The invention relates to a device for planting bulbous and tuberous plants, in particular potatoes, comprising a storage hopper for bulbs or tubers to be planted, a conveyor, preferably an endless belt, comprising parallel rows of elements, for example so-called cups, for receiving bulbs or tubers from the storage hopper and releasing said bulbs or tubers again, and a guide for guiding the released bulbs or tubers to a common delivery opening, for example above a trench under the device.

Previously, planting machines were usually provided with a chain on which one row of cups was mounted.

To increase the capacity, the machines were subsequently fitted with a cup belt comprising two rows of cups. An example of such a planting machine is shown in German Gebrauchsmuster No. 94 01 110.9.

Another example of a similar planting machine is shown in document GB-A-681 315.

In existing machines, guides are usually disposed under the two rows of cups, which guides impart a movement towards the centre to the bulbs or tubers that are being released. As a result, said bulbs or tubers are placed in line with each other in the middle of a trench formed under the device by means of a planting coulter.

The object of the invention is to further increase the capacity of the planting machine as referred to in the first paragraph.

In order to accomplish that object, the conveyor comprises at least three rows of such elements, and the device is configured in such a manner that differences between the times of fall of bulbs or tubers from different rows caused by differences in the height of fall and/or the resistance of fall are compensated by differences in the moment and/or the height at which the bulbs or tubers are released above the guide.

In the cultivation of plants, e.g. potatoes, not only the planting depth but also the position of the seed potatoes in the ridge, seen in the direction of movement and in a direction transversely thereto, is important for the development of the plants. The above aspects make it possible to increase the capacity without interfering with said position of the potatoes, especially in the direction of movement, too much.

Preferably, the rows of elements are offset relative to each other.

Thus, the moment at which the bulbs or tubers are released from a first row can be delayed or advanced in relation to the moment at which the bulbs or tubers are released from a second row, and variations in the height of fall and/or the resistance of fall can be compensated in a simple manner.

Furthermore it is preferable to provide a substantially symmetrical and centred guide, and preferably the distance (indicated "C" in the appended Fig. 3) between the elements in one of the outer rows and the next elements in at least one of the inner rows, seen in a direction opposed to the direction of transport of the belt, is larger than the distance (B) between the elements in said inner row and the next elements in the other outer row (C>B). The average (B+C)/2) of the aforesaid distances is preferably substantially equal to the shortest distance (A) between the elements in one outer row and those in the other outer row.

In these configurations, the moment at which the bulbs or tubers are released from an inner row is delayed in relation to the moment at which the bulbs or tubers are released from one outer row and, quite the contrary, advanced in relation to the moment at which the bulbs or tubers are released from the other outer row.

In an alternative embodiment, the elements present in the channels and/or the channels that surround said elements, the so-called planting channels, are configured to be different from each other in at least two rows. For example, by configuring the elements in at least one of the outer rows and/or the diameter of at least one of the channels of the outer rows to be smaller or larger than those in the inner row or rows, the moment at which the bulbs or tubers fall from said outer channel is advanced in relation to the moment at which the bulbs or tubers fall from the inner channel. This aspect makes it possible to increase or decrease the height from which the bulbs or tubers fall from the channels by adapting the aforesaid dimension(s) to a sufficient extent.

To prevent the potatoes from bouncing, or at least reduce the extent to which this occurs, the guide preferably comprises a flexible material under at least one of the rows, such that when a bulb or tuber comes into contact with this material, the shock is absorbed and the bulb or tuber glides downwards.

Generally, the rows lying side by side preferably extend jointly in a direction transversely to, at least not in line with, the direction of movement of the device for planting bulbous and tuberous crops.

The invention will now be explained in more detail with reference to the figures, which schematically show preferred embodiments of the present invention.

Fig. 1 is a side elevation of a device according to the invention, comprising a planting element.

Fig. 2 is a cross-sectional top plan view of the planting element of Fig. 1.

Figs. 3 and 4 are a schematic front view and a schematic longitudinal sectional view of a planting element according to the invention.

Figs. 5 and 6 are schematic, cross-sectional top plan views of two further embodiments of the planting element according to the invention.

Identical parts and parts having the same or substantially the same function are indicated by identical numerals.

Fig. 1 shows an example of a planting machine 1 according to the invention, by means of which four rows of seed material, in this case potatoes P, for example, can be planted in one operation. The planting machine 1 comprises a frame 2, which can be coupled to a tractor (not shown) by means of a three-point linkage that is known per se, and which is furthermore supported by ground wheels 4. In this specific embodiment, a storage hopper 5 for potatoes to be planted and four (substantially vertical) planting elements 6 are mounted on and in the frame 2, which planting elements are all provided with a delivery opening (indicated at 20 in Fig. 3) at their bottom sides. A planting coulter 7, also referred to as furrow or trench opener, is mounted under the frame, in front of each of said openings.

Disposed behind each of the planting coulters 7, substantially in line therewith, are a pair of covering discs 8, which function to cover a trench formed by means of the planting coulter 7. The frame 2 further comprises parallelogram mechanisms 10, by means of which the planting depth can be adjusted and be maintained at the adjusted value. For details about this mechanism reference can be had to Dutch patent No. 1014692.

Figs, 2-4 show different views of a planting element 6 as shown in Fig. 1, comprising a housing 11, two horizontal shafts 12, on which a drum 13 is mounted, and an endless belt 14, which is passed over the drums 13 and to which three vertical rows of cups 15 are attached. The lower drum 13 is driven proportionally to the speed of the planting machine 1 by means of a chain (not shown). The front side of each of the planting elements 6 is provided with three parallel semi-tubes 16, which surround the respective rows of cups 15. I.e., inherent to this configuration is the fact that the rows that lie side by side extend jointly in a direction transversely to the direction of movement of the planting machine 1. A funnel-shaped, symmetrical guide 18 is disposed centrally below the planting element 6, the width of said guide at the upper side thereof being greater than or equal to the width of the belt 14, and the side walls 19 of said guide tapering off in downward direction, terminating in a common delivery opening 20. The front wall 21 of the guide 18 slopes towards the rear. The angle of said sloping wall 21 is adjustable from vertical to e.g. 45° in rearward direction.

During operation as shown in Fig. 4, the rear side of the belt 14 moves upwards, in such a manner that the cups 15 remove potatoes P from the storage hopper 5. After being turned upside down on the upper drum 13, the cups 15 move through the semi-tubes 16 at the front side of the planting elements 6. During this movement, the potatoes fall from their respective cups 15 onto the preceding cups 15. When the belt 14 reaches the lower drum 13, the cups 15 are turned upside down once again and the potatoes are released one by one. The potatoes fall into the guide 18, roll towards the delivery opening 20 and fall in the trench 22 under said delivery opening.

Fig. 3 shows the distances by which the cups 15 are spaced apart. The cups in one row are spaced a regular distance apart, which distance is the same for each row, viz. A+B+C, and preferably it is selected to be at least equal to or maximally 1.5 times larger than the distance that is used with the existing 2-cup belt (which is usually about 13 cm). Preferably, the value lies approximately halfway this range, so that on the one hand a higher capacity is achieved, given the same speed of the cup belt, whilst on the other hand an improved filling of the cups is achieved, because the filling interval between two cups in the same row is greater.

To ensure that the potatoes being planted will be in line with each other, the potatoes from the two outer planting channels must be moved over a relatively large distance towards the middle after exiting the planting channels. The potatoes exiting the outer channels must cover a longer distance, therefore, and experience more resistance, i.e. the time of fall before they hit the bottom of the pre-formed trench is longer.

To compensate for this difference in the time of fall between the potatoes from the middle channel and the potatoes from the outer channels, the middle row of cups is offset with respect to the outer rows.

The difference between the aforesaid distances A, B, and C that is optimal for specific circumstances must be determined by experiment, it depends inter alia on the shape and the material properties of the guide 18, i.e. on the speed with which the released potatoes slide through the guide 18. In this example, the distance C between the cups 15 in the right-hand row and the next cups in the middle row is larger than the distance B between the cups 15 in said middle row and the next cups 15 in the left-hand row. Furthermore, said distances, C and B, are larger and smaller, respectively, than the distance A between the cups 15 in the left-hand row and the next cups 15 in the right-hand row.

Thus, the moment at which the potatoes are released from a middle row is delayed in relation to the moment at which the potatoes are released from the right-hand row and, quite the contrary, advanced in relation to the moment at which the potatoes are released from the left-hand row.

A comparable result is obtained with the embodiment that is shown in Fig. 5. In this embodiment, the distances A, B and C between the cups 15 are identical, but the cups 15 in the middle row are longer than the cups 15 in the left-hand row and the right-hand row. As a result, the clearance between the cups 16 in the middle row and the respective semi-tube 16 will be large enough at a later moment to release the potato. In the embodiment that is shown in Fig. 6, the moment at which the potatoes in the middle row of cups 15 are released is delayed in that the diameter of the middle semi-tube 16 is smaller than the diameter of the left-hand tube 16 and the right-hand tube 16.

To reduce the extent to which bouncing of the released potatoes occurs, and at least slightly suppress uncontrolled variations in the time of fall for each potato, it is preferable for at least the side walls 19, and possibly also the aforesaid sloping wall 21, to be made of a flexible material. Suitable materials are, for example, gauze, cloth, either woven or nonwoven, and foil.

The sloping wall 21 furthermore guides the potatoes in a rearward direction, i.e. in a direction opposed to the direction of movement of the planting machine. As a result, the forward speed of the planting machine is partially compensated and the potatoes will hit the ground at a lower speed.

The invention is not limited to the embodiments as described above, which can be varied in many ways within the scope of the invention as defined in the claims. Thus it is possible to provide a separate belt and separate drums for each row instead of a common belt (14) and common drums (30). The height of the rows of cups and thus the height at which the bulbs or tubers are released from said rows can be freely selected for each individual row in that case.

Furthermore, the planting elements may comprise four or more rows of cups. Moreover, an asymmetrical guide may be used, in which case the moment and/or the height at which the bulbs or tubers are released above the guide can be adapted to such a guide again.