WO2016185324A1

WO2016185324A1 - Improved metering device for particulate material

Info

Publication number: WO2016185324A1
Application number: PCT/IB2016/052710
Authority: WO
Inventors: Brian Stewart Taege
Original assignee: TOMORROW'S INNOVATIONS Ltd
Current assignee: TOMORROW'S INNOVATIONS Ltd
Priority date: 2015-05-15
Filing date: 2016-05-12
Publication date: 2016-11-24
Anticipated expiration: 2017-11-15

Abstract

A metering device for particulate material, including: • a housing supporting a pair of parallel substantially horizontal first and second rotatable shafts; each shaft having at least one roller mounted thereon aligned opposite each other and arranged such that the curved surface of the first roller is in surface contact with the curved surface of the corresponding second roller; • at least part of the upper surfaces of the first and second rollers being arranged such that in use particulate material to be dispensed can fall upon said part of the upper surfaces of the said first and second rollers; • the first and second shafts being rotatable in opposite directions and such that the first and second rollers rotate towards each other when moving downwards; • the first roller being a soft resilient roller; and • the second roller incorporating one or more depressions on its surface.

Description

IMPROVED METERING DEVICE FOR PARTICULATE MATERIAL

Technical Field

The present invention relates to a metering device for particulate material and to apparatus incorporating said metering device.

Background Art

Any discussion of the prior art throughout the specification is not an admission that such prior art is widely known or forms part of the common general knowledge in the field.

There are a number of applications for which particulate materials need to be accurately dispensed at a preset rate, i.e. the quantity of material dispensed in a set time period or in a set distance traveled by a mobile apparatus.

The nature of the particulate material itself frequently presents difficulties:- the material may vary in size and/or be fragile and easily damaged by the apparatus and/or may be prone to clogging or bridging.

Ideally, a metering device for particulate material should be capable of accurate dispensing, be able to handle particulate material of a wide range of sizes, regular and irregular (including fragile material), be easy to adjust to vary the dispensing rate and be easy to clean out and to maintain.

Metering devices for particulate material are used in applications as varied as cosmetics and foodstuffs preparation, chemicals processing, preparation of agricultural chemicals such as fertilizer mixes, and mixing sized crushed rocks for applications such as roading.

One of the most demanding applications for dispensing particulate material is in dispensing seeds for agricultural and horticultural applications. In addition to the requirements set out above, a seed drill must be mobile and capable of continued long-term use under sometimes rugged conditions.

NZ 333057 summarises types of metering devices used with seed drills, and the advantages and disadvantages thereof. The apparatus of NZ 333057 improved upon the prior art discussed in that document by providing an apparatus that handled a wider range of seed sizes and shapes more easily. The first embodiment of the apparatus in NZ 333057 provides two counter-rotating sponges, and the rotation of the rollers towards each other draws seeds downwards through the rollers. However, while allowing a broad range of seed sizes and shapes to pass through the metering device, the flow-through rate of the apparatus is limited.

An additional limitation of the first embodiment described in NZ 333057 is the open- celled surface of foam rollers results in a number of seeds making a "full circuit" of the roller, i.e. the seed passes between the rollers, sticks to the surface of a roller, and completes a full circuit back into the store of seed. This affects the accuracy of the metering device, and although the difficulty was overcome in NZ 333057 by locating scrapers adjacent the underside of the sponges, this increases wear on the foam due to the friction between the foam and the hard surface of the scrapers.

A second embodiment of a metering device in NZ 333057 describes a similar setup to the aforementioned metering system, but includes one resilient roller and one hard roller, the latter incorporating one or more cavities in its surface. The hard roller rotates so that a cavity moves downwards towards the adjacent resilient roller. The soft roller and hard roller rotate in the same direction (i.e. not counter-rotary); this causes the soft roller to "brush" excess seed upward and out of the hard roller's cavity as the cavity in the hard roller moves downward; if more than the desired amount of seed is in the cavity, the extra seeds are gently pushed away by the soft roller. As the hard roller reaches the bottom of its rotation, the seed is free to drop from the cavity into the cavity leading to the drill tines. The soft roller moderates the flow of seed through the metering device, its rotation away from the hard roller acting to reduce the amount of seed in the cavity. While providing a more accurate metering device to those previously known, this action limits the throughput of the metering device.

It is therefore an object of the present invention to provide a metering device for particulate materials which overcomes at least some of the above described disadvantages. The device of the present invention has been designed for a seed drill and will therefore be described with reference to that application. However, it will be appreciated that the device of the present invention may also be used to dispense a wide range of particulate materials, either as a mobile dispenser or as a stationary dispenser. Disclosure of Invention

The present invention provides a metering device for particulate material, the metering device including:

- · a housing supporting a pair of parallel substantially horizontal shafts;

- · a first shaft having at least one first roller mounted thereon and a second shaft having at least one second roller mounted thereon, the or each said first and second rollers being aligned opposite each other on their respective shafts and arranged such that the curved surface of the or each first roller is in surface contact with the curved surface of the or each corresponding second roller;

- · at least part of the upper surfaces of the or each first and second rollers being arranged such that in use particulate material to be dispensed can fall upon said part of the upper surfaces of the or each said first and second rollers;

- · said first shaft being rotatable so as to rotate the or each first roller in a first direction;

- · said second shaft being rotatable so as to rotate the or each second roller in the opposite direction to the or each first roller;

- · said first and second shafts being rotatable such that the or each first and second rollers rotate towards each other when moving downwards;

- · the or each first roller being a soft resilient roller; and

- · the or each second roller incorporating one or more depressions on its surface.

Preferably the second roller is constructed from a hard material; more preferably that material is hard plastic.

In one embodiment, the first roller also incorporates depressions on its surface. Preferably, the first roller depressions are grooves along the length of the first roller, said grooves being parallel to each other.

Preferably the surface of the first roller has a membrane of resilient material. Preferably the resilient material is a polymeric material such as rubber (either natural or synthetic). More preferably, where the second roller is also a soft resilient roller, the surface of the second roller has a membrane of resilient material. Preferably the, or each, depression on the second roller extends the length of the roller. More preferably, the depressions are flutes that curve helically around the axis of the second roller. Alternatively the depressions are flutes that are parallel with the axis of the second roller.

Alternatively, the depressions on the surface of the second roller do not extend for the full length of the roller.

The present invention further provides the combination of a hopper adapted to contain a bulk supply of particulate material to be metered and the metering device, wherein the housing containing the first and second rollers is releasably attached below the hopper.

The present invention further provides apparatus for dispensing particulate material, said apparatus incorporating the above described metering device. Preferably, said apparatus is a seed drill. Preferably the apparatus includes a hopper adapted to contain a bulk supply of particulate material to be metered, the metering device located below said hopper, and means for driving the first shaft as to rotate the first roller in a first direction, and means for driving the second shaft as to rotate the second roller in the opposite direction to the first roller.

Brief Description of Drawings

By way of example only, a preferred embodiment of the present invention is described in detail below with reference to the accompanying drawings, in which:

Figure 1 shows a cross-section view through an apparatus incorporating a hopper and the metering device;

Figure 2 shows an end view of the rollers of the metering device of Figure 1 ; Figure 3a shows a side view of an embodiment of the second roller;

Figure 3b shows an end view of the second roller shown in Figure 3a;

Figure 3c shows a side view of a second embodiment of the second roller;

Figure 3d shows a side view of a third embodiment of the second roller;

Figure 4 shows a close-up, side view of a preferred embodiment of the second roller of Figure 3a;

Figure 5 shows end views of the metering device of Figure 1 in use, with particulate matter passing through the metering device; Figures 6 shows an end view of the rollers of a second embodiment of the metering device.

Best Mode for Carrying Out the Invention

The present invention relates to a metering device for for particulate material, and apparatus incorporating the metering device. Figure 1 shows a cross-section view of the metering device (10), in combination with a hopper (1 1 ). The metering device (10) and hopper (1 1 ) may be incorporated in any apparatus that requires a device for metering particulate and/or granular material, but will be described with particular reference to the purpose for which it was invented: a seed drill.

The hopper (1 1 ) is configured to hold a quantity of particulate material (50); where the metering device (10) is to be used with a seed drill, the particulate material (50) is seed. The bottom (12) of the hopper (1 1 ) is funnelled toward an outlet (13). The metering device (10) is located below the outlet (13), as can be seen in Figure 1 , and the particulate material (50) will tend to fall through the outlet (13) into the top of the metering device (10) due to gravity.

The metering device (10) includes a housing (20) with a housing inlet (21 ) on the upper surface of the metering device (10). The housing inlet (21 ) may be contiguous with the outlet (13) of the hopper (1 1 ). Within the housing (20) are a first roller (22) and a second roller (23) secured around a first shaft (24) and a second shaft (25) respectively. The shafts are mounted within the housing such that they are parallel to each other and their axes of rotation are horizontal, as can be seen in Figure 1 .

The rollers (22, 23) are immediately adjacent to each other, and arranged so that their curved surfaces contact each other, as shown in Figure 2. The rollers (22,23) are positioned across the housing inlet (21 ) as shown in Figure 1 , such that any particulate material (50) entering the housing inlet (21 ) falls onto the upper surfaces of the rollers (22, 23). The metering device (10) feeds at least one housing outlet (26), and the, or each, housing outlet (26) is in use connected by a chute to a drill tine or other seed-sowing apparatus, (not shown), in known manner.

The first roller (22) consists of a sleeve of resilient material rigidly secured (e.g. by gluing or molding) onto a metal sleeve, which is sized to be a sliding fit over the first shaft (24); this is best seen in Figure 2. The resilient sleeve forms a major part of the diameter of the first roller (22).

The resilient material could be any of a wide range of non-toxic materials not chemically reactive with seeds or seed coatings. Medium density open cell foam plastics materials have been found to be suitable. Preferably the foam material is a "no memory" foam, i.e. a foam which, after having been depressed, returns to its original shape rapidly, and tends not to become permanently deformed under pressure. Some polyurethane foams have been found suitable in this respect. In the most preferred embodiment, the resilient material of the first roller (22) is a foam, as previously described, and the surface of the resilient material has a resilient coating (130). Preferably this resilient coating is a polymeric material such as rubber (either natural or synthetic). Most preferably the resilient coating is spray-on latex.

The second roller (23) consists of a sleeve of rigid material, preferably rubber, which is sized to be a sliding fit over a second shaft (25), as seen in Figure 2. The rigid sleeve forms a major part of the diameter of the second roller (23). The surface of the second roller (23) includes at least one depression (27) in its surface.

In the most preferred embodiment, shown in Figure 3a, the surface of the second roller (23) is fluted, the flutes (27) extending from the first end to the second end of the roller. The fluting is helical about the axis of the roller, and the distance between the adjacent flutes is substantially identical, although this is not essential. Figures 3b and 3c show other, non-limiting embodiments of the second roller (23). In Figure 3b, the flutes (227) are straight and parallel to the axis of the second roller. In Figure 3c, the depressions are cavities (327) that do not extend the full length of the roller (23).

Preferably, to prevent any particulate matter from leaking down the sides of the rollers, by-passing the metering device, the ends of each flute (27) or groove can be blocked in any known manner. The preferred method of doing so is to include an end plate (32) as shown in Figure 4. The end plate (32) has the same diameter as the widest diameter of the second roller (23), and prevents seeds from leaking from the edges of the flutes (27). The shafts (24, 25) are rotated by driving a corresponding socket (not shown). This may be done by any suitable means e.g., drive sprockets secured to the ends of the shafts (24, 25) and connected to a drive band.

The shafts (24, 25) are rotated in opposite directions, as indicated by arrows A and B in Figure 2. Thus, both rollers (22, 23) rotate toward each other when moving downwards, as shown in Figure 2.

The above described embodiments show a single first roller and a single second roller, but it will be appreciated that each of the first and second rollers could in fact be a series of pairs of first and second rollers mounted end to end on the respective shafts. The above-described device is now described with particular reference to Figures 1 and 5, and is used as follows:- the hopper (1 1 ) and metering device (10) are mounted on a seed drill (not shown) and the, or each, housing outlet (26) is connected to drill tines, in known manner.

Seed (50) to be drilled is placed in the hopper (1 1 ). When the drill is in position over the area of land to be sown, the shafts (24, 25) are rotated by any suitable means to rotate the rollers (22, 23) attached to those shafts, in the directions of arrows A and B.

Seed (50) from the hopper (1 1 ) falls under gravity onto the top of the housing (20) and through the housing inlet (21 ) to contact the upper parts of the rollers (22, 23). The seed settles in a depression (27) in the second roller (23), and the rotation of the second roller draws the seed downward (arrow D in Figure 5). The first roller (23), being a soft, resilient roller, aids in the movement of the seeds (50) downwards through the rollers to fall into the housing outlet (26), the soft surface allowing the seed to be drawn through the rollers (22, 23) with little pressure, thus reducing the risk of crushing of the seeds (50). The resilience in the first roller (22) means that roller will retain its original shape once the seed has passed through the rollers (22, 23).

The rate of metering can be controlled by varying the rate of rotation of the rollers (22, 23), simply by adjusting the speed at which the shafts (24, 25) are driven. The size of the depressions in the second roller can also be varied depending on the seed size and the metering rate required. The metering rates of the device are set in known manner i.e. by rotating the drive with the device stationary, measuring how much seed is dispersed per shaft rotation and adjusting the drive as necessary to obtain the required rate.

In a second embodiment of the metering device, as shown in Figure 6, the first roller (122) and the second roller (123) are both made from resilient material, and the surfaces of both rollers (122, 123) include a series of grooves (127). The two rollers (122, 123) are preferably foam covered in a resilient coating (130); preferably the resilient coating (130) is a polymeric material such as rubber (either natural or synthetic), but most preferably is spray-on latex. The grooves in the two rollers aid in increasing the through-put of the metering device over the prior art by allowing seed to settle within the grooves before rotating toward each other. The grooves (127) also increase the "grab" on the seed over smooth, soft rollers, and thus encourage the seed to move downward between the rollers (122, 123). The inventor has found that the rubberized coating (130) on the foam rollers prevents seed from making a "full circuit" of the roller, i.e. the coating minimizes the occurrences where seed passes between the rollers, sticks to the surface of a roller, and completes a full circuit back into the store of seed. Reducing the number of times this occurs increases the accuracy of the metering device.

The present invention provides a benefit over the apparatus described in NZ 333057, as it increases the throughput of the metering device. The soft roller of the present invention works with the hard roller, supporting the particulate material, but not actively restricting the flow. This is in contrast to the soft roller of the second embodiment described in NZ 333057, which works against a hard roller.

The use of at least one roller incorporating flutes (or other types of depressions in the roller surface) that rotates towards the other roller greatly increases the throughput of the metering device over the prior art. The use of at least one soft resilient roller greatly aids in the reduction of crushed seeds, and where the, or each, soft resilient roller has a rubberised surface, the reduction of seeds completing "full circles" of the soft rollers decreases over "open cell" foam rollers.

Claims

Claims:

1 . A metering device for particulate material, the metering device including:

a housing supporting a pair of parallel substantially horizontal shafts;

a first shaft having at least one first roller mounted thereon and a second shaft having at least one second roller mounted thereon, the or each said first and second rollers being aligned opposite each other on their respective shafts and arranged such that the curved surface of the or each first roller is in surface contact with the curved surface of the or each corresponding second roller;

at least part of the upper surfaces of the or each first and second rollers being arranged such that in use particulate material to be dispensed can fall upon said part of the upper surfaces of the or each said first and second rollers;

said first shaft being rotatable so as to rotate the or each first roller in a first direction;

said second shaft being rotatable so as to rotate the or each second roller in the opposite direction to the or each first roller;

said first and second shafts being rotatable such that the or each first and second rollers rotate towards each other when moving downwards;

the or each first roller being a soft resilient roller; and

the or each second roller incorporating one or more depressions on its surface.

2. The metering device as claimed in claim 1 , wherein the or each first roller is formed with depressions on its surface.

3. The metering device as claimed in claim 2, wherein the depressions formed on the surface of the or each first roller are parallel grooves which extend along the length of the roller.

4. The metering device as claimed in any one of the preceding claims, wherein the surface of the or each first roller is provided with a membrane of resilient material.

5. The metering device as claimed in any one of the preceding claims, wherein the or each second roller is a soft resilient roller.

6. The metering device as claimed in claim 5, wherein the surface of the or each second roller is provided with a membrane of resilient material.

7. The metering device as claimed in any one of claims 1 - 4, wherein the or each second roller is made from a hard material.

8. The metering device as claimed in claim 7, wherein said hard material is a hard plastics material.

9. The metering device as claimed in any one of the preceding claims, wherein the depressions on the or each second roller extend the full length of the roller.

10. The metering device as claimed in any one of the preceding claims, wherein the depressions on the or each second roller are formed as spaced flutes which curve helically around the axis of said roller.

1 1 . The metering device as claimed in any one of claims 1 - 9, wherein the depressions on the or each second roller are formed as spaced flutes which extend parallel to the axis of said roller.

12. The metering device as claimed in any one of claims 1 - 8, wherein the depressions on the or each second roller do not extend the full length of the roller.

13. The metering device as claimed in any one of the preceding claims, wherein the or each second roller is formed with a plate at each end thereof, each plate being arranged to block the ends of said depressions adjacent the ends of the roller.

14. A device for dispensing particulate material which includes a hopper adapted to contain a bulk supply of particulate material to be metered in combination with a metering device as claimed in any one of claims 1 to 13.