GB2228910A - Increasing the spacing between receptacles of an endless conveyor - Google Patents

Abstract

An endless conveyor assembly is operative to convey a group of items from a first location 27, at which the assembly presents stationary receptacles with a first receptacle-to-receptacle spacing, to a second location 44 at which the assembly presents moving receptacles having an increased second receptacle-to-receptacle spacing. The increased spacing may be achieved by means of chain links with slotted connections to allow relative movement in the longitudinal direction of the chain. The receptacles on the chain are preferably pivoted to discharge the article into a chute. At the loading station (27) the articles, which are preferably plants to be potted at station 44, are ejected from trays which are held vertically, the plants being horizontal. The trays are indexed downwardly by gravity being supported at each step by two reciprocable plungers. <IMAGE>

Description

CONVEYOR ASSEMBLY The present invention relates to an endless conveyor assembly and to an automatic module planter or transplanter incorporating such an assembly.

In known designs of planter, a frame linked to the towing tractor carries a shaft fitted with two or four ground-engaging wheels. The planter units are pivotably attached to the frame, usually about the axis of this shaft, which, by means of chains or gears, drives the planter mechanisms of these units.

Alternatively each planter unit may have its own ground-engaging drive wheels.

It is a disadvantage of these known planters that one worker is required to feed the plants to each planter unit, that is a worker is required for each row to be planted.

Plants to be transplanted into a field may have been grown in beds or trays, in peat blocks, or in compost-filled cells formed in plastics trays. This last type of transplant is generally known as a module. Not all cells of such a tray will produce a healthy plant and it is one of the functions of the worker supplying plants to the planter to select good plants.

It is an object of the present invention to provide a means for reducing the number of workers required to operate a group of planter units, that is to plant a number of rows of plants at a time.

Accordingly, the present invention provides a conveyor assembly comprising an endless conveyor for conveying a group of items from a first location at which the assembly presents stationary receptacles with a first receptacle-to-receptacle spacing to a second location at which the assembly presents moving receptacles having an increased second receptacle-toreceptacle spacing.

Conveniently, the conveyor comprises a roller chain in which the rollers are mounted on link-connecting members, and the links are slotted (i.e. provided with long apertures or "slots") so as, in appropriate situations, to allow relative motion to occur between the links to provide the different receptacle-toreceptacle spacings at the first and second locations.

Conveniently, the assembly includes drive means operative to move the receptacles continuously past the second location and relative motion between links of the conveyor is used to provide groups of stationary receptacles at the first location.

Conveniently, in this latter case, the drive means comprises an accelerator drive which periodically operates to hurry the receptacles into their desired stationary positions at the first location.

Conveniently, the accelerator drive is operative to move the receptacles at about twice their previous speed.

Conveniently, the accelerator drive comprises a toothed wheel or drum meshing with the conveyor or an endless chain or toothed belt with relatively widely spaced projections adapted to mesh with the conveyor.

Conveniently, a removable stop is provided at the downstream end of the first location.

Conveniently, the assembly includes loading means for loading the receptacles when stationary at tihe first location.

The invention also includes an automatic planter or transplanter utilising the conveyor assembly of the present invention and in particular, but not exclusively, such a planter or transplanter including loading means which are operative to load receptacles at the first location with a row of plants or seeds from a module carrier and discharge means for unloading the receptacles at the second location e.g. into the one or more chutes of an appropriate number of planter units.

In a preferred form of module planter or transplanter according to the present invention, replacement means are provided for automatically replacing the contents or intended contents of any one or more receptacles of the conveyor assembly.

In one known type of planter unit intended for manual feeding, the plant is ejected rearwardly by a so-called "kicker" mechanism so that its true velocity is low as the soil is moved around its roots.

If a conveyor assembly according to the present invention is to serve a number of planter units of the type, the kicker mechanisms of these units will have to operate at synchronous speeds, but not necessarily at the same time.

It should be understood, however, that the conveyor assembly of the present invention would be equally suitable for supplying plants to planter units with other forms of mechanism used to place the plants in the soil.

Planters or transplanters according to some embodiments of the present invention include a frame adapted to be linked to the towing tractor, the frame carries a drive shaft and the planter units are pivotably attached to the frame, conveniently about the axis of the drive shaft, which, e.g. by means of chains and, or, a train of gears, drives the planter units.

Conveniently, the planter or transplanter includes a land-wheel driven axle which powers the drive shaft e.g. through gearing or a chain drive.

Preferably, only the gear ratio of the gearing or chain drive need be changed to alter the plant spacing.

The drive shaft conveniently drives each planter unit through a fixed ratio chain and can also power the tray handling mechanism and the module ejector and a module conveyor unit to be described below.

Row spacing can be changed by altering the spacing apart of the planter units, preferably without any other adjustments being necessary and conveniently, each planter unit is adapted to rise and fall to allow for uneven ground.

In embodiments of the present invention designed to encourage relatively high planting speeds, it is preferred that a row of twenty four or so plant-bearing modules should be discharged from a tray at once, that the modules should be discharged directly on to carriers on a chain conveyor, that the conveyor receptacles into which the plants are ejected from the tray should be stationary during that operation, and that in order to deliver plants at the required time intervals e.g. to each of four planter units, the conveyor passing over the chutes or small hoppers of the planter units should move continuously. This latter objective can be achieved, for example, by mounting the module carriers on elements of a chain which can be pushed together to provide a pitch spacing to match that of the tray cells (e.g. 28mm) or extended (e.g. 48mm).

It will be appreciated from the above, that embodiments of the present invention rely on the principle of a dual pitch chain used to build in an appropriate dwell period. Thus slotted holes included in the chain links permit change in pitch while providing sufficient constraint for the chain, with its wheels or rollers if present, to support module carriers on each chain pitch. The dwell facility thus allows the efficient transfer of modules from the tray while at the same time permitting a constant chain speed for delivery to the planter units.

Conveniently, the module carriers are "V" shaped although as an alternative, other forms of plant carrier may be used, for example ones incorporating plant grippers.

Embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings in which: Figure la shows a side view of part of the conveyor according to a first embodiment of the invention and Figure lb shows a plan view of one of the links of the conveyor without the module-carrying element in position; Figures 2a,2b; 2c and 2d show, in diagrammatic form, side views of the same conveyor at different stages of its operation; Figure 3a shows a side view of a conveyor according to a second embodiment of the invention; Figure 3b and 3c show end views of the conveyor of the second embodiment at two different stages of its operation; Figure 3d shows a plan view of one of the conveyor links in the conveyor of the second embodiment; Figure 3e is a cross-section taken along the line XX in Figure 3b; Figure 4 diagrammatically illustrates in plan view a conveyor according to a third embodiment of the invention; Figure 5 shows a side view of a loading mechanism for use in the three embodiments illustrated in the earlier Figures; Figures 6a,6b and 6c respectively show side, plan and side views of a discharge mechanism for use in the same three embodiments; and Figures 7a,7b and 7c are diagrammatic side views of a feed system for feeding down the plant-bearing trays one row at a time illustrating three different stages of its operation.

Where convenient, the same reference numerals have been used to indicate structurally and/or functionally similar or identical items or parts of items in the different embodiments illustrated.

Referring first to Figures la and lb of the drawings, a conveyor 10 according to the present invention comprises a roller chain in which the rollers 13 are mounted on pins 15 interconnecting adjacent pairs of links 17.

The trailing ends of the links are slotted at 19 (as shown in Figure lb) so as to allow varying amounts of overlap between the links. Thus, in the situation illustrated in Figure la, the right-hand pair of links 17 (shown supporting a carrier 21) is shown fully extended whilst with the following links, the overlap is shown at a maximum with the link-connecting pins 15 at the foremost ends of the slots 19 rather than at their rearmost ends.

Although only one receptacle (carrier 21) is shown in Figure la, similar receptacles will be supported by the other links in the conveyor, as will be apparent from the later Figures. Typically, these receptacles will take the form of injection-moulded plastics trays.

Turning now to Figures 2a,2b,2c and 2d, these show in schematic outline how the conveyor 10 of Figures la and lb may be used in conjunction with a conveyor-accelerating drive chain or toothed belt 23 and a removable stop 25 to provide bunching of the links and associated carriers 21 at a first location 27.

In these Figures, the small circles represent the module carriers and for simplicity eight have been shown for each tray row. In addition, reference numerals 29,30 indicate the respective sprockets powering the conveyor 10 and accelerator drive 23 and it should be understood that whereas the conveyor continuously operates at substantially constant speed, the accelerator operates only intermittently.

Thus, in more detail, in the situation shown in Figure 2a of the drawings, the stop 25 is operating to stop the foremost carrier of a group at the first location 27 and a projection 34 of the stationary accelerator belt 23 has reached the end of its first journey to locate the rearmost carrier of the group at location 27. Thus Figure 2a depicts the beginning of a dwell period in which the group of carriers between projection 34 and stop 25 are held stationary and the modules are ejected from the module tray to commence loading.

To ensure that the carriers are accurately located relative to the tray, the leading carrier of each such group of carriers is provided with a downwardly-extending lug 36 which can be stopped by the retractable pin 25 operated by the tray indexing mechanism. Similarly, the last carrier of each group is provided with an upwardly-extending second lug 37 for engagement by projection 34.

Clearly, the conveyor 10 with this arrangement must consist of a whole multiple of the number of cells in each group (eight in this Figure) in view of the presence of the lugs 36,37.

It will be appreciated that the links in the top run of the conveyor 10 will at all times be fully extended resulting in a continual rotation of the idling sprocket 38 corresponding exactly to that of drive sprocket 29. However, although the rotating idler sprocket 38 will pull on the bottom run of the conveyor 10, this pull will initially be wholly accommodated not by a corresponding bodily movement of the lower run of the conveyor (which is prevented by projection 34 and stop 25), but instead by a spacing apart of the previously bunched carriers 21 to the right of location 27 so that the roller-supporting pins 15 can be accommodated in the notches 40 of the idler sprocket 38.

Just before the links to the right of location 27 have been fully extended (Figure 2b), the stop 25 is released and the drive to sprocket 30 is automatically reactivated to restart the accelerator drive 23. This will result in the projection 34 moving out of engagement with the lug 37 only to be replaced (upstream) by the second belt projection 42 which moves round the idler 43 to re-engage the next upwardly-extending lug 37 on the conveyor.

The subsequent motion of the projection 42 to the position previously occupied by projection 34 drives the previously bunched carriers to the right of location 27 and replaces them (at location 27) with the next batch of bunched carriers 21. At this point the sprocket 30 is stopped and the stop 25 is re-activated with the assembly as shown in Figure 2c once again ready for loading at location 27.

Following completion of this loading operation (Figure 2d), the stop 25 is again withdrawn and the accelerator drive sprocket 30 is re-activated to return the assembly to the position of Figure 2a whereupon the operation sequence repeats as above described.

For convenience, only the first of the two locations discussed in the initial statements of invention has so far been identified in the drawings. However, Figure 2d also identifies the second location 44 which contains four chutes of planter units 46,47,48,49 designed to accept material discharged from the continuously moving top run of the conveyor as it passes alongside the chutes.

Reference numeral 51, in Figure 2d, indicates a make-up unit which is operative automatically to replace in the carriers 21 any dud plants which have been detected and ejected at the quality investigation site 52. As an alternative to a fully automatic system, a combined manual and mechanical process may be used instead if desired.

To summarise, the plant carriers are spaced out before the location 27 in the view of Figure 2a but at the end of the dwell, (Figure 2b), they have been partly bunched up by the rotation of sprocket 29, and the spacing of the carriers beyond the tray has been extended. At the end of the dwell, the accelerator chain 23 is driven faster, e.g. at twice the conveyor speed, to move the carriers into their bunched up position and at the same time to move the carriers that have just been loaded with plants, on their way.

Details of the discharge mechanism for loading modules into the planter units 46-49 may be had from Figures 3a,3b,3c,3d and 3e from which it will be seen that each carrier 21 comprises a V-profiled chute 54 hinged at 56 and normally held in the Figure 3b orientation by a magnet 58. Once released by a quick upward push (as will be described below with reference to Figures 6a,6b and 6c), a torsion spring 60 acting between the frame 20 and the chute 54 will tilt the chute to the new orientation shown in Figure 3c. This tilting action causes the self-closing flap 62 to pivot open so that the module in carrier 21 can slide out roots first into the appropriate planter unit chute at the discharge location 44. A one-piece spring catch could be used in place of the magnet 58 but the latter has some desirable characteristics.

Instead of using a conveyor with the inner and outer links of Figures la and lb, Figures 3a to 3c show an alternative construction in which all the links are identically fabricated from pairs of fairly simple metal stampings which are spot welded together, the difference in height of the carriers 21 being negligible. The guide channel 63 in which the chain rollers 13 run is formed in one piece as shown, although as an alternative (not shown), the roller tracks could be machined sections of hard plastics material. When the links are bunched together as at 64, the carriers 21 will be at the correct pitch spacing to suit the module tray. When extended as at 65, the pitch is increased to 48m for the planting chutes.

The chain pins 15 pass through the link plates 17 and carry the two rollers 13 which are secured by push-on fasteners 67.

Two or three spacing tubes 69 (the central one being optional) are fitted on the pin 15. The bottom of the chain guide channel 63 could, if desired, incorporate apertures so that trash did not need to be pushed to the ends of the channels before falling out.

It will be understood that other designs of conveyor might be used instead. For example, the conveyor might consist of moulded plastics sliders linked together with a flexible element, or it might be made of metal diecastings.

Figure 4 shows an alternative embodiment in which the accelerator drive chain 23 of the earlier embodiment is replaced by an intermittently driven accelerator drive sprocket 71 driven in a 1:1 drive:dwell ratio. When driven by a single revolution clutch (not shown), the speed of sprocket 71 would be twice the speed of the continuously driven sprocket 29 for conveyor 10.

As before a removable stop 25 is used to define a stationary loading site between sprocket 71 and the stop.

Reference numerals 73,74 indicate a full tray and a stock of full trays respectively while reference numeral 76 includes a stock of additional full trays. The position where dud modules could be replaced by hand is thus conveniently close to the tray magazines.

Typically, the roller spacing in that portion of the conveyor between the two drive sprockets 29 and 71 will be partly at 28mm and partly at 48mm while the corresponding spacing in the discharging section immediately upstream of the drive 29 will be 48mm. The four planter units 46-49 are spaced apart on 61mm centres but this may be adjusted to provide different row spacings.

In the illustrated arrangement of Figure 4, there would be approximately 175 pitches (i.e. receptacles) in the conveyor.

Figure 5 is a diagrammatic view in the direction of arrow X in Figure 4 illustrating a system for loading the carriers 21 with plants from a tray 73 of such plants.

The tray is fed downwardly in the direction indicated, one row at a time, and a row of ejector rods 78 displaces a row of plants into a group of receptacles 21. When the tray has been emptied in this way, a stacking plunger 80 displaces the tray into a stack 82 of empty trays where it is held in place against latches 84 by the action of a compression spring 86.

A new tray is then fed into the system and the process is repeated.

To accommodate the stack 82 within the loop of the conveyor, it may be necessary to have the hoppers or chutes of the planter units 46-49 at a greater height above ground level than is used with conventional hoppers and for this reason, it may be desirable to have a flap in the chutes of planter units 46-49 at about the height of the conventional rotating hoppers. This flap would be operated by the kicker operating mechanism at the appropriate time.

A feed system 88 for indexing the module trays 73 downwards a row at a time is shown in Figures 7a,7b and 7c. This is based on plungers locating with the underside of the cells. The tray indexing plungers can conveniently be operated by cams on the shaft which carries those for the module ejection plungers.

Figures 7a,7b and 7c, show the feed system 88 at three different stages of its operation, the plungers, on extension, intruding between the individual plant-bearing cells of the trays 73 as illustrated.

Basically, feed system 88 comprises a bottom plunger 90 constrained to move horizontally and a top plunger 91 which can also incline downwardly against the action of a restraining tension spring 93. Reference numerals 94,95 indicate the two stops for plunger 91 at the upper and lower extremities of its movement and reference numerals 96,97 indicate guide surfaces for the trays and the plungers respectively.

Thus starting from the situation shown in Figure 7a, the bottom plunger 90 is withdrawn and the weight of the tray 73 forces the top plunger down (against the action of spring 93) until it is supported on the bottom stop 95 as shown in Figure 7b. During this operation, the tray will have been allowed to move downwardly (under gravity) by an amount exactly equal to one of the plant bearing cells.

With the tray in this new position, the plungers 90,91 are simultaneously extended (plunger 90) and withdrawn (plunger 91) until the tray 73 is wholly supported on plunger 90 and plunger 91 has been pulled up by spring 93 into engagement with the upper stop 94 (Figure 7c).

Plunger 91 is now extended so as again to engage a cell of the tray 73 and the situation illustrated in Figure 7a will have been resumed except that the plungers will now span the middle cell shown instead of the bottom one.

Turning now to Figures 6a,6b and 6c, these show in more detail, the discharge mechanism (96) referred to above.

Basically, this mechanism comprises an indexing eighttooth sprocket 98 driven by the pins 15 of the conveyor 10.

Secured to and extending radially of the sprocket 98 is a cross-arm 100 having rollers 102,103 at either end. On rotation of the arm 100 to the position shown in Figure 6b, the right-hand roller 103 will engage the rocking lever 105 to urge upwardly the push-rod referred to in the discussion of Figures 3b and 3c thereby to tip the receptacle 21 and discharge the plant down the appropriate one of chutes of transplanter units 46-49. This rod is identified in Figures 6a,6b and 6c by the reference numeral 107.

Identical discharge systems would be provided at each of the four sequential discharge sites of the conveyor to discharge a respective module into each of the four chutes.

Although the illustrated assembly is designed as a four row unit, it will readily be appreciated that the assembly could easily be modified for three, two or even one row planting.

Similarly, it could be modified for use with five or more rows although in these cases more than operator on the machine would probably be required. Modification can be facilitated by having the sprockets 98 easily interchangeable and selected according to whether three or four units, say, were tn operation. A planter which was not in use would have its sprocket removed. A drive pin arrangement would be used to ensure that sprockets could only be fitted the correct way round in the correct angular relationship.

To satisfy growers who miss out rows to provide wheelways for subsequent operations, it is possible to operate the illustrated four row machine with any one of the rows out of action. This feature might also be useful at edges of fields. Similarly, the machine is readily adaptable to suit different row widths and plant spacing in the row.

If, for example, it is decided to discharge into only three transplanter unit chutes, then the sprocket 98 is replaced by a six-toothed version while if, for any reason, it were desirable to use only two or one of the four chutes, the indexing sprocket would have to have eight teeth and either four rollers or eight rollers respectively.

Returning now to the make-up facility referred to briefly above with reference to Figure 2d, it is probable that with the carrier mounting system shown in Figure 3b, the operator could discharge a dud module from its carrier by tilting the carrier so that it is released by its magnet (or catch) and then with a second movement could place a fresh module in the carrier while returning it to its transport inclination. A more mechanised method would be for the operator merely to release the carrier so that it tilts to discharge the module. The tilted carrier could then trigger a mechanical make-up facility further along the line. This make-up facility would conveniently consist of a rotary pre-filled magazine, for example. If required an optical detector could be used to replace the operator detecting the dud modules. The detector could be arranged to tip the carriers containing the dud modules and the same make-up facility described above could be used to replace them.

It is essential that all the planter unit mechanism operate at the same speed and they therefore require plants at the same time intervals. This can conveniently and cheaply be arranged by driving them all from the same land-wheels. An alternative would be to take a drive from a ground speed tractor power take-off for tractors which have this facility. Since the conveyor and tray feed drives must be synchronised with the planter unit mechanism these could conveniently be driven from the same power source.

The power required for these latter drives should be small.

Since land-wheels driving a group of planter units can be positioned to be between the plant rows they can be fitted with substantial lugs if required.

With the twenty four cell rows used in the illustrated embodiment and an eight tooth conveyor drive sprocket, the ratio between that sprocket and the cam shaft operating the ejection plungers would be 3:1 assuming single lobe cams, regardless of how many planter units were in use. However, the ratio between the conveyor sprocket and the planter unit kicker mechanism would be 1:2 with four planters in use and 3:8 with three in use.

If a mechanised dud module replacement option is included, this could conveniently be electrically powered, for example with a solenoid. Electrical power from the tractor's battery would be very much cheaper to provide than pneumatic power, although the latter might be used to power the kicker mechanism if desired.

It is envisaged that planting speeds of around 2 plants per row per second should be possible with machines designed in accordance with the present invention.

Claims (19)

1. A conveyor assembly comprising an endless conveyor for conveying a group of items from a first location at which the assembly presents stationary receptacles with a first receptacle-to-receptacle spacing to a second location at which the assembly presents moving receptacles having an increased second receptacle-to-receptacle spacing.

2. An assembly as claimed in Claim 1 in which the conveyor comprises a roller chain in which the rollers are mounted on link-connecting members, and the links are slotted so as, in appropriate situations, to allow relative motion to occur between the links to provide the different receptacle-to-receptacle spacings at the first and second locations.

3. An assembly as claimed in Claim 1 or Claim 2 including drive means operative to move the receptacles continuously past the second location and in which relative motion between links of the conveyor is used to provide groups of stationary receptacles at the first location.

4. An assembly as claimed in Claim 3 in which the drive means comprises an accelerator drive which periodically operates to hurry the receptacles into their desired stationary positions at the first location.

5. An assembly as claimed in Claim 4 in which the accelerator drive is operative to move the receptacles at about twice their previous speed.

6. An assembly as claimed in Claim 4 or Claim 5 in which the accelerator drive comprises a toothed wheel or drum meshing with the conveyor or an endless chain or toothed belt with relatively widely spaced projections adapted to mesh with the conveyor.

7. An assembly as claimed in any preceding claim in which a removable stop is provided at the downstream end of the first location.

8. An assembly as claimed in any preceding claim including loading means for loading the receptacles when stationary at the first location.

9. A conveyor assembly as claimed in Claim 1 and substantially as hereinbefore described with reference to and/or as illustrated in the accompanying drawings.

10. An automatic planter or transplanter including a conveyor assembly as claimed in any preceding claim.

11. A planter or transplanter as claimed in Claim 10 including loading means which are operative to load receptacles at the first location with a row of plants or seeds from a module carrier and discharge means for unloading the receptacles at the second location.

12. A planter or transplanter as claimed in Claim 10 or Claim 11 including replacement means adapted automatically to replace the contents or intended contents of any one or more receptacles of the conveyor assembly.

13. A planter or transplanter as claimed in any of Claims 10 to 12 in which the conveyor assembly serves a number of planter units, the kicker mechanisms of these units being adapted to operate at synchronous speeds, but not necessarily at the same time.

14. A planter or transplanter as claimed in any of Claims 10 to 13 including a frame adapted to be linked to a towing tractor and in which the frame carries a drive shaft and the planter units which are driven by the drive shaft are pivotably attached to the frame.

15. A planter or transplanter as claimed in Claim 14 in which the planter units are adapted to pivot about the axis of the drive shaft.

16. A planter or transplanter as claimed in Claim 14 or Claim 15 including a land-wheel driven axle which powers the drive shaft.

17. A planter or transplanter as claimed in any of Claims 14 to 16 in which only the gear ratio of the gearing or chain drive need be changed to alter the plant spacing.

18. A planter or transplanter as claimed in any of Claims 14 to 17 in which the drive shaft is adapted to drive each planter unit through a fixed ratio chain and can also power a tray handling mechanism and a module ejector and a module conveyor unit.

19. A planter or transplanter as claimed in Claim 10 and substantially as hereinbefore described with reference to and/or as illustrated in the accompanying drawings.