Turbine flowmeter, flow calculation method

Abstract

The application discloses a turbine flowmeter and a flow calculation method. The turbine flowmeter comprises a light emitter, a light receiver, a turbine and a processor. The turbine comprises a turbine shaft and turbine blades. The turbine shaft is made of transparent material. Only one of the turbine blades is made of opaque material, and the other turbine blades are made of transparent material. The number of the light emitter and the corresponding light receiver is two, three or four pairs. Each pair of the light emitter and the corresponding light receiver is arranged on a target area in alignment and the light path formed by the light emitter and the corresponding light receiver passes through the turbine shaft. Each pair of the light emitter and the corresponding light receiver is uniformly distributed on the target area. The corresponding light receiver of each light emitter is electrically connected to the processor. When the light path of the light emitter is blocked, the corresponding light receiver sends a pulse signal to the processor. The application can improve the accuracy and reliability of the turbine flowmeter in measuring flow.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of flow measurement, in particular to a turbine flowmeter and a flow calculation method. BACKGROUND

[0002] Due to the serious air pollution in China, the large number of smoking population and the population aging, chronic obstructive pulmonary disease (COPD) ranks third in the list of disease causes in China. COPD patients not only need hospital treatment but also need medical care. Generally speaking, the core component of a medical COPD health monitoring system is an exhalation collection device (i.e. a flowmeter). Among four types of flowmeters, i.e. thermal type, differential pressure type, ultrasonic type and turbine type, the turbine flowmeter has the advantages of low power consumption, high reliability and low cost, but the disadvantage is that the precision is not high enough.

[0003] The turbine flowmeter is a speed type flowmeter with temperature and pressure compensation functions. Its working principle is that the power of the flowing fluid drives the turbine blade to rotate, and the rotation speed is approximately proportional to the volume flow. The volume value of the fluid through the flowmeter is based on the turbine impeller rotation number. Usually, the turbine flowmeter adopts a pair of light-emitting and light-sensitive diodes. When the turbine rotates, it can be counted once every 180° rotation, and twice for one revolution of the turbine. However, when the turbine rotation angle is less than 180°, it cannot be detected, which will cause measurement error and result in low flow measurement precision. Therefore, it is very important to improve the flow measurement precision of the turbine flowmeter. SUMMARY

[0004] The technical problem to be solved by the present application is to provide a turbine flowmeter and a flow calculation method, which can improve the flow measurement precision and reliability of the turbine flowmeter.

[0005] To solve the above technical problems, the present application discloses a turbine flowmeter in the first aspect, which comprises a light emitter, a light receiver, a turbine and a processor, the turbine comprising a turbine shaft and turbine blades; wherein,

[0006] The turbine shaft is made of transparent material;

[0007] Only one of the turbine blades is made of opaque material, and the others are made of transparent material;

[0008] The number of the light emitting devices and the corresponding light receiving devices is 2, 3 or 4 pairs, each pair of the light emitting device and the corresponding light receiving device is arranged on the target area in alignment with each other and the light path formed by the two devices passes through the turbine shaft, and each pair of the light emitting device and the corresponding light receiving device is uniformly distributed on the target area, wherein the target area is an inner wall area of the turbine flow meter, the inner wall area is in a circular ring shape, the axis of the turbine shaft passes through the center of the circular ring shape, and the circular ring shape is located in the radial direction of the axis of the turbine shaft.

[0009] The corresponding light receiving device of each light emitting device is electrically connected with the processor; and each time the light path corresponding to the light emitting device is blocked, the light receiving device sends a pulse signal to the processor.

[0010] As an optional implementation, in the first aspect of the present application, the turbine flow meter further comprises a light shielding plate, which is arranged on both sides of the light emitting device adjacent to other light emitting devices or light receiving devices, for shielding the light emitted by the light emitting device to both sides.

[0011] As an optional implementation, in the first aspect of the present application, the radius of the circular ring of the target area is less than 1.5 times the turbine rotation radius, and the turbine rotation radius is the maximum radius of the rotation area on the vertical plane of the turbine shaft when the turbine rotates.

[0012] As an optional implementation, in the first aspect of the present application, each light emitting device is electrically connected with the processor.

[0013] As an optional implementation, in the first aspect of the present application, the pulse signal sent by the light receiving device is in a TTL mode.

[0014] The second aspect of the present application discloses a flow calculation method, which is based on the turbine flow meter of the first aspect of the present application, and the method comprises:

[0015] Each time the pulse signal is received, the processor records the receiving time of the pulse signal and the corresponding light receiving device of the pulse signal as the recording information of the pulse signal.

[0016] The processor determines the rotation direction of the turbine and the number of rotations of the turbine according to the recording information of all the received pulse signals, and determines the product of the number of rotations of the turbine and the single-turn flow value of the turbine as the flow value of the measured fluid flowing through the turbine; the single-turn flow value of the turbine is the flow value of the fluid passing through the turbine when the turbine rotates one turn.

[0017] As an optional implementation, in the second aspect of the present application, the processor determines the rotating direction of the turbine and the rotating number of the turbine according to the record information of all the received pulse signals, including:

[0018] The processor obtains the light receivers corresponding to the last two pulse signals according to the record information of all the received pulse signals, determines the two light paths blocked by the turbine and the order of blocking the two light paths according to the light receivers corresponding to the two pulse signals, and judges whether the order of blocking the two light paths is consistent with the preset blocking order; when the judgment is consistent, the rotating direction of the turbine is determined as clockwise; when the judgment is inconsistent, the rotating direction of the turbine is determined as counterclockwise.

[0019] The processor calculates the rotating number of the turbine according to the following formula:

[0020] N=A / (2B+1),

[0021] Wherein, N is the rotating number of the turbine, A is the number of all the received pulse signals, and B is the logarithm of all the light emitters and the light receivers corresponding to the light emitters.

[0022] As an optional implementation, in the second aspect of the present application, the processor determines the rotating direction of the turbine and the rotating number of the turbine according to the record information of all the received pulse signals, including:

[0023] The processor screens the pulse signals received since the turbine rotates the second round from all the received pulse signals, and determines the rotating direction of the turbine and the rotating number of the turbine according to the record information of the pulse signals received since the turbine rotates the second round.

[0024] As an optional implementation, in the second aspect of the present application, the processor determines the rotating direction of the turbine and the rotating number of the turbine according to the record information of all the received pulse signals, including:

[0025] The processor screens the pulse signals received within 6s since the turbine rotates from all the received pulse signals, and determines the rotating direction of the turbine and the rotating number of the turbine according to the record information of the pulse signals received within 6s since the turbine rotates.

[0026] Compared with the prior art, the embodiment of the present application has the following beneficial effects:

[0027] The prior art counts only twice in one rotation, the measurement accuracy is 1 / 2 circle flow, and the measurement accuracy of the application can be 1 / 8 circle flow at least, and the accuracy is higher; meanwhile, the prior art cannot perform detection work when a pair of light emitters and light receivers fails, and great troubles will be caused in some special application scenarios, for example, medical monitoring of slow obstructive pulmonary patients needs to monitor the breathing condition of the patients, and the application can still work in such a scenario, and the reliability of the turbine flowmeter is improved. It can be seen that the embodiment of the application can improve the accuracy and reliability of the turbine flowmeter in measuring flow. BRIEF DESCRIPTION OF DRAWINGS

[0028] In order to more clearly illustrate the technical solutions in the embodiments of the application, the drawings needed to be used in the embodiments will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the application, and other drawings can be obtained by those skilled in the art without creative labor.

[0029] Figure 1 is a structural schematic diagram of a turbine flowmeter disclosed by the embodiment of the application;

[0030] Figure 2 is a flowchart of a flow calculation method disclosed by the embodiment of the application. DETAILED DESCRIPTION

[0031] In order to enable the persons skilled in the art to better understand the application scheme, the technical solutions in the embodiments of the application will be clearly and completely described in the following with reference to the drawings of the embodiments of the application. Obviously, the described embodiments are only some of the embodiments of the application, but not all the embodiments. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative labor are within the protection scope of the application.

[0032] Embodiment one

[0033] Referring to Figure 1 , Figure 1 is a structural schematic diagram of a turbine flowmeter disclosed by the embodiment of the application. The turbine flowmeter comprises a light emitter 1, a light receiver 2, a turbine and a processor, the turbine comprises a turbine shaft 5 and turbine blades 4; wherein,

[0034] The turbine shaft 5 is made of transparent material; only one blade 3 in the turbine blades 4 is made of opaque material, and the other blades are made of transparent material;

[0035] The number of the light emitting device 1 and the light receiving device 2 corresponding to the light emitting device 1 is 2, 3 or 4 pairs, each pair of the light emitting device 1 and the corresponding light receiving device 2 is arranged on the target area in alignment with each other and the light path formed by the two passes through the turbine shaft 5, each pair of the light emitting device 1 and the corresponding light receiving device 2 is uniformly distributed on the target area, wherein the target area is an inner wall area of the turbine flowmeter, the inner wall area is a circular ring shape, the axis of the turbine shaft 5 passes through the center of the circular ring shape, and the circular ring shape is located in the radial direction of the axis of the turbine shaft 5.

[0036] Each light receiving device 2 corresponding to the light emitting device 1 is electrically connected with the processor; each time the light path corresponding to the light emitting device is blocked, the light receiving device sends a pulse signal to the processor.

[0037] In the embodiment of the application, the transparent material can be an optical transparent material with a refractive index of 1.0-1.7.

[0038] In the embodiment of the application, the light receiving device 2 can only receive light propagated from a certain area, for example, as shown in the figure, the light receiving device 2 can only receive light propagated from an area with the center of the turbine shaft 5 as the center and the line between the center of the light receiving device 2 and the center of the turbine shaft 5 as the reference radius, and the reference radius rotates 20° clockwise and 20° counterclockwise. Figure 1

[0039] In the embodiment of the application, the light emitting device 1 can be an infrared light emitting diode, the corresponding light receiving device 2 can be an infrared light sensitive diode, and the corresponding transparent material can be an infrared transmitting material. Infrared rays have strong penetrating ability and can penetrate thick smoke and thick fog. Since human respiration generally contains water vapor, infrared rays are very suitable for measuring human respiratory flow.

[0040] For example, as shown in the figure, Figure 1 Figure 1 ​​There are four pairs of light emitters and light receivers, light emitters 1 include A1, A2, A3 and A4, and light receivers 2 include B1, B2, B3 and B4. Assuming that light receiver B1 is the starting counting point, when the rotation angle of the turbine exceeds 45°, it can be counted once, and one rotation can be counted 8 times. The order of the pulse signals corresponding to the light receivers received by the processor when rotating one circle is B1-B2-B4-B3-B1-B2-B4-B3. When one or more pairs of light emitters and light receivers are closed, for example, B2-A2 is closed, assuming that light receiver B1 is the starting counting point, when the rotation angle of the turbine exceeds 60°, it can be counted once, and one rotation can be counted 6 times. The order of the pulse signals corresponding to the light receivers received by the processor when rotating one circle is B1-B4-B3-B1-B4-B3, and it can still work. The prior art counts only twice in one rotation, and the measurement accuracy is 1 / 2 circle flow, while the measurement accuracy of the present application can be 1 / 8 circle flow, and the accuracy is higher. At the same time, the prior art cannot detect when one pair of light emitters and light receivers fails, which can cause great inconvenience in some special application scenarios, for example, medical monitoring of patients with slow obstructive pulmonary disease needs to monitor the breathing of patients, and the present application can still work in such scenarios, improving the reliability of the turbine flowmeter. It can be seen that the embodiment of the present application can improve the accuracy and reliability of the turbine flowmeter in measuring flow.

[0041] In an optional embodiment, the turbine flowmeter further comprises a light shielding plate 6 arranged on both sides of the light emitter adjacent to other light emitters or light receivers, for shielding the light emitted by the light emitter to both sides.

[0042] For example, as shown in Figure 1 The light shielding plate 6 is arranged on both sides of the light emitter A4, which can block the side light emitted by A4 to the light receivers B2 and B3, thereby reducing the interference of side light and improving the accuracy of the timing of the pulse signal emitted by the light receiver.

[0043] In another optional embodiment, the radius of the target area is less than 1.5 times the radius of the turbine rotation, and the radius of the turbine rotation is the maximum radius of the rotation area on the vertical plane of the turbine shaft when the turbine rotates.

[0044] In another optional embodiment, each light emitter is electrically connected to the processor.

[0045] In this optional embodiment, the processor controls the switching of the light emitter through the IO port or other interfaces that can output high and low levels, and can start or close any pair of light emitter-light receiver according to needs.

[0046] In another optional embodiment, the light receiver sends the pulse signal in TTL mode.

[0047] Embodiment Two

[0048] Referring to Figure 2 , Figure 2 A flow chart of a flow calculation method disclosed in an embodiment of the present application. The flow calculation method is based on the turbine flow meter described in Embodiment One. The method comprises:

[0049] 101. The processor records the receiving time of each pulse signal and the light receiver corresponding to the pulse signal as the record information of the pulse signal.

[0050] 102. The processor determines the rotation direction of the turbine and the rotation number of the turbine according to the record information of all the received pulse signals, and determines the product of the rotation number of the turbine and the single-turn flow value of the turbine as the flow value of the measured fluid flowing through the turbine.

[0051] In the embodiment of the present application, the single-turn flow value of the turbine is the flow of the fluid passing through the turbine when the turbine rotates one turn.

[0052] The embodiment of the present application can determine the rotation direction and the flow value during the rotation of the turbine according to the pulse data of all the light receivers.

[0053] In an optional embodiment, the processor determines the rotation direction of the turbine and the rotation number of the turbine according to the record information of all the received pulse signals, comprising:

[0054] The processor obtains the light receivers corresponding to the last two pulse signals according to the record information of all the received pulse signals, determines the two light paths blocked by the turbine and the order of blocking the two light paths according to the light receivers corresponding to the two pulse signals, and judges whether the order of blocking the two light paths conforms to the preset blocking order; when the judgment is that it conforms, the rotation direction of the turbine is determined as clockwise; when the judgment is that it does not conform, the rotation direction of the turbine is determined as counterclockwise.

[0055] The processor calculates the rotation number of the turbine according to the following formula:

[0056] N=A / (2B+1),

[0057] Wherein, N is the rotation number of the turbine, A is the number of all the received pulse signals, and B is the logarithm of all the light emitters and the light receivers corresponding to the light emitters.

[0058] In the optional embodiment, the preset blocking order is the order of blocking the light paths when the turbine rotates clockwise, for example, Figure 1 For example, Figure 1There are four pairs of light emitters-receivers working normally, and there are A1-B1 (1st path), A2-B2 (2nd path), A3-B3 (3rd path), and A4-B4 (4th path) four light paths, and the preset shielding sequence is 1st path-2nd path-4th path-3rd path-1st path. If the light paths recently shielded by the turbine are the 3rd path and the 1st path, the preset shielding sequence is met, and the turbine rotation direction is clockwise; if the light paths recently shielded by the turbine are the 1st path and the 3rd path, the preset shielding sequence is not met, and the turbine rotation direction is counterclockwise.

[0059] In the optional embodiment, for the rotation number calculation formula, for example, there are four pairs of light emitters-receivers working, and it is assumed that the processor receives 9 pulse signals, and the corresponding light receivers are B1, B2, B4, B3, B1, B2, B4, B3, and B1 respectively. Then A is 9, B is 4, and the rotation number calculation formula can be obtained N = 1, that is, 1 rotation. Figure 1

[0060] In another optional embodiment, the processor determines the rotation direction of the turbine and the rotation number of the turbine according to the record information of all received pulse signals, including:

[0061] The processor filters out the pulse signals received since the turbine rotates the second rotation from all received pulse signals, and determines the rotation direction of the turbine and the rotation number of the turbine according to the record information of the pulse signals received since the turbine rotates the second rotation.

[0062] In the optional embodiment, since there is static friction of the turbine when the turbine flowmeter starts, the flow y and the rotation number N do not have a proportional relationship at this time. Therefore, in order to ensure the accuracy of the flow calculation result, the turbine rotation number is counted after the turbine rotates more than 1 rotation after starting, which can reduce the non-linear error caused by the static friction of the turbine at the start, and improve the accuracy of the flow calculation result.

[0063] In another optional embodiment, the processor determines the rotation direction of the turbine and the rotation number of the turbine according to the record information of all received pulse signals, including:

[0064] The processor filters out the pulse signals received within 6s of the turbine rotation from all received pulse signals, and determines the rotation direction of the turbine and the rotation number of the turbine according to the record information of the pulse signals received within 6s of the turbine rotation.

[0065] ​In the alternative embodiment, in the monitoring of slow obstructive lung, the exhalation test requires the subject to exhale for 6s, after the exhalation, due to the rotational inertia, the turbine does not stop rotating immediately, if the system continues to count at this time, it will lead to inaccurate test. Therefore, the turbine rotation after 6s is not counted into the pulse number, which can reduce the error caused by rotational inertia and improve the accuracy of the flow calculation result.

[0066] Embodiment three

[0067] The embodiment of the present application provides another flow calculation method based on the turbine flow meter described in embodiment one, the method comprises:

[0068] 201, calculate the regression coefficients β0, β1, β2, β3, β4.

[0069] 202, calculate the flow according to the following formula:

[0070] y=β0+β1×N1+β2×N2+β3×N3+β4×N4+ξ,

[0071] Wherein, β0, β1, β2, β3, β4 are regression coefficients, and ξ is a random variable, that is, a random error. ξ, y conforms to normal distribution.

[0072] Taking FIG. 1 as an example, assuming that N1, N2, N3, N4 are the cumulative number of pulse signals corresponding to 4 pairs of light emitters-light receivers, since the total number of pulse signals N in the turbine flow meter is proportional to the flow y, it can be assumed that:

[0073] y=β0+β1×N1+β2×N2+β3×N3+β4×N4+ξ,

[0074] Wherein, β0, β1, β2, β3, β4 are regression coefficients, and ξ is a random variable, that is, a random error. ξ, y conforms to normal distribution, and σ is the standard deviation: ξ~N(0,σ 2 ),

[0075] y~N(β0+β1×N 11 +β2×N 12 +β3×N 13 +β4×N 14 ,σ 2 ),

[0076] In order to estimate the regression coefficients β i (i=0, 1, 2, 3, 4), the system independently observes n groups of data:

[0077]

[0078] Using the least square estimation of parameters, the error square sum R is required to be minimum, and the parameters β0, β1, β2, β3 and β4 are estimated as follows:

[0079]

[0080] The partial derivative of R=R(β0, β1, β2, β3, β4) is obtained as follows:

[0081]

[0082] Y, N and β are the coefficient matrix in formula (7). Let

[0083]

[0084]

[0085] Supposing that the coefficient matrix is full rank, the matrix equation in formula (7) is solved, and the optimal estimation of the coefficient β is obtained as follows: i

[0086] β=(N T ×N) -1 ×N T ×Y (8)

[0087] According to formula (8), the regression coefficients β0, β1, β2, β3 and β4 can be calculated, wherein the matrix Y and the matrix N can be obtained by collecting data in advance. The method based on the optimal estimation of parameters can obtain the accurate value of the regression coefficients, and further improve the accuracy of the flow value calculated according to the regression coefficients.

[0088] The embodiments of the present application only disclose the preferred embodiments of the present application, and are used for describing the technical solutions of the present application, but not for limiting the present application. Although the present application is described in detail with reference to the foregoing embodiments, those skilled in the art should understand that the technical solutions recorded in the foregoing embodiments can be modified, or some technical features can be replaced equivalently. The modification or replacement does not make the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.​

Claims

1. A turbine flow meter, comprising a light emitter, a light receiver, a turbine, and a processor, wherein the turbine comprises a turbine shaft and turbine blades; characterized in that, The turbine shaft is made of a transparent material; Only one of the turbine blades is made of an opaque material, while the other blades are made of a transparent material. The number of the light emitters and the corresponding light receivers is 2, 3 or 4 pairs. Each pair of light emitters and their corresponding light receivers are aligned with each other on the target area and the light path formed by them passes through the turbine shaft. Each pair of light emitters and their corresponding light receivers are evenly distributed on the target area. The target area is the inner wall area of ​​the turbine flow meter. The inner wall area is annular in shape. The axis of the turbine shaft passes through the center of the annular shape and the annular shape is located in the radial direction of the axis of the turbine shaft. Each of the light emitters has a corresponding light receiver electrically connected to the processor; whenever the light path corresponding to the light emitter is blocked, the light receiver sends a pulse signal to the processor. The turbine flow meter also includes a light shield, which is disposed on both sides of the emitter adjacent to other emitters or receivers, for blocking the light emitted by the emitter to both sides. The radius of the annular region of the target area is less than 1.5 times the turbine rotation radius, where the turbine rotation radius is the maximum radius of the rotation area on the vertical plane of the turbine shaft when the turbine rotates. Each of the light emitters is electrically connected to the processor; The receiver transmits pulse signals in TTL mode.

2. A flow calculation method, said flow calculation method being based on the turbine flow meter of claim 1, characterized in that, The method includes: Whenever the pulse signal is received, the processor records the reception time of the pulse signal and the receiver corresponding to the pulse signal as the recording information of the pulse signal; The processor determines the rotation direction and number of rotations of the turbine based on the recorded information of all received pulse signals, and determines the flow rate of the fluid being measured through the turbine by multiplying the number of rotations of the turbine by the flow rate per rotation of the turbine; the flow rate per rotation of the turbine is the flow rate of the fluid passing through the turbine when the turbine rotates once.

3. The flow calculation method according to claim 2, characterized in that, The processor determines the rotation direction and the number of rotations of the turbine based on the recorded information of all received pulse signals, including: The processor obtains the receivers corresponding to the last two pulse signals based on the recorded information of all received pulse signals, determines the two optical paths blocked by the turbine and the order in which the two optical paths are blocked based on the receivers corresponding to the two pulse signals, and determines whether the order in which the two optical paths are blocked conforms to a preset blocking order; if it does, the rotation direction of the turbine is determined to be clockwise; if it does not, the rotation direction of the turbine is determined to be counterclockwise. The processor calculates the number of revolutions of the turbine according to the following formula: N = A / (2B+1), Where N is the number of rotations of the turbine, A is the number of all received pulse signals, and B is the number of all the light emitters and the corresponding light receivers.

4. The flow calculation method according to claim 2, characterized in that, The processor determines the rotation direction and the number of rotations of the turbine based on the recorded information of all received pulse signals, including: The processor filters out the pulse signals received from all received pulse signals starting from the second rotation of the turbine, and determines the rotation direction and the number of rotations of the turbine based on the recorded information of the pulse signals received starting from the second rotation of the turbine.

5. The flow calculation method according to claim 2, characterized in that, The processor determines the rotation direction and the number of rotations of the turbine based on the recorded information of all received pulse signals, including: The processor filters out the pulse signals received within 6 seconds of the turbine's rotation from all received pulse signals, and determines the turbine's rotation direction and the number of rotations based on the recorded information of the pulse signals received within 6 seconds of the turbine's rotation.

Images