JP2683851B2 - Anomaly detection device for controlled objects - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an abnormality detecting device to be controlled, and more particularly, to detecting an abnormality such as a wire breakage of a heater as a control object controlled by a controller or welding of a circuit for driving the heater. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus, and more specifically, to an abnormality detecting apparatus for detecting an abnormality in a heater circuit whose phase is controlled.

[0002]

2. Description of the Related Art Conventionally, as this kind of abnormality detecting device,
For example, Japanese Utility Model Laid-Open No. 61-79280 and Japanese Unexamined Patent Publication No. 2-51.
A configuration as disclosed in Japanese Patent No. 887 is known.
The former detects the heater current flowing in the heater circuit whose current is controlled by phase control and outputs it by converting it into a voltage, while detecting and smoothing the terminal voltage of the heater to form a reference voltage. This is a configuration in which the output voltages are compared and a heater burnout is detected when the converted output voltage falls below the reference voltage.

In the latter, the heater circuit, which is current-controlled by phase control, converts the current from the current output circuit for outputting a heater control signal into a voltage by means of a resistor.
Of the current output circuit through the phase control circuit to detect the current actually flowing to the heater and convert it into a voltage, and increase the converted voltage higher than that of the first comparison signal to obtain the second comparison signal. The heater disconnection detection signal is formed when a signal is formed and the second comparison signal is lower than the first comparison signal. As described above, in any of the configurations, even if the current supplied to the heater changes in accordance with the phase control, the reference voltage is changed according to the change to prevent erroneous detection of the heater disconnection, and the phase control is performed. It is considered suitable for use in a heater circuit.

[0004]

However, in the former abnormality detecting device described above, a circuit for detecting and smoothing the terminal voltage of the heater to form the reference voltage is required in addition to the detection circuit for the heater current. It is necessary to devise to simplify. Also, in the latter abnormality detection device, it is premised that the current flowing from the phase control circuit to the heater follows the output from the current output circuit, and the output current from the current output circuit to the resistor and from the phase control circuit to the heater are assumed. I am comparing the currents of the
In many cases, the changes in the output currents from the current output circuit and the phase control circuit do not exactly match, and there is room for improvement in improving the detection accuracy of heater burnout.

Further, the abnormality detecting device is desired to have a structure capable of setting various alarm levels. In the latter structure, the output current from the phase control circuit is converted into a voltage to uniformly increase the level. Form the comparison signal of
From this point as well, there is room for improvement. The present invention has been made under such circumstances, and an object of the present invention is to provide an abnormality detection device capable of accurately detecting an abnormality in a control circuit that controls a control target by continuous output of current or voltage, and having a simple configuration. To do.

[0006]

In order to solve such a problem, the present invention, as shown in the claim correspondence diagram of FIG. 1, is a detection means for detecting the drive current value to the controlled object 100 based on the manipulated variable. 101, an operating means 102 for variably operating the operation amount, a measuring means 103 for measuring and inputting the temperature of the controlled object 100, a storage means 104 for storing an alarm level, and an operating amount for preliminarily operating the operating means 102. Temperature control means 105 for storing the alarm level based on the detection value obtained from the detection means 101 in the storage means 104 and setting means 106 for setting the control temperature of the controlled object 100. ing. Then, the temperature control means 105 operates the operating means 10 based on the set temperature from the setting means 106 and the measured temperature from the measuring means 103.
2, the detected value at the time of the main operation is compared with the alarm level corresponding to the operation amount at the time of the main operation among the alarm levels stored in the storage unit 104, and the detected value at the time of the main operation is compared. Is output from the alarm level, an alarm indicating an abnormality is output.

Further, in the present invention, a plurality of controlled objects 100
A plurality of detecting means 101 and operating means 1 corresponding to
02 is provided, and when the detection value from one detection means 101 deviates from the alarm level, the rate at which the detection value from another detection means 101 deviates from the alarm level for this detection value is detected. It is possible to modify the degree of change in the detected value from 101 by the degree of change in the detected value from other detecting means, and form the temperature control means 105 so as to output an alarm when it is still outside the alarm level. Further, according to the present invention, the temperature control means is preliminarily operated with the progress of this operation, and the alarm level based on the detection value obtained from the detection means 101 by this preliminary operation is updated and stored in the storage means 104. 105 may be formed.

[0008]

In the present invention provided with such means, the temperature control means 105 obtains the detected value by preliminarily operating the operating means 102, and stores the alarm level based on this detected value in the storage means 104. Then, the temperature control means 105
When the operation means 102 is actually operated, the detected value at the time of this operation is compared with the alarm level corresponding to the operation amount at the time of this operation among the alarm levels stored in the storage means 104, and this operation is performed. When the detected value at the time deviates from the alarm level, an alarm indicating an abnormality is output.

Further, a plurality of detecting means 101 and operating means 102 are provided, and when the detected value from one detecting means 101 deviates from the alarm level, an alarm is output in consideration of the degree of change in the other detecting means 101. In the configuration in which the temperature control means 105 is formed as described above, an actual alarm is not output even if one detection value fluctuates due to fluctuations in the power supply voltage. Further, in the configuration in which the temperature control means 105 is formed so as to perform the preliminary operation again after the lapse of this operation, even if the characteristic of the control target is changed by this operation, the alarm level and the detected value corresponding to the characteristic change are compared. .

[0010]

Embodiments of the present invention will be described below with reference to the drawings. First, a usage mode of the temperature controller equipped with the abnormality detecting device of the present invention will be described with reference to the block diagram of FIG. FIG.
In, the temperature controller 1 has a set value S set from the outside.
V and a measured value PV obtained by measuring the temperature of the heater 3 as a control target arranged in an injection molding machine (not shown) with a temperature sensor 5 to perform PID calculation, for example, DC 4 to 20
A continuous current output of mA or a continuous voltage output of 0 to 5V DC is output to the heater operating unit 7 as the manipulated variable MV.

The heater operating unit 7 is composed of, for example, an SCR unit, and turns on / off a driving current of 100 V from a commercial power source 9 in accordance with the continuous operation amount MV of the heater 3.
Is for phase control. Heater operation unit 7 and heater 3
A current transformer CT as a current detector is arranged in the heater circuit between them to detect the driving current value to the heater 3 and output it to the temperature controller 1. The temperature controller 1 outputs a preset alarm level and its alarm level. The detected values are compared, and when the detected value exceeds the alarm level, an alarm signal indicating an abnormality is output.

That is, the temperature controller 1 detects an abnormal state when a abnormal current flows in the heater circuit due to a breakage of the heater 3 or a welding of the operating device circuit, and outputs an alarm signal. It is equipped with. Note that the temperature controller 1 shown in FIG. 2 is simplified to a one-channel (CH) configuration for controlling one heater 3 composed of three heater wires for convenience, but in reality, control of a large number of heaters 3 is performed. It has a configuration having a plurality of channels (CH) as much as possible.

FIG. 3 is a block diagram showing an embodiment of the abnormality detecting device according to the present invention together with a temperature controller. The control circuit 11 is a microcomputer having a CPU, which is a main part of operation processing of the abnormality detection device and the temperature controller, a ROM storing an operation program of the CPU, and an I / O for interfacing each circuit described later. Has been formed.

The control circuit 11 includes an input circuit 13, a measurement input circuit 15, a current detector input circuit 17, an alarm level storage circuit 19, a measured value storage circuit 21, and a circuit welding alarm output circuit 2.
3, the heater burnout alarm output circuit 25, the output circuit 27, the display circuit 29, and the heater burnout determination circuit 31 are connected to manage them. The input circuit 13 is, for example, a keyboard arranged on the operation panel of the temperature controller, and set temperature SV, a coefficient for setting an alarm level, selection of start or end of preparatory operation or main operation described later, and temperature adjustment. It functions as a setting means for inputting instructions necessary for operating the meter.

In addition to the keyboard, this input circuit 13
For example, it may be formed by a communication input unit according to the RS-232C standard or the like. The measurement input circuit 15 A / D-converts and counts the temperature signal measured by the temperature sensor 5 of FIG. 2, and digitally measures and fetches the temperature of the heater 3. The current detector input circuit 17 detects a drive current value from the heater operating unit 7 to the heater 3 by the current transformer CT of FIG. 2, A / D converts the current detection value, counts it, and digitally captures it. It is a measuring means.

The alarm level storage circuit 19 calculates the heater burnout alarm level and the circuit welding alarm level for calculation, and the detected current values for the heater 3 measured by the current detector input circuit 17 during the preparatory operation described later. It is a readable / writable RAM that stores in correspondence with the amount, and also stores the heater burnout warning level and circuit welding warning level calculated by multiplying each current detection value by the heater burnout warning level calculation coefficient and the circuit welding warning level calculation coefficient. doing. The respective current detection values, heater burnout alarm levels and circuit welding alarm levels are registered in the state of a matrix table (not shown). For example, if the current detection value of a certain channel (CH) is 100 A, this current detection value is detected. Value or coefficient (10% or 1
5%) and heater break alarm levels such as 90A and 85A are registered (see FIG. 5 described later).

The measurement value storage circuit 21 is a RAM for storing the temperature signal from the measurement input circuit 15. The heater disconnection determination circuit 31 determines that the heater is disconnected when the detected current value is lower than the heater disconnection alarm level corresponding to the manipulated variable MV from the control circuit 11, and a circuit welding alarm corresponding to the manipulated variable MV from the control circuit 11. When the detected current value exceeds the level, it is determined that the actuator circuit is welded, and the determination result is output to the control circuit 11.

The control circuit 11 follows the operation instruction from the input circuit 13, for example, DC 4 mA, 5 mA, 6 mA, ...
・ Amount of operation M little by little like 19mA and 20mA
V is increased and output to the output circuit (refer to the heater operation unit 7 in FIG. 2) 27, and each current detection value from the current detector input circuit 17 corresponding to each operation amount MV is stored in the alarm level storage circuit 19. In addition, it has a function of multiplying each current detection value by a heater burnout warning level calculation coefficient and a circuit welding warning level calculation coefficient to generate a heater burnout warning level and a circuit welding warning level, and similarly storing them in the warning level storage circuit 19. doing. For convenience, this function is called a preliminary operation.

In addition to the above-mentioned preliminary operation function, the control circuit 11 has the measured value PV from the measurement input circuit 15 and the input circuit 13.
The deviation is calculated by comparing the set value SV from
It has a function of calculating the ID, outputting the manipulated variable MV to the output circuit 27, and displaying them on the display circuit 29 such as a liquid crystal display or a CRT display. This function is called this operation for convenience. The control circuit 11 outputs the detected current value and the alarm level to the heater disconnection determination circuit 31, and the heater disconnection alarm output circuit 25 outputs the heater disconnection alarm output circuit 25 based on the result of the heater disconnection determination from the heater disconnection determination circuit 31 or the operation circuit welding determination. It has a function of outputting a disconnection alarm signal and outputting an operation unit circuit welding alarm from the circuit welding alarm output circuit 23. That is, the control circuit 11 and the heater disconnection determination circuit 31 form a temperature control means.

The abnormality detecting device of the present invention will be clarified by the description with reference to the flowchart showing the operation thereof. When a preliminary operation is instructed from the input circuit 13 at the time of exchanging dies of the injection molding machine or the like (setup change) or at the start of operation, the operation program of FIG.
The output% (operation amount) from the control circuit 11 is set to the output lower limit value (operation lower limit amount) in 01, and the output lower limit value is output to the output circuit 27 as the operation amount MV in step 402.

Then, in step 403, the detected current value is fetched from the current detector input circuit 17 into the control circuit 11, and if necessary, appropriate correction is performed, and in step 404, the detected current value is made into a matrix table in correspondence with the output%. Is registered, and the increase amount X is added to the output% in step 405 to set a new output% in the control circuit 11. In the following step 406, it is determined whether or not the new output% exceeds the upper limit value, and if it does not exceed the upper limit value, NO is returned to step 402,
Step 4 described above until the new output% exceeds the upper limit value
When the new output% exceeds the upper limit value and YES is obtained in step 406, the process is ended.

Therefore, for example, a DC current of 4 mA to 20 m
When varying the operation output amount in the range of A, 4 mA (lower limit value: 0%), 5 mA, 6 mA, ... 19 mA, 20 m
The detected current value corresponding to A (upper limit value: 100%) is registered in the matrix table, and as shown in FIG. 5, the characteristic A of each detected current value and the heater burnout alarm calculated based on each detected current value. Level characteristic B and circuit welding alarm level characteristic C
Is obtained, the initial setting of the alarm level is completed, and the operation is ready to start. By the way, for example, when the heater 3 is phase-controlled by the temperature controller 1 as shown in FIG. 2, if the heater current follows the manipulated variable MV, theoretically the current detection value is indicated by the broken line D in FIG. Although the characteristics are as shown, in reality, since the heater operation unit 7 and the like are interposed between the temperature controller 1 and the heater 3, the overall characteristics change, and the tendency of the change depends on the configuration of the heater operation unit 7 and the heater 3. Change.

Next, the heater disconnection and circuit welding determination operation will be described with reference to the flow chart of FIG. Step 60
In step 1, a temperature signal is input from the measurement input circuit 15, and in step 602, a current detection value is input from the current detector input circuit 17. In step 603, it is determined whether or not the current detection value has dropped below the heater burnout alarm level. If it is determined and it has decreased, the determination is YES and the routine proceeds to step 604. At this step 604, the heater disconnection alarm signal output processing is performed and the processing ends. If NO at step 603, the routine proceeds to step 605.

In step 605, it is judged whether or not the detected current value has risen above the circuit welding alarm level, and if it has risen, the determination is YES and the process moves to step 606. In step 606, the circuit welding alarm signal output process is performed. If the result of step 605 is NO, the process ends. As described above, the abnormality detection device of the present invention captures the detected value of the heater current in advance by the preliminary operation, calculates and stores the alarm level, and detects the abnormality by comparing the detected current value with the alarm level during the main operation. Since the configuration is adopted, the presence or absence of heater disconnection and circuit welding can be detected by internal calculation, the circuit configuration is simplified and the device can be downsized as compared with the conventional configuration.

Moreover, since the abnormality is detected from the alarm level based on the detection value obtained by changing the operation output, the abnormality is detected in the state including the heater current characteristic including the heater operating unit 7 for phase control, and the heater is detected. Accurate detection of disconnection and circuit welding. By the way, in the abnormality detection device,
Even if the conditions for outputting the burnout alarm signal are met for a certain heater, that heater may not always be burnt out due to fluctuations in the power supply voltage or the like. Therefore, in the abnormality detection device of the present invention, even if the current detection value of a heater exceeds the alarm level, the state of the drive current to another heater connected to the same power source as that heater is detected, and the current detection value is If there is a similar fluctuation tendency, the control circuit 11 of FIG. 3 can be configured so that the alarm signal is not output because it is a detected value change based on the fluctuation of the power supply voltage.

That is, in the configuration of FIG. 3 described above,
When the heater disconnection determination circuit 31 determines that one heater has a heater disconnection or circuit welding, the current detection value of the one heater and the current detection values of the other heaters connected to the same power source are changed. If the degree of fluctuation is the same for both heaters, the current detection value of that one heater is increased or decreased by the degree of fluctuation and an alarm is issued if the corrected detection value exceeds the alarm level. The control circuit 11 is formed so as to output a signal. FIG. 7 is a flowchart explaining this operation.

In step 701, the heater channel (CH) for which an alarm has occurred and another heater channel (C) of the same power source are used.
The current detection value related to the drive current to (H) is detected, and in step 702, it is determined whether or not both current detection values fluctuate with the same tendency. If the fluctuations of the same tendency are not satisfied, step 702 becomes NO and the process moves to step 703. At step 703, it is judged that the alarm is an actual alarm, and the alarm signal output process is performed and the process ends. If both current detection values have the same tendency and step 702 is YES, step 704 is performed.
The correction degree is corrected by and the alarm level is still exceeded after the correction, and it is determined whether or not the alarm state.

If step 704 is YES, an alarm signal output process is performed in step 703, and step 7
If 04 is NO, it is determined in step 705 that the fluctuation of the detected current value is caused by the fluctuation of the power supply, and the alarm invalidation process is performed, and the process ends. The modification of the degree of fluctuation in step 704 can be performed by a method of correcting the heater current value and a method of correcting the alarm level.

In such a configuration, for example, as shown in FIG. 8, when the current detection value A0 relating to one heater of the channel (CH) 1 fluctuates and drops to A1, the control circuit 11
Detects the current detection value of the heater in the other channels (CH) 2 and 3, and the current detection value related to the channels (CH) 2 and 3 changes from B0 or C0 to B1 or C1,
The detected value A1 after the change related to channel (CH) 1 is corrected to AX by the change and compared with the heater burnout alarm level. If the corrected value AX does not exceed the heater burnout alarm level, the actual heater burnout is detected. The alarm invalid process is performed without outputting the alarm signal, and if the alarm is exceeded, the alarm signal output process is performed. The circuit welding alarm detection operation is also the same, so description thereof will be omitted. Therefore, even if the detected current value for a certain heater fluctuates due to fluctuations in the power supply voltage, an alarm judgment is made based on the corrected value, so false alarms due to fluctuations in the power supply voltage can be avoided.

Note that in such a configuration, a large number of heaters are grouped for each power supply line, the variation between the heaters is measured in the group, and an actual alarm is issued when an alarm judgment is output a plurality of times. Control circuit 11 to output
Can be configured. In FIG. 8, each channel (C
H) The current detection values A0, B0, C0 of 1 to 3 are shown in the same level, but in general, each channel (CH) 1
The detected current values A0, B0, C0 of .about.3 are different from each other, and the corresponding alarm levels are also different.

On the other hand, in the abnormality detecting device to be controlled,
Since the resistance value of the heater to be controlled changes according to the temperature rise, it is preferable to reset the alarm level after the temperature rise of the heater from the viewpoint of ensuring an accurate alarm detection operation according to the control target. Therefore, the control circuit 11 of FIG.
Is the manipulated variable MV after the temperature of the heater is raised by this operation.
C4mA, 5mA, 6mA, ... 19mA, 20mA
As described above, the temperature is raised and output to the output circuit 27, each current detection value corresponding to each manipulated variable MV is input again, and the heater burnout alarm level and the circuit welding alarm level are recalculated for each current detection value. It is preferable that the previous heater burnout alarm level and the circuit welding alarm level are rewritably registered by registering them in the alarm level storage circuit 19.

As described above, after the temperature of the heater is raised by this operation, the timing for the preliminary operation is as follows: (1) When the operator confirms the stable operation state after the temperature rise and gives a manual instruction from the input circuit 13. (2) When the control circuit 11 automatically gives an instruction after a lapse of a predetermined set time after startup,
(3) It is realistic that the control circuit 11 automatically gives an instruction when the measured value PV reaches close to 90% of the set value SV, and the input circuit 13 gives an instruction to select those (1) to (3). Based on this, the control circuit 11 executes. Regarding the resetting of the alarm level after the heater temperature rises, other than the method of re-inputting each current detection value corresponding to each manipulated variable MV, (1)
Then, a method of measuring at least one current detection value corresponding to the manipulated variable MV after the temperature rise and correcting the whole again by the difference, or (2) storing the above (1) as a function of the measured value PV. There is a way to go.

Of course, the measured value PV after the temperature rise, the detected current value or the alarm level for each heater configuration is stored in the measured value storage circuit 21 in FIG. Is also possible. The solid line in FIG. 9A shows the characteristic of the current detection value before the temperature rise of the heater, and the broken line in FIG. 9B shows the characteristic of the current detection value after the temperature rise. As described above, if the preparatory operation is possible after the main operation, it is possible to detect the alarm with high accuracy in accordance with the progress of the control of the controlled object.

[0034]

As described above, according to the present invention, the alarm level is stored from the detected value obtained by performing the preliminary operation on the controlled object, and the detected value at the time of the actual operation is compared with the stored alarm level. However, since the alarm is output when the detected value at the time of the main operation deviates from the alarm level, it is possible to accurately detect the abnormality of the control target or the drive circuit of the control target, and the configuration becomes simple. Further, when one detection value deviates from the alarm level, in a configuration that outputs an alarm in consideration of the degree of change of other detection values, for example, even if there is a change in one detection value due to a change in power supply voltage. The actual alarm is not output unless the fluctuation is outside the predetermined range, and erroneous detection due to power fluctuation can be prevented. Furthermore, in the configuration in which the preliminary operation is performed again after this operation, even if the characteristics of the control target change due to this operation, the alarm level and detection value corresponding to the change in the characteristics can be reset, and the operation progresses to the control target. Accurate abnormality detection is possible in accordance with the above. In particular, the present invention is suitable for a configuration in which a controlled object is controlled by continuous output of current or voltage.

[Brief description of the drawings]

FIG. 1 is a claim correspondence diagram showing a configuration of an abnormality detection device according to the present invention.

FIG. 2 is a circuit diagram illustrating a temperature controller equipped with the abnormality detection device according to the present invention.

FIG. 3 is a block diagram showing an embodiment of an abnormality detecting device according to the present invention.

FIG. 4 is a flowchart illustrating an operation of the abnormality detection device of the present invention.

5 is a diagram showing characteristics of a detection value and an alarm level stored in an alarm level storage circuit in FIG.

FIG. 6 is a flowchart illustrating an operation of the abnormality detection device of the present invention.

FIG. 7 is a flowchart illustrating an operation of the abnormality detection device of the present invention.

FIG. 8 is a diagram illustrating a relationship between a detection value and an alarm level in which a variation of the power supply voltage is corrected in the abnormality detection device of the present invention.

FIG. 9 is a characteristic diagram of current detection values before and after temperature rise.

[Explanation of symbols]

 1 Temperature Controller 3 Control Target (Heater) 5 Temperature Sensor 7 Heater Operator 9 Power Supply 11 Temperature Control Means (Control Circuit) 13 Setting Means (Input Circuit) 15 Measuring Means (Measurement Input Circuit) 17 Detecting Means (Current Detector Input) 19) Memory means (alarm level memory circuit) 21 Measured value memory circuit 23 Circuit welding alarm output circuit 25 Heater burnout alarm output circuit 27 Output circuit 29 Display circuit 31 Temperature control means (heater burnout determination circuit) 100 Control object 101 Detection means 102 Operation Means 103 Measuring Means 104 Storage Means 105 Temperature Control Means 106 Setting Means CT Current Transformer

Claims (3)

(57) [Claims] 1. A detection means for detecting a drive current value to a control target based on an operation amount, an operation means for variably operating the operation amount, a measurement means for measuring and inputting a temperature of the control target, and an alarm level. Storage means for storing, temperature control means for preliminarily operating the operation means, changing the operation amount, and storing the alarm level based on the detection value obtained from the detection means in the storage means, and the controlled object. And a setting means for setting the control temperature of the control object, wherein the temperature control means operates the operating means based on the set temperature from the setting means and the measured temperature from the measuring means. At the same time, the detected value at the time of the main operation is compared with the alarm level corresponding to the operation amount at the time of the main operation among the alarm levels stored in the storage means, and An abnormality detecting device to be controlled, which is configured to output an alarm indicating an abnormality when a detected value deviates from the alarm level. 2. The temperature control means includes a plurality of detection means and a plurality of operation means respectively corresponding to a plurality of control targets, and the temperature control means, when a detection value from one detection means deviates from the alarm level, Is configured to output the alarm when the ratio of the detected value from the detecting means deviating from the alarm level for the detected value is larger and the degree of change in the detected value from the one detecting means is larger. Claim 1
Anomaly detection device for the described control target. 3. The temperature control means preliminarily operates the operation means in accordance with the progress of the main operation, and the detection value obtained from the detection means by the preliminary operation is updated and stored in the storage means as an alarm level. The abnormality detecting device for a controlled object according to claim 1 or 2, wherein the abnormality detecting device is controlled.