Ultrasonic flowmeter

Abstract

Disclosed is an ultrasonic flow meter (1) for measuring the flow of a fluid through a channel (2), the ultrasonic flow meter (1) comprising a flow meter body (10) and at least two ultrasonic transducers (11, 11A, 11B) attached to the flow meter body (10), the ultrasonic transducers (11, 11A, 11B) being configured to emit ultrasonic pulses to the channel and to receive ultrasonic pulses in the channel (2), the ultrasonic transducers (11, 11A, 11B) are arranged at a distance from one another in the flow direction (f) when the flow meter body (10) is fixed to the channel (2), and at least one ultrasonic transducer (11, 11A, 11B) is attached to the flow meter body (10) by means of an acoustic decoupling element (12, 12A, 12B).

Description

Technical Field

[0001] The present disclosure relates to an ultrasonic flow meter for measuring fluid flow in an HVAC system. Background Art

[0002] WO 2010 / 122117 A1 describes a ventilation system that draws air from the outside of a building into the interior of the building through a ventilation duct. The ventilation system has an ultrasonic sensor that is located in the ventilation duct upstream and / or downstream of the ventilator for measuring the volume flow. The ultrasonic sensor of WO 2010 / 122117 A1 includes a pair of ultrasonic transceivers that are mounted on opposite surfaces of the ventilation duct in a spaced relationship facing each other, and transmit and receive ultrasonic waves at an angle of 60-90 degrees relative to the surface of the ventilation duct.

[0003] WO 2021 / 130307 A1 discloses an HVAC flow measurement system, which includes an ultrasonic flow meter for measuring the flow of a fluid through a channel, the ultrasonic flow meter including ultrasonic transducers arranged at a certain distance from each other in the flow direction. The ultrasonic transducer is configured to transmit ultrasonic pulses into the channel and receive ultrasonic pulses in the channel. The HVAC flow measurement system is configured to measure the flow of the fluid through the channel not only using the received first reflected signal (i.e., the signal reflected from the channel wall opposite to the ultrasonic transducer), but also using multiple reflected signals, in particular, signals that have been reflected two or three times from the channel wall before being received. The disadvantage of using multiple reflected signals to measure flow is that the return signals from single reflection, double reflection and / or triple reflection signals may overlap with each other, making them difficult to distinguish. Summary of the invention

[0004] An object of the present disclosure and the embodiments disclosed herein is to provide an ultrasonic flow meter.

[0005] In particular, the object of the present disclosure and the embodiments disclosed herein is to provide an ultrasonic flow meter which does not have at least some of the disadvantages of the prior art and in particular which allows better differentiation of measurement signals of single, double and / or triple reflections.

[0006] The present disclosure relates to an ultrasonic flowmeter for measuring the flow rate of a fluid passing through a channel. The ultrasonic flowmeter includes a flowmeter body and at least two ultrasonic transducers attached to the flowmeter body. The ultrasonic transducer is configured to transmit at least one ultrasonic pulse into the channel and receive at least one ultrasonic pulse in the channel. Receiving an ultrasonic pulse in the channel means that the specific ultrasonic pulse received by the ultrasonic transducer is an ultrasonic pulse within the channel, which is incident on the ultrasonic transducer and is therefore received. When the flowmeter body is fixed to the channel, the ultrasonic transducers are arranged at a certain distance from each other in the flow direction. At least one of the ultrasonic transducers is attached to the flowmeter body through an acoustic decoupling element.

[0007] The acoustic decoupling element is configured to attenuate acoustic signals passing through it, in particular acoustic signals transmitted from the flow meter body through the acoustic decoupling element to the ultrasonic transducer; and vice versa (i.e., acoustic signals transmitted from the ultrasonic transducer through the acoustic decoupling element to the flow meter body). The acoustic decoupling element is particularly configured to attenuate acoustic signals in the ultrasonic frequency range (i.e., frequencies of 20 kHz and above).

[0008] The acoustic decoupling element has the benefit of improving the signal-to-noise ratio, particularly when a particular ultrasonic transducer receives an ultrasonic pulse from a channel (i.e., the particular ultrasonic transducer is in measurement mode). This is because the ultrasonic pulse emitted by the first ultrasonic transducer into the channel is also partially coupled into the flow meter body and travels through the flow meter body to the second ultrasonic transducer that receives the ultrasonic pulse, thereby causing undesirable noise. According to embodiments, other undesirable couplings are also possible, such as when the ultrasonic pulse is coupled between ultrasonic transducers directly through the flow meter body and / or is coupled into the side wall of the channel at a position close to the first ultrasonic transducer via the flow meter body, and then coupled back out of the channel and into the flow meter body at another position close to the second ultrasonic transducer, causing further stray signals.

[0009] Undesirable noise caused by transmission through the flow meter body and / or channel sidewalls typically arrives at the receiving ultrasonic transducer in priority to the ultrasonic pulse reflected in the channel. Therefore, previously known mitigation techniques have included time filters, in which the receiving ultrasonic transducer filters out (i.e., ignores) signals received before the earliest expected arrival time of the ultrasonic pulse reflected in the channel, and filters out signals received after the latest expected arrival time of the ultrasonic pulse. However, time filters have the significant disadvantage that only the most direct noise paths are eliminated thereby. More complex noise paths are possible (e.g., the ultrasonic pulse is coupled into the flow meter body after the first reflection in the channel), which cannot be eliminated by time filters.

[0010] This is of particular relevance for ultrasonic flow meters, which consider not only a single primary reflection off the channel back wall (i.e., the wall opposite the flow meter), but also multiple reflected pulses. This is because the receiving ultrasonic transducer must "listen" for an extended period of time so that all ultrasonic pulses from all multiple paths are received, and also because some of the received ultrasonic pulses will at least partially overlap each other. In this case, a simple time filter as described above is of little use, because the period of listening is much longer than the simple case described above where only a single reflected pulse is considered.

[0011] In an embodiment, the acoustic decoupling element has a cylindrical shape (e.g., at least partially a hollow cylindrical shape or a sleeve shape), at least partially enclosing an ultrasonic transducer to which it is attached, and the ultrasonic transducer is attached to the flow meter body through the acoustic decoupling element. The acoustic decoupling element can be made of any material suitable for the intended use of the flow meter, in particular depending on the type of fluid in the channel.

[0012] Preferably, the acoustic decoupling element also acts as a gasket or seal to prevent any fluid from leaking out of the channel and into the flow meter through the gap between the flow meter body and the ultrasonic transducer.

[0013] In an embodiment, there is at least one air gap between at least a portion of a particular acoustic decoupling element and the ultrasonic transducer. Alternatively or additionally, there is at least one air gap between at least a portion of a particular acoustic decoupling element and the flow meter body. The air gap may be implemented by one or more protrusions as described herein. The air gap may be open to the interior of the passage or flow meter body, or the air gap may be closed, thereby forming an air pocket between the acoustic decoupling element and the ultrasonic transducer or between the acoustic decoupling element and the flow meter body.

[0014] According to an embodiment, the acoustic decoupling element comprises a porous material, and the one or more air gaps are formed by means of the porous material.

[0015] The air gap has the advantage of providing another (additional) acoustic impedance transition, e.g. from the acoustic decoupling element to air, and vice versa, since the acoustic decoupling element has a different acoustic impedance than air. This further serves to attenuate (i.e. weaken) the ultrasonic pulses travelling between the flow meter body and the ultrasonic transducer.

[0016] In an embodiment, at least one of the acoustic decoupling elements comprises a protrusion on the inner surface of the specific acoustic decoupling element. The protrusion is, for example, arranged on the radial inner surface of the hollow cylindrical acoustic decoupling element. Additionally or alternatively, at least one of the acoustic decoupling elements comprises a protrusion on the outer surface of the specific acoustic decoupling element. The protrusion is, for example, arranged on the radial outer surface of the hollow cylindrical acoustic decoupling element.

[0017] The protrusion is, for example, a longitudinal rib (on the inner and / or outer surface of the acoustic decoupling element) extending parallel to the cylindrical axis of the ultrasonic transducer, the ultrasonic transducer having a cylindrical (preferably circular cylindrical) shape extending from a first end to a second end, the first end having the membrane. The protrusion is, for example, also a transverse ring, for example extending in a circumferential direction around the inner or outer surface of the acoustic decoupling element. The protrusion is designed to couple the acoustic decoupling element to the ultrasonic transducer and / or to couple the acoustic decoupling element to the flow meter body.

[0018] In an embodiment, at least one of the acoustic decoupling elements comprises or is made of an elastomer or a thermoplastic or thermosetting polymer. For example, the elastomer is silicone. This has the additional advantage of having a high acoustic impedance relative to the flow meter body, which is typically injection molded from one or more thermoplastic or thermosetting polymers.

[0019] In an embodiment, the ultrasonic flow meter comprises a circuit board, and at least one of the acoustic decoupling elements abuts against the circuit board. In particular, a first end of the acoustic decoupling element opposite to the second end facing the channel abuts against the circuit board. This has the further benefit of acoustically isolating the ultrasonic transducer from the circuit board. Further, the second end may at least partially abut against the flow meter body. Thereby, the acoustic decoupling element is held between the flow meter body and the circuit board. In a further embodiment, the circuit board is coupled to the ultrasonic transducer only via the acoustic decoupling element.

[0020] In an embodiment, the ultrasonic transducer extends beyond the acoustic decoupling element in the direction of the channel. Advantageously, the ultrasonic transducer extends beyond the acoustic decoupling element in the direction of the channel by at least 2 mm. More advantageously, the ultrasonic transducer extends beyond the acoustic decoupling element in the direction of the channel by 2 mm-5 mm.

[0021] In an embodiment, the ultrasonic transducer is at least flush with the inner wall of the channel or extends in the direction of the channel. Advantageously, the ultrasonic transducer extends 0 mm-5 mm into the channel. In an embodiment, the ultrasonic transducer has a symmetrical polar radiation characteristic.

[0022] In an embodiment, the ultrasonic transducer has a central axis, and at least one of the ultrasonic transducers has an asymmetric polar radiation characteristic about the central axis of the transducer. The inner surface of the acoustic decoupling element can be additionally configured to cooperate with the outer surface of a specific ultrasonic transducer. The outer surface of the acoustic decoupling element is configured to cooperate with the flow meter body so that the ultrasonic transducer has a predetermined polar angle with respect to the flow meter body. Therefore, during the manufacture of the flow meter, the ultrasonic transducer is easily oriented in the correct manner. According to an embodiment, an asymmetric radiating ultrasonic transducer can be installed so that when installed in a channel, the radiation emitted along the central axis of the channel away from the central axis of the transducer is relatively more obvious than the radiation emitted along the direction transverse to the central axis of the channel away from the central axis of the transducer (or vice versa).

[0023] In an embodiment, the flow meter body comprises at least one sealing element arranged around at least one of the ultrasonic transducers, the sealing element being configured to seal the ultrasonic flow meter to the channel when the ultrasonic flow meter is secured to the channel. The sealing element is arranged on the flow meter body around the ultrasonic transducer. The sealing element is preferably circular, such as an elastic annular seal disposed in an annular recess of the flow meter body.

[0024] In an embodiment, the sealing element comprises a gasket, such as a rubber gasket.

[0025] In an embodiment, the sealing element consists of foam.

[0026] In an embodiment, the sealing element is an injection molded thermoset or thermoplastic polymer, preferably co-molded with the flow meter body.

[0027] In an embodiment, the ultrasonic transducers are arranged asymmetrically about the transverse centerline of the flow meter body. Thus, the ultrasonic transducers are arranged so that the midpoint of the line between the ultrasonic transducers does not coincide with the center of the surface of the flow meter body facing the channel. In particular, the midpoint is further upstream in the flow direction than the center point.

[0028] In an embodiment, the flow meter body comprises a housing having a substantially flat bottom wall having at least one opening for receiving at least two ultrasonic transducers directly or through an acoustic decoupling element. When the flow meter is installed, the bottom wall is expected to face the channel through which the fluid flow is measured. Preferably, there are at least two openings in the bottom wall for receiving each of the at least two ultrasonic transducers directly or through at least one acoustic decoupling element. More preferably, there are at least two openings for receiving each of the at least two ultrasonic transducers through at least two acoustic decoupling elements. When the flow meter is installed, the bottom wall preferably physically contacts the channel, for example directly or by means of a sealing element arranged on the underside of the bottom wall. These embodiments have the advantage of allowing simple assembly of the ultrasonic flow meter, because the ultrasonic transducer and the flow meter body are structurally integrated in a single unit, and therefore only a single unit must be assembled during manufacturing. This provides a further advantage of simple and time-saving installation of the flow meter body on the channel, because only a single unit must be installed.

[0029] In an embodiment, the ultrasonic transducer has a shape having a substantially flat bottom surface. The central axis of each ultrasonic transducer is perpendicular to the bottom surface of the corresponding ultrasonic transducer. Preferably, the central axis of the ultrasonic transducer extends perpendicular to the bottom wall of the flow meter body housing. Preferably, the central axes of the ultrasonic transducers are parallel to each other. These embodiments have the advantage of allowing simple assembly and / or attachment of the ultrasonic transducer in the flow meter body.

[0030] Alternatively or additionally, the flow meter body comprises a substantially rectangular cuboid housing having at least one opening for receiving at least one ultrasonic transducer through the acoustic decoupling element. This embodiment also has the advantage of allowing simple assembly and / or attachment of the ultrasonic flow meter to the channel, since only a single unit has to be assembled and installed.

[0031] Alternatively or in addition, the flow meter body comprises a housing having a main compartment formed by a wall, the main compartment comprising at least a bottom wall and a plurality of side walls interconnected with the bottom wall, each side wall extending at an angle (e.g., vertically) from the edge of the bottom wall. An ultrasonic transducer is arranged in the main compartment, and at least one ultrasonic transducer is attached to at least one opening of the bottom wall by at least one acoustic decoupling element. When the flow meter is installed, the bottom wall faces the channel through which the fluid flow is measured. Preferably, two of the side walls are structurally interconnected with two opposite edges of the bottom wall, and the two side walls together with the bottom wall form a U-shaped structure around the main compartment. More preferably, the bottom wall is rectangular, and the four side walls are structurally interconnected with the four edges of the bottom wall, and the four side walls together with the rectangular bottom wall form a basin structure, which provides or forms at least part of the main compartment. Preferably, the side walls and the bottom wall can be formed integrally. Preferably, the main compartment is hollow. These embodiments also have the advantage of allowing simple manufacture of the flow meter body.

[0032] Alternatively or in addition, the bottom wall has at least one tubular extension defining at least one ultrasonic transducer opening and extending from the bottom wall of the flow meter body into the main compartment of the flow meter body, each tubular extension being configured to receive an ultrasonic transducer, wherein each ultrasonic transducer is at least partially sheathed in an acoustic decoupling element at least partially arranged in the tubular extension. Preferably, the tubular extension is arranged flush with the bottom wall. Preferably, the tubular extension extends only into the main compartment. Preferably, the tubular extension and the bottom wall are integrally formed, for example, as a single injection molded part. Preferably, there are at least two tubular extensions, the two tubular extensions being designed to accommodate two ultrasonic transducers, respectively. Preferably, the ultrasonic transducers are at least partially sheathed in two acoustic decoupling elements, respectively. The tubular extension may have a circular, preferably circular or elliptical cross section. These embodiments have the advantage of allowing simple manufacture of the flow meter body and simple assembly of the ultrasonic transducers.

[0033] Alternatively or additionally, at least one ultrasonic transducer is separated from the tubular extension by at least one acoustic decoupling element, the acoustic decoupling element being an insert in the bottom wall opening, which in turn is configured to receive the ultrasonic transducer. Preferably, the acoustic decoupling element has a central axis substantially parallel to the central axis of the ultrasonic transducer. More preferably, the central axis of the acoustic decoupling element and the central axis of the corresponding ultrasonic transducer coincide.

[0034] Alternatively or additionally, the acoustic decoupling element is tubular with a varying diameter and / or cross-sectional area. For example, the acoustic decoupling element has at least two regions of different diameter and / or cross-sectional area along its central axis (which is located in the axial direction). In particular, the acoustic decoupling element has at least two regions of different inner diameter, outer diameter and / or wall thickness. Alternatively and / or additionally, the acoustic decoupling element has at least two regions of different internal cross-sectional area and / or external cross-sectional area, wherein the internal cross-sectional area is defined by the internal contour of the tubular acoustic decoupling element and the external cross-sectional area is defined by the external contour of the tubular acoustic decoupling element. Alternatively or additionally, the acoustic decoupling element comprises steps such that the external cross-sectional area and / or the average distance of the external cross-sectional area from its central axis decreases substantially when moving along the central axis of the acoustic decoupling element from the upper end of the acoustic decoupling element toward the lower end of the acoustic decoupling element. The upper end is the end facing the main compartment, and the lower end is the end located at or near the bottom wall of the housing. Alternatively or additionally, the acoustic decoupling element comprises at least one alignment element, which may be formed as one or more protrusions and / or one or more recesses. The alignment element may extend at least partially in a radial direction beyond the tubular extension. The alignment element may extend inwardly at the upper end, at least partially to a central hollow region of the tubular shape of the acoustic decoupling element. Alternatively or additionally, the acoustic decoupling element comprises an edge extending outwardly at the upper end to abut against the tubular extension. Alternatively or additionally, the acoustic decoupling element comprises an edge extending inwardly at the upper end to abut against the ultrasonic transducer. These embodiments have the advantage of allowing simple assembly of the flow meter body, the acoustic decoupling element and the ultrasonic transducer.

[0035] In an embodiment, the main compartment of the flow meter body accommodates at least one circuit board and / or at least one electronic component. Preferably, the main compartment accommodates at least two circuit boards, which are preferably arranged stacked on top of each other. This allows a sufficiently large total circuit board area to be provided for all necessary circuits and electronic components, while requiring a relatively small footprint (i.e., two-dimensional cross-sectional area) and / or total volume of the main compartment compared to arranging the circuits on a single larger circuit board, thereby also resulting in a relatively small footprint and / or total volume of the flow meter body.

[0036] In an embodiment, the ultrasonic flow meter further comprises a control module configured to determine and store the transmission time of ultrasonic pulses propagating in the flow direction and against the flow direction along more than one path between the ultrasonic transducers. The control module is further configured to use the transmission time to determine the fluid flow rate.

[0037] In addition to the flow meter, the present disclosure also relates to a flow control system comprising a channel, a baffle system having a baffle valve arranged in the channel, and an ultrasonic flow meter as described herein. The ultrasonic flow meter is fixed to the channel and arranged upstream of the baffle system.

[0038] In an embodiment, the flow control system further comprises a control module configured to determine and store the transit times of ultrasonic pulses propagating in the flow direction and against the flow direction along more than one path in the channel. The flow control system is configured to use the transit times to determine the fluid flow rate.

[0039] In an embodiment, the control module is further configured to receive a flow set point and control a damper actuator connected to the damper valve according to the flow set point and the determined fluid flow rate. Thus, the flow set point is reached, for example using a control loop.

[0040] In an embodiment, the control module is arranged in the baffle system, in the ultrasonic flow meter, or as a separate device connected to the baffle system and the ultrasonic flow meter. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] The disclosure described herein will be more fully understood from the detailed description given below and the accompanying drawings, which should not be construed as limiting the disclosure described in the appended claims.

[0042] In the attached figure:

[0043] Figure 1 A block diagram schematically illustrating a flow meter having two ultrasonic transducers is shown;

[0044] Figure 2 shows a block diagram schematically illustrating a flow control system including a flow meter, a channel, and a baffle system;

[0045] Figure 3 A block diagram is shown schematically illustrating in cross-sectional side view a channel for conveying a fluid with an ultrasonic flow meter and an optional baffle system attached thereto;

[0046] Figure 4 A block diagram is shown schematically illustrating in cross-sectional top view a channel for conveying a fluid with an ultrasonic flow meter and an optional baffle system attached thereto, the flow meter having two ultrasonic pulse reflection paths;

[0047] Figure 5 A block diagram is shown schematically illustrating in cross-sectional top view a channel for conveying a fluid to which an ultrasonic flow meter and an optional baffle system are attached in an alternative arrangement, the flow meter having two ultrasonic pulse reflection paths;

[0048] Figure 6 A block diagram is shown schematically illustrating in cross-sectional side view a flow meter having two ultrasonic transducers, each attached via an acoustic decoupling element;

[0049] Figure 7a A block diagram schematically illustrates a portion of a flow meter in a cross-sectional side view, depicting a single ultrasonic transducer having an acoustic decoupling element without an air gap and flush with the acoustic decoupling element; and

[0050] Figure 7b A block diagram is shown schematically illustrating a portion of a flow meter in a cross-sectional side view, depicting a single ultrasonic transducer having a plurality of air gaps between an acoustic decoupling element and the ultrasonic transducer and between the acoustic decoupling element and a flow meter body, with the ultrasonic transducer being flush with the acoustic decoupling element;

[0051] Figure 7c A block diagram schematically illustrating a portion of a flow meter in a cross-sectional side view depicting a single ultrasonic transducer having an acoustic decoupling element without an air gap and extending from the acoustic decoupling element in a channel direction; and

[0052] Figure 7d A block diagram is shown schematically illustrating a portion of a flow meter in a cross-sectional side view, depicting a single ultrasonic transducer having a plurality of air gaps between an acoustic decoupling element and the ultrasonic transducer and between the acoustic decoupling element and a flow meter body, and the ultrasonic transducer extending from the acoustic decoupling element in a channel direction;

[0053] Figure 8 A perspective view illustrating an acoustic decoupling element is shown;

[0054] Fig. 9 shows a perspective view illustrating an ultrasonic transducer partially enclosed in an acoustic decoupling element; and

[0055] Fig.10 A bottom view illustrating a flow meter body having a recess for securing an ultrasonic transducer having an acoustic decoupling element is shown; and

[0056] Fig.11 Shown are recorded signals of a transmission signal of a certain amplitude from the ultrasonic transducers 11 , 11A, 11B at an exit angle of 0° for two different relative extensions of the ultrasonic transducers 11 , 11A, 11B from the acoustic decoupling elements 12 , 12A, 12B, respectively. DETAILED DESCRIPTION

[0057] Reference will now be made in detail to certain embodiments, examples of which are illustrated in the accompanying drawings, in which some, but not all, features are shown. Indeed, the embodiments disclosed herein may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will satisfy applicable legal requirements. Whenever possible, like reference numerals will be used to refer to like components or parts.

[0058] exist Figure 1-Figure 5 In the figure, reference numeral 1 refers to an ultrasonic flow meter for measuring a fluid (e.g., air) flow rate Φ through a channel 2; in particular, an HVAC ultrasonic flow meter for heating, ventilation, and air conditioning (HVAC). The channel 2 is, for example, a gas (air) duct, a gas (air) pipe, or a gas (air) inlet channel. The channel 2 has a cross-sectional profile of, for example, a circular, square, or rectangular shape. Figure 3-Figure 6 In the illustrated embodiment, the channel 2 has a circular cross-sectional profile with a diameter D. The ultrasonic flow meter 1 includes one or more ultrasonic flow meter units fixed to the channel 2, for example, arranged on the wall of the channel 2. The ultrasonic flow meter 1 includes a flow meter body 10 and at least two ultrasonic transducers 11, 11A, 11B, which are attached to the flow meter body 10 and are configured to transmit ultrasonic pulses into the channel 2 and receive ultrasonic pulses in the channel 2 along one or more paths, including a direct path (i.e. without any intermediate reflection) and / or a reflected path (i.e. via one or more reflection points).

[0059] In an embodiment, the ultrasonic flow meter 1 comprises two separate flow meter units having separate flow meter bodies 10, each having at least one ultrasonic transducer 11, 11A, 11B, the flow meter units being electrically connected to each other.

[0060] like Figure 3-Figure 5 As shown, the ultrasonic transducers 11, 11A, 11B are configured to receive at least one reflection of an ultrasonic pulse in the channel 2, specifically, the reflection of the ultrasonic pulse on one or more reflection points P1, P21, P22 on the inner wall 20 of the channel 2, and propagate along the reflection paths R1, R2 via the one or more reflection points P1, P21, P22. Figure 4 and Figure 5As shown, one or more ultrasonic transducers 11, 11* are arranged on opposite walls of the channel 2 so that ultrasonic pulses can be transmitted and received via a direct path D1. The one or more ultrasonic transducers 11, 11* can also transmit and receive ultrasonic pulses via an indirect path (e.g., R3), in which the ultrasonic pulses are reflected once from the side walls of the channel 2. As described above, the one or more ultrasonic transducers 11, 11* on the opposite walls of the channel 2 are preferably in a separate flow meter unit having a separate flow meter body 10.

[0061] like Figure 1-Figure 8 and Fig.10 As shown, (one or more) ultrasonic transducers 11, 11A, 11B are at least partially arranged in an acoustic decoupling element 12, 12A, 12B. The acoustic decoupling elements 12, 12A, 12B are preferably designed to have a shape (e.g., a cylindrical shape) that is form-fitted around the ultrasonic transducers 11, 11A, 11B. In particular, the cylindrical shape of the acoustic decoupling elements 12, 12A, 12B corresponds to the cylindrical shape of the ultrasonic transducers 11, 11A, 11B. More specifically, the acoustic decoupling elements 12, 12A, 12B are designed so that the inner surface of the acoustic decoupling elements 12, 12A, 12B is at least partially form-fitted with the outer surface of the ultrasonic transducers 11, 11A, 11B. In particular, the ends of the ultrasonic transducers 11, 11A, 11B that transmit or receive ultrasonic pulses from the channel will remain at least partially unobstructed by the acoustic decoupling elements 12, 12A, 12B.

[0062] Further, the acoustic decoupling element 12, 12A, 12B is preferably designed to have or at least partially form a shape fit with the flow meter body 10. Thus, since no part of the body of the ultrasonic transducer 11, 11A, 11B is in direct contact with the flow meter body 10, the ultrasonic transducer 11, 11A, 11B is acoustically decoupled from the flow meter body 10.

[0063] That is, the ultrasonic transducers 11, 11A, 11B are electrically connected to at least another part of the flow meter 1 (e.g., the circuit board 15) (e.g., by means of a Figure 8 In another example, the ultrasonic transducers 11, 11A, 11B are mechanically and electrically connected to the flow meter 1, in particular the circuit board 15, via two electrical pins.

[0064] In the following description, reference is mainly made to the reflected paths R1, R2 via one or more reflection points P1, P21, P22; however, those skilled in the art will appreciate that multiple direct paths D1, multiple reflected paths R1, R2, or a combination of one or more direct paths D1 and one or more reflected paths R1, R2 may be used to implement multiple paths for measuring the transmission time of an ultrasonic pulse that propagates at least partially along the flow direction f and against the flow direction f. Preferably, at least one path is a reflected path R1, R2.

[0065] In an embodiment, the baffle system 4 is arranged in the channel 2. Figures 3 to 6 As shown, the baffle system 4 includes a baffle blade 40 arranged in the channel 2, which can rotate about a rotation axis r to adjust the orifice of the channel 2 and thereby regulate the fluid flow rate Φ through the channel 2. The baffle system 4 and its baffle blades 40 are arranged in the channel 2 downstream of the ultrasonic flow meter 10 and its ultrasonic transducers 11, 11A, 11B. The rotation axis r of the baffle blade 4 divides the cross section of the channel 2 into two halves H1, H2.

[0066] like Figure 4 , Figure 5 As shown, in one of the two halves H1, herein defined as the upper half H1, the baffle blade 40 can move downstream along the flow direction f. In the other of the two halves H2, herein defined as the lower half H2, the baffle blade 40 can move upstream u against the flow direction f. The ultrasonic transducers 11A, 11B are arranged on the same side of the channel 2 forming either of the two halves H1, H2.

[0067] exist Figure 5 In the illustrated embodiment, the ultrasonic transducers 11A, 11B are arranged on one side of the channel 2 forming the lower half H2, i.e., the side where the baffle blades 40 can move upstream u against the flow direction f. Figure 2 , Figure 4 and Figure 6 As shown, the ultrasonic transducers 11A, 11B are arranged on the side of the channel 2 forming the upper half H1, i.e., the side where the baffle blades 40 can move downstream along the flow direction f. Of course, the baffle blades 40 can also move in the opposite direction to facilitate limiting the flow f.

[0068] exist Figure 3In Fig. 7, reference numeral 5 refers to a flow control system, also known as a variable air volume (VAV) system (also known as a "VAV device" or "VAV box"), for heating, ventilation and air conditioning (HVAC), which flow control system 5 includes an ultrasonic flow meter 1 and a damper system 4. The flow control system 5 controls the amount of air at a given set point typically received from an external device or system. The set point can be derived from any mathematical combination of the temperature and / or measured flow of the supply and / or return air (and in the room (e.g., from room sensors)). The room sensors can include temperature, humidity and / or CO2 sensors.

[0069] like Figure 3 , Figure 4 As illustrated, the ultrasonic transducers 11A, 11B are arranged on the same side of the channel 2 along a longitudinal arrangement axis a running parallel to the central axis of the channel 2 .

[0070] like Figure 3-Figure 5 As shown, the ultrasonic transducer 11B arranged downstream in the flow direction f is arranged at a defined distance L from the baffle blade 40. More specifically, the ultrasonic transducer 11B is arranged at a distance L between its central axis c and a cross-sectional plane q / r passing through the baffle blade 40 in the closed position. Preferably, the defined distance L from the downstream ultrasonic transducer 11B is in the range of 75% to 250% of the diameter D of the passage 2, more preferably in the range of 140% to 200%.

[0071] In an embodiment, the ultrasonic transducers 11A, 11B are arranged asymmetrically about the transverse centerline b of the flow meter 1 (particularly the flow meter body 10). In particular, the ultrasonic transducer 11B downstream in the flow direction f is arranged closer to the centerline b of the flow meter 1 than the ultrasonic transducer 11A upstream in the flow direction f. This has the benefit of allowing the flow meter 1 to be fixed closer to the baffle system 4 while still maintaining the distance L between the downstream flow meter 11B and the baffle blades 40. This results in a more compact flow control system 1, so that the flow control system 1 can be installed in places where space is more restricted.

[0072] In further embodiments, the baffle system 40 includes a baffle actuator 3 having a motor coupled to the baffle blade 40 to drive the baffle blade 40 in all possible positions between an open and closed position to regulate fluid flow in the channel 2 .

[0073] like Figure 1-Figure 5 As shown, the flow measurement system 1 further comprises a control module 14 connected to the ultrasonic transducers 11, 11A, 11B of the ultrasonic flow meter 10. Figure 1-Figure 5As shown, the control module 14 is arranged in the ultrasonic flow meter 10, for example, arranged in a common housing together with the ultrasonic transducers 11A, 11B, or arranged outside the ultrasonic flow meter 10, separated from the ultrasonic transducers 11, 11A, 11B, for example, arranged in or on the housing of the actuator 3 of the baffle system 4. In an embodiment, the control module 14 is connected to the actuator 3 of the baffle system 4, for controlling the operation of the actuator 3 or its motor, respectively, such as driving the baffle blades 40 to adjust the orifice of the channel 2 and control the fluid flow rate Φ passing through the channel 2.

[0074] The control module 14 includes electronic circuitry and is configured to perform various functions and steps as described in more detail below. According to an embodiment, the electronic circuitry of the control module 14 is controlled by software program code stored on a computer-readable non-transitory computer medium, the electronic circuitry may include an application specific integrated circuit (ASIC), and / or the electronic circuitry includes discrete electronic components.

[0075] like Figure 3-5 As shown in the figure, the ultrasonic transducers 11, 11A, 11B of the ultrasonic flow meter 10 are not only arranged and configured to transmit ultrasonic pulses into the channel 2, but also arranged and configured to receive reflections of ultrasonic pulses from reflection points P1, P21, P22 on the inner wall 20 of the channel 2 and propagating along corresponding reflection paths R1, R2. Figure 3-Figure 5 The diagram shows a reflection path R1 of an ultrasonic pulse having a single reflection at a single reflection point P1 on the inner wall 20 of the channel 2, and a reflection path R2 of an ultrasonic pulse having a double reflection R2 at two reflection points P21, P22 on the inner wall 20 of the channel 2. However, additional reflection paths of ultrasonic pulses having three or more reflections at three or more reflection points on the inner wall 20 of the channel 2 can be detected by the receiving ultrasonic transducers 11, 11A, 11B, just as emitted by the transmitting ultrasonic transducers 11, 11A, 11B of the ultrasonic flow meter 10.

[0076] The control module 14 or its electronic circuit is respectively configured to control the ultrasonic transducers 11 , 11A, 11B to emit one or more ultrasonic pulses.

[0077] The control module 14 or its electronic circuit is also configured to receive from the ultrasonic transducers 11 , 11A, 11B, respectively, a reflection of one of the plurality of ultrasonic pulses detected by the corresponding ultrasonic transducer 11 , 11A, 11B.

[0078] The control module 14 or its electronic circuit is also configured to determine and store the transmission time of the ultrasonic pulse along the reflection path R1, R2 from the transmitting ultrasonic transducer 11, 11A, 11B via one or more reflection points P1, P21, P22 on the inner wall 20 of the channel 2 to the receiving ultrasonic transducer 11, 11A, 11B.

[0079] The control module 14 or its electronic circuit is further configured to respectively follow one or more reflection paths R1, R2 via one or more reflection points P1, P21, P22 on the inner wall 20 of the channel 2, using the downstream transmission time t of the ultrasonic pulse propagating in the flow direction f. down and the upstream transmission time t of the ultrasonic pulse propagating in the countercurrent direction f up Specifically, by calculating the corresponding downstream transmission time t of the ultrasonic pulse propagating from the transmitting ultrasonic transducer 11, 11A, 11B to the receiving ultrasonic transducer 11, 11A, 11B along the specific reflection path R1, R2, the fluid flow rate (such as gas flow Φ) is determined. down and upstream transmission time t up The time difference is averaged, and the gas flow rate Φ is determined according to the average speed of the ultrasonic pulse on the specific reflection paths R1 and R2. For example, the fluid flow rate Φ is the volume flow rate (m 3 / h) or mass flow rate (kg / sec).

[0080] To improve accuracy, the control module 14 or its electronic circuit is configured to use the downstream transmission time t of the ultrasonic pulse along more than one reflection path R1, R2, respectively. down and upstream transmission time t up To determine the gas flow Φ, for example, along the reflection path R1, there is a single reflection at a reflection point P1, and along one or more other reflection paths R2, there are multiple reflections at more than one reflection point P21, P22. For example, according to the downstream transmission time t of the ultrasonic pulse along the multiple reflection paths R1, R2 down and upstream transmission time t up The fluid velocity or flow rate Φ determined by the measurement is averaged. In an embodiment, a (weighted) average is used, for example using a correction or weighting factor derived from the flow distribution of channel 2. For the latter example, the control module 14 or its electronic circuit is respectively configured to determine the flow distribution in channel 2, such as laminar, Poiseuille, turbulent or other flow distribution, based on the transmission time of the ultrasonic pulse measured in channel 2 via multiple different paths R1, R2. In an embodiment, the control module 14 or its electronic circuit is respectively configured to determine the fluid flow rate Φ using the determined flow distribution, for example by multiplying the determined flow rate Φ (or the measurement of the transmission time) by a correction factor that depends on the determined flow distribution.

[0081] In an embodiment, the control module 14 or its electronic circuitry, respectively, is configured to further use the detected reflected signal strength, ie, the signal strength of the ultrasonic pulses received and detected by the ultrasonic transducers 11 , 11A, 11B via the reflection paths R1 , R2 , to determine the fluid flow rate Φ.

[0082] For example, the control module 14 or its electronic circuit is respectively configured to exclude the transmission time of the ultrasonic pulse received via the specific reflection path R1, R2 from determining the fluid flow rate Φ if the specific reflection signal strength value is lower than the set threshold value, which indicates that the dirt or debris deposited at the corresponding reflection point P1, P21, P22 position causes contamination. In an embodiment, the control module 14 or its electronic circuit is respectively configured to generate an alarm if the signal strength of the ultrasonic pulse received via all paths is lower than a defined threshold value, for example, set to 25% of the ultrasonic pulse signal strength value emitted by the corresponding ultrasonic transducer 11, 11*, 11A, 11B. For example, the alarm is sent to the operator via a wired or wireless communication network.

[0083] Alternatively or additionally, the control module 14 or its electronic circuitry, respectively, is configured to determine the fluid flow rate Φ using the average value of the transit times or their contribution to determining the fluid flow rate Φ, respectively, for example further applying a correction factor determined according to the flow distribution in the channel 2 .

[0084] In an embodiment, the control module 14 may be configured to detect reverse flow of fluid and generate an alarm if reverse flow of fluid in the channel 2 is detected.

[0085] The control module 14 may be configured to regulate the fluid flow. This is accomplished by moving the damper blades 40 to modify the fluid flow in the channel 2 until the measured fluid flow is equal to or within a tolerance range of a defined set point. The set point may be defined using a message received from an input, such as a digital or analog input of the flow control system 5 (particularly the flow meter 1). The set point may be related to the flow velocity, volume flow and / or heat flow of the fluid.

[0086] The flow meter 1 may additionally comprise one or more status indicators, in particular in the form of one or more LEDs, which are configured to indicate via a specific color of the LEDs and / or via one or more flashing patterns the status of the flow meter 1. In particular, the power status and the communication status may be indicated.

[0087] In an embodiment, the control module 14 is further configured to receive a blade position of a baffle blade 40 from the baffle system 4. The baffle system 4 may be operated in a "slave" mode, i.e., wherein the flow meter 1 controls the baffle system 4, in particular the baffle blade 40. Preferably, the control module 14 controls the blade position of the baffle blade 40 in a closed-loop control. Additionally, the control module 14 may be configured to compensate the signal received by the ultrasonic transducers 11, 11A, 11B according to the blade position using a compensation curve stored in the control module 14 as part of the calibration parameters. As discussed herein, the calibration parameters may be adjusted. This may allow a reduction in the distance L between the downstream ultrasonic sensor 11B and the baffle blade 40, thereby allowing a more compact flow measurement system 4.

[0088] The control module 14 also includes a wireless communication module configured for short-range wireless communication, in particular using RFID, such as NFC and / or Bluetooth. The control module 14 is configured to receive data from a mobile communication device (such as a smart phone) and / or transmit data to it via the wireless communication module. For example, the data received from the mobile communication device includes configuration parameters and / or calibration parameters. For example, configuration parameters related to the commissioning of the flow meter 1 and / or the baffle system 4. For example, calibration parameters are related to sensor calibration. The data transmitted to the mobile communication device includes, for example, configuration parameters and / or calibration data, but may also include device identification information of the flow meter 1 and / or the baffle system 4, including, for example, a device serial number and / or a device type.

[0089] The flow control system 5, in particular the flow meter 1 and / or the baffle system 4, can also be configured to measure additional parameters in addition to the fluid flow rate. The flow control system 5 can use ultrasonic transducers 11, 11A, 11B to measure these additional parameters (for example, the speed of sound in the fluid can be determined using the transmission time), or include additional sensors such as temperature sensors, humidity sensors and / or CO2 sensors. Using these additional sensors, not only directly measured parameters such as temperature, humidity and / or CO2 concentration in the fluid can be provided, but also parameters derived therefrom, in particular including heat flow in the fluid. In an embodiment, the flow control system 1, in particular the flow meter 1, includes an additional temperature output interface (i.e., an analog and / or digital interface).

[0090] The control module 14 may also be configured with a counter function that may be configured to record various measured parameters over time, in particular the cumulative volume / mass of fluid flow.

[0091] like Figure 1 , Figure 2 , Figure 6 Figure 7 Figure 8 , Fig.10As shown, at least one of the ultrasonic transducers 11, 11A, 11B of the ultrasonic flow meter 1 is attached to the flow meter body 10 via an acoustic decoupling element 12, 12A, 12B. Preferably, each ultrasonic transducer 11, 11A, 11B is attached to the flow meter body 10 via an acoustic decoupling element 12, 12A, 12B.

[0092] The acoustic decoupling elements 12, 12A, 12B are designed to attenuate sound waves passing through the acoustic decoupling elements 12, 12A, 12B, in particular sound waves in the ultrasonic frequency range, i.e. above 20 kHz. Preferably, the acoustic decoupling elements 12, 12A, 12B have an acoustic impedance that is different from the acoustic impedance of any component of the flow meter 1 that contacts the acoustic decoupling elements 12, 12A, 12B. These components in particular include the ultrasonic transducers 11, 11A, 11B and the flow meter body 1. Further, these components may include a circuit board of the flow meter 1, wherein the ultrasonic transducers 11, 11A, 11B are connected to the circuit board.

[0093] By attenuating sound waves, the acoustic decoupling elements 12 , 12A, 12B reduce the noise detected by the ultrasonic transducers 11 , 11A, 11B when receiving ultrasonic pulses from the channel.

[0094] Preferably, the acoustic decoupling elements 12, 12A, 12B are made of an elastic material, such as rubber or silicone.

[0095] Especially if Figure 6 As shown, the flow meter 1 is mounted to the channel 2, in particular, attached to the outer wall 21 of the channel 2. The outer wall 21 of the channel has channel openings 22A, 22B, preferably circular openings, in which the flow meter 1 is mounted so that the ultrasonic transducers 11A, 11B of the flow meter 1 transmit and receive ultrasonic pulses to and from the channel 2 through the channel openings 22A, 22B, respectively.

[0096] The flow meter 1 has a flow meter body 10 designed to house the components of the flow meter 1. In particular, the flow meter body 10 includes one or more printed circuit boards 15, 15A, 15B, which include electrical traces and are designed to electrically connect the ultrasonic transducers 11A, 11B to various electronic components of the flow meter 1, in particular to the control module 14. For the sake of simplicity, additional electronic components are not shown, including electronic devices for powering various components of the flow meter 1 and optionally also the baffle system 4. The additional electronic components may also include protection circuits to protect the electronic components of the flow meter 1 and / or the baffle system 4 from electrostatic discharge. The ultrasonic transducers 11A, 11B may be connected to at least one of the circuit boards 15A, 15B by one or more wiring and / or connectors (not shown).

[0097] In the embodiment, the flow meter 1 comprises two circuit boards 15A, 15B, such as Figure 6 As shown. The first circuit board 15A is preferably arranged adjacent to the ultrasonic transducers 11A, 11B, and includes analog circuits and / or digital circuits, in particular circuits related to the ultrasonic transducers 11A, 11B. For example, the first circuit board 15A includes circuits necessary for transmitting and receiving ultrasonic pulses from the ultrasonic transducers 11A, 11B and for digital signal processing of ultrasonic pulses. The second circuit board 15B preferably includes components related to the control module 14 and is configured to implement at least some of the steps and / or functions described herein. The second circuit board 15B also includes circuits for communication, in particular a wireless communication module, and is also configured to perform data communication using a data bus. A reverse arrangement is also possible.

[0098] The circuit board 15, preferably the first circuit board 15A, has one or more openings 151. Each opening 151 is adjacent to a specific ultrasonic transducer 11, 11A, 11B so that a cable 112, preferably a twisted pair cable 112 connected to the specific ultrasonic transducer 11, 11A, 11B, can pass through the circuit board 15 for electrically connecting the specific ultrasonic transducer 11, 11A, 11B to a plug or socket attached to a side of the circuit board 15 opposite to the specific ultrasonic transducer 11, 11A, 11B.

[0099] The space between the ultrasonic transducers 11 , 11A, 11B, the acoustic decoupling elements 12 , 12A, 12B and the circuit board 15A is preferably filled with a curable potting material 125 .

[0100] The flow meter body 10 has two ultrasonic transducer openings 101A, 101B, preferably circular openings, which are configured to receive ultrasonic transducers 11A, 11B when attached to acoustic decoupling elements 12A, 12B. The ultrasonic transducer openings 101A, 101B are used to allow ultrasonic pulses to be transmitted into the channel 2 and received from the channel 2.

[0101] The ultrasonic transducers 11A, 11B are designed to transmit ultrasonic pulses into the channel, however, it is inevitable that at least some of the acoustic energy of the transmitted and / or received ultrasonic pulses is coupled into the flow meter body 10. This acoustic energy is transmitted from the transmitting ultrasonic transducer 11A to the receiving ultrasonic transducer 11B by the flow meter body 10, or the received ultrasonic pulses are coupled into the flow meter body 10 near the ultrasonic transducers 11, 11A, 11B, and from there into the ultrasonic transducers 11, 11A, 11B, causing a reduction in the signal-to-noise ratio. The acoustic decoupling elements 12A, 12B attenuate the signal by absorbing the acoustic energy, and also reflect the acoustic energy due to the sudden change in acoustic impedance caused by the strong difference in material properties between the acoustic decoupling elements 12A, 12B and the flow meter body 10 and between the acoustic decoupling elements 12A, 12B and the ultrasonic transducers 11A, 11B.

[0102] As depicted, the acoustic decoupling elements 12A, 12B are cylindrical in shape (e.g., annular cylindrical, sleeve-shaped) and are designed to achieve shape adaptation with the ultrasonic transducers 11A, 11B, which are typically also cylindrical in shape. The acoustic decoupling elements 12A, 12B may additionally have a base 122 that extends radially inward toward the cylindrical axis c of the cylindrical shape and optionally also extends radially outward away from the cylindrical axis c. The bottom of the base 122 abuts against the circuit board 15 and thereby also provides a convenient way to mount the ultrasonic transducers 11A, 11B in the flow meter body 10.

[0103] The acoustic decoupling elements 12A, 12B also serve to seal the flow meter body 10 from the ingress of fluids (eg, gases).

[0104] In an embodiment, the ultrasonic transducers 11, 11A, 11B are arranged such that they extend out of the flow meter body 10, in particular into the channel 2, as shown in FIG. Figure 7a , Figure 7b For example, the ultrasonic transducers 11, 11A, 11B are configured to extend 1 mm-10 mm, preferably 1 mm-5 mm, from the flow meter body 10. Preferably, the ultrasonic transducers 11, 11A, 11B are configured to extend out of the flow meter body 10 so that the emitting surface of the ultrasonic transducer extends into the channel by 0-5 mm, preferably 0-2 mm.

[0105] Figure 6 , Figure 7a , Figure 7b , Figure 7c and Figure 7dAlso shown are optional sealing elements 13A, 13B, which are arranged on the outside of the flow meter body 10 around the ultrasonic transducer openings 101A, 101B in the flow meter body 10. The sealing elements 13A, 13B seal the flow meter body 10 on the channel 2 so that no fluid can leak out of the openings 22A, 22B. Additionally, the sealing elements 13A, 13B further acoustically isolate the flow meter body 10 from the channel 2, thereby reducing any acoustic energy transmitted between the ultrasonic transducers 11A, 11B via the channel 2. This further attenuates any acoustic energy traveling between the flow meter body 10 and the channel 2.

[0106] In the embodiment, the sealing elements 13A, 13B are annular and are centered on the ultrasonic transducers 11A, 11B. The sealing elements 13A, 13B are preferably mounted / arranged in the recesses 102A, 102B of the flow meter body 10 (eg, Fig.10 The sealing elements 13A and 13B are preferably made of an elastomer.

[0107] In an embodiment, the sealing elements 13A, 13B are co-molded with the flow meter body 10 .

[0108] Figure 7a Shows Figure 6 Detailed view of area C in the figure. Figure 7b Shows Figure 6 Alternative embodiment of region C ( Figure 6 1 ), wherein the acoustic decoupling element 12 has transverse ribs 121, so that there is an air gap between the flow meter body 10 and the acoustic decoupling element 12 and between the acoustic decoupling element 12 and the ultrasonic transducer 11. The air gap further increases the noise isolation.

[0109] In an embodiment, the acoustic decoupling element 12 comprises a foam having a plurality of enclosed air pockets and also forming small air gaps on the inner and / or outer surfaces when installed.

[0110] The flow meter 1 includes an input cable connected to the flow meter body 10 by an attachment mechanism, which is configured to slidably engage with the flow meter body 10 to secure the input cable. The input cable is configured to provide power to the flow meter 1 (e.g., a two-wire power supply including a 24V supply AC or DC power and GND). The input cable also includes one or more data lines for controlling the flow meter 1 and / or the baffle system 4.

[0111] The signals are received and transmitted by the flow meter 1 via the data line(s). The signals may comprise analog and / or digital signals.

[0112] Depending on the embodiment, the input signals may be received as analog and / or digital signals and the output signals may be transmitted as analog and / or digital signals.

[0113] The analog signal is, for example, a variable voltage (eg, 0V to 10V, or 2V to 10V).

[0114] The digital signals are preferably communicated using a data bus. For example, the data bus is Modbus RTU (RS485), BACnet MS / TP (RS458) or MP bus.

[0115] Additionally, the flow meter 1 includes a baffle system connection cable, which is configured to provide power and control signals to the baffle system 4 .

[0116] In an embodiment, the ultrasonic transducers 11, 11A, 11B are arranged such that they extend beyond the acoustic decoupling element 12, 12A, 12B, in particular in the direction of the channel 2, such as Figure 7c , Figure 7d For example, the ultrasonic transducers 11, 11A, 11B are arranged such that they extend 1 mm to 10 mm, preferably 2 mm to 5 mm, most preferably 2 mm from the acoustic decoupling elements 12, 12A, 12B.

[0117] Preferably, the ultrasonic transducers 11, 11A, 11B are arranged so that they extend beyond the acoustic decoupling elements 12, 12A, 12B so that when the flow meter is mounted, the bottom end of the ultrasonic transducer, i.e. the emitting surface of the ultrasonic transducer, is flush with the inner wall of the channel or extends into the channel 2, preferably extending a distance of up to 10 mm, preferably a distance of 5 mm.

[0118] Arranging the ultrasonic transducers 11, 11A, 11B such that they extend beyond the acoustic decoupling elements 12, 12A, 12B provides a positive effect of improving signal quality (e.g., related to overall signal-to-noise ratio, envelope side steepness, signal rise and fall times, signal shortness, etc.), as described below Fig.11 As described.

[0119] In an embodiment, Figure 8 As shown, the acoustic decoupling elements 12, 12A, 12B have one or more internal alignment elements 123. These internal alignment elements 123 are, for example, one or more protrusions and / or recesses and / or steps on the inner surface at defined angular positions (i.e. defined by a specific polar angle with respect to the cylinder axis c).

[0120] The one or more internal alignment elements 123 are designed to mechanically cooperate with at least partially complementary alignment elements (e.g., recesses or protrusions, respectively) on the outer surface of the ultrasonic transducers 11A, 11B so that the ultrasonic transducers 11A, 11B have a defined angular position (in particular a defined polar angle) with respect to the acoustic decoupling elements 12A, 12B.

[0121] Additionally, the acoustic decoupling elements 12A, 12B have one or more external alignment elements 124. These external alignment elements 124 are, for example, one or more protrusions and / or recesses on the outer surface at defined angular positions. These external alignment elements 124 are designed to cooperate with at least partially complementary alignment elements (e.g., recesses and / or protrusions, respectively) of the flow meter body 10, so that the final ultrasonic transducers 11A, 11B have a defined angular position (in particular a defined polar angle) with respect to the flow meter body 10. This is particularly beneficial in the case where the ultrasonic transducers 11A, 11B have asymmetric polar radiation characteristics.

[0122] like Fig. 9 As shown, the ultrasonic transducer 11 is arranged inside the acoustic decoupling element 12 so that when it is installed in the flow meter 1, it is held in place only by the acoustic decoupling element 12, so that there is no direct mechanical connection between the flow meter body 10 and the ultrasonic transducer 11. The transverse ribs 121 are circular protrusions on the outside (and optionally also on the inside) of the acoustic decoupling element 121, which further reduce the contact area between the acoustic decoupling element 12 and the flow meter body 10 (and for the inside ribs, also reduce the contact area between the acoustic decoupling element 12 and the ultrasonic transducer 11). The acoustic decoupling element 12 has a cylindrical shape with a base 122.

[0123] In embodiments where a particular acoustic decoupling element 12 has transverse ribs 121 on the inside and outside, it is preferred that a given transverse rib 121 on the inside does not have a corresponding transverse rib 121 on the outside at the same position relative to the centerline c. In other words, the transverse ribs 121 on the inside and outside are displaced longitudinally (i.e., in the direction of the centerline c) relative to each other.

[0124] According to an embodiment, base 122 may include potting material 125 introduced into a recess formed after inserting ultrasonic transducer 11 into the cylindrical portion of acoustic decoupling element 11. Potting material 125 is preferably silicone and prevents axial movement of ultrasonic transducer 11 along central axis c.

[0125] The ultrasonic transducer 11 is connected to the circuit board 15 through a twisted pair cable 112 and a plug 113 .

[0126] like Fig.10As shown, the bottom of the flow meter body 10 is generally flat and substantially rectangular, and includes two ultrasonic transducer openings 101A, 101B. The annular recesses 102A, 102B for the sealing elements 13A, 13B are arranged centered on the ultrasonic transducer openings 101A, 101B, and have a diameter larger than the ultrasonic transducer openings 101A, 101B.

[0127] Fig.11 The recorded signals of the transmitted signal of a certain amplitude from the ultrasonic transducer 11, 11A, 11B at an exit angle of 0° are shown for two different relative extensions of the ultrasonic transducer 11, 11A, 11B from the acoustic decoupling element 12, 12A, 12B, respectively. The left figure shows the signal amplitude for the scenario where the acoustic decoupling element 12, 12A, 12B is flush with the ultrasonic transducer 11, 11A, 11B. The right figure shows the signal amplitude for the scenario where the ultrasonic transducer 11, 11A, 11B extends 2 mm from the acoustic decoupling element 12, 12A, 12B. The signal quality of the recorded signal in the right-hand figure is higher, that is, if the ultrasonic transducer 11, 11A, 11B extends from the acoustic decoupling element 12, 12A, 12B, the signal quality improves because the peak amplitude increases, the envelope sides are steeper, and the overall signal duration is shorter (which allows a more accurate determination of the signal arrival time).

[0128] The above-mentioned embodiments of the present disclosure are exemplary, and those skilled in the art appreciate that at least some of the components and / or steps described in the above-mentioned embodiments may be rearranged, omitted or introduced into other embodiments without departing from the scope of the present disclosure.

Claims

1. An ultrasonic flow meter (1) for measuring the flow of a fluid through a channel (2), the ultrasonic flow meter (1) comprising: a flow meter body (10), and at least two ultrasonic transducers (11, 11A, 11B) attached to the flow meter body (10), The ultrasonic transducer (11, 11A, 11B) is configured to transmit ultrasonic pulses into the channel and receive ultrasonic pulses in the channel (2), and When the flow meter body (10) is fixed to the channel (2), the ultrasonic transducers (11, 11A, 11B) are arranged at a certain distance from each other in the flow direction (f), Therein, at least one ultrasonic transducer (11, 11A, 11B) is attached to the flow meter body (10) via an acoustic decoupling element (12, 12A, 12B).

2. The ultrasonic flow meter (1) according to claim 1, wherein: The acoustic decoupling element(s) (12, 12A, 12B) has a cylindrical shape which at least partially surrounds the ultrasonic transducer (11, 11A, 11B).

3. The ultrasonic flow meter (1) according to any one of claims 1 or 2, wherein: At least one air gap exists between one or more of: at least a portion of a specific acoustic decoupling element (12, 12A, 12B) and the ultrasonic transducer (11, 11A, 11B), or between at least a portion of the specific acoustic decoupling element (12, 12A, 12B) and the flow meter body (10).

4. The ultrasonic flow meter (1) according to any one of claims 1 to 3, wherein: At least one of the acoustic decoupling elements (12, 12A, 12B) comprises a protrusion (121) located on an inner surface and / or an outer surface of the particular acoustic decoupling element (12, 12A, 12B).

5. The ultrasonic flow meter (1) according to any one of claims 1 to 4, wherein: At least one of the acoustic decoupling elements (12, 12A, 12B) comprises an elastomer or a thermoplastic or thermosetting polymer.

6. The ultrasonic flow meter (1) according to any one of claims 1 to 5, wherein: The ultrasonic flow meter (1) comprises a circuit board, and at least one of the acoustic decoupling elements (12, 12A, 12B) abuts against the circuit board.

7. The ultrasonic flow meter (1) according to any one of claims 1 to 6, wherein: The ultrasonic transducer (11, 11A, 11B) has a central axis (c), and at least one of the ultrasonic transducers (11, 11A, 11B) has an asymmetric polar radiation characteristic about the central axis (c), and wherein the inner surface of the acoustic decoupling element (12, 12A, 12B) is configured to cooperate with the outer surface of the specific ultrasonic transducer (11, 11A, 11B), and wherein the outer surface of the acoustic decoupling element (12, 12A, 12B) is configured to cooperate with the flow meter body (10), so that the ultrasonic transducer (11, 11A, 11B) has a predetermined polar angle relative to the flow meter body (10).

8. The ultrasonic flow meter (1) according to any one of claims 1 to 7, wherein: The flow meter body (10) includes at least one sealing element (13A, 13B) arranged around at least one of the ultrasonic transducers (11, 11A, 11B), the sealing element being configured to seal between the ultrasonic flow meter (1) and the channel (2) when the ultrasonic flow meter (1) is fixed to the channel (2).

9. The ultrasonic flow meter (1) according to claim 8, wherein: The sealing element (13A, 13B) is an injection molded thermosetting or thermoplastic polymer, preferably co-molded with the flow meter body (10).

10. The ultrasonic flow meter (1) according to any one of claims 1 to 9, wherein: The ultrasonic transducers (11, 11A, 11B) are arranged asymmetrically with respect to a transverse center line (b) of the flow meter body (10).

11. The ultrasonic flow meter (1) according to any one of claims 1 to 10, further comprising a control module (14), the control module (14) being configured to determine and store the transmission time of ultrasonic pulses propagating along the flow direction (f) and against the flow direction (f) along more than one path between the ultrasonic transducers (11, 11A, 11B), and use the transmission time to determine the fluid flow rate.

12. A flow control system (5), comprising a channel (2), a baffle system (4) having a baffle valve (40) arranged in the channel, and an ultrasonic flow meter (1) according to any one of claims 1 to 10, wherein the ultrasonic flow meter (1) is fixed to the channel and arranged upstream of the baffle system (4).

13. The flow control system (5) according to claim 12 further comprises a control module (14) configured to determine and store the transmission time of ultrasonic pulses propagating along the flow direction (f) and against the flow direction (f) along more than one path in the channel (2), and to determine the fluid flow rate using the transmission time.

14. The flow control system (5) according to claim 13, wherein: The control module (14) is further configured to receive a flow set point and control the flapper actuator based on the flow set point and the determined fluid flow rate to achieve the flow set point.

15. The flow control system (5) according to any one of claims 12 or 14, wherein: The control module (14) is arranged in the baffle system (4), in the ultrasonic flow meter (1), or is arranged as a separate device connected to the baffle system (4) and the ultrasonic flow meter (1).

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