A turbine flowmeter suitable for cardiopulmonary function testing

Abstract

The present invention relates to a turbine flowmeter suitable for cardiopulmonary function detection, which is provided with a main housing and a pressure difference sensor. A detection chamber is provided in the main housing, and a turbine detection assembly is provided in the detection chamber. The turbine detection assembly includes two front and rear guide wheels and blades. Both guide wheels adopt a turbine structure and are respectively fixed and sealed on the inlet and outlet sides of the detection chamber. The blade is located between the two guide wheels and is a rectangular straight blade. The blade shaft is arranged in the middle of the blade. Two bearings for rotating and supporting the blade shaft are respectively arranged at the inner center of the two guide wheels. The air intake side pressure taking port of the differential pressure sensor is opened on the inlet side of the detection chamber, and the outlet side pressure taking port is opened on the outlet side of the detection chamber or connected to the atmosphere. The present invention helps to improve the sensitivity and accuracy of the flowmeter at low flow rates and better adapt to related cardiopulmonary function detection.

Description

Technical Field

[0001] The invention relates to a turbine flowmeter suitable for cardiopulmonary function detection, belonging to the technical field of fluid detection and medical equipment. Background Art

[0002] The turbine flowmeter is a commonly used instrument in vital capacity / pulmonary function testing. The exhaled and inhaled air flows drive the blades to rotate through the guide wheel, and the blade rotation frequency is obtained by photoelectric detection, thereby calculating the flow value and capacity value. For example, Chinese patent document CN117045231A discloses a turbine multifunctional spirometer, including a turbine, a turbine rotation signal acquisition module, a handheld housing, a controller, an air pump, a gas measurement cavity and a carbon dioxide concentration sensor. The turbine and the turbine rotation signal acquisition module are both located in the handheld housing, one end of the air pump is connected to the gas output port of the handheld housing through a pipeline, and the other end is connected to the gas measurement cavity through a pipeline, and the detection end of the carbon dioxide concentration sensor is located in the gas measurement cavity; the controller is used to determine the start time of receiving the exhaled gas according to the output signal of the turbine rotation signal acquisition module, perform vital capacity measurement, and drive the air pump to start, and obtain the carbon dioxide concentration value of the exhaled gas according to the output signal of the carbon dioxide concentration sensor, and has both vital capacity and CO2 concentration detection functions. Chinese patent document CN113520367A discloses a portable pulmonary function tester and its working method, including a main unit, a mouthpiece and a mask. The main unit of the traditional pulmonary function tester is improved to make the main unit convenient to carry, and a mask adapted to the main unit is designed. The mask is provided with a fixing piece, and the fixing piece can be adjusted to effectively prevent the mask from falling off during exercise. The inner edge of the mask is provided with an adhesive patch, which can make the mask tightly connected to the patient's face, ensuring that all the gas exhaled or inhaled by the patient during exercise passes through the turbine flowmeter, and the data calculated by the turbine circuit board is the breathing intensity data of the patient during exercise. These turbine flowmeters are widely used due to their good noise resistance, low aerodynamic resistance, little influence by atmospheric pressure changes, and low production cost. However, in some cases, for example, near the end of exhalation, the detection error is relatively large, affecting the accuracy of vital capacity or other related test data.

[0003] In order to obtain more accurate detection data, some improved technologies have emerged. For example, Chinese patent document CN118310587A discloses a turbine flowmeter, including a main body, a receiving cavity is formed inside the main body, and the main body is provided with a fluid outlet; a rotating shaft, the rotating shaft is located in the receiving cavity, and the rotating shaft is rotatably connected to the main body; a turbine, the turbine is arranged on the rotating shaft, and the turbine is located in the receiving cavity; a probe, the probe is arranged in the main body, the probe includes a probe, the probe is located in the receiving cavity and on the side of the turbine close to the fluid outlet, and the probe is arranged to be able to measure the pressure of the fluid after leaving the turbine, so as to determine the absolute fluid velocity angle of the fluid after leaving the turbine according to the pressure. This turbine flowmeter can measure the absolute fluid velocity angle of the fluid after leaving the turbine while measuring the fluid flow rate, and the absolute fluid velocity angle can be used to associate with the system loss to improve the accuracy of the turbine flowmeter. Chinese patent document CN114224316A discloses a method for calculating lung function parameters based on a turbine-type pulmonary function instrument, comprising the following steps: S10 performs sliding average processing on the collected data input to obtain a new data column O(new)n; S20 removes low threshold data and performs data sparse processing; S30 finds the peak point; S40 calculates the adjustment coefficient α according to the frequency of the peak point i ; S50 substitutes the data into the following expiratory capacity model: Compared with the existing technology, on the theoretical basis of the steady-state gas turbine flow model, based on the double-blade shaft tip gas flow turbine, a frequency coefficient adjustment algorithm based on peak point detection is proposed, which solves the problem of large error in expiratory capacity calculation and improves the acceptability of capacity calculation results.

[0004] These technologies have unique features and are conducive to improving the accuracy of detection data, but they still have certain limitations. One of the important reasons is that due to the inertia and friction resistance of the turbine, when the airflow is small, the turbine cannot be driven to rotate, or the turbine rotation speed cannot reach the required level, resulting in the flow detection data being lower than the actual flow. On the other hand, also due to the inertia of the turbine, after the airflow stops, the turbine can still rely on inertia to continue to rotate, resulting in the flow detection data being higher than the actual flow. These factors will affect the accuracy of the flow detection results. Summary of the invention

[0005] The purpose of the present invention is to improve the sensitivity and accuracy of the flow meter at low flow rates and to better adapt to related cardiopulmonary function tests.

[0006] The technical solution of the present invention is: a turbine flowmeter suitable for cardiopulmonary function testing, provided with a main shell, and also provided with a differential pressure sensor, a detection chamber is provided in the main shell, a turbine detection assembly is provided in the detection chamber, the turbine detection assembly includes two front and rear guide wheels and blades, the two guide wheels both adopt a turbine structure, and are respectively fixed and sealed (the mutually connected parts are sealed, that is, the seal between the outer circle of the guide wheel and the inner wall of the detection chamber) and installed on the inlet side and outlet side of the detection chamber, the blade is located between the two guide wheels, and is a rectangular straight blade (planar blade), the blade shaft is arranged in the middle of the blade, and is fixed to the blade as a whole, and two bearings for rotatably supporting the blade shaft are respectively arranged at the center of the inner side (towards the blade side) of the two guide wheels, the air inlet side (high pressure side) pressure taking port of the differential pressure sensor is opened on the inlet side of the detection chamber, and the outlet side (low pressure side) pressure taking port is opened on the outlet side of the detection chamber or connected to the atmosphere.

[0007] Preferably, the blade shaft is a pointed shaft.

[0008] Preferably, the bearing is a sapphire bearing or a polyoxymethylene bearing.

[0009] Preferably, the blade is an ultra-thin blade, for example, the blade thickness is ≤0.05 mm.

[0010] Preferably, the blade is made of lightweight plastic, such as PET material or similar lightweight plastic, and light blocking is achieved by providing a light-shielding coating on the blade, for example, light-shielding paint or other alternative coatings are sprayed on the blade surface.

[0011] Preferably, the two guide wheels adopt the same basic structure and the swirl directions are consistent.

[0012] Preferably, the angle between the airflow direction on the outlet side of the guide wheel and the blade plane is 45°~90°.

[0013] Preferably, three sensors are provided for detecting the rotation of the blades, and the detection positions of the three sensors are distributed at equal intervals (angular distances) on the same circumference.

[0014] Preferably, the sensor is a laser sensor (eg, an infrared laser sensor) provided with a transmitter and a receiver, the transmitter and receiver of the same sensor are arranged on the same straight line, the transmitting end and the receiving end face inwards, and the optical paths of the three sensors intersect each other at an angle of 60°.

[0015] Preferably, the cavity body of the detection cavity (the shell forming the detection cavity) is a transparent cavity or a cavity that can transmit the laser used by the laser sensor, and can be mounted on a bracket.

[0016] Furthermore, the laser sensor (including a transmitter and a receiver) is also mounted on the bracket.

[0017] Preferably, a lower limit of the frequency (rotation frequency, the same below) of the turbine detection (the detection performed by the turbine detection component, or the detection result obtained by calculating based on the blade speed / rotation frequency) is set. When the blade frequency (real-time frequency / measured frequency) is greater than (or not less than) the lower frequency limit of the turbine detection, the flow detection result of the turbine detection component (the flow result calculated based on the blade frequency) is confirmed as the flow detection result; when the blade frequency is less than (or not greater than) the lower frequency limit of the turbine detection, the flow detection result of the differential pressure sensor (the flow result obtained by calculating based on the pressure difference) is confirmed as the flow detection result.

[0018] Preferably, an upper frequency limit and a lower frequency limit of the turbine detection in the transition stage are set. When the blade frequency is not less than the upper frequency limit of the turbine detection in the transition stage, the flow detection result of the turbine detection assembly is confirmed as the flow detection result; when the blade frequency is not greater than the lower frequency limit of the turbine detection in the transition stage, the flow detection result of the differential pressure sensor is confirmed as the flow detection result. When the blade frequency is between the upper frequency limit and the lower frequency limit of the turbine detection in the transition stage, the flow detection result is determined according to the following formula:

[0019]

[0020] in is the flow detection result, This is the flow test result of the turbine test component. is the flow detection result of the differential pressure sensor, is the blade frequency, is the upper frequency limit of turbine detection in the transition phase, It is the lower frequency limit of turbine detection in the transition phase.

[0021] The above thresholds (upper and lower limits) can be set according to the effective detection range of the turbine detection component.

[0022] Preferably, an inertial rotation model is set to characterize (embody) the frequency-time curve (function) relationship under the inertial rotation of the blade. During the period when the blade frequency continues to decrease (the shortest duration of the period can be set, and the situation below the shortest duration is ignored), it is compared whether the change pattern of the blade frequency over time is consistent with the inertial rotation model (differences within the specified error range are allowed). If it is consistent with the inertial rotation model, the blade frequency of the period is set to zero.

[0023] The beneficial effects of the present invention are as follows: since the rotating part adopts straight blades, under the condition of ensuring the pushing effect of the airflow on the blades, compared with directly adopting the turbine as the rotating part, the mass (weight) and rotational inertia of the rotating part are effectively reduced, the response speed of the rotating part to the change of the airflow is improved, and the sensitivity of the detection start stage and the detection end stage is improved; since a pressure difference flow detection device is provided on the basis of the turbine flowmeter, under the condition of being lower than the effective detection lower limit of the turbine, the detection data can be obtained by relying on the pressure difference flowmeter, thereby further reducing the detection error caused by the low flow rate at the detection end stage; since the turbine assembly is placed in the transition stage, the turbine assembly is placed in the transition stage, and ... The detection result and the pressure difference detection result are merged into the confirmed detection result, which ensures the smoothness of the detection data when both the turbine detection and the pressure difference detection are set at the same time, and avoids the inaccuracy of a single detection method in the transition stage; due to the use of a three-sensor detection method, the rotation direction of the blades can be identified, and the changing breathing state of the subject during the test can be discovered at any time, avoiding distortion of the detection result due to changes in the breathing state, and can improve the detection accuracy at the end; due to the use of an inertial rotation model to correct the detection data of the turbine detection under inertial rotation, especially the detection data at the end of the detection, the detection accuracy is further improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a schematic diagram of the structure of turbine flow detection involved in the present invention;

[0025] Figure 2 It is a schematic diagram (explosion diagram / separation state diagram) of a turbine detection assembly involved in the present invention;

[0026] Figure 3 It is a schematic diagram of sensor arrangement in a three-sensor detection mode involved in the present invention;

[0027] Figure 4 It is a timing diagram of the three-sensor detection mode involved in the present invention;

[0028] Figure 5 It is a frequency-time curve diagram of blades under inertial rotation involved in the present invention.

[0029] Markings in the figure: 1. guide wheel; 2. bearing; 3. blade; 4. blade shaft. DETAILED DESCRIPTION

[0030] Research shows that when using a turbine flowmeter for vital capacity testing, the main reason that restricts the improvement of accuracy is that the turbine blades have rotational inertia, which leads to large flow errors at the beginning and end of exhalation due to inertia, and the existence of friction resistance further reduces the sensitivity in the corresponding situation. In addition, in order to take into account the sensitivity at low flow, it often presents nonlinear characteristics at high flow. Therefore, reducing inertia and increasing sensitivity at low flow become the key to improving the accuracy of vital capacity testing.

[0031] See also Figure 1-Figure 5 , mainly including the following improvements: 1) setting a guide wheel 1 of a turbine structure with straight blades 2 as rotating parts; 2) using a pointed shaft for the blade shaft 4 to reduce the contact area between the shaft and the bearing 3 and achieve near-zero contact area; 3) using lightweight / low-density blades and shafts; 4) using the detection data (detection results) of the differential pressure flowmeter at small flow rates (for example, <50mL / s); 5) improving the blade rotation detection method to identify the rotation direction; 6) using a turbine natural inertia elimination method / algorithm to eliminate the influence of inertial rotation.

[0032] The above improvements may be implemented individually, in any combination or in whole.

[0033] Further explanation:

[0034] A guide wheel (or guide structure) of a turbine structure is provided, with straight blades as rotating parts.

[0035] See also Figure 1 Two front and rear turbine-type guide wheels 1 are arranged in the detection cavity (the air flow channel of the corresponding part in the shell), and blades 3 are arranged between the two guide wheels. The blades are rectangular straight blades (flat blades), and the blade shaft is arranged in the middle of the blade (the blades on both sides of the shaft are symmetrical). The bearings for supporting the two ends of the blade shaft are arranged in the center of the front and rear guide wheels near the blade side (the surface facing the blade). The guide wheel converts the axial intake air flow (the intake air flows along the pipeline, which is axial) into a rotating forward (thread-shaped) vortex flow, which drives the straight blade to rotate, thereby greatly reducing the strength standard of the straight blade, reducing the thickness and blade area of ​​the straight blade, and thus greatly reducing the rotational inertia of the blade.

[0036] The number and shape of the turbine blades in the guide wheel should take into account the guide resistance (including the impact of resistance on the lower limit of eddy current detection and the sensitivity of pressure difference detection) and the driving effect of airflow on straight blades (especially at low flow rates) (depending on the angle between the airflow and the blade plane, with the thrust being maximum when vertical and zero when parallel). Usually, the angle between the airflow (swirl) direction on the outlet side of the guide wheel and the blade plane can be made 45°~90° to obtain a better overall effect.

[0037] The blade shaft adopts a pointed shaft to reduce the contact area between the shaft and the bearing, reduce the contact friction surface and friction resistance. The bearing used is a low-friction bearing matched with the pointed shaft, and any suitable existing technology can be used.

[0038] Suitable lightweight materials are used to make blades and blade shafts, and low-friction (low friction coefficient) bearings (e.g., jewel bearings) are used to reduce friction.

[0039] With the development of material technology, more and more lightweight metals or plastics, such as titanium, aluminum, plastic and other materials with low density and high strength, can be used to make blades and shafts. By controlling the density or weight of the blades and shafts to reduce inertia, the response of the turbine flowmeter can be effectively improved. For example, under normal circumstances, plastics have a lower density than metal materials. At the same time, the thickness of the blades can be appropriately reduced, for example, by using ultra-thin blades. Through engineering test comparison, a better implementation method is to use ultra-thin blades supported by PET material, and the thickness can be controlled to ≤0.05mm. The surface of the ultra-thin blade is provided (for example, sprayed) with a surface coating of light-shielding paint (other alternative materials) to achieve the function of blocking infrared rays to ensure that the infrared laser detector can effectively detect the blades.

[0040] The material of the blade shaft is selected to be a material with good rigidity, wear resistance and fine diameter, for example, a lightweight steel shaft, or other lightweight and rigid materials. The diameter of the shaft can be controlled within 0.3 mm.

[0041] The bearings can be made of materials such as sapphire or POM (polyoxymethylene) plastic, with sapphire materials being preferred.

[0042] A differential pressure flow detection device (or differential pressure flowmeter) is added, and the detection results of the differential pressure flowmeter are used at small (extremely small) flow rates.

[0043] Because the airflow is obstructed by the guide wheel, there is a differential pressure before and after the turbine detection assembly (blades and front and rear guide wheels), and the pressure difference is positively correlated with the flow rate. Using the principle of differential pressure detection, a differential pressure sensor (for example, a low differential pressure sensor) is added, and a pressure sampling port for the differential pressure sensor is set on the intake side of the turbine detection assembly (connected to the high-pressure side interface), and another pressure sampling port (connected to the low-pressure side interface) is connected to the atmosphere or opened on the outlet side of the turbine detection assembly. When the flow rate is below the set turbine detection lower limit (for example, 50ml / s), low flow measurement is achieved with the help of the differential pressure principle to compensate for the low flow accuracy perception and insufficient precision of the turbine flowmeter. After testing, under the design of the turbine detection assembly of the present invention, after adding differential pressure detection, a resolution of 10mL / s or even lower can be achieved.

[0044] During the detection process, when the blade frequency (or speed, the same below) is zero or lower than the set detection lower limit, the detection result obtained by the pressure difference detection is used as the detection result, and when the blade frequency is greater than zero or not lower than the set detection lower limit, the detection result obtained by the turbine detection is used as the detection result. If necessary, a transition stage between the two detection results can also be set, and the two detection results are fused in the transition stage. For example, for the blade frequency (or speed), the frequency (or speed) upper limit of the transition stage is set. and lower limit (The lower limit can usually be zero or greater than zero). When the blade frequency or speed is between the upper and lower limits of the transition stage, the detection result (real-time flow) is calculated as follows:

[0045]

[0046] in, For the test results, The turbine test results are: is the pressure difference detection result, is the blade frequency ( ), is the upper frequency limit of turbine detection in the transition phase, It is the lower frequency limit of turbine detection in the transition phase.

[0047] This method of determining the flow rate in the transition stage is also applicable to the situation where the blade frequency enters the transition stage range during the detection process.

[0048] When the blade frequency is set to zero (because the blade is in an inertial rotation state), the pressure difference detection data is used.

[0049] Improve the blade rotation detection method, identify the rotation direction, and achieve high flow detection.

[0050] Turbine flowmeters usually use laser detection devices to detect (or count) blade rotation. The laser detection device can be a split type, in which the transmitter light beam (or light path) passes through the blade rotation area and shoots to the receiver. When there is no blade blocking the two, the receiver receives the light signal. When the blade rotates between the two, the light beam is blocked and the receiver cannot receive the light signal. Therefore, the rotation counting is achieved through photoelectric signal conversion (for example, the resistance value of the photoresistor is switched to form different outputs of high and low levels).

[0051] See also Figure 3The present invention sets three infrared laser detection devices (or infrared laser sensors, or infrared laser detectors), sets three sets of transmitters and receivers, and the angle α between the optical paths (light beams) of each set of transmitters and receivers is 60 degrees. The three light beams are all perpendicular to the blade axis in different planes, and can usually be located in the same plane, or at different axial positions when necessary. This detection method can not only identify the rotation direction of the blade, distinguish between exhalation and inhalation (airflows in different directions), but also increase the detection accuracy.

[0052] Figure 3 The numbers outside the middle and outer circles (corresponding to the inner wall of the detection cavity) are used to indicate the position (in the form of scale), and the inner circle is the trajectory of the blade vertices A and B during rotation. To illustrate the principle, it is assumed that the spacing / angular distance between adjacent scales (positions indicated by the scales) (for example, the distance from scale 9_1 to 9, scale 9 to 9_2, and scale 9_2 to 8_1) is 1 / 36 of the circumference.

[0053] The three transmitters are located at 9_2, 1_2, and 5_2, and the three receivers are located at 1_1, 5_1, and 9_1, respectively. The corresponding transmitters and receivers are arranged relative to each other, and their light beams are respectively along light path 1, light path 2, and light path 3. The intersection of each light path and the blade rotation (track) plane is the sensor's detection position of the blade. When the blade (any part of the blade) is at this position, the light beam is blocked. When there is no blade at this position, the light path is connected.

[0054] Based on the same principle, any other suitable form of sensor may be used to replace the above infrared laser detector, and the detection position may be consistent with the detection position of the above infrared laser detector.

[0055] For the convenience of analysis, the following assumptions are made: 1) The blade rotates counterclockwise at a constant speed; 2) The time zero is when the blade passes position 9_1; 3) A pair of transmitters and receivers at the same position do not affect each other; 4) A high value in the timing indicates that the light path is open, and a low value indicates that the light path is closed: 4) The scale of the circle passed by end A of the blade (the number below the timing diagram) represents time.

[0056] Figure 4The timing diagram of the detection is shown. The interval between 9_2 and 7_2 is 1 / 6 of a circle, the interval between 7_2 and 5_2 is 1 / 6 of a circle, and the interval between 5_2 and 3_2 is 1 / 6 of a circle. It can be seen that the requirement that a rising edge corresponds to a rotation of 1 / 6 of a circle of the blade is met. This detection method can realize 60-degree angle judgment. When the blade rotates at high speed, the sensitivity of high rotation detection can be further increased. Experiments have shown that this detection method can meet the requirements of the YY / T1438 (ISO23747) standard. While taking into account the low flow detection sensitivity, it can achieve a flow detection of up to 20L / s. At extremely low speeds, since the 60-degree angle before the rotation stops can be recognized, a lower rotation speed can be recognized.

[0057] Eliminate natural inertia through algorithms / models

[0058] Derive the inertial rotation model / formula

[0059] The so-called natural inertia refers to the characteristic that when the blades rotate under the drive of airflow, the blades will continue to rotate (which can be called inertial rotation or inertial rotation) after the driving force suddenly disappears, and the inertial rotation will gradually stop under the action of resistance (which can be called natural stop). Therefore, after the airflow stops, a certain amount of airflow will still be counted according to the inertial rotation of the blades, and this airflow is not real.

[0060] The study found that when the airflow stops suddenly, there is a nonlinear negative correlation between the natural stop time and the blade frequency when the airflow stops. Figure 5 The corresponding frequency-time curve is given, where Fmax is the maximum frequency of blade rotation, F1–F5 indicates that the blade starts to perform inertial rotation motion at these 5 frequency points, and t4 is the time corresponding to F4.

[0061] According to the experimental data, the curve function is obtained by fitting:

[0062]

[0063] The time zero point in the formula is the frequency The moment (point in time).

[0064] Set the time zero to the moment when the airflow stops, and take is 4000 (it is generally believed that the maximum blade rotation frequency of the current measurement system is 4000Hz). After fitting / verification of experimental data, the following frequency-time function of inertial motion is obtained (which can be called inertial rotation model / model formula):

[0065] .

[0066] Any other suitable method may also be used to determine the inertial rotation model / formula. Experimental data for constructing the inertial rotation model / formula may be obtained based on a corresponding flow detector and a standard / higher precision flow detection device.

[0067] Eliminate the inertia of the waveform using the inertial rotation model (formula)

[0068] The measured (especially the final stage near the end) exhalation frequency-time data (which can be discrete data) is compared with the frequency-time relationship of the inertial rotation model. If the two are consistent (the difference is within the allowable error range), the rotation of the blades is considered to be inertial rotational motion, and the blade rotation frequency of the corresponding stage is set to 0. When a pressure difference detection device is also provided, the pressure difference retrieval result of the corresponding stage is used as the retrieval result.

[0069] Experiments show that the present invention can effectively improve the response speed and sensitivity, obtain higher-precision flow values ​​at low flows, achieve a platform for the end-expiratory and end-inspiratory curves, meet the requirements of the pulmonary function guidelines for judging the end of exhalation, and allow the upper limit of the turbine flow to be increased, where the volume change in the last second of end-expiration is <0.025L, reaching 0.0125L or even lower.

[0070] Unless otherwise specified or when one preferred or optional technical means is a further limitation of another technical means, the preferred and optional technical means disclosed in the present invention can be arbitrarily combined to form several different specific implementation methods.

Claims

1. A turbine flowmeter suitable for cardiopulmonary function testing, comprising a main housing, a detection chamber provided in the main housing, characterized in that A differential pressure sensor is also provided. A turbine detection assembly is provided in the detection chamber. The turbine detection assembly includes two front and rear guide wheels and blades. Both guide wheels adopt a turbine structure and are respectively fixed and sealed on the inlet and outlet sides of the detection chamber. The blade is located between the two guide wheels and is a rectangular straight blade. The blade shaft is arranged in the middle of the blade and is fixed to the blade as a whole. Two bearings for rotatably supporting the blade shaft are respectively arranged in the inner center of the two guide wheels. The air inlet side pressure taking port of the differential pressure sensor is opened on the inlet side of the detection chamber, and the outlet side pressure taking port is opened on the outlet side of the detection chamber or connected to the atmosphere. A lower frequency limit of turbine detection is set. When the blade frequency is greater than the lower frequency limit of turbine detection, the flow detection result of the turbine detection assembly is confirmed as the flow detection result; when the blade frequency is less than the lower frequency limit of turbine detection, the flow detection result of the differential pressure sensor is confirmed as the flow detection result.

2. The turbine flowmeter according to claim 1, characterized in that The blade shaft is a pointed shaft, and the bearing is a sapphire bearing or a polyoxymethylene bearing.

3. The turbine flowmeter according to claim 2, characterized in that The blades are ultra-thin blades made of lightweight plastic, and light blocking is achieved by arranging a light-shielding coating on the blades.

4. The turbine flowmeter according to claim 1, characterized in that The two guide wheels adopt the same basic structure and the swirl direction is consistent.

5. The turbine flowmeter according to claim 4, characterized in that The angle between the airflow direction on the outlet side of the guide wheel and the blade plane is 45°~90°.

6. The turbine flowmeter according to claim 1, characterized in that Three sensors are provided for detecting the rotation of the blades, and the detection positions of the three sensors are distributed at equal intervals on the same circumference.

7. The turbine flowmeter according to claim 6, characterized in that The sensor is a laser sensor, which is provided with a transmitter and a receiver. The transmitter and the receiver of the same sensor are arranged on the same straight line, with the transmitting end and the receiving end facing inwards, and the optical paths of the three sensors intersect each other at an angle of 60°.

8. The turbine flowmeter according to claim 7, characterized in that The cavity of the detection cavity is a transparent cavity or a cavity that can transmit the laser used by the laser sensor, and is installed on the bracket. The laser sensor is also installed on the bracket.

9. The turbine flowmeter according to any one of claims 1 to 8, characterized in that The frequency upper limit and frequency lower limit of the turbine detection in the transition stage are set. When the blade frequency is not less than the frequency upper limit of the turbine detection in the transition stage, the flow detection result of the turbine detection component is confirmed as the flow detection result; when the blade frequency is not greater than the frequency lower limit of the turbine detection in the transition stage, the flow detection result of the differential pressure sensor is confirmed as the flow detection result. When the blade frequency is between the frequency upper limit and frequency lower limit of the turbine detection in the transition stage, the flow detection result is determined according to the following formula: in is the flow detection result, This is the flow test result of the turbine test component. is the flow detection result of the differential pressure sensor, is the blade frequency, is the upper frequency limit of turbine detection in the transition phase, It is the lower frequency limit of turbine detection in the transition phase.

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