Ultrasonic flow meter

Abstract

Ultrasonic flowmeter (1) with at least one measuring tube (2), with at least one first ultrasonic transducer (3) and a second ultrasonic transducer (4), wherein the first ultrasonic transducer (3) is designed as an ultrasonic transmitter and / or as an ultrasonic receiver and wherein the second ultrasonic transducer (4) is designed as an ultrasonic transmitter and / or as an ultrasonic receiver, wherein the ultrasonic transducers (3, 4) are arranged offset on the measuring tube (2) as seen in the direction of flow such that the respective transmitter emits an ultrasonic signal in the direction of flow or counter to the direction of flow during operation and that the receiver receives the ultrasonic signal emitted by the transmitter after at least three reflections, wherein at least three reflection surfaces (9, 10) are present and wherein the course of the ultrasonic signal between the ultrasonic transducers (3, 4) defines a signal path (5), characterized by that the signal path (5) has a first signal path section (6) and a second signal path section (7), wherein the first signal path section (6) has at least two subsections (6.1, 6.2, 6.3), wherein the second signal path section (7) has at least two subsections (7.1, 7.2, 7.3) and wherein the number of subsections (6.1, 6.2, 6.3) of the first signal path section (6) corresponds to the number of subsections (7.1, 7.2, 7.3) of the second signal path section (7), that the signal path in the first signal path section (6) has a first direction of rotation and that the signal path in the second signal path section (7) has a second direction of rotation, wherein the second direction of rotation is opposite to the first direction of rotation, wherein the signal path (5) has exactly two signal path sections (6,7), that at least one reflector element (8) with a reflection surface (9) is present, wherein the at least one reflector element (8) is arranged between the first signal path section (6) and the second signal path section (7) and that the measuring tube (2) has an inner wall (11) and that at least one reflection surface (10) is formed by the inner wall (11) of the measuring tube (2), and that all reflection surfaces (10) within a signal path section (6, 7), i.e. with the exception of the reflection surface (9) which is arranged between the first signal path section (6) and the second signal path section (7), are formed by the inner wall (11) of the measuring tube (2), and that the reflection surface (9) between the first signal path section (6) and the second signal path section (7) is formed by the reflector element (8).

Description

[0001] The invention is based on an ultrasonic flow meter with at least one measuring tube, with at least one first ultrasonic transducer and a second ultrasonic transducer, wherein the first ultrasonic transducer is designed as an ultrasonic transmitter and / or as an ultrasonic receiver and wherein the second ultrasonic transducer is designed as an ultrasonic transmitter and / or as an ultrasonic receiver, wherein the ultrasonic transducers are arranged offset on the measuring tube as seen in the direction of flow such that the respective transmitter emits an ultrasonic signal in the direction of flow or against the direction of flow during operation and that the receiver receives the ultrasonic signal emitted by the transmitter after at least three reflections, wherein at least three reflection surfaces are present and wherein the course of the ultrasonic signal between the ultrasonic transducers defines a signal path.

[0002] The measurement of the flow of a medium flowing through a measuring tube using an ultrasonic flowmeter is known from the prior art. Ultrasonic flowmeters typically comprise a measuring tube and at least two ultrasonic transducers configured as ultrasonic transmitters and / or ultrasonic receivers, which are arranged on the measuring tube at a distance from one another in the direction of flow (axially relative to the measuring tube axis). To measure the flow, an ultrasonic signal is emitted along the signal path between the ultrasonic transducers, both in the direction of flow and opposite to the direction of flow. Due to the entrainment effect, the signals moving along a signal path with or against the flow have different propagation times. The flow velocity and, taking the measuring tube cross-section into account, the volume flow are determined from the propagation time difference.

[0003] Ultrasonic flow meters are also known, where the signal path between the two ultrasonic transducers is extended by one or more reflections on a respective reflection surface.

[0004] The publication DE 10 2013 105 922 A1 discloses an ultrasonic flowmeter, wherein the signal path between the two ultrasonic transducers is designed such that, in an axial plan view of the measuring tube cross-section, it forms a closed signal path, and wherein the signal is reflected back into a virtually identical plane at two points within the measuring tube. For the purposes of this document, the relevant plane is defined as a plane parallel to the measuring tube axis, which is spanned by a portion of the signal path. The closed signal path, in combination with double back reflection, allows even rotating flows with turbulence to be reliably detected, such as those that can occur following disturbances in the pipe, such as pipe bends, 90° bends, etc.

[0005] Furthermore, EP 0 639 776 A1 discloses an ultrasonic flowmeter, wherein a plurality of ultrasonic transducer pairs are arranged on the measuring tube in such a way that at least two ultrasonic signals are emitted into the measuring tube. The signal paths formed by the respective paths of the ultrasonic signals have a different degree of sensitivity with respect to the symmetry of the flow profile, and at least one sound wave passes through the measuring tube in a clockwise direction and at least one sound wave passes through the measuring tube in a counterclockwise direction. With this arrangement, for example, even flow profiles exhibiting turbulence can be reliably measured.

[0006] The documents DE 10 2012 013 916 A1, DE 10 2013 105 407 A1, DE 298 03 912 U1 and EP 0 715 155 A1 also disclose ultrasonic flow meters, wherein a signal path is spanned between two ultrasonic transducers, which comprises a plurality of signal path sections, wherein the measuring signal passes through the measuring tube cross-section in the individual signal path sections in different directions.

[0007] In principle, for signal paths that have at least one reflection on a reflection surface (so-called multi-path systems), a direction of rotation (clockwise or counterclockwise) can be defined with which the ultrasonic signal passes through the measuring tube.

[0008] Based on this prior art, it is the object of the invention to provide an ultrasonic flow meter which is particularly simple in design and which has a particularly high measuring accuracy even in the case of uneven flows which, for example, have turbulences.

[0009] According to the invention, this object is achieved in that the signal path has a first signal path section and a second signal path section, wherein the first signal path section has at least two subsections, wherein the second signal path section has at least two subsections and wherein the number of subsections of the first signal path section corresponds to the number of subsections of the second signal path section and that the signal course in the first signal path section has a first direction of rotation and that the signal course in the second signal path section has a second direction of rotation, wherein the second direction of rotation is opposite to the first direction of rotation.

[0010] According to the invention, the signal path has exactly two signal path sections.

[0011] According to the invention, it was recognized that in multi-path systems, a particularly high measurement accuracy can be achieved by aligning the ultrasonic transducers in such a way that a first scan of the flow profile in a first signal path section, viewed in an axial plan view of the measuring tube cross-section, takes place in a direction of rotation, for example clockwise, and that in a second signal path section the scan of the flow to be measured takes place in the opposite direction of rotation, for example counterclockwise.

[0012] According to the invention, the two signal path sections have the same number of subsections, so that the flow is traversed equally in the first direction of rotation and also in the opposite direction of rotation. This inventive design has the advantage that rotating components of a flow, in particular turbulences, which generate fictitious velocity components when measuring the flowing medium using ultrasonic signals, are traversed in different directions, allowing these interfering components to be effectively filtered out.

[0013] As a result, the ultrasonic flow meter according to the invention has a particularly high measurement accuracy even with irregular flow profiles, which in particular include turbulence.

[0014] According to the invention, the measuring tube has an inner wall, with at least one reflection surface being formed by the inner wall of the measuring tube. According to the invention, all reflection surfaces within a signal path section, i.e., with the exception of the reflection surface arranged between the first signal path section and the second signal path section, are formed by the inner wall of the measuring tube. Each individual reflection surface can, for example, be formed by the smooth inner wall of the measuring tube or by a shape of the measuring tube, with the reflection surface either protruding into the measuring tube or being arranged set back from the inner wall.

[0015] According to the invention, at least one reflector element is provided, wherein the at least one reflector element is arranged between the first signal path section and the second signal path section. The reflector element is thus particularly preferably arranged, viewed in the flow direction, in particular centrally, between the two ultrasonic transducers. According to one embodiment, the two ultrasonic transducers and the reflection surface formed by the reflector element are arranged at the same location on the measuring tube circumference, viewed in the axial direction.

[0016] The presence of a reflector element with a reflection surface between the first signal path section and the second signal path section has the advantage that the reflection of the ultrasonic signal from the first signal path section into the second signal path section can be designed particularly flexibly with regard to the reflection direction by a corresponding design and arrangement of the reflection surface.

[0017] In a particularly preferred embodiment, the reflection surfaces within the first and second signal path sections are each formed by the smooth inner wall of the measuring tube, and the reflection surface between the first and second signal path sections is formed by a reflector element. This embodiment has the advantage of being particularly simple, since a complete scan of the flow profile in two rotational directions is achieved with the help of only one reflector element.

[0018] According to a further embodiment, the reflector element or the reflection surface formed by the reflector element is arranged set back from the inner wall of the measuring tube. Alternatively or additionally, at least one reflector element or the reflection surface formed by the reflector element protrudes into the measuring tube. Alternatively or additionally, one reflector element or the reflection surface formed by the reflector element is flush with the inner wall of the measuring tube.

[0019] Particularly for measuring the edge regions of the flowing medium, it is also conceivable for at least one ultrasonic transducer or both ultrasonic transducers to be positioned set back from the inner wall of the measuring tube. Alternatively, at least one ultrasonic transducer or both ultrasonic transducers can extend into the measuring tube.

[0020] The flexible arrangement of one or more reflector elements and / or the ultrasonic transducers makes it possible to realize different signal path geometries.

[0021] According to a next preferred embodiment, the reflection surface between the first signal path section and the second signal path section is designed and arranged such that the reflection causes a reversal of direction with respect to the rotation of the signal path. Particularly preferably, the reversal of direction is achieved by reflecting the ultrasonic signal back substantially into the plane of the incident ultrasonic signal.

[0022] According to one embodiment, the signal path is designed as a closed path when viewed from an axial view of the measuring tube cross-section. According to this embodiment, the ultrasonic transducers are arranged at the same location on the measuring tube circumference in the axial direction of the measuring tube.

[0023] This design has the advantage that the flow cross-section is measured essentially circularly, which also increases the measurement accuracy.

[0024] According to a further advantageous embodiment, each signal path section forms a closed path in axial plan view.

[0025] Particularly preferably, the signal profile of the first signal path section and the signal profile of the second signal path section are substantially congruent in axial plan view. According to this embodiment, there are corresponding subsections that lie in the same plane parallel to the measuring tube axis and that are traversed in a first rotational direction in the first signal path section and in an opposite rotational direction in the second signal path section.

[0026] According to a next embodiment, the first signal section and the second signal section each have more than two subsections, wherein the signal path and / or each signal path section essentially forms a triangle or a quadrilateral or a pentagon in an axial plan view of the measuring tube cross-section.

[0027] In detail, there are now numerous possibilities for designing and developing the ultrasonic flowmeter according to the invention. Reference is made to the claims subordinate to the independent patent claim as well as to the following description of preferred embodiments in conjunction with the drawings. The drawings show: Fig. 1 shows a first embodiment of an ultrasonic flowmeter according to the invention, Fig. 2 the first embodiment of the ultrasonic flowmeter according to the invention in a further view, Fig. 3 the first embodiment of an ultrasonic flowmeter according to the invention in an axial plan view of the measuring tube cross-section, Fig. 4a to different geometries of the signal path between the 4d ultrasonic transducers in axial plan view and Fig. 5 another embodiment of an ultrasonic flow meter in partial view.

[0028] In Fig. Figure 1 shows an embodiment of an ultrasonic flowmeter 1 with a measuring tube 2 and a first ultrasonic transducer 3, which is configured as an ultrasonic transmitter or an ultrasonic receiver depending on the operating mode, and a second ultrasonic transducer 4, which is also configured either as an ultrasonic transmitter or an ultrasonic receiver depending on the operating mode. The ultrasonic transducers 3 and 4 are arranged offset on the measuring tube, viewed in the direction of flow, such that the respective transmitter emits an ultrasonic signal in the direction of flow or against the direction of flow during operation, and the receiver receives the ultrasonic signal emitted by the transmitter. The course of the ultrasonic signal between the ultrasonic transducers 3, 4 defines a signal path 5.

[0029] The signal path 5 formed between the ultrasonic transducers 3 and 4 has a first signal path section 6 and a second signal section 7, i.e. a total of exactly two signal path sections 6 and 7, wherein the first signal path section 6 has three subsections 6.1, 6.2, 6.3 and wherein the second signal path section 7 also has three subsections 7.1, 7.2 and 7.3. The subsections 6.1 and 7.3, as well as the subsections 6.2 and 7.2 and the subsections 6.3 and 7.1, each lie in the same plane parallel to the measuring tube axis. A reflector element 8 with a reflection surface 9 is arranged between the first signal path section 6 and the second signal path section 7. Each signal path section 6, 7 has two further reflections, wherein the respective reflection surfaces 10 are formed by the smooth inner wall 11 of the measuring tube 2.

[0030] Due to the course of the signal path 5, the medium flowing through the measuring tube is scanned during operation, depending on the flow direction, first counterclockwise and then clockwise or vice versa.

[0031] The ultrasonic flow meter shown here therefore has the advantage that it is particularly simple in design and that it ensures particularly high measurement accuracy even in flows with turbulence.

[0032] Fig. 2 shows the same exemplary embodiment of the ultrasonic flow meter 1 in a different view. It is shown that the signal path 5 as a whole, but also each signal path section 6 and 7, form a closed path, wherein, viewed in the axial direction, both the ultrasonic transducers 3 and 4 and the reflection surface 9 are arranged at the same point on the measuring tube circumference. In the exemplary embodiment shown, each signal path section 6 and 7 is designed in the shape of a triangle in an axial plan view, wherein the first signal path section 6 passes through the measuring tube counterclockwise in an axial plan view and the second signal path section 7 passes through the measuring tube clockwise, so that any turbulence that may be present in the flow profile is filtered out particularly easily by the ultrasonic signal passing through the turbulence in the same plane both clockwise and counterclockwise.

[0033] Fig. 3 shows the axial plan view of the measuring tube cross-section of the first embodiment of the ultrasonic flow meter 1. The illustration shows that in this view the signal path 5 or the signal path sections 6 and 7 have the shape of a triangle.

[0034] In the Fig. 4a to 4d, alternative signal path profiles of the signal path 5 are shown schematically in axial plan view. In the simplest case, each signal path section 6, 7 comprises only one reflection, for example, against the inner wall of the measuring tube 2, wherein the signal path 5 additionally comprises a reflection between the first signal path section 6 and the second signal path section 7, which reverses the direction of rotation of the signal path 5 or of the ultrasonic signal emitted during operation. This particularly simple embodiment is shown in Fig. 4a.

[0035] In addition, the signal path 5 in axial plan view can also have the shape of a triangle ( Fig. 4b) or a square shape (4c), which allows the detection of further outlying areas of the flow profile, or the shape of a pentagon ( Fig. 4d), which also allows the edge area of ​​the flow profile to be captured.

[0036] For a flexible design of the signal path, one or more reflector elements 8 can be provided, wherein the reflector element 8 or the reflection surface 9 can be arranged either set back with respect to the inner wall 11 of the measuring tube 2 or can also protrude into the measuring tube 2. This is shown in Fig.5. Depending on the arrangement of the reflection surfaces 9, it is possible to measure areas of the flow profile that are closer to the edge or areas that are close to the measuring tube axis. Furthermore, the ultrasonic transducers 3, 4 can be arranged offset or extend into the measuring tube 2 to achieve different signal profile geometries.

[0037] As a result, all embodiments show an ultrasonic flow meter or parts thereof, whereby a particularly high measurement accuracy can be guaranteed due to the advantageous signal routing. Reference symbol 1 ultrasonic flow meter 2 measuring tube 3 ultrasonic transducers 4 ultrasonic transducers 5 Signal path 6 first signal path section 6.1, 6.2, 6.3 sections 7 second signal path section 7.1, 7.2, 7.3 subsection 8 Reflector 9 Reflection surface 10 Reflection surface 11 Inner wall of the measuring tube

Claims

[1] Ultrasonic flowmeter (1) with at least one measuring tube (2), with at least one first ultrasonic transducer (3) and a second ultrasonic transducer (4), wherein the first ultrasonic transducer (3) is designed as an ultrasonic transmitter and / or as an ultrasonic receiver and wherein the second ultrasonic transducer (4) is designed as an ultrasonic transmitter and / or as an ultrasonic receiver, wherein the ultrasonic transducers (3, 4) are arranged offset on the measuring tube (2) as seen in the direction of flow such that the respective transmitter emits an ultrasonic signal in the direction of flow or counter to the direction of flow during operation and that the receiver receives the ultrasonic signal emitted by the transmitter after at least three reflections, wherein at least three reflection surfaces (9, 10) are present and wherein the course of the ultrasonic signal between the ultrasonic transducers (3, 4) defines a signal path (5), characterized by , that the signal path (5) has a first signal path section (6) and a second signal path section (7), wherein the first signal path section (6) has at least two subsections (6.1, 6.2, 6.3), wherein the second signal path section (7) has at least two subsections (7.1, 7.2, 7.3) and wherein the number of subsections (6.1, 6.2, 6.3) of the first signal path section (6) corresponds to the number of subsections (7.1, 7.2, 7.3) of the second signal path section (7), that the signal path in the first signal path section (6) has a first direction of rotation and that the signal path in the second signal path section (7) has a second direction of rotation, wherein the second direction of rotation is opposite to the first direction of rotation, wherein the signal path (5) has exactly two signal path sections (6,7), that at least one reflector element (8) with a reflection surface (9) is present, wherein the at least one reflector element (8) is arranged between the first signal path section (6) and the second signal path section (7) and that the measuring tube (2) has an inner wall (11) and that at least one reflection surface (10) is formed by the inner wall (11) of the measuring tube (2), and that all reflection surfaces (10) within a signal path section (6, 7), i.e. with the exception of the reflection surface (9) which is arranged between the first signal path section (6) and the second signal path section (7), are formed by the inner wall (11) of the measuring tube (2), and that the reflection surface (9) between the first signal path section (6) and the second signal path section (7) is formed by the reflector element (8). [2] Ultrasonic flow meter (1) according to claim 1, characterized bythat the at least one reflector element (8) or the reflection surface (9) formed by the at least one reflector element (8) is arranged set back with respect to the inner wall (11) of the measuring tube (2). [3] Ultrasonic flow meter (1) according to one of claims 1 to 2, characterized by that the reflection surface (9) between the first signal path section (6) and the second signal path section (7) is designed such that the reflection causes a reversal of direction with respect to the rotation of the signal path. [4] Ultrasonic flow meter (1) according to one of claims 1 to 3, characterized by that the signal path (5) is designed as a closed path in an axial plan view of the measuring tube cross-section. [5] Ultrasonic flow meter (1) according to one of claims 1 to 4, characterized by that each signal path section (6,7) forms a closed path in an axial plan view of the measuring tube cross-section. [6] Ultrasonic flow meter (1) according to claim 5, characterized by that the signal profile of the first signal path section (6) and the signal profile of the second signal path section (7) are substantially congruent in axial plan view. [7] Ultrasonic flow meter (1) according to one of claims 1 to 6, characterized by that the first signal path section (6) and the second signal path section (7) each have more than two subsections and that the signal path (5) and / or each signal path section (6, 7) forms a triangle or a quadrilateral or a pentagon in an axial plan view of the measuring tube cross-section.

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