PNEUMATIC SEED METERING UNIT FOR PRECISION SEEDERS

摘要

The invention relates to a pneumatic metering unit which forms an essential component of an automatic precision seeder and which is particularly suitable for large seeds having an atypical shape, such as garlic, onion and similar. The invention makes use of a hopper with an oscillating base and an adjustable hatch in order to facilitate and control the flow of seeds being supplied. The invention is primarily used to meter seeds (separation of individual seeds and ordered delivery) and said operation is performed satisfactorily using various different factors, such as: a suitable, constant seed level in the separation chamber; seed mixing by means of the vibration of the oscillating plate with an amplitude and frequency in accordance with the properties of the seed; the shape and kinematic parameters of the dispensing disks which are mounted in pairs and which combine suction adhesion with mechanical support; the geometric configuration of the periphery of the disks (backs) and the cover (chute), which eliminates double-amount-type errors; the continuous cleaning of the ducts using an air jet, which prevents permanent clogging and which significantly reduces breakdown-type errors; suitable values for the generated pressure and vacuum; and checking of the sealing system in order to prevent suction losses. The suction and pressure generated by the centrifugal fans are conveyed to the metering unit through flexible corrugated pipes which are connected to the dispenser and are subsequently directed through the axially-divided central hollow shaft to the respective ducts of the rotating metering disks. The rotational movement of the dispensing disks is generated from follower wheels by means of a suitable standard transmission system in accordance with the desired seeding rate. The components of the metering unit can be assembled in different arrangements such as to be adapted to furrow planting with two rows or bed planting with multiple rows.