1. Field of the Invention
The present invention relates to sowing apparatus for the metered dispensing of seed material of varying size and type, fertilizers, chemical granulates and the like, by means of at least one metering device, comprising a cellular wheel arranged within a casing, and a pneumatic drive for transporting the granular material discharged pneumatically from the cellular wheel through feeding ducts, hoses into distributor ducts or holes to the fertilizer or granulate outlets.
2. Prior Art
Metering apparatuses (made by Flexi-Coil) are known, with which cellular wheels for coarse, fine and superfine distribution of different types and grain sizes of seed material and fertilizers in granular form are available. Such metering apparatuses are exchanged if wheels for different grain sizes are required.
Furthermore, metering apparatuses (made by Accord) with central cellular wheels for seed grains are known, with which by means of the cellular wheel the seed is metered exactly according to its volume, and, for example, is sealed by means of a rubber ledge. The amount of seed can be continuously adjusted by changing the width of the cells. This allows an exact meeting operation dependent on the path and the volume.
For obtaining an exact sowing operation sowing machines with precise wheels are known, which are individually supported in one sowing casing each. Bottom flaps allow the adjustment in four positions for adapting to various sizes of seeds.
Furthermore, from EP-A 0 295 633, a metering apparatus for volumetrically discharging of seed material or fertilizer in granular form is known, which uses a cellular wheel and a stripping means associated thereto. The granulate discharged in a metered manner from the cellular wheel is transported pneumatically through guide chutes resp. individual channels into the discharge ducts with increased speed.
U.S. Pat. No. 3,606,965 discloses a device for exactly distributing metered amounts of a powdery material by means of rotating cylindrical drums which are subdivided into chambers, the open circular areas of which are cooperating with locking gates through which the amount of material is adjustable, which is distributed from supply bins into the chambers of the drums. The number of parallel drums is determined by the number of different materials to be distributed. Said different materials pass from the drums to a rotating plate, from where they are discharged to the soil.
PCT/WO 92/12619 refers to a metering device for sowing machines in order to discharge granulate seed material in an exactly metered manner. This device comprises cellular wheels, which are arranged parallel to each other on a common shaft, and which are arranged in a supply container and can be removed from the container as a unit together with the wheel. For dispensing the seed material, a pressurized airflow is passed over the cellular wheel, which transports and discharges the seed material to an outlet. By restricting the output channel, the speed of the pressurized air is increased.