Constant speed sampling adjustment system based on automatic probe switching

Abstract

The present invention discloses an isokinetic sampling adjustment system based on automatic probe switching, comprising: a sensor for measuring the flow data in the sampling pipeline and the sampling probe; a controller for receiving the flow signal from the sensor and calculating the current isokinetic sampling ratio based thereon, and determining whether a sampling probe needs to be replaced according to the calculation result of the isokinetic sampling ratio; and an actuator for receiving and executing the sampling probe replacement instruction issued by the controller. Through the precise monitoring of the sensor, the intelligent judgment of the controller, and the automated operation of the actuator, the present invention can realize the automatic switching of the sampling probe, thereby effectively meeting the sampling requirements under different flow conditions and ensuring the isokinetic property and accuracy of the sampling process. The present invention can not only improve the experimental efficiency, but also significantly improve the reliability of the sampling results, and is an ideal solution for isokinetic sampling adjustment in a closed system.

Description

Technical Field

[0001] The present invention relates to the field of intelligent measuring instruments, and particularly to an isokinetic sampling adjustment system based on automatic probe switching. Background Art

[0002] With the accelerating trend of passenger vehicle electrification, the particulate emissions from motor vehicles have been continuously decreasing. However, at the same time, the proportion of particulate matter generated during braking in traffic pollutants has been gradually increasing. Some studies have shown that the PN (particulate number) emission level of braking particulate matter has even exceeded the PN emission limit for light-duty vehicles specified in China's National VI standard. Therefore, how to study and control the particulate matter generated during braking has become a current research hotspot.

[0003] Currently, the brake dynamometer method is the mainstream method for testing braking particulate matter. Its principle is to place the brake dynamometer in a relatively airtight test chamber, continuously purge the particulate matter generated during braking to the sampling pipeline through an external air flow, and then the sampling probe collects the particulate matter in the channel and sends it to related instruments for analysis. In the entire test device, the collection process of particulate matter is the key. However, since the flow rate inside the sampling probe is often inconsistent with the flow rate inside the sampling pipeline, it is easy to cause non-isokinetic sampling, which in turn affects the accuracy of the results. The existing adjustment methods are relatively cumbersome and require comprehensive consideration of factors such as the size of the sampling pipeline and the flow rate of the purge air flow. Isokinetic sampling is achieved by replacing the sampling probe with sampling probes of different sizes. However, since the sampling probe is embedded inside the sampling pipeline, replacement requires first disassembling the sampling pipeline, then replacing the sampling probe, and finally reconnecting the sampling pipeline. This process is not only complex but may also damage the sealing of the sampling system, thereby affecting the sampling results. Therefore, how to more conveniently replace the sampling nozzle under the premise of reducing the disturbance to the sampling system has become a technical problem to be solved urgently. Summary of the Invention

[0004] In order to solve one or more technical problems in the prior art, the present invention provides an isokinetic sampling adjustment system based on automatic probe switching.

[0005] The isokinetic sampling adjustment system based on automatic probe switching includes:

[0006] A sensor for measuring the flow data inside the sampling pipeline and the sampling probe;

[0007] A controller for receiving the flow signal from the sensor and calculating the current isokinetic sampling ratio based on it, and judging whether it is necessary to replace the sampling probe according to the calculation result of the isokinetic sampling ratio;

[0008] An actuator for receiving and executing the sampling probe replacement instruction issued by the controller.

[0009] Preferably, the actuator includes a motor which drives the turntable to retract and rotate through a transmission mechanism. A plurality of sampling probes with different inner diameter sizes are arranged on the turntable, and the sampling probes are replaceably connected to the front end of the sampling probe.

[0010] Preferably, the transmission mechanism includes a transmission rod. The front end of the transmission rod is connected to the middle of the turntable. The motor includes a first motor for driving the transmission rod to retract and a second motor for driving the transmission rod to rotate.

[0011] Preferably, a transmission gear is sleeved on the transmission rod. The transmission gear is meshed and connected with the driving gear of the second motor, and the second motor is fixed to the transmission rod through a motor bracket.

[0012] Preferably, the rear end of the transmission rod is connected to the rack of the feeding mechanism, and the driving gear of the first motor is meshed and connected with the rack.

[0013] Preferably, the sensor includes an ultrasonic flowmeter. When calculating the flow data in the sampling pipeline by using the ultrasonic flowmeter, the following steps are included:

[0014] S11. By measuring the Doppler frequency shift △f, the flow velocity v of the fluid is inversely deduced:

[0015]

[0016] In the formula, v is the calculated flow velocity of the fluid; △f is the frequency offset of the reflected wave; c is the propagation speed of the sound wave in the fluid; f0 is the frequency of the sound wave emitted by the ultrasonic transmitter; θ is the included angle between the propagation direction of the ultrasonic wave and the fluid flow direction;

[0017] S12. Calculate the flow in the sampling pipeline according to the flow velocity v of the fluid:

[0018] NQ = v·A

[0019] In the formula, NQ is the average standardized air flow rate in the sampling pipeline (Nm 3 / h), and A is the cross-sectional area of the pipeline (m 2 ).

[0020] Preferably, the controller calculates the isokinetic sampling ratio according to the following formula:

[0021]

[0022] In the formula, IR is the isokinetic sampling ratio; NQs is the average standardized air flow rate in the sampling probe (Nm 3 / h), set by the analyzer connected to the sampling probe, is a constant; di is the inner diameter (mm) of the sampling pipe, which is a fixed value; dn is the inner diameter (mm) of the sampling probe, which is an adjustable value.

[0023] Preferably, when IR > 1.15, the controller issues an instruction to replace the sampling probe with a larger inner diameter size; when IR < 0.9, the controller issues an instruction to replace the sampling probe with a smaller inner diameter size; when 0.9 ≤ IR ≤ 1.15, the controller does not issue an instruction.

[0024] Preferably, when it is necessary to switch the sampling probe, the inner diameter size dn of the sampling probe to be replaced is calculated according to the following formula:

[0025]

[0026] In the formula, when IR takes 0.9 and NQs / NQ takes the maximum adjustable value of the system, the calculated dn1 is the inner diameter size of the largest specification sampling probe; when IR takes 1.15 and NQs / NQ takes the minimum adjustable value of the system, the calculated dn2 is the inner diameter size of the smallest specification sampling probe.

[0027] According to the number of adjustable gears, multiple sampling probes of different specifications are arranged and distributed on the turntable within the inner diameter range of dn1 and dn2.

[0028] Preferably, the sampling probe is made of an electroplated and polished stainless steel pipe; further preferably, the inner diameter of the sampling probe is at least greater than 4 mm; further preferably, the inner hole length of the sampling probe is at least 10 mm and not less than the inner diameter size of the sampling probe; further preferably, the ratio of the outer diameter to the inner diameter at the inlet of the sampling probe is less than 1.1; further preferably, any change in the inner diameter of the sampling probe 3 changes at a tapered angle of less than 30°; further preferably, at the connection between the sampling probe 3 and the sampling probe 2, the axial direction of the inner hole of the sampling probe 3 is parallel to the axial direction of the inner hole of the sampling pipe of the sampling probe 2 to ensure that the suction angle ≤ 15°.

[0029] The beneficial effects of the present invention:

[0030] In the prior art, the method of replacing the sampling probe is very cumbersome. It is necessary to first disassemble the sampling pipeline, then replace the sampling probe, and finally reconnect the sampling pipeline. This process is not only complex but also may damage the sealing between the pipelines of the sampling system, thereby affecting the sampling results. The present invention proposes an isokinetic sampling adjustment system based on automatic probe switching, which can effectively shorten the time for replacing the sampling probe, improve the experimental efficiency, and eliminate the adverse effects on the sealing of the sampling device and the sampling accuracy during the disassembly and assembly of the sampling pipeline. This system is not only applicable to the measurement of vehicle emissions but also can be applied to the isokinetic sampling adjustment of various closed systems, featuring convenience and high efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation to the present invention.

[0032] Figure 1 is a top view of the mechanical structure according to an embodiment of the present invention;

[0033] Figure 2 is a three-dimensional Figure 1 ;

[0034] Figure 3 is Figure 2 an enlarged view of part A in

[0035] Figure 4 is Figure 2 an enlarged view of part B in

[0036] Figure 5 is a three-dimensional Figure 2 ;

[0037] Figure 6 is a flowchart of the system operation according to an embodiment of the present invention;

[0038] In the figure: 1, sampling pipeline; 2, sampling probe; 21, sampling probe support; 3, sampling probe head; 4, motor; 41, first motor; 42, second motor; 421, motor support; 5, transmission mechanism; 51, transmission rod; 52, transmission gear; 53, feed mechanism; 531, rack; 54, transmission rod support; 6, turntable; 61, through hole; 7, analyzer; 71, analyzer connecting pipe; 8, console. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0039] The present invention will be further described in detail below with reference to the embodiments. The following embodiments are explanations of the present invention and the present invention is not limited to the following embodiments.

[0040] Due to the relatively fixed size of the sampling channel while the purging gas flow changes in real time, it is difficult to precisely control the flow rates of the sampling probe and the sampling channel, which in turn leads to non-isokinetic sampling and affects the accuracy of experimental results. To solve this problem, the present invention effectively improves the non-isokinetic sampling phenomenon, enhances the sampling accuracy and experimental efficiency by real-time monitoring the flow signal and timely and dynamically adjusting the size of the sampling probe.

[0041] The following will describe in detail various embodiments according to the present invention with reference to the accompanying drawings.

[0042] As Figures 1-6 shown, the isokinetic sampling adjustment system based on automatic probe switching includes:

[0043] A sensor for measuring the flow data in the sampling pipeline 1 and the sampling probe 2; the sensor part is mainly composed of a flow sensor, and its task is to real-time monitor the flow data in the pipeline (including the sampling pipeline, the pipeline of the sampling probe, etc.) and feed these data back to the control system (including the controller); the flow data in the sampling probe 2 can be directly measured and read by the analyzer 7 (with a built-in flow sensor).

[0044] A controller for receiving the flow signal from the sensor and calculating the current isokinetic sampling ratio based on it, and judging whether to replace the sampling probe 3 according to the calculation result of the isokinetic sampling ratio; the controller part is preferably composed of a high-performance control computer. The controller is responsible for receiving the flow signal from the sensor and calculating the current isokinetic sampling ratio based on it; according to the calculation result, the controller will judge whether to replace the sampling probe 3 and send a corresponding instruction to start the replacement procedure; the controller plays a key decision-making role in the whole system to ensure that the sampling process always remains in the optimal state; in specific implementation, the replacement instruction signal transmitted by the controller to the actuator can be fully automatically transmitted according to the set program; or by setting up a control console 8, the operator manually manipulates the control console 8 according to the system prompt to transmit the replacement instruction signal to the actuator to achieve semi-automatic switching.

[0045] An actuator for receiving and executing the sampling probe 3 replacement instruction issued by the controller; the actuator part is composed of a transmission mechanism 5 driven by a motor 4; when the controller issues an instruction to replace the sampling probe 3, the actuator immediately responds, controls the motor 4 to operate, and drives the turntable 6 to retract and rotate through the transmission mechanism 5 to switch to the size of the sampling probe 3 suitable for the current flow rate. This process not only greatly simplifies the replacement operation process of the sampling probe 3, but also avoids the sealing problems that may be caused by manually replacing the sampling probe 3, improving the overall reliability and working efficiency of the sampling system. The turntable 6 with sampling probes 3 of different sizes is the core part of the actuator mechanical mechanism. Preferably, the sampling probes 3 of different sizes are fixed on the turntable 6 by bolts.

[0046] The mechanical structure part of the present invention will be described in detail below.

[0047] As Figures 1-5 shown, the actuator includes a motor 4. The motor 4 drives the turntable 6 to retract and rotate through a transmission mechanism 5. A plurality of sampling probes 3 with different inner diameter sizes are arranged on the turntable 6. The sampling probe 3 is replaceably connected to the front end of the sampling probe 2. Specifically in implementation, when the transmission mechanism 5 pushes the turntable 6 forward, the sampling probe 3 is separated from the front end of the sampling probe 2. At this time, the transmission mechanism 5 drives the turntable 6 to rotate, and the position replacement of the sampling probes 3 with different inner diameter specifications can be realized. After the position replacement of the sampling probe 3 is completed, the transmission mechanism 5 pulls the turntable 6 backward to realize the connection between the sampling probe 3 and the front end of the sampling probe 2. In specific design, the sampling probe 3 can be arranged on the outer edge of the driving turntable 6. This design can directly connect the sampling probe 3 to the front end of the sampling probe 2. Or, through holes 61 can also be arranged on the main body of the driving turntable 6. The sampling probe 3 is connected to the through holes 61, and the through holes 61 are sleeved on the front end of the sampling probe 2 to realize the connection between the sampling probe 3 and the sampling probe 2. The sleeving of the through holes 61 can further enhance the sealing effect at the connection between the sampling probe 3 and the sampling probe 2. More specifically, to improve the accuracy of the docking process between the sampling probe 2 and the sampling probe 3 and the stability of the connection state, the sampling probe 2 is fixed on the pipe wall of the sampling pipe 1 (for example, the sampling probe 2 and the sampling pipe 1 are fixed through the sampling probe bracket 21 shown in Figure 2 ), so that the position of the sampling probe 2 will not shift with operations such as the retraction of the turntable 6. In addition, at the connection between the sampling probe 2 and the sampling probe 3, the sampling probe 3 is designed as a gradually expanding pipe, and the front end of the sampling probe 2 is correspondingly designed as a cone to ensure accurate positioning during assembly and good sealing. Further, a fixing device is arranged on the sampling pipe 1 to be connected to the ground to minimize the vibration phenomenon caused by gas flow.

[0048] In a specific embodiment of the present invention, the transmission mechanism 5 includes a transmission rod 51. The front end of the transmission rod 51 is connected to the middle of the turntable 6. The motor 4 includes a first motor 41 for driving the transmission rod 51 to retract and a second motor 42 for driving the transmission rod 51 to rotate. In specific setting, the first motor 41 can also be replaced by a telescopic pump oil pump, an air pump, etc. The telescopic pump is controlled by a controller for telescoping.

[0049] In a specific embodiment of the present invention, a transmission gear 52 is sleeved on the transmission rod 51. The transmission gear 52 is meshed and connected with the driving gear of the second motor 42. The second motor 42 is fixed to the transmission rod 51 through a motor bracket 421. With such a setting, it can be realized that when the transmission rod 51 retracts, the second motor 42 and the transmission gear 52 maintain the meshed connection.

[0050] In a specific embodiment of the present invention, the rear end of the transmission rod 51 is connected to the rack 531 of the feeding mechanism 53, and the driving gear of the first motor 41 is meshed with the rack 531. During specific implementation, the first motor 41 drives the rack 531 to move forward or backward, and the rack 531 pushes the transmission rod 51 forward or pulls it backward. During specific design, the transmission mechanism 5 further includes a transmission rod bracket 54 for maintaining the stable movement of the transmission rod 51. A ring structure can be provided on the transmission rod bracket 54, and the ring structure is movably sleeved outside the transmission rod 51 to achieve the stable movement of the transmission rod 51 during retraction and rotation.

[0051] The system process part of the present invention will be described in detail below.

[0052] As Figures 1-6 shown, the sensor includes an ultrasonic flowmeter. Since the measurement process cannot interfere with the particulate matter in the pipeline, traditional mechanical flow sensors and thermal flow sensors are not suitable for this scenario. In contrast, the ultrasonic flowmeter is currently the most suitable choice. The ultrasonic flowmeter measures the flow rate by the change in the time or frequency of ultrasonic waves propagating in the fluid. When ultrasonic waves encounter particles or bubbles in the fluid, a frequency shift (i.e., the Doppler effect) occurs. By measuring this shift, the flow velocity of the fluid can be accurately determined, thereby obtaining accurate flow rate data.

[0053] When calculating the flow rate data in the sampling pipeline 1 using an ultrasonic flowmeter, the following steps are included:

[0054] S11. By measuring the Doppler frequency shift △f, the flow velocity v of the fluid is inversely deduced:

[0055]

[0056] In the formula, v is the calculated flow velocity of the fluid; △f is the frequency shift of the reflected wave; c is the propagation velocity of the sound wave in the fluid; f0 is the frequency of the sound wave emitted by the ultrasonic transmitter; θ is the angle between the propagation direction of the ultrasonic wave and the flow direction of the fluid; it should be noted that the propagation velocity c of the sound wave in the fluid depends on the temperature, density and other physical properties of the fluid; usually, the sound velocity needs to be corrected during the measurement process; the selection of the angle θ directly affects the measurement result, and usually, it is necessary to ensure that the measurement device is properly installed to obtain an accurate θ value; the Doppler method requires the presence of particles in the fluid that can reflect ultrasonic waves. If the particulate matter concentration is too low, it may lead to inaccurate measurement results;

[0057] S12. Calculate the flow rate in the sampling pipeline 1 according to the flow velocity v of the fluid:

[0058] NQ = v · A

[0059] In the formula, NQ is the average standardized air flow rate in the sampling pipeline (Nm 3 / h), where A is the cross-sectional area of the pipeline (m 2 ).

[0060] The flow sensor is installed upstream and / or downstream of the sampling probe 2, preferably on the straight section of the horizontal sampling pipeline 1, to ensure the stable flow of the fluid and reduce the influence of turbulence on the measurement. Further preferably, there is a straight section with a length of 10 times the diameter of the sampling pipeline 1 upstream of the flow sensor and a straight section with a length of 5 times the diameter of the sampling pipeline 1 downstream of the flow sensor.

[0061] In a specific embodiment of the present invention, the controller calculates the isokinetic sampling ratio according to the following formula:

[0062]

[0063] In the formula, IR is the isokinetic sampling ratio; NQs is the average standardized airflow rate in the sampling probe 2 (Nm 3 / h), which is set by the analyzer 7 connected to the sampling probe 2 and is a constant; di is the inner diameter of the sampling pipeline 1 (mm) and is a fixed value; dn is the inner diameter of the sampling probe 3 (mm) and is an adjustable value. NQs is the standardized airflow rate in the sampling probe 2, which is controlled by the sampling instrument connected to the rear end, i.e., the analyzer 7. Under different experimental conditions, NQs can be set to different constant values, and this constant value does not change during the same experiment. The same is true for the inner diameter of the sampling probe 2. During the same experiment, there is no need to replace the sampling probe 2, and sampling probes 2 with different inner diameters may be replaced according to different experimental conditions. During the same experiment, since NQs is a constant and di is a fixed value, in order to make IR approach 1, the operation performed is to replace the sampling probe 3 with a smaller dn when NQ becomes larger, and replace the sampling probe 3 with a larger dn when NQ becomes smaller.

[0064] When IR is equal to 1, it is isokinetic sampling. However, in actual situations, IR often shows a fluctuating and stable state. Therefore, values of the isokinetic sampling ratio close to 1 can all be considered as isokinetic sampling. Preferably, calculated values of the isokinetic ratio between 0.9 and 1.15 are considered as isokinetic sampling. The controller includes a control computer, which is responsible for processing the flow signal, calculating the isokinetic sampling ratio, and outputting an operation to replace the sampling nozzle according to the isokinetic sampling ratio.

[0065] In a specific embodiment of the present invention, when IR > 1.15, the controller issues an instruction to replace the sampling probe 3 with a larger inner diameter size; when IR < 0.9, the controller issues an instruction to replace the sampling probe 3 with a smaller inner diameter size; when 0.9 ≤ IR ≤ 1.15, the controller does not issue an instruction. After the instruction is issued, the signal to replace the sampling probe 3 can be automatically transmitted to the actuator through a set program, or the operator can be prompted by the system to manually control the controller to transmit the signal to replace the sampling probe 3 to the actuator.

[0066] In a specific embodiment of the present invention, when it is necessary to switch the sampling probe 3, the inner diameter dimension dn of the sampling probe 3 to be replaced is calculated according to the following formula:

[0067]

[0068] In the formula, when IR takes 0.9 and NQs / NQ takes the maximum value adjustable by the system, the calculated dn1 is the inner diameter dimension of the sampling probe 3 with the largest specification; when IR takes 1.15 and NQs / NQ takes the minimum value adjustable by the system, the calculated dn2 is the inner diameter dimension of the sampling probe 3 with the smallest specification;

[0069] According to the number of adjustable gears, within the inner diameter range of dn1 and dn2, multiple sampling probes 3 of different specifications are arranged on the turntable 6. During the measurement process, if it is still impossible to make 0.9 ≤ IR ≤ 1.15 after exhausting the switching of all specifications of the sampling probe 3, the controller is made to issue an alarm signal.

[0070] In a specific embodiment of the present invention, the design of the sampling probe 3 follows the following requirements:

[0071] (1) The sampling probe 3 is made of electroplated and polished stainless steel pipe (or equivalent / higher grade weather-resistant and high-precision materials) to achieve the ultra-high cleanliness and ultra-high precision surface that can be achieved in the prior art, thereby reducing the interference of dust accumulation and impurities on the sampling analysis;

[0072] (2) The inner diameter of the sampling probe 3 is at least greater than 4 mm, and the inner hole length of the sampling probe 3 (from the tip of the sampling port of the sampling probe 3 to the tail end of the sampling probe 3) is at least 10 mm and not less than the inner diameter dimension of the sampling probe 3;

[0073] (3) The wall thickness at the edge of the sampling port of the sampling probe 3 is as thin as possible to minimize the interference to the flow; preferably, the ratio of the outer diameter to the inner diameter at the edge of the sampling port (the entrance of the sampling probe 3) is less than 1.1;

[0074] (4) Any change in the inner diameter of the sampling probe 3 changes at a conical angle less than 30°, and its axis should be parallel to the sampling pipe 1 to ensure that the suction angle ≤ 15°; the sampling port of the sampling probe 3 is the entrance of the air flow into the sampling tube of the sampling probe 2. The size (inner diameter) of the sampling port of the sampling probe 3 is designed to have a conical transition during design. A conical angle less than 30° can ensure that the air flow remains stable when entering the sampling tube of the sampling probe 2 and will not be suddenly blocked or generate turbulence; the suction angle is the angle between the air flow direction and the axis of the sampling tube of the sampling probe 2 when the air flow enters the sampling tube of the sampling probe 2; ensuring that the suction angle ≤ 15° can ensure that the air flow enters the sampling system of the sampling probe 2 in a nearly parallel state and reduce the flow interference.

[0075] After completing the above design, the turntable 6 is installed at the front end of the transmission rod 51. During the experiment, the flow rate in the sampling pipeline 1 and the flow signal at the sampling probe 2 are fed back to the control computer of the controller to calculate the isokinetic sampling ratio. When the isokinetic sampling ratio is too small, the control computer of the controller instructs the first motor 41 to drive the transmission mechanism 5 to start feeding, pushing the turntable 6 to move axially along the transmission rod 51, so that the sampling probe 3 is separated from the sampling probe 2. Then, the second motor 42 drives the transmission rod 51 to rotate the turntable 6, switches to the sampling probe 3 with a larger inner diameter, and after adjustment, the transmission mechanism 5 pulls the turntable 6 back to connect the new sampling probe 3 with the sampling probe 2. If the sampling ratio is too large, the system performs the opposite operation: the turntable 6 rotates to the position of the sampling probe 3 with a smaller inner diameter and reconnects. Through these automatic adjustments, it is ensured that the sampling probe 3 can automatically switch with the change of the flow rate, simplifying the replacement process and improving the experimental efficiency and the accuracy of switching.

[0076] In summary, through the precise monitoring of sensors, the intelligent judgment of the controller, and the automated operation of the actuator, the present invention can achieve the automatic switching of the sampling probe, thereby effectively meeting the sampling requirements under different flow conditions and ensuring the isokinetic property and accuracy of the sampling process. The present invention can not only improve the experimental efficiency but also significantly improve the reliability of the sampling results, and is an ideal solution for isokinetic sampling adjustment in a closed system.

[0077] It should be noted that the terms used in the present invention are only for describing specific embodiments and do not limit the scope of the present invention. As shown in the specification of the present invention, unless the context clearly indicates otherwise, words such as "a", "an", "one" and / or "the" are not specifically singular and may also include the plural. The term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method or device including a series of elements not only includes those elements but also includes other elements not expressly listed, or further includes elements inherent to such a process, method or device. Without further limitation, an element defined by the statement "including a..." does not exclude the existence of additional identical elements in the process, method or device including the said element.

[0078] It should also be noted that the orientation or positional relationship indicated by terms such as "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation to the present invention. Unless otherwise clearly specified and defined, terms such as "installed", "connected", "coupled" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection; it can be directly connected, or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0079] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the technical solutions of the embodiments of the present invention.

[0080] In addition, it should be noted that for the specific embodiments described in this specification, the shapes, names of the components, etc. can be different. Any equivalent or simple changes made according to the structure, features and principles described in the inventive concept of the present invention are included in the protection scope of the present invention. Those skilled in the art to which the present invention pertains can make various modifications or supplements to the described specific embodiments or use similar methods for substitution, as long as they do not deviate from the structure of the present invention or exceed the scope defined by the claims, they should fall within the protection scope of the present invention.

Claims

1. An isokinetic sampling adjustment system based on automatic probe switching, characterized in that Comprising: A sensor for measuring the flow data in the sampling pipeline (1) and the sampling probe (2); A controller for receiving the flow signal from the sensor and calculating the current isokinetic sampling ratio based thereon, and judging whether the sampling probe (3) needs to be replaced according to the calculation result of the isokinetic sampling ratio; An actuator for receiving and executing the sampling probe (3) replacement instruction issued by the controller; The actuator includes a motor (4), the motor (4) drives the turntable (6) to retract and rotate through a transmission mechanism (5), and a plurality of sampling probes (3) with different inner diameter sizes are arranged on the turntable (6), and the sampling probe (3) is replaceably connected to the front end of the sampling probe (2); The transmission mechanism (5) includes a transmission rod (51), the front end of the transmission rod (51) is connected to the middle of the turntable (6), and the motor (4) includes a first motor (41) for driving the transmission rod (51) to retract and a second motor (42) for driving the transmission rod (51) to rotate; The transmission rod (51) is sleeved with a transmission gear (52), the transmission gear (52) is meshed and connected with the driving gear of the second motor (42), and the second motor (42) is fixed to the transmission rod (51) through a motor bracket (421); The rear end of the transmission rod (51) is connected to the rack (531) of the feeding mechanism (53), and the driving gear of the first motor (41) is meshed and connected with the rack (531).

2. The isokinetic sampling adjustment system according to claim 1, characterized in that, The sensor includes an ultrasonic flowmeter. When calculating the flow data in the sampling pipeline (1) by using the ultrasonic flowmeter, the following steps are included: S11. By measuring the Doppler frequency shift △f, the flow velocity v of the fluid is inversely deduced: In the formula, v is the calculated flow velocity of the fluid; △f is the frequency offset of the reflected wave; c is the propagation velocity of the sound wave in the fluid; f0 is the frequency of the sound wave emitted by the ultrasonic transmitter; θ is the included angle between the propagation direction of the ultrasonic wave and the fluid flow direction; S12. Calculate the flow rate in the sampling pipeline (1) according to the flow velocity v of the fluid: NQ = v·A Wherein, NQ is the average standardized air flow rate in the sampling pipeline (Nm 3 / h), and A is the cross-sectional area of the pipeline (m 2 ).

3. The isokinetic sampling adjustment system according to claim 2, wherein, The controller calculates the isokinetic sampling ratio according to the following formula: wherein, IR is the isokinetic sampling ratio; NQs is the average standardized airflow rate (Nm 3 / h) in the sampling probe (2), which is set by an analyzer (7) connected to the sampling probe (2) and is a constant; di is the inner diameter (mm) of the sampling pipe (1), which is a fixed value; dn is the inner diameter (mm) of the sampling probe (3), which is an adjustable value.

4. The isokinetic sampling and adjustment system according to claim 3, wherein, When IR > 1.15, the controller issues an instruction to replace the sampling probe (3) with a larger inner diameter size; when IR < 0.9, the controller issues an instruction to replace the sampling probe (3) with a smaller inner diameter size; when 0.9 ≤ IR ≤ 1.15, the controller does not issue an instruction.

5. The isokinetic sampling adjustment system according to claim 4, characterized in that, The inner diameter size dn of the sampling probe (3) on the turntable 6 is calculated according to the following formula: In the formula, when IR takes 0.9 and NQs / NQ takes the maximum adjustable value of the system, the calculated dn1 is the inner diameter size of the largest specification sampling probe (3); when IR takes 1.15 and NQs / NQ takes the minimum adjustable value of the system, the calculated dn2 is the inner diameter size of the smallest specification sampling probe (3); According to the number of adjustable gears, a plurality of sampling probes (3) with different specifications are arranged on the turntable (6) within the inner diameter range of dn1 and dn2.

6. The isokinetic sampling adjustment system according to claim 5, wherein The sampling probe (3) is made of an electroplated and polished stainless steel pipe.

7. The isokinetic sampling adjustment system according to claim 5, characterized in that, The inner diameter of the sampling probe (3) is at least greater than 4 mm.

8. The isokinetic sampling adjustment system according to claim 5, characterized in that, The length of the inner hole of the sampling probe (3) is at least 10 mm and not less than the inner diameter dimension of the sampling probe (3).

9. The isokinetic sampling adjustment system according to claim 5, characterized in that, The ratio of the outer diameter to the inner diameter at the inlet of the sampling probe (3) is less than 1.

1.

10. The isokinetic sampling adjustment system according to claim 5, characterized in that, The inner diameter of the sampling probe (3) changes at a conical angle of less than 30°.

11. The isokinetic sampling adjustment system according to claim 5, wherein Any change in the inner diameter of the sampling probe (3) changes at a conical angle of less than 30°.

12. The isokinetic sampling adjustment system according to claim 5, wherein At the connection between the sampling probe (3) and the sampling probe (2), the axial direction of the inner hole of the sampling probe (3) is parallel to the axial direction of the inner hole of the sampling tube of the sampling probe (2) to ensure that the suction angle ≤ 15°.

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