Computer-aided design and DEM-based simulation analysis of a diversion-type precision soybean metering device

• Diversion-type soybean metering device based on computer-aided design. • The design idea of ’directional shunt, seed pending’ is adopted. • The key structural parameters are determined by theoretical analysis. • The novel metering device showed a higher optimal operating speed. To address the issues of unstable filling performance and poor sowing quality caused by ineffective seed clearing in mechanical soybean metering devices under high-speed operation, a novel high-speed precision metering device featuring seed diversion and pending filling functions was developed. The design introduces the concept of ’directional diversion and seed pending’ in which the sloped seed inlet guides the seeds directionally, while the double-lug hole structure enables orderly filling and temporary pending, thereby significantly enhancing the filling qualification index. Theoretical analysis was conducted to identify key structural parameters influencing seed filling, transportation, pending, and clearing. Orthogonal simulation experiments were performed to evaluate three critical parameters—perturbation angle, sidewall length, and bottom length—using the qualification index and pending index as optimization criteria. The results indicated that optimal seeding performance was achieved at a perturbation angle of − 12.07°, a sidewall length of 5.08 mm, and a bottom length of 15.28 mm. Bench validation experiments conducted at 6–10 km/h showed that the qualification index exceeded 98 %, while the pending index reached 93.47 %, representing an improvement of at least 3.9 percentage points over conventional brush-type metering devices. These results meet the operational requirements for high-speed precision seeding and offer new insights into the design of soybean metering devices.