Seed distribution element for precision seed drills, seed drill including said element
A seed distribution element ( 1 ) includes: —a sowing disc ( 16 ) rotated by a motor-driven transmission shaft ( 20 ) —a housing ( 10 ) with a fixed portion ( 11 ) in which the shaft ( 20 ) is supported and a portion ( 12 ) movable relative to the fixed portion and can be closed against it, with a seed collection chamber ( 15 ) in the fixed portion ( 11 ) and a pneumatic suction chamber ( 17 ) in the movable portion ( 12 ), —the sowing disc ( 16 ) being interposed between the portions ( 11, 12 ) and having opposed surfaces ( 16 a, 16 b ) delimiting the chambers, and provided with a ring of selector holes ( 23 ) extending between the opposed surfaces structure for producing a pressure differential between the opposed surfaces in the region of a circumferential segment of the ring of holes, including the pneumatic suction chamber, and —a seal ( 24 ) on the movable portion ( 12 ) capable of sliding contact with the facing surface ( 16 a ) of the disc ( 16 ) when the portions are closed against one another,—a thrust-bearing element ( 26 ) of the sowing disc ( 16 ), supported rotatably in the movable portion ( 12 ), to withstand the axial load produced by the disc ( 16 ) on the seal ( 24 ).
1. A seed distribution element for precision pneumatic seed drills, comprising:
a sowing disc which is rotated by a motor-driven transmission drive shaft at controlled speed,
a housing with a fixed portion and a portion which is movable relative to the fixed portion and can be closed against the fixed portion,
a seed collection chamber being defined in the fixed portion,
a pneumatic suction chamber being defined in the movable portion,
the sowing disc being interposed between the fixed and movable portions and having opposed surfaces delimiting the chambers,
the sowing disc having at least one ring of selector holes extending between the opposed surfaces, and
a seal which is arranged on the movable portion and is capable of sliding contact with the facing surface of the disc when the fixed and movable portions are closed against one another,
wherein a pressure differential is provided between the opposed surfaces in the region of a circumferential segment of the ring of holes,
wherein the seed distribution element further comprises a thrust-bearing element of the sowing disc, which thrust-bearing element is supported rotatably in the movable portion in order to withstand at least some of the axial load produced by the disc on the seal.
2. The seed distribution element according to claim 1 , wherein the thrust-bearing element is rotated with the disc when the fixed and movable portions are closed against one another.
3. The seed distribution element according to claim 1 , wherein the thrust-bearing element comprises a thrust-bearing plate which can bear on that surface of the sowing disc which faces the seal, in a zone radially inside of the ring of holes.
4. The seed distribution element according to claim 3 , wherein the thrust-bearing element comprises a drive element which is fixed for rotation with the plate and can be coupled with the drive shaft of the disc when the fixed and movable portions are closed against one another.
5. The seed distribution element according to claim 4 , wherein the drive element is self-centring relative to the drive shaft.
6. The seed distribution element according to claim 4 , wherein the drive element comprises a coupling member which rotates jointly with the thrust-bearing plate but has radial and/or circumferential clearance so as to be self-centred during rotational coupling with the drive shaft of the disc.
7. The seed distribution element according to claim 1 , wherein the movable portion is hinged to the fixed portion.
8. A sowing element for precision seed drills comprising a frame on which a seed distribution element according to claim 1 is mounted.
9. A seed drill comprising a supporting structure on which a plurality of sowing elements according to claim 8 are mounted.
10. A kit for the retrofitting of seed distribution elements of precision pneumatic seed drills wherein the distribution elements are of the type including:
a sowing disc which is rotated by a motor-driven transmission drive shaft at controlled speed,
a housing with a fixed portion and a portion which is movable relative to the fixed portion and can be closed against the fixed portion,
a seed collection chamber being defined in the fixed portion,
a pneumatic suction chamber being defined in the movable portion,
the sowing disc being interposed between the fixed and movable portions and having opposed surfaces delimiting the chambers,
the sowing disc having at least one ring of selector holes extending between the opposed surfaces, and
a seal which is arranged on the movable portion and is capable of sliding contact with the facing surface of the disc when the portions are closed against one another,
wherein a pressure differential is provided between the opposed surfaces in the region of a circumferential segment of the ring of holes,
wherein the kit comprises:
the movable portion pre-assembled with: a thrust-bearing element of the sowing disc, which thrust-bearing element is supported rotatably in the movable portion in order to withstand at least some of the axial load produced by the disc on the seal.
11. The kit according to claim 10 wherein the movable portion and the thrust-bearing element comprise at least one feature according to claim 2 .
12. The kit according to claim 10 wherein the movable portion and the thrust-bearing element comprise at least one feature according to claim 3 .
13. The kit according to claim 10 wherein the movable portion and the thrust-bearing element comprise at least one feature according to claim 4 .
14. The kit according to claim 10 wherein the movable portion and the thrust-bearing element comprise at least one feature according to claim 5 .
15. The kit according to claim 10 wherein the movable portion and the thrust-bearing element comprise at least one feature according to claim 6 .
16. The kit according to claim 10 wherein the movable portion and the thrust-bearing element comprise at least one feature according to claim 7 .