature data, and the temperature control device of the controlled object 3200 The basic processing flow of operating 3202 is the same as in the first embodiment. Therefore, the temperature measurement section 3100, the controlled object 3200, the temperature converter 3300, the control section 3500, and their internal configurations are the same as in the first embodiment.

In the second embodiment, a data transmitting/receiving device 3400 is arranged between the temperature converter 3300 and the control unit 3500, and the digital temperature data transmitted from the temperature converter 3300 is transmitted to the control unit 3500, via the data transmitting/receiving device 3400. It is transmitted to the upper control device 3600. Therefore, the data transmitting/receiving device functions as an output section.

This configuration is possible because the temperature measurement data is converted into digital data and can be transmitted to an external device using the same method as normal data. In the conventional configuration, temperature data from the temperature measurement unit was sent to the controller as an analog current, so it was necessary for the controller to convert the temperature data into digital temperature data and send it to the host controller.

The upper control device 3600 is a device that manages not only the controlled object 3200 but also the entire manufacturing process, including a device (not shown) that heats parts with the controlled object and processes and assembles them in processes before and after the controlled object. be. Therefore, if the temperature measurement result of the temperature measurement unit 3100 is abnormal, or conversely, if processing in the controlled object is delayed due to an abnormality in other devices, it is possible to issue a stop command or alarm to the related devices. can.

Further, the control parameters calculated by the control unit 3500 are sent to the data transmitting/receiving device 3400, and from the data transmitting/receiving device 3400 to the control circuit 3201 of the controlled object 3200 to control the temperature control device 3202.

In both embodiments, the control unit and the controlled object can be connected via communication, so they can be placed at separate locations. On the other hand, if communication between the control unit and the controlled object is interrupted, there is a possibility that the control cannot be performed even though the heater is heating. Therefore, when the control unit and the controlled object are connected through communication, it is desirable to have a specification for forcibly stopping the controlled object or a device that issues a warning near the controlled object in response to a communication abnormality.

4 and 5 are examples in which a temperature converter and a controller are connected and integrated. FIG. 4 shows an example in which a temperature converter 4101 is connected to a controller main body 4100 like an external module. FIG. 5 is an example of adding a temperature conversion function to the controller 5100 by inserting a module 5101 having a temperature conversion function into a slot in the controller main body 5100.

FIG. 6 compares the temperature changes when the electric furnace is controlled by a controller alone and when the electric furnace is controlled by connecting a temperature converter to the controller. It can be seen that there is no difference in the temperature increase characteristics and the characteristics of maintaining a constant temperature when heating from 200° C. to 600° C. in 400 seconds.

1100 Temperature measuring section 1200 Controlled object 1300 Temperature converter 1400 Control section 3400 Data transmitting/receiving device 3600 Upper control device

Claims (3)

a temperature measurement unit that measures the temperature of the controlled object as analog temperature information;
an acquisition unit that acquires analog temperature information from the temperature measurement unit;
a temperature compensation section that determines the temperature of the reference junction;
a conversion unit that converts into digital temperature information based on the analog temperature information acquired by the acquisition unit and the temperature of the temperature compensation unit;
an output section that outputs digital temperature information to the control section;
a control unit that controls the temperature of the controlled object based on the digital temperature information output from the output unit;
A temperature control system consisting of: The temperature control system according to claim 1, wherein the temperature measuring section is a thermocouple. 3. The temperature control system according to claim 1, further comprising a data transmitting/receiving device disposed between the converter and the controller.

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