Clamp-on Ultrasonic Flow Sensor

Abstract

A clamp-on ultrasonic flow sensor capable of calculating the flow rate of a fluid flowing in a small-diameter metal pipe is provided. An elastic coupling medium is supported on the pipe by a clamping member in such a manner that a pipe contact portion contacts the pipe and is arranged along the axial direction. The elastic coupling medium propagates ultrasonic waves emitted from an ultrasonic element to the pipe. The pipe contact portion is surrounded by a damping material between the clamping member and the pipe. The elastic coupling medium is supported on the pipe by a clamping member in such a manner that a pipe contact portion contacts the pipe and is arranged along the axial direction. The elastic coupling medium propagates ultrasonic waves emitted from an ultrasonic element to the pipe. The pipe contact portion is surrounded by a damping material between the clamping member and the pipe. In a state where the clamping members respectively pressurize the damping material, the clamping members are coupled to each other to clamp the pipe.

Description

Technical Field

[0001] The present invention relates to a clamp-on type ultrasonic flow sensor for calculating the flow rate of a fluid flowing in a pipe. Background Art

[0002] A clamp-on ultrasonic flow sensor is known that can calculate the flow rate of a fluid flowing in a pipe in a state where the clamp-on ultrasonic flow sensor is mounted to the pipe via a clamping member (for example, see Japanese Patent Application Laid-Open No. 2016-217733 (Patent Document 1)).

[0003] The clamp-on ultrasonic flow sensor (ultrasonic flow switch) of Patent Document 1 includes a pair of ultrasonic elements that transmit and receive ultrasonic waves. Ultrasonic waves are transmitted to a fluid flowing in a pipe by one ultrasonic element. The ultrasonic waves that pass through the fluid are received by the other ultrasonic element. The flow rate of the fluid is calculated based on the ultrasonic waves transmitted and received by the pair of ultrasonic elements. Summary of the invention

[0004] Problem that the invention aims to solve

[0005] In a clamp-on ultrasonic flow sensor, there is a component in the ultrasonic wave that reaches another ultrasonic wave element from one ultrasonic wave element, which propagates in the peripheral wall of the tube and does not pass through the fluid. This component is an unnecessary component that does not have information about the flow rate of the fluid. When the unnecessary component of the ultrasonic wave is large, it is difficult to accurately calculate the flow rate of the fluid. Therefore, it is necessary to separate the component of the ultrasonic wave that passes through the fluid from the unnecessary component and receive the component of the ultrasonic wave.

[0006] When the diameter of the pipe is large, a pair of ultrasonic elements can be arranged to be separated from each other. The propagation speed of ultrasonic waves in a resin material is lower than the propagation speed of ultrasonic waves in a metal material. In addition, the attenuation rate of ultrasonic waves in a resin material is greater than the attenuation rate of ultrasonic waves in a metal material. Therefore, when the diameter of the pipe is large or the pipe is formed of a resin material, a pair of ultrasonic elements can be easily arranged in such a manner that the component of ultrasonic waves passing through the fluid is temporarily or spatially separated from unnecessary components and received.

[0007] However, when the diameter of the pipe is small and the pipe is formed of a metal material, it is not easy to arrange a pair of ultrasonic elements in such a way that the components of ultrasonic waves that pass through the fluid are separated from unnecessary components and received. Therefore, the flow rate of the fluid flowing in the metal pipe with a small diameter cannot be calculated.

[0008] An object of the present invention is to provide a clamp-on type ultrasonic flow sensor capable of calculating the flow rate of a fluid flowing in a metal pipe having a small diameter.

[0009] Solutions for solving problems

[0010] (1) A clamp-on ultrasonic flow sensor according to the present invention is: a clamp-on ultrasonic flow sensor that measures the flow rate of a fluid flowing in a pipe, the clamp-on ultrasonic flow sensor comprising: a first ultrasonic element configured to transmit and receive ultrasonic waves; a first wedge-shaped material configured to propagate ultrasonic waves transmitted from the first ultrasonic element and comprising a first incident / emitting surface that is inclined relative to a propagation direction of the ultrasonic waves and transmits the propagated ultrasonic waves; a first elastic coupling medium that comprises a first pipe contact portion that contacts the pipe and is configured to cause the ultrasonic waves emitted from the first incident / emitting surface of the first wedge-shaped material to propagate to the pipe via the first pipe contact portion; a first clamping member configured to support the pipe and support the first elastic coupling medium, and to arrange the first pipe contact portion along the axial direction of the pipe; a first damping material that is arranged to attenuate ultrasonic waves and surrounds the first pipe contact portion of the first elastic coupling medium between the first clamping member and the pipe; a second ultrasonic element configured to attenuate ultrasonic waves and surround the first pipe contact portion of the first elastic coupling medium between the first clamping member and the pipe; a second wedge-shaped material configured to propagate the ultrasonic wave transmitted from the second ultrasonic element and including a second incident / transmitting surface inclined with respect to the propagation direction of the ultrasonic wave and transmitting the propagated ultrasonic wave; a second elastic coupling medium including a second tube contact portion in contact with the tube and configured to propagate the ultrasonic wave transmitted from the second incident / transmitting surface of the second wedge-shaped material to the tube via the second tube contact portion; a second clamping member configured to support the tube and support the second elastic coupling medium, and to arrange the second tube contact portion along the axial direction; a second damping material arranged to attenuate the ultrasonic wave and to surround the second tube contact portion of the second elastic coupling medium between the second clamping member and the tube; and a flow rate calculation portion configured to calculate the flow rate of the fluid flowing in the tube based on the ultrasonic wave transmitted and received between the first ultrasonic element and the second ultrasonic element. In a state where the first clamping member presses the first damping material and the second clamping member presses the second damping material, the first clamping member and the second clamping member are connected to each other to clamp the tube.

[0011] In the clamp-on ultrasonic flow sensor, ultrasonic waves are transmitted and received between the first ultrasonic element and the second ultrasonic element through the tube. The ultrasonic wave transmitted from the first ultrasonic element propagates through the first wedge material and is emitted from the first incident / emission surface inclined relative to the propagation direction of the ultrasonic wave. The first elastic coupling medium is supported on the tube by the first clamping member in such a manner that the first tube contact portion contacts the tube and is arranged along the axial direction. The first elastic coupling medium causes the ultrasonic wave emitted from the first incident / emission surface of the first wedge material to propagate to the tube via the first tube contact portion. The first damping material is arranged to attenuate the ultrasonic wave and surrounds the first tube contact portion of the first elastic coupling medium between the first clamping member and the tube.

[0012] The ultrasonic wave transmitted from the second ultrasonic element propagates through the second wedge material and is emitted from the second incident / emission surface inclined with respect to the propagation direction of the ultrasonic wave. The second elastic coupling medium is supported on the tube by the second clamping member in such a manner that the second tube contact portion contacts the tube and is arranged along the axial direction. The second elastic coupling medium propagates the ultrasonic wave emitted from the second incident / emission surface of the second wedge material to the tube via the second tube contact portion. The second damping material is arranged to attenuate the ultrasonic wave and surround the second tube contact portion of the second elastic coupling medium between the second clamping member and the tube. In a state where the first damping material is pressed by the first clamping member and the second damping material is pressed by the second clamping member, the first clamping member and the second clamping member are connected to each other to clamp the tube.

[0013] With the above configuration, ultrasonic waves are excited in the peripheral wall of the pipe by vibration. The excited ultrasonic waves can be used to transmit and receive the ultrasonic waves through the pipe between the first ultrasonic element and the second ultrasonic element. In this case, unnecessary components of the ultrasonic waves that propagate in the peripheral wall of the pipe and do not pass through the fluid and are transmitted and received between the first ultrasonic element and the second ultrasonic element are reduced. Therefore, it is easy to calculate the flow rate of the fluid flowing in the pipe based on the ultrasonic waves transmitted and received between the first ultrasonic element and the second ultrasonic element.

[0014] In a state where the first damping material surrounds the first tube contact portion, the first damping material is pressed against the tube. In a state where the second damping material surrounds the second tube contact portion, the second damping material is pressed against the tube. Therefore, vibration of a portion of the tube other than the contact portion of the first tube contact portion and the second tube contact portion is prevented. The component of the ultrasonic wave that propagates in the circumferential direction in the peripheral wall of the tube is attenuated by the first damping material and the second damping material. As a result, unnecessary components of the ultrasonic wave that propagate in the peripheral wall of the tube and do not pass through the fluid and are transmitted and received between the first ultrasonic element and the second ultrasonic element are further reduced.

[0015] The first damping material and the second damping material prevent the ultrasonic wave propagating in the axial direction in the peripheral wall of the pipe from being reflected at the end surface in the axial direction of the peripheral wall and returning. Therefore, the returning ultrasonic wave does not excite the ultrasonic wave at an unnecessary time. As a result, the flow rate of the fluid flowing in the metal pipe with a small diameter can be calculated.

[0016] (2) The clamp-on ultrasonic flow sensor may further include: a first pressurizing member mounted on the first clamping member and configured to press the first damping material against the tube; and a second pressurizing member mounted on the second clamping member and configured to press the second damping material against the tube. In this case, the first damping material and the second damping material are sufficiently pressed against the tube, whereby the ultrasonic wave propagating in the peripheral wall of the tube is sufficiently attenuated. As a result, the flow rate of the fluid can be calculated more accurately.

[0017] (3) The first pressurizing member may be a first thin leaf spring whose two ends in the circumferential direction are arc-shaped cantilevers relative to the fixed part installed to the first clamping member, and the first pressurizing member can also cause the first damping material to press against the tube in a direction different from the clamping direction of the first clamping member and the second clamping member, and the second pressurizing member may be a second thin leaf spring whose two ends in the circumferential direction are arc-shaped cantilevers relative to the fixed part installed to the second clamping member, and the second pressurizing member can also cause the second damping material to press against the tube in a direction different from the clamping direction of the first clamping member and the second clamping member.

[0018] In this case, simply by clamping the pipe between the first clamping member and the second clamping member, the first damping material and the second damping material are pressed against the pipe in a direction different from the clamping direction of the first clamping member and the second clamping member by the first thin leaf spring and the second thin leaf spring. As a result, unnecessary components of ultrasonic waves propagating in the peripheral wall of the pipe can be sufficiently attenuated.

[0019] (4) The first thin leaf spring may have a semi-cylindrical shape and may be arranged to surround the entire circumference of the tube and pressurize the first damping material, and the second thin leaf spring may have a semi-cylindrical shape and may be arranged to surround the entire circumference of the tube and pressurize the second damping material. In this case, the first damping material and the second damping material are pressed against the tube also over the entire circumference of the tube in a direction different from the clamping direction of the first clamping member and the second clamping member by the first thin leaf spring and the second thin leaf spring. As a result, unnecessary components of ultrasonic waves propagating in the peripheral wall of the tube can be more fully attenuated.

[0020] (5) A space for allowing the first damping material and the second damping material to deform may be formed between the first clamping member and the tube and between the second clamping member and the tube. With this configuration, even when there is an error or fluctuation in the outer diameter of the tube, the first damping material is deformed, thereby enabling the first damping material to be pressed against the tube more reliably by the first clamping member. Similarly, the second damping material is also deformed, thereby enabling the second damping material to be pressed against the tube more reliably by the second clamping member.

[0021] (6) The first damping material and the second damping material may be formed of an elastic body. With this configuration, even when there is an error or fluctuation in the outer diameter of the tube, the first damping material is deformed, thereby enabling the first damping material to be pressed against the tube more reliably by the first clamping member. Similarly, the second damping material is also deformed, thereby enabling the second damping material to be pressed against the tube more reliably by the second clamping member.

[0022] (7) The first pressurizing member may be configured to maintain the position and posture of the first elastic coupling medium, and the second pressurizing member may be configured to maintain the position and posture of the second elastic coupling medium. With this configuration, even when the first tube contact portion and the second tube contact portion are pressed against the tube, changes in the width of the first tube contact portion and the second tube contact portion are restricted. Bending, meandering, and deformation of the first tube contact portion and the second tube contact portion are prevented. As a result, the flow rate of a fluid flowing in a metal tube having a small diameter can be accurately calculated.

[0023] (8) The first pressurizing member may include a third slit extending along the axial direction, the first tube contact portion of the first elastic coupling medium being fitted into the third slit, and the second pressurizing member may include a fourth slit extending along the axial direction, the second tube contact portion of the second elastic coupling medium being fitted into the fourth slit. In this case, the first damping material can be easily pressed against the tube by the first pressurizing member while the first tube contact portion is in contact with the tube. Similarly, the second damping material can be easily pressed against the tube by the second pressurizing member while the second tube contact portion is in contact with the tube.

[0024] (9) At least one of the first clamping member and the second clamping member may include a guide wall that guides the clamping member to the pipe when the clamping member supports the pipe. In this case, the pipe can be easily supported by the first clamping member or the second clamping member.

[0025] (10) The peripheral wall of the tube may include a first excitation region and a second excitation region, a longitudinal wave of the ultrasonic wave emitted from the first incident / emission surface of the first wedge-shaped material collides with the first excitation region, and a longitudinal wave of the ultrasonic wave emitted from the second incident / emission surface of the second wedge-shaped material collides with the second excitation region, the first excitation region of the tube may excite the ultrasonic wave that passes through the fluid flowing in the tube and travels to the second ultrasonic element, and the second excitation region of the tube may excite the ultrasonic wave that passes through the fluid flowing in the tube and travels to the first ultrasonic element. In this case, the flow rate of the fluid flowing in the tube can be calculated based on the ultrasonic waves generated from the first excitation region and the second excitation region of the tube.

[0026] (11) The first damping material may be mounted to the tube and surround the first excitation region, and the second damping material may be mounted to the tube and surround the second excitation region. In this case, vibration of portions of the tube other than the first excitation region and the second excitation region is further prevented. The components of the ultrasonic wave propagating in the circumferential direction and the axial direction in the peripheral wall of the tube are further attenuated by the first damping material and the second damping material. As a result, the flow rate of the fluid flowing in the metal tube having a small diameter can be calculated more accurately.

[0027] (12) The first wedge-shaped material may be configured so that the incident angle of the shear wave of the ultrasonic wave transmitted from the first ultrasonic element with respect to the axial direction is set to be greater than or equal to a critical angle, and the second wedge-shaped material may be configured so that the incident angle of the shear wave of the ultrasonic wave transmitted from the second ultrasonic element with respect to the axial direction is set to be greater than or equal to the critical angle.

[0028] In this case, the ultrasonic waves emitted from the first tube contact portion and the second tube contact portion are all reflected by the tube and are difficult to intrude into the peripheral wall of the tube. As a result, it is possible to further reduce unnecessary components of the ultrasonic waves that propagate through the peripheral wall of the tube and do not pass through the fluid and are transmitted and received between the first ultrasonic element and the second ultrasonic element.

[0029] (13) The outer diameter of the tube may be equal to or larger than 2 mm and equal to or smaller than 20 mm. With this structure, even when the outer diameter of the metal tube is sufficiently small, the flow rate of the fluid can be calculated.

[0030] Effects of the Invention

[0031] According to the present invention, it is possible to calculate the flow rate of a fluid flowing in a metal pipe having a small diameter. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 is a perspective view of the appearance of a flow sensor according to an embodiment of the present invention;

[0033] Figure 2 It is shown Figure 1 A cross-sectional view of the internal structure of the head shown;

[0034] Figure 3 It is used to illustrate Figure 1 A diagram showing a method for calculating flow rate in a flow sensor;

[0035] Figure 4 is a schematic cross-sectional view showing details of the sensor head;

[0036] Figure 5 yes Figure 4 A cross-sectional view of the sensor head along line AA shown;

[0037] Figure 6 is a schematic cross-sectional view showing the internal structure of the head in a modified example;

[0038] Figure 7 is a diagram for explaining the process of attaching the head to the pipe;

[0039] Figure 8 is a diagram for explaining the process of attaching the head to the pipe;

[0040] Fig. 9 is a schematic cross-sectional view showing the interior of the clamping member in a state where no pipe is installed;

[0041] Fig.10 is a schematic cross-sectional view showing the interior of the clamping member in a state where a pipe is mounted;

[0042] Fig.11 is a schematic cross-sectional view showing the interior of the clamping member in a state where a pipe is mounted; and

[0043] Fig.12 It is shown Figure 1 The block diagram shows the internal structure of the relay unit and the main body unit. DETAILED DESCRIPTION

[0044] (1) Schematic structure of clamp-on ultrasonic flow sensor

[0045] A clamp-on ultrasonic flow sensor (hereinafter referred to as flow sensor) according to an embodiment of the present invention is described with reference to the accompanying drawings. In the following description, the direction along the central axis of the tube is referred to as the axial direction. The direction along the peripheral wall of the tube is referred to as the circumferential direction. The direction inclined at a predetermined angle relative to the axial direction is referred to as the inclined direction. The direction orthogonal to the axial direction and the inclined direction is referred to as the width direction. The direction orthogonal to the inclined direction and the width direction is referred to as the length direction.

[0046] Figure 1FIG. 2 is a perspective view of the appearance of a flow sensor according to an embodiment of the present invention. Figure 1 As shown, the flow sensor 1 according to this embodiment is composed of a head 100, a relay part 200 and a main body 300. The head 100 includes two sensor heads 110 and 120 and two clamping members 130 and 140. The head 100 also includes two mounting metal sheets 150 and 160 for mounting a part of the sensor heads 110 and 120 to the clamping members 130 and 140. The clamping members 130 and 140 are formed of, for example, a metal material.

[0047] The sensor heads 110 and 120 are mounted to the outer peripheral surface of the peripheral wall of the pipe P while being held by the clamping members 130 and 140, respectively. In this embodiment, the pipe P is a metal pipe having a relatively small diameter. The diameter (outer diameter) of the pipe P is, for example, 2 mm or more and 20 mm or less. A fluid flows in the pipe P.

[0048] The head cable CA1 is connected between the sensor head 110 and the relay unit 200. The head cable CA2 is connected between the sensor head 120 and the relay unit 200. The relay cable CA3 is connected between the relay unit 200 and the main unit 300. One end of the main unit cable CA4 is also connected to the main unit 300. The other end of the main unit cable CA4 is connected to an external device (in the case of the flow sensor 1) Figure 1 The external device is, for example, a personal computer or a programmable logic controller. The details of the relay unit 200 and the main unit 300 are described below.

[0049] Figure 2 It is shown Figure 1 The cross-sectional view of the internal structure of the head 100 is shown. Figure 2 As shown, the sensor head 110 includes a housing 111 , an ultrasonic element 112 , a wedge material 113 , an elastic coupling medium 114 , a leaf spring 115 , a damping material 116 and a display light 117 .

[0050] The housing 111 is formed of, for example, a resin material and has an elongated shape (in this example, a substantially rectangular parallelepiped shape) extending in the axial direction. In the following description, in the housing 111, a direction facing the tube P is defined as a lower direction, and a direction opposite to the lower direction is defined as an upper direction. The up-down direction of the housing 111 is orthogonal to the axial direction and the width direction. A window portion W formed of a transparent member is formed on the upper surface of the housing 111. An opening H1 is formed in the lower portion of the housing 111.

[0051] The ultrasonic element 112 includes a transmission / reception surface A1 capable of transmitting and receiving ultrasonic waves. The wedge-shaped material 113 is formed of a non-metallic material having high rigidity and high acoustic transparency. The wedge-shaped material 113 is preferably formed of a material having high environmental resistance. The wedge-shaped material 113 includes a bonding surface B1 facing in an inclined direction, and, in the lower part, the wedge-shaped material 113 includes an incident / transmitting surface C1 facing downward. The transmission / reception surface A1 of the ultrasonic element 112 is bonded to the bonding surface B1 of the wedge-shaped material 113 by an acoustic adhesive not shown.

[0052] The wedge material 113 is mounted to the lower part of the housing 111 via a sealing member not shown to close the opening H1. As a result, a space into which liquids such as water and oil cannot invade is formed in the housing 111. The ultrasonic element 112 is accommodated in the housing 111. The incident / emitting surface C1 of the wedge material 113 protrudes slightly downward from the opening H1 of the housing 111. In this state, the housing 111 is mounted to the mounting metal sheet 150 by two mounting screws 151. The housing 111 is filled with a resin member.

[0053] The elastic coupling medium 114 has a solid shape and is formed of a soft elastic material made of polymer rubber or gel substance. The hardness of the elastic coupling medium 114 is, for example, 20 to 40 degrees. In the lower portion of the elastic coupling medium 114, a downwardly protruding pipe contact portion T1 capable of contacting the pipe P is formed over a predetermined length in the axial direction.

[0054] The elastic coupling medium 114 is arranged to contact the pipe P and the incident / emitting surface C1 of the wedge material 113, thereby matching the acoustic impedance of the pipe P and the acoustic impedance of the wedge material 113. The contact surface of the elastic coupling medium 114 in contact with the wedge material 113 is referred to as a wedge contact surface D1. The contact surface of the pipe contact portion T1 of the elastic coupling medium 114 in contact with the pipe P is referred to as a pipe contact surface E1.

[0055] The leaf spring 115 is arranged to surround the pipe contact portion T1 in the circumferential direction and in the axial direction, and is mounted to the clamping member 130 together with the elastic coupling medium 114 by two mounting screws 134. The damping material 116 is formed of, for example, an elastomer that attenuates ultrasonic waves in the pipe P and is arranged between the leaf spring 115 and the pipe P to surround the pipe contact portion T1 in the circumferential direction and in the axial direction.

[0056] As described below, the flow sensor 1 can also operate as a flow switch that changes the state of a switch signal (ON / OFF signal) to an external device based on whether the fluid flows in the pipe P at a flow rate equal to or higher than a threshold value. The display light 117 includes, for example, a plurality of light emitting diodes that emit light of different colors. Figure 1 The control of the relay unit 200 shown in the figure causes the display lamp 117 to light up or flash in various forms according to the operating state of the flow switch.

[0057] In this embodiment, the display light 117 is lit green when the external device is in the ON state, and is lit red when the external device is in the OFF state. The display light 117 can be lit when the external device is in the ON state and can be extinguished when the external device is in the OFF state. Conversely, the display light 117 can be extinguished when the external device is in the ON state and can be lit when the external device is in the OFF state.

[0058] The display light 117 is arranged in close contact with the window W in the housing 111. As a result, the operation form of the display light 117 can be visually recognized from the outside of the housing 111 through the window W. The user can easily distinguish between the ON state and the OFF state of the external device by visually recognizing the color, lighting state, etc. of the display light 117.

[0059] The sensor head 120 includes a housing 121, an ultrasonic element 122, a wedge material 123, an elastic coupling medium 124, a leaf spring 125, and a damping material 126. The housing 121 has the same configuration as that of the housing 111 except that the window portion W is not formed. Therefore, an opening H2 that is the same as the opening H1 is formed in the housing 121.

[0060] The ultrasonic element 122 and the wedge material 123 have the same configurations as those of the ultrasonic element 112 and the wedge material 113, respectively. Therefore, the ultrasonic element 122 includes a transmission / reception surface A2 that is the same as the transmission / reception surface A1. The wedge material 123 includes a bonding surface B2 and an incident / transmission surface C2 that are the same as the bonding surface B1 and the incident / transmission surface C1, respectively. The transmission / reception surface A2 of the ultrasonic element 122 is bonded to the bonding surface B2 of the wedge material 123. In a state where the wedge material 123 is mounted, the housing 121 is mounted to the mounting metal sheet 160 by two mounting screws 161.

[0061] The elastic coupling medium 124 has the same configuration as that of the elastic coupling medium 114. Therefore, the elastic coupling medium 124 includes a tube contact portion T2, a wedge contact surface D2, and a tube contact surface E2, which are respectively the same as the tube contact portion T1, the wedge contact surface D1, and the tube contact surface E1. The elastic coupling medium 124 is arranged to contact the tube P and the incident / emitting surface C2 of the wedge material 123, thereby matching the acoustic impedance of the tube P and the acoustic impedance of the wedge material 123.

[0062] The leaf spring 125 and the damping material 126 have the same configurations as those of the leaf spring 115 and the damping material 116, respectively. The leaf spring 125 is arranged to surround the tube contact portion T2 in the circumferential direction and in the axial direction and is mounted to the clamping member 140 together with the elastic coupling medium 124 by two mounting screws 144. The damping material 126 is arranged between the leaf spring 125 and the tube P to surround the tube contact portion T2 in the circumferential direction and in the axial direction.

[0063] The mounting metal sheet 150 and the mounting metal sheet 160 are connected to each other by four coupling screws 101 to clamp the clamping member 130, the pipe P, and the clamping member 140. As a result, the sensor head 110 is mounted to the clamping member 130 in a state where the elastic coupling medium 114 and the damping material 116 are pressed against the pipe P by the clamping member 130. Similarly, the sensor head 120 is mounted to the clamping member 140 in a state where the elastic coupling medium 124 and the damping material 126 are pressed against the pipe P by the clamping member 140.

[0064] (2) Flow calculation method

[0065] Figure 3 It is used to illustrate Figure 1 FIG. 1 is a diagram showing a method for calculating a flow rate in the flow sensor 1. Figure 3 In the figure, the clamping members 130 and 140 and the mounting metal sheets 150 and 160 are omitted. Figure 3 As shown, the ultrasonic element 112 and the ultrasonic element 122 are arranged in a state where the ultrasonic element 112 and the ultrasonic element 122 are offset from each other in the axial direction.

[0066] based on Figure 1 By controlling the relay unit 200 shown in FIG. 1 , the ultrasonic element 112 transmits ultrasonic waves in an oblique direction from the transmission / reception surface A1. The transmitted ultrasonic waves are made incident on the wedge material 113 from the joint surface B1. Thereafter, the ultrasonic waves propagate in the wedge material 113 and are transmitted from the incident / transmitting surface C1. The ultrasonic waves transmitted from the incident / transmitting surface are made incident on the elastic coupling medium 114 from the wedge contact surface D1, propagate in the elastic coupling medium 114, and are then transmitted toward the pipe P from the pipe contact surface E1 of the pipe contact portion T1.

[0067] In the present embodiment, in the wedge material 113, the joint surface B1 and the incident / emitting surface C1 are formed so that the incident angle of the transverse wave (shear wave) relative to the axial direction is set to be greater than or equal to the critical angle. In this case, the longitudinal wave and the transverse wave of the ultrasonic wave emitted from the tube contact surface E1 are all reflected by the peripheral wall P1 of the tube P and are difficult to penetrate the peripheral wall P1. On the other hand, the longitudinal wave of the ultrasonic wave collides with the outer peripheral surface of the peripheral wall P1, thereby exciting the guided wave in the peripheral wall P1. The guided wave is an ultrasonic wave that propagates in the tube P in a direction parallel to the axial direction. Like the guided wave, there are also plate waves, surface waves, etc. There are multiple vibration modes in the guided wave. The guided wave has such a characteristic that the phase velocity (phase velocity) and group velocity (group velocity) of the guided wave and the vibration state of the guided wave are different according to the product of the frequency of the ultrasonic wave and the thickness of the peripheral wall P1 and the vibration mode.

[0068] The guided wave in the peripheral wall P1 collides with the inner peripheral surface of the peripheral wall P1, whereby the ultrasonic wave is excited and passes through the fluid and travels to the peripheral wall P2 opposite to the peripheral wall P1 at a predetermined incident angle θ. The longitudinal wave of the ultrasonic wave that passes through the fluid collides with the inner peripheral surface of the peripheral wall P2, thereby exciting the guided wave in the peripheral wall P2. The guided wave in the peripheral wall P2 collides with the outer peripheral surface of the peripheral wall P2, thereby exciting the longitudinal wave of the ultrasonic wave that travels from the pipe P to the pipe contact surface E2 of the elastic coupling medium 124.

[0069] The ultrasonic wave traveling from the pipe P is made incident on the pipe contact portion T2 from the pipe contact surface E2, propagates in the elastic coupling medium 124, and is emitted from the wedge contact surface D2. The ultrasonic wave emitted from the wedge contact surface D2 is made incident on the wedge material 123 from the incident / emission surface C2, thereafter propagates in the wedge material 123, and is emitted from the joint surface B2. Thereafter, the ultrasonic wave is received from the transmission / reception surface A2 of the ultrasonic element 122 based on the control of the relay section 200.

[0070] In this manner, an excitation region R1 against which the longitudinal wave of the ultrasonic wave emitted from the ultrasonic element 112 hits is provided in the peripheral wall P1. The excitation region R1 is a region where the ultrasonic wave that passes through the fluid flowing in the pipe P and travels to the ultrasonic element 122 is mainly excited. Figure 3 , the excitation region R1 is represented by a hatched pattern.

[0071] Subsequently, the ultrasonic element 122 transmits ultrasonic waves in an oblique direction from the transmission / reception surface A2 based on the control of the relay section 200. The transmitted ultrasonic waves are made incident on the wedge material 123 from the joint surface B2. Thereafter, the ultrasonic waves propagate in the wedge material 123 and are transmitted from the incident / transmitting surface C2. The ultrasonic waves transmitted from the incident / transmitting surface C2 are made incident on the elastic coupling medium 124 from the wedge contact surface D2, propagate in the elastic coupling medium 124, and thereafter are transmitted toward the pipe P from the pipe contact surface E2 of the pipe contact portion T2.

[0072] In the present embodiment, the joint surface B2 and the incident / emitting surface C2 are formed in the wedge-shaped material 123 so that the incident angle of the ultrasonic transverse wave with respect to the axial direction is set to be equal to or greater than the critical angle. In this case, the longitudinal wave and the transverse wave of the ultrasonic wave emitted from the pipe contact surface E2 are all reflected by the peripheral wall P2 of the pipe P and are difficult to penetrate into the peripheral wall P2. On the other hand, the longitudinal wave of the ultrasonic wave collides with the outer peripheral surface of the peripheral wall P2, thereby exciting the guided wave in the peripheral wall P2.

[0073] The guided wave in the peripheral wall P2 collides with the inner peripheral surface of the peripheral wall P2, whereby an ultrasonic wave is generated and passes through the fluid and travels to the peripheral wall P1 opposite to the peripheral wall P2 at a predetermined incident angle θ. The longitudinal wave of the ultrasonic wave that passes through the fluid collides with the inner peripheral surface of the peripheral wall P1, thereby exciting the guided wave in the peripheral wall P1. The guided wave in the peripheral wall P1 collides with the outer peripheral surface of the peripheral wall P1, thereby exciting the longitudinal wave of the ultrasonic wave that travels from the pipe P to the pipe contact surface E1 of the elastic coupling medium 114.

[0074] The ultrasonic wave traveling from the pipe P is made incident on the pipe contact portion T1 from the pipe contact surface E1, propagates in the elastic coupling medium 114, and is emitted from the wedge contact surface D1. The ultrasonic wave emitted from the wedge contact surface D1 is made incident on the wedge material 113 from the incident / emission surface C1, and thereafter propagates in the wedge material 113 and is emitted from the contact surface B1. Thereafter, the ultrasonic wave is received from the transmission / reception surface A1 of the ultrasonic element 112 based on the control of the relay unit 200.

[0075] In this manner, an excitation region R2 against which the longitudinal wave of the ultrasonic wave emitted from the ultrasonic element 122 collides is provided in the peripheral wall P2. The excitation region R2 is a region where the ultrasonic wave that passes through the fluid flowing in the pipe P and travels to the ultrasonic element 122 is mainly excited. Figure 3 In FIG. 1 , the excitation region R2 is represented by a dot pattern.

[0076] The difference between the propagation time of the ultrasonic wave from the ultrasonic element 112 to the ultrasonic element 122 and the propagation time of the ultrasonic wave from the ultrasonic element 122 to the ultrasonic element 112 is referred to as a time difference Δt. Based on the time difference Δt, the flow rate Q of the fluid flowing in the pipe P is calculated by the following expression (1). In the expression (1), d1 represents the inner diameter of the pipe P, V s represents the velocity of the ultrasonic wave in the fluid, θ represents the incident angle of the ultrasonic wave in the fluid, and K represents a flow correction coefficient for converting the velocity of the fluid having a predetermined distribution in the cross section of the pipe P into an average velocity. Velocity V s , the incident angle θ and the flow correction coefficient K are known. The user can operate Figure 1 The main body 300 shown is used to set the inner diameter d1 of the tube P.

[0077]

[0078] The flow sensor 1 can also be operated as a flow switch. The user can set a flow threshold by operating the main body 300. The main body 300 compares the flow Q calculated by the expression (1) with the set threshold and outputs an ON / OFF signal to an external device based on the comparison result. The ON / OFF signal is used to control the flow rate Q calculated by the expression (1) and the set threshold. Figure 1 The main body cable C4 shown is connected to the main body portion 300 and sends a signal for switching the external device between the ON state and the OFF state. Figure 2 The display light 117 shown in FIG. 1 is lit to enable distinction between the ON state and the OFF state of the external device.

[0079] (3) Details of the head

[0080] Figure 4 is a schematic cross-sectional view showing details of the sensor heads 110 and 120 . Figure 5 yes Figure 4 The sensor heads 110 and 120 are shown in cross-sectional view along line AA. Figure 4 In the figure, the housings 111 and 121, the indicator light 117, the clamping elements 130 and 140, and the mounting metal sheets 150 and 160 are omitted. Figure 5 In the figure, the housings 111 and 121, the indicator lamp 117, and the mounting metal sheets 150 and 160 are omitted. The sensor head 120 and the clamping members 130 and 140 are indicated by dotted lines.

[0081] The ultrasonic element 112 is formed by a thin plate-shaped piezoelectric element. The thickness of the ultrasonic element 112 is t1 ( Figure 4 ). The width of the ultrasonic element 112 (transmitting / receiving surface A1) is w1 ( Figure 5 ). The thickness and width refer to the dimensions in the tilt direction and the width direction, respectively. The dimension (length) of the transmitting / receiving surface A1 in the longitudinal direction is L1 ( Figure 4 ). The length L1 may be substantially equal to the width w1 or may be greater than the width w1. Figure 4 , the thickness of the ultrasonic element 112 is shown as being greater than the actual thickness. The outer diameter of the tube P is d2. The thickness of the peripheral wall is t2.

[0082] An AC voltage (pulse voltage) close to the natural frequency is applied to the ultrasonic element 112. As a result, the ultrasonic element 112 is resonant at the natural frequency (resonance frequency f r ) vibrates and transmits ultrasonic waves with high intensity. In the following description, the resonant frequency f of the ultrasonic wave expressed in MHz (megahertz) is r The product of the thickness t2 of the peripheral wall expressed in mm (millimeter) is referred to as the f·t product.

[0083] The ultrasonic element 112 is preferably formed to have a resonance frequency f r Vibration, resonant frequency f r The f·t product is greater than or equal to 2 and less than or equal to 6. By setting the f·t product to be greater than or equal to 2, the fluctuation of the phase velocity of the guided wave in the peripheral wall is prevented. As a result, the flow rate of the fluid can be calculated more accurately. By setting the f·t product to be less than or equal to 6, the surface wave of the guided wave in the peripheral wall is prevented from dominating. As a result, ultrasonic waves with high intensity can be generated in the fluid.

[0084] The ultrasonic element 112 is preferably formed so that the width w1 is greater than or equal to five times the thickness t1. In this case, the intensity of the plurality of resonances in the width direction is reduced relative to the resonance in the oblique direction as the transmission direction of the ultrasonic wave. As a result, the resonance characteristics in the oblique direction can be improved. The preferred configuration of the ultrasonic element 122 is the same as the preferred configuration of the ultrasonic element 112.

[0085] The width of the portion of the peripheral wall of the pipe P to which the ultrasonic wave is irradiated (hereinafter referred to as the irradiation width) is preferably equal to or less than one third of the outer diameter d2 of the pipe P. In this case, the component of the ultrasonic wave that propagates in the peripheral wall without passing through the fluid and is transmitted and received between the sensor heads 110 and 120 can be further reduced. As a result, the flow rate of the fluid can be calculated more accurately.

[0086] As described above, the width w1 of the ultrasonic element 112 is preferably equal to or greater than five times the thickness t1. In order to prevent the ultrasonic element 112 from being damaged, the thickness t1 of the ultrasonic element 112 needs to be set to be equal to or greater than a predetermined thickness. Therefore, the width w1 of the ultrasonic element 112 (transmitting / receiving surface A1) is greater than the predetermined width.

[0087] On the other hand, as described above, it is preferable that the irradiation width of the ultrasonic wave is equal to or less than one third of the outer diameter d2 of the pipe P. In this embodiment, since the outer diameter d2 of the pipe P is relatively small (for example, equal to or greater than 2 mm and equal to or less than 20 mm), the irradiation width of the ultrasonic wave is smaller than the predetermined width. In this way, when the ultrasonic wave transmitted from the entire area of ​​the width w1 of the transmission / reception surface A1 is irradiated to the pipe P, both of the above-described preferred conditions cannot be satisfied.

[0088] Therefore, a propagation path for propagating the ultrasonic wave transmitted from the transmission / reception surface A1 of the ultrasonic element 112 to the pipe P is provided in the elastic coupling medium 114. In the propagation path, a width change portion V1 is formed whose width changes between the wedge contact surface D1 and the pipe contact surface E1. In this embodiment, the wedge contact surface D1 of the elastic coupling medium 114 is formed to have a width w1. On the other hand, the pipe contact portion T1 and the pipe contact surface E1 are formed to have a width w2 smaller than w1. Specifically, the width w2 is equal to or less than one-third of the outer diameter d2 of the pipe P. That is, in the width change portion V1 of the propagation path, between the wedge contact surface D1 and the pipe contact surface E1, the width changes from w1 to w2.

[0089] In this configuration, an ultrasonic wave having a large width w1 is made incident on the elastic coupling medium 114 from the wedge contact surface D1. Thereafter, the ultrasonic wave propagates in the elastic coupling medium 114 and is emitted from the lower surface (emitting surface) of the elastic coupling medium 114. The emission surfaces of the ultrasonic wave other than the tube contact surface E1 do not contact the tube P. Therefore, the ultrasonic wave emitted from the emission surface gradually attenuates and is difficult to be irradiated onto the tube P. On the other hand, since the tube contact surface E1 is in contact with the tube P, the ultrasonic wave emitted from the tube contact surface E1 is hardly attenuated and is irradiated onto the tube P.

[0090] In particular, in this embodiment, the leaf spring 115 formed of a metal member is arranged between the pipe P and the emitting surface of the ultrasonic wave other than the pipe contact surface E1. In this case, the ultrasonic wave emitted from the emitting surface is blocked by the leaf spring 115. As a result, it is possible to reliably prevent the ultrasonic wave from being irradiated onto the pipe P from the emitting surface other than the pipe contact surface E1.

[0091] In this way, even when ultrasonic waves are transmitted from the transmission / reception surface A1 of the ultrasonic element 112 having a large width w1, ultrasonic waves having a small width w2 can be irradiated onto the pipe P. As a result, both preferred conditions can be satisfied. In this embodiment, the width of the width change portion V1 is changed from w1 to w2. However, the present invention is not limited thereto. The width of the width change portion V1 may be changed from w3 different from w1 and w2 to w2. The width w3 may be larger than w1 or may be smaller than w1.

[0092] The ultrasonic element 112 is arranged to transmit ultrasonic waves in an oblique direction. Therefore, the diffusion area of ​​ultrasonic waves in the axial direction is larger than the diffusion area of ​​ultrasonic waves transmitted by the ultrasonic element 112 in a direction orthogonal to the axial direction. Therefore, the tube contact surface E1 of the tube contact portion T1 of the elastic coupling medium 114 is preferably formed to have a length L2 greater than L1 in the axial direction. As a result, ultrasonic waves can be irradiated on the tube P from the tube contact surface E1 over a sufficiently large area in the axial direction.

[0093] The configuration of the elastic coupling medium 124 is the same as that of the elastic coupling medium 114. Therefore, a width change portion V2 identical to the width change portion V1 is formed in the propagation path of the elastic coupling medium 124. The tube contact surface E2 of the tube contact portion T2 of the elastic coupling medium 124 is preferably formed to have a length L2 greater than L1 in the axial direction.

[0094] A rectangular slit S3 extending in the axial direction is formed in the leaf spring 115. A rectangular slit S1 extending in the axial direction and overlapping with the slit S3 is formed in the damping material 116. The tube contact portion T1 of the elastic coupling medium 114 is fitted in the slit S3 of the leaf spring 115 and the slit S1 of the damping material 116. In this case, the tube contact portion T1 is surrounded by the leaf spring 115 and the damping material 116 in the circumferential direction and in the axial direction while in contact with the tube P.

[0095] The plate spring 115 is made to surround the tube contact portion T1 in a state of being mounted on the clamp member 130, thereby maintaining the position and posture of the elastic coupling medium 114 relative to the clamp member 130. As a result, even when the tube contact portion T1 having a small width w2 is pressed against the pipe P, the change in the width of the tube contact portion T1 is restricted. Therefore, the ultrasonic wave having the small width w2 can be easily irradiated onto the pipe P. With the width of the tube contact portion T1 maintained, bending, meandering, and deformation of the tube contact portion T1 are prevented. As a result, the flow rate of the fluid flowing in the pipe P can be accurately calculated.

[0096] The damping material 116 is mounted to the pipe P while surrounding the pipe contact portion T1 and the excitation region R1 in the circumferential direction, and the damping material 116 is pressed against the pipe P. In this case, vibration of a portion of the pipe P other than the excitation region R1 is prevented. The ultrasonic wave propagating in the circumferential direction in the peripheral wall is attenuated by the damping material 116. As a result, the component of the ultrasonic wave that propagates in the peripheral wall without passing through the fluid and is transmitted and received between the sensor heads 110 and 120 can be further reduced.

[0097] The damping material 116 is mounted on the pipe P while surrounding the pipe contact portion T1 and the excitation region R1 in the axial direction, and the damping material 116 is pressed against the pipe P. In this case, vibration of a portion of the pipe P other than the excitation region R1 is prevented. The ultrasonic wave propagating in the axial direction in the peripheral wall of the pipe P is attenuated by the damping material 116. Therefore, the guided wave propagating in the axial direction is prevented from being reflected at the end face of the peripheral wall in the axial direction and is prevented from returning. Therefore, the returning guided wave does not excite the ultrasonic wave at an unnecessary timing. As a result, the flow rate of the fluid can be calculated more accurately.

[0098] The structure of the leaf spring 125 and the structure of the damping material 126 are respectively the same as the structure of the leaf spring 115 and the structure of the damping material 116. Therefore, a slit S4 which is the same as the slit S3 is formed in the leaf spring 125. A slit S2 which is the same as the slit S1 is formed in the damping material 126. The tube contact portion T2 of the elastic coupling medium 124 is fitted into the slit S4 of the leaf spring 125 and the slit S2 of the damping material 126. As a result, the tube contact portion T2 is surrounded by the leaf spring 125 and the damping material 126 in the circumferential direction and the axial direction while in contact with the tube P. The damping material 126 is mounted on the tube P in a state of surrounding the excitation region R2 in the circumferential direction and the axial direction, and the damping material 126 is pressed against the tube P.

[0099] Figure 6 1 is a schematic cross-sectional view showing the internal structure of the head 100 in a modified example. Figure 6 As shown, in the modified example, a standing wall portion W1 that surrounds the edge of the slit S3 and extends toward the pipe P is formed in the leaf spring 115. The standing wall portion W1 surrounds the pipe contact portion T1 of the elastic coupling medium 114 while being fitted in the slit S1 of the damping material 116. In this case, the leaf spring 115 more firmly maintains the position and posture of the elastic coupling medium 114 relative to the clamping member 130. As a result, bending, meandering, and deformation of the pipe contact portion T1 are more reliably prevented.

[0100] Similarly, in the modification, a standing wall portion W2 surrounding the edge of the slit S4 and extending toward the pipe P is formed in the leaf spring 125 . The standing wall portion W2 surrounds the pipe contact portion T2 of the elastic coupling medium 124 while being fitted in the slit S2 of the damping material 126 .

[0101] (4) Installation from head to tube

[0102] Figure 7 and Figure 8 1 is a diagram for explaining the process of installing the head 100 on the pipe P. Figure 7 As shown, the elastic coupling medium 114 is arranged between the clamping member 130 and the leaf spring 115. Then, at the tube contact portion T1 ( Figure 4 and Figure 5 ) is fitted into the slit S3 of the leaf spring 115, the leaf spring 115 is mounted to the clamp member 130 by two mounting screws 134. The tip of the tube contact portion T1 protrudes from the slit S3 of the leaf spring 115.

[0103] Then, the damping material 116 is arranged in such a manner that the tip of the tube contact portion T1 is fitted in the slit S1. The damping material 116 may be bonded to the leaf spring 115 by an adhesive or the like. In this case, the elastic coupling medium 114, the leaf spring 115, and the damping material 116 are easily handled integrally with the clamping member 130.

[0104] Similarly, the elastic coupling medium 124 is arranged between the clamping member 140 and the leaf spring 125. Then, the tube contact portion T2 of the elastic coupling medium 124 is fitted into the slit S4 ( Figure 4 and Figure 5 ), the leaf spring 125 is mounted to the clamp member 140 by two mounting screws 144. The tip of the tube contact portion T2 protrudes from the slit S4 of the leaf spring 125.

[0105] Then, the damping material 126 is arranged so that the end of the tube contact portion T2 is fitted into the slit S2 ( Figure 4 and Figure 5 ). The damping material 126 may be bonded to the leaf spring 125 by an adhesive or the like. In this case, it is easy to integrally handle the elastic coupling medium 124, the leaf spring 125, and the damping material 126 together with the clamping member 140.

[0106] The clamping member 140 includes a pair of vertical walls 141 extending in the axial direction and facing each other in the width direction, and a pair of vertical walls 142 facing each other in the axial direction. The clamping member 140 includes a support portion 143 formed to be able to support the pipe P by contacting the pipe P. A pair of temporary fixing members 145 for temporarily fixing the clamping member 140 to the pipe P are provided on surfaces (inner surfaces) facing each other of the pair of vertical walls 141. The temporary fixing members 145 are formed by an elastic body such as a rubber member. In the present embodiment, the pair of temporary fixing members 145 are arranged to be staggered from each other in the axial direction without facing each other in the width direction.

[0107] The clamping member 130 includes a pair of vertical walls 131 extending in the axial direction and facing each other in the width direction and a pair of vertical walls 132 facing each other in the axial direction. The pair of vertical walls 131 and the pair of vertical walls 141 correspond to each other. Similarly, the pair of vertical walls 132 and the pair of vertical walls 142 correspond to each other. The clamping member 130 includes a support portion 133 formed to be able to support the pipe P by contacting the pipe P.

[0108] The pair of vertical walls 131 and the pair of vertical walls 132 guide the clamping member 130 when the clamping member 130 is mounted to the pipe P. The pair of vertical walls 141 and the pair of vertical walls 142 guide the clamping member 140 when the clamping member 140 is mounted to the pipe P. The clamping members 130 and 140 are guided by the pair of vertical walls 131 and 141 corresponding to each other and the pair of vertical walls 132 and 142 corresponding to each other.

[0109] The inner surfaces of the pair of vertical walls 131 and the outer surfaces of the pair of vertical walls 141 have a dimensional relationship with which a gap is formed for enabling the inner surfaces and the outer surfaces to move parallel to each other when facing each other and for restricting the inner surfaces and the outer surfaces from tilting more than a predetermined angle around the axial direction of the pipe P. Similarly, the inner surfaces of the pair of vertical walls 132 and the outer surfaces of the pair of vertical walls 142 have a dimensional relationship with which a gap is formed for enabling the inner surfaces and the outer surfaces to move parallel to each other when facing each other and for restricting the inner surfaces and the outer surfaces from tilting more than a predetermined angle in the pitch direction along the axial direction of the pipe P.

[0110] The clamping member 140 is arranged to position the pipe P between the inner surfaces of the pair of vertical walls 141. In this case, the pair of temporary fixing members 145 are in contact with the pipe P. The clamping member 130 is arranged to position the pair of vertical walls 141 between the inner surfaces of the pair of vertical walls 131 and to position the pair of vertical walls 142 between the inner surfaces of the pair of vertical walls 132. Thereafter, the clamping member 130 and the clamping member 140 clamp the pipe P with a predetermined pressing force or more. In this state, the pair of temporary fixing screws 135 are respectively screwed into the pair of temporary fixing members 145 of the clamping member 140 in such a manner as to penetrate the clamping member 130 in the up-down direction.

[0111] According to the above process, the clamping members 130 and 140 are temporarily fixed to the pipe P together with the elastic coupling media 114 and 124, the leaf springs 115 and 125, and the damping materials 116 and 126. In this case, the clamping members 130 and 140 are maintained in a compressed state by the pair of temporary fixing members 145 and the pair of temporary fixing screws 135. As a result, the clamping members 130 and 140 are prevented from falling off the pipe P. The clamping members 130 and 140 are prevented from sliding in the axial direction by the friction force generated between the clamping members 130 and 140 and the pipe P.

[0112] A screw hole having a diameter slightly smaller than that of a threaded portion of the temporary fixing screw 135 corresponding to the screw hole is formed in the temporary fixing member 145. When the clamping members 130 and 140 clamp the pipe P with a predetermined pressure or more, the temporary fixing screw 135 is inserted into the temporary fixing member 145 while expanding the screw hole of the temporary fixing member 145 corresponding to the temporary fixing screw 135. In this case, the temporary fixing screw 135 is prevented from coming out of the temporary fixing member 145 due to the friction force generated between the temporary fixing screw 135 and the temporary fixing member 145. As a result, it is possible to maintain a state in which the clamping members 130 and 140 clamp the pipe P with a predetermined pressure or more.

[0113] The length of the threaded portion of the temporary fixing screw 135 inserted into the screw hole of the temporary fixing member 145 differs according to the outer diameter of the pipe P. Specifically, the insertion portion of the temporary fixing screw 135 is short when the outer diameter of the pipe P is large. The insertion portion of the temporary fixing screw 135 is long when the outer diameter of the pipe P is small. Therefore, the screw hole of the temporary fixing member 145 is formed to have such a length that a sufficient friction force can be generated even when the insertion portion of the temporary fixing screw 135 is shortest, and the tip of the temporary fixing screw 135 does not contact the bottom of the screw hole of the temporary fixing member 145 even when the insertion portion of the temporary fixing screw 135 is longest. As a result, the clamping members 130 and 140 can be temporarily fixed to the pipes P having various outer diameters.

[0114] Thereafter, the mounting metal sheets 150 and 160 are arranged to clamp the clamping members 130 and 140 temporarily fixed to the pipe P. Figure 2 As shown, the housing 111 is mounted on the mounting metal sheet 150 by two mounting screws 151 , and the housing 121 is mounted on the mounting metal sheet 160 by two mounting screws 161 .

[0115] In this state, the mounting metal sheet 150 and the mounting metal sheet 160 are coupled to each other by the four coupling screws 101, thereby clamping the pipe P in such a manner that the mounting metal sheet 150 is mounted to the clamp member 130 and the mounting metal sheet 160 is mounted to the clamp member 140. As a result, the sensor head 110 is mounted to the pipe P through the clamp member 130 with the pipe P supported by the support portion 133 of the clamp member 130. The sensor head 120 is mounted to the clamp member 140 with the pipe P supported by the support portion 143 of the clamp member 140.

[0116] In a state where the sensor head 110 is mounted on the pipe P, the elastic coupling medium 114 and the damping material 116 are pressed against the pipe P by the clamping member 130. The pipe contact portion T1 of the elastic coupling medium 114 is arranged along the axial direction while in contact with the pipe P. The support portion 133 of the clamping member 130 is in contact with the pipe P, whereby the crushing amount of the elastic coupling medium 114 (pipe contact portion T1) is restricted. Therefore, the elastic coupling medium 114 can be uniformly pressed without considering individual differences of operators who mount the clamping member 130.

[0117] Similarly, in a state where the sensor head 120 is mounted on the pipe P, the elastic coupling medium 124 and the damping material 126 are pressed against the pipe P by the clamping member 140. The pipe contact portion T2 of the elastic coupling medium 124 is arranged along the axial direction while in contact with the pipe P. The support portion 143 of the clamping member 140 is in contact with the pipe P, whereby the amount of collapse of the elastic coupling medium 124 (pipe contact portion T2) is limited. Therefore, the elastic coupling medium 124 can be uniformly pressed without considering individual differences of operators who mount the clamping member 140.

[0118] Fig. 9 1 is a schematic cross-sectional view showing the interior of the clamping members 130 and 140 in a state where the pipe P is not mounted. Fig.10 and Fig.11 1 is a schematic cross-sectional view showing the interior of the clamping members 130 and 140 in a state where the pipe P is mounted. Fig.11 The outer diameter of the tube P shown is slightly larger than Fig.10 The outer diameter of the pipe P is shown.

[0119] In the present embodiment, the leaf springs 115 and 125 and the damping materials 116 and 126 have high elasticity. The leaf springs 115 and 125 are semi-cylindrical thin plate springs and are thin leaf springs whose circumferential ends are arc-shaped cantilevered relative to the fixing portions mounted to the clamping members 130 and 140 by two mounting screws 134 and 144. Figures 9 to 11 As shown, a space V for allowing the leaf springs 115 and 125 and the damping materials 116 and 126 to deform is fixed in the clamping members 130 and 140. Fig. 9 As shown, in a state where the pipe P is not mounted to the leaf springs 115 and 125 , the diameter of the inner surface of the damping materials 116 and 126 is set to be slightly smaller than the outer diameter of the pipe P that can be mounted.

[0120] like Fig.10As shown, the clamping members 130 and 140 clamp the pipe P. The pipe P is attached to the leaf springs 115 and 125. At this time, as indicated by white arrows, forces facing each other are generated in the leaf springs 115 and 125, and forces facing each other are generated in the damping materials 116 and 126, whereby the leaf springs 115 and 125 and the damping materials 116 and 126 expand in the space V. In this case, as indicated by dot-dash arrows, a pressing force is also generated in a direction different from the clamping direction of the clamping members 130 and 140 (direction toward the axial center of the pipe P) by the elasticity of the thin leaf springs of the respective arc-shaped cantilever arms of the leaf springs 115 and 125 against expansion. As a result, simply by clamping the pipe P with the clamping members 130 and 140, the damping materials 116 and 126 are pressed against the pipe P toward the axial center of the pipe P by the leaf springs 115 and 125 as springs of semi-cylindrical thin plates. As a result, unnecessary components of the ultrasonic waves propagating through the peripheral wall of the pipe P can be reliably attenuated.

[0121] like Fig.11 As shown, even when the outer diameters of the pipes P are slightly different, when the clamping members 130 and 140 are as shown in FIG. Fig.10 When the pipe P is clamped as shown, a pressure is generated in a direction toward the axial center of the pipe P by the elasticity of the leaf springs 115 and 125. As a result, the damping materials 116 and 126 are pressed against the pipe P toward the axial center of the pipe P.

[0122] The space V is fixed in the clamping members 130 and 140 in this manner, thereby allowing the leaf springs 115 and 125 to deform even when there is an error or fluctuation in the outer diameter of the pipe P. As a result, the clamping members 130 and 140 can be easily mounted to the pipe P. The damping material 116 is deformed, thereby enabling the damping material 116 to be surely pressed against the pipe P by the clamping member 130. Similarly, the damping material 126 is deformed, thereby enabling the damping material 126 to be surely pressed against the pipe P by the clamping member 140.

[0123] (5) Relay unit and main unit

[0124] Fig.12 It is shown Figure 1 The block diagram of the internal structure of the relay unit 200 and the main body 300 is shown. Fig.12 As shown, the relay unit 200 includes a switch circuit 201, sending circuits 202 and 203, an amplifier circuit 204, an A / D (analog / digital) converter 205, a relay control unit 206, a correction information storage unit 207, a communication circuit 208, a power supply circuit 209 and a display light driving circuit 210.

[0125] Switching circuit 201 via Figure 1 The head cable CA1 shown is connected to the ultrasonic element 112 and is connected to the ultrasonic element 112 via Figure 1The head cable CA2 shown is connected to the ultrasonic element 122. In the relay section 200, the switch circuit 201 is connected to the amplifier circuit 204. The switch circuit 201 switches the connection state of the ultrasonic elements 112 and 122 and the amplifier circuit 204 between the first state and the second state based on the control of the relay control section 206.

[0126] The first state is a state in which the ultrasonic element 122 is connected to the amplifier circuit 204 and the ultrasonic element 112 is not connected to the amplifier circuit 204. In the first state, the ultrasonic element 122 receives an ultrasonic wave and outputs an ultrasonic wave signal in an analog format corresponding to the received ultrasonic wave. The ultrasonic wave signal output from the ultrasonic element 122 is given to the amplifier circuit 204.

[0127] The second state is a state in which the ultrasonic element 112 is connected to the amplifier circuit 204 and the ultrasonic element 122 is not connected to the amplifier circuit 204. In the second state, the ultrasonic element 112 receives an ultrasonic wave and outputs an ultrasonic signal in an analog format corresponding to the received ultrasonic wave. The ultrasonic signal output from the ultrasonic element 112 is given to the amplifier circuit 204.

[0128] The transmission circuit 202 includes a three-state driver. In the transmission circuit 202, the output state of the three-state driver switches among three states (H level state, L level state and high impedance state) based on the control of the relay control unit 206, thereby generating a first drive signal. The ultrasonic element 112 transmits ultrasonic waves in response to the first drive signal generated by the transmission circuit 202.

[0129] Similarly, the transmission circuit 203 includes a three-state driver. In the transmission circuit 203, the output state of the three-state driver switches among three states based on the control of the relay control unit 206, thereby generating a second drive signal. The ultrasonic element 122 transmits ultrasonic waves in response to the second drive signal generated by the transmission circuit 203.

[0130] The amplifier circuit 204 amplifies the ultrasonic signal given by the ultrasonic element 112 or the ultrasonic element 122 at a predetermined gain and gives the ultrasonic signal after amplification to the A / D converter 205. The A / D converter 205 performs A / D conversion of the given ultrasonic signal and gives the ultrasonic signal in a digital format to the relay control unit 206 after the conversion.

[0131] The relay control unit 206 is composed of, for example, an FPGA (field programmable gate array) or a CPU (central processing unit) and a memory. The relay control unit 206 includes an ultrasonic control unit 206a, a measurement information generating unit 206b, and a display light control unit 206c as functional units. When the relay control unit 206 is composed of a CPU and a memory, these functional units are implemented by the CPU executing a computer program stored in the memory. A part of the ultrasonic control unit 206a, the measurement information generating unit 206b, and the display light control unit 206c can be implemented by an electronic circuit (hardware) such as an FPGA. The remaining part can be implemented by the CPU executing the computer program.

[0132] The ultrasonic control section 206a controls the switch circuit 201 and the transmission circuits 202 and 203 based on the control of the main body section 300. For example, the ultrasonic control section 206a changes the connection state between the ultrasonic elements 112 and 122 and the amplifier circuit 204 to the first state and operates the transmission circuit 202 to generate a first drive signal. In this case, the ultrasonic signal is transmitted by the ultrasonic element 112 and received by the ultrasonic element 122. The ultrasonic signal output from the ultrasonic element 122 is amplified by the amplifier circuit 204, A / D converted by the A / D converter 205, and then given to the measurement information generation section 206b.

[0133] The ultrasonic control section 206a changes the connection state between the ultrasonic elements 112 and 122 and the amplifier circuit 204 to the second state and operates the transmission circuit 203 to generate a second drive signal. In this case, ultrasonic waves are transmitted by the ultrasonic element 122 and received by the ultrasonic element 112. The ultrasonic signal output from the ultrasonic element 112 is amplified by the amplifier circuit 204, A / D converted by the A / D converter 205, and then given to the measurement information generation section 206b.

[0134] The measurement information generating section 206b generates the time difference as the measurement information based on the peak value of the cross-correlation function of the signal waveforms of the two ultrasonic signals output from the ultrasonic elements 112 and 122. The measurement information generating section 206b may measure the propagation time of the ultrasonic wave from the ultrasonic element 112 to the ultrasonic element 122 and the propagation time of the ultrasonic wave from the ultrasonic element 122 to the ultrasonic element 112, and calculate the difference between the times as the time difference.

[0135] The indicator light control unit 206c controls the indicator light drive circuit 210 based on the control of the main body 300. The indicator light drive circuit 210 is connected to the display light via Figure 1The head cable CA1 shown is connected to the display light 117. The display light driving circuit 210 generates a third driving signal for driving the display light 117 based on the control of the display light control section 206c.

[0136] The correction information storage section 207 is constituted by, for example, a nonvolatile memory and stores correction information on the ultrasonic elements 112 and 122 , the switch circuit 201 , the transmission circuits 202 and 203 , the amplifier circuit 204 , and the A / D converter 205 .

[0137] According to the operational characteristics of the components of the head 100 and the relay 200, the time difference calculated by the measurement information generating section 206b and the flow rate of the fluid flowing in the pipe P do not satisfy the relational expression (1). The correction information is information for correcting the expression (1) so as to accurately calculate the inherent relationship between the time difference calculated by the measurement information generating section 206b and the flow rate to be actually measured. The correction information includes, for example, the value of a coefficient for adjusting the time difference Δt in the expression (1) and an offset value (adjustment value relative to the flow rate 0) to be added to the term including the time difference Δt in the expression (1).

[0138] Communication loop 208 is connected to Figure 1 The communication circuit 208 outputs the calibration information and the digital measurement information generated by the measurement information generating unit 206b to the main unit 300 via the relay cable CA3. The communication circuit 208 gives the transmission control signal and the display control signal input from the main unit 300 to the relay control unit 206 via the relay cable CA3. The transmission control signal is a control signal for controlling the transmission circuits 202 and 203. The display control signal is a control signal for controlling the display light driving circuit 210.

[0139] The power circuit 209 receives power supplied from the main body portion 300 through the relay cable CA3 , and supplies the received power to other components provided in the relay portion 200 .

[0140] The main body 300 includes a communication circuit 301, a main body control unit 302, a display unit 303, an operation unit 304, a storage unit 305, an output circuit 306, and a power supply circuit 307. The communication circuit 301 is connected to Figure 1 The communication circuit 301 gives the measurement information and correction information output from the relay unit 200 to the main body control unit 302 via the relay cable CA3. The communication circuit 301 outputs the transmission control signal and display control signal generated in the main body control unit 302 to the relay unit 200 via the relay cable CA3 as described below.

[0141] The display unit 303 includes, for example, a segment display or a dot matrix display and displays, for example, the flow rate of the fluid flowing in the pipe P based on the control of the main body control unit 302. The operation unit 304 includes a plurality of operation buttons. The user can input the size of the pipe P to be mounted on the head 100, the flow rate correction coefficient, etc. by operating the operation unit 304. The user can input the threshold value of the flow rate by operating the operation unit 304. The storage unit 305 is composed of a nonvolatile memory or a hard disk drive.

[0142] The main body control section 302 includes, for example, a CPU and a memory and generates a transmission control signal and a display control signal to be given to the relay section 200 so as to respectively drive the ultrasonic elements 112 and 122 and the display lamp 117. The main body control section 302 causes the storage section 305 to store information such as the size of the pipe P, the flow rate correction coefficient, and the threshold value of the flow rate input through the operation section 304, thereby setting the information. As the size of the pipe P, the outer diameter d2 of the pipe P and the thickness t2 of the peripheral wall are input to the operation section 304, whereby the inner diameter d1 of the pipe P can be set.

[0143] In addition, the main body control unit 302 corrects the expression (1) based on the correction information given from the communication circuit 301. The main body control unit 302 calculates the flow rate of the fluid flowing in the pipe P based on the measurement information given from the communication circuit 301 and the set flow rate correction coefficient. The main body control unit 302 generates an ON / OFF signal based on the comparison result of the calculated flow rate and the set flow rate threshold value. The output circuit 306 is connected to Figure 1 The output circuit 306 outputs the ON / OFF signal generated by the main body control unit 302 to the external device of the flow sensor 1 through the main body cable CA4.

[0144] (6) Effect

[0145] In the flow sensor 1 according to the present embodiment, the ultrasonic wave emitted from the ultrasonic element 112 propagates through the wedge material 113 and is emitted from the incident / emission surface C1 inclined with respect to the propagation direction of the ultrasonic wave. The elastic coupling medium 114 is supported on the pipe P in such a manner that the pipe contact portion T1 is in contact with the pipe P and arranged in the axial direction. The elastic coupling medium 114 propagates the ultrasonic wave emitted from the incident / emission surface C1 of the wedge material 113 to the pipe P via the pipe contact portion T1. The damping material 116 is arranged to attenuate the ultrasonic wave and surrounds the pipe contact portion T1 of the elastic coupling medium 114 between the clamping member 130 and the pipe P.

[0146] The ultrasonic wave emitted from the ultrasonic element 122 propagates through the wedge material 123 and is emitted from the incident / emission surface C2 inclined with respect to the propagation direction of the ultrasonic wave. The elastic coupling medium 124 is supported on the pipe P by the clamping member 140 in such a manner that the pipe contact portion T2 contacts the pipe P and is arranged in the axial direction. The elastic coupling medium 124 propagates the ultrasonic wave emitted from the incident / emission surface C2 of the wedge material 123 to the pipe P via the pipe contact portion T2. ​​The damping material 126 is arranged to attenuate the ultrasonic wave and surrounds the pipe contact portion T2 of the elastic coupling medium 124 between the clamping member 140 and the pipe P.

[0147] The clamping members 130 and 140 are coupled to each other to clamp the pipe P in a state where the damping material 116 is pressed by the clamping member 130 and the damping material 126 is pressed by the clamping member 140 . Ultrasonic waves are transmitted and received through the pipe P between the ultrasonic elements 112 and 122 .

[0148] With this configuration, Lamb waves are excited in the peripheral wall of the pipe P by vibration. Ultrasonic waves can be transmitted and received between the ultrasonic element 112 and the ultrasonic element 122 through the pipe P using the excited Lamb waves. In this case, unnecessary components of ultrasonic waves that propagate in the peripheral wall of the pipe P and do not pass through the fluid and are transmitted and received between the ultrasonic element 112 and the ultrasonic element 122 are reduced. Therefore, it is easy to calculate the flow rate of the fluid flowing in the pipe P based on the ultrasonic waves transmitted and received between the ultrasonic element 112 and the ultrasonic element 122.

[0149] In a state where the damping material 116 surrounds the tube contact portion T1, the damping material 116 is pressed against the tube P. In a state where the damping material 126 surrounds the tube contact portion T2, the damping material 126 is pressed against the tube P. Therefore, vibration of portions of the tube P other than the contact portions of the tube contact portions T1 and T2 is prevented. The components of the ultrasonic wave that propagate in the circumferential direction in the peripheral wall of the tube P are attenuated by the damping materials 116 and 126. As a result, unnecessary components of the ultrasonic wave that propagate in the peripheral wall of the tube P and do not pass through the fluid and are transmitted and received between the ultrasonic element 112 and the ultrasonic element 122 are further reduced.

[0150] The ultrasonic wave propagating in the axial direction in the peripheral wall of the pipe P is prevented from being reflected at the end surface in the axial direction of the peripheral wall and returning by the damping materials 116 and 126. Therefore, the returning ultrasonic wave does not excite the ultrasonic wave at an unnecessary timing. As a result, the flow rate of the fluid flowing in the metal pipe P having a small diameter can be calculated.

[0151] (7) Other Implementation Methods

[0152] (a) In the embodiment, the relay unit 200 and the main body 300 are provided as separate bodies and connected by the relay cable CA3. However, the present invention is not limited thereto. The relay unit 200 and the main body 300 may be provided integrally.

[0153] (b) In the embodiment, the damping material 116 is composed of one elastic body surrounding the tube contact portion T1 of the elastic coupling medium 114 in the circumferential direction and the axial direction. However, the present invention is not limited thereto. The damping material 116 may be composed of a plurality of elastic bodies surrounding the tube contact portion T1 of the elastic coupling medium 114 in the circumferential direction and the axial direction. In this case, the slit S1 may not be formed in the damping material 116. Similarly, the damping material 126 may be composed of a plurality of elastic bodies surrounding the tube contact portion T2 of the elastic coupling medium 124 in the circumferential direction and the axial direction.

[0154] (c) In the embodiment, the leaf springs 115 and 125 are provided in the head 100. However, the present invention is not limited thereto. The leaf spring 115 may not be provided in the head 100. In this case, the damping material 116 may be attached to the clamping member 130 by an adhesive or the like. The tube contact portion T1 of the elastic coupling medium 114 is fitted in the slit S1 of the damping material 116. As a result, the damping material 116 maintains the position and posture of the elastic coupling medium 114 relative to the clamping member 130.

[0155] Similarly, the leaf spring 125 may not be provided in the head 100. In this case, the damping material 126 may be attached to the clamping member 140 by an adhesive or the like. The tube contact portion T2 of the elastic coupling medium 124 is fitted into the slit S2 of the damping material 126. As a result, the damping material 126 maintains the position and posture of the elastic coupling medium 124 relative to the clamping member 140.

[0156] (8) Correspondence between the components of the technical solution and the parts of the implementation method

[0157] An example of the correspondence between the constituent elements of the technical solution and the parts of the implementation scheme is described below. However, the present invention is not limited to this example. It is also possible to use various other elements having the structure or function described in the technical solution as constituent elements of the technical solution.

[0158] In the embodiment, the tube P is an example of a tube. The flow sensor 1 is an example of a clamp-on ultrasonic flow sensor. The ultrasonic elements 112 and 122 are examples of a first ultrasonic element and a second ultrasonic element, respectively. The incident / emission surfaces C1 and C2 are examples of a first incident / emission surface and a second incident / emission surface, respectively. The wedge materials 113 and 123 are examples of a first wedge material and a second wedge material, respectively. The tube contact portions T1 and T2 are examples of a first tube contact portion and a second tube contact portion, respectively.

[0159] Elastic coupling media 114 and 124 are examples of a first elastic coupling medium and a second elastic coupling medium, respectively. Clamping members 130 and 140 are examples of a first clamping member and a second clamping member, respectively. Damping materials 116 and 126 are examples of a first damping material and a second damping material, respectively. The main body control portion 302 is an example of a flow calculation portion. Slits S1 to S4 are examples of a first slit to a fourth slit, respectively. Space V is an example of a space. Leaf springs 115 and 125 are examples of a first pressurizing member and a second pressurizing member, respectively. Vertical walls 131, 132, 141, and 142 are examples of guide walls. Excitation regions R1 and R2 are examples of a first excitation region and a second excitation region, respectively.

Claims

1. A clamp-on ultrasonic flow sensor for measuring the flow of a fluid flowing in a pipe, the clamp-on ultrasonic flow sensor comprising: a first ultrasonic element configured to transmit and receive ultrasonic waves; a first wedge-shaped material configured to propagate the ultrasonic wave transmitted from the first ultrasonic wave element and including a first incident / emitting surface inclined with respect to a propagation direction of the ultrasonic wave and emitting the propagated ultrasonic wave; a first elastic coupling medium including a first tube contact portion in contact with the tube and configured to cause an ultrasonic wave emitted from the first incident / emitting surface of the first wedge-shaped material to propagate to the tube via the first tube contact portion; a first clamping member configured to support the tube and the first elastic coupling medium and to arrange the first tube contact portion along an axial direction of the tube; a first damping material arranged to attenuate ultrasonic waves and surrounding the first tube contacting portion of the first elastic coupling medium between the first clamping member and the tube; a second ultrasonic element configured to transmit and receive ultrasonic waves between the second ultrasonic element and the first ultrasonic element through the tube; a second wedge-shaped material configured to propagate the ultrasonic wave transmitted from the second ultrasonic wave element and including a second incident / emitting surface inclined with respect to the propagation direction of the ultrasonic wave and emitting the propagated ultrasonic wave; a second elastic coupling medium including a second tube contact portion in contact with the tube and configured to cause the ultrasonic wave emitted from the second incident / emitting surface of the second wedge-shaped material to propagate to the tube via the second tube contact portion; a second clamping member configured to support the tube and the second elastic coupling medium and to arrange the second tube contact portion along the axial direction; a second damping material arranged to attenuate ultrasonic waves and surrounding the second tube contacting portion of the second elastic coupling medium between the second clamping member and the tube; as well as a flow rate calculation section configured to calculate a flow rate of a fluid flowing in the pipe based on ultrasonic waves transmitted and received between the first ultrasonic element and the second ultrasonic element, wherein The outer diameter of the tube is greater than or equal to 2 mm and less than or equal to 20 mm, The first tube contact portion has a first width along a width direction orthogonal to the axial direction, the first width being narrower than a width of the first ultrasonic element along the width direction, The second tube contact portion has a second width along the width direction, the second width being narrower than a width of the second ultrasonic element along the width direction, and The first clamping member and the second clamping member are connected to each other to clamp the tube in a state where the first clamping member presses the first damping material and the second clamping member presses the second damping material, The clamp-on ultrasonic flow sensor further comprises: a first pressing member mounted to the first clamping member and configured to press the first damping material against the tube; and A second pressing member is mounted to the second clamping member and is configured to press the second damping material against the tube.

2. The clamp-on ultrasonic flow sensor according to claim 1, characterized in that: The first pressing member is a first thin leaf spring whose two ends in the circumferential direction are arc-shaped cantilevered relative to the fixed portion mounted to the first clamping member, and the first pressing member also presses the first damping material against the tube in a direction different from the clamping direction of the first clamping member and the second clamping member, and The second pressing member is a second thin leaf spring, both ends of which in the circumferential direction are arc-shaped cantilevered relative to the fixed part mounted to the second clamping member, and the second pressing member also presses the second damping material against the tube in a direction different from the clamping direction of the first clamping member and the second clamping member.

3. The clamp-on ultrasonic flow sensor according to claim 2, characterized in that: The first thin leaf spring has a semi-cylindrical shape and is arranged to surround the entire circumference of the tube and pressurize the first damping material, and The second thin leaf spring has a semi-cylindrical shape and is arranged to surround the entire circumference of the tube and pressurize the second damping material.

4. The clamp-on ultrasonic flow sensor according to claim 1, characterized in that: A space for allowing the first damping material and the second damping material to deform is formed between the first clamping member and the tube and between the second clamping member and the tube.

5. The clamp-on ultrasonic flow sensor according to claim 1, characterized in that: The first damping material and the second damping material are formed of an elastomer.

6. The clamp-on ultrasonic flow sensor according to claim 5, characterized in that: The first pressing member is configured to maintain the position and posture of the first elastic coupling medium, and The second pressing member is configured to maintain a position and a posture of the second elastic coupling medium.

7. The clamp-on ultrasonic flow sensor according to claim 5, characterized in that: The first pressurizing member includes a third slit extending along the axial direction, the first tube contact portion of the first elastic coupling medium being fitted into the third slit, and The second pressurizing member includes a fourth slit extending along the axial direction, and the second tube contact portion of the second elastic coupling medium is fitted into the fourth slit.

8. The clamp-on ultrasonic flow sensor according to claim 1, characterized in that: At least one of the first clamping member and the second clamping member includes a guide wall that guides the clamping member to the tube when the clamping member supports the tube.

9. The clamp-on ultrasonic flow sensor according to claim 1, characterized in that: The peripheral wall of the tube includes a first excitation region and a second excitation region, the longitudinal wave of the ultrasonic wave emitted from the first incident / emission surface of the first wedge-shaped material collides with the first excitation region, and the longitudinal wave of the ultrasonic wave emitted from the second incident / emission surface of the second wedge-shaped material collides with the second excitation region, The first excitation region of the tube excites ultrasonic waves that pass through the fluid flowing in the tube and travel to the second ultrasonic element, and The second excitation region of the tube excites ultrasonic waves that pass through the fluid flowing in the tube and travel to the first ultrasonic element.

10. The clamp-on ultrasonic flow sensor according to claim 9, characterized in that: The first damping material is mounted to the tube and surrounds the first excitation region, and The second damping material is mounted to the tube and surrounds the second excitation region.

11. The clamp-on ultrasonic flow sensor according to claim 1, characterized in that: The first wedge-shaped material is provided so that the incident angle of the shear wave of the ultrasonic wave transmitted from the first ultrasonic element with respect to the axial direction is set to be equal to or greater than a critical angle, and The second wedge-shaped material is provided so that an incident angle of a shear wave of ultrasonic waves transmitted from the second ultrasonic element with respect to the axial direction is set to be equal to or greater than the critical angle.

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