Flowmeter

Abstract

The utility model discloses a flow meter which comprises a sensing module, a control module, a DAC (Digital-to-Analog Converter) module, a conversion module, an output module and an output end, the sensing module is used for generating a sensing signal, the control module is connected with the sensing module to generate a data signal based on the sensing signal, the DAC module is connected with the control module to convert the data signal into a current signal, the conversion module is connected with the DAC module to convert the current signal into a voltage signal, and the control module is further used for generating an output control signal. And the output module is connected with the control module, the DAC module, the conversion module and the output end so as to gate the current signal or the voltage signal based on the control of the output control signal and output the current signal or the voltage signal through the output end. According to the flow meter, the output port can be reused, self-defined analog quantity types can be output through one output end, and meanwhile the range of the analog quantity can be self-defined. A user can freely switch and select output current or voltage, the precision loading capacity is high, the linear calibration function is achieved, and the circuit optimization cost is low.

Description

Technical Field

[0001] The utility model belongs to the technical field of flow monitoring, in particular to a flow meter. Background Art

[0002] Vortex flowmeters are popular flow measurement instruments in the chemical industry. With the continuous development of industrial control technology, high-precision vortex flow acquisition and analog output are being applied in the field of vortex sensors. Existing sensor manufacturers such as FESTO, CKD, IFM, and SMC all support analog output. These manufacturers primarily use non-domestic integrated digital-to-analog conversion chips to convert the collected flow or temperature signals into 4-20mA or 0-5V analog outputs. However, there are still problems such as incomplete output types, limited compatibility and customization, low load capacity, output accuracy variations, EMC and reliability issues, and complex circuits and high costs.

[0003] The information disclosed in this background technology section is only intended to increase the understanding of the overall background of the present invention, and should not be regarded as an admission or any form of suggestion that the information constitutes the prior art already known to those skilled in the art. Utility Model Content

[0004] The purpose of the utility model is to provide a flow meter which can freely select the type of output analog quantity.

[0005] In order to achieve the above-mentioned purpose, the technical solution provided by a specific embodiment of the present invention is as follows:

[0006] A flowmeter includes a sensing module, a control module, a DAC module, a conversion module, an output module and an output end; the sensing module is used to generate a sensing signal; the control module is connected to the sensing module to generate a data signal based on the sensing signal; the DAC module is connected to the control module to convert the data signal into a current signal; the conversion module is connected to the DAC module to convert the current signal into a voltage signal; the control module is also used to generate an output control signal; the output module is connected to the control module, the DAC module, the conversion module and the output end to select the current signal or the voltage signal based on the control of the output control signal and output it through the output end.

[0007] In one or more embodiments of the present invention, the flow meter further includes a sampling module, and the control module is further configured to generate a sampling control signal. The sampling module is connected to the conversion module and the control module to sample the voltage signal based on the control of the sampling control signal to generate a sampling signal. The control module is further configured to adjust the data signal based on the sampling signal.

[0008] In one or more embodiments of the present invention, the sampling module includes a switch unit and a voltage divider unit. The switch unit is connected to the control module to receive the sampling control signal. The switch unit is connected to the conversion module and the voltage divider unit to control the connection and disconnection between the conversion module and the voltage divider unit based on the sampling control signal. The voltage divider unit is used to divide the voltage signal to generate the sampling signal.

[0009] In one or more embodiments of the present invention, the switch unit includes a first switch subunit and a second switch subunit, the first switch subunit is connected to the control module to receive the sampling control signal, the first switch subunit is connected to the first bias voltage and the second switch subunit to control the on and off between the first bias voltage and the second switch subunit based on the sampling control signal, and the second switch subunit is connected to the conversion module and the voltage divider unit to control the on and off between the conversion module and the voltage divider unit based on the first bias voltage.

[0010] In one or more embodiments of the present invention, the first switch subunit includes a first transistor and a first resistor, the first end of the first resistor and the control end of the first transistor are connected to the control module to receive the sampling control signal, the second end of the first resistor is connected to the ground voltage, the second end of the first transistor is connected to the first bias voltage, and the first end of the first transistor is connected to the second switch subunit.

[0011] In one or more embodiments of the present invention, the second switch subunit includes a second resistor, a third resistor and a second transistor, the first end of the second resistor is connected to the first switch subunit to receive the first bias voltage, the second end of the second resistor and the first end of the third resistor are connected to the control end of the second transistor, the second end of the third resistor and the first end of the second transistor are connected to the conversion module to receive the voltage signal, and the second end of the second transistor is connected to the voltage divider unit.

[0012] In one or more embodiments of the present invention, the conversion module includes a conversion unit and an adjustment unit, the conversion unit is connected to the DAC module to convert the current signal into a first voltage, and the adjustment unit is connected to the conversion unit to adjust the first voltage to generate the voltage signal.

[0013] In one or more embodiments of the present invention, the regulating unit includes an amplifier, a fourth resistor, a fifth resistor and a sixth resistor, the first end of the fourth resistor is connected to the conversion unit to receive the first voltage, the second end of the fourth resistor is connected to the first input end of the amplifier, the first end of the fifth resistor is connected to the second bias voltage, the second end of the fifth resistor and the first end of the sixth resistor are connected to the second input end of the amplifier, and the output end of the amplifier is connected to the second end of the sixth resistor to generate the voltage signal.

[0014] In one or more embodiments of the present invention, the conversion module further includes a voltage follower unit, an input end of the voltage follower unit is connected to the conversion unit to receive the first voltage, and an output end of the voltage follower unit is connected to the adjustment unit.

[0015] In one or more embodiments of the present invention, the flow meter further includes a protection module connected to the output module and the output end; and / or the flow meter further includes a filter module connected to the output module and the output end.

[0016] Compared to existing technologies, this flowmeter features a reusable output port, allowing users to output custom analog values ​​through a single output port, while also allowing users to customize the analog value range. Users can freely switch between output current and voltage, with high accuracy and load capacity, linear calibration capabilities, and low-cost circuit optimization. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments recorded in the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0018] Figure 1 This is a system structure diagram of a flow meter in one embodiment of the present invention.

[0019] Figure 2 1 is a circuit diagram of a DAC module in one embodiment of the present invention.

[0020] Figure 3 2 is a circuit diagram of a conversion module in one embodiment of the present invention.

[0021] Figure 4 2 is a circuit diagram of a sampling module in one embodiment of the present invention.

[0022] Figure 5This is a circuit schematic diagram of the output module, protection module and filter module in one embodiment of the present utility model. DETAILED DESCRIPTION

[0023] In order to enable those skilled in the art to better understand the technical solutions of the present invention, the following will be combined with the drawings of the embodiments of the present invention to clearly and completely describe the technical solutions of the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts should fall within the scope of protection of the present invention.

[0024] The terms "coupled," "connected," or "connected" in this specification encompass both direct and indirect connections. An indirect connection is a connection made through an intermediate medium, such as an electrically conductive medium, which may have parasitic inductance or capacitance. An indirect connection may also include a connection through other active or passive devices, such as switches, follower circuits, or other circuits or components, to achieve the same or similar functional objectives. Furthermore, in this specification, terms such as "first" and "second" are primarily used to distinguish one technical feature from another and do not necessarily require or imply a specific relationship, quantity, or order between these technical features.

[0025] In the detailed description of the specification, reference is made to the accompanying drawings forming a part thereof, wherein like reference numerals designate like parts throughout, and wherein exemplary embodiments that may be implemented are shown by way of example. It should be understood that other embodiments may be utilized and structural or logical changes may be made without departing from the scope of the present disclosure. Therefore, the following detailed description should not be construed in a limiting sense.

[0026] The various operations in the specification may be described as multiple discrete actions or operations in a manner that is most helpful in understanding the claimed subject matter. However, the order of description should not be interpreted as implying that these operations must be sequentially related. Specifically, these operations may not be performed in the order presented. The described operations may be performed in an order different from the described embodiments. Various additional operations may be performed and / or the described operations may be omitted in additional embodiments.

[0027] For the purposes of this disclosure, the phrase "A and / or B" means (A), (B), or (A and B). For the purposes of this disclosure, the phrase "A, B and / or C" means (A), (B), (C), (A and B), (A and C), (B and C), or (A, B and C).

[0028] Various components and devices may be referred to or shown in the singular form in this document (for example, "MOS tube", "transistor", "switch", etc.), but this is only for convenience of discussion, and any element referred to in the singular form may include multiple such elements according to the teachings of this document.

[0029] The specification uses the phrases "in one embodiment," "in other embodiments," or "in some embodiments," which can each refer to one or more of the same or different embodiments. In addition, the terms "including," "comprising," "having," etc. used with respect to the embodiments of the present disclosure are synonymous.

[0030] like Figure 1 As shown, the flow meter in one embodiment of the present invention includes a sensing module 10 , a control module 20 , a DAC module 30 , a conversion module 40 , a sampling module 50 , an output module 60 , a protection module 80 , a filtering module 70 and an output terminal 90 .

[0031] The sensing module 10 is configured to generate a sensing signal. The control module 20 is connected to the sensing module 10 to generate a data signal PWM_Flow based on the sensing signal. The DAC module 30 is connected to the control module 20 to convert the data signal PWM_Flow into a current signal I_Rate. The conversion module 40 is connected to the DAC module 30 to convert the current signal I_Rate into a voltage signal U_Rate. The control module 20 is further configured to generate an output control signal Zero_offset3. The output module 60 is connected to the control module 20, the DAC module 30, the conversion module 40, and an output terminal 90 to select the current signal I_Rate or the voltage signal U_Rate based on the output control signal Zero_offset3 and output the signal through the output terminal 90. The protection module 80 and the filter module 70 are connected to the output module 60 and the output terminal 90. The protection module 80 is configured to provide circuit protection, and the filter module 70 is configured to filter the voltage signal U_Rate or the current signal I_Rate.

[0032] The control module 20 is further configured to generate a sampling control signal USS_EN. The sampling module 50 is connected to the conversion module 40 and the control module 20 to sample the voltage signal U_Rate based on the sampling control signal USS_EN to generate a sampling signal V_ADC. The control module 20 is further configured to adjust the data signal PWM_Flow based on the sampling signal V_ADC.

[0033] In one embodiment, the sensor module 10 senses external flow, generates a primary sensing signal capable of representing flow data, and amplifies and filters the primary sensing signal to form a sensing signal suitable for processing by the control module 20. Based on the flow information in the sensing signal, the control module 20 generates a data signal PWM_Flow in the form of a PWM wave. The data signal PWM_Flow can represent the flow data based on its own frequency.

[0034] In one embodiment, the sampling module 50 may not be provided, and the control module 20 may not generate the sampling control signal USS_EN.

[0035] like Figure 2 As shown, the DAC module 30 includes an ADC chip U2 and its peripheral circuits. The model of the ADC chip U2 is preferably GP8301.

[0036] Pin 3 of the ADC chip U2 is connected to the control module 20 to receive the data signal PWM_Flow. The ADC chip U2 can linearly convert the data signal PWM_Flow with a duty cycle of 0%-100% into an analog current signal I_Rate of 0-24mA, and output the current signal I_Rate through its own pin 7.

[0037] In the peripheral circuit, capacitors C2 and C8 are used for filtering, and resistor R5 is a selected feedback resistor for adjusting the output current range.

[0038] The source of PMOS transistor Q1 is connected to pin 7 of ADC chip U2. The drain of PMOS transistor Q1 is connected to the anode of diode D3 via resettable fuse F3. The cathode of diode D3 ultimately outputs the current signal I_Rate. PMOS transistor Q1, capacitor C7, resistor R2, and Zener diode D2 form a switch heat sink circuit that not only controls the current output but also dissipates the 90% power dissipation at the current output. TVS diode D4 provides overvoltage protection, capacitor C9 provides filtering, resettable fuse F3 provides overcurrent protection, and diode D3 provides reverse polarity protection.

[0039] like Figure 3 As shown, the conversion module 40 includes a conversion unit, a voltage follower unit, and a regulating unit. The conversion unit is connected to the cathode of the diode D3 in the DAC module 30 to convert the current signal I_Rate into a first voltage. The input terminal of the voltage follower unit is connected to the conversion unit to receive the first voltage. The output terminal 90 of the voltage follower unit is connected to the regulating unit. The regulating unit is used to regulate the first voltage to generate a voltage signal U_Rate.

[0040] The conversion unit includes a conversion resistor R32 and a conversion resistor R33. A first end of the conversion resistor R33 is connected to the cathode of the diode D3, a second end of the conversion resistor R33 is connected to the first end of the conversion resistor R32, and a second end of the conversion resistor R32 is connected to the ground voltage.

[0041] In one embodiment, the first end of the conversion resistor R33 is connected to the cathode of the diode D3 via a 0Ω debugging resistor R30. In other embodiments, this debugging resistor may not be provided.

[0042] The current signal I_Rate passes through the conversion resistor R32 and the conversion resistor R33 , and a first voltage generated at the first end of the conversion resistor R33 is I_Rate×(R33+R32), where R33 and R32 are the resistance values ​​of the conversion resistor R33 and the conversion resistor R32 respectively.

[0043] like Figure 3 As shown, the voltage follower unit includes an amplifier chip A1A and a resistor R31. A first end of the resistor R31 forms an input terminal of the voltage follower unit and is connected to a first end of a conversion resistor R33 to receive a first voltage. A second end of the resistor R31 is connected to the first input terminal of the amplifier chip A1A. An output terminal 90 of the amplifier chip A1A is connected to a second input terminal of the amplifier chip A1A and forms an output terminal 90 of the voltage follower unit.

[0044] According to the operational amplifier virtual short principle, the voltage at the second input terminal of the amplifier chip A1A and the voltage at the first output terminal 90 are both the first voltage.

[0045] like Figure 3 As shown, the regulation unit includes an amplifier A1B, a fourth resistor R29, a fifth resistor R27, and a sixth resistor R26. A first end of the fourth resistor R29 is connected to the output terminal 90 of the amplifier chip A1A to receive the first voltage. A second end of the fourth resistor R29 is connected to the first input terminal of the amplifier A1B. A first end of the fifth resistor R27 is connected to the second bias voltage +VDD. A second end of the fifth resistor R27 and a first end of the sixth resistor R26 are connected to the second input terminal of the amplifier A1B. The output terminal 90 of the amplifier A1B is connected to the second end of the sixth resistor R26 to generate the voltage signal U_Rate.

[0046] In one embodiment, the adjustment unit may further include a TVS diode D13 and a fuse F6. The amplifier output terminal 90 is connected to the second end of the sixth resistor R26, the cathode of the TVS diode D13, and the first end of the fuse F6. The second end of the fuse F6 is used to generate the voltage signal U_Rate, and the anode of the TVS diode D13 is connected to the ground voltage. The TVS diode D13 provides overvoltage protection, and the fuse F6 provides overcurrent protection.

[0047] In one embodiment, the first input terminal of the amplifier A1A and the first input terminal of the amplifier A1B are non-inverting input terminals, and the second input terminal of the amplifier A1A and the second input terminal of the amplifier A1B are inverting input terminals.

[0048] Based on the op amp virtual short principle, the voltage at the first input terminal of amplifier A1B is the same as the voltage at the second input terminal. Therefore, the magnitude of voltage signal U_Rate is: U_Rate = I_Rate × (R33 + R32) - (+VDD - I_Rate × (R33 + R32)) ÷ R27 × R26. R27 and R26 are the resistance values ​​of the fifth resistor R27 and the sixth resistor R26, respectively.

[0049] like Figure 4 As shown, the sampling module 50 includes a switch unit and a voltage divider unit. The switch unit is connected to the control module 20 to receive the sampling control signal USS_EN. The switch unit is connected to the second end of the fuse F6 in the conversion module 40 and the voltage divider unit to control the connection between the second end of the fuse F6 and the voltage divider unit based on the sampling control signal USS_EN. The voltage divider unit is used to divide the voltage signal U_Rate to generate a sampling signal V_ADC.

[0050] Among them, the switching unit includes a first switching sub-unit and a second switching sub-unit, the first switching sub-unit is connected to the control module 20 to receive the sampling control signal USS_EN, the first switching sub-unit is connected to the first bias voltage and the second switching sub-unit to control the on and off between the first bias voltage and the second switching sub-unit based on the sampling control signal USS_EN, and the second switching sub-unit is connected to the second end of the fuse F6 and the voltage divider unit to control the on and off between the second end of the fuse F6 and the voltage divider unit based on the first bias voltage.

[0051] The first switch subunit includes a first transistor Q5, a first resistor R46, and a diode D19. The anode of diode D19 is connected to the control module 20 to receive the sampling control signal USS_EN. The first end of the first resistor R46 and the control end of the first transistor Q5 are connected to the cathode of diode D19. Diode D19 is used to prevent backflow. The second end of the first resistor R46 is connected to the ground voltage, the second end of the first transistor Q5 is connected to the first bias voltage, and the first end of the first transistor Q5 is connected to the second switch subunit.

[0052] In other embodiments, the diode D19 may not be provided.

[0053] The second switch subunit includes a second resistor R44, a third resistor R6, and a second transistor Q6. The first end of the second resistor R44 is connected to the first end of the first transistor Q5 to receive the first bias voltage. The second end of the second resistor R44 and the first end of the third resistor R6 are connected to the control end of the second transistor Q6. The second end of the third resistor R6 and the first end of the second transistor Q6 are connected to the second end of the fuse F6 to receive the voltage signal U_Rate. The second end of the second transistor Q6 is connected to the voltage divider unit. The second resistor R44 is used for current limiting, and the third resistor R6 is a pull-up resistor.

[0054] The voltage divider unit includes a first voltage divider resistor R47 and a second voltage divider resistor R48. The first end of the first voltage divider resistor R47 is connected to the second end of the second transistor Q6, and the second end of the first voltage divider resistor R47 is connected to the first end of the second voltage divider resistor R48 to generate a sampling signal V_ADC. The second end of the second voltage divider resistor R48 is connected to ground. The first and second voltage divider resistors R47 and R48 divide the voltage signal U_Rate to generate a sampling signal V_ADC at the second end of the first voltage divider resistor R47 and the first end of the second voltage divider resistor R48, with the magnitude of V_ADC = U_Rate × R48 / (R48 + R47).

[0055] In one embodiment, the first transistor Q5 is an NPN transistor, wherein the first terminal of the first transistor Q5 is an emitter, the second terminal is a collector, and the control terminal is a base. In other embodiments, the first transistor Q5 may also be a PNP transistor or other device, and the connection and control methods thereof may be adjusted accordingly.

[0056] In one embodiment, the second transistor Q6 is a PMOS transistor, wherein the first terminal of the second transistor Q6 is a source, the second terminal is a drain, the control terminal is a gate, and the first bias voltage is a ground voltage. In other embodiments, the second transistor Q6 may be an NMOS transistor or other device, and its connection and control methods may be adaptively adjusted.

[0057] When the control module 20 generates a high-level sampling control signal USS_EN, the first transistor Q5 is turned on, the control terminal voltage of the second transistor Q6 is pulled to the first bias voltage (ground voltage), the second transistor Q6 is turned on, and the voltage divider unit divides the voltage signal U_Rate to generate a sampling signal V_ADC.

[0058] When the control module 20 generates a low-level sampling control signal USS_EN, the first transistor Q5 is turned off, the control terminal voltage of the second transistor Q6 is the same as the first terminal voltage, the second transistor Q6 is turned off, the voltage divider unit does not divide the voltage signal U_Rate, and does not generate the sampling signal V_ADC.

[0059] In one embodiment, the control module 20 performs multi-point sampling of the voltage signal U_Rate. Based on the actual voltage values ​​of the sampled signal V_ADC, it generates a linear equation representing the voltage signal U_Rate and the data signal PWM_Flow. This linear calibration is then performed. Through this linear calibration, the control module 20 can establish a linear relationship between the output analog value and the flow rate. This allows the control module 20 to control the PWM wave data signal PWM_Flow with varying duty cycles, which is then input into the DAC module 30, ensuring that the analog value output corresponds linearly to the flow rate.

[0060] In other embodiments, the control module 20 may collect the sampling signal V_ADC and adjust the data signal PWM_Flow in other ways based on the sampling signal V_ADC, so as to achieve calibration, normalized output or other purposes.

[0061] like Figure 5 As shown, the output module 60 includes a digital selector switch U7. Pin 6 of the digital selector switch U7 is connected to the control module 20 to receive the output control signal Zero_offset3. Pin 1 of the digital selector switch U7 is connected to the cathode of the diode D3 in the DAC module 30 to receive the current signal I_Rate. Pin 3 of the digital selector switch U7 is connected to the second end of the fuse F6 to receive the voltage signal U_Rate. Based on the control of the output control signal Zero_offset3, the digital selector switch U7 outputs the current signal I_Rate or the voltage signal U_Rate through its pin 4.

[0062] In one embodiment, when the output control signal Zero_offset3 is high, the connection between pins 4 and 1 of the digital selector switch U7 is closed, while the connection between pins 4 and 3 of the digital selector switch U7 is disconnected, resulting in the output of the current signal I_Rate. When the output control signal Zero_offset3 is low, the connection between pins 4 and 3 of the switch chip U14 is closed, while the connection between pins 4 and 1 of the switch chip U14 is disconnected, resulting in the output of the voltage signal U_Rate.

[0063] like Figure 5 As shown, protection module 80 includes diode D18 and fuse F2. The anode of diode D18 is connected to ground, the cathode of diode D18 and the first end of fuse F2 are connected to pin 4 of digital select switch U7, and the second end of fuse F2 is connected to output terminal 90. Fuse F2 is used for overcurrent protection, and diode D18 is used for overvoltage protection.

[0064] Preferably, the diode D18 is a TVS diode.

[0065] The filter module 70 includes a capacitor C28 , a first end of the capacitor C28 is connected to the ground voltage, and a second end of the capacitor C28 is connected to the pin 4 of the digital selection switch U7 .

[0066] In other embodiments, the filtering module 70 and / or the protection module 80 may not be provided.

[0067] In practice, sensor module 10 transmits a sensor signal to control module 20. Based on the flow information in the sensor signal, control module 20 generates a flow rate-representing data signal PWM_Flow. DAC module 30 then converts data signal PWM_Flow into a current signal I_Rate. During the conversion process in DAC module 30, by configuring ADC chip U2, the output current signal I_Rate can be customized to an analog output range of 0-20mA, 4-20mA, or another custom range.

[0068] Then, the conversion module 40 converts the current signal I_Rate into a voltage signal U_Rate. By adjusting the resistance of each resistor in the conversion module 40, the range of the output voltage signal U_Rate can be adjusted, such as 0-5V, 1-5V, 0-10V or 1-10V.

[0069] The sampling module 50 samples the voltage signal U_Rate. The control module 20 generates a linear equation representing the voltage signal U_Rate and the data signal PWM_Flow based on the actual voltage value of the sampled signal V_ADC, and then performs linear calibration. This linear calibration allows the control module 20 to establish a linear relationship between the output analog value and the flow rate. This allows the control module 20 to control the PWM wave data signal PWM_Flow with varying duty cycles, which is then input into the DAC module 30, ensuring that the analog value output corresponds linearly to the flow rate.

[0070] Finally, the control module 20 controls the output module 60 by outputting the control signal Zero_offset3 to output the voltage signal U_Rate or the current signal I_Rate to the protection module 80 and the filter module 70 to achieve conduction, and then output it to the outside through the output terminal 90 .

[0071] Based on the above scheme, the flowmeter of this utility model can customize the output analog value range, reuse the output port, and freely select the output current or voltage mode. It can achieve linear calibration, making the analog value linear output, with high precision and load capacity, low circuit optimization cost, and high safety and reliability.

[0072] It is apparent for a person skilled in the art that the present application is not limited to the details of the above-described exemplary embodiments, but that it can be implemented in other concrete forms without departing from the spirit or the essential characteristics of the present application. Therefore, the embodiments should be considered as exemplary and non-limiting, the scope of the present application being defined by the claims appended hereto rather than by the above description, and all the changes which fall within the meaning and the scope of the equivalent elements of the claims are intended to be embraced therein. Any reference signs in the claims should not be construed as limiting the claims to the figures in which the reference signs are used.

[0073] Furthermore, it should be understood that although the present specification is described in terms of embodiments, not every embodiment according to the present specification needs to exhibit each and every characteristic specified in the present specification. The specification can also be described in terms of a single independent technical solution, but this does not mean that each embodiment only contains one independent technical solution. The specification is described in this way only for the sake of clarity, and a person skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by a person skilled in the art.

Claims

1. A flow meter, characterized in that: It includes a sensing module, a control module, a DAC module, a conversion module, an output module and an output terminal; The sensing module is used to generate a sensing signal; The control module is connected to the sensing module to generate a data signal based on the sensing signal; The DAC module is connected to the control module to convert the data signal into a current signal; The conversion module is connected to the DAC module to convert the current signal into a voltage signal; The control module is also used to generate an output control signal; The output module is connected to the control module, the DAC module, the conversion module and the output end to select the current signal or the voltage signal based on the control of the output control signal and output it through the output end.

2. The flow meter according to claim 1, wherein: The flow meter also includes a sampling module, and the control module is further used to generate a sampling control signal. The sampling module is connected to the conversion module and the control module to sample the voltage signal based on the control of the sampling control signal to generate a sampling signal. The control module is also used to adjust the data signal based on the sampling signal.

3. The flow meter according to claim 2, wherein: The sampling module includes a switch unit and a voltage divider unit. The switch unit is connected to the control module to receive the sampling control signal. The switch unit is connected to the conversion module and the voltage divider unit to control the connection and disconnection between the conversion module and the voltage divider unit based on the sampling control signal. The voltage divider unit is used to divide the voltage signal to generate the sampling signal.

4. The flow meter according to claim 3, wherein: The switch unit includes a first switch subunit and a second switch subunit, the first switch subunit is connected to the control module to receive the sampling control signal, the first switch subunit is connected to the first bias voltage and the second switch subunit to control the on and off between the first bias voltage and the second switch subunit based on the sampling control signal, and the second switch subunit is connected to the conversion module and the voltage divider unit to control the on and off between the conversion module and the voltage divider unit based on the first bias voltage.

5. The flow meter according to claim 4, characterized in that The first switch subunit includes a first transistor and a first resistor, the first end of the first resistor and the control end of the first transistor are connected to the control module to receive the sampling control signal, the second end of the first resistor is connected to the ground voltage, the second end of the first transistor is connected to the first bias voltage, and the first end of the first transistor is connected to the second switch subunit.

6. The flow meter according to claim 4, wherein: The second switch subunit includes a second resistor, a third resistor and a second transistor. The first end of the second resistor is connected to the first switch subunit to receive the first bias voltage, the second end of the second resistor and the first end of the third resistor are connected to the control end of the second transistor, the second end of the third resistor and the first end of the second transistor are connected to the conversion module to receive the voltage signal, and the second end of the second transistor is connected to the voltage divider unit.

7. The flow meter according to claim 1, wherein: The conversion module includes a conversion unit and an adjustment unit. The conversion unit is connected to the DAC module to convert the current signal into a first voltage. The adjustment unit is connected to the conversion unit to adjust the first voltage to generate the voltage signal.

8. The flow meter according to claim 7, wherein: The adjustment unit includes an amplifier, a fourth resistor, a fifth resistor and a sixth resistor. The first end of the fourth resistor is connected to the conversion unit to receive the first voltage, the second end of the fourth resistor is connected to the first input end of the amplifier, the first end of the fifth resistor is connected to the second bias voltage, the second end of the fifth resistor and the first end of the sixth resistor are connected to the second input end of the amplifier, and the output end of the amplifier is connected to the second end of the sixth resistor to generate the voltage signal.

9. The flow meter according to claim 7, wherein: The conversion module further includes a voltage follower unit, an input end of the voltage follower unit is connected to the conversion unit to receive the first voltage, and an output end of the voltage follower unit is connected to the adjustment unit.

10. The flow meter according to claim 1, wherein The flow meter further includes a protection module, wherein the protection module is connected to the output module and the output end; and / or The flow meter further includes a filter module connected to the output module and the output end.

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