NL2015681B1 - Arthropod distributor having a centrifugal spreader wheel with widening compartments. - Google Patents

Abstract

An arthropod distributor (1) comprises a centrifugal spreader wheel (20) that is rotatable around a central axis (C) and a first drive (21) for driving the centrifugal spreader wheel in rotation. The wheel comprises a number of vanes (24) that extend at least partly in between the central axis and an outer circumference of the wheel. The wheel has a bottom plate (22) and a top plate (26). The vanes extend in between the bottom and top plates for forming compartments that open out towards the environment via outlet openings (31) lying in between the bottom and top plates. At least one inlet opening (27) is provided that connects an arthropod supply (2) to the compartments such that living arthropods supplied to this at least one inlet opening get centrifugally thrown out of the compartments via the outlet 10 openings into the environment when the spreader wheel is driven in rotation.

Description

Title: Arthropod distributor having a centrifugal spreader wheel with widening compartments.

The invention relates to an arthropod distributor for distribution of living arthropods, like predatory mites, parasite wasps, and assassin bugs, in crop for performing a positive role in biological pest control.

Such arthropod distributors are known in various variants. For example it is known to manually distribute the living arthropods over the crop. It is also known to hang small containers, like pouches, at various locations above or in between the crop, out of which the arthropods themselves need to find their way via one or more outlet openings.

Other known devices use blow systems for forcedly blowing the arthropods through the air over the crop. For example DE 4424499 discloses a device in which arthropods can get distributed by means of such blowing. With this a mixture of the arthropods and a support and/or dissemination substrate material that is selected from inert substrates, such as, for example, particles of vermiculite, particles of pearlite, bran, vermiculite, saw/wood dust or mixtures thereof, is supplied from a reservoir into an air blowing channel. A stream of air which is blown at high velocity through the channel by means of a ventilator then takes along and forcefully blows the arthropods over distances of several meters above the crop.

However in practice it has been found that maintaining the quality of arthropods throughout the application and realising an optimal distribution in the crop from the start is a big challenge. This makes it necessary to use less blowing force and/or distribute larger amounts of arthropods at more locations in the crop. This is time-consuming and laborious, and also more expensive. It may also happen that an aimed biological pest control then cannot take place as intensively as necessary, with the effect of lower quality/production of the crop, a higher need of using chemicals to control the pests or even crop failure.

An arthropod distributor according to the preamble of claim 1 is known from WO 2008/084355. This distributor comprises a rotary dispersing disc on top of which radially extending flaps are present. A hopper is provided above the rotary dispersing disc. A fixedly mounted disc is provided below the hopper at a distance above the rotary dispersing disc. In this upper disc an eccentrically positioned slit-shaped through hole is provided. The hopper projects with its outlet through this slit-shaped through hole. A disadvantage here is that arthropods that during use fall downwards onto the rotating dispersing disc immediately get hit by one of the flaps. Depending on the speed of the dispersing disc this may damage or even kill large amounts of the arthropods.

The present invention aims to overcome those disadvantages at least partly or to provide a usable alternative. In particular the invention aims to provide an animal-friendly arthropod distributor which is able to distribute living arthropods over distances of more than 1 meter in such a way that killing or damaging of the arthropods is minimized as much as possible. More in particular this invention at a same time aims to ensure a uniform distribution in the crop to improve efficacy and efficiency of the biological control of pests.

This aim is obtained by an arthropod distributor for distribution of living arthropods, in particular predatory mites, in crop according to claim 1. This distributor comprises a spreading device for spreading the living arthropods through the environment, and an arthropod supply for supplying said living arthropods towards the spreading device. According to the inventive thought the spreading device comprises a centrifugal spreader wheel that is rotatable around a central axis. The distributor further comprises a first drive for driving the centrifugal spreader wheel in rotation around its central axis. The centrifugal spreader wheel comprises a number of vanes that extend at least partly in between the central axis and an outer circumference of the centrifugal spreader wheel. Furthermore the centrifugal spreader wheel has a bottom plate and a top plate, with the vanes extending in between the bottom and top plates for forming compartments that are delimited downwardly by the bottom plate, upwardly by the top plate and sideways by respective ones of the vanes and that open out towards the environment via outlet openings that lie in between the bottom and top plates. At least one inlet opening is provided that connects the arthropod supply to the compartments such that living arthropods supplied to this at least one inlet opening get centrifugally thrown out of the compartments via the outlet openings into the environment when the centrifugal spreader wheel is driven in rotation.

The centrifugal spreader wheel has appeared to be well able to gently and efficiently distribute the living arthropods over the crop. In fact it has even appeared possible to have less than 10% of the vulnerable arthropods get killed or seriously damaged owing to the present invention. Thus, compared to the already known state of the art air blow distributors, an impressively larger number of fit arthropods is able to perform its biological pest control function in the crop. This leads to lower costs, healthier crop, higher production and profits, and to less hazardous pesticides being necessary during cultivation.

The centrifugal spreader wheel with its upwardly and downwardly delimited compartments lying between the bottom and top plates not only accelerate the living arthropods outwardly along the vanes through the compartments because of centrifugal forces, but also are able to make use of a pressure difference between the inlet and outlet openings that automatically starts to occur during the distribution process. The closer the arthropods get towards the outer circumference, the higher the circumferential speed they get to undergo. When reaching the outlet openings at or near the outer circumference of the centrifugal spreader wheel, the arthropods then are thrown out and away from the centrifugal spreader wheel. Because of this the arthropods start to fly through the air while only being slightly counteracted by gravity and air friction.

It is noted that the occurrence of the abovementioned pressure difference between the inlet and outlet openings of the compartments in between the vanes and the bottom and top plates is deemed to have a protecting effect on the vulnerable arthropods during the spreading. The top plate largely closes of the compartments in between the vanes and the bottom plate. Since the rotating spreader wheel transports the arthropods radially outwards, an underpressure is deemed to occur in the outlet openings compared to a pressure at or near the inlet opening(s). This pressure difference shall cause the arthropods to get smoothly sucked out of the supply into the compartments without having to be forcedly pushed into those compartments. Furthermore a positive flow of air may start to occur between the inlet and outlet openings that might slightly lift up the lightweight arthropods and help them to smoothly and gently move through the compartments towards the outlet openings. A film of air may help to minimize direct contact between the arthropods, the plates and the vanes.

The underpressure also is deemed to help in equalizing the distribution of the arthropods over the various compartments.

Thus the invention advantageously has appeared to be able to make it possible to obtain a truly uniform spreading of the arthropods over the crop with only a minimum damage being observed for the arthropods that have been spread over the crop. It is noted that the spread population of living arthropods in particular comprises adult individuals, larvae and/or nymphs thereof, but in addition thereto also can comprise eggs thereof or mixtures of these various stages. It may even be possible to add food particles to such mixtures for stimulating and conserving populations of biological pest control arthropods in crops at required levels.

It is noted that DE 10 2010 009 510 shows a rotary spreading disc with a bottom and top plate, between which radially extending throwing wings are provided. This spreading disc however is destined to be used for spreading ice granules. It is not destined to be used for spreading arthropods, nor is it suitable therefore. For example it comprises biased closing plates that extend in between adjacent vanes at the side of a central inlet. Arthropods would be unable to help pushing such closing plates towards open positions during use. Depending on the biasing force of the closing plates this may damage or even kill large amounts of arthropods. Furthermore the throwing wings at their inner ends are sharp edged and thus would form undesired obstacles for arthropods.

It is further noted that US 8,191,804 shows a fertilizer dispenser with a rotary disc having a plurality of radial blades positioned thereon. The rotary disc is positioned beneath a dispersal opening of a frustoconical housing. A disc-shaped bottom plate of the housing lies at a distance above the rotary disc. In this bottom plate the dispersal opening is provided at an eccentric position above the rotary disc. This rotary disc however is destined to be used for spreading fertilizer granules. It is not destined to be used for spreading arthropods, nor is it suitable therefore. For example arthropods during use then would fall downwards at an eccentric position onto the rotating disc and there immediately get hit by one of the blades. Depending on the speed of the disc this may damage or even kill large amounts of the arthropods.

The arthropod distributor according to the present invention can be hung at a stationary position above the crop and from there distribute the arthropods over the crop. Preferably however it gets displaced in a longitudinal direction over and/or along rows of the crop. For this a dedicated transportation device can be provided. It is also possible to mount the distributor to other devices that also need to be transported over and/or along the crop, for example a spraying device for pesticides.

The compartments may have all kinds of shapes. In an advantageous embodiment the compartments however are constructed such that they widen towards the outer circumference. For example the compartments may be wedge-shaped seen from above. This widening shape helps to increase the pressure difference between the inlet and outlet openings during use, and thus may help in keeping the vulnerable arthropods undamaged while getting transported through the compartments.

In a preferred embodiment the vanes may start at the central axis of the centrifugal spreader wheel. Thus it can advantageously be prevented that the arthropods may bump against inner ends of the vanes. This helps to get even further improved rates of living undamaged arthropods to be spread with the distributor.

In the alternative or in addition thereto the vanes may be constructed such long that they end at the outer circumference of the centrifugal spreader wheel. Thus the content of the compartments is optimized and the vanes are well able to keep on helping the transport of the arthropods towards the outlet openings.

In a further preferred embodiment the vanes may be constructed gutter-shaped. In particular the vanes may have concave curved cross-sections. The gutter shape causes the arthropods to move towards the middle of the vanes while getting transported radially outwards towards the outlet openings. This helps to further minimize contact between the arthropods and the plates, which in turn helps to keep them undamaged and fit.

The at least one inlet opening advantageously may be provided in the top plate.

Owing to this the supply can be positioned directly above the inlet opening, and the arthropods may fall freely downwards into the inlet opening, and then get sucked further into the compartment because of the occurring centrifugal forces and pressure differences.

In a further embodiment the inlet opening in the top plate can preferably be positioned centrally around the central axis. Thus the spreader wheel can be rotated together with the inlet opening, while the inlet opening is able to maintain its position relative to the supply.

In a further embodiment a cone can be provided that projects upwardly from the bottom plate into the inlet opening. Arthropods that are supplied to the inlet opening then automatically get equally distributed over the various compartments. The cone may form an integral connection organ between the various vanes such that no dead spots are formed inside the spreader wheel at that location.

The inlet opening in the top plate advantageously can be delimited by an upwardly projecting circumferential entrance wall part of the top plate, in particular a funnel-shaped wall part. This may help to catch any downwardly falling arthropods and guide them gradually towards and into the spreader wheel compartments.

The bottom and/or top plate may be substantially flat and extend substantially perpendicular to the central axis, that is to say in a substantially horizontal direction when the central axis extends substantially vertically. It is also possible to construct the bottom and/or top plate somewhat dish-shaped with angled surfaces delimiting the compartments such that those surfaces extend slanted upwards starting at the central axis. In particular an angle can then be enclosed of less than 90 of up to 50 degrees between said surfaces of the bottom and/or top plate and the central axis. The advantage hereof is that the compartments and vanes then may get directed somewhat upwardly slanting, which helps to throw out the arthropods not only outwards but also slightly upwards and make it possible to obtain larger spreading widths.

The arthropod supply may comprise a hopper that is positioned above the centrifugal spreader wheel. This hopper can easily be filled with an amount of the arthropods, if necessary mixed with some kind of support and/or dissemination substrate material that is selected from inert substrates, such as, for example, particles of vermiculite, particles of pearlite, bran, vermiculite, saw/wood dust or mixtures thereof. This support and/or dissemination substrate material helps to create air spaces in between the arthropods such that they are able to breath during transport and distribution. Also this makes it possible to manipulate the arthropods inside the centrifugal spreader wheel more easily without damaging or killing them.

The hopper then preferably may be dimensioned such that it widens downwardly.

Thus bridge formation of the arthropods and/or support and/or dissemination substrate material inside the hopper can be efficiently prevented, and it can be guaranteed that the entire content of the hopper get emptied into the centrifugal spreader wheel and distributed over the crop. A dosing organ can advantageously be provided in between the arthropod supply and the inlet opening of the centrifugal spreader wheel. The provision of such a dosing organ makes it possible to actively steer and control the amounts and rates at which the spreader wheel gets fed with arthropods during rotation.

The dosing organ can be formed by some kind of valve that can be placed in various opening positions for having larger or smaller amounts to pass by it per unit of time. In a preferred embodiment the dosing organ however may comprise a rotatable organ like a rotatable brush. A second drive then can be provided for driving the dosing organ in rotation.

The rotatable organ preferably is formed by a toothed wheel with transportation chambers lying in between the teeth. During rotation, the chambers between the respective teeth shall automatically get filled with the arthropods from out of the supply. By varying the rotation frequency of the toothed wheel, it is possible to control the spreading amount. The centrifugal spreader wheel than can even be rotated at constant speed. The frequency for example can be controlled by using a continuously variable electromotor as second drive. Another advantage of the rotating toothed wheel is that it helps the arthropods and/or support and/or dissemination substrate material inside the supply to keep get mixed and keep on moving. Owing to this the spreader wheel is deemed to get a better grade of uniform filling.

Further preferred embodiments are stated in the dependent subclaims. The invention also relates to a use of the distributor for spreading living arthropods in a crop, in particular in crop that is cultivated inside a greenhouse.

The invention shall be explained in more detail below with reference to the accompanying drawings in which: - Fig. 1 shows a front view of an embodiment of the arthropod distributor according to the invention; - Fig. 2 shows a cross-sectional view over the line A-A in fig. 1; - Fig. 3 shows a perspective view of the centrifugal spreader wheel of fig. 1; - Fig. 4 shows a top view of fig. 3 with vanes that lie underneath the top plate indicated with dotted lines; - Fig. 5 shows a sectional view over the line A-A in fig. 4; - Fig. 6 shows a side view of fig. 3; and - Fig. 7 shows a schematic front and side view of a greenhouse with the distributor device of fig. 1 guided displaceable over rails therein.

In fig. 1 and 2 the arthropod distributor has been indicated in its entirety with the reference numeral 1. The distributor 1 comprises a hopper 2 which is filled with a mixture of living predatory mites and a support and/or dissemination substrate material 3. The predatory mites are such small that they cannot be seen by the eye without a microscope. The hopper 2 has two opposing side-walls 4 that diverge downwards such that the hopper 2 is wider at its lower end than at its upper end. A filling level indicator 5 has been provided in the hopper 2.

At its lower end the hopper 2 comprises a downwardly tapering funnel part 8. A toothed dosing wheel 10 is provided which is rotatable around a substantially horizontal axis X by means of a drive 11, that here is formed by a frequency controlled electromotor. The toothed dosing wheel 10 extends with an upper part into the funnel part 8 of the hopper 2 such that chambers 11 that lie in between teeth 12 of the wheel 10 get automatically filled with amounts of the mixture of the mites and support and/or dissemination substrate material each time they pass through the funnel part 8 of the hopper 2. Below the funnel part 8, a bearing house 14 is provided which delimits a semi-cylindrical space that is complementary to the toothed wheel 10, that is to say that the respective teeth 12 thereof substantially get to slide alongside a cylindrical inner wall of the bearing house 14 during rotation of the toothed wheel 10. At its lower end the bearing house 14 is provided with a dispensing opening 15 via which the dosing wheel 10 can empty its chambers 12 of their amounts of the mixture of mites and support and/or dissemination substrate material when those chambers 12 get to move along this dispensing opening 15.

Below the dispensing opening 15 a centrifugal spreader wheel 20 is provided which is rotatable around a substantially vertical axis Y by means of a drive 21, that here is formed by a single-speed electromotor.

As can be seen in fig. 3-6, the spreader wheel 20 has a central axis C and comprises a disc-shaped bottom plate 22. In its center this bottom plate 22 is provided with an integrally formed upwardly projecting cone 23. Furthermore the bottom plate 20 is provided with a plurality of vanes 24. The vanes 24, seen in cross-section, are gutter-shaped, and are integrally connected with lower sides to the bottom plate 22. Furthermore the vanes 24 are integrally connected with their inner ends to the cone 23. The vanes 24 extend outwardly from the cone 23 towards an outer circumference of the wheel 20. In fig. 4 it can be seen that longitudinal directions of the vanes 24 lie substantially parallel to radial directions of the wheel 20.

The spreader wheel 20 furthermore comprises a disc-shaped top plate 26. The top plate 26 comprises a central inlet opening 27 that is delimited by an upwardly projecting funnel-shaped circumferential entrance wall part 28 that forms an integral part of the top plate 26. The bottom and top plates 22 and 26 are somewhat dish-shaped. Wall parts of the plates 22 and 26 that delimit the compartments 30 in the shown embodiment are slightly angled at an angle a of approximately 5 degrees relative to the horizontal. Larger or smaller angles are also possible, depending on aimed maximum spreading distances that need to be obtained.

In its fixedly mounted position the top plate 26 lies with its lower side on top of the vanes 24. The cone 23 then points out centrally with a circumferential play into the inlet opening 27. Compartments 30 are formed that are delimited downwardly by the bottom plate 22, upwardly by the top plate 26 and sideways by respective ones of the vanes 24. The compartments 30 are wedge-shaped, start pointed in the middle of the wheel 20 and from there widen out towards the outer circumference of the wheel 20 where they open out to the environment via outlet openings 31.

During energizing of the drives 11,21, the dosing wheel 10 and spreader wheel 20 are driven in rotation and amounts of the mites and support and/or dissemination substrate material that get dosed into the dispensing opening 15 by the dosing wheel 10 fall down under gravity into the inlet opening 27 of the spreader wheel 20. This stream of the mites and support and/or dissemination substrate material is indicated in fig. 5 with arrow M. From there those amounts are substantially equally divided by the cone 23 over the various compartments 30. Owing to the rotation of the spreader wheel 20, the amounts of the mites and support and/or dissemination substrate material then start to move through the compartments 30 along the gutter-shaped vanes 24 in the direction of the outlet openings 31. Owing to this centrifugal transportation also a stream of air starts to flow from out of the environment into the inlet opening 27 and then outwards through the compartments 30. This stream of air is indicated with the arrow A. The individual particles, that is to say the respective mites and the support and/or dissemination substrate material, then get thrown via the outlet openings 31 away into the environment.

For example the spreader wheel 20 can be rotated at speeds of between 500-1500 rpm while having an outer circumferential diameter of between 100-300 mm. Spreading distances of between one to several meters then can easily be obtained with a survival rate of more than 90% of fit undamaged mites. In practice even rates of more than 95% have been accomplished.

The distributor 1 is provided with a hinged support 35 with which it can be hung to a transportation device for moving it in a longitudinal direction overcrop. This hinged support 35 is able to take up any acceleration and deceleration forces that may occur during start and stop. Furthermore it is able to have the distributor 1 hang in a same position underneath such a transportation device, such that a substantial uniform spreading image can be obtained during the transportation. The spreader wheel’s central axis C then in particular extends substantially vertical.

In fig. 7 a greenhouse 40 for cultivation of crop on cultivation beds 41 is schematically shown. The cultivation beds 41 have widths w of several meters, for example between 5-15 meters. Inside this glasshouse 40, rails 42 are provided which extend in a horizontal direction at a height h above the crop. A transportation beam 43 hangs below the rails 42. The beam 43 is provided with a number of the distributors 1. The sideways interspacing between the distributors 1 is such that their circular spreading images overlap and that they together span the entire width of the corresponding cultivation bed 41.

During use the drives of the distributors 1 are energized and they each shall start to spread their mixtures of mites and support and/or dissemination substrate material in circular spreading images underneath them. A suitable drive is provided for at the same time actively displacing the beam 43 back and forth along the rails 42 in a transportation direction t that is perpendicular to the beam 43.

It is noted that distributors 1 are each hingedly connected to the beam 43 by means of their hinged supports 35 in such a way that the swinging axis of the hinged supports 35 lies parallel to the beam 43. This has the effect that each time the beam 43 gets stopped to move in the transportation direction t, the then occurring deceleration forces shall cause the distributors 1 to swing around their hinged supports 35 while continuing to spread the mixtures of mites and support and/or dissemination substrate material particles. In this way it can be effectively guaranteed that outer ends of the cultivation beds 41 also get well provided with the required amounts of mites.

Besides the embodiments shown numerous variants are possible. Instead of using the distributor for mites it can also be used for distribution of other types of useful arthropods for biological pest control. The dimensions and shapes of the various components may be varied. For example the number of vanes and compartments of the spreader wheel can be chosen smaller or larger, and depending on the type of arthropods and support and/or dissemination substrate material that needs to be distributed, the number and size offer example the chambers of the toothed wheel can be varied. The spreader wheel preferably is made out of plastic because of its low friction coefficient for the arthropods and easy manufacturing, but also can be made out of other materials like metal. Likewise the dosing unit and the bearing housing are also preferably made out of plastic, whereas other materials here are also possible. Instead of using a toothed wheel as dosing organ it is also possible to use other types of mechanically operating dosing organs, like a brush or a transportation screw. It is also possible to have the mixture of arthropods and support and/or dissemination substrate material merely fall under gravity out of a supply into one or more inlet openings of the spreader wheel. Instead of using a hopper it is also possible to use other types of containers or supply. The supply does not need to be positioned above the spreader wheel but can also feed the spreader wheel from out of other directions.

Thus according to the invention an economic and user-friendly arthropod distributor is obtained with which the arthropods can be distributed in an efficient automated manner over crop in a greenhouse or the like.

Claims (14)

An arthropod distributor (1) for dividing live arthropods into plants, comprising: a spreading device for spreading the live arthropods over the environment; an arthropod supply for supplying the live arthropod to the spreading device; wherein the spreading device comprises a centrifugal spreading wheel (20) rotatable about a central axis (C), the distributor further comprising a first drive (21) for rotating the centrifugal spreading wheel (20) about its central axis (C), wherein the centrifugal spreading wheel (20) comprises a number of blades (24) extending at least partially between the central axis (C) and an outer circumference of the centrifugal spreading wheel (20), characterized in that the centrifugal spreading wheel (20) has a bottom plate (22) and has a top plate (26), wherein the blades (24) extend between the bottom and top plates (22, 26) to form compartments (30) that are downwardly bounded by the bottom plate (22), upwards through the top plate (26) and laterally through the blades (24) and which open to the environment through outlet openings (31) lying between the bottom and top plates (22, 26), at least one inlet opening (27) being for see which connects the arthropod supply to the compartments such that live arthropods supplied to this at least one inlet opening (27) are centrifugally ejected from the surrounding compartments via the outlet openings (31) when the centrifugal spreading wheel (20) becomes rotating powered. Distributor (1) according to claim 1, wherein the compartments (30) widen in the direction of the outer circumference. Distributor (1) according to one of the preceding claims, wherein each blade (24) extends substantially parallel to one of respective radial directions. Distributor (1) according to one of the preceding claims, wherein the blades (24) start at the central axis (C) of the centrifugal spreading wheel (20). Distributor (1) according to one of the preceding claims, wherein the blades (24) open out onto the outer circumference of the centrifugal spreading wheel (20). Distributor (1) according to one of the preceding claims, wherein the blades (24) are channel-shaped, in particular with a concave curved cross section. Distributor (1) according to one of the preceding claims, wherein the at least one inlet opening (27) is provided in the top plate (26), in particular centrally around the central axis (C). Distributor (1) according to claim 7, wherein a cone (23) is provided which projects upwards from the bottom plate (22) inwards into the inlet opening (27). Distributor (1) according to one of the preceding claims, wherein the inlet opening (27) is bounded by an upwardly projecting circumferential entrance wall part (28) of the top plate (26), in particular a funnel-shaped wall part. Distributor (1) according to one of the preceding claims, wherein the bottom and / or top plate (22, 26) are at an angle (a) such that they extend obliquely upwards starting at the central axis (C) , in particular at an angle (a) of less than 90 to 50 degrees between the bottom and / or top plate (22, 26) and the central axis (C). The distributor (1) according to any of the preceding claims, wherein the arthropod supply is a hopper (2) positioned above the centrifugal spreading wheel (20). Distributor (1) according to one of the preceding claims, wherein a dosing device is provided between the arthropod supply and the inlet opening (27) of the centrifugal spreading wheel (20). The distributor (1) according to claim 12, wherein the metering member comprises a toothed wheel (10), and wherein the distributor (1) further comprises a second drive (11) for rotatingly driving the toothed wheel (10). Use of the distributor (1) according to one of the preceding claims, for spreading live arthropods in a crop, in particular in crop cultivated within a greenhouse.