Turbine rotation detection device and turbine flowmeter

Abstract

The utility model relates to a turbine rotation detection device and a turbine flowmeter. The turbine rotation detection device is provided with three sensors used for detecting rotation of blades, detection positions of the three sensors are distributed on the same circumference in a blade rotation track at equal intervals, the sensors are laser sensors and are provided with emitters and receivers, the emitters and the receivers of the same sensors are arranged on the same straight line, and the emitters and the receivers of the same sensors are arranged on the same straight line. The transmitting end and the receiving end face inwards, and every two light paths of the three sensors intersect to form an angle of 60 degrees. The turbine flow meter is provided with a main shell, a detection cavity is formed in the main shell, a blade serving as a rotating piece is arranged in the detection cavity, the turbine flow meter is further provided with a detection device used for detecting rotation of the blade, and the detection device is the turbine rotation detection device. The air flow direction change can be identified, the inertia modulus of the blade is small, the distortion or error of detection data can be reduced, and the air flow detection device can be mainly used for lung function detection.

Description

TECHNICAL FIELD

[0001] The utility model relates to turbine rotation detection device and turbine flowmeter belongs to fluid detection and medical instrument technical field. BACKGROUND

[0002] Turbine flowmeter is commonly used in the instrument of vital capacity / pulmonary function detection, and the exhalation and inhalation flow is pushed by the guide wheel to drive the blade to rotate, and the blade rotation frequency is obtained by using the photoelectric detection mode, so that the flow value and the capacity value are calculated. For example, the Chinese patent document CN117045231A discloses a turbine type multifunctional vital capacity meter, which comprises a turbine, a turbine rotation signal acquisition module, a handheld shell, a controller, a gas pump, a gas measurement cavity and a carbon dioxide concentration sensor, the turbine and the turbine rotation signal acquisition module are located in the handheld shell, one end of the gas pump is connected with the gas output port of the handheld shell through a pipeline, the other end is connected with 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 for judging the start time of receiving the exhaled gas according to the output signal of the turbine rotation signal acquisition module, measuring the vital capacity, and driving the gas pump to open, and obtaining the carbon dioxide concentration value of the exhaled gas according to the output signal of the carbon dioxide concentration sensor, which has the functions of vital capacity and CO2 concentration detection. The Chinese patent document CN113520367A discloses a portable lung function detector and its working method, which comprises a host computer, a blow nozzle head and a mask. The traditional lung function detector host computer is improved to make the host computer convenient to carry, and a mask compatible with the host computer is designed. The mask is provided with a fixing member, which can effectively prevent the mask from falling off when the patient is moving. The inner edge of the mask is provided with a sticky piece, which can tightly connect the mask with the patient's face, ensuring that all the exhaled gas or inhaled gas of the patient during the movement passes through the turbine flowmeter, and the data calculated by the turbine circuit board is the respiratory intensity data of the patient during the movement. These turbine flowmeters are widely used due to their good noise resistance, low pneumatic resistance, small influence of atmospheric pressure change and low production cost. However, in some cases, for example, near the end of exhalation, the detection error is relatively large, which affects the accuracy of the vital capacity or other related detection data.

[0003] To obtain more accurate detection data, some improved technologies have emerged. For example, Chinese patent document CN118310587A discloses a turbine flowmeter, which includes a main body, an accommodation cavity formed inside the main body, and a fluid outlet provided on the main body; a rotating shaft located inside the accommodation cavity and rotationally connected with the main body; a turbine provided on the rotating shaft and located inside the accommodation cavity; and a probe provided on the main body and including a measuring head located inside the accommodation cavity and on the side of the turbine close to the fluid outlet. The measuring head is arranged to measure the pressure of the fluid after it leaves the turbine, so as to determine the absolute fluid speed angle of the fluid after it leaves the turbine according to the pressure. This turbine flowmeter can measure the absolute fluid speed angle of the fluid after it leaves the turbine while measuring the fluid flow, and the absolute fluid speed angle can be used to correlate with 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 lung function instrument, which includes the following steps: S10 inputting collected data into a sliding average processing to obtain a new data column O(new)n; S20 removing low threshold data and performing sparse processing on the data; S30 finding peak points; S40 calculating an adjustment coefficient a according to the frequency of the peak points; and S50 substituting the data into the following exhalation volume model: Compared with existing technologies, based on the theoretical basis of the steady-state gas turbine flow model, the frequency coefficient adjustment algorithm based on peak point detection is proposed based on a double-blade shaft tip type gas flow turbine, which solves the problem of large exhalation volume calculation error and improves the acceptability of the volume calculation result. i

[0004] These technologies have unique features and are beneficial to improving the accuracy of detection data, but still have certain limitations. For example, one important defect is that a single rotation counter (sensor) is used for turbine rotation detection (counting), which cannot identify the rotation direction of the turbine. For example, if the subject performs a short inhalation during exhalation detection or a short exhalation during inhalation detection, the detection result will be severely distorted. In addition, due to the relatively large inertia of the turbine, inertia rotation will also cause certain errors. Practical new type content

[0005] The purpose of the present utility model is to reduce the detection error of the turbine flowmeter.

[0006] The technical scheme of the present utility model is: a turbine rotation detection device is provided with a sensor for detecting blade rotation, the number of sensors is three, and the detection positions of the three sensors are equally spaced (angular distance) distributed on the same circumference in the blade rotation track. Generally, the plane where the circumference (circle) is located is perpendicular to the axis of blade rotation, and the intersection of the axis of blade rotation and the plane is the center of the circumference.

[0007] ​Preferably, the sensor is a laser sensor, provided with a transmitter and a receiver, the transmitter and the receiver of the same sensor are arranged on the same line, the transmitting end and the receiving end are inward, and the light paths of the three sensors intersect each other at an angle of 60°.

[0008] Preferably, the laser sensor is an infrared laser sensor.

[0009] Preferably, the cavity of the detection cavity (the shell forming the detection cavity) is a transparent cavity or a cavity capable of transmitting the laser used by the laser sensor, which can be mounted on a bracket.

[0010] Further, the laser sensor (including the transmitter and the receiver) is also mounted on the bracket.

[0011] The turbine flowmeter is provided with a main shell, a detection cavity is arranged in the main shell, a blade serving as a rotating part is arranged in the detection cavity, and a detection device for detecting the rotation of the blade is arranged.

[0012] Further, the turbine flowmeter is provided with a main shell, two guide wheels are arranged in the detection cavity, both guide wheels adopt a turbine structure, and are fixed and sealed (the connection part is sealed, that is, the outer circle of the guide wheel and the inner wall of the detection cavity are sealed) on the inlet side and the outlet side of the detection cavity, respectively, the blade is a rectangular straight blade (flat blade) located between the two guide wheels, the blade shaft is arranged in the middle of the blade and is fixed as a whole, and two bearings for rotating and supporting the blade shaft are arranged on the inner side (towards the blade side) of the two guide wheels.

[0013] Preferably, the circumferential surface of the guide wheel is provided with an annular groove, the number of the annular grooves is one or more, and a sealing ring is embedded on the annular groove, so as to realize the sealing between the guide wheel and the inner wall of the detection cavity.

[0014] Preferably, the blade is an ultra-thin blade, for example, the thickness of the blade is ≤0.05mm.

[0015] Preferably, the blade material is a light plastic, for example, PET material or similar light plastic.

[0016] Preferably, the surface of the blade is provided with a light shielding layer to block light. For example, the surface of the blade is sprayed with light shielding paint or other alternative coating.

[0017] Preferably, the blade shaft is a pointed shaft, and the bearing adopts a sapphire bearing or a polyformaldehyde bearing.

[0018] Preferably, the two guide wheels adopt the same basic structure and have consistent swirling directions.

[0019] Preferably, the included angle between the airflow direction of the outlet side of the flow guiding wheel and the blade plane is 45-90 degrees.

[0020] Preferably, the turbine flow meter is also provided with a differential pressure sensor, the inlet side (high pressure side) of the differential pressure sensor is provided with a pressure tapping on the inlet side of the detection chamber, and the outlet side (low pressure side) is provided with a pressure tapping on the outlet side of the detection chamber or communicated with the atmosphere.

[0021] The beneficial effects of the utility model are: as three-sensor detection mode is adopted, the rotating direction of the blade can be recognized, the changeable breathing state of the subject in the test process can be found at any time, the detection result distortion caused by the changeable breathing state is avoided, and the detection precision at the end can be improved; as the rotating part adopts straight blades, under the condition of ensuring the pushing effect of the airflow on the blades, compared with directly adopting a turbine as the rotating part, the mass (weight) and the moment of inertia of the rotating part are effectively reduced, the response speed of the rotating part to the airflow change is improved, and the sensitivity at the detection initial stage and the detection end stage is improved; as the differential pressure flow detection device can also be arranged on the basis of the turbine flow meter, under the condition of being lower than the effective detection lower limit of the turbine, the detection data can be obtained by the differential pressure flow meter, and thus the detection error caused by the low flow at the detection end stage is further reduced.

[0022] The utility model can recognize the airflow direction change, the blade inertia modulus is small, helps to reduce the distortion or error of detection data, and mainly can be used for lung function detection. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 It is the sensor layout schematic view of the turbine rotation detection device of the utility model;

[0024] Figure 2 It is the detection timing diagram of three sensors of the turbine rotation detection device of the utility model;

[0025] Figure 3 It is the schematic view (explosion view / separation state view) of the turbine detection assembly in the flow meter of the utility model;

[0026] Figure 4 It is the schematic view of the flow meter provided with a differential pressure sensor,

[0027] Identified in the drawing: 1. flow guiding wheel; 2. bearing; 3. blade; 4. blade shaft. DETAILED DESCRIPTION

[0028] Referring to Figures 1-4The existing turbine flowmeter can be improved in the following aspects: 1) the guide wheel of the turbine structure is provided with straight blades as rotating members; 2) the blade shaft is a pointed shaft to reduce the contact area of the shaft and the bearing and realize nearly zero area contact; 3) light / low density blades and shafts are used; 4) the detection data of the differential pressure flowmeter is used when the flow is small (e.g., <50 mL / s); 5) the blade rotation detection method is improved to identify the rotation direction; and 6) the turbine natural inertia elimination method / algorithm is used to eliminate the influence of inertial rotation.

[0029] The above improvements can be implemented alone, in any combination, or all together.

[0030] Further description is as follows:

[0031] The guide wheel of the turbine structure (or guide structure) is provided with straight blades as rotating members.

[0032] Referring to Figure 1 In the detection cavity (the gas flow passage of the corresponding part in the shell), two front and rear turbine guide wheels 1 are arranged, blades 3 are arranged between the two guide wheels, the blades are rectangular straight blades (flat blades), the blade shaft is arranged in the middle of the blades (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 inlet gas flow (the inlet gas flows along the pipeline, which is axial) into a rotating forward (screw-shaped) rotational flow, which drives the straight blades to rotate, thereby greatly reducing the strength standard of the straight blades, reducing the thickness and area of the blades, and further greatly reducing the moment of inertia of the blades.

[0033] The number and shape of the turbine blades in the guide wheel should consider the guide resistance (including the influence of resistance on the lower limit of vortex detection and the sensitivity of differential pressure detection) and the pushing effect of the gas flow on the straight blades (especially at low flow, which depends on the angle between the gas flow and the blade plane, the perpendicular pushing force is the largest, and the parallel pushing force is zero). Generally, the angle between the gas flow (rotational flow) direction at the outlet side of the guide wheel and the blade plane is 45°-90° to obtain better overall effect.

[0034] The blade shaft is a pointed shaft to reduce the contact area of the shaft and the bearing, and to 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.

[0035] Lightweight materials are used to prepare the blades and blade shafts, and low-friction (low-friction coefficient) bearings (e.g., jewel bearings) are used to reduce friction.

[0036] With the development of material technology, light metal or plastic is more and more used, such as titanium, aluminum, plastic and other materials with low density and high strength, which can be used to prepare 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, in general cases, plastic has a lower density than metal materials. At the same time, the thickness of the blades can also be appropriately reduced, for example, ultra-thin blades are used. Through engineering test comparison, a preferred embodiment is to use PET material supported ultra-thin blades, and the thickness can be controlled to be ≤0.05mm. The surface of the ultra-thin blade is provided with (for example, sprayed with) a light-shielding paint (other alternative materials) surface coating, which realizes the blocking function of infrared rays, so that the infrared laser detector can effectively detect the blades.

[0037] The material of the blade shaft is selected to be a material with good rigidity, wear resistance and thin diameter, for example, a light steel shaft, and other light and rigid materials can also be selected, and the diameter of the shaft can be controlled to be within 0.3mm.

[0038] The bearing can be made of sapphire or POM (polyoxymethylene) plastic, and the sapphire material is preferred.

[0039] A differential pressure flow detection device (or a differential pressure flowmeter) is additionally provided, and the detection result of the differential pressure flowmeter is used at a small (extremely small) flow.

[0040] Due to the obstruction of the airflow by the guide wheels, there is a differential pressure between the front and back of the turbine detection assembly (blades and front and back guide wheels), and the differential pressure is positively correlated with the flow. By using the differential pressure detection principle, a differential pressure sensor (for example, a low differential pressure sensor) is additionally provided, a pressure sampling port (connected to the high pressure side interface) for the differential pressure sensor is arranged on the inlet side of the turbine detection assembly, and another pressure sampling port (connected to the low pressure side interface) is connected to the atmosphere or is arranged on the outlet side of the turbine detection assembly. When the flow is below the set lower limit of the turbine detection (for example, 50ml / s), low flow measurement is realized by means of the differential pressure principle, so as to make up for the problem of insufficient accuracy and precision of the turbine flowmeter at low flow. Through tests, after the differential pressure detection is increased, a resolution of 10mL / s or even lower can be realized under the design of the turbine detection assembly of the utility model.

[0041] During the detection process, when the blade frequency (or rotating speed, the same below) is zero or lower than the set lower limit of the detection, the detection result obtained by the differential pressure detection is the detection result, and when the blade frequency is greater than zero or not lower than the set lower limit of the detection, the detection result obtained by the turbine detection is the detection result. If necessary, a transition stage of the two detection results can also be set, and the fusion of the two detection results is implemented in the transition stage, for example, the upper limit and the lower limit (The lower limit can usually be zero or greater than zero.) When the blade frequency or rotational speed is between the upper and lower limits of the transition phase, the detection result (real-time flow rate) is calculated using the following formula:

[0042]

[0043] in, For the test results, For turbine inspection results, The result is from the differential pressure test. blade frequency ( ), This is the upper limit of the frequency for turbine detection during the transition phase. This is the lower limit of the frequency for turbine detection during the transition phase.

[0044] This method of determining the flow rate during the transition phase is also suitable for situations where the blade frequency enters the transition phase range during the detection process.

[0045] When the blade frequency is set to zero (because the blade is in an inertial rotation state), differential pressure detection data is used.

[0046] Improve the blade rotation detection method to identify the rotation direction and achieve high flow rate detection.

[0047] Turbine flow meters typically use laser detection devices to detect (or count) blade rotation. The laser detection device can be a split type, where the transmitter beam (or optical path) passes through the blade rotation area and is directed to the receiver. When there are no blades obstructing the view between the two, the receiver receives the optical signal. When the blades rotate between the two, the beam is blocked, and the receiver cannot receive the optical signal. Thus, rotation counting is achieved through photoelectric signal conversion (for example, the resistance value of a photoresistor switches to form different high and low level outputs).

[0048] See Figure 3 This invention employs three infrared laser detection devices (or infrared laser sensors, or infrared laser detectors) and three sets of transmitter-receiver pairs. The angle α between the optical paths (beams) of each transmitter-receiver pair is 60 degrees. All three beams are perpendicular to the blade axis and can typically be located in the same plane, but can also be positioned at different axial locations if necessary. This detection method not only identifies the direction of blade rotation and distinguishes between exhalation and inhalation (airflows in different directions), but also increases detection accuracy.

[0049] Figure 3The numbers outside the inner and outer circles (corresponding to the inner wall of the detection cavity) are used to indicate the position (in the form of a scale), and the inner circle is the trajectory of the blade vertex A and B during rotation. To illustrate the principle, assume that the distance / angle distance between adjacent scales (the position indicated by the scale) is 1 / 36 of the circumference (for example, the distance between scales 9_1 to 9, scale 9 to 9_2, and scale 9_2 to 8_1).

[0050] The positions of the three emitters are 9_2, 1_2, and 5_2, and the positions of the three receivers are 1_1, 5_1, and 9_1, respectively. The corresponding emitters and receivers are arranged opposite to each other, and their light beams pass along optical paths 1, 2, and 3, respectively. The intersection of each optical path with the blade rotation (trajectory) plane is the detection position of the sensor to the blade. When the blade (any part of the blade) is at this position, the light beam is blocked. When the position is changed without the blade, the optical path is connected.

[0051] According to the same principle, any other suitable form of sensor can be used instead of the above-mentioned infrared laser detector, and the detection position can be consistent with the detection position of the above-mentioned infrared laser detector.

[0052] For ease of analysis, the following assumptions are made: 1) the blade rotates uniformly counterclockwise; 2) the time zero point is when the blade passes through position 9_1; 3) a pair of emitters and receivers at the same position do not affect each other; 4) the high time sequence indicates that the optical path is open, and the low time sequence indicates that the optical path is closed; 4) the scale of the circumference passed by the blade A end (the numbers below the time sequence diagram) represents time.

[0053] Figure 4 The time sequence diagram of the detection is shown. The distance between 9_2 and 7_2 is 1 / 6 of the circumference, the distance between 7_2 and 5_2 is 1 / 6 of the circumference, and the distance between 5_2 and 3_2 is 1 / 6 of the circumference. It can be seen that it meets the requirement of one rising edge corresponding to 1 / 6 of the blade rotation. This detection method can realize 60-degree angle judgment, and can further increase the sensitivity of high-speed rotation detection when the blade rotates at high speed. Experiments have shown that this detection method can meet the requirements of YY / T1438 (ISO23747) standard, and can realize the detection of a maximum flow of 20 L / s while considering the sensitivity of low flow detection. At very low speed, since 60-degree angle recognition before rotation stop can be realized, lower rotation speed can be recognized.

[0054] Elimination of natural inertia through algorithm / model

[0055] Derivation of inertia rotation model / formula

[0056] The so-called natural inertia refers to the characteristic that the blade will continue to rotate (which can be called inertial rotation or inertial rotation) after the driving force disappears in the process of rotating under the driving of the airflow, and the inertial rotation will gradually stop (which can be called natural stop) under the action of resistance. Therefore, after the airflow stops, according to the inertial rotation of the blade, a certain air flow will still be counted, which is not real.

[0057] It is found that, in the case of sudden airflow stop, the natural stop time and the blade frequency at the time of airflow stop have a nonlinear negative correlation.

[0058] According to the experimental data, the curve function is obtained by fitting:

[0059]

[0060] The time zero point is the time (time point) when the frequency is .

[0061] The time zero point is set at the time of airflow stop, and 4000 (at present, it is generally believed that the maximum blade rotation frequency of the measurement system is 4000Hz), and the following inertial motion frequency-time function (which can be called inertial rotation model / formula) is obtained through experimental data fitting / verification:

[0062] 。

[0063] The inertial rotation model / formula can also be determined in other appropriate ways. The experimental data for constructing the inertial rotation model / formula can be obtained according to the corresponding flow detection instrument and the standard / precision higher flow detection device.

[0064] Inertial elimination of waveform using inertial rotation model (formula)

[0065] The measured (especially the end of the end) expiratory frequency-time data (which can be discrete data) and the frequency-time relationship of the inertial rotation model are compared. If they are consistent (the difference is within the allowable error range), it is considered that the rotation of the blade is inertial rotation, and the blade rotation frequency of the corresponding stage is set to 0. When there is also a pressure difference detection device, the pressure difference detection result of the corresponding stage is taken as the detection result.

[0066] Experiments show that the utility model can effectively improve the response speed and sensitivity, obtain higher precision flow value under low flow, realize the end of expiration and the end of inspiration curve should reach the platform, meet the requirements of the pulmonary function guide on the end of expiration judgment, and allow to improve the upper limit of the turbine flow, wherein the volume change of the last second of the end of expiration is <0.025L, reaching 0.0125L or even lower.

[0067] The various preferred and optional technical means disclosed in the utility model, except for the case where a preferred or optional technical means is further limited by another technical means as particularly stated, can be arbitrarily combined to form several different specific embodiments.

Claims

1. A turbine rotation detecting device provided with a sensor for detecting rotation of a blade, characterized by The number of the sensors is three, and the detection positions of the three sensors are equidistantly distributed on the same circle in the rotating track of the blade.

2. The turbine rotation detecting apparatus according to claim 1, wherein The sensor is a laser sensor, and is provided with a transmitter and a receiver. The transmitter and the receiver of the same sensor are arranged on the same straight line, and the transmitting end and the receiving end are inward. The light paths of the three sensors are crossed by two to form an angle of 60°.

3. The turbine rotation detecting apparatus according to claim 2, wherein The laser sensor is an infrared laser sensor.

4. The turbine rotation detecting apparatus according to claim 3, wherein The cavity of the detection cavity is a transparent cavity or a cavity capable of transmitting the laser used by the laser sensor, and is mounted on the bracket.

5. The turbine rotation detecting apparatus according to claim 4, wherein The laser sensor is mounted on the bracket.

6. A turbine flow meter having a main housing with a detection chamber disposed therein, characterized by The detection cavity is provided with a blade serving as a rotating member, and is also provided with a detection device for detecting the rotation of the blade. The detection device adopts the turbine rotation detection device according to any one of claims 1-5.

7. The turbine flow meter of claim 6, wherein The detection cavity is provided with two guide wheels in front and back. Both guide wheels adopt a turbine structure, are fixed and sealed at the inlet side and the outlet side of the detection cavity respectively, and 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 with the blade. Two bearings for rotating and supporting the blade shaft are arranged at the inner side center of the two guide wheels.

8. The turbine flow meter of claim 7, wherein The blade is an ultrathin blade, and the material thereof is light plastic. The surface of the blade is provided with a light shielding layer.

9. The turbine flow meter of claim 7, wherein The blade shaft is a pointed shaft, and the bearing adopts a sapphire bearing or a polyformaldehyde bearing.

10. The turbine flow meter of claim 7, wherein The two guide wheels adopt the same basic structure and have consistent cyclone directions.

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