JP2004037468A - Ultrasonic flowmeter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve measuring accuracy and an upper limit value to be measured by reducing vortices in opening holes, accelerating attenuation of unnecessary components of the ultrasonic wave transmitted from ultrasonic transmitter/receivers, and improving S/N of ultrasonic transmission waveform. <P>SOLUTION: This ultrasonic flowmeter is provided with a measurement channel for flowing fluid, the ultrasonic transmitter/receivers provided in the upstream side and the downstream side of the measurement channel, the opening holes 12 in the upstream side and the downstream side allowing the ultrasonic transmitter/receivers 9 to face to the measurement channel, opening hole insulating bodies 21 disposed inside the opening holes 12 and finished of a material having electric insulation, and flow suppressing bodies 14 in the opening holes. The presence of the opening hole insulating bodies can enlarge conduction distances between the ultrasonic transmitter/receivers 9 and the channel bodies formed with the opening holes 12 in a case of a compact storage space so as to enhance voltage endurance causing leak, even if an abnormal high voltage is impressed between the channel body in the attachment side and the ultrasonic transmitter/receivers due to thunderbolt, and can prevent the breakage of the ultrasonic transmitter/receivers 9 by the leakage current to improve the reliability. <P>COPYRIGHT: (C)2004,JPO

Description

The present invention relates to an ultrasonic flow rate measuring apparatus that measures the flow rate and flow velocity of a gas or liquid by ultrasonic waves.

Conventionally, in this type of ultrasonic flow rate measuring apparatus, as shown in FIG. 16, an ultrasonic wave on the upstream side is opposed with a measuring tube 1 that flows a fluid from one side to the other with a predetermined angle with respect to the center line. A transmitter / receiver 2a and an ultrasonic transmitter / receiver 2b on the downstream side are provided facing each other, and these ultrasonic transmitter / receivers 2a and 2b are housed in recesses 3a and 3b provided in the measurement tube 1 and are also provided on the inlet side of the measurement tube 1 4 is provided with a flow fluctuation inhibiting means 5. Then, the flow entering the measuring tube 1 is regulated by the flow fluctuation suppressing means 5 to reduce the inclination of the streamline in the measuring section or to suppress the generation of vortices, so that the ultrasonic wave at the boundary of the flow turbulence is reduced. The fluctuation of the reception level of the ultrasonic wave due to reflection or refraction is reduced to prevent the measurement accuracy from deteriorating (see, for example, Patent Document 1).
Japanese Patent Laid-Open No. 11-351926

In such a conventional configuration, although the flow fluctuation suppression means 5 reduces the disturbance of the flow in the measurement section of the measurement tube 1 and the recesses 3a and 3b and reduces the deterioration of measurement accuracy, the flow rate flowing through the measurement tube 1 is reduced. When it becomes larger, the fluid flows into the recesses 3a and 3b to generate vortices, so that the turbulence in the flow between the ultrasonic transmitters / receivers 2a and 2b increases, and the ultrasonic waves are reflected or refracted by the increased vortices. Therefore, there is a problem that it is difficult to reduce the drive input of the ultrasonic transceivers 2a and 2b.

The present invention solves the above-mentioned problem, reduces the vortex caused by the flow of fluid into the opening hole, reduces the attenuation of the ultrasonic wave, raises the reception level of the ultrasonic wave, and further transmits the ultrasonic wave transmitted from the ultrasonic transceiver. The purpose is to increase the upper limit of measurement accuracy and flow rate measurement by promoting the attenuation of unnecessary components that do not go directly to the receiving side because they are transmitted to the side of the sound waves, thereby increasing the S / N of the ultrasonic transmission waveform. .

In order to solve the above-described conventional problems, an ultrasonic flow rate measuring device according to the present invention includes a measurement channel through which a fluid flows, ultrasonic transmitters / receivers provided upstream and downstream of the measurement channel, and the ultrasonic wave An upstream and downstream opening hole that allows the transmitter / receiver to face the measurement flow path, an opening hole insulator formed of an electrically insulating material disposed on the inner surface of the opening hole, and an inflow suppression to the opening hole It has a body.

In this way, even in a compact storage space, the conductive distance between the ultrasonic transmitter / receiver and the flow path body forming the open hole is increased by the opening hole insulator, and the mounting side flow path body and the ultrasonic wave are Even when an abnormally high voltage is generated between the transmitter and the receiver, the withstand voltage leading to leakage can be increased, the ultrasonic transmitter and receiver can be prevented from being damaged by the leak current, the reliability can be improved, and the miniaturization can be promoted.

As is clear from the above description, according to the ultrasonic flow measuring device of the present invention, even in a compact storage space, the conductive distance between the ultrasonic transceiver and the flow path body that forms the opening hole is reduced by the opening hole insulator. Even if an abnormally high voltage occurs between the mounting-side flow path body and the ultrasonic transmitter / receiver due to lightning, etc., the withstand voltage leading to leakage is increased, and the ultrasonic transmitter / receiver is not damaged by the leak current, thereby improving reliability. It can improve and miniaturization can be promoted.

In one embodiment of the present invention, a measurement channel through which a fluid to be measured flows, ultrasonic transmitters / receivers provided on the upstream side and the downstream side of the measurement channel, and the ultrasonic transmitter / receiver face the measurement channel. The opening hole on the upstream side and the downstream side, the measurement flow path and the opening hole are communicated with each other and have an opening window which is smaller than the cross-sectional area of the opening hole and is substantially flush with the flow path wall of the measurement flow path. By providing an inflow suppressor, the flow of measured fluid into the aperture hole is reduced, the generation of vortices in the aperture hole is reduced, the attenuation of ultrasonic waves due to the vortex is reduced, and the transmission / reception level is increased. By forming an expansion space by the opening hole between the sound wave transmitter / receiver and the inflow suppression body having the opening window, unnecessary ultrasonic waves transmitted to the side of the ultrasonic transmitter / receiver are reflected in the opening hole to promote attenuation. Reduce the noise by increasing the proportion of direct waves that pass directly through the aperture window. Can be obtained have transmitted waveform. For this reason, by improving the transmission / reception level of ultrasonic waves and transmitting / receiving ultrasonic waves with improved S / N characteristics, the upper limit of measurement accuracy and flow rate measurement is increased, and driving input of the ultrasonic transmitter / receiver is improved by improving the transmission / reception level of ultrasonic waves. The input can be reduced and the input can be reduced, and a long-term operation can be realized even when the battery is driven at a low voltage.

In one embodiment of the present invention, a measurement channel through which a fluid to be measured flows, ultrasonic transmitters / receivers provided on the upstream side and the downstream side of the measurement channel, and the ultrasonic transmitter / receiver face the measurement channel. An inflow in which the upstream and downstream opening holes, the measurement channel and the opening hole communicate with each other, have an opening window smaller than the sectional area of the opening hole, and are substantially flush with the channel wall of the measurement channel A suppression body and an opening hole insulator formed of an electrically insulating material disposed on the inner surface of the opening hole are provided. For this reason, even in a compact storage space, the conductive distance between the ultrasonic transmitter / receiver and the flow path body forming the open hole is increased by the opening hole insulator, and the mounting side flow path body and the ultrasonic transmitter / receiver are caused by a lightning strike or the like. Even if an abnormally high voltage occurs in the meantime, the withstand voltage leading to leakage can be increased, the ultrasonic transceiver can be prevented from being damaged by the leakage current, the reliability can be improved, and the miniaturization can be promoted. Further, as in the first aspect, the generation of vortices in the aperture hole is reduced and unnecessary ultrasonic waves are attenuated by multiple reflection in the aperture hole to improve the ultrasonic transmission / reception level and transmit / receive ultrasonic waves with improved S / N characteristics. Therefore, it is possible to increase the measurement accuracy and the upper limit value at which the flow rate can be measured, and to reduce the drive input of the ultrasonic transmitter / receiver by improving the transmission / reception level of the ultrasonic wave.

In one embodiment of the present invention, the surface on the ultrasonic transmitter / receiver side of the inflow suppressor is obliquely crossed with the propagation direction of the ultrasonic wave, so that an unnecessary ultrasonic wave that does not pass through the aperture window hits the inflow suppressor. Since it reflects to the side wall side of an opening hole, without reflecting in the direction which returns to the sound wave transmitter / receiver side, multiple reflection can be accelerated | stimulated and attenuation | damping of an unnecessary ultrasonic wave can be promoted further. For this reason, transmission / reception of ultrasonic waves with improved S / N characteristics can be further enhanced to improve measurement accuracy.

In one embodiment of the present invention, the inflow suppressor is formed of an electrically insulating material, and the end of the opening hole insulator on the measurement channel side is brought into contact with the inflow suppressor, whereby the ultrasonic transceiver is connected to the measurement channel side. Even if they are placed closer to each other, the conductive distance between the ultrasonic transceiver and the channel wall that forms the measurement channel can be increased, and even if an abnormally high voltage is generated due to a lightning strike, etc. The reliability can be improved by preventing damage to the ultrasonic transmitter / receiver due to leakage current, and further miniaturization can be further promoted because the ultrasonic transmitter / receiver can be placed closer to the measurement flow path side.

In one embodiment of the present invention, since the inflow suppressing body and the opening hole insulator are integrated, the electrical insulation at the contact portion between the inflow suppressing body and the opening hole insulator is further improved and the reliability is improved. it can. Furthermore, the variation in the positional relationship between the inflow suppressor and the opening hole insulator can be reduced to improve the stability of measurement accuracy, and the cost can be reduced by reducing the number of parts.

In one embodiment of the present invention, the inflow suppressor is provided with an ultrasonic transmission body having a large number of fine openings through which ultrasonic waves can pass, so that the flow of the fluid to be measured into the opening hole is greatly increased. The generation of vortices in the aperture hole can be greatly reduced, and the attenuation of ultrasonic waves by the vortices can be further reduced. For this reason, the transmission / reception level of an ultrasonic wave can be further improved to transmit / receive an ultrasonic wave having a further improved S / N characteristic, and the measurement accuracy and the upper limit value at which the flow rate can be measured can be improved.

In one embodiment of the present invention, the inflow suppression body is formed of a resin material, and the ultrasonic transmission body is welded and joined, so that the inflow suppression body and the ultrasonic transmission body can be joined flush with each other. It is possible to improve the uniformity of the flow path wall and the attachment portion of the ultrasonic transmission body of the inflow suppressor to prevent the disturbance of the flow in the vicinity of the wall surface of the measurement flow path and to improve the measurement accuracy and the upper limit value at which the flow rate can be measured. Furthermore, the inflow suppression body and the ultrasonic transmission body can be reliably integrated, and the reliability can be improved.

In one embodiment of the present invention, the resin material forming the inflow suppressor is mixed with glass fiber, so that the thermal expansion coefficient is reduced to maintain the flatness of the surface after the heat welding operation. It is possible to prevent irregularities from occurring and stabilize the flow of the measurement channel.

In one embodiment of the present invention, since the inflow suppressor is provided with an ultrasonic sound absorbing means, an ultrasonic wave that does not pass through the opening window and an ultrasonic wave that hits the inflow suppressor is absorbed and an unnecessary ultrasonic wave is generated. Damping can be further promoted. For this reason, transmission / reception of ultrasonic waves with improved S / N characteristics can be further enhanced to improve measurement accuracy.

In one embodiment of the present invention, since the inflow suppressor is formed of a porous material, the inflow suppressor can be made compact and the sound absorption effect can be stabilized by stabilizing the shape and dimensions, and the measurement apparatus can be downsized. Reliability can be improved.

In one embodiment of the present invention, the opening hole insulator is provided with an ultrasonic sound absorbing means, and unnecessary ultrasonic waves transmitted to the side of the ultrasonic transmitter / receiver are transmitted by the sound absorbing means provided in the opening hole insulator. Attenuation can be promoted by absorbing sound, and a transmission waveform with less noise can be obtained by increasing the proportion of direct waves that pass directly through the aperture window. For this reason, the upper limit of measurement accuracy and flow rate measurement can be increased by improving the transmission / reception level of ultrasonic waves and transmitting / receiving ultrasonic waves with improved S / N characteristics. Even when an abnormally high voltage is generated between the flow path body on the attachment side and the ultrasonic transmitter / receiver, the withstand voltage leading to leakage can be increased, and the ultrasonic transmitter / receiver can be prevented from being damaged by the leak current, thereby improving the reliability.

In one embodiment of the present invention, the cross-sectional shape through which the ultrasonic wave of the aperture hole insulator passes is made asymptotic to the shape of the aperture window as it goes to the measurement flow path side, so that the ultrasonic wave that has passed through the aperture window is in the aperture hole. Dissipation at the point can be reduced to reach the receiving-side ultrasonic transmitter / receiver, and the upper limit of measurement accuracy and flow rate measurement can be increased by transmitting / receiving ultrasonic waves with improved sensitivity.

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

(Embodiment 1)
FIG. 1 is a cross-sectional view of an ultrasonic flow rate measuring apparatus according to Embodiment 1 of the present invention. In FIG. 1, 6 is a measurement flow path surrounded by a flow path body 7, and 8 and 9 are upstream and downstream sides attached to the flow path body 7 via a vibration transmission restraining body 10 so as to face each other. It is an ultrasonic transmitter / receiver, and the ultrasonic transmitter / receiver 8 on the upstream side and the ultrasonic transmitter / receiver 9 on the downstream side are separated from each other by a distance L and inclined at an angle θ with respect to the fluid flow direction of the measurement channel 6. . Reference numerals 11 and 12 are opening holes on the upstream side and the downstream side that allow the ultrasonic transmitters and receivers 8 and 9 to face the measurement flow path 6, and are recessed with respect to the flow path body 7. Reference numeral 13 denotes an ultrasonic wave propagation path (a region indicated by a two-dot chain line) in which an ultrasonic wave transmitted between the opposing ultrasonic transmitters / receivers 8 and 9 propagates directly to the ultrasonic transmitter / receiver on the other side without being reflected on the wall surface. is there. 14 has the measurement flow path 6 and the opening holes 11, 12 communicated with each other and has an opening window 15 smaller than the cross-sectional area of the opening holes 11, 12 and is disposed substantially flush with the flow path wall 6 a of the measurement flow path 6. It is an inflow suppressor. The vibration transmission suppressing body 10 supports the ultrasonic transceivers 8 and 9 in an anti-vibration manner and also performs airtight sealing so that the fluid to be measured does not leak.

Reference numeral 16 denotes a flow stabilizing means provided on the upstream side of the ultrasonic wave propagation path 13 to stabilize the flow of the measurement flow path 6 and reduce the flow of the fluid to be measured into the opening holes 11 and 12 on the upstream side and the downstream side. The flow stabilizing means 16 includes a direction restricting portion 16a that adjusts the flow direction of the fluid to be measured and a fluctuation suppressing portion 16b that equalizes the flow velocity distribution or reduces pulsation of the flow. The direction restricting portion 16a and the fluctuation suppressing portion 16b are distances. It is arranged so as to be fitted in a recess 7 a provided in the flow path body 7 in the vicinity of X apart. The direction restricting portion 16a is provided with a plurality of subdivided ports (not shown) obtained by finely dividing the cross section of the measurement channel 6 with a partition wall extending in the flow direction. Further, the fluctuation suppressing portion 16b is short in the flow direction and has a large number of fine openings (not shown) with respect to the cross section of the measurement flow path 6. Here, the fluctuation suppressing portion 16b is formed of a mesh. doing.

FIG. 2 is an enlarged view of the attachment portion of the inflow suppression body 14. The inflow suppression body 14 is inserted into the recess 7 b provided in the flow path body 7, and the surface 14 a on the measurement flow path 6 side is the measurement flow path 6. It is flush with the flow path wall 6a. Further, the opening area of the opening window 15 is made smaller than the cross-sectional area of the opening hole 12, and the opening hole 12 is made larger than the outer dimension D of the ultrasonic transceiver 9. A space portion 12a is formed before the ultrasonic wave propagation path 13 is entered. Further, the back surface 14b of the inflow suppressor 14 on the ultrasonic transmitter / receiver 9 side is disposed at an angle that intersects obliquely without being orthogonal to the ultrasonic wave propagation direction (direction indicated by the ultrasonic wave propagation path 13). In addition, although the downstream opening hole 12 part was shown here, the same expansion space part 11a (not shown) is formed by the inflow suppression body 14 also in the upstream opening hole 11 part.

Reference numeral 17 denotes an upstream bent portion communicating with an on-off valve (not shown) provided on the upstream side of the measurement flow path 6, and reference numeral 18 denotes a downstream connected to an outlet (not shown) provided on the downstream side of the measurement flow path 6. This is a bent portion on the side, and the flow path is configured compactly by the bent portions 17 and 18. Reference numeral 19 denotes a measurement control unit that is connected to the ultrasonic transmitters / receivers 8 and 9 and transmits / receives ultrasonic waves. Reference numeral 20 denotes an arithmetic unit that calculates a flow rate based on a signal from the measurement control unit 19 and calculates a flow rate.

Next, the flow measurement operation using ultrasonic waves will be described. In the ultrasonic wave propagation path 13 of the measurement flow path 6, ultrasonic waves are transmitted and received between the ultrasonic transmitters / receivers 8 and 9 across the measurement flow path 6 by the action of the measurement control unit 19. That is, the propagation time T1 until the ultrasonic wave emitted from the upstream ultrasonic transceiver 8 is received by the downstream ultrasonic transceiver 9 is measured. On the other hand, the propagation time T2 until the ultrasonic wave emitted from the ultrasonic transmitter / receiver 9 on the downstream side is received by the ultrasonic transmitter / receiver 8 on the upstream side is measured.

Based on the propagation times T1 and T2 measured in this way, the flow rate is calculated by the calculation unit 20 by the following calculation formula.

Now, let θ be the angle formed between the flow velocity V of the fluid to be measured in the longitudinal direction of the measurement flow path 6 and the ultrasonic wave propagation path 13, L be the distance between the ultrasonic transceivers 8 and 9, and the ultrasonic wave propagating through the fluid to be measured. When the sound velocity of the sound wave is C, the flow velocity V is calculated by the following equation.

T1 = L / (C + V cos θ)
T2 = L / (C−Vcos θ)
The speed of sound C is eliminated from the equation for subtracting the reciprocal of T2 from the reciprocal of T1, and V = (L / 2 cos θ) ((1 / T1) − (1 / T2))
Since θ and L are known, the flow velocity V can be calculated from the values of T1 and T2.

Next, from the cross-sectional area S orthogonal to the flow direction of the measurement channel 6, the flow rate Q is Q = KVS
Here, K is a flow rate correction coefficient considering the flow velocity distribution in the cross-sectional area S.

In this way, the flow rate is obtained by the calculation unit 20.

Next, the flow state and measurement operation in the measurement flow path of this ultrasonic flow rate measuring device will be described. The measured flow remains unbalanced or pulsates due to the fluid being measured being enlarged or reduced in the cross-sectional area of the flow path at an on-off valve (not shown) provided on the upstream side of the measurement flow path 6 or flowing through the bent portion 17. Enter road 6. In the measurement flow path 6, the flow in the cross section of the measurement flow path 6 is rectified in a direction in which it is difficult to flow into the opening holes 11 and 12 by the direction restricting portion 16 a of the flow stabilizing means 16 provided on the upstream side of the ultrasonic propagation path 13. And reduce turbulence. Next, the fluctuation suppressing unit 16b reduces the disturbance due to flow fluctuations such as pulsation, and further suppresses the inflow to the opening holes 11 and 12, and causes the ultrasonic wave propagation path 13 to flow. Furthermore, the fluctuation suppressing unit 16b has an effect of stabilizing the flow velocity distribution by flattening the flow that has flowed out of the plurality of subdividing ports of the direction restricting unit 16a into a jet shape. Further, in the opening holes 11 and 12 on the upstream side and the downstream side, the opening window 15 of the inflow suppressing body 14 has a smaller opening area than the opening hole and is flush with the flow path wall 6b. Since the flow is not disturbed, the flow of the fluid to be measured into the opening holes 11 and 12 can be reduced, the generation of vortices in the opening holes 11 and 12 can be reduced, and the attenuation of ultrasonic waves by the vortices is reduced. The transmission / reception level can be increased, and further, the space 11a, 12a is formed between the ultrasonic transmission / reception units 8 and 9 and the inflow suppressing body 14 having the opening window 15, thereby forming the ultrasonic transmission / reception units 8 and 9 side. Unnecessary ultrasonic waves transmitted to the other side are multiple-reflected in the aperture holes 11 and 12 to promote attenuation, and the ratio of direct waves that pass directly through the aperture window can be increased to obtain a transmission waveform with less noise.

For this reason, by improving the transmission / reception level of ultrasonic waves and transmitting / receiving ultrasonic waves with improved S / N characteristics, the upper limit of measurement accuracy and flow rate measurement is increased, and driving input of the ultrasonic transmitter / receiver is improved by improving the transmission / reception level of ultrasonic waves. The input can be reduced and the input can be reduced, and a long-term operation can be realized even when the battery is driven at a low voltage. Further, since the inflow suppressing body 14 is a separate member from the flow path body 7, the measurement flow path 6 remains common and the opening window 15 has an appropriate area for the type of fluid to be measured and the flow rate range to be measured. Or it can respond to many use conditions by arbitrarily setting to an appropriate shape, and can improve the convenience or functionality.

Further, the back surface 14b of the inflow suppressor 14 on the ultrasonic transmitter / receiver 8 and 9 side is obliquely crossed without being orthogonal to the ultrasonic wave propagation direction, so that the back surface of the inflow suppressor 14 does not pass through the opening window 15. The unnecessary ultrasonic wave hitting 14b is not reflected in the direction returning to the ultrasonic transmitter / receiver side, but is reflected on the side walls 11b and 12b side of the opening holes 11 and 12, and multiple reflection is promoted to attenuate unnecessary ultrasonic waves. It can be further promoted. For this reason, transmission / reception of ultrasonic waves with improved S / N characteristics can be further enhanced to improve measurement accuracy.

As described above, in the present embodiment, the fluid to be measured is provided by including the inflow suppressing body that has the opening window smaller than the cross-sectional area of the opening hole and is disposed flush with the flow path wall of the measurement flow path. Inflow with an ultrasonic transmitter / receiver and an opening window can be achieved by reducing the flow of sound into the opening hole, reducing the generation of vortices in the opening hole, reducing the attenuation of ultrasonic waves by the vortex, and increasing the transmission / reception level. Directly passing through the aperture window directly by directing the unwanted ultrasonic waves transmitted to the side of the ultrasonic transmitter / receiver by multiple reflections in the aperture hole by facilitating the attenuation by forming an opening space between the suppressors. The ratio of waves can be increased to obtain a transmission waveform with less noise. By improving the transmission / reception level of ultrasonic waves and transmitting / receiving ultrasonic waves with improved S / N characteristics, the upper limit of measurement accuracy and flow rate can be increased. Ultra-high by improving sound wave transmission / reception level Can low input reduction by reducing the driving input of the wave transceiver can be realized long-term operation at low voltage due to battery.

Further, in this embodiment, the surface of the inflow suppressor on the ultrasonic transmitter / receiver side is obliquely crossed with the propagation direction of the ultrasonic wave, thereby accelerating the multiple reflection of unnecessary ultrasonic waves that do not pass through the aperture window. Attenuation of ultrasonic waves can be further promoted, and transmission / reception of ultrasonic waves with improved S / N characteristics can be further enhanced to improve measurement accuracy.

(Embodiment 2)
FIG. 3 shows a partial cross-sectional view of the ultrasonic flow rate measuring apparatus according to the second embodiment of the present invention. Here, the downstream opening hole 12 is shown, but the upstream opening hole 11 is the same. The same members and functions as those in the embodiment of FIG. 1 and FIG. 2 are denoted by the same reference numerals, and detailed description thereof is omitted.

Reference numeral 21 denotes an opening hole insulator formed of an electrically insulating material disposed on the inner surface of the opening hole 12. The opening hole insulator 21 is provided so as to surround the outer peripheral side of the ultrasonic transceiver 9, The one end 21a is in contact with the vibration transmission deterrence body 10 that supports and hermetically seals the ultrasonic transmitter / receiver 9. The ultrasonic transmitter / receiver 9 has a piezoelectric body 23 bonded to an inner surface of a case 22 formed of a metal material, an acoustic matching layer 24 bonded to an outer surface of the case 22, and a support base 25 formed of the case 22 of a metal material. Is airtightly bonded. Reference numeral 26 denotes a connection terminal. One connection terminal 26 a is electrically connected to one end of the piezoelectric body 23 via a conductor 27, and the other connection terminal 26 b is connected to the piezoelectric body 23 via a support base 25 and a case 22. It is electrically connected to the other end. Reference numeral 28 denotes a sealing body that electrically insulates and hermetically seals the connection terminal 26a and the connection terminal 26b. Reference numeral 29 denotes a fixed body that is pressed against the flow path so that the vibration transmission suppressing body 10 does not fall off. The vibration transmission restraining body 10 is made of a material such as rubber having a large electric resistance in addition to vibration proof support and airtight sealing, and provides electrical insulation. The fixed pair 29 is made of an electric material such as resin. It is made of a material with high resistance to provide electrical insulation.

Here, when the flow path body 7 is formed of a metal material such as a die-cast alloy having excellent durability, strength, and corrosion resistance, the ultrasonic transmitter / receiver 9 is connected to the opening hole insulator 21 that is an electrically insulating material. By enclosing, the conductive distance between the ultrasonic transceiver 9 and the flow path body 7 can be set large. Further, the vibration transmission restraining body 10 having electrical insulation and the fixed body 29 are fixedly supported on the flow path body 7 and the one end 21a of the opening hole insulator 21 which is an electrical insulating material is brought into contact with the vibration transmission restraining body 10. By doing so, the conductive distance between the flow path body 7 and the ultrasonic transmitter / receiver 9 can be set large by surrounding the ultrasonic transmitter / receiver 9.

For this reason, even in a compact storage space, the conductive distance between the ultrasonic transmitter / receiver and the flow path body forming the open hole is increased by the opening hole insulator 21, and ultrasonic wave transmission / reception with the flow path body on the mounting side is caused by a lightning strike. Even when an abnormally high voltage occurs between the devices, the withstand voltage leading to leakage can be increased, the ultrasonic transceiver can be prevented from being damaged by the leakage current, the reliability can be improved, and the miniaturization can be promoted. Furthermore, the inflow suppressor 14 installed flush with the flow path wall 6a and the opening window 15 with a reduced opening area reduce vortex generation in the opening hole and attenuate unnecessary ultrasonic waves by multiple reflection in the opening hole, By improving the transmission / reception level of ultrasonic waves and transmitting / receiving ultrasonic waves with improved S / N characteristics, the upper limit of measurement accuracy and flow rate can be increased, and the drive input of the ultrasonic transmitter / receiver can be reduced by improving the transmission / reception level of ultrasonic waves. Input can be reduced.

Further, as an application of the present embodiment, the opening window 15 having a reduced opening cross-sectional area of the opening hole 12 is not provided, the opening of the opening hole 12 is left as it is, and the periphery of the ultrasonic transceiver 9 is formed as an opening hole insulator. FIG. 4 shows a configuration surrounded by. In this configuration, the vibration transmission restraining body 10 is made of a material such as rubber having a large electric resistance in addition to the vibration-proofing support property and the airtight sealability, and imparts electric insulation, and the fixed body 29 is an electric resistance such as resin. It is made of a large material to provide electrical insulation.

Further, the vibration transmission restraining body 10 having electrical insulation and the fixed body 29 are fixedly supported on the flow path body 7 and the one end 21a of the opening hole insulator 21 which is an electrical insulating material is brought into contact with the vibration transmission restraining body 10. By doing so, the conductive distance between the flow path body 7 and the ultrasonic transmitter / receiver 9 can be set large by surrounding the ultrasonic transmitter / receiver 9.

In the configuration of FIG. 4, since the opening window 15 in which the cross-sectional area of the opening hole is reduced is eliminated, the attenuation of ultrasonic waves is small and the sensitivity is improved. In addition, if there is an open window, stagnation occurs on the inside, but since there is no such, accumulation of dust and the like can be prevented and reliability is improved.

FIG. 5 is a partial cross-sectional view showing another embodiment of the opening holes 11 and 12, and one end 21 a of the opening hole insulator 21 is a vibration transmission restraining body 10 that supports and hermetically seals the ultrasonic transceiver 9. And the other end 21 b of the opening hole insulator 21 is in contact with the inflow suppressing body 14. Here, by forming the inflow suppression body 14 and the vibration transmission suppression body 10 with an insulating material, the ultrasonic transmitter / receiver 9 can increase the electrical insulation distance from the flow path body 7, and the ultrasonic transmitter / receiver 9 is connected to the measurement flow path 6. The measurement part can be made compact and compact.

In this way, the inflow suppressor is formed of an electrically insulating material, and the end of the opening hole insulator on the measurement channel side is brought into contact with the inflow suppressor, thereby bringing the ultrasonic transmitter / receiver closer to the measurement channel side. Even if they are placed in a horizontal position, the conductive distance between the ultrasonic transmitter / receiver and the channel wall that forms the measurement channel can be increased. Therefore, it is possible to improve the reliability by preventing the ultrasonic transmitter / receiver from being damaged, and to further reduce the size because the ultrasonic transmitter / receiver can be arranged closer to the measurement channel.

Further, as shown in FIG. 6 as an application of the embodiment of FIG. 5, the opening window 15 having a reduced opening cross-sectional area of the opening hole 12 is not provided, and the opening of the opening hole 12 is left as it is. There is a configuration in which 21 is extended to the inflow suppression body 14. In this configuration, since the opening window 15 having a reduced cross-sectional area of the opening hole is eliminated, the ultrasonic wave is less attenuated and the sensitivity is improved. In addition, if there is an open window, stagnation occurs on the inside, but since there is no such, accumulation of dust and the like can be prevented and reliability is improved.

FIG. 7 is a partial cross-sectional view showing another embodiment of the opening holes 11 and 12, where the inflow suppressing body 14 and the opening hole insulator 21 are integrated, and one end 21a of the opening hole insulator 21 transmits vibration. It is in contact with the deterrent body 10. By integrating the inflow suppression body 14 and the opening hole insulator 21, electrical insulation between the inflow suppression body 14 and the opening hole insulator 21 can be ensured. In addition, the electrical insulation between the opening hole insulator 21 and the vibration transmission restraining body 10 can be ensured by forming the vibration transmission restraining body 10 from a material such as elastic rubber and applying contact force to make contact. Thus, the reliability can be improved by slightly bending the vibration transmission suppressing body 10.

Thus, by integrating the inflow suppressing body and the opening hole insulator, the electrical insulation at the contact portion between the inflow suppressing body and the opening hole insulator can be further enhanced to improve the reliability. Furthermore, the variation in the positional relationship between the inflow suppressor and the opening hole insulator can be reduced to improve the stability of measurement accuracy, and the cost can be reduced by reducing the number of parts.

As described above, in this embodiment, the inflow suppression body having an opening window smaller than the cross-sectional area of the opening hole and disposed flush with the flow path wall of the measurement flow path, and the inner surface of the opening hole are arranged. By providing an opening hole insulator made of a material having electrical insulation, the conductive distance between the ultrasonic transmitter / receiver and the flow path body forming the opening hole is reduced by the opening hole insulator even in a compact storage space. Even if an abnormally high voltage occurs between the flow channel on the mounting side and the ultrasonic transmitter / receiver due to a lightning strike, etc., the withstand voltage leading to leakage can be increased, and damage to the ultrasonic transmitter / receiver due to leakage current can be prevented. Reliability can be improved and miniaturization can be promoted. Furthermore, measurement accuracy and flow rate are reduced by reducing the generation of vortices in the aperture hole and attenuating unnecessary ultrasonic waves by multiple reflection in the aperture hole, improving the transmission / reception level of ultrasonic waves and transmitting / receiving ultrasonic waves with improved S / N characteristics. The upper limit value that can be measured can be increased, and the drive input of the ultrasonic transmitter / receiver can be reduced and the input can be reduced by improving the ultrasonic transmission / reception level.

Further, in this embodiment, the inflow suppression body is formed of an electrically insulating material, and the end of the opening hole insulator on the measurement channel side is brought into contact with the inflow suppression body, so that the ultrasonic transceiver is connected to the measurement channel side. Even if they are placed closer to each other, the conductive distance between the ultrasonic transceiver and the channel wall that forms the measurement channel can be increased, and even if an abnormally high voltage occurs due to a lightning strike, etc., the withstand voltage leading to leakage is increased. Therefore, the ultrasonic transmitter / receiver can be prevented from being damaged by a leak current, and the reliability can be improved. Further, since the ultrasonic transmitter / receiver can be arranged closer to the measurement flow path side, the miniaturization can be further promoted.

Further, in this embodiment, the inflow suppressor and the opening hole insulator are integrated, so that the electrical insulation at the contact portion between the inflow suppressor and the opening hole insulator can be further improved and the reliability can be improved. The stability of the measurement accuracy can be improved by reducing the variation in the positional relationship between the inflow suppressor and the opening hole insulator, and the cost can be reduced by reducing the number of parts.

(Embodiment 3)
FIG. 8 shows a partial cross-sectional view of the ultrasonic flow rate measuring apparatus according to Embodiment 3 of the present invention. Here, the downstream opening hole 12 is shown, but the upstream opening hole 11 is the same. The same members and functions as those in the embodiment of FIGS. 1 to 5 are denoted by the same reference numerals, detailed description thereof is omitted, and different points will be mainly described.

Reference numeral 30 denotes an ultrasonic transmission body provided on the measurement flow path 6 side of the opening window 15 of the inflow suppressing body 14. The ultrasonic transmission body 30 has a large number of fine openings (not shown) through which ultrasonic waves can pass. At the same time, the surface 30a of the ultrasonic transmitting body 30 is attached to the recess 14a provided in the inflow suppressing body 14 so that it is substantially flush with the flow path wall 6a. Here, a mesh is used as the ultrasonic transmission body 30, and fine meshes having a mesh size of about # 50 to # 500 can be used. In addition, what has many small fine openings, such as a perforated board by punching processing or an etching process, cloth, such as a lath net, gauze, and a nonwoven fabric, a perforated film, and a mesh-shaped resin molded product, can also be utilized.

By installing the ultrasonic transmission body 30 in the opening window 15 substantially flush with the flow path wall 6a, the flow of the fluid to be measured into the opening hole 12 can be greatly reduced, so that the flow disturbance in the measurement flow path 6 is prevented. Further, the generation of vortices in the opening hole 12 can be greatly reduced. Furthermore, by making the flow path body 7 and the inflow suppression body 14 that covers the opening window 15 with the ultrasonic transmission body 30 having a fine opening as separate members, the type of measurement fluid and the flow rate range to be measured are reduced. The flow path body 7 forming the measurement flow path 6 remains the same, and the shape and size of the opening window 15 or the fineness of the mesh that determines the size of the fine opening of the ultrasonic transmission body 30 is optimized to be super-high. Measurement of flow velocity or flow rate with enhanced sensitivity for transmitting and receiving sound waves.

In this way, the inflow suppressor is equipped with an ultrasonic transmission body having a large number of fine openings through which ultrasonic waves can pass, so that the flow of the fluid to be measured into the opening hole is greatly reduced. The generation of vortices in the hole can be greatly reduced, and the attenuation of ultrasonic waves by the vortices can be further reduced. For this reason, the transmission / reception level of an ultrasonic wave can be further improved to transmit / receive an ultrasonic wave having a further improved S / N characteristic, and the measurement accuracy and the upper limit value at which the flow rate can be measured can be improved.

Further, the inflow suppression body 14 is formed of a thermoplastic resin material, and after placing the ultrasonic transmission body 30 at a predetermined position, the inflow suppression body 14 is locally heated and melted, and the inflow suppression body 14 is ultrasonically transmitted. The body 30 can be securely fixed. In particular, when a metallic mesh is selected as the ultrasonic transmission body 30, not only the welding operation becomes easy, but also the melted resin enters between the meshes, so that the surface 30 a of the ultrasonic transmission body 30 is The ratio of the smooth surface can be increased, and the flow in the measurement channel 6 can be further stabilized by reducing the unevenness. Furthermore, by mixing about 20 to 30% of glass fiber into the resin material forming the inflow suppressing body 14, the thermal expansion coefficient is reduced to the same level as that of the mesh material, and the ultrasonic transmission body is formed by the mesh after the heat welding operation. 30 parts can be maintained flat, and the flow of the measurement flow path 6 can be stabilized by preventing the unevenness of the surface 30a of the ultrasonic transmission body 30 from occurring.

In this way, the inflow suppressor is formed of a resin material, and the ultrasonic transmission body is welded and joined, so that the inflow suppression body and the ultrasonic transmission body can be joined flush with each other. In addition, it is possible to improve the surface uniformity of the attachment portion of the ultrasonic transmission body of the inflow suppression body and prevent the disturbance of the flow in the vicinity of the wall surface of the measurement flow path, thereby improving the measurement accuracy and the upper limit value for measuring the flow rate. Furthermore, the inflow suppression body and the ultrasonic transmission body can be reliably integrated, and the reliability can be improved.

In addition, by mixing glass fiber into the resin material that forms the inflow suppressor, the thermal expansion coefficient can be reduced to maintain the flatness of the surface of the ultrasonic transmission body after heating and welding, thereby preventing irregularities from occurring. Thus, the flow of the measurement channel can be stabilized.

As described above, in the present embodiment, the inflow suppressing body includes an ultrasonic transmission body having a large number of fine openings through which ultrasonic waves can pass, so that the fluid to be measured flows into the opening hole. Can significantly reduce the generation of vortices in the aperture hole, further reduce the attenuation of ultrasonic waves caused by the vortices, further improve the transmission / reception level of ultrasonic waves and further improve the S / N characteristics. Transmission and reception can be performed, and the upper limit value for measuring accuracy and flow rate can be improved.

Further, in this embodiment, the inflow suppressor is formed of a resin material, and the ultrasonic transmission body is welded and joined, so that the inflow suppression body and the ultrasonic transmission body can be joined flush with each other. Improves the flushness of the flow path wall and the ultrasonic transmission body mounting part of the inflow suppressor to prevent disturbance of the flow near the measurement flow path wall, and improves the measurement accuracy and the upper limit of flow rate measurement. Reliability can be improved by the reliable integration of the suppressor and the ultrasonic transmission body.

Further, in this embodiment, the resin material forming the inflow suppressing body is mixed with glass fiber, so that the thermal expansion coefficient can be reduced and the ultrasonic transmission body after the heat welding operation can be maintained in the flatness of the surface. The flow of the measurement channel can be stabilized by preventing the occurrence of unevenness.

Note that as an application of the present embodiment, there is a configuration in which the opening window shown in FIG. 9 is not provided. With this configuration, by providing an ultrasonic transmission body at the opening of the opening hole, the fluid does not directly enter the opening hole, and the opening window 15 with a reduced cross-sectional area of the opening hole is eliminated, so that the attenuation of the ultrasonic wave is eliminated. There is little and sensitivity improves. In addition, if there is an open window, stagnation occurs on the inside, but since there is no such, accumulation of dust and the like can be prevented, improving reliability.

(Embodiment 4)
FIG. 10 shows a partial cross-sectional view of the ultrasonic flow rate measuring apparatus according to Embodiment 4 of the present invention. Here, the downstream opening hole 12 is shown, but the upstream opening hole 11 is the same. The same members and functions as those in the embodiment of FIGS. 1 to 6 are denoted by the same reference numerals, detailed description thereof is omitted, and different points will be mainly described.

31 is a sound absorbing means having an action of absorbing ultrasonic waves provided in the inflow suppressing body 14, and the sound absorbing means 31 is a sound absorbing means 31a provided on the surface 14a on the measurement flow path 6 side of the inflow suppressing body 14 and an ultrasonic transmitter / receiver. The sound absorbing means 31b is provided on the back surface 14b on the 9th side.

First, the case where ultrasonic waves are transmitted from the ultrasonic transmitter / receiver 9 on the downstream side will be described. By providing the sound absorbing means 31 in the inflow suppressor 14, unnecessary ultrasonic waves that do not pass through the opening window 15 among the ultrasonic waves transmitted from the ultrasonic transmitter / receiver 9 are provided on the back surface 14 b of the inflow suppressor 14. When it hits 31b, although the remaining sound is reflected, unnecessary ultrasonic waves are attenuated, and ultrasonic waves with improved S / N characteristics are transmitted toward the ultrasonic transmitter / receiver 8 on the upstream side which is the reception side. The

Next, a case where ultrasonic waves are transmitted from the ultrasonic transmitter / receiver 8 on the upstream side and received by the ultrasonic transmitter / receiver 9 on the downstream side will be described. The ultrasonic wave with improved S / N characteristics propagates to the receiving side and is received through the opening window 15 of the inflow suppressing body 14 on the downstream side. However, the ultrasonic wave hitting the downstream opening window 15 due to the spread during propagation is absorbed and attenuated by the sound absorbing means 31a provided on the surface 14a of the inflow suppressing body 14. Due to the sound absorbing action of the sound absorbing means 31a provided on the surface 14a of the inflow suppressing body 14, attenuation of multiple reflection is promoted, and ultrasonic waves with further improved S / N characteristics can be transmitted and received.

In this way, the inflow suppressor is equipped with ultrasonic sound absorption means, so that unnecessary ultrasonic waves that do not pass through the opening window are absorbed by the ultrasonic waves that hit the inflow suppressor, further promoting the attenuation of unnecessary ultrasonic waves. it can. For this reason, transmission / reception of ultrasonic waves with improved S / N characteristics can be further enhanced to improve measurement accuracy. Here, although the sound absorbing means is provided with the sound absorbing means 31a and 31b on the front surface 14a and the back surface 14b of the inflow suppressing body 14, respectively, it is also possible to use each independently.

FIG. 11 is a partial cross-sectional view showing another embodiment of the sound absorbing means. An ultrasonic transmission body 30 and a sound absorption means 31a are provided on the surface 14a of the inflow suppressing body 14 on the measurement flow path 6 side, and the ultrasonic transmission is performed. Where the body 30 is located, the sound absorbing means 31 a is disposed inside the ultrasonic transmission body 30.

For this reason, the attenuation of ultrasonic waves can be further reduced by reducing the inflow into the opening hole by the ultrasonic transmission body 30 and reducing the flow turbulence of the measurement flow path, and eliminating the cause of noise by reducing unnecessary reflected waves by the sound absorbing means 31. By the action, ultrasonic transmission / reception with further improved S / N characteristics by further improving the ultrasonic transmission / reception level can be achieved, and the measurement accuracy and the upper limit value at which the flow rate can be measured can be improved.

Further, by forming the inflow suppressing body 14 from a porous material, the inflow suppressing body 14 can be made compact and the sound absorption effect can be stabilized by stabilizing the shape and dimensions, and the measurement apparatus can be downsized and improved in reliability. Can do. Here, by forming with a foam metal having fine open cells, sufficient mechanical strength can be secured, and long-term reliability can be secured.

As described above, in the present embodiment, since the inflow suppression body includes the ultrasonic sound absorbing means, the ultrasonic waves that hit the inflow suppression body by unnecessary ultrasonic waves that do not pass through the opening window are absorbed and unnecessary. Attenuation of ultrasonic waves can be further promoted, and transmission / reception of ultrasonic waves with improved S / N characteristics can be further enhanced to improve measurement accuracy.

In addition, in this embodiment, since the inflow suppressor is formed of a porous material, the inflow suppressor can be made compact and the sound absorption effect can be stabilized by stabilizing the shape and dimensions, and the measurement apparatus can be downsized and reliable. Can improve the performance.

(Embodiment 5)
FIG. 12 is a partial cross-sectional view of an ultrasonic flow rate measuring apparatus according to Embodiment 5 of the present invention. Here, a downstream opening hole 12 is shown, but an upstream opening hole 11 is the same, and FIG. The same members and functions as those in the embodiment of FIGS. 1 to 8 are denoted by the same reference numerals, detailed description thereof is omitted, and different points will be mainly described.

The inflow suppressing body 14 provided with the opening hole insulator 21 and the opening window 15 is provided in the opening hole 12 portion, and the sound absorbing means 31 is provided at least on the inner surface 21c of the opening hole insulator 21. Here, as the sound absorbing means 31, the sound absorbing means 31 a provided on the front surface 14 a of the inflow suppressing body 14, the sound absorbing means 31 b provided on the back surface 14 b of the inflow suppressing body 14, and the sound absorbing means provided on the inner surface 21 c of the opening hole insulator 21. 31c.

The case where ultrasonic waves are transmitted from the ultrasonic transmitter / receiver 9 on the downstream side will be described. By providing the sound absorbing means 31 on the inner surface of the opening hole insulator 21, the ultrasonic waves transmitted from the ultrasonic waves transmitted from the ultrasonic transmitter / receiver 9 are provided on the inner surface 21 c of the opening hole insulator 21. By receiving the sound absorbing means 31c and being attenuated, the component reflected by the side wall and passing through the opening window 15 is reduced, and the ratio of the direct wave passing directly through the opening window 15 is increased to receive a transmission waveform with less noise. The accuracy of measurement can be increased by transmitting and receiving ultrasonic waves with improved S / N characteristics, and the upper limit value of the measurable flow rate can be increased. Furthermore, due to the electrical insulation of the opening hole insulator 21, even when an abnormally high voltage is generated between the attachment-side flow path body and the ultrasonic transmitter / receiver due to a lightning strike or the like, the withstand voltage leading to leakage is increased, and the ultrasonic wave generated by the leak current Reliability can be improved by preventing damage to the transceiver.

As described above, since the opening hole insulator includes the ultrasonic sound absorbing means, unnecessary ultrasonic waves transmitted to the side of the ultrasonic transceiver are absorbed and attenuated by the sound absorbing means provided in the opening hole insulator. And a transmission waveform with less noise can be obtained by increasing the proportion of direct waves that pass directly through the aperture window. For this reason, the upper limit of measurement accuracy and flow rate measurement can be increased by improving the transmission / reception level of ultrasonic waves and transmitting / receiving ultrasonic waves with improved S / N characteristics. Even when an abnormally high voltage is generated between the flow path body on the attachment side and the ultrasonic transmitter / receiver, the withstand voltage leading to leakage can be increased, and the ultrasonic transmitter / receiver can be prevented from being damaged by the leak current, thereby improving the reliability.

Further, the inflow suppression body 14 is formed of an electrically insulating material, and one end and the other end of the opening hole insulator are disposed in contact with the vibration transmission suppression body 10 and the inflow suppression body 14, respectively. By providing the means 31, it is possible to further enhance the acceleration of attenuation of unnecessary reflected waves of ultrasonic waves, improve the measurement accuracy by ultrasonic wave transmission / reception with further improved S / N characteristics and the upper limit value capable of measuring the flow rate, and abnormalities such as lightning strikes. The reliability of preventing damage to the ultrasonic transmitter / receiver due to leakage current when a high voltage is generated can be improved, and the measurement apparatus can be further downsized.

As described above, in the present embodiment, the opening hole insulator is provided with ultrasonic sound absorbing means, so that unnecessary ultrasonic waves transmitted to the side of the ultrasonic transceiver are provided in the opening hole insulator. Attenuation can be promoted by absorbing sound by the sound absorbing means, and the transmission waveform with less noise can be obtained by increasing the proportion of direct waves that pass directly through the aperture window, improving the transmission / reception level of ultrasonic waves and S / N characteristics. Increased transmission and reception of ultrasonic waves can increase the upper limit of measurement accuracy and flow rate measurement, and abnormally high voltage between the flow channel on the installation side and the ultrasonic transmitter / receiver due to lightning due to the electrical insulation of the opening hole insulator Even in the case of occurrence of a fault, the withstand voltage leading to the leak can be increased, and the ultrasonic transceiver can be prevented from being damaged by the leak current, thereby improving the reliability.

As an application of the present embodiment, as shown in FIG. 13, there is shown a configuration in which an opening window is not provided and a sound absorbing means is provided on the side surface of the opening hole and the surface of the inflow suppressing body so as to surround the ultrasonic transceiver. In this configuration, the internal reflection of the aperture hole is reduced to improve the S / N characteristics of the ultrasonic wave, and further, attenuation due to the aperture window with a reduced cross-sectional area does not occur. It can be further improved. Further, since there is no stagnation inside the opening window, accumulation of dust and the like can be prevented, and reliability is improved.

Furthermore, the configuration of FIG. 14 shows a configuration in which the sound absorbing means on the surface of the inflow suppressor is omitted. The surface 14a of the inflow suppressor 14 does not have a sound absorbing means that tends to be uneven, and the disturbance of the flow of the fluid to be measured in the vicinity of the flow path wall 6a can be reduced to stabilize the flow velocity distribution and improve the measurement accuracy.

(Embodiment 6)
FIG. 15 is a partial cross-sectional view of an ultrasonic flow rate measuring apparatus showing Embodiment 6 of the present invention. Here, a downstream opening hole 12 is shown, but an upstream opening hole 11 is also the same, and The same members and the same functions as those of the previous embodiments are denoted by the same reference numerals, detailed description thereof is omitted, and different points will be mainly described.

The cross-sectional shape through which the ultrasonic wave of the opening hole insulator 21 provided in the opening hole 12 passes is as close as possible to the shape of the opening window 15 and the cross-sectional area from the ultrasonic transceiver 9 side toward the measurement channel 6 side. It is a thing. Here, the cross-sectional shape on the ultrasonic transmitter / receiver 9 side is a circle having a diameter of about 14 mm, the cross-sectional shape on the measurement flow path 6 side is a shape close to a square hole of about □ 8 mm, which is the shape of the opening window 15, and a halfway is circular. The shape changes smoothly from square to square hole.

Here, a case where the ultrasonic transmitter / receiver 9 on the downstream side becomes the receiving side will be described. The ultrasonic wave transmitted from the upstream ultrasonic transmitter / receiver 8 propagates through the ultrasonic propagation path 13, passes through the opening window 15 of the downstream inflow suppression body 14, and enters the opening hole 12. In the opening hole 12, the passage cross section smoothly expands as the ultrasonic wave transmitter / receiver 9 is approached by the opening hole insulator 21, so that the dissipation of ultrasonic waves in the opening hole 12 is reduced and ultrasonic transmission / reception on the receiving side is performed. A signal with high reception sensitivity can be obtained. Further, when the downstream ultrasonic transmitter / receiver 9 is on the transmission side, the transmitted ultrasonic wave is less spread by the opening hole insulator 21 having a cross-sectional shape that smoothly reduces toward the opening window 15. Ultrasonic waves are transmitted and received as enhanced ultrasonic waves through the downstream opening window 15 and propagated to the upstream ultrasonic transmitter / receiver 8 which is the receiving side, thereby increasing the sensitivity.

As described above, in the present embodiment, the cross-sectional shape through which the ultrasonic wave of the opening hole insulator passes is made asymptotic to the shape of the open window toward the measurement channel side, so that the ultrasonic wave that has passed through the open window Can reduce the dissipation in the opening hole and reach the ultrasonic transmitter / receiver on the receiving side, and can increase the measurement accuracy and the upper limit of flow rate measurement by transmitting / receiving ultrasonic waves with improved sensitivity.

As described above, the ultrasonic flow measuring device according to the present invention increases the conductive distance between the ultrasonic transmitter / receiver and the flow path body that forms the opening hole by the opening hole insulator even in a compact storage space. Even if an abnormally high voltage occurs between the flow path body on the mounting side and the ultrasonic transmitter / receiver, etc., the withstand voltage leading to leakage can be increased, and the ultrasonic transmitter / receiver can be prevented from being damaged by leakage current, improving reliability, and being compact Therefore, it can be applied to an ultrasonic flow rate measuring device that measures the flow rate and flow rate of gas and liquid.

Cross-sectional view of the configuration of the ultrasonic flow rate measuring apparatus according to Embodiment 1 of the present invention Partial sectional view of the opening hole in FIG. The fragmentary sectional view of the opening hole part which shows the opening hole insulator of Embodiment 2 of this invention The fragmentary sectional view of the opening hole which shows the other opening hole insulator of Embodiment 2 of this invention Partial sectional view showing another embodiment of the same insulator Partial sectional view showing another embodiment of the same insulator Partial sectional view showing still another embodiment of the insulator The fragmentary sectional view of the opening hole which shows the ultrasonic transmission body of Embodiment 3 of this invention The fragmentary sectional view of the opening hole which shows the ultrasonic transmission body of Embodiment 3 of this invention The fragmentary sectional view of the opening hole which shows the sound absorption means of Embodiment 4 of this invention Partial sectional view of another opening hole of the sound absorbing means The fragmentary sectional view of the opening hole part which shows the opening hole insulator of Embodiment 5 of this invention The fragmentary sectional view of the opening hole part which shows the other opening hole insulator of Embodiment 5 of this invention The fragmentary sectional view of the opening hole which shows another opening hole insulator of Embodiment 5 of this invention The fragmentary sectional view of the opening hole which shows the opening hole insulator of Embodiment 6 of this invention Cross-sectional view of a conventional ultrasonic flow measurement device

Explanation of symbols

6 Measurement Channel 6a Channel Wall 8, 9 Ultrasonic Transmitter / Receiver 11, 12 Open Hole 14 Inflow Suppressor 15 Open Window 21 Open Hole Insulator 30 Ultrasonic Transmitter 31 Sound Absorbing Means

Claims (11)

A measurement channel through which a fluid flows, ultrasonic transmitters / receivers provided on the upstream side and downstream side of the measurement channel, and upstream and downstream opening holes that allow the ultrasonic transmitter / receiver to face the measurement channel, An ultrasonic flow rate measuring device comprising: an opening hole insulator formed of an electrically insulating material disposed on an inner surface of the opening hole; and an inflow suppressing body in the opening hole. The ultrasonic flow rate measuring device according to claim 1, wherein a surface of the inflow suppressing body on the ultrasonic transmitter / receiver side is obliquely crossed with an ultrasonic wave propagation direction. The ultrasonic flow rate measuring device according to claim 1 or 2, wherein the inflow suppressing body is formed of an electrically insulating material, and an end of the opening hole insulator on the measurement flow path side is in contact with the inflow suppressing body. The ultrasonic flow measuring device according to any one of claims 1 to 3, wherein the inflow suppressing body and the opening hole insulator are integrated. The ultrasonic flow measuring device according to any one of claims 1 to 4, wherein the inflow suppressing body includes an ultrasonic transmission body having a large number of fine openings through which ultrasonic waves can pass in an opening window. The ultrasonic flow rate measuring device according to claim 1, wherein the inflow suppressing body is formed of a resin material, and an ultrasonic transmission body is welded and joined. The ultrasonic flow rate measuring device according to claim 6, wherein the resin material forming the inflow suppressing body is mixed with glass fiber. The ultrasonic flow rate measuring device according to claim 1, wherein the inflow suppressing body includes ultrasonic sound absorbing means. The ultrasonic flow rate measuring device according to claim 1, wherein the inflow suppressing body is formed of a porous material. The ultrasonic flow rate measuring device according to any one of claims 1 to 9, wherein the opening hole insulator includes an ultrasonic sound absorbing means. The ultrasonic flow rate measuring device according to any one of claims 1 to 10, wherein a cross-sectional shape through which the ultrasonic wave of the opening hole insulator passes is a shape that gradually approaches the shape of the opening window toward the measurement channel side.

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