JP2005134212A - Ultrasonic sensor and ultrasonic flow measuring device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent leakage ultrasonic waves from spreading through a flow meter main body or a vortex generator. <P>SOLUTION: In an ultrasonic vortex flowmeter 10, an exciting force of a piezo-electric element 70 is transmitted to a diaphragm 72c, whereby ultrasonic waves are emitted into fluid, and the leakage ultrasonic waves spread to a holding member 39 through a cylindrical section 72a of a sensor holder 72 and a covering member 78. Each fluid in channels 18, 20 is supplied to a space 38c, whereby the diaphragm 72c and the covering member 78 are placed under the same pressure, and the strength of a conduit line 78b can be reduced. Therefore, the cross-section area of wall thickness of the conduit line 78b being perpendicular to the axis of the conduit line 78b is made smaller than the cross-section area of wall thickness of the cylindrical section 72a being perpendicular to the axis of the cylindrical section 72a. Thus, the ultrasonic waves leaking from the cylindrical section 72a is attenuated at the conduit line 78b in accordance with the reduced cross-section area. As a result, leakage sonic waves from the sensor holder 72 to a sensor mounting section 38 are decreased, and a sufficient S/N ratio is assured. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an ultrasonic sensor and an ultrasonic flow measuring device that transmit ultrasonic waves into a fluid to be measured to detect Karman vortices generated downstream of the vortex generator and measure the flow rate of the fluid to be measured.

  Hereinafter, the prior art will be described using an ultrasonic vortex flowmeter as an example of an ultrasonic flow measuring device.

  Generally, in a conventional ultrasonic vortex flowmeter, a vortex generator extending in a direction perpendicular to the flow direction is provided in a flow path in which a fluid to be measured flows, and one set or Two sets of ultrasonic sensors are provided to detect Karman vortices generated downstream of the vortex generator. One set of ultrasonic sensors is provided in the flow path so as to face each other, one is a transmitting side that transmits ultrasonic waves, and the other is a receiving side that receives ultrasonic waves propagated in the fluid to be measured It becomes.

  In this type of ultrasonic vortex flowmeter, an ultrasonic reception signal propagated through a Karman vortex generated alternately in proportion to the flow velocity in the flow path, and an ultrasonic signal supplied to the transmission side. By comparing the phase with the transmission signal of the sound wave, the Doppler effect that the ultrasonic wave receives from the Karman vortex is detected as a sinusoidal phase modulation amount.

  In addition, in an ultrasonic vortex flowmeter using two sets of ultrasonic sensors, by comparing the phases of two ultrasonic signals that propagate the fluid from the opposite directions relative to the Karman vortex flow, Only the phase change received from the Karman vortex is extracted by canceling the influence of the sound velocity change of the fluid to be measured.

  The conventional ultrasonic vortex flowmeter configured as described above is theoretically configured to extract the Doppler effect received by the ultrasonic wave from the Karman vortex as a phase change, so that it is independent of the type of fluid being measured. Vortices can be detected.

  However, in the ultrasonic vortex flowmeter in which the ultrasonic sensor is provided in the pipe through which the fluid to be measured flows as described above, the ultrasonic wave transmitted from the ultrasonic sensor on the transmission side generates the flowmeter main body (pipeline) and vortex generation. The signal is also transmitted to the body as leaked ultrasonic waves, and the reception-side ultrasonic sensor receives a combined signal in which the ultrasonic wave propagated through the fluid to be measured and the signal propagated through the pipeline are combined.

  Therefore, leaked ultrasonic waves propagated through the pipeline in the process of generating the flow rate pulse by receiving the above synthesized signal will be detected as noise, resulting in deterioration of the sensor S / N, due to missing pulses, etc. It may cause a decrease in measurement accuracy, or the low flow detection sensitivity may deteriorate.

As means for solving such a problem, for example, a sensor holder in which a piezoelectric element is accommodated is inserted into cylindrical portions formed at both ends of the vortex generator, and a flange of the sensor holder and a flange of the cylindrical portion are arranged. There is an arrangement in which an elastic member (O-ring) is interposed between the two so that vibration due to the piezoelectric element does not propagate to the vortex generator (for example, see Patent Document 1).
JP 2000-193502 A

  As described above, the ultrasonic sensor mounting structure includes a piezoelectric element that vibrates the diaphragm at a predetermined cycle by a signal from the oscillator, and a sensor holder that houses the piezoelectric element. In order to ensure insulation of the ultrasonic propagation path between the flowmeter body holding the holder, an elastic body (O-ring, etc.) made of a rubber material is interposed between the sensor holder and the flowmeter body. Is held in a floating structure.

  In the floating structure in which the elastic body is interposed, since the ultrasonic wave propagated to the elastic O-ring is attenuated inside the elastic O-ring, the sound pressure of the ultrasonic wave leaking to the flowmeter body is low.

  However, the structure of the above publication has a property that an elastic body made of a rubber material is hardened at a low temperature, so that leakage of sound waves from the ultrasonic sensor to the main body increases, and there is a possibility that sufficient sensor S / N cannot be secured. is there.

  In addition, since the diaphragm of the ultrasonic sensor is a pressure receiving surface for the pressure of the fluid to be measured, the sensor holder must be firmly fastened to the flowmeter body so that it can withstand this pressure. The elasticity of the elastic body interposed between the sensor holder and the flow meter body decreases, and as a result, leakage of sound waves from the ultrasonic sensor to the main body may increase, making it impossible to secure a sufficient S / N ratio. There is.

In addition, when the diameter of the flow meter (flow path inner diameter) is increased, the separation distance between the ultrasonic transmitter and the ultrasonic receiver is increased, and the propagation distance of the ultrasonic wave is increased correspondingly, resulting in a decrease in transmission / reception efficiency. There arises a problem that it is difficult to secure a sufficient S / N ratio.
Accordingly, an object of the present invention is to provide an ultrasonic sensor and an ultrasonic flow rate measuring apparatus that solve the above-described problems.

The invention according to claim 1 is a piezoelectric element that vibrates by application of a voltage;
A sensor holder that houses the piezoelectric element;
In an ultrasonic sensor having
The sensor holder is
Storage for storing the piezoelectric element from a diaphragm that contacts the piezoelectric element, a cylindrical portion that is continuously formed on the diaphragm and covers the outer periphery of the piezoelectric element, and a closing member that closes the opening of the cylindrical portion A piezoelectric element housing portion in which a space is formed;
An internal space having a space portion penetrating in the axial direction for insertion of an electric wire for applying a voltage to the piezoelectric element, and one end of which is coupled to a closing member of the piezoelectric element housing portion;
Consists of
The cross-sectional area in the direction orthogonal to the axial direction of the wall thickness of the pipe line is set smaller than the cross-sectional area in the direction orthogonal to the axial direction of the wall thickness of the cylindrical portion.

The invention according to claim 2 is a flow meter body in which a flow path through which a fluid to be measured flows is formed,
An ultrasonic transmitter for transmitting ultrasonic waves;
An ultrasonic receiver for receiving the ultrasonic wave transmitted from the ultrasonic transmitter;
A holding member for fixing and holding the ultrasonic transmitter and the ultrasonic receiver to the flowmeter body;
In an ultrasonic flow measurement device for measuring the flow rate of the fluid to be measured flowing through the flow path based on the reception signal received by the ultrasonic receiver,
At least one of the ultrasonic transmitter and the ultrasonic receiver is:
A piezoelectric element that vibrates when a voltage is applied;
A sensor holder that houses the piezoelectric element;
An ultrasonic sensor having
The sensor holder is
A housing for housing the piezoelectric element from a diaphragm that contacts the piezoelectric element, a cylindrical portion that is continuously formed on the diaphragm and covers the outer periphery of the piezoelectric element, and a closing member that closes the opening of the cylindrical portion. A piezoelectric element housing portion in which a space is formed;
An internal space having a space portion penetrating in the axial direction so that an electric wire for applying a voltage to the piezoelectric element is inserted therein, one end of which is coupled to a closing member of the piezoelectric element housing portion;
Consists of
The cross-sectional area in the direction orthogonal to the axial direction of the wall thickness of the pipe line is set smaller than the cross-sectional area in the direction orthogonal to the axial direction of the wall thickness of the cylindrical portion.

According to a third aspect of the present invention, the ultrasonic sensor is provided so as to be relatively displaceable with respect to the holding member, and is provided with a biasing member that biases the ultrasonic sensor in the separation direction with respect to the holding member. And providing a vortex generator perpendicular to the flow direction in the flow path,
The vortex generator has a passage communicating with the flow path of the flowmeter main body, and the ultrasonic wave receiver is in contact with the first mounting portion where the ultrasonic transmitter abuts in the middle of the passage. A second attachment portion that comes into contact is provided.

  According to a fourth aspect of the present invention, there is provided a passage through which fluid can pass through the contact portion of the ultrasonic transmitter of the first attachment portion and the contact portion of the ultrasonic receiver of the second attachment portion. An annular member having the above is provided.

  The invention according to claim 5 is characterized in that an annular member having a passage through which a fluid can pass is provided on the outer periphery of the cylindrical portion of the ultrasonic transmitter and the ultrasonic receiver.

The invention according to claim 6 is the ultrasonic flow measuring device according to claim 2,
An electric wire from a piezoelectric element housed in the sensor holder of the ultrasonic transmitter and ultrasonic receiver is inserted into the conduit and connected to a substrate housed in the holding member;
The pipe line is integrally coupled to the sensor holder.

  The invention according to claim 7 is provided with a sound absorbing material that absorbs ultrasonic waves between an inner circumference of an ultrasonic wave propagation path into which the ultrasonic transmitter and the ultrasonic receiver are inserted and an outer circumference of the sensor holder. It is characterized by.

  The invention according to claim 8 is characterized in that a sound absorbing material for absorbing ultrasonic waves is provided on the outer periphery of the pipe.

  The invention according to claim 9 is characterized in that the sound absorbing material guides the position of the sensor holder with respect to the inner periphery of the ultrasonic wave propagation path.

The invention according to claim 10 is the ultrasonic flow measuring device according to claim 2,
A pair of the ultrasonic transmitters is provided,
A pair of the ultrasonic receivers are provided,
A substrate is provided on the holding member;
The substrate is
A drive circuit having a pair of connection terminals to which the pair of ultrasonic transmitters are connected;
A receiving circuit having a pair of connection terminals to which the pair of ultrasonic receivers are connected;
The pair of connection terminals of the receiving circuit are provided at positions spaced apart from both sides of the pair of connection terminals of the drive circuit.

  According to invention of Claim 1 and 2, the cross-sectional area of the direction orthogonal to the axial direction of the thickness of the pipe line of a sensor holder is made smaller than the cross-sectional area of the direction orthogonal to the axial direction of the thickness of a cylinder part. Since it is set, vibration from the piezoelectric element is attenuated by the pipe line, and leakage of ultrasonic waves can be prevented.

  According to the third aspect of the present invention, since the ultrasonic sensor is provided so as to be relatively displaceable with respect to the holding member, the position of the ultrasonic sensor is adjusted with respect to the holding member and the attachment provided in the passage Aligned with the part. Therefore, the length of the pipe path of the sensor holder and the position in the radial direction can be processed more easily than the configuration in which the pipe path of the sensor holder is integrated with the holding member.

  According to the fourth aspect of the present invention, the passage through which the fluid can pass is provided in the contact portion of the ultrasonic transmitter of the first attachment portion and the contact portion of the ultrasonic receiver of the second attachment portion. Since the annular member is provided, it is possible to guide the mounting position in the radial direction of the ultrasonic transmitter and the ultrasonic receiver while keeping the separation distance between the ultrasonic transmitter and the ultrasonic receiver constant by the contact portion. In addition, the pressure difference applied to the upper part and the lower part of the cylindrical part through the passage of the annular member is reduced, and the thickness of the pipe line can be reduced to reduce the strength.

  According to the fifth aspect of the present invention, since the annular member having the passage through which the fluid can pass is provided on the outer periphery of the cylindrical portion of the ultrasonic transmitter and the ultrasonic receiver, the radii of the ultrasonic transmitter and the ultrasonic receiver are provided. In addition to guiding the mounting position in the direction, the pressure difference applied to the upper part and the lower part of the cylindrical part is reduced by the passage of the annular member, and the thickness of the pipe line can be reduced to reduce the strength.

  According to the sixth aspect of the invention, in the ultrasonic flow measuring device according to the second aspect, the electric wire from the piezoelectric element housed in the sensor holder of the ultrasonic transmitter and the ultrasonic receiver is connected to the conduit. Is connected to the substrate housed in the holding member and the pipe line is integrally coupled to the sensor holder, so that each electric wire can be arranged so as not to get entangled, and the ultrasonic transmitter and the ultrasonic receiver are held. Assembling work and maintenance can be performed as a unit integrated with the member.

  According to the seventh aspect of the present invention, the sound absorbing material for absorbing ultrasonic waves is provided between the inner periphery of the ultrasonic propagation path into which the ultrasonic transmitter and the ultrasonic receiver are inserted and the outer periphery of the sensor holder. By absorbing sound waves traveling in an oblique direction with respect to the flow direction, leakage of ultrasonic waves can be prevented.

  According to the eighth aspect of the present invention, since the sound absorbing material that absorbs the ultrasonic waves is provided on the outer periphery of the pipe, the sound waves traveling in an oblique direction with respect to the flow direction are prevented from being irregularly reflected in the pipe, Can prevent noise.

  According to the ninth aspect of the invention, the sound absorbing material guides the position of the sensor holder with respect to the inner circumference of the ultrasonic wave propagation path so that the sensor holder does not contact the inner circumference of the ultrasonic wave propagation path. Thus, leakage of ultrasonic waves can be prevented.

  According to the invention described in claim 10, since the pair of connection terminals of the receiving circuit are provided at positions separated from both sides of the pair of connection terminals of the drive circuit, the electric wires from the piezoelectric elements are not entangled, And the crosstalk between electric wires and connection terminals can be prevented by separating the electric wires on the receiving side.

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

  FIG. 1 is a block diagram showing an embodiment of an ultrasonic sensor and an ultrasonic flow measuring device according to the present invention. FIG. 2 is a cross-sectional view of the ultrasonic flow measuring device.

  As shown in FIGS. 1 and 2, an ultrasonic vortex flow meter 10 as an ultrasonic flow measuring device includes a flow meter body 14 having a flow path 12 through which a fluid to be measured flows, and a flow meter body 14. And a vortex generator 16 extending in a vertical direction perpendicular to the flow direction of the fluid to be measured (indicated by an arrow in FIG. 2). The vortex generator 16 has a substantially pentagonal cross section when viewed from above.

  Then, in the process in which the fluid to be measured flows downstream while colliding with the front surface 16 a of the vortex generator 16 facing the upstream side, Karman vortices are alternately generated on the left and right sides of the vortex generator 16. Since the frequency at which this Karman vortex is generated is proportional to the flow velocity of the fluid to be measured, the flow velocity of the fluid to be measured can be obtained by detecting the number of Karman vortices generated in the fluid to be measured. The flow rate is calculated from the diameter.

  The vortex generator 16 has a pair of passages 18 and 20 extending in the longitudinal direction penetrating as an ultrasonic wave propagation path. The passages 18 and 20 communicate with first to fourth pressure introduction passages 22, 24, 26, and 28 that open to oblique sides 16 b and 16 c formed on the downstream side of the vortex generator 16, respectively. The pressure introduction paths 22, 24, 26, and 28 are shifted in the longitudinal direction (height direction) of the vortex generator 16, and are provided so as not to cross each other.

  As shown in FIG. 2, the first pressure introduction path 22 has one end opened to the hypotenuse 16 b and the other end communicated with the passage 18. Further, one end of the second pressure introduction path 24 opens to the hypotenuse 16 c and the other end communicates with the passage 20. The third pressure introduction path 26 has one end opened to the hypotenuse 16 b and the other end connected to the path 20. The fourth pressure introduction path 28 has one end opened to the hypotenuse 16 c and the other end connected to the passage 18.

  Accordingly, when a Karman vortex is generated in the fluid to be measured flowing downstream of the vortex generator 16, a pressure difference is generated on both the left and right sides of the vortex generator 16 due to a pressure change caused by the generation of the Karman vortex. , 20 generates a fluid flow to be measured. That is, in the passages 18 and 20, a reverse flow alternately occurs at the same cycle as the generation of the Karman vortex.

  A sensor attachment portion 38 to which a pair of transmission-side ultrasonic sensors (ultrasonic transmitters) 30 and 32 are attached is provided at the upper end of the vortex generator 16. A holding member 39 that holds the transmission-side ultrasonic sensors 30 and 32 is provided on the upper part of the sensor mounting portion 38.

  A sensor mounting portion 40 to which a pair of reception-side ultrasonic sensors (ultrasonic receivers) 34 and 36 are mounted is provided at the lower end of the vortex generator 16. A holding member 41 that holds the reception-side ultrasonic sensors 34 and 36 is provided below the sensor mounting portion 40. Each ultrasonic sensor 30, 32, 34, 36 is inserted into mounting holes 38a, 38b, 40a, 40b provided in the sensor mounting portions 38, 40.

  The ultrasonic sensors 30, 32, 34, and 36 are provided at positions that are symmetrical in FIG. That is, the separation distance between the transmission-side ultrasonic sensor 30 and the reception-side ultrasonic sensor 34 arranged on the left side and the separation distance between the transmission-side ultrasonic sensor 32 and the reception-side ultrasonic sensor 36 arranged on the right side are: They are arranged to be the same.

  The mounting holes 38a, 38b, 40a, 40b into which the ultrasonic sensors 30, 32, 34, 36 are inserted communicate with the upper and lower openings of the passages 18, 20, respectively. The ultrasonic waves transmitted from the transmission side ultrasonic sensors 30 and 32 propagate through the fluid in the passages 18 and 20 and are received by the reception side ultrasonic sensors 34 and 36.

  At that time, the ultrasonic wave propagating in the passages 18 and 20 is modulated by the flow velocity of the fluid to be measured flowing in the passages 18 and 20 due to the pressure difference between the left and right sides of the vortex generator 16 accompanying the generation of Karman vortex. Therefore, the detection signals output from the reception-side ultrasonic sensors 34 and 36 are demodulated to detect the Karman vortex generation frequency, and the flow rate of the fluid to be measured flowing in the flow path 12 is measured based on this frequency. it can.

  As shown in FIG. 1, the drive circuit 42 includes an oscillation circuit 44 that outputs a drive signal having a constant period, and the drive signal output from the oscillation circuit 44 is used as a pair of transmission-side ultrasonic sensors 30 and 32. Output to.

  In this manner, the pair of transmission-side ultrasonic sensors 30 and 32 each receive a drive signal from the drive circuit 42 and vibrate according to the drive signal from the oscillation circuit 44 to be superfluid in the fluid in the passages 18 and 20. Send sound waves.

  Then, the ultrasonic waves propagating through the passages 18 and 20 penetrating the vortex generator 16 are received by the reception-side ultrasonic sensors 34 and 36.

  Therefore, the ultrasonic signals received by the reception-side ultrasonic sensors 34 and 36 are only the ultrasonic waves propagating in the passages 18 and 20 from the transmission-side ultrasonic sensors 30 and 32 to the reception-side ultrasonic sensors 34 and 36. Received. The reception-side ultrasonic sensors 34 and 36 are connected to a calculation unit 46 that calculates a flow rate.

  The calculation unit 46 as a reception circuit includes reception amplification circuits 48 and 50, waveform shaping circuits 52 and 54, a phase comparison circuit 56, and a flow rate calculation unit 60. The flow rate calculation unit 60 calculates the flow rate of the fluid to be measured flowing through the flow path 12 based on the Karman vortex frequency obtained from the phase difference between the reception signals output from the reception-side ultrasonic sensors 34 and 36.

  Here, the structure of the sensor attachment part 38, the holding member 39, the sensor attachment part 40, and the holding member 41 is demonstrated.

  The sensor mounting portion 38 and the holding member 39 provided on the upper portion of the vortex generator 16 have the same configuration as the sensor mounting portion 40 and the holding member 41 provided on the lower portion of the vortex generator 16 and are arranged vertically symmetrically. Has been. Therefore, the configuration of the sensor mounting portion 38 and the holding member 39 will be described, and the description of the sensor mounting portion 40 and the holding member 41 will be omitted.

FIG. 3 is an enlarged longitudinal sectional view showing the mounting structure of the sensor mounting portion 38 and the holding member 39.
As shown in FIG. 3, the sensor mounting portion 38 includes sensor insertion holes 38a and 38b communicating with the passages 18 and 20, and a space 38c communicating with the sensor insertion holes 38a and 38b above the sensor insertion holes 38a and 38b. Is provided. Further, on the inner walls of the sensor insertion holes 38a and 38b, there are provided attachment portions 64 for locking the guide rings 62 with which the insertion side end portions of the transmission side ultrasonic sensors 30 and 32 abut. The guide ring 62 is brought into contact with the contact portion 64a of the guide ring mounting portion 64 and locked.

  In addition, a seal groove 68 for mounting a seal member (O-ring) 66 is provided on the upper part of the sensor mounting portion 38. The seal member 66 is compressed by tightening the mounting bolt 69 in a state where the holding member 39 is in contact with the upper surface of the sensor mounting portion 38 and seals between the sensor mounting portion 38 and the holding member 39.

  The transmission-side ultrasonic sensors 30 and 32 include a piezoelectric element 70 and a sensor holder 72 that holds the piezoelectric element 70. The piezoelectric element 70 is accommodated in the interior 72 b of the cylindrical portion 72 a of the sensor holder 72.

  The sensor holder 72 is attached so that the bottom surface of the cylindrical portion 72 a is a diaphragm 72 c and the diaphragm 72 c faces the passages 18 and 20. Accordingly, when a drive signal having a fixed period is supplied to the piezoelectric elements 70 of the transmission-side ultrasonic sensors 30 and 32, the piezoelectric elements 70 vibrate the diaphragm 72c and transmit ultrasonic waves toward the passages 18 and 20. .

  The guide ring 62 is formed in a ring shape from, for example, tetrafluoroethylene resin, and a concave portion 62a with which the corner portion 72d of the sensor holder 72 abuts is provided on the inner periphery. The guide ring 62 is positioned at the center of the sensor insertion holes 38a and 38b so that the sensor holder 72 does not contact the sensor insertion holes 38a and 38b, and functions as a guide portion for positioning the insertion position in the axial direction.

  Further, the guide ring 62 is prevented from dropping downward by the contact portion 64a of the guide ring mounting portion 64 formed in the passages 18 and 20 of the sensor mounting portion 38. The guide ring 62 is formed with a groove 74 extending in the radial direction and the vertical direction with respect to the guide ring mounting portion 64. Therefore, the passages 18 and 20 communicate with the sensor insertion holes 38 a and 38 b and the space 38 c through the groove 74.

  As a result, the fluid in the passages 18 and 20 also flows into the sensor insertion holes 38a and 38b and the space 38c, and the pressure in the passages 18 and 20 and the pressure in the sensor insertion holes 38a and 38b and the space 38c are the same. Become pressure.

  On the other hand, the sensor holder 72 has a disk-like lid member 78 that closes the inside 72b of the cylindrical portion 72a fixed by welding or brazing. Further, the lid member 78 includes a lid portion 78a that closes the cylindrical portion 72a, and a small-diameter pipe 78b that projects to the center of the upper surface of the lid portion 78a. The pipe line 78 b is formed in a hollow shape having a passage (space) for inserting the lead wire (electric wire) 82.

  A pipe 80 having the same diameter is coupled to the upper end of the pipe line 78b by welding or brazing, and the upper end of the pipe 80 is welded or brazed to the pipe line 39a protruding from the lower surface of the holding member 39. Are combined. The pipe 39a communicates with a through hole 39b penetrating the holding member 39 in the vertical direction, and a pipe 76 having the same diameter is coupled to the pipe 39c protruding from the upper surface of the holding member 39 by welding or brazing. Has been.

  The lead wire 82 connected to the piezoelectric element 70 is inserted into the pipe line 78b, the pipe 80, the through hole 39b, and the pipe line 39c, and is drawn out from the inside 72b of the cylindrical portion 72a to be connected to the oscillation circuit 44. Is done. Thus, since the sensor holder 72 is supported by the pipe line 78b having a smaller diameter than the cylindrical portion 72a, the difference in the pressing force between the pressure in the passages 18 and 20 and the pressure in the sensor insertion holes 38a and 38b and the space 38c. That is, it is pressed upward by the pressure acting on the area (Sa-Sb) obtained by subtracting the pressure receiving area Sb of the lid portion 78a (the area excluding the cross-sectional area of the pipe line 78b) from the pressure receiving area Sa of the pressure diaphragm 72c. become.

  Therefore, the pressing force in the direction in which the sensor holder 72 acting on the pipe line 78b is separated from the guide ring 62 is reduced, and the strength of the pipe line 78b can be reduced accordingly. For this reason, the cross-sectional area in the direction orthogonal to the axial direction of the wall thickness of the pipe line 78b can be made smaller than the cross-sectional area in the direction orthogonal to the axial direction of the wall thickness of the cylindrical portion 72a. Therefore, the ultrasonic wave leaking from the cylindrical portion 72a in the pipe line 78b can be attenuated. Therefore, sound wave leakage from the sensor holder 72 to the sensor mounting portion 38 is reduced, and a sufficient S / N ratio can be secured.

  Therefore, the vibration (leakage ultrasonic wave) from the sensor holder 72 is difficult to propagate to the vortex generator 16. Therefore, most of the vibration (leakage ultrasonic wave) from the sensor holder 72 is attenuated and does not propagate to the sensor mounting portion 38, but propagates to the reception-side ultrasonic sensors 34 and 36 via the vortex generator 16 and the flowmeter main body 14. Is prevented.

  As described above, in the ultrasonic vortex flowmeter 10, leaked ultrasonic waves do not propagate to the vortex generator 16 and the flowmeter main body 14 via the sensor mounting portion 38, so that the noise superimposed on the received signal is reduced and the flow rate is reduced. Measurement accuracy can be improved. For this reason, the flow rate measurement accuracy in the low temperature region can be ensured, and the flow rate of the fluid to be measured can be accurately measured even in a low temperature environment such as a cold region having a relatively low temperature or a refrigeration facility.

  Further, in the ultrasonic vortex flowmeter 10, since the modulation by the Karman vortex is small at a low flow rate, the S / N ratio due to the leaked ultrasonic wave is easily influenced, but the occurrence of a missing pulse or the like is detected. It is possible to prevent the sensitivity from deteriorating or the flow rate signal from becoming unstable, resulting in a decrease in accuracy or inability to measure.

Here, Modification 1 will be described.
FIG. 4 is an enlarged longitudinal sectional view showing a main part of the first modification. In FIG. 4, the same parts as those in the above embodiment are denoted by the same reference numerals, and the description thereof is omitted.

  As shown in FIG. 4, in the ultrasonic vortex flowmeter 90 of the first modification, a pipe 92 having the same diameter is coupled to the upper end of the hollow portion 78 b of the sensor holder 72 by welding or brazing. The pipe line 92 is inserted into an attachment hole 39d penetrating the holding member 39 so as to be movable in the axial direction (vertical direction), and is sealed by a seal member (O-ring) 94 attached to the inner wall of the attachment hole 39d. ing.

  The lead wire 82 connected to the piezoelectric element 70 is drawn out from the inside 72b of the cylindrical portion 72a through the hollow portion 78b and the conduit 92.

  Further, a biasing member 96 made of a coil spring is interposed between the upper surface of the lid portion 78 a of the lid member 78 fixed to the sensor holder 72 and the lower surface of the holding member 39. This urging member 96 has a slightly stronger spring force than the pressure acting on the area (Sa-Sb) obtained by subtracting the pressure receiving area Sb (the area excluding the hollow part 78b) of the lid part 78a from the pressure receiving area Sa of the diaphragm 72c. Spring constants (values based on conditions such as spring material, inner diameter, wire diameter, pitch, number of turns, etc.) are set so as to be generated.

  The guide ring 62 that contacts the corner 72d of the diaphragm 72c of the sensor holder 72 is provided with a groove 74 that extends in the radial direction and the vertical direction with respect to the guide ring mounting portion 64 in the passages 18 and 20. ing.

  Further, since the conduit 92 formed integrally with the sensor holder 72 is inserted in the mounting hole 39d so as to be movable in the axial direction (vertical direction), the sensor holder 72 is attached when the sensor holder 72 is attached to the sensor attachment portion 38. Can be held at a position where it abuts against the guide ring 62. Therefore, the sensor holder 72 is positioned and the measurement accuracy is maintained. In this way, the length and radial alignment of the pipe 92 with respect to the holding member 39 are easily performed, and further, it is not necessary to increase the processing accuracy as compared with the one in which the pipe 92 is integrally coupled to the holding member 39. Processing is easy.

Here, Modification 2 will be described.
FIG. 5 is a longitudinal sectional view for explaining the configuration of the second modification. In FIG. 5, the same parts as those in the above embodiment are denoted by the same reference numerals, and the description thereof is omitted.

  As shown in FIG. 5, in the ultrasonic vortex flowmeter 100 of the second modification, the transmission-side ultrasonic sensor 30, the intermediate position in the longitudinal direction (longitudinal direction) in the passages 18 and 20 of the vortex generator 16, The first mounting portions 102 and 104 with which 32 abuts and the second mounting portions 106 and 108 with which the receiving-side ultrasonic sensors 34 and 36 abut are provided. The first mounting portions 102 and 104 and the second mounting portions 106 and 108 have a contact portion 64a with which the guide ring 62 contacts in the same manner as the guide ring mounting portion 64 described above. Omitted.

  Therefore, when the inner diameter (portion) of the flow path 12 of the flow meter main body 14 is large, the separation distance between the first mounting portions 102 and 104 and the second mounting portions 106 and 108 does not increase, and the transmission side ultrasonic sensor The ultrasonic waves transmitted from 30 and 32 are prevented from being attenuated before reaching the reception-side ultrasonic sensors 34 and 36, and it is possible to ensure reception sensitivity regardless of the inner diameter (caliber) of the flow path 12. Become.

  Therefore, in the ultrasonic vortex flowmeter 100, the separation distance between the transmission-side ultrasonic sensors 30, 32 and the reception-side ultrasonic sensors 34, 36 is constant regardless of the inner diameter (caliber) of the flow path 12. By setting the positions of the first mounting portions 102 and 104 and the second mounting portions 106 and 108, the S / N ratio is stable even at a low flow rate with small modulation due to Karman vortex, resulting in a decrease in accuracy and inability to measure. Can be prevented.

  Pressure passages 22, 24, 26, and 28 that open to both sides of the vortex generator 16 are communicated with the passages 18 and 20. Therefore, the generation of Karman vortex causes a pressure difference on both sides of the vortex generator 16, and fluid flows in the passages 18 and 20.

  In addition, by setting the separation distance between the first attachment portions 102 and 104 and the second attachment portions 106 and 108 to an arbitrary distance, the ultrasonic wave propagating in the passages 18 and 20 causes the generation of Karman vortices. The pressure difference between the left and right sides of the vortex generator 16 is modulated by the flow velocity of the fluid to be measured flowing in the passages 18 and 20. Therefore, the measurement accuracy can be further improved by changing the separation distance between the first attachment portions 102 and 104 and the second attachment portions 106 and 108 according to the measured flow rate range.

Here, Modification 3 will be described.
FIG. 6 is a longitudinal sectional view for explaining the configuration of the third modification. In FIG. 6, the same parts as those in the above embodiment are denoted by the same reference numerals, and the description thereof is omitted.

  As shown in FIG. 6, in the ultrasonic vortex flow meter 110 according to the modified example 4, the end of the vortex generator 16 extends to the same position as the end face of the sensor attachment 38, and the sensor attachment 38 In this case, spaces 112 and 114 communicating with the passages 18 and 20 pass therethrough.

  A guide ring mounting portion 64 is provided on the inner walls of the spaces 112 and 114. Furthermore, seal grooves 122 and 124 for mounting a seal member (O-ring) 120 are provided at the upper ends of the spaces 112 and 114 so as to face the holding member 39. The seal member 120 is compressed when the mounting bolt 69 is tightened in a state where the holding member 39 is in contact with the upper surface of the sensor mounting portion 38, and seals between the sensor mounting portion 38 and the holding member 39. Also seal between 112 and 114.

  A guide ring 126 with which the sensor holder 72 abuts is fitted into the abutment portion 64 a of the guide ring attachment portion 64. The guide ring 126 has a concave portion 128 with which the peripheral portion of the diaphragm 72c of the sensor holder 72 abuts on the upper surface, and a plurality of notches (passages) 130 communicating between the spaces 112, 114 and the passages 18, 20 on the outer periphery. Have

7A and 7B are views showing the guide ring 126, where FIG. 7A is a plan view and FIG. 7B is a longitudinal sectional view.
As shown in FIGS. 7A and 7B, when viewed from above, the guide ring 126 has a triangular notch 130 (130 _{1 to} 130 _n-1 ) on the outer periphery and a protrusion 132 (132 that protrudes in the radial direction). _{1 to} 132 _n ) are alternately formed in a star shape. As a result, the spaces 112 and 114 are provided independently, but the pressures of the passages 18 and 20 of the vortex generator 16 are introduced through the plurality of notches 130.

  Further, the guide ring 126 guides the insertion position of the sensor holder 72 in the radial direction to the center of the spaces 112 and 114 by fitting the tips of the protrusions 132 to the inner walls 112 a and 114 a of the spaces 112 and 114.

  Since the plurality of notches 130 have a sufficient opening area, oil mist and moisture contained in the fluid can pass therethrough. Therefore, oil mist and moisture contained in the fluid do not accumulate on the surface of the guide ring 126. Moreover, since the pressure applied to the diaphragm 72c of the sensor holder 72 and the closing member 78a can be made the same, the load applied to the pipe line 78b and the pipe 80 can be reduced, and the cross-sectional area of the pipe 80 is reduced accordingly. be able to.

  Thus, since the sensor holder 72 is supported by the pipe line 78b having a smaller diameter than the cylindrical portion 72a, the difference in the pressing force between the pressure in the passages 18 and 20 and the pressure in the sensor insertion holes 38a and 38b and the space 38c. That is, it is pressed upward by the pressure acting on the area (Sa-Sb) obtained by subtracting the pressure receiving area Sb of the lid portion 78a (the area excluding the cross-sectional area of the pipe line 78b) from the pressure receiving area Sa of the pressure diaphragm 72c. become.

  Therefore, the pressing force in the direction in which the sensor holder 72 acting on the pipe line 78b is separated from the guide ring 62 is reduced, and the strength of the pipe line 78b can be reduced accordingly. For this reason, the cross-sectional area in the direction orthogonal to the axial direction of the wall thickness of the pipe line 78b can be made smaller than the cross-sectional area in the direction orthogonal to the axial direction of the wall thickness of the cylindrical portion 72a. Therefore, the ultrasonic wave leaking from the cylindrical portion 72a in the pipe line 78b can be attenuated. Therefore, sound wave leakage from the sensor holder 72 to the sensor mounting portion 38 is reduced, and a sufficient S / N ratio can be secured.

  Therefore, the vibration (leakage ultrasonic wave) from the sensor holder 72 is difficult to propagate to the vortex generator 16. Therefore, most of the vibration (leakage ultrasonic wave) from the sensor holder 72 is attenuated and does not propagate to the sensor mounting portion 38, but propagates to the reception-side ultrasonic sensors 34 and 36 via the vortex generator 16 and the flowmeter main body 14. Is prevented.

  Further, the guide ring 126 has a small contact area with the guide ring mounting portion 64 because the plurality of protrusions 132 are brought into contact with and locked with the contact portion 64a of the guide ring mounting portion 64. Therefore, the vibration from the diaphragm 72c of the sensor holder 72 is not easily propagated to the guide ring mounting portion 64, the sound wave leakage from the sensor holder 72 to the sensor mounting portion 38 is reduced, and a sufficient S / N ratio can be secured. become.

FIG. 8 is a view showing a modified example of the guide ring, where (A) is a plan view and (B) is a longitudinal sectional view.
As shown in FIGS. 8A and 8B, the guide ring 134 has a concave portion 136 with which the peripheral edge of the diaphragm 72c of the sensor holder 72 abuts on the upper surface, and the spaces 112 and 114 and the vortex on the center line. A plurality of through holes (passages) 138 (138 ₁ to 138 _n ) communicating with the passages 18 and 20 of the generator 16 are provided.

  Further, the guide ring 134 guides the insertion position of the sensor holder 72 in the radial direction to the center of the spaces 112 and 114 by fitting the outer periphery of the guide ring 134 to the inner walls 112a and 114a of the spaces 112 and 114.

  Since the plurality of through holes 138 have a sufficient opening area, oil mist and moisture contained in the fluid can pass therethrough. For this reason, oil mist and moisture contained in the fluid are not deposited on the surface of the guide ring 134.

  And since the peripheral part except the some through-hole 138 is contact | abutted and latched by the contact part 64a of the guide ring attachment part 64, the guide ring 134 is contacted with the contact part 64a of the guide ring attachment part 64 The area is small. Therefore, the vibration from the diaphragm 72c of the sensor holder 72 is not easily propagated to the guide ring mounting portion 64, the sound wave leakage from the sensor holder 72 to the sensor mounting portion 38 is reduced, and a sufficient S / N ratio can be secured. become.

FIG. 9 is a longitudinal sectional view showing another modification of the guide ring.
As shown in FIG. 9, the guide ring (annular member) 140 is attached so as to be fitted into a groove 142 formed on the outer periphery of the cylindrical portion 72 a of the sensor holder 72.

Similar to the guide ring 126, a triangular notch (passage) 130 (130 _{1 to} 130 _n-1 ) and a radially projecting protrusion 132 (132 _{1 to} 132 _n ) are formed on the outer periphery of the guide ring 140. It is formed in a star shape that is provided alternately. The guide ring 140 guides the insertion position of the sensor holder 72 in the radial direction to the center of the spaces 112 and 114 by fitting the tip ends of the protrusions 132 to the inner walls 112 a and 114 a of the spaces 112 and 114.

  Therefore, the sensor holder 72 is positioned at the insertion position in the radial direction by the guide ring 126 fitted in the groove 142, and is positioned at the axial insertion position by the length of the pipe 80 coupled to the pipe line 78b. . Therefore, there is no need to provide the guide ring mounting portion 64 in the passages 18 and 20 of the vortex generator 16, and the processing man-hour of the sensor mounting portion 38 is reduced and the processing becomes easy.

  Since the guide ring 140 having a passage through which a fluid can pass is provided on the outer periphery of the cylindrical portion 72a of the sensor holder 72, the radial attachment position of the sensor holder 72 is guided, and the upper portion of the cylinder portion is guided by the passage of the guide ring 140. The pressure difference applied to the lower portion is reduced, and the strength of the pipe can be reduced by reducing the wall thickness.

Here, Modification 4 will be described.
FIG. 10 is a longitudinal sectional view for explaining the configuration of the fourth modification. In FIG. 10, the same parts as those in the above embodiment are denoted by the same reference numerals, and the description thereof is omitted.

  As shown in FIG. 10, in the ultrasonic vortex flowmeter 148 of the third modification, the upper end 16 b of the partition wall 16 a partitioning the passages 18 and 20 extends to a position where it abuts on the upper holding member 39. The lower end 16c of the partition wall 16a extends to a position where it contacts the lower holding member 39. Therefore, the upper side of the transmission side ultrasonic sensors 30 and 32 is partitioned into spaces 112 and 114, and the lower side of the reception side ultrasonic sensors 34 and 36 is similarly partitioned into spaces 112 and 114.

  A pressure introduction path 22 communicates with the transmission side ultrasonic sensor 30 and a pressure introduction path 24 communicates with the transmission side ultrasonic sensor 32. Further, a pressure introduction path 28 communicates with the reception side ultrasonic sensor 34 and a pressure introduction path 26 communicates with the reception side ultrasonic sensor 36. The first attachment portions 102 and 104 and the second attachment portions 106 and 108 are provided with guide rings (not shown) having passages communicating with the passages 18 and 20 and the spaces 112 and 114.

  Therefore, in the ultrasonic vortex flowmeter 109, the distance between the transmission-side ultrasonic sensors 30 and 32 and the reception-side ultrasonic sensors 34 and 36 is an arbitrary distance regardless of the inner diameter (caliber) of the flow path 12. By setting the positions of the first mounting portions 102 and 104 and the second mounting portions 106 and 108 as described above, even at a low flow rate with small modulation due to Karman vortex or at a high flow rate with large modulation due to Karman vortex, S The / N ratio is stable, and it is possible to prevent the accuracy from being reduced and measurement impossible.

  Since the pressure introduction paths 22, 24, 26, and 28 that open to both sides of the vortex generator 16 are communicated with the passages 18 and 20, when a Karman vortex is generated, a pressure difference is generated on both sides of the vortex generator 16. A fluid flow is generated in the passages 18 and 20. Thereby, the ultrasonic wave propagating in the passages 18 and 20 is modulated by the flow velocity of the fluid to be measured flowing in the passages 18 and 20 due to the pressure difference between the left and right sides of the vortex generator 16 accompanying the generation of Karman vortex. Therefore, the measurement accuracy can be further improved by changing the separation distance between the first attachment portions 102 and 104 and the second attachment portions 106 and 108 according to the measured flow rate range.

Here, Modification 5 will be described.
FIG. 11 is a longitudinal sectional view for explaining the configuration of the fifth modification. FIG. 12 is a longitudinal sectional view showing a state in which the holding member 152, the transmission side ultrasonic sensors 30, 32, and the reception side ultrasonic sensors 34, 36 are unitized. Figure 13 is the receiving side of the connection terminals 156a, 158a, sender of the connection terminals 160a, is a perspective view showing a state where the lead wire ₈₂ 1-82 ₄ is connected to a 160 b. In FIG. 11 to FIG. 13, the same parts as those in the above embodiment are designated by the same reference numerals and the description thereof is omitted.

As shown in FIGS. 11 to 13, in the ultrasonic vortex flowmeter 150 of the fourth modification, a plurality of substrates 154 in which the drive circuit 42 and the calculation unit 46 (see FIG. 1) are arranged inside the holding member 152. A substrate storage chamber 152a in which (154 _{1 to} 154 _n ) is stored is provided. The first substrate 154 ₁ disposed in the lower of the plurality of substrates 154, the receiving side than the transmitting-side connecting portion 160 of the receiving side connecting portion 156 and the driving circuit 42 of the arithmetic unit 46 as will be described later The ultrasonic sensors 34 and 36 and the transmission-side ultrasonic sensors 30 and 32 are provided in a line so as to face each other.

Lead wires 82 ₁ and 82 ₂ , which are electric wires on the reception side, are connected to the connection terminals 156 a and 158 a of the pair of reception side connection portions 156 and 158, and the pair of connection terminals 160 a and 160 b of the transmission side connection portion 160 are connected to the connection terminals 156 a and 158 a. , leads ₈₂ 3, 82 ₄ are connected to a wire receiving end.

Accordingly, the transmission side ultrasonic sensors 30, 32, and the receiving-side lead wire drawn out from the ultrasonic sensor 34, 36 ₈₂ 1-82 ₄ prevents the entanglement, and a pair of receiving side connection terminals 156 and 158 the sender because provided at a position spaced so as to sandwich the both sides of the connection terminals 160, the receiving side of the lead wire ₈₂ 1, 82 ₂ leads ₈₂ 1 by the spaced, 82 ₂ and between the receiving side of the connection terminal 156a, between 158a Crosstalk can be prevented.

  The upper opening of the holding member 152 is closed by a lid member 162 fastened to the mounting bolt 161, and the reception amplification circuits 48 and 50, the waveform shaping circuits 52 and 54, the phase comparison circuit 56, and the like provided on the substrate 154, The flow rate calculation unit 60 is protected by the lid member 162. Further, the holding member 152 is sealed between the mounting surface 166a of the main body 166 by the seal member 164 by fastening of the mounting bolt 163, and the bottomed cylindrical portion 152b is inserted into the mounting hole 166b of the main body 166.

The four pipe lines 168 to 171 that support the transmission-side ultrasonic sensors 30 and 32 and the reception-side ultrasonic sensors 34 and 36 are fixed to the bottom 152c of the bottomed cylindrical portion 152b so as to extend downward. Has been. Conduit 168-171 has an upper end is coupled to the arranged transmitting side connecting portion 156 and 158 provided on the substrate 154 ₁ and opposite to the receiving side connecting portion 160 located at the bottom. The end of the lead wire ₈₂ 1-82 ₄ inserted through the conduit 168 to 171, the receiving side of the connection terminals 156a, 158a, sender of the connection terminal 160a, is connected by soldering or the like to 160 b.

  Therefore, in the ultrasonic vortex flowmeter 150, the holding member 152, the reception-side ultrasonic sensors 34 and 36, and the transmission-side ultrasonic sensors 30 and 32 are unitized via the pipe lines 168 to 171. Therefore, the receiving-side ultrasonic sensors 34 and 36 and the transmitting-side ultrasonic sensors 30 and 32 can be taken out together with the holding member 152 only by loosening the mounting bolt 163, so that the taking-out operation at the time of maintenance can be easily performed.

  In addition, since the reception-side ultrasonic sensors 34 and 36 and the transmission-side ultrasonic sensors 30 and 32 can be inserted together when inserted into the passages 18 and 20 of the vortex generator 16, they can be attached in a short time. Become. Further, the separation distance between the reception-side ultrasonic sensors 34 and 36 and the transmission-side ultrasonic sensors 30 and 32, that is, the distance between the diaphragms 72 c facing each other in the passages 18 and 20 is the length of the pipes 168 to 171. Thus, the reception sensitivity of the reception-side ultrasonic sensors 34 and 36 can be stabilized.

  Since the pipes 168 to 171 have a smaller diameter than the cylindrical portion 72a of the sensor holder 72, the rigidity is higher than that of the cylindrical portion 72a of the sensor holder 72, so that vibration (leakage ultrasonic waves) is less likely to propagate. ing. That is, ultrasonic waves leaking from the sensor holder 72 in the pipe lines 168 to 171 can be attenuated. Therefore, sound wave leakage from the sensor holder 72 to the holding member 152 is reduced, and a sufficient S / N ratio can be secured.

  The lower ends of the pipes 168 and 169 are fixed to the sensor holder 72 of the transmission side ultrasonic sensors 30 and 32. The lower ends of the receiving side pipes 168 and 169 are fixed to the lid member 78 of the sensor holder 72 of the receiving side ultrasonic sensors 34 and 36. A piezoelectric element 70 is housed in the interior 72 b of each sensor holder 72 of the transmission-side ultrasonic sensors 30 and 32 and the reception-side ultrasonic sensors 34 and 36.

  A guide ring 172 is fitted and fixed to the outer periphery of the cylindrical portion 72 a of the sensor holder 72. The guide ring (annular member) 172 is provided with a plurality of through-holes 174 in the passage extending direction for allowing fluid to pass therethrough like the guide ring 134 shown in FIG. 8 described above. The lower ends of the pipes 170 and 171 on the reception side are inserted into the through holes 174 and are coupled to the outer periphery of the cylindrical portion 72 a of the sensor holder 72.

  The guide ring 172 is formed of, for example, a sintered material in which open cell holes are formed by mixing resin particles and metal, and guides the insertion position of the sensor holder 72 in the passages 18 and 20 of the vortex generator 16. In addition, it also has a function of absorbing ultrasonic waves traveling in an oblique direction with respect to the fluid flow direction to prevent leakage of ultrasonic waves.

  Further, a sound absorbing material 176 formed in a cylindrical shape is fixed to the end face of each guide ring 172. The sound absorbing material 176 has a hole (not shown) for allowing fluid to pass in the same manner as the guide ring 172. For example, the sound absorbing material 176 is formed of an elastic material having a large number of holes such as a sponge. , Has the function of preventing the propagation of sound waves. In addition, the sound absorbing material 176 is provided with a hole 176a for inserting the pipes 170 and 171 on the receiving side in the passage extending direction.

Inside the Kakukanro 168-171, leads ₈₂ 1-82 ₄ and is inserted, and the outer periphery of the Kakukanro 168-171, wave propagation preventing portion 178 is formed. The sound wave propagation preventing unit 178 is made of a groove for preventing sound wave propagation, a sponge for absorbing sound waves, a porous sintered metal, or the like.

  Further, among the pipes 168 to 171, the pipes 170 and 171 on the receiving side are inserted into the passages 18 and 20 of the vortex generator 16, so that the sound wave propagation prevention unit 178 of the pipes 170 and 171 has the passage 18. , 20 also prevents irregular reflection of sound waves propagating in the interior.

Here, the operation at the time of flow rate measurement will be described.
When the fluid to be measured flows through the flow path 12 in the flow meter main body 14, a Karman vortex (see FIG. 2) is generated downstream of the vortex generator 16. Since the vortex generator 16 is provided with the pressure introduction paths 22, 24, 26, and 28 as described above, when the Karman vortex is generated in the fluid to be measured flowing downstream of the vortex generator 16, the Karman vortex is generated. Due to the pressure change caused by the generation of the vortex generator 16, a pressure difference is generated on both the left and right sides of the vortex generator 16, and the fluid to be measured 180, 182 is generated in the passages 18, 20 due to this pressure difference. That is, in the passages 18 and 20, a reverse flow alternately occurs at the same cycle as the generation of the Karman vortex.

  Further, the ultrasonic waves transmitted from the transmission side ultrasonic sensors 30 and 32 propagate through the fluid to be measured flowing in the passages 18 and 20 and are received by the reception side ultrasonic sensors 34 and 36. At this time, of the ultrasonic waves transmitted from the transmission-side ultrasonic sensors 30 and 32, the ultrasonic waves transmitted obliquely toward the inner walls of the passages 18 and 20 are absorbed by the sound absorbing material 176 and received by the reception-side ultrasonic sensor 34, It is prevented from reaching 36 and the generation of noise due to diffuse reflection is suppressed.

  Further, since the sound wave propagation preventing portion 178 is formed on the outer periphery of each of the pipes 168 to 171, the ultrasonic waves propagating in the fluid in the passages 18 and 20 are reflected on the pipes 170 and 171 on the receiving side. The generation of noise due to reflected waves is suppressed.

  In the vortex generator 16, the pressure introduction paths 22 and 24 are provided above the transmission side ultrasonic sensors 30 and 32, and the pressure introduction paths 26 and 28 are provided below the reception side ultrasonic sensors 34 and 36. It has been.

  Then, due to the pressure difference between the two sides of the vortex generator 16 generated by the Karman vortex 184, the fluid that has flowed into the left passage 18 from the pressure introduction passage 22 is fitted to the outer periphery of the transmission-side ultrasonic sensor 30. And flow 180 in the same direction as the transmission direction through the sound absorbing material 176. Further, the fluid passes through the guide ring 172 and the sound absorbing material 176 fitted to the outer periphery of the reception-side ultrasonic sensor 34 and flows out to the pressure introduction path 28.

  Further, the fluid flowing into the right passage 20 from the pressure introduction passage 26 passes through the guide ring 172 and the sound absorbing material 176 fitted to the outer periphery of the reception-side ultrasonic sensor 36, and generates a flow 182 in the reverse direction. Further, the fluid passes through the guide ring 172 and the sound absorbing material 176 fitted to the outer periphery of the transmission side ultrasonic sensor 32 and flows out to the pressure introduction path 24.

  Accordingly, any one of the ultrasonic waves propagating in the passages 18 and 20 is accelerated by the flow velocity of the fluid to be measured flowing in the passages 18 and 20 due to the generation of the Karman vortex and propagates in the passages 18 and 20. The other ultrasonic wave is decelerated by the flow velocity of the fluid to be measured flowing in the passages 18 and 20 accompanying the generation of the Karman vortex.

  Therefore, the calculation unit 46 demodulates the signal obtained from the phase difference between the detection signals output from the reception-side ultrasonic sensors 34 and 36 to detect the Karman vortex generation frequency, and based on this frequency, the calculation unit 46 Measure the flow rate of the fluid to be measured flowing through.

  Here, an assembling operation of the ultrasonic vortex flowmeter 150 of the above-described modification 4 will be described with reference to FIGS. 12 and 13.

As shown in FIGS. 12 and 13, in the ultrasonic vortex flowmeter 150, the holding member 152 storing the substrate 154 (154 _{1 to} 154 _n ), the transmission-side ultrasonic sensors 30 and 32, and the reception side Since the ultrasonic sensors 34 and 36 are unitized, the transmission-side ultrasonic sensors 30 and 32 and the reception-side ultrasonic sensors 34 and 36 can be collectively inserted into the passages 18 and 20 of the vortex generator 16. Is possible.

  Furthermore, at the time of maintenance, the transmission-side ultrasonic sensors 30 and 32 and the reception-side ultrasonic sensors 34 and 36 can be taken out simultaneously by pulling the holding member 152 upward simply by loosening the mounting bolt 163. Therefore, it is possible to reduce the time for taking out the maintenance work and to easily take out the work.

Further, the conduit 168 to 171 is a connection terminal on the receiving side is provided on the first substrate 154 ₁ 156a, 158a, sender of the connection terminals 160a, since provided on the counter located 160 b, conduit 168 to 171 four lead wires 82 ₁ to 82 ₄ drawn from, are arranged in parallel with each other, since no entangled, can prevent the lead wire 82 _{1-82 4} crosstalk each other, wraparound substrate Is reduced.

  In the above embodiment, a configuration in which the pair of transmission-side ultrasonic sensors 30 and 32 and the reception-side ultrasonic sensors 34 and 36 are disposed at positions facing the passages 18 and 20 of the vortex generator 16 is given as an example position. However, the present invention is not limited to this, and it is a matter of course that any one of the transmission-side ultrasonic sensor and the reception-side ultrasonic sensor may be configured to detect the Karman vortex from the phase difference between the transmission signal and the reception signal. .

  Needless to say, the fluid to be measured may be liquid or gas.

It is a block diagram which shows one Example of the ultrasonic sensor and ultrasonic flow measuring device which become this invention. It is a cross-sectional view of an embodiment of an ultrasonic flow measuring device according to the present invention. It is a longitudinal cross-sectional view which expands and shows the attachment structure of the sensor attachment part 38 and the holding member 39. FIG. It is a longitudinal cross-sectional view which expands and shows the principal part of the modification 1. 10 is a longitudinal sectional view for explaining a configuration of modification example 2. FIG. 10 is a longitudinal sectional view for explaining a configuration of modification example 3. FIG. It is a figure which shows the guide ring 126, (A) is a top view, (B) is a longitudinal cross-sectional view. It is a figure which shows the modification of a guide ring, (A) is a top view, (B) is a longitudinal cross-sectional view. It is a longitudinal cross-sectional view which shows another modification of a guide ring. 10 is a longitudinal sectional view for explaining a configuration of modification example 4. FIG. FIG. 10 is a vertical cross-sectional view for explaining the configuration of Modification 5. It is a longitudinal cross-sectional view which shows the state in which the holding member 152, the transmission side ultrasonic sensors 30 and 32, and the reception side ultrasonic sensors 34 and 36 were unitized. Reception of the connection terminals 156a, 158a, sender of the connection terminals 160a, is a perspective view showing a state where the lead wire ₈₂ 1-82 ₄ is connected to a 160 b.

Explanation of symbols

10, 90, 100, 110, 149, 150 Ultrasonic vortex flow meter 12 Flow path 14 Flow meter body 16 Vortex generator 18, 20 Passage 22, 24, 26, 28 Pressure introduction path 30, 32 Transmission side ultrasonic sensor 34, 36 Receiving-side ultrasonic sensors 38, 40 Sensor mounting portions 38a, 38b Sensor insertion holes 38c Space 39, 41 Holding member 39a Hollow portion 39b Through hole 39c Hollow portion 42 Drive circuit 44 Oscillation circuit 46 Calculation portion 48, 50 Reception amplification Circuits 52, 54 Waveform shaping circuit 56 Phase comparison circuit 60 Flow rate calculation units 62, 126, 134, 140, 172 Guide ring 64 Guide ring mounting portions 66, 94 Seal member 70 Piezoelectric element 72 Sensor holder 72a Cylindrical portion 72b Internal 72c Diaphragm 72d Corner portion 74 Clearance 78 Lid member 78a Lid portion 78b Hollow portion 80, 92 Pipe 82 Lead Line 96 biasing members 102 first mounting portion 106 second mounting portion 112, 114 space _{130 (130 1 ~130 n-1} ) notch ₁₃₂ (132 1 to 132 _n) projections 138 (138 ₁ to 138 _n) through holes 152 holding member _{154 (154} 1 _{~154 n)} substrate 156, 158 receiving side connecting portion 156a, 158a, 160a, 160b connecting terminals 160 transmitting side connecting portion 168 to 171 conduits 176 sound-absorbing material 178 wave propagation Prevention part

Claims (10)

A piezoelectric element that vibrates when a voltage is applied;
A sensor holder that houses the piezoelectric element;
In an ultrasonic sensor having
The sensor holder is
Storage for storing the piezoelectric element from a diaphragm that contacts the piezoelectric element, a cylindrical portion that is continuously formed on the diaphragm and covers the outer periphery of the piezoelectric element, and a closing member that closes the opening of the cylindrical portion A piezoelectric element housing portion in which a space is formed;
An internal space having a space portion penetrating in the axial direction so that an electric wire for applying a voltage to the piezoelectric element is inserted therein, one end of which is coupled to a closing member of the piezoelectric element housing portion;
Consists of
The ultrasonic sensor according to claim 1, wherein a cross-sectional area in a direction orthogonal to the axial direction of the thickness of the pipe line is set to be smaller than a cross-sectional area in a direction orthogonal to the axial direction of the thickness of the cylindrical portion. A flow meter body in which a flow path for the fluid to be measured is formed;
An ultrasonic transmitter for transmitting ultrasonic waves;
An ultrasonic receiver for receiving the ultrasonic wave transmitted from the ultrasonic transmitter;
A holding member for fixing and holding the ultrasonic transmitter and the ultrasonic receiver to the flowmeter body;
In an ultrasonic flow measurement device for measuring the flow rate of the fluid to be measured flowing through the flow path based on the reception signal received by the ultrasonic receiver,
At least one of the ultrasonic transmitter and the ultrasonic receiver is:
A piezoelectric element that vibrates when a voltage is applied;
A sensor holder that houses the piezoelectric element;
An ultrasonic sensor having
The sensor holder is
Storage for storing the piezoelectric element from a diaphragm that contacts the piezoelectric element, a cylindrical portion that is continuously formed on the diaphragm and covers the outer periphery of the piezoelectric element, and a closing member that closes the opening of the cylindrical portion A piezoelectric element housing portion in which a space is formed;
An internal space having a space portion penetrating in the axial direction for insertion of an electric wire for applying a voltage to the piezoelectric element, and one end of which is coupled to a closing member of the piezoelectric element housing portion;
Consists of
An ultrasonic flow rate characterized in that a cross-sectional area in a direction perpendicular to the axial direction of the wall thickness of the pipe is set smaller than a cross-sectional area in a direction orthogonal to the axial direction of the wall thickness of the cylindrical portion. measuring device. The ultrasonic sensor is provided so as to be relatively displaceable with respect to the holding member, is provided with an urging member that urges the ultrasonic sensor in a separating direction with respect to the holding member, and is provided in the flow path. A vortex generator perpendicular to the flow direction is provided,
The vortex generator has a passage communicating with the flow path of the flowmeter main body, and the ultrasonic wave receiver is in contact with the first mounting portion where the ultrasonic transmitter abuts in the middle of the passage. The ultrasonic flow rate measuring apparatus according to claim 2, further comprising a second attachment portion that contacts the ultrasonic wave.   An annular member having a passage through which a fluid can pass is provided in the contact portion of the ultrasonic transmitter of the first attachment portion and the contact portion of the ultrasonic receiver of the second attachment portion. The ultrasonic flow rate measuring device according to claim 3.   4. The ultrasonic flow measuring device according to claim 3, wherein an annular member having a passage through which a fluid can pass is provided on the outer circumference of the cylindrical portion of the ultrasonic transmitter and the ultrasonic receiver. The ultrasonic flow measuring device according to claim 2,
An electric wire from a piezoelectric element housed in the sensor holder of the ultrasonic transmitter and ultrasonic receiver is inserted into the conduit and connected to a substrate housed in the holding member;
An ultrasonic flow rate measuring apparatus, wherein the pipe line is integrally coupled to the sensor holder.   The sound absorbing material which absorbs an ultrasonic wave is provided between the inner periphery of the ultrasonic propagation path in which the said ultrasonic transmitter and an ultrasonic receiver are inserted, and the outer periphery of the said sensor holder, It is characterized by the above-mentioned. Ultrasonic flow measuring device.   The ultrasonic flow measuring device according to claim 6, wherein a sound absorbing material that absorbs ultrasonic waves is provided on an outer periphery of the conduit.   The ultrasonic flow rate measuring apparatus according to claim 7, wherein the sound absorbing material guides a position of the sensor holder with respect to an inner periphery of the ultrasonic propagation path. The ultrasonic flow measuring device according to claim 2,
A pair of the ultrasonic transmitters is provided,
A pair of the ultrasonic receivers are provided,
A substrate is provided on the holding member;
The substrate is
A drive circuit having a pair of connection terminals to which the pair of ultrasonic transmitters are connected;
A receiving circuit having a pair of connection terminals to which the pair of ultrasonic receivers are connected;
An ultrasonic flow rate measuring apparatus, wherein the pair of connection terminals of the receiving circuit are provided at positions separated from both sides of the pair of connection terminals of the drive circuit.

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