Straight-type flow meter sensor

Abstract

The objective is to provide a straight-type flow meter sensor that can measure with stable sensitivity over a wide temperature range, including high temperatures. The straight-type flow meter sensor 11 of the present invention comprises a pair of shoes 61, a coupling material layer 81, an inner case 22, an outer case 21, a pressing plate 74, a screw member 73, and a coil spring 82. The pressing plate 74 is positioned between the shoe 61 and the inner wall surface 51a of the inner case 22, with its front surface in surface contact with the first pressed portion P1 of the shoe 61. The screw member 73 has its screw tip in contact with the back surface of the pressing plate 74, and by screwing it in, it presses the first pressed portion P1 towards the center of the pipe 1 via the pressing plate 74. The coil spring 82 has its first end t1 in contact with the second pressed portion P2 of the shoe 61, and presses the second pressed portion P2 towards the center of the pipe 1. Selected figure: Figure 4

Description

Technical Field

[0001] The present invention relates to a straight-type flow meter sensor, and particularly to a straight-type flow meter sensor having a plurality of legs that sandwich a pipe from both sides.

[0002] Conventionally, as a measuring device using ultrasonic waves, various ultrasonic flow meters for measuring the flow rate of a liquid have been proposed. In this ultrasonic flow meter, a flow measurement pipe is provided in the middle of a pipe through which a liquid flows, and ultrasonic sensors are installed at the upstream position and the downstream position of the flow measurement pipe, respectively. Then, ultrasonic waves are transmitted and received using these ultrasonic sensors, and the flow rate of the liquid is calculated based on the time difference between the propagation time of the ultrasonic wave propagating from the upstream side to the downstream side and the propagation time of the ultrasonic wave propagating from the downstream side to the upstream side.

[0003] As various types of ultrasonic flow meters of this kind have been proposed conventionally, for example, a clamp-on type ultrasonic flow meter sensor that can be attached by sandwiching a straight-shaped pipe is well known (see, for example, Patent Documents 1 and 2).

[0004] In addition, straight-type flow meter sensors of another type that are not of the clamp-on type have also been proposed conventionally (see, for example, Patent Documents 3 and 4). This type of straight-type flow meter sensor has a double-structured case (an inner case and an outer case that houses it). And a pipe made of a resin material is provided so as to penetrate the case. Inside the inner case, a pair of shoes are accommodated in a state offset in the axial direction of the pipe. The pair of shoes has a main body portion that supports an ultrasonic vibrator and a plurality of legs that sandwich the pipe from both sides.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

[0006] Incidentally, the leg-clamp type straight flow meter sensor mentioned above is used not only for measurements in environments where fluids at room temperature flow through piping, but also sometimes for measurements in environments where high-temperature fluids flow.

[0007] However, even if the required sensitivity was obtained during the initial measurement of high-temperature fluid, there was a problem in that the seal between the shoe and the pipe deteriorated when the temperature of the fluid flowing through the pipe (i.e., the temperature of the pipe) dropped to room temperature. Once this decrease in seal occurred, the sensitivity remained reduced thereafter, regardless of whether the fluid was measured at room temperature or high temperature, and in cases where the decrease in sensitivity was significant, measurement became impossible. Therefore, the conventional leg-clamp type straight flow meter sensor described above could not perform stable measurements without a decrease in sensitivity over a wide temperature range, including the high-temperature range.

[0008] The present invention has been made in view of the above-mentioned problems, and its objective is to provide a straight-type flow meter sensor that can maintain sensitivity and perform stable measurements over a wide temperature range, including high-temperature ranges. [Means for solving the problem]

[0009] To solve the above problems, the invention described in claim 1 is positioned offset in the axial direction of a straight pipe through which a fluid flows, and supports an ultrasonic transducer on the inclined surface on the front side. Furthermore, a front tongue is integrally formed on the lower part of the front side, and a rear tongue is integrally formed on the lower part of the rear side.A straight-type flow meter sensor comprising: a main body; a pair of shoes having a plurality of legs protruding from the bottom surface of the shoe so as to sandwich the piping from both sides; a coupling material layer positioned in contact with the outer surface of the piping and the bottom surface of the shoe; an inner case for housing and positioning the pair of shoes; and an outer case for housing the inner case, wherein a pressing plate is positioned between the shoe and the inner wall surface of the inner case such that the front surface of the plate is in surface contact with the first pressed portion on the shoe; a screw member is provided inside the inner case such that the tip of the screw abuts against the back surface of the plate of the pressing plate, and when screwed in, applies a pressing force that presses the first pressed portion on the shoe toward the center of the piping via the pressing plate; and the first end of the screw is located at the second pressed portion on the shoe. The upper surface of the front tongue piece and the upper surface of the rear tongue piece are respectively In a state of contact and constantly compressed , within the inner case, a pair of positions spaced apart in the front-rear direction of the shoe It is provided with a coil spring that applies a biasing force to press the second pressed portion toward the center of the pipe. The front surface of the pressing plate is positioned in surface contact with the top surface of the shoe, which is the first pressed portion. The gist of this invention is a straight-type flow meter sensor characterized by the following features.

[0010] Accordingly, according to the invention described in claim 1, a pressing force corresponding to the degree of screwing in of the screw member is applied, and the first pressed portion of the shoe is pressed toward the center of the pipe via the pressing plate, so that the shoe is assembled in a tightly fitted state to the pipe. In addition, the coil spring is provided inside the inner case in a constantly compressed state, and its biasing force acts to constantly press the second pressed portion of the shoe toward the center of the pipe. For this reason, even if the fluid temperature drops from high temperature to room temperature and the pressing force acting via the pressing plate decreases or disappears, the shoe is pressed by the coil spring, maintaining the tight fit between the shoe and the pipe. Thus, sensitivity is maintained over a wide temperature range, including high temperature ranges, and measurements can be performed stably without becoming impossible to measure.

[0012] Also, bookAccording to the invention, compared to the case where a coil spring is provided in only one place, a more even pressing force can be applied to the shoe. Furthermore, when the pair of coil springs are spaced apart in the front-rear direction, the shoe is positioned stably, resulting in less tilting or misalignment of the shoe.

[0014] Also, book According to the invention, space for accommodating a pair of coil springs is easily secured in the front and rear regions of the shoe, making it easier to assemble the pair of coil springs. Furthermore, since a second pressing area of ​​the required size is secured on the upper surfaces of the front tongue and the rear tongue, the first end can be stably positioned in contact with the upper surfaces. Moreover, since a first pressing area of ​​the required size is secured on the top surface of the shoe, the front surface of the pressing plate can be stably positioned in surface contact with the top surface.

[0015] Claim 2 The invention described in the claim 1 In this configuration, the second ends of the pair of coil springs are provided within the inner case, with each end in contact with the front surface of the pressing plate.

[0016] Therefore, claim 2 According to the invention described above, the second end of a pair of coil springs receives a resistive force from the inner wall surface of the inner case, thereby generating a biasing force that presses the shoe on the opposite end, the first end.

[0017] Claim 3 The invention described in the claim 2 The gist of this invention is that the upper surfaces of the front tongue piece and the rear tongue piece are each provided with first locking portions for positioning the first ends of the pair of coil springs.

[0018] Therefore, claim 3According to the invention described in , by locking the first ends of the pair of coil springs to the first locking portions, the first ends are respectively positioned at suitable positions on the upper surfaces of the front tongue piece and the rear tongue piece. Therefore, the biasing force of the pair of coil springs can be reliably applied to the shoe. Also, the pair of coil springs can be easily assembled.

[0019] Claim 4 The invention described in is 3 characterized in that, on the front surface of the plate of the pressing plate, a second locking portion for positioning the second ends of the pair of coil springs is provided.

[0020] Therefore, according to the invention described in 4 by locking the second ends of the pair of coil springs to the second locking portions, the second ends are respectively positioned at suitable positions on the pressing plate. Therefore, the biasing force of the pair of coil springs can be reliably applied to the shoe.

[0021] Claim 5 The invention described in is 1 characterized in that the second ends of the pair of coil springs are provided in the inner case in a state of respectively contacting the inner wall surface of the inner case.

[0022] Therefore, according to the invention described in 5 by receiving resistance from the inner wall surface of the inner case on the second end sides of the pair of coil springs, a biasing force for pressing the shoe can be generated on the first end sides, which are the opposite sides. Also, with this configuration, since the pair of coil springs do not press the pressing plate, the biasing force can be set independently of the pressing force through the pressing plate. [[ID=...]]

[0023] Claim 6 The invention described in is 1In this configuration, insertion portions are formed at both ends of the pressing plate in the longitudinal direction, through which a pair of coil springs can be inserted. The second ends of the pair of coil springs are inserted through the insertion portions and are provided inside the inner case, in contact with the inner wall surface of the inner case.

[0024] Therefore, claim 6 According to the invention described above, since the second ends of the pair of coil springs are inserted into the insertion portion of the pressing plate, the pair of coil springs can be arranged inside the inner case while avoiding interference with the pressing plate.

[0025] Claim 7 The invention described in the claim 6 The gist of this invention is that the upper surfaces of the front tongue piece and the rear tongue piece are each provided with first locking portions for positioning the first ends of the pair of coil springs.

[0026] Therefore, claim 7 According to the invention described above, the first ends of a pair of coil springs are locked to a first locking portion, thereby positioning the first ends at suitable locations on the upper surfaces of the front and rear tongue pieces. This ensures that the biasing force of the pair of coil springs is reliably applied to the shoe. Furthermore, the pair of coil springs can be easily assembled.

[0027] Claim 8 The invention described is as described in Claims 1 to 7 In any one of the above, the plurality of legs consist of a total of four legs, a pair of front legs and a pair of rear legs, and the plurality of legs are positioned relatively close to the screw member when the axial direction of the piping is taken as the reference, and the pair of coil springs are positioned relatively far from the screw member.

[0028] Therefore, claim 8According to the invention described above, since the pair of coil springs are located further from the screw member than the pair of front legs and the pair of rear legs, it becomes easier to apply a uniform pressing force to the shoe. Therefore, the shoe is more easily positioned stably, and tilting or misalignment of the shoe is less likely to occur.

[0029] Claim 9 The invention described is as described in Claims 1 to 7 In any one of the above, the gist of the provision is that the piping is made of a resin material having heat resistance up to 200°C, and the flow meter sensor is used in an environment in which the fluid at 90°C or higher flows through the piping. [Effects of the Invention]

[0030] As detailed above, claims 1 to 9 According to the invention described above, it is possible to provide a straight-type flow meter sensor that can perform measurements while maintaining stable sensitivity over a wide temperature range, including high-temperature ranges. [Brief explanation of the drawing]

[0031] [Figure 1] A perspective view showing a straight-type flow meter sensor according to an embodiment of the present invention. [Figure 2] A perspective view of the straight-type flow meter sensor of the first embodiment, seen from a different angle. [Figure 3] An exploded perspective view showing a straight-type flow meter sensor of the first embodiment. [Figure 4] A plan view showing the straight-type flow meter sensor of the first embodiment with the upper case split piece and upper cover member removed. [Figure 5] An exploded perspective view illustrating the arrangement of each component housed within the inner case. [Figure 6] A perspective view illustrating the arrangement of each component housed within the inner case. [Figure 7] (a) to (e) are cross-sectional diagrams illustrating a pair of shoes, coupling material layers, and piping in order to explain the problems of conventional straight-type flow meter sensors. [Figure 8] (a) and (b) are plan views schematically showing a pair of shoes, coupling material layers, piping, etc., to illustrate the problems of conventional straight-type flow meter sensors, and (c) and (d) are plan views schematically showing a pair of shoes, coupling material layers, piping, etc., to illustrate the advantages of the straight-type flow meter sensor of this embodiment. [Figure 9] A plan view showing the straight-type flow meter sensor of the second embodiment with the upper case split piece and upper cover member removed. [Figure 10] A plan view showing the pressure plate of a straight-type flow meter sensor according to the second embodiment. [Figure 11] A plan view showing the straight-type flow meter sensor of the third embodiment with the upper case split piece and upper cover member removed. [Best Mode for Carrying Out the Invention]

[0032] [First Embodiment] Hereinafter, a straight-type flow meter sensor 11, which embodies one embodiment of the present invention, will be described in detail with reference to Figures 1 to 8.

[0033] As shown in Figures 1 to 7, the straight-type flow meter sensor 11 of this embodiment comprises a pipe 1, an inner case 22, an outer case 21, an ultrasonic transducer 64, a shoe 61, a coupling material layer 81, etc. This straight-type flow meter sensor 11 can be used not only in environments where a low-temperature liquid (especially a room-temperature liquid of about 20°C ± 15°C) flows through the pipe 1, but also in environments where a high-temperature liquid (especially a high-temperature liquid of 90°C or higher, especially a high-temperature liquid of 90°C or higher, or 200°C or lower) flows through it.

[0034] The pipe 1 is a resin tube member with a circular cross-section, and at least a part of it has a straight section. The fluid to be measured for flow rate is flowed inside the pipe 1, and in this embodiment, a high-temperature liquid of about 90°C to 200°C is flowed inside. The pipe 1 is made of a thermoplastic resin material that has heat resistance in a temperature range of at least 90°C to 200°C. Specifically in this embodiment, a fluororesin such as PFA (perfluoroalkoxyalkane) is selected as the resin material. This type of fluororesin is preferable because it has chemical resistance that prevents deterioration or corrosion even when exposed to high temperatures, strong acids, and strong alkalis. A sheet-like coupling material layer 81 is arranged on the outer circumferential surface of the shoe installation location in the pipe 1. The coupling material layer 81 is in contact with the outer circumferential surface of the pipe 1 and the shoe bottom surface 65, which will be described later. The coupling material layer 81 in this embodiment is a rectangular sheet material with a thickness of about 0.5 mm to 1 mm, and is made of an elastic material that has heat resistance in a temperature range of at least 90°C to 200°C. In this embodiment, a fluororubber with high heat resistance (for example, FKM (hexafluoropropylene-vinylidene fluoride copolymer, etc.)) is specifically selected as the elastic material.

[0035] The pair of shoes (also called acoustic prisms) 61 are members that support an ultrasonic transducer 64 capable of transmitting and receiving ultrasonic waves, and also members that propagate ultrasonic waves from the ultrasonic transducer 64 towards the fluid in the pipe 1 (see Figures 5, 6, etc.). The pair of shoes 61 are arranged on the outer surface of the pipe 1 in a position that is almost opposite to each other in order to constitute a through-type straight flow meter sensor 11. The pair of shoes 61 also support the ultrasonic transducer 64 in a manner that allows ultrasonic waves to be incident at an oblique angle on the straight pipe 1 through which the fluid flows, and are positioned offset in the axial direction D1 of the pipe 1. The pair of shoes 61 are made of a resin material that has heat resistance in a temperature range of at least 90°C to 200°C. Specifically in this embodiment, PES (polyethersulfone) is selected as the resin material.

[0036] As shown in Figures 5 and 6, the pair of shoes 61 in this embodiment are the same size and have the same shape. More specifically, these shoes 61 have a long block shape in the front-to-back direction (left-to-right direction in Figures 5 and 6) and are formed using a resin material that can efficiently transmit ultrasonic waves. A front inclined surface 63 is formed on the front side of the main body 62 that constitutes the shoe 61, at a predetermined angle (approximately 60° in this embodiment) with respect to the shoe bottom surface 65. A disc-shaped ultrasonic transducer 64 made of a ceramic sintered body is bonded and supported on this front inclined surface 63. In this embodiment, for example, an ultrasonic transducer 64 that generates ultrasonic waves at 2 MHz is used, but of course, one that generates other frequencies may also be used. Furthermore, as the ceramic sintered body that constitutes the ultrasonic transducer 64, which is a piezoelectric element, a porous sintered body of alkali niobate piezoelectric ceramics, such as potassium sodium niobate, is selected, but of course, other ceramic sintered bodies may also be used. The ultrasonic radiating surfaces of these ultrasonic transducers 64 are positioned at an angle toward the straight pipe 1.

[0037] A front tongue 68 is integrally formed on the lower front side of the main body 62. The front tongue 68 is rectangular and extends toward the front of the main body 62. A rear tongue 69 is integrally formed on the lower rear side of the main body 62. The rear tongue 69 is rectangular and extends toward the rear of the main body 62. The lengths of the front tongue 68 and rear tongue 69 are not particularly limited, but are set to approximately 1 / 6 to 1 / 3 of the length of the main body 62. The thickness of the front tongue 68 and rear tongue 69 is also not particularly limited, but is set to approximately 1 / 6 to 1 / 3 of the thickness of the main body 62.

[0038] Multiple legs 66 are integrally provided protruding from the bottom surface 65 of the shoe (i.e., the surface facing the pipe 1) of the main body 62 that constitutes these shoes 61. In this embodiment, the bottom surface 65 of the shoe is flat, but it may be curved in a concave shape to conform to the shape of the outer surface of the pipe 1. These legs 66 extend in the same direction and hold and fix the pipe 1 by sandwiching it from both sides. In this embodiment, there are a total of four legs 66 (a pair of front legs 66a and a pair of rear legs 66b), each having the same shape and size. The number of legs 66 is not limited to four; it may be three or fewer, or five or more. Each leg 66 is formed to be slightly shorter than the diameter of the pipe 1. The pair of front legs 66a and the pair of rear legs 66b are spaced apart at a distance greater than the width of the legs 66. The reason for this is to position the leg portion 66 belonging to the other shoe 61 with ample space in the area between the front leg portion 66a and the rear leg portion 66b belonging to one shoe 61.

[0039] The pair of shoes 61 are arranged with their legs 66 offset from each other in the axial direction D1 of the piping 1, and are positioned so that the legs 66 of the other shoe 61 (i.e., the opposing shoe 61) do not come into contact with each other. The reason for avoiding contact between the legs 66 is to prevent the ultrasonic vibrations emitted by the ultrasonic transducer 64 belonging to one shoe 61 from being directly transmitted to the other. In addition, the multiple legs 66 are arranged so as to avoid the center of the ultrasonic beam emitted from the ultrasonic transducer 64. The reason for this is to reduce the loss of ultrasonic vibrations due to the transmission of the ultrasonic beam to the legs 66, thereby avoiding a decrease in measurement accuracy and sensitivity.

[0040] As shown in Figures 3 and 4, the inner case 22 is a rectangular box-shaped container that houses a pair of shoes 61 inside itself and holds and fixes them in the correct position relative to the piping 1. The inner case 22 may also serve as an electromagnetic shield to protect the ultrasonic transducer 64 housed inside from magnetic influences. The material used to form the inner case 22 is not particularly limited; for example, PPS or fluororesin can be used, but it is preferable to use a metal material with magnetic shielding properties when providing the function of an electromagnetic shield. The inner case 22 is composed of an upper cover member 51 and a lower cover member 52. Approximately U-shaped notches 54 are formed in the central parts of both end faces of the upper cover member 51 and the central parts of both end faces of the lower cover member 52. When the lower cover member 52 is placed over the upper cover member 51, these notches 54 form a circular pipe insertion hole.

[0041] The inner case 22 houses a pair of shoes 61 that securely hold the pipe 1 in place from both sides. In this configuration, the coupling material layer 81 is interposed between the outer surface of the pipe 1 and the bottom surface 65 of the shoe 61, and is in contact with them. The shoe sides of the shoe 61 are in close contact with the inner wall surface of the inner case 22.

[0042] As shown in Figures 1 to 4, the outer case 21 is a rectangular box-shaped container that is slightly larger than the inner case 22, and serves to house and protect the inner case 22, which is a sensor module. The material used to form the outer case 21 is not particularly limited, but for example, PPS or fluororesin can be used. This outer case 21 is composed of a lower case division piece 31 (first case division piece) and an upper case division piece 41 (second case division piece).

[0043] The lower case segment 31 has an opening on its upper side overall, and its opening edge constitutes the segmented surface P1 of the outer case 21. The lower case segment 31 is provided with a first side wall 31a on only one side. A pipe insertion section 33 having a first insertion hole 32 is projected from the center of the outer surface of the first side wall 31a, and the first end portion T1 of the pipe 1 is inserted through the first insertion hole 32. In addition, a connector section 34 for cable connection is projected from the outer surface of the first side wall 31a next to the pipe insertion section 33. As shown in Figure 3, a rectangular frame-shaped wall 36 is provided in the center of the inner bottom surface of the lower case segment 31. The inner case 22 is fitted into the recess formed by this wall 36, thereby positioning and fixing the inner case 22 to the lower case segment 31. At the four corners of the inner bottom surface of the lower case division piece 31, cylindrical boss portions 35 are provided, which are used when screwing and fixing the upper case division piece 41 to it. Each of the boss portions 35 has an internal thread.

[0044] On the other hand, the upper case segment 41 has an opening on its lower side overall, and its opening edge constitutes the segmentation surface P1 of the outer case 21. The upper case segment 41 is provided with a second side wall portion 41a on only one side. The second side wall portion 41a is positioned opposite the first side wall portion 31a on the outer case 21. A pipe insertion portion 43 having a second insertion hole 42 is projected from the center of the outer surface of the second side wall portion 41a, and the second end portion T2 of the pipe 1 is inserted through the second insertion hole 42. This upper case segment 41 differs from the lower case segment 31 in that it does not have a connector portion 34, a boss portion 35, and a wall portion 36. In addition, screw insertion portions 45 are formed at the four corners of the bottom surface of this upper case segment 41, opposite the boss portion 35 of the lower case segment 31. A screw 71 is inserted through each screw insertion portion 45, and a screw cover 72 is provided to conceal the screw 71.

[0045] A waterproof packing 23 is attached to the interface where the lower case division piece 31 and the upper case division piece 41 are joined at their dividing surfaces P1. The packing 23 in this embodiment is rectangular in shape, the same as the shape of the opening edge, and is formed using a fluororesin such as FPM. This waterproof packing 23 is compressed by tightening screws 71 from above and below while it is positioned between the lower case division piece 31 and the upper case division piece 41. As a result, no gap is formed at the interface between the lower case division piece 31 and the upper case division piece 41, resulting in improved sealing and thus waterproofing of the outer case 21.

[0046] Next, the structure for maintaining airtightness between the shoe 61 and the pipe 1 (airtightness maintenance structure) in this embodiment will be described. As shown in Figures 3 to 6, the airtightness maintenance structure in this embodiment is composed of a pressing plate 74, a screw member 73, and a coil spring 82.

[0047] The pressing plate 74 is a rectangular metal plate having heat resistance and rigidity at least from 90°C to 200°C. The pressing plate 74 in this embodiment has a length equal to the length of the shoe 61. The pressing plate 74 is positioned between one of the two shoes 61 (the upper shoe 61 in Figures 3 to 6) and the inner wall surface 51a of the inner case 22. The pressing plate 74 is positioned so that its front surface is in surface contact with the first pressed portion P1 of the shoe 61 (the top surface 67 of the shoe 61). Note that both ends of the pressing plate 74 in the longitudinal direction are not in surface contact with the top surface 67 of the shoe 61, but protrude in the front-rear direction of the main body 62.

[0048] The screw member 73 is a male screw member with a screw groove (not shown) formed on its outer circumference, and its tip is tapered and has a flat screw tip. The screw member 73 is inserted into a female screw hole 58 provided in the inner case 22. At this time, the screw tip of the screw member 73 reaches inside the inner case 22 and comes into contact with approximately the center of the back surface of the pressing plate 74. When the screw member 73 is screwed in, it applies a pressing force that presses the first pressed portion P1 toward the center of the pipe 1 via the pressing plate 74. As a result, the pair of shoes 61 are held and fixed in a position that prevents misalignment with respect to the inner case 22 and the pipe 1. Furthermore, by adjusting the degree to which the screw member 73 is screwed in, the contact pressure of the shoes 61 toward the pipe 1 during assembly at room temperature can be set. Note that, with respect to the axial direction D1 of the pipe 1, the multiple legs 66 are provided in positions relatively close to the screw member 73.

[0049] The coil springs 82 are positioned on the upper side of the shoe 61 in the inner case 22, as shown in Figures 3 to 6, in other words, on the same side as the pressure plate 74, and a pair of them are provided at positions spaced apart in the front-rear direction of the shoe 61. The coil springs 82 in this embodiment are made of metal wire having heat resistance and elasticity at least from 90°C to 200°C. When the axial direction D1 of the piping 1 (front-rear direction D2 of the shoe 61) is taken as the reference, the pair of coil springs 82 are provided at positions relatively far from the screw member 73. The pair of coil springs 82 have equal spring constants and are both in a constantly compressed state. These coil springs 82 are provided inside the inner case 22 with their first ends t1 in contact with the second pressure-bearing portion P2 on the shoe 61. Specifically, the upper central portion of the front tongue piece 68 and the upper central portion of the rear tongue piece 69 are provided with first locking portions 68a for positioning the first ends t1 of a pair of coil springs 82. In this embodiment, the first locking portions 68a are cylindrical projections, and the first ends t1 of the coil springs 82 are externally fitted and fixed to these projections. In other words, the first ends t1 of the pair of coil springs 82 are provided inside the inner case 22 in contact with the upper surfaces of the front tongue piece 68 and the rear tongue piece 69, respectively, which are the second pressed area P2.

[0050] Furthermore, the front surface of the pressing plate 74 is provided with a second locking portion 75a for positioning the second ends t2 of a pair of coil springs 82. The second locking portion 75a is positioned opposite the first locking portion 68a. In this embodiment, the second locking portion 75a is a cylindrical projection, and the second ends t2 of the coil springs 82 are externally fitted and fixed to these projections. In other words, the second ends t2 of the pair of coil springs 82 are provided inside the inner case 22, in contact with the front surface of the pressing plate 74. The pair of coil springs 82 constantly apply a biasing force that presses the second pressed portion P2 toward the center of the pipe 1. The biasing force of the pair of coil springs 82 increases in proportion to the degree to which the screw member 73 is screwed in, and is smaller than the pressing force of the screw member 73.

[0051] Here, based on Figure 7, we will describe the problems with the conventional leg-clamp type straight flow meter sensor. Figures 7(a) to 7(e) are schematic cross-sectional views of a pair of shoes 61, a coupling material layer 81, and a pipe 1, illustrating the above problems. Figure 7(a) shows the state after these components have been assembled at room temperature. The bottom surfaces 65 of the pair of shoes 61 contact the pipe 1 via the coupling material layer 81 at a predetermined contact pressure. This contact pressure is set in advance by adjusting the degree to which the screw member 73 is threaded, as described above. At this point, the pipe 1 has not yet undergone thermal deformation (thermal expansion). Incidentally, this state is maintained even when the initial flow rate measurement is performed in an environment where room temperature liquid flows before high-temperature liquid is flowed.

[0052] Figure 7(b) shows the state when flow rate measurement is being performed in an environment where a high-temperature liquid is flowing, and it shows how pipe 1 has softened and expanded in diameter due to thermal expansion. However, pipe 1, which has softened and expanded in diameter due to thermal expansion, actually deforms as shown in Figure 7(c), and its outer surface is pressed against the inner surface of the leg portion 66 and the coupling material layer 81, respectively, resulting in a tight seal. In other words, since pipe 1 is housed in a space with a rectangular cross-section, even if it originally had a circular cross-section, it deforms through heating to approach the rectangular cross-sectional shape of the housing space. In this state, the tight seal between the shoe bottom surface 65 and pipe 1 via the coupling material layer 81 is maintained. Therefore, the sensitivity does not decrease.

[0053] Figures 7(d) and 7(e) both show the state after flow rate measurement has been performed in an environment where a high-temperature liquid is flowing, and the temperature of the liquid flowing through pipe 1 (i.e., the temperature of pipe 1) has dropped to room temperature. At this time, pipe 1 hardens in a reduced diameter state due to contraction. For example, in Figure 7(d), the inner surface of the leg portion 66 is not pressed against pipe 1, and a gap G1 is created between them. On the other hand, the coupling material layer 81 is in contact with and pressed against pipe 1. Therefore, in this state, the ultrasonic propagation path from the ultrasonic transducer 64 to the liquid in pipe 1 is secured, and there is no decrease in sensitivity. In contrast, in Figure 7(e), the inner surface of the leg portion 66 is in contact with and pressed against pipe 1. In other words, the leg portion 66 clamps and fixes pipe 1 from both sides (left and right in the figure), making it difficult for pipe 1 to move (deform) in the vertical direction. Therefore, in Figure 7(e), the coupling material layer 81 is not pressed against pipe 1, and a gap G1 is created between them. Therefore, the ultrasonic wave propagation path cannot be secured, resulting in the inability to measure. Furthermore, even if the coupling material layer 81 is in contact with the pipe 1, sufficient contact pressure cannot be obtained, resulting in a decrease in sensitivity. Of course, if the decrease in sensitivity is significant, it will result in the inability to measure. Once a decrease in adhesion between the shoe bottom surface 65 and the pipe 1 via the coupling material layer 81 occurs, the sensitivity will remain reduced thereafter, regardless of whether the fluid is measured at room temperature or high temperature, and will not recover.

[0054] Figures 8(a) and 8(b) are schematic plan views of a conventional leg-clamping type straight flow meter sensor, showing a pair of shoes 61, a coupling material layer 81, a pipe 1, a screw member 73, and a pressing plate 74. Figure 8(a), like Figure 7(a), shows the state after these components have been assembled at room temperature. At this time, a predetermined contact pressure is set by adjusting the degree to which the screw member 73 is threaded, so that a relatively large pressing force (see arrow A1) is applied to the shoe 61. Figure 8(b), like Figures 7(d) and 7(e), shows the state after flow rate measurement has been performed in an environment where a high-temperature liquid flows, and the temperature of the pipe 1 has dropped to room temperature. In Figure 8(b), for example, a gap G1 is created between the top surface 67 of the shoe 61 and the pressing plate 74, so that no pressing force is applied to the top surface 67 of the shoe 61.

[0055] Figure 8(c) is a schematic plan view of the pair of shoes 61, coupling material layer 81, piping 1, screw member 73, pressure plate 74, and pair of coil springs 82 in this embodiment. Figure 8(c) shows the state after these components have been assembled at room temperature. At this time, a predetermined contact pressure is set by adjusting the degree to which the screw member 73 is threaded, so that a relatively large pressing force (see arrow A1) is applied to the shoe 61. In addition, a relatively small biasing force (see arrow A2) is also applied to the shoe 61 by the pair of coil springs 82 which are always in a compressed state. Figure 8(d) illustrates the state after the temperature of piping 1 has dropped to room temperature after flow rate measurement has been performed in an environment in which a high-temperature liquid flows. In Figure 8(d), for example, a gap G1 is created between the top surface 67 of the shoe 61 and the pressure plate 74, so that no pressing force is applied to the top surface 67 of the shoe 61. However, since the biasing force of the pair of coil springs 82 is still applied to the shoe 61, a contact pressure above a predetermined value is maintained.

[0056] [Examples] The evaluation tests performed on the straight-type flow meter sensor 11 of this embodiment will be described below.

[0057] In this evaluation test, a straight-type flow meter sensor 11 of this embodiment was prepared. First, the pair of coil springs 82 were removed, and the piping 1 was set between the pair of shoes 61. Then, the sensor 11 was reassembled. In Test 1, the sensitivity of this sensor 11 was measured at room temperature. The results are shown in Table 1 (Comparative Example 1). Here, the "GAIN value" was determined as an indicator of sensitivity. The GAIN value is a numerical value that indicates the amount of amplification required to bring the measured ultrasonic signal to a certain level. Incidentally, a high GAIN value means that the ultrasonic propagation intensity is small and a large amount of amplification is required (i.e., the sensitivity is low).

[0058] In Test 2, the sensor 11 used in Test 1 was left at 170°C for 1 hour, then returned to room temperature multiple times, and the sensitivity was measured at room temperature using the method described above. The results are shown in Table 1 (Comparative Example 2).

[0059] In Test 3, a pair of "type A" coil springs 82 were attached to the sensor 11 used in Test 2. With this setup, piping 1 was set between the pair of shoes 61, and the sensor 11 was reassembled. For the type A coil spring 82, a stainless steel coil spring with a spring constant of 0.49 N / mm and an outer diameter of 3 mm was used. The sensor 11 was then left at 170°C for 1 hour, and after being returned to room temperature once, the sensitivity was measured at room temperature using the method described above. The results are shown in Table 1 (Example 1).

[0060] In Test 4, a pair of "type B" coil springs 82 were attached to the sensor 11 used in Test 2. With this attached, the piping 1 was set between the pair of shoes 61, and the sensor 11 was reassembled. For the type B coil spring 82, a stainless steel coil spring with a spring constant of 0.29 N / mm and an outer diameter of 3 mm was used. The sensor 11 was then left at 170°C for 1 hour, and after being returned to room temperature once, the sensitivity was measured at room temperature using the method described above. The results are shown in Table 1 (Example 2). [Table 1]

[0061] As shown in Table 1, in Comparative Example 1, which had not yet been exposed to a high-temperature environment, the GAIN value was "54," while in Comparative Example 2, which had been exposed to a high-temperature environment, the GAIN value rose considerably to "110." In contrast, in Example 1, in which a type A coil spring 82 was added, the GAIN value became "59," confirming that it returned to a value similar to that of Comparative Example 1. Similarly, in Example 2, in which a type B coil spring 82 with a smaller spring constant was added, the GAIN value became "60," confirming that it returned to a value similar to that of Comparative Example 1. In other words, it was found that in Examples 1 and 2, in which a pair of coil springs 82 were added, sensitivity was maintained even after exposure to a high-temperature environment.

[0062] Therefore, according to this embodiment, the following effects can be obtained.

[0063] (1) According to the configuration of the straight-type flow meter sensor 11 of this embodiment, a pressing force corresponding to the degree of screwing in of the screw member 73 acts, and the first pressed portion P1 of the shoe 61 is pressed toward the center of the pipe 1 via the pressing plate 74, so that the shoe 61 is assembled in close contact with the pipe 1. In addition, the coil spring 82 is provided inside the inner case 22 in a constantly compressed state, and its biasing force acts to constantly press the second pressed portion P2 of the shoe 61 toward the center of the pipe 1. Therefore, even if the fluid temperature drops from high temperature to room temperature and the pressing force acting via the pressing plate 74 decreases or disappears, the shoe 61 is still pressed by the coil spring 82. As a result, the close contact between the shoe bottom surface 65 and the pipe 1 via the coupling material layer 81 is maintained, and a suitable ultrasonic wave propagation path is secured. Thus, it is possible to provide a straight-type flow meter sensor 11 that maintains sensitivity over a wide temperature range including high temperature ranges and can perform measurements stably without becoming unable to measure.

[0064] (2) In this embodiment, a pair of coil springs 82 are provided at positions spaced apart in the front-rear direction of the shoe 61. Therefore, compared to the case where a coil spring 82 is provided at only one location, a more even pressing force can be applied to the shoe 61. In addition, when the pair of coil springs 82 are spaced apart in the front-rear direction, the shoe 61 is positioned stably. As a result, tilting and displacement of the shoe 61 are less likely to occur.

[0065] (3) In this embodiment, a front tongue 68 is integrally formed on the lower front side of the main body 62, and a rear tongue 69 is integrally formed on the lower rear side of the main body 62. The first ends t1 of the pair of coil springs 82 are provided inside the inner case 22, in contact with the upper surfaces of the front tongue 68 and the rear tongue 69, respectively, which are the second pressed area P2. The front surface of the pressing plate 74 is positioned in surface contact with the top surface 67 of the shoe 61, which is the first pressed area P1. With this configuration, a suitable space for housing the pair of coil springs 82 is easily secured in the front and rear regions of the shoe 61. As a result, assembly of the pair of coil springs 82 becomes easier. In addition, the upper surfaces of the front tongue 68 and the rear tongue 69 are secured with the required size of second pressed area P2. Thus, the first ends t1 can be stably positioned in contact with each of the aforementioned upper surfaces. Furthermore, a first pressed area P1 of the required size is secured on the top surface 67 of the shoe 61. Therefore, the front surface of the pressing plate 74 can be stably positioned in surface contact with the top surface 67.

[0066] (4) In this embodiment, first locking portions 68a and 69a are provided on the upper surface of the front tongue piece 68 and the upper surface of the rear tongue piece 69, respectively, for positioning the first end t1 of the pair of coil springs 82. In addition, a second locking portion 75a is provided on the front surface of the pressing plate 74, which the second end t2 of the pair of coil springs 82 abuts against, for positioning the second end t2. Accordingly, with this configuration, the first end t1 is locked into the first locking portions 68a and 69a, thereby positioning the first end t1 at a suitable position on the upper surface of the front tongue piece 68 and the upper surface of the rear tongue piece 69, respectively. Also, the second end t2 is locked into the second locking portion 75a, thereby positioning the second end t2 at a suitable position on the front surface of the pressing plate 74. As a result, the first end t1 and the second end t2 of the pair of coil springs 82 are less likely to shift laterally in the spring diameter direction. Therefore, the biasing force of the pair of coil springs 82 can be reliably applied to the shoe 61. In addition, the assembly of the pair of coil springs 82 into the inner case 22 can be easily performed.

[0067] [Second Embodiment] Next, the straight-type flow meter sensor 11A of the second embodiment will be described in detail with reference to Figures 9 to 10. Here, we will describe the configurations that differ from those of the first embodiment, and the descriptions of common configurations will be omitted instead of assigning the same part numbers.

[0068] As shown in Figure 9, this straight-type flow meter sensor 11A includes a contact maintenance structure composed of a pressing plate 74A, a screw member 73, and a coil spring 82. The pressing plate 74A, the screw member 73, and the coil spring 82 are all positioned on the side of one of the two shoes 61 (the upper shoe 61 in Figure 9). The pressing plate 74A used in this embodiment is different from the pressing plate 74 of the first embodiment. Specifically, insertion portions 89 through which a pair of coil springs 82 can be inserted are formed at both ends in the longitudinal direction of this pressing plate 74A (see Figure 10). The insertion portions 89 in this embodiment are notched grooves cut in a U-shape. These notched grooves have a width slightly larger than the diameter of the coil springs 82, allowing the coil springs 82 to be inserted.

[0069] In this embodiment, the pair of coil springs 82 are provided inside the inner case 22 with their first ends t1 in contact with the second pressed portion P2 on the shoe 61, which is the same as in the first embodiment. However, in the first embodiment, the second ends t2 were in contact with the front surface of the pressing plate 74, whereas in this embodiment they are in contact with the inner wall surface 51a of the inner case 22. In other words, the pair of coil springs 82 are arranged inside the inner case 22 in a manner that avoids interference with the pressing plate 74A.

[0070] Furthermore, even with the straight-type flow meter sensor 11A configured in this way, the shoe 61 is pressed by the coil spring 82, maintaining airtightness between the shoe 61 and the pipe 1. Therefore, as in the first embodiment, stable sensitivity can be maintained over a wide temperature range, including high temperatures, for flow rate measurement. In addition, with the configuration of this embodiment, the second end t2 side of the pair of coil springs 82 receives a resistance force from the inner wall surface 51a of the inner case 22, thereby generating a biasing force that presses the shoe 61 on the opposite side, the first end t1 side. Moreover, since the pair of coil springs 82 do not press the pressing plate 74A, the biasing force can be set independently of the pressing force via the pressing plate 74A.

[0071] [Third Embodiment] Next, the straight-type flow meter sensor 11B of the third embodiment will be described in detail with reference to Figure 11. Here, we will describe the configurations that differ from the first embodiment, and the common configurations will be given the same part numbers and their descriptions will be omitted.

[0072] As shown in Figure 11, this straight-type flow meter sensor 11B is similar to the first embodiment in that it has a contact maintenance structure consisting of a pressing plate 74, a screw member 73, and a coil spring 82. However, the pressing plate 74A and the screw member 73 are located on the side of one of the two shoes 61 (the upper shoe 61 in Figure 11), and the pair of coil springs 82 are located on the side of the other shoe 61 (the lower shoe 61 in Figure 9). In other words, in the first embodiment, all three of the above components were located on the side of one shoe 61, whereas in this embodiment, some of the above three components are located on the side of the other shoe 61. In this embodiment, the second ends t2 of the pair of coil springs 82 are locked to a projection, which is a second locking portion 52a, that protrudes from the inner wall surface 51a of the inner case 22.

[0073] Furthermore, even with the straight-type flow meter sensor 11B configured in this way, the shoe 61 is pressed by the coil spring 82, maintaining a tight seal between the shoe 61 and the pipe 1. Therefore, as in the first embodiment, flow rate measurement can be performed while maintaining stable sensitivity over a wide temperature range, including high temperatures.

[0074] The above embodiment may be modified as follows.

[0075] In the first embodiment described above, a cylindrical projection was provided as the first locking portion 68a, and the first ends t1 of the pair of coil springs 82 were externally fitted thereto, but the invention is not limited to this. For example, in another embodiment, a projection of a shape other than cylindrical (e.g., hemispherical) may be provided. Alternatively, a recess may be provided instead of a projection, and the first ends t1 of the pair of coil springs 82 may be inserted therein and fixed. Of course, a configuration without projections or recesses is also possible, in which case, for example, the first ends t1 may be bonded and fixed to the second pressed portion P2.

[0076] In the first embodiment described above, a cylindrical projection was provided as the second locking portion 75a, and the second ends t2 of the pair of coil springs 82 were externally fitted thereto. However, the invention is not limited to this. For example, in another embodiment, a projection of a shape other than cylindrical (e.g., hemispherical) may be provided. Alternatively, a recess may be provided instead of a projection, and the second ends t2 of the pair of coil springs 82 may be inserted therein and fixed. Of course, a configuration without projections or recesses is also possible, in which case the second ends t2 may be fixed by bonding them to the pressing plate 74 or the inner wall surface 51a, for example.

[0077] In each of the above embodiments, a total of four legs 66 are provided protruding from the shoe bottom surface 65 of the main body portion 62 constituting the shoe 61 in order to hold and fix the pipe 1 by sandwiching it from both sides, but the number of legs may be changed.

[0078] • In the embodiments described above, a shoe 61 having a main body portion 62 that is substantially trapezoidal in side view was used, but the invention is not limited to this. For example, a shoe 61 having a main body portion 62 that is substantially triangular in side view may be used.

[0079] • In the ultrasonic transducers 64 of each of the above embodiments, an ultrasonic transducer 64 made of a porous sintered body of potassium sodium niobate (alkali niobate) was used, but the material used to form the ultrasonic transducer 64 is not particularly limited. For example, lead zirconate titanate (PZT), barium titanate, PMN-PT(Pb(Mg 1 / 3 Nb 2 / 3 )O3-PbTiO3) single crystal, PZNT(Pb(Zn 1 / 3 Nb 2 / 3 An ultrasonic transducer 64 made of a ceramic sintered body of a single crystal of )O3-PbTiO3 or LiNbO3 may also be used.

[0080] Next, in addition to the technical ideas described in the claims, the technical ideas that can be grasped by the embodiments described above are listed below. (1) The invention further comprises a coupling material layer that is in contact with the outer surface of the piping and the bottom surface of the main body of the shoe, wherein the coupling material layer is made of a heat-resistant material having heat resistance in a temperature range of 90°C to 200°C. (2) In claim 1, etc., the pressing plate and the coil spring are arranged on one side of the pair of shoes. (3) In claim 1, etc., the pressing plate is located on one side of the pair of shoes, and the coil spring is located on the other side. [Explanation of symbols]

[0081] 1: Piping 11, 11A, 11B: Straight-type flow meter sensor 21: Outer case 22: Inner case 51a: Inner wall surface (of the inner case) 52a, 75a: 2nd locking part 61: Shoe 62: Main body 63: Slope 64: Ultrasonic transducer 65: Shoe bottom 66: Legs 66a: Front leg 66b: Hind leg 67: Top surface (of a choux pastry) 68: Anterior tongue piece 68a, 69a: 1st locking part 69: Posterior tongue piece 73: Screw component 74, 74A: Pressure plate 81: Coupling material layer 82: Coil spring 89: Insertion part D1: Axial direction (of the piping) D2: Front-to-back direction of the shoe P1: First pressure point P2: Second pressure point t1: 1st end t2: 2nd end

Claims

1. The main body is positioned offset in the axial direction of a straight pipe through which fluid flows, supports an ultrasonic transducer on its inclined front surface, has a front tongue integrally formed on the lower front side, and a rear tongue integrally formed on the lower rear side, A pair of shoes having multiple legs protruding from the bottom surface of the shoe so as to sandwich the aforementioned piping from both sides, A coupling material layer is positioned in contact with the outer surface of the piping and the bottom surface of the shoe, An inner case for housing and positioning the pair of shoes, An outer case that houses the aforementioned inner case and A straight-type flow meter sensor equipped with, A pressing plate is positioned between the shoe and the inner wall surface of the inner case such that the front surface of the plate is in surface contact with the first pressed portion of the shoe, A screw member is provided inside the inner case with its screw tip in contact with the back surface of the pressing plate, and when screwed in, it applies a pressing force that presses the first pressed portion toward the center of the piping via the pressing plate, A pair of coil springs are provided within the inner case at positions spaced apart in the front-rear direction of the shoe, with the first end of each spring in contact with the upper surface of the front tongue piece and the upper surface of the rear tongue piece, respectively, which are the second pressed portion of the shoe, and are constantly compressed, and the coil springs provide a biasing force that presses the second pressed portion toward the center of the piping. Equipped with, The front surface of the pressing plate is positioned to be in surface contact with the top surface of the shoe, which is the first part to be pressed. A straight-type flow meter sensor characterized by the following features.

2. The straight-type flow meter sensor according to claim 1, characterized in that the second ends of a pair of coil springs are provided inside the inner case, with each end in contact with the front surface of the pressing plate.

3. The upper surfaces of the front tongue piece and the rear tongue piece are each provided with a first locking portion for positioning the first end of the pair of coil springs. The straight-type flow meter sensor according to feature 2.

4. The straight-type flow meter sensor according to claim 3, characterized in that the front surface of the pressing plate is provided with a second locking portion for positioning the second ends of a pair of coil springs.

5. The straight-type flow meter sensor according to claim 1, characterized in that the second ends of a pair of coil springs are provided inside the inner case, with each end in contact with the inner wall surface of the inner case.

6. The pressing plate has insertion portions formed at both ends in the longitudinal direction through which a pair of coil springs can be inserted. The second ends of the pair of coil springs are inserted through the insertion portion and are provided inside the inner case, in contact with the inner wall surface of the inner case. The straight-type flow meter sensor according to feature 1.

7. The straight-type flow meter sensor according to claim 6, characterized in that the upper surface of the front tongue piece and the upper surface of the rear tongue piece are each provided with a first locking portion for positioning the first end of the pair of coil springs.

8. The aforementioned multiple legs consist of a total of four legs, each comprising a pair of front legs and a pair of rear legs. With respect to the axial direction of the piping, the plurality of legs are positioned relatively close to the screw member, and the pair of coil springs are positioned relatively far from the screw member. A straight-type flow meter sensor according to any one of claims 1 to 7.

9. The aforementioned piping is made of a resin material that has heat resistance up to 200°C. The flow meter sensor is used in an environment where the fluid at 90°C or higher flows through the piping. A straight-type flow meter sensor according to any one of claims 1 to 7.

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