Seed entrainment unit

1. An entrainment unit for distributing seed, comprising;

a seed chamber for seed in bulk;

a mixing chamber for mixing seed and air, the mixing chamber having a discharge outlet for discharging entrained seeds; and

an air supply means having an air outlet divided into a first passageway and a second passageway for:

(a) supplying a turbulent first air flow into the mixing chamber via the first passageway so that the first air flow travels into and across to the seed chamber so that seed is entrained therein and transported to the mixing chamber, and

(b) supplying a laminar second air flow into the mixing chamber via the second passageway, the second passageway extending around the seed chamber and directly into the mixing chamber to combine with the first air flow and form a combined air flow that distributes the seed and transports the seed through the discharge outlet;

wherein, in use, the combined air flow effectively entrains and distributes seeds of different sizes and weights from the entrainment unit without the need to adjust the air supply when switching from one seed to another.

2. The entrainment unit of claim 1 , wherein the air supply unit comprises an air chamber for receiving air from an air source, the air source being one of a motor driven fan and a compressed air source.

3. The entrainment unit of claim 1 , wherein the first passageway includes a first passage outlet for the first air flow to enter into the seed chamber and the second passageway includes a second passage outlet for the second airflow to enter into the mixing chamber.

4. The entrainment unit of claim 3 , wherein the first passage outlet is in direct fluid communication with the seed chamber and the second passage outlet is in direct fluid communication with the mixing chamber.

5. The entrainment unit of claim 4 , wherein the first and second passageways are parallel to each other.

6. The entrainment unit of claim 5 , comprising a baffle that separates the first and second passageways.

7. The entrainment unit of claim 6 , wherein the baffle provides a common wall that extends between the first and second passageways from the air chamber to the mixing chamber.

8. The entrainment unit of claim 7 , wherein the common wall comprises three portions, namely an inclined portion situated at least partially in the air chamber;

a seed chamber portion that extends between the air chamber and the mixing chamber; and an upwardly curved portion that extends into the mixing chamber.

9. The entrainment unit of claim 8 , wherein the inclined portion of the common wall provides a leading edge to separate air exiting the air chamber into the first and the second air flows.

10. The entrainment unit of claim 8 , wherein the upwardly curved portion of the common wall is configured to induce turbulence into the first air flow such that the first air flow enters the mixing chamber as a turbulent air flow.

11. The entrainment unit of claim 8 , wherein the seed chamber portion of the common wall defines a lower wall of the seed chamber.

12. The entrainment unit of claim 1 , further including an internal wall that separates the mixing chamber and the seed chamber.

13. The entrainment unit of claim 12 , wherein the internal wall includes a curved surface for guiding the combined air flow towards the discharge outlet.

14. The entrainment unit of claim 1 , wherein the seed chamber includes at least one inclined side walls for funnelling seed under a gravitational force towards the mixing chamber.

15. An entrainment unit for distributing seed, comprising;

a seed chamber for seed in bulk;

a mixing chamber for mixing seed and air, the mixing chamber having a discharge outlet for discharging entrained seeds; and

an air supply means for:

(a) supplying a turbulent first air flow to the seed chamber so that the first air flow travels into and across the seed chamber and seed is entrained therein and transported to the mixing chamber, and

(b) supplying a laminar second air flow directly to the mixing chamber so that the second air flow can be combined with the first air flow to form a combined air flow that distributes the seed and transports the seed through the discharge outlet;

wherein, in use, the combined air flow effectively entrains and distributes seeds of different sizes and weights from the entrainment unit without the need to adjust the air supply when switching from one seed to another.

16. The entrainment unit of claim 1 , wherein the air outlet of the air supply unit is one of a plurality of alike air outlets that together form a manifold.

17. The entrainment unit of claim 16 , wherein the seed chamber is a common seed chamber, with each air outlet of the manifold being in fluid communication therewith.

18. The entrainment unit of claim 16 , wherein the mixing chamber is one of a plurality of separate mixing chambers, with each air outlet of the manifold being in fluid communication with one of the mixing chambers.

19. The entrainment unit of claim 18 , wherein the discharge outlet is one of a plurality of separate discharge outlets, with each mixing chamber of the manifold being in fluid communication with one of the discharge outlets.

20. The entrainment unit of claim 15 , wherein the air outlet of the air supply unit is one of a plurality of alike air outlets that together form a manifold.

21. The entrainment unit of claim 20 , wherein the seed chamber is a common seed chamber, with each air outlet of the manifold being in fluid communication therewith.

22. The entrainment unit of claim 20 , wherein the mixing chamber is one of a plurality of separate mixing chambers, with each air outlet of the manifold being in fluid communication with one of the mixing chambers.

23. The entrainment unit of claim 22 , wherein the discharge outlet is one of a plurality of separate discharge outlets, with each mixing chamber of the manifold being in fluid communication with one of the discharge outlets.