Flowmeter

Abstract

The utility model discloses a flowmeter, which comprises a sensing module, a control module, a DAC (Digital-to-Analog Converter) module and an output system, and the output system comprises a conversion module, a switch 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 voltage signal, the conversion module is connected with the DAC module to convert the voltage signal into a current signal, and the switch module is connected with the DAC module, the conversion module and the output end. The control module is further used for generating an output control signal, and the switch module is connected with the control module to control connection and disconnection between the voltage signal, the current signal and the output end based on the output control signal. According to the flow meter, the type and range of output analog quantity can be customized, an output port can be reused, and a user can switch and select output current or voltage in a customized mode. The precision loading capacity is high, the zero compensation 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, characterized in that it includes a sensing module, a control module, a DAC module and an output system, wherein the output system includes a conversion module, a switch 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 voltage signal, the conversion module is connected to the DAC module to convert the voltage signal into a current signal, the switch module is connected to the DAC module, the conversion module and the output end, the control module is also used to generate an output control signal, and the switch module is connected to the control module to control the on / off between the voltage signal, the current signal and the output end based on the output control signal.

[0007] In one or more embodiments of the present invention, the output system also includes a zero-point calibration module, and the control module is further used to generate a calibration signal. The zero-point calibration module is connected to the control module to receive the calibration signal, and the zero-point calibration module is connected to the DAC module, the conversion module and the switch module to perform zero-point calibration on the voltage signal based on the calibration signal and transmit the calibrated voltage signal to the conversion module and the switch module.

[0008] In one or more embodiments of the present invention, the zero point calibration module includes a switching unit and a first voltage follower, the input end of the first voltage follower is connected to the DAC module to receive a voltage signal, the switching unit is connected to the control module to receive a calibration signal, the switching unit is connected to the input end of the first voltage follower and the ground voltage to control the on and off between the input end of the first voltage follower and the ground voltage based on the calibration signal, and the output end of the first voltage follower is connected to the conversion module and the switching module.

[0009] In one or more embodiments of the present invention, the zero-point calibration module also includes a first resistor, the first end of the first resistor is connected to the DAC module to receive a voltage signal, and the second end of the first resistor is connected to the input end of the first voltage follower; and / or the zero-point calibration module also includes a second resistor, the first end of the second resistor is connected to the input end of the first voltage follower, and the second end of the second resistor is connected to the switching unit.

[0010] In one or more embodiments of the present invention, the conversion module includes a current generating unit and a conversion resistor, and the current generating unit is connected to the DAC module and the conversion resistor to generate a current signal on the conversion resistor based on the voltage signal.

[0011] In one or more embodiments of the present invention, the current generating unit includes an amplifier, a transistor, a first voltage divider unit and a second voltage divider unit, the first voltage divider unit has a first voltage divider node, and the second voltage divider unit has a second voltage divider node; the first end of the first voltage divider unit is connected to the DAC module to receive a voltage signal, and the second end of the first voltage divider unit is connected to the first end of the conversion resistor; the first end of the second voltage divider unit is connected to the second end of the conversion resistor, and the second end of the second voltage divider unit is connected to the ground voltage; the first input end of the amplifier is connected to the first voltage divider node, the second input end of the amplifier is connected to the second voltage divider node, the output end of the amplifier is connected to the control end of the transistor, the first end of the transistor is connected to the second end of the conversion resistor, and the second end of the transistor is connected to the power supply voltage.

[0012] In one or more embodiments of the present invention, the first voltage-dividing unit includes a first voltage-dividing resistor and a second voltage-dividing resistor, the first end of the first voltage-dividing resistor is used to form the first end of the first voltage-dividing unit, the second end of the first voltage-dividing resistor is connected to the first end of the second voltage-dividing resistor to form a voltage-dividing node of the first voltage-dividing unit, and the second end of the second voltage-dividing resistor is used to form the second end of the first voltage-dividing unit; and / or the second voltage-dividing unit includes a third voltage-dividing resistor and a fourth voltage-dividing resistor, the first end of the third voltage-dividing resistor is used to form the first end of the second voltage-dividing unit, the second end of the third voltage-dividing resistor is connected to the first end of the fourth voltage-dividing resistor to form a second voltage-dividing node, and the second end of the fourth voltage-dividing resistor is used to form the second end of the second voltage-dividing unit.

[0013] In one or more embodiments of the present invention, the conversion module further includes a second voltage follower, an input end of the second voltage follower is connected to the DAC module to receive a voltage signal, and an output end of the second voltage follower is connected to the current generating unit.

[0014] In one or more embodiments of the present invention, the output system further includes a protection module connected to the switch module and the output end; and / or the output system further includes a filter module connected to the switch module and the output end.

[0015] In one or more embodiments of the present invention, the output system is provided with one or more.

[0016] Compared to existing technologies, this flowmeter allows for customized analog output types and ranges, multiplexed output ports, and user-defined switching between current and voltage outputs. It also boasts high precision and load capacity, zero-point compensation, 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 3This is a circuit schematic diagram of a zero point calibration module in one embodiment of the present invention.

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

[0022] Figure 5 This is a circuit diagram of a switch module in one embodiment of the present invention. 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" as used 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 the invention, 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, a flow meter in an embodiment of the present invention is characterized by comprising a sensor module 10, a control module 20, a DAC module 30 and an output system.

[0031] The sensing module 10 is used to generate a sensing signal, the control module 20 is connected to the sensing module 10 to generate a data signal based on the sensing signal, and the DAC module 30 is connected to the control module 20 to convert the data signal into a voltage signal.

[0032] In one embodiment, the sensor module 10 senses external flow and temperature to generate a primary sensing signal, which is then amplified and filtered to form a sensing signal suitable for processing by the control module 20. Based on the flow and temperature information in the sensing signal, the control module 20 generates two data signals in the form of PWM waves: a data signal PWM_FLOW representing the flow rate and a data signal PWM_Temp representing the temperature.

[0033] The DAC module 30 generates voltage signals corresponding to the duty cycle of the PWM signal, specifically, voltage signal U1 based on the data signal PWM_FLOW and voltage signal U2 based on the data signal PWM_Temp. Two output systems are also provided: output system 40 and output system 40'. Output system 40 corresponds to voltage signal U1, while output system 40' corresponds to voltage signal U2.

[0034] In other embodiments, one or more data signals and sensor signals may be generated, and one or more output systems may be provided accordingly.

[0035] The following description will be made by taking the output system 40 as an example. The output system 40' has the same or corresponding structure and working principle as the output system 40.

[0036] like Figure 1 As shown, the output system 40 includes a zero point calibration module 41 , a conversion module 42 , a switch module 43 , a protection module 45 , a filter module 44 and an output terminal 46 .

[0037] The control module 20 is also configured to generate a calibration signal Zero_offset1 and an output control signal Zero_offset3. A zero-point calibration module 41 is connected to the control module 20 to receive the calibration signal Zero_offset1. The zero-point calibration module 41 is connected to the DAC module 30, the conversion module 42, and the switch module 43 to perform zero-point calibration on the voltage signal U1 based on the calibration signal Zero_offset1 and transmit the calibrated voltage signal Uo1 to the conversion module 42 and the switch module 43. The conversion module 42 is configured to convert the voltage signal Uo1 into a current signal AO_Rate. The switch module 43 is connected to the conversion module 42, the protection module 45, and the filter module 44. The protection module 45 and the filter module 44 are connected to an output terminal 46. The switch module 43 is connected to the control module 20 to control the connection and disconnection between the voltage signal Uo1 and the current signal AO_Rate and the protection module 45 and the filter module 44 based on the output control signal Zero_offset3. The protection module 45 is used for circuit protection, and the filtering module 44 is used for filtering the voltage signal Uo1 or the current signal AO_Rate.

[0038] like Figure 2 As shown, the DAC module 30 includes a DAC chip U5 and peripheral circuits. The model of the DAC chip U5 is preferably GP8401. Pin 3 of the DAC chip U5 is connected to the control module 20 through a resistor R54 to receive the data signal PWM_FLOW, and outputs a voltage signal U1 representing flow information through its own pin 8. Pin 4 of the DAC chip U5 is connected to the control module 20 through a resistor R55 to receive the data signal PWM_Temp, and outputs a voltage signal U2 representing temperature information through its own pin 7. The first end of the capacitor C36 is connected to pin 7 of the DAC chip U5, the first end of the capacitor C37 is connected to pin 8 of the DAC chip U5, the second end of the capacitor C36 and the second end of the capacitor C37 are connected to the ground voltage, the capacitor C36 is used to filter the voltage signal U2, and the capacitor C37 is used to filter the voltage signal U1.

[0039] Pin 5 of DAC chip U5 is connected to the chip power supply SVDD, and capacitor C24 is a power supply filter capacitor. Pin 10 of DAC chip U5 is connected to ground via capacitor C5, and pin 10 of DAC chip U5 is connected to pin 9 via resistor R11. Capacitor C5 is used to filter the 5V reference voltage required by DAC chip U5.

[0040] like Figure 3 As shown, the zero point calibration module 41 includes a switch unit, a first voltage follower, a first resistor R66 and a second resistor R67.

[0041] The first end of the first resistor R66 is connected to pin 8 of the DAC chip U5 to receive the voltage signal U1. The second end of the first resistor R66 is connected to the input of the first voltage follower. The first end of the second resistor R67 is connected to the input of the first voltage follower, and the second end of the second resistor R67 is connected to the switch unit. The switch unit is connected to the control module 20 to receive the calibration signal Zero_offset1. The switch unit is connected to the ground voltage to control the connection and disconnection between the second end of the second resistor R67 and the ground voltage based on the calibration signal Zero_offset1. The output terminal 46 of the first voltage follower is connected to the conversion module 42 and the switch module 43 and outputs the calibrated voltage signal Uo1.

[0042] The first resistor R66 and the second resistor R67 are used for current limiting. In other embodiments, the first resistor R66 and / or the second resistor R67 may not be provided.

[0043] Specifically, the switch unit includes a switch chip U13 and a capacitor C30. Pins 1 and 2 of the switch chip U13 are connected to ground. Pin 6 of the switch chip U13 is connected to the control module 20 to receive a calibration signal, Zero_offset1. Pin 5 of the switch chip U13 is connected to a 5V power supply and the first end of the capacitor C30. The second end of the capacitor C30 is connected to ground. Pin 4 of the switch chip U13 is connected to the second end of the second resistor R67. Based on the calibration signal, Zero_offset1, the switch chip U13 controls the connection between the second end of the second resistor R67 and ground.

[0044] The first voltage follower includes an amplifier chip U2A and peripheral circuitry. Pin 3 (the positive input) of the amplifier chip U2A is connected to the second end of the first resistor R66 and the first end of the second resistor R67 via a current-limiting debug resistor R70. Pin 2 (the negative input) of the amplifier chip U2A is connected to pin 1 (the output 46) to form a negative feedback loop and output voltage signal Uo1.

[0045] In one embodiment, when the control module 20 generates a low-level calibration signal, Zero_offset1, the switch chip U13 is disconnected, and the output voltage signal Uo1 of the amplifier chip U2A changes in accordance with the voltage signal U1. When the control module 20 generates a high-level calibration signal, Zero_offset1, the switch chip U13 is closed, and the voltage on pin 3 (the positive input terminal) of the amplifier chip U2A is pulled down to zero potential, and the voltage signal Uo1 is immediately zeroed, thus achieving zero-point calibration.

[0046] like Figure 4 As shown, the conversion module 42 includes a second voltage follower, a current generating unit, and a conversion resistor R57. The input terminal of the second voltage follower is connected to pin 1 of the amplifier chip U2A to receive the voltage signal Uo1, and the output terminal 46 of the second voltage follower is connected to the current generating unit. The current generating unit is connected to the conversion resistor to generate a current signal AO_Rate across the conversion resistor based on the voltage signal Uo1.

[0047] Specifically, the second voltage follower includes an amplifier chip U1A, a charge pump chip U4, and peripheral circuits. Pin 3 (positive input) of amplifier chip U1A is connected to pin 1 of amplifier chip U2A to receive voltage signal Uo1. Pin 2 (negative input) and pin 1 (output 46) of amplifier chip U1A are connected to the current generating unit.

[0048] Pin 2 of the charge pump chip U4 is connected to the 5V power supply voltage. The charge pump chip U4 is used to generate a -5V voltage G- through its own pin 1. Pin 11 of the amplifier chip U1A is connected to pin 1 of the charge pump chip U4 to receive the -5V voltage.

[0049] Specifically, the current generating unit includes an amplifier U1D, a transistor Q1, a first voltage dividing unit, a second voltage dividing unit and a resistor R9. The first voltage dividing unit has a first voltage dividing node, and the second voltage dividing unit has a second voltage dividing node.

[0050] A first end of the first voltage dividing unit is connected to pin 1 of the amplifier chip U1A to receive the voltage signal Uo1 , and a second end of the first voltage dividing unit is connected to a first end of the conversion resistor R57 .

[0051] A first end of the second voltage dividing unit is connected to the second end of the conversion resistor R57 , and a second end of the second voltage dividing unit is connected to the ground voltage.

[0052] A first input terminal of amplifier U1D is connected to a first voltage-dividing node, a second input terminal of amplifier U1D is connected to a second voltage-dividing node, an output terminal 46 of amplifier U1D is connected to a first terminal of resistor R9, a second terminal of resistor R9 is connected to a control terminal of transistor Q1, a first terminal of transistor Q1 is connected to a second terminal of switching resistor R57, and a second terminal of transistor Q1 is connected to a power supply voltage. Resistor R9 is used for current limiting.

[0053] The first voltage-dividing unit includes a first voltage-dividing resistor R5 and a second voltage-dividing resistor R1. The first end of the first voltage-dividing resistor R5 is used to form a first end of the first voltage-dividing unit, the second end of the first voltage-dividing resistor R5 is connected to the first end of the second voltage-dividing resistor R1 to form a first voltage-dividing node, and the second end of the second voltage-dividing resistor R1 is used to form a second end of the first voltage-dividing unit.

[0054] The second voltage dividing unit includes a third voltage dividing resistor R14 and a fourth voltage dividing resistor R13, the first end of the third voltage dividing resistor R14 is used to form the first end of the second voltage dividing unit, the second end of the third voltage dividing resistor R14 is connected to the first end of the fourth voltage dividing resistor R13 to form a second voltage dividing node, and the second end of the fourth voltage dividing resistor R13 is used to form the second end of the second voltage dividing unit.

[0055] In one embodiment, the conversion module 42 further includes a capacitor C38 and a current-limiting debugging resistor R51. The second end of the conversion resistor R57 is connected to the first end of the capacitor C38 and the first end of the current-limiting debugging resistor R51. The second end of the capacitor C38 is connected to the ground voltage. The second end of the current-limiting debugging resistor R51 is connected to the switch module 43 to output the current signal AO_Rate. The capacitor C38 is used to filter the current signal AO_Rate. In other embodiments, one or more of the resistor R9, the capacitor C38, and the current-limiting debugging resistor R51 may not be provided.

[0056] In one embodiment, the resistances of the first voltage-divider resistor R5, the second voltage-divider resistor R1, the third voltage-divider resistor R14, and the fourth voltage-divider resistor R13 are all equal. The first input terminal of the amplifier U1D is a positive input terminal, and the second input terminal of the amplifier U1D is a negative input terminal. The transistor Q1 is an NPN transistor, wherein the first terminal of the transistor Q1 is an emitter, the second terminal of the transistor Q1 is a collector, and the control terminal of the transistor Q1 is a base.

[0057] Due to the virtual short, the voltage at the first input terminal of amplifier U1D is equal to the voltage at the second input terminal of amplifier U1D. The voltage at the second terminal of conversion resistor R57 is Ua1, the voltage at the first terminal of conversion resistor R57 is Ub1, and the resistance of conversion resistor R57 is R57.

[0058] Through voltage division by the first voltage divider unit, the voltages at the first input terminal and the second input terminal of the amplifier U1D are both (Uo1-Ub1) / 2+Ub1.

[0059] After voltage division by the second voltage dividing unit, the voltage Ua1 is 2*((Uo1-Ub1) / 2+Ub1)=Uo1+Ub1.

[0060] The voltage difference across the conversion resistor R57 is Ua1 - Ub1 = Uo1 , and the magnitude of the current signal AO_Rate on the conversion resistor R57 is Uo1 / R57 .

[0061] In other embodiments, the resistance values of the first, second, third, and fourth voltage-divider resistors R5, R1, R14, and R13 can be in other proportional relationships. By modifying the ratios of the respective voltage-divider resistors, the proportional relationship between the current signal AO_Rate and the voltage signal Uo1 can be adjusted. Transistor Q1 can also be a PNP transistor or other device, and its connection method can be adaptively adjusted.

[0062] like Figure 5 As shown, the switch module 43 includes a switch chip U14 and peripheral circuits. Pin 1 of the switch chip U14 is connected to the second end of the current-limiting debugging resistor R51 to receive the current signal AO_Rate. Pin 3 of the switch chip U14 is connected to pin 2 of the amplifier chip U2A to receive the voltage signal Uo1. Pin 6 of the switch chip U14 is connected to the control module 20 to receive the output control signal Zero_offset3. Pin 4 of the switch chip U14 is connected to the protection module 45 and the filter module 44. Based on the output control signal Zero_offset3, the switch chip U14 controls the connection and disconnection between the current signal AO_Rate and the voltage signal Uo1 and the protection module 45 and the filter module 44.

[0063] In one embodiment, when the output control signal Zero_offset3 is at a high level, the connection between pins 4 and 1 of the switch chip U14 is closed, the connection between pins 4 and 3 of the switch chip U14 is disconnected, and the protection module 45 and the filter module 44 receive the current signal AO_Rate. When the output control signal Zero_offset3 is at a low level, the connection between pins 4 and 3 of the switch chip U14 is closed, the connection between pins 4 and 1 of the switch chip U14 is disconnected, and the protection module 45 and the filter module 44 receive the voltage signal Uo1.

[0064] Protection module 45 includes a diode D3 and a resettable fuse F3. The cathode of diode D3 and the first end of resettable fuse F3 are connected to pin 4 of switch chip U14. The anode of diode D3 is connected to ground voltage. The second end of resettable fuse F3 is connected to output terminal 46. Resettable fuse F3 is used for overcurrent protection, and diode D3 is used for overvoltage protection.

[0065] Preferably, the diode D3 is a TVS diode.

[0066] The filter module 44 includes a capacitor C22 , a first end of the capacitor C22 is connected to the pin 4 of the switch chip U14 , and a second end of the capacitor C22 is connected to the ground voltage.

[0067] In one embodiment, the flow meter further includes a power network module for system power supply and input end EMC protection.

[0068] In actual applications, the sensing module 10 transmits the sensing signal to the control module 20 . The control module 20 generates a data signal PWM_FLOW representing the flow rate based on the flow rate information in the sensing signal. The DAC chip U5 converts the data signal PWM_FLOW into a voltage signal U1 .

[0069] When the duty cycle of the data signal PWM_FLOW is 0, the control module 20 generates a high-level calibration signal Zero_offset1 to close the switch chip U13, performing zero-point calibration on the voltage signal U1 and ensuring that the zero point of the calibrated voltage signal Uo1 is at the standard zero potential. When the duty cycle of the data signal PWM_FLOW is not 0, the control module 20 generates a low-level calibration signal Zero_offset1 to open the switch unit, causing the amplifier chip U2A to output the voltage signal Uo1 in accordance with the voltage signal U1.

[0070] Next, the conversion module 42 converts the voltage signal Uo1 into a current signal AO_Rate. During this process, the control module 20 first controls the frequency range of the data signal PWM_FLOW, thereby controlling the range of the voltage signal Uo1 to conform to a standard signal range, such as 0-5V, 1-5V, 0-10V, or 1-10V. By adjusting the resistance of the conversion resistor R57 in the conversion module 42, the ratio of the current signal AO_Rate to the voltage signal Uo1 can be adjusted. For example, when the resistance of the conversion resistor R57 is 250Ω, standard currents of 0-20mA, 4-20mA, 0-40mA, and 4-40mA can be obtained, respectively.

[0071] Finally, the control module 20 controls the switch chip U14 by outputting the control signal Zero_offset3 to connect the voltage signal Uo1 or the current signal AO_Rate to the protection module 45 and the filter module 44 , and outputs the signal to the outside through the output terminal 46 .

[0072] Based on the above scheme, the flowmeter of this utility model can customize the output analog range, reuse the output port, and freely select the output voltage or current mode. It can achieve automatic zero point compensation, high precision and load capacity, low circuit optimization cost, and high safety and reliability.

[0073] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the present invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the present invention. Therefore, the embodiments should be considered in all respects as illustrative and non-restrictive, and the scope of the present invention is defined by the appended claims, not the foregoing description, and all variations within the meaning and range of equivalents of the claims are intended to be encompassed within the present invention. Any reference sign in a claim should not be construed as limiting the claim to which it relates.

[0074] In addition, it should be understood that although this specification is described in terms of implementation methods, not every implementation method contains only one independent technical solution. This narrative method of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

Claims

1. A flow meter, characterized in that: It includes a sensing module, a control module, a DAC module and an output system, wherein the output system includes a conversion module, a switch 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 voltage signal, the conversion module is connected to the DAC module to convert the voltage signal into a current signal, the switch module is connected to the DAC module, the conversion module and the output end, the control module is also used to generate an output control signal, and the switch module is connected to the control module to control the connection and disconnection between the voltage signal, the current signal and the output end based on the output control signal.

2. The flow meter according to claim 1, wherein The output system also includes a zero-point calibration module, and the control module is further used to generate a calibration signal. The zero-point calibration module is connected to the control module to receive the calibration signal. The zero-point calibration module is connected to the DAC module, the conversion module and the switch module to perform zero-point calibration on the voltage signal based on the calibration signal and transmit the calibrated voltage signal to the conversion module and the switch module.

3. The flow meter according to claim 2, wherein: The zero point calibration module includes a switching unit and a first voltage follower, the input end of the first voltage follower is connected to the DAC module to receive a voltage signal, the switching unit is connected to the control module to receive a calibration signal, the switching unit is connected to the input end of the first voltage follower and the ground voltage to control the on and off between the input end of the first voltage follower and the ground voltage based on the calibration signal, and the output end of the first voltage follower is connected to the conversion module and the switching module.

4. The flow meter according to claim 3, wherein: The zero point calibration module further includes a first resistor, a first end of the first resistor is connected to the DAC module to receive a voltage signal, and a second end of the first resistor is connected to an input end of the first voltage follower; and / or The zero point calibration module further includes a second resistor, a first end of the second resistor is connected to the input end of the first voltage follower, and a second end of the second resistor is connected to the switch unit.

5. The flow meter according to claim 1, wherein The conversion module includes a current generating unit and a conversion resistor. The current generating unit is connected to the DAC module and the conversion resistor to generate a current signal on the conversion resistor based on a voltage signal.

6. The flow meter according to claim 5, characterized in that The current generating unit includes an amplifier, a transistor, a first voltage dividing unit and a second voltage dividing unit, wherein the first voltage dividing unit has a first voltage dividing node and the second voltage dividing unit has a second voltage dividing node; A first end of the first voltage dividing unit is connected to the DAC module to receive a voltage signal, and a second end of the first voltage dividing unit is connected to a first end of the conversion resistor; The first end of the second voltage dividing unit is connected to the second end of the conversion resistor, and the second end of the second voltage dividing unit is connected to the ground voltage; The first input terminal of the amplifier is connected to the first voltage dividing node, the second input terminal of the amplifier is connected to the second voltage dividing node, the output terminal of the amplifier is connected to the control terminal of the transistor, the first terminal of the transistor is connected to the second terminal of the conversion resistor, and the second terminal of the transistor is connected to the power supply voltage.

7. The flow meter according to claim 6, characterized in that The first voltage-dividing unit includes a first voltage-dividing resistor and a second voltage-dividing resistor, the first end of the first voltage-dividing resistor is used to form a first end of the first voltage-dividing unit, the second end of the first voltage-dividing resistor is connected to the first end of the second voltage-dividing resistor to form a voltage-dividing node of the first voltage-dividing unit, and the second end of the second voltage-dividing resistor is used to form a second end of the first voltage-dividing unit; and / or The second voltage-dividing unit includes a third voltage-dividing resistor and a fourth voltage-dividing resistor, the first end of the third voltage-dividing resistor is used to form the first end of the second voltage-dividing unit, the second end of the third voltage-dividing resistor is connected to the first end of the fourth voltage-dividing resistor to form a second voltage-dividing node, and the second end of the fourth voltage-dividing resistor is used to form the second end of the second voltage-dividing unit.

8. The flow meter according to claim 5, wherein: The conversion module further includes a second voltage follower, an input end of the second voltage follower is connected to the DAC module to receive a voltage signal, and an output end of the second voltage follower is connected to the current generating unit.

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

10. The flow meter according to claim 1, wherein The output system is provided with one or more.

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