JP2010237035A - Apparatus and method for diagnosing valve rod of valve device - Google Patents

Apparatus and method for diagnosing valve rod of valve device Download PDF

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JP2010237035A
JP2010237035A JP2009085262A JP2009085262A JP2010237035A JP 2010237035 A JP2010237035 A JP 2010237035A JP 2009085262 A JP2009085262 A JP 2009085262A JP 2009085262 A JP2009085262 A JP 2009085262A JP 2010237035 A JP2010237035 A JP 2010237035A
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valve stem
wave
valve
probe
ultrasonic probe
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JP5232061B2 (en
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Yoshihiro Yamashita
善弘 山下
Kazumi Watabe
和美 渡部
Keiichi Sasaki
恵一 佐々木
Atsushi Chihoshi
淳 千星
Shunichi Shimizu
俊一 清水
Koji Hikuma
幸治 日隈
Tomohito Nakano
智仁 中野
Kotaro Sogi
幸太郎 枌
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Toshiba Corp
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Abstract

<P>PROBLEM TO BE SOLVED: To quickly and effectively detect a defect of a valve rod of a valve device, which may lead to breakage, before resulting in the breakage. <P>SOLUTION: An apparatus includes an electromagnetic ultrasonic probe (transverse wave EMAT probe 23) installed on a side face 36 of the valve rod 16 of a motor-driven valve which drives the valve rod 16 having a valve body 15 at an end thereof in an axial direction to make the valve body perform opening/closing, and for exciting and propagating an ultrasonic wave (transverse SH wave 23A) at the valve rod 16 by an electromagnetic force, and detecting the ultrasonic wave to be reflected from the defect 41 of the valve rod 16 as a reflected wave; a high-frequency power supply 29 supplying to this transverse wave EMAT probe 23 a high-frequency current for exciting the ultrasonic wave; and a processing section 35 computing a state of the defect 41 of the valve rod 16, using a time difference between the excitation of the ultrasonic wave by the transverse EMAT probe 23 and the detection of the reflected wave, based on a potential difference caused at a high-frequency coil 40 constituting the transverse wave EMAT probe 23. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

本発明は、電磁力により弁棒に超音波を励起して、この弁棒に生じた欠陥を検出する電磁超音波探触子を備えた弁装置の弁棒診断装置及び方法に関する。   The present invention relates to a valve stem diagnostic apparatus and method for a valve device provided with an electromagnetic ultrasonic probe that excites ultrasonic waves on a valve stem by electromagnetic force and detects defects generated in the valve stem.

原子力及び火力発電プラント等の配管に設置される電動弁や空気作動弁等の弁装置における弁棒の超音波診断は、弁装置を分解することなく実施できることから、弁棒折損によるプラントの計画外停止を事前に回避し、弁棒による故障を予防してプラント稼動率を改善することができる。特に、プラントの計画外停止及びプラント再起動に多くの時間と費用を要する原子力発電プラントでは、大きな経済的効果を奏する。   Ultrasound diagnosis of valve stems in valve devices such as motor-operated valves and pneumatically operated valves installed in piping of nuclear power plants and thermal power plants can be performed without disassembling the valve devices. The plant operation rate can be improved by avoiding the stop in advance and preventing the failure due to the valve stem. In particular, a nuclear power plant that requires a lot of time and cost for unplanned shutdown and restart of the plant has a great economic effect.

また近年、発電設備やエネルギー伝送ライン等の社会インフラの経年劣化が大きな問題になっている。劣化による損傷が一旦発生すると、経済的・社会的損失が大きく、特に１９６０年代から１９７０年代の高度成長期に建設されたプラントの主要部品の多くは、４０年近い劣化と損傷が進んでいることが想定される。このことから、近年圧電セラミックを用いた接触式超音波探触子による欠陥診断が各種プラントで広く適用されており、この欠陥診断は、経年プラントの稼働率向上を目指すプラント運用の要になりつつある。   In recent years, aging of social infrastructure such as power generation facilities and energy transmission lines has become a major problem. Once damage due to deterioration occurs, economic and social losses are significant, and many of the major parts of the plant constructed during the high-growth period of the 1960s and 1970s have been deteriorated and damaged for nearly 40 years. Is assumed. For this reason, in recent years, defect diagnosis using contact-type ultrasonic probes using piezoelectric ceramics has been widely applied in various plants, and this defect diagnosis is becoming the key to plant operations aimed at improving the operating rate of aged plants. is there.

超音波診断の特徴は、検査対象物に接触する圧電セラミックもしくは高分子の圧電素子により超音波を励起して伝播し、欠陥部分からの反射波を接触式超音波探触子により受信して検出し、欠陥の有無を診断する。しかし、現場においては、超音波の伝播に必要な種々の形状や寸法の探触子や、この接触子を接着させるための接着治具が必要であり、更に超音波伝播のＳ/Ｎ比を確保するためのカプラント（接触媒体）が必要になるため、これらの選定に多くの工数と時間を要し、このためコストが上昇して、プラントの運用面から改善が求められている。   Ultrasonic diagnostics are characterized by exciting and propagating ultrasonic waves with a piezoelectric ceramic or polymer piezoelectric element in contact with the object to be inspected, and receiving and detecting reflected waves from the defective part with a contact ultrasonic probe. Then, the presence or absence of defects is diagnosed. However, in the field, probes of various shapes and dimensions necessary for the propagation of ultrasonic waves and bonding jigs for bonding these contacts are required, and the S / N ratio of ultrasonic propagation is further increased. Since a plant (contact medium) for securing is required, it takes a lot of man-hours and time for the selection, which increases the cost and requires improvement from the operational aspect of the plant.

ところで、運転中のプラントにおける電動弁等の弁装置を診断することにより、プラントの計画外停止を予防し稼働率を改善する技術が特許文献１及び２に記載されており、産業界では一部実施されているものがある。これら両特許は、電動弁駆動時のモータの駆動トルクや駆動電流・電圧を検出して、弁駆動の健全性から弁装置を診断するもの等である。   By the way, Patent Documents 1 and 2 describe techniques for preventing unplanned stoppage of a plant and improving the operation rate by diagnosing a valve device such as an electric valve in an operating plant. Some have been implemented. Both of these patents, for example, detect the driving torque, driving current and voltage of the motor when driving the electric valve, and diagnose the valve device from the soundness of the valve driving.

特表２００５−５０２８２４号公報JP-T-2005-502824 特開２００５−３０８５４０号公報JP 2005-308540 A

このように、特許文献１及び２に記載の診断技術は、弁棒駆動系の劣化は検出できても、弁棒折損事象を直接検出するものではないため、初期に発生したき裂等の欠陥が運転期間中に序々に進展して疲労折損に至る弁棒の故障を、弁棒折損前に有効に検出することは不可能である。   As described above, the diagnostic techniques described in Patent Documents 1 and 2 do not directly detect the valve stem breakage event even though the deterioration of the valve stem drive system can be detected. However, it is impossible to effectively detect the failure of the valve stem that gradually progresses during the operation period and leads to fatigue breakage before the valve stem breakage.

本発明の目的は、上述の事情を考慮してなされたものであり、弁装置の弁棒に生じた折損に至る欠陥を、折損前に迅速且つ有効に検出できる弁装置の弁棒診断装置及び方法を提供することにある。   An object of the present invention has been made in consideration of the above-mentioned circumstances, and a valve rod diagnostic device for a valve device capable of quickly and effectively detecting a defect leading to breakage occurring in the valve rod of the valve device, and It is to provide a method.

本発明に係る弁装置の弁棒診断装置は、先端に弁体が設けられた弁棒を軸方向に駆動して、前記弁体に開閉動作を行わせる弁装置の前記弁棒の表面に設置され、電磁力により超音波を前記弁棒に励起して伝播させると共に、前記弁棒に生じた欠陥から反射する超音波を反射波として検出可能な電磁超音波探触子と、この電磁超音波探触子に超音波を励起させるための高周波電流を供給する高周波電源と、前記電磁超音波探触子を構成する高周波コイルに生じた電位差に基づき、前記電磁超音波探触子が超音波を励起してから反射波を検出するまでの時間差を用いて、前記弁棒における前記欠陥の状態を演算処理する処理部と、を有することを特徴とするものである。   A valve stem diagnostic apparatus for a valve device according to the present invention is installed on the surface of the valve stem of a valve device that drives a valve rod, which is provided with a valve body at the tip, in an axial direction to cause the valve body to open and close. An electromagnetic ultrasonic probe capable of exciting and propagating ultrasonic waves to the valve stem by electromagnetic force and detecting ultrasonic waves reflected from defects generated on the valve stem as reflected waves, and the electromagnetic ultrasonic wave Based on a high-frequency power source that supplies a high-frequency current for exciting ultrasonic waves to the probe and a potential difference generated in a high-frequency coil that constitutes the electromagnetic ultrasonic probe, the electromagnetic ultrasonic probe generates ultrasonic waves. And a processing unit that performs arithmetic processing on the state of the defect in the valve stem by using a time difference from when the reflected wave is detected to when the reflected wave is detected.

また、本発明に係る弁装置の弁棒診断方法は、先端に弁体が設けられた弁棒を軸方向に駆動して、前記弁体に開閉動作を行わせる弁装置の前記弁棒の表面に電磁超音波探触子を設置して、電磁力により前記弁棒に超音波を励起させて伝播させ、前記弁棒に生じた欠陥から反射する超音波を反射波として検出し、前記電磁超音波探触子が超音波を励起してから反射波を検出するまでの時間差を用いて、前記弁棒における前記欠陥の状態を演算することを特徴とするものである。   The valve stem diagnosis method for a valve device according to the present invention also includes a valve stem surface of the valve device that drives a valve stem, which is provided with a valve body at a tip, in an axial direction to cause the valve body to open and close. An electromagnetic ultrasonic probe is installed on the valve stem, and the valve stem is excited and propagated by electromagnetic force to detect the ultrasonic wave reflected from the defect generated in the valve stem as a reflected wave. The state of the defect in the valve stem is calculated using a time difference from when the acoustic probe excites the ultrasonic wave until the reflected wave is detected.

本発明によれば、弁装置の弁棒に生じた折損に至る欠陥を、電磁超音波探触子を用いて検出するので、弁棒の折損前に、この欠陥を迅速且つ有効に検出できる。   According to the present invention, since the defect that causes breakage in the valve stem of the valve device is detected using the electromagnetic ultrasonic probe, this defect can be detected quickly and effectively before the valve stem is broken.

本発明に係る弁装置の弁棒診断装置における一実施の形態が適用される弁装置としての電動弁を、横波電磁超音波探触子及び縦波電磁超音波探触子と共に示す斜視図。The perspective view which shows the motor operated valve as a valve apparatus with which one Embodiment in the valve-rod diagnostic apparatus of the valve apparatus which concerns on this invention is applied with a transverse wave electromagnetic ultrasonic probe and a longitudinal wave electromagnetic ultrasonic probe. 図１の横波電磁超音波探触子を用いた弁棒診断装置を示す構成斜視図。The composition perspective view showing the valve stem diagnostic device using the transverse wave electromagnetic ultrasonic probe of Drawing 1. 図１の縦波電磁超音波探触子を用いた弁棒診断装置を示す構成斜視図。The composition perspective view showing the valve stem diagnostic device using the longitudinal wave electromagnetic ultrasonic probe of Drawing 1. 図２及び図３の弁棒診断装置の構成を更に詳細に示す模式図。The schematic diagram which shows the structure of the valve-rod diagnostic apparatus of FIG.2 and FIG.3 in detail. 図２の横波電磁超音波探触子を用いた弁棒診断装置にて検出された反射波を表す電位差を示すグラフ。The graph which shows the electric potential difference showing the reflected wave detected with the valve-rod diagnostic apparatus using the transverse wave electromagnetic ultrasonic probe of FIG. 図３の縦波電磁超音波探触子を用いた弁棒診断装置にて検出された反射波を表す電位差を示すグラフ。The graph which shows the electric potential difference showing the reflected wave detected with the valve-rod diagnostic apparatus using the longitudinal wave electromagnetic ultrasonic probe of FIG. 図２の弁棒診断装置が、弁体と一体化された弁棒に適用された場合の一部を示す斜視図。The perspective view which shows a part at the time of the valve stem diagnostic apparatus of FIG. 2 being applied to the valve stem integrated with the valve body.

以下、本発明を実施するための最良の形態を、図面に基づき説明する。   The best mode for carrying out the present invention will be described below with reference to the drawings.

図１は、本発明に係る弁装置の弁棒診断装置における一実施の形態が適用される弁装置としての電動弁を、横波電磁超音波探触子及び縦波電磁超音波探触子と共に示す斜視図である。この図１に示す弁装置としての電動弁１０は、弁体収納部１１、弁体駆動部１２、駆動量制御機構部１３及びヨーク１４を有して構成される。   FIG. 1 shows a motor-operated valve as a valve device to which an embodiment of a valve stem diagnostic device for a valve device according to the present invention is applied, together with a transverse electromagnetic ultrasonic probe and a longitudinal electromagnetic ultrasonic probe. It is a perspective view. The motor-operated valve 10 as the valve device shown in FIG. 1 includes a valve body storage portion 11, a valve body drive portion 12, a drive amount control mechanism portion 13, and a yoke 14.

弁体収納部１１は、図示しない配管に接続される。この弁体収納部１１には、弁棒１６の先端に設けられた弁体１５が、弁体収納部１１の流路を開閉し得るように収納されている。また、弁体駆動部１２は、モータ１７の回転駆動力をギア部１８により減速して弁棒１６へ伝達し、この弁棒１６を軸方向に昇降駆動して弁体１５に開閉動作を行なわせ、弁体収納部１１内を流れる流体の流量を制御する。   The valve body storage part 11 is connected to piping which is not shown in figure. In the valve body storage section 11, a valve body 15 provided at the tip of the valve rod 16 is stored so that the flow path of the valve body storage section 11 can be opened and closed. Further, the valve body drive unit 12 decelerates the rotational driving force of the motor 17 by the gear unit 18 and transmits it to the valve stem 16, and drives the valve rod 16 up and down in the axial direction to open and close the valve body 15. The flow rate of the fluid flowing through the valve body storage unit 11 is controlled.

駆動量制御機構部１３は、リミットスイッチ１９及びトルクスイッチ２０を備える。リミットスイッチ１９は、弁棒１６の回転量からこの弁棒１６の昇降駆動量（軸方向ストローク）を検出して、弁体１５の開度を検知する。トルクスイッチ２０は、ギア部１８の図示しないウォームギアに作用するトルクを検出して、弁体１５の全開位置または全閉位置を検知する。このようにしてリミットスイッチ１９及びトルクスイッチ２０が弁体１５の位置を検知することで、駆動量制御機構部１３は、弁棒１６の昇降駆動量を制御して、弁体１５の開閉動作を制御する。   The drive amount control mechanism unit 13 includes a limit switch 19 and a torque switch 20. The limit switch 19 detects the opening / closing drive amount (axial stroke) of the valve stem 16 from the rotation amount of the valve stem 16 to detect the opening degree of the valve body 15. The torque switch 20 detects a torque acting on a worm gear (not shown) of the gear unit 18 and detects the fully open position or the fully closed position of the valve body 15. Thus, when the limit switch 19 and the torque switch 20 detect the position of the valve body 15, the drive amount control mechanism unit 13 controls the drive amount of the valve rod 16 to open and close the valve body 15. Control.

ヨーク１４は、弁体収納部１１と弁体駆動部１２とを連結するものである。このヨーク１４には開口２１が形成され、これにより弁棒１６の一部が外部に露出して、弁棒１６に外部露出部２２が生ずる。   The yoke 14 connects the valve body storage part 11 and the valve body drive part 12. An opening 21 is formed in the yoke 14, whereby a part of the valve stem 16 is exposed to the outside, and an external exposed portion 22 is generated in the valve stem 16.

弁棒１６には、前記の如く、モータ１７の回転駆動力が、ギア部１８により減速され増大して繰り返し作用することから、この弁棒１６に疲労欠陥が発生し、最終的にき裂が進展して弁棒１６が折損する事態を引き起こす場合がある。本実施の形態の弁棒診断装置は、この弁棒１６に生じた欠陥を、弁棒１６の折損前に迅速かつ有効に検出するものであり、横波電磁超音波探触子（以下、横波ＥＭＡＴ探触子と称する）２３を用いた弁棒診断装置２４（図２）と、縦波電磁超音波探触子（以下、縦波ＥＭＡＴ探触子と称する）２５を用いた弁棒診断装置２６（図３）とを有する。   As described above, the rotational driving force of the motor 17 is decelerated and increased by the gear portion 18 and repeatedly acts on the valve stem 16, so that a fatigue defect occurs in the valve stem 16 and eventually cracks occur. There is a case where the valve stem 16 breaks down and breaks. The valve stem diagnostic apparatus according to the present embodiment detects a defect generated in the valve stem 16 quickly and effectively before the valve stem 16 breaks. A transverse wave electromagnetic ultrasonic probe (hereinafter, transverse wave EMAT) is detected. A valve stem diagnostic device 24 using a probe 23) (FIG. 2) and a valve stem diagnostic device 26 using a longitudinal electromagnetic ultrasonic probe (hereinafter referred to as a longitudinal EMAT probe) 25. (FIG. 3).

弁棒診断装置２４は、図２及び図４に示すように、横波マット探触子２３のほかに、高周波発生部２７及び送信アンプ２８を備えた高周波電源２９と、電位差計３０と、バンドパスフィルタ３１、プリアンプ３２、ＡＤ変換器３３及びデータ処理システム３４を備えた処理部３５と、を有して構成される。また、前記弁棒診断装置２６は、縦波ＥＭＡＴ探触子２５のほか、弁棒診断装置２４と同様に、高周波電源２９、電位差計３０及び処理部３５を有して構成される。   As shown in FIGS. 2 and 4, the valve stem diagnostic device 24 includes a high-frequency power source 29 including a high-frequency generator 27 and a transmission amplifier 28, a potentiometer 30, a bandpass, in addition to the transverse wave mat probe 23. And a processing unit 35 including a filter 31, a preamplifier 32, an AD converter 33, and a data processing system 34. In addition to the longitudinal wave EMAT probe 25, the valve stem diagnostic device 26 includes a high frequency power supply 29, a potentiometer 30 and a processing unit 35, similar to the valve rod diagnostic device 24.

横波ＥＭＡＴ探触子２３は、図２に示すように、弁棒１６の表面である側面３６の外部露出部２２に設置され、この側面３６に垂直な方向の定常磁場３７を生じさせる永久磁石３８と、この永久磁石３８の外周に巻き付けられ、高周波電源２９から供給されるパルス変調された高周波電流によって、弁棒１６の側面３６に定常磁場３７に直交し高周波振動する渦電流３９を発生する高周波コイル４０と、を有してなる。   As shown in FIG. 2, the transverse wave EMAT probe 23 is installed on the externally exposed portion 22 of the side surface 36 that is the surface of the valve stem 16, and a permanent magnet 38 that generates a stationary magnetic field 37 in a direction perpendicular to the side surface 36. And a high frequency that is wound around the outer periphery of the permanent magnet 38 and generates an eddy current 39 that oscillates at a high frequency perpendicular to the stationary magnetic field 37 on the side surface 36 of the valve rod 16 by a pulse-modulated high frequency current supplied from a high frequency power supply 29. A coil 40.

尚、弁棒１６がクロム系鋼またはマルテンサイト系ステンレス鋼の場合には、横波ＥＭＡＴ探触子２３は、永久磁石３８の磁力によって弁棒１６の側面３６に磁着される。それ以外の場合には、横波ＥＭＡＴ探触子２３は、図示しない取付バンドや、柔軟で形状追従性に富む接着治具（例えばソフトシュー）を用いて弁棒１６の側面３６に取り付けられる。   When the valve stem 16 is chrome steel or martensitic stainless steel, the transverse wave EMAT probe 23 is magnetically attached to the side surface 36 of the valve stem 16 by the magnetic force of the permanent magnet 38. In other cases, the transverse wave EMAT probe 23 is attached to the side surface 36 of the valve stem 16 by using an attachment band (not shown) or an adhesive jig (for example, soft shoe) that is flexible and has good shape following ability.

定常磁場３７と渦電流３９とが直交するため、これらによって弁棒１６の側面３６に、周期的に振動する電磁力（ローレンツ力）が発生し、この電磁力により弁棒１６の側面３６にパルス状の超音波である横波のＳＨ波２３Ａが励起され、このＳＨ波２３Ａが弁棒１６の軸方向に伝播する。ここで、ＳＨ波２３Ａは、横波のうち弁棒１６の表面に沿って水平方向に振動する波である。   Since the stationary magnetic field 37 and the eddy current 39 are orthogonal, an electromagnetic force (Lorentz force) that periodically oscillates is generated on the side surface 36 of the valve stem 16, and the electromagnetic force causes a pulse on the side surface 36 of the valve stem 16. The transverse wave SH wave 23 </ b> A, which is an ultrasonic wave, is excited, and this SH wave 23 </ b> A propagates in the axial direction of the valve stem 16. Here, the SH wave 23 </ b> A is a wave that oscillates in the horizontal direction along the surface of the valve rod 16 of the transverse wave.

このパルス状の横波のＳＨ波１３Ａは、弁棒１６に生じた欠陥４１により反射してパルス状の反射波になり、伝播ルートを戻る。この反射波は、横波ＥＭＡＴ探触子２３の永久磁石３８及び高周波コイル４０を振動させ、電磁誘導の作用で高周波コイル４０に電位差を発生させることで検出される。この電位差が電位差計３０により計測される。前記欠陥４１は、通常弁棒１６の半径方向に延び、その長さ寸法は数百μｍ以上である。   The pulsed shear wave 13A is reflected by the defect 41 generated in the valve stem 16 to become a pulsed reflected wave and returns to the propagation route. This reflected wave is detected by causing the permanent magnet 38 and the high-frequency coil 40 of the transverse wave EMAT probe 23 to vibrate and generating a potential difference in the high-frequency coil 40 by the action of electromagnetic induction. This potential difference is measured by the potentiometer 30. The defect 41 usually extends in the radial direction of the valve stem 16 and has a length dimension of several hundred μm or more.

縦波ＥＭＡＴ探触子２５は、図３に示すように、弁棒１６の表面である頂面４２に設置され、この頂面４２に平行な定常磁場４３を生じさせる一対の永久磁石４４と、これら一対の永久磁石４４間に配置されて、高周波電源２９から供給されるパルス変調された高周波電流によって、弁棒１６の頂面４２に、定常磁場４３に直交し高周波振動する渦電流４５を発生する高周波コイル４６と、を有してなる。   As shown in FIG. 3, the longitudinal wave EMAT probe 25 is installed on a top surface 42 that is a surface of the valve stem 16, and a pair of permanent magnets 44 that generate a stationary magnetic field 43 parallel to the top surface 42. An eddy current 45 that is arranged between the pair of permanent magnets 44 and that oscillates at a high frequency perpendicular to the stationary magnetic field 43 is generated on the top surface 42 of the valve rod 16 by a pulse-modulated high-frequency current supplied from a high-frequency power supply 29. High-frequency coil 46.

尚、この縦波ＥＭＡＴ探触子２５も、弁棒１６がクロム系鋼またはマルテンサイト系ステンレス鋼の場合に、永久磁石４４の磁力により弁棒１６の頂面４２に磁着される。それ以外の場合には、縦波ＥＭＡＴ探触子２５は、図示しない取付バンドや、柔軟で形状追従性に富む接着治具（例えばソフトシュー）を用いて弁棒１６の頂面４２に取り付けられる。   The longitudinal wave EMAT probe 25 is also magnetically attached to the top surface 42 of the valve stem 16 by the magnetic force of the permanent magnet 44 when the valve stem 16 is made of chromium steel or martensitic stainless steel. In other cases, the longitudinal wave EMAT probe 25 is attached to the top surface 42 of the valve stem 16 using an attachment band (not shown) or an adhesive jig (for example, a soft shoe) that is flexible and has a good shape following ability. .

定常磁場４３と渦電流４５とが直交するため、これらによって弁棒４６の頂面４２に、周期的に振動する電磁力（ローレンツ力）が発生し、この電磁力により弁棒１６の頂面４２にパルス状の超音波である縦波２５Ａが励起される。この縦波２５Ａは、弁棒１６の頂面４２から、弁棒１６の内部及び側面３６を、弁棒１６の軸方向に伝播する。このパルス状の縦波２５Ａは、弁棒１６に生じた欠陥４１により反射してパルス状の反射波となり、伝播ルートを戻る。この反射波は、縦波ＥＭＡＴ探触子２５の永久磁石４４及び高周波コイル４６を振動させ、電磁誘導の作用で高周波コイル４６に電位差を発生させることで検出され、この電位差が電位差計３０により計測される。   Since the stationary magnetic field 43 and the eddy current 45 are orthogonal to each other, an electromagnetic force (Lorentz force) that periodically oscillates is generated on the top surface 42 of the valve stem 46, and the top surface 42 of the valve stem 16 is generated by this electromagnetic force. A longitudinal wave 25A, which is a pulsed ultrasonic wave, is excited. The longitudinal wave 25 </ b> A propagates from the top surface 42 of the valve stem 16 through the inside of the valve stem 16 and the side surface 36 in the axial direction of the valve stem 16. The pulse-like longitudinal wave 25A is reflected by the defect 41 generated in the valve stem 16 to become a pulse-like reflected wave, and returns to the propagation route. This reflected wave is detected by causing the permanent magnet 44 and the high frequency coil 46 of the longitudinal wave EMAT probe 25 to vibrate and generating a potential difference in the high frequency coil 46 by the action of electromagnetic induction, and this potential difference is measured by the potentiometer 30. Is done.

本実施の形態では横波ＥＭＡＴ探触子２３及び縦波ＥＭＡＴ探触子２５は、超音波を励起する機能と、反射波を検出する機能とを備えたものを述べたが、超音波励起用の横波ＥＭＡＴ探触子２３、縦波ＥＭＡＴ探触子２５と、反射波検出用の横波ＥＭＡＴ探触子２３、縦波ＥＭＡＴ探触子２５とを別々に設けてもよい。   In the present embodiment, the transverse wave EMAT probe 23 and the longitudinal wave EMAT probe 25 have been described as having a function of exciting an ultrasonic wave and a function of detecting a reflected wave. The transverse wave EMAT probe 23, the longitudinal wave EMAT probe 25, and the transverse wave EMAT probe 23 for detecting reflected waves and the longitudinal wave EMAT probe 25 may be provided separately.

前記高周波電源２９は、図２、図３及び図４に示すように、横波ＥＭＡＴ探触子２３、縦波ＥＭＡＴ探触子２５にパルス状の超音波を励起させるために、これらの横波ＥＭＡＴ探触子２３、縦波ＥＭＡＴ探触子２５にパルス変調された高周波電流を供給するものである。具体的には、高周波発生部２７からパルス変調された高周波電流を出力し、この高周波電流を送信アンプ２８にて増幅して横波ＥＭＡＴ探触子２３の高周波コイル４０、縦波ＥＭＡＴ探触子２５の高周波コイル４６へ供給する。この高周波電流により、横波ＥＭＡＴ探触子２３の高周波コイル４０が弁棒１６の側面３６に、また、縦波ＥＭＡＴ探触子２５の高周波コイル４６が弁棒１６の頂面４２に、それぞれ高周波振動する渦電流を発生させる。   As shown in FIGS. 2, 3, and 4, the high-frequency power source 29 is used to excite pulse-like ultrasonic waves in the transverse wave EMAT probe 23 and the longitudinal wave EMAT probe 25. A high frequency current pulse-modulated is supplied to the contact 23 and the longitudinal wave EMAT probe 25. Specifically, a high-frequency current pulse-modulated from the high-frequency generator 27 is output, and this high-frequency current is amplified by the transmission amplifier 28 to be amplified by the high-frequency coil 40 of the transverse wave EMAT probe 23 and the longitudinal wave EMAT probe 25. To the high frequency coil 46. This high frequency current causes the high frequency coil 40 of the transverse wave EMAT probe 23 to vibrate on the side surface 36 of the valve stem 16 and the high frequency coil 46 of the longitudinal wave EMAT probe 25 to the top surface 42 of the valve stem 16. Eddy currents are generated.

前記処理部３５は、横波ＥＭＡＴ探触子２３の高周波コイル４０、縦波ＥＭＡＴ探触子２５の高周波コイル４６に生じた電位差に基づき、横波ＥＭＡＴ探触子２３、縦波ＥＭＡＴ探触子２５がそれぞれパルス状の超音波（横波ＥＭＡＴ探触子２３の場合には横波のＳＨ波２３Ａ、縦波ＥＭＡＴ探触子２５の場合には縦波２５Ａ）を励起してからパルス状の反射波を検出するまでの時間差を用いて、弁棒１６における欠陥４１の状態（位置及び面積（長さ×深さ））を演算処理して特定する。   Based on the potential difference generated in the high-frequency coil 40 of the transverse wave EMAT probe 23 and the high-frequency coil 46 of the longitudinal wave EMAT probe 25, the processing unit 35 includes the transverse wave EMAT probe 23 and the longitudinal wave EMAT probe 25. Pulse-like reflected waves are detected after exciting pulse-like ultrasonic waves (in the case of the transverse wave EMAT probe 23, the shear wave 23A of the transverse wave, and in the case of the longitudinal wave EMAT probe 25, the longitudinal wave 25A). The state (position and area (length × depth)) of the defect 41 in the valve stem 16 is calculated and specified using the time difference until it is done.

つまり、電位差計３０から出力される電位差のノイズ成分をバンドパスフィルタ３１にて除去し、プリアンプ３２にて電位を増幅し、ＡＤ変換器３３にて電位差をデジタル信号に変換する。データ処理システム３４は、ＡＤ変換器３３からの電位差信号に基づき、横波ＥＭＡＴ探触子２３によりパルス状の横波のＳＨ波２３Ａが励起されてから反射波が検出されるまでの時間差を用いて、また、縦波ＥＭＡＴ探触子２５によりパルス状の縦波２５Ａが励起されてからその反射波が検出されるまでの時間差を用いて、欠陥４１の位置を演算し特定する。更にデータ処理システム３４は、反射波（特に縦波２５Ａの反射波）の電位差が欠陥４１の面積に比例することから、反射波（特に縦波２５Ａの反射波）の電位差から欠陥４１の面積（長さ×深さ）を演算し特定する。   That is, the noise component of the potential difference output from the potentiometer 30 is removed by the band pass filter 31, the potential is amplified by the preamplifier 32, and the potential difference is converted into a digital signal by the AD converter 33. Based on the potential difference signal from the AD converter 33, the data processing system 34 uses the time difference from when the pulsed transverse wave SH wave 23 </ b> A is excited by the transverse wave EMAT probe 23 to when the reflected wave is detected, Further, the position of the defect 41 is calculated and specified using the time difference from when the pulsed longitudinal wave 25A is excited by the longitudinal wave EMAT probe 25 until the reflected wave is detected. Furthermore, since the potential difference of the reflected wave (especially the reflected wave of the longitudinal wave 25A) is proportional to the area of the defect 41, the data processing system 34 determines the area of the defect 41 (from the potential difference of the reflected wave (particularly the reflected wave of the longitudinal wave 25A)). (Length x depth) is calculated and specified.

ところで、横波ＥＭＡＴ探触子２３、縦波ＥＭＡＴ探触子２５が弁棒１６に励起する超音波の周波数、波長は、高周波電源２９から横波ＥＭＡＴ探触子２３の高周波コイル４０、縦波ＥＭＡＴ探触子２５の高周波コイル４６へ供給される高周波電流の周波数、波長にそれぞれ依存する。   By the way, the frequency and the wavelength of the ultrasonic wave excited by the transverse wave EMAT probe 23 and the longitudinal wave EMAT probe 25 on the valve rod 16 are changed from the high frequency power source 29 to the high frequency coil 40 of the transverse wave EMAT probe 23, the longitudinal wave EMAT probe. The frequency depends on the frequency and wavelength of the high-frequency current supplied to the high-frequency coil 46 of the touch element 25.

そこで、高周波電源２９は、横波ＥＭＡＴ探触子２３、縦波ＥＭＡＴ探触子２５へ供給して超音波（横波のＳＨ波２３Ａ、縦波２５Ａ）を励起させる高周波電流の波長を、弁棒１６の直径寸法（例えば１０ｍｍ〜１００ｍｍ）と同等またはその数分の一程度として、弁棒１６に励起される超音波が、弁棒１６に対して波長減衰が少なく伝播性の良好なガイド波として挙動するようにする。   Therefore, the high-frequency power source 29 supplies the wavelength of the high-frequency current to the transverse wave EMAT probe 23 and the longitudinal wave EMAT probe 25 to excite ultrasonic waves (the transverse wave SH wave 23A and the longitudinal wave 25A). The ultrasonic wave excited by the valve stem 16 behaves as a guide wave having a small wavelength attenuation with respect to the valve stem 16 and having a good propagation property. To do.

更に、高周波電源２９は、横波ＥＭＡＴ探触子２３、縦波ＥＭＡＴ探触子２５へ供給して超音波（横波のＳＨ波２３Ａ、縦波２５Ａ）を励起させる高周波電流の波長を、弁棒１６に生じた長さ寸法が数百μｍ以上の欠陥４１からは超音波を反射させるが、弁棒１６の側面３６に数ｍｍピッチで加工されているねじ４７からは超音波の反射を抑制する値とする。   Further, the high-frequency power source 29 supplies the wavelength of the high-frequency current supplied to the transverse wave EMAT probe 23 and the longitudinal wave EMAT probe 25 to excite the ultrasonic waves (the transverse wave SH wave 23A and the longitudinal wave 25A). The ultrasonic wave is reflected from the defect 41 having a length dimension of several hundreds μm or more, but the reflection of the ultrasonic wave is suppressed from the screw 47 processed on the side surface 36 of the valve stem 16 at a pitch of several mm. And

具体的には、高周波電源２９は、横波ＥＭＡＴ探触子２３、縦波ＥＭＡＴ探触子２５へ供給して超音波（横波のＳＨ波２３Ａ、縦波２５Ａ）を励起させる高周波電流の周波数を、弁棒１６の直径が１０ｍｍ〜１００ｍｍであるときに、１００ｋＨｚ〜５００ｋＨｚの範囲の値とする。この周波数範囲の高周波電流により弁棒１６に励起される超音波（横波のＳＨ波２３Ａ、縦波２５Ａ）は、上記直径の弁棒１６に対してガイド波として挙動し、波長減衰が少なく弁棒１６及び弁体１５の略全長に亘って伝播する良好な伝播性を有すると共に、長さ寸法が数百μｍ以上の欠陥４１から反射波を生じさせ、弁棒１６の側面３６に加工された数ｍｍピッチのねじ４７からは反射波を抑制して、高Ｓ/Ｎ比を実現する。   Specifically, the high frequency power supply 29 supplies the frequency of the high frequency current that is supplied to the transverse wave EMAT probe 23 and the longitudinal wave EMAT probe 25 to excite the ultrasonic waves (lateral wave SH wave 23A, longitudinal wave 25A). When the diameter of the valve stem 16 is 10 mm to 100 mm, the value is in the range of 100 kHz to 500 kHz. The ultrasonic waves (transverse wave SH wave 23A, longitudinal wave 25A) excited by the high frequency current in this frequency range behave as a guide wave with respect to the valve rod 16 having the above-mentioned diameter, and have little wavelength attenuation. 16 and the valve body 15 have a good propagation property that propagates over substantially the entire length, and a reflected wave is generated from the defect 41 having a length dimension of several hundred μm or more, and the number processed on the side surface 36 of the valve stem 16 Reflected waves are suppressed from the mm pitch screw 47 to achieve a high S / N ratio.

図５は、横波ＥＭＡＴ探触子２３にて検出され処理部３５のデータ処理システム３４へ出力される超音波（横波のＳＨ波２３Ａ）の反射波を表す電位差を、前記横波ＥＭＡＴ探触子２３が超音波を励起した時点を基準とする時間軸を用いて示すグラフである。横波ＥＭＡＴ探触子２３は、例えば弁棒１６の側面３６に超音波（横波のＳＨ波２３Ａ）を励起してから、１１０μ秒後に欠陥４１からの反射波を、２１０μ秒後に弁棒１６と弁体１５の接続部４８からの反射波を、２２０〜２４０μ秒後に弁体１３の先端面４９の内部を迂回してきた反射波を、それぞれ検出している。   FIG. 5 shows a potential difference representing a reflected wave of an ultrasonic wave (a transverse SH wave 23A) detected by the transverse wave EMAT probe 23 and output to the data processing system 34 of the processing unit 35, and the transverse wave EMAT probe 23. It is a graph shown using the time-axis on the basis of the time of exciting an ultrasonic wave. For example, the transverse wave EMAT probe 23 excites ultrasonic waves (a transverse wave SH wave 23A) on the side surface 36 of the valve stem 16, and then reflects the reflected wave from the defect 41 after 110 μs, and the valve rod 16 and the valve after 210 μs. The reflected wave from the connection portion 48 of the body 15 is detected as the reflected wave that has bypassed the inside of the distal end surface 49 of the valve body 13 after 220 to 240 μsec.

直径数１０ｍｍの弁棒１６の側面３６を伝播する横波のＳＨ波２３Ａが３０００ｍ／秒の伝播速度であることから、処理部３５のデータ処理システム３４は下記計算により、横波ＥＭＡＴ探触子２３から欠陥４１までの距離Ｌを算出する。
［数１］
Ｌ＝Ｖ×ｔ／２＝３０００ｍ×１１０×１０−６÷２＝０．１６５ｍ
ここで、Ｖ：横波のＳＨ波２３Ａの伝播速度
ｔ：超音波(横波のＳＨ波２３Ａ)の励起から反射波検出までの時間差 Since the shear wave 23A of the transverse wave propagating through the side surface 36 of the valve rod 16 having a diameter of several tens of millimeters has a propagation velocity of 3000 m / second, the data processing system 34 of the processing unit 35 performs the following calculation from the transverse wave EMAT probe 23 by The distance L to the defect 41 is calculated.
[Equation 1]
L = V × t / 2 = 3000 m × 110 × 10 −6 ÷ 2 = 0.165 m
Where V: Propagation speed of shear wave 23A
t: Time difference from excitation of ultrasonic wave (transverse SH wave 23A) to detection of reflected wave

上記計算によれば、弁棒１６の側面３６において、横波ＥＭＡＴ探触子２３から０．１６５ｍ、つまり１６．５ｃｍの距離（位置）に欠陥４１が存在することが分かる。横波のＳＨ波２３Ａは、一般的に、縦波２５Ａで発生する弁体１５内部でのバックエコー(図６参照)が少ないことから、欠陥４１の位置を高Ｓ/Ｎ比で特定することができる。   According to the above calculation, it can be seen that the defect 41 exists on the side surface 36 of the valve stem 16 at a distance (position) of 0.165 m from the transverse wave EMAT probe 23, that is, 16.5 cm. Since the shear wave 23A of the transverse wave generally has few back echoes (see FIG. 6) inside the valve element 15 generated by the longitudinal wave 25A, the position of the defect 41 can be specified with a high S / N ratio. it can.

ここで、弁棒１６と弁体１５の接続部４８と横波ＥＭＡＴ探触子２３との距離、弁体１５の先端面４９と横波ＥＭＡＴ探触子２３との距離がそれぞれ既知であることから、図５において、弁棒１６と弁体１５の接続部４８からの反射波、弁体１５の先端面４９の内部を迂回した反射波は、共に、欠陥４１からの反射波と区別して認識される。   Here, since the distance between the connecting portion 48 of the valve stem 16 and the valve body 15 and the transverse wave EMAT probe 23 and the distance between the tip surface 49 of the valve body 15 and the transverse wave EMAT probe 23 are known, In FIG. 5, the reflected wave from the connecting portion 48 of the valve stem 16 and the valve body 15 and the reflected wave that bypasses the inside of the front end surface 49 of the valve body 15 are recognized separately from the reflected wave from the defect 41. .

図６は、縦波ＥＭＡＴ探触子２５にて検出され処理部３５のデータ処理システム３４へ出力される超音波（縦波２５Ａ）の反射波を表す電位差を、前記縦波ＥＭＡＴ探触子２５が超音波を励起した時点を基準とする時間軸を用いて示すグラフである。縦波ＥＭＡＴ探触子２５は、例えば弁棒１６の頂面４２に超音波（縦波２５Ａ）を励起してから、８０μ秒後に欠陥４１からの反射波を、１３０μ秒後に弁棒１６と弁体１５の接続部からの反射波を、１４０〜１８０μ秒後に弁体１５の先端面４９にて反射した反射波を、それぞれ検出している。   6 shows the potential difference representing the reflected wave of the ultrasonic wave (longitudinal wave 25A) detected by the longitudinal wave EMAT probe 25 and output to the data processing system 34 of the processing unit 35, and the longitudinal wave EMAT probe 25. It is a graph shown using the time-axis on the basis of the time of exciting an ultrasonic wave. The longitudinal wave EMAT probe 25, for example, excites ultrasonic waves (longitudinal wave 25A) on the top surface 42 of the valve stem 16, and then reflects the reflected wave from the defect 41 after 80 μs, and the valve rod 16 and the valve after 130 μs. The reflected wave reflected from the front end surface 49 of the valve body 15 after 140 to 180 microseconds is detected from the reflected wave from the connection part of the body 15.

直径数１０ｍｍの弁棒１６の内部及び側面３６を伝播する縦波２５Ａが５０００ｍ／秒の伝播速度であることから、処理部３５のデータ処理システム３４は下記計算により、縦波ＥＭＡＴ探触子２５から欠陥４１までの距離Ｌを算出する。
［数２］
Ｌ＝Ｖ×ｔ／２＝５０００ｍ×８０×１０−６÷２＝０．２００ｍ
ここで、Ｖ：縦波２５Ａの伝播速度
ｔ：超音波(縦波２５Ａ)の励起から反射波検出までの時間差 Since the longitudinal wave 25A propagating through the inside and the side surface 36 of the valve rod 16 having a diameter of 10 mm has a propagation velocity of 5000 m / sec, the data processing system 34 of the processing unit 35 calculates the longitudinal wave EMAT probe 25 by the following calculation. The distance L from to the defect 41 is calculated.
[Equation 2]
L = V × t / 2 = 0.000 m × 80 × 10 −6 ÷ 2 = 0.200 m
Where V: propagation speed of longitudinal wave 25A
t: Time difference from excitation of ultrasonic wave (longitudinal wave 25A) to detection of reflected wave

上記計算によれば、弁棒１６の側面３６において、縦波ＥＭＡＴ探触子２５から０．２００ｍ、つまり２０．０ｃｍの距離(位置)に欠陥４１があることが分かる。この欠陥位置は、縦波ＥＭＡＴ探触子２５と横波ＥＭＡＴ探触子２３の設置位置の若干の違いを考慮すると、上述の横波のＳＨ波２３Ａによる欠陥４１の計測位置と略一致する。   According to the above calculation, it can be seen that the defect 41 is present on the side surface 36 of the valve stem 16 at a distance (position) of 0.200 m, that is, 20.0 cm from the longitudinal wave EMAT probe 25. This defect position substantially coincides with the measurement position of the defect 41 by the above-described shear wave 23A of the transverse wave in consideration of a slight difference in the installation position of the longitudinal wave EMAT probe 25 and the transverse wave EMAT probe 23.

縦波２５Ａは、一般的に、弁体１５の内部でのバックエコーが強く数回反射することから、このバックエコーの処理が煩雑になるが、欠陥４１の面積（長さ×深さ）が、欠陥４１からの反射波の電位差（パルス高さ）に比例することから、処理部３５のデータ処理システム３４は、特に縦波２５Ａの反射波を用いて、欠陥４１の位置と面積を特定することができる。   In the longitudinal wave 25A, since the back echo inside the valve body 15 is reflected strongly several times in general, the processing of the back echo becomes complicated, but the area (length × depth) of the defect 41 is large. Since it is proportional to the potential difference (pulse height) of the reflected wave from the defect 41, the data processing system 34 of the processing unit 35 specifies the position and area of the defect 41 using the reflected wave of the longitudinal wave 25A in particular. be able to.

従って、本実施の形態によれば、次の効果（１）〜（４）を奏する。   Therefore, according to the present embodiment, the following effects (1) to (4) are obtained.

（１）電動弁１０における弁棒１６の表面、つまり弁棒１６の側面３６、頂面４２に横波ＥＭＡＴ探触子２３、縦波ＥＭＡＴ探触子２５をそれぞれ設置し、この弁棒１６に生じた折損に至る欠陥４１を、前記横波ＥＭＡＴ探触子２３及び縦波ＥＭＡＴ探触子２５を用いて直接検出するので、弁棒１６の折損前に、前記欠陥４１を迅速かつ有効に検出できる。   (1) The transverse wave EMAT probe 23 and the longitudinal wave EMAT probe 25 are respectively installed on the surface of the valve stem 16 in the motor-operated valve 10, that is, on the side surface 36 and the top surface 42 of the valve stem 16. Since the defect 41 leading to breakage is directly detected using the transverse wave EMAT probe 23 and the longitudinal wave EMAT probe 25, the defect 41 can be detected quickly and effectively before the valve stem 16 breaks.

（２）電動弁１０を分解することなく、弁棒１６の側面３６の外部露出部２２に横波ＥＭＡＴ探触子２３を、また、弁棒１６の外部に露出する頂面４２に縦波ＥＭＡＴ探触子２５をそれぞれ設置して、この弁棒１６に生じた欠陥４１を検出するので、電動弁１０を分解する必要がない。このため、電動弁１０の分解及び組立工程を削除できると共に、これらの分解または組立時に不具合が発生する事態を未然に回避できる。   (2) Without disassembling the motor-operated valve 10, the transverse wave EMAT probe 23 is exposed to the externally exposed portion 22 of the side surface 36 of the valve stem 16, and the longitudinal wave EMAT probe is exposed to the top surface 42 exposed to the outside of the valve stem 16. Since the touch elements 25 are respectively installed and the defect 41 generated in the valve rod 16 is detected, it is not necessary to disassemble the motor-operated valve 10. For this reason, the disassembly and assembly process of the motor-operated valve 10 can be eliminated, and a situation in which a malfunction occurs during the disassembly or assembly can be avoided.

（３）圧電素子を具備する従来の接触式超音波探触子を用いて電動弁１０の弁棒１６における欠陥４１を検出する場合には、弁棒１６の直径に対応する探触子や接着治具（例えばシュー）を、異なる直径の弁棒１６毎に用意しなければならず、更に、超音波の伝播性を向上させるための接触媒体（例えばグリースなどの液体）を用意しなければならない。   (3) When detecting a defect 41 in the valve stem 16 of the motor-operated valve 10 using a conventional contact ultrasonic probe having a piezoelectric element, a probe or an adhesive corresponding to the diameter of the valve stem 16 A jig (for example, a shoe) must be prepared for each valve stem 16 having a different diameter, and a contact medium (for example, a liquid such as grease) must be prepared for improving the propagation of ultrasonic waves. .

これに対し、本実施の形態では、永久磁石３８、４４と高周波コイル４０、４６を具備し、電磁力により弁棒１６の表面に超音波を非接触で励起させ、また弁棒１６に生じた欠陥４１からの反射波を弁棒１６に対して非接触で検出する電磁超音波探触子（横波ＥＭＡＴ探触子２３、縦波ＥＭＡＴ探触子２５）を用いて、前記欠陥４１を検出している。このため、前記接触媒体が不要となり、弁棒１６の直径に応じた電磁超音波探触子（横波ＥＭＡＴ探触子２３、縦波ＥＭＡＴ探触子２５）や接着治具を複数用意する必要もない。更に、弁棒１６の表面にねじ４７が加工されている場合にも、弁棒１６の表面形状に影響されることなく、電磁超音波探触子（横波ＥＭＡＴ探触子２３、縦波ＥＭＡＴ探触子２５）にて超音波を励起し、反射波を検出することができる。   On the other hand, in the present embodiment, the permanent magnets 38 and 44 and the high frequency coils 40 and 46 are provided, and the surface of the valve stem 16 is excited in a non-contact manner by electromagnetic force. The defect 41 is detected using an electromagnetic ultrasonic probe (a transverse wave EMAT probe 23, a longitudinal wave EMAT probe 25) that detects a reflected wave from the defect 41 in a non-contact manner with respect to the valve stem 16. ing. This eliminates the need for the contact medium, and it is also necessary to prepare a plurality of electromagnetic ultrasonic probes (transverse wave EMAT probe 23, longitudinal wave EMAT probe 25) and bonding jigs according to the diameter of the valve stem 16. Absent. Further, even when the screw 47 is machined on the surface of the valve stem 16, the electromagnetic ultrasonic probe (transverse wave EMAT probe 23, longitudinal wave EMAT probe is not affected by the surface shape of the valve stem 16. Ultrasonic waves can be excited by the touch element 25) to detect a reflected wave.

（４）横波ＥＭＡＴ探触子２３、縦波ＥＭＡＴ探触子２５にて弁棒１６の表面に励起される超音波（横波のＳＨ波２３Ａ、縦波２５Ａ）の周波数は、弁棒１６の直径が１０ｍｍ〜１００ｍｍであるときに、１００ｋＨｚ〜５００ｋＨｚの範囲の値に設定される。このため、この超音波（横波のＳＨ波２３Ａ、縦波２５Ａ）は、波長が弁棒１６の直径と同等または数分の一程度となるので、この直径の弁棒１６に対してガイド波となり、波長減衰が少なく弁棒１６及び弁体１５の略全長に亘って伝播する良好な伝播性を有する。更に、この周波数範囲の超音波（横波のＳＨ波２３Ａ、縦波２５Ａ）は、長さ寸法が数百μｍ以上の欠陥４１から反射波を生じさせ、弁棒１６の側面３６に加工された数ｍｍピッチのねじ４７からは反射波を抑制できるので、高Ｓ/Ｎ比を実現できる。   (4) The frequency of the ultrasonic waves (transverse SH wave 23A, longitudinal wave 25A) excited on the surface of the valve stem 16 by the transverse wave EMAT probe 23 and longitudinal wave EMAT probe 25 is the diameter of the valve stem 16. Is set to a value in the range of 100 kHz to 500 kHz. For this reason, since the wavelength of this ultrasonic wave (transverse SH wave 23A, longitudinal wave 25A) is equal to or about a fraction of the diameter of the valve stem 16, it becomes a guide wave for the valve stem 16 of this diameter. In addition, the wavelength attenuation is small, and the valve rod 16 and the valve body 15 have a good propagation property that propagates over substantially the entire length. Further, the ultrasonic waves in this frequency range (the shear wave 23A and the longitudinal wave 25A) generate reflected waves from the defect 41 having a length dimension of several hundreds μm or more and are processed on the side surface 36 of the valve stem 16. Since the reflected wave can be suppressed from the mm pitch screw 47, a high S / N ratio can be realized.

以上、本発明を上記実施の形態に基づいて説明したが、本発明はこれに限定されるものではない。例えば、上述の実施の形態では、先端に弁体１５が接続された構造の弁棒１６に対して、横波ＥＭＡＴ探触子２３を備えた弁棒診断装置２４、縦波ＥＭＡＴ探触子２５を備えた弁棒診断装置２６を適用した場合を述べたが、弁棒１６と弁体１５が鍛造により一体成形され、弁棒１６が弁体１５に向かって徐々に扁平し、弁体１５が例えば楕円形状を有するものに対しても、前記弁棒診断装置２４、２６を適用できる。特に、弁棒診断装置２４の横波ＥＭＡＴ探触子２３を弁棒１６の側面３６に設置して、この側面３６に超音波（横波のＳＨ波２３Ａ）を励起させる場合には、この横波のＳＨ波２３Ａが弁棒１６から弁体１５へ伝播することで、弁棒１６及び弁体１５の表面に生じた欠陥４１を確実に検出することができる。   As mentioned above, although this invention was demonstrated based on the said embodiment, this invention is not limited to this. For example, in the above-described embodiment, the valve stem diagnostic device 24 including the transverse wave EMAT probe 23 and the longitudinal wave EMAT probe 25 are provided to the valve stem 16 having a structure in which the valve body 15 is connected to the tip. Although the case where the provided valve stem diagnostic device 26 is applied has been described, the valve stem 16 and the valve body 15 are integrally formed by forging, the valve stem 16 is gradually flattened toward the valve body 15, and the valve body 15 is, for example, The valve stem diagnostic devices 24 and 26 can also be applied to those having an elliptical shape. In particular, when the transverse wave EMAT probe 23 of the valve stem diagnostic device 24 is installed on the side surface 36 of the valve stem 16 and the side surface 36 is excited with ultrasonic waves (a transverse wave SH wave 23A), the shear wave SH Since the wave 23 </ b> A propagates from the valve stem 16 to the valve body 15, the defect 41 generated on the surfaces of the valve stem 16 and the valve body 15 can be reliably detected.

１０ 電動弁（弁装置）
１５ 弁体
１６ 弁棒
２３ 横波ＥＭＡＴ探触子（横波電磁超音波探触子）
２３Ａ 横波のＳＨ波
２４ 弁棒診断装置
２５ 縦波ＥＭＡＴ探触子（縦波電磁超音波探触子）
２５Ａ 縦波
２６ 弁棒診断装置
２９ 高周波電源
３０ 電位差計
３５ 処理部
３６ 側面（表面）
３８ 永久磁石
４０ 高周波コイル
４１ 欠陥
４２ 頂面（表面）
４４ 永久磁石
４６ 高周波コイル
４７ ねじ 10 Electric valve (valve device)
15 Valve body 16 Valve stem 23 Transverse wave EMAT probe (transverse wave electromagnetic ultrasonic probe)
23A SH wave of shear wave 24 Valve stem diagnosis device 25 Longitudinal wave EMAT probe (longitudinal wave electromagnetic ultrasonic probe)
25A Longitudinal wave 26 Valve stem diagnostic device 29 High frequency power supply 30 Potentiometer 35 Processing unit 36 Side surface (surface)
38 Permanent magnet 40 High-frequency coil 41 Defect 42 Top surface (surface)
44 Permanent magnet 46 High frequency coil 47 Screw

Claims (9)

先端に弁体が設けられた弁棒を軸方向に駆動して、前記弁体に開閉動作を行わせる弁装置の前記弁棒の表面に設置され、電磁力により超音波を前記弁棒に励起して伝播させると共に、前記弁棒に生じた欠陥から反射する超音波を反射波として検出可能な電磁超音波探触子と、
この電磁超音波探触子に超音波を励起させるための高周波電流を供給する高周波電源と、
前記電磁超音波探触子を構成する高周波コイルに生じた電位差に基づき、前記電磁超音波探触子が超音波を励起してから反射波を検出するまでの時間差を用いて、前記弁棒における前記欠陥の状態を演算処理する処理部と、を有することを特徴とする弁装置の弁棒診断装置。 It is installed on the surface of the valve stem of the valve device that drives the valve stem, which is provided with a valve body at the tip, in the axial direction to cause the valve body to open and close, and excites ultrasonic waves to the valve stem by electromagnetic force And an electromagnetic ultrasonic probe capable of detecting an ultrasonic wave reflected from a defect generated in the valve stem as a reflected wave, and
A high-frequency power source for supplying a high-frequency current for exciting ultrasonic waves to the electromagnetic ultrasonic probe;
Based on the potential difference generated in the high-frequency coil constituting the electromagnetic ultrasonic probe, using the time difference from when the electromagnetic ultrasonic probe excites the ultrasonic wave until the reflected wave is detected, A valve stem diagnosis device for a valve device, comprising: a processing unit that performs arithmetic processing on the state of the defect. 前記電磁超音波探触子は、弁棒の側面に設置され、前記弁棒の表面を伝播する超音波としての横波のＳＨ波を励起し検出する横波電磁超音波探触子であることを特徴とする請求項１に記載の弁装置の弁棒診断装置。 The electromagnetic ultrasonic probe is a lateral wave electromagnetic ultrasonic probe that is installed on a side surface of a valve stem and excites and detects a shear wave of a transverse wave as an ultrasonic wave propagating through the surface of the valve stem. The valve stem diagnosis device for a valve device according to claim 1. 前記電磁超音波探触子は、弁棒の端面に設置され、前記弁棒の内部及び表面を伝播する超音波としての縦波を励起し検出する縦波電磁超音波探触子であることを特徴とする請求項１に記載の弁装置の弁棒診断装置。 The electromagnetic ultrasonic probe is a longitudinal wave electromagnetic ultrasonic probe that is installed on an end surface of a valve stem and excites and detects longitudinal waves as ultrasonic waves propagating through the inside and the surface of the valve stem. The valve stem diagnosis device for a valve device according to claim 1, wherein the device is a diagnostic device. 前記高周波電源が電磁超音波探触子へ供給して超音波を励磁させる高周波電流は、弁棒の直径寸法と同等または数分の一程度の波長の電流であることを特徴とする請求項１に記載の弁装置の弁棒診断装置。 2. The high-frequency current supplied from the high-frequency power source to the electromagnetic ultrasonic probe to excite the ultrasonic wave is a current having a wavelength equivalent to or about a fraction of the diameter of the valve stem. The valve stem diagnostic device for the valve device according to 1. 前記高周波電源が電磁超音波探触子へ供給して超音波を励磁させる高周波電流は、弁棒に生じた欠陥からは超音波を反射させるが、弁棒の表面に加工されたねじからは超音波の反射を抑制する波長の電流であることを特徴とする請求項１に記載の弁装置の弁棒診断装置。 The high-frequency current supplied to the electromagnetic ultrasonic probe by the high-frequency power source to excite the ultrasonic wave reflects the ultrasonic wave from the defect generated in the valve stem, but from the screw processed on the surface of the valve stem. 2. The valve stem diagnostic device for a valve device according to claim 1, wherein the current is a wavelength that suppresses reflection of sound waves. 前記高周波電源が電磁超音波探触子へ供給して超音波を励磁させる高周波電流は、弁棒の直径が１０ｍｍ〜１００ｍｍであるとき、１００ＫＨｚ〜５００ＫＨｚの周波数の電流であることを特徴とする請求項１に記載の弁装置の弁棒診断装置。 The high frequency current that the high frequency power supply supplies to the electromagnetic ultrasonic probe to excite the ultrasonic wave is a current having a frequency of 100 KHz to 500 KHz when the diameter of the valve stem is 10 mm to 100 mm. Item 8. A valve stem diagnostic apparatus for a valve device according to Item 1. 前記電磁超音波探触子は、この電磁超音波探触子を構成する永久磁石による磁力、取付バンド、または柔軟で形状追従性を有する接着治具を用いて、弁棒の表面に設置されることを特徴とする請求項１に記載の弁装置の弁棒診断装置。   The electromagnetic ultrasonic probe is installed on the surface of the valve stem using a magnetic force by a permanent magnet constituting the electromagnetic ultrasonic probe, an attachment band, or a flexible and shape-adhering bonding jig. The valve stem diagnostic apparatus for a valve device according to claim 1. 先端に弁体が設けられた弁棒を軸方向に駆動して、前記弁体に開閉動作を行わせる弁装置の前記弁棒の表面に電磁超音波探触子を設置して、電磁力により前記弁棒に超音波を励起させて伝播させ、前記弁棒に生じた欠陥から反射する超音波を反射波として検出し、
前記電磁超音波探触子が超音波を励起してから反射波を検出するまでの時間差を用いて、前記弁棒における前記欠陥の状態を演算することを特徴とする弁装置の弁棒診断方法。 An electromagnetic ultrasonic probe is installed on the surface of the valve stem of the valve device that drives the valve stem provided with a valve body at the tip end in the axial direction to cause the valve body to open and close. Exciting and propagating ultrasonic waves to the valve stem, detecting ultrasonic waves reflected from defects generated in the valve stem as reflected waves,
A valve rod diagnostic method for a valve device, wherein the state of the defect in the valve rod is calculated using a time difference from when the electromagnetic ultrasonic probe excites an ultrasonic wave until a reflected wave is detected. . 前記電磁超音波探触子が励起する超音波の周波数は、弁棒の直径が１０ｍｍ〜１００ｍｍであるとき、１００ＫＨｚ〜５００ＫＨｚであることを特徴とする請求項８に記載の弁装置の弁棒診断方法。 9. The valve stem diagnosis of a valve device according to claim 8, wherein the frequency of the ultrasonic wave excited by the electromagnetic ultrasonic probe is 100 KHz to 500 KHz when the diameter of the valve stem is 10 mm to 100 mm. Method.
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