The invention relates to a method and apparatus for transporting
seedlings in a planting machine, in particular for regular delivery of seedlings
in a planting vehicle to the soil.
For such methods the seedlings to be planted are generally
stocked in trays. The planting machine comprises generally means for transfering
the seedlings, eg. row per row, from the trays and for conveying the seedlings,
optionally through a selector device, to the planting station. In such selector
device the improper seedlings are removed. The selected seedlings are further suitably
transported to a downwardly directed conveyor that feeds them to said planting station
for the intended regular delivery to the soil. With a regular delivery is meant
the delivery to the soil of consecutive seedlings at a predetermined substantially
identical distance from one another at any driving speed of the planting vehicle
over the soil.
The method and apparatus needs also measures and means
for first transporting and positioning the seedling carrying trays in the planting
vehicle in view of a proper transfer of the seedlings to the selector device and
further to the planting station. In particular means and measures have to be provided
for exchanging trays, i.a. for evacuating empty trays from the apparatus.
The European patent application 390 289 relates to an apparatus
for relocating cutlings in plant boxes in which an endless transport ation element
with grippers is used. Seedling transportation apparatuses for a transplantation
machine are also known from EP 806131, EP 898866 and EP 900516. In the planting
vehicles according to EP 806131 and EP 900516 a horizontal path is provided for
transporting the seedling carrying trays under a seedling pick-up and transfer device
that removes the seedlings from the trays row per row. The emptied trays are advanced
mechanically further at the same level below a transversally oriented horizontal
conveyor belt on which the removed seedlings are deposited by the pick-up and transfer
According to EP 898866 this transverse conveyor belt is
equiped with a very specific selector device for removing improper seedlings. This
belt with the coupled selector device delivers the proper seedlings further via
a downwardly directed conveyor to the planting station.
The selector device delivers at its exit the proper seedlings to the inlet of the
downwardly directed conveyor. At that spot a sensor detects the packing condition
of the proper seedlings passing by and roughly steers the speed of the transverse
conveyor as a response to this packing condition. This arrangement however has the
drawback that no reliable operational link is provided between the actual planting
speed in the field and the feeding speed of proper seedlings at the outlet end of
the selector device. As a consequence a regular delivery of seedlings to the planting
station at a predetermined substantially constant planting distance is not assured.
The very specific selector device has also a quite complicated construction.
Further, these machines of the prior art, especially according
to EP 806131 and EP 900516 have the disadvantage that they enable only a relatively
complex pick-up process. Indeed, the correct positioning row per row of each new
tray carrying seedlings under the seedling transfer device requires a quite cumbersome
positioning cycle especially between removal of the last row of seedlings from the
previous tray and the first row from the subsequent new tray. The positioning speed
Description of the invention
It is now an object of the invention to provide a planting
method and machine of the type described above that enables a faster planting operation,
i.e. with a faster vehicle speed (m/min).
It is also an object of the invention to provide a planting
method and machine that allows a more accurate planting operation whereby the consecutive
seedlings are planted in the soil at a predetermined and also identical or nearly
identical distance from one another, irrespective of the driving speed of the planting
vehicle or at least largely independent of said speed. The latter objective is particularly
important in cases where a constant output per time unit is desired for mechanically
harvesting later on the grown plants, eventually with human intervention as required
eg. for sprouts.
It is a further object of the invention to allow such faster
and/or more accurate planting operation with a simpler planting machine than those
known from the prior art. In particular the means for the exchange of trays and
the new selector device require a simpler construction to allow such faster operation.
To meet the objectives of the invention, a seedling transportation
apparatus with the features of claim 1 is proposed.
According to the invention the means for guiding and removing
an empty tray include guiding rails for temporarily supporting the opposite side
edges of said empty tray. Said rails are pivotably mounted in the neighbourhood
of their outer edge to enable said tray to be removed on a support and to actuate,
preferably at the same time, abutment means for the front side of the adjacent new
tray. The empty tray is preferably removed at a level that is lower than the path
of advancement of a new tray, eg. at a level under said horizontal conveyor.
Said guiding rails are preferably pivotably mounted along
their outer edge to enable said empty tray to drop down on a support for further
removal at a lower level, optionally at a level under said first conveyor. If desired,
said removal can even be carried out at a lowermost level underneath said first
conveyor itself in a direction that is substantially parallel to the advancement
direction of a new tray.
However the level of the support can also be somewhat higher
than said lowermost level. After the guiding rails have then released and deposited
the empty tray on the support, eg. at such higher level, it can be removed in a
direction perpendicular to the direction of advancement of a new tray. The empty
tray is thus removed sideways, eg. running along a path adjacent to that of the
first conveyor and eg. in the same direction as the seedlings deposited on the first
The abutment means are preferably stops that are transversely
mounted at the inlet end of said guide rails. The path for advancing a new tray
is preferably along a feeding conveyor that is slightly inclined downwardly from
a higher inlet end to a lower outlet end.
Said path is preferably at an average level equal to or
higher than the level of the first horizontal conveyor. The support for removal
of an empty tray under the first horizontal conveyor comprises preferably discharging
means with most preferably an inclination from a higher inlet end to a lower outlet
end. The apparatus can also be equiped with suitable recirculating means for bringing
back the empty tray close to the feeding area for a new tray.
According to an interesting aspect of the invention the
row of picking means in the seedling transfer device cooperates with a row of up
and down movable pushing pins in the apparatus, i.a. for suitably lifting the seedlings
row per row from the trays. At least one and preferably all of said pushing pins
act thereby as a positioning pin for each consecutive row of seedlings to be lifted
from the tray.
In fact, according to the invention there is a very advantageous
functional link between the operation of said abutment means for the positioning
of the front side of a new tray in view of the insertion of the row of picking means
in the first row of cells and the subsequent insertion of the row of pushing pins
in said first row. This fast, simple and correct positioning for the first row is
also a good start for the further positioning of said tray by said row of pushing
pins in each consecutive row in view of the suitable lifting of the seedlings from
any subsequent row.
The invention comprises also transfer means for depositing the seedlings, that are
removed row per row from the trays, in a series on a first horizontal conveyor.
This first conveyor may cooperate with a second conveyor so that the loaf portion
of the seedlings is gripped between said first and second conveyor. A selector device
is provided for removing improper seedlings from the apparatus during advancement
of said first conveyor towards a third downwardly directed conveyor that receives
and advances the remaining proper seedlings towards the soil area for the planting
operation in the field. With improper seedlings is meant seedlings having only a
rootball portion and no, or a too short loaf portion.
According to another advantageous aspect of the invention
separate buffer means can be arranged between the outlet of said first and the inlet
of said third conveyor for carrying said proper seedlings to said inlet. Means are
also provided for driving said buffer means at a speed that is linked to the speed
of the third conveyor. Said buffer means comprise preferably a further fourth conveyor.
The speed of the fourth conveyor is linked by its driving means in the appropriate
manner to the speed of the third conveyor in view of producing the predetermined
planting distance in the soil. This fourth conveyor most preferably cooperates with
a transportation belt and both together constitute a preferred embodiment of the
buffer means. The root ball portion of the proper seedlings are then gripped or
held and advanced between said fourth conveyor and the cooperating transportation
Actually, such separate buffer means assure a flexibly
adjustable and accurate transfer the seedlings through the third conveyor to plant
them in the soil at the predetermined substantially identical distance.
Another interesting feature of the invention relates to
the preferred selector device with a specific simple construction. This selector
device is preferably coupled to said first conveyor. This device comprises an inclined
selector belt, mounted adjacent to the exit end of, and driven by the exit roller
of the first conveyor. This inclined selector belt faces with its inlet roller the
outlet roller of the rootball-carrying portion of said first conveyor and has an
upwardly directed inclination from its inlet roller towards said exit roller.
These and many other features of the invention and its
operation will be explained hereinafter with their advantages and with reference
to the accompanying drawings. It is clear that the invention is not limited to the
exemplary embodiments decribed below.
Brief description of the drawings
- Figure 1 is a perspective view of some essential parts of the planting vehicle
according to the invention.
- Figure 2 is a side elevation view of figure 1.
- Figure 3 is another perspective view showing some details of the buffer means.
- Figure 4 is a front elevation view of the first to fourth conveyor and buffer
- Figure 5 is a perspective view of a stage in the tray positioning cycle according
to the invention.
- Figure 6 is a similar view of a newly positioned tray just before the picking
up cycle of the first row of seedlings from that tray.
- Figure 7 is a side elevation of the mechanism that steers the positioning cycle
of the tray row per row.
The general construction and operation of the whole process
and apparatus will first be described in a brief overview with reference to figures
1 to 3. Details of the important new and inventive parts such as the tray positioning
cycle (figures 5, 6 and 7) and the buffer means and process (illustrated in figures
3 and 4) will then follow. The seedling transportation apparatus 1 illustrated in
figure 1, 2 and 3 is of course to be mounted on or connected to the chassis of a
vehicle, e.g. a tractor (not shown). The apparatus 1 comprises a tray transporting
section 27 mounted in a frame 26. Advancing means, such as or comprising a feeding
conveyor 28 are provided at the feeding area 38 of said section 27 to bring the
new trays 29 into the apparatus. The path for advancing a new tray along the feeding
conveyor 28 is preferably slightly inclined downwardly from a higher inlet end to
a lower outlet end. Said path is preferably at an average level equal to or higher
than the level of the first transverse horizontal conveyor 4 at the other end of
the apparatus 1. Likewise, the support for removal of an empty tray 36 under the
first horizontal conveyor 4 in this embodiment comprises preferably discharging
conveying means 37 with an inclination from a higher inlet end to a lower outlet
end. The conveying means 37 shown in figures 1 and 2 comprise a set of parallel
rollers with their axes perpendicular to the advancement direction of the new trays
29. However a conveyor belt or any other suitable conveyor can be used i.s.o. this
set of rollers.
In an embodiment (not shown) where the empty tray is to
be removed sideways as explained above, the axis of rotation of discharging conveyor
rollers of a support means is then of course parallel to the direction of advancement
of the new tray (in stead of perpendicular as for the embodiment shown in figure
Downstream of the feeding conveyor 28 a row of up and down
movable pushing pins 30 is arranged i.a. for lifting the seedlings 2 per row 32
from their cells 31 in the new trays. Above said row of pushing pins 30 a seedling
transfer device 3 is pivotally mounted on arms 33 and 39. Said arms 33 and 39 are
themselves pivotally supported in the frame 26. Due to said simple pivotable arrangement,
and as shown in figure 2, the seedling transfer device 3 can move from a picking-up
position A of the seedlings 2 to a deposition position B of said picked
seedlings on a first transverse horizontal conveyor 4 mounted in the apparatus.
The fact that the tray 29 is about at the level of the conveyor 4 is of great advantage.
Indeed, it enables to design a relatively short and easy transfer path and thus
a simple and fast transfer process of the seedlings from an upright position in
the tray 29 to a horizontal lay down position on the conveyor 4.
The transfer device 3 carries a row of picking means 34
such as needles mounted here for up and down movement in said device between a retracted
position (up) and an extended position (down). Figure 1 and 3 show the seedling
transfer device 3 in its picking position whereby the needle points face the cells
31 and the upper ends of the pushing pins 30.
Further downstream of said pushing pins, guiding rails
35 are mounted in the opposite side edges in the frame 26 for temporarily supporting
the opposite side edges of an empty tray 36 and for guiding and removing said empty
tray. Said L-shaped guiding rails 35 are pivotally mounted at their ends to enable
to drop said tray 36 on a support 37 for further removal under the transverse conveyor
4. This removal or discharge operation for an empty tray will be described in more
detail further on with reference to figures 5 and 6.
The transverse horizontal conveyor 4 transports the deposited
seedlings 2 towards the inlet end 17 of the third downwardly directed conveyor 6.
Details of the construction and operation of this transportation with the use of
a preferred selector device 14 and separate buffer means 8 will be described further
on with reference to figure 4.
At the lower exit end of the third conveyor 6 near to the soil area 7, the selected
plants are gripped with their loaf portion 18 in the planting wheel 40. This wheel
brings the seedlings 2 from their horizontal position in the conveyor 6 to their
vertical planting position in the soil area 7. This soil area is in the shape of
a furrow formed by the plough 41. The wheels 42 fill up the furrow around the planted
seedlings to complete the planting operation concurrent with the advancement of
the tractor with the apparatus 1 in the field.
Details of the positioning means and process for the consecutive
trays will first be explained with reference to figures 5, 6 and 7. When the seedlings
are removed row per row from a tray and transferred to the conveyor 4, except after
picking up the last row, this almost empty tray is supported on the rails 35. For
removal of this last row of seedlings the row of pushing pins 30 is first brought
into a position where it faces the bottom of the cells of this last row. How this
occurs will be described below when explaining the positioning cycle of the tray
row per row.
Secondly, the row of needles 34, facing the topside of
the cells of this last row is moved down and inserted into the cells to pick up
the seedlings therefrom. After that, the row of pushing pins 30 is lifted by a piston
53 to push the rootballs 22 of the seedlings out of their cells. The piston 53 is
fixed in the frame of a horizontally movable carrier 55 for the pushing pins. The
needles 34 lift at the same time with the result that the seedlings stay picked
up on their needles. During this removal process of the seedlings the tray is of
course fixed in its position by the transverse blocking stops 54 as will be explained
hereinafter. The seedlings 2 are thereby ready for transfer to the conveyor 4 by
means of simply pivoting the transfer means 3 with its arms 33, 39 from position
A to B (see figure 2).
At the same time the feeding conveyor 28 and the pushing
pins 30, that are located in the last row 52, advance the tray by a step forward
that is equal to the distance "d" between two consecutive rows. This movement is
part of the positioning cycle of the tray and is carried out and monitored by the
movable carrier 55 of the pushing pins. This carrier is supported by pivoting arms
56 in the frame 26 of the apparatus. The conveyor 28 is preferably slightly inclined
from a higher inlet end to a lower outlet end.
The whole positioning cycle is controlled by a software
programme that links and steers the movement of the carrier 55 and pushing pins
30 in consecutive positioning steps. The advancement distance "d" of a step forward
is preset by the distance stops 57 in the frame 26. This preset distance d is of
course adjustable according to the type of tray in use. The horizontal movement
back and forth of the carrier 55 for the step "d" is performed eg. by a piston 58
fixed in the frame 26. The most forward position of the carrier and pushing pins
is shown in dotted lines in figure 7.
Once the tray with its now emptied last row 52 is pushed
forward by a step "d" the pushing pins are lowered from this row to the level below
the bottom of the tray and moved horizontally backwards by the carrier 55 to their
position right under the pick-up needles. At this time a detector gives a signal
that there is no more tray in the pick-up area and thereby actuates the guiding
rails 35 to pivot down along their outer edge 61. As a result thereof, the empty
tray 36 drops down on the support 37 that is preferably inclined in downward direction.
This stage in the removal process of an empty tray is illustrated as an example
in the embodiment of figure 5.
Concurrent with the pivoting of the rails 35 abutment means
59 for the front side of the new tray 29 are actuated. Figure 6 shows this further
stage where the previous empty tray is removed. The new tray 29 is meanwhile advanced
with its front side against these abutment means 59 by the feeding conveyor 28.
Now that the new tray 29 is in its position to pick up
the first row of seedlings from it, transverse blocking stops 54 in the side walls
of the frame 26 are actuated from a retracted position to an extended position where
they clamp said tray transversally by its sidewalls in a fixed position. The needles
34 are again lowered to pick up the first row from tray 29 and the pushing pins
underneath this first row of cells are again lifted to remove this row together
with the needles 34.
The tray positioning and seedling removing cycle for the
second and any further row repeats itself in the same manner. The blocking stops
54 are first again retracted to set the tray free for moving a step d forward. The
pushing pins 30 move the tray forward over the step d. The blocking stops 54 are
again extended to clamp the tray and thereby fix its position for removal of a new
row and the pushing pins 30 are lowered. Subsequently, by retraction of the piston
58 the carrier 55 moves the pushing pins back where they are ready to start a new
pick-up cycle for the next row. This movement cycle for the pins 30 is indicated
by the four arrows 60 in figure 7.
With reference now to figure 4, the first horizontal conveyor
4 cooperates with a second conveyor 11 so that the loaf portion 18 of the seedlings
is gripped between said first and said optional second conveyor. The specific selector
device 14,15 is coupled to said first conveyor for removing improper seedlings 5
therefrom and from said coupled selector device during advancement thereof towards
the third downwardly directed conveyor 6. This third conveyor 6 thus receives and
advances only the remaining proper seedlings to the soil area 7 for the planting
operation in the field. The separate buffer means are arranged between the outlet
16 of said first and the inlet 17 of said third conveyor for carrying said proper
seedlings to said inlet 17.
The means 25 for driving said buffer means 8, at a speed
that is linked to the speed of the third conveyor 6, comprise a number of chain
or gear transmissions coupled to the respective shafts 43, 44, 45, 46 of the fourth
conveyor 12, the cooperating transportation belt 24, the third conveyor 6 and the
exit roller 13. This is schematically shown in figure 4. The chain 25 runs eg. over
two gears with different diameter. These diameters will be chosen according to the
desired speed proportion between the fourth conveyor 12 and the third conveyor 6
in view of setting a predetermined distance between consecutive seedlings moving
down to the planting station between the two belts of said third conveyor 6. A parallel
gear (not shown) can be arranged on shaft 43 that grips into a gear on shaft 46
to rotate the exit roller 13 in opposite direction but at about the same speed.
In addition a suitable chain transmission 48 via another parallel gear on shaft
46 can drive the transportation belt 24 so that in fact the belts 12, 24 and the
roller 13 all rotate at about the same linear speed at their circumference. It will
be clear to a person skilled in mechanics that similar transmissions can be designed
to reach the same effect.
The exit roller 13 facing the inlet 17 of the third conveyor
6 has preferably a relatively soft and elastically compressible surface such as
a foam rubber layer to suitably accomodate i.a. irregularities in the surface of
the rootball portions 22.
Just upstream of the fourth conveyor 12 and close to the
exit roller 20 of the selector device, a roller 9 may be arranged that runs parallel
to both and with a circumferential speed preferably equal to that of the fourth
conveyor 12. This roller 9 has preferably a small diameter and forms a bridge that
facilitates the advancement of the rootballs of the proper seedlings delivered by
the selector belt 14 to the buffer means.
The inclined selector belt 14 is mounted adjacent to the
exit end of the first conveyor 4. This belt is driven by its outlet roller 20 that
is mounted on the same shaft as the exit roller 10 of the loaf carrying portion
of the first conveyor 4 and thus runs at the same speed as the first conveyor. The
inclined belt 14 faces with its inlet roller 19 the outlet roller 15 of the rootball-carrying
portion 23 of said first conveyor 4. The inclination is upwardly directed from its
inlet roller 19 towards its outlet roller 20. The degree of inclination can be set
by fixing the level of the inlet roller 19 in a slit 47 of the supporting member
for that roller.
The selection and subsequent buffer process operates as
follows. Seedlings 2 on the first conveyor 4 have their rootballs 22 resting on
the portion 23 of the first conveyor. Their loaf portion 18 rests on the longer
parallel portion 49 and is gripped between said portion 49 and the second conveyor
11. These good seedlings continue further their movement into the buffer means 8.
During this movement their rootball portion 22 falls at the end of the belt 23 onto
the lower inlet end 19 of the inclined belt 14 and climbs again up on this belt
to the inlet end of the buffer means 8 in the nip between the cooperating transportation
belt 24 and the roller 9. A number of consecutive good seedlings is more or less
closely packed one after the other in this broad and spacy buffer area 50. A contactless
(eg. infrared) detector 51 checks the packing condition in this area. If the packing
is not close enough, a signal is given by the detector to the driving motor (not
shown) of the first conveyor to accelerate its speed to restore a close packing.
The closely packed good seedlings 2 are automatically advanced and delivered at
the appropriate speed to the inlet 17 of the third conveyor 6 to meet the preset
planting distance in the soil.
Improper seedlings on the first conveyor do not have a
loaf portion that can be gripped between the first (4) and second conveyor 11. The
rootball 22 of said improper seedlings thus falls down from the conveyor portion
23 on the inclined selector belt 14 when it reaches its exit roller 15. Since there
is no gripped loaf portion to hold it and to drag it upwards on the selector belt
14, the rootball falls further down as an improper seedling 5.
Having described the invention with reference to an exemplary
embodiment, it is clear that different mechanical constructions can be used with
an equivalent function. It is possible eg. , as indicated in figures 3 and 5, to
arrange the rails 35 (accompanied by suitable abutment means) with their leading
end 62 pivotable downwards and again upwards around a horizontal axis 63 parallel
to the front side of the adjacent new tray 29.
The transplanting apparatus can of course be equiped with
its own traction motor to constitute an independent selfmoving machine. It can be
designed to feed one, two or more furrows at a time.