WO2023176494A1 - Failure detection device - Google Patents

Abstract

The present disclosure provides a failure detection device capable of detecting a failure of an analog instrument.　A failure detection device according to the present disclosure is characterized by comprising: an analog instrument including a housing, an indicator provided in the housing, and a magnet attached to the rotary axial center of the indicator; and a sensor unit attached to a front side of the analog instrument, wherein the sensor unit determines a failure from a change in the magnetic field of the magnet occurring due to the micro-motion of the indicator.

Description

Failure detection device

The present disclosure relates to a failure detection device. This application claims priority to Japanese Patent Application No. 2022-042039 filed in Japan on March 17, 2022, the contents of which are incorporated herein.

In factories, etc., the state of the system is stabilized by measuring the pressure, temperature, flow rate, etc. of piping and managing the state. To display detected values such as pressure, temperature, flow rate, etc., a device such as a circular instrument panel or a rectangular display panel, which indicates detected values with an analog pointer, is generally used.

Additionally, the value indicated by the pointer of an analog meter is read and taken out to the outside wirelessly.

For example, in Patent Document 1, the device is attached to a meter that has a scale plate with a scale, a pointer, and a transparent cover plate that covers the scale plate and the pointer, and is equipped with an IC chip and an antenna, and can transmit stored information by radio waves in a non-contact manner. an IC tag unit for an instrument, an IC tag system for an instrument, and an IC tag unit, which has an IC tag and a mounting medium for attaching the IC tag to an instrument, and is used with a wireless reader that performs wireless communication with the IC tag. A method for calibrating a meter equipped with an IC tag unit and an IC tag unit is disclosed. In this way, according to Patent Document 1, the value indicated by the pointer can be read and taken out wirelessly without impairing the calibration state and visibility of the analog meter by being retrofitted to the analog meter.

Japanese Patent Application Publication No. 2017-203775

However, when an analog meter breaks down, in many cases, the pointer of the analog meter becomes stuck and does not move, indicating a certain value. In such cases, the failure may not be noticed because the pointer of the analog meter indicates a certain value.

Therefore, in view of the above problems, the present disclosure provides a failure detection device that can detect failures of analog instruments.

In one aspect of the present disclosure, an analog meter includes a housing, a pointer provided in the housing, a magnet attached to a rotation axis of the pointer, and a sensor unit attached to a front side of the analog meter. The sensor unit is characterized in that a failure is determined based on a change in the magnetic field of the magnet caused by a slight movement of the pointer.

As described above, according to the present disclosure, it is possible to provide a failure detection device that can detect failures in analog instruments.

FIG. 1 is a front view schematically showing a failure detection device according to the present disclosure. FIG. 2 is a front view of the analog meter. FIG. 3 is an AA cross-sectional view schematically showing the failure detection device according to the present disclosure. FIG. 4 is a front view schematically showing a failure detection device according to the present disclosure. FIG. 5 is an image diagram showing how a magnetic sensor reads the movement of a magnet that rotates with the rotation axis. FIG. 6 is a diagram showing voltage versus angle. FIG. 7 is a flow diagram when an analog meter reads measurements. FIG. 8 is a flow diagram in which the failure detection device according to the present disclosure determines a failure. FIG. 9 is a flow diagram of a modification example in which the failure detection device according to the present disclosure determines a failure.

Hereinafter, preferred embodiments of the present disclosure will be described in detail with reference to the drawings. Note that this embodiment described below does not unduly limit the content of the present disclosure described in the claims, and all of the configurations described in this embodiment are essential as a solution to the present disclosure. Not necessarily.

1 to 4 show an example of a failure detection device that is the subject of this application. FIG. 1 is a front view schematically showing a failure detection device 100 according to the present disclosure. FIG. 2 is a front view of the analog meter 10. FIG. 3 is an AA cross-sectional view schematically showing the failure detection device 100 according to the present disclosure. FIG. 4 is a front view schematically showing the failure detection device 100 according to the present disclosure. As shown in FIGS. 1, 2, 3, and 4, a failure detection device 100 according to the present disclosure includes an analog meter 10 and a sensor unit 20.

The analog meter 10 includes a housing 11 of the analog meter 10 and a pointer 12 provided inside the housing 11. Examples of the analog instrument 10 include a pressure gauge, a thermometer, a flow meter, a power meter, a liquid level gauge, and the like. Examples of the analog instrument 10 include a circular instrument panel and a rectangular display panel.

The housing 11 accommodates the dial 17 in addition to the pointer 12. The dial 17 is provided within the housing 11 and has numerical values 15 and/or scales 16 written thereon. The pointer 12 points to a numerical value 15 and/or a scale 16. The transparent plate 18 is placed over the housing 11 so as to cover the front side (+Z direction) of the dial 17 and the hands 12.

The magnet 14 is attached to the rotation axis 13 of the pointer 12. As the rotation axis 13 rotates in response to the slight movement of the pointer 12, the rotation angle of the pointer 12 is read from changes in the magnetic field of the magnet 14 attached to the rotation axis 13, and the measured value of the analog meter 10 is read. . Further, the angle θ (+θ, −θ) of the pointer 12 as shown in FIG. 4 is measured to determine a failure. The method for reading measured values and the method for determining failure will be described in detail later.

Note that the magnet 14 can also be attached to the pointer 12, or the pointer 12 itself can be the magnet 14. Further, the magnet 14 can be a permanent magnet or an electromagnet.

The diameter M of the sensor unit 20 is preferably φ25 mm to φ40 mm.

The sensor unit 20 has a function of reading the movement of the pointer 12 of the analog meter 10 and outputting the measured value of the analog meter 10 as a digital signal.

As shown in FIGS. 1 and 3, the sensor unit 20 is installed on a transparent substrate 18 provided above the pointer 12 of the analog meter 10 (at the opening of the housing 11). Before installation, the transparent substrate 18 is removed and the magnet 14 is attached to the rotary cram 13 of the pointer 12 as described above. With this configuration, the magnetic sensor in the sensor unit 20 can read the magnetism of the magnet 14.

We will explain how the magnetic sensor reads the rotation angle of the pointer.

The magnet 14 attached to the rotating shaft 13 rotates together with the rotation of the rotating shaft 13, as shown in FIG. The magnetic sensor 21 reads the magnetic movement of the magnet 14 and outputs the values of Sin θ and Cos θ with respect to the angle θ as voltages as shown in FIG. Based on this output, the angle θ is calculated. For example, when the output of Sin θ is 0.0 V, if Cos θ is 1.5 V, the angle is 0 degree, and if Cos θ is −1.5 V, θ is 180 degrees. Since the angle θ corresponds to the rotation angle of the pointer 12, it becomes possible to read an analog measurement value from θ.

Devices that indicate detected values using analog pointers are commonly used in factories and the like. Since it is an analog meter, it is necessary to visually read the meter to manage the measured values, but the above-mentioned literature makes it possible to read the measured values automatically.

For example, a Bourdon tube pressure gauge usually has a Bourdon tube, a scale plate, and a pointer inside the housing, and the slight movement caused by the elastic stress of the Bourdon tube due to fluctuations in the measured fluid pressure is reflected in the pointer through an enlargement mechanism. The system transmits the information and instructs the pointer to rotate on the scale plate.

As mentioned above, the Bourdon tube pressure gauge detects subtle changes in the Bourdon tube, so it is easily affected by, for example, pulsation of the measuring fluid, vibrations of the pressure gauge attached, the tube body, etc., and it is difficult to see with the naked eye. Even if the pointer appears to be stationary, it is always moving slightly.

FIG. 7 shows the flow when reading the measured values of the analog meter 10. In the flow of FIG. 7, reading the angle of the pointer 12 of the analog meter 10 with the magnetic sensor 21 of the magnet 14 is expressed as angle measurement. After starting the measurement and performing the measurement a specified number of times, averaging processing is performed.

The device shown above has a high reading resolution, and when it is used to read the movement of the pointer, the measured value is unstable because it reads the minute movement mentioned above. Therefore, it is necessary to take measurements repeatedly and average them.

Next, the averaged data is output as the measurement result.

The failure detection device 100 according to the present disclosure outputs the display of the pointer 12 of the analog measuring instrument 10 as a digital value as described above, but also has a function of detecting that the analog measuring instrument 10 has failed. Have it together. The reason why a failure detection function is necessary and the detection means are described below.

Since the analog meter 10 generally performs measurements by mechanical means, failures may occur. For example, in a pressure gauge, a bourdon tube measures deformation based on pressure and displays it with a mechanical pointer, so failures may occur due to metal fatigue or deformation of the bourdon tube or due to sticking of the pointer.

In rare cases, a skilled worker will detect an abnormality by observing the movement of the pointer when the detected value fluctuates and detect something different from normal, but this may occur if the pointer does not move from zero. There are problems in which failures are not known until they have completely stopped working.

Therefore, the failure detection device 100 according to the present disclosure makes it possible to easily detect failures in analog instruments. Under normal conditions, the pointer of an analog meter pulsates and makes slight movements, so the failure detection device 100 according to the present disclosure detects a failure by the change in the magnetic field of the magnet that occurs when the pointer shakes (rotates) due to the slight movement of the pointer. do.

The failure determination method will be explained. FIG. 8 is a flow diagram in which the failure detection device 100 according to the present disclosure determines a failure.

The failure detection device 100 according to the present disclosure can use a small analog meter 10 or the like. Specifically, the diameter N of the analog meter 10 is 60 mm or less and 50 mm or less. The pulsation of the pointer 12 of a small analog instrument 10 such as these diameters is very small and has a small amplitude due to the small size of the pointer 12, so it is impossible to judge the presence or absence of pulsation with the naked eye. be. The failure detection device 100 according to the present disclosure can detect failures even in small analog instruments 10.

First, the sensor unit 20 reads the change in the magnetic field of the magnet 14 attached to the pointer 12, measures the relative angle of the pointer 12 a specified number of times from the initial value, and stores the data. For example, repeat this every second or faster, at 2 milliseconds. By measuring in 2 milliseconds, data can be obtained 500 times in 1 second.

The measurement interval can be set arbitrarily. If the interval is too short, the power consumption of the measurement system will increase, and if it is too long, it will be too late to notice changes in measured values. Set the time taking into consideration the needs of the measurement system.

Then, the standard deviation of the relative angle is calculated using the stored data. The standard deviation can be calculated based on data obtained by calculating the above-mentioned average value in order to stabilize the measured value, or can be calculated from data obtained by measuring a specified number of times.

The standard deviation calculation method is as shown in FIG. 4, for example, if the measured angles are θ=1°, -θ=-1°, θ=0.8°, θ=-1°, θ=-0.9°, When θ=1.5°, the data is calculated as 1°, -1°, 0.8°, -1°, -0.9°, 1.5°, and the average value is approximately 0.07°. The standard deviation is approximately 1.16°.

If the measured standard deviation is larger than the threshold value, it is determined to be normal. On the other hand, if the measured standard deviation is smaller than the threshold, it is determined that there is a failure. If the standard deviation is large, it means that the variation in the measured values is large. This shows that the pointer 12 is operating normally by following the random micro-movements of the object to be measured. On the other hand, when the standard deviation is small, it means that the variation in measured values is small. In this case, it is considered that the pointer 12 is stuck and unable to follow the random micro-movement of the object to be measured, and it can be determined that the pointer 12 is malfunctioning.

Here, the purpose of setting the threshold value is that the swing amplitude of the pointer 12 due to pulsation varies depending on the location where the analog meter 10 is installed and the degree of vibration etc. Therefore, in setting the threshold value, it is necessary to measure the angle of the analog instrument 10 at the installation location, obtain the standard deviation, and set the threshold value in consideration of temperature fluctuations, vibration changes, and the like.

When installing the device on a device that operates normally, the threshold value can be determined by obtaining the standard deviation during normal operation when the device is installed and using that as the threshold value. The threshold value can also be in a range greater than 0° and less than or equal to 0.5°. For example, the length from the center of the pointer 12 to the scale 16 of the φ50 analog meter 10 is approximately 20 mm. At this time, the length of the string of θ=0.25° and -θ=-0.25° (center angle 0.5°, ±0.25°) at a radius of 20 mm is approximately 0.17 mm, that is, the pointer 12 The moving distance of the tip is approximately ±0.085 mm. The minimum distance that humans can judge with the naked eye is said to be 0.1 mm, so the above range is preferable. Therefore, failure can be determined with high accuracy.

FIG. 9 is a flow diagram of a modification example in which the failure detection device 100 according to the present disclosure determines a failure. As shown in FIG. 9, parameters and dead zones are used to determine failure.

Due to the nature of magnetic sensors, initial calibration is required. At this time, the standard deviation during normal operation is obtained, stored as an internal parameter, and used as a parameter for failure determination.

The angle measurement and standard deviation are performed in the same manner as in the embodiment shown in FIG. In the embodiment shown in FIG. 8, a standard deviation is set to determine a failure, but in this modification, a failure is determined based on parameters acquired during calibration.

The parameter is the standard deviation of the analog instrument 10 when it is not operating. Further, a dead zone is set by the user, and the determination is made by comparing the parameter ± dead zone with the standard deviation obtained by frequently measuring angles.

At this time, if the standard deviation is larger than the sum of the parameter and the dead zone, it is determined to be normal. On the other hand, if the standard deviation is smaller than the sum of the parameter and the dead zone, it is determined that there is a failure.

Furthermore, the dead zone is preferably in the range of -0.5° to 0.5°.

Furthermore, in the embodiments shown in FIGS. 8 and 9, it is preferable to automatically measure at regular intervals and determine a failure. The fixed period can be set every half day or every day.

As described above, according to the failure detection device 100 according to the present disclosure, it is possible to detect a failure of the analog meter 10.

Although each embodiment and each example of the present disclosure has been described in detail as above, those skilled in the art will appreciate that many modifications can be made without substantially departing from the novelty and effects of the present disclosure. , it will be easy to understand. Therefore, all such modifications are included within the scope of the present disclosure.

For example, a term that is described at least once in the specification or drawings together with a different term with a broader or synonymous meaning can be replaced by that different term anywhere in the specification or drawings. Further, the configuration and operation of the failure detection device are not limited to those described in each embodiment and each example of the present disclosure, and various modifications are possible.

Claims (8)

1. An analog instrument comprising a housing, a pointer provided in the housing, and a magnet attached to a rotation axis of the pointer;
   a sensor unit attached to the front side of the analog instrument;
   Equipped with
   The failure detection device is characterized in that the sensor unit determines failure based on a change in the magnetic field of the magnet caused by slight movement of the pointer.
2. The sensor unit measures a standard deviation of a relative angle at which the pointer rotates from a change in the magnetic field of the magnet caused by a slight movement of the pointer during failure determination of the analog meter;
   The failure detection device according to claim 1, wherein a failure is determined when the standard deviation is smaller than a threshold value specific to the analog meter.
3. The failure detection device according to claim 2, wherein the threshold value is in a range of greater than 0° and less than or equal to 0.5°.
4. The sensor unit measures a standard deviation of a relative angle at which the pointer rotates from a change in the magnetic field of the magnet caused by a slight movement of the pointer during failure determination of the analog meter;
   A failure is determined when the standard deviation is smaller than a parameter that is a standard deviation of the relative angle at which the pointer rotates from a change in the magnetic field of the magnet caused by slight movement of the pointer during normal operation of the analog meter. The failure detection device according to claim 1.
5. The failure detection device according to claim 4, wherein a failure is determined when the standard deviation is smaller than the sum of the parameter and the dead zone.
6. The failure detection device according to claim 5, wherein the dead zone is in a range of -0.5° to 0.5°.
7. The failure detection device according to any one of claims 1 to 6, wherein the failure detection device automatically determines failure at regular intervals.
8. The failure detection device according to any one of claims 1 to 7, wherein the analog meter has a diameter of 60 mm or less.

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