Development of 4CL-1 self-propelled combine harvester for green onion

Abstract: Based on the agronomic requirements and planting methods of domestic green onion planting, a self-propelled green onion combine harvester was designed. The machine is composed of walking system, transmission system, combined excavating device, clearing device, clamping conveyor, torsion paving device, and so on. It can complete the excavating, cleaning, lifting and laying of green onion at one time. Based on the theoretical analysis of power configuration requirements for the machine and motion relationship of each key component, the overall power of the machine and the gear ratio of each stage were determined, and the structural parameters of the key components were designed. The whole drive system consists of mechanical transmission part and hydraulic transmission part. The power coordination of walking system and excavating system is realized by the mechanical transmission part. The position adjustment of the excavating system, the rotation speed control of the clamping conveyor and the torsion paving device are realized by the hydraulic transmission. The combined excavating device composed of rotary loosening knife group and V-type excavating shovel, as the core part of green onion harvesting, affects the excavating effect and harvesting quality. That has a strong applicability to improve the excavating depth of green onion, realize step-by-step loosening and excavation of the soil, reduce excavation resistance and avoid harvesting congestion. The rotary loosening knife group completes the cutting of the soil on both sides, the V- type excavating shovel realizes the bottom excavation and lifting of the soil, the rod conveyor chain transports and lifts the green onions and the initial cleaning of the onion-attached soil, and the clearing roller remove residual soil from roots of green onion. The two-stage soil cleaning is composed of rod conveyor chain and soil cleaning roller to ensure the effect of soil cleaning and impurity removal. To alleviate the extrusion damage of green onion, the effective feeding and flexible clamping of green onion can be completed by clamping conveyor to adapt to different green onion sizes. Designing the speed of the rod conveyor chain, the forward speed of the machine and the clamping conveying speed, to understand the speed matching relationship among them, and ensure that the soil at the root of the green onion is cleaned and the clamping conveying is stable. The reversal conveying and laying mechanism can change the vertical clamping to horizontal conveying of green onion, and the orderly laying of green onion can be completed. The field test results show that the removal rate, damage rate, loss rate and productivity of the machine are 99.50%, 1.40%, 0.70% and 0.049 hm2/h, respectively. The machine solves the problems of large excavation resistance, unstable clamping and conveying, unclean root soil cleaning, disorderly laying, etc. This research can provide basis for design and development of green onion harvesting and equipment.