Multi-channel ultrasonic flowmeter

Abstract

The multi-channel ultrasonic flowmeter comprises a controller, a double-pulse excitation circuit, a channel selection circuit, a transceiving switching circuit, a signal receiving circuit and a plurality of transducer groups, each transducer group comprises a first transducer and a second transducer, and a polarized positive electrode and a polarized negative electrode of each transducer are respectively connected with the channel selection circuit. The controller controls the channel selection circuit and the transmitting-receiving switching circuit so that a transmission link can be formed between the double-pulse excitation circuit and the gated transducer set, and a first pulse signal and a second pulse signal can enter a polarized positive electrode and a polarized negative electrode of the gated transducer used for excitation respectively to form an electric damping effect. And the afterwave oscillation of the transducer is quickly attenuated, and the secondary echo interference is reduced, so that the next metering can be quickly started, and the metering interval time is shortened.

Description

Technical Field

[0001] Multiple embodiments of the present specification relate to the technical field of ultrasonic flowmeters, and in particular to a multi-channel ultrasonic flowmeter. Background Art

[0002] Under non-ideal flow conditions, such as turbulence, eddy currents or pipe bends, the velocity distribution along the pipe cross section is usually uneven, with profile differences from laminar to turbulent. This uneven distribution makes it difficult for traditional single-point or single-angle velocity measurement technology to accurately capture the entire velocity profile. To overcome this limitation, the industry usually evenly arranges multiple groups of transducers on the circumference of the pipe cross section, or sets transducer groups at different angles along the length of the pipe to capture the evolution of the velocity profile and obtain more accurate velocity measurement results.

[0003] Traditional multi-channel ultrasonic flowmeter products usually use multiple independent transducer drive circuits to achieve switching control of multiple measurement channels. This solution involves duplicating the circuit of a single-channel ultrasonic flowmeter, which causes the hardware circuit cost and power consumption to increase exponentially with the number of channels, and also brings about problems such as an increase in circuit board area. The Chinese utility model patent with patent number CN217276343U discloses a flow measuring box and its ultrasonic transducer multi-channel switching circuit. The patent uses an analog switch to achieve multi-channel switching control, selects the transducer pair through a controller, and controls the working mode of the transceiver switching module to determine which of the selected transducer pairs is responsible for sending and which is responsible for receiving. This method reduces the complexity of the circuit, while also reducing production costs and power consumption.

[0004] However, after the transducer is excited, it continues to vibrate due to inertia (mechanical resonance), which will form a tail oscillation and produce afterwaves. The afterwaves may overlap with the subsequent ultrasonic signal, making it impossible to accurately distinguish between the two consecutive signals, thus causing measurement errors. In order to ensure the separation between the signals, it is necessary to increase the time interval and wait for the afterwave to decay to a level that will not interfere with the subsequent signals. Although this can reduce the measurement error, it also increases the measurement time interval, affecting the real-time and efficiency of the flow rate measurement. Summary of the invention

[0005] The embodiment of this specification provides a multi-channel ultrasonic flowmeter, which effectively reduces the impact of residual waves on measurement accuracy and time interval while maintaining the advantages of multi-channel switching circuits. Its technical solution is as follows: A multi-channel ultrasonic flow meter, comprising: A controller, a double pulse excitation circuit, a channel selection circuit, a transceiver switching circuit, a signal receiving circuit, and a plurality of transducer groups; Each of the transducer groups includes a first transducer and a second transducer, and the polarized positive electrode and the polarized negative electrode of each transducer are respectively connected to the channel selection circuit; The first control output terminal of the controller is connected to the control input terminal of the double pulse excitation circuit to control the double pulse excitation circuit to excite the first pulse signal and the second pulse signal; The channel selection circuit is connected to the transceiver switching circuit, and the second control output end of the controller is connected to the control input end of the channel selection circuit, so as to control the channel selection circuit to form four transmission links between any transducer group and the transceiver switching circuit, with the polarization positive poles and polarization negative poles corresponding to the two transducers in the transducer group as link endpoints; The transceiver switching circuit is connected to the signal receiving circuit and the dual pulse excitation circuit, and the third control output end of the controller is connected to the transceiver switching circuit to control the transceiver switching circuit to change the connectivity between the first pulse signal and the second pulse signal excited by the dual pulse excitation circuit and the signal input end of the signal receiving circuit and the four transmission links.

[0006] As a preferred solution, the transceiver switching circuit includes a downstream switching module and a downstream switching module; The channel selection circuit can form two downstream transmission links with the polarized positive pole and the polarized negative pole of the transducer as link endpoints between the downstream switching module and the first transducer in any transducer group, and form two upstream transmission links with the polarized positive pole and the polarized negative pole of the transducer as link endpoints between the downstream switching module and the second transducer in the transducer group; The downstream switching module and the upstream switching module are both connected to the signal receiving circuit and the dual pulse excitation circuit. The third control output end of the controller is respectively connected to the downstream switching module and the upstream switching module. The downstream switching module is controlled to change the connectivity between the first pulse signal, the second pulse signal excited by the dual pulse excitation circuit and the signal input end of the signal receiving circuit and the two downstream transmission links, and the upstream switching module is controlled to change the connectivity between the first pulse signal, the second pulse signal excited by the dual pulse excitation circuit and the signal input end of the signal receiving circuit and the two upstream transmission links.

[0007] As a preferred solution, the double pulse excitation circuit includes a pulse generator that emits a first pulse signal, a trigger that is connected to the output end of the pulse generator and emits a second pulse signal, and a shunt analog switch; The output end of the pulse generator is connected to the first common end of the shunt analog switch, the output end of the trigger is connected to the second common end of the shunt analog switch, the two selection ends corresponding to the first common end and the second common end of the shunt analog switch are respectively connected to the downstream switching module and the upstream switching module, and the third control output end of the controller is connected to the control end of the shunt analog switch to control the shunt analog switch to change the connectivity between the first pulse signal and the second pulse signal and the downstream switching module and the upstream switching module.

[0008] As a preferred solution, the downstream switching module and the upstream switching module both include a boost analog switch, and a gate end of the boost analog switch is connected to a voltage input source; The strobe terminal corresponding to the first common terminal of the shunt analog switch is connected to the first control terminal of the boost analog switch to control the boost analog switch to change the connection state between the first common terminal of the boost analog switch and the voltage input source to form a new first pulse signal; The selection end corresponding to the second common end of the shunt analog switch is connected to the second control end of the boost analog switch to control the boost analog switch to change the connection state between the second common end of the boost analog switch and the voltage input source to form a new second pulse signal.

[0009] As a preferred solution, two selection terminals of the boost analog switch are respectively connected to the positive electrode and the negative electrode of the voltage input source.

[0010] As a preferred solution, it also includes a load switch, wherein the input end of the load switch is connected to the power supply, and the output end of the load switch is connected to the power supply end of the double pulse excitation circuit; The fourth control output terminal of the controller is connected to the control terminal of the load switch to control the connection state between the power supply and the power supply terminal of the double pulse excitation circuit.

[0011] As a preferred solution, a zero drift compensation circuit is connected between the signal receiving circuit and the transceiver switching circuit, and the zero drift compensation circuit includes a limiting diode, a DC blocking capacitor, a phase correction resistor and a phase correction capacitor; The anode of the limiting diode is grounded and the cathode is connected to the power supply. The clamping end of the limiting diode is connected to the transceiver switching circuit and one end of the DC blocking capacitor. The other end of the DC blocking capacitor is connected to the phase correction resistor. The other end of the phase correction resistor is connected to the signal receiving circuit and the phase correction capacitor. The other end of the phase correction capacitor is grounded.

[0012] As a preferred solution, a signal window switch is connected between the zero drift compensation circuit and the signal receiving circuit; The fifth control output terminal of the controller is connected to the control terminal of the signal window switch to control the connection state between the zero drift compensation circuit and the signal receiving circuit.

[0013] As a preferred solution, the channel selection circuit includes three inverters, four-channel AND gates and four channel selection modules; Each of the channel selection modules is connected to a transducer group; The second control output end of the controller includes a first port and a second port, the first port is connected to the first input end of the three-way inverter and the first input ends of the first, second and fourth AND gates of the four-channel AND gates, respectively, and the second port is connected to the second input end of the three-way inverter and the second input ends of the first, second and third AND gates of the four-channel AND gates, respectively; The first output end of the three-way inverter is connected to the first input end of the third AND gate of the four-channel AND gate, the second output end of the three-way inverter is connected to the second input end of the fourth AND gate of the four-channel AND gate, the output end of the second AND gate of the four-channel AND gate is connected to the third input end of the three-way inverter, and the corresponding output ends of the first AND gate, the third AND gate and the fourth AND gate of the four-channel AND gate and the third output end of the three-way inverter are respectively connected to the corresponding control ends of the four channel selection modules.

[0014] As a preferred solution, the channel selection module is a four-channel analog switch circuit, and the four common ends of the four-channel analog switch circuit are respectively connected to the polarized positive pole and the polarized negative pole corresponding to the two transducers in the transducer group, and one end of the two selection ends corresponding to the four common ends of the four-channel analog switch circuit is grounded, and the other end is connected to the transceiver switching circuit.

[0015] The beneficial effects brought by the technical solutions provided by some embodiments of this specification include at least: 1. The controller controls the channel selection circuit and the transceiver switching circuit to form a transmission link between the double-pulse excitation circuit and the selected transducer group. The first pulse signal and the second pulse signal can enter the polarized positive electrode and the polarized negative electrode of the selected transducer for excitation respectively, forming an electrical damping effect, so that the transducer residual oscillation decays rapidly and the secondary echo interference is reduced, so that the next measurement can be started quickly, shortening the measurement interval time.

[0016] 2. The transceiver switching circuit is divided into a downstream switching module and a upstream switching module to simplify the link switching structure. The downstream switching module only needs to switch the connection between the first transducer in the selected transducer group and the signal input end of the dual-pulse excitation circuit or the signal receiving circuit, thereby determining the receiving state or the excitation state of the first transducer; the upstream switching module only needs to switch the connection between the second transducer in the selected transducer group and the signal input end of the dual-pulse excitation circuit or the signal receiving circuit, thereby determining the receiving state or the excitation state of the second transducer.

[0017] 3. After the pulse generator sends out the first pulse signal, the trigger generates the second pulse signal following the falling edge of the first pulse signal. The controller controls the shunt analog switch to control the flow direction of the first pulse signal and the second pulse signal according to the receiving and transmitting status of the two selected transducers. The first pulse signal and the second pulse signal are successively input by the polarized positive and negative electrodes of the selected transducer in the excited state to form an electrical damping effect. The second pulse signal causes the residual residual oscillation of the transducer after the first pulse signal ends to decay rapidly, reducing the secondary echo interference, thereby shortening the metering interval time of the multi-channel flow meter.

[0018] 4. Abandon the traditional transformer boosting method, use low-voltage pulses to trigger analog switches to quickly switch between the positive and negative poles of the high power input source to form high-voltage pulses, greatly reducing overall power consumption.

[0019] 5. The load switch cuts off the trigger and analog switch power supply when the system is in sleep mode, reducing the system static power consumption to μA level.

[0020] 6. After the echo signal is limited by the limiting diode, the bias voltage is eliminated by the capacitor, and then the phase correction resistor and phase correction capacitor adjust the echo phase to reduce the zero drift error.

[0021] 7. The signal window switch switches the signal from the transceiver switching circuit on and off synchronously according to the switching of the transceiver status of the two transducers, ensuring that the echo signal is correctly captured, isolating crosstalk, and improving the anti-interference ability and measurement accuracy of the ultrasonic flowmeter.

[0022] 8. Use logic gate combination to achieve 2-to-4 channel control. Only 2 controller I / Os are needed to control 4 channels, significantly reducing I / O resource usage.

[0023] 9. Each four-channel analog switch circuit controls the on-off state of a transducer group, making the circuit layout more intuitive, simplified and beautiful. The two ends of the non-selected transducers are grounded by default, which can effectively suppress crosstalk. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0025] Figure 1 It is a structural schematic diagram of a multi-channel ultrasonic flowmeter provided in an embodiment of this specification.

[0026] Figure 2 It is a schematic diagram of the first pulse signal and the second pulse signal being successively input into the positive polarization electrode and the negative polarization electrode of the transducer in the embodiment of this specification.

[0027] Figure 3 It is a structural schematic diagram of a zero drift compensation circuit provided in an embodiment of this specification.

[0028] Figure 4 It is a schematic diagram of the structure of a three-way inverter and a four-channel AND gate provided in the embodiments of this specification.

[0029] Figure 5 It is a schematic diagram of the structure of a chip model ADG5434.

[0030] Figure 6 It is a schematic diagram of the structure of a chip model ADG5433. DETAILED DESCRIPTION

[0031] The technical solutions in the embodiments of this specification will be described clearly and completely below in conjunction with the drawings in the embodiments of this specification.

[0032] The terms "first", "second", "third", etc. in the description and claims of this specification and the above-mentioned drawings are used to distinguish different objects, rather than to describe a specific order. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device that includes a series of steps or units is not limited to the listed steps or units, but optionally includes steps or units that are not listed, or optionally includes other steps or units inherent to these processes, methods, products or devices.

[0033] The following description provides examples and does not limit the scope, applicability or examples set forth in the claims. Changes may be made to the functions and arrangements of the elements described without departing from the scope of the present specification. Various processes or components may be appropriately omitted, substituted or added to each example. For example, the described method may be performed in an order different from the order described, and various steps may be added, omitted or combined. In addition, features described with respect to some examples may be combined in other examples.

[0034] like Figure 1 As shown, a multi-channel ultrasonic flow meter includes a controller 1, a dual-pulse excitation circuit 2, a channel selection circuit 3, a transceiver switching circuit 4, a signal receiving circuit and a plurality of transducer groups 6.

[0035] Each transducer group 6 includes a first transducer and a second transducer, and the positive polarization pole and the negative polarization pole of each transducer are respectively connected to the channel selection circuit 3 .

[0036] The first control output terminal of the controller 1 is connected to the control input terminal of the double pulse excitation circuit 2 to control the double pulse excitation circuit 2 to excite the first pulse signal and the second pulse signal.

[0037] The channel selection circuit 3 is connected to the transceiver switching circuit 4, and the second control output end of the controller 1 is connected to the control input end of the channel selection circuit 3, so as to control the channel selection circuit 3 to form four transmission links between any transducer group 6 and the transceiver switching circuit 4, with the polarization positive pole and polarization negative pole corresponding to each of the two transducers in the transducer group 6 as link endpoints.

[0038] The transceiver switching circuit 4 is connected to the signal receiving circuit and the dual pulse excitation circuit 2, and the third control output end of the controller 1 is connected to the transceiver switching circuit 4 to control the transceiver switching circuit 4 to change the connectivity between the first pulse signal, the second pulse signal excited by the dual pulse excitation circuit 2 and the signal input end of the signal receiving circuit and the four transmission links.

[0039] Illustratively, multiple transducer groups 6 are respectively arranged at different positions on the measured pipeline, and the first transducer and the second transducer in each transducer group 6 are relatively arranged on both sides of the measured pipeline, and they transmit and receive to each other during measurement, that is, when the first transducer is in an exciting state, the second transducer is in a receiving state, or when the first transducer is in a receiving state, the second transducer is in an exciting state. The controller 1 controls the gating state of each node in the channel selection circuit 3 and the transceiver switching circuit 4 so that a transmission link is formed between the dual pulse excitation circuit 2 and the selected transducer group 6, and the first pulse signal and the second pulse signal can respectively enter the polarized positive pole and the polarized negative pole of the selected transducer in the excited state, that is, the two sides of the piezoelectric ceramic element of the transducer.

[0040] Explanatory, the controller 1 can use precise clock control to make the dual-pulse excitation circuit 2 excite a first pulse signal and a second pulse signal with equal pulse width and amplitude and a certain time difference. In this way, the ultrasonic waves generated by the two pulse signals on the load cancel each other out in the residual wave part, forming an electrical damping effect, causing the residual wave oscillation of the transducer to decay rapidly and reduce the secondary echo interference, so that the next measurement can be started quickly, shortening the measurement interval time.

[0041] In multiple embodiments of the specification, the transceiver switching circuit 4 includes a downstream switching module and a downstream switching module.

[0042] The channel selection circuit 3 can form two downstream transmission links between the downstream switching module and the first transducer in any transducer group 6, with the polarization positive pole and the polarization negative pole of the transducer as link endpoints, and form two upstream transmission links between the downstream switching module and the second transducer in the transducer group 6, with the polarization positive pole and the polarization negative pole of the transducer as link endpoints.

[0043] Both the downstream switching module and the upstream switching module are connected to the signal receiving circuit and the dual pulse excitation circuit 2. The third control output end of the controller 1 is respectively connected to the downstream switching module and the upstream switching module. The downstream switching module is controlled to change the connectivity between the first pulse signal, the second pulse signal excited by the dual pulse excitation circuit 2 and the signal input end of the signal receiving circuit and the two downstream transmission links, and the upstream switching module is controlled to change the connectivity between the first pulse signal, the second pulse signal excited by the dual pulse excitation circuit 2 and the signal input end of the signal receiving circuit and the two upstream transmission links.

[0044] Illustratively, the transceiver switching circuit 4 is divided into a downstream switching module and a upstream switching module to simplify the link switching structure. The downstream switching module only needs to switch the connection between the first transducer in the enabled transducer group 6 and the signal input end of the dual-pulse excitation circuit 2 or the signal receiving circuit, thereby determining the receiving state or the excitation state of the first transducer; the upstream switching module only needs to switch the connection between the second transducer in the enabled transducer group 6 and the signal input end of the dual-pulse excitation circuit 2 or the signal receiving circuit, thereby determining the receiving state or the excitation state of the second transducer.

[0045] For illustration, the first transducer and the second transducer in each transducer group 6 are relatively arranged on both sides of the measured pipeline, and the connection direction of the two transducers is at a certain angle to the measured pipeline. The ultrasonic wave emitted by the transducer located upstream of the measured pipeline is propagated along the fluid flow direction, and the ultrasonic wave emitted by the transducer located downstream of the measured pipeline is propagated against the fluid flow direction. In the following text, the transducer arranged upstream is regarded as the first transducer, and the transducer arranged downstream is regarded as the second transducer for explanation.

[0046] Explanatory, the transceiver switching circuit 4 is divided into a downstream switching module and a reverse switching module. The downstream switching module switches the downstream transmission link by connecting the double pulse excitation module to enable the first transducer to be selected for transmission, or by connecting the signal input end of the signal receiving circuit to enable the echo signal received by the first transducer to enter the signal receiving circuit. Similarly, the reverse switching module switches the reverse transmission link by connecting the double pulse excitation module to enable the second transducer to be selected for transmission, or by connecting the signal input end of the signal receiving circuit to enable the echo signal received by the second transducer to enter the signal receiving circuit. The third control output end of the controller 1 outputs opposite control signals to the downstream switching module and the reverse switching module at the same time, or an inverter is set between the third control output end of the controller 1 and one of the switching modules, so that the two are in a receiving connection state and a transmitting connection state respectively, simplifying the switching control logic and simplifying the internal switching structure of the transceiver switching circuit 4.

[0047] Exemplarily, when the first transducer is in an excited state and the second transducer is in a receiving state, the controller 1 enables the two downstream transmission links of the downstream switching module to connect the polarized positive pole and the polarized negative pole of the first transducer to the first pulse signal and the second pulse signal respectively, and the controller 1 enables the upstream transmission link of the upstream switching module to connect the second transducer to the signal input end of the signal receiving circuit; when the second transducer is in an excited state and the first transducer is in a receiving state, the controller 1 enables the two upstream transmission links of the upstream switching module to connect the polarized positive pole and the polarized negative pole of the second transducer to the first pulse signal and the second pulse signal respectively, and the controller 1 enables the downstream transmission link of the downstream switching module to connect the first transducer to the signal input end of the signal receiving circuit.

[0048] In multiple embodiments of the specification, the dual pulse excitation circuit 2 includes a pulse generator that sends out a first pulse signal, a trigger that is connected to the output end of the pulse generator and sends out a second pulse signal, and a shunt analog switch.

[0049] The output end of the pulse generator is connected to the first common end of the shunt analog switch, the output end of the trigger is connected to the second common end of the shunt analog switch, the two selection ends corresponding to the first common end and the second common end of the shunt analog switch are respectively connected to the downstream switching module and the upstream switching module, and the third control output end of the controller 1 is connected to the control end of the shunt analog switch to control the shunt analog switch to change the connectivity between the first pulse signal and the second pulse signal and the downstream switching module and the upstream switching module.

[0050] Illustratively, the shunt analog switch can be two single-pole double-throw switches controlled by the third control output terminal of the controller 1. When the transducer in the downstream position is determined to be used as excitation and the transducer in the upstream position is used as receiving, the first pulse signal output by the pulse generator is sent to the downstream switching module via a single-pole double-throw switch, and is also sent to the downstream switching module via a trigger and another single-pole double-throw switch; when the transducer in the upstream position is determined to be used as excitation and the transducer in the downstream position is used as receiving, the first pulse signal output by the pulse generator is sent to the upstream switching module via a single-pole double-throw switch, and is also sent to the upstream switching module via a trigger and another single-pole double-throw switch.

[0051] Explanatory, see attached Figure 2 After the pulse generator sends out the first pulse signal, a second pulse signal is generated by a trigger following the falling edge of the first pulse signal. The controller 1 controls the shunt analog switch to control the flow direction of the first pulse signal and the second pulse signal according to the receiving and transmitting status of the two selected transducers. The first pulse signal and the second pulse signal are successively input by the polarized positive electrode and the polarized negative electrode of the selected transducer in the excited state to form an electrical damping effect. The second pulse signal causes the residual residual oscillation of the transducer after the end of the first pulse signal to decay rapidly, reducing the secondary echo interference, and obtaining an ultrasonic wave with a single peak and a small residual wave, thereby shortening the metering interval time of the multi-channel flow meter. The controller 1 does not need to use a clock to accurately control the output timing of the two pulses.

[0052] In multiple embodiments of the specification, the downstream switching module and the upstream switching module both include a boost analog switch, and a gate terminal of the boost analog switch is connected to a voltage input source.

[0053] The selection end corresponding to the first common end of the shunt analog switch is connected to the first control end of the boost analog switch to control the boost analog switch to change the connection state between the first common end of the boost analog switch and the voltage input source to form a new first pulse signal.

[0054] The selection end corresponding to the second common end of the shunt analog switch is connected to the second control end of the boost analog switch to control the boost analog switch to change the connection state between the second common end of the boost analog switch and the voltage input source to form a new second pulse signal.

[0055] Illustratively, the voltage input source is selected to output a voltage that is higher than the output voltage of the pulse generator.

[0056] Explanatory, the first pulse signal output by the pulse generator and the second pulse signal output by the trigger are used as control signals for controlling the switching of the boost analog switch, so that the boost analog switch quickly switches between the positive and negative poles of the high power input source to form a high-voltage pulse as a new pulse signal with a higher voltage to replace the original pulse signal with a lower voltage. The traditional transformer boosting method is abandoned, and the overall power consumption is greatly reduced.

[0057] In one embodiment of the specification, two select terminals of the boost analog switch are respectively connected to the positive and negative electrodes of the voltage input source.

[0058] Explanatory, the voltage difference formed when the boost analog switch switches between the two gate terminals is larger, thereby generating a pulse signal with a larger amplitude change.

[0059] In multiple embodiments of the specification, a load switch is also included, the input end of the load switch is connected to the power supply, and the output end of the load switch is connected to the power supply end of the double pulse excitation circuit 2.

[0060] The fourth control output terminal of the controller 1 is connected to the control terminal of the load switch to control the connection state between the power supply and the power supply terminal of the double pulse excitation circuit 2 .

[0061] Explanatory, the load switch cuts off the power supply of the trigger and analog switch when the system is dormant, reducing the system static power consumption to the μA level.

[0062] In multiple embodiments of the specification, Figure 3 As shown, a zero drift compensation circuit is connected between the signal receiving circuit and the transceiver switching circuit 4, and the zero drift compensation circuit includes a limiting diode, a DC blocking capacitor, a phase correction resistor and a phase correction capacitor.

[0063] The anode of the limiting diode is grounded and the cathode is connected to the power supply. The clamping end of the limiting diode is connected to the transmit-receive switching circuit 4 and one end of the DC blocking capacitor. The other end of the DC blocking capacitor is connected to the phase correction resistor. The other end of the phase correction resistor is connected to the signal receiving circuit and the phase correction capacitor. The other end of the phase correction capacitor is grounded.

[0064] Illustratively, the limiting diodes are D9 and D10, the DC blocking capacitor is C120, the phase correction resistor is R81, and the phase correction capacitor is C121.

[0065] Explanatory, the transceiver groups of the transducers are inconsistent in the resonant frequencies of the transducers, resulting in different phase offsets of the echo signals received by each, which causes zero drift error in ultrasonic measurement. After the echo signal is limited by the limiting diode, the bias voltage is eliminated by the capacitor, and then the phase correction resistor and phase correction capacitor adjust the echo phase, thereby reducing the zero drift error.

[0066] In multiple embodiments of the specification, a signal window switch is connected between the zero drift compensation circuit and the signal receiving circuit.

[0067] The fifth control output terminal of the controller 1 is connected to the control terminal of the signal window switch to control the connection state between the zero drift compensation circuit and the signal receiving circuit.

[0068] Illustratively, the signal window switch may be a single pole double throw switch or a dual channel selection chip.

[0069] Explanatory, the signal window switch switches the signal from the transceiver switching circuit 4 on and off synchronously according to the switching of the transceiver states of the two transducers, ensuring that the echo signal is correctly captured, isolating the crosstalk, and improving the anti-interference capability and measurement accuracy of the ultrasonic flowmeter.

[0070] In another embodiment of the specification, a signal window switch and a zero drift compensation circuit are connected between the downstream switching module and the upstream switching module and the signal receiving circuit, and the fifth control output terminal of the controller 1 outputs control signals for controlling the on and off states of the two signal window switches according to the third control output terminal.

[0071] In multiple embodiments of the specification, Figure 4 As shown, the channel selection circuit 3 includes three inverters, four-channel AND gates and four channel selection modules.

[0072] Each channel selection module is connected to a transducer group 6 .

[0073] The second control output end of the controller 1 includes a first port and a second port, the first port is connected to the first input end of the three-way inverter and the first input ends corresponding to the first AND gate, the second AND gate and the fourth AND gate of the four-channel AND gate, and the second port is connected to the second input end of the three-way inverter and the second input ends corresponding to the first AND gate, the second AND gate and the third AND gate of the four-channel AND gate.

[0074] The first output end of the three-way inverter is connected to the first input end of the third AND gate of the four-channel AND gate, the second output end of the three-way inverter is connected to the second input end of the fourth AND gate of the four-channel AND gate, the output end of the second AND gate of the four-channel AND gate is connected to the third input end of the three-way inverter, and the corresponding output ends of the first AND gate, the third AND gate and the fourth AND gate of the four-channel AND gate and the third output end of the three-way inverter are respectively connected to the corresponding control ends of the four channel selection modules.

[0075] Illustrative, Figure 3 U42 is a four-channel AND gate, and U43 is a three-way inverter. Each channel selection module controls the on-off state of a transducer group 6, simplifies the control logic of the channel selection circuit 3, and makes the circuit layout more intuitive, simplified and beautiful.

[0076] Explanatory, the logic gate combination is used to realize 2-to-4 channel control. Only 2 controllers 1I / O are needed to control 4 channels, which significantly reduces the I / O resource usage. The control logic is shown in the table below.

[0077] In multiple embodiments of the specification, the channel selection module is a four-channel analog switch circuit, and the four common ends of the four-channel analog switch circuit are respectively connected to the polarized positive pole and the polarized negative pole corresponding to the two transducers in the transducer group 6, and one end of the two selection ends corresponding to the four common ends of the four-channel analog switch circuit is grounded, and the other end is connected to the transceiver switching circuit 4.

[0078] Explanatory, both ends of the non-gated transducer are grounded by default, which can effectively suppress crosstalk.

[0079] For example, Figure 5 As shown, the model of the four-channel analog switch circuit is ADG5434, and the polarized positive pole and polarized negative pole corresponding to the first transducer and the second transducer of the transducer group 6 are respectively connected to the common terminals D1, D2, D3, and D4 of the four-channel analog switch circuit, and the selection terminals S1A, S2A, S3A, and S4A are respectively connected to the transceiver switching circuit 4 to form four transmission links. The control terminals IN1, IN2, IN3, and IN4 corresponding to each four-channel analog switch circuit are connected to form a common control terminal. A1, A2, A3, and A4 are respectively output to the common control terminals corresponding to the four four-channel analog switch circuits. The transducer group 6 connected to the four-channel analog switch circuit that receives the high level at the common control terminal is selected.

[0080] In one embodiment of the specification, Figure 6 As shown, the downstream switching module and the upstream switching module are three-channel selection modules, model ADG5433.

[0081] For illustration, the three-channel selection module corresponding to the downstream switching module is taken as an example. The common terminals D1 and D2 of the three-channel selection module are respectively connected to the selection terminals S1A and S2A of each four-channel selection module, and another common terminal D3 is connected to the selection terminal S1B of the downstream switching module itself. The selection terminal S1A is connected to the zero drift compensation circuit and the signal window switch to the signal receiving circuit. The control terminals IN1 and IN2 are connected to the third control output terminal of the controller 1, the selection terminal S2A is connected to the second pulse signal after boosting, the selection terminal S2B is grounded, the selection terminal S3A is connected to +15V, the selection terminal S3B is connected to -15V, and the control terminal IN3 is connected to the first pulse signal output by the trigger.

[0082] In summary, the present invention provides a multi-channel ultrasonic flowmeter having many advantages such as low power consumption, simple control logic, flexible transducer transmission and reception switching, expandable channels, low zero drift and high reliability.

[0083] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A multi-channel ultrasonic flow meter, characterized in that: It comprises a controller (1), a dual pulse excitation circuit (2), a channel selection circuit (3), a transceiver switching circuit (4), a signal receiving circuit and a plurality of transducer groups (6); Each of the transducer groups (6) comprises a first transducer and a second transducer, and a polarized positive electrode and a polarized negative electrode of each transducer are respectively connected to a channel selection circuit (3); The first control output terminal of the controller (1) is connected to the control input terminal of the double pulse excitation circuit (2) to control the double pulse excitation circuit (2) to excite the first pulse signal and the second pulse signal; The channel selection circuit (3) is connected to the transceiver switching circuit (4), and the second control output end of the controller (1) is connected to the control input end of the channel selection circuit (3), so as to control the channel selection circuit (3) to form four transmission links between any transducer group (6) and the transceiver switching circuit (4), with the polarization positive poles and polarization negative poles corresponding to the two transducers in the transducer group (6) serving as link endpoints; The transceiver switching circuit (4) is connected to the signal receiving circuit and the dual pulse excitation circuit (2), and the third control output end of the controller (1) is connected to the transceiver switching circuit (4) to control the transceiver switching circuit (4) to change the first pulse signal and the second pulse signal excited by the dual pulse excitation circuit (2) and the connection state between the signal input end of the signal receiving circuit and the four transmission links.

2. A multi-channel ultrasonic flowmeter according to claim 1, characterized in that: The transceiver switching circuit (4) comprises a downstream switching module and a downstream switching module; The channel selection circuit (3) can form two downstream transmission links between the downstream switching module and the first transducer in any transducer group (6), with the polarization positive pole and polarization negative pole of the transducer as link endpoints, and form two upstream transmission links between the downstream switching module and the second transducer in the transducer group (6), with the polarization positive pole and polarization negative pole of the transducer as link endpoints; The downstream switching module and the upstream switching module are both connected to the signal receiving circuit and the dual pulse excitation circuit (2); the third control output end of the controller (1) is respectively connected to the downstream switching module and the upstream switching module; the downstream switching module is controlled to change the connection state between the first pulse signal, the second pulse signal excited by the dual pulse excitation circuit (2) and the signal input end of the signal receiving circuit and the two downstream transmission links; and the upstream switching module is controlled to change the connection state between the first pulse signal, the second pulse signal excited by the dual pulse excitation circuit (2) and the signal input end of the signal receiving circuit and the two upstream transmission links.

3. A multi-channel ultrasonic flowmeter according to claim 2, characterized in that: The double pulse excitation circuit (2) comprises a pulse generator for emitting a first pulse signal, a trigger connected to the output end of the pulse generator and emitting a second pulse signal, and a shunt analog switch; The output end of the pulse generator is connected to the first common end of the shunt analog switch, the output end of the trigger is connected to the second common end of the shunt analog switch, the two selection ends corresponding to the first common end and the second common end of the shunt analog switch are respectively connected to the downstream switching module and the upstream switching module, and the third control output end of the controller (1) is connected to the control end of the shunt analog switch to control the shunt analog switch to change the connection state between the first pulse signal and the second pulse signal and the downstream switching module and the upstream switching module.

4. A multi-channel ultrasonic flowmeter according to claim 3, characterized in that: The downstream switching module and the upstream switching module both include a boost analog switch, and a gate end of the boost analog switch is connected to a voltage input source; The strobe terminal corresponding to the first common terminal of the shunt analog switch is connected to the first control terminal of the boost analog switch to control the boost analog switch to change the connection state between the first common terminal of the boost analog switch and the voltage input source to form a new first pulse signal; The selection end corresponding to the second common end of the shunt analog switch is connected to the second control end of the boost analog switch to control the boost analog switch to change the connection state between the second common end of the boost analog switch and the voltage input source to form a new second pulse signal.

5. A multi-channel ultrasonic flowmeter according to claim 4, characterized in that: The two selection terminals of the boost analog switch are respectively connected to the positive electrode and the negative electrode of the voltage input source.

6. A multi-channel ultrasonic flowmeter according to claim 1, characterized in that: It also includes a load switch, wherein the input end of the load switch is connected to a power supply, and the output end of the load switch is connected to a power supply end of a double pulse excitation circuit (2); The fourth control output terminal of the controller (1) is connected to the control terminal of the load switch to control the connection state between the power supply and the power supply terminal of the double pulse excitation circuit (2).

7. A multi-channel ultrasonic flowmeter according to claim 1, characterized in that: A zero drift compensation circuit is connected between the signal receiving circuit and the transceiver switching circuit (4), and the zero drift compensation circuit comprises a limiting diode, a DC blocking capacitor, a phase correction resistor and a phase correction capacitor; The anode of the limiting diode is grounded, and the cathode is connected to a power supply. The clamping end of the limiting diode is connected to a transceiver switching circuit (4) and one end of the DC blocking capacitor. The other end of the DC blocking capacitor is connected to the phase correction resistor. The other end of the phase correction resistor is connected to a signal receiving circuit and the phase correction capacitor. The other end of the phase correction capacitor is grounded.

8. A multi-channel ultrasonic flowmeter according to claim 7, characterized in that: A signal window switch is connected between the zero drift compensation circuit and the signal receiving circuit; The fifth control output terminal of the controller (1) is connected to the control terminal of the signal window switch to control the connection state between the zero drift compensation circuit and the signal receiving circuit.

9. A multi-channel ultrasonic flowmeter according to claim 1, characterized in that: The channel selection circuit (3) comprises three inverters, four-channel AND gates and four channel selection modules; Each of the channel selection modules is connected to a transducer group (6); The second control output end of the controller (1) comprises a first port and a second port, the first port being connected to the first input end of the three-way inverter and the first input ends of the first, second and fourth AND gates of the four-channel AND gates, respectively, and the second port being connected to the second input end of the three-way inverter and the second input ends of the first, second and third AND gates of the four-channel AND gates, respectively; The first output end of the three-way inverter is connected to the first input end of the third AND gate of the four-channel AND gate, the second output end of the three-way inverter is connected to the second input end of the fourth AND gate of the four-channel AND gate, the output end of the second AND gate of the four-channel AND gate is connected to the third input end of the three-way inverter, and the corresponding output ends of the first AND gate, the third AND gate and the fourth AND gate of the four-channel AND gate and the third output end of the three-way inverter are respectively connected to the corresponding control ends of the four channel selection modules.

10. A multi-channel ultrasonic flowmeter according to claim 9, characterized in that: The channel selection module is a four-channel analog switch circuit, wherein four common ends of the four-channel analog switch circuit are respectively connected to the polarized positive poles and polarized negative poles corresponding to two transducers in the transducer group (6), and one end of the two selection ends corresponding to the four common ends of the four-channel analog switch circuit is grounded, and the other end is connected to the transceiver switching circuit (4).

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