DE202021003603U1 - Device for measuring a flow rate of a fluid - Google Patents

Abstract

Device (10) for determining a flow rate of a fluid, in particular a liquid, through a volume (12), comprising:the volume (12), the volume (12) having a fluid inlet (14) and a fluid outlet (16),a Measuring device (24) for measuring the flow rate of the fluid through one or more ultrasonic measuring sections arranged in the volume (12), having at least one ultrasonic measuring section (20-1, 20-2, 20-3) for measuring the flow rate, wherein the at least one ultrasonic measuring section (20-1, 20-2, 20-3) is arranged in the volume (12) and has an ultrasonic sensor assigned to it in order to measure the flow rate of the fluid and to output at least one flow rate measured value, a flow rate determination device (26) for determining the flow rate through the volume (12) based on the at least one flow rate meter t; a first pressure sensor (28) for measuring a first pressure and a second pressure sensor (30) for measuring a second pressure, the first pressure sensor (28) and the second pressure sensor (30) being arranged in the volume (12), the first pressure sensor (28) and the second pressure sensor (30) delimit a differential pressure determination section (32) for determining a differential pressure over the differential pressure determination section (32), a differential pressure determination device (34) for determining the differential pressure over the differential pressure determination section ( 32) using the first pressure and the second pressure, a flow rate change determiner (36) for determining a change between a value of the flow rate determined by the flow rate determiner (26) and a value previously determined by the flow rate determiner (26). the flow rate and a difference na pressure change determining means (38) for determining a change between a value of the differential pressure determined by the differential pressure determining means (34) and a value of the differential pressure previously determined by the differential pressure determining means (34), and a flow rate evaluating device (40) for evaluating values for the flow rate determined by the flow rate determination device (26) as error-free or as faulty and for outputting values for the flow rate evaluated as error-free, the flow rate evaluation device (40) being designed to evaluate the flow rate determined by the flow rate determination device (26 ) evaluating the determined value for the flow rate as error-free, (i) if the change between the value of the flow rate determined by the flow rate determining device (26) and the preceding value before the value of the flow rate determined by the flow rate determination device (26) is greater than a first limit value for the change in flow rate and the change in the differential pressure is greater than a first limit value for the change in the differential pressure, or (ii) if the change between the value of the flow rate determined by the flow rate determination device (26) and the value of the flow rate previously determined by the flow rate determination device (26) is less than a second limit value for the change in flow rate and the change in the differential pressure is less than a second limit value for the change in differential pressure.

Description

The present invention relates to a device for determining or determining a flow rate of a fluid, in particular a liquid, through a volume, according to claim 1.

Flow rates of fluids, in particular liquids in volumes, such as pipelines or channels, can be determined using ultrasonic measurement technology. As a rule, for this purpose, ultrasonic pulses are emitted by a sensor and received by the same sensor or by a second sensor. The flow speed can be determined from typical variables, for example the transit time of the ultrasound on the measurement path with the flow and against the flow.

However, such a device has a limited measuring accuracy, for example caused by air or foreign gas bubbles in the fluid system or by other foreign media that have a different propagation speed of the ultrasonic signal used in the fluid in the system.

Proceeding from this, the present invention is based on the object of specifying a device with improved measurement accuracy or increased error tolerance compared to the prior art.

According to the invention, this object is achieved by a device having the features of claim 1 . Advantageous configurations and developments of the invention are specified in the further claims.

• - das Volumen, wobei das Volumen einen Fluideintritt und einen Fluidaustritt aufweist,
• - eine Messvorrichtung zur Messung der Durchflussgeschwindigkeit des Fluids durch eine oder mehrere in dem Volumen angeordnete Ultraschall-Messstrecken aufweisend wenigstens eine Ultraschall-Messstrecke zum Messen der Durchflussgeschwindigkeit, wobei die wenigstens eine Ultraschall-Messstrecke in dem Volumen angeordnet ist und einen ihr zugeordneten Ultraschall-Sensor aufweist, um die Durchflussgeschwindigkeit des Fluids zu messen und um wenigstens einen Durchflussgeschwindigkeitsmesswert auszugeben,
• - eine Durchflussgeschwindigkeits-Bestimmungsvorrichtung zur Bestimmung der Durchflussgeschwindigkeit durch das Volumen basiert auf dem wenigstens einen Durchflussgeschwindigkeitsmesswert;
• - einen ersten Drucksensor zur Messung eines ersten Drucks und einen zweiten Drucksensor zur Messung eines zweiten Drucks, wobei der erste Drucksensor und der zweite Drucksensor in dem Volumen angeordnet sind, wobei der erste Drucksensor und der zweite Drucksensor eine Differenzdruck-Bestimmungsstrecke zur Bestimmung eines Differenzdrucks über der Differenzdruck-Bestimmungsstrecke begrenzen,
• - eine Differenzdruck-Bestimmungsvorrichtung zur Bestimmung des Differenzdrucks über der Differenzdruck-Bestimmungsstrecke unter Verwendung des ersten Drucks und des zweiten Drucks,
• - eine Durchflussgeschwindigkeits-Änderungsbestimmungsvorrichtung zur Bestimmung einer Änderung zwischen einem durch die Durchflussgeschwindigkeits-Bestimmungsvorrichtung bestimmten Wert der Durchflussgeschwindigkeit und einem vorangehend durch die Durchflussgeschwindigkeits-Bestimmungsvorrichtung bestimmten Wert der Durchflussgeschwindigkeit und
• - eine Differenzdruck-Änderungsbestimmungsvorrichtung zur Bestimmung einer Änderung zwischen einem durch die Differenzdruck-Bestimmungsvorrichtung bestimmten Wert des Differenzdrucks und einem vorangehend durch die Differenzdruck-Bestimmungsvorrichtung bestimmten Wert des Differenzdrucks, und
• - eine Durchflussgeschwindigkeits-Bewertungsvorrichtung zum Bewerten von durch die Durchflussgeschwindigkeits-Bestimmungsvorrichtung bestimmten Werten für die Durchflussgeschwindigkeit als fehlerfrei oder als fehlerhaft und zum Ausgeben von als fehlerfrei bewerteten Werten für die Durchflussgeschwindigkeit,
• - wobei die Durchflussgeschwindigkeits-Bewertungsvorrichtung ausgebildet ist, um den durch die Durchflussgeschwindigkeits-Bestimmungsvorrichtung bestimmten Wert für die Durchflussgeschwindigkeit als fehlerfrei zu bewerten,
  1. (i) wenn die Änderung zwischen dem durch die Durchflussgeschwindigkeits-Bestimmungsvorrichtung bestimmten Wert der Durchflussgeschwindigkeit und dem vorangehend durch die Durchflussgeschwindigkeits-Bestimmungsvorrichtung bestimmten Wert der Durchflussgeschwindigkeit größer als ein erster Grenzwert für die Änderung der Durchflussgeschwindigkeit ist und die Änderung des Differenzdrucks größer als ein erster Grenzwert für die Änderung des Differenzdrucks ist, oder
  2. (ii) wenn die Änderung zwischen dem durch die Durchflussgeschwindigkeits-Bestimmungsvorrichtung bestimmten Wert der Durchflussgeschwindigkeit und dem vorangehend durch die Durchflussgeschwindigkeits-Bestimmungsvorrichtung bestimmten Wert der Durchflussgeschwindigkeit kleiner als ein zweiter Grenzwert für die Änderung der Durchflussgeschwindigkeit ist und die Änderung des Differenzdrucks kleiner als ein zweiter Grenzwert für die Änderung des Differenzdrucks ist.

Accordingly, the object on which the invention is based is achieved by a device for determining or determining a flow rate of a fluid, in particular a liquid, through a volume, which has the following:

• - the volume, the volume having a fluid inlet and a fluid outlet,
• - a measuring device for measuring the flow rate of the fluid through one or more ultrasonic measuring sections arranged in the volume, having at least one ultrasonic measuring section for measuring the flow rate, the at least one ultrasonic measuring section being arranged in the volume and having an ultrasonic sensor assigned to it to measure the flow rate of the fluid and to output at least one flow rate measurement value,
• - a flow rate determination device for determining the flow rate through the volume based on the at least one flow rate measurement value;
• - a first pressure sensor for measuring a first pressure and a second pressure sensor for measuring a second pressure, the first pressure sensor and the second pressure sensor being arranged in the volume, the first pressure sensor and the second pressure sensor over a differential pressure determination path for determining a differential pressure limit the differential pressure determination section,
• - a differential pressure determination device for determining the differential pressure across the differential pressure determination section using the first pressure and the second pressure,
• - a flow rate change determining device for determining a change between a value of the flow rate determined by the flow rate determining device and a value of the flow rate previously determined by the flow rate determining device and
• - a differential pressure change determination device for determining a change between a value of the differential pressure determined by the differential pressure determination device and a value of the differential pressure previously determined by the differential pressure determination device, and
• - a flow rate evaluation device for evaluating flow rate values determined by the flow rate determination device as error-free or erroneous and for outputting flow rate values evaluated as error-free,
• - wherein the flow rate evaluation device is designed to evaluate the value for the flow rate determined by the flow rate determination device as error-free,
  1. (i) if the change between the flow rate value determined by the flow rate determination device and the flow rate value previously determined by the flow rate determination device is greater than a first limit value for the change in flow rate and the change in the differential pressure is greater than a first limit value for the change of the differential pressure, or
  2. (ii) if the change between the flow rate value determined by the flow rate determination device and the flow rate value previously determined by the flow rate determination device is less than a second limit value for the change in flow rate and the change in the differential pressure is less than a second limit value for the change in differential pressure.

A device with the above-mentioned features leads to increased measurement accuracy, in particular due to the elimination of incorrect measurements by the ultrasonic sensors, which are due to foreign media in the fluid, for example (this can be gas bubbles or air bubbles in a liquid or accumulations of foreign media in the fluid).

In one possible embodiment, the device has more than one ultrasonic measuring section for measuring the flow rate of the fluid, in particular three ultrasonic measuring sections for measuring the flow rate of the fluid, the ultrasonic measuring sections being arranged in succession in the volume downstream or upstream and wherein each ultrasonic measuring section has an associated ultrasonic sensor. This increases the redundancy and also the accuracy of the measurements.

In a further possible embodiment, the differential pressure determination section extends over at least parts of all ultrasonic measurement sections. This increases the accuracy of the measurements.

In an optional configuration, the ultrasonic sensor or at least one of the ultrasonic sensors, in particular all of the ultrasonic sensors, has/have two piezoceramic or piezoelectric elements. This represents a relatively simple but nevertheless robust construction.

The ultrasonic sensor or at least one of the ultrasonic sensors, in particular all of the ultrasonic sensors, can be a time-of-flight sensor. This ensures a high precision of the measurement with relatively low costs for the device and relatively low calculation effort for determining the speed.

As described above, the device can have a plurality of ultrasonic measuring sections. In this case, at least one first ultrasonic measuring section of the more than one ultrasonic measuring section is optionally arranged and designed in such a way that the flow rate of the fluid is measured in a flow direction of the volume and at least one second ultrasonic measuring section of the more than one ultrasonic measuring section is arranged and designed in such a way that the flow rate of the fluid is measured counter to the flow direction of the volume. This increases the redundancy of the measurement and enables precise measurement.

Also in the event that the device has several ultrasonic measuring sections, the flow rate determination device can be designed to determine the flow rate from the flow rates measured in each of the more than one ultrasonic measuring sections by means of the ultrasonic sensors, in particular flow rates measured simultaneously. This also increases the precision of the measurement, among other things.

In one possible embodiment, the device has a measuring process or scanning process initiator, which initiates a measuring process or a scanning process, wherein the measuring process or scanning process initiator works with at least one, in particular all of the ultrasonic measuring sections, in particular the respective ultrasonic sensors and is in communication with the first pressure sensor and the second pressure sensor in order to initiate a measuring process or a scanning process on the respective ultrasonic measuring section, in particular the respective ultrasonic sensor and the first pressure sensor and the second pressure sensor, in particular simultaneously initiate. At this point it should be noted that the meaning of the term "simultaneously" means as simultaneously as possible within the framework of the technical conditions. This means, for example, that two measurement processes that are initiated simultaneously in the sense of the present description can also be initiated sequentially in immediate succession by a processor or a controller, depending on the communication structure of the device. The term "simultaneously" can therefore also be interpreted as "immediately consecutively" if signal paths or communication structures make this necessary.

The device is designed in particular to discard measured values for the flow rate that are incorrect due to foreign media or gas bubbles by using the measuring device for measuring the flow rate and the differential pressure determination device.

In one possible embodiment, the first flow rate change limit is equal to the second flow rate change limit. Alternatively or additionally, the first differential pressure change limit is equal to the second differential pressure change limit. As a result, little effort is required when determining a result with high precision at the same time.

In a further possible embodiment, the value of the flow rate previously determined by the flow rate determination device is the value of the flow rate determined immediately beforehand by the flow rate determination device. As an alternative to this or in addition to this, the value of the differential pressure previously determined by the differential pressure determination device is the value of the differential pressure determined immediately beforehand by the differential pressure determination device. This also serves to obtain a precise result with at the same time little effort to determine the same.

The device can be designed to measure the flow rate value, which is based on the value of the flow rate determined by the flow rate determination device, and the values for the first pressure and the second pressure, which are based on the value of the differential pressure determined by the differential pressure determination device , to be determined approximately, in particular exactly at the same time. Furthermore, as an alternative or in addition to this, the device can be designed to measure the flow rate measurement value, on which the value of the flow rate previously determined by the flow rate determination device is based, and the values for the first pressure and the second pressure, which are based on the value previously determined by the differential pressure Determination device based certain value of the differential pressure, approximately, in particular exactly at the same time to determine.

Optionally, the device has an ultrasonic received signal amplitude determination device for determining peak values of the amplitude for one period of an ultrasonic signal received by the measuring device for measuring the flow rate and an ultrasonic received signal amplitude evaluation device, which is designed to based on of a value for the amplitude and on the basis of the differential pressure determined approximately, in particular exactly at the same time, to evaluate whether the value of the amplitude is to be regarded as an error-free value or whether the value of the amplitude is to be regarded as an incorrect value. The ultrasonic received signal amplitude evaluation device can be designed to, in the case where the value of the amplitude is to be regarded as an erroneous value, on the basis of a peak value for the amplitude determined chronologically beforehand and/or on the basis of a peak value determined chronologically subsequently for the amplitude and on the basis of the differential pressure to evaluate whether the value of the amplitude is to be regarded as an error-free value or whether the value of the amplitude is to be regarded as an incorrect value.

• 1 eine Ausführungsform einer erfindungsgemäßen Vorrichtung in einer Schnittdarstellung; und
• 2 eine Darstellung eines beispielhaften Verlaufs einer Durchflussgeschwindigkeit und eines Differenzdrucks in der Vorrichtung gemäß 1.

The invention is described in the following by way of example with reference to the accompanying drawings using a preferred embodiment. Show in the drawings

• 1 an embodiment of a device according to the invention in a sectional view; and
• 2 a representation of an exemplary course of a flow rate and a differential pressure in the device according to FIG 1 .

In 1 a possible embodiment of a device 10 according to the invention for determining or determining a flow rate of a fluid, in particular a liquid, through a volume 12 is shown. The device 10 has the volume 12 through which the fluid, whose flow rate is to be determined, flows in a flow or flow direction. The volume 12 has a fluid inlet 14 and a fluid outlet 16 . The flow or flow direction is indicated by arrows 18 which define the flow or flow direction as extending from the fluid inlet 14 to the fluid outlet 16 .

The volume 12 has in 1 illustrated embodiment three (in alternative embodiments also two or more than three, i.e. generally several) ultrasonic measuring sections 20-1 (first ultrasonic measuring section), 20-2 (second ultrasonic measuring section) arranged between the fluid inlet 14 and the fluid outlet 16 and 20-3 (third ultrasonic measuring section). The first to third ultrasonic measuring sections 20-1, 20-2 and 20-3 are in 1 illustrated embodiment in the direction of flow or throughflow sequentially arranged between the fluid inlet 14 and the fluid outlet 16.

The three ultrasonic measurement sections 20-1, 20-2 and 20-3 are each delimited by a piezoceramic element (hereinafter also referred to as a piezoceramic sensor) 22-1 to 22-6 at their beginning and end.

The first ultrasonic measuring section 20-1 is delimited by a first piezoceramic sensor 22-1 and a second piezoceramic sensor 22-2, which are components of a first ultrasonic sensor for measuring the flow rate through the first ultrasonic measuring section 20-1. The second ultrasonic measuring section 20-2 is delimited by a third piezoceramic sensor 22-3 and a fourth piezoceramic sensor 22-4, which are components of a second ultrasonic sensor for measuring the flow rate through the second ultrasonic measuring section 20-2. The third ultrasonic measuring section 20-3 is delimited by a fifth piezoceramic sensor 22-5 and a sixth piezoceramic sensor 22-6, which are components of a third ultrasonic sensor for measuring the flow rate through the third ultrasonic measuring section 20-3.

The piezoceramic sensors 22 - 1 to 22 - 6 are arranged in a wall 25 of the volume 12 , alternatively also arranged on the outside of the wall 25 of the volume 12 .

The first and the third ultrasonic measurement section 20-1 and 20-3 and the piezoceramic sensors 22-1, 22-2, 22-5 and 22-6 are designed and arranged such that the flow rate of the fluid in the direction of flow respective assigned ultrasonic measuring section 20-1 and 20-3 is measured. The second ultrasonic measuring section 20-2 or the piezoceramic sensors 22-3 and 22-4 are designed and arranged in such a way that the flow rate of the fluid is measured counter to the flow direction of the associated ultrasonic measuring section 20-2. Each of the ultrasonic measurement sections 20-1, 20-2 and 20-3 is provided with a measuring device 24 for measuring the flow rate of the fluid through each of the ultrasonic measurement sections 20-1, 20-2 and 20 in order to measure or determine the respective flow rate -3 in connection, which measures the flow rate of the fluid through each of the ultrasonic measuring sections 20-1, 20-2 and 20-3 (possibly also determined or determined).

In the embodiment described here, measuring device 24 is therefore provided to determine three measured values, namely the flow rate of the fluid through the first ultrasonic measuring section 20-1, the flow rate of the fluid through the second ultrasonic measuring section 20-2 and the flow rate of the Fluid through the third ultrasonic measuring section 20-3. In alternative embodiments, the measuring device 24 can be provided in order to determine more than three or also fewer than three measured values; the number of measured values generally corresponds to the number of ultrasonic measurement sections present.

To determine the flow rate v of the fluid through the volume 12, the device 10 also has a flow rate determination device 26 for determining the flow rate v through the volume 12, which is connected to the measuring device 24 and from the measuring device 24 output data, ie in the embodiment described here from the flow rate of the fluid through the first ultrasonic measuring section 20-1, the flow rate of the fluid through the second ultrasonic measuring section 20-2 and the flow rate of the fluid through the third ultrasonic measuring section 20- 3 the flow rate v of the fluid through the volume 12 is determined or ascertained.

in the in 1 described embodiment, the flow rate is measured by means of the time-of-flight principle, ie the transit time principle. For this purpose, all of the ultrasonic sensors are time-of-flight sensors, ie all of the piezoceramic sensors 22-1 to 22-6 are time-of-flight sensors. Thus, all measurement sections are time-of-flight measurement sections. In alternative embodiments, one or more of the measurement sections or ultrasonic sensors could be based on the singaround principle or the ultrasonic Doppler principle.

The device 10 also has a first pressure sensor 28 for determining a first pressure p1 and a second pressure sensor 30 for determining a second pressure p2. The first pressure sensor 28 and the second pressure sensor 30 are arranged in the volume 12 . The first pressure sensor 28 and the second pressure sensor 30 delimit or define a differential pressure determination path 32 arranged between them, i.e. between the first pressure sensor 28 and the second pressure sensor 30.

A differential pressure determination device 34 is designed to determine a differential pressure Δp across the differential pressure determination path 32 . As differential pressure Ap (t _pbest) via the differential pressure determination section 32 for determining the time t _pbest is the difference between the the first pressure sensor 28 to the time t _pbest applied pressure p1 and the signal present at the second pressure sensor 30 in approximately at the same time pressure p2 defined ( Δp(t _pbest ) = p1(t _pbest ) - p2(t _pbest )).

It should be noted at this point that when the present application refers to the same time or concurrently, the ent Speaking times, which are mentioned at the same time or are described as being at the same time, can deviate from one another within the framework of technical tolerances or due to a sequential sequence of processes, in particular measuring processes. For example, measurement processes that are described simultaneously can be triggered sequentially or be slightly separated from one another in terms of time due to latencies. This is also illustrated by the fact that the wording is used at about the same time or around the same time.

Taking into account the above remarks, it applies to the above that the time t _vbest , at which the measured value for v is determined, and the time t _pbest , at which the measured value for p1 and p2 and thus also for Δp is determined, in the described _Embodiment are approximately the same, ie t pbest = t _vbest .

Furthermore, the device 10 has a flow rate change determination device 36 (or a flow rate or flow volume change determination device) and a differential pressure change determination device 38 .

The flow rate change determiner 36 (or flow rate or flow volume change determiner) is for determining a change in flow rate δv(t _vbest ) = v(t _vbest ) - v(t _vbest Δt1) between the value determined by the flow rate determiner 26 the flow rate v(t _vbest ) and the value of the flow rate v(t _vbest -Δt1) previously determined by the flow rate determiner 26. Equivalently, instead of the change δ(t _vbest ) in the flow rate v(t _vbest ) of the fluid (flow rate v(t), specified in [m/s]), the change δVol(t _Volbest ) in the flow rate or the flow volume Vol (flow rate or flow volume indicated in [I/h]) through the volume 12, which has a known size or a known cross-section, as in 2 shown, find use. However, these variables are all dependent on the flow rate v(t), so that the respective relative changes at a given point in time are again identical to the change δv(t _vbest ) in the flow rate.

The differential pressure change determination device 38 is provided for determining a change δΔp(t _pbest ) of the differential _pressure Δp(t pbest ). It applies here that δΔp(t _pbest )=Δp(t _pbest )−Δp(t pbest −Δt2), ie the difference between the value of the differential _{pressure Δp(t pbest ) determined by the differential pressure determination} device 34 and the previously determined by the _{Differential pressure} determination device 34 determined value of the differential pressure Δp (t pbest -Δt2).

Again, referring to the above, in the embodiment described herein, the times (t _vbest -Δt1) and (t _pbest -Δt2) are approximately simultaneous. As an alternative to this, points in time separated by time intervals for the respective determination of δ(t _vbest ) and δΔp(t _pbest ) are also conceivable, ie alternatively embodiments are conceivable in which t _vbest and t _{pbest are separated} by a time interval Δt _best . Furthermore, in the present embodiment, Δt1=Δt2 applies, with the values for Δt1 and Δt2 being able to deviate from one another within the scope of technical tolerances or due to a successive sequence of processes, in particular measurement processes. Alternatively, a relation Δt1=Δt2+Δt _{diff is also} conceivable, where Δt _{diff is} a time duration that (in the mathematical sense) can be either positive or negative.

It should also be noted at this point that in the embodiment described here, the value of the flow rate v(t _vbest -Δt1) previously determined by the flow rate determination device 26 is the value of the flow rate determined immediately beforehand by the flow rate determination device 26, and that in the embodiment described here, the value of the differential _pressure Δp(t pbest Δt2) previously determined by the differential pressure determination device 34 is the value of the differential pressure determined immediately beforehand by the differential pressure determination device 34 .

In alternative embodiments, the value of the flow rate v(t vbest -Δt1) previously determined by the flow rate determination device 26 can be the penultimate value or a value of the flow rate determined even further back in time and/or can be the value previously determined by the differential _{pressure determination device 34} of the differential _pressure Δp(t pbest -Δt2) can be the penultimate value of the differential pressure or a value determined even further back in time.

1. (i) die Änderung δv(t_vbest) = v(t_vbest) - v(t_vbest-Δt1) zwischen dem durch die Durchflussgeschwindigkeits-Bestimmungsvorrichtung 26 bestimmten Wert der Durchflussgeschwindigkeit v(t_vbest) und dem vorangehend durch die Durchflussgeschwindigkeits-Bestimmungsvorrichtung 26 bestimmten Wert der Durchflussgeschwindigkeit v(t_vbest-Δt1) größer als ein erster Grenzwert v_grenz1 für die Änderung der Durchflussgeschwindigkeit ist, und die Änderung δΔp(t_pbest) des Differenzdrucks Δp(t_pbest), d.h. die Differenz zwischen dem durch die Differenzdruck-Bestimmungsvorrichtung 34 bestimmten Wert des Differenzdrucks Δp(t_pbest) und dem vorangehend durch die Differenzdruck-Bestimmungsvorrichtung 34 bestimmten Wert des Differenzdrucks Δp(t_pbest-Δt2), größer als ein erster Grenzwert p_grenz1 für die Änderung des Differenzdrucks ist, oder
2. (ii) wenn die Änderung δv(t_vbest) = v(t_vbest) - v(t_vbest-Δt1) zwischen dem durch die Durchflussgeschwindigkeits-Bestimmungsvorrichtung 26 bestimmten Wert der Durchflussgeschwindigkeit v(t_vbest) und dem vorangehend durch die Durchflussgeschwindigkeits-Bestimmungsvorrichtung 26 bestimmten Wert der Durchflussgeschwindigkeit v(t_vbest-Δt1) kleiner als ein zweiter Grenzwert v_grenz2 für die Änderung der Durchflussgeschwindigkeit ist und die Änderung des Differenzdrucks Δp(t_pbest), d.h. d.h. die Differenz zwischen dem durch die Differenzdruck-Bestimmungsvorrichtung 34 bestimmten Wert des Differenzdrucks Δp(t_pbest) und dem vorangehend durch die Differenzdruck-Bestimmungsvorrichtung 34 bestimmten Wert des Differenzdrucks Δp(t_pbest-Δt2), kleiner als ein zweiter Grenzwert p_grenz2 für die Änderung des Differenzdrucks ist.

Furthermore, the device 10 has a flow rate evaluation device 40 for evaluating values determined by the flow rate determination device 26 for the flow rate v as error-free or as incorrect and for outputting values for the flow rate v assessed as error-free. The flow rate evaluation device 40 is off forms in order to assess the value determined by the flow rate determination _device 26 for the flow rate v(t vbest ) as error-free if

1. (i) the change δv(t _vbest ) = v(t _vbest ) - v(t _vbest -Δt1) between the value of the flow rate v(t _vbest ) determined by the flow rate determiner 26 and that previously determined by the flow rate determiner 26 determined value of the flow rate v(t _vbest -Δt1) is greater than a first limit value v _limit1 for the change in the flow rate, and the change δΔp(t _pbest ) of the differential _pressure Δp(t pbest ), ie the difference between the differential pressure value of the differential _{pressure Δp(t pbest ) determined by the determination device 34} and the value of the differential pressure Δp(t pbest -Δt2) previously determined by the differential _pressure determination device 34, is greater than a first limit value p _limit1 for the change in the differential pressure, or
2. (ii) when the change δv(t _vbest ) = v(t _vbest ) - v(t _vbest -Δt1) between the value of the flow rate v(t _{vbest ) determined by the flow rate estimator 26} and that previously determined by the flow rate determiner 26 determined value of the flow rate v(t _vbest -Δt1) is less than a second limit value v _limit2 for the change in the flow rate and the change in the differential _pressure Δp(t pbest ), i.e. the difference between the value determined by the differential pressure determination device 34 of the _{Differential pressure} Δp(t pbest ) and the value of the differential _pressure Δp(t pbest -Δt2) previously determined by the differential pressure determination device 34, is smaller than a second limit value p _limit2 for the change in the differential pressure.

The two limit values are determined empirically (they generally depend on the geometry of the device) and are defined in the embodiment described here as: v _limit1 =10 l/h, v _limit2 =5 l/h, p _limit1 =20 mbar and p _limit2 = 50 mbar. It should be noted at this point that v _limit1 and v _{limit2 can be} easily converted into values that have the unit m/s, ie are specified as distance/time, by knowing the dimensions and the geometry of the device .

In this context, be on 2 referenced, where values for the flow rate v (given here in l/h) and the change δΔp in the differential pressure over time are shown, ie the device 10 repeatedly, in particular continuously, carries out measurements.

Out 2 it can be seen that at the time t _peak1 , at which a first peak in the flow rate occurs (marked by a circle 42 on the left), the flow rate v (upper curve, denoted by reference numeral 44) from around 100 l/h to in increases by about 150 l/h. The change in the flow rate δ(t _peak1 ) = v(t _peak1 ) - v(t _peak1 -Δt1) is about 50 l/h. In contrast, the value for the differential pressure Δp (lower curve, denoted by reference _{numeral 46) in the area around t peak1 remains} almost constant at approximately 50 mbar. The change in the differential pressure δΔp(t _peak1 ) = Δp(t _peak1 ) - Δp(t _peak1 -Δt2) is therefore approximately equal to 0 mbar. The measured value for v(t _peak1 ) is rejected as erroneous because δv(t _peak1 ) is above the limit value v _limit1 , but the value of δΔp(t _peak1 ) is below the limit value p _limit1 .

Out 2 it can also be seen that at the time t _peak2 , at which a second peak in the flow rate occurs (marked by a right-hand circle 47), the flow rate v (upper curve, denoted by reference numeral 44) of approximately 100 l/h increases by about 170 l/h. The change in the flow rate δv(t _peak2 ) = v(t _peak2 ) - v(t _peak2 -Δt1) is about 70 l/h. In contrast, the value for the differential pressure Δp (lower curve, denoted by reference _numeral 46) increases in the area around t peak2 from approximately 50 mbar to approximately 300 mbar. The change in the differential pressure δΔp(t _peak2 ) = Δp(t _peak2 ) - Δp(t _peak2 -Δt2)) is approximately 250 mbar. The measured value for v(t _peak2 ) is determined to be error-free and is output because δv(t _peak2 ) is above the limit value v _limit2 and δΔp(t _peak2 ) is above the limit value p _limit2 .

The embodiment of a device 10 according to the invention described above is particularly well suited for measurements in extreme ranges, for example in the low flow range (0-6000 ml/min), for measurements under pulsating conditions (pulse widths below one millisecond) and for high-precision flow measurements. The device 10 can ensure an accurate and rapid measurement (in particular through the simultaneous measurement in and against the direction of flow and through the large number of measuring sections) in order to measure the flow or the flow rate v. The differential pressure Δp(t) can also be determined quickly. In particular, it is suitable for being able to reliably detect short-term increases or decreases in the flow rate, which means that the measured values can be quickly classified as error-free or erroneous measurements of v(t). Therewith erroneous values of v(t) due to gas bubbles in liquids and/or accumulations of foreign substances or foreign media in the system can be discarded.

One of the fundamental advantages of ultrasonic measurement and differential pressure measurement in this type of application is that the device 10 is not sensitive to vibration due to the lack of moving elements. Ultrasonic measurements can be performed in a low-power mode, which reduces power consumption and allows for a smaller power budget. Another advantage is that the devices are not as bulky as with other measurement principles, such as mechanical measurements. The pressure measurements can also be carried out with little energy expenditure in a small space.

The device 10 also has a measuring process or scanning process initiator 48 which initiates a measuring process or a scanning process. The measuring process or scanning process initiator 48 is in communication with all piezoceramic sensors 22-1 to 22-6 and with the first pressure sensor 28 and the second pressure sensor 30 in order to start a measuring process or a scanning process on the respective ultrasonic measuring section 20- 1 to 20-3, in particular the respective piezoceramic sensor 22-1 to 22-6 and the first pressure sensor 28 and the second pressure sensor 30 to initiate. In the embodiment of 1 the scanning processes on the respective ultrasonic measuring section, in particular the respective piezoceramic sensor 22-1 to 22-6 and the first pressure sensor 28 and the second pressure sensor 30, as already explained above, are initiated simultaneously.

In possible embodiments, the first limit value v _limit1 for the change in flow rate is equal to the second limit value v _limit2 for the change in flow rate. As an alternative to this or in addition to this, the first limit value p _{limit1 for the change in the differential pressure is} equal to the second limit value p limit2 for the change in the differential pressure.

Furthermore, the device 10 is designed to calculate the flow rate measurement values, on which the value of the flow rate v determined by the flow rate determination device 26 is based, and the values for the first pressure p1 and the second pressure p2, which are based on the value determined by the differential pressure determination device 34 certain value of the differential pressure as a basis, to be determined on the basis of simultaneously determined values for the respective variables. The device 10 is also designed to measure the flow rate value, which is the basis of the value of the flow rate previously determined by the flow rate determination device 26, and the values for the first pressure p1 and the second pressure p2, which are based on the previously determined by the differential pressure Determination device 34 specific value of the differential pressure are based, to be determined on the basis of values determined at the same time for the respective variables.

As a further component, device 10 has an ultrasonic received signal amplitude determination device 50 for determining peak values of the amplitude for one period of an ultrasonic signal received from measuring device 24 for measuring the flow rate and an ultrasonic received signal amplitude evaluation device 52, which is designed to evaluate on the basis of a value for the amplitude and on the basis of the differential pressure determined at the same time whether the value of the amplitude is to be regarded as an error-free value or whether the value of the amplitude is to be regarded as an incorrect value. The ultrasonic received signal amplitude evaluation device 52 is designed, in the case in which the value of the amplitude is to be regarded as an erroneous value, on the basis of a peak value for the amplitude determined in a chronologically preceding manner and/or on the basis of a peak value determined in a chronologically subsequent manner for the amplitude and on the basis of the differential pressure to evaluate whether the value of the amplitude is to be regarded as an error-free value or whether the value of the amplitude is to be regarded as an incorrect value.

Although the invention is described on the basis of embodiments with fixed combinations of features, it also includes other conceivable advantageous combinations, as specified in particular, but not exhaustively, by the dependent claims. All features disclosed in the application documents are claimed to be essential to the invention insofar as they are new compared to the prior art, either individually or in combination.

Reference List

10

Device for determining or determining a flow rate of a fluid

12

volume

14

fluid entry

16

fluid leakage

18

arrow

20-1

Ultrasonic measuring section

20-2

Ultrasonic measuring section

20-3

Ultrasonic measuring section

22-1

piezoceramic sensor

22-2

piezoceramic sensor

22-3

piezoceramic sensor

22-4

piezoceramic sensor

22-5

piezoceramic sensor

22-6

piezoceramic sensor

24

Measuring device for measuring the flow rate

25

Volume 12 wall

26

Flow Rate Determination Device

28

first pressure sensor

30

second pressure sensor

32

differential pressure determination section

34

differential pressure determination device

36

Flow rate change determining device

38

differential pressure change determining device

40

flow rate evaluation device

42

left circle

44

upper curve

46

lower curve

47

right circle

48

Scanning Initiator

50

Ultrasonic received signal amplitude determination device

52

Ultrasonic received signal amplitude evaluation device

Claims (17)

Device (10) for determining a flow rate of a fluid, in particular a liquid, through a volume (12), comprising: the volume (12), the volume (12) having a fluid inlet (14) and a fluid outlet (16), a Measuring device (24) for measuring the flow rate of the fluid through one or more ultrasonic measuring sections arranged in the volume (12), having at least one ultrasonic measuring section (20-1, 20-2, 20-3) for measuring the flow rate, wherein the at least one ultrasonic measuring section (20-1, 20-2, 20-3) is arranged in the volume (12) and has an ultrasonic sensor assigned to it in order to measure the flow rate of the fluid and to output at least one flow rate measured value, a flow rate determination device (26) for determining the flow rate through the volume (12) based on the at least one flow rate measurement worth; a first pressure sensor (28) for measuring a first pressure and a second pressure sensor (30) for measuring a second pressure, the first pressure sensor (28) and the second pressure sensor (30) being arranged in the volume (12), the first Pressure sensor (28) and the second pressure sensor (30) delimit a differential pressure determination path (32) for determining a differential pressure across the differential pressure determination path (32), a differential pressure determination device (34) for determining the differential pressure across the differential pressure determination path (32 ) using the first pressure and the second pressure, a flow rate change determiner (36) for determining a change between a value of the flow rate determined by the flow rate determiner (26) and a value of the flow rate previously determined by the flow rate determiner (26). flow rate and a diff limit pressure change determining means (38) for determining a change between a value of the differential pressure determined by the differential pressure determining means (34) and a value of the differential pressure previously determined by the differential pressure determining means (34), and a flow rate evaluating device (40) for evaluating values determined by the flow rate determination device (26) for the flow rate as error-free or as faulty and for outputting values for the flow rate assessed as error-free, the flow rate evaluation device (40) being designed to evaluate the flow rate determined by the flow rate determination device ( 26) evaluate the determined value for the flow rate as error-free, (i) if the change between the value of the flow rate determined by the flow rate determination device (26) and the v value of the flow rate previously determined by the flow rate determination device (26). is greater than a first limit for the change in flow rate and the change in the differential pressure is greater than a first limit for the change in the differential pressure, or (ii) if the change between the value of the flow rate determined by the flow rate determination device (26) and the flow rate value previously determined by the flow rate determining device (26) is less than a second flow rate change limit and the differential pressure change is less than a second differential pressure change limit. Device (10) after claim 1 , wherein the device (10) has more than one ultrasonic measuring section (20-1, 20-2, 20-3) for measuring the flow rate of the fluid, in particular three ultrasonic measuring sections (20-1, 20-2, 20-3 ) for measuring the flow rate of the fluid, wherein the ultrasonic measuring sections (20-1, 20-2, 20-3) are arranged in the volume (12) downstream or upstream one after the other and wherein each ultrasonic measuring section (20-1 , 20-2, 20-3) has an associated ultrasonic sensor. Device (10) after claim 2 , wherein the differential pressure determination section (32) extends over at least parts of all ultrasonic measurement sections (20-1, 20-2, 20-3). Device (10) according to one of the preceding claims, in which the ultrasonic sensor or at least one of the ultrasonic sensors, in particular all of the ultrasonic sensors, has two piezoceramic or piezoelectric elements (22-1, 22-2, 22-3, 22-4, 22-5, 22-6). Device (10) according to one of the preceding claims, wherein the ultrasonic sensor or at least one of the ultrasonic sensors, in particular all of the ultrasonic sensors is a time-of-flight sensor / are time-of-flight sensors. Device (10) according to one of claims 2 until 5 , wherein at least one first ultrasonic measuring section (20-1, 20-2, 20-3) of the more than one ultrasonic measuring sections (20-1, 20-2, 20-3) is arranged and designed in such a way that the flow rate of the fluid is measured in a flow direction of the volume (12) and wherein at least one second ultrasonic measuring section (20-1, 20-2, 20-3) of the more than one ultrasonic measuring section (20-1, 20-2, 20 -3) is arranged and designed in such a way that the flow rate of the fluid is measured counter to the flow direction of the volume (12). Device (10) according to one of claims 2 until 6 , wherein the flow rate determination device (26) is designed to determine from the flow rates measured in each of the more than one ultrasonic measuring sections (20-1, 20-2, 20-3) by means of the ultrasonic sensors, in particular flow rates measured simultaneously to determine the flow rate. Device (10) according to one of the preceding claims, wherein the device (10) has a measuring process or scanning process initiator (48) which initiates a measuring process or a scanning process, the measuring process or scanning process initiator (48 ) is in communication with at least one, in particular all of the ultrasonic measuring sections (20-1, 20-2, 20-3), in particular the respective ultrasonic sensors and with the first pressure sensor (28) and the second pressure sensor (30), to initiate a measurement process or a scanning process on the respective ultrasonic measuring section (20-1, 20-2, 20-3), in particular the respective ultrasonic sensor and the first pressure sensor (28) and the second pressure sensor (30), especially to initiate at the same time. Device (10) according to one of the preceding claims, wherein the device (10) is designed to, by using the measuring device (24) for measuring the flow rate and the differential pressure determination device (34), measured values for the flow rate due to foreign media or gas bubbles are defective. Apparatus (10) according to any one of the preceding claims, wherein the first flow rate change limit is equal to the second flow rate change limit. Apparatus (10) according to any one of the preceding claims, wherein the first differential pressure change limit is equal to the second differential pressure change limit. Apparatus (10) according to any one of the preceding claims, wherein the flow rate value previously determined by the flow rate determination device (26) is the flow rate value determined by the flow rate determination device (26) immediately previously in time. Apparatus (10) according to any one of the preceding claims, wherein the precedent by the value of the differential pressure determined by the differential pressure determining device (34) is the value of the differential pressure determined immediately beforehand by the differential pressure determining device (34). Device (10) according to one of the preceding claims, wherein the device (10) is designed to calculate the flow rate measurement value, on which the value of the flow rate determined by the flow rate determination device (26) is based, and the values for the first pressure and the second pressure, on which the value of the differential pressure determined by the differential pressure determining device (34) is based, approximately, in particular exactly at the same time. Device (10) according to one of the preceding claims, wherein the device (10) is designed to calculate the flow rate measurement value, on which the value of the flow rate previously determined by the flow rate determination device (26) is based, and the values for the first pressure and to determine the second pressure, on which the value of the differential pressure previously determined by the differential pressure determining device (34) is based, approximately, in particular exactly at the same time. Device (10) according to one of the preceding claims, wherein the device (10) has an ultrasonic received signal amplitude determination device (50) for determining peak values of the amplitude for one period of an ultrasonic signal received from the measuring device (24) for measuring the flow rate and has an ultrasound received signal amplitude evaluation device (52) which is designed to evaluate on the basis of a value for the amplitude and on the basis of the differential pressure determined approximately, in particular exactly at the same time, whether the value of the amplitude is an error-free value is to be considered or whether the value of the amplitude is to be considered as an erroneous value. Device (10) after Claim 16 , wherein the ultrasonic received signal amplitude evaluation device (52) is designed, in the case in which the value of the amplitude is to be regarded as an erroneous value, on the basis of a temporally previously determined peak value for the amplitude and/or on the basis of a to evaluate the chronologically subsequent peak value for the amplitude and on the basis of the differential pressure whether the value of the amplitude is to be regarded as an error-free value or whether the value of the amplitude is to be regarded as an incorrect value.

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