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

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

  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.

  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.

  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.

  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.

  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.

JP-T-2005-502824 JP 2005-308540 A

  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.

  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.

  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.

  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.

  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.

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. The composition perspective view showing the valve stem diagnostic device using the transverse wave electromagnetic ultrasonic probe of Drawing 1. The composition perspective view showing the valve stem diagnostic device using the longitudinal wave electromagnetic ultrasonic probe of Drawing 1. The schematic diagram which shows the structure of the valve-rod diagnostic apparatus of FIG.2 and FIG.3 in detail. 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. 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. 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.

  The best mode for carrying out the present invention will be described below with reference to the drawings.

  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.

  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.

  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.

  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.

  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).

  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.

  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.

  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.

  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.

  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.

  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.

  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. .

  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.

  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.

  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.

  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.

  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.

  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.

  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.

  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

  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.

  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.

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

  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.

  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. .

  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.

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

  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.

  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.

  Therefore, according to the present embodiment, the following effects (1) to (4) are obtained.

  (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) 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) 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. .

  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) 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.

  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 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)

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. 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. 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. 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. 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. 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.   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. 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. . 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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