Ultrasonic flowmeter

Abstract

The present invention provides an ultrasonic flow meter that is easy to assemble and allows for the smallest possible flow resistance for the fluid medium flowing through the measuring tube. [Solution] An ultrasonic flow meter 1 has a measuring tube 10 through which a flow space 11 extends, through which a flow medium 20 can flow in the direction of flow, a first ultrasonic transducer 12 is installed at a first position, and a second ultrasonic transducer 13 or a reflecting surface is installed at a second position, thereby sending ultrasonic waves into the flow space and receiving the sent ultrasonic waves again by the other ultrasonic transducer or the reflecting surface, respectively, while forming an ultrasonic propagation path 16, an inner wall segment 15 is installed inside the measuring tube, the sent ultrasonic waves strike and reflect off this inner wall segment, and the ultrasonic propagation path has sections perpendicular and lateral to the direction of flow.

Description

Technical Field

[0001] The present invention relates to an ultrasonic flowmeter, comprising a measuring tube through which a flow space extends, through which a flowing medium can flow in at least one flow direction, a first ultrasonic transducer being installed at a first position, and at least one second ultrasonic transducer or at least one reflecting surface being installed at a second position, whereby ultrasonic waves are sent into the flow space and the sent ultrasonic waves can be received again by the other ultrasonic transducer or reflected from the reflecting surface while forming an ultrasonic propagation path, an inner wall segment being installed in the measuring tube, the sent ultrasonic waves hitting and being reflected by this inner wall segment.

Background Art

[0002] Based on Patent Document 1, an ultrasonic flowmeter is known, which comprises a measuring tube through which a flow space extends, the flow space being flowed through by a flowing medium. In this case, a first ultrasonic transducer is installed at a first position and a second ultrasonic transducer is installed at a second position in order to send ultrasonic waves into the flow space and receive the sent ultrasonic waves again by the other ultrasonic transducer.

[0003] The ultrasonic sensors are positioned in the measuring tube at a predetermined angle to form an oblique path for ultrasonic waves through the measuring tube. The ultrasonic waves can be emitted by a first ultrasonic transducer and received by a second ultrasonic transducer, and emitted by a second ultrasonic transducer and received by a second ultrasonic transducer. When the flow medium flows along the longitudinal axis through the flow space of the measuring tube, the flow medium carries the ultrasonic waves to the receiving ultrasonic transducer more quickly by the flow than when sound propagates in the opposite direction to the flow. Therefore, the resulting time-of-flight difference is evaluated by the evaluation electronic equipment, which allows for the inference of the flow velocity of the flow medium in the flow space of the measuring tube.

[0004] Unfortunately, this leads to the drawback that since the ultrasound must penetrate the tube wall, both ultrasonic transducers must be positioned on the outside of the measuring tube, forming a predetermined angle with respect to the longitudinal axis.

[0005] Patent Document 2 discloses an alternative configuration of an ultrasonic flowmeter. This ultrasonic flowmeter includes a measuring tube through which a flow space extends, through which a flow medium can flow, and a first ultrasonic transducer is positioned in a first position and a second ultrasonic transducer is positioned in a second position such that a W-shaped wave propagation of ultrasonic waves occurs between the ultrasonic transducers. A flow limiting element is provided to affect the propagation of ultrasonic waves in the flow passage, the flow limiting element is positioned between two of a total of three reflectors, the flow limiting element includes a first wedge having a first inclined surface, the first wedge having a plurality of first teeth protruding from the first inclined surface, the flow passage includes an inlet opening, the flow path includes an inlet opening, the inlet opening is positioned on the opposite side from the outlet opening, the fluid path extends from the inlet opening to the outlet opening, and the three reflectors are first reflectors The apparatus includes a first reflector, which is positioned closest to the outlet opening among the three reflectors, and the three reflectors include a second reflector, which is positioned closest to the inlet opening among the three reflectors, and a flow limiting element is inserted between the first and second reflectors, and the flow passage has a fourth wedge with a fourth inclined surface, the fourth wedge having at least one tooth protruding from the fourth inclined surface, and the fourth wedge is positioned between the second reflector and the inlet opening. In particular, the flow limiting element significantly narrows the remaining flow cross-section, which results in pressure loss in the flow measuring instrument.

[0006] Ultrasonic flowmeters are the most precise and versatile instruments for measuring the flow rate of liquids and gases. They utilize the properties of ultrasound, which moves through various media at characteristic velocities. The velocity of the ultrasound is influenced by the flow velocity of the medium.

[0007] The fundamental principles of ultrasonic flow measurement are based on three key methods: In the time-of-flight method, two ultrasonic transducers transmit and receive signals along and in the direction of flow, and the time-of-flight difference is used to calculate the flow velocity. In contrast, the Doppler method measures the frequency change of ultrasound reflected by particles or bubbles in the medium, and is therefore particularly suitable for media containing particles or bubbles. The cross-correlation method analyzes the delay between correlated signals from different transducers, which makes this method ideal for heterogeneous flows.

[0008] Advances in technologies such as multipath technology and clamp-on ultrasonic measurement have significantly expanded the applicability of these instruments. Multipath technology utilizes multiple ultrasonic paths, thereby compensating for non-uniformities in the flow, such as turbulent or asymmetrical profiles, and thus improving measurement accuracy. Clamp-on technology allows ultrasonic transducers to be attached to the pipeline externally using retaining elements, making these instruments ideal for applications where invasion of the pipe system is undesirable.

[0009] Clamp-on ultrasonic measurements generally operate according to the time-of-flight principle. Sound waves are sent through the pipe wall into the medium, reflected by the pipe wall on the opposite side, and then measured. The time-of-flight difference between the wave traveling in the direction of flow and the wave traveling in the opposite direction helps to calculate the flow velocity. Compared to in-line (in-pipe) measurements, where the sensor is directly positioned in the medium and thus provides extremely accurate results, the clamp-on method is non-contact and avoids intrusion into the pipe system. However, the clamp-on method has challenges such as signal loss due to reflection at the interface.

[0010] Insertion solutions constitute a hybrid form of invasive in-line devices and non-contact clamp-on systems. In insertion solutions, the sensor is inserted into the pipeline through a special opening or valve, thereby ensuring direct contact with the medium. This offers the advantage of less invasive installation compared to in-line devices, but also presents unique challenges. Geometric changes in the pipe wall caused by insertion sensors can form cavities and dead zones, leading to flow turbulence, sedimentation, and inaccuracies. Pressure loss occurs due to flow resistance and turbulence, particularly when the sensor is not properly positioned or aerodynamically shaped.

[0011] Clamp-on technology also has its own inherent drawbacks, such as the problem of structure-borne sound. Ultrasound can travel through the tube wall, which can lead to undesirable malfunctions. Another challenge is reflection at the interface caused by differences in acoustic impedance, as well as enclosed air that weakens or scatters sound waves. At typical frequencies of 1 MHz to 10 MHz, even small amounts of enclosed air can cause significant signal loss.

[0012] Optimizations such as the use of expensive bonding materials, frequency matching, and advanced signal processing can help minimize these drawbacks. Overall, clamp-on ultrasonic measurement provides a flexible and non-contact solution for flow measurement, particularly in applications where opening pipe systems is prohibited due to sanitary or operational requirements.

[0013] Ultrasonic flowmeters are widely used in industries including water supply, energy, chemical and petrochemicals, and the food and beverage industries. Nevertheless, challenges remain, such as accuracy in heavy media, sensitivity to flow profiles, and suitability for extreme operating conditions. Future developments will focus on miniaturizing sensor devices, expanding measurement capabilities for heterogeneous media, and improving energy efficiency and robustness.

[0014] Patent documents 3 or 4 disclose an ultrasonic flowmeter that delivers ultrasonic waves into a flow space at an angle to the longitudinal axis. Although sound waves can be directly incident into the flow medium, an undesirable dead zone is created before the ultrasonic transducer, and this dead zone undesirably affects the flow of the flow medium. [Prior art documents] [Patent Documents]

[0015] [Patent Document 1] German Patent No. 102006019146 Specification [Patent Document 2] European Patent No. 3800448 [Patent Document 3] European Patent Application Publication No. 1096236 [Patent Document 4] German Patent Application Publication No. 3941544 [Overview of the Initiative] [Problems that the invention aims to solve]

[0016] Therefore, the object of this invention is to provide an ultrasonic flow meter that can be easily assembled and allows for the smallest possible flow resistance for the fluid medium flowing through the measuring tube. In particular, the object of this invention is to minimize pressure loss in the insertable sensor. Ideally, the flow meter should have only pressure loss corresponding to the nominal diameter of the tube section. [Means for solving the problem]

[0017] This problem is solved starting with the ultrasonic flowmeter described in the premise of claim 1, and relating to the features described in each feature section. An advantageous improvement of the present invention is described in the dependent claims.

[0018] This invention includes the technical teaching that the ultrasonic propagation path has sections perpendicular and transverse to the flow direction.

[0019] The solution to the problem is first a wise selection of the ultrasonic propagation path. The section perpendicular and lateral to the flow direction forms an M shape and does not form a W shape. This M shape is illustrated by lines in FIGS. 2 to 4. Strictly speaking, this M shape is an M shape that is upside down in the drawing.

[0020] The M shape has multiple advantages. The sensor end face is formed so as to be well shape-coupled with the inner wall of the pipe. As a result, the sensor end face has no significant deviation from the inner wall contour of the remaining measurement pipe. In this configuration, the regions of stagnant water in the cavity and the protrusion are minimized. <B000082>

[0021] Furthermore, the M shape enables a measurement section perpendicular to the flow, which is advantageous because it allows measurement of the sound propagation speed of fluids that depend particularly on temperature and purity.

[0022] Therefore, the present invention relates to an ultrasonic flowmeter having a measurement pipe through which a flow space extends, through which a flowing medium can flow in a flow direction, a first ultrasonic transducer installed at a first position, and at least one second ultrasonic transducer or at least one reflecting surface installed at a second position, whereby ultrasonic waves are sent into the flow space and the sent ultrasonic waves can be received again by the other ultrasonic transducer or by the reflecting surface while forming an ultrasonic propagation path, an inner wall segment is installed in the measurement pipe, the sent ultrasonic waves hit and are reflected by this inner wall segment, and the ultrasonic propagation path has a section perpendicular and lateral to the flow direction.

[0023] The ultrasonic propagation path is formed in an M shape, the "V-shaped" section inside the M shape is formed so as to extend obliquely with respect to the flow direction, and the "I-shaped" section outside the M shape is formed so as to extend perpendicular to the flow direction.

[0024] At least one or more inner wall segments can form at least one or more cavities, and these cavities are at least partially or completely covered by a shape-coupled cover surface for the separation of the fluid in the flow space and the ultrasonic transducer, and the space volume in each cavity is fluid-technologically separated from the flow space.

[0025] Furthermore, the cover surface is formed from a membrane, and the membrane enables the space volume of the cavity to be filled with a flowing medium flowing through the flow space.

[0026] The membrane can form a planar body having a plurality of openings and / or being perforated and / or being formed in a sieve shape. Alternatively, at least one small tube for the respiration of the cavity may be installed, and this small tube connects the space volume to the flowing medium inside the tube respectively. Advantageously, two small tubes may be installed, and these small tubes are positioned one after the other in the flow direction, thereby enabling a steady liquid exchange in the cavity even though the cover surface is substantially closed.

[0027] Alternatively, it can be规定 that the space volume is filled with a sealing compound and the cover surface is formed from the sealing compound. The sealing compound can have sound propagation characteristics the same as or similar to those of the flowing medium.

[0028] The flowing medium can be a gas or a liquid. It is also conceivable that the flowing medium is a phase mixture and / or has gaseous, liquid and / or solid components. The flowing medium can be formed, for example, at least partially by H2O. ……(这里原文中

[0029] - 没有实质内容,所以翻译中

[0029] - 也保留原样)

[0029] The sealing compound can behave like polyurethane and / or like "AptFlex F7" and / or can have polyurethane and / or "AptFlex F7". (这里原内容似乎不太完整准确,推测是想表达密封化合物可以像聚氨酯或“AptFlex F7”那样表现,或者含有聚氨酯和 / 或“AptFlex F7”,按照推测翻译了)

[0030] Furthermore, the thickness of the membrane can be considered to coincide with half the wavelength of sound in the membrane material, or an integer multiple of this wavelength. This makes it possible to make the membrane particularly transparent to sound waves of the frequencies used. This achieves a conduction of λ / 2, which works to make the membrane acoustically transparent to the extent that its acoustic impedance is no longer present.

[0031] Another means of improving the present invention will be described in more detail below, along with a description of a preferred embodiment of the present invention with reference to the drawings. [Brief explanation of the drawing]

[0032] [Figure 1] This figure shows an ultrasonic flowmeter with two ultrasonic transducers positioned on the outside of the measuring tube. [Figure 2] This diagram shows an ultrasonic flowmeter equipped with ultrasonic transducers that are incident or received perpendicularly to form an M-shape in the ultrasonic propagation path, with two cavities machined into the inner contour of the measuring tube. [Figure 3] This diagram shows an ultrasonic flowmeter with two cavities in the inner contour of the measuring tube, which are filled with a sealing compound. [Figure 4] This diagram shows an ultrasonic flowmeter with two cavities in the inner contour of the measuring tube, which are covered by a membrane that is permeable to sound and fluid. [Modes for carrying out the invention]

[0033] Figure 1, like Figures 2, 3, and 4, shows an ultrasonic flowmeter 1, which includes a measuring tube 10 through which a flow space 11 extends, through which a flow medium 20 can flow in the flow direction 111, and a first ultrasonic transducer 12 is installed at a first position I, and at least one second ultrasonic transducer 13 or at least one reflecting surface is installed at a second position II, thereby enabling ultrasonic waves 14 to be sent into the flow space 11, and the sent ultrasonic waves 14 can be received again by the other ultrasonic transducers 12, 13, or by the reflecting surface, forming an ultrasonic propagation path 16, and an inner wall segment 15 is installed inside the measuring tube 10, and the sent ultrasonic waves 14 strike and are reflected off the inner wall segment 15. Refer in particular to Figures 2 to 4 for this. The ultrasonic transducers 12 and 13 shown in Figure 1 are attached to the outer surface of the measuring tube 10 by the holding element 3, which allows for oblique incidence of ultrasonic waves, and this is conventional technology.

[0034] As shown in Figure 2, the large cavity 17 in front of the reflector at the apex of the M-shape would be undesirable. According to this invention, these cavities 17 are separated from the flow dynamics by the cover surfaces 18 and 19.

[0035] As shown in Figures 3 and 4, the cover surfaces 18 and 19 are shape-coupled to the inner wall of the pipe. Thus, the flow medium 20 simply passes through a nearly ordinary pipe section with a continuous inner wall.

[0036] Here, there are two possibilities for filling the cavity. On the one hand, the cavity can be filled with a sealing compound 24 having ultrasonic propagation velocity characteristics comparable to those of the flow medium 20. In particular, the sealing compound "AptFlex F7" may be suitable because it exhibits acoustic behavior similar to conventional flow mediums that contain or resemble water. On the other hand, the spatial volume behind the cover surfaces 18,19 can be filled with a flowing fluid. In this case, the ultrasonic propagation velocity is usually the same, and the perforations in the membrane may be configured so that fluid exchange can still occur within the cavity, i.e., behind the membrane.

[0037] AptFlex F7 is a polyurethane-based specialty sealing compound frequently used in ultrasonic technology. Supplied by Precision Acoustics Ltd, AptFlex F7 serves primarily as an acoustically optimized material for applications requiring low attenuation and good acoustic impedance matching.

[0038] A key characteristic of AptFlex F7 is its low acoustic attenuation. This results in high signal quality and minimal loss during ultrasonic transmission. Furthermore, it allows for good acoustic impedance matching, which is particularly important for minimizing reflections at the interface. This also allows for the use of flexible and durable materials, which are particularly robust and suitable for use in variable environments.

[0039] Furthermore, AptFlex F7 is easy to process, supplied in liquid form, and hardens to form a flexible solid material. AptFlex F7 is used as a seal and protective part for ultrasonic sensors, and is often used to protect ultrasonic sensors from mechanical damage, moisture, and other environmental factors. In addition, AptFlex F7 can serve as an acoustic coupling medium, particularly in the manufacture of ultrasonic arrays or acoustic elements, and in research and development, AptFlex F7 can be used in ultrasonic technology and related fields to enable accurate measurements.

[0040] The present invention is not limited to the preferred embodiments described above in its implementation. Rather, numerous variations are conceivable in which the presented solutions are used in fundamentally different implementations. All features and / or advantages evident from the claims, specification, or drawings, including structural details or spatial arrangements, may be important to the present invention, individually or in various combinations. [Explanation of symbols]

[0041] 1 Ultrasonic flowmeter 3 Retention elements 10 Measuring tube 11 Flow Space 12 Ultrasonic transducers 13. Ultrasonic transducer 14. Ultrasound 15 Inner wall segments 16 Ultrasound propagation paths 16a Vertical section 16b Sections extending horizontally 17 Cavity 18 Cover surface 19 Cover surface 20 Flow media 21 Spatial volume section 22 membrane 23 Small tube 24. Encapsulating compound 111 Flow direction

Claims

1. An ultrasonic flow meter (1) comprising a measuring tube (10), through which a flow space (11) extends, through which a flow medium (20) can flow in at least one flow direction (111), a first ultrasonic transducer (12) is installed at a first position (I), and at least one second ultrasonic transducer (13) or at least one reflecting surface is installed at a second position (II), thereby sending ultrasonic waves (14) into the flow space (11) and receiving the sent ultrasonic waves (14) again by the other ultrasonic transducers (12, 13) or reflecting surface, respectively, forming an ultrasonic propagation path (16), and an inner wall segment (15) is installed inside the measuring tube (10), to which the sent ultrasonic waves (14) strike and are reflected, in an ultrasonic flow meter, An ultrasonic flow meter (1) characterized in that the ultrasonic propagation path (16) has sections perpendicular (16a) and lateral (16b) to the flow direction (111).

2. The ultrasonic flow meter (1) according to claim 1, characterized in that the ultrasonic propagation path (16) is formed in an M shape, the inner "V" section of the M shape is formed to extend diagonally with respect to the flow direction (111), and the outer "I" section of the M shape is formed to extend perpendicularly with respect to the flow direction (111).

3. The ultrasonic flowmeter (1) according to claim 1 or 2, characterized in that at least one or more inner wall segments (15) form a cavity (17), the cavity (17) is at least partially or completely covered by shape-coupled cover surfaces (18, 19) for separation of the fluid in the flow space (11) from the ultrasonic transducers (12, 13), and each of the cavity (17) has a single spatial volume portion (21) that is fluid-technically separated from the flow space (11).

4. The ultrasonic flowmeter (1) according to any one of claims 1 to 3, characterized in that the cover surface (18, 19) is formed from a membrane (22), and the membrane (22) allows the spatial volume portion (21) of the cavity (17) to be filled with a flow medium (20) that flows through the flow space (11).

5. The ultrasonic flowmeter (1) according to any one of claims 1 to 4, characterized in that the membrane (22) forms a planar body having an opening and / or a perforated surface and / or is formed in a sieve shape.

6. An ultrasonic flow meter (1) according to any one of claims 1 to 5, characterized in that at least one small tube is installed, and each small tube connects the spatial volume section (21) to the flow medium (20) inside the tube.

7. The ultrasonic flow meter (1) according to any one of claims 1 to 6, characterized in that the spatial volume portion (21) is filled with a sealing compound (24), and the cover surfaces (28, 29) are formed from the sealing compound (24).

8. The ultrasonic flowmeter (1) according to any one of claims 1 to 7, characterized in that the sealing compound (24) has the same or similar sound propagation characteristics as the flow medium.

9. The ultrasonic flow meter (1) according to any one of claims 1 to 8, characterized in that the flow medium (20) is a gas.

10. The ultrasonic flow meter (1) according to any one of claims 1 to 9, characterized in that the flow medium (20) is a liquid.

11. The ultrasonic flow meter (1) according to any one of claims 1 to 10, characterized in that the flow medium (20) is a phase mixture and / or has gaseous, liquid or solid components.

12. The ultrasonic flow meter (1) according to any one of claims 1 to 11, characterized in that the flow medium (20) is at least partially formed of H2O.

13. The ultrasonic flow meter (1) according to any one of claims 1 to 12, characterized in that the sealing compound (24) behaves like polyurethane and / or like "AptFlex F7" and / or has components of polyurethane and / or "AptFlex F7", or is composed of polyurethane and / or "AptFlex F7".

14. The ultrasonic flowmeter (1) according to any one of claims 1 to 13, characterized in that the thickness of the membrane (22) is equal to half the wavelength of sound in the material of the membrane (22) or an integer multiple of said wavelength.

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