Constant-speed sampling adjusting system based on automatic probe switching

Abstract

The invention discloses a constant-speed sampling adjusting system based on automatic probe switching, and the system comprises a sensor which is used for measuring flow data in a sampling pipeline and a sampling probe; the controller is used for receiving the flow signal of the sensor, calculating the current constant-speed sampling ratio according to the flow signal, and judging whether the sampling probe needs to be replaced or not according to the calculation result of the constant-speed sampling ratio; and the actuator is used for receiving and executing the sampling probe replacement instruction sent by the controller. Through accurate monitoring of the sensor, intelligent judgment of the controller and automatic operation of the actuator, automatic switching of the sampling probes can be achieved, so that the sampling requirements under different flow conditions are effectively met, and the constant speed and accuracy of the sampling process are ensured. According to the invention, the experiment efficiency can be improved, the reliability of the sampling result can be obviously improved, and the method is an ideal solution for constant-speed sampling adjustment in a closed system.

Description

Technical Field

[0001] The invention relates to the field of intelligent measuring instruments and meters, and in particular to a constant speed sampling and regulating system based on automatic switching of probes. Background Art

[0002] As the trend of electrification of passenger cars accelerates, the emission of particulate matter from motor vehicle exhaust continues to decrease, but at the same time, the proportion of particulate matter generated during braking in traffic pollutants has gradually increased. Studies have shown that the PN (particulate matter number) emission level of braking particulate matter has even exceeded the PN emission limit for light vehicles specified in my country's National VI Standard. Therefore, how to study and control particulate matter generated during braking has become a current research hotspot.

[0003] At present, the brake bench method is the mainstream brake particle test method. Its principle is to place the brake bench in a relatively closed test chamber, and use external airflow to continuously purge the particles generated during the braking process to the sampling pipe, and then the sampling probe collects the particles in the channel and sends them to relevant instruments for analysis. In the entire test device, the particle collection process is the key. However, since the flow rate in the sampling probe is often inconsistent with the flow rate in the sampling pipe, it is easy to cause non-isokinetic sampling, which in turn affects the accuracy of the results. The existing adjustment method is relatively cumbersome, and it is necessary to comprehensively consider factors such as the sampling pipe size and the purge airflow flow rate, and replace the sampling probes of different sizes for the sampling probe to achieve isokinetic sampling. However, since the sampling probe is embedded in the sampling pipe, the replacement requires the disassembly of the sampling pipe first, then the replacement of the sampling probe, and finally the reconnection of the sampling pipe. This process is not only complicated, 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 that needs 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 and adjustment system based on automatic switching of probes.

[0005] Isokinetic sampling and adjustment system based on automatic probe switching, including:

[0006] Sensors for measuring flow data in sampling pipes and sampling probes;

[0007] A controller, used for receiving the flow signal of the sensor and calculating the current constant speed sampling ratio accordingly, and judging whether the sampling probe needs to be replaced according to the calculation result of the constant speed sampling ratio;

[0008] The actuator is used to receive and execute the sampling probe replacement instruction issued by the controller.

[0009] Preferably, the actuator comprises a motor, which drives the turntable to retract and rotate through a transmission mechanism. A plurality of sampling probes with different inner diameters 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 comprises a transmission rod, a front end of which is connected to the middle of the turntable, and the motor comprises a first motor for driving the transmission rod to retract and a second motor for driving the transmission rod to rotate.

[0011] Preferably, the transmission rod is sleeved with a transmission gear, the transmission gear is meshedly connected with a driving gear of the second motor, and the second motor is fixed to the transmission rod via 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 meshingly connected to the rack.

[0013] Preferably, the sensor includes an ultrasonic flow meter, and the following steps are included when the ultrasonic flow meter is used to calculate the flow data in the sampling pipeline:

[0014] S11. By measuring the Doppler frequency shift △f, the flow velocity v of the fluid can be inferred:

[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 angle between the propagation direction of the ultrasonic wave and the flow direction of the fluid;

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

[0018] NQ=v·A

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

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

[0021]

[0022] Where IR is the constant speed sampling ratio; NQs is the average standardized airflow rate in the sampling probe (Nm 3 / h), which is set by the analyzer connected to the sampling probe and is a constant; di is the inner diameter of the sampling pipeline (mm), which is a fixed value; dn is the inner diameter of the sampling probe (mm), which is an adjusted value.

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

[0024] Preferably, when the sampling probe needs to be switched, 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 is 0.9 and NQs / NQ is the maximum value that the system can adjust, the calculated dn1 is the inner diameter size of the sampling probe with the largest specification; when IR is 1.15 and NQs / NQ is the minimum value that the system can adjust, the calculated dn2 is the inner diameter size of the sampling probe with the minimum specification;

[0027] According to the number of adjustable gears, a plurality of sampling probes of different specifications are arranged on the rotating disk within the inner diameter range of dn1 and dn2.

[0028] Preferably, the sampling probe is made of an electroplated and polished stainless steel tube; further preferably, the inner diameter of the sampling probe is at least greater than 4 mm; further preferably, the length of the inner hole of the sampling probe is at least 10 mm and not less than the inner diameter of the sampling probe; further preferably, the ratio of the outer diameter to the inner diameter at the entrance 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 conical 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 tube of the sampling probe 2, ensuring that the suction angle is ≤15°.

[0029] Beneficial effects of the present invention:

[0030] The sampling probe replacement method in the prior art is very cumbersome, requiring the sampling pipeline to be disassembled first, then the sampling probe to be replaced, and finally the sampling pipeline to be reconnected. This process is not only complicated, but may also damage the sealing between the pipelines of the sampling system, thereby affecting the sampling results. The present invention proposes an isokinetic sampling and adjustment system based on automatic switching of the probe, which can effectively shorten the sampling probe replacement time, improve 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 suitable for automobile emission measurements, but can also be used for isokinetic sampling and adjustment of various closed systems, and is convenient and efficient. BRIEF DESCRIPTION OF THE DRAWINGS

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

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

[0033] Figure 2 is a three-dimensional view of a mechanical structure according to an embodiment of the present invention Figure 1 ;

[0034] Figure 3 yes Figure 2 The enlarged view of point A in the middle;

[0035] Figure 4 yes Figure 2 The enlarged view of point B in the middle;

[0036] Figure 5 is a three-dimensional view of a mechanical structure according to an embodiment of the present invention Figure 2 ;

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

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

[0039] The present invention is further described in detail below in conjunction with embodiments. The following embodiments are for explanation of the present invention but the present invention is not limited to the following embodiments.

[0040] Since the size of the sampling channel is relatively fixed while the purge airflow changes in real time, it is difficult to accurately control the flow of the sampling probe and the sampling channel, which leads to non-constant speed sampling and affects the accuracy of the experimental results. In order to solve this problem, the present invention monitors the flow signal in real time and dynamically adjusts the size of the sampling probe in time, effectively improving the non-constant speed sampling phenomenon, and improving the sampling accuracy and experimental efficiency.

[0041] Various embodiments according to the present invention will be described in detail below with reference to the accompanying drawings.

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

[0043] The sensor is used to measure the flow data in the sampling pipeline 1 and the sampling probe 2; the sensor part is mainly composed of a flow sensor, whose task is to monitor the flow data in the pipeline (including the sampling pipeline, the pipeline of the sampling probe, etc.) in real time 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 (built-in flow sensor);

[0044] The controller is used to receive the flow signal from the sensor and calculate the current constant speed sampling ratio based on it, and judge whether the sampling probe 3 needs to be replaced according to the calculation result of the constant speed sampling ratio; the controller part is preferably composed of a high-performance control computer, and the controller is responsible for receiving the flow signal from the sensor and calculating the current constant speed sampling ratio based on it; according to the calculation result, the controller will judge whether the sampling probe 3 needs to be replaced, and send a corresponding instruction to start the replacement program; the controller plays a key decision-making role in the whole system to ensure that the sampling process is always kept 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; it can also be set by setting the console 8, and the operator manually controls the console 8 to transmit the replacement instruction signal to the actuator according to the system prompt to achieve semi-automatic switching;

[0045] The actuator is used to receive and execute 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, drives the turntable 6 to retract and rotate through the transmission mechanism 5, and switches to the sampling probe 3 size suitable for the current flow. 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 manual replacement of the sampling probe 3, and improves the overall reliability and work 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 to the turntable 6 by bolts.

[0046] The mechanical structure of the present invention is described in detail below.

[0047] like Figure 1-5 As shown, the actuator includes a motor 4, which drives the turntable 6 to retract and rotate through a transmission mechanism 5. A plurality of sampling probes 3 with different inner diameters are arranged on the turntable 6, and the sampling probes 3 are replaceably connected to the front end of the sampling probe 2. In specific 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 to achieve the position replacement of the sampling probes 3 with different inner diameter specifications. After the position replacement of the sampling probe 3 is completed, the transmission mechanism 5 pulls the turntable 6 backward to achieve 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 allows the sampling probe 3 to be directly connected to the front end of the sampling probe 2. Alternatively, a through hole 61 can be arranged on the main body of the driving turntable 6, and the sampling probe 3 is connected to the through hole 61. The through hole 61 is sleeved on the front end of the sampling probe 2 to achieve the connection between the sampling probe 3 and the sampling probe 2. The sleeve of the through hole 61 can further increase the sealing effect of the connection between the sampling probe 3 and the sampling probe 2. More specifically, in order 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 to the wall of the sampling pipeline 1 (for example, by Figure 2 The sampling probe bracket 21 shown in the figure fixes the sampling probe 2 to the sampling pipeline 1), so that the position of the sampling probe 2 will not be offset with the retraction of the turntable 6 and other operations. 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 pipeline, and the front end of the sampling probe 2 is correspondingly designed as a cone to ensure accurate positioning during assembly and ensure good sealing. Furthermore, a fixing device is set on the sampling pipeline 1 to connect to the ground to minimize the vibration 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, 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. In specific settings, the first motor 41 can also be replaced by a telescopic pump, an oil pump, an air pump, etc., and the telescopic pump is controlled to extend and retract through a controller.

[0049] In a specific embodiment of the present invention, the transmission rod 51 is sleeved with a transmission gear 52, the transmission gear 52 is meshedly 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. In this way, when the transmission rod 51 is retracted, the second motor 42 and the transmission gear 52 are kept in meshing 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. In specific implementation, the first motor 41 drives the rack 531 to move forward or backward, and the rack 531 pushes forward or pulls backward the transmission rod 51. In specific design, the transmission mechanism 5 also includes a transmission rod bracket 54 for maintaining the stable movement of the transmission rod 51. An annular structure can be provided on the transmission rod bracket 54, and the annular structure is movably sleeved on the outside of the transmission rod 51 to achieve stable movement of the transmission rod 51 during retraction and rotation.

[0051] The system flow part of the present invention is described in detail below.

[0052] like Figure 1-6 As shown, the sensor includes an ultrasonic flow meter. Since the particles in the pipeline cannot be disturbed during the measurement process, traditional mechanical flow sensors and thermal flow sensors are not suitable for this scenario. In contrast, ultrasonic flow meters are currently the most suitable choice. Ultrasonic flow meters measure flow 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 rate of the fluid can be accurately determined, thereby obtaining accurate flow data.

[0053] The following steps are included when using an ultrasonic flow meter to calculate the flow data in the sampling pipeline 1:

[0054] S11. By measuring the Doppler frequency shift △f, the flow velocity v of the fluid can be inferred:

[0055]

[0056] Wherein, 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 angle between the propagation direction of the ultrasonic sound wave and the flow direction of the fluid; it is worth noting that the propagation speed of the sound velocity in the fluid c depends on the temperature, density and other physical properties of the fluid; the sound velocity usually needs to be corrected during the measurement process; the selection of the angle θ directly affects the measurement results, and it is usually necessary to ensure that the measuring 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 concentration of particles is too low, the measurement results may be inaccurate;

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

[0058] NQ=v·A

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

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

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

[0062]

[0063] Where IR is the constant speed 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 pipe 1 (mm), which is a fixed value; dn is the inner diameter of the sampling probe 3 (mm), which is an adjustment value. NQs is the standardized airflow rate in the sampling probe 2, which is controlled by the sampling instrument connected to the rear end, namely 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. 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 to replace the sampling probe 3 with a larger dn when NQ becomes smaller.

[0064] When IR is equal to 1, it is constant speed sampling, but in actual situations, IR often presents a fluctuating and stable state. Therefore, the value of the constant speed sampling ratio near 1 can be considered as constant speed sampling. Preferably, the calculated value of the constant speed ratio between 0.9-1.15 is considered as constant speed sampling. The controller includes a control computer, which is responsible for processing the flow signal, calculating the constant speed sampling ratio, and outputting the operation of replacing the sampling nozzle according to the constant speed 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; when IR<0.9, the controller issues an instruction to replace the sampling probe 3 with a smaller inner diameter; 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 the setting program, or the system can prompt the operator 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 the sampling probe 3 needs to be switched, the inner diameter size dn of the sampling probe 3 to be replaced is calculated according to the following formula:

[0067]

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

[0069] According to the number of adjustable gears, multiple sampling probes 3 of different specifications are arranged on the turntable 6 within the inner diameter range of dn1 and dn2. During the measurement process, if 0.9≤IR≤1.15 cannot be achieved after switching all the sampling probes 3, the controller will send out an alarm signal.

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

[0071] (1) The sampling probe 3 is made of electroplated and polished stainless steel tube (or weather-resistant, high-precision material of the same or higher grade) to achieve 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 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 sampling port tip 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 of the sampling probe 3;

[0073] (3) The wall thickness of the edge of the sampling port of the sampling probe 3 is as thin as possible to minimize the interference with the flow; preferably, the ratio of the outer diameter to the inner diameter of the edge of the sampling port (at 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 of less than 30°, and its axial direction should be parallel to the sampling pipe 1 to ensure that the suction angle is ≤15°; the sampling port of the sampling probe 3 is the entrance of the airflow 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 be a conical transition during design. A conical angle of less than 30° can ensure that the airflow remains stable when entering the sampling tube of the sampling probe 2 and will not be suddenly obstructed or generate turbulence; the suction angle is the angle between the airflow direction and the axis of the sampling tube of the sampling probe 2 when the airflow enters the sampling tube of the sampling probe 2; ensuring that the suction angle is ≤15° can ensure that the airflow enters the sampling system of the sampling probe 2 in a nearly parallel state, thereby reducing 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 rate signal at the sampling probe 2 are fed back to the control computer of the controller to calculate the constant speed sampling ratio. When the constant speed sampling ratio is too small, the control computer of the controller instructs the first motor 41 to drive the transmission mechanism 5 to start the feed, 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 and switch to the sampling probe 3 with a larger inner diameter. After adjustment, the transmission mechanism 5 pulls the turntable 6 back to connect the new sampling probe 3 to 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 connects again. Through these automatic adjustments, it is ensured that the sampling probe 3 can automatically switch with changes in flow, which simplifies the replacement process and improves the experimental efficiency and switching accuracy.

[0076] In summary, the present invention can realize automatic switching of sampling probes through precise monitoring of sensors, intelligent judgment of controllers, and automated operation of actuators, thereby effectively responding to sampling requirements under different flow conditions and ensuring the isokineticity and accuracy of the sampling process. The present invention can not only improve experimental efficiency, but also significantly improve the reliability of sampling results, and is an ideal solution for isokinetic sampling regulation in a closed system.

[0077] It should be noted that the terms used in the present invention are only for describing specific embodiments, rather than limiting the scope of the present invention. As shown in the present specification, unless the context clearly indicates an exception, the words "one", "a", "a kind of" and / or "the" do not specifically refer to the singular, but may also include the plural. The terms "include", "comprise" or any other variant thereof are intended to cover non-exclusive inclusion, so that the process, method or device including a series of elements includes not only those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such process, method or device. In the absence of more restrictions, the elements defined by the sentence "include one..." do not exclude the presence of other identical elements in the process, method or device including the elements.

[0078] It should also be noted that the terms "center", "up", "down", "left", "right", "vertical", "horizontal", "inside", "outside", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are 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, and therefore cannot be understood as a limitation on the present invention. Unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", etc. 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 or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be a connection between the 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 it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the technical solutions of the embodiments of the present invention.

[0080] In addition, it should be noted that the shapes and names of the parts and components of the specific embodiments described in this specification may be different. Any equivalent or simple changes made based on the structure, features and principles described in the patent concept of the present invention are included in the protection scope of the patent of the present invention. The technicians in the technical field of the present invention can make various modifications or supplements to the specific embodiments described or replace them in a similar manner, as long as they do not deviate from the structure of the present invention or exceed the scope defined by the claims, they should all fall within the protection scope of the present invention.

Claims

1. The isokinetic sampling and adjustment system based on automatic probe switching is characterized by: include: A sensor for measuring flow data in a sampling pipeline (1) and a sampling probe (2); A controller, used for receiving the flow signal of the sensor and calculating the current constant speed sampling ratio based on the flow signal, and judging whether the sampling probe (3) needs to be replaced according to the calculation result of the constant speed sampling ratio; An actuator is used to receive and execute a sampling probe (3) replacement instruction issued by the controller.

2. The isokinetic sampling and adjustment system according to claim 1, characterized in that: The actuator comprises a motor (4), and the motor (4) drives a turntable (6) to retract and rotate via a transmission mechanism (5). A plurality of sampling probes (3) with different inner diameters are arranged on the turntable (6), and the sampling probes (3) are replaceably connected to the front end of the sampling probe (2).

3. The isokinetic sampling and adjustment system according to claim 2, characterized in that: The transmission mechanism (5) comprises a transmission rod (51), the front end of which is connected to the middle of the turntable (6); the motor (4) comprises 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.

4. The isokinetic sampling and adjustment system according to claim 3, characterized in that: The transmission rod (51) is sleeved with a transmission gear (52), the transmission gear (52) is meshedly connected with a driving gear of the second motor (42), and the second motor (42) is fixed to the transmission rod (51) via a motor bracket (421).

5. The isokinetic sampling and adjustment system according to claim 4, characterized in that: The rear end of the transmission rod (51) is connected to a rack (531) of a feeding mechanism (53), and the driving gear of the first motor (41) is meshingly connected to the rack (531).

6. The isokinetic sampling and adjustment system according to claim 5, characterized in that: The sensor comprises an ultrasonic flow meter. When the ultrasonic flow meter is used to calculate the flow data in the sampling pipeline (1), the following steps are included: S11. By measuring the Doppler frequency shift △f, the flow velocity v of the fluid can be inferred: 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 angle between the propagation direction of the ultrasonic wave and the flow direction of the fluid; S12. Calculate the flow rate in the sampling pipeline (1) according to the flow velocity v of the fluid: NQ=v·A Where NQ is the average standardized air flow rate in the sampling pipeline (Nm 3 / h), A is the cross-sectional area of ​​the pipe (m 2 ).

7. The isokinetic sampling and adjustment system according to claim 6, characterized in that: The controller calculates the constant speed sampling ratio according to the following formula: Wherein, IR is the constant speed sampling ratio; NQs is the average standardized airflow rate (Nm 3 / h), 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 pipeline (1) and is a fixed value; dn is the inner diameter (mm) of the sampling probe (3) and is an adjustable value.

8. The isokinetic sampling and adjustment system according to claim 7, characterized in that: When IR>1.15, the controller issues an instruction to replace the sampling probe (3) with a larger inner diameter; when IR<0.9, the controller issues an instruction to replace the sampling probe (3) with a smaller inner diameter; when 0.9≤IR≤1.15, the controller does not issue an instruction.

9. The isokinetic sampling and adjustment system according to claim 8, characterized in that: The inner diameter dimension dn of the sampling probe (3) on the rotating disk 6 is calculated according to the following formula: In the formula, when IR is 0.9 and NQs / NQ is the maximum value that the system can adjust, the calculated dn1 is the inner diameter size of the sampling probe (3) with the largest specification; when IR is 1.15 and NQs / NQ is the minimum value that the system can adjust, the calculated dn2 is the inner diameter size of the sampling probe (3) with the smallest specification; According to the number of adjustable gears, a plurality of sampling probes (3) of different specifications are arranged on the rotating disk (6) within the inner diameter range of dn1 and dn2.

10. The isokinetic sampling and adjustment system according to claim 9, characterized in that: The sampling probe (3) is made of a stainless steel tube that is electroplated and polished; preferably, the inner diameter of the sampling probe (3) is at least greater than 4 mm; preferably, the inner hole length of the sampling probe (3) is at least 10 mm and is not less than the inner diameter of the sampling probe (3); preferably, the ratio of the outer diameter to the inner diameter at the entrance of the sampling probe (3) is less than 1.1; preferably, the inner diameter of the sampling probe (3) changes at a conical angle of less than 30°; preferably, any change in the inner diameter of the sampling probe (3) changes at a conical angle of less than 30°; 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 tube of the sampling probe (2), ensuring that the suction angle is ≤15°.

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