Ultrasonic flowmeter and method for assembling ultrasonic flowmeter

Abstract

To provide an ultrasonic flowmeter with which the fitting region of an ultrasonic sensor and a measurement tube can easily be made to be a sealed structure.SOLUTION: An ultrasonic flowmeter 1 comprises: a measurement tube 2 having a flow path 9 in which a fluid flows; at least a pair of sensor units 7 for accommodating an ultrasonic sensor 5, located on the upper and lower sides of the flow path, and provided on an outer wall of the measurement tube to enable transmission and reception of an ultrasonic signal; an arithmetic processing unit 6 provided on the outside of the measurement tube, for computing the flow rate of the fluid on the basis of a propagation time between ultrasonic sensors; a piping 20 provided on the outside of the measurement tube, for inserting a connection line 47 therein to electrically connect the ultrasonic sensor and the arithmetic processing unit; and a cover member 8 for covering a fitting region 30 of the sensor units and the measurement tube. The cover member is undetachably secured to the measurement tube in a state of covering the fitting region by connection of the piping to the sensor units.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an ultrasonic flow meter and a method for assembling an ultrasonic flow meter. [Background technology]

[0002] Conventionally, ultrasonic flowmeters that measure the flow rate of a fluid passing through a measuring pipe are known. For example, the ultrasonic flowmeter described in Patent Document 1 transmits and receives ultrasonic waves between a pair of ultrasonic sensors attached to the upstream and downstream sides of a measuring pipe through which a fluid flows. The ultrasonic flowmeter measures the flow velocity based on the difference between the propagation time from the upstream side to the downstream side and the propagation time from the downstream side to the upstream side, and is able to measure the flow rate of the fluid passing through the measuring pipe using the cross-sectional area of ​​the flow path.

[0003] Furthermore, the ultrasonic flowmeter has a sensor case that houses the ultrasonic sensor, a flow rate calculation and display unit, and piping that electrically connects the ultrasonic sensor and the flow rate calculation and display unit. The flow rate calculation and display unit calculates and displays the flow rate based on the signal received from the ultrasonic sensor. The piping has a connection line inside that connects to the ultrasonic sensor, which is drawn from the sensor case to the outside of the measuring pipe and connected to the display unit. The sensor case is fixed to the outer wall of the measuring pipe with multiple bolts.

[0004] Generally, in the ultrasonic flowmeter, a sealing structure is used to prevent the sensor case from being removed, for example, to prevent a user from maliciously removing the ultrasonic sensor from the measuring pipe and temporarily immobilizing the flowmeter. Specific sealing structures include a structure in which a horizontal hole is drilled in the head of a bolt, a wire is passed through the horizontal hole, and then a lead ball is used to secure the sensor case, a structure in which a resin cap is press-fitted onto the head of the bolt, and a structure in which the entire sensor case is sealed by welding. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2011-33389 Summary of the Invention [Problem to be solved by the invention]

[0006] However, in any of the above-mentioned ultrasonic flowmeters, there is a problem in that the work efficiency is low because it takes time to pass the wire and to crimp the lead ball for sealing, regardless of the sealing structure.

[0007] SUMMARY OF THE INVENTION In view of the above problems, the present invention provides an ultrasonic flowmeter that can easily provide a sealed structure at the attachment portion between the ultrasonic sensor and the measuring pipe. [Means for solving the problem]

[0008] (1) To achieve the above-mentioned object, according to one aspect of the present disclosure, there is provided an ultrasonic flowmeter comprising: a measuring pipe having a flow path through which a fluid flows; at least one pair of sensor units accommodating ultrasonic sensors, the sensor units being located on the upstream and downstream sides of the flow path and being provided on the outer wall of the measuring pipe so as to be capable of transmitting and receiving ultrasonic signals; a processing unit provided outside the measuring pipe and calculating the flow rate of the fluid based on the propagation time between the ultrasonic sensors; a pipe provided outside the measuring pipe and through which a connecting wire electrically connecting the ultrasonic sensor and the processing unit is inserted; and a cover member connected to the pipe and fixed to the measuring pipe so as to cover an attachment portion between the sensor unit and the measuring pipe and unremovably attached thereto.

[0009] According to this type of ultrasonic flowmeter, when the pipe is connected to the sensor unit, the cover member is fixed to the measurement pipe in an unremovable manner, covering the attachment portion between the sensor unit and the measurement pipe. Therefore, by attaching the cover member to the attachment portion and then connecting the pipe to the sensor unit, the attachment portion of the sensor unit to the measurement pipe can be easily sealed. This effectively prevents, for example, malicious user actions such as removing the ultrasonic sensor from the measurement pipe to temporarily immobilize the flowmeter. Furthermore, if an attempt were made to remove the sensor unit, the pipe or cover member connected to the sensor unit would have to be destroyed, leaving traces of the destruction.

[0010] (2) In the ultrasonic flowmeter of the above form, the sensor unit has a sensor case having a connection portion having a first opening into which the piping is inserted and a storage portion that stores the ultrasonic sensor, and the cover member has a first cover portion that covers the mounting location and a second cover portion that is formed integrally with the first cover portion, covers the connection portion, and has a second opening into which the piping is inserted, and the cover member may be fixed to the measuring pipe by the piping inserted into the second cover portion and the connection portion through the second opening and the first opening and connecting to the connection portion.

[0011] According to this ultrasonic flowmeter, a pipe is inserted into the second cover part through the first opening and the second opening, and the pipe is connected to the connecting part of the sensor case. By inserting the pipe into the opening of the second cover part, the cover member can be prevented from coming off the sensor case. In other words, because the second cover part has a retaining effect, the cover member attached to the sensor part can be easily fixed by connecting the pipe to the connecting part.

[0012] (3) In the ultrasonic flowmeter of the above aspect, the sensor unit may be fixed to the measuring pipe by attaching the housing of the sensor case to a mounting hole provided in the measuring pipe, the cover member may cover the sensor case from a direction intersecting the axial direction of the measuring pipe, and the piping may be provided from the connection part to the arithmetic processing unit along the outer periphery of the measuring pipe. According to the ultrasonic flowmeter of this aspect, the cover member can be attached to the sensor case from a direction intersecting the axial direction of the measuring pipe with respect to the sensor unit fixed to the mounting hole of the measuring pipe, thereby facilitating the assembly work.

[0013] (4) In the ultrasonic flowmeter of the above aspect, the sensor case may be fixed to the measuring pipe by a bolt, and the first cover part may cover the mounting part including the head of the bolt. According to the ultrasonic flowmeter of this aspect, by covering the head of the bolt with the first cover part, the mounting part can be easily sealed.

[0014] (5) The ultrasonic flowmeter of the above aspect may further include a coupling member connected to the connection part, and the piping and the connection part may be fastened by screwing together threaded portions formed on the coupling member and the connection part. According to this aspect of the ultrasonic flowmeter, the piping can be easily connected to the sensor case via the coupling member that is connected to the connection part by screwing together the threaded portions.

[0015] (6) The ultrasonic flowmeter of the above aspect may further include a joint cover that entirely covers the joint member. According to this aspect of the ultrasonic flowmeter, the joint member, which is the connection portion between the sensor unit and the piping, is entirely covered by the joint cover, thereby providing a stronger sealing structure than when there is no joint cover. This makes it possible to more effectively prevent attempts to remove the joint from the cover member.

[0016] (7) According to a second aspect of the present disclosure, there is provided a method for assembling an ultrasonic flowmeter, the method comprising: a measuring pipe having a flow path through which a fluid flows; at least one pair of sensor units accommodating ultrasonic sensors, the sensor units being located upstream and downstream of the flow path and being attached to the outer wall of the measuring pipe so as to be able to transmit and receive ultrasonic signals; a processing unit provided outside the measuring pipe and configured to calculate a flow rate of the fluid based on a propagation time between the ultrasonic sensors; a pipe provided outside the measuring pipe and having a connecting wire passing through it that electrically connects the ultrasonic sensors to the processing unit; and a cover member that is connected to the pipe and is fixed to the measuring pipe so as to cover an attachment site between the sensor unit and the measuring pipe and cannot be removed therefrom; the method comprises the steps of: attaching the sensor unit to the measuring pipe; attaching the cover member to the attachment site so as to cover the attachment site; and connecting the pipe to the sensor unit with the cover member attached thereto.

[0017] According to the method for assembling an ultrasonic flowmeter of the above aspect, the attachment portion between the sensor unit and the measuring pipe is covered with the cover member in the cover member assembling step, and the cover member is fixed to the measuring pipe in an unremovable state from the state where it covers the attachment portion in the piping connecting step. Therefore, by simply adding the simple step of assembling the cover member to the sensor unit, the attachment portion can be easily sealed. [Effects of the Invention]

[0018] According to the ultrasonic flowmeter of the present invention, it is possible to provide an ultrasonic flowmeter in which the attachment portion between the ultrasonic sensor and the measuring pipe can be easily sealed. [Brief explanation of the drawings]

[0019] [Figure 1] 1 is a perspective view of an ultrasonic flowmeter according to a first embodiment of the present invention. [Figure 2] FIG. 1 is a front view of an ultrasonic flow meter. [Figure 3]FIG. 1 is a side view of an ultrasonic flow meter. [Figure 4] FIG. 4 is a cross-sectional view of the ultrasonic flowmeter taken along line IV-IV in FIG. 3. [Figure 5] FIG. 5 is an enlarged view of a part of FIG. 4, mainly showing a cross-sectional view of a sensor portion. [Figure 6] FIG. [Figure 7] FIG. [Figure 8] FIG. 2 is a perspective view of the sensor case as seen from the bottom. [Figure 9] FIG. [Figure 10] FIG. 2 is a perspective view of the cover member as seen from the bottom. [Figure 11] FIG. [Figure 12] FIG. 4 is an enlarged perspective view showing a connection portion between the cover member and the pipe. [Figure 13] FIG. 10 is a front view showing a state in which the sensor unit is attached to the measurement pipe, and shows a state before the cover member is attached. [Figure 14] FIG. 4 is a front view of an ultrasonic flowmeter according to a second embodiment of the present invention. [Figure 15] FIG. [Figure 16] FIG. 2 is a perspective view of the cover member as seen from the bottom. [Figure 17] FIG. 10 is a perspective view of a cover member in another embodiment. [Figure 18] FIG. 10 is a perspective view of a cover member in another embodiment. [Figure 19] FIG. 10 is an enlarged perspective view showing a connection portion between a cover member and a pipe in another embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0020] Hereinafter, several embodiments will be described with reference to the drawings. First Embodiment An ultrasonic flowmeter 1 according to a first embodiment of the present invention will be described with reference to FIGS. [Overall configuration of ultrasonic flowmeter 1] As shown in FIGS. 1 and 2, the ultrasonic flowmeter 1 of the first embodiment includes a measuring pipe 2, a flow rate calculation and display unit 6, a sensor unit 7, a pipe 20, and a cover member 8.

[0021] The measuring tube 2 is a cylindrical member, and is made of metal such as stainless steel. The measuring tube 2 is open at both ends in the direction in which the central axis X extends (hereinafter simply referred to as the "central axis X direction"). A cylindrical flow path 9 is formed inside the measuring tube 2, connecting both ends in the central axis X direction. A fluid to be measured flows through the flow path 9. The inner diameter of the flow path 9 is formed to be approximately the same over the entire length in the central axis X direction.

[0022] Flanges 10 are provided at both ends of the measuring pipe 2, protruding radially outward from the measuring pipe 2. A plurality of through holes 10a are formed in each flange 10 at appropriate intervals in the circumferential direction centered on the central axis X of the flow path 9. A feed pipe (not shown) for circulating a fluid is connected to the outer side of each flange 10 in the direction of the central axis X. Then, bolts are inserted through the through holes 10b of the flanges 10 and through holes provided in the feed pipe, and the bolts are screwed together with nuts, thereby connecting the measuring pipe 2 and the feed pipe.

[0023] Depending on the arrangement of the connected feed pipe, the direction of the central axis X of the flow path 9 can be positioned in any direction, such as vertically or horizontally. Also, by changing the mutual connection position between the through hole 10b of the flange 10 and the through hole of the feed pipe, the mounting angle of the ultrasonic flowmeter 1 in the circumferential direction relative to the feed pipe can be changed.

[0024] As shown in Figures 3 and 4, a pair of sensor units 7 are provided on the upstream and downstream sides of the measuring pipe 2. The pair of sensor units 7 are provided such that an imaginary line Y (see Figure 4) connecting the axes of the ultrasonic sensors 5 of the sensor units 7 is positioned on a straight line inclined with respect to the direction of the central axis X. In other words, ultrasonic waves can be transmitted and received between the pair of ultrasonic sensors 5 of the pair of sensor units 7 in a direction diagonally intersecting the central axis X of the flow path 9. The flow rate of the fluid passing through the flow path 9 can be measured based on the propagation time of the ultrasonic signal between the ultrasonic sensors 5 from the upstream side to the downstream side and the propagation time of the ultrasonic wave between the ultrasonic sensors 5 from the downstream side to the upstream side.

[0025] As shown in Fig. 6, a mounting hole 11 for mounting the display base 6a of the flow rate calculation display unit 6 is formed in the peripheral wall of the measuring pipe 2. In addition, two mounting portions 12 for mounting the sensor unit 7 are provided in the peripheral wall of the measuring pipe 2. One mounting portion 12 is provided at the upstream side and one at the downstream side in the direction of the central axis X of the measuring pipe 2, and the mounting portions 12 are provided at positions 180 degrees apart in the circumferential direction of the measuring pipe 2. In other words, when the sensor unit 7 is mounted to each mounting portion 12, one ultrasonic sensor 5 is located upstream of the flow path 9, and the other ultrasonic sensor 5 is located downstream of the flow path 9. The two ultrasonic sensors 5 are capable of transmitting and receiving waves to and from each other.

[0026] The mounting portion 12 has a cylindrical mounting hole 12a that penetrates the inside and outside of the measuring pipe 2, formed so that the central axis Z of this mounting hole 12a and the central axis X of the measuring pipe 2 are perpendicular to each other. A mounting surface 12c is formed on the outer surface of the mounting portion 12. The mounting surface 12c is perpendicular to the central axis Z of the mounting hole 12a and forms a flat surface that is annular in plan view. Four female threads 12d are formed on this mounting surface 12c at appropriate intervals in the circumferential direction centered on the central axis Z of the mounting hole 12a.

[0027] A positioning portion 13 is provided on the mounting surface 12c at a position closer to the center in the direction of the central axis X of the measuring pipe 2, protruding from the mounting surface 12c outward in the radial direction of the measuring pipe 2. The outer peripheral surface of the positioning portion 13 is arc-shaped with its center on the central axis Z of the mounting hole 12a, and the inner surface is flat.

[0028] Referring again to Figures 1 to 3, the flow rate calculation display unit 6 is capable of calculating and displaying the flow rate based on the signal received from the ultrasonic sensor 5 on the receiving side. The flow rate calculation display unit 6 corresponds to an example of a "calculation processing unit." In this embodiment, as shown in Figures 1 to 3, an example is shown in which the flow rate calculation display unit 6 is disposed so that the central axis X direction of the flow path 9 coincides with the horizontal direction and the axial direction of the display base 6a of the flow rate calculation display unit 6 is positioned in the vertical direction. In other words, the flow rate calculation display unit 6 is positioned above the measuring pipe 2. Furthermore, the angle θ of the line connecting the axes of the ultrasonic sensors 5 with the horizontal direction is 22.5 degrees (see Figure 3).

[0029] [Configuration of sensor unit 7] Next, the configuration of the sensor unit 7 will be described with reference to Figures 4, 5, 7, and 8. As shown in Figures 4 and 5, the sensor unit 7 has a sensor case 3, a sensor bracket 4, and an ultrasonic sensor 5. The ultrasonic sensor 5 has a transmitting and receiving surface 41 at one end for transmitting and receiving ultrasonic waves, and this transmitting and receiving surface 41 is provided in a position that is substantially aligned with the outer wall of the measuring pipe 2. In the following description, for convenience, the top in Figure 5 may be referred to as "top" and the bottom in Figure 5 may be referred to as "bottom."

[0030] As shown in Figure 5, the sensor bracket 4 is integrally molded from resin and holds the ultrasonic sensor 5 inside. An elastic member 42 is disposed between the outer periphery of the ultrasonic sensor 5 and the arm portion 38 of the sensor bracket 4. In other words, the ultrasonic sensor 5 is not in direct contact with the sensor bracket 4. The ultrasonic sensor 5 and the elastic member 42 are held within the sensor bracket 4.

[0031] A lead wire 46 connected to the ultrasonic sensor 5 protrudes from the back surface 5a of the ultrasonic sensor 5. The tip of this lead wire 46 is connected to the terminal 32 of the sensor bracket 4. The terminal 32 and the flow rate calculation display unit 6 are connected by a connection wire 47 arranged inside the piping 20. The piping 20 has a joint 21 and a shield tube 24. The joint 21 is fixed to both ends of the piping 20 and has a male thread 21b on its outer periphery. The joint 21 on the sensor unit 7 side is connected to the sensor unit 7. The joint 21 on the flow rate calculation display unit 6 side is connected to the flow rate calculation display unit 6. The shield tube 24 is connected between the joints 21 on both ends. The joint 21 corresponds to an example of a "joint member".

[0032] [Configuration of Sensor Case 3] The sensor case 3 is made of metal such as stainless steel, and as shown in Fig. 7, has a cylindrical portion 15, an attachment portion 16, a neck portion 17, and a connection portion 18. The cylindrical portion 15, the attachment portion 16, the neck portion 17, and the connection portion 18 are integrally configured so that they are closer to the central axis X of the measurement pipe 2 in that order when the sensor case 3 is attached to the measurement pipe 2.

[0033] As shown in FIGS. 4, 5, and 8, the cylindrical portion 15 is formed into a cylindrical shape with a circular cross section. The outer diameter R1 of the cylindrical portion 15 is set to be the same as or slightly smaller than the inner diameter R2 of the mounting hole 12a of the mounting portion 12 of the measurement pipe 2. A groove 15a (see FIG. 5) for fitting an O-ring 55 is formed in the base of the cylindrical portion 15 on the mounting portion side, over the entire circumferential direction. The surface of the cylindrical portion 15 facing the central axis X of the measurement pipe 2 is formed into an inclined surface 15b (see FIG. 8) that inclines toward the central axis X of the measurement pipe 2 from the inside toward the outside in the direction of the central axis X of the measurement pipe 2. Two mounting holes 15c for mounting the sensor bracket 4 are provided near the periphery of the inclined surface 15b, spaced approximately 180 degrees apart in the circumferential direction, as shown in FIG. 8. A female thread is formed in the mounting hole 15c.

[0034] A flange-shaped mounting portion 16 is integrally formed at the base of the cylindrical portion 15, perpendicular to the axis C (see FIG. 7) of the cylindrical portion 15 and protruding outward from the cylindrical portion 15. As shown in FIG. 7, the mounting portion 16 has an outer surface formed in a substantially circular flat plate shape, and the outer diameter of the mounting portion 16 and the outer diameter of the mounting surface 12c of the mounting portion 12 of the measuring pipe 2 are set to be substantially the same. A notch 16a is formed by cutting out part of the outer periphery of the mounting portion 16 in a portion that corresponds to the positioning portion 13 of the mounting portion 12 of the measuring pipe 2.

[0035] When attaching the sensor case 3 to the attachment part 12 of the measuring pipe 2, the notch 16a is brought into contact with the inner surface of the positioning part 13, thereby enabling the sensor case 3 to be positioned relative to the attachment part 12. A flat attachment surface 16c that is perpendicular to the axis C of the cylindrical part 15 is formed on the cylindrical part 15 side of the attachment part 16.

[0036] A passage 26 (see FIG. 5) that communicates with the outside is formed in the peripheral wall of the tubular portion 15. The opening on the outside side of the passage 26 opens into the flow path 9 when the sensor case 3 is attached to the measurement pipe 2. In other words, the passage 26 connects the inside of the storage portion 19 (sensor bracket 4) of the sensor case 3 with the inside of the flow path 9 of the measurement pipe 2. The tubular portion 15 corresponds to an example of a "storage portion" that stores the ultrasonic sensor 5.

[0037] 7 and 8 again. Four through holes 16b are formed in the mounting portion 16 at positions corresponding to the female threads 12d on the mounting surface 12c of the measurement pipe 2. When assembling the sensor portion 7 to the measurement pipe 2, bolts 51 (see FIGS. 5 and 13) are inserted into the through holes 16b, and the bolts 51 are screwed into the female threads 12d on the mounting surface 12c of the measurement pipe 2. In this way, the sensor case 3 is fixed to the measurement pipe 2 in a direction perpendicular to the direction of the central axis X of the flow path 9.

[0038] The "mounting portion 30 between the sensor unit 7 and the measurement pipe 2" is configured to include the through hole 16b, the bolt 51, and the female thread 12d on the mounting surface 12c of the measurement pipe 2. However, in this embodiment, the "mounting portion 30" when "covering the mounting portion 30" refers only to the head of at least one bolt 51 that is to be operated when the sensor unit 7 is removed from the measurement pipe 2, for example, during maintenance by an authorized contractor. The method of assembling the sensor unit 7 to the measurement pipe 2 will be described in detail later.

[0039] The neck portion 17 is provided radially outward from the central axis X of the measurement pipe 2 in the mounting portion 16. As shown in Fig. 5, a storage portion 19 capable of storing the sensor bracket 4 is formed inside the cylindrical portion 15, the mounting portion 16, and the neck portion 17. The storage portion 19 has an opening 19a on the side of the inclined surface 15b of the cylindrical portion 15, and is formed with a bottom having a wall 22a at the back end opposite the inclined surface 15b. As shown in Fig. 5, the axis F of the storage portion 19 is inclined with respect to the axis C of the cylindrical portion 15.

[0040] The connecting portion 18 is provided on the neck portion 17 radially outward from the central axis X of the measuring pipe 2 (upper side in FIG. 5 ). As shown in FIG. 7 , the connecting portion 18 has a large-diameter connecting portion 61 and a small-diameter connecting portion 62. The large-diameter connecting portion 61 is cylindrical and has a central axis L parallel to the central axis Z of the mounting hole 12a. The end of the large-diameter connecting portion 61 on the axial side of the tubular portion 15 is connected to the neck portion 17. The small-diameter connecting portion 62 is cylindrical and has a smaller diameter than the large-diameter connecting portion 61 and has a central axis M parallel to the central axis X. The central axis L of the large-diameter connecting portion 61 and the central axis M of the small-diameter connecting portion 62 are perpendicular to each other. Note that these central axes L and M do not necessarily have to be perpendicular to each other. The small diameter connecting part 62 protrudes in a direction parallel to the central axis X of the measuring pipe 2 (toward the notch 16a) from the end (upper end in FIG. 5) of the large diameter connecting part 61 opposite the neck part 17 in the axial direction. The large diameter connecting part 61 and the small diameter connecting part 62 are internally connected, and a space 22 is formed therein.

[0041] A first opening 62a for inserting the fitting 21 of the pipe 20 is formed at the protruding end of the small diameter connecting portion 62 opposite to the large diameter connecting portion 61. The first opening 62a is circular. The first opening 62a communicates with the space 22. A female thread 62b (see FIG. 5) that screws into the male thread 21b provided on the fitting 21 is engraved on the inner wall of the small diameter connecting portion 62 for a predetermined length from the open end of the first opening 62a inward.

[0042] A hole 61c that connects the space 22 to the outside is formed in the end of the large diameter connecting part 61 opposite the cylindrical part 15 along the axial direction of the large diameter connecting part 61. The hole 61c is a work hole for connecting the connection wire 47 and the terminal 35, and after assembly, a lid 52 (see FIG. 5) fits into the hole 61c. Two mounting holes (not shown) for mounting the terminal 35 are formed in the wall 22a (see FIG. 5) facing the hole 61c on the inside of the space 22. The mounting holes connect the space 22 to the inside of the storage part 19.

[0043] [Configuration of cover member 8] Next, the configuration of the cover member 8 will be described with reference to FIGS. 9 to 11. The cover member 8 is a container-like member for covering the attachment portion 30 of the sensor unit 7 and the measurement tube 2, and has an outer shape corresponding to the outer shape of the sensor case 3. A bottom opening 67 is formed on one side (the lower side in FIG. 9) of the cover member 8. The cover member 8 is placed over the entire sensor case 3 from the connection portion 18 side of the sensor case 3, thereby covering the entire sensor case 3 except for the tubular portion 15, i.e., the connection portion 18, the neck portion 17, and the attachment portion 16. The cover member 8 is integrally molded from, for example, resin, highly hard rubber that is difficult to deform, or a metal material such as aluminum. It can be manufactured by various methods, including aluminum die casting and sheet metal.

[0044] The cover member 8 includes a first cover portion 65 and a second cover portion 66. The first cover portion 65 and the second cover portion 66 are internally connected. The first cover portion 65 is substantially cylindrical and has the bottom opening 67 at one axial end (the lower end in FIG. 9 ) and an upper bottom portion 68 at the other axial end (the upper end in FIG. 9 ). A space 69 (see FIG. 10 ) capable of accommodating the neck portion 17 and the mounting portion 16 of the sensor case 3 is formed inside the first cover portion 65. The first cover portion 65 mainly covers the neck portion 17 and the mounting portion 16 of the sensor case 3. In other words, the first cover portion 65 covers the heads of the multiple bolts 51 that secure the sensor case 3 to the measuring pipe 2. Therefore, the user cannot see the bolts 51 from the outside.

[0045] The second cover part 66 covers the connection part 18 of the sensor case 3. The outer shape of the second cover part 66 corresponds to the outer shape of the connection part 18 of the sensor case 3. The second cover part 66 is provided to protrude from the other side of the first cover part 65. The first cover part 65 and the second cover part 66 are molded integrally and are internally connected. The second cover part 66 has a large diameter cover part 71 and a small diameter cover part 72. One ends of the large diameter cover part 71 and the small diameter cover part 72 are connected to the upper bottom part 68 of the first cover part 65. The other end of the large diameter cover part 71 is cylindrical with a bottom and has a central axis N parallel to the central axis Z.

[0046] The small diameter cover portion 72 is substantially cylindrical with a smaller diameter than the large diameter cover portion 71, and has a central axis P parallel to the central axis X. The central axis N of the large diameter cover portion 71 and the central axis P of the small diameter cover portion 72 are perpendicular to each other. Note that these central axes N and P do not necessarily have to be perpendicular to each other. The small diameter cover portion 72 protrudes from the outer peripheral surface of the large diameter cover portion 71 in a direction parallel to the central axis X of the measuring pipe 2. The large diameter cover portion 71 and the small diameter cover portion 72 are internally connected, and the second cover portion 66 as a whole defines a space 73 inside which the connection portion 18 of the sensor case 3 can be accommodated.

[0047] A second opening 72a for inserting the fitting 21 of the pipe 20 is formed in the protruding end of the small diameter cover portion 72 opposite to the large diameter cover portion 71. The second opening 72a is circular. The opening diameter of the second opening 72a is slightly larger than the opening diameter of the first opening 62a. When the cover member 8 is attached to the sensor case 3, the inner surface of the wall portion 74 forming the outer peripheral wall of the second opening 72a faces the protruding tip surface 63 (see FIG. 7) of the small diameter connecting portion 62. The first opening 62a of the sensor case 3 and the second opening 72a of the cover member 8 are positioned substantially in the same position.

[0048] Therefore, with the cover member 8 covering the sensor case 3, the joint 21 of the pipe 20 can be inserted into the second opening 72a and the first opening 62a. When the joint 21 of the pipe 20 is inserted into the second opening 72a and the first opening 62a and connected by threaded engagement of the screws 21b, 62b, the joint 21 prevents the cover member 8 from being removed from the sensor case 3. In other words, the engagement between the outer periphery of the joint 21 and the second opening 72a prevents the cover member 8 from coming off.

[0049] When the cover member 8 is placed over the sensor case 3, the cover member 8 and the sensor case 3 are removably engaged with each other. In other words, even before connection with the joint 21, when the cover member 8 is placed over the sensor case 3, the cover member 8 is engaged to the extent that it will not easily come off the sensor case 3, even if the sensor case 3 is turned upside down with the cover member 8 on the bottom. After the joint 21 is connected, the cover member 8 cannot be removed from the sensor case 3 unless the joint 21 is turned again in the opposite direction to the attachment to release the threaded engagement and remove the joint 21 from each of the openings 62a, 72a. The threads 21b and the female threads 62b of the joint 21 correspond to an example of a "threaded portion."

[0050] The wall portion 74 of the small diameter cover portion 72 is inclined in a direction away from the central axis N of the large diameter cover portion 71 as it approaches the first cover portion 65. In other words, while the tip surface 63 of the small diameter connecting portion 62 that forms the first opening 62a is a vertical wall surface, the wall portion 74 of the small diameter cover portion 72 is inclined, which makes it easier to attach the cover member 8 to the sensor case 3.

[0051] A slit 75 is provided in the wall portion 74 that forms the outer peripheral wall of the second opening 72a. The slit 75 extends continuously from the lower edge of the second opening 72a to the outside in the radial direction of the second opening 72a (toward the first cover portion 65, that is, the lower side in FIG. 9 ), but is formed to a length that does not reach the first cover portion 65. This slit 75 is for temporarily receiving the connection wire 47 extending from the first opening 62a of the sensor case 3 when attaching the cover member 8 to the sensor case 3, and is intended to facilitate the assembling operation of the cover member 8. The assembling process will be described in detail later.

[0052] [How to assemble the ultrasonic flowmeter 1] Next, we will explain the method for assembling the ultrasonic flowmeter 1 described in detail above. The assembly method includes a sensor unit mounting step of mounting the sensor unit 7 to the measuring pipe 2, a cover member assembling step of assembling the cover member 8 to the mounting site 30 so as to cover the mounting site 30 between the sensor unit 7 and the measuring pipe 2, and a piping connection step of connecting the piping 20 to the sensor unit 7 with the cover member 8 mounted thereto. This will be explained in more detail below.

[0053] First, the elastic member 42 is fitted onto the periphery of the ultrasonic sensor 5. Next, the ultrasonic sensor 5 together with the elastic member 42 is engaged with the groove in the arm portion 38 of the sensor bracket 4 and housed within the sensor bracket 4. Next, the lead wires 46 of the ultrasonic sensor 5 are soldered to the terminals 32 to establish electrical continuity.

[0054] Next, with the sensor case 3 not attached to the measuring pipe 2, the sensor bracket 4 is stored in the storage section 19 from the terminal 32 side through the opening 19a of the sensor case 3. Then, the insulating rubber of the airtight terminal 35 is fitted into the mounting hole in the wall 22a, and the terminal 32 is made to protrude from the mounting hole in the direction opposite to the storage section 19.

[0055] Next, a bolt is inserted through a hole formed in the sensor bracket 4 and into the mounting hole 15c of the sensor case 3, and is screwed into the female thread in the mounting hole 15c to secure the sensor bracket 4 to the sensor case 3. In other words, the ultrasonic sensor 5 is secured to the sensor case 3. Through the above steps, the ultrasonic sensor 5, sensor bracket 4, and sensor case 3 are assembled into a unit.

[0056] Next, an O-ring 55 (see FIG. 5) is fitted into the groove 15a of the sensor case 3. Next, the unitized sensor case 3 is attached to the measurement pipe 2. Specifically, first, from the outside of the measurement pipe 2, the cylindrical portion 15 of the sensor case 3 is fitted into the mounting hole 12a of the mounting portion 12 of the measurement pipe 2 in a direction perpendicular to the central axis X of the measurement pipe 2. Then, the outer surface of the notch 16a of the mounting portion 16 of the sensor case 3 is brought into contact with the inner surface of the positioning portion 13, and the mounting surface 16c of the mounting portion 16 is brought into contact with the mounting surface 12c of the mounting portion 12.

[0057] Next, a bolt 51 (see Figures 5 and 13) is inserted into the through hole 16b of the mounting portion 16 of the sensor case 3, and the bolt 51 is screwed into the female thread 12d of the mounting surface 12c of the measuring pipe 2, thereby fixing the set of sensor cases 3 to the measuring pipe 2 in a direction perpendicular to the central axis X.

[0058] Next, the display base 6a of the flow rate calculation display unit 6 is attached to the mounting hole 11 of the measuring pipe 2. Next, using the hole 61c as a working hole, one end of the connection wire 47 is soldered to the terminal 32, and the lid 52 is fitted into the hole 61c. The connection wire 47 is pulled out to the outside from the first opening 62a of the small diameter connection part 62.

[0059] Next, the cover member 8 is attached to the sensor case 3. First, the connection line 47 is pulled out from the first opening 62a of the small diameter connection portion 62 and inserted through the bottom opening 67 of the cover member 8 into the second opening 72a. Then, with the connection line 47 hooked into the slit 75, the cover member 8 is placed over the sensor case 3 so as to cover the entire sensor case 3 from the connection portion 18 onwards. As a result, the connection portion 18 of the sensor case 3 is housed in the space 73 within the second cover portion 66, and the neck portion 17 and the mounting portion 16 of the sensor case 3 are housed in the space 69 within the first cover portion 65. When the cover member 8 is placed over the sensor case 3, the central axis L of the large diameter connection portion 61 and the central axis N of the large diameter cover portion 71 are approximately aligned.

[0060] When the sensor case 3 is placed over the cover member 8, a small gap is formed between the outer wall of the inclined neck portion 17 and the inner wall of the wall portion 74 of the small diameter cover portion 72. A gap is also formed between the inner surface of the upper bottom portion 68 of the first cover portion 65 and the upper surface 16d of the mounting portion 16.

[0061] After attaching the cover member 8 to the sensor case 3, with the connection line 47 inserted into the joint 21 of the piping 20, the joint 21 is inserted into the second opening 72a of the cover member 8 and the first opening 62a of the small diameter connecting portion 62. Then, the male thread 21b of the joint 21 is screwed into the female thread 62b of the small diameter connecting portion 62 to connect the joint 21 to the connecting portion 18. By connecting the joint 21 to the connecting portion 18, the cover member 8 is fixed to the sensor case 3. Next, the shield tube 24 of the piping 20 is attached to the end of the joint 21.

[0062] 1, the other end of the piping 20 is connected to the flow rate calculation and display unit 6, and the other end of the connection wire 47 inside the piping 20 is also connected to the flow rate calculation and display unit 6. This electrically connects the ultrasonic sensor 5 and the flow rate calculation and display unit 6 to form the ultrasonic flowmeter 1. The piping 20 is pulled out from the sensor unit 7 in a direction substantially parallel to the central axis X of the measuring pipe 2 and is provided up to the flow rate calculation and display unit 6 so as to follow the outer peripheral surface of the measuring pipe 2. After being assembled as described above, the flow rate calculation and display unit 6 and the sensor unit 7 have a sealed structure, and therefore the cover member 8 cannot be removed from the sensor case 3 unless the fitting 21 of the piping 20 is removed by cutting the piping 20 or forcibly pulling the piping 20 out of the sensor case 3, thereby destroying it.

[0063] The ultrasonic flowmeter 1 of the first embodiment has the above-described structure and thereby provides the following functions and effects.

[0064] When the piping 20 is connected to the sensor unit 7, the cover member 8 attached to the sensor case 3 so as to cover the mounting portion 30 is fixed to the measuring pipe 2 so as not to be removed from the state in which it covers the mounting portion 30. After the ultrasonic flowmeter 1 is assembled, the cover member 8 cannot be removed from the sensor case 3 unless the joint 21 of the piping 20 is removed by cutting the piping 20 or forcibly pulling the piping 20 out of the sensor case 3, thereby destroying the piping.

[0065] That is, by adding the simple step of attaching the cover member 8 to the sensor case 3 in the cover member assembly process, it is possible to provide a sealed structure for the attachment site 30 of the sensor unit 7 to the measurement pipe 2. Because the heads of the bolts 51 are covered by the cover member 8 without being exposed, the user cannot rotate the bolts 51. This effectively prevents malicious user actions, such as, for example, removing the ultrasonic sensor 5 from the measurement pipe 2 to temporarily immobilize the flowmeter. In other words, it is possible to prevent theft of gas or water flowing through the measurement pipe 2. Furthermore, if someone were to attempt to remove the sensor unit 7, the pipe 20 or the structure around the cover member 8 would have to be destroyed, which would leave traces of the destruction.

[0066] Furthermore, the joint 21 of the pipe 20 is inserted into and screwed onto the second opening 72a of the second cover portion 66 of the cover member 8 and the first opening 62a of the connection portion of the sensor portion 7, thereby connecting the pipe 20 and the sensor portion 7. The joint 21 allows the pipe 20 and the sensor portion 7 to be connected without the use of tools, making the assembly work easier.

[0067] Furthermore, at this time, the piping 20 is inserted into the second opening 72a of the second cover part 66, preventing the cover member 8 from coming off the sensor case 3. That is, the small diameter cover part 72 of the second cover part 66 has the effect of preventing it from coming off, so by going through the single process of connecting the fitting 21 to the connection part 18, it is possible to simultaneously connect the piping 20 to the sensor part 7 and fix the cover member 8 attached to the sensor part 7. The work of creating a sealing structure is not complicated, and the cover member 8 can be easily fixed.

[0068] Second Embodiment Next, an ultrasonic flowmeter 100 according to a second embodiment of the present invention will be described with reference to Figs. 14 to 16. Note that components substantially similar to those in the first embodiment are denoted by the same reference numerals, and descriptions thereof will be omitted. The ultrasonic flowmeter 100 according to the second embodiment differs from the ultrasonic flowmeter 1 according to the first embodiment only in the configuration of the cover member 8.

[0069] The cover member 8 in the first embodiment was shaped to cover the entire sensor case 3 except for the tubular portion 15, but the cover member 80 in the second embodiment is shaped to cover a part of the mounting portion 16 and a part of the connecting portion 18 (small diameter connecting portion 62) of the sensor case 3. The cover member 80 includes a first cover portion 81 and a second cover portion 82.

[0070] The first cover part 81 covers only the portion of the mounting part 16 of the sensor case 3 where the heads of the bolts 51 are exposed. In other words, a portion of the outer surface of the mounting part 16 of the sensor case 3 is not covered by the first cover part 65. As shown in Figures 15 and 16, the first cover part 65 has two divided housing parts 83 that have the same shape.

[0071] The divided accommodating portion 83 is a cylindrical member whose outer shape is substantially elliptical in plan view (when viewed from the outside in the radial direction of the measurement tube 2). The divided accommodating portion 83 has a bottom opening 84 on one axial side (the side facing the sensor case 3 when attached) and an upper bottom portion 85 on the other side. The outer peripheral wall connecting the bottom opening 84 and the upper bottom portion 85 has two side flat portions 86 and two curved portions 87. The two side flat portions 86 face each other in parallel. The curved portions 87 are provided contiguous to both ends of the two side flat portions 86 and connect to both longitudinal ends of the two side flat portions 86. The contour of each curved portion 87 is semicircular in plan view.

[0072] A space 88 capable of accommodating the heads of two parallel bolts 51 is formed inside the divided accommodating portion 83. The two divided accommodating portions 83 are spaced apart from each other so that their longitudinal directions (the direction in which the side flat surfaces 86 extend) are parallel, and are connected by the second cover portion 66. The second cover portion 66 is provided upright at any position on the opposing side flat surfaces 86 in the portion where the divided accommodating portions 83 are spaced apart.

[0073] The second cover part 82 is dome-shaped and covers the small diameter connection part 62 of the sensor case 3. Unlike the first embodiment, the second cover part 82 does not have the large diameter cover part 71, and is configured to have only a portion corresponding to the small diameter cover part 72 in the first embodiment. Note that "covering the connection part" does not mean that the second cover part 82 covers the entire connection part 18, but also includes a portion of the connection part 18. An opening 89 (see FIG. 16 ) is formed in the second cover part 82 at the portion where the large diameter cover part 71 in the first embodiment was provided. A space 91 capable of accommodating the small diameter connection part 62 of the sensor case 3 is formed inside the second cover part 82.

[0074] The second cover portion 82 is formed with a second opening 82a for inserting the joint 21 of the pipe 20. The second opening 82a has a circular shape. Note that, in the second embodiment, the slit 75 is not formed. The second opening 82a has the same configuration as the second opening 72a of the first embodiment, and therefore a detailed description thereof will be omitted. According to the second embodiment, by placing the cover member 8 over the sensor case 3 from the connection portion 18 side, the head of the bolt 51 is accommodated in the space 88 within the first cover portion 81 (split accommodation portion 83), and the small-diameter connection portion 62 of the sensor case 3 is accommodated in the space 91 within the second cover portion 82.

[0075] The ultrasonic flowmeter 100 of the second embodiment can also achieve the same effects as the first embodiment. That is, the mounting site 30 can be easily sealed. Furthermore, the configuration of the cover member 8 is the minimum necessary to achieve the function of covering the mounting site 30 with the first cover portion 81 and the function of preventing the sensor case 3 from coming off with the second cover portion 82, so that the material of the cover member 8 can be reduced, and manufacturing costs can be kept down.

[0076] <Other embodiments> In the above embodiments, the first cover part 65 covers the entire attachment part 30 between the sensor case 3 and the measurement pipe 2, i.e., all of the heads of the four bolts 51, but it may also cover only a part of the attachment part 30. This is because as long as the head of at least one bolt 51 is covered, the sensor part 7 cannot be removed from the measurement pipe 2, thereby achieving a sealed structure.

[0077] In the second embodiment, the shapes of the first cover portion 81 and the second cover portion 82 can be arbitrarily modified in design to suit the position of the bolt 51 and the shape of the connection portion 18 of the sensor case 3. That is, it is sufficient that the first cover portion 81 and the second cover portion 82 are integrated, the first cover portion 81 can cover the head of the bolt 51, and the second cover portion 82 can be inserted into the joint 21 to prevent the cover member 8 from coming off. Therefore, the divided housing portion 83 may be a rectangular tube or another shape.

[0078] In each of the above embodiments, the sensor unit 7 is fixed to the measuring pipe 2 by the bolts 51, but it may be fixed by other fixing means. Also, the joint 21 of the pipe 20 and the sensor unit 7 are fastened by screwing together the threads, but they may be fastened by other fastening means other than threads. Any configuration is acceptable as long as the cover members 8, 80 are fixed to the sensor unit 7 by connecting the joint 21 to the sensor unit 7.

[0079] In the first embodiment, the first cover part 65 may cover only the attachment part 16, and the second cover part 66 may cover the connection part 18 and the neck part 17.

[0080] In the first embodiment, the slit 75 of the cover member 8 does not have to be formed. Alternatively, as in the cover member 8b shown in FIG. 17, the slit 92 may be formed so as to extend to the upper bottom portion 68 of the first cover portion 65. Furthermore, as in the cover member 8c shown in FIG. 18, instead of a slit, a receiving portion 93 may be provided that can temporarily receive the connection wire 47 when the cover member 8c is assembled to the sensor case 3. For example, the receiving portion 93 can be formed as a cylindrical portion that is continuous with the lower end of the second opening 72a and protrudes from the wall portion 74 in a direction away from the central axis N of the large-diameter cover portion 71. Various configurations are possible as long as it can function as a receiving portion that temporarily receives the connection wire 47 when the cover member 8c is assembled to the sensor case 3.

[0081] In each of the above embodiments, the cover members 8, 80 may be formed with a plurality of holes for draining drainage, oil, etc. contained in the fluid to be measured.

[0082] In each of the above embodiments, a joint cover for covering the joint 21 of the pipe 20 may be further provided. For example, as shown in FIG. 19 , a resin joint cover 94 is provided to cover the joint 21 so that it cannot be seen from the outside. In this configuration, after the joint 21 is connected to the sensor unit 7, the joint cover 94 is fitted, and then the shield tube 24 is connected. With this configuration, in order to rotate the joint 21, the joint cover 94 must first be destroyed, resulting in a stronger sealing structure than a configuration without the joint cover 94. This in turn effectively prevents attempts to remove the joint 21 from the cover members 8, 80.

[0083] The present invention is not limited to the above-described embodiments and can be realized in various configurations without departing from the spirit of the present invention. For example, the technical features in each embodiment corresponding to the technical features in the form described in the Summary of the Invention section can be appropriately replaced or combined to solve some or all of the above-described problems or achieve some or all of the above-described effects. Furthermore, if a technical feature is not described as essential in this specification, it can be appropriately deleted. [Explanation of symbols]

[0084] 1,100: Ultrasonic flowmeter 2: Measuring tube 3: Sensor case 4: Sensor bracket 5: Ultrasonic sensor 6:Flow rate calculation display section 7: Sensor section 8,80: Cover member 9: Flow path 10: Flange 12a: Mounting hole 15:Cylinder part 16: Mounting part 17: Neck 18: Connection part 19: Storage area 20: Piping 21: Joint 30: Mounting location 47: Connection line 51: Bolt 62a: 1st opening 65,81: First cover part 66,82: Second cover part 72a, 82a: 2nd opening 94: Joint cover

Claims

1. a measuring tube having a flow path through which a fluid flows; At least one pair of sensor units accommodating ultrasonic sensors are located on the upstream and downstream sides of the flow path and are provided on the outer wall of the measuring pipe so as to be capable of transmitting and receiving ultrasonic signals; a calculation processing unit provided outside the measuring pipe and configured to calculate a flow rate of the fluid based on a propagation time between the ultrasonic sensors; a pipe provided outside the measuring pipe, through which a connection line is inserted to electrically connect the ultrasonic sensor and the arithmetic processing unit; a cover member that is fixed to the measurement pipe in an unremovable manner from a state in which the cover member covers an attachment portion between the sensor unit and the measurement pipe when the piping is connected to the sensor unit; An ultrasonic flow meter comprising:

2. the sensor unit includes a sensor case including a connection portion having a first opening into which the pipe is inserted and a housing portion that houses the ultrasonic sensor; The cover member is a first cover portion that covers the attachment portion; a second cover portion that is integral with the first cover portion, covers the connection portion, and has a second opening portion into which the piping is inserted; and 2. The ultrasonic flowmeter according to claim 1, wherein the cover member is fixed to the measuring pipe by connecting the piping inserted into the second cover portion and the connecting portion through the second opening and the first opening to the connecting portion.

3. the sensor unit is fixed to the measurement pipe by attaching the housing portion of the sensor case to an attachment hole provided in the measurement pipe, the cover member covers the sensor case in a direction intersecting the axial direction of the measuring pipe, 3. The ultrasonic flowmeter according to claim 2, wherein the piping is provided from the connection portion to the arithmetic processing portion along the outer periphery of the measuring pipe.

4. the sensor case is fixed to the measuring pipe by a bolt, 4. The ultrasonic flowmeter according to claim 2, wherein the first cover portion covers the mounting portion including the head portion of the bolt.

5. Further, a coupling member is connected to the connection portion, 4. The ultrasonic flowmeter according to claim 2, wherein the pipe and the connecting portion are fastened together by screwing together threaded portions formed on the joint member and the connecting portion, respectively.

6. The ultrasonic flowmeter according to claim 5, further comprising a joint cover that covers the entire joint member.

7. a measuring tube having a flow path through which a fluid flows; At least one pair of sensor units accommodating ultrasonic sensors are located on the upstream and downstream sides of the flow path and are provided on the outer wall of the measuring pipe so as to be capable of transmitting and receiving ultrasonic signals; a calculation processing unit provided outside the measuring pipe and configured to calculate a flow rate of the fluid based on a propagation time between the ultrasonic sensors; a pipe provided outside the measuring pipe, through which a connection line is inserted to electrically connect the ultrasonic sensor and the arithmetic processing unit; a cover member that is fixed to the measurement pipe in an unremovable manner from a state in which the cover member covers an attachment portion between the sensor unit and the measurement pipe when the piping is connected to the sensor unit; A method for assembling an ultrasonic flow meter comprising: a sensor unit mounting step of mounting the sensor unit to the measuring pipe; a cover member assembling step of assembling the cover member to the attachment site so as to cover the attachment site; a piping connection step of connecting the piping to the sensor unit to which the cover member is attached; 1. A method for assembling an ultrasonic flowmeter, comprising:

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