Classifications

• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
  • G01F1/00—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow
  • G01F1/66—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow by measuring frequency, phase shift or propagation time of electromagnetic or other waves, e.g. using ultrasonic flowmeters
  • G01F1/662—Constructional details
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
  • G01F1/00—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow
  • G01F1/66—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow by measuring frequency, phase shift or propagation time of electromagnetic or other waves, e.g. using ultrasonic flowmeters
  • G01F1/663—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow by measuring frequency, phase shift or propagation time of electromagnetic or other waves, e.g. using ultrasonic flowmeters by measuring Doppler frequency shift

Definitions

• Measuring system for determining and / or monitoring the flow of a
• the present invention relates to a measuring system for determining and / or monitoring the flow of a measuring medium through a measuring tube with at least one UStraschaSlwandler and at least one control / evaluation, which are derived from the measurement signals or based on measurement data, which are derived from the measurement signals Determined volume and / or the mass flow of the flowing in the measuring tube measuring medium, wherein the ultrasonic transducer has at least one eiektromechanisches transducer element which transmits and / or receives ultrasonic signals, and with at least one Koppei harsh in the region between the electromechanical transducer element and the measuring medium, which coupling layer conducts the ultrasonic signals ,
• Uitraschall flowmeters are widely used in process and automation technology. They allow in a simple way to determine the volume flow and / or mass flow in a pipeline.
• the known ultrasonic flowmeters often work after the Doppler or after the transit time difference principle.
• ultrasonic pulses are sent at a certain angle to the pipe axis both with and against the flow.
• the runtime difference can be used to determine the flow velocity and, with a known diameter of the pipe section, the volume flow rate.
• ultrasonic waves with a specific frequency are coupled into the liquid and the reflected waves reflected by the liquid are evaluated. From the frequency shift between the coupled and reflected waves can also determine the flow velocity of the liquid.
• ultrasonic transducers are firmly attached to the pipe wall of the relevant pipe section. More recently, clamp-on
• Ultrasonic flow measuring systems available. In these systems, the ultrasonic transducers are pressed against the pipe wall only with a clamping lock. Such systems are for. Example, from EP 686 255 B1, US-A 44 84 478 or US-A 45 98 593 known.
• a big advantage of clamp-on ultrasonic flowmeters is that they do not touch the medium being measured and are mounted on an existing pipeline.
• the disadvantage is a high effort in the assembly of the clamp-on systems to align the individual Ultraschallaliwandler each other, which depends on many parameters, such as pipe wall thickness, pipe diameter, speed of sound in the measured medium.
• Both ultrasound transducers of medium-contacting InNne systems and ultrasound transducers of clamp-on systems conventionally require a relatively large amount of space outside of the measuring tube. They are exposed to mechanical influences.
• the ultrasonic signals between the ultrasonic transducers usually propagate on a signal path.
• the ultrasound transducers normally consist of a piezoelectric element, also called piezo for short, and a coupling layer, also Koppeikei! or less commonly called Vorlauf stresses.
• the coupling layer is usually made of plastic
• the piezoelectric element is in industrial process measurement usually a piezoceramic.
• the ultrasonic waves are generated and passed over the coupling layer to the pipe wall and passed from there into the liquid. Since the speeds of sound in liquids and plastics are different, the ultrasonic waves are refracted during the transition from one medium to another. The refraction angle! determined in first approximation after the
• the adaptation layer assumes the function of the transmission of the ultrasonic signal and at the same time the reduction of a reflection caused by different acoustic impedances at boundary layers between two materials.
• a sensor device for flow measurement which is fixedly mounted on a measuring tube.
• This sensor device is a piezoelectric sensor which detects vibration and / or oscillation variables of the measuring tube or the wall of the measuring tube on which the piezoelectric sensor is mounted, and these vibration and / or oscillation variables of the measuring tube, which due to interactions of a flowing medium in the Measuring tube with the wall of the measuring tube are generated, converted into voltage signals. By means of these voltage signals, the flow of the measuring medium through the measuring tube is then determined.
• the piezosensor foil is attached to the outside of the wall of the measuring tube, whereby a measuring medium flows past on the inside of the wall.
• a shield may be attached to protect the piezo sensor film.
• the piezo sensor film preferably consists of polyvinylidene fluoride (PVDF). From the Piezose ⁇ sorfolie no vibration or vibration signal is emitted. The piezo sensor film only receives vibrations or vibrations caused by the flow that is located in the interior of the measuring tube.
• the measuring accuracy of the sensor device is very limited.
• US Pat. No. 3,906,791 shows an ultrasonic flowmeter with a measuring tube of rectangular or square cross-section.
• ultrasonic transducers are mounted on the flat outside of the measuring tube wall. They emit an ultrasonic signal substantially perpendicular to the main flow direction of the measuring medium in the measuring tube. The ultrasonic signal is deflected in the direction of the flow of the measuring medium or its opposite by triangular in cross-section recesses on the inside of the measuring tube wall.
• the object of the invention is to provide a flow measuring system whose sensors can be attached to a pipeline and require no complicated mutual alignment.
• a measuring system for determining and / or monitoring the flow of a measuring medium through a measuring tube with at least one ultrasonic transducer and with at least one control / evaluation unit, which are based on the measurement signals or on the basis of measurement data derived from the measurement signals determines the volume and / or the mass flow of the measuring medium flowing in the measuring tube, wherein the ultrasonic transducer has at least one electromechanical transducer element which transmits and / or receives ultrasonic signals, and with at least one Coupling layer in the region between the electromechanical transducer element and measuring medium, soft coupling layer fuses the UltraschallaSIsignale, the ultrasonic transducer with the measuring tube acoustically coupled and that the ultrasonic transducer is configured such that the ultrasonic transducer to the respective shape of the inner and / or outer wall of the measuring tube at least partially adaptable is.
• another advantage is a very flat design of the ultrasonic
• the electromechanical transducer element converts the ultrasonic signals according to the principle of electrostriction or magnetostriction.
• Magnetostriction is the change in length of a ferromagnetic material due to an applied magnetic field.
• the electrostriction describes the deformation of a dielectric as a result of an applied electric field. The deformation is generally not dependent on the direction of the field. The piezoelectric effect is thus in the special part of electrostriction.
• magnetostriction is the change in length of a ferromagnetic material due to an applied magnetic field.
• the electrostriction describes the deformation of a dielectric as a result of an applied electric field. The deformation is generally not dependent on the direction of the field.
• the piezoelectric effect is thus in the special part of electrostriction.
• the electromechanical transducer element is a piezoelectric element.
• the electromechanical transducer generates ultrasound signals and / or converts received ultrasound signals into electrical signals.
• the coupling layer conducts the ultrasonic signals.
• the coupling layer is preferably made of a material which has certain acoustic properties, e.g. a predeterminable acoustic impedance and / or a predeterminable sound velocity.
• the tube itself serves as a coupler layer. If e.g. a steel tube used as a measuring tube and the electromechanical Wandierelement is a piezoelectric element, so a coupling layer as an adaptation layer between the transducer element and the measuring tube is providable.
• the electromechanical transducer element can be attached directly to the measuring tube.
• the measuring tube takes over the task of the coupling layer, the acoustic coupling between the transducer element and the measuring medium.
• Ultrasonic transducers generate ultrasonic signals in the form of ultrasonic waves.
• ultrasonic waves propagate only as longitudinal waves.
• the excited particles vibrate in the propagation direction by the amount of the amplitude.
• An ultrasound signal thus consists of at least one ultrasound wave with a wavefront.
• the Welienfront stands perpendicular to the propagation direction of the ultrasonic waves.
• An ultrasonic signal is limited in its width. That the wavefront has a finite extent.
• the essential element for limiting the width of an ultrasonic signal is the surface of the ultrasonic transducer from which the ultrasound wire is emitted. For the sake of simplicity, it is believed that a limited width ultrasonic signal propagates on a sharp sound or signal path. The width of the signal path is to be regarded as punctiform. An ultrasonic signal therefore propagates on a straight signal path in a model. The propagation direction of the ultrasonic waves thus corresponds to the direction of the ultrasound signal on the signal path.
• an ultrasonic transducer comprises at least one electromechanical wall element, e.g. a piezoelectric element, which emits and / or receives ultrasound signals on at least one first signal path, and a coupling layer in the region between the electromechanical transducer element and the measurement medium conducts the ultrasound signals on the first signal path.
• electromechanical element e.g. a piezoelectric element, which emits and / or receives ultrasound signals on at least one first signal path, and a coupling layer in the region between the electromechanical transducer element and the measurement medium conducts the ultrasound signals on the first signal path.
• electromechanical element several elements can be used. These are e.g. to arrange next to each other and / or one above the other in so-called stacks. For the stacks, the individual elements are contacted and connected in series (series) or in sandwich construction.
• the electromechanical transducer element is flexible.
• the electromechanical Wandlausement has at least during the assembly of Uftraschallwandlers on a certain flexibility. For example, by curing an adhesive or by cooling the flexible at an assembly temperature electromechanical transducer element, a flexibility in the use of Ultraschallaliwandiers is not mandatory.
• the electromechanical transducer element is a foil.
• a film is a thin sheet, which can be produced in Endfosbahnen and can be rolled up. The thickness of a film thus depends on different material parameters.
• PVDF films are usually less than 1 mm thick.
• the electromechanical transducer element takes the form of a single or double-curved shell. Ultrasonic signals can be emitted and / or received over approximately the entire surface of the electromechanical transducer element. Two shells are parallel if their tails and their mantle lines are parallel to each other.
• the eiektromechanische transducer element can be applied to a first surface of the coupling layer and the ultrasonic signal occurs substantially perpendicular to the first surface of the coupling layer in the first surface of the coupling layer and / or from the first surface of the Coupling layer exits and the coupling layer, the ultrasonic signal deflected at least partially so that a first direction component of the ultrasonic signal in or against the flow direction of the measuring medium in the measuring tube shows and / or that a second direction component of the ultrasonic signal is perpendicular to the flow direction of the measuring medium in the measuring tube.
• the propagation direction of the ultrasound signal on the first signal path is substantially perpendicular to the first surface of the first coupling layer upon signal entry and / or signal exit from the first surface of the first coupling layer.
• the ultrasonic signal is refracted. If the ultrasonic signal is refracted or deflected perpendicularly to the flow direction of the measuring medium in the measuring tube, ie provided with a directional component in the radial direction, a flow measurement with the transit time difference method, eg with prior flow conditioning, is possible.
• parameters of the measuring medium such as e.g. the speed of sound in the medium to be determined.
• the ultrasonic signal thus runs on a straight path perpendicular to the electromechanical transducer through the measuring tube.
• the e vomromechanische transducer element can be applied to a first surface of the coupling layer and the ultrasonic signal occurs substantially perpendicular to the first surface of the Koppei Mrs in the first surface of the coupling layer and / or emerges from the first surface of the coupling layer and the coupling layer deflects the ultrasonic signal onto two signal paths in such a way that a first directional component of the ultrasound signal on a first signal path and a third directional component of the ultrasound signal on a second
• the coupling layer has at least one recess, which recess has an approximately trapezoidal cross-section.
• the recess forms a groove.
• the groove with the approximately trapezoidal cross section has an extent perpendicular to the approximately trapezoidal cross section.
• the cross section is continued in the longitudinal direction.
• the RiNe runs at an angle of 0 ° to 90 ° to the tube axis, ie the longitudinal direction of the groove extends at an angle of 0 ° to 90 ° to the tube axis.
• the groove assumes a circular or oval longitudinal section. The angle refers to the tangent to the ultrasound transducer.
• the recesses are arranged approximately uniformly over the surface of the coupling layer.
• the distance of the recesses from each other is substantially constant.
• the recesses have approximately the same cross sections.
• the recesses are introduced on two opposite sides of the coupling layer.
• a supplementary development of the device according to the invention is that the recesses are an integral part of the measuring tube.
• the measuring tube has a thread in its inner wall and / or outer wall.
• the recesses are triangular, wherein one side of the triangular recess is substantially parallel to at least one propagation direction of the ultrasound signal. In one embodiment, one side of the triangular-shaped recess is substantially perpendicular to at least one propagation direction of the ultrasound signal.
• the ultrasound signal is modeled along an approximately sharp signal path.
• the measuring system determines and / or monitors the flow of the measuring medium through the measuring tube with the transit time difference method or the Doppler method.
• the measuring system has at least two Uitraschallwandler, which are arranged on the measuring tube, that the ultrasonic signal on the first signal path between the two ultrasonic transducers.
• Fig. 1 shows in longitudinal section a measuring tube with trapezoidal according to the invention
• FIG. 2 shows a longitudinal section of a measuring tube with trapezoidal recesses according to the invention on the outside
• Fig. 3 shows a longitudinal section of a Ultraschallwandier invention with two
• Fig. 4 shows a longitudinal section of a Ultraschallwandier invention with two
• FIG. 5 shows a longitudinal section of a Ultraschallwandier invention with two
• FIG. 6 shows in cross section an ultrasonic transducer according to the invention with two
• FIG. 7 shows in perspective a coupling layer according to the invention of an ultrasonic transducer
• Fig. 8 shows in perspective a coupling layer according to the invention a
• Fig. 9 shows in longitudinal and cross section an inventive measuring system with a Ultraschallwandier
• Fig. 10 shows in longitudinal and cross section an inventive measuring system with an ultrasonic transducer
• Fig. 11 shows a longitudinal section of an inventive measuring system with two
• Fig. 13 shows in cross-section an inventive measuring system with two or three
• Fig. 14 shows in cross section the structure of an inventive
• Ultrasonic transducer 15 shows an ultrasonic transducer array on a coupling element according to the invention of two coupling layers
• Fig. 1 shows an inventive measuring system in longitudinal section.
• the measuring tube 3 has essentially triangular recesses 21 in the measuring tube inner wall 23, which recesses 21 form a groove in the measuring tube inner wall 23.
• the triangular shape of the cross sections of the recesses 21 is an extreme expression of a trapezoid.
• a trapezoid is determined by four sides, which include four angles. We one of these hints! Zero and thus a side length zero, creates a triangle. Other extreme forms are e.g. a rectangle or a stretch.
• medium parameters such as e.g. Due to the tube curvature, the trapezoid may have slightly curved sides, but the cross section of the recesses 21 is approximately recognizable as a trapezoid.
• the recesses 21 may be filled with a material or, as here, filled by the measuring medium 4.
• the electromechanical transducer preferably a piezoelectric film 5, not shown here for the sake of simplicity, is mounted on the part of the measuring tube outer wall 22 opposite the recesses 21, ie the region of the measuring tube 3 which has the recesses 21 also has the piezoelectric FoNe 5 on, just on the other side of the measuring tube wall.
• Ultrasonic signals which are irradiated by the piezoelectric film 5 approximately perpendicular to the outer wall 22 of the measuring tube 3, ie perpendicular to an imaginary tangential plane, strike the recesses 21 and are corresponding to the angle at which they interfere with the interface between measuring tube 3 and measuring medium.
• the measuring tube 3 takes over here the same function as a first and in this case
• the measuring tube outer wall forms the first surface 10 of the first Koppet Anlagen 7 and the interface between the measuring tube 3 and measuring medium 4 is the second surface 11 of the first coupling layer. 7
• the inscribed Uitraschallsignaipfad 6 represents the ultrasonic signal waveform. It is perpendicular to the wavefront of an ultrasonic signal.
• an ultrasonic signal in both directions, when the refractions at the entry point of the signal opposite side of the rotating Uitraschallwandiers 4 have the same angle. This is e.g. achieved in that the circumferential recesses 21 approximately constant shape and
• the first Rambatungskomponente 25 of the ultrasonic signal on the first signal path 6 points in the main flow direction of the measuring medium 4 in the measuring tube 3.
• a second directional component 26 of the ultrasonic signal on the first signal path 6 transversely to the main flow direction of the measuring medium 4 in the measuring tube 3 would point into the plane of the plane or out of the plane of the drawing.
• the measuring tube 3 acts as a second coupling layer 8.
• the measuring tube 3 has trapezoidal recesses 21 in its outer wall 22, which are filled, for example, with a plastic compound.
• the filled recesses 21 form the first Koppei Mrs 7.
• the piezoelectric film 5 is applied, which again is not shown here.
• At the interface between first coupling layer 7 and second coupling layer 8 Thus, at the interface between the second surface 11 of the first coupling layer 7 and the first surface 12 of the second coupling layer 8, an ultrasound signal is deflected or refracted according to the known circumstances.
• a second refraction takes place on the second surface 13 of the second coupling layer 8, the tube inner wall 23.
• the ultrasonic signals from the piezoelectric element that is to say the ultrasonic signals irradiated into the first coupling layer 7, are also shown in the following FIGS. 3 to 6.
• the ultrasonic signals can either be totally reflected approximately at the inner wall 23 of the measuring tube 3, to which the ultrasonic signal impinges, and be directed back to the ultrasonic transducer 2, or they are, as indicated in FIG. 2, broken analogously to the signal entry, if an ultrasonic transducer 2 is mounted on the opposite side of the Einstrahl scanning the measuring tube 3.
• angles of inclination of the surfaces of the coupling layers to the incident ultrasonic signal are not necessarily equal to the refraction angle of the ultrasonic signal. This depends on the speed of sound, u.a. of the medium to be measured. This is a great advantage of the invention: conventional clamp-on systems must be aligned with each other, e.g. with a change of the measuring medium. This system does not have to be realigned.
• FIG. 3 shows a measuring tube 3 with an ultrasound transducer 2 mounted on its outside 22.
• the ultrasonic transducer 2 consists of a piezoelectric film 5 and two coupling layers 7, 8, wherein the piezoelectric film 5 is mounted on the first coupling layer 7 and the second coupling layer 8 is mounted on the measuring tube 3.
• the piezoelectric film 5 is not shown for the sake of simplicity.
• the ultrasonic signals enter into the first coupling layer 7 substantially perpendicular to the first surface 10 of the first coupling layer 7 and out of the first coupling layer 7. Here again, only the entrance is so
• the refraction at the boundary layer between the first coupling sheath 7 and the second coupling layer 8 is influenced by the fact that the speed of sound in the first coupling layer 7 is higher than in the second coupling layer 8.
• the second surface 11 of the first coupling layer 7 assumes substantially the shape of a bellows. Since the second surface 11 of the first coupling layer 7 has trapezoidal recesses 21, the first surface 12 of the second coupling layer 8 has a congruent increase. Alone considered, however, the first surface 12 of the second coupling layer 8 is also provided with trapezoidal recesses 21.
• the two surfaces 10, 11 are to be regarded as positive and negative to each other.
• the recesses 21 in the first coupling layer 7 are completely filled by the second coupling layer 8.
• the advantage of the embodiment of the trapezoidal recesses 21 in sawtooth form is that the ultrasonic signals radiated by the piezoelectric film 5, which run parallel to each other and in a common imaginary axial plane 19, are deflected differently at the interfaces of the coupling layers 7 and 8, since the ultrasonic signals hit the shorter and longer interfaces at different angles.
• a part of the ultrasound signal can be radiated into the measuring mandrel 4 at a certain angle in one direction, wherein another, in particular a very small, part of the ultrasound signal is deflected at an interface, here at the shorter, such that the signal is passed out of the ultrasonic transducer 2, without it passes through the measuring medium 4.
• part of the signal energy is lost.
• the materials of the coupling layers 7 and 8 are according to their acoustic properties, such as. e.g. their acoustic impedance or their speed of sound.
• the ultrasonic transducer 2 is mounted on the outer wall 22 of the measuring tube 3. He takes approximately the shape of the measuring tube 3 and the shape of the outer wall 22 at least partially, here the Uitraschalfwandler 2 takes the form of a simply curved shell.
• Fig. 6 discloses the Teüquerroughsansicht an ultrasonic transducer according to the invention 2.
• the ultrasonic transducer 2 consists of a piezoelectric film 5, not shown, and a coupling element between the measuring tube 3 and piezo 5 of two coupling layers.
• the trapezoidal recesses 21 extend substantially parallel to the tube axis 16 in the side of the first coupling layer 7 facing the measuring medium 4.
• the second coupling layer 8 is located between measuring tube 3 and first coupling layer 7 and completely fills the recesses 21 in the first coupling layer 7.
• the ultrasonic signals entering substantially perpendicularly to the first surface 10 of the first coupling layer 7 and extending essentially in an imaginary radial plane are deflected at an angle to an imaginary axial plane, ie perpendicular to the main flow direction of the measuring medium 4 in the measuring tube 3, in accordance with the known circumstances.
• the ultrasonic transducer 2 is mounted around the entire measuring tube circumference. Refractions of the ultrasonic signal are in turn possible on the inner wall 23 of the measuring tube 3 or on the surfaces of the recesses 21 of the Uitraschallwandlers 2.
• a coupling layer 7 is shown in perspective on both sides of the Koppei Mrs, ie both on its first surface 10, as well as on its second surface 11, triangular recesses 21 are attached.
• the recesses 21 form grooves.
• the grooves on the first side are perpendicular to the grooves of the second side.
• FIG. 8 shows a coupling layer 7 with recesses 21 introduced only into a surface 10. If this coupling layer 7 is placed around a measuring tube 3, not shown, the grooves formed by the recesses 21 have an angle to the tube axis 16 or to the main flow direction of the measuring medium 4 in the measuring tube 3 an angle of about 45 °. To realize such grooves by simply tapping, for example in the inner wall 23 of the measuring tube. 3
• FIGS. 9 and 10 show longitudinal and cross sections of measuring systems according to the invention. In each case the full cross-section of the measuring tube 3 is penetrated by ultrasonic signals. In FIG. 10, the ultrasonic transducer covers only half the outer wall 24 of the measuring tube 3, wherein in FIG. 9 the full measuring tube circumference is covered.
• FIG. 10 shows the cross sections of the longitudinal sections drawn in FIGS. 9a and 10a. The degree of coverage of the tubes 3 by the ultrasonic transducers 2 can be seen.
• FIG. 10a shows the signal course upon reflection at the measuring tube outer wall.
• FIGS. 11 and 12 likewise show longitudinal sections of a measuring system 1.
• two ultrasonic transducers 2 are mounted on a measuring tube 3. Both transducers 2 send ultrasonic signals in the direction of the other converter. So one sends upstream, the other downstream. Received is the signal of the other ultrasonic transducer 2.
• For an asymmetric profile of the recesses 21 is advantageous.
• Fig. 12 shows three Uitraschailwandler 2 in a row.
• the middle ultrasonic transducer 2 serves as a transmitter, the other two are used only as a receiver.
• the transmitter transmits both in a! S and counter to the main flow direction of the measuring medium 4 in the measuring tube 3.
• the cross section illustrated in FIG. 13 can originate both from a measuring system with an ultrasonic transducer 2, as well as with a plurality of ultrasonic transducers 2 in series.
• the region of the measuring medium 4 in the measuring tube 3, which is penetrated by ultrasonic signals is shown hatched.
• the measuring system is, as can be seen here, very flat in contrast to the prior art. It is thus comparatively less frequently and exposed to much lower mechanical loads.
• FIG. 14 shows an ultrasound converter 2 according to the invention.
• the electromechanical Wandlereiement 5 is applied to a first coupling layer 7.
• a second coupling layer 8 is in contact with the first coupling layer 7 and the outer wall 22 of the measuring tube 3.
• a Meßmedäum 4 are located in the interior of the measuring tube 3.
• On the detailed drawing of a triangular recess 21 are individual signal paths to see 6, on which propagate ultrasound signals modeühaft , The signal paths 6 are substantially parallel to one another and approximately parallel to a surface or to a side of the triangular-shaped recess 21 in cross-section. This ensures that a loss of signal energy due to refraction is very small. Over the entire surface 13, the ultrasonic signals are emitted from the coupling element 8. If the signal paths are not parallel to a side surface of the triangular-shaped recess 21, there is a signal gap and thus a loss of signal energy.
• Fig. 15 shows an ultrasonic transducer array of two interdigitated ultrasonic wall elements 5, 5 '.
• the ultrasound transducer elements 5, 5 ' can also consist of a single foil with electrodes applied at specific intervals to one another, for example sputtered on.
• they are arranged over a triangular-shaped recess 21 and they each cover a deflecting side of the triangle.

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• Physics & Mathematics (AREA)
• Electromagnetism (AREA)
• Fluid Mechanics (AREA)
• General Physics & Mathematics (AREA)
• Measuring Volume Flow (AREA)

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• 2008
  • 2008-06-03 DE DE102008002166A patent/DE102008002166A1/de not_active Withdrawn
• 2009
  • 2009-06-02 EP EP09757509A patent/EP2283326A1/de not_active Withdrawn
  • 2009-06-02 WO PCT/EP2009/056726 patent/WO2009147128A1/de active Application Filing
  • 2009-06-02 US US12/996,065 patent/US8468897B2/en not_active Expired - Fee Related
  • 2009-06-02 RU RU2010154163/28A patent/RU2466359C2/ru not_active IP Right Cessation

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