WO1994026090A2

WO1994026090A2 - Dibber drills

Info

Publication number: WO1994026090A2
Application number: PCT/GB1994/001051
Authority: WO
Inventors: John Nicholas Reed; Simon John Miles
Original assignee: British Technology Group Limited
Priority date: 1993-05-19
Filing date: 1994-05-17
Publication date: 1994-11-24
Also published as: GB2278033A; GB9409948D0; WO1994026090A3

Abstract

A rotary dibber drill (10) includes venturi devices (20 and 34) to transfer seed and fertiliser granules from a presentation assembly to a pneumatically activated dibber wheel (49). A rotary face valve (86) controls the radial movement of the dibber elements in wheel (49).

Description

DIBBER DRILLS

The present invention relates to dibber drills, that is to say to machines which, in operation, press a hole in the ground with the seed to be planted in or on the consolidated soil at the bottom of the hole.

Rotary planters of this type are already known in which a plurality of radially disposed dibber elements are mounted for movement along respective guide channels in a rotating ground-engaging support called a dibber wheel, so that as the dibber wheel is rotated about its horizontal axis during forward motion of the planter, the dibber elements move radially between withdrawn positions over the upper part of their rotary motion and extended positions over the lower part. In addition to the dibber wheel, the planter includes a presentation assembly adapted to meter seed into the dibber guide channels currently moving over the upper part of their rotary motion. If desired, other granular material e.g. a pesticide or fertiliser, may also be metered Into the dibber wheel using a similar presentation assembly and in the following description, the term 'seeds etc.' has been used to mean either seeds alone or seeds accompanied by this other granular material. Once embedded in the soil, adhesion forces prevent the seeds etc. from being withdrawn with the dibber elements. Such machines will hereinafter be referred to as rotary dibber drills. In the rotary dibber drill described and illustrated in EP 0320248A (British Technology Group Ltd.), seeds are fed to the dibber wheel by an annular cell ring and the seeds enter their cells from the seed hopper mounted on one side of the ring. Sandwiched between the cell ring and the dibber wheel is a stationary plain ring with a single opening, which controls the transfer of seeds from the cell ring into the dibber guide bores. Thus, as the dibber wheel rotates to bring successive dibbers to the transfer position, the dibber, which is normally flush with the face of the dibber wheel, retracts slightly in its guide bore, exposing the opening in the plain ring. The seed is then blown into the guide bore by a low positive-pressure air jet in readiness for a subsequent planting operation when the dibber extends to press a hole in the ground with the seed at the bottom of it. It is a drawback of rotary dibber drills using this known pneumatic transfer system that fitting transfer components internally necessitates that the dibbers must retract significantly more than the diameter of the seed. This dictates a larger than ideal amplitude of movement of the dibber thereby increasing the dynamic forces and mechanical difficulty of achieving sufficiently high dibber cycling rates. Should a blockage occur or the seed type require changing, an internal metering/transfer system poses intrinsic problems to speedy/convenient access and it is an object of the present invention to provide a rotary dibber drill in which these drawbacks are avoided or at least significantly reduced.

According to a first aspect of the present invention, a rotary dibber drill as above defined includes a venturi device operative to transfer seed and/or other granular material to the dibber wheel from a suitable presentation assembly e.g. a cell wheel .

Provision of a venturi device in accordance with the present invention enables seeds etc. metered at peripheral cell wheel speeds of up to 0.25m/sec to be satisfactorily targeted into the dibber wheel at peripheral dibber wheel speeds up to 2m/sec.

Conveniently, the dibber elements are pneumatically activated.

Preferably, in such cases, the positions of the dibber elements are controlled by a rotary face valve comprising two annular disc elements arranged face to face with one of the elements fixed against rotation and the other element rotating with the dibber wheel so as together to provide apertures and surface grooves or other passages connecting said apertures to atmosphere or to an external pressure source as the case may be thereby to expand or retract piston drives to the dibber elements in the required fashion. According to a second aspect of the present invention, there is provided a rotary valve comprising first and second parts mounted for relative rotation about an axis, at least two first grooves or other passages in said parts being disposed so as to lie along the circumference of a first circle centred on said axis, at least two second grooves or other passages in said parts being disposed so as to lie along the circumference of a second circle centred on said axis, and at least two pairs of apertures with one aperture of each pair arranged on relative rotation between said two parts to move into and out of communication with said first grooves or other passages and with the other aperture of each pair arranged on relative rotation between said two parts to move into and out of communication with said second grooves or other passages. Conveniently, in this last case, the two parts are annular discs mounted in face to face contact with one another with the first and second passages provided by concentric grooves in a first of the two parts and the pairs of apertures with which they are adapted to communicate provided in the second of the two parts.

The invention further includes a rotary dibber drill according to the first aspect of the present invention in which the positions of pneumatically activated dibber elements are controlled by a rotary face valve according to the second aspect of the present invention.

An embodiment of the invention will now be described, by way of example only, with reference to the accompanying partly diagrammatic drawings in which:

Figure la is a partly sectioned side view of a rotary dibber drill in accordance with the invention;

Figure lb is a similar view taken from the other side of the machine;

Figure 2a shows the venturi device on an enlarged scale with

Figures 2b and 2c respectively showing side and plan views of a first component of the device and Figures 2d and 2e respectively showing a vertical section and end view of the second component of the device;

Figure 3 is a vertical section showing further details of the dibber wheel etc. ; Figures 4a and 4b show the two sides of one part of a rotary face valve used in the dibber wheel to control the radial movement of the dibber elements;

Figures 5a and 5b are schematic views of an alternative metering arrangement; and Figure 6 is a partly sectioned side view of an alternative design of dibber drill to that shown in Figure 1.

Where convenient, Figures la and lb, Figures 2a to 2d, Figures 4a and 4b, and Figures 5a and 5b will be collectively referred to as Figure 1, Figure 2, Figure 4 and Figure 5 as appropriate.

Referring first to Figure 1 of the drawings, a rotary dibber drill 10 according to the present invention comprises a repeller wheel 12 mounted for co-operation with a cell wheel 14 to meter seed 16 from a hopper 18 into a venturi device 20. The cell wheel 14 may be of any convenient design e.g. a Stanhay Webb type.

In use, the two wheels 12,14 will both rotate in an anti-clockwise sense (as viewed in Figure la) with the seeds located in the peripheral cells 22 held in place by an associated casing. Once clear of the casing, at or near the bottom dead centre of the cell wheel, the seeds will drop from the respective cells 22 into the Inlet passage 24 of the air venturi device 20.

A similar assembly 26 provided for the introduction of pesticide or other chemical granules 28 from a hopper 30 comprises a notched metering wheel 32 and associated air venturi transfer device 34.

In either case, if there is a tendency for the seeds or the granules to jam into the cells or notches 22,64, then an ejector blade may be included to free them at the appropriate point rather than rely on gravity alone. The detailed construction of the two-component venturi device 20 is best seen from the larger scale views of Figure 2 which show the two components (36,37) individually and as assembled. Thus referring first to Figures 2d and 2e, it will be seen that the vertical seed inlet 24 in the first component 36 extends downwardly from a flared mouth section to intersect with a downwardly inclined through passage 39. This latter is fed by the nozzle section 41 of an air line 43 (Figure 2a) typically operating at an air pressure of between 4 and 12 pounds per square inch (p.s.i.) (0.28-0.84 kg/cm² or 28-83 kPa).

At its lower end, the passage 39 terminates at the vertical face 45 of the second component 37 and in operation the majority of the seeds will impact against this face before passing through the vertical exit passage 47 to the dibber wheel 49.

Vee-section notches 51,52 are provided as shown at the base of face 45 and (optionally) at the junction between passages 39 and 47 to assist air flow.

In accordance with the venturi principle, the high speed air flow from the nozzle section 41, generates a suction effect which entrains the seeds from the cell wheel into an even faster air flow through the seed transfer section 24,39,47.

This latter flow fires the seeds to the periphery of the dibber wheel either directly or via the impact face 45 as described. The individual seeds remain on the periphery of the dibber wheel (swept into contact with the impact face 45) until a respective dibber recess 54 passes by into which they can enter. Typically, the recesses 54 will be some 5mm deep, dependent upon seed size. The annular gap 56 between the dibber wheel and the adjacent surfaces of the venturi device etc. is deliberately kept small e.g. in the range 1 to 2mm (preferably 1.5mm) and hence special steps have to be taken to provide an additional escape path which will allow the desired air flow characteristics to be established. Thus, in the illustrated embodiment, in addition to the main air escape path provided by the clearance gap 56 and the 'V notches 51,52, rapid transfer of the seed into the recesses 54 created by retraction of the dibber elements 58 is ensured by an open-ended cross channel 60 communicating with gap 56 via a series of drillings 62. A plurality of air exit holes 63 is (optionally) provided in face 45 so as to connect passage 47 with channel 60.

The granule transfer device shown at 26 in Figure la works on exactly the same principle as device 20 but with reduced clearances (typically 0.5mm⁾ consistent with the smaller size of particle transferred.

Seed/granule loss is prevented by covers 66,67 etc. Turning now to Figure 3 of the drawings, it will be seen that the dibber wheel 49 is keyed to a support shaft 69 driven from a ground wheel via a belt connection (not shown) with a pulley 71. For clarity, this latter has been omitted from Figure lb which shows how the repeller wheel 12 and metering wheel 32 are powered from a primary drive sprocket 73 on the shaft 69 by a toothed chain 75 acting through sprockets 77,78. The drive to cell wheel 14 is derived from the repeller wheel drive using a secondary chain and sprocket system 80.

In operation, rotational motion of the dibber wheel is effected by direct soil contact or by a ground-driven transmission or any other suitable means. Translational motion of the drill along the ground is from right to left as viewed in Figure la, the machine being either self-powered or towed behind a tractor or other suitable vehicle, as convenient. During this motion, the seeds etc. are punched into the soil just before the bottom dead centre portion of the dibber wheel 49 by the pneumatically operated dibber elements 58. The illustrated dibber wheel uses twelve such elements at 50 mm (nominal) spacing but, clearly, modifications are possible in which a larger or smaller number of dibber elements are used.

As best seen from Figure 3, the dibber elements 58 are attached to the rod ends of conventional compact piston/cylinder devices 82 which are attached to a centre flange 84 of the dibber wheel. The extension and retraction of the piston in devices 82 is controlled by a rotary face valve 86 made up of two annular discs 88 and 89 which are pressed together by a spring/nut combination 91 to form an air-tight seal between their mating surfaces.

The innermost 'distribution' disc 88 of these two is made of stainless steel and is locked against movement by an appropriate dowel pin connection (not shown) with the adjacent support structure 93.

The outermost 'switching' disc 89, on the other hand, is made of a plastics material and is connected by dowel pins (not shown) with the rotary dibber wheel 49.

Figures 4a and 4b respectively show the inner and outer faces of the distribution disc 88 in which a number of through apertures 95 are connected by appropriate annular and radial grooves formed in the two faces of the disc. In use, air at 80 to 120 p.s.i. (5.6-8.4 kg/cm² or 550-830 kPa) is supplied via an inlet hose 97 and a drilling 98 in the bearing housing to pressurise the apertures 95 and the associated grooves in the two faces of the disc 88. Other grooves found only in the outmost face of the disc 88 are permanently vented to atmosphere via radial drillings 99 as shown.

The switching disc 89 is apertured by twelve pairs of holes spread evenly around the rotation axis of the dibber wheel in the same positions as the dibber elements 58. Two pairs of these holes are visible in the view of Figure 3 although, for clarity, only the top pair has been identified by reference numerals (100,101⁾. It will be appreciated that when the outer apertures 100 of any pair are brought into communication with a pressurised groove in the disc 88, then the inner aperture 101 of that pair will communicate with an atmospheric groove and vice versa. In between these two situations, the apertures 100,101 are isolated from either set of grooves by the interruptions between adjacent groove ends in disc 88. As will be seen from Figure 3, tubing (102,103) is used to connect each pair of holes in the distributing disc 89 with the pressure/exhaust ports 104,105 for the dibber piston/cylinder devices 82 so that as the switching disc 89 rotates with the dibber wheel 49, the piston/cylinder devices are connected as appropriate to effect extension or retraction of the dibber elements in the desired manner.

Thus, for most of the time, each dibber element 58 will be withdrawn (corresponding to the connection of ports 104,105 with the longer grooves in Figure 4a). Dibber extension occurs, however, at the bottom dead centre of the dibber elements' motion (to punch plant the captured seed into the ground) and, optionally, following this e.g. at about the three o'clock position 107 (as viewed in Figure la) when the dibber elements are temporarily extended for their ends to be scraped free of any adhering matter by a scraper (not shown). A second scraper 109 is also provided, as shown, upstream of the scraper at position 107.

Various lubricated plastic materials e.g. Nyloil are currently being evaluated for the two discs of valve 86 in place of the materials currently being used, e.g. stainless steel and Nylatron.

In a modification (Figure 6) of the Figure 1 embodiment, the cell wheel 14 and the dibber wheel 49 are driven so as to rotate, not in the same rotative sense as one another i.e. both clockwise or both anti-clockwise, but rather in contrary rotative senses. Having the wheels 14,49 rotate in contrary rotative senses has the advantage that the horizontal velocity component given to the seed leaving the cell wheel is in a direction such as to reduce the relative velocity between the seed and the dibber wheel recess in which it is to be received.

Figures 5a and 5b are orthogonal views of an alternative transfer system to the venturi device 34 used in the embodiments of Figures 1 to 4 and 6. In this alternative transfer system, when the passageways in the two parts 120,121 are connected together by a cell 64 (Figure la) of the metering wheel 32, the resulting air flow from air line 43 (operating at the same p.s.i. value as before), is effective to sweep the pesticide or other chemical granules from the cell into the appropriate recess 54 in the dibber wheel 49.

It is, at least in theory, also possible to use this alternative transfer system to replace venturi device 20 rather than device 34.

As an alternative to using individual pneumatic cylinders to activate the dibber elements 58, it is envisaged that a one piece ring could be used instead with radial drillings in the ring forming the cylinder bores for the individual dibber elements.

Another option (not shown) is to have the separate systems for introducing the seeds and pesticide or fertiliser granules into the dibber wheel combined into a single cell wheel assembly communicating directly with the separate hopper supplies and feeding their contents into the dibber wheel via a single venturi device.

Claims

CLAIMS 1. A rotary dibber drill including a venturi device operative to transfer seed and/or other granular material from a presentation assembly to a dibber wheel.

2. A drill as claimed in Claim 1 in which the dibber elements of the dibber wheel are pneumatically activated.

3. A drill as claimed in Claim 2 in which the positions of the dibber elements are controlled by a rotary face valve comprising two annular disc elements arranged face to face with one of the elements fixed against rotation and the other element rotating with the dibber wheel so as together to provide apertures and surface grooves or other passages connecting said apertures to atmosphere or to an external pressure source as the case may be thereby to expand or retract piston drives to the dibber elements in the required fashion.

4. A dibber drill as claimed in Claim 2 or Claim 3 in which the positions of the dibber elements are controlled by a rotary valve comprising first and second parts mounted for relative rotation about an axis, at least two first grooves or other passages in said parts being disposed so as to lie along the circumference of a first circle centred on said axis, at least two second grooves or other passages in said parts being disposed so as to lie along the circumference of a second circle centred on said axis, and at least two pairs of apertures with one aperture of each pair arranged on relative rotation between said two parts to move into and out of communication with said first grooves or other passages and with the other aperture of each pair arranged on relative rotation between said two parts to move into and out of communication with said second grooves or other passages.

5. A dibber drill as claimed in Claim 4 in which the two parts are annular discs mounted in face to face contact with one another with the first and second passages provided by concentric grooves in a first of the two parts and the pairs of apertures with which they are adapted to communicate provided in the second of the two parts.

6. A rotary valve comprising first and second parts mounted for relative rotation about an axis, at least two first grooves or other passages in said parts being disposed so as to lie along the circumference of a first circle centred on said axis, at least two second grooves or other passages in said parts being disposed so as to lie along the circumference of a second circle centred on said axis, and at least two pairs of apertures with one aperture of each pair arranged on relative rotation between said two parts to move into and out of communication with said first grooves or other passages and with the other aperture of each pair arranged on relative rotation between said two parts to move into and out of communication with said second grooves or other passages.

7. A valve as claimed in Claim 4 in which the two parts are annular discs mounted in face to face contact with one another with the first and second passages provided by concentric grooves in a first of the two parts and the pairs of apertures with which they are adapted to communicate provided in the second of the two parts.

8. A rotary dibber drill or a rotary valve substantially as hereinbefore described with reference to and/or as illustrated in the accompanying drawings.