Constant-speed sampling control system based on variable-diameter probe

Abstract

The invention discloses a constant-speed sampling control system based on a variable-diameter probe, and the system comprises a sensor which is used for measuring the 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 subjected to diameter change according to the calculation result of the constant-speed sampling ratio; and the actuator is used for receiving and executing the sampling probe reducing instruction sent by the controller. Through accurate monitoring of the sensor, intelligent judgment of the controller and automatic operation of the actuator, the diameter change of the sampling probe can be controlled, so that the sampling requirements under different flow conditions are effectively met, and the constant speed and accuracy of the sampling process are ensured. The experimental efficiency can be improved, the reliability of a sampling result can be remarkably improved, and the method is an ideal solution for constant-speed sampling in a closed system.

Description

Technical Field

[0001] The present application relates to the field of intelligent measuring instruments and meters, and in particular to a constant-speed sampling control system based on a variable-diameter probe. 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 mainstream method for brake particle testing is the brake bench method. The basic principle of this method is to place the brake bench in a relatively closed test chamber, and continuously purge it through external airflow so that the particles generated during the braking process enter the sampling channel. The sampling probe is located in the channel and is responsible for collecting particles and transmitting them to the corresponding analytical instrument for detection. In the entire test system, the effective collection of particles is a key link. However, since the air flow velocity in the sampling probe usually does not match the air flow velocity in the sampling channel, the phenomenon of non-isokinetic sampling often occurs, which has an adverse effect on the accuracy of the test results. The current adjustment method is relatively complicated, and it is often necessary to comprehensively consider multiple factors such as pipeline size and purge air flow rate, and replace sampling probes of different specifications to achieve isokinetic sampling. However, since the sampling probe is embedded in the pipeline, the replacement process of the sampling probe is relatively cumbersome. During operation, it is necessary to first disassemble the connecting pipeline, then replace the sampling probe, and finally reinstall the pipeline. This not only increases the complexity of the operation, but also may damage the sealing of the equipment, thereby further affecting the accuracy of the sampling. Therefore, how to simplify the adjustment process of the sampling probe size to ensure constant-speed sampling and reduce interference to the equipment has become an important issue that needs to be urgently resolved in this test method. Summary of the invention

[0004] In order to solve one or more technical problems in the prior art, the present application provides an isokinetic sampling control system based on a variable diameter probe, comprising:

[0005] Sensors for measuring flow data in sampling pipes and sampling probes;

[0006] 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 reduced in diameter according to the calculation result of the constant speed sampling ratio;

[0007] The actuator is used to receive and execute the sampling probe diameter change instruction issued by the controller.

[0008] In a possible implementation, the sampling probe is connected to the sampling probe, and the sampling probe includes a variable diameter adjustment member and a sampling port;

[0009] The variable diameter adjusting member comprises an adjusting gear and an adjusting ring arranged on the adjusting gear, the adjusting gear is connected to the actuator, and the adjusting ring is connected to the sampling port.

[0010] In a possible implementation, at least one adjustment track is provided on the adjustment ring;

[0011] The sampling port includes at least two blades and a bracket, and the blades are movably connected to the bracket;

[0012] At least one of the blades is provided with a protrusion, and the protrusion is clamped in the adjustment track.

[0013] In a possible implementation, the actuator includes a motor and a transmission mechanism, and the motor is connected to the transmission mechanism to drive the sampling probe to retract and change its diameter.

[0014] In a possible implementation, the motor includes a first motor, the transmission mechanism includes a feeding mechanism connected to the first motor and a transmission rod connected to the feeding mechanism, and the other end of the transmission rod is connected to the sampling probe to drive the sampling probe to retract axially along the transmission rod.

[0015] In a possible implementation, the motor includes a second motor, and the second motor is connected to the adjusting gear to drive the sampling probe to change its diameter.

[0016] In a possible implementation, the sensor includes an optical particle flow meter, and using the optical particle flow meter to calculate the flow data in the sampling pipeline includes the following steps:

[0017] S11. Calculate the flow velocity v of the fluid by measuring the time it takes for the fluid to pass through the light beam and the geometric parameters of the optical detection area:

[0018]

[0019] Where, v is the calculated fluid velocity, in m / s; L is the effective detection length of the light beam or the length of the measurement area, in m; t is the time it takes for the fluid to pass through the light beam area, in s;

[0020] S12. Calculate the flow rate in the sampling pipeline according to the flow velocity v of the fluid:

[0021] NQ=3600·v·A

[0022] Where NQ is the average standardized air flow rate in the sampling pipeline, in Nm 3 / h, A is the cross-sectional area of ​​the pipe, in m 2 .

[0023] In a possible implementation, the controller calculates the constant speed sampling ratio according to the following formula:

[0024]

[0025] Where IR is the constant speed sampling ratio; NQ s is the average standardized airflow rate in the sampling probe, in Nm 3 / h, which is set by the analyzer connected to the sampling probe and is a constant; NQ is the average standardized air flow rate in the sampling pipeline, in Nm 3 / h;d i is the inner diameter of the sampling pipe, in mm, and is a fixed value; d n is the inner diameter of the sampling probe, in mm, and is the adjustment value.

[0026] In a possible implementation, when IR>1.15, the controller issues an instruction to enlarge the inner diameter of the sampling probe; when IR<0.9, the controller issues an instruction to reduce the inner diameter of the sampling probe; when 0.9≤IR≤1.15, the controller does not issue an instruction;

[0027] Preferably, the inner diameter size d of the sampling probe is n Calculate according to the following formula:

[0028]

[0029] In the formula, when IR is 0.9, NQ s When NQ takes the maximum value that the system can adjust, the calculated d n1 is the inner diameter of the largest sampling probe; when IR is 1.15, NQ s When / NQ takes the minimum value that the system can adjust, the calculated d n2 is the inner diameter of the minimum sampling probe;

[0030] The actuator receives the sampling probe diameter change instruction from the controller, and moves the sampling probe to the same position as the control probe. n1 With d n2 Adjust the inner diameter of the sampling probe within the inner diameter range.

[0031] In a possible implementation, the sampling probe is made of electroplated and polished stainless steel; preferably, the inner diameter of the sampling probe is at least greater than 4 mm; 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; preferably, the ratio of the outer diameter to the inner diameter at the entrance of the sampling probe is less than 1.1; preferably, any change in the inner diameter of the sampling probe changes at a conical angle less than 30°; preferably, at the connection between the sampling probe and the sampling probe, the axial direction of the inner hole of the sampling probe is parallel to the axial direction of the inner hole of the sampling tube of the sampling probe, ensuring that the suction angle is ≤15°.

[0032] Beneficial effects of this application:

[0033] The method of changing the inner diameter of the sampling probe in the prior art is very cumbersome, and it is necessary to first disassemble the sampling pipeline, then replace the sampling probe with a different inner diameter, and finally reconnect the sampling pipeline. This process is not only complicated, but may also destroy the sealing between the pipelines of the sampling system, thereby affecting the sampling results. The present application proposes an isokinetic sampling control system based on a variable diameter probe, which can effectively shorten the time for changing the inner diameter of the sampling probe, 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 emissions measurement, but also can be used for isokinetic sampling adjustment of various closed systems, and is convenient and efficient. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] The accompanying drawings are used to provide further understanding of the present application and constitute a part of the specification. They are used to explain the present application together with the embodiments of the present application and do not constitute a limitation of the present application.

[0035] Figure 1 It is a structural schematic diagram of a constant-speed sampling control system based on a variable-diameter probe according to an embodiment of the present application;

[0036] Figure 2 It is a partial cross-sectional view of the isokinetic sampling control system of the present application after installation;

[0037] Figure 3 yes Figure 1 The enlarged view of point A in the middle;

[0038] Figure 4 It is a schematic diagram of the sampling probe structure of the isokinetic sampling control system of an embodiment of the present application;

[0039] Figure 5 It is a schematic diagram of the structure of the variable diameter adjustment member of the constant speed sampling control system of the embodiment of the present application;

[0040] Figure 6 Schematic diagram of the sampling port structure of the isokinetic sampling control system of the embodiment of the present application;

[0041] Figure 7 It is a schematic diagram of the state structure of a large inner diameter sampling probe of a constant speed sampling control system according to an embodiment of the present application;

[0042] Figure 8 It is a schematic diagram of the state structure of a small inner diameter sampling probe of the isokinetic sampling control system of an embodiment of the present application;

[0043] Fig. 9 is a flowchart of the system operation according to an embodiment of the present application;

[0044] Reference numerals:

[0045] 1. Sampling pipeline,

[0046] 2. Sampling probe, 21. Probe bracket,

[0047] 3. Sampling probe, 31. Variable diameter adjustment member, 311. Adjusting gear, 312. Adjusting ring, 313. Fixing pin; 312-1. Adjusting track, 32. Sampling port, 321. Blade, 3211-1. Protrusion, 3211. Active blade, 3212. Driven blade, 322. Bracket, 323. Hinge,

[0048] 4. Motor, 41. First motor, 42. Second motor,

[0049] 5. Transmission mechanism, 51. Feed mechanism, 511. Rack, 52. Transmission rod, 521. Fixed plate, 53. Motor bracket, 54. Transmission gear, 55. Transmission rod bracket,

[0050] 6. Analyzer,

[0051] 7. Console. DETAILED DESCRIPTION

[0052] The present application is further described in detail below in conjunction with the embodiments. The following embodiments are intended to explain the present application but the present application is not limited to the following embodiments.

[0053] 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 application effectively improves the non-constant speed sampling phenomenon and improves the sampling accuracy and experimental efficiency by real-time monitoring of the flow signal and timely dynamic adjustment of the size of the sampling probe.

[0054] Various embodiments according to the present application will be described in detail below with reference to the accompanying drawings.

[0055] like Figure 1-9 As shown, the isokinetic sampling and adjustment system based on automatic probe switching includes:

[0056] 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, and its 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 6 (built-in flow sensor);

[0057] The controller is used to receive the flow signal from the sensor and calculate the current constant speed sampling ratio accordingly, and judge whether the sampling probe 3 needs to be changed in diameter 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 accordingly; according to the calculation result, the controller will judge whether the sampling probe 3 needs to be changed in diameter, 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 7, and the operator can manually control the console 7 to transmit the replacement instruction signal to the actuator according to the system prompt to achieve semi-automatic switching;

[0058] 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 a sampling probe 3 diameter change instruction, the actuator immediately responds, controls the motor 4 to operate, and drives the sampling probe 3 to retract and change its diameter through the transmission mechanism 5, and changes it to a 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 sampling probe 3 with a changeable inner diameter of different sizes is the core part of the mechanical mechanism of this application.

[0059] The mechanical structure part of the present application is described in detail below.

[0060] Figure 1 is a schematic diagram of the structure of the isokinetic sampling control system based on the variable diameter probe provided in this application, Figure 2 It is a schematic diagram of an isokinetic sampling control system based on a variable diameter probe provided in the present application installed in a sampling pipeline 1. Figure 3 yes Figure 1 The enlarged schematic diagram at A in the middle is as follows: Figure 1-Figure 3As shown, the actuator includes a motor 4, which drives the sampling probe 3 to retract and change its diameter through a transmission mechanism 5. The sampling probe 3 is movably connected to the front end of the sampling probe 2. Before performing the diameter change operation, the motor 4 pushes the sampling probe 3 away from the sampling probe 2 through the transmission mechanism 5 to separate the sampling probe 2 from the sampling probe 3. Then, the inner diameter of the sampling port 32 is adjusted by controlling the diameter-changing adjustment member 31 of the sampling probe 3. After completing the diameter change operation of the sampling probe 3, the transmission mechanism 5 pulls the sampling probe 3 backward until the sampling probe 3 is connected to the front end of the sampling probe 2.

[0061] In some examples of this application, see Figure 4-Figure 5 , Figure 4 It is a schematic diagram of the structure of the sampling probe 3 that can automatically change the inner diameter size provided by the present application. Figure 5 3 is a schematic diagram of the structure of the variable diameter adjusting member 31 provided in the present application. In order to realize the flexible adjustment of the inner diameter of the sampling probe 3, the variable diameter adjusting member 31 includes an adjusting gear 311 and an adjusting ring 312. The adjusting ring 312 is fixed to the adjusting gear 311 through a fixing pin 313. The transmission mechanism 5 of the actuator is movably connected with the adjusting gear 311, and can drive the adjusting gear 311 to rotate, thereby driving the adjusting ring 312 to rotate. The adjusting ring 312 is connected to the sampling port 32. When the adjusting ring 312 rotates, the inner diameter of the sampling port 32 can be changed.

[0062] See also Figure 6 The sampling port 32 is mainly formed by at least two blades 321, which are movably connected to the bracket 322. The blade 321 can be a folded rectangular blade with a fold in the middle, and the blade surfaces on both sides overlap each other to facilitate the change and adjustment of its inner diameter; the blade 321 can also be a rectangular blade with multiple folds, or an arc-shaped or other shaped blade, as long as it can enclose a sampling port 32 with a variable inner diameter. Part of the blade surfaces between the two blades 321 fit each other. When one blade 321 moves, such as expanding outward or contracting toward the center, it can drive the other blades 321 hinged to the blade to move in the same direction.

[0063] See also Figure 6 and Figure 7 The blade 321 includes an active blade 3211 and a driven blade 3212, both of which are connected to the bracket 322 through a movable hinge 323 arranged at the bottom of the blade 321. A vertical protrusion 3211-1 is formed at the hinge 323 at the bottom of the outer side of the active blade 3211, and the protrusion 3211-1 is clamped in at least one inclined adjustment track 312-1 opened on the adjustment ring 312.

[0064] The number of active blades 3211 and driven blades 3212 can be set according to actual needs, and this application does not impose any restrictions on this.

[0065] The size of the protrusion 3211-1 and the width of the adjustment track 312-1 can be adjusted according to the purpose of completing the function, and the number of adjustment track 312-1 can also be adjusted according to actual production use, but the inclination direction of multiple adjustment track 312-1 should be consistent. For example, when the adjustment ring 312 is placed horizontally, the opening direction of the adjustment track 312-1 thereon is from the upper left to the lower right, and the angle formed by each track with the horizontal direction is consistent.

[0066] See also Figure 2-7 , Figure 7 and Figure 8 , Figure 8 This is the state of the small inner diameter of the sampling probe 3. Figure 7 The sampling probe 3 is in the state of maximum inner diameter. When the actuator executes the instruction to expand the inner diameter, Figure 8 to Figure 7 During the process, the motor 4 drives the transmission mechanism 5, thereby driving the adjusting gear 311 to rotate clockwise relative to the bracket 322, thereby driving the adjusting ring 312 to rotate clockwise relative to the bracket 322, while the blade 321 does not rotate relative to the bracket 322. At this time, due to the rotation of the adjusting ring 312, the protrusion 3211-1 at the bottom of the active blade 3211 moves in the inclined adjustment track 312-1 opened on the adjusting ring 312, and the moving direction is from the upper left to the lower right (that is, from the direction away from the bracket 322 to the direction close to the bracket 322). During this process, the adjustment track 312-1 can gradually restrict the protrusion 3211-1, that is, it can generate a downward force on the protrusion 3211-1, thereby driving the active blade 3211 to rotate through the hinge 323 at its bottom, so that the top of the active blade 3211 expands outward, and the active blade 3211 drives the adjacent driven blade 3212 to expand outward synchronously, thereby causing all the blades 321 surrounding the sampling port 32 to expand outward, so that the inner diameter of the final sampling port 32 is expanded, thereby completing the instruction to expand the inner diameter.

[0067] When the actuator executes the instruction to reduce the inner diameter, Figure 7 to Figure 8During the process, the motor 4 drives the transmission mechanism 5, thereby driving the adjusting gear 311 to rotate counterclockwise relative to the bracket 322, thereby driving the adjusting ring 312 to rotate counterclockwise relative to the bracket 322, while the blade 321 does not rotate relative to the bracket 322. At this time, due to the rotation of the adjusting ring 312, the protrusion 3211-1 at the bottom of the active blade 3211 moves in the gradually expanding adjustment track 312-1 opened on the adjusting ring 312, and moves from the lower right to the upper left (that is, from the direction close to the bracket 322 to the direction away from the bracket 322), and then the adjustment track 312-1 exerts an upward force on the protrusion 3211-1. At this time, under the action of the hinge 323, the active blade 3211 shrinks toward the center of the probe, thereby driving the adjacent driven blades 3212 to automatically gather and enclose toward the inner center, so that the inner diameter of the final sampling port 32 is reduced, thereby completing the instruction to reduce the inner diameter.

[0068] In some examples of the present application, 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 1 and Figure 2 The sampling probe bracket 21 shown in the figure fixes the sampling probe 2 to the sampling pipe 1), so that the position of the sampling probe 2 will not be offset as the inner diameter of the sampling probe 3 changes. 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 ensure good sealing. Furthermore, a fixing device is set on the sampling pipe 1 to connect to the ground to minimize the vibration caused by gas flow.

[0069] In some examples of the present application, in order to better adjust the inner diameter of the sampling probe 3, refer to Figure 1 The motor 4 includes a first motor 41, and the transmission mechanism 5 includes a feeding mechanism 51 and a transmission rod 52. The driving gear of the first motor 41 is meshed with the rack 511 of the feeding mechanism 51, thereby driving the rack 511 to move forward or backward. The rack 511 is connected to the transmission rod 52, thereby driving the transmission rod 52 to move forward or backward. The other end of the transmission rod 52 is connected to the sampling probe 3 to drive the sampling probe 3 to move forward or backward along the axial direction of the transmission rod 52. In the specific setting, 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 be telescopic by a controller.

[0070] In some examples of this application, see Figure 2 and Figure 3 The motor 4 includes a second motor 42, which is disposed on a transmission rod 52 via a motor bracket 53, and a driving gear of the second motor 42 is connected to an adjusting gear 311 via a transmission gear 54 to drive the sampling probe 3 to change its diameter.

[0071] Further, to optimize the installation of components, see Figure 3 A fixing plate 521 is provided at the sampling end of the transmission rod 52, and the sampling probe 3 is fixed on the fixing plate 521 through a bracket 322. Its specific setting position should correspond to the port of the sampling probe 2 so that the two can be accurately docked; the transmission gear 54 is fixed on the fixing plate 521 and meshed with the adjustment gear 311.

[0072] In some examples of the present application, the transmission mechanism 5 further includes a transmission rod bracket 55 for maintaining stable movement of the transmission rod 52. The transmission rod bracket 55 may be provided with an annular structure, which is movably sleeved on the outside of the transmission rod 52 to achieve stable movement of the transmission rod 52 during retraction and rotation.

[0073] The system flow part of this application is described in detail below.

[0074] Sensors include optical particle flow meters. Traditional mechanical flow sensors and thermal flow sensors are not suitable for this scenario because they cannot interfere with the particles in the pipeline during the measurement process. In contrast, optical particle flow meters are currently the most suitable choice. Optical particle flow meters are sensors that detect particle flow and particle size distribution based on optical measurement principles. Their working principle mainly relies on optical scattering, absorption or occlusion to analyze the number, size and movement speed of particles.

[0075] The optical particle flowmeter is used to measure and calculate the flow data in the sampling pipeline 1, including the following steps:

[0076] S11. Calculate the flow velocity v of the fluid by measuring the time it takes for the fluid to pass through the light beam and the geometric parameters of the optical detection area:

[0077]

[0078] Where, v is the calculated fluid velocity, in m / s; L is the effective detection length of the light beam or the length of the measurement area, in m; t is the time it takes for the fluid to pass through the light beam area, in s;

[0079] S12. Calculate the flow rate in the sampling pipeline (1) according to the flow velocity v of the fluid:

[0080] NQ=3600·v·A

[0081] Where NQ is the average standardized air flow rate in the sampling pipeline, in Nm 3 / h, A is the cross-sectional area of ​​the pipe, in m 2 .

[0082] 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.

[0083] In the process of using an optical particle flowmeter to measure flow, it is necessary to ensure that a measurement window with transparency that meets the requirements is provided on the sampling pipe 1 so that the light beam can penetrate the pipe wall and enter the interior of the pipe for detection. The measurement window can be made of quartz glass or other suitable light-transmitting materials to ensure effective transmission of the light beam without affecting the sealing of the pipe. At the same time, in order to maintain the accuracy and reliability of the measurement system, the measurement window needs to be cleaned and maintained regularly to prevent dust accumulation and contaminant adhesion, thereby ensuring the quality of light beam transmission and the accuracy of its measurement results.

[0084] In some examples of the present application, the controller calculates the constant speed sampling ratio according to the following formula:

[0085]

[0086] Where IR is the constant speed sampling ratio; NQ s is the average standardized air flow rate in the sampling probe (2), in Nm 3 / h, which is set by the analyzer (6) connected to the sampling probe (2) and is a constant; NQ is the average standardized air flow rate in the sampling pipeline, in Nm 3 / h;d i is the inner diameter of the sampling pipe (1), in mm, and is a fixed value; d n is the inner diameter of the sampling probe (3), in mm, and is the adjustment value. s is the standardized air flow rate in the sampling probe 2, which is controlled by the sampling instrument connected to the back end, namely the analyzer 6. Under different experimental conditions, NQ s It can be set to different constant values. This constant value does not change during the same experiment. The same is true for the inner diameter of sampling probe 2. There is no need to replace sampling probe 2 during the same experiment. Sampling probes with different inner diameters may be replaced according to different experimental conditions. During the same experiment, due to NQ s is a constant, d i is a fixed value. In order to make IR approach 1, the operation performed is to reduce the inner diameter d of the sampling probe 3 when NQ increases. n When NQ increases, the inner diameter d of the sampling probe 3 is enlarged. n .

[0087] 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.

[0088] In some examples of the present application, when IR>1.15, the controller issues an instruction to enlarge the inner diameter of the sampling probe 3; when IR<0.9, the controller issues an instruction to reduce the inner diameter of the sampling probe 3; 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.

[0089] In some examples of the present application, when the sampling probe 3 needs to be replaced, the inner diameter size d of the sampling probe 3 to be replaced is n Calculate according to the following formula:

[0090]

[0091] In the formula, when IR is 0.9, NQ s When NQ takes the maximum value that the system can adjust, the calculated d n1 is the inner diameter of the largest sampling probe (3); when IR is 1.15, NQ s When / NQ takes the minimum value that the system can adjust, the calculated d n2 is the inner diameter of the minimum-specification sampling probe (3);

[0092] In d n1 With d n2 Within the inner diameter range, the size of the blade 321 of the sampling port 32 is designed so that after shrinking, the size can be no larger than d n2 , after expansion, the inner diameter is not less than d n1 During the measurement process, if the sampling probe 3 after the diameter change still cannot make 0.9≤IR≤1.15, the controller will send out an alarm signal.

[0093] In some examples of the present application, the design of the sampling probe 3 complies with the following requirements:

[0094] (1) The blade 321 of the sampling probe 3 is made of electroplated and polished stainless steel (or weather-resistant, high-precision materials of equal 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;

[0095] (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;

[0096] (3) The wall thickness of the sampling port edge of the sampling probe 3 is as thin as possible, that is, the thickness of the active and driven blades should be as small as possible, so as to minimize the interference with the flow; preferably, the ratio of the outer diameter to the inner diameter of the sampling port edge (at the entrance of the sampling probe 3) is less than 1.1;

[0097] (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.

[0098] See also Fig. 9During the experiment, the sensor feeds back the flow rate in the sampling pipe 1 and the flow rate signal at the sampling probe 2 to the control computer of the controller. After receiving the signal, the controller calculates the constant speed sampling ratio. It is determined whether the constant sampling speed ratio is between 0.9 and 1.15. If so, there is no need to perform the diameter reduction operation. If not, it is determined whether the constant sampling speed ratio is less than 0.9. When the constant speed sampling is less than 0.9, the control computer of the controller issues an inner diameter increase instruction, controls the first motor 41 to drive the transmission mechanism 5 to start feeding, and pushes the sampling probe 3 to move axially along the transmission rod 52, so that the sampling probe 3 is separated from the sampling probe 2. Then, the second motor 42 drives the diameter reducing adjustment member 31 to increase the inner diameter of the sampling probe 3. After adjustment, the transmission mechanism 5 pulls back the sampling probe 3, so that the sampling probe 3 after the diameter reduction is connected to the sampling probe 2, and the operation of increasing the inner diameter of the sampling probe 3 is completed. Then, the above process is repeated until the sampling speed ratio is between 0.9 and 1.15. If the sampling ratio is greater than 1.15, the system performs the opposite operation: the control computer of the controller issues a reduction command, controls the first motor 41 to drive the transmission mechanism 5 to start feeding, and pushes the sampling probe 3 to move axially along the transmission rod 52, so that the sampling probe 3 is separated from the sampling probe 2. Then, the second motor 42 drives the variable diameter adjustment member 31 to reduce the inner diameter of the sampling probe 3. After adjustment, the transmission mechanism 5 pulls back the sampling probe 3, so that the reduced diameter sampling probe 3 is connected to the sampling probe 2, completing an operation of reducing the inner diameter of the sampling probe 3. The above process is then repeated until the sampling speed ratio is between 0.9 and 1.15. Through these automatic adjustments, it is ensured that the sampling probe 3 can be automatically switched with the flow rate change, which simplifies the replacement process and improves the experimental efficiency and switching accuracy.

[0099] In summary, this application can adjust the inner diameter of the sampling probe through precise monitoring of the sensor, intelligent judgment of the controller, and automated operation of the actuator, thereby effectively responding to sampling requirements under different flow conditions and ensuring the isokineticity and accuracy of the sampling process. This application can not only improve experimental efficiency, but also significantly improve the reliability of sampling results, and is an ideal solution for isokinetic sampling adjustment in a closed system.

[0100] It should be noted that the terms used in this application are only for describing specific embodiments, rather than limiting the scope of this application. As shown in the specification of this application, 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.

[0101] It should also be noted that the terms "center", "up", "down", "left", "right", "vertical", "horizontal", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply 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 application. 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 this application can be understood according to specific circumstances.

[0102] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit it. Although the present application 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 with 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 application.

[0103] 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 this application are included in the protection scope of the patent of this application. The technicians in the technical field of this application can make various modifications or supplements to the specific embodiments described or replace them in a similar way, as long as they do not deviate from the structure of this application or exceed the scope defined by the claims, they should all fall within the protection scope of this application.

Claims

1. An isokinetic sampling control system based on a variable diameter probe, characterized in that: 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 reduced in diameter according to the calculation result of the constant speed sampling ratio; An actuator is used to receive and execute a diameter change instruction of the sampling probe (3) issued by the controller.

2. The constant speed sampling control system according to claim 1, characterized in that: The sampling probe (3) is connected to the sampling probe (2), and the sampling probe (3) comprises a diameter-changing adjusting member (31) and a sampling port (32); The variable diameter adjusting member (31) comprises an adjusting gear (311) and an adjusting ring (312) arranged on the adjusting gear (311); the adjusting gear (311) is connected to the actuator, and the adjusting ring (312) is connected to the sampling port (32).

3. The constant speed sampling control system according to claim 2, characterized in that: The adjustment ring (312) is provided with at least one adjustment track (312-1); The sampling port (32) comprises at least two blades (321) and a bracket (322), and the blades (321) are movably connected to the bracket (322); At least one of the blades (321) is provided with a protrusion (321-1), and the protrusion (321-1) is clamped in the adjustment track (312-1).

4. The constant speed sampling control system according to claim 2, characterized in that: The actuator comprises a motor (4) and a transmission mechanism (5), wherein the motor (4) is connected to the transmission mechanism (5) to drive the sampling probe (3) to retract and change its diameter.

5. The constant speed sampling control system according to claim 4, characterized in that: The motor (4) comprises a first motor (41), the transmission mechanism (5) comprises a feeding mechanism (51) connected to the first motor (41) and a transmission rod (52) connected to the feeding mechanism (51), and the other end of the transmission rod (52) is connected to the sampling probe (3) to drive the sampling probe (3) to retract axially along the transmission rod (52).

6. The constant speed sampling control system according to claim 4, characterized in that: The motor (4) comprises a second motor (42), and the second motor (42) is connected to the adjustment gear (311) to drive the sampling probe (3) to change its diameter.

7. The constant speed sampling control system according to claim 1, characterized in that: The sensor comprises an optical particle flow meter. When the optical particle flow meter is used to calculate the flow data in the sampling pipeline (1), the following steps are included: S11. Calculate the flow velocity v of the fluid by measuring the time it takes for the fluid to pass through the light beam and the geometric parameters of the optical detection area: Where, v is the calculated fluid velocity, in m / s; L is the effective detection length of the light beam or the length of the measurement area, in m; t is the time it takes for the fluid to pass through the light beam area, in s; S12. Calculate the flow rate in the sampling pipeline (1) according to the flow velocity v of the fluid: NQ=3600·v·A Where NQ is the average standardized air flow rate in the sampling pipeline, in Nm 3 / h, A is the cross-sectional area of ​​the pipe, in m 2 .

8. The constant speed sampling control system according to claim 1, characterized in that: The controller calculates the constant speed sampling ratio according to the following formula: Where IR is the constant speed sampling ratio; NQ s is the average standardized air flow rate in the sampling probe (2), in Nm 3 / h, which is set by the analyzer (6) connected to the sampling probe (2) and is a constant; NQ is the average standardized air flow rate in the sampling pipeline, in Nm 3 / h;d i is the inner diameter of the sampling pipe (1), in mm, and is a fixed value; d n is the inner diameter of the sampling probe (3), in mm, and is the adjustment value.

9. The constant speed sampling control system according to claim 8, characterized in that: When IR>1.15, the controller issues an instruction to enlarge the inner diameter of the sampling probe (3); when IR<0.9, the controller issues an instruction to reduce the inner diameter of the sampling probe (3); when 0.9≤IR≤1.15, the controller does not issue an instruction; Preferably, the inner diameter size d of the sampling probe (3) is n Calculate according to the following formula: In the formula, when IR is 0.9, NQ s When / NQ takes the maximum value that the system can adjust, the calculated d n1 is the inner diameter of the largest sampling probe (3); when IR is 1.15, NQ s When / NQ takes the minimum value that the system can adjust, the calculated d n2 is the inner diameter of the minimum-specification sampling probe (3); The actuator receives a diameter change instruction of the sampling probe (3) from the controller, and moves the sampling probe (3) to the actuator at d n1 With d n2 Within the inner diameter range, the inner diameter of the sampling probe (3) is adjusted.

10. The constant speed sampling control system according to claim 1, characterized in that: The sampling probe (3) is made of electroplated and polished stainless steel; 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, 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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