A turbine flowmeter detection probe, sensing element and flowmeter

Abstract

The present application belongs to the field of instruments and meters, and particularly relates to a turbine flowmeter detection probe, a sensitive element and a turbine flowmeter based on a Hall sensor. The detection probe comprises a signal detection part and a signal processing part. The signal detection part is used for detecting the rotation of turbine blades in the turbine flowmeter and generating a corresponding induction signal. The signal processing part is used for converting the induction signal into a standard current signal of 4-20 mA. The signal detection part is composed of a linear Hall element and a micro permanent magnet. The micro permanent magnet is located at the top of the linear Hall element, and the interconnecting direction of the magnetic poles of the micro permanent magnet is perpendicular to the magnetic induction surface of the linear Hall element. The side of the permanent magnet is close to the impeller of the turbine flowmeter. When the impeller rotates, the magnetic flux of the magnetic induction surface of the linear Hall element changes, and then a sinusoidal induction signal is output. The present application solves the problems of poor precision and stability and non-uniform signal output standard of the existing coil type electromagnetic flowmeter.

Description

Technical Field

[0001] This invention belongs to the field of instrumentation, specifically relating to a Hall sensor-based turbine flow meter detection probe, a sensitive element, and a corresponding turbine flow meter. Background Technology

[0002] A turbine flow meter is a type of velocity flow meter, consisting of a turbine and a probe that detects the turbine's rotational speed. When fluid passes through the turbine flow meter, it drives the turbine to rotate at a specific speed. During the flow meter's detection process, there is a specific functional relationship between the turbine's rotational speed and the fluid flow rate. The probe, mounted outside the housing, detects the turbine's rotation and generates an electrical signal related to its rotational speed. By processing the electrical signal output by the probe, the vortex speed can be obtained, and the flow rate can then be calculated.

[0003] Traditional turbine flow meters use a coil as the sensing element in the probe to measure the impeller speed. When the impeller rotates, the impeller blades and the gap between the blades alternately approach the coil. Because the impeller is made of ferromagnetic cast iron, the coil detects the periodic changes in the surrounding induced magnetic field. By analyzing the induced signal, the impeller speed can be calculated, and thus the fluid flow rate can be determined.

[0004] Coil-type electromagnetic flowmeters are currently the most widely used flow detection solution, but they also have some performance drawbacks. For example, conventional magnetic coil amplifiers have poor electromagnetic interference resistance, and magnetic impurities tend to accumulate near the test point during prolonged use, thus degrading detection performance. Furthermore, the signal strength of coil-type electromagnetic flowmeters is directly proportional to the turbine speed, resulting in a signal cutoff and saturation region. This makes coil-type flowmeters prone to signal loss when measuring low flow rates (low speed) or high flow rates (high speed), leading to inaccurate measurement results.

[0005] In addition, most existing products on the market output pulse frequency signals; however, signal receiving equipment in industrial sites generally uses 4-20mA standard current signals, and older turbine flow meter products cannot meet the new standard's requirements for output signals. Summary of the Invention

[0006] To address the issues of poor accuracy and stability, and inconsistent signal output standards in existing coil-type electromagnetic flowmeters, this invention provides a Hall sensor-based turbine flowmeter detection probe, a sensing element, and a corresponding turbine flowmeter.

[0007] This invention is achieved using the following technical solution:

[0008] A detection probe for a turbine flow meter based on a Hall sensor includes a signal detection section and a signal processing section. The signal detection section is used to detect the rotation of the turbine blades in the turbine flow meter and generate a corresponding induction signal. The signal processing section is used to convert the induction signal into a standard current signal of 4-20mA.

[0009] The signal detection section consists of a linear Hall element and a miniature permanent magnet. The miniature permanent magnet is located on top of the linear Hall element, and the line connecting the magnetic poles of the miniature permanent magnet is perpendicular to the magnetic induction surface of the linear Hall element. The output terminal of the linear Hall element serves as the output terminal of the signal detection section, and the output signal Vout satisfies the following equation:

[0010] Vout = K·B

[0011] In the above formula, K represents the sensitivity coefficient of the linear Hall element; B represents the magnetic flux density of the environment in which the linear Hall element is located.

[0012] As a further improvement of the present invention, when the permanent magnet side is close to the impeller of the turbine flow meter in the signal detection section, the magnetic flux of the magnetic induction surface of the linear Hall element changes when the impeller rotates, thereby generating a sinusoidal induced signal.

[0013] As a further improvement of this invention, the signal processing section converts the sinusoidal AC signal acquired by the signal detection section into a standard 4-20mA current signal output. The signal processing circuit includes: a signal amplification circuit, a shaping circuit, a frequency-to-voltage conversion circuit, a voltage-to-current conversion circuit, and a regulated power supply. The signal amplification circuit amplifies the induced signal from the linear Hall element, with an amplification factor A of 100. The shaping circuit converts the amplified induced signal into a standard square wave frequency signal output. The frequency-to-voltage conversion circuit uses an F / V converter to convert the frequency signal output from the shaping circuit into a voltage signal output. The voltage-to-current conversion circuit converts the voltage signal output from the frequency-to-voltage conversion circuit into a standard 4-20mA current signal output; the regulated power supply provides the +5V voltage required for the operation of other circuits in the signal processing section.

[0014] As a further improvement of this invention, the voltage-to-current conversion circuit includes a +24V power supply positive terminal, a 0V power supply negative terminal, and an output terminal OUT. The voltage-to-current conversion circuit includes: potentiometers S1 and Z1, operational amplifiers U3.2, U4.1, and U4.2, resistors R2 and R11-R16, capacitors C8-C11 and C13, protection diodes D1-D3, a Zener diode D4, a MOSFET Q1, a BJT transistor Q2, and ferrite beads L1-L2. The circuit connection relationship of the voltage-to-current conversion circuit is as follows:

[0015] One fixed terminal of S1 is connected to the output of U1, and the other fixed terminal is grounded through R2. The sliding terminal is connected to the non-inverting input of U3.2 through R10. The non-inverting input of U3.2 is also grounded through C7. The inverting input of U3.2 is connected to the output and then connected to a +5V voltage source through R12, Z1, and R11 in series. One end of C8 is connected to the junction of R12 and Z1 and to the non-inverting input of U4.2. The other end of C8 is grounded. The inverting input of U4.2 is connected to the emitter of Q2 and grounded through R13. The output of U4.2 is connected to the base of Q2; the collector of Q2 is connected to the non-inverting input of U4.1 and the lower ends of C10 and R15. The upper end of C10 is connected to VCC through D4; the upper end of C9 is connected to VCC, and the lower end is grounded through R14. The lower end of C9 is also connected to the upper ends of C10, R15, and R16. The lower end of R16 is connected to the inverting input of U4.1 and the source of Q1. The output of U4.1 is connected to the gate of Q1; the drain of Q1 is connected to the signal output terminal OUT through D3 and L2. The positive power supply terminal is connected to GND in series through L1, D1, and C11; the connection point of D1 and C11 is connected to VCC; the negative power supply terminal is connected to GND in series through L3 and D2.

[0016] As a further improvement to this invention, the signal amplification circuit consists of capacitors C3 and C17, resistors R17 to R19, operational amplifier U5, and BJT transistor Q3. The circuit connections are as follows: the base of Q3 is connected to one end of the induction coil T via C17, and the other end of the induction coil T is connected to GND. R17 is connected between the base and collector of Q3. The collector of Q3 is connected to a +5V voltage source via R18. The emitter of Q3 is connected to GND via R19 and C3 connected in parallel. The non-inverting input of U5 is connected to the collector of Q3, and the inverting input of U5 is connected to the output terminal and serves as the output port for amplified signals.

[0017] As a further improvement to this invention, the shaping circuit consists of capacitors C18 and C19, resistors R3 to R9, and operational amplifier U3.1. The circuit connection is as follows:

[0018] Capacitor C18 is a polarized electrolytic capacitor. The negative terminal of C18 is connected to the output port of the signal amplifier circuit, and the positive terminal of C18 is connected to one end of R5 and R9. The other end of R5 is connected to GND through R6 and C19 connected in parallel. The other end of R9 is connected to the non-inverting input of U3.1. R8 is connected between the non-inverting input and output of U3.1. The inverting input of U3.1 is connected to a +5V voltage source through R7. The output of U3.1 is also connected to GND through C12, R4, and R3 in sequence. The connection point of R3 and R4 leads out to the output port F as a standard square wave frequency signal.

[0019] As a further improvement of this invention, the frequency-to-voltage conversion circuit consists of capacitors C1, C2, and C4, resistor R1, and an F / V converter U1. The F / V converter U1 is an XD2917 type frequency-to-voltage converter, including pins 1 to 8. Pin 1 of U1 is connected to the output port F of the shaping circuit; pin 2 is connected to GND through C1; pin 3 is connected to GND through R1 and C2 connected in parallel; pins 4 and 7 are connected and serve as the output port of the converted voltage signal; pins 5 and 6 are connected and connected to a +5V voltage source; pin 8 is connected to GND. Capacitor C4 is connected between pins 5 and 8.

[0020] As a further improvement of the present invention, the regulated power supply consists of a voltage regulator chip U2 and capacitors C5, C6, and C13. The voltage regulator chip adopts an HT7550 integrated circuit, which includes three pins. The circuit connection is as follows: pin 1 of U2 is connected to GND, pin 2 is connected to VCC, and pin 3 is used to generate a +5V output voltage; capacitor C5 is connected between pins 1 and 2; capacitor C6 is connected between pins 1 and 3.

[0021] In addition, capacitor C13 is connected between the housing terminals KE and GND.

[0022] This invention also provides a sensing element for detecting the rotation of turbine blades in a turbine flow meter and generating a corresponding sinusoidal sensing signal. The sensing element comprises a linear Hall element and a miniature permanent magnet; the miniature permanent magnet is located on top of the packaged linear Hall element, and the direction of the line connecting the magnetic poles of the miniature permanent magnet is perpendicular to the magnetic induction surface of the linear Hall element. The output terminal of the linear Hall element serves as the output terminal of the sensing element.

[0023] The present invention also provides a turbine flow meter, which includes a turbine structure and a probe. The probe in the turbine flow meter employs a Hall sensor-based turbine flow meter detection probe as described above.

[0024] The technical solution provided by this invention has the following beneficial effects:

[0025] This invention utilizes a linear Hall element and a permanent magnet to design a novel sensitive element that can detect the rotation of the turbine in a turbine flow meter. This sensitive element has strong anti-electromagnetic interference capability and higher sensitivity. When applied to a turbine flow meter, it can improve the accuracy and stability of the turbine flow meter and enhance its adaptability to high-flow and low-flow detection scenarios.

[0026] Furthermore, the sensing element based on a linear Hall element and a permanent magnet provided in this embodiment only requires a native magnetic field with extremely low magnetic induction intensity to excite the linear Hall element and generate a detection signal. This can reduce the risk of the impeller adsorbing ferromagnetic impurities during operation and improve the defect of decreased detection accuracy caused by impeller contamination with ferromagnetic impurities, which is prone to occur in traditional coil-type turbine flow meters.

[0027] This invention also designs a novel signal processing circuit that can directly convert the sinusoidal signal acquired by the linear Hall element in a turbine flowmeter into a standard 4-20mA current signal. This circuit can sequentially amplify, shape, convert the frequency to voltage, and convert the current output of the induced signal. Compared to traditional frequency output signal processing circuits, this invention requires the addition of a frequency-to-voltage conversion section based on the XD2917 integrated circuit, and a current output section composed of several operational amplifiers, MOSFETs, BJTs, resistors, capacitors, and other basic components. Therefore, this solution has both performance and cost advantages.

[0028] The signal processing circuit provided by this invention incorporates multiple noise filtering processes, which improves the stability of the acquired signal and enhances the accuracy of the output current signal. Furthermore, the circuit solution provided by this invention supports adjustments to the zero point and full-scale of the detection signal for different application scenarios, resulting in more powerful performance. Installation and debugging are also more convenient. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the structure of a novel sensing element for a turbine flow meter provided in Embodiment 1 of the present invention.

[0030] Figure 2 This is a schematic diagram of the principle of a linear Hall element.

[0031] Figure 3 The change in magnetic flux of the sensing element provided in Embodiment 1 of the present invention during impeller rotation.

[0032] Figure 4 This is a complete circuit diagram of the turbine flow meter detection probe based on a Hall sensor provided in Embodiment 2 of the present invention.

[0033] Figure 5 This is a circuit diagram of the amplifier circuit in the signal processing circuit of Embodiment 2 of the present invention.

[0034] Figure 6 This is a circuit diagram of the shaping circuit in the signal processing circuit of Embodiment 2 of the present invention.

[0035] Figure 7 This is a circuit diagram of the regulated power supply in the signal processing circuit of Embodiment 2 of the present invention.

[0036] Figure 8 The circuit diagram of the frequency-to-voltage conversion circuit in the signal processing circuit of Embodiment 2 of the present invention is shown.

[0037] Figure 9 This is a circuit diagram of the voltage-to-current conversion circuit in the signal processing circuit of Embodiment 2 of the present invention. Detailed Implementation

[0038] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0039] Example 1

[0040] This embodiment provides a novel sensing element for use in turbine flow meters. This sensing element can replace the coil in a traditional turbine flow meter to detect the impeller speed and generate a sinusoidal waveform signal characterizing the turbine flow meter's rotation process.

[0041] like Figure 1 As shown, the sensing element provided in this embodiment consists of a linear Hall element and a miniature permanent magnet. The miniature permanent magnet is located on top of the packaged linear Hall element, and the direction of the line connecting the magnetic poles of the miniature permanent magnet is perpendicular to the magnetic induction surface of the linear Hall element.

[0042] Traditional linear Hall elements are devices composed of Hall sensors, linear amplifiers, and emitter followers, such as... Figure 2 As shown, the output voltage of a linear Hall element is proportional to the strength of the magnetic field passing through it, and it can reflect the characteristics and strength of the surrounding magnetic field by the rise or fall of the output voltage. Specifically, the output signal Vout satisfies the following equation:

[0043] Vout = K·B

[0044] In the above formula, K represents the sensitivity coefficient of the linear Hall element; B represents the magnetic flux density of the environment in which the linear Hall element is located.

[0045] Based on the above characteristics, linear Hall elements are currently widely used in displacement detection, pressure sensing, magnetic field detection, current and voltage measurement, speed regulation, and throttle pedal signal detection. However, it is important to emphasize that when the magnetic field strength around a linear Hall element remains constant, its output signal will remain constant. Therefore, linear Hall elements are generally unsuitable for detecting impeller rotation in turbine flow meters, because the impeller rotation itself does not affect the change in the surrounding magnetic field strength, and the linear Hall element cannot respond to the impeller rotation.

[0046] The sensing element provided in this embodiment adds a permanent magnet arranged at a specific angle to the linear Hall element. Utilizing the magnetic field generated by the permanent magnet and the basic electrical characteristics of the linear Hall element, it detects the rotation of a ferromagnetic impeller and generates sinusoidal waveforms of different frequencies based on the impeller's rotational speed. During signal detection, the permanent magnet side of the sensing element is brought close to the impeller being measured, and the direction of the magnetic pole connection of the permanent magnet is made as parallel as possible to the rotation plane of the turbine flowmeter's impeller. When the impeller rotates, it causes a change in the magnetic flux of the linear Hall element, thereby outputting a sinusoidal induced signal.

[0047] In detail, the working principle of this sensitive element is as follows:

[0048] In this embodiment, the permanent magnet generates a native magnetic field around the linear Hall element in the sensing element. When the impeller rotates, the outer edge of the impeller blades and the inter-blade gap alternately approach the sensing element. For example... Figure 3 As shown, when the blades of the impeller approach the sensing element, the impeller, made of ferromagnetic material, attracts some magnetic induction lines, causing the magnetic flux on the magnetic induction surface of the linear Hall element to decrease; at this time, the output signal of the linear Hall element decreases.

[0049] When the impeller blade gap approaches the sensing element, the magnetic field lines attracted by the impeller decrease, which in turn increases the magnetic flux on the magnetic induction surface of the linear Hall element; at this time, the output signal of the linear Hall element increases.

[0050] Ultimately, when the impeller approaches the sensing element and rotates at a certain speed, it causes the magnetic flux of the magnetic induction surface of the linear Hall element to undergo periodic dynamic changes, which in turn causes the sinusoidal waveform of the voltage output by the linear Hall element to change.

[0051] Therefore, it can be seen that the novel sensing element composed of "linear Hall element + permanent magnet" provided in this embodiment can replace the traditional induction coil when applied in a turbine flow meter, so as to realize real-time non-contact detection of the impeller's rotation status.

[0052] In particular, due to the strong anti-electromagnetic interference capability and higher sensitivity of the linear Hall element, its application in turbine flow meters can improve the accuracy and stability of the flow meters and enhance their adaptability in both high-flow and low-flow detection scenarios. Furthermore, in traditional coil-type turbine flow meters, to ensure the strength of the detection signal, the magnetic field strength generated by the coil needs to reach a preset threshold. This may cause the impeller of the turbine flow meter to attract ferromagnetic impurities during long-term operation, leading to a decrease in detection accuracy. However, the sensing element based on a linear Hall element and a permanent magnet provided in this embodiment only requires a native magnetic field with extremely low magnetic induction intensity to excite the linear Hall element to generate a detection signal. Therefore, it can reduce the risk of the impeller attracting ferromagnetic impurities during operation and improve the defect of decreased turbine flow meter detection accuracy due to impurity contamination of the impeller.

[0053] Example 2

[0054] This embodiment provides a turbine flow meter detection probe based on a Hall sensor, which includes a signal detection section and a signal processing section. The signal detection section in this embodiment uses the novel sensing element from Embodiment 1. The signal detection section is used to detect the rotation of the turbine blades in the turbine flow meter and generate a corresponding induction signal. Specifically, the signal detection section is composed of a linear Hall element and a miniature permanent magnet; the output terminal of the Hall sensor serves as the output terminal of the signal detection section.

[0055] like Figure 4 As shown, in this embodiment, the linear Hall element U6 is selected as HX6659IUA. Pin 1 of U6 is the VCC interface, pin 2 is the GND interface, and pin 3 is the OUT interface. In this embodiment, a 1μF capacitor C15 and a 0.01μF capacitor C16 are connected in series between pins 1 and 2. Pin 2 is connected between C15 and C16, and the detected sensing signal is output at the OUT terminal.

[0056] Furthermore, the Hall sensor-based turbine flow meter detection probe provided in this embodiment further improves the signal processing section, which can convert the sinusoidal induced signal detected by the sensitive element into a standard 4-20mA current signal. The signal processing section is a signal processing circuit, such as... Figure 4As shown, the signal processing circuit provided in this embodiment includes: a signal amplification circuit, a shaping circuit, a frequency-to-voltage conversion circuit, a voltage-to-current conversion circuit, and a regulated power supply. The signal amplification circuit amplifies the induced signal from the induction coil. The shaping circuit converts the amplified induced signal into a standard square wave frequency signal for output. The frequency-to-voltage conversion circuit uses an F / V converter to convert the frequency signal output from the shaping circuit into a voltage signal for output. The voltage-to-current conversion circuit converts the voltage signal output from the frequency-to-voltage conversion circuit into a standard 4-20mA current signal for output. The regulated power supply provides the +5V regulated power required for the operation of the aforementioned four circuit components.

[0057] The signal processing circuit provided in this embodiment operates as follows: First, the weak sinusoidal signal F1 sensed by the induction coil is amplified by the signal amplification circuit. Then, the sinusoidal signal F1 is converted into a square wave signal F of the corresponding frequency by the shaping circuit. Traditional coil induction turbine flow meters output such a square wave frequency signal. This embodiment further converts the square wave frequency signal F into a corresponding voltage signal V1 by a frequency-to-voltage conversion circuit based on an F / V converter. After achieving the frequency-to-voltage conversion, this embodiment finally converts the previous stage output voltage signal V1 into a standard current signal Iout in the range of 4-20mA by a newly designed voltage-to-current conversion circuit.

[0058] Specifically, such as Figure 5 As shown, the signal amplification circuit consists of capacitors C3 and C17, resistors R17 to R19, operational amplifier U5, and BJT transistor Q3. The circuit connections are as follows: the base of Q3 is connected to one end of the induction coil T via C17, and the other end of the induction coil T is connected to GND. R17 is connected between the base and collector of Q3. The collector of Q3 is connected to a +5V voltage source via R18. The emitter of Q3 is connected to GND via R19 and C3 connected in parallel. The non-inverting input of U5 is connected to the collector of Q3, and the inverting input of U5 is connected to the output terminal and serves as the output port for amplified signals. Specifically, in this embodiment, BJT transistor Q3 is a 9014 type transistor, and operational amplifier U5 is an HGV8551.

[0059] In the signal amplification circuit, resistors R17-R19, capacitor C3, and BJT transistor Q3 constitute the signal amplification section. C3 and C17 form an AC path, R17 provides bias current, and the amplified signal is output from the collector (C) of Q3. Operational amplifier U5 forms a follower circuit, its function being to increase the signal driving capability to match the input requirements of the next stage. The amplification factor A of the signal amplification circuit provided in this embodiment is determined by the resistance values ​​of resistors R18 and R19, calculated using the following formula:

[0060] A = R 18 / R 19

[0061] In the above formula, R 18 and R 19 These are the resistance values ​​of resistors R18 and R19, respectively. In the actual product solution of this embodiment, the resistance values ​​of resistors R18 and R19 are 20KΩ and 200Ω, respectively, therefore the amplification factor A of the signal amplification circuit is 100 times. It should be noted that the amplification factor of the signal amplification circuit in this embodiment needs to be optimized based on the intensity of the induced signal corresponding to the typical speed of the turbine sensor under actual operating conditions. For example, in this embodiment, the amplified signal A is set to 100 times, which is the optimal matching parameter selected by the technicians after multiple experiments.

[0062] like Figure 6 As shown, the shaping circuit provided in this embodiment consists of capacitors C18 and C19, resistors R3 to R9, and operational amplifier U3.1. The circuit connection is as follows:

[0063] Capacitor C18 is a polarized electrolytic capacitor. The negative terminal of C18 is connected to the output port of the signal amplifier circuit, and the positive terminal of C18 is connected to one end of R5 and R9. The other end of R5 is connected to GND through R6 and C19 connected in parallel. The other end of R9 is connected to the non-inverting input of U3.1. R8 is connected between the non-inverting input and output of U3.1. The inverting input of U3.1 is connected to a +5V voltage source through R7. The output of U3.1 is also connected to GND through C12, R4, and R3 in sequence. The connection point of R3 and R4 leads out to the output port F as a standard square wave frequency signal.

[0064] The operational amplifier U3.1 in the shaping circuit provided in this embodiment adopts HGV8552. The overall circuit actually constitutes a positive feedback amplifier. Therefore, this circuit can convert the sinusoidal waveform induced signal F1 into the corresponding square wave frequency signal F and output it.

[0065] In this embodiment, as Figure 7 As shown, the regulated power supply consists of a voltage regulator chip U2, capacitors C5, C6, and C13. The voltage regulator chip uses an HT7550 integrated circuit, which has three pins. The circuit connections are as follows: pin 1 of U2 is connected to GND, pin 2 is connected to VCC, and pin 3 is used to generate a +5V output voltage; capacitor C5 is connected between pins 1 and 2; capacitor C6 is connected between pins 1 and 3.

[0066] In this embodiment, the standard +5V voltage source generated by the regulated power supply not only provides the operating voltage required for the operation of other circuit parts, but also serves as the reference voltage for the voltage signal output by the frequency-to-voltage conversion circuit.

[0067] Specifically, capacitor C13 is connected between the housing terminals KE and GND, which can suppress the dynamic common-mode voltage between high-frequency interference sources and the circuit, and allow high-frequency interference generated inside the circuit to flow into the housing and into the ground through C13, thus avoiding antenna radiation caused by high-frequency interference.

[0068] Among the five functional circuits of the signal processing circuit provided in this embodiment, the frequency-to-voltage conversion circuit and the voltage-to-current conversion circuit are the core circuits that convert the frequency signal F into the required 4-20mA standard current signal. Functionally, they can replace the signal processing tasks that require a microcontroller and its supporting software in the prior art, and can greatly reduce the hardware cost of the microcontroller solution.

[0069] Specifically, such as Figure 8 As shown, the frequency-to-voltage conversion circuit provided in this embodiment consists of capacitors C1, C2, and C4, resistor R1, and an F / V converter U1. The F / V converter U1 can directly use the highly integrated XD2917 frequency-to-voltage converter, which includes pins 1 to 8. Pin 1 of U1 is the TACH+ interface, which in this embodiment is connected to the output port F of the shaping circuit to receive the frequency signal from the previous stage. Pin 2 is the CP1 interface, which in this embodiment is connected to GND via C1. Pin 3 is the CP2 / IN+ interface, which in this embodiment is connected to R1 and C2 in parallel, with the other ends of R1 and C2 connected to GND. Pin 4 is the EMIT interface, and pin 7 is the IN- interface; in this embodiment, these two are connected together and used as the output port of the converted voltage signal. Pin 5 is the COL interface, and pin 6 is the V+ interface; in this embodiment, these two are connected together and connected to a +5V voltage source. Pin 8 is the TACH- / GND interface, which in this embodiment is connected to GND. Finally, in this embodiment, a capacitor C4 is connected between pins 5 and 8.

[0070] The following are provided in this embodiment: Figure 8 The converted voltage shown uses the XD2917 as the main component for frequency-to-voltage conversion, and employs the recommended wiring method for the XD2917. Finally, the converted voltage signal V1 is output through pins 4 and 7 of the XD2917. Specifically, the voltage signal V1 output by the frequency-to-voltage conversion circuit satisfies the following equation:

[0071] V1 = (+5V)·R1·C1·F

[0072] In the above formula, R1 represents the resistance value of resistor R1 in the frequency-to-voltage conversion circuit; C1 represents the capacitance value of capacitor C1 in the frequency-to-voltage conversion circuit; and F represents the frequency of the input standard square wave signal.

[0073] Therefore, the waveform of the voltage signal is determined by the frequency signal F, but the amplitude of the voltage signal is affected by the regulated power supply output reference voltage (+5V) and the resistance value of R1 and the capacitance value of C1. In this embodiment, the resistance value of R1 and the capacitance value of C1 were tested and optimized according to the actual application scenario. The optimal parameters selected were R1 = 36KΩ and C1 = 1μF.

[0074] The circuit design of the voltage-to-current conversion circuit used in this embodiment is as follows: Figure 9 As shown, the voltage-to-current converter circuit includes a +24V positive power supply terminal, a 0V negative power supply terminal, and an output terminal OUT. The voltage-to-current converter circuit includes: potentiometers S1 and Z1, operational amplifiers U3.2, U4.1, and U4.2, resistors R2 and R11-R16, capacitors C8-C11, protection diodes D1-D3, a Zener diode D4, a MOSFET Q1, a BJT Q2, and ferrite beads L1-L2. The circuit connection relationship of the voltage-to-current converter circuit is as follows:

[0075] One fixed terminal of S1 is connected to the output of U1, and the other fixed terminal is grounded through R2. The sliding terminal is connected to the non-inverting input of U3.2 through R10. The non-inverting input of U3.2 is also grounded through C7. The inverting input of U3.2 is connected to the output and then connected to a +5V voltage source through R12, Z1, and R11 in series. One end of C8 is connected to the junction of R12 and Z1 and to the non-inverting input of U4.2. The other end of C8 is grounded. The inverting input of U4.2 is connected to the emitter of Q2 and grounded through R13. The output of U4.2 is connected to the base of Q2; the collector of Q2 is connected to the non-inverting input of U4.1 and the lower ends of C10 and R15. The upper end of C10 is connected to VCC through D4; the upper end of C9 is connected to VCC, and the lower end is grounded through R14. The lower end of C9 is also connected to the upper ends of C10, R15, and R16. The lower end of R16 is connected to the inverting input of U4.1 and the source of Q1. The output of U4.1 is connected to the gate of Q1; the drain of Q1 is connected to the signal output terminal OUT through D3 and L2. The positive power supply terminal is connected to GND in series through L1, D1, and C11; the connection point of D1 and C11 is connected to VCC; the negative power supply terminal is connected to GND in series through L3 and D2.

[0076] Combination Figure 9 The working principle of the voltage-to-current conversion circuit provided in this embodiment is as follows:

[0077] The circuit signal V1 output from the frequency-to-voltage conversion circuit is input to the voltage-to-current conversion circuit. First, it is divided by potentiometers S1 and R2 connected in series, yielding the desired signal voltage value V2. During this process, adjusting the resistance of S1 changes the signal voltage to meet the requirements of full-scale output adjustment. R10 and C7, through which the voltage signal flows, form an L-type filter, thus providing stability; while operational amplifier U3.2 acts as a follower, increasing the driving capability. Then, R11, Z1, and R12 form a zero-point reference, outputting the desired zero-point voltage value. Adjusting Z1 changes the zero-point output value.

[0078] Therefore, it can be seen that adjusting S1 and Z1 in the voltage-to-current conversion circuit can achieve the purpose of calibrating the instrument. S1 divides the original voltage signal V1; therefore, lowering the moving point of S1 will decrease the full-scale output, and vice versa. Z1 adjusts the zero-point voltage value; increasing the resistance of Z1 will decrease the zero-point output, and vice versa.

[0079] The voltage signal V2 continues to propagate. R15, R13, U4.2, and Q2 form a current-series feedback circuit, the purpose of which is to transfer the voltage signal V2 to V3 for sampling by subsequent circuits. In the current-series feedback circuit, C8 and C10 serve to stabilize the signal.

[0080] The voltage signal V3 is then converted from a voltage signal to a current signal via a voltage-to-current conversion circuit (V / A converter) formed by R16, U4.1, and Q1. Specifically, in the V / A conversion section, the output current Iout satisfies the following equation:

[0081] Iout = V 16 / R 16

[0082] Where V16 represents the voltage across resistor R16, R 16 This is the resistance value of resistor R16.

[0083] In addition, for Figure 9 After analyzing the circuit schematic, it can be deduced that:

[0084] V 16 =V 15 =V 13 =V2

[0085] Among them, V 15 V is the voltage across R15. 13 V1 is the voltage across R13, and V2 is the voltage divider of the original voltage signal V1, which is affected by S1 and Z1.

[0086] Therefore, combining the above two equations, we can also obtain the output current Iout, which satisfies the following equation:

[0087] Iout = V2 / R16.

[0088] In this embodiment, R16 = 51KΩ, so the OUT port can ultimately output a standard current value within the range of 4 to 20mA based on the input voltage signal V1.

[0089] Specifically, in the V / A conversion section at the back end of the voltage-to-current conversion circuit in this embodiment, D4, C9, and R14 provide a suitable operating range for the circuit. Ferrite beads L1-L3 and C11 enhance the circuit's anti-interference capabilities. Diodes D1-D3 protect the circuit, preventing damage caused by wiring errors.

[0090] In detail, in the actual product provided in this embodiment, potentiometer S1 is a 502 precision adjustable potentiometer; potentiometer Z1 is a 204 precision adjustable potentiometer. Operational amplifier U3.2 is an HGV8552; U4.1 and U4.2 are LM2904; protection diodes D1 to D3 are 1N4148WS; Zener diode D4 is a BZT52C2V0S; MOSFET Q1 is a CEA6861; and BJT Q2 is a 9014 type.

[0091] To overcome the specificity of component performance and the influence of manufacturing processes on the performance of the final product, and to ensure the uniformity of the final product's performance, the signal processing circuit of the coil induction turbine flowmeter provided in this embodiment needs to be tested and debugged before practical application. Specifically, the circuit testing process is as follows:

[0092] (1) After the permanent magnet and linear Hall element are assembled, they are soldered to the printed circuit board through connecting wires.

[0093] (2) Install the turbine on a standard turbine flow calibration stand, start the test stand to purge air from the pipe and ensure the pipe is full so that the measurement results are more accurate.

[0094] (3) Install the sensitive element composed of permanent magnet and linear Hall element on the turbine in the calibration stand and connect it to the secondary instrument. Connect the +24V port of the circuit main board to the corresponding positive power supply terminal, the 0V port to the negative power supply terminal, and the out port to the current output terminal.

[0095] (4) In the initial state, the valve of the standard turbine flow calibration bench is closed. Observe whether the current display value of the secondary instrument is around 4 mA. If the current value detected in the valve closed state deviates from the standard value of 4 mA and exceeds the upper limit of error, the zero position can be adjusted by adjusting the resistance of potentiometer Z1.

[0096] (5) Open the valve of the standard turbine flow calibration bench and adjust the flow rate to the maximum turbine flow rate. Observe whether the current display value of the secondary instrument is around 20 mA. If the current value detected at the maximum valve opening is more than 200 mA than the standard value, the deviation exceeds the upper limit of the error. The full-scale adjustment can be achieved by adjusting the resistance of potentiometer S1.

[0097] Example 3

[0098] This embodiment provides a turbine flow meter, which includes a turbine structure and a probe. The probe adopts a Hall sensor-based turbine flow meter detection probe as shown in Embodiment 2. This embodiment provides a novel turbine flow meter that directly integrates the new sensing element in Embodiment 1 and the new signal processing circuit in Embodiment 2. This turbine flow meter can overcome the shortcomings of coil-type turbine flow meters, such as insufficient electromagnetic interference resistance and decreased accuracy in low and high flow measurement scenarios. Furthermore, it overcomes the problem that traditional turbine flow meters can only output frequency signals, thus being unsuitable for signal output standards under current operating conditions.

[0099] The turbine flow meter provided in this embodiment utilizes a low-cost linear Hall element and permanent magnet to design a high-performance non-contact measuring element for impeller speed. Furthermore, it employs an inexpensive XD2917 frequency-to-voltage converter and other basic electrical components to output the induced signal as a standard 4-20mA current signal. This solution improves the performance of the turbine flow meter and reduces production costs. In summary, the novel turbine flow meter provided in this embodiment is of high quality and low price, with a very broad market prospect.

[0100] The above description is only a preferred embodiment of the present invention and is 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 within the protection scope of the present invention.

Claims

1. A turbine flow meter detection probe based on a Hall sensor, comprising a signal detection section and a signal processing section, characterized in that, The signal detection section is used to detect the rotation of the turbine blades in the turbine flow meter and generate a corresponding induced signal; the signal processing section is used to convert the induced signal into a standard 4-20mA current signal; the circuit of the signal processing section includes: a signal amplification circuit, a shaping circuit, a frequency-to-voltage conversion circuit, a voltage-to-current conversion circuit, and a regulated power supply; the voltage-to-current conversion circuit includes a +24V positive terminal, a 0V negative terminal, and an output terminal OUT; the voltage-to-current conversion circuit includes: potentiometers S1 and Z1. Operational amplifiers U3.2, U4.1, and U4.2; resistors R2, R11~R16; capacitors C8~C11, C13; protection diodes D1~D3; Zener diode D4; MOSFET Q1; BJT Q2; and ferrite beads L1~L2 are connected as follows: one fixed terminal of S1 is connected to the output of U1, the other fixed terminal is grounded through R2, and the sliding terminal is connected to the non-inverting input of U3.2 through R10; the non-inverting input of U3.2 is also grounded through C7, and the inverting terminal of U3.2... The inverting input terminal is connected to the output terminal, and then connected to a +5V voltage source through R12, Z1, and R11 in series. One end of C8 is connected to the junction of R12 and Z1 and to the non-inverting input terminal of U4.2, while the other end of C8 is grounded. The inverting input terminal of U4.2 is connected to the emitter of Q2 and grounded through R13. The output terminal of U4.2 is connected to the base of Q2. The collector of Q2 is connected to the non-inverting input terminal of U4.1 and the lower ends of C10 and R15. The upper end of C10 is connected to VCC through D4. The upper end of C9 is connected to VCC, and the lower end is grounded through R14. The lower end of C9 is also connected to the upper ends of C10, R15, and R16. The lower end of R16 is connected to the inverting input of U4.1 and the source of Q1. The output of U4.1 is connected to the gate of Q1. The drain of Q1 is connected to the signal output terminal OUT through D3 and L2. The positive terminal of the power supply is connected to GND in sequence through L1, D1, and C11 connected in series. The connection point of D1 and C11 is connected to VCC. The negative terminal of the power supply is connected to GND in sequence through L3 and D2. The signal detection section consists of a linear Hall element and a miniature permanent magnet; the miniature permanent magnet is located on top of the linear Hall element, and the direction of the line connecting the magnetic poles of the miniature permanent magnet is perpendicular to the magnetic induction surface of the linear Hall element; the output terminal of the linear Hall element serves as the output terminal of the signal detection section, and the output signal Vout satisfies the following equation: Vout=K·B In the above formula, K represents the sensitivity coefficient of the linear Hall element; B represents the magnetic flux density of the environment in which the linear Hall element is located.

2. The turbine flow meter detection probe based on a Hall sensor as described in claim 1, characterized in that: When the permanent magnet side of the signal detection section is close to the impeller of the turbine flow meter, the rotation of the impeller causes a change in the magnetic flux of the magnetic induction surface of the linear Hall element, thereby generating a sinusoidal induced signal.

3. The turbine flow meter detection probe based on a Hall sensor as described in claim 1, characterized in that: The signal processing section converts the sinusoidal AC signal acquired by the signal detection section into a standard 4-20mA current signal output; the signal amplification circuit amplifies the induced signal of the linear Hall element; the shaping circuit converts the amplified induced signal into a standard square wave frequency signal output; the frequency-to-voltage conversion circuit uses an F / V converter to convert the frequency signal output by the shaping circuit into a voltage signal output; the voltage-to-current conversion circuit converts the voltage signal output by the frequency-to-voltage conversion circuit into a standard 4-20mA current signal output; and the regulated power supply provides the +5V voltage source required for the operation of other circuits in the signal processing section.

4. The turbine flow meter detection probe based on a Hall sensor as described in claim 1, characterized in that: The signal amplification circuit consists of capacitors C3 and C17, resistors R17~R19, operational amplifier U5, and BJT transistor Q3; the circuit connection is as follows: The base of Q3 is connected to one end of the induction coil T via C17, and the other end of the induction coil T is connected to GND; R17 is connected between the base and collector of Q3; the collector of Q3 is connected to a +5V voltage source via R18; the emitter of Q3 is connected to GND via R19 and C3 connected in parallel; the non-inverting input of U5 is connected to the collector of Q3, and the inverting input of U5 is connected to the output and serves as the output port for amplified signals.

5. The turbine flow meter detection probe based on a Hall sensor as described in claim 1, characterized in that: The shaping circuit consists of capacitors C18 and C19, resistors R3 to R9, and operational amplifier U3.1; the circuit connection is as follows: Capacitor C18 is a polarized electrolytic capacitor. The negative terminal of C18 is connected to the output port of the signal amplification circuit, and the positive terminal of C18 is connected to one end of R5 and R9. The other end of R5 is connected to GND through R6 and C19 connected in parallel. The other end of R9 is connected to the non-inverting input of U3.

1. R8 is connected between the non-inverting input and output of U3.

1. The inverting input of U3.1 is connected to a +5V voltage source through R7. The output of U3.1 is also connected to GND through C12, R4 and R3 in sequence. The connection point of R3 and R4 leads out to the output port F as a standard square wave frequency signal.

6. The turbine flow meter detection probe based on a Hall sensor as described in claim 1, characterized in that: The frequency-to-voltage conversion circuit consists of capacitors C1, C2, and C4, resistor R1, and an F / V converter U1. The F / V converter U1 is an XD2917 type frequency-to-voltage converter, including pins 1 to 8. Pin 1 of U1 is connected to the output port F of the shaping circuit; pin 2 is connected to GND through C1; pin 3 is connected to GND through R1 and C2 connected in parallel; pins 4 and 7 are connected and serve as the output port of the converted voltage signal; pins 5 and 6 are connected and connected to a +5V voltage source; pin 8 is connected to GND, and capacitor C4 is connected between pins 5 and 8.

7. The turbine flow meter detection probe based on a Hall sensor as described in claim 1, characterized in that: The regulated power supply consists of a voltage regulator chip U2, capacitors C5, C6, and C13. The voltage regulator chip uses an HT7550 integrated circuit, which has three pins. The circuit connection is as follows: pin 1 of U2 is connected to GND, pin 2 is connected to VCC, and pin 3 is used to generate a +5V output voltage. Capacitor C5 is connected between pins 1 and 2, and capacitor C6 is connected between pins 1 and 3. The housing end KE is connected to GND through capacitor C13.

8. A turbine flow meter, comprising a turbine structure and a probe, characterized in that: The probe is a Hall sensor-based turbine flow meter detection probe as described in any one of claims 1-7.

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