Seed passage speed through short vertical delivery tubes at precise seeding
Czech University of Life Sciences Prague, Faculty of Engineering, Kamýcká 129,
CZ 165 21 Prague 6 – Suchdol, Czech Republic
The development trend of precision seed machines is the use of central seed hopper. Another requirement is to increase the driving speed during precise sowing up to 10–12 km h-1. This involves increased demand for uniformity of the seeds movement between the dosing mechanism and seed coulters. Previous measurements of seed passage speed showed undesirable changes in distance of seed during passage by long delivery tubes. The research was therefore focused on the evaluation of flyby seed parameters in short vertical delivery tubes of inner diameter 10, 12 and 14 mm and a length of 0.50 m. The aim of the experiment was to evaluate the dependence of the seed passage speed of corn, winter wheat and oilseed rape on the air pressure in the supply hose from the fan to short vertical delivery tubes and to recommend appropriate settings of air pressure in the intake air to delivery tubes. Logarithmic function was chosen for the description of dependence of flyby speed of three crops seeds on air pressure in the vertical tubes. The speed of the seed at the end of seed tubes, established as necessary for high-speed seeding (10 m s-1) was achieved in all three test seed tubes when the air pressure in the supply pipe 3.0 kPa. Air speed in the vertical delivery tubes was 3.15 to 4.2 times higher than the speed of the seeds. Based on the correlation index values from 0.90 to 0.96, the high quality of the regression model was found in all cases. It was found that the short vertical delivery tubes of internal diameter 10, 12 and 14 mm are useful for a new developed seeder. On the other hand, deviations of seed passage speed for winter wheat seeds occur at higher air speed. Higher internal diameter of downtube decreased significantly seed passage speed for maize seeds.