Aging test box and humidity control method of the aging test box

Abstract

The present invention discloses an aging test box and a humidity control method for the aging test box, wherein the aging test box includes an ultrasonic humidification device, an air blowing device, a test box working room, a control device and a humidity sensor, and the control device is connected to the ultrasonic humidification device and the humidity sensor respectively; the ultrasonic humidification device is used to generate mechanical vibration to break up water molecules and generate water mist; the air blowing device is used to input the water mist into the test box working room; the humidity sensor is used to collect humidity parameters in the test box working room and transmit the humidity parameters to the control device; the control device is used to control the working state of the ultrasonic humidification device in combination with the humidity parameters and the humidity threshold. The present invention uses an ultrasonic humidification device to break up water molecules to generate water mist, thereby improving the test accuracy of the aging test box, and has a simple working principle, lower cost, smaller size and higher safety, and can be widely used in the field of weather resistance test detection.

Description

Technical Field

[0001] The invention relates to the field of weather resistance test detection, and in particular to an aging test box and a humidity control method of the aging test box. Background Art

[0002] The weather resistance test of xenon lamps or other lamps is an important means to screen formulas and optimize product composition in the process of scientific research and production, and is also an important part of product quality inspection. Product standards for application materials such as coatings, plastics, aluminum-plastic panels, and automotive safety glass all require weather resistance tests. The main factors that cause material aging simulated by the xenon lamp weathering test chamber are sunlight and humidity. The weather resistance test machine can simulate the harmful environment caused by sunlight, rain and dew. The xenon lamp weathering test chamber uses xenon lamps to simulate the effect of sunlight, and uses condensed moisture to simulate rain and dew. The tested material is placed in a cycle program of alternating light and moisture at a certain temperature for testing. It takes a few days or weeks to reproduce the hazards that occur outdoors for months or even years. The artificial accelerated aging test data can help select new materials, improve existing materials, and evaluate how changes in formulas affect the durability of products.

[0003] At present, the mainstream aging equipment in the world, such as temperature and humidity aging chambers, light aging chambers (xenon lamp aging chambers, ultraviolet aging chambers), etc., not only involve the control of temperature, irradiance and other conditions, but also involve the control requirements of humidity parameters. For the current mainstream aging chambers, two methods are usually used for humidification. The first is aerosol humidification. The main principle is that a high-speed airflow generated by a pressurized air pump through an air pipe hits the water flow of another water pipe to produce atomized particles, which then enter the test chamber air circulation; the second is to humidify the vaporized water mist obtained by evaporating water vapor. There are currently the following problems with the first humidification method: 1. The cost of raw materials for the equipment is high, and air compressors and pressurized water pumps are required to generate water mist; 2. A large installation space is required, and a large space is required to install the internal area of ​​the aging chamber. It is not conducive to internal heat dissipation. It greatly increases the volume of the overall aging chamber; 3. Once a failure occurs or the high-pressure air pipe or pipeline connection is damaged or leaked, it is easy to cause a safety accident with greater danger. The second humidification method currently has the following problems: during the humidification process, water needs to be heated and evaporated by heating wire to obtain water vapor. Since the water vapor generated after heating has a high temperature, its own temperature will enter the working room as a variable factor, causing the temperature and humidity parameters in the working room of the aging box to fluctuate, greatly affecting the accuracy of the detection. Currently, there is no equipment that can solve the above problems. Summary of the invention

[0004] In order to solve the above technical problems, the purpose of the present invention is to provide an aging test chamber with low cost, small size, higher safety and higher detection accuracy.

[0005] Another object of the present invention is to provide a humidity control method with higher accuracy.

[0006] The technical solution adopted by the present invention is:

[0007] An aging test chamber, comprising an ultrasonic humidifying device, a blasting device, a test chamber working room, a control device and a humidity sensor arranged in the test chamber working room, wherein the control device is connected to the ultrasonic humidifying device and the humidity sensor respectively;

[0008] The ultrasonic humidification device is used to generate mechanical vibration to break up water molecules and generate water mist;

[0009] The blowing device is used to input water mist into the test chamber working room;

[0010] The humidity sensor is used to collect humidity parameters in the test chamber working room and transmit the humidity parameters to the control device;

[0011] The control device is used to control the working state of the ultrasonic humidification device in combination with the humidity parameter and the preset humidity threshold.

[0012] Furthermore, the ultrasonic humidification device includes an ultrasonic generator, an ultrasonic atomization sheet, a transducer and a DC regulated power supply for powering the ultrasonic humidification device, and the transducer is connected to the ultrasonic generator and the ultrasonic atomization sheet respectively.

[0013] Furthermore, the test chamber working room is provided with an external air inlet and outlet and a circulation switch for controlling the opening and closing of the external air inlet and outlet.

[0014] Furthermore, the control device includes a PID regulator, and the PID regulator is used to control the working state of the ultrasonic humidification device in combination with the humidity parameter, the preset humidity threshold value and the parameters of the PID regulator.

[0015] Furthermore, it also includes a temperature sensor, which is installed in the working room of the test box and is connected to the control device.

[0016] Another technical solution adopted by the present invention is:

[0017] A humidity control method for an aging test chamber comprises the following steps:

[0018] Get the humidity parameters in the test chamber working room;

[0019] The humidity parameters and the PID regulator optimized by genetic algorithm are combined to control the working state of the ultrasonic humidification device, and indirectly control the humidity in the test chamber studio.

[0020] Further, the method also includes the step of establishing a PID regulator, which specifically includes the following steps:

[0021] Obtain the critical proportional gain and oscillation period of the PID regulator, and establish the PID regulator according to the critical proportional gain and oscillation period;

[0022] Genetic algorithm is used to optimize the parameters of PID regulator.

[0023] Furthermore, a decoupling step is also included, which specifically includes the following steps:

[0024] Obtain the temperature parameters in the working room of the test chamber;

[0025] The temperature and humidity of the test chamber studio are decoupled by combining humidity parameters, temperature parameters and a preset decoupling method.

[0026] Further, the step of optimizing the parameters of the PID regulator by using a genetic algorithm specifically comprises the following steps:

[0027] Combine the genetic algorithm and the three parameters of the PID regulator to evaluate the PID regulator as a whole and obtain the evaluation value;

[0028] The quality information of the parameters of the PID regulator is judged according to the evaluation value, and the parameters are preset iteratively processed according to the quality information until the quality information of the parameters meets the preset requirements.

[0029] The beneficial effects of the present invention are as follows: the present invention uses an ultrasonic humidification device to break up water molecules to generate water mist, and increases the humidity in the test chamber working room through the water mist, thereby solving the problem that the temperature of the test chamber working room is increased by using water vapor humidification, which affects the accuracy of the test, and improves the test accuracy of the aging test chamber; a humidity sensor is used to collect the humidity parameters in the test chamber working room in real time, and a control device indirectly adjusts the humidity in the test chamber working room according to the working state of the ultrasonic humidification device of the humidity parameter, thereby forming a closed-loop control and ensuring the stability of the humidity in the test chamber working room; in addition, the ultrasonic humidification device has a simple working principle, lower cost, smaller size and higher safety.

[0030] Another beneficial effect of the present invention is that the present invention uses a genetic algorithm to optimize the PID regulator, obtains the optimal parameters of the PID regulator, and then combines the PID regulator and humidity parameters to control the working state of the ultrasonic humidification device in real time, thereby improving the accuracy of humidity regulation, ensuring the stability of the humidity in the test chamber studio, and making the test results more reliable. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a structural schematic diagram of an aging test box of the present invention;

[0032] Figure 2 is a structural block diagram of an ultrasonic humidification device in a specific embodiment;

[0033] Figure 3 A flow chart of the steps of a humidity control method for an aging test chamber of the present invention;

[0034] Figure 4 Schematic diagram of the self-tuning control structure of the relay type PID regulator in a specific embodiment;

[0035] Figure 5 It is a schematic diagram of the temperature and humidity decoupling structure of the test chamber studio in a specific embodiment. DETAILED DESCRIPTION

[0036] Embodiment 1

[0037] like Figure 1 As shown, this embodiment provides an aging test chamber, including an ultrasonic humidification device 1, a blast device 2, a test chamber working room 3, a control device and a humidity sensor 4 arranged in the test chamber working room 3, wherein the control device is connected to the ultrasonic humidification device 1 and the humidity sensor 4 respectively;

[0038] The ultrasonic humidification device 1 is used to generate mechanical vibration to break up water molecules and generate water mist;

[0039] The blowing device 2 is used to input water mist into the test chamber working room 3;

[0040] The humidity sensor 4 is used to collect humidity parameters in the test chamber working room 3 and transmit the humidity parameters to the control device;

[0041] The control device is used to control the working state of the ultrasonic humidification device 1 in combination with the humidity parameter and the preset humidity threshold.

[0042] The ultrasonic humidification device 1 is used to generate high-frequency oscillation to break up water molecules and produce naturally floating water mist, wherein the frequency of the oscillation is 1.7MHz or 2.4MHz, and the water mist enters the test chamber 3 along with the air circulation formed by the operation of the blower 2, thereby increasing the humidity in the test chamber 3, and the humidity sensor 4 collects the humidity parameters in the test chamber 3 in real time, and transmits the humidity parameters to the control device, and the control device regulates the working state of the ultrasonic humidification device 1 in combination with the humidity parameters and the preset humidity threshold value, for example, when the humidity in the test chamber 3 is less than the humidity threshold value, the ultrasonic humidification device 1 is controlled to start working and increase the humidity in the test chamber 3. In this embodiment, the humidity is increased by generating water mist by the ultrasonic humidification device 1, and the temperature of the water mist will not bring additional temperature to the test chamber 3 like water vapor, so as to avoid the temperature of the test chamber 3 being higher than the preset temperature, which affects the accuracy of the test. The humidity parameters are collected in real time by the humidity sensor 4, and the working state of the ultrasonic humidification device 1 is regulated in real time according to the humidity parameters, so as to form a closed-loop control mechanism to ensure the stability of the humidity in the test chamber 3. In addition, the ultrasonic humidification device 1 uses the ultrasonic principle to produce water mist, which is lower in cost and safer, and the device has a smaller size.

[0043] Reference Figure 2 As a further preferred embodiment, the ultrasonic humidification device 1 includes an ultrasonic generator, an ultrasonic atomization sheet, a transducer and a DC regulated power supply for powering the ultrasonic humidification device 1, and the transducer is respectively connected to the ultrasonic generator and the ultrasonic atomization sheet.

[0044] When the ultrasonic humidification device 1 is working, the ultrasonic generator generates a high-frequency electrical signal, and the transducer converts the electrical energy into mechanical vibrations of the same frequency according to the high-frequency electrical signal. The atomizing plate amplifies the mechanical vibrations, increases the vibration amplitude of the atomizing surface, and generates a lateral standing wave in the direction of the atomizing plate. The sound wave reaches the maximum when it reaches the atomizing plate, and the liquid above the atomizing plate absorbs the vibration energy, thereby achieving atomization. The atomized water vapor is in a natural floating state, and forms an air circulation flow through the blowing device 2 to enter the interior of the aging chamber studio, and then diffusely distributed in the studio. The principle of generating water mist by the ultrasonic humidification device 1 is simple, the equipment cost is low, the operation is safer, and the volume of the equipment used is also small.

[0045] Reference Figure 1 As a further preferred embodiment, the test chamber working room 3 is provided with an external air inlet and outlet 6 and a circulation switch 5 for controlling the opening and closing of the external air inlet and outlet 6.

[0046] An external air inlet and outlet 6 is provided on the test chamber studio 3. When the test chamber studio 3 needs to contact with external air and circulate external air, the external air inlet and outlet 6 is opened by the circulation switch 5. When the test chamber studio 3 only circulates internal air, the external air inlet and outlet 6 is closed by the circulation switch 5, so that the test chamber studio 3 can meet more test requirements.

[0047] As a further preferred embodiment, the control device includes a PID regulator, and the PID regulator is used to control the working state of the ultrasonic humidification device 1 in combination with the humidity parameter, the preset humidity threshold value and the parameters of the PID regulator.

[0048] The working state of the ultrasonic humidification device 1 is regulated by a PID regulator according to humidity parameters, wherein the PID parameters are self-tuned and the humidity threshold is selected according to different test chambers. After comparing the collected humidity parameters with the preset humidity threshold, the working state of the ultrasonic humidification device 1 is controlled by a PWM on-off mode.

[0049] As a further preferred embodiment, it further comprises a temperature sensor, wherein the temperature sensor is installed in the test chamber working room 3 and is connected to the control device.

[0050] In the test chamber studio 3, the coupling of temperature and humidity is a common phenomenon. Sometimes the adjustment of humidity will cause slight changes in temperature. The temperature parameters in the test chamber studio 3 are collected in real time by the temperature sensor, and the temperature parameters are fed back to the control device. The temperature parameters are used as a parameter for the control device to control the operation of the ultrasonic humidification device 1. For example, when the temperature in the test chamber studio 3 drops too quickly, the ultrasonic humidification device 1 is controlled to stop working to avoid large changes in the temperature of the test chamber studio 3, which affects the test results.

[0051] Compared with aerosol humidification, the above-mentioned aging test chamber has greatly reduced the cost of raw materials and greatly reduced the space occupied. Secondly, there is no temperature variable factor introduced by water vapor. In terms of the speed of humidity generation, there is no need to wait for heated water to generate water vapor, so the humidity generation is rapid and the response time is short. Modular assembly method; easy to install, disassemble, and maintain. This aging test chamber can meet the current temperature and humidity aging chamber, light aging chamber and other equipment that require humidity regulation.

[0052] Embodiment 2

[0053] like Figure 3 As shown, this embodiment provides a humidity control method for an aging test chamber, comprising the following steps:

[0054] S1. Obtain the humidity parameters in the test chamber studio;

[0055] S2. Combining humidity parameters with the PID regulator optimized by genetic algorithm to control the working state of the ultrasonic humidification device, indirectly controlling the humidity in the test chamber studio.

[0056] This embodiment optimizes the PID regulator by using a genetic algorithm to obtain the optimal parameters of the PID regulator, and then combines the PID regulator and humidity parameters to control the working state of the ultrasonic humidification device in real time, thereby improving the accuracy of humidity regulation, ensuring the stability of the humidity in the test chamber studio, and making the test results more reliable.

[0057] The method further includes the step of establishing a PID regulator, wherein the step of establishing a PID regulator is specifically as follows:

[0058] A1. Obtain the critical proportional gain and oscillation period of the PID regulator, and establish the PID regulator according to the critical proportional gain and oscillation period.

[0059] A2. Use genetic algorithm to optimize the parameters of PID controller.

[0060] After obtaining the critical proportional gain Kc and oscillation period Tc of the PID regulator, establish the PID regulator according to the critical proportional gain Kc and the oscillation period Tc. The PID regulator in this embodiment uses a relay-type PID regulator. The basic idea of ​​self-tuning of the relay-type PID regulator is to set two modes in the control system: test mode and adjustment mode. In the test mode, the regulator automatically switches to positional regulation, that is, when the measured value is less than the set value, the regulator output is full scale, otherwise it is zero, so that the system oscillates. During the oscillation process, the regulator automatically extracts the characteristic parameters of the controlled object; and in the adjustment mode, the PID controller is first derived from the characteristic parameters of the system, and then the system is adjusted by this controller. The relay-type PID regulator has an autonomous control structure such as Figure 4 As shown. When PID parameter tuning is required, the switch is placed in the adjustment position. After the system establishes a stable limit cycle oscillation according to the relay feedback, the PID parameters can be determined according to the system response characteristics. After the self-tuning calculation is completed, the switch is placed in the adjustment position, and the system enters normal control. Among them, Figure 4 In the formula, R represents the input value and Y represents the output value.

[0061] Wherein, step A2 specifically includes steps A21 to A22:

[0062] A21. Evaluate the PID controller as a whole by combining the genetic algorithm and the three parameters of the PID controller, and obtain the evaluation value.

[0063] A22. The quality information of the parameters of the PID regulator is judged according to the evaluation value, and the parameters are subjected to preset iterative processing according to the quality information until the quality information of the parameters meets the preset requirements.

[0064] The genetic algorithm is used to adjust the parameters of the PID regulator. The optimal or approximately optimal PID control parameters are found through the genetic algorithm based on the mathematical model of the temperature and humidity of the environmental test chamber studio. The genetic algorithm evaluates the PID regulator as a whole based on the three parameters of the PID regulator (i.e., proportion, integral, and derivative). The evaluation value is used as the performance indicator of the genetic algorithm to determine the quality of the PID parameters. The appropriate population is selected based on the quality of the parameters, and the parameters do not need to be initialized, which can meet the time-varying requirements. The genetic algorithm is used to obtain an accurate or approximate optimal solution. The optimization process steps are as follows:

[0065] (1) According to the genetic algorithm, first set the algorithm population N and initialize the population. In this embodiment, N is 30. Set the genetic algorithm crossover probability Pc (taken as 0.9 in this embodiment) and mutation probability Pm (taken as 0.1 in this embodiment), the number of iterations (taken as 100 in this embodiment), etc. Randomly generate the initial population, and the gene expression is K = [KP, KI, KD]. Use binary coding to set the value range of the parameter to be optimized according to the established temperature and humidity model.

[0066] (2) The optimization process of the genetic algorithm is a dynamic process. The overall objective function can generally be in the form of an integral. This objective function is used to measure the adaptability of the individual and avoid excessive output. Therefore, it is necessary to add the square term of the control input to determine the fitness objective function as follows:

[0067]

[0068] Where: w1, w2 and w3 are weights, e(t) is the system error, and tu is the rise time.

[0069] (3) Calculate and save the fitness function f(n) of each generation, perform crossover and mutation operations according to the genetic algorithm, generate new individuals, and calculate the fitness value of the new individuals. Compare whether the fitness of the new individuals is optimal. If it is, replace the optimal value and go to step (4); otherwise, go to step (4).

[0070] (4) The number of iterations is increased by one. It is determined whether the termination condition is met (in this embodiment, the determination is made by the maximum number of iterations). If so, the optimal PID parameters and fitness values ​​are output, and the optimal PID parameters are applied to the controlled object to complete the temperature and humidity control of the test chamber working room; otherwise, the process goes to step (3) to continue the optimization.

[0071] Through the above, the optimal PID parameters can be obtained to better control the humidity and temperature of the test chamber working room and improve the accuracy of the test.

[0072] In the test chamber, the coupling of temperature and humidity is a common phenomenon. Sometimes the adjustment of humidity will cause slight changes in temperature. Therefore, it is necessary to decouple the coupling inside the test chamber. This embodiment uses the estimated decoupling method to decouple the temperature and humidity in the test chamber, and uses the decoupling links α1 and α2 to decouple the temperature and humidity. The decoupling structure used is as follows: Figure 5 As shown. After the two decoupling links of α1 and α1, the actual output of the controller is:

[0073] Ut=Kt[(1-α1)*Ct+α1*Ch], α1=0~1

[0074] Uh=Kh[(1-α2)*Ch+α2*Ct], α2=0~1

[0075] Among them, Ct and Ch represent the output of the temperature and humidity controller; Kt and Kh represent the proportional factors of the temperature and humidity controller; Ut and Uh represent the actual output of the temperature and humidity of the system; α1 and α2 represent the decoupling coefficients of temperature and humidity. When α1 and α2 are 0, it means that there is no coupling between the loops. When α1 and α2 are 1, it means that the loop is in an extreme coupling state. The actual α1 and α2 vary between 0 and 1. The values ​​of α1 and α2 can be determined by experiments. The decoupling link parameters are determined by experimental methods. After a large number of experimental verifications, this embodiment is determined to be 0.261 and α2 is 0.315.

[0076] After decoupling the temperature and humidity of the test chamber working room, the humidity of the test chamber working room can be better controlled, indirectly improving the accuracy of the test.

[0077] The above is a specific description of the preferred implementation of the present invention, but the invention is not limited to the embodiments. Those skilled in the art can make various equivalent modifications or substitutions without violating the spirit of the present invention. These equivalent modifications or substitutions are all included in the scope defined by the claims of this application.

Claims

1. An aging test chamber, characterized in that: It includes an ultrasonic humidifying device, a blasting device, a test chamber working room, a control device, a temperature sensor and a humidity sensor arranged in the test chamber working room, wherein the control device is respectively connected to the ultrasonic humidifying device, the humidity sensor and the temperature sensor; The ultrasonic humidification device comprises an ultrasonic generator, an ultrasonic atomization sheet, a transducer and a DC regulated power supply for powering the ultrasonic humidification device, wherein the transducer is connected to the ultrasonic generator and the ultrasonic atomization sheet respectively; The transducer is used to convert electrical energy into mechanical vibration of the same frequency; The ultrasonic atomizer is used to amplify the mechanical vibration and break up the water molecules to generate water mist; The air blowing device is used to input water mist into the test chamber working room; The humidity sensor is used to collect humidity parameters in the test chamber working room and transmit the humidity parameters to the control device; The temperature sensor is used to collect the temperature parameters in the working room of the test box and feed the temperature parameters back to the control device; The control device is used to control the working state of the ultrasonic humidification device in combination with the humidity parameter and the preset humidity threshold, decouple the temperature and humidity of the test chamber studio in combination with the humidity parameter, the temperature parameter and the preset decoupling method, decouple the temperature and humidity of the test chamber studio by using the estimated decoupling method, decouple the temperature and humidity by using the decoupling links α1 and α2, and the actual output of the controller after the two decoupling links α1 and α2 is: Ut=Kt[(1-α1)*Ct+α1*Ch], α1=0~1; Uh=Kh[(1-α2)*Ch+α2*Ct], α2=0~1; Among them, Ct and Ch represent the output of temperature and humidity controller; Kt and Kh represent the proportional factors of temperature and humidity controller; Ut and Uh represent the actual output of temperature and humidity of the system; α1 and α2 represent the decoupling coefficients of temperature and humidity. When α1 and α2 are 0, it means that there is no coupling between the loops. When α1 and α2 are 1, it means that the loops are in the extreme coupling state. The actual α1 and α2 vary between 0 and 1. The values ​​of α1 and α2 can be determined by experiments, and the decoupling link parameters can be determined by experiments.

2. The aging test chamber according to claim 1, characterized in that: The test box working room is provided with an external air inlet and outlet and a circulation switch for controlling the opening and closing of the external air inlet and outlet.

3. The aging test chamber according to claim 1, characterized in that: The control device comprises a PID regulator, and the PID regulator is used to control the working state of the ultrasonic humidification device in combination with the humidity parameter, the preset humidity threshold value and the parameters of the PID regulator.

4. A humidity control method for an aging test chamber, characterized in that: The following steps are involved: Get the humidity parameters in the test chamber working room; The humidity parameters and the PID regulator optimized by genetic algorithm are combined to control the working state of the ultrasonic humidification device, and indirectly control the humidity in the test chamber studio; It also includes the establishment of a PID regulator, including: Obtaining a critical proportional gain and an oscillation period of a PID regulator, and establishing a PID regulator according to the critical proportional gain and the oscillation period; Genetic algorithm is used to optimize the parameters of PID regulator; Among them, the use of genetic algorithm to optimize the parameters of the PID regulator specifically includes: combining the genetic algorithm and the three parameters of the PID regulator to evaluate the PID regulator as a whole, and obtaining the evaluation value, judging the quality information of the parameters of the PID regulator according to the evaluation value, and performing preset iterative processing on the parameters according to the quality information until the quality information of the parameters meets the preset requirements. The specific steps are as follows: 1) According to the genetic algorithm, first set the algorithm population N and initialize the population, set the genetic algorithm crossover probability Pc and mutation probability Pm, and the number of iterations, randomly generate the initial population, and the gene expression is K = [KP, KI, KD]. Use binary coding and set the value range of the parameters to be optimized according to the established temperature and humidity model; 2) Add the square term of the control input and determine the fitness objective function as follows: Where: w1, w2 and w3 are weights, e(t) is the system error, and tu is the rise time; 3) Calculate and save the fitness function f(n) of each generation, perform crossover and mutation operations according to the genetic algorithm, generate new individuals, calculate the fitness value of the new individuals, compare whether the fitness of the new individuals is optimal, and replace the optimal value if it is; 4) The number of iterations is increased by one to determine whether the end condition is met. If so, the optimal PID parameters and fitness value are output, and the optimal PID parameters are applied to the controlled object to complete the temperature and humidity control of the test chamber studio. Otherwise, go to step 3) to continue optimization; It also includes decoupling steps, including: Obtain the temperature parameters in the working room of the test chamber; The temperature and humidity of the test chamber studio are decoupled by combining humidity parameters, temperature parameters and a preset decoupling method.

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