Flow correction method and K coefficient adjustment high-precision flowmeter

Abstract

The invention relates to the technical field of flow measurement, in particular to a flow correction method and a K coefficient adjustment high-precision flowmeter. According to the method, different conversion coefficient K values are input in different flow sections, the waveform of the collected signal is adjusted, amplified and output according to the K values, the measurable range of the turbine flowmeter is increased, the measurement precision of the turbine flowmeter in a nonlinear section is greatly improved, and the measurement accuracy of the turbine flowmeter in the nonlinear section is improved. The problem that in the prior art, the flow measurement error of a turbine flowmeter in a nonlinear section is large is solved.

Description

Technical Field

[0001] This invention relates to the field of flow measurement technology, specifically to a flow correction method and a high-precision flow meter with K-coefficient adjustment. Background Technology

[0002] A turbine flow meter is a type of velocity flow meter. A turbine is placed in the center of the pipe, supported at both ends by bearings. When fluid flows through the pipe, it impacts the turbine blades, generating a driving torque that causes the turbine to rotate, overcoming frictional torque and fluid resistance torque. Within a certain flow range, for a given medium viscosity, the turbine rotation angle is directly proportional to the flow velocity. Therefore, the fluid velocity can be obtained from the turbine's rotation angle, and thus the fluid flow rate through the pipe can be calculated. Theoretically, there are... Q = f / K or Q =( f ×3600) / K The relationship is given by K, where K is the instrument coefficient. However, due to factors such as bearing friction and fluid viscous resistance, the instrument coefficient K of the turbine flow meter is not constant throughout the measurement range.

[0003] The measurement range of a turbine flow sensor is divided into two segments: a linear segment (high flow rate) and a non-linear segment (low flow rate). Typically, the linear segment... K The value is relatively stable, but in the nonlinear segment K The values ​​vary considerably. The linear segment is approximately two-thirds of its operating range, and its characteristics are related to the sensor's structural dimensions and the fluid viscosity. Within the measurement range of a turbine-type flow sensor, the low-flow-rate segment is generally in the nonlinear segment. Because its characteristics are significantly affected by bearing friction and fluid viscous resistance, the measurement error is relatively large at low flow rates.

[0004] Existing technologies, such as patent documents with publication numbers CN114894261A and CN115493660A, propose a method for segmented calibration of the K coefficient, that is, using different values ​​for different flow rates in different segments. K Values ​​are set to improve the accuracy of nonlinear segments. However, these methods typically set the number of flow segments corresponding to the number of values. K The coefficients were not further addressed from the perspectives of system optimization and engineering simplicity. Furthermore, the fixed output frequency range of traditional flow meters limits the further expansion of their flow measurement range and requires frequent calibration to maintain accuracy.

[0005] Therefore, there is an urgent need in this field for a new type of flow meter solution that can achieve high-precision measurement, broaden the measurement range, and simplify the calibration and maintenance process. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this invention provides a flow correction method and K High-precision flow meters with coefficient adjustment: This method involves inputting different conversion coefficients for different flow ranges. K Value, based on K The value adjusts, amplifies, and outputs the waveform of the acquired signal, increasing the measurable range of the turbine flow meter and significantly improving the measurement accuracy of the turbine flow meter in the nonlinear range, thus solving the problem of large flow measurement error in the nonlinear range of existing turbine flow meters.

[0007] The present invention is achieved through the following technical solution.

[0008] First, this invention discloses a flow correction method, comprising the following steps: Step S1: Acquire the magnetic flux periodic change signal characterizing the flow velocity of the target fluid; Step S2: Based on the conversion coefficient corresponding to the flow segment to which the magnetic flux periodic change signal belongs. K The frequency of the periodic change signal of the magnetic flux is adjusted and the signal is amplified to obtain a pulse signal; Step S3: Obtain the instantaneous flow rate and cumulative flow rate of the target fluid based on the pulse signal.

[0009] To better realize the present invention, step S2 further includes: Step S21: Divide the flow segment according to the preset flow calibration point; Step S22: Obtain the calibration point conversion coefficient corresponding to each flow calibration point, and calculate the average measurement frequency corresponding to each flow calibration point based on the calibration point conversion coefficient. Step S23: Based on the conversion coefficient of the calibration point and the average measurement frequency, obtain the conversion coefficient corresponding to each flow segment. K ; Step S24: Based on the current flow rate and the conversion coefficients corresponding to each flow segment. K The frequency of the periodic magnetic flux change signal is corrected for errors and the signal is amplified to obtain a pulse signal.

[0010] To better implement this invention, the flow rate calibration points are further configured as five, namely... Qmin 0.25 Qmax 0.4 Qmax 0.7 Qmax , Qmax ,in, Qmin This refers to the lower limit of the flow rate range for the turbine flow meter. Qmax This represents the upper limit of the flow range for the turbine flow meter.

[0011] To better realize the present invention, the relationship between the calibration point conversion coefficient and the average measurement frequency satisfies: Ki= ( fi / Qi )×3600; in, Ki For the first i The conversion factor for each flow rate calibration point is expressed as calibration points per L. fi For the first i The average measurement frequency at each flow calibration point is expressed in Hz. Qi For the first i The flow rate at each flow calibration point is expressed in L / h.

[0012] To better realize the present invention, the conversion coefficient is further... K The relationship between the conversion coefficient and the verification point satisfies: ; in, K1 to Kn This is the conversion coefficient of the calibration point corresponding to each calibration point in this flow range.

[0013] To better realize the present invention, further, in determining the conversion coefficients... K Previously, the conversion coefficients of each flow rate calibration point were tested, and the average value of the test results for each flow rate calibration point was obtained as the conversion coefficient. The relationship between the flow rate calibration point test results and the conversion coefficient satisfies the following: and ,in, Nij For the i-th flow calibration point j Number of pulses in the second test Vij For the first i The first flow calibration point j The actual flow volume of this test is expressed in liters (L). Kij For the first i The first flow calibration point j The test results are expressed in units of samples per L. Ki For the first i The average value of the test results at each flow calibration point, expressed in units of points / L. n To test the number of times.

[0014] To better realize this invention, the calculation formula for the error at each flow rate calibration point is further as follows: ; in, K This is the conversion factor, expressed in units per L. fi For the first i The average measurement frequency at each flow calibration point is expressed in Hz.Qi For the first i The flow rate at each flow calibration point is expressed in L / h.

[0015] Secondly, this invention also discloses a K-coefficient adjustable high-precision flow meter for implementing the above-mentioned flow correction method, wherein the K-coefficient adjustable high-precision flow meter includes: A sensing component, wherein the sensing component is used to acquire a magnetic flux periodic change signal characterizing the flow velocity of a target fluid; The signal conversion module is used to convert the signal based on the conversion coefficients corresponding to different flow segments. K The frequency of the periodic change signal of the magnetic flux is adjusted and the signal is amplified to obtain a pulse signal; The signal processing module is used to obtain the instantaneous flow rate and cumulative flow rate of the target fluid based on the pulse signal.

[0016] Compared with the prior art, the present invention has the following advantages and beneficial effects.

[0017] 1. The flow correction method disclosed in this invention improves detection accuracy and broadens the frequency output range.

[0018] 2. The flow correction method disclosed in this invention divides the flow into segments and matches an appropriate conversion coefficient according to the flow segment to which the flow belongs during detection. K According to the conversion factor K The frequency of the input magnetic flux periodic change signal is corrected to adjust the waveform of the magnetic flux periodic change signal, thereby correcting the influence of bearing friction and fluid viscous resistance in the low flow range and reducing measurement error.

[0019] 3. The flow correction method disclosed in this invention divides the flow into segments and matches an appropriate conversion coefficient according to the flow segment to which the flow belongs during detection. K This allows the frequency output range to expand from a single conversion factor. K The decision is transformed into a conversion coefficient based on multiple flow segments. K This decision led to an increase in the range of flow detection and greater adaptability.

[0020] 4. The flow correction method disclosed in this invention simplifies the measurement process by integrating the signal conversion component into the sensor, enabling direct measurement of the flow data passing through the sensor. The display directly shows the instantaneous flow and cumulative flow, reducing the number of measurement devices and improving reliability. Attached Figure Description

[0021] The present invention will be further described in conjunction with the following drawings and embodiments. All inventive concepts of the present invention should be considered as disclosed content and within the scope of protection of the present invention.

[0022] Figure 1This is a schematic diagram of the overall structure of the flow meter with display according to the present invention.

[0023] Figure 2 This is an exploded structural diagram of the flow sensing part of the present invention.

[0024] Figure 3 This is a flowchart illustrating the electronic control principle and signal processing of the present invention.

[0025] The components include: 1. Housing; 2. Snap ring; 3. Nut; 4. Signal cable connector; 5. Sensing assembly; 6. Flow guide; 7. Impeller assembly; 100. Flow sensing area; 200. Flow converter. Detailed Implementation

[0026] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments.

[0027] Example 1: like Figure 1 As shown, the flow meter consists of two parts: a flow sensing area 100 and a flow converter 200.

[0028] like Figure 2 As shown, the mechanical mechanism of the flow sensing includes a housing 1, a retaining ring 2, a nut 3, a signal line connector 4, a sensing component 5, a flow guide 6, and an impeller assembly 7. The flow sensing zone 100 is used to sense the flow velocity of the liquid in the pipeline, converting the fuel flow velocity into the impeller speed. The impeller cuts the magnetic field of the coil assembly in the signal converter, causing the coil assembly to generate an alternating current pulse signal of a certain frequency. The speed of the impeller is detected by the induction coil in the sensing component 5, which is mounted outside the housing 1. When the impeller cuts the magnetic lines of force generated by the permanent magnet inside the housing 1, it causes a change in the magnetic flux in the induction coil of the sensing component 5. When the fluid flows through, it drives the impeller to rotate, and the impeller blades cut the magnetic field generated by the sensing component 5, generating an alternating current signal.

[0029] like Figure 3 As shown, the electrical signal is sent to a signal conversion circuit, where it is amplified and shaped to form a pulse signal proportional to the flow rate. One path of this pulse signal is sent to a unit conversion and flow calculation circuit to obtain and display the cumulative flow value; the other path is sent to a frequency-current conversion circuit to obtain the instantaneous flow value, which is then displayed on a screen. The signal conversion module includes a preamplifier and... K The value correction unit sends the detected periodic change signal of magnetic flux from the induction coil to the preamplifier of the signal conversion module for amplification, and then... K Value correction unit shaping, based on the conversion coefficients corresponding to different flow ranges. KThe frequency of the periodic change signal of the magnetic flux is adjusted to generate a pulse signal proportional to the flow velocity. The signal calculation module includes a unit conversion and flow totalization circuit and a frequency-current conversion circuit. The two circuits are connected to the display. The pulse signal is input to the unit conversion and flow totalization circuit to obtain the cumulative flow value and display it on the display. The pulse signal is input to the frequency-current conversion circuit to convert the pulse signal into an analog current quantity to obtain the instantaneous flow value and display it on the display screen.

[0030] This embodiment provides a traffic correction method, including the following steps: Step S1: Acquire the magnetic flux periodic change signal characterizing the flow velocity of the target fluid; Step S2: Based on the conversion coefficient corresponding to the flow segment to which the magnetic flux periodic change signal belongs. K The frequency of the periodic change signal of the magnetic flux is adjusted and the signal is amplified to obtain a pulse signal; Step S3: Obtain the instantaneous flow rate and cumulative flow rate of the target fluid based on the pulse signal.

[0031] The flow meter has built-in software correction, allowing different meter coefficients to be input for different flow ranges. K Value, software based on K The value adjusts the waveform of the input signal and outputs the adjusted waveform, increasing the frequency output range of the flowmeter and significantly improving the measurement accuracy of the product. Each flow calibration point of the product corresponds to a conversion coefficient. Ki' Conversion factor Ki With frequency fi and flow value Qi The relationship is as follows: Ki= ( fi / Qi )×3600; In the formula: Ki For the first i Instrument conversion coefficient for each flow calibration point (number / L); fi For the first i Average measurement frequency (Hz) at each flow calibration point; Qi For the first i Flow rate (L / h) at each flow calibration point; Determine the measurement frequency at each flow calibration point of the product. fi Each point should be checked at least 3 times.

[0032] For commonly used turbine flow meters, the flow rangeability (the ratio of maximum flow to minimum flow) is typically greater than 5 but not greater than 10. Generally, the calibration points for flow rate verification should include: Qmin 0.25 Qmax 0.4 Qmax 0.7Qmax , Qmax ; Qmin This is the lower limit of the traffic volume. Qmax This represents the maximum traffic limit.

[0033] Taking a flow meter with a flow range of (10000-60000) L / h and an accuracy of 0.2% as an example, based on... Qmin 0.25 Qmax 0.4 Qmax 0.7 Qmax , Qmax Five flow rate calibration points were selected: 10000 L / h, 15000 L / h, 24000 L / h, 42000 L / h, and 60000 L / h.

[0034] Products K The coefficient is calculated using the following formula: Where: Nij—the number of pulses measured in the j-th measurement at the i-th flow calibration point; Vij — Actual volume (L) of the j-th measurement at the i-th flow calibration point; Kij — Conversion factor for the j-th measurement of the i-th flow value (number / L); Ki — Average value of meter conversion coefficient for the i-th flow rate (number / L); Determine the conversion coefficient for each flow rate calibration point of the product. Ki Each point should be checked at least 3 times.

[0035] Calculate the conversion factor for each product using the following formula: Where: MAX(K1:K5) — the maximum K value of the 5 flow rate calibration points; Min(K1:K5) — The minimum K value for the 5 flow rate calibration points; The current flow error is calculated using the following formula: High-precision flow meters can achieve an accuracy of 0.2%, meaning that the measurement error requirement is met at all five flow calibration points: 10000 L / h, 15000 L / h, 24000 L / h, 42000 L / h, and 60000 L / h. However, their overall measurement range is relatively narrow, with a flow range tolerance of only 6, and they require frequent calibration; otherwise, out-of-tolerance situations are very likely to occur.

[0036] The flow sensor measurement range is divided into 4 frequency bands: K1is 10000 L / h to 15000 L / h; K2 is 15000 L / h to 24000 L / h; K3 is 24000 L / h to 42000 L / h, K4 is 42000 L / h to 60000 L / h. Write the set K coefficients of each frequency into the software algorithm, and according to the flow rate of each flow rate calibration point, output the modulated frequency in the corresponding flow rate segment, that is: fi =( ki × Qi ) / 3600, output the modulated frequency fi and perform error calculation.

[0037] Optionally, the magnetic flux periodic change signal is collected by the cooperation of the turbine and the induction coil.

[0038] Specifically, the target fluid is used to drive the turbine to rotate, so that the blades of the turbine cut the magnetic field lines generated by the permanent magnet, causing a change in the magnetic flux in the induction coil, and obtaining a magnetic flux periodic change signal proportional to the flow rate of the target fluid.

[0039] The core of this embodiment is: divide the flow rate range into (N + 1) detection segments, but only allocate independent K values to M of them (M < N + 1), and simplify the system by combining the K coefficients of the linear segments. Use the software to modulate the output frequency in real time according to the selected K value, effectively compensating the non-linear error in the small flow rate segment, improving the measurement accuracy to above 0.2%, and broadening the frequency output and flow rate measurement range, with the advantages of high precision and wide range.

[0040] The flow rate correction method of this embodiment has two prominent technical advantages of accuracy improvement and frequency output range broadening.

[0041] On the one hand, before the product is software-modulated, the errors of each flow rate calibration point are relatively fixed and need to be calibrated frequently, and it is very easy to have the situation of error exceeding the standard. In the measurement range of the turbine flow sensor, the small flow rate segment is generally in the non-linear segment, and its characteristics are greatly affected by the bearing friction and fluid viscous resistance, resulting in a relatively large flow rate measurement error. Using software for frequency modulation, calculate according to the K coefficient used in the calculation, that is: fi =( K × Qi ) / 3600, input the corresponding coefficient value according to the required standard frequency fi , that is: ki , that is: ki= ( fi / Qi )×3600, in the ideal state, its measurement error should approach 0, and the measurement error of the product mainly comes from the conversion error in the modulation process, greatly improving the measurement accuracy.

[0042] On the other hand, before software modification of the product K Taking coefficient 28 (pieces / L) as an example, according to fi =( ki × Qi The frequency output range is (77.8~466.7) Hz, determined by the sensor's inherent properties and fixed before software modulation. If the input... K1 If the input is 26, then the minimum output frequency is 72.2Hz. K4 If the value is 30, then the maximum output frequency is 500Hz, and the product's frequency output range is widened from (77.8~466.7)Hz to (72.2~500)Hz. Qi= ( fi / K The value is 3600, which corresponds to a flow measurement range of (9282~64285) L / h, with each flow segment input. K The value can be determined based on the actual project requirements.

[0043] Example 2: This embodiment is a further optimization based on Embodiment 1 described above. In this embodiment... K High-precision flow meters with adjustable coefficients, including: Sensing component 5, the sensing component 5 being used to acquire magnetic flux periodic change signals characterizing the flow velocity of the target fluid; The signal conversion module is used to convert the signal based on the conversion coefficients corresponding to different flow segments. K The frequency of the periodic change signal of the magnetic flux is adjusted and the signal is amplified to obtain a pulse signal; The signal processing module is used to obtain the instantaneous flow rate and cumulative flow rate of the target fluid based on the pulse signal.

[0044] Example 3: This embodiment is based on Embodiment 1 or Embodiment 2, taking a flow meter with a flow range of 10,000~60,000 L / h and a target accuracy of 0.2% as an example.

[0045] The first step is calibration. Five flow rate calibration points are selected: Q1 =10000L / h, Q2 =15000L / h, Q3 =24000L / h, Q4 =42000L / h, Q5 =60000 L / h. Measured 3 times at each point, using the formula: Kij = Nij / Vij and Ki =( Ki 1+Ki 2+ Ki 3) / 3 Calculate the average K value for each point.

[0046] The second step is to determine the product. K Coefficient. Five flow rate calibration points were selected. K The maximum and minimum values ​​are determined by the formula. K =(MAX( K1 : K5 )+MIN (K1 : K5 )) / 2 calculates the benchmark for this product. K coefficient.

[0047] The third step is segmented configuration. The flow range is divided into four segments: I (10000~15000), II (15000~24000), III (24000~42000), and IV (42000~60000). Since segments II and III are in the linear operating segment, K Values ​​that change little can be combined and used in the same way. K Values ​​(e.g.) K2 Therefore, we assign 3 to the 4 segments. K Value: Segment I K1 Segments II and III use K2, and segment IV uses K2. K3 These K values ​​are obtained by fine-tuning the baseline K coefficients according to the characteristics of each segment.

[0048] Fourth step, run the modulation, K1 , K2 , K3 Write it into the software. During runtime, if traffic is detected in segment I, then call... K1 , and according to f =( K1 × Q ) / 3600 output frequency; in segment II or III, then call K2 In segment IV, the function is called. K3 .

[0049] After the above processing, the error of the flow meter was effectively controlled within 0.2% across the entire flow range. Simultaneously, by setting... K1 Slightly smaller than the benchmark K , K3 Slightly larger than the benchmark K This results in a lower output frequency at the minimum flow rate and a higher output frequency at the maximum flow rate, thereby widening the frequency output range and the actual measurable flow range.

[0050] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Any simple modifications or equivalent changes made to the above embodiments based on the technical essence of the present invention shall fall within the protection scope of the present invention.

Claims

1. A flow rate correction method characterized by, The method comprises the following steps: Step S1, collecting a magnetic flux periodic change signal representing a flow rate of a target fluid; Step S2, adjusting a frequency of the magnetic flux periodic change signal and performing signal amplification according to a conversion coefficient K corresponding to a flow section to which the magnetic flux periodic change signal belongs, to obtain a pulse signal; Step S3, obtaining an instantaneous flow value and an accumulated flow value of the target fluid according to the pulse signal.

2. The flow rate correction method according to claim 1, characterized by, The step S2 comprises: Step S21, dividing flow sections according to preset flow calibration points; Step S22, obtaining a calibration point conversion coefficient corresponding to each flow calibration point, and calculating a measurement frequency average value corresponding to each flow calibration point according to the calibration point conversion coefficient; Step S23, obtaining a conversion coefficient K corresponding to each flow section according to the calibration point conversion coefficient and the measurement frequency average value; Step S24, performing error correction on a frequency of the magnetic flux periodic change signal and performing signal amplification according to a current flow and the conversion coefficient K corresponding to each flow section, to obtain a pulse signal.

3. The flow rate correction method according to claim 2, characterized by: The flow verification points are configured as five, respectively Qmin , 0.25 Qmax , 0.4 Qmax , 0.7 Qmax , Qmax , wherein, Qmin is the flow lower limit value of the flow range of the turbine flowmeter, Qmax is the flow upper limit value of the flow range of the turbine flowmeter.

4. The flow rate correction method according to claim 2, characterized by: The relationship between the test point conversion coefficient and the average value of the measurement frequency satisfies: Ki= fi / Qi ) × 3600;​ in, Ki For the first i The conversion factor for each flow rate calibration point is expressed as calibration points per L. fi For the first i The average measurement frequency at each flow calibration point is expressed in Hz. Qi For the first i The flow rate at each flow calibration point is expressed in L / h.

5. The flow correction method according to claim 2, characterized in that: The conversion coefficients K The relationship between the conversion coefficients and the test point conversion coefficients satisfies: ； wherein, K1 to Kn is the conversion factor for the flow calibration point corresponding to the flow calibration point of the flow section.

6. The flow correction method according to claim 5, characterized in that: Before determining the conversion coefficient K Before determining the conversion coefficient, the conversion coefficient corresponding to each flow test point is tested, and the average value of the test results of each flow test point is obtained as the conversion coefficient of the test point. The relationship between the flow rate calibration point test results and the calibration point conversion coefficient satisfies: and ,in, Nij For the first i The first flow calibration point j Number of pulses in the second test Vij For the first i The first flow calibration point j The actual flow volume of this test is expressed in liters (L). Kij For the i-th flow calibration point j The test results are expressed in units of samples per L. Ki For the first i The average value of the test results at each flow calibration point, expressed in units of points / L. n To test the number of times.

7. The flow correction method according to claim 2, characterized in that: A calculation formula of an error of each flow calibration point is: ； wherein, K is the conversion factor, in units of L, fi is the average of the measurement frequency of the flow rate verification point number i , in units of Hz, Qi is the flow rate of the flow rate verification point number i , in units of L / h.

8. A K-factor adjustable high accuracy flowmeter characterized by, for implementing the flow correction method according to any one of claims 1-7; The K coefficient adjustment high-precision flowmeter comprises: an induction assembly (5) for collecting a magnetic flux periodic change signal representing a flow rate of a target fluid; a signal conversion module for adjusting a frequency of the magnetic flux periodic change signal and performing signal amplification according to a conversion coefficient K corresponding to different flow sections, to obtain a pulse signal; a signal solving module for obtaining an instantaneous flow value and an accumulated flow value of the target fluid according to the pulse signal.

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