GB2110911A - Pneumatic seed dispenser - Google Patents

Abstract

A pneumatic seed dispenser comprises a seed conveyor (2) with a ring of pockets (3) and an upright seed pick up plate (9) formed with a plurality of apertures (14) arranged on a circle and adapted so that each can hold a seed by the action of air pressure; the conveyor (2) and the plate (9) each being rotatable within a housing (1) about a respective axes 18, 17 so that each aperture (14) moves in an eccentric path relative to the conveyor (2) as both rotate together, thereby to carry a seed upwards from a central seed reservoir (4) and move it outwards into a pocket (3) of the conveyor. The offset of the two axes is selected to deliver the seed into the pockets (3) before they are released, the pocket then being closed by a fixed wall (5) past which the conveyor rotates. Outwards movement of the seeds within the pockets (3) is accommodated by providing radially extended pockets so that the speed of the seeds is further increased before they are discharged at the outer periphery of the conveyor (2). <IMAGE>

Description

SPECIFICATION Pneumatic seed dispensers This invention relates to a pneumatic seed dispenser suitable for a planter.

The known planter pneumatic seed dispensers comprise a vertical rotating drum or disc formed with a series of apertures around its periphery in which seeds are held by air pressure, the seeds being picked up from a seed reservoir and released at a seed delivery point from which they are conducted to a coulter for sowing.

It has been found that the accuracy of seed spacing can be optimised if the seed delivery point is arranged close to the ground and the velocity of the seed at the delivery point is substantially equal and opposite to the velocity of the planter over the ground, thereby producing effective vertical delivery of the seed to the ground. In order to achieve this result, the speed of rotation of the drum or disc is related to the velocity of the planter over the ground, but it is then found that there is an upper limit to the velocity at which the planter can operate accurately because it is difficult to ensure that seeds are picked up reliably in the apertures of the drum or disc when it is rotating at higher speeds.This difficulty is particularly notable because the apertures lie on a circle concentric with the axis of rotation and thus travel at the same speed at the seed pick up point in the reservoir and at the seed delivery point.

It has been proposed that the aforesaid difficulty can be mitigated by arranging that seeds are picked up in the reservoir at a central region of a vertical disc and are moved radially outwards to a peripheral seed delivery point as the disc rotates, thereby increasing the speed of the seed prior to delivery to the ground. This radial movementof the seed has been achieved by providing a fixed disc with a slot, and a superimposed rotating disc with a series of straight radial slots so that the intersection of each straight slot with the spiral slot forms a seed pick up aperture that moves outwards with movement of the rotating disc. A ring of equi-angularly spaced pockets is concentric with and rotates with the rotating disc so that a seed is delivered into each pocket in turn and is subsequently delivered to the ground.

An object of the present invention is to provide a pneumatic seed dispenser in which seeds are moved radially outwards from a central reservoir but which avoids the over-lapping slots of the proposed dispenser and thus the consequent air leakage caused by the thickness of the rotating disc and seed damage caused by the guillotining action of the slots.

A pneumatic seed dispenser according to the invention consists in a seed conveyor comprising a ring of pockets, and an upright seed pick up plate formed with a plurality of apertures arranged on a circle and adapted so that each can hold a seed by the action of air pressure, the covneyor and the plate each being rotatable within a housing about a respective axis through the centre of the ring of pockets and the centre of the circle of apertures, these two axes being parallel but offset from one another so that each aperture moves in an eccentric path relative to the conveyor as both rotate together, thereby to carry a seed upwards from a central seed reservoir and move it outwards into a pocket of the conveyor.

The offset of the two axes is selected to produce sufficient movement of the seed into the pockets before they are released, the pocket then preferably being closed by a fixed wall past which the conveyor rotates.

Preferably, further outwards movement of the seeds within the pockets is accomodated by provid ing radially extended pockets so that the speed of the seeds is further increased before they are discharged at the outer periphery of the conveyor.

The invention will now be described by way of example with reference to the accompanying drawings in which, Figure lisa plan view of a pneumatic seed dispenser according to the invention, Figure 2 is the side elevation in the direction of arrow A in Figure 1,and The pneumatic seed dispenser comprises a discshaped housing 1 within which a ring-shaped c-shaped housing 1 within which a ring-shaped conveyor 2 is rotatably mounted. The conveyor 2 is formed with none equi-angularly spaced pockets 3 that extend from the inner to the outer periphery of the conveyor. A seed reservoir 4 is located at the centre of the conveyor and comprises a cylindrical, horizontally extending duct 5 that is connected to an upright seed supply pipe 6 at its outer end and is open at its inner end.An internal wall 7 determines that level of seed in the duct at approximately half the height of the duct. A bearing 8 is provided between the duct 5 and conveyor 2 so as to support the latter for rotation.

A seed suction disc 9 is rotatably mounted in a recess 10 in the transverse wall 11 of the housing 1 so that its inner face lies opposite the open end of the duct 5. A central drive shaft 12 extends from the disc 9 through the wall 11 of the housing and is rotatably supported by a bearing 13. Nine equi-angularly spaced apertures 14 are formed through the disc 9 and lie on a circle about the centre of the disc.

Agroove 15 in the base ofthe recess 10 extends in an arc along the circle of apertures from the lowest point of the reservoir 4, as shown in Figure 2, and is connected via an outlet 16 to a vacuum pump so that a seed is picked up by each aperture in turn as the disc 9 rotates.

The axis of rotation 17 of the seed suction disc 9 extends parallel to the axis of rotation 18 of the conveyor 2 but is offset from it so that the circle of seed suction apertures 14 passes alongside the lowest point of the seed reservoir 4 and also passes outside of the reservoir at the top and alongside the pockets 3 of the conveyor. By these means, seeds picked up in the apertures 14 can be moved upwards The drawing(s) originally filed was/were informal and the print here reproduced is taken from a later filed formal copy.

in an arc out of the reservoir through an opening 19 in the top of the duct 5 and into respective pockets 3 of the surrounding conveyor, the disc 9 and conveyor 2 both rotating in the same sense, at the same speed and in phase with one another.

Once each aperture 14 has delivered its seed into a pocket 3, it releases that seed by removal of the suction as the aperture passes the end of the suction groove 15. At this point in the rotary motion of the conveyor, the pocket is closed at its inner end by the upper edge of the duct 5.

Once released in the pocket 3, each seed moves outwards within it by a centrifugal action and cooperation with the side walls of the pocket, the trailing side walls 20 being inclined rearwards relative to the radii from its inner to its outer end.

The seeds are then discharged through an opening 21 at a lower point in the peripheral wall of the housing 1.

The dispenser shown in Figure 2 is adapted to be used in a planter moving from left to right in the drawing, the axis 17 of the disc 9 being offset from the axis 18 of the conveyor in the direction of advance of the planter so that the seeds are moved upwards and forwards into the pocket 3 and are then moved downwards and rearwards to be discharged through the opening 21. This rearwards delivery of the seeds counteracts the forward velocity of the planter across the ground, and ideally, these speeds are matched so that the seeds effectively move vertically downwards to the ground. Typically, for a planter moving at a velocity of 6 m.p.h., the conveyor might rotate at a speed of 3 revolutions/ second and its outer diameter might be 1 foot. The seeds would then be sown at a spacing of 4 inches.

In other embodiments of the invention, a different number of pockets 3 are provided in the conveyor with a corresponding number of seed pick up apertures 14. Further, the seed spacing can be varied by replacing the disc 9 with one having a fraction of the number of apertures 14 so that the seeds are delivered to some of the pockets but not others. For example, halving the number of apertures will allow seeds to be delivered to every other pocket. Alternatively, instead of replacing discs 9 plugs could be used to close some of the apertures 14.

The size of the apertures can also be varied to suit different seeds either by using different discs 9 or using plugs with different aperture sizes in the one disc 9.

The drive mechanism for the conveyor 2 and disc 9 comprises a chain drive 22 to each from a common shaft 23. An alternative drive mechanism might include a drive coupling between the conveyor 2 and disc 9 within the housing 1 so that just one of these need be driven externally.

A seed dispenser mechanism such as that illus trated might be located between the discs of a double disc coulter so as to form a compact system located near to the ground for accurate planting.

Claims (13)

1. A pneumatic seed dispenser comprising a seed conveyor with a ring of pockets and an upright seed pick-up plate formed with a plurality of aper tures arranged on a circle and adapted so that each can hold a seed by the action of air pressure, the conveyor and the plate each being rotatable within a housing about a respective axis through the centre of the ring of pockets and the centre of the circle of apertures, characterised in that said two axes (18, 17) are parallel but offset from one another so that each aperture (14) moves in an eccentric path relative to the conveyor (2) as both rotate together, thereby to carry a seed upwards from a central seed reservoir (4) and move it outwards into a pocket (3) of the conveyor.

2. A seed dispenser as claimed in claim 1 in which the offset ofthetwo axes (18,17) is adapted to produce movement of the seed into the pockets (3) before they are released.

3. A seed dispenser as claimed in claim 1 or 2 which further comprises a fixed wall (5) about which the conveyor (2) rotates and which serves to close each pocket (3) after is receives a seed.

4. A seed dispenser as claimed in claim 3 in which the fixed wall (5) is circular with an opening (19) in its upper region through which seed are carried from the reservior (4) formed by said fixed wall (5).

5. A seed dispenser as claimed in any one of the preceding claims in which each of said pockets (3) is open at its outer periphery and is closed by a fixed circular wall (1) of said housing which is formed with a seed outlet through which the seed is delivered.

6. A seed dispenser as claimed in claim 5 in which said seed outlet opening (21) is located below the centre of the conveyor (2) on that side of the vertical through said centre (18) from which the conveyor rotates towards the vertical.

7. A seed dispenser as claimed in claim 5 or 6 in which each pocket (3) is elongate and extends radially.

8. A seed dispenser as claimed in claim 7 in which each pocket (3) extends radially over more than half the radius of the housing (1).

9. A seed dispenser as claimed in claim 7 or 8 in which each pocket (3) has a trailing side wall (20) which is inclined from the conveyor diameter so that its outer end trails relative to its inner end.

10. A seed dispenser as claimed in any one of the preceding claims in which there are an equal number of apertures (14) and pockets (3).

11. A seed dispenser as claimed in any one of the preceding claims in which the conveyor (2) and pick-up plate (9) are driven by a respective connection (22) from a common input drive (23).

12. A seed dispenser as claimed in any one of claims 1 to 10 in which an input drive is connected to the conveyor (2) or pick-up plate (9) and the latter are interconnected.

13. A pneumatic seed dispenser substantially as herein described with reference to the accompany ing drawings.