CN107374635B - Spirometer to prevent cross infection - Google Patents

Abstract

The invention provides a pulmonary function instrument that can prevent cross-infection, including a flow sensor and a pulmonary function instrument host, wherein the flow sensor and the pulmonary function instrument host are detachably assembled together, and the flow sensor is a hollow tube structure, comprising: The main vent pipe and the pressure taking hole arranged on the wall of the main vent pipe, the outer wall of the main vent pipe is provided with a pressure taking hole column that communicates with the pressure taking hole gas, it is characterized in that the volume of the cavity inside the pressure taking hole column The size satisfies the following conditions: During the process of pulmonary function testing, the gas exhaled or inhaled by the tester enters the pressure-taking hole column through the pressure-taking hole, and is kept in the pressure-taking hole column without touching the connecting pipe other than the flow sensor. The pulmonary function instrument of the present invention can isolate pollutants such as bacteria or viruses from entering other pipelines or cavities of the pulmonary function detector, so as to avoid cross-infection during the pulmonary function test.

Description

Spirometer to prevent cross infection

technical field

The invention relates to the field of pulmonary function detection, in particular to a pulmonary function instrument capable of preventing cross infection.

Background technique

Pulmonary function instruments, spirometers and other products on the existing market all use mouthpieces and disposable breathing filters to avoid cross-infection. Although mouthpieces and filters are both disposable, disposable breathing filters cannot be filtered. The filter with the highest efficiency, the higher the filtration efficiency, the better the isolation effect, but the greater the resistance to the airflow, the greater the impact on the gas flow of the lung function measurement, and the larger the measurement error, so one-time breathing The filter can only take into account the filtration efficiency, and choose a filter with less airflow resistance. Although it has the effect of isolating bacteria and viruses, it cannot completely isolate bacteria or viruses from entering the flow sensor.

In order to avoid cross-infection of the pulmonary function instrument after applying the filter, the pulmonary function instrument must be cleaned and disinfected regularly. The medical pulmonary function instrument is expensive and complicated in structure. It must be disassembled by professionals with special tools, and it is easy to be damaged. Thoroughly dry, and need to be recalibrated before use. The whole process is cumbersome, consumes a lot of time and costs, and the instrument cannot be used for a long time.

SUMMARY OF THE INVENTION

In order to overcome the above shortcomings, the purpose of the present invention is to provide a flow sensor for pulmonary function measurement that can prevent cross infection, which is a hollow tube structure, including a main ventilation tube and a pressure-taking hole provided on the wall of the main ventilation tube, The outer wall of the main ventilation pipe is provided with a pressure-taking hole column that communicates with the pressure-taking hole gas, and the volume size of the inner cavity of the pressure-taking hole column meets the following conditions: during the pulmonary function detection process, the gas exhaled or inhaled by the tester passes through The pressure taking hole enters the pressure taking hole column and is kept in the pressure taking hole column without touching the connecting pipeline outside the flow sensor.

According to the ideal gas equation of state and Boyle's law, at a certain temperature, the volume of the quantitative gas is inversely proportional to the pressure of the gas. By setting an appropriate pressure variation range, the volume change of the gas that is pressed into or overflowed from the pressure-taking hole can be limited. In the pressure-taking orifice column, there is no contact with the connecting pipeline other than the flow sensor.

Wherein, the volume of the cavity inside the pressure-taking hole column satisfies the following conditions, V ₁ >K(V ₁ +V ₂ ), V ₁ is the inner volume of the pressure-taking hole column, and V ₂ is the inner volume of the pressure-guiding tube connected to the pressure-taking hole column The volume of gas, K is a constant.

式中Δp为呼气进气部与喉口部的压差，ρ为流体密度，Q为流量，A₁为进气部的截面积，A₂为喉口部的截面积，通过调节A₁与A₂，获得Δp。The further calculation method of K value is to compare the K value with atmospheric pressure according to formula IV and Δp, where formula IV:

where Δp is the pressure difference between the exhalation air inlet and the throat, ρ is the fluid density, Q is the flow rate, A1 is the cross _- sectional area of the air intake, and A2 is the cross _- sectional area _of the throat. By adjusting A1 With A ₂ , Δp is obtained.

Preferably, the K value is 10%.

Further, the main ventilation pipe mainly comprises an exhalation air intake part, a first cone part, a throat part and a second cone part which are connected in sequence, and the pipe wall of the throat part is provided with a low pressure pressure taking hole and is connected with the low pressure take-off hole. The pressure hole column is communicated, and the tube wall of the exhalation air intake part is provided with a first high-pressure pressure-taking hole and communicated with the first high-pressure pressure-taking hole column, and the high-pressure pressure-taking hole column passes through the pressure guiding tube and the positive pressure end of the differential pressure sensor. Connection, the low-pressure pressure-taking hole column is connected to the negative pressure end of the differential pressure sensor through the pressure guiding tube,

Further, a second high pressure pressure taking hole is opened on the pipe wall of the second conical part and communicated with the second high pressure pressure taking hole column, and the second high pressure pressure taking hole column is connected with the positive pressure end of the differential pressure sensor.

Further, the exhalation air intake part and the throat part are cylindrical, the diameter of the exhalation air intake part is larger than the diameter of the throat part, the first cone part and the second cone part are truncated cones, and the first cone part and the second cone part are in the shape of a truncated cone. The ends with the smaller diameter of the tapered portion are respectively directed toward the throat portion.

Further, the outer wall of the cylinder of the pressure-taking hole column is provided with a groove, and the sealing ring is assembled in the groove.

Further, a clamping device is also included.

Further, the clamping device on the flow sensor is detachably connected to the pressure guiding tube connected to the differential pressure sensor on the spirometer through the connecting seat.

The present invention provides a method for preventing cross-infection in the process of measuring lung function, including providing a flow sensor, wherein the flow sensor is a hollow tube structure, comprising a main ventilation tube and a pressure-taking hole arranged on the wall of the main ventilation tube , the outer wall of the main ventilation pipe is provided with a pressure-taking hole column that communicates with the pressure-taking hole gas, and the volume size of the internal cavity of the pressure-taking hole column satisfies the following conditions: during the pulmonary function detection process, the gas exhaled or inhaled by the tester It enters the pressure-taking hole column through the pressure-taking hole, and is kept in the pressure-taking hole column without touching the connecting pipeline other than the flow sensor.

Wherein, the volume of the cavity inside the pressure-taking hole column satisfies the following conditions, V ₁ >K(V ₁ +V ₂ ), V ₁ is the inner volume of the pressure-taking hole column, and V ₂ is the inner volume of the pressure-guiding tube connected to the pressure-taking hole column The volume of gas, K is a constant.

式中Δp为呼气进气部与喉口部的压差，ρ为流体密度，Q为流量，A₁为进气部的截面积，A₂为喉口部的截面积，通过调节A₁与A₂，获得Δp。The further calculation method of K value is to compare the K value with atmospheric pressure according to formula IV and Δp, where formula IV:

where Δp is the pressure difference between the exhalation air inlet and the throat, ρ is the fluid density, Q is the flow rate, A1 is the cross _- sectional area of the air intake, and A2 is the cross _- sectional area _of the throat. By adjusting A1 With A ₂ , Δp is obtained.

Preferably, the K value is 10%.

The present invention also provides a pulmonary function meter capable of preventing cross infection, including a flow sensor, which is detachably assembled with the main body of the pulmonary function meter to form a pulmonary function meter. The flow sensor is a hollow tube structure, including a main vent pipe and a pressure taking hole arranged on the wall of the main vent pipe, and a pressure taking hole column that is in gas communication with the pressure taking hole is arranged on the outer wall of the main vent pipe. The volume size of the cavity inside the hole column meets the following conditions: During the lung function test, the gas exhaled or inhaled by the tester enters the pressure hole column through the pressure hole, and is kept in the pressure hole column without touching it. Connection lines other than the flow sensor.

Wherein, the volume of the cavity inside the pressure-taking hole column satisfies the following conditions, V ₁ >K(V ₁ +V ₂ ), V ₁ is the inner volume of the pressure-taking hole column, and V ₂ is the inner volume of the pressure-guiding tube connected to the pressure-taking hole column The volume of gas, K is a constant. Preferably, the K value is 10%.

式中Δp为呼气进气部与喉口部的压差，ρ为流体密度，Q为流量，A₁为进气部的截面积，A₂为喉口部的截面积，通过调节A₁与A₂，获得Δp。The further calculation method of K value is to compare the K value with atmospheric pressure according to formula IV and Δp, where formula IV:

where Δp is the pressure difference between the exhalation air inlet and the throat, ρ is the fluid density, Q is the flow rate, A1 is the cross _- sectional area of the air intake, and A2 is the cross _- sectional area _of the throat. By adjusting A1 With A ₂ , Δp is obtained.

The spirometer includes a differential pressure sensor. The differential pressure sensor is connected with the pressure-taking hole column of the flow sensor through a pressure-guiding pipe.

Compared with the prior art, the beneficial effect of the present invention is that the air in the pressure-taking hole column of the flow sensor can play an isolation role, so that the breath exhaled by the subject cannot contact other instruments and equipment of the spirometer, such as The connection seat or conduit connected with the pressure-taking hole column, therefore, the reused connection seat and conduit cannot come into contact with the subject's gas, and the flow sensor of the present invention can be replaced at any time, thus avoiding cross infection.

Description of drawings

Figure 1 is a schematic cross-sectional view of a disposable flow sensor with two pressure-taking orifice columns.

FIG. 2 is a schematic structural diagram of the connection between the disposable flow sensor and the differential pressure sensor shown in FIG. 1 .

3 is a schematic cross-sectional view of the changing position of the air column during exhalation of the disposable flow sensor with two pressure-taking hole columns.

Figure 4 is a schematic cross-sectional view of a disposable flow sensor with three pressure-taking orifice columns.

FIG. 5 is a schematic structural diagram of the connection between the disposable flow sensor and the differential pressure sensor shown in FIG. 4 .

6 is a schematic cross-sectional view of the changing position of the air column during exhalation of the disposable flow sensor with three pressure-taking hole columns.

7 is a schematic cross-sectional view of the changing position of the air column during inhalation of the disposable flow sensor with three pressure-taking hole columns.

8 is a schematic diagram of the connection between the flow sensor and the T-shaped pipe in Embodiment 4.

Detailed ways

As shown in Figures 1 to 7 , the flow sensor for pulmonary function detection is detachably assembled with the spirometer host to form a spirometer together. The flow sensor can prevent cross infection, and includes a main vent pipe and a pressure taking hole arranged on the wall of the main vent pipe, and the outer wall of the main vent pipe is provided with a pressure taking hole column which is in gas communication with the pressure taking hole. The pulmonary function tester exhales or inhales gas through the main airway, and the pressure hole is the sampling point for the differential pressure sensor to collect the gas flow in the main airway. The air conduit of the differential pressure sensor is not directly connected to the pressure-taking hole, but is indirectly connected to the pressure-taking hole through the pressure-taking hole column. The volume size of the cavity inside the pressure-taking hole column satisfies the following conditions: in the process of pulmonary function testing, the gas exhaled or inhaled by the tester will be pressed into or overflowed from the pressure-taking hole column through the pressure-taking hole, but is limited to the pressure-taking hole. inside the hole column without touching the connecting pipeline outside the flow sensor.

Example 1 Flow sensor with two pressure-taking orifice columns

As shown in FIGS. 1 to 3 , the main ventilation pipe of the flow sensor includes an exhalation air intake portion 1 , a first cone portion 2 , a throat portion 3 and a second cone portion 4 that are connected in sequence. The tube wall of the throat portion 3 is provided with a low-pressure pressure-taking hole 31 and communicated with the low-pressure pressure-taking hole column 5, and the tube wall of the exhalation air inlet portion 1 is provided with a first high-pressure pressure-taking hole 21 and is connected with the first high-pressure taking hole. The press hole column 6 is communicated. The expiratory air intake part 1 and the throat part 3 are cylindrical, and the diameter of the exhalation air intake part is larger than that of the throat part. The cross-sections of the first cone portion 2 and the second cone portion 4 are truncated cones, and the smaller diameter ends of the first cone portion and the second cone portion face the throat portion respectively.

As shown in FIG. 2 , the pressure guiding tube 201 of the differential pressure sensor 200 is connected to the pressure-taking hole post insertion hole 101 of the connection base 100 . 5 corresponds to the first high pressure pressure taking hole column 6 . Insert the pressure-taking hole column of the flow sensor shown in FIG. 2 into the pressure-taking hole column socket 101 of the connecting seat, and then the connection between the pressure guiding tube of the differential pressure sensor and the pressure taking hole of the flow sensor can be completed. The high pressure taking hole column is connected with the positive pressure end of the differential pressure sensor, and the low pressure pressure taking hole column is connected with the negative pressure end of the differential pressure sensor. As shown in Fig. 3, when the tester inhales gas into the main vent pipe of the flow sensor, the inhaled gas enters the low-pressure pressure-taking hole column 5 and the high-pressure pressure-taking hole column through the low-pressure pressure-taking hole 31 and the high-pressure sampling hole 21 respectively. 6 within. The original air 300 in the pressure taking hole column and the pressure guiding pipe 201 is continuously compressed by the newly entered gas 301 until the newly breathed gas into the pressure taking hole column and the original gas establish a new balance. The volume size of the internal cavity of the pressure-taking hole column of the present invention satisfies the following conditions: when the gas exhaled by the tester enters the pressure-taking hole column through the pressure-taking hole, the newly entered gas will compress the gas originally existing in the pressure-taking hole column. Air and the air in the pipeline connected to it, but the top end of the compressed air is always located in the pressure-taking hole column. As shown in FIG. 3 , since the volume of the cavity inside the pressure-taking hole column is sufficient to ensure that when a new equilibrium is established, the newly entered gas 301 still remains in the pressure-taking hole column and will not enter the pressure guiding tube.

Example 2 Flow sensor with three pressure-taking orifice columns

As shown in FIGS. 4 to 7 , the main ventilation pipe of the flow sensor includes an exhalation air intake portion 1 , a first cone portion 2 , a throat portion 3 and a second cone portion 4 which are connected in sequence. The tube wall of the throat portion 3 is provided with a low-pressure pressure-taking hole 31 and communicated with the low-pressure pressure-taking hole column 5; The orifice column 6 is communicated. A second high pressure pressure taking hole 41 is opened on the pipe wall of the second cone portion 4 and communicated with the second high pressure pressure taking hole column 7 . The expiratory air intake part 1 and the throat part 3 are cylindrical, and the diameter of the exhalation air intake part is larger than that of the throat part. The cross-sections of the first cone portion 2 and the second cone portion 4 are truncated cones, and the smaller diameter ends of the first cone portion and the second cone portion face the throat portion respectively.

As shown in FIG. 5 , the pressure guiding tube 201 of the differential pressure sensor 200 is connected to the pressure-taking hole column insertion hole 101 of the connection base 100 , and the position of the pressure-taking hole column insertion hole 101 is the same as that of the low pressure pressure-taking hole column of the flow sensor. Corresponding to the high pressure tap hole column. The first high pressure taking hole column 6 is connected with the positive pressure end of the first differential pressure sensor, the second high pressure taking hole column 7 is connected with the positive pressure end of the second differential pressure sensor, and the low pressure ends of the two differential pressure sensors pass through the three The through pipes are respectively connected with the low-pressure pressure-taking hole columns 5 . As shown in Figure 6, when the tester inhales gas into the main vent pipe of the flow sensor, the inhaled gas enters the low pressure pressure hole column 5 and the high pressure pressure through the low pressure pressure hole 31 and the high pressure sampling holes 21 and 41 respectively. Inside the hole columns 6 and 7. The original air 300 in the pressure taking hole column and the pressure guiding pipe 201 is continuously compressed by the newly entered gas 301 until the newly breathed gas into the pressure taking hole column and the original gas establish a new balance. As shown in Figure 7, when the tester inhales gas into the main vent pipe of the flow sensor, the inhaled gas enters the low pressure pressure hole column 5 and the high pressure pressure hole through the low pressure pressure hole 31 and the high pressure sampling holes 21 and 41 respectively. Inside columns 6 and 7. The original air 300 in the pressure taking hole column and the pressure guiding pipe 201 is continuously compressed by the newly entered gas 301 until the gas newly sucked into the pressure taking hole column and the original gas establish a new balance. The volume size of the inner cavity of the pressure-taking hole column of the present invention satisfies the following conditions: when the gas exhaled or inhaled by the tester enters the pressure-taking hole column through the pressure-taking hole, the newly entered gas will compress the gas originally existing in the pressure-taking hole column. The air inside and the air in the pipeline connected to it, but the top end of the compressed air is always located in the pressure-taking hole column. As shown in FIGS. 6 and 7 , since the volume of the cavity inside the pressure-taking hole column is sufficient to ensure that when a new equilibrium is established, the newly entered gas 301 will not enter the pressure-guiding tube.

Embodiment 3 Flow sensor optimized structure

The flow sensor is for one-time use, and the connection between it and the differential pressure sensor is detachable.

In order to ensure the air-tightness of the connection between the pressure guiding tube and the flow sensor during the test, a sealing element is provided between the pressure-taking hole column and the pipe connected to it. For example, there is a groove 9 outside the pressure-taking hole column of the flow sensor To store the sealing ring 19.

In other embodiments, the flow sensor further includes a clamping device that can stably install the flow sensor on the main body of the spirometer. The clamping device can ensure that the flow sensor inserted into the pulmonary function host will not fall off during use, and at the same time, after use, the flow sensor can be smoothly pulled out from the host of the pulmonary function instrument. The clamping device is, for example, but not limited to, for example, the clamping device of the flow sensor is a claw 11 with a plum-shaped structure, which has a certain elastic opening and closing, and the connecting seat or the main body of the flow sensor is provided with a matching claw. component 102 . For another example, the clamping device is an elastic buckle with a button structure.

Embodiment 4 The calculation method of the internal cavity volume of the pressure hole column

式中p为流体中某点的压强，v为气流该点的流速，ρ为流体密度，g为重力加速度，h为该点所在高度，C是一个常量。对于气体，可忽略重力，将公式简化为公式Ⅰ:

气流的流速越大，压力越小。流量与流速满足公式Ⅱ：v＝Q/A，式中Q为流量，A为气流该点管子的截面积。气流流过呼气进气部和喉口部的流量相等，但截面积不相等，根据公式Ⅱ可得出流速也不相等，设进气部的截面积为A₁，流速为v₁，压强为p₁；喉口部的截面积为A₂，流速为v₂，压强为p₂。根据公式I，可推出压差

再用公式Ⅱ代入可得公式Ⅳ：

根据肺功能仪检测标准，检测流量峰值为14L/s，通过调节呼气进气部与喉口部的截面积，使呼气进气部与喉口部的压差峰值为10kPa。当没有气流流过流量传感器时，p₁、p₂都为标准大气压，当有气流流过流量传感器时，p₁、p₂会在10kPa范围内上下波动，标准大气压约为101kPa，因此取压口的压强变化范围为10％。According to Bernoulli's principle, fluid velocity and pressure satisfy the equation:

where p is the pressure at a certain point in the fluid, v is the flow velocity of the airflow at that point, ρ is the fluid density, g is the acceleration of gravity, h is the height of the point, and C is a constant. For gases, gravity can be ignored and the formula can be simplified to Equation I:

The higher the flow rate of the air flow, the lower the pressure. The flow rate and flow rate satisfy the formula II: v=Q/A, where Q is the flow rate, and A is the cross-sectional area of the pipe at this point of the airflow. The flow rate of the air flowing through the exhalation intake part and the throat part is equal, but the cross-sectional area is not equal. According to formula II, it can be concluded that the flow velocity is not equal. Let the cross-sectional area of the air intake part be A ₁ , the flow velocity is v ₁ , and the pressure is p ₁ ; the cross-sectional area of the throat is A ₂ , the flow velocity is v ₂ , and the pressure is p ₂ . According to formula I, the differential pressure can be derived

Substitute formula II into formula IV again:

According to the detection standard of spirometer, the peak value of the detected flow rate is 14L/s. By adjusting the cross-sectional area of the expiratory intake part and the throat part, the peak pressure difference between the exhalation intake part and the throat part is 10kPa. When there is no air flow through the flow sensor, p ₁ and p ₂ are standard atmospheric pressure. When there is air flow through the flow sensor, p ₁ and p ₂ will fluctuate up and down within the range of 10kPa. The standard atmospheric pressure is about 101kPa, so take the pressure The pressure of the ports varies by 10%.

According to the ideal gas state equation and Boyle's law, at a certain temperature, the volume of the quantitative gas is inversely proportional to the pressure of the gas, which satisfies the formula III: PV=C, where P is the pressure of the gas, V is the volume of the gas, and set The inner volume of the pressure-taking hole column is V ₁ , and the gas volume in the pressure-guiding tube is V ₂ . According to formula III, it can be inferred that P is inversely proportional to (V ₁ +V ₂ ), and if P decreases by 10%, then (V ₁ +V ₂ ) becomes larger by 10%; on the contrary, if P increases by 10%, (V ₁ +V ₂ ) becomes smaller by 10%, and the change in volume (V ₁ +V ₂ ) will cause the air column to fluctuate up and down, as long as V ₁ >10 %(V ₁ +V ₂ ), the airflow passing through the flow sensor will only be partially pressed into the pressure-taking hole column, but will not enter the pressure-guiding tube. Since the flow sensor is one-time use, the air in the pressure-taking hole column of the flow sensor can be isolated, so that the breath exhaled by the subject cannot contact the connection seat or the pressure guiding tube, so the connection seat and the pressure guiding tube are reused. No exposure to subject gas is possible, avoiding cross-contamination.

Example 5 Comparative test of preventing cross infection

The two types of disposable flow sensors 10, the connection seat and the differential pressure sensor are sterilized and connected as shown in Figure 2 (experimental group 1) and Figure 5 (experimental group 2), and then connected to the atomizer 401 through the T-shaped tube 400 Connect to 3L calibration cartridge 402, as shown in FIG. 8 . Use 0.9% normal saline to prepare 5ml of standard bacterial strain suspension of 5×10 ⁸ cfu/ml, turn on the nebulizer to generate bacterial aerosol mist particles, and then simulate the human body’s forced exhalation through a 3L calibration cylinder to remove the bacterial aerosol. The mist particles and air were mixed and pushed into the flow sensor, and exhaled continuously for 5 times. Finally, the disposable flow sensor was pulled out, and the connecting seat and the pressure guiding tube were separated. For the specific comparative experimental steps, please refer to "Research and Development of Special Respiratory Filters for Pulmonary Function Testing" (2003 Master's Thesis, Guangzhou Medical College, May 2006).

Table 1: Sterility test results for experimental group 1

Table 2: Sterility test results for experimental group 2

The experimental results are shown in Table 1 and Table 2. As a result, the flow sensor of the present invention can ensure that the connecting seat and pressure guiding tube connected to it still meet the sterile standard after the pulmonary function test is completed.

Claims (8)

1. A spirometer that can prevent cross-infection, including a flow sensor and a spirometer host. The flow sensor and the spirometer host are detachably assembled together. The flow sensor is a hollow tube structure, including the main ventilation tube and The pressure-taking hole located on the wall of the main vent pipe, the outer wall of the main vent pipe is provided with a pressure-taking hole column that communicates with the pressure-taking hole gas, and it is characterized in that the volume size of the cavity inside the pressure-taking hole column satisfies the following conditions : The volume of the internal cavity of the pressure-taking hole column satisfies the following conditions, V ₁ >K(V ₁ +V ₂ ), V ₁ is the inner volume of the pressure-taking hole column, and V ₂ is the volume in the pressure-guiding tube connected to the pressure-taking hole column Gas volume; the K value is calculated by comparing the K value with the atmospheric pressure according to formula IV and Δp, where formula IV:

, where Δp is the pressure difference between the exhalation air inlet and the throat, ρ is the fluid density, Q is the flow rate, A ₁ is the cross-sectional area of the air intake, and A ₂ is the cross-sectional area of the throat. By adjusting A ₁ with A ₂ to obtain Δp; the K value is 10%. 2. The spirometer according to claim 1, wherein the main ventilation pipe comprises an exhalation and air intake part, a first cone part, a throat part and a second cone part which are connected in sequence, and the throat part is A low-pressure pressure-taking hole is opened on the pipe wall and communicated with the low-pressure pressure-taking hole column, and a first high-pressure pressure-taking hole is opened on the pipe wall of the exhalation air intake part and communicated with the first high-pressure pressure-taking hole column. The column is connected with the positive pressure end of the differential pressure sensor through the pressure guiding tube, and the low pressure pressure taking hole column is connected with the negative pressure end of the differential pressure sensor through the pressure guiding tube. 3. The pulmonary function instrument according to claim 2, wherein the second high pressure pressure taking hole is opened on the tube wall of the second taper part and communicated with the second high pressure pressure taking hole post, and the second high pressure pressure taking hole The column is connected to the positive pressure end of the differential pressure sensor. 4. The spirometer according to claim 1, wherein the exhalation air intake part and the throat part are cylindrical, the diameter of the exhalation air intake part is larger than the diameter of the throat part, and the first cone part and the first conical part are cylindrical. The biconical portion is in the shape of a truncated cone, and the smaller diameter ends of the first cone portion and the second cone portion face the throat portion respectively. 5 . The lung function tester according to claim 1 , wherein the outer wall of the cylinder of the pressure-taking hole is provided with a groove, and the sealing ring is assembled in the groove. 6 . 6. The lung function tester according to claim 1, further comprising a clamping device. 7 . The spirometer according to claim 1 , wherein the clamping device on the flow sensor is detachably connected to a pressure guiding tube connected to the differential pressure sensor on the spirometer through a connecting seat. 8 . 8 . The spirometer according to claim 6 , wherein the clamping device is a claws of a plum-shaped structure. 9 .

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