Ultrasonic transducer and method of operating the same, ultrasonic flowmeter and method of operating the same

Abstract

An ultrasonic transducer (1), in particular for an ultrasonic flowmeter (3), is described and shown, wherein the ultrasonic transducer (1) has at least one electroacoustic element (7), at least one housing (5), at least one sound window (6) and at least one control unit (13), wherein the electroacoustic element (7) is arranged on the sound window (6) inside the housing (5) in such a way that, in operation, ultrasonic signals generated by the electroacoustic element (7) exit the housing (5) through the sound window (6). An implementation of the object of the ultrasonic transducer which ensures an improvement in the quality of the measurement signals and thus an increase in the measurement range is proposed in that the electroacoustic element (7) has at least two electroacoustic discs (10), wherein the at least two electroacoustic discs (10) are arranged one above the other and in that at least one electroacoustic disc (10) can be excited at least temporarily individually by the control unit (13).

Description

Technical Field

[0001] This invention is based on an ultrasonic transducer (or ultrasonic sensor, i.e., Ultraschallwandler) particularly for ultrasonic flow meters, wherein the ultrasonic transducer has at least one electroacoustic element, at least one housing, at least one acoustic window, and at least one control unit.

[0002] The electroacoustic element is arranged on the acoustic window inside the housing so that the ultrasonic signal generated by the electroacoustic element passes through the acoustic window and leaves the housing during operation.

[0003] Furthermore, the present invention relates to: a method for operating an ultrasonic transducer in a measurement environment; an ultrasonic flow meter having at least one measuring tube, at least one ultrasonic transducer, and at least one control and evaluation unit; and a method for operating the ultrasonic flow meter, wherein at least one ultrasonic transducer is configured at least as an ultrasonic transmitter, preferably as an ultrasonic transmitter and receiver, and wherein the ultrasonic transducer is arranged at the measuring tube such that it emits ultrasonic signals into the measuring tube along or against the flow direction of the flowing medium during operation. Background Technology

[0004] An ultrasonic transducer known from the prior art for determining the flow velocity of a medium flowing through a measuring tube emits an ultrasonic signal at a fixed frequency and a fixed beamwidth, independent of the current process conditions during operation.

[0005] In principle, the quality of an ultrasonic measurement signal transmitted through a medium depends on the medium's absorption characteristics, viscosity, and current process conditions. Effects that reduce the quality of the transmitted signal include, for example, signal attenuation through the medium or a blowing effect (or drift effect) at high flow rates when measuring flowing media. In the following text, the ultrasonic signal that has traversed the medium is referred to as the received signal. Summary of the Invention

[0006] To avoid or reduce the above-mentioned disadvantages, the object of the present invention is to provide an ultrasonic transducer that ensures improved quality of received signals.

[0007] Furthermore, the object of the present invention is to provide a method for operating an ultrasonic transducer, an ultrasonic flow meter, and a method for operating an ultrasonic flow meter, which respectively ensure the improvement of the quality of the received signal.

[0008] According to the first teaching of the present invention, the above objective is achieved by the following means: the electroacoustic element has at least two electroacoustic disks, wherein the at least two electroacoustic disks are arranged stacked one on top of the other, and wherein at least one electroacoustic disk can be excited individually by the control unit at least temporarily (or sometimes, i.e., zeitweise).

[0009] According to the present invention, the electroacoustic elements of an ultrasonic transducer can be modularly constructed, allowing the electroacoustic elements to be excited in different ways. This has the advantage that the characteristics of the ultrasonic signal generated during operation can be affected. Specifically, the characteristics of the ultrasonic signal can be matched to the characteristics of the medium and / or the current process conditions, thereby improving the quality of the received signal.

[0010] In operation, for example, exactly one electroacoustic disk can be excited to vibrate, wherein at least two electroacoustic disks are connected to each other such that a second electroacoustic disk vibrates accordingly, and as a result, the resonant frequency of the resonator (or resonator) formed by the electroacoustic elements is determined by the combination of at least two electroacoustic disks. Individual excitation within the scope of this invention does not mean that the individually excited electroacoustic disk vibrates freely on its own.

[0011] By designing and / or controlling the second electroacoustic disc, the resonant frequency of the electroacoustic components can be influenced as a whole, thereby altering the frequency of the generated ultrasonic signal. This will be explained in more detail below for different designs.

[0012] According to a preferred design, at least two electroacoustic disks can be controlled independently. In this case, the two electroacoustic disks are connected to the control unit individually (or separately, i.e., separately). During operation, the at least two disks can be excited, for example, differently. It is also conceivable that these electroacoustic disks are connected in parallel or in series, at least temporarily. Particularly preferably, the at least two electroacoustic disks are connected to the control unit in such a way that switching between different controls of the individual electroacoustic disks can be achieved during operation.

[0013] According to another design, the electroacoustic element is a piezoelectric element, i.e., an element made of piezoelectric ceramic material, and / or a micromechanical element of a capacitive micromechanical ultrasonic transducer. Furthermore, the electroacoustic disk is preferably a piezoelectric disk, i.e., a disk made of piezoelectric ceramic material, and / or a micromechanical disk of a capacitive micromechanical ultrasonic transducer. Other electroacoustic elements or disks are also conceivable for realizing this invention.

[0014] Particularly preferably, at least two electroacoustic disks each have a first and a second end face, wherein at least three electrodes are connected to an electroacoustic element, wherein at least one electrode is disposed on the end face of the first electroacoustic disk facing the acoustic window, wherein at least one electrode is disposed between the first and second electroacoustic disks, and wherein at least one electrode is disposed on the end face of the second electroacoustic disk facing away from the acoustic window.

[0015] If the electroacoustic disk is constructed substantially cylindrical (or zylinderförmig), then the end faces of the electroacoustic disk correspond to the opposing bases of the cylinder. These bases can be circular, or they can have polygonal or elliptical shapes.

[0016] According to one design, the first and / or second electroacoustic disks are polarized (or polarisiert) along the height direction of the cylinder. If the electrodes are positioned on the end faces, the electroacoustic disks vibrate longitudinally during operation and undergo mechanical deflection between the electrodes. Alternatively, lateral vibration excitation of the electroacoustic disks can also be achieved. In this case, the electrodes are arranged beside the electroacoustic element, and vibration perpendicular to the electrodes occurs when a voltage is applied.

[0017] Particularly preferably, at least two electrodes are provided on at least one end face of the first and / or second electroacoustic disc, wherein the at least two electrodes are different in their shape and / or their size.

[0018] Particularly preferably, these electrodes are geometrically configured such that the generated ultrasonic signal is rotationally symmetric. According to this design, the electrodes are particularly preferably circularly constructed. In particular, a circular design is advantageous in applications where a preferred orientation does not exist.

[0019] In addition to symmetrical beam shapes, asymmetrical beam shapes for ultrasonic signals can also be achieved through appropriate geometric design of the electrodes.

[0020] Particularly preferably, at least two electrodes are different in diameter.

[0021] For example, a first electrode, configured as a ring electrode, surrounds a second electrode located within the ring electrode. According to this design, the two electrodes are preferably constructed in a circular or elliptical shape. According to this design, the two electrodes can be controlled individually or in parallel during operation. According to one design, only the inner electrode can be controlled during operation, or the inner electrode can be controlled in parallel with the outer electrode. Similarly, it is conceivable to control only the outer ring electrode.

[0022] Furthermore, it is equally advantageous that at least three electrodes are arranged on the same end face of at least one electroacoustic disk, wherein at least two electrodes are constructed as nested ring electrodes, and one electrode is arranged as a substantially circular electrode inside the ring electrodes. In this combination, the electrodes can also be controlled individually or in parallel during operation.

[0023] When an electroacoustic disk is excited, the shape and / or size of the electrodes affect the shape of the generated ultrasonic signal.

[0024] If at least three individually controllable electrodes are excited differently during operation, the beam shape of the emitted ultrasonic signal can be matched, for example, to the medium being measured or the current measurement conditions.

[0025] This design has the advantage that the generated ultrasonic signal can be particularly flexibly matched to the measurement situation, thereby further improving the quality of the received signal.

[0026] Besides the ring electrode designed with built-in electrodes, other electrode shapes are also conceivable and advantageous. For example, multiple electrodes can exist on one end face, wherein each electrode used to adjust the beam shape, especially the beam width, of the emitted ultrasonic signal can be individually controlled and / or controlled in different combinations during operation.

[0027] According to another design, at least one electrode is elliptical in shape. Preferably, at least two electrodes are elliptical in shape, wherein at least one elliptical electrode surrounds at least one other elliptical electrode. According to this design, these electrodes can be controlled individually or in parallel.

[0028] According to another preferred design, there are multiple individually controllable electrodes, wherein the multiple electrodes are arranged on the same end face of at least one electroacoustic disk, and wherein the individual electrodes for adjusting the beam shape, and in particular the beam width, of the emitted ultrasonic signal can be controlled in different combinations during operation.

[0029] Within the scope of this invention, "multiple electrodes" is understood to mean at least three electrodes, at least four electrodes, or at least five electrodes.

[0030] These electrodes can be configured, for example, as hexagons and / or rectangles, preferably squares, thereby creating a grid (or raster) with individually controllable electrodes. According to this design, the controlled geometry can be adjusted with particular flexibility. Particularly preferred is a combination of seven or nineteen hexagonal honeycombs or a combination of four, six, nine, or twelve squares arranged on one end face. This design has the advantage of allowing for particularly flexible adjustment of the beam shape, and furthermore, it allows for the configuration of asymmetrical beam shapes in addition to symmetrical ones.

[0031] In this regard, the shape of the ultrasonic signal can be altered during operation by controlling different electrodes. Through alternative (or alternating) control of the two electrode geometries, switching between the two beamforms during operation can be advantageously achieved. This design offers the advantage that the resulting ultrasonic signal can be tailored particularly well to the current measurement conditions.

[0032] If the medium under test is a flowing medium, it is possible that the ultrasonic signal emitted into the medium may not reach the receiving unit due to the blowing effect. In this case, it is advantageous to increase the beamwidth, thereby enabling the detection of higher flow velocities. Furthermore, reducing the beamwidth of the generated ultrasonic signal can reduce the superposition of reflections and received signals at the surfaces of the measurement environment (e.g., at the inner wall of the measuring tube).

[0033] According to another preferred design, at least one electrode is configured as a ground electrode, wherein the ground electrode is preferably a common ground electrode used for at least two other electrodes. The ground electrode is particularly preferably arranged on the end face of the electroacoustic element facing the acoustic window. In this case, the ground electrode has the same potential as the housing. Particularly preferably, the ground electrode substantially completely covers the end face on which the ground electrode is arranged.

[0034] Furthermore, it is particularly preferred that at least one recess and / or at least one gap be arranged between at least two electrodes disposed on the end face. This design has the advantage of avoiding or at least reducing crosstalk between the individual electrodes during operation.

[0035] According to another preferred design, the control unit is constructed and connected to the electrodes such that at least two electrodes can be controlled, at least temporarily, with different phases and / or amplitudes. Particularly preferably, the at least two electrodes controlled with different phases and / or amplitudes are arranged on the same end face. This design has the advantage of influencing the direction of the emitted ultrasonic signal.

[0036] According to a particularly preferred design, at least two electroacoustic disks have substantially the same thickness. In the case of cylindrical disks, the thickness of the electroacoustic disk has the same meaning as the height of the disk.

[0037] Furthermore, it is advantageous that at least two electroacoustic disks have different thicknesses. For example, the electroacoustic disk used for excitation can be constructed to be thicker than the second electroacoustic disk arranged on that disk.

[0038] Similarly, it is conceivable that an electroacoustic element has multiple electroacoustic disks, which are partially of the same thickness and / or partially of different thicknesses. These disks can operate in parallel or in series.

[0039] According to another preferred design, at least two electroacoustic discs are made of the same material. For example, at least two electroacoustic discs are constructed of piezoelectric ceramic.

[0040] Furthermore, it is preferable that at least two electroacoustic discs are made of different materials.

[0041] Particularly preferably, at least one electroacoustic disc is connected to an adjustable load, particularly an inductive and / or capacitive load. During operation, by applying the load, the acoustic impedance can be transferred to this electroacoustic disc, which affects the vibration of another actively excited electroacoustic disc. As a result, the resonant frequency of the entire electroacoustic element can be changed, and thus the frequency of the generated ultrasonic signal can be altered. During operation, the frequency of the generated ultrasonic signal can then be matched, for example, to minimize absorption through the medium.

[0042] Similarly, it is conceivable to apply different loads to multiple electroacoustic discs.

[0043] For example, the adjustable load can be constructed as a gyrator. Furthermore, the load can be a high-impedance load. Additionally, the load can be connected to a switch such that it can be switched on as needed during operation. According to this design, switching between two different frequencies of emission can be particularly easy during operation.

[0044] According to the second teaching of the present invention, the object stated at the beginning is achieved by the method mentioned at the beginning for operating an ultrasonic transducer in a measurement environment in such a way that the ultrasonic transducer is constructed according to one of the aforementioned designs.

[0045] The ultrasonic transducer transmits ultrasonic signals into the medium, and...

[0046] The electroacoustic element, particularly at least one electroacoustic disc, is controlled based on the viscosity of the medium and / or the absorption of the generated ultrasonic signal by the medium.

[0047] When it is said that the electroacoustic element is controlled according to the viscosity of the medium and / or according to the absorption of the generated ultrasonic signal by the medium, it means that when the viscosity of the medium is below a limit value, the electroacoustic disk is controlled such that the ultrasonic signal has a first frequency, and if the viscosity is above the limit value, the electroacoustic disk is controlled such that the ultrasonic signal has a second frequency.

[0048] Alternatively or additionally, the transmission of the ultrasonic signal through the medium can be determined at at least two frequencies to be achieved, wherein the electroacoustic element is controlled such that the ultrasonic signal is emitted at a frequency in which absorption is minimized.

[0049] Particularly preferably, the ultrasonic transducer can switch between two frequencies during operation, for example, between 1 MHz and 2 MHz.

[0050] For example, the method used to operate the ultrasonic transducer can be used to measure the flow rate of a flowing medium, or it can be used to measure the liquid level.

[0051] In principle, the medium (in which the ultrasonic signal is emitted) can be a liquid or a gas.

[0052] According to the third teaching of the present invention, the object proposed at the beginning is achieved by the ultrasonic flow meter described at the beginning in such a way that at least one ultrasonic transducer is constructed according to one of the above designs.

[0053] According to a preferred design, at least two ultrasonic transducers are provided, wherein the two ultrasonic transducers are configured as an ultrasonic transmitter and as an ultrasonic receiver, and wherein the two ultrasonic transducers are configured according to one of the designs described above. In terms of the design of the electroacoustic elements, the two ultrasonic transducers can be constructed identically. Alternatively, the structures of the electroacoustic elements of the two ultrasonic transducers can be different.

[0054] According to one design, the ultrasonic transducer varies in the number and / or geometry of the electrodes.

[0055] Particularly preferably, the control and evaluation unit stores the relationship between the viscosity of the medium and / or the absorption of ultrasonic signals by the medium and the control of electroacoustic components.

[0056] Preferably, the ultrasonic flow meter has another sensor unit for detecting the viscosity of the medium.

[0057] According to another design, the relationship between the flow rate and / or viscosity of the test medium or the suppression (or damping, attenuation, i.e., Dämpfung) of the ultrasonic signal by the test medium and the control of the electrodes is stored in the control and evaluation unit.

[0058] According to the fourth teaching of the present invention, the object stated at the beginning is achieved by the method for operating the ultrasonic flow meter described at the beginning, in such a way that the ultrasonic flow meter is constructed according to one of the above designs, and at least one ultrasonic transducer is operated according to one of the above methods.

[0059] According to one design, the ultrasonic flow meter according to the invention has at least two ultrasonic transducers, wherein the two ultrasonic transducers are configured as an ultrasonic transmitter and an ultrasonic receiver, wherein the two ultrasonic transducers are configured according to one of the above-described designs, wherein the two ultrasonic transducers are configured identically in terms of electroacoustic element design, and wherein the two ultrasonic transducers are identically controlled during operation.

[0060] In detail, the two ultrasonic transducers are controlled so that they emit the same frequency. According to this design, the ultrasonic transducers operate at the same frequency in both transmit and receive modes.

[0061] According to another design of the method, a first ultrasonic transducer transmits an ultrasonic signal having a first frequency f1, and a second ultrasonic transducer transmits an ultrasonic signal having a second frequency f2. According to this design, the ultrasonic transducers operate at different frequencies in transmit and receive modes. Specifically, the first ultrasonic transducer operates in receive mode such that it receives frequency f2, and the second ultrasonic transducer operates in receive mode such that it receives frequency f1.

[0062] According to another design, the control and evaluation unit controls at least two electrodes based on at least one state variable, wherein the control of at least two electrodes is changed during operation based on at least one state variable.

[0063] The relevant state variables here are the flow rate of the fluid and / or the viscosity of the fluid and / or the absorption of the ultrasonic signal by the fluid.

[0064] According to one design, the amplitude and / or spectrum of the received signal are analyzed by a control and evaluation unit. Electrodes connected to the electroacoustic element are controlled based on the value of the transmitted (or emitted, transmitted, i.e., transmitted) intensity and / or the spectrum of the received signal.

[0065] Here, the limiting value for switching the control of the electrodes depends on the medium being measured. Since gases have a lower speed of sound than liquids, resulting in a longer propagation time for sound waves, the dispersing effect in gaseous media is significantly stronger than in liquid media. Therefore, the limiting value for switching to a wider beam shape is preferably lower in gaseous media than in liquid media.

[0066] In addition, at least one additional sensor may be present to measure at least one other state variable of the system, such as the viscosity of the medium.

[0067] According to a preferred design, at least two electrodes arranged on the same end face of the electroacoustic disk are controlled in parallel, at least temporarily. This design allows for particularly flexible adjustment of the beam shape.

[0068] Furthermore, it is preferable that at least two electrodes are controlled at least temporarily with different phases and / or different amplitudes. Especially at high flow velocities, the direction of the emitted ultrasonic signal can be influenced such that the emitted ultrasonic signal oscillates (or rotates, i.e., geschwenkt) against the flow direction. For this purpose, for example, at least two electrodes arranged sequentially in the flow direction are controlled temporally staggered against the flow direction. Thus, the scattering effect can be advantageously counteracted (or resisted, i.e., entgegengewirkt) by the oscillation of the ultrasonic signal.

[0069] According to another preferred design of the method, there are at least two ultrasonic transducers, wherein the at least two ultrasonic transducers are configured as ultrasonic transmitters and as ultrasonic receivers, and wherein the two ultrasonic transducers are configured according to one of the above designs, wherein the two ultrasonic transducers are configured identically in terms of the design of electroacoustic elements, and wherein the two ultrasonic transducers are controlled identically during operation.

[0070] Alternatively, the two ultrasonic transducers can also have different electroacoustic elements, and / or can be controlled during operation to have different frequencies and / or different beamwidths. This design has the advantage of increasing the overall bandwidth of the flow measurement.

[0071] According to another design, the ultrasonic transducers operate differently in transmitting and receiving operations. For example, these ultrasonic transducers can emit ultrasonic signals with a small beamwidth and then operate in such a way, through switching control, that they have a wider acoustically effective receiving surface. Attached Figure Description

[0072] Numerous feasible solutions exist for designing and improving the ultrasonic transducer according to the invention, the ultrasonic flow meter according to the invention, and the method according to the invention. Reference is made to the claims, which are dependent on the independent claims, and to the following description of embodiments in conjunction with the accompanying drawings. In the figures:

[0073] Figure 1a An ultrasonic transducer known from the prior art is shown;

[0074] Figure 1b This illustrates a piezoelectric element known from the prior art;

[0075] Figure 2 A first embodiment of the electroacoustic element according to the present invention is shown;

[0076] Figure 3 Another embodiment of the electroacoustic element according to the present invention is shown;

[0077] Figure 4 Another embodiment of the electroacoustic element according to the present invention is shown;

[0078] Figure 5 Another embodiment of the electroacoustic element according to the present invention is shown;

[0079] Figure 6 Another embodiment of the electroacoustic element according to the present invention is shown;

[0080] Figure 7 Another embodiment of the electroacoustic element according to the present invention is shown;

[0081] Figure 8 Another embodiment of the electroacoustic element according to the present invention is shown;

[0082] Figures 9a-9c A top view of other electroacoustic elements according to the present invention;

[0083] Figure 10 An embodiment of the ultrasonic flow meter according to the present invention is shown;

[0084] Figure 11 An embodiment of a method for operating an ultrasonic transducer according to the present invention is shown; and

[0085] Figure 12 An embodiment of a method for operating an ultrasonic flow meter according to the present invention is shown. Detailed Implementation

[0086] Figure 1a An ultrasonic transducer 1, known in the prior art, is shown, suitable for application in an ultrasonic flow meter 3. The ultrasonic transducer 1 has a housing 5 and an acoustic window 6. Furthermore, an electroacoustic element 7, designed as a piezoelectric element, is arranged on the acoustic window 6. During operation, a voltage is applied to the electroacoustic element 7, thereby causing it to vibrate. This vibration, transmitted through the acoustic window 6, generates an ultrasonic signal in the medium arranged in front of the acoustic window 6 during operation.

[0087] Figure 1bThe electroacoustic element 7 is shown in an enlarged view. Electrodes 9 are arranged on the end face 8 of the electroacoustic element 7, and a voltage for exciting the electroacoustic element 7 is applied to these electrodes during operation. In principle, the shape of the electrodes 9 determines the shape of the ultrasonic signal emitted by the electroacoustic element 7, especially the width of the ultrasonic cone. The frequency of the generated ultrasonic signal depends on the height of the electroacoustic element. Typically, the electroacoustic element is excited to vibrate in resonance. Here, the electroacoustic element vibrates such that the height of the electroacoustic element corresponds to an integer multiple, preferably an odd multiple, of half a wavelength.

[0088] Figure 2 A first embodiment of an electroacoustic element 7 according to the present invention is shown, which is designed as a piezoelectric element. The electroacoustic element 7 has two electroacoustic discs 10 in the form of piezoelectric disks. In the illustrated embodiment, the electroacoustic discs 10 have the same thickness and the same material. Furthermore, the electroacoustic discs 10 can be individually controlled during operation. Specifically, a voltage can be applied to each of these electroacoustic discs 10. In this regard, the same voltage can be applied to these electroacoustic discs 10 during operation, or different voltages can be applied.

[0089] Figure 3 Another embodiment of the electroacoustic element 7 in the form of a piezoelectric element is shown, wherein the electroacoustic element 7 also has two electroacoustic disks 10 of the same thickness. Instead of controlling each electroacoustic disk 10 individually, these electroacoustic disks 10 can also be excited together.

[0090] Figure 4 Another embodiment of an electroacoustic element 7 in the form of a piezoelectric element is shown, wherein the electroacoustic element 7 has two electroacoustic disks 10 in the form of piezoelectric discs. During operation, the lower electroacoustic disk is excited by applying a voltage. The upper disk is connected to an electrical load 11, which affects the vibration of the upper electroacoustic disk 10 during operation. The combined resonant frequency of the two electroacoustic disks 10 can be tuned (or detuned, i.e., verstimmt) during operation in such a way that it can also match the frequency of the generated ultrasonic signal.

[0091] Figure 5 An embodiment of an electroacoustic element 7 according to the invention, in the form of a piezoelectric element, is shown, wherein the electroacoustic element 7 has two electroacoustic disks 10 in the form of piezoelectric disks. (Compared to...) Figures 2 to 4 The embodiments shown differ in that the electroacoustic discs 10 have different thicknesses. The lower electroacoustic disc 10 has a thickness d2, which is greater than the thickness d1 of the upper electroacoustic disc.

[0092] exist Figure 6Another embodiment of the electroacoustic element 7 in the form of a piezoelectric element is shown, wherein the electroacoustic element 7 comprises three electroacoustic disks 10 in the form of piezoelectric discs. The illustrated embodiment is designed such that, during operation, a voltage for exciting the electroacoustic element 7 is applied to the middle electroacoustic disk 10, which has a greater thickness d2 than the two outer electroacoustic disks 10. The two outer electroacoustic disks are each connected to an adjustable load, through which the vibration of the combination of the three electroacoustic disks can be influenced during operation.

[0093] Figure 7 Another embodiment of an electroacoustic element 7 in the form of a piezoelectric element is shown, wherein the electroacoustic element 7 has two electroacoustic disks 10 in the form of piezoelectric discs. Each electroacoustic disk 10 has an upper end face 8 and a lower end face 8, wherein the electroacoustic disks 10 are interconnected via the upper end face 8 of the lower electroacoustic element 10 and the lower end face 8 of the upper electroacoustic element 10. An electrode 9 configured as a ground electrode is arranged on the lower end face 8 of the lower electroacoustic disk 10. This electrode serves as a ground electrode for all other electrodes 9 connected to the electroacoustic element 7. An outer ring electrode 9 and another electrode arranged inside the ring electrode 9 are present on the upper end face 8 of the lower electroacoustic disk 10. A plurality of hexagonal electrodes 9 are arranged on the upper end face 8 of the upper electroacoustic disk, which can be controlled individually or in parallel during operation.

[0094] During operation, one or two electroacoustic discs can be excited, and the beam shape of the generated ultrasonic signal can be affected by different controls on these electrodes.

[0095] Figure 8 Another embodiment of the electroacoustic element 7 according to the invention is shown, which is constructed as a piezoelectric element. The electroacoustic element 7 also has two electroacoustic discs 10 arranged in the form of piezoelectric discs stacked one on top of the other, wherein at least one electrode 9 is arranged on the end face 7 of each electroacoustic disc 10.

[0096] Two electrodes 9, which can be controlled individually or in parallel, are respectively arranged on the upper end surface 8 of the lower electroacoustic disk 10 and the upper end surface 8 of the upper electroacoustic disk 10, wherein a corresponding outer ring electrode 9 surrounds an inner circular electrode 9.

[0097] During operation, voltage is applied to at least one electrode 9 disposed on the upper end face 8 and the lower end face 8 of the lower electroacoustic disk 10 to excite the lower electroacoustic disk 10. By exciting the lower electroacoustic disk 10, the upper electroacoustic disk 10 is also excited to vibrate during operation. An additional electrical load is applied (or abutted) between at least one electrode 9 disposed on the lower end face 8 and at least one electrode 9 disposed on the upper end face 8 of the upper electroacoustic disk 10, which can suppress the vibration of the upper electroacoustic disk 10 during operation, thereby resulting in overall tuning of the resonant vibration of the electroacoustic element 7. In the illustrated embodiment, the control unit 13 is configured as a multiplexer or a switchable array. As a result, with the illustrated embodiment, not only can the beamform be matched with multiple different electrodes 9, but the frequency of the generated ultrasonic signal can also be influenced by special control of these electroacoustic disks 10.

[0098] Furthermore, the electroacoustic disc shown can operate differently in transmit mode and receive mode during operation.

[0099] In this regard, the illustrated embodiment is particularly flexible in adjusting the characteristics of the generated ultrasonic signal.

[0100] Figures 9a to 9c Embodiments of the electroacoustic element 7 are shown in top views of the upper end face 8 of the electroacoustic disk, wherein the electrodes 9 have different shapes. In detail, Figure 9a A honeycomb structure consisting of seven electrodes is shown, wherein each individual, individually controllable electrode 9 is hexagonally constructed. Figure 9b A combination consisting of nine individually controllable electrodes is shown, wherein each individual electrode 9 is constructed rectangularly, and in particular squarely. Both embodiments have the advantage that different combinations of electrodes 9 can be controlled in parallel. This allows for the adjustment (or generation, tuning, i.e., einstellen) of a particularly large number of beamforms during operation, especially asymmetrical beamforms. Figure 9c An embodiment is shown in which electrode 9 has an elliptical shape. According to the illustrated embodiment, an annular elliptical electrode 9 surrounds an inner elliptical electrode 9.

[0101] Figure 10A first embodiment of the ultrasonic flow meter 3 according to the invention is shown, which has two ultrasonic transducers 1 according to the invention. These two ultrasonic transducers 1 are configured not only as ultrasonic transmitters but also as ultrasonic receivers. These ultrasonic transducers 1 are arranged offset at the measuring tube 12 such that ultrasonic signals are emitted into the medium, respectively, along and against the flow direction. Due to the design of the ultrasonic transducers according to the invention, each ultrasonic transducer can be controlled differently according to the measurement conditions and the characteristics of the measured medium. As a result, the ultrasonic transducers 1 can emit signals with two different beamwidths ΔΘ1 and ΔΘ2 and two different frequencies f1 and f2.

[0102] In this regard, the operation of the ultrasonic flow meter 3 can be particularly flexibly matched to the medium and the current measurement conditions.

[0103] Figure 11 A first embodiment of a method 2 for operating an ultrasonic transducer 1 according to the present invention is shown.

[0104] In the first step, the viscosity of the medium to be tested (14) is determined. Based on the viscosity, a voltage is applied to the electroacoustic disk (10). The frequency of the generated ultrasonic signal is adjusted by the determined voltage to be 1 MHz or 2 MHz.

[0105] Instead of determining the viscosity of the medium, the transmission intensity of the ultrasonic signal can also be determined, and / or the spectrum of the transmitted signal can be determined. In this regard, the frequency of the ultrasonic signal can also be adjusted such that transmission through (or through, i.e., durch) the medium is maximized.

[0106] Figure 12 An embodiment of a method 4 for operating an ultrasonic flow meter 3 is shown, wherein the ultrasonic flow meter 3, as... Figure 10 The structure is as shown. In the first step 14, the viscosity of the medium is determined. Based on the measured viscosity value, a voltage 15 is applied to the electroacoustic disk 10 for each ultrasonic transducer 1, thereby adjusting the frequency of the ultrasonic signal. The flow velocity of the medium 16 is determined by the measured ultrasonic signal propagation time.

[0107] The control of electrode 9 is switched based on the measured flow velocity, thereby increasing or decreasing the beamwidth. Specifically, the control is switched if the flow velocity exceeds or falls below a limit value; alternatively or supplementarily, the control is switched if the transmission intensity exceeds or falls below a threshold value.

[0108] Then, before issuing a second ultrasonic signal to determine the flow rate, the viscosity of 14 is re-determined.

[0109] The viscosity of the medium under test can be determined before each measurement, and in alternative embodiments, measurements are performed at regular or irregular intervals. Furthermore, the ultrasonic transducers can operate at the same frequency; alternatively, the ultrasonic signals can operate at different frequencies. In this case, each ultrasonic transducer operates at a different frequency during transmission operation than during reception operation.

[0110] As a result, the method shown has the advantage that the operation of the ultrasonic transducer 1 and, in this regard, the operation of the ultrasonic flow meter 3 can be matched to the medium and / or the current measurement conditions, thereby improving the measurement process as a whole.

[0111] List of reference numerals

[0112] 1. Ultrasonic transducer

[0113] 2. Methods for operating ultrasonic transducers

[0114] 3. Ultrasonic flow meter

[0115] 4. Methods for operating ultrasonic flow meters

[0116] 5. Housing

[0117] 6 sound windows

[0118] 7 Electroacoustic components

[0119] 8 end face

[0120] 9 electrodes

[0121] 10 Electroacoustic discs

[0122] 11 Electrical load

[0123] 12 Measuring tubes

[0124] 13 Control Unit

[0125] 14. Determine the viscosity

[0126] 15. Apply voltage to the electroacoustic disc.

[0127] 16. Determine the flow velocity

[0128] 17. Electrode switching control.

Claims

1. A method (2) for operating an ultrasonic transducer (1) in a measurement environment, Its features are, The ultrasonic transducer (1) has at least one electroacoustic element (7), at least one housing (5), at least one acoustic window (6), and at least one control unit (13). The electroacoustic element (7) is arranged inside the housing (5) on the acoustic window (6) such that the ultrasonic signal generated by the electroacoustic element (7) during operation exits the housing (5) through the acoustic window (6). The electroacoustic element (7) has at least two electroacoustic disks (10), wherein the at least two electroacoustic disks (10) are arranged stacked vertically, and wherein at least one electroacoustic disk (10) can be excited individually, at least temporarily, by the control unit (13). The ultrasonic transducer (1) transmits ultrasonic signals into the medium, and, The electroacoustic element (7) is controlled based on the viscosity of the medium and / or the absorption of the generated ultrasonic signal by the medium. Wherein, when the viscosity of the medium is below a limit value, the electroacoustic disk is controlled in such a way that the ultrasonic signal has a first frequency; and where, when the viscosity is above a limit value, the electroacoustic disk is controlled in such a way that the ultrasonic signal has a second frequency; and / or, The ultrasonic signal is determined at at least two frequencies to be achieved through transmission through a medium, wherein the electroacoustic element is controlled such that the ultrasonic signal is emitted at a frequency at which absorption is minimized.

2. An ultrasonic transducer (1) for an ultrasonic flow meter (3), wherein, The ultrasonic transducer (1) has at least one electroacoustic element (7), at least one housing (5), at least one acoustic window (6), and at least one control unit (13). The electroacoustic element (7) is arranged inside the housing (5) on the acoustic window (6) such that the ultrasonic signal generated by the electroacoustic element (7) during operation exits the housing (5) through the acoustic window (6). Its features are, The electroacoustic element (7) has at least two electroacoustic discs (10), wherein the at least two electroacoustic discs (10) are arranged stacked one on top of the other, and wherein at least one electroacoustic disc (10) can be excited individually, at least temporarily, by the control unit (13), and the ultrasonic transducer is capable of operating according to the method according to claim 1.

3. The ultrasonic transducer (1) according to claim 2, wherein the electroacoustic element (7) is a piezoelectric element and / or a micromechanical element of a capacitive micromechanical ultrasonic transducer, and / or at least one electroacoustic disk (10) is a piezoelectric disk and / or a micromechanical disk of a capacitive micromechanical ultrasonic transducer.

4. The ultrasonic transducer (1) according to claim 3, characterized in that, Each of the at least two electroacoustic discs (10) has a first and a second end face (8), and at least three electrodes (9) are connected to the electroacoustic element (7), wherein at least one electrode (9) is arranged on the end face (8) of the first electroacoustic disc (10) facing the acoustic window (6), wherein at least one electrode (9) is arranged between the first and second electroacoustic discs (10), and wherein at least one electrode (9) is arranged on the end face (8) of the second electroacoustic disc (10) facing away from the acoustic window (6).

5. The ultrasonic transducer according to any one of claims 2 to 4, characterized in that, At least two electrodes differ in their shape and / or their size.

6. The ultrasonic transducer according to claim 4, characterized in that, The control unit is constructed and connected to the electrodes such that at least two electrodes can be controlled, at least temporarily, with different phases and / or different amplitudes.

7. The ultrasonic transducer according to any one of claims 2 to 4, characterized in that, There are multiple individually controllable electrodes, wherein the multiple electrodes are arranged on the same end face of at least one electroacoustic disk, and wherein the individual electrodes for adjusting the beam shape of the generated ultrasonic signal can be controlled in different combinations during operation.

8. The ultrasonic transducer (1) according to any one of claims 2 to 4, characterized in that, At least two electroacoustic discs (10) have the same or different thicknesses.

9. The ultrasonic transducer (1) according to any one of claims 2 to 4, characterized in that, At least two electroacoustic discs (10) are made of the same material or different materials.

10. The ultrasonic transducer (1) according to any one of claims 2 to 4, characterized in that, At least one electroacoustic disc (10) is connected to an adjustable load.

11. The ultrasonic transducer according to any one of claims 2 to 4, characterized in that, There are multiple individually controllable electrodes, wherein the multiple electrodes are arranged on the same end face of at least one electroacoustic disk, and wherein each electrode for adjusting the beamwidth of the generated ultrasonic signal can be controlled in different combinations during operation.

12. The ultrasonic transducer (1) according to any one of claims 2 to 4, characterized in that, At least one electroacoustic disc (10) is connected to an inductive and / or capacitive load.

13. The ultrasonic transducer according to any one of claims 2 to 4, characterized in that, Two electrodes arranged on the same end face are different in their shape and / or their size.

14. An ultrasonic flow meter (3) having at least one measuring tube (12), at least one ultrasonic transducer (1), and at least one control and evaluation unit, wherein, The at least one ultrasonic transducer (1) is configured as at least an ultrasonic transmitter, and wherein the ultrasonic transducer (1) is arranged at the measuring tube (12) such that the ultrasonic transducer transmits ultrasonic signals into the measuring tube (12) in operation, either along or against the flow direction of the flowing medium. Its features are, The at least one ultrasonic transducer (1) is constructed according to any one of claims 2 to 13.

15. An ultrasonic flow meter (3) having at least one measuring tube (12), at least one ultrasonic transducer (1), and at least one control and evaluation unit, wherein, The at least one ultrasonic transducer (1) is configured as an ultrasonic transmitter and receiver, and wherein the ultrasonic transducer (1) is arranged at the measuring tube (12) such that the ultrasonic transducer transmits ultrasonic signals into the measuring tube (12) in operation along or against the flow direction of the flowing medium. Its features are, The at least one ultrasonic transducer (1) is constructed according to any one of claims 2 to 13.

16. The ultrasonic flow meter (3) according to claim 14 or 15, characterized in that, The control and evaluation unit stores the relationship between the viscosity of the medium under test and / or the absorption of ultrasonic signals by the medium and the control of the electroacoustic element (7).

17. The ultrasonic flow meter (3) according to claim 14 or 15, characterized in that, The control and evaluation unit stores the relationship between the value of at least one state variable of the ultrasonic flow meter and the control of the electrode (9).

18. The ultrasonic flow meter (3) according to claim 14 or 15, characterized in that, The control and evaluation unit stores the relationship between the flow rate and / or viscosity of the medium under test and the control of the electrode (9).

19. A method (4) for operating an ultrasonic flow meter (3), Its features are, The ultrasonic flow meter (3) is constructed according to any one of claims 14 to 18, and at least one ultrasonic transducer (1) operates according to the method (2) of claim 1.

20. The method (4) according to claim 19, characterized in that, The ultrasonic flow meter (3) has at least two ultrasonic transducers (1), wherein the at least two ultrasonic transducers (1) are configured as ultrasonic transmitters and as ultrasonic receivers, and wherein the two ultrasonic transducers (1) are configured according to any one of claims 2 to 13, wherein the two ultrasonic transducers (1) are configured identically in relation to the design of the electroacoustic element (7), and wherein the two ultrasonic transducers (1) are identically controlled during operation.

21. The method (4) according to claim 19 or 20, characterized in that, The control and evaluation unit controls at least two electrodes (9) based on at least one state variable, and wherein, during operation, the control of the at least two electrodes is changed based on at least one state variable.

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