GB2168666A - Singulator - Google Patents

Abstract

A potato singulator 10 comprises an endless conveyor 12 with convoluted flexible tubular sleeves 22 capable of expanding from a closed position (right-hand side of Fig. 1) where the convolutions are touching or in close proximity progressively to an open position (left-hand side of Fig. 1) where the convolutions have moved apart to separate the potatoes. The sleeves are expanded by suitably disposed cam surfaces engaged by the ends of sleeves. The conveyor may be driven intermittently. <IMAGE>

Description

SPECIFICATION Singulator The present invention relates to a singulator and in particular, but not exclusively, to a singulator for agricultural products, e.g. potatoes and other tubers.

The term "singulation" is to be interpreted throughout the specification as meaning "the act of causing items in an initially disorganised state, to be organised into a more regular configuration although not necessarily oriented in a particular way". The term "singulator" is to be interpreted as meaning an apparatus for effecting singulation as above defined.

The process of singulation is the subject of many prior patents with specific applications in industry such as packaging biscuits or cigarettes. Where the objects to be singulated are of uniform size and shape, the process is relatively simple. Thus, in dealing with those agricultural products in which there is uniformity, few problems arise. For example, the relative uniformity of shape, makes egg singulation and packaging feasible though their delicate nature requires careful design of the handling components. In the case of potatoes and other tubers, however, there is a wide spectrum of both size and shape and acceptably effective singulation devices are rare. One such, uses a series of groups of round-section belts travelling with progressively increasing velocity and troughed to encourage the formation of a single line of tubers.At each transfer point in the series, the velocity is increased to encourage spatial separation of the tubers, which may initially be contiguous or overlapping in the row. However, such a device by virtue of its design tends to be long, occupying considerable space. Moreover, it is only capable of feeding one sizing head. Thus to obtain adequate throughput, high tuber velocities are required or a multiplicity of singulators and sizing heads. This may lead to tuber damage.

Other known devices include compartmented conveyors with various mechanical devices such as rotary brushes which attempt to minimise the number of doubles in the compartments. Here the difficulty is to avoid doubies when the tuber size range is large.

It is an object of the present invention to provide a singulator in which these drawbacks are avoided or at least significantly reduced.

According to the present invention, a singulator as hereinbefore defined comprises a conveyor adapted to convey the items to be singulated in a first direction and expansion means for expanding the conveyor in a substantially horizontal second direction having at least its principal component at right angles to the first direction.

Conveniently, the conveyor comprises a plurality of elongate sections with each section coupled to the preceding and following sections of the conveyor and extending across a width dimension of the conveyor.

Conveniently, the expansion means operates to expand each conveyor section progressively across the width of the conveyor as it moves from a load-accepting first location to a loaddischarging second location.

Conveniently, each section comprises an axially-expandable roller element, e.g. biased towards either a maximum-length or minimumlength configuration as the case may be.

Conveniently, in this case, the length of each section is controlled by a suitably disposed cam surface engaged by end portions of the roller elements or by some part moving with these end portions. In one such embodiment, there are two such cam surfaces operative together to move the two ends of each section in opposite directions to one another.

Conveniently, retraction means are provided at a load-discharging location of the conveyor to retract the end section (or sections) at that location in order more positively to discharge the load therefrom.

As an alternative, the conveyor may be driven by a sprocket having sufficiently few teeth to impart a cyclical movement to the conveyor drive. In this case, a flexible arrester flap may be provided to maintain the singulation of objects in transit from the conveyor to a different location.

As a second alternative, a tilt tray may be provided in which items received from the conveyor will dwell momentarily before discharge to a different location.

Conveniently, in the latter case, the tilt tray is supported by crossed pivotal links.

As already indicated, singulators according to the present invention are especially suited for sorting potatoes and other tubers. Thus, according to another aspect, the invention further includes a singulator adapted to take potatoes or other tubers from a bulk hopper, marshal them into single lines in which they may be contiguous and even overlapping and then effect spatial separation of the tubers from each other so that they can be presented singly to a sizing head (which uses weight, or optical, or other sizing means).

Where high throughputs are required, such a singulator could supply several sizing heads.

The singulators of the present invention could also form the basis for seed planting equipment and the invention also includes such equipment.

An embodiment of the invention will now be described, by way of example only, with reference to the accompanying drawings in which: Figure 1 is a plan view of part of a singulator according to the present invention; Figure 2 is an end view (looking from right to left in Figure 1); Figure 3 is a side view of the discharge end of the singulator; and Figures 4 and 5 are side views of the discharge ends of the alternative designs of singulator.

Thus referring first to Figures 1 to 3 of the drawings, a singulator 10, according to the present invention uses as a basis for singulation a conveyor in the form of a roller table 12 in which the rollers may commence in a sloping area (not shown) forming the base of a small feed hopper. Alternatively the table 12 may receive potatoes (or other tubers) directly from another conveyor (not shown) capable of feeding it across its full width to maximise capacity.

The rollers of table 12 are carried by two hollow pin roller chains 16, 17 and their square-section drive shafts 18 have spindles passing through the hollow pins of the chains.

The millers are caused to rotate by pinions 19 attached to the rollers at one end by anchoring collars 20. The pinions 19 engage with a rack 21 alongside one of the two carrier chains 16, 17.

The rollers of table 12 differ in configuration from normal rollers in so far as they comprise tubes 22 of convoluted rubber (or other flexible material) anchored at the same end of the shaft 18 as pinions 19. At the other end, the tubes are clamped to slide blocks 24 carried in bearing blocks 26. These latter are moulded in pairs joined by bridge pieces 28 which carry spigots and rollers 30, 31.

The slide blocks 24 have square apertures enabling each slide block to rotate within its associated bearing block 26 but also able to allow the bearing block to slide along the square shaft 18 without imparting any rotation relative to the fixed ends of the rubber tubes 22 (which would cause the tubes to distort).

In an alternative embodiment (not shown), the shafts 18 could be of tubular circular cross-section with a suitable groove to ensure that the fixed collars 20 and slide blocks 24 could not be angularly displaced relative to one another.

In another variant, the bridge pieces 28 are omitted and each tube 22 has its own individual spigot and roller assembly. In this case, however, the tubes would have to be provided with other rotation-inhibiting devices in place of the bridge pieces 28. They could, for example, have square section end pieces moving in an appropriate channel section at the side of the roller table.

Returning now to the illustrated embodiment, at a suitable point underneath the roller table 12 an angled preferably double-faced cam rail 33 is positioned. In Figure 1, only one side of the rail is shown. In a modification (not shown), the single rail 33 is replaced by a pair of diverging cam rails and both ends of the rollers are moved apart simultaneously.

As the rollers of table 12 are carried along towards the delivery point by the two side carrier chains 16, 17, the rollers 31 on the spigots 30 engage with the inner face of the double-faced cam rail 33 causing the slide blocks 24 with convoluted tubes 22 to move sideways relative to the fixed collars 20.

The carrier chains 16, 17 are preferably restrained in order to prevent lateral displacement of the chains by the thrust of the expanding and contracting support rollers of table 12. One way of doing this is to have vertical-axis guide rollers or the like e.g. a slide rail with a suitable bearing surface (not shown) rotatably secured to the frame of the apparatus and contacted by the side plates of the chains 16, 17.

Conveniently, these guide rollers or the like would be located adjacent the outermost side plates of the top run of chain 17 and adjacent the outermost side plates of the bottom (return) run of chain 16.

At an appropriate point, the rotation of the crop-supporting rollers of table 12 is stopped by terminating the driving rack (not shown) situated at the side of one of the carrier chains 16, 17.

The potatoes 35 which may be contiguous, or overlapping prior to the expansion of the convoluted tubes 22, are separated spatially by the action of the tube expansion. When they reach the end of the roller table 12 they are substantially fully singulated. The distance between adjacent tubers is, to an extent, dependent on the proximity of their nearest contact points on the convolutions prior to expansion. Thus, if these points are 20 mm apart, after expansion they may be up to 60 mm apart, depending on how much slippage occurs. The ratio of closed to open tube dimensions is approximately 3:1 in the illustrated embodiment, though other ratios would be possible. There are approximately 5 convolutions per 25 mm when the tubes are in the closed position.

On reaching the end of the conveyor, the potatoes are delivered either to a flighted cross conveyor 40 (shown only in Figure 3) or, in an alternative embodiment, to a conveyor travelling in the same direction as the roller table 12 (this latter version not being shown).

To achieve a sharp ejection of the entire row of tubers, provision is made to alter the pattern of rotation of the rollers round the drive sprocket 42 (Figure 3). Instead of passing round this sprocket, the carrier chains (which have approximately 75 mm pitch in this example) continue over a sliding rail assembly comprising a fixed part 44 and a moving part 45, the drive being assured by an anti-jump rail 46 which holds the chain down in this area.

The sliding rail part 45 is caused to move linearly at the same speed as the chains by the thrust of a cam roller 48 actuated by an Archimedean spiral cam 50. The drive shaft for cam 50 is driven through a chain transmission layshaft 52 from the drive sprocket 42.

When a full pitch has advanced, the vertical step in the cam 50 allows the slide to rapidly retract under the action of a pair of compression springs mounted on part 44 on either side of part 45. Only one of these (spring 54) is visible in Figure 3. The end roller 55 now drops under the action of gravity and a chain tensioner (not shown), allowing potatoes to be rapidly and simultaneously ejected to land on the flighted conveyor 40. The flights 56 of this conveyor are pitched closely (25 mm) and angled at 45 , although other shallow angles could be used. They are troughed towards the middle to encourage potatoes to lie centrally on the belt. The angle of the flights and compliance of the rubber, or other material, of the conveyor 40, is intended to ensure that when a potato lands on the flights it will depress those immediately underneath.The first rearward flights not so depressed, then perform the function of a back stop in helping to accelerate the potatoes in the direction normal to the plane of the drawing.

The right-hand side of Figure 1 shows a pair of convoluted tubes in the closed position with the newly loaded potatoes contiguous and a very wide size range. The left-hand side of the same Figure shows the configuration after expansion.

Turning now to Figure 4, this shows a detail of an alternative embodiment in which the drive sprocket has now been repositioned adjacent the cross conveyor 40 and the ejection mechanism 44-50 omitted.

Preferably the sprocket 58 will have only a few teeth e.g. six or thereabouts, so as to impart a somewhat cyclical motion to the roller chain drive. If desired, a suitable drive mechanism (not shown) can be used to enhance this effect e.g. an elliptical driving sprocket or a geneva wheel mechanism.

Reference numeral 60 in Figure 4, indicates a flexible arrester flap designed to maintain the singulation of the potatoes during their transfer to the cross conveyor 40. The position of the flap is adjustable in the vertical and/or horizontal planes. It is preferably made from flexible rubber belting or equivalent material.

Figure 5 shows a further embodiment in which the arrester flap of the previous version is replaced by a tilt tray 62 adjustably positioned to catch the potatoes as they roll from the expanded rollers of the roller table 12.

As shown in the drawings, the tilt tray 62 is pivotally supported at the bottom ends of two pairs of crossed pivotal links 64, 65 of which only one of each pair is visible in the view of Figure 5.

The discharge mechanism further includes a suitable six-lobed cam (not shown) fixed to the drive shaft of the sprocket 58 or to another shaft (not shown) arranged to travel at the same speed as the sprocket shaft. A lever (not shown) connects the tilt tray (or its links) with the cam so as in operation to cause the tilt tray to swing to its discharge position 67 and back again for each row of potatoes discharged from the roller table 12.

In operation, the cross-sectional shape of the tray 62 and the geometry of the links 64, 65 is such that the potatoes will dwell momentarily on the tray before it swings rapidly back to off load the potatoes on to the belt 40.

In variations of the transfer arrangements shown in Figures 3, 4 and 5, the flighted belt 40 is replaced by a longitudinally channelled belt moving in the same directions as the roller table 12.

In the event of handling exceptionally heavy produce such as large potatoes, or other heavy materials, it may be necessary to assist the even opening of the tubes against the drag of the produce. This could be accomplished by inserting inside each convoluted tube a fine pitch tension spring of marginally larger diameter than the drive shaft and slightly smaller outside diameter than the inside diameter of the convoluted tube. Another solution is to move both ends of the roller elements apart simultaneously as already mentioned, since this would halve the distance through which the tube convolutions would otherwise be dragged during expansion of the tubes.

It should be noted that the return run of the roller table (not shown) is spring-loaded to maintain tension in the conveyor chains and that the cam rail returns the convoluted tubes to the closed position in which they are held until the cam rail diverges on the upper run of the roller table.

Some of the more important advantages and constructional features of the invention may be summarised as follows: Firstly, a means is provided whereby potatoes taken from a bulk supply or received from a conveyor belt in random presentation, may be marshalled in orderly rows, singulated and deposited on a transfer belt, or other conveyor, in such a way as to maintain the singulated state.

Secondly, the device may include rollers with convoluted flexible tubular sleeves, capable of expanding from a closed position where the convolutions are touching or in close proximity, to an open position where the convolutions have moved apart e.g. by a factor of 3 (though not essentially by this amount).

Thirdly, the device may comprise slide rails driven by a cam producing iinear movement to enhance the ejection of rows of singulated produce, or alternatively, a flexible arrester belt or tilt tray could be fitted to retain singulation during transfer from the roller table.

Fourthly, the transfer conveyor may com prise a belt with flights designed to achieve acceleration with minimal loss of position such that all potatoes move clear of the ejection point prior to the arrival of the next row of singulated potatoes.

Fifthly, as an alternative, to receive the singulated produce, a forward plain or flighted conveyor may be provided moving in the same direction as the singulating conveyor to carry the produce to appropriately disposed sizing/weighing means.

Claims (18)

1. A singulator as hereinbefore defined comprising a conveyor adapted to convey the items to be singulated in a first direction and expansion means for expanding the conveyor in a substantially horizontal second direction having at least its principal component at right angles to the first direction.

2. A singulator as claimed in Claim 1 in which the conveyor comprises a plurality of elongate sections with each section coupled to the preceding and following sections of the conveyor and extending across a width dimension of the conveyor.

3. A singulator as claimed in Claim 1 or Claim 2 in which the expansion means is adapted to operate to expand each conveyor section progressively across the width of the conveyor as it moves from a ioad-accepting first location to a load-discharging second location.

4. A singulator as claimed in Claim 3 in which each section comprises an axially-expandable roller element.

5. A singulator as claimed in Claim 4 in which each said roller element is biased towards either a maximum-length or minimumlength configuration as the case may be.

6. A singulator as claimed in Claim 4 in which the length of each section is controlled by a suitably disposed cam surface engaged by end portions of the roller elements or by some part moving with these end portions.

7. A singulator as claimed in Claim 6 in which there are two said cam surfaces which are operative together to move the two ends of each section in opposite directions to one another.

8. A singulator as claimed in any preceding claim in which retraction means are provided at a load-discharging location of the conveyor periodically to retract the end section or sections at that location in order more positively to discharge the load therefrom.

9. A singulator as claimed in any of Claims 1 to 7 in which the conveyor is arranged to be driven by a sprocket having sufficiently few teeth to impart a cyclical movement to the conveyor drive.

10. A singulator as claimed in Claim 9 in which a flexible arrester flap is provided to maintain the singulation of objects in transit from the conveyor to a different location.

11. A singulator as claimed in any of Claims 1 to 7 in which a tilt tray is provided on which items received from the conveyor will dwell momentarily before discharge to a different location.

12. A singulator as claimed in Claim 11 in which the tilt tray is supported by crossed pivotal links.

13. A singulator as claimed in any preceding claim adapted to take potatoes or other tubers from a bulk hopper, marshal them into single lines in which they may be contiguous and even overlapping and then effect spatial separation of all tubers from each other so that they can be presented singly to a sizing head.

14. A singulator as claimed in Claim 13 in which the singulator suppiies several sizing heads.

15. A singulator substantially as hereinbefore described with reference to and/or as illustrated in Figures 1 to 3 of the accompanying drawings.

16. A singulator substantially as hereinbefore described with reference to and/or as illustrated in Figures 1, 2 and 4 of the accompanying drawings.

17. A singulator substantially as hereinbefore described with reference to and/or as illustrated in Figures 1, 2 and 5 of the accompanying drawings.

18. 8eed planting equipment including a singulator as claimed in any preceding claim.