JP2020035310A - Temperature control system, temperature control method, and program - Google Patents

Abstract

To provide a temperature control system that includes an electric resistance heater and a temperature sensor mounted on an object to be heated, and controls an energization current to the heater on the basis of an output from the temperature sensor, and automatically detect and notify deterioration of the heater to a user.SOLUTION: A temperature control system determines a target power value PWtarget and a power maximum value PWmax on the basis of the value of an applied voltage V and the value of an energization current I to a heater and an operation amount MV at a first time point when an object to be heated is at a target temperature Ttarget during temperature control of the object to be heated. The temperature control system calculates a first resistance value R1 indicated by the heater at the first time point. The temperature control system sets a resistance threshold Rth for deterioration determination on the basis of the target power value PWtarget, power maximum value PWmax, and first resistance value R1. During temperature control of the object to be heated after the first time point, the temperature control system determines the current resistance value Rs indicated by the heater. The temperature control system compares the current resistance value Rs with the resistance threshold Rth and determines and notifies deterioration of the heater to the user.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a temperature control system and a temperature control method, and more specifically, includes an electric resistance heater and a temperature sensor mounted on an object to be heated, and controls a current supplied to the electric resistance heater based on an output of the temperature sensor. The present invention relates to a temperature control system and a temperature control method. The present invention also relates to a program for causing a computer to execute such a temperature control method.

  Conventionally, as this type of temperature control system, as disclosed in Patent Document 1 (Japanese Patent Application Laid-Open No. 2003-053437), for example, an electric resistance heater is provided on an object to be heated (a die for press working). A rod-shaped heater (a commercially available product in which a heating wire is covered with a heat-resistant insulator and housed in a steel pipe) and a temperature sensor for measuring the temperature of the object to be heated are mounted, and the object to be heated reaches a target temperature. As described above, there is known a device that controls a current supplied to the rod-shaped heater based on an output of the temperature sensor.

JP 2003-053437 A

  If the operation of the temperature control system is repeated or continuously continued, the heating wire constituting the electric resistance heater (rod-shaped heater) is oxidized, and the resistance value (electric resistance) indicated by the heating wire increases. , Eventually leading to disconnection. As the deterioration progresses, the current (or supply power) to the electric resistance heater becomes insufficient, and the object to be heated cannot be controlled to the target temperature.

  Conventionally, a user of the temperature control system checks the current temperature of the object to be heated, and if it does not reach the target temperature, determines that the electric resistance heater has deteriorated and replaces the electric resistance heater. are doing. Alternatively, the user manually sets a threshold value (current threshold value) for the heater disconnection alarm, and when the current supplied to the electric resistance heater falls below the threshold value, it is determined that the electric resistance heater has deteriorated. The resistance heater has been replaced.

  Here, in the method of checking the current temperature of the object to be heated, measures to be taken after the heater has been degraded, so that a product produced when the temperature of the object to be heated does not reach the target temperature becomes defective. (Or quality degradation). In the method of manually setting the threshold value (current threshold value) for the heater disconnection alarm, the threshold value to be set depends on the heat capacity, the amount of heat radiation, and the like of the object to be heated. Costly and cumbersome.

  Therefore, an object of the present invention is to provide a temperature control system as described above, which can automatically detect and report deterioration of an electric resistance heater. Another object of the present invention is to provide a temperature control method for such a temperature control system, which can automatically detect and report deterioration of an electric resistance heater. Another object of the present invention is to provide a program for causing a computer to execute such a temperature control method.

In order to solve the above problems, in a first aspect, a temperature control system according to the present disclosure includes:
A temperature control system comprising an electric resistance heater and a temperature sensor mounted on a heating object, and controlling a current supplied to the electric resistance heater based on a temperature of the heating object output by the temperature sensor,
An operation amount for controlling the object to be heated to a predetermined target temperature is created, and a current is supplied from a power supply to the electric resistance heater according to the operation amount to control the temperature of the object to be heated. A temperature control unit;
At the first time when the heating target is at the target temperature during the temperature control of the heating target, the electric resistance based on the applied voltage value, the energizing current value, and the operation amount to the electric resistance heater, A heater power calculating unit that calculates a power value supplied to the heater as a target power value, and calculates a maximum value of power that can be supplied from the power supply to the electric resistance heater;
A first resistance value calculation unit that calculates a first resistance value indicated by the electric resistance heater at the first time based on the applied voltage value and the energized current value;
A resistance threshold setting unit that sets a resistance threshold for determining whether the electric resistance heater has deteriorated based on the target power value, the power maximum value, and the first resistance value;
Calculating a current resistance value indicated by the electric resistance heater based on an applied voltage value and an energized current value to the electric resistance heater during the temperature control of the object to be heated after the first time point; Department and
A comparison determination unit that compares the current resistance value with the resistance threshold value to determine whether the electric resistance heater has deteriorated,
When it is determined that the electric resistance heater has deteriorated, an alarm unit for notifying that the electric resistance heater has deteriorated is provided.

  In the present specification, the “applied voltage value” and the “conducting current value” indicate the values (typically, effective values) of the applied voltage and the conducting current in the ON period, respectively. The “power maximum value” means a power value supplied from the power supply to the electric resistance heater when the operation amount is the maximum. During the operation of the temperature control system, the power supply (particularly, power supply voltage) is not changed unless otherwise specified.

  In the temperature control system according to the present disclosure, the temperature control unit creates an operation amount for controlling the heating target to a predetermined target temperature, and supplies a current from a power supply to the electric resistance heater according to the operation amount. To control the temperature of the object to be heated. The heater power calculator calculates the applied voltage value, the energized current value, and the operation amount of the electric resistance heater at the first time point when the heating target is at the target temperature during the temperature control of the heating target. Then, the power value supplied to the electric resistance heater is obtained as a target power value. At the same time, the heater power calculator calculates the maximum power that can be supplied from the power supply to the electric resistance heater (that is, the electric power value supplied from the power supply to the electric resistance heater when the operation amount is the maximum). Ask for. The first resistance value calculator calculates a first resistance value indicated by the electric resistance heater at the first time based on the applied voltage value and the energized current value. The resistance threshold setting unit sets a resistance threshold for determining whether or not the electric resistance heater has deteriorated, based on the target power value, the power maximum value, and the first resistance value. During the temperature control of the object to be heated after the first point in time, the current resistance value calculation unit determines the current resistance indicated by the electric resistance heater based on the applied voltage value and the energized current value to the electric resistance heater. Find the value. The comparison determination unit compares the current resistance value with the resistance threshold to determine whether the electric resistance heater has deteriorated. The alarm unit, when it is determined that the electric resistance heater has deteriorated, notifies that the electric resistance heater has deteriorated. In this manner, according to the temperature control system, it is possible to automatically detect and notify that the electric resistance heater has deteriorated. The user who has received the notification can take prompt measures such as replacing the electric resistance heater with a new one or increasing the power supply voltage. As a result, it is possible to prevent a product produced by using the temperature control system from becoming defective (or quality degradation).

In one embodiment of the temperature control system,
The resistance threshold setting unit is configured to express the target power value as PWtarget, the power maximum value as PWmax, the first resistance value as R1, and the resistance threshold as Rth, respectively.
Rth = R1 × PWmax / PWtarget
It is characterized in that the above-mentioned resistance threshold is set according to the following formula.

  In the temperature control system of this embodiment, when the operation amount is maximized, the resistance threshold Rth is appropriately set to a level at which the electric power supplied to the electric resistance heater becomes the target electric power value PWtarget ( Details will be described in the embodiment section.)

  In one embodiment of the present invention, the comparison determination unit determines that the electric resistance heater has deteriorated when the current resistance value matches the resistance threshold.

  In the temperature control system according to the embodiment, when the current resistance value matches the resistance threshold value, the power supplied to the electric resistance heater becomes the target power value when the operation amount is the maximum. Sometimes equivalent. Therefore, when the current resistance value of the electric resistance heater has increased to a practical limit, the comparing and judging unit judges that the electric resistance heater has deteriorated, and the alarming unit judges that the electric resistance heater has deteriorated. Notify what you did. Therefore, the user can use the electric resistance heater with confidence to the practical limit.

In one embodiment of the temperature control system,
When the current resistance value matches a value obtained by multiplying the resistance threshold value by a predetermined coefficient smaller than 1, the deterioration of the electric resistance heater is set to the coefficient. Judge that it is in accordance with the progress,
The alarm unit is configured to notify the deterioration of the electric resistance heater indicating the progress.

  The "predetermined coefficient smaller than 1" is defined in a range of 0 to 1, typically in a range of 0.5 to 1, and more typically in a range of 0 to 1. It is defined as a number close to 1 such as 8 or 0.9.

  In the temperature control system of this embodiment, when the comparison determination unit matches the current resistance value with a value obtained by multiplying the resistance threshold by a predetermined coefficient smaller than 1, It is determined that the deterioration of the electric resistance heater is at a rate corresponding to the coefficient. The alarm unit notifies the deterioration of the electric resistance heater indicating the progress. Therefore, the user who has received this notification can prepare to replace the electric resistance heater with a new one according to the degree of deterioration of the electric resistance heater. Alternatively, for safety, the electric resistance heater can be replaced with a new one at an early stage before the progress of deterioration of the electric resistance heater becomes 1.

  In the temperature control system according to one embodiment, the first time point is a timing immediately after the heating target is controlled to the target temperature after the temperature control unit starts controlling the temperature of the heating target. It is characterized by.

  In the temperature control system according to the embodiment, the first time point is a timing immediately after the heating target is controlled to the target temperature after the temperature control unit starts controlling the temperature of the heating target. Therefore, the resistance threshold is set at that timing. As a result, whether or not the electric resistance heater has deteriorated can be determined continuously from the timing immediately after the heating target is controlled to the target temperature. Accordingly, the period during which the deterioration of the electric resistance heater can be monitored is relatively long.

  Further, in the process of repeatedly starting and shutting down the temperature control system, the resistance threshold is updated and set at the timing of the first time every time the temperature control system is started. As a result, the accuracy of determining whether the electric resistance heater has deteriorated is increased.

  In the temperature control system of one embodiment, the timing that forms the first time point is a timing at which a trigger signal is input from outside the temperature control system.

  In the temperature control system according to the embodiment, the resistance threshold is updated and set at a timing when a user inputs a trigger signal from outside the temperature control system. As a result, user convenience is improved.

In a second aspect, a temperature control method according to the present disclosure includes:
Temperature control for a temperature control system that uses an electric resistance heater and a temperature sensor mounted on a heating object and controls a current supplied to the electric resistance heater based on the temperature of the heating object output by the temperature sensor. The method
Create an operation amount for controlling the object to be heated to a predetermined target temperature, supply a current to the electric resistance heater according to the operation amount from a power supply, and control the temperature of the object to be heated. ,
At the first time when the heating target is at the target temperature during the temperature control of the heating target, the electric resistance based on the applied voltage value, the energizing current value, and the operation amount to the electric resistance heater, The power value supplied to the heater is obtained as a target power value, and the maximum power value that can be supplied from the power supply to the electric resistance heater is obtained,
Calculating a first resistance value indicated by the electric resistance heater at the first time based on the applied voltage value and the energized current value;
The target power value, the power maximum value, and, based on the first resistance value, set a resistance threshold value for determining whether the electric resistance heater has deteriorated,
During the temperature control of the object to be heated after the first time point, a current resistance value indicated by the electric resistance heater is obtained based on an applied voltage value and an energized current value to the electric resistance heater,
Comparing the current resistance value with the resistance threshold value to determine whether the electric resistance heater has deteriorated,
When it is determined that the electric resistance heater has deteriorated, it is notified that the electric resistance heater has deteriorated.

  According to the temperature control method of the present disclosure, the deterioration of the electric resistance heater can be automatically detected and reported. The user who has received the notification can take prompt measures such as replacing the electric resistance heater with a new one or increasing the power supply voltage. As a result, it is possible to prevent a product produced by using the temperature control system from becoming defective (or quality degradation).

In a third aspect, a temperature control system of the present disclosure includes:
A temperature control system comprising an electric resistance heater and a temperature sensor mounted on a heating object, and controlling a current supplied to the electric resistance heater based on a temperature of the heating object output by the temperature sensor,
An operation amount for controlling the object to be heated to a predetermined target temperature is created, and a current is supplied from a power supply to the electric resistance heater according to the operation amount to control the temperature of the object to be heated. A temperature control unit;
At the first time when the heating target is at the target temperature during the temperature control of the heating target, the electric resistance based on the applied voltage value, the energizing current value, and the operation amount to the electric resistance heater, A heater power calculating unit that calculates a power value supplied to the heater as a target power value, and calculates a maximum value of power that can be supplied from the power supply to the electric resistance heater;
A current threshold value setting unit that sets a current threshold value for determining whether the electric resistance heater has deteriorated based on the target electric power value, the electric power maximum value, and the energizing current value at the first time point. When,
During the temperature control of the object to be heated after the first time point, a current value measuring unit that measures a current value of a current supplied to the electric resistance heater;
A comparison determination unit that compares the current supply current value with the current threshold value to determine whether the electric resistance heater has deteriorated,
When it is determined that the electric resistance heater has deteriorated, an alarm unit for notifying that the electric resistance heater has deteriorated is provided.

  In the temperature control system according to the present disclosure, the temperature control unit creates an operation amount for controlling the object to be heated to a predetermined target temperature, and supplies an electric current from a power supply to the electric resistance heater according to the operation amount. To control the temperature of the object to be heated. The heater power calculator calculates the applied voltage value, the energized current value, and the operation amount of the electric resistance heater at the first time point when the heating target is at the target temperature during the temperature control of the heating target. Then, the power value supplied to the electric resistance heater is obtained as a target power value. At the same time, the heater power calculator calculates the maximum power that can be supplied from the power supply to the electric resistance heater (that is, the electric power value supplied from the power supply to the electric resistance heater when the operation amount is the maximum). Ask for. The current threshold value setting unit sets a current threshold value for determining whether the electric resistance heater has deteriorated based on the target power value, the power maximum value, and the energizing current value at the first time point. Set. The current value measuring unit measures the current value of the current supplied to the electric resistance heater during the temperature control of the object to be heated after the first time point. The comparison determination unit compares the current supply current value with the current threshold value to determine whether the electric resistance heater has deteriorated. The alarm unit, when it is determined that the electric resistance heater has deteriorated, notifies that the electric resistance heater has deteriorated. In this manner, according to the temperature control system, it is possible to automatically detect and notify that the electric resistance heater has deteriorated. The user who has received the notification can take prompt measures such as replacing the electric resistance heater with a new one or increasing the power supply voltage. As a result, it is possible to prevent a product produced by using the temperature control system from becoming defective (or quality degradation).

In a fourth aspect, a temperature control method according to the present disclosure includes:
Temperature control for a temperature control system including an electric resistance heater and a temperature sensor mounted on an object to be heated, and controlling an electric current supplied to the electric resistance heater based on the temperature of the object to be heated outputted by the temperature sensor. The method
Create an operation amount for controlling the object to be heated to a predetermined target temperature, supply a current to the electric resistance heater according to the operation amount from a power supply, and control the temperature of the object to be heated. ,
At the first time when the heating target is at the target temperature during the temperature control of the heating target, the electric resistance based on the applied voltage value, the energizing current value, and the operation amount to the electric resistance heater, The power value supplied to the heater is obtained as a target power value, and the maximum power value that can be supplied from the power supply to the electric resistance heater is obtained,
The target power value, the power maximum value, and a current threshold value for determining whether or not the electric resistance heater has deteriorated based on the energized current value at the first time point,
During the temperature control of the object to be heated after the first point in time, a current flowing current value to the electric resistance heater is measured,
Comparing the current supply current value with the current threshold value to determine whether the electric resistance heater has deteriorated,
When it is determined that the electric resistance heater has deteriorated, it is notified that the electric resistance heater has deteriorated.

  According to the temperature control method of the present disclosure, the deterioration of the electric resistance heater can be automatically detected and reported. The user who has received the notification can take prompt measures such as replacing the electric resistance heater with a new one or increasing the power supply voltage. As a result, it is possible to prevent a product produced by using the temperature control system from becoming defective (or quality degradation).

In one embodiment of the temperature control system,
The current threshold value setting unit sets the target power value to PWtarget, the power maximum value to PWmax, the conduction current value at the first time point to I1, and the current threshold value to Ith, respectively.
Ith = I1 × PWtarget / PWmax
The current threshold value is set according to the following formula:

  In a fifth aspect, a program according to the present disclosure is a program for causing a computer to execute the temperature control method according to the second or fourth aspect.

  By causing a computer to execute the program according to the present disclosure, the temperature control method according to the second or fourth aspect can be performed.

  As is clear from the above, according to the temperature control system and the temperature control method of the present disclosure, the deterioration of the electric resistance heater can be automatically detected and notified. The temperature control method can be implemented by causing a computer to execute the program of the present disclosure.

It is a figure showing typically composition of a temperature control system of one embodiment of the present invention. FIG. 2 is a diagram illustrating a hardware configuration of a temperature controller included in the temperature control system. FIG. 3 is a diagram illustrating a functional block configuration realized by a calculation unit of the temperature controller. It is a figure showing the flow of the temperature control processing (temperature control method) which the operation part of the above-mentioned temperature controller performs. It is a figure showing the concrete flow of the deterioration judging processing included in the above-mentioned temperature control processing. FIG. 6A is a diagram illustrating a time-series change of each of the temperature of the heating wire and the temperature of the object to be heated constituting the electric resistance heater in the temperature control system. FIG. 6B is a diagram illustrating a time-series change of an on / off control signal for a solid state relay in the temperature control system. It is a figure explaining how to compare the present resistance value and a resistance threshold about the above-mentioned electric resistance heater, and to judge whether the above-mentioned electric resistance heater has deteriorated.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 schematically shows a configuration of a temperature control system 200 according to an embodiment of the present invention. The temperature control system 200 includes an electric resistance heater (hereinafter, simply referred to as a “heater”) 20 and a temperature sensor 30 housed or mounted in a housing (indicated by a dashed line) of the object 90 to be heated. A temperature controller 100 is provided for controlling on / off of a current supplied to the heater 20 based on an output of the sensor 30 (temperature signal TO).

  In this example, the heater 20 has a case 20a formed of an elongated cylindrical steel pipe forming an outer wall of the heater, and a heating wire 20x disposed inside the case 20a and energized to generate heat. In this example, the wire type of the heating wire 20x is two types of nickel chrome wires for heating (abbreviated as NCHW2) specified in Japanese Industrial Standards (JISC2520), but other wire types may be used. The heater 20 is connected to a single-phase 200 volt commercial power supply 120 in this example by a pair of wires 121 and 122. A solid state relay (SSR) 110 as a switching element is interposed in one wiring 121. An ammeter 71 including a current transformer (CT) is attached to the other wiring 122. A voltmeter 70 including an instrument transformer (VT) is connected across the wires 121 and 122 on both sides of the heater 20.

  The solid state relay 110 is on / off controlled by an on / off control signal Ctl from the temperature controller 100. In this example, the on / off control signal Ctl is a rectangular wave having a period of 1 second to 2 seconds. The duty of the on / off control signal Ctl (that is, the ratio of the on period in one cycle) is set in accordance with an operation amount described below (this is referred to as MV). Thereby, during the ON period of the solid state relay 110, the heater 20 is energized by the commercial power source 120 (synonymous with energization of the heating wire 20x; the same applies throughout this specification).

  The ammeter 71 detects the current value I of the current supplied to the heater 20. The voltmeter 70 detects a voltage value V of a voltage applied to the heater 20. The current value I detected by the ammeter 71 and the voltage value V detected by the voltmeter 70 are input to the temperature controller 100.

  As shown in FIG. 2, the temperature controller 100 includes, as hardware, in this example, an operation unit 11, a display unit 12, an operation unit 13, a storage unit 14, a data input unit 15, and an output unit 17. , A communication unit 16 and an alarm 18.

  The operation unit 11 includes a CPU (Central Processing Unit) operated by software (computer program), and executes processing according to a temperature control method described later and other various processing.

  In this example, the operation unit 13 includes a key input switch and a setting switch, and is used for inputting or setting an instruction and data from a user (operator). In this example, it is assumed that a target temperature at which the heating target 90 is to be heated Ttarget = 200 ° C. is set in the setting switch of the operation unit 13.

  In this example, the display 12 includes an LED (light emitting diode) array, and displays numerical values and the like according to a control signal from the arithmetic unit 11. In this example, the display 12 is used to display the set target temperature Ttarget and the current temperature TO of the heating target 90.

  In this example, the storage unit 14 includes an EEPROM (electrically rewritable nonvolatile memory) that can temporarily store data and a RAM (random access memory) that can temporarily store data. Contains. The storage unit 14 stores software (computer program) for controlling the operation unit 11. In this example, the storage unit 14 temporarily stores various data during the temperature control of the object 90 to be heated.

  The data input unit 15 includes an AD (analog to digital) converter in this example. The data input unit 15 receives signals representing the current value I from the ammeter 71 and the voltage value V from the voltmeter 70, performs AD conversion, and inputs the result to the arithmetic unit 11.

  The output unit 17 outputs a signal (ON / OFF control signal Ctl) for controlling ON / OFF of the solid state relay 110 according to a control signal from the arithmetic unit 11. Solid state relay 110 conducts or cuts off wiring 121 connected to commercial power supply 120 according to on / off control signal Ctl.

  The communication unit 16 is controlled by the arithmetic unit 11 to transmit predetermined information to an external device, or receives information from the external device and passes it to the arithmetic unit 11. In this example, the communication unit 16 receives an instruction (command signal CM) from an external device.

  The alarm 18 issues an audible or visual alarm according to a control signal from the arithmetic unit 11. In this example, a buzzer or an LED (light emitting diode) array is provided, and a display such as an alarm sound or blinking is issued.

  As shown in FIG. 3, in this example, the programmed operation unit 11 roughly divides the temperature control unit 40 that controls the temperature of the heating target 90 and the deterioration determination that detects and reports the deterioration of the heater 20. The processing unit 50 is configured. The temperature control unit 40 includes a temperature calculation unit 41, a target temperature setting unit 42, a deviation calculation unit 43, an operation amount calculation unit 44, and an output signal creation unit 45. The deterioration determination processing unit 50 includes an output voltage measurement unit 51, an output current measurement unit 52, a resistance value calculation unit 53 serving as a first resistance value calculation unit and a current resistance value calculation unit, a heater power calculation unit 54, It includes a threshold setting unit 55, a comparison determination unit 56, and an alarm signal creation unit 57. The alarm signal creating section 57 constitutes an alarm section in combination with the alarm device 18 shown in FIG. The operation of each of these units will be described later in the flow of the temperature control process of FIG. 4 and the deterioration determination process of FIG.

  FIG. 4 shows a flow of a temperature control process (temperature control method) executed by the calculation unit 11 of the temperature controller 100. Upon receiving a start instruction from the user (operator) via the operation unit 13 shown in FIG. 2 or a start instruction (command instruction CM) via the communication unit 16, the calculation unit 11 functions as a temperature control unit. Then, the flow of the temperature control process (in this example, the first operation of the temperature control system 200) is started.

  First, as shown in step S1 of FIG. 4, the calculation unit 11 functions as a temperature calculation unit 41, and receives an output (temperature signal TO) of the temperature sensor 30 mounted on the heating target 90 shown in FIG. The current temperature of the heating target 90 (this is represented by the same symbol TO as the temperature signal) is measured and obtained. In this example, initially, the current temperature TO of the heating target 90 is assumed to be normal temperature 23 ° C. In addition, as shown in step S2 of FIG. 4, the calculation unit 11 functions as a target temperature setting unit 42, and reads a target temperature Ttarget to heat the heating target 90, which is set in advance by the operation unit 13. In this example, it is assumed that the target temperature Ttarget = 200 ° C.

  Next, as shown in step S3 in FIG. 4, the calculation unit 11 functions as the deviation calculation unit 43, and calculates a deviation DV between the current temperature TO of the heating target 90 and the target temperature Ttarget. Further, as shown in step S4 in FIG. 4, the calculation unit 11 operates as the manipulated variable calculation unit 44, and performs feedback so that the current temperature TO of the heating target 90 output from the temperature sensor 30 matches the target temperature Ttarget. An operation amount MV for control (in this example, PID control) is created. In this example, it is assumed that the manipulated variable MV represents the duty for turning on and off the solid state relay 110 shown in FIG. 1 in units of percent (%).

  Next, as shown in step S5 in FIG. 4, the arithmetic unit 11 functions as the output signal creating unit 45, and turns on and off the solid state relay 110 shown in FIG. 1 in accordance with the manipulated variable MV. Create the control signal Ctl. Arithmetic unit 11 outputs this on / off control signal Ctl to solid state relay 110 via output unit 17 shown in FIG. As a result, the solid state relay 110 is turned on and off according to the on / off control signal Ctl, and the heater 20 is energized by the commercial power supply 120.

  Next, as shown in step S6 of FIG. 4, the calculation unit 11 performs a later-described deterioration determination process (FIG. 5). Thereafter, as shown in step S7 of FIG. 4, unless a stop instruction is received from the user (NO in step S7), the arithmetic unit 11 repeats the processing of steps S1 to S6. Upon receiving a stop instruction from the user via the operation unit 13 or a stop instruction (command instruction CM) via the communication unit 16 (YES in step S7), the arithmetic unit 11 ends this temperature control process.

  In this manner, the temperature control system 200 creates the manipulated variable MV for controlling the heating target 90 to the target temperature Ttarget, and supplies the current from the commercial power supply 120 to the heater 20 at a duty corresponding to the manipulated variable MV. To control the temperature of the heating target 90 to the target temperature Ttarget.

  When this temperature control process is executed, for example, as shown in FIG. 6A, at the time of starting the temperature control (t = 0), the temperature TO of the heating target 90 is normal temperature (23 ° C. in this example). ). Then, the duty of the on / off control signal Ctl is changed for a while from the temperature control start time (t = 0) so that the heating target 90 reaches the target temperature Ttarget (200 ° C. in this example) as soon as possible. In the example, the period from t = 0 to the time t1), it is maintained at 100% (maximum) as shown by the solid line C1 in FIG. In this example, as shown in FIG. 6A, at time t1, the temperature TO of the heating target 90 reaches the target temperature Ttarget, and after time t1, the temperature TO is controlled to be substantially equal to the target temperature Ttarget without overshoot. I have. Specifically, after the time t1, the on-off control signal Ctl causes the off period (in this example, from the time t1 to the time t2 and from the time t3 to the time t4) and the solid line C2 in FIG. , C3 (in this example, from time t2 to time t3 and from time t4 to time t5) are alternately repeated (in the example shown, the duty is about 50%). .).

  Here, as shown in FIG. 6A, the temperature of the heating wire 20x inside the heater 20 is changed from the time when the current supply to the heater is started (t = 0) to the time when the heating target 90 reaches the target temperature Ttarget. TH is said to reach a relatively high temperature Tx (about 800 ° C. to 1000 ° C.). Therefore, when the operation of the temperature control system 200 is repeated or continuously continued, the heating wire 20x constituting the heater 20 is oxidized, and the resistance (electric resistance) indicated by the heating wire 20x increases (deterioration). ). As the deterioration progresses, the current (or supply power) to the heater 20 becomes insufficient, and as shown by broken lines C1 ', C2', and C3 'in FIG. The duty is gradually increased. When the deterioration further progresses, the heating target 90 cannot be controlled to the target temperature Ttarget even if the duty of the on / off control signal Ctl is set to 100%. For this reason, if no countermeasures are taken, various problems occur as described in the section of “Problems to be Solved by the Invention”.

  Therefore, the temperature control system 200 performs a deterioration determination process in step S6 in FIG. 4, and automatically detects and reports the deterioration of the heater 20. FIG. 5 shows a specific flow of this deterioration determination processing. As described above, initially, the current temperature TO of the heating target 90 is assumed to be normal temperature 23 ° C.

(1) Processing from the first temperature control start to the time when the object to be heated reaches the target temperature First, as shown in step S61 of FIG. 5, the arithmetic unit 11 was measured by the voltmeter 70 shown in FIG. The voltage value V and the current value I measured by the ammeter 71 are input via the data input unit 15 shown in FIG. Further, the calculation unit 11 works as an output voltage measurement unit 51 and an output current measurement unit 52 to obtain the current voltage value V and current value I.

  Further, as shown in step S62 of FIG. 5, the calculation unit 11 works as a resistance value calculation unit 53 (particularly, a current resistance value calculation unit) to change the resistance value indicated by the heating wire 20x to the current resistance value Rs = V / It is calculated and obtained as I.

  Next, as shown in step S63 of FIG. 5, the calculation unit 11 determines whether the current time is the timing at which the resistance threshold Rth for determining whether the heater 20 has deteriorated should be set or updated. Judge.

  In this example, this timing is a timing immediately after the heating target 90 is controlled to the target temperature Ttarget after the arithmetic unit 11 starts the temperature control of the heating target 90 as the temperature control unit, that is, FIG. It is assumed that it is the first time point t1a shown in the parentheses. The calculation unit 11 determines whether the timing immediately after the heating target 90 is controlled to the target temperature Ttarget (first time point t1a) is between the current temperature TO of the heating target 90 and the target temperature Ttarget. The determination is made based on the fact that the deviation DV has become substantially zero for at least a certain period (for example, a period indicated by a broken-line circle as the first time point t1a in FIG. 6A).

  In the first operation, during the period from t = 0 to time t1 shown in FIG. 6A, since the resistance threshold Rth has not yet been set, the process skips step S67 in FIG. 5 and skips step S67. It is determined that the heater 20 has not deteriorated yet (NO in step S67), and the process returns to the flow of FIG.

(2) Processing at First Time When the current time reaches the first time t1a shown in FIG. 6A, in step S61 of the flow (new turn) of FIG. The current voltage value V and the current value I are obtained by acting as 51 and the output current measuring section 52. These correspond to the voltage value V and the current value I at the first time point t1a.

  Further, as shown in step S62 in FIG. 5, the calculation unit 11 works as a resistance value calculation unit 53 (particularly, a first resistance value calculation unit) to change the current resistance value indicated by the heating wire 20x at the first time point t1a. Of the first resistance value R1 = V / I. In this example, the first resistance value R1 is assumed to be 50Ω.

  Next, as shown in step S63 in FIG. 5, the calculation unit 11 determines whether the current time is the timing at which the resistance threshold Rth for determining whether the heater 20 has deteriorated should be set or updated. Determine whether or not. In this example, since the current time is the first time point t1a shown in FIG. 6A (YES in step S63), the process proceeds to step S64 in FIG. Is read (the value created in step S4 in FIG. 4). Further, as shown in step S65 in FIG. 5, the calculation unit 11 functions as the heater power calculation unit 54, and the current voltage value V, current value I, and operation amount MV for the heater 20 at the first time point t1a. , A power value supplied to the heater 20 is determined as a target power value PWtarget, and a maximum power value PWmax that can be supplied from the commercial power supply 120 to the heater 20 is determined. Here, the power maximum value PWmax corresponds to the power value supplied from the power supply to the heater 20 when the duty according to the operation amount MV is 100%.

Specifically, for example, at the first time point t1a, if the current voltage value V = 200 volts, the current value I = 4 amps, and the manipulated variable (that is, duty) MV = 70%,
Target power value PWtarget = 200 volts × 4 amps × 70% = 560 watts Maximum power value PWmax = 200 volts × 4 amps = 800 watts. At the first time point t1a, since the heating target 90 is controlled to the target temperature Ttarget, the target power value PWtarget is a value that takes into account the heat capacity, the heat radiation amount, and the like of the heating target 90.

Next, as shown in step S66 of FIG. 5, the calculation unit 11 functions as the resistance threshold value setting unit 55, and based on the target power value PWtarget, the power maximum value PWmax, and the first resistance value R1, the heater 20 A resistance threshold value Rth for determining whether or not the battery has deteriorated is set (or updated). This resistance threshold value Rth is set to a level at which the power supplied to the heater 20 becomes the target power value PWtarget when the duty according to the operation amount MV becomes 100%. Specifically, the resistance threshold Rth is
Rth = R1 × PWmax / PWtarget (Eq. 1)
It is set according to the following formula. The set resistance threshold Rth is stored in the storage unit 14 shown in FIG.

  Next, as shown in steps S67 and S68 in FIG. 5, the calculation unit 11 functions as the comparison determination unit 56, compares the current resistance value Rs with the resistance threshold value Rth, and determines whether the heater 20 has deteriorated. Is determined. At the first time point t1a, Rs = R1 <Rth, and since the heater 20 has not deteriorated yet (NO in step S68), the process returns to the flow in FIG.

(3) Processing during Temperature Control of Heating Object After First Time Point If the temperature control of the heating object 90 is continued after the first time point t1a, the deterioration of the heater 20 may proceed as described above. There is. Therefore, during the temperature control of the heating target 90 after the first time point t1a, in step S61 of the flow (new turn) of FIG. 5, the calculation unit 11 sets the output voltage measurement unit 51 and the output current measurement unit 52 as Working, the current voltage value V and current value I are obtained.

  Further, as shown in step S62 of FIG. 5, the calculation unit 11 works as a resistance value calculation unit 53 (particularly, a current resistance value calculation unit) to change the resistance value indicated by the heating wire 20x to the current resistance value Rs = V / It is calculated and obtained as I. In this example, it is assumed that the deterioration of the heater 20 has progressed to some extent and Rs> R1.

  Next, as shown in step S63 of FIG. 5, the calculation unit 11 determines whether the current time is the timing at which the resistance threshold Rth for determining whether the heater 20 has deteriorated should be set or updated. Judge. In this example, since the current time is after the first time point t1a shown in FIG. 6A (NO in step S63), the process proceeds to steps S67 and S68 in FIG.

  Next, in steps S67 and S68 in FIG. 5, the calculation unit 11 acts as the comparison determination unit 56, compares the current resistance value Rs with the resistance threshold value Rth, and determines whether the heater 20 has deteriorated. . This resistance threshold value Rth is a value set at the first time point t1a by the processing of step S66 in FIG.

  In this example, when the current resistance value Rs matches the resistance threshold value Rth, the calculation unit 11 determines that the heater 20 has deteriorated. Specifically, as indicated by the auxiliary line Q1 in FIG. 7, at time td100 when Rs = Rth, it is determined that the heater 20 has deteriorated. According to this determination criterion, the power supplied to the heater 20 becomes the target power value PWtarget when the duty corresponding to the manipulated variable MV is 100%. Therefore, when the current resistance value Rs of the heater 20 has increased to a practical limit, it is determined that the heater 20 has deteriorated.

  When it is determined that the heater 20 has deteriorated (YES in step S68 of FIG. 5), in step S69 of FIG. 5, the arithmetic unit 11 functions as the alarm signal creating unit 57, and as shown in FIG. Based on the result DS, an alarm signal AS1 indicating that the heater 20 has deteriorated is created. The alarm 18 shown in FIG. 2 receives this alarm signal AS1 and notifies the user that the heater 20 has deteriorated. This notification (this is called alarm A1) may be an alarm sound of a buzzer and / or blinking of an LED. The arithmetic unit 11 may transmit the alarm signal AS1 to an external device (not shown) via the communication unit 16.

  In this manner, according to the temperature control system 200, it is possible to automatically detect and notify that the heater 20 has deteriorated. The user who has received the notification can take prompt action such as replacing the heater 20 with a new one or increasing the power supply voltage. As a result, it is possible to prevent a product produced using the temperature control system 200 from becoming defective (or quality degradation).

  In the above example, when the current resistance value Rs of the heater 20 has increased to a practical limit, it is determined that the heater 20 has deteriorated and a notification is issued. Therefore, the user can use the heater 20 with confidence up to the practical limit.

  In the above example, at the first time point t1a, as shown in FIG. 6A, after the arithmetic unit 11 starts controlling the temperature of the heating target 90, the heating target 90 is set to the target temperature Ttarget. Since the timing is immediately after the control, the resistance threshold Rth is set at that timing. As a result, it can be determined whether or not the heater 20 has deteriorated continuously from the timing immediately after the heating target 90 is controlled to the target temperature Ttarget. Therefore, the period during which the deterioration of the heater 20 can be monitored becomes relatively long.

  Further, in the process of repeatedly starting and shutting down the temperature control system 200, the resistance threshold value Rth is updated and set at the timing of the first time point t1a every time the temperature control system 200 is started. As a result, the accuracy of determining whether the heater 20 has deteriorated is increased.

  The timing at which the first time point t1a is formed is not limited to the above example, and may be any time during which the temperature of the heating target 90 is at the target temperature Ttarget during the temperature control of the heating target 90. For example, the timing that forms the first time point t1a is the timing at which a trigger signal is input from outside the temperature control system 200 via the communication unit 16, for example, the period indicated by a broken-line circle in FIG. tn. Thus, the resistance threshold Rth is updated and set at the timing when the user inputs the trigger signal from outside the temperature control system 200. As a result, user convenience is improved.

(Modification 1)
In the above example, when the current resistance value Rs matches the resistance threshold value Rth, that is, as shown by the auxiliary line Q1 in FIG. 7, the heater 20 has deteriorated at the time td100 when Rs = Rth. The judgment was made. However, it is not limited to this. The calculation unit 11 functions as the comparison determination unit 56, and the current resistance value Rs matches a value obtained by multiplying the resistance threshold value Rth by a predetermined coefficient smaller than 1 (for example, 0.8). At this time, it may be determined that the deterioration of the heater 20 is progressing according to the coefficient (0.8 in this example).

  Specifically, as indicated by the auxiliary line Q2 in FIG. 7, at time td80 when Rs = 0.8 × Rth, it is determined that the deterioration of the heater 20 is at a rate corresponding to the coefficient 0.8. At this time, the arithmetic unit 11 works as an alarm signal creating unit 57 to create an alarm signal (this is indicated by a symbol AS2) indicating the progress of the deterioration of the heater 20. Thus, the alarm 18 shown in FIG. 2 receives the alarm signal AS2 and notifies the user of the degree of deterioration of the heater 20.

  The user who has received the notification (this is called alarm A2) can prepare to replace the heater 20 with a new one in accordance with the degree of deterioration of the heater 20. Alternatively, for safety, the heater 20 can be replaced with a new one at an early stage before the progress of the deterioration of the heater 20 becomes one. The arithmetic unit 11 may transmit the alarm signal AS2 to an external device (not shown) via the communication unit 16.

  It is desirable that the alarm A2 indicating the degree of the deterioration be distinguishable from the alarm A1. For example, it is desirable that the alarm A2 has a different pitch or intermittent period from the buzzer sound of the alarm A1 and / or has a different emission color or a blinking period from the LED blinking of the alarm A1.

  Further, the “predetermined coefficient smaller than 1” representing the degree of deterioration is determined in a range of 0 to 1, preferably in a range of 0.5 to 1, and more preferably, It is defined as a number close to 1 such as 0.8 or 0.9.

(Modification 2)
In the above example, in step S66 in FIG. 5, the calculation unit 11 functions as the resistance threshold setting unit 55, and the heater 20 is degraded based on the target power value PWtarget, the power maximum value PWmax, and the first resistance value R1. The resistance threshold Rth for determining whether or not the threshold has been set (or updated). However, it is not limited to this. A current threshold value Ith may be set instead of the resistance threshold value Rth. In this case, points different from the above-described deterioration determination processing will be mainly described.

  Specifically, at the first time point t1a, in step S61 of the flow (new turn) of FIG. 5, the current value is stored in the storage unit 14 as the first current value I1. The process of step S62 in FIG. 5 (the process of calculating the current resistance value indicated by the heating wire 20x as the first resistance value R1) may be omitted. In step S65 of FIG. 5, a target power value PWtarget and a maximum power value PWmax are obtained in the same manner as described in the above example.

Next, in step S66 in FIG. 5, the calculation unit 11 functions as a current threshold value setting unit, and sets a current threshold value Ith for determining whether the heater 20 has deteriorated. The current threshold value Ith is set to a level at which the power supplied to the heater 20 becomes the target power value PWtarget when the duty according to the operation amount MV becomes 100%. Specifically, the current threshold value Ith is based on the target power value PWtarget, the power maximum value PWmax, and the first current value (the energizing current value at the first time point t1a) I1.
Ith = I1 × PWtarget / PWmax (Eq. 2)
It is set according to the following formula. The set current threshold Ith is stored in the storage unit 14 shown in FIG.

  Next, in step S61 of the flow (new turn) of FIG. 5 after the first time point t1a, the calculation unit 11 operates as the output voltage measurement unit 51 and the output current measurement unit (current current value measurement unit) 52. Thus, the current voltage value V and current value I are obtained. Thereafter, in steps S67 and S68, the calculation unit 11 functions as the comparison determination unit 56, and compares the current value I with the current threshold value Ith to determine whether the heater 20 has deteriorated. Specifically, for example, when I> Ith, the arithmetic unit 11 determines that the heater 20 has not deteriorated yet, and when I = Ith, determines that the heater 20 has deteriorated.

  Also in this case, similarly to the case where the above-described resistance threshold value Rth is set, the deterioration of the heater 20 can be automatically detected and notified. The user who has received the notification can take prompt action such as replacing the heater 20 with a new one or increasing the power supply voltage. As a result, it is possible to prevent a product produced using the temperature control system 200 from becoming defective (or quality degradation).

  In addition, the above-mentioned temperature control method is applied as software (computer program) to a recording medium capable of storing data non-transitoryly, such as a CD (compact disk), a DVD (digital universal disk), and a flash memory. It may be recorded. By installing the software recorded on such a recording medium into a substantial computer device such as a personal computer, a PDA (Personal Digital Assistance), a smartphone, and a PLC (Programmable Logic Controller), the software can be installed in those computer devices. The above-described temperature control method can be executed.

  In the above example, the temperature controller 100 digitally controls the temperature of the heater 20 by using the on / off control signal Ctl. However, the present invention is not limited to this. The temperature controller 100 may control the temperature of the heater 20 by analog output.

  The above embodiment is an exemplification, and various modifications can be made without departing from the scope of the present invention. Each of the above-described embodiments can be realized independently, but combinations of the embodiments are also possible. In addition, various features in different embodiments can also be independently realized, but combinations of features in different embodiments are also possible.

11 arithmetic unit 14 storage unit 18 alarm device 20 heater 20x heating wire 70 voltmeter 71 ammeter 100 temperature controller 200 temperature control system

Claims (11)

A temperature control system comprising an electric resistance heater and a temperature sensor mounted on a heating object, and controlling a current supplied to the electric resistance heater based on a temperature of the heating object output by the temperature sensor,
An operation amount for controlling the object to be heated to a predetermined target temperature is created, and a current is supplied from a power supply to the electric resistance heater according to the operation amount to control the temperature of the object to be heated. A temperature control unit;
At the first time when the heating target is at the target temperature during the temperature control of the heating target, the electric resistance based on the applied voltage value, the energizing current value, and the operation amount to the electric resistance heater, A heater power calculating unit that calculates a power value supplied to the heater as a target power value, and calculates a maximum value of power that can be supplied from the power supply to the electric resistance heater;
A first resistance value calculation unit that calculates a first resistance value indicated by the electric resistance heater at the first time based on the applied voltage value and the energized current value;
A resistance threshold setting unit that sets a resistance threshold for determining whether the electric resistance heater has deteriorated based on the target power value, the power maximum value, and the first resistance value;
Calculating a current resistance value indicated by the electric resistance heater based on an applied voltage value and an energized current value to the electric resistance heater during the temperature control of the object to be heated after the first time point; Department and
A comparison determination unit that compares the current resistance value with the resistance threshold value to determine whether the electric resistance heater has deteriorated,
A temperature control system comprising: an alarm unit for notifying that the electric resistance heater has deteriorated when it is determined that the electric resistance heater has deteriorated. The temperature control system according to claim 1,
The resistance threshold setting unit is configured to express the target power value as PWtarget, the power maximum value as PWmax, the first resistance value as R1, and the resistance threshold as Rth, respectively.
Rth = R1 × PWmax / PWtarget
A temperature control system, wherein the resistance threshold value is set according to a calculation formula. The temperature control system according to claim 2,
The temperature control system according to claim 1, wherein the comparison determination unit determines that the electric resistance heater has deteriorated when the current resistance value matches the resistance threshold value. The temperature control system according to claim 2 or 3,
When the current resistance value matches a value obtained by multiplying the resistance threshold value by a predetermined coefficient smaller than 1, the deterioration of the electric resistance heater is set to the coefficient. Judge that it is in accordance with the progress,
The temperature control system, wherein the alarm unit issues a notification indicating the progress of the deterioration of the electric resistance heater. The temperature control system according to any one of claims 1 to 4,
The first time point is a timing immediately after the temperature control unit starts controlling the temperature of the heating target and then immediately after the heating target is controlled to the target temperature. The temperature control system according to claim 5,
The temperature control system according to claim 1, wherein the first timing is a timing at which a trigger signal is input from outside the temperature control system. Temperature control for a temperature control system that uses an electric resistance heater and a temperature sensor mounted on a heating object and controls a current supplied to the electric resistance heater based on the temperature of the heating object output by the temperature sensor. The method
Create an operation amount for controlling the object to be heated to a predetermined target temperature, supply a current to the electric resistance heater according to the operation amount from a power supply, and control the temperature of the object to be heated. ,
At the first time when the heating target is at the target temperature during the temperature control of the heating target, the electric resistance based on the applied voltage value, the energizing current value, and the operation amount to the electric resistance heater, The power value supplied to the heater is obtained as a target power value, and the maximum power value that can be supplied from the power supply to the electric resistance heater is obtained,
Calculating a first resistance value indicated by the electric resistance heater at the first time based on the applied voltage value and the energized current value;
The target power value, the power maximum value, and, based on the first resistance value, set a resistance threshold value for determining whether the electric resistance heater has deteriorated,
During the temperature control of the object to be heated after the first time point, a current resistance value indicated by the electric resistance heater is obtained based on an applied voltage value and an energized current value to the electric resistance heater,
Comparing the current resistance value with the resistance threshold value to determine whether the electric resistance heater has deteriorated,
A temperature control method comprising: notifying that the electric resistance heater has deteriorated when it is determined that the electric resistance heater has deteriorated. A temperature control system comprising an electric resistance heater and a temperature sensor mounted on a heating object, and controlling a current supplied to the electric resistance heater based on a temperature of the heating object output by the temperature sensor,
An operation amount for controlling the object to be heated to a predetermined target temperature is created, and a current is supplied from a power supply to the electric resistance heater according to the operation amount to control the temperature of the object to be heated. A temperature control unit;
At the first time when the heating target is at the target temperature during the temperature control of the heating target, the electric resistance based on the applied voltage value, the energizing current value, and the operation amount to the electric resistance heater, A heater power calculating unit that calculates a power value supplied to the heater as a target power value, and calculates a maximum value of power that can be supplied from the power supply to the electric resistance heater;
A current threshold value setting unit that sets a current threshold value for determining whether the electric resistance heater has deteriorated based on the target electric power value, the electric power maximum value, and the energizing current value at the first time point. When,
During the temperature control of the object to be heated after the first time point, a current value measuring unit that measures a current value of a current supplied to the electric resistance heater;
A comparison determination unit that compares the current supply current value with the current threshold value to determine whether the electric resistance heater has deteriorated,
A temperature control system comprising: an alarm unit for notifying that the electric resistance heater has deteriorated when it is determined that the electric resistance heater has deteriorated. The temperature control system according to claim 8,
The current threshold value setting unit sets the target power value to PWtarget, the power maximum value to PWmax, the conduction current value at the first time point to I1, and the current threshold value to Ith, respectively.
Ith = I1 × PWtarget / PWmax
A temperature control system, wherein the current threshold value is set according to a calculation formula.
Temperature control for a temperature control system including an electric resistance heater and a temperature sensor mounted on an object to be heated, and controlling an electric current supplied to the electric resistance heater based on the temperature of the object to be heated outputted by the temperature sensor. The method
Create an operation amount for controlling the object to be heated to a predetermined target temperature, supply a current to the electric resistance heater according to the operation amount from a power supply, and control the temperature of the object to be heated. ,
At the first time when the heating target is at the target temperature during the temperature control of the heating target, the electric resistance based on the applied voltage value, the energizing current value, and the operation amount to the electric resistance heater, The power value supplied to the heater is obtained as a target power value, and the maximum power value that can be supplied from the power supply to the electric resistance heater is obtained,
The target power value, the power maximum value, and a current threshold value for determining whether or not the electric resistance heater has deteriorated based on the energized current value at the first time point,
During the temperature control of the object to be heated after the first point in time, a current flowing current value to the electric resistance heater is measured,
Comparing the current supply current value with the current threshold value to determine whether the electric resistance heater has deteriorated,
A temperature control method comprising: notifying that the electric resistance heater has deteriorated when it is determined that the electric resistance heater has deteriorated.   A program for causing a computer to execute the temperature control method according to claim 7.

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