JP2012205184A - Ultrasonic sensor, method for diagnosing abnormality in ultrasonic sensor, and method for recovering abnormality in ultrasonic sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ultrasonic sensor that facilitates determination as to whether the ultrasonic sensor itself is responsible for a malfuntion therein, and to provide a method for diagnosing an abnormality in the ultrasonic sensor and a method for recovering an abnormality in the ultrasonic sensor.SOLUTION: A piezoelectric element 2 comprises: a first lead 22; a second lead 23; and a third lead 24. Thus, the cause of any abnormality in an ultrasonic sensor can be determined by checking electrical continuity between the leads.

Description

  The present invention relates to an ultrasonic sensor provided with a piezoelectric element.

  2. Description of the Related Art Conventionally, there has been known an ultrasonic sensor that propagates ultrasonic waves to a fluid flowing in a pipe and measures a fluid flow velocity, a flow rate, and the like based on a change in the propagation speed (see, for example, Patent Document 1). . As shown in FIG. 8, the ultrasonic sensor includes a case 100 made of a conductive material and a disk-shaped piezoelectric element 200 accommodated in the case 100. The piezoelectric element 200 vibrates when a voltage is applied between the electrodes formed on the upper surface and the lower surface to become a generation source of ultrasonic waves, and can take out the voltage through the electrodes by receiving external vibration. it can. Such a piezoelectric element 200 is fixed to the inner wall surface at the bottom of the case 100 by an adhesive 300 made of epoxy resin or the like. As a result, the electrode on the bottom surface side of the piezoelectric element 200 and the case 100 are electrically connected to each other. By applying, the piezoelectric element 200 can be vibrated to generate ultrasonic waves. Further, the propagated ultrasonic wave is received by the piezoelectric element 200, and the voltage generated by the piezoelectric effect can be taken out from the lead wire 201 and the case 200.

  In such an ultrasonic sensor, the reason why the ultrasonic sensor does not operate normally includes a failure of the ultrasonic sensor itself or an abnormality in the flow path where measurement is performed by the ultrasonic sensor. The failure of the ultrasonic sensor itself is that the adhesive 300 is broken and the piezoelectric element 200 is lifted from the case 100, so that the conduction between the case 100 and the piezoelectric element 200 is cut off, or the connection portion between the electrode of the piezoelectric element 200 and the lead wire 201. May occur due to peeling off, the lead wire 201 being broken, or the piezoelectric element 200 being damaged. If the ultrasonic sensor itself fails for these reasons, it does not vibrate even when a voltage is applied to the piezoelectric element 200, and the voltage cannot be extracted even if the piezoelectric element 200 vibrates due to ultrasonic waves. On the other hand, examples of abnormalities in the flow path include a large amount of bubbles generated in the flow path and foreign substances mixed in the flow path. When such an abnormality occurs, the ultrasonic sensor does not output a normal value.

  If the ultrasonic sensor does not operate normally, accurate measurement cannot be realized. Therefore, it is necessary to take measures so that the ultrasonic sensor operates normally. At this time, ascertaining the cause of the ultrasonic sensor not operating normally is important in taking appropriate measures. Therefore, when the ultrasonic sensor stops operating normally, it is first diagnosed whether or not the ultrasonic sensor itself has failed. If it is determined that the ultrasonic sensor itself has failed, the failure In general, when the ultrasonic sensor itself has not failed, the cause of the abnormality in the flow path is determined. Here, as a method for diagnosing whether or not the ultrasonic sensor itself has failed, conventionally, an oscilloscope is used to observe a transmission / reception waveform between a pair of ultrasonic sensors, or an impedance analyzer is used. There is a method for confirming the impedance characteristics of an ultrasonic sensor.

Japanese Patent No. 4509458

  However, in the conventional method of diagnosing abnormalities in the ultrasonic sensor, special equipment such as an oscilloscope and an impedance analyzer must be prepared. However, it is difficult and impractical to bring such equipment to the site where the ultrasonic sensor is installed. Even if the cause of the abnormality can be identified, if the cause is in the ultrasonic sensor itself, it is necessary to replace it.

  Accordingly, it is a first object of the present invention to provide an ultrasonic sensor, an ultrasonic sensor abnormality diagnosis method, and an ultrasonic sensor abnormality recovery method that can easily diagnose whether or not the ultrasonic sensor itself has a cause of failure. .

  Also provided are an ultrasonic sensor, an ultrasonic sensor abnormality diagnosis method, and an ultrasonic sensor abnormality recovery method that enable measurement without replacing the ultrasonic sensor even if any failure occurs. Is the second purpose.

  In order to solve the problems as described above, an ultrasonic sensor according to the present invention is composed of a conductive material, and has a case having a cylindrical inner space with one end opened, and an inner space of the case. An ultrasonic sensor comprising a piezoelectric element fixed to the bottom, the piezoelectric element comprising a piezoelectric material plate, a positive electrode formed on one surface of the piezoelectric material plate, and the other surface of the piezoelectric material plate A negative electrode formed and electrically connected to the case, a folded electrode electrically connected to the negative electrode and extending from the other surface to one surface, and electrically insulated from the positive electrode; A first lead connected to the positive electrode on one side, a second lead connected at a location different from the location where the first lead is connected to the positive electrode on one side, and a negative electrode on one side And a third lead. .

  In addition, the abnormality diagnosis method for an ultrasonic sensor according to the present invention is made of a conductive material, and is fixed to a case having a cylindrical internal space with one end opened, and a bottom portion in the internal space of the case. The piezoelectric element includes a piezoelectric material plate, a positive electrode formed on one surface of the piezoelectric material plate, and a negative electrode formed on the other surface of the piezoelectric material plate and electrically connected to the case. A folded electrode electrically connected to the negative electrode and extending from the other surface to one surface and electrically insulated from the positive electrode, and a first lead connected to the positive electrode on the one surface An ultrasonic sensor comprising: a second lead connected at a location different from the location where the first lead is connected to the positive electrode on one surface; and a third lead connected to the negative electrode on the one surface An abnormality diagnosis method for an ultrasonic sensor A detection step for detecting whether or not an abnormality has occurred in the ultrasonic sensor by this detection step, a) confirming electrical continuity between the third lead and the case, When there is electrical continuity, it is diagnosed that there is no abnormality between the third lead and the case, while when there is no electrical continuity, it is diagnosed that there is an abnormality between the third lead and the case. A first diagnostic step; and b) checking electrical continuity between the first lead and the second lead, and if there is electrical continuity, between the first lead and the second lead. On the other hand, if there is no electrical continuity, at least one of the second diagnostic steps for diagnosing that there is an abnormality between the first lead and the second lead is performed. It is what.

  In the ultrasonic sensor abnormality diagnosis method, when it is diagnosed that there is an abnormality between the first lead and the second lead in the second diagnosis step, a voltage is applied between the case and the second lead. When the piezoelectric element is operated, it is diagnosed that there is an abnormality between the first lead and the piezoelectric element. On the other hand, when the piezoelectric element does not operate, A third diagnostic step for diagnosing an abnormality between the second lead and the piezoelectric element or in the piezoelectric element may be further included.

  Further, the abnormality recovery method of the ultrasonic sensor according to the present invention is made of a conductive material, and is fixed to a case having a cylindrical internal space with one end opened and a bottom portion in the internal space of the case. The piezoelectric element includes a piezoelectric material plate, a positive electrode formed on one surface of the piezoelectric material plate, and a negative electrode formed on the other surface of the piezoelectric material plate and electrically connected to the case. A folded electrode electrically connected to the negative electrode and extending from the other surface to one surface and electrically insulated from the positive electrode, and a first lead connected to the positive electrode on the one surface An ultrasonic sensor comprising: a second lead connected at a location different from the location where the first lead is connected to the positive electrode on one surface; and a third lead connected to the negative electrode on the one surface An abnormality recovery method for an ultrasonic sensor A first step for detecting whether or not an abnormality has occurred in the ultrasonic sensor in the first step, and confirming electrical continuity between the third lead and the case. And a third step of confirming electrical continuity between the first lead and the second lead when the second step confirms that there is electrical continuity; When it is confirmed by this third step that there is no electrical continuity, a voltage is applied between the case and the second lead to check whether the piezoelectric element operates; When the fourth step confirms that the piezoelectric element operates, the fifth step has a fifth step of connecting the second lead to the electronic circuit with the positive electrode and the case as the negative electrode. .

  According to the present invention, since the piezoelectric element includes the first lead, the second lead, and the third lead, by confirming the electrical continuity between these leads, the ultrasonic sensor itself is not damaged. It can be determined whether or not there is a cause. Moreover, when there is a cause of failure in the ultrasonic sensor itself, the cause can be determined. Furthermore, since it is possible to operate the ultrasonic sensor normally only by changing the lead connected to the electronic circuit according to the cause, the ultrasonic sensor is not replaced even if an abnormality occurs in the ultrasonic sensor. It is possible to solve the abnormality.

FIG. 1 is a cross-sectional view schematically showing a configuration of an ultrasonic sensor according to an embodiment of the present invention. FIG. 2 is a perspective view schematically showing the configuration of the piezoelectric element in the ultrasonic sensor according to the embodiment of the present invention. FIG. 3 is a diagram for explaining the operation of the ultrasonic sensor according to the embodiment of the present invention. FIG. 4 is a flowchart for explaining a failure diagnosis method in the ultrasonic sensor according to the embodiment of the present invention. FIG. 5 is a diagram for explaining a failure diagnosis method in the ultrasonic sensor according to the embodiment of the present invention. FIG. 6 is a diagram for explaining a failure diagnosis method in the ultrasonic sensor according to the embodiment of the present invention. FIG. 7 is a diagram for explaining a failure diagnosis method in the ultrasonic sensor according to the embodiment of the present invention. FIG. 8 is a cross-sectional view schematically showing a configuration example of a conventional ultrasonic sensor.

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

<Configuration of ultrasonic sensor>
As shown in FIG. 1, the ultrasonic sensor according to the present embodiment includes a case 1 and a disk-shaped piezoelectric element 2, and the piezoelectric element 2 is fixed inside the case 1 with an adhesive 3. .

  The case 1 is made of a conductive material such as stainless steel, and has a cylindrical internal space that is open at one end. The piezoelectric element 2 is fixed to the inner wall surface of the bottom 1 b facing the opening 1 a of the case 1 with an adhesive 3.

  The piezoelectric element 2 includes a disk-shaped piezoelectric plate 21 sandwiched between two electrodes 21a and 21b. On the lower surface of the piezoelectric plate 21 facing the bottom of the case 1, a negative electrode 21b is formed over the entire surface. On the other hand, as shown in FIG. 2, a positive electrode 21a is formed on the upper surface of the piezoelectric plate 21 except for a part thereof, and a folded electrode electrically connected to the negative electrode 21b on the lower surface is formed on a part thereof. 21b 'is formed. That is, the negative electrode 21 b formed over almost the entire lower surface is formed to extend to the upper surface through the side surface of the piezoelectric element 2. On this upper surface, the folded electrode 21b 'is spaced apart from the positive electrode 21a by a predetermined distance, and is insulated from the positive electrode 21a. A first lead 22 and a second lead 23 are connected to the cathode 21a on the upper surface at a position separated from each other. On the other hand, the third lead 24 is connected to the negative electrode 21b on the upper surface. In the present embodiment, by providing the folded electrode 21b ′, it is possible to connect the lead wire from only the upper surface of the piezoelectric element 2 to the positive electrode 21a and the negative electrode 21b by having such a folded electrode configuration. Become. In FIG. 1 and the like, the thicknesses of the positive electrode 21a, the negative electrode 21b, and the folded electrode 21b 'are shown large for the sake of explanation, but in actuality, these thicknesses are extremely small.

  The adhesive 3 is made of a known adhesive having conductivity, such as an epoxy resin, and electrically connects the case 1 and the negative electrode 21 b of the piezoelectric element 2.

<Operation of ultrasonic sensor>
Next, the operation of the ultrasonic sensor according to the present embodiment will be described.

  First, when an ultrasonic wave is transmitted by an ultrasonic sensor, as shown in FIG. 3, one of the first lead 22 and the second lead 23 connected to the positive electrode 21a of the piezoelectric element 2 (hereinafter simply referred to as “simple”). Therefore, the first lead 22 will be described as an example.) Is connected to the power supply circuit with the positive electrode and the case 1 as the negative electrode, and a voltage is applied. The case 1 is made of a conductive material, and the adhesive 3 that bonds the inner wall surface of the bottom of the case 1 and the lower surface of the piezoelectric element 2, that is, the negative electrode 21b, is also made of a conductive material. Therefore, when a voltage is applied between the positive electrode 21 a and the negative electrode 21 b of the piezoelectric plate 21, the piezoelectric plate 21 vibrates and ultrasonic waves are transmitted from the bottom of the case 1.

  On the other hand, when ultrasonic waves are received by the ultrasonic sensor, first, the first lead 22 is connected to the voltage detection circuit with the positive electrode and the case 1 as the negative electrode. In this state, when the ultrasonic wave reaches the bottom of the case 1, the vibration of the ultrasonic wave is converted into a change in voltage by the piezoelectric plate 21 that receives pressure by the ultrasonic wave. This voltage is detected by the voltage detection circuit via the first lead 22 connected to the positive electrode 21a and the case 1 connected to the negative electrode 21b via the adhesive 3.

<Fault diagnosis method for ultrasonic sensors>
Next, an ultrasonic sensor failure diagnosis method according to the present embodiment will be described with reference to FIG.

  Normally, as described above, the first lead 22 is the positive electrode and the case 1 is the negative electrode, a voltage is applied between them, or the voltage between them is detected, and an abnormality occurs in the ultrasonic sensor. It is confirmed whether or not (step S1). In such a case, if it is detected that an abnormality has occurred in the ultrasonic sensor, such as no ultrasonic wave is output from the piezoelectric element 2 or an abnormal voltage value is detected (step S1: YES), As shown in FIG. 5, electrical continuity between the case 1 and the third lead 24 is confirmed by a tester or the like (step S2). As described above, the case 1 is connected to the negative electrode 21 b formed on the lower surface of the piezoelectric plate 21 via the adhesive 3. The third lead 24 is connected to a folded electrode 21 b ′ formed on the upper surface of the piezoelectric plate 21 by a folded electrode structure. Therefore, by confirming electrical continuity between the case 1 and the third lead 24, an abnormality occurs between them, that is, between the case 1, the adhesive 3, the negative electrode 21b, and the third lead 24. It can be confirmed whether or not.

  If the electrical continuity between the case 1 and the third lead 24 cannot be confirmed (step S2: NO), it is determined that an abnormality has occurred between them (step S3). Examples of abnormalities in this case include poor adhesion between the case 1 and the piezoelectric plate 21, poor connection between the third lead 24 and the negative electrode 21 b, and disconnection of the third lead 24. In this case, the replacement of the ultrasonic sensor itself will be considered.

  On the other hand, when the electrical continuity between the case 1 and the third lead 24 can be confirmed (step S2: YES), it is determined that there is no abnormality between them (step S4). Next, as shown in FIG. 6, electrical continuity between the first lead 22 and the second lead 23 is confirmed by a tester or the like (step S5). As described above, the first lead 22 and the second lead 23 are connected to the positive electrode 21 a on the upper surface of the piezoelectric plate 21. Therefore, by confirming the electrical continuity between the first lead 22 and the second lead 23, there is an abnormality between them, that is, between the first lead 22, the positive electrode 21 a, and the second lead 23. It is possible to confirm whether or not the error has occurred.

  If the electrical continuity between the first lead 22 and the second lead 23 can be confirmed (step S5: YES), it is determined that there is no abnormality between them (step S6). As a result, it was confirmed that there was no abnormality between the case 1 and the third lead 24 and between the first lead 22 and the second lead 23. It can be considered that an abnormality has occurred.

  On the other hand, when the electrical continuity between the first lead 22 and the second lead 23 cannot be confirmed (step S5: NO), it can be determined that an abnormality has occurred between them. Therefore, in order to determine which of the first lead 22 and the second lead 23 is abnormal, as shown in FIG. 7, the second lead 23 is a positive electrode and the case 1 is a negative electrode. In the meantime, a voltage is applied by connecting to the power supply circuit to check whether the ultrasonic sensor operates normally (step S7). As described above, the case 1 is connected to the negative electrode 21 b formed on the lower surface of the piezoelectric plate 21 via the conductive adhesive 3. The second lead 23 is connected to the positive electrode 21 a formed on the upper surface of the piezoelectric plate 21. Therefore, when there is no abnormality in the second lead 23 or its contact point, when a voltage is applied between the case 1 and the second lead 23, the voltage between the positive electrode 21a and the negative electrode 21b of the piezoelectric plate 21 is Is applied, the piezoelectric plate 21 vibrates and ultrasonic waves are transmitted from the bottom of the case 1. Therefore, when the first lead 22 and the second lead 23 are respectively selected as the positive electrodes, either the first lead 22 or the second lead 23 is determined depending on whether an ultrasonic wave is output from the ultrasonic sensor. It can be determined whether an abnormality has occurred. Here, whether or not an ultrasonic wave is output from the ultrasonic sensor can be easily detected by, for example, an equivalent ultrasonic sensor that has already been arranged to face the flow rate or the like.

  When an ultrasonic wave is output from the ultrasonic sensor (step S7: YES), no abnormality has occurred in the second lead 23 or its contact, that is, an abnormality has occurred in the first lead or its contact. (Step S8). Examples of this abnormality include disconnection of the first lead 22 and poor connection between the first lead 22 and the positive electrode 21a. In such a case, the ultrasonic sensor can be operated normally by using the second lead 23 as the positive electrode instead of the first lead 22. Thus, it can be said that the ultrasonic sensor according to the present embodiment has redundancy.

  If no ultrasonic wave is output from the ultrasonic sensor (step S7: NO), an abnormality has occurred in the second lead 23 or its contact or the piezoelectric plate 21, that is, the first lead or its contact. It is determined that no abnormality has occurred (step S9). Examples of the abnormality include a connection failure between the second lead 23 and the positive electrode 21a, a disconnection of the second lead 23, and the like.

  As described above, according to the present embodiment, the piezoelectric element 2 includes the first lead 22, the second lead 23, and the third lead 24, thereby providing electrical continuity between these leads. By checking, the cause of the abnormality occurring in the ultrasonic sensor can be ascertained. In addition, the ultrasonic sensor can be operated normally only by changing the lead connected to the electronic circuit according to the cause, so the ultrasonic sensor can be replaced even if an abnormality occurs in the ultrasonic sensor. It is possible to solve the abnormality without doing so.

  In the present embodiment, the electrical continuity between the case 1 and the third lead 24 is confirmed, the electrical continuity between the first lead 22 and the second lead 23 is confirmed, and the case and the second lead 23 are confirmed. The case where the cause of the abnormality of the ultrasonic sensor is ascertained in the order of applying the voltage between the lead 23 and the lead 23 has been described as an example, but the order is not limited to this, and it is needless to say that the order can be set as appropriate. Moreover, not only in that order, but also in the case where at least one cause is determined by any procedure, all procedures may be performed. All causes can be determined.

  Further, in the present embodiment, the case where the piezoelectric plate 21 has a disc shape has been described as an example, but the shape is not limited to the disc shape and can be freely set as appropriate.

  Furthermore, in the present embodiment, the case where the piezoelectric element 2 is fixed to the case 1 with the conductive adhesive 3 has been described as an example, but the method of fixing the piezoelectric element 2 to the case 1 is not limited to this. Various methods can be used. For example, you may make it fix the piezoelectric element 2 to the case 1 with the adhesive agent which does not have electroconductivity. In this case, the adhesive layer may be made thin to such an extent that the negative electrode 21b of the piezoelectric element 2 and the bottom 1b of the case 1 are in point contact. Further, the piezoelectric element 2 may be fixed to the case 1 with a brazing material. Also by adopting these methods, conduction between the piezoelectric element 2 and the case 1 can be realized.

  The present invention can be applied to various apparatuses as long as the apparatus has a piezoelectric element such as an ultrasonic sensor.

  DESCRIPTION OF SYMBOLS 1 ... Case, 1a ... Opening, 1b ... Bottom part, 2 ... Piezoelectric element, 3 ... Adhesive, 21 ... Piezoelectric board, 21a ... Positive electrode, 21b ... Negative electrode, 21b '... Folded electrode, 22 ... First lead, 23 ... second lead, 24 ... third lead.

Claims (4)

An ultrasonic sensor comprising a case made of a conductive material and having a cylindrical internal space with one end opened, and a piezoelectric element fixed to the bottom of the internal space of the case,
The piezoelectric element is
A piezoelectric material plate;
A positive electrode formed on one surface of the piezoelectric material plate;
A negative electrode formed on the other surface of the piezoelectric material plate and electrically connected to the case;
A folded electrode electrically connected to the negative electrode and extending from the other surface to the one surface, and electrically insulated from the positive electrode;
A first lead connected to the positive electrode on the one surface, a second lead connected at a location different from the location where the first lead is connected to the positive electrode on the one surface, and the one An ultrasonic sensor comprising: a third lead connected to the negative electrode of the surface. A case made of a conductive material and having a cylindrical internal space with one end opened, and a piezoelectric element fixed to the bottom of the internal space of the case, the piezoelectric element comprising: a piezoelectric material plate; The positive electrode formed on one surface of the piezoelectric material plate, the negative electrode formed on the other surface of the piezoelectric material plate and electrically connected to the case, and the negative electrode electrically connected to the negative electrode A folded electrode extending from the other surface to the one surface and electrically insulated from the positive electrode, a first lead connected to the positive electrode on the one surface, and the one surface on the one surface Abnormality of an ultrasonic sensor including a second lead connected to a positive electrode at a location different from a location where the first lead is connected, and a third lead connected to the negative electrode on the one surface A diagnostic method,
A detection step of detecting whether an abnormality has occurred in the ultrasonic sensor;
When it is detected by this detection step that an abnormality has occurred in the ultrasonic sensor,
a) Confirming electrical continuity between the third lead and the case, and if there is electrical continuity, diagnosing that there is no abnormality between the third lead and the case, A first diagnostic step for diagnosing that there is an abnormality between the third lead and the case when there is no electrical continuity; and
b) Confirming electrical continuity between the first lead and the second lead, and if there is electrical continuity, there is no abnormality between the first lead and the second lead. On the other hand, if there is no electrical continuity, at least one of a second diagnostic step of diagnosing that there is an abnormality between the first lead and the second lead is performed. Abnormal diagnosis method for ultrasonic sensors. When it is diagnosed by the second diagnosis step that there is an abnormality between the first lead and the second lead, a voltage is applied between the case and the second lead, and the piezoelectric Check whether the element operates, and if the piezoelectric element operates, diagnose that there is an abnormality between the first lead and the piezoelectric element, but if the piezoelectric element does not operate The method for diagnosing abnormality of an ultrasonic sensor according to claim 2, further comprising a third diagnosis step of diagnosing that there is an abnormality between the second lead and the piezoelectric element or in the piezoelectric element. A case made of a conductive material and having a cylindrical internal space with one end opened, and a piezoelectric element fixed to the bottom of the internal space of the case, the piezoelectric element comprising: a piezoelectric material plate; The positive electrode formed on one surface of the piezoelectric material plate, the negative electrode formed on the other surface of the piezoelectric material plate and electrically connected to the case, and the negative electrode electrically connected to the negative electrode A folded electrode extending from the other surface to the one surface and electrically insulated from the positive electrode, a first lead connected to the positive electrode on the one surface, and the one surface on the one surface Abnormality of an ultrasonic sensor including a second lead connected to a positive electrode at a location different from a location where the first lead is connected, and a third lead connected to the negative electrode on the one surface A recovery method,
A first step of detecting whether an abnormality has occurred in the ultrasonic sensor;
A second step of confirming electrical continuity between the third lead and the case when it is detected that an abnormality has occurred in the ultrasonic sensor in the first step;
When it is confirmed that there is electrical continuity by this second step, a third step of confirming electrical continuity between the first lead and the second lead;
When it is confirmed that there is no electrical continuity in the third step, a voltage is applied between the case and the second lead to check whether the piezoelectric element operates. Steps,
When the fourth step confirms that the piezoelectric element operates, a fifth step of connecting the second lead to the electronic circuit with the positive electrode and the case as the negative electrode is provided. To recover abnormality of ultrasonic sensor.

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