油菜籽气力精量排种器串联排种机制与短程排种路径优化

Same as most other precision seed-metering devices, the metering process of the pneumatic precision seed metering device for rapeseed is composed of eight sub-processes in series, including filling, taking, carrying, cleaning, shielding, casting, guiding and transporting. In the metering process, the device routes rapeseeds singly and orderly across such a long path in a multiple links series system that the process are easy to be disturbed to degrade the reliability and stability of the metering device. To solve the problem, an attempt of the project will be made to explore the series mechanism of the device in the process and to develop an advanced pneumatic precision rapeseed metering device employing minimal links and shorter path. Firstly, the movement law of the seed and the forces on the seed under pneumatic power in each sub-process will be determine via dynamics and kinematics analysis combined numerical simulation technology and high-speed photography technology on the premise of singly and orderly metering. The influences of the parameters of each link in the series system to the performance of the metering device, including quality of feed index, multiple index, miss index , are investigated in detail. The primary and secondary factors in the series system which affect the performance of the device are determined. The mathematical model is established to describe the series mechanism of the metering device. Then, with a conception of less links and short-range path in the metering process, the theories of the reliability and fuzzy reliability design will be applied to optimize the device to enhance the reliability and stability of it. An advanced metering device with simpler structure will be design, in which the number of sub-processes in the metering process would be reduced as less as possible and the reliability and stability of the metering performance would be improved. Finally, the advanced metering device will be manufactured and the performance of it would be tested under laboratory and filed conditions to verify the effect of the optimization. The research results of this project will supply theory of rape-seed pneumatic precision metering technology so as to improve the performance of rape planting equipments and to promote the development of rape industry.

本项目针对油菜籽气力式精量排种器排种过程属串联系统，环节多、路径长，影响排种器工作可靠性和稳定性的特征，开展油菜籽气力式精量排种器串联排种机制的研究和短程排种路径的优化：在单粒有序排种的前提下，采用种子动力学和运动学分析方法，结合数值模拟与高速摄影技术，分析油菜种子受气力作用在串联排种系统各环节的运移规律，揭示气力式油菜籽精量排种器串联排种机制；在满足排种器功能要求的前提下，应用可靠性和模糊可靠性设计理论，量化各环节关键要素与排种合格指数、重播和漏播指数等性能指标的相互关系，提出实现短程排种路径的控制策略，将充种、吸种、携种、清种、护种、投种、导种和输种等多个环节合并优化为较少的环节（如取种、投种和导种等），探索短程排种的新路径，最大限度简化排种过程，优化排种器的结构；研发一种新型短程油菜籽精量排种器；为油菜籽气力式精量排种技术提供理论支撑，提高油菜机械化直播装备性能，促进油菜产业的发展。

在油菜种植生产实践中，要提高油菜机械化水平、形成油菜种植的标准化，实现油菜生产的全程机械化，首要环节是开发高效适用的油菜机械化播种装备，其核心内容是油菜排种技术与装置。目前，影响排种器工作性能的因素繁多、复杂，排种器工作环节主要包括充种、吸种、携种、清种、护种、投种、导种和输种，这些环节构成一个串联系统，串联环节多不仅导致排种器结构复杂且一旦某个环节发生故障将大大降低排种器的性能及其工作可靠性。因此开展油菜籽气力式精量短程排种技术研究，提出短程排种的新路径，减少排种器工作过程所包括的工作环节，缩短种子迁移的行程，优化排种器结构，明确其串联排种机制与短程排种路径的工作机理成为研究重点。.本项目主要研究工作包括：（1）探明油菜籽气力式精量排种器形成“单粒有序”的排种机理，进一步分析各排种环节的结构参数和运行参数对种子轨迹路线的影响规律及主次因素。（2）阐明排种器各串联排种过程与排种性能指标的影响机制。上述排种过程串联环节中某一局部的变化会引起种子位移、速度、加速度、受载等的变化，破坏“单粒有序”的预期目标，影响排种合格、重播与漏播指数等性能指标。（3）开展短程排种路径的优化。在上述研究的基础上，针对现有排种过程含充种、吸种、携种、清种、护种、投种、导种、输种等环节是一串联系统，其中一个环节出现故障将大大降低排种精度的现实问题，应用可靠性和模糊可靠性设计的原理，分析排种系统串联环节中的关键节点与薄弱环节，研究提升排种系统稳定性和可靠性的控制策略，开展排种器结构的优化设计。（4）研究减少排种环节的控制策略、研发短程排种技术及其配套装置。上述研发基础上，优化并构建短程排种路径，设计短程排种的相关机构、开发形成短程的排种装置。.上述研究为油菜籽精量排种串联环节影响机制研究奠定理论基础，对于完善油菜籽精量排种技术理论有重要的理论意义和实际指导意义，对于其他各类小粒径种子的精量排种理论研究具有重要的理论参考价值；提出的油菜籽气力式精量短程排种技术，可简化油菜籽排种器的结构、提高油菜籽排种器排种性能的稳定性，节约良种，为油菜稳产高产提供技术支持，可推动油菜籽精量播种机械化的快速发展，在国民经济和社会发展中具有重大的现实意义。