Active horizontal piston disk gas flow standard device and test method

Abstract

The present application relates to the field of gas flow standard device, especially to active horizontal disc-shaped piston gas flow standard device and testing method.The technical scheme is as follows: the active horizontal disc-shaped piston gas flow standard device includes driving module, guide module, metering module and control system module, the driving module includes servo motor, coupling and ball screw, the servo motor is connected with the ball screw through the coupling, the ball screw is provided with screw nut, and the screw nut is connected with the piston disc support rod.Through the structural design of horizontal disc-shaped piston and balance cavity, the gas pressure difference on both sides of the piston is offset, the load of the driving unit is reduced, the operation efficiency and service life of the device under high pressure working condition are improved, the sealing reliability of the sealing assembly is enhanced, gas leakage is prevented, the sealing state is diagnosed in real time and safety protection is provided when abnormal, and the long-term stability of gas flow output, the safety of device operation and the accuracy of measurement results are ensured.

Description

Technical Field

[0001] This invention relates to the field of gas flow standard devices, and more particularly to an active horizontal disc piston gas flow standard device and testing method. Background Technology

[0002] Piston-type gas flow standard devices belong to the volumetric method and are based on the dynamic measurement principle. The core components of this device are the piston body and piston cylinder. The piston moves at a constant speed in a linear motion, displacing air from the piston cylinder and introducing it into the flow meter under test, thus enabling the measurement of the flow meter. Depending on the piston's measuring components, piston-type gas flow standard devices can be divided into disc-type piston gas flow standard devices and cylindrical piston gas flow standard devices.

[0003] In the field of gas flow standard devices, the active disc piston gas flow standard device is a common gas flow metering equipment. This device uses a drive unit to move a piston, thereby continuously generating a stable and adjustable gas flow rate during the smooth movement of the piston, used for calibrating flow meters and other flow instruments. Traditional active piston gas flow standard devices typically consist of a single piston cylinder with a metering chamber inside. The movement of the piston disc changes the volume of the metering chamber, discharging gas and achieving precise control of the gas flow rate.

[0004] However, existing technologies have significant shortcomings. When measuring high-pressure (greater than 0.4 MPa) flow meters, the inconsistent gas pressure at both ends of the piston disc causes an unnecessary load on the drive unit due to the gas reaction force, leading to increased power demand and a shortened drive unit lifespan. The presence of this reaction force can also cause instability in the gas flow output. Due to the mechanical structure of the horizontal disc piston, its own weight directly acts on the sealing interface, easily causing a decrease in piston sealing performance. Traditional devices struggle to meet the stability and accuracy requirements for high-pressure flow measurement, failing to adapt to the needs of modern high-precision flow metering. Summary of the Invention

[0005] This invention proposes an active horizontal disc piston gas flow standard device and testing method, which solves the problems of unstable airflow, small pressure adjustment range, and the inability to perform metrological verification and calibration of small and medium flow meters under operating pressure conditions in the prior art.

[0006] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows: An active horizontal disc piston gas flow standard device includes a drive module, a guide module, a metering module, and a control system module; The drive module includes a servo motor, a coupling, and a ball screw. The servo motor is connected to the ball screw via the coupling, and a screw nut is provided on the ball screw. The guiding module includes a guide rail, a first linear bearing, a lead screw slider, a piston disc support rod, and a second linear bearing. The lead screw slider is connected to the piston disc support rod, and the lead screw nut is fixedly connected to the lead screw slider. The piston disc support rod is fixed to the piston disc through the first linear bearing and the second linear bearing. The piston disc is disposed in the metering cylinder. The second linear bearing is sealed by a first sealing ring. The metering module includes a metering cylinder body, a front cylinder head, and a rear cylinder head. The piston disc is disposed in the metering cylinder body and its interior is divided into a balance chamber and a metering chamber. A combined seal is provided between the piston disc and the metering cylinder, and the combined seal includes multiple sealing rings.

[0007] Furthermore, the combined sealing element includes a second sealing ring, and multiple second sealing rings are provided between the piston disc and the metering cylinder. A sealing cavity is also formed between the multiple second sealing rings. The sealing cavity is connected to a pressure detection tap, which is connected to a differential pressure sensor and a gauge pressure sensor. Furthermore, two guide rings are symmetrically installed on both sides of the outer surface of the piston disc, and the guide rings are made of high-strength wear-resistant composite material.

[0008] Furthermore, the control system module includes a measurement module, a data acquisition module, a communication module, a control module, a power supply module, and host computer software; The measurement module includes two differential pressure sensors and a gauge pressure sensor. The first differential pressure sensor is used to monitor the pressure difference between the two sealed cavities, and the gauge pressure sensor is used to monitor the pressure inside the sealed cavity. The second differential pressure sensor is connected between the metering cavity and the balancing cavity.

[0009] Furthermore, the device supports switching between two specifications: 30L and 500L disc pistons.

[0010] A test method for the above-mentioned active horizontal disc piston gas flow standard device includes the following steps: Step 1: Supply air to the flow meter under test to pre-run it at the target flow rate; Step 2: Start the servo motor to drive the piston disk to reset to the starting position; Step 3: Calculate the target piston speed based on the target flow rate and the cross-sectional area of ​​the piston cylinder, and set the initial parameters of the PID controller using a method based on genetic algorithm (GA) optimization. Step 4: Drive the piston to move. After the piston reaches the target flow rate, close the balance valve between the piston balance chamber and the metering chamber, and start PID regulation. Step 5: Monitor the pressure difference Δp between the balance chamber and the metering chamber in real time, input it into the PID controller for closed-loop regulation, and use a state recognition model based on long short-term memory neural network LSTM to determine whether the system is in a stable or disturbed state. Step Six: When in a disturbed state, automatically activate the fuzzy controller to adjust the output of the PID controller; Step 7: After the pressure difference Δp between the balancing chamber and the metering chamber approaches zero and reaches equilibrium, perform the formal flow rate verification; Step 8: By constructing a mathematical model, the precise conversion from volumetric flow rate to mass flow rate is achieved.

[0011] Furthermore, the initial parameters of the PID controller are obtained through optimization using a genetic algorithm (GA). This genetic algorithm is based on piston metering cylinder parameters and historical calibration data. It encodes the proportional coefficient Kp, integral coefficient Ki, and derivative coefficient Kd into genetic individuals for iterative evolution. The optimization objectives include steady-state error, differential pressure fluctuation, and settling time.

[0012] Furthermore, the specific operation of the closed-loop regulation is as follows: the pressure difference Δp between the balance chamber and the metering chamber is used as the input of the PID controller, and the controller operates according to the formula; Calculate the output u(t) and use u(t) to adjust the speed of the servo motor (1) in real time.

[0013] Furthermore, the fuzzy controller has a single-input, three-output structure. The input variable is the pressure difference ΔP between the balance chamber and the metering chamber, and the output variable is the correction amount for the proportional coefficient Kp, integral coefficient Ki, and derivative coefficient Kd of the PID controller.

[0014] Furthermore, the fuzzy controller divides the input variable ΔP into multiple fuzzy linguistic variables and uses the Mamdani inference model and centroid method to resolve the fuzziness. The mass flow rate is calculated according to the formula calculate.

[0015] The positive effects of this invention are as follows: Through the structural design of a horizontal dual-chamber disc piston and a balance chamber, a balance chamber is added to the traditional metering chamber, effectively offsetting the gas pressure difference on both sides of the piston, significantly reducing the load on the drive unit, and improving the operating efficiency and lifespan of the device under high-pressure conditions. Its multi-layer combined sealing structure, combined with a dynamic pressure monitoring mechanism, not only greatly enhances sealing reliability and prevents gas leakage, but also diagnoses the sealing status in real time and provides safety protection in case of abnormalities, thereby fundamentally ensuring the long-term stability of gas flow output, the safety of device operation, and the accuracy of measurement results.

[0016] Furthermore, this invention introduces a multi-layered intelligent control strategy combining genetic algorithm optimization, long short-term memory neural network state recognition, and fuzzy control. This strategy can adaptively tune control parameters, accurately determine the system's operating state, and intelligently intervene when disturbances occur, making the system more robust to external disturbances and changes in internal parameters. By constructing a mathematical model, the precise conversion from volumetric flow rate to mass flow rate is achieved. Ultimately, high-precision and high-stability control of gas flow rate is realized across the entire flow range, meeting the stringent requirements of modern high-precision gas flow metering. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the active horizontal disc piston gas flow standard device of the present invention; Figure 2 This is a schematic diagram of the sealing structure in the active horizontal disc piston gas flow standard device of the present invention; In the picture: 1. Servo motor; 2. Coupling; 3. Connecting support plate; 4. Ball screw; 5. Guide rail; 6. Screw nut; 7. First linear bearing; 8. Screw slider; 9. Piston disc support rod; 10. Second linear bearing; 11. Front cylinder head; 12. First sealing ring; 13. Metering cylinder; 14. Support ring; 15. Combined seal; 16. Piston disc; 17. Cylinder head connecting rod; 18. Rear cylinder head; 19. Pressure detection tap; 20. Guide ring; 21. Second sealing ring. Detailed Implementation

[0018] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0019] Example 1 In this embodiment, the specific parameters of the disc piston are as follows: The flow rate range for the 30L disc piston is (1.5~30) L / min, and the flow rate range for the 500L disc piston is (25~500) L / min. The pressure range is (0.1~0.6) MPa, and the expanded uncertainty is better than 0.1% (k=2).

[0020] like Figure 1 As shown, this embodiment provides an active horizontal disc piston gas flow standard device, including: a drive module, a guide module, a control system module, a piston assembly, and a sealing and metering module.

[0021] The drive module includes a servo motor 1, a coupling 2, and a ball screw 4. The servo motor 1 is connected to the ball screw 4 via the coupling 2, and is used to convert the rotational motion of the motor into high-precision linear motion of the piston assembly.

[0022] The connecting support module consists of a connecting support plate 3, which is located between the ball screw and the piston transmission structure to support the transmission components and maintain overall rigidity and stability.

[0023] The guiding module consists of a guide rail 5, a first linear bearing 7, and a lead screw slider 8, which provides precise rigid guidance for the piston disc support rod 9, ensuring that the piston disc 16 moves axially in a linear fashion within the metering cylinder 13, avoiding offset or vibration, and improving the stability of flow output.

[0024] The piston assembly includes a lead screw nut 6, a piston disc support rod 9, and a piston disc 16. The lead screw nut 6 is threadedly engaged with a ball screw 4, and drives the piston disc support rod 9 to move linearly through the lead screw slider 8, thereby realizing the reciprocating movement of the piston disc 16 within the metering cylinder 13.

[0025] The metering module consists of a metering cylinder body 13, a front cylinder head 11, a rear cylinder head 18, and a cylinder head connecting rod 17. The piston disc 16 fits tightly with the metering cylinder body 13, dividing the internal space of the metering cylinder body 13 into a balance chamber and a metering chamber. The cylinder head connecting rod 17 is used to fix and seal the front and rear cylinder head structures.

[0026] To ensure airtightness and smooth operation, a combined seal 15 is installed between the piston disc 16 and the metering cylinder 13. The sealing structure further includes a first sealing ring 12 and a support ring 14 to prevent gas leakage and withstand gas pressure differences. A pressure monitoring tap is provided on one side of the metering chamber for connection with a differential pressure sensor and a gauge pressure sensor. Dynamic monitoring of the pressure difference between the two sealed chambers and changes in the pressure within the sealed chambers ensures the device's airtightness.

[0027] Example 2 like Figure 2 As shown, based on Embodiment 1, this embodiment provides a highly reliable sealing structure suitable for an active horizontal disc piston gas flow standard device. This sealing structure mainly consists of a metering cylinder 13, a piston disc 16, a second sealing ring 21, a guide ring 20, and a pressure detection tap 19, aiming to improve the sealing performance and motion stability of the piston under high pressure and long stroke conditions.

[0028] The piston disc 16 is disposed within the metering cylinder 13 and is axially slidingly fitted with the metering cylinder 13. To ensure sealing reliability and gas leakage control, multiple second sealing rings 21, which are cap-shaped sealing rings, are provided on the outer edge of the piston disc 16. The piston disc 16 has two guide rings 20 on both sides, and a dustproof ring on the outer side of the piston disc 16, forming a multi-layer combined sealing structure design, which has the characteristics of low friction, low starting resistance, and smooth movement.

[0029] The second sealing ring 21 is installed in the sealing groove on the piston disc, effectively preventing high-pressure gas from leaking outwards through the sealing area. Simultaneously, a sealing cavity is provided between the sealing rings. This cavity is connected to a differential pressure sensor and a gauge pressure sensor via a pressure detection port 19. The differential pressure sensor monitors the gas pressure difference between the two sealing rings in real time, while the gauge pressure sensor monitors pressure changes within the sealing cavity. When the differential pressure or gauge pressure exceeds a set threshold, the control system automatically triggers an alarm and implements a shutdown protection operation. The measurement module includes two differential pressure sensors and a gauge pressure sensor. The first differential pressure sensor monitors the pressure difference between the two sealing cavities, and the gauge pressure sensor monitors the pressure within the sealing cavity. The second differential pressure sensor is connected between the metering cavity and the balancing cavity.

[0030] To further improve the guiding accuracy of the piston disc, a guide ring 20 is provided between the piston disc 16 and the metering cylinder 13. The guide ring 20 is made of high-strength wear-resistant composite material, which can withstand the lateral force during piston movement, while reducing the direct contact between the piston and the metering cylinder 13, reducing wear, and improving movement stability.

[0031] Example 3 Based on Examples 1 and 2, this example proposes a test method for an active horizontal disc piston gas flow standard device. The test object is mainly a high-pressure flow meter, with a pressure loss typically ranging from 10 to 100 kPa (constant flow method). The method involves the following steps: (1) Supply air to the flow meter under test so that the flow meter under test is in a pre-operation state with the target flow rate.

[0032] (2) Start the servo motor 1. The servo motor 1 drives the ball screw 4 to rotate at a stable speed, so that the piston disc returns to the starting position.

[0033] (3) Calculate the target piston speed according to the target flow rate of the flow meter under test and the cross-sectional area of ​​the piston cylinder, initially set the speed of the servo motor, and set it as the initial set value of the PID controller. (4) The servo motor 1 drives the ball screw 4 to rotate at a stable speed. The ball screw 4 drives the piston disc to move to the right. The reading head of the grating ruler moves synchronously with the piston disc. When the flow rate output by the piston reaches the target flow rate of the flow meter under test, the pneumatic valve between the balance chamber and the metering chamber is closed, and the PID regulation of the piston device is started. When the pressure difference Δp between the balance chamber and the metering chamber of the piston approaches zero, the verification and calibration work begins.

[0034] (5) The computer control system monitors the pressure difference Δp between the piston's balance chamber and metering chamber in real time, determines whether the horizontal disc-shaped double piston gas flow standard device is in a stable or disturbed state, and inputs it into the PID controller for closed-loop regulation.

[0035] (6) When the horizontal disc-shaped double piston gas flow standard device is in a disturbed state, the fuzzy controller is automatically activated to adjust the output of the PID controller; (7) When the pressure difference Δp approaches zero, the dual-chamber disc piston gas flow standard device begins the formal flow calibration process.

[0036] Example 4 Based on Example 3, the initial setpoint of the PID controller in the aforementioned test method is specifically as follows: The initial settings are designed using a PID parameter design method based on genetic algorithm (GA). This PID parameter design method is based on the parameters of the piston metering cylinder 13 and the flow control data from the historical calibration process. It constructs a multi-objective fitness function and encodes the proportional coefficient Kp, integral coefficient Ki, and derivative coefficient Kd of the PID controller as genetic individuals. The global optimization of the parameter set is achieved through an iterative evolution process. The optimization objectives include: minimizing the system's steady-state error, minimizing differential pressure fluctuations, and minimizing the settling time; Genetic algorithms (GA) iteratively obtain PID parameter combinations through population initialization, fitness evaluation, selection, crossover, and mutation operations, and use them as the initial controller configuration for the control system.

[0037] Example 5 Based on Example 4, the specific operation of the closed-loop adjustment in the aforementioned test method is as follows: (1) Compare the measured actual flow rate with the target flow rate, and automatically adjust the servo motor speed according to the error to minimize the error; (2) Differential pressure monitoring: Real-time acquisition of the differential pressure Δp between the piston's balance chamber and metering chamber; (3) The pressure difference Δp is used as the input to the PID controller and enters the regulation algorithm. The PID controller is adjusted according to the following formula. In the formula, Kp, Ki, and Kd are the proportional, integral, and differential coefficients obtained by the genetic algorithm optimization; For controller output; To integrate the flow error Δp ​​along the time axis; It is the first derivative of the pressure difference Δp with respect to time; (4) The output u(t) is used to adjust the speed of the servo motor in real time, thereby changing the pushing speed of the piston disc driven by the ball screw; (5) After adjustment, measure the pressure difference Δp between the piston's balance chamber and metering chamber in real time, and adjust the speed of the servo motor in real time to form a continuous feedback loop until the pressure difference Δp approaches 0 or enters the allowable error range.

[0038] Example 6 The test method for a horizontal disc-shaped double piston gas flow standard device, specifically determining whether the horizontal disc-shaped double piston gas flow standard device is in a stable or disturbed state, is as follows: A state recognition model based on Long Short-Term Memory (LSTM) neural network is used to learn and classify continuously collected data to determine the current state of the system. When the pressure difference ΔP < 5Pa and the stabilization time is 5s, the system is determined to be in a stable state and enters an effective metering cycle. When the pressure difference ΔP is still in the process of convergence, the parameter fluctuations gradually slow down, the system is judged to be in a transition state, and the system continues to adjust but does not perform measurement. If a sudden change in pressure or a large jump in temperature occurs, the system determines it to be a disturbance state and immediately activates the fuzzy control intervention module to correct the output of the PID controller.

[0039] Example 7 Based on Example 6, the testing method for the horizontal disc-shaped double-piston gas flow standard device uses a fuzzy controller with a single-input, three-output structure. Its input variables include the pressure difference ΔP between the balance chamber and the metering chamber. This variable is divided into seven fuzzy linguistic variables: NB, NM, NS, ZO, PS, PM, and PB. The membership function type is a symmetric triangular function. The pressure difference ΔP is adapted to the input space of the fuzzy controller, and a linear normalization method is used to map the physical quantity to the range [−3, +3]. The typical variation range of the pressure difference ΔP is ±5 Pa, and the normalization function is: ; ; The output variables are the correction values ​​for three parameters of the current PID controller: proportional coefficient Kp, integral coefficient Ki, and derivative coefficient Kd; there are 49 fuzzy control rules, the fuzzy inference uses the Mamdani model, and the centroid method is used for defuzzification; the final output correction value is combined with the original PID parameters to control the speed of the servo motor.

[0040] Example 8 Based on Example 7, after the pressure of the horizontal disc-shaped double piston gas flow standard device stabilizes, it enters the verification and calibration state. Considering that the pressure applicable range of this device is (0.1~0.6) MPa, the influence of the compressibility factor cannot be ignored. By constructing a mathematical model, the accurate conversion of volumetric flow rate to mass flow rate is completed.

[0041] Volumetric flow rate q of the piston device under standard conditions s for: ; Mass flow rate q m According to the formula: calculate; The compressibility factor Z is calculated using the formula: calculate.

[0042] In the formula: a0, a1, a2, b0, b1, c0, c1, d, and e are constants, where a0 = 1.58123 × 10 -6 kPa -1 a1 = -2.9331 × 10 -8 Pa -1 a2 = 1.1043 × 10 -10 K -1 Pa -1 b0 = 5.707 × 10 -6 kPa -1 b1 = -2.051 × 10 -8 Pa -1 c0 = 1.9898 × ​​10 -4 kPa -1 c1 = -2.376 × 10 -6 Pa -1 d = 1.83 × 10 -11 K 2 Pa -2 e = -0.765 × 10 -8 K 2 Pa -2 .

[0043] The above-described embodiments are detailed and specific, illustrating preferred embodiments of the present invention. They are only used to illustrate the technical ideas and features of the present invention, with the aim of enabling those skilled in the art to understand the content of the present invention and implement it accordingly. However, they are not limited to the present invention, and the patent scope of the present invention cannot be limited by this embodiment alone. That is, any equivalent changes or modifications made to the spirit disclosed in the present invention, without departing from the structure of the present invention, such as local improvements within the system and modifications or transformations between subsystems, are still within the patent scope of the present invention.

Claims

1. An active horizontal disc piston gas flow standard device, comprising a drive module, a guide module, a metering module, and a control system module, characterized in that: The drive module includes a servo motor (1), a coupling (2) and a ball screw (4). The servo motor (1) is connected to the ball screw (4) through the coupling (2). A screw nut (6) is provided on the ball screw (4). The guiding module includes a guide rail (5), a first linear bearing (7), a lead screw slider (8), a piston disc support rod (9), and a second linear bearing (10). The lead screw slider (8) is connected to the piston disc support rod (9), and the lead screw nut (6) is fixedly connected to the lead screw slider (8). The piston disc support rod (9) is fixed to the piston disc (16) through the first linear bearing (7) and the second linear bearing (10). The piston disc (16) is located inside the metering cylinder (13). The second linear bearing (10) is sealed by the first sealing ring (12). The metering module includes a metering cylinder (13), a front cylinder head (11) and a rear cylinder head (18). The piston disc (16) is disposed inside the metering cylinder (13) and its interior is divided into a balance chamber and a metering chamber. A combined seal (15) is provided between the piston disc (16) and the metering cylinder (13), the combined seal (15) comprising multiple sealing rings.

2. The active horizontal disc piston gas flow standard device according to claim 1, characterized in that: The combined seal (15) includes a second sealing ring (21). Multiple second sealing rings (21) are provided between the piston disc (16) and the metering cylinder (13), and a sealing cavity is also formed between the multiple second sealing rings (21). The sealing cavity is connected to a pressure detection tap (19), and the sealing cavity is connected to a differential pressure sensor and a gauge pressure sensor through the pressure detection tap (19).

3. The active horizontal disc piston gas flow standard device according to claim 2, characterized in that: Two guide rings (20) are symmetrically installed on both sides of the outer surface of the piston disc (16), and the guide rings (20) are made of high-strength wear-resistant composite material.

4. The active horizontal disc piston gas flow standard device according to claim 1, characterized in that: The control system module includes a measurement module, a data acquisition module, a communication module, a control module, a power supply module, and host computer software. The measurement module includes two differential pressure sensors and a gauge pressure sensor. The first differential pressure sensor is used to monitor the pressure difference between the two sealed cavities, and the gauge pressure sensor is used to monitor the pressure inside the sealed cavity. The second differential pressure sensor is connected between the metering cavity and the balancing cavity.

5. The active horizontal disc piston gas flow standard device according to claim 1, characterized in that: The device supports switching between two specifications: 30L and 500L disc pistons.

6. A test method for an active horizontal disc piston gas flow standard device as described in any one of claims 1-5, characterized in that, Includes the following steps: Step 1: Supply air to the flow meter under test to pre-run it at the target flow rate; Step 2: Start the servo motor (1) to drive the piston disk (16) to reset to the starting position; Step 3: Calculate the target piston speed based on the target flow rate and the cross-sectional area of ​​the piston cylinder, and set the initial parameters of the PID controller using a method based on genetic algorithm (GA) optimization. Step 4: Drive the piston to move. After the piston reaches the target flow rate, close the balance valve between the piston balance chamber and the metering chamber, and start PID regulation. Step 5: Monitor the pressure difference Δp between the balance chamber and the metering chamber in real time, input it into the PID controller for closed-loop regulation, and use a state recognition model based on long short-term memory neural network LSTM to determine whether the system is in a stable or disturbed state. Step Six: When in a disturbed state, automatically activate the fuzzy controller to adjust the output of the PID controller; Step 7: After the pressure difference Δp between the balancing chamber and the metering chamber approaches zero and reaches equilibrium, perform the formal flow rate verification; Step 8: By constructing a mathematical model, the precise conversion from volumetric flow rate to mass flow rate is achieved.

7. The test method according to claim 6, characterized in that: The initial parameters of the PID controller are obtained by the genetic algorithm GA. The genetic algorithm is based on the parameters of the piston metering cylinder (13) and historical calibration data. The proportional coefficient Kp, integral coefficient Ki, and derivative coefficient Kd are encoded as genetic individuals for iterative evolution. The optimization objectives include steady-state error, differential pressure fluctuation and adjustment time.

8. The test method according to claim 6, characterized in that: The specific operation of the closed-loop regulation is as follows: the pressure difference Δp between the balance chamber and the metering chamber is used as the input of the PID controller, and the controller operates according to the formula. Calculate the output u(t) and use u(t) to adjust the speed of the servo motor (1) in real time.

9. The test method according to claim 6, characterized in that: The fuzzy controller has a single-input, three-output structure. The input variable is the pressure difference ΔP between the balance chamber and the metering chamber, and the output variable is the correction amount for the proportional coefficient Kp, integral coefficient Ki, and derivative coefficient Kd of the PID controller.

10. The test method according to claim 9, characterized in that: The fuzzy controller divides the input variable ΔP into multiple fuzzy linguistic variables and uses the Mamdani inference model and centroid method to resolve the fuzziness. The mass flow rate is calculated according to the formula calculate.

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