摘要
针对脉宽调制(pulse width modulation, PWM)变量喷雾系统电磁阀同步启闭造成管路压力波动严重的问题,该研究提出一种基于错相位驱动的压力波动抑制方法,基于C37控制器开发了支持不同相位差驱动的PWM变量控制系统,设计并搭建试验平台,开展PWM变量喷雾系统压力波动特性试验、雾化特性试验及雾滴沉积试验。压力波动试验结果表明,错相位驱动方式有效降低了系统压力波动峰峰值和变异系数,且随着占空比的增加,压力波动降低趋势逐渐缩小。当占空比为20%和70%时,错相位120°的压力波动变异系数(CV)比同相位驱动分别减小66.61%和19.48%。占空比对变异系数影响最小的相位差区间是60°~90°驱动,相位差120°时,不同占空比下系统压力波动CV值均最小;对比试验结果表明,错相位驱动的系统雾滴粒径统计项均略低于同相位驱动,错相位驱动系统的雾滴相对跨度(RS)低于同相位驱动,占空比50%时,RS下降最多,为5.56%;雾滴沉积对比试验结果表明,错相位驱动PWM喷雾系统的雾滴覆盖率变异系数相比同相位驱动方式减小了31.75%,错相位驱动方式可有效改善PWM变量喷药系统低频控制条件下药液沉积均匀性。研究结果可为PWM变量喷雾技术研发与应用提供依据,为精准变量施药装置的进一步优化提供技术支撑。
Variable pesticide application is one of the most important techniques for on-demand spraying.According to the prescription information or the online acquisition of the crop growth and disease occurrence,the forward speed of the unit can be detected to adjust the amount of pesticide application in real-time.The utilization efficiency of the insecticides or herbicides can be maximized to reduce the pollution caused by excessive pesticides to the environment.The residue of pesticide solutions can also be lowered in agricultural products.Among them,the pulse width modulation(PWM)variable spraying has been widely used at present,due to its short reaction time,high response speed,high atomization,and the large range of flow adjustment.Conventional nozzles can also be used to obtain better spray characteristics.However,the frequent hydraulic shocks can be caused by the solenoid valve switches,leading to the serious fluctuation of the pipeline pressure.In this study,a suppression approach was proposed using staggered phase driving.A PWM variable control system was developed to support the various driving modes of the phase difference using a C37 controller.Additionally,a PWM variable spray platform was designed and constructed to incorporate the staggered phase driving.Subsequently,a series of tests were conducted on the PWM variable spray system,including the pressure fluctuation,atomization,and droplet deposition test.The results indicate that the staggered driving effectively reduced the amplitude and the coefficient of variation(CV)of the pressure fluctuation.There was no reduction,as the duty cycle increased.No significant difference was found in the average pressure of the system during phase driving.Once the duty cycle was 20%and 70%,the CV rates of the pressure fluctuation were-66.61%and-19.48%,respectively,for the 120°staggered-and same-phase systems.The least impact on the duty cycle's CV was observed in the phase difference between 60°and 90°.Furthermore,the smallest CV value of the pressure fluctuation was found at a phase difference of 120°across different duty cycles.The atomization tests reveal that the relative span(RS)of the droplets in the PWM variable spraying driven by a staggered phase was lower than that by the same phase.The RS decreased the most at the duty cycle of 50%,with a change rate of 5.56%.The deposition test shows that the CV of the droplet coverage in the staggered-phase PWM spray system was reduced by 31.75%,compared with the same phase driving.The staggered-phase driving mode can effectively reduce the non-uniform deposition caused by the low-frequency control of the PWM variable spraying.The finding can also offer technical support to further optimize the precision variable spraying.
作者
张春凤
张萌
邹伟
翟长远
张弛
赵春江
ZHANG Chunfeng;ZHANG Meng;ZOU Wei;ZHAI Changyuan;ZHANG Chi;ZHAO Chunjiang(Intelligent Equipment Research Center,Beijing Academy of Agriculture and Forestry Sciences,Beijing 100097,China;College of Mechanical and Electronic Engineering,Northwest A&F University,Yangling 712100,China;College of Agricultural Engineering,Jiangsu University,Zhenjiang 212013,China;College of Intelligent Science and Engineering,Beijing University of Agriculture,Beijing 100096,China)
出处
《农业工程学报》
北大核心
2025年第16期25-34,共10页
Transactions of the Chinese Society of Agricultural Engineering
基金
北京市农林科学院改革与发展项目(GGFZ20240112)
江苏省重点研发计划项目(BE2021302)。
关键词
PWM
变量喷雾
压力波动
雾化特性
雾滴粒径
雾滴沉积
PWM
variable spray
pressure fluctuation
atomization characteristics
droplet size
droplet deposition
作者简介
张春凤,博士生,研究方向为肥药精准施用技术及装备。Email:zhangchunfeng2022@163.com;通信作者:赵春江,博士,研究员,中国工程院院士,研究方向为农业信息化技术。Email:zhaocj@nercita.org.cn。
