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
  • G01F1/667—Arrangements of transducers for ultrasonic flowmeters; Circuits for operating ultrasonic flowmeters
  • G01F1/668—Compensating or correcting for variations in velocity of sound
• • 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

Definitions

• the invention relates to a method for measuring the flow rate of a fluid in a pipe.
• the invention also relates to a flowmeter suitable for implementing such a flow measurement method.
• each transmission cycle includes:
• ⁇ comprising: o a step of transmitting an ultrasonic wave by the first ultrasonic transducer, o a step of receiving said ultrasonic wave by the second ultrasonic transducer, o a step of measuring a propagation time of the ultrasonic wave from the first ultrasonic transducer to the second ultrasonic transducer,
• a sub-cycle B' comprising: o a step for transmitting an ultrasonic wave by the second ultrasonic transducer, o a step for receiving said ultrasonic wave by the first ultrasonic transducer, o a step for measuring a propagation time of the ultrasonic wave from the second ultrasonic transducer to the first ultrasonic transducer.
• the ultrasonic transducer operating as a transmitter during a given cycle operates as a receiver during the cycle which follows this given cycle.
• the ultrasonic transducer operating as a receiver during a given cycle operates as a transmitter during the cycle following this given cycle.
• the transmission step of the second sub-cycle carried out by a transmission cycle follows the reception step of the first sub-cycle carried out by this same transmission cycle after a period of a few milliseconds ( 4ms) the time for the ultrasound to fade out.
• This method further comprises a step of calculating a fluid flow rate in which the fluid flow rate is calculated from a difference between the measured propagation time of the first measurement cycle performed and the measured propagation time of the second measurement cycle carried out.
• the aim of the invention is therefore to propose a method for measuring the flow rate of a fluid making it possible to determine reliable and precise flow rates.
• the invention also aims to provide such a flow measurement method that is simple, fast and inexpensive in energy.
• the invention also aims to provide a flowmeter suitable for implementing such a flow measurement method.
• the invention therefore relates to a method for measuring the flow rate of a fluid in a pipe, the flow rate being measured using at least two ultrasonic transducers, the method comprising a generation of successive cycles, called cycles of transmissions, controlled by a control unit, each cycle of transmissions comprising:
• - a sub-cycle A comprising: o a step of transmitting an ultrasonic wave by a first ultrasonic transducer among said at least two ultrasonic transducers, o a step of receiving said ultrasonic wave by a second ultrasonic transducer among said at least two ultrasonic transducers, o a step of measuring a propagation time of the ultrasonic wave from the first ultrasonic transducer to the second ultrasonic transducer,
• a sub-cycle B comprising: o a step for transmitting an ultrasonic wave by the second ultrasonic transducer, o a step for receiving said ultrasonic wave by the first ultrasonic transducer, o a step for measuring a propagation time of the ultrasonic wave from the second ultrasonic transducer to the first ultrasonic transducer, the first sub-cycle A and the sub-cycle B of the same cycle of transmissions succeeding one after the other according to a given order, characterized in that the order between the sub-cycle A and the sub- cycle B of a given transmission cycle is reversed with respect to the order between sub-cycle A and sub-cycle B of a transmission cycle immediately preceding said given transmission cycle, and in that it comprises at least one fluid flow rate calculation step in which a flow rate of the fluid flowing in the pipe is calculated from an average between:
• the cycle directly following the given cycle designates the first cycle which follows the given cycle in the succession of cycles carried out in the measurement method.
• the expression “the cycle directly preceding the given cycle” designates the first cycle which precedes the given cycle in all the cycles carried out in the measurement process.
• the difference made during the flow calculation step is multiplied by -1, one cycle out of two, in order to maintain a result of the same sign.
• a first given transmission cycle is separated from a second transmission cycle directly preceding the first given transmission cycle by a duration, called intercycle duration, greater than or equal to 15ms.
• said intercycle duration may be between 15 ms and 4000 ms (4 seconds), in particular between 125 ms and 4000 ms (4 seconds), more particularly between 250 ms and 2000 ms (2 seconds), for example order of 500 ms.
• the sub-cycle A and the sub-cycle B of the same transmission cycle are separated from each other by a duration, called intracycle duration, less than or equal to 10 ms.
• said intracycle duration may be between 1 ms and 10 ms, for example of the order of [0020]
• the fluid flow rate is determined from a predetermined table in which propagation time difference results are associated with flow rates. The table can also take into account the temperature of the fluid.
• the flow measurement method comprises a step of at least partial standby of the control unit between each transmission cycle.
• the sub-cycle A and the sub-cycle B are each carried out during a period of stabilization of the electronic components of the control unit.
• the ultrasonic wave emitted during sub-cycle A and the ultrasonic wave emitted during sub-cycle B of each transmission cycle are each emitted over a predefined transmission time interval.
• the preset transmit time interval can be less than 1 ps.
• the characteristics of this embodiment make it possible to increase the precision of the measurement of the propagation time and to reduce the energy consumption of the flowmeter.
• the ultrasonic wave is generated by a transducer operating as a transmitter from a square electrical pulse.
• the emission of a single electric pulse to generate an ultrasonic wave makes it possible to improve the precision of the measurement by providing an ultrasonic wave whose signal is short.
• the signal may be half a wavelength long. The wake-up time of the flowmeter electronics and the consumption of electrical energy are thus reduced.
• the invention also extends to a flowmeter suitable for implementing a method according to the invention.
• the invention extends to a flow meter comprising:
• a control unit programmed to control a generation of successive cycles, called transmission cycles, each transmission cycle comprising: o a sub-cycle A comprising:
• ⁇ a step of emitting an ultrasonic wave by a first ultrasonic transducer among said at least two ultrasonic transducers
• ⁇ a step for measuring a propagation time of the ultrasonic wave from the first ultrasonic transducer to the second ultrasonic transducer, o a sub-cycle B comprising:
• ⁇ a step of measuring a propagation time of the ultrasonic wave from the second ultrasonic transducer to the first ultrasonic transducer, the sub-cycle A and the sub-cycle B of the same cycle of successive transmissions one after the other according to a given order, characterized in that the order between the sub-cycle A and the sub-cycle B of a given cycle of transmissions is reversed with respect to the order between the sub-cycle cycle A and the sub-cycle B of a transmission cycle directly preceding said given transmission cycle, and in that the control unit is programmed to carry out at least one fluid flow calculation step in which a flow rate of the fluid flowing in the pipe is calculated from an average between: - a difference between the propagation time measured for sub-cycle A and the propagation time measured for sub-cycle B of the same given transmission cycle, and
• the first transducer and the second transducer are adapted to be mounted on a pipe so as to be arranged facing each other in a direction diagonal with respect to a longitudinal axis of the channeling. Nevertheless, nothing prevents the provision of a flow meter comprising two transducers adapted to be placed inside the pipe opposite one another along the longitudinal axis of the pipe.
• a flowmeter comprising a single ultrasonic transducer and an ultrasonic wave reflector arranged inside the pipe. This single ultrasonic transducer is then placed facing the reflector so that this transducer can emit and then receive ultrasonic waves by reflecting them on the reflector.
• the first transducer and the second transducer are the same.
• the flow meter comprises said pipe on which the two ultrasonic transducers are mounted, this pipe having two longitudinal ends comprising a connecting member.
• the invention also relates to a flow measurement method and a flow meter characterized, in combination or not, by all or some of the characteristics mentioned above or below. Regardless of the formal presentation given, unless expressly indicated otherwise, the various characteristics mentioned above or below should not be considered as closely or inextricably linked to each other, the invention possibly relating to only one of them. these structural or functional characteristics, or only part of these structural or functional characteristics, or only part of one of these structural or functional characteristics, or any grouping, combination or juxtaposition of all or part of these structural or functional characteristics .
• FIG. 1 is a sequential diagram representing four successive transmission cycles of a flow measurement method according to the invention
• Figure 2 is a block diagram of a longitudinal section of a flowmeter according to one embodiment of the invention.
• Figure 3 includes timing diagrams representing four successive cycles of a flow measurement method according to the invention.
• a method 28 for measuring the flow rate of a fluid flowing in a pipe is represented according to one embodiment of the invention in FIG.
• This flow measurement method 28 can be implemented by any type of ultrasonic flow meter operating on the basis of measurements of differences in the propagation time of the ultrasonic waves by at least one ultrasonic transducer.
• the flow meter 20 shown in Figure 2 is suitable for implementing the method 28 of measurement.
• This flowmeter 20 comprises a first ultrasonic transducer 23a and a second ultrasonic transducer 23b mounted on a pipe 21 extending longitudinally along and around a theoretical longitudinal axis 27.
• Pipe 21 includes a wall delimiting a passage in which a fluid 26 can flow.
• the transducers 23a, 23b are mounted on the wall of the pipe 21 and arranged opposite one another in a direction 25 diagonal with respect to the longitudinal axis 27 of the pipe 21 .
• Each transducer 23a, 23b is adapted to emit ultrasonic waves and to receive ultrasonic waves.
• each transducer 23a, 23b can function as a transmitting transducer so as to be able to transmit ultrasonic waves or else as a receiving transducer so as to be able to receive ultrasonic waves.
• this transducer 23a, 23b when a transducer 23a, 23b operates as a transmitting transducer, this transducer 23a, 23b is suitable for converting an electric signal into an ultrasonic wave.
• this transducer 23a, 23b operates as a receiving transducer, this transducer 23a, 23b is adapted to convert an ultrasonic wave into an electrical signal.
• the transducers 23a, 23b are arranged so that an ultrasonic wave emitted by one of these two transducers can propagate through the pipe 21 in said diagonal direction 25 to be directly received by the other transducer without reflection. intermediary of the ultrasonic wave on a wall of the pipe.
• nothing prevents, for example, providing a flowmeter comprising two transducers arranged inside the pipe facing each other along the longitudinal axis of the pipeline.
• a flow meter comprising a single ultrasonic transducer and an ultrasonic wave reflector arranged inside the pipe. This single ultrasonic transducer is then placed facing the reflector so that this transducer can emit ultrasonic waves and then receive them by reflecting them on the reflector.
• the flowmeter 20 also comprises a control unit 24 connected to the transducers 23a, 23b by electrically conductive links 22.
• the control unit comprises at least one integrated circuit, chosen in particular from a microcontroller, a microprocessor, an application-specific integrated circuit (better known by the acronym ASIC for "application-specific integrated circuit"), a programmable logic circuit.
• the control unit also includes a memory.
• the control unit also includes a pulse generator, a signal amplifier, a zero crossing detector, a time capture, a sequencing state machine and a calculation processor.
• the control unit 24 includes at least one real-time clock.
• control unit 24 includes two clocks.
• a first clock is used to count most of the propagation time. This clock operates at a frequency greater than 10 MHz, for example of the order of 16 MHz.
• a second clock is used to obtain an accurate measurement of the delay. This second clock is triggered as close as possible to the moment of reception of the ultrasonic wave by the transducer operating as a receiver. This second clock operates at a frequency greater than that of the first clock, in particular at a frequency greater than 1 GHz, for example of the order of 26 GHz.
• This control unit 24 is adapted to control each transducer 23a, 23b to operate them as a transmitter transducer or as a receiver transducer. In particular, when one of the two transducers 23a, 23b is controlled to operate as a transmitter transducer, the other transducer 23a, 23b is controlled to operate as a receiver transducer.
• control unit 24 is adapted to supply the transducer 23a, 23b controlled as transmitter transducer by an electric signal, said control signal, via the electrically conductive link 22 connecting the control unit 24 to this transducer 23a, 23b controlled as a transmitting transducer.
• This transducer 23a, 23b operating as a transmitter transducer is thus suitable for converting this control signal into a ultrasonic wave which then propagates through the pipe 21 to the other transducer 23a, 23b operating as a receiving transducer.
• control unit 24 is adapted to perform an acquisition of an electrical signal, said reception signal, generated by the transducer 23a, 23b controlled to operate as a receiver transducer, this reception signal being generated from an ultrasonic wave received by this transducer 23a, 23b operating as a receiver transducer and transmitted to the control unit 24 via the electrically conductive link 22 connecting the control unit 24 to this transducer 23a, 23b operating as a receiving transducer.
• control unit is adapted to measure a propagation time Tprop of an ultrasonic wave in the pipe 21 between a transducer 23a, 23b emitting this ultrasonic wave and the other transducer 23a, 23b.
• control unit uses its pair of clocks to measure the propagation time from a control signal emitted by the processing unit 24 and a reception signal emitted by the receiver transducer and acquired by the processing unit 24.
• control unit 24 is adapted to control a generation of successive cycles, called transmission cycles, as will now be explained with reference to Figures 1 to 3, in particular in the non-limiting case of four cycles of successive transmissions denoted Ci to C4.
• Each transmission cycle Ci comprises:
• a sub-cycle A comprising: o a step 35 of emission of an ultrasonic wave by the first ultrasonic transducer 23a, o a step 36 of reception of said ultrasonic wave by the second ultrasonic transducer 23b, o a step 37 measuring a propagation time of the ultrasound wave from the first ultrasound transducer 23a to the second ultrasound transducer 23b,
• a sub-cycle B comprising: o a step 38 of emission of an ultrasonic wave by the second ultrasonic transducer 23a, o a step 39 of reception of said ultrasonic wave by the first ultrasonic transducer 23b, o a step 40 of measuring a propagation time of the ultrasound wave from the second ultrasound transducer 23a to the first ultrasound transducer 23b.
• each Ci cycle of transmissions includes a single A sub-cycle and a single B sub-cycle.
• the ultrasonic wave emitted during sub-cycle A and the ultrasonic wave emitted during sub-cycle B of each cycle G of transmissions are each emitted over a predefined transmission time interval 52, 56 ( see figure 3).
• the ultrasonic wave emitted during sub-cycle A and the ultrasonic wave emitted during sub-cycle B of each cycle G of transmissions are each received over a reception time interval 53, 57 (see FIG. 3).
• the ultrasonic wave is generated by the transducer operating as a transmitter from a square electric pulse, for example with a duration of half a wavelength, or from of a square signal of greater duration.
• the predefined transmission time interval 52, 56 is less than 1 ps, more particularly between 100 ns and 250 ns, for example of the order of 125 ns.
• the predefined reception time interval 53, 57 is less than 40 ps, more particularly between 2 ps and 20 ps, for example of the order of 5 ps.
• the flow measurement method 28 makes it possible to measure a flow rate of a fluid 26 flowing in the pipe 21 between the two transducers 23a, 23b at several given instants.
• FIG. 3 shows time diagrams corresponding to four successive cycles Ci to C4.
• Line 29 is a time diagram representing the transmission steps 35 for which the transducer 23a functions as a transmitting transducer. When a transmission step 35 is in progress, this is represented by a slot on line 29.
• the line 30 is a time diagram representing the reception steps 36 for which the transducer 23b operates as a receiver transducer. When a reception step 36 is in progress, this is represented by a slot on line 30.
• Line 31 is a time diagram representing the transmission steps 38 for which the transducer 23b operates as a transmitter transducer. When a transmission step 38 is in progress, this is represented by a slot on line 31 .
• Line 32 is a time diagram representing the reception steps 39 for which the transducer 23a operates as a receiver transducer. When a reception step 39 is in progress, this is represented by a slot on line 32.
• Line 33 is a timing diagram representing throughput calculation steps, described in more detail below.
• a flow calculation step 51 is in progress, this is represented by a slot on line 33.
• the arrows 34 between the calculation steps and the transmission cycles indicate the moment for which the flow is calculated (this calculated flow then being representative of the flow of fluid 26 flowing in the pipe 21 at this moment pointed by the arrow).
• the flow measurement method comprises a generation of cycles C, of successive transmissions controlled by the control unit 24.
• each cycle of transmissions comprises a sub-cycle A comprising a step 35 of transmission over a predefined time interval 52 of transmission, a step 36 of reception over a time interval 53 of predefined reception and a step 37 of measurement of a propagation time Tprop a .
• Each transmission cycle also includes a sub-cycle B comprising a step 38 of sending over a predefined transmission time interval 56, a step 39 of receiving over a predefined reception time interval 57 and a step 40 of measuring a propagation time Tprop b .
• the measurement method comprises at least two transmission cycles. In FIGS. 1 and 3, four cycles Ci to C4 are shown.
• the term "directly”, in particular in the expressions "CM cycle directly succeeding the given cycle G” and "CM cycle directly preceding the given cycle G”, means that the cycle Ci+i directly succeeding the cycle Given G corresponds to the first cycle performed after the given G cycle and that the CM cycle directly preceding the given G cycle corresponds to the last cycle performed before the given C cycle.
• the given cycle G can correspond to any transmission cycle of a measurement method according to the invention.
• the transducer 23a, 23b operating as a transmitting transducer (in particular the transducer 23a in the example shown) for a sub-cycle A operates as a receiving transducer for the sub-cycle B.
• the transducer 23a , 23b operating as a transmitter transducer (in particular the transducer 23b in the example shown) for a sub-cycle A operates as a receiver transducer for the sub-cycle B.
• the ultrasonic wave is emitted by a first transducer (in particular the transducer 23a in the example shown) operating as a transmitter transducer to the second transducer 23a, 23b operating as a receiver transducer.
• the ultrasonic wave is emitted in a first direction of propagation with respect to the direction of flow of the fluid 26, for example upstream.
• the ultrasonic wave is emitted by the second transducer (in particular transducer 23b in the example shown) operating as transmitter transducer to first transducer 23a, 23b operating as receiver transducer.
• the ultrasonic wave is emitted in a second direction of propagation opposite to the first direction, for example downstream.
• the order between sub-cycle A and sub-cycle B of a given transmission cycle is reversed with respect to a transmission cycle directly preceding said given transmission cycle.
• the sub-cycle A is carried out before the sub-cycle B and in a cycle CM directly succeeding the cycle G, the sub-cycle A is carried out after the sub-cycle B.
• the cycles are separated from each other by a duration, called the 55 intercycle duration.
• a given cycle G is separated from a cycle G-/ directly preceding this given cycle G by said duration 55 intercycle.
• This duration 55 intercycle is greater than or equal to 15 ms.
• said intercycle duration 55 may be between 125 ms and 4000 ms (4 seconds), in particular between 250 ms and 4000 ms (4 seconds), more particularly between 250 ms and 2000 ms (2 seconds) for example the order of 500 ms.
• the duration 55 intercycle can be variable. Nevertheless, preferably, the duration 55 intercycle is fixed.
• the pair of clocks makes it possible to start each cycle of transmissions after said duration 55 intercycle.
• sub-cycle A of this transmission cycle is separated from sub-cycle B of this same transmission cycle by a duration, called intracycle duration 54, less than or equal to 10 ms .
• said intracycle duration 54 can be between 1 ms and 10 ms, for example of the order of 4 ms.
• the intracycle duration can be variable. However, preferably, the intracycle duration is fixed. In particular, the pair of clocks makes it possible to start each transmission cycle after said intracycle duration 54 .
• the method comprises at least one step 51 of fluid flow calculation in which a fluid flow flowing in the pipe between a given G cycle and a CM cycle directly following this given C cycle is calculated.
• Each fluid flow calculation step 51 can be performed by the control unit 24 .
• the bit rate calculation steps are preferably performed at the time of the transmission cycles, as illustrated by the line 33 of FIG. 3. Nevertheless, the bit rate calculation steps can also be carried out between the transmission cycles.
• a flow rate of fluid flowing in the pipe between a given cycle G and a cycle CM directly following this given cycle C is calculated from a propagation time Tprop measured during the sub-cycle A of this cycle Ci, a propagation time Tprop measured during sub-cycle B of this given cycle G and a propagation time Tprop“ +1 measured during sub-cycle A of cycle CM and of a propagation time Tprop l - + measured the sub-cycle B of the CM cycle.
• this flow is calculated from an average between:
• - Tprop? is the propagation time of the ultrasonic wave emitted during a sub-cycle A of a given transmission cycle Ci
• Tpropf is the propagation time of the ultrasonic wave emitted during a sub-cycle B of said given cycle G of transmissions
• Tpropi +1 is the propagation time of the ultrasonic wave emitted during a sub-cycle B of a transmission CM cycle directly following said given transmission cycle G,
• Tprop“ +1 is the propagation time of the ultrasonic wave emitted during a sub-cycle A of the transmission cycle CM directly following said given transmission cycle G.
• the fluid flow rate in the pipe between cycle C 2 and cycle C 3 is calculated during calculation step 51 from the formula [Math. 2] next:
• - Tprop% is the propagation time of the ultrasonic wave emitted during a sub-cycle A of a given cycle C 2 of transmissions
• - Tprop is the propagation time of the ultrasonic wave emitted during a sub-cycle B of said cycle C 2 of given transmissions
• Tprop is the propagation time of the ultrasonic wave emitted during a sub-cycle B of a cycle C 3 of transmissions
• Tprop is the propagation time of the ultrasonic wave emitted during a sub-cycle A of cycle C 3 of transmissions.
• the fluid flow rate is determined from a predetermined table in which propagation time difference results are associated with flow rates.
• the table can also take into account the temperature of the fluid.
• the calculated flow rate D12 corresponds to the flow rate of the fluid in the pipe between the cycle Ci and the cycle C 2
• the calculated flow rate D 23 corresponds to the flow rate of the fluid in the pipe between cycle C 2 and cycle C 3
• the calculated flow rate D 34 corresponds to the flow rate of the fluid in the pipe between cycle C 3 and cycle C 4 .
• a flow measurement method makes it possible to obtain more reliable flow rates than those obtained by known flow measurement methods.
• the known throughput measurement methods comprise a succession of cycles, called transmission cycles, each comprising a sub-cycle A', similar to sub-cycle A, and a sub-cycle B', similar in sub-cycle B.
• the ultrasonic wave is emitted by a first ultrasonic transducer to the second ultrasonic transducer in a first direction with respect to the direction of flow of the fluid in the pipe.
• the ultrasonic wave is emitted by the second ultrasonic transducer to the first ultrasonic transducer in a second direction opposite to the first direction.
• the order between the A' sub-cycle and the B' sub-cycle of each transmission cycle is predefined and is the same for each transmission cycle. Furthermore, the sub-cycle A' and the sub-cycle B' of each transmission cycle are separated from each other by a duration of the order of 4 ms.
• the flow rate is calculated from a difference between the transmission time between the two ultrasonic transducers of the ultrasonic wave emitted during the sub-cycle >4' and the time transmission between the two ultrasonic transducers of the sound wave emitted during the sub-cycle B'.
• the inventors have noticed that in these known flow measurement methods, the flow rates calculated from the propagation times of the ultrasonic waves between the transducers are distorted due to an asymmetry in the operating conditions of the flow meter between the two sub -cycles of the same cycle of transmissions.
• the operating conditions of the flow meter during sub-cycle A' may be different from the operating conditions during sub-cycle B'.
• the measurement of the transmission time of the ultrasound wave emitted during sub-cycle B' can be distorted by echoes in the channel of the ultrasound wave emitted during sub-cycle A' due to the time between these two sub-cycles of the order of 4 ms.
• the flow rate calculation can also be distorted by a change in the temperature of the fluid flowing in the pipe or a change in the temperature of the control unit between sub-cycle A' and sub-cycle B'.
• a flow measurement method makes it possible to compensate for flow measurement errors due to differences in operating conditions of a flow meter between sub-cycle A and sub-cycle B of the same cycle. of transmissions by reversing the order between the sub-cycle A and the sub-cycle B between two successive transmission cycles and by calculating the rate from measurements of transmission times measured during the sub-cycles A and the sub-cycles B of these two transmission cycles.
• the operating conditions are different between the sub-cycle A and the sub-cycle B.
• the sub-cycle A is performed before sub-cycle B
• an echo of the ultrasonic wave emitted during sub-cycle A may still be present in the pipe during sub-cycle B, which disturbs the measurement of a transmission time of the ultrasonic wave emitted during this B sub-cycle.
• intercycle is large enough for echoes of ultrasonic waves in the pipe to dissipate.
• sub-cycle B of the second cycle is carried out under conditions at least substantially identical to the conditions under which sub-cycle A of the first cycle is carried out.
• the sub-cycle A of the second cycle is carried out under conditions at least substantially identical to the conditions under which the sub-cycle B of the first cycle is carried out.
• the fact of calculating a flow rate of the fluid flowing in the pipe from an average between a difference in the times of propagation measured during the first cycle and a difference in the propagation times measured during the second cycle makes it possible to compensate for the errors induced by an asymmetry of the operating conditions between the sub-cycle A and the sub-cycle B of the same transmission cycle .
• the flow rates calculated according to a flow measurement method according to the invention are more accurate and more reliable than those calculated using known flow measurement methods.
• Such a flow measurement method is relatively simple, quick and inexpensive to implement.
• the control unit can be easily programmed to be able to implement such a method (duration 55 intercycle which can be fixed, inversion of the order between the sub-cycle A and the sub-cycle B between the transmission cycles successive).
• a measurement method comprises a step 50 of at least partial standby of the control unit 24 between each transmission cycle during said duration 55 intercycle.
• the control unit 24 is put on standby, at least part of the electronic components of the control unit 24 are not powered up.
• the amplifier and time counters are not powered up.
• the processor is also not powered up when the control unit 24 is on standby, the whole unit 24 is then on standby. Since the control unit 24 is put on standby during the intercycle duration 55, the first ultrasonic transducer and the second ultrasonic transducer are not electrically powered and are therefore also put on standby.
• the first clock makes it possible to wake up the control unit so as to carry out each cycle, that is to say that the electronic components of the necessary control unit 24 are powered up again. The calculation steps can then be performed when the control unit 24 is awake during the cycles.
• a lack of precision in the calculated flow rates can also result from an asymmetry in the state of the electronic components of the flow meter between a sub-cycle carried out just after the electronic components of the control unit and a sub-cycle performed when the control unit electronics have already been powered on long enough to stabilize.
• the operating state of the electronic components of the control unit may change before reaching a state (e.g. capacitor charging, internal temperature) for a transient stabilization period (or "initialization" period).
• this transient stabilization period can falsify the flow rate measurements because the operating state of the electronic components of the control unit is different between two sub-cycles of the same transmission cycle if the flow rate is calculated only depending on the transmission times of the ultrasonic waves emitted during this transmission cycle.
• the control unit in sleep mode during the 55 intercycle times and reversing the order between sub-cycle A and sub-cycle B between two successive transmission cycles makes it possible to compensate for errors. induced by the stabilization period of the control unit.
• the state of the electronic components of the flowmeter during the first sub-cycle carried out (for example a sub-cycle A) of a given transmission cycle G is similar to that during the first sub-cycle carried out (for example a sub-cycle B) of a cycle C,+i of transmissions directly following the cycle Ci.
• these first two sub-cycles can each be carried out during a stabilization period of the control unit.
• the state of the electronic components of the flowmeter during the second sub-cycle carried out (for example a sub-cycle B) of cycle G is similar to that during the second sub-cycle carried out (in particular a sub-cycle A) of the G+y cycle. Errors that may result from the stabilization period of the control unit are thus compensated.
• a flow measurement method according to the invention makes it possible to improve the precision of the calculated flow rates.
• the invention can be the subject of numerous variants and applications other than those described above.
• the various structural and functional characteristics of each of the embodiments described above should not be considered as combined and/or closely and/or inextricably linked to each other, but to the opposite as mere juxtapositions.
• the structural and/or functional characteristics of the different embodiments described above can be the subject in whole or in part of any different juxtaposition or any different combination.
• the pipe 21 may be included in the flowmeter, this pipe then having connecting members at its longitudinal ends so as to be able to connect the pipe to a pipe network.
• the flowmeter can embed more than one pair of ultrasonic transducers.
• a processing unit can then be associated with each pair of transducers.
• a single processing unit can successively control the different pairs of transducers.

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

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• 2020
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  • 2021-09-21 EP EP21793981.8A patent/EP4217687A1/de active Pending
  • 2021-09-21 WO PCT/FR2021/051618 patent/WO2022064133A1/fr unknown

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