Mathematical model and optimization of structure and operating parameters of pneumatic precision metering device for rapeseed

The optimization of the structure and operating parameters is a key for the good performance of an automatic precision seeding system, which has been widely investigated through experimental methods by many researchers. This paper focused on the sucking-seed process of the nozzle of a pneumatic rapeseed metering device, and gave several theoretical results on the optimization of structure and operating parameters. Firstly, an optimal model was obtained by minimizing the contact force per point of contact ring while the seed was sucked on the seed nozzle. From this model an optimal relation of the diameter of seed, the cone angle and the diameter of the seed nozzles was obtained. Secondly, an approximate model on the pressure difference of the seed nozzle was introduced. Through model analysis, we provided some optimal conclusions on the diameter of the nozzle, the nozzle number of the metering disc, the radius of orifice and the rotational speed of the metering disc. Furthermore, some experiments were presented to indicate the effectiveness of the theoretical results.