1. An ultrasonic flowmeter based on an MEMS ultrasonic transducer chip is characterized by comprising a main pipeline, a branch pipeline, two MEMS ultrasonic components and a signal processing board, wherein the inlet end and the outlet end of the branch pipeline are respectively communicated to an inner cavity of the main pipeline along the fluid flowing direction in the main pipeline; a flow resisting structure matched with the sectional areas of the inlet end and the outlet end is formed between the inlet end and the outlet end of the branch pipeline in the main pipeline; two MEMS ultrasonic wave components are installed in the tributary pipeline, every MEMS ultrasonic wave component realizes based on MEMS ultrasonic transducer chip, and two MEMS ultrasonic wave transducer chip connect the signal processing board, and the propagation path of two MEMS ultrasonic wave components is predetermined measurement angle.

2. An ultrasonic flow meter according to claim 1, wherein each MEMS ultrasonic assembly comprises a MEMS ultrasonic transducer chip secured to a chip base, a chip base and an acoustically transparent protective cover secured to the chip base and spaced a predetermined distance from the MEMS ultrasonic transducer chip.

3. An ultrasonic flow meter according to claim 2, wherein the acoustically transparent protective cover is comprised of a waterproof acoustically transparent layer and a metallic braid.

4. An ultrasonic flow meter according to claim 1, wherein two component mounting openings are formed in the branch conduit, and two MEMS ultrasonic components are detachably disposed in the two component mounting openings, respectively.

5. An ultrasonic flow meter according to claim 1, wherein the tributary conduit is mounted above an outer surface of a housing of the main conduit, the signal processing board being mounted in a space between the tributary conduit and the housing of the main conduit.

6. The ultrasonic flowmeter of claim 5, wherein a circuit board protection box is arranged in a gap between the branch pipe and the housing of the main pipe, a press buckle is arranged inside the circuit board protection box, the signal processing board is arranged in a slot between a box bottom and the press buckle in the circuit board protection box, the box bottom and the press buckle fasten the signal processing board, and the MEMS ultrasonic component is connected with the signal processing board through an electrical connector on the circuit board protection box.

7. An ultrasonic flow meter according to any of claims 1 to 6, wherein the inner wall of the main conduit is inwardly convex between the inlet end and the outlet end of the branch conduit to form a venturi-type flow-obstructing structure.

8. The ultrasonic flow meter according to any one of claims 1 to 6, wherein a branch flow pipe rectifying baffle plate is further provided in the branch flow pipe, and a plate surface of the branch flow pipe rectifying baffle plate is parallel to the flow direction of the fluid.

9. An ultrasonic flow meter according to any of claims 1-6, wherein the branch flow conduit has a rectangular cross-section of its lumen perpendicular to the direction of flow.

10. An ultrasonic flow meter according to any of claims 1 to 6, wherein the branch flow pipe is at an inlet end of the branch flow pipe at 45 to 90 degrees to the direction of fluid flow in the main pipe.

Background

Most of the current ultrasonic flow meters measure flowing fluid based on a time-of-flight (TOF) algorithm, which calculates the flow velocity and the flow rate of the fluid by measuring the transmission time difference of two ultrasonic signals with opposite directions and the same transmission distance in the fluid, and the traditional ultrasonic flow meter based on the TOF algorithm adopts a ceramic ultrasonic transducer to transmit and receive the ultrasonic signals, and the size of the ceramic ultrasonic transducer is large (the diameter of a ceramic membrane for receiving the signals is usually in the centimeter scale), so that the size of the whole ultrasonic flow meter is large, and the integration degree is not high.

With the development of technology, MEMS ultrasonic transducer chips (of hundred micrometers) with tiny sizes are becoming popular, but if the MEMS ultrasonic transducer chips are directly applied to an ultrasonic flowmeter instead of a ceramic ultrasonic transducer, the following problems may occur: in practical application, the ultrasonic flowmeter needs to be capable of measuring fluid within a certain flow rate range, for example, according to the newly published GB/T39841-2021 standard, the measuring range span of the ultrasonic flowmeter for the common household or commercial gas meter is from 1.6m³H to 10m³Per, the minimum resolution needs to be 0.01m³The ceramic ultrasonic transducer has a large size, so that the influence of flow velocity change caused by flow rate change in the same pipeline cross section on whether signals can be received is small, but for an MEMS ultrasonic transducer chip with a small size, the ultrasonic transducer with a fixed distance cannot receive ultrasonic signals due to an overlarge change range of the flow velocity, and therefore the problem that the measurement accuracy is not high or even cannot be measured when the MEMS ultrasonic transducer chip is directly applied to the existing ultrasonic flowmeter is solved.

Disclosure of Invention

The invention provides an ultrasonic flowmeter based on an MEMS ultrasonic transducer chip aiming at the problems and technical requirements, and the technical scheme of the invention is as follows:

an ultrasonic flowmeter based on an MEMS ultrasonic transducer chip comprises a main pipeline, a branch pipeline, two MEMS ultrasonic components and a signal processing plate, wherein the inlet end and the outlet end of the branch pipeline are respectively communicated to the inner cavity of the main pipeline along the fluid flowing direction in the main pipeline; a flow resisting structure matched with the sectional areas of the inlet end and the outlet end is formed between the inlet end and the outlet end of the branch pipeline in the main pipeline; two MEMS ultrasonic wave components are installed in the branch pipeline, each MEMS ultrasonic wave component is realized based on an MEMS ultrasonic wave transducer chip, the propagation paths of the two MEMS ultrasonic wave components are in a preset measurement angle, and the two MEMS ultrasonic wave transducer chips are connected with the signal processing board.

The further technical scheme is that each MEMS ultrasonic component comprises an MEMS ultrasonic transducer chip, a chip base and an acoustically transparent protective cover, the MEMS ultrasonic transducer chip is fixed on the chip base, and the acoustically transparent protective cover is fixed on the chip base and is spaced from the MEMS ultrasonic transducer chip by a preset distance.

The sound-transmitting protective cover is further characterized by comprising a waterproof sound-transmitting layer and a metal woven layer.

The further technical scheme is that two component mounting openings are formed in the branch pipeline, and the two MEMS ultrasonic components are detachably arranged in the two component mounting openings respectively.

Its further technical scheme does, and the tributary pipeline is installed in the top of the casing surface of trunk line, and signal processing board installs in the space between the casing of tributary pipeline and trunk line.

The technical scheme is that a circuit board protection box is arranged in a gap between a branch pipeline and a shell of a main pipeline, a pressing buckle is arranged inside the circuit board protection box, a signal processing board is arranged in a slot between a box bottom and the pressing buckle in the circuit board protection box, the box bottom and the pressing buckle fasten the signal processing board, and an MEMS ultrasonic component is connected with the signal processing board through an electric connector on the circuit board protection box.

The further technical proposal is that the inner wall of the main pipeline is bulged inwards between the inlet end and the outlet end of the branch pipeline to form a Venturi tube type flow resisting structure.

The further technical scheme is that a branch pipeline rectifying clapboard is arranged in the branch pipeline, and the surface of the branch pipeline rectifying clapboard is parallel to the flowing direction of the fluid.

The further technical proposal is that the section of the inner cavity of the branch pipeline, which is vertical to the direction of the fluid, is rectangular.

The technical scheme is that the flow direction of the fluid in the branch pipeline and the main pipeline is 45-90 degrees at the inlet end of the branch pipeline.

The beneficial technical effects of the invention are as follows:

the application discloses ultrasonic flowmeter based on MEMS ultrasonic transducer chip, this ultrasonic flowmeter is based on MEMS ultrasonic transducer chip design, set up MEMS ultrasonic component in the tributary pipeline of intercommunication trunk line, the effect through the inside choked flow structure of trunk line reduces the fluid velocity of flow adjustment in the tributary pipeline to the applicable within range of MEMS ultrasonic transducer chip, make available MEMS ultrasonic transducer chip realize the flow measurement requirement of predetermined velocity of flow scope and precision demand, benefit from the small-size of MEMS chip simultaneously, whole ultrasonic flowmeter's compact structure is small and exquisite.

Drawings

Fig. 1 is a schematic perspective view of an ultrasonic flowmeter according to the present application.

Fig. 2 is a cross-sectional view of the structure shown in fig. 1 parallel to the direction of fluid flow.

Fig. 3 is a cross-sectional view of the structure shown in fig. 1 perpendicular to the direction of fluid flow.

Fig. 4 is an enlarged schematic view of a part of the structure in fig. 2.

Fig. 5 is a schematic perspective cross-sectional view of the structure shown in fig. 1 perpendicular to the direction of fluid flow.

Fig. 6 is a schematic view of an application scenario of the ultrasonic flow meter of the present application.

Detailed Description

The following further describes the embodiments of the present invention with reference to the drawings.

The application discloses an ultrasonic flowmeter based on MEMS ultrasonic transducer chip, as shown in fig. 1-5, the ultrasonic flowmeter includes a main pipeline 1, a branch pipeline 2, two MEMS ultrasonic components 3 and a signal processing board 4. The main pipe 1 has openings at both ends and is internally penetrated for fluid to flow through, the fluid may be gas, liquid or the like, the flow direction of the fluid in the main pipe 1 is from one end to the other end, the cross-sectional shape of the main pipe 1 perpendicular to the flow direction v of the fluid is not limited, and the illustrated rectangular shape is taken as an example.

The inlet end 21 and the outlet end 22 of the branch pipe 2 are respectively communicated to the inner cavity of the main pipe along the fluid flow direction v inside the main pipe 1, the inlet end 21 of the branch pipe 2 is located at the upstream position in the fluid flow direction, and the outlet end 22 is located at the downstream position.

Two MEMS ultrasonic components 3 are installed in tributary pipeline 2, every MEMS ultrasonic component 3 is realized based on MEMS ultrasonic transducer chip, the propagation path of two MEMS ultrasonic components 3 is predetermined measurement angle, thereby make the ultrasonic signal that an MEMS ultrasonic component 3 transmitted can be received by another MEMS ultrasonic component 3 through the reflection of tributary pipeline wall, thereby realize the measurement framework of TOF algorithm, this predetermined measurement angle is fixed according to TOF algorithm's measurement specification, for example, as shown in FIG. 2, two MEMS ultrasonic components 3's propagation path is the V-arrangement structure of predetermined contained angle, some conventional applications can set up in correlation formula structure etc. still, this application does not do the restriction. The two MEMS ultrasonic transducer chips are connected with the signal processing board 4 through resistance-capacitance wires.

Optionally, at the inlet end of the branch pipe 2, the branch pipe 2 and the fluid flowing direction θ in the main pipe 1 form 45-90 degrees, so that the design of pointing angle parameters of the MEMS ultrasonic transducer chip is not selected at the same time, fig. 2 takes θ as 45 degrees as an example, θ at different angles can adapt to MEMS ultrasonic transducer chips with different performances, and the ultrasonic signals emitted by the two MEMS ultrasonic assemblies 3 can be received by another opposite ultrasonic transducer assembly through 1-2 times of reflection on the wall surface of the branch pipe.

Preferably, the cross section of the inner cavity of the branch pipe 2 perpendicular to the fluid direction is rectangular, such as rectangular or square, because the reflection direction of the rectangular structure is relatively consistent, and if a circular pipe is adopted, scattering phenomenon is easy to occur. Optionally, two component mounting openings are formed in the branch pipeline 2, the two MEMS ultrasonic components 3 are detachably arranged in the two component mounting openings respectively, installation and replacement are facilitated, and when the two MEMS ultrasonic components 3 are plugged into the component mounting openings, the measurement requirement that the propagation path is a preset measurement angle can be met, so that debugging is facilitated. The removable mounting can be done by a pull-out type or a threaded nut type.

Optionally, each MEMS ultrasonic component 3 includes a MEMS ultrasonic transducer chip 31, a chip base 32, and an acoustically transparent protective cover 33, the MEMS ultrasonic transducer chip 31 is fixed on the chip base 32, and the acoustically transparent protective cover 33 is fixed on the chip base 32 and spaced from the MEMS ultrasonic transducer chip 31 by a predetermined distance. Further, the sound-transmitting protective cover 33 is composed of a waterproof sound-transmitting layer and a metal woven layer, so that the sound-transmitting protective cover 33 has a waterproof function besides sound transmission so as to be applied to a liquid measurement scene, the metal woven layer can effectively prevent dust, and corrosion of fluid to the MEMS ultrasonic transducer chip 31 is reduced.

Be formed with the choked flow structure that matches with the sectional area of entrance point 21 and exit end 22 between the entrance point 21 of main pipeline 1 internal tributary pipeline 2 and exit end 22, choked flow structure is in partly fluidic extrusion to the tributary pipeline 2 of connecting on main pipeline 1, because the fluidic area of choked flow structure separation is little makes tributary pipeline 2 entrance point 21 and exit end 22's pressure differential less, consequently, the fluid velocity that flows into in tributary pipeline 2 is also less, size through the sectional area of adjustment choked flow structure and entrance point 21 and exit end 22 realizes the matching, can reduce the fluid velocity range that flows into in tributary pipeline 2 to the MEMS ultrasonic transducer chip in being fit for tributary pipeline 2, thereby satisfy the measuring range of MEMS ultrasonic transducer chip. In one embodiment, as shown in fig. 2 and 3, the inner wall of the main pipe 1 protrudes inward between the inlet end 21 and the outlet end 22 of the branch pipe 2 to form a venturi-type flow blocking structure, and each of the wall inward protruding structures is as shown in fig. 2 and 1a of fig. 3, and typically, the inner wall of the main pipe 1 protrudes to the highest in the center of the inlet end 21 and the outlet end 22, and the highest protrusion forms a slope to the opening of the main pipe 1, so that the inner wall of the main pipe 1 slowly protrudes toward the normal direction of the pipe wall to form a flow blocking structure similar to the venturi structure.

Optionally, in order to realize more stable flow state in the tributary pipeline 2 under the prerequisite that does not influence the test so that improve the test accuracy, still be provided with tributary pipeline fairing partition plate 2a in the tributary pipeline 2, tributary pipeline fairing partition plate 2 a's face is on a parallel with the fluid flow direction, can set up a plurality of parallel spaced tributary pipeline fairing partition plate 2a as required in practice.

Optionally, the branch pipe 2 is installed above the outer surface of the housing of the main pipe 1 to avoid interference of solid particles such as dust, rust, etc. blown in from the fluid inlet of the main pipe 1 on the flow measurement.

In one embodiment, a space is formed between the branch pipe 2 and the housing of the main pipe 1, and the signal processing board 4 is installed in the space between the branch pipe and the housing of the main pipe. Further, signal processing board 4 does not directly peg graft in the space of two casings, is provided with circuit board protection box 5 in the space between the casing of tributary pipeline 2 and trunk line 1, and circuit board protection box 5 is inside to be provided with and presses knot 5a, and signal processing board 4 sets up in the slot between the box bottom in the circuit board protection box and the pressure knot 5a, and the box bottom fastens signal processing board 4 with the pressure knot 5a, prevents that signal processing board 4 from moving in-process vibration damage and leading to the inefficacy in the transportation. Further optionally, potting glue may be filled in the circuit board protection box 5 to protect the signal processing board 4. The MEMS ultrasound components 3 are connected to the signal processing board 5 by electrical connectors on the circuit board protection box 5, while the electrical connectors on the circuit board protection box 5 also support the powering of the two MEMS ultrasound components 3. In practical application, the signal processing board 4 and the circuit board protection box 5 may be fixed at other side walls of the main pipe 1, or integrated with circuits such as external power supply and the like of the flow meter case to process the sensing signal, or at other positions, which does not affect the implementation of the above structure.

An application schematic diagram of ultrasonic flowmeter of this application is shown in fig. 6, whole ultrasonic flowmeter A can place and assemble in the gas table case, the fluid outlet of trunk line 1 with ultrasonic flowmeter connects the conversion head of a square circle to be connected to outlet pipe 6 on, inlet pipe 7 directly flows into to gas table box 8 in, gas table box 8 only is as the buffer space in gas flow field, its appearance property does not have the influence to measurement accuracy, it can to reserve installation space for flow sensor inside, along with the gas inflow, unnecessary gas flows out and carries out the measurement of gas flow from this only export of ultrasonic flowmeter A.

What has been described above is only a preferred embodiment of the present application, and the present invention is not limited to the above embodiment. It is to be understood that other modifications and variations directly derivable or suggested by those skilled in the art without departing from the spirit and concept of the present invention are to be considered as included within the scope of the present invention.