WO2008108732A1

WO2008108732A1 - An arrangement for a seed metering device on an agricultural machine

Info

Publication number: WO2008108732A1
Application number: PCT/SE2008/050246
Authority: WO
Inventors: Gert Gilstring
Original assignee: Väderstad-Verken Ab
Priority date: 2007-03-05
Filing date: 2008-03-05
Publication date: 2008-09-12
Also published as: SE0700529L; SE531269C2

Abstract

The present invention relates to a device (10) and a method for detecting particles in a flow The device (10) comprises a particle chamber (11 ) having an inlet (12) and an outlet (13) for a flow containing particles flowing through the particle chamber (11 ), and a detector (15) for detecting particles in the flow containing particles, the detector being arranged at an angle towards the particle chamber (11 ). The detector (15) is arranged in a detector chamber (14) being arranged at an angle to the particle chamber (11 ), the detector chamber (14) being connected to the particle chamber through an aperture (20) through which detection can be performed, and the detector chamber (14) being provided with an intake channel (21 ) for introducing a counterflow, wherein said counterflow can flow in through the intake channel (21 ), through the detector chamber (14) and out through the aperture (20) at an angle to the flow containing particles to prevent this from entering the detector chamber (14).

Description

AN ARRANGEMENT FOR A SEED METERING DEVICE ON AN AGRICULTURAL MACHINE

TECHNICAL AREA

The invention refers to an agricultural machine comprising at least one seed metering device for distributing seeds to soil over which the agricultural machine moves, wherein the seed metering device is connected to a structural member, being a part of the agricultural machine, in such a way that the seed metering device is moveable at least partly vertically in relation to the structural member, in addition to which the seed metering device comprises a seed metering element which by means of a drive device is rotatable around a seed metering axle and adapted to, at a distance from the seed metering axle, take and release seeds.

BACKGROUND

An agricultural machine of the type 'precision seed drill' (Eng. planter) is moved, usually towed by a tractor, over the soil that is to be drilled, and comprises a plurality of, in the lateral direction of the machine distributed, row sowing entities, each one adapted to form a seed furrow in the direction of travel of the machine, and by means of a special device place a row of seeds in the seed furrow. In order to create good conditions for the crop and yields it is important that the seeds are placed at a constant, uniform distance from each other. There is also a desire to be able to maintain a high driving velocity at sowing, decreasing the time requirement.

Patent document US6564730B2 describes a precision seed drill with row sowing entities, each with two discs obliquely rotatable in its own direction for formation of a seed furrow, which row sowing entities can move vertically in relation to the frame of the precision seed drill. Seed metering devices, each one fixedly connected to one respective of the row sowing entities, are each one adapted to distribute one seed at a time to the respective seed furrow. Even with solutions of this type an

-. i O FY - I RA NSLm U )N Rule 12.4) uneven seed distribution is not infrequently obtained in the seed furrows, especially at relatively high velocities for the machine. Such problems with uneven seed distribution can mean that the driving velocity at sowing must be kept relatively low.

SUMMARY

One aim with the invention is to decrease the time requirement at sowing with an agricultural machine of the type precision seed drill.

A further aim with the invention is to permit higher driving velocities at sowing with an agricultural machine of the type precision seed drill.

Another aim with the invention is to achieve a uniform placement of seeds with an agricultural machine of the type precision seed drill.

A further aim with the invention is to achieve a uniform placement of seeds with an agricultural machine of the type precision seed drill, even at relatively high velocities for the agricultural machine.

These aims are achieved with an agricultural machine of the initially described type wherein the drive device is adapted to increase the rotational speed of the seed metering element at an upward-directed relative movement of the seed metering device, and to decrease the rotational speed of the seed metering element at a downward-directed relative movement of the seed metering device.

As is described more closely below, the movement of the seed metering device, on the basis of which rotational speed of the seed metering element is adjusted, can be a movement in relation to the structural member or alternatively to the soil. Thus the drive device at certain embodiments can be adapted to increase and decrease, respectively, the rotational speed of the seed metering element at a upward-directed movement and downward-directed movement, respectively, for the seed metering device in relation to the structural member, and at other embodiments the drive device can be adapted to increase or decrease, respectively, the rotational speed of the seed metering element at a upward-directed movement or downward-directed movement, respectively, for the seed metering device in relation to the soil. In cases, which are exemplified more closely below, where the seed metering device is coupled to a row sowing entity, which has a mass which is considerably smaller than the mass of a structure on the agricultural machine, which structure comprises the structural member, the vertical movements of the structural member are considerably smaller than the vertical movements of the row sowing entity. This means that the vertical velocity of the row sowing entity, and thereby of the seed metering device, in relation to the structural member in such cases is mainly the same as their vertical velocity in relation to the soil.

It transpires that previous solutions have not considered that variations in the vertical velocity of the seed metering device, and the absence of vertical velocity at certain time intervals for the movement of the agricultural machine, in combination with a vertical velocity for the seed metering device at other time intervals for the movement of the agricultural machine, contribute to a high degree to a uneven distribution of the seeds in the seed furrow. The invention permits, in cases where the seed metering axle is not vertical, especially where the seed metering axle is primarily horizontal, and the seeds are released on a side of the seed metering axle on which the seeds are transported by the seed metering element with a downward- directed velocity component in relation to the seed metering axle, that the downward-directed velocity component of the seeds in relation to the seed metering axle increases at an upward-directed relative movement of the seed metering device, and that the downward-directed velocity component of the seeds in relation to the seed metering axle decreases at a downward-directed relative movement of the seed metering device. This means in its turn that the difference in velocity in relation to the seed furrow for different seeds is decreased so that variations in time for displacement of the seeds from the seed metering device to the seed furrow are decreased. A more even seed distribution in the seed furrow at soil irregularities is thereby achieved. The increased precision for the seed distribution means that driving velocity at sowing can increase, which means that the time requirement decreases.

Preferably, the seed metering element is adapted to release seeds in a release region, and the drive device and the seed metering device are arranged so that a vertical component of an increase and decrease, respectively, of the velocity of the seed metering element in the release region, corresponding to the increase and decrease, respectively, in rotational speed of the seed metering element, is 26-75% of the vertical component of the velocity of the seed metering device at the upward- directed relative movement and downward-directed relative movement, respectively.

By the concept release region, (in the drawings marked with the reference code SL), is meant here an area in which a seed transport area displayed by the seed metering element, (see e.g. Fig. 3, #806), is adapted to release the seed. At use of the agricultural machine an at least partly vertical velocity for the seed metering axle in relation to the structural member or the soil gives rise to a change in the rotational speed of the seed metering element, which in its turn alters the velocity for the seed transport area in the release region. If the vertical component of the velocity change for the seed transport area in the release region is as large as the vertical component of the velocity for the seed metering axle, so a complete compensation for the velocity of the seeds is obtained at the release occasion for vertical movement of the seed metering device. However, according to the actual embodiment the vertical component of the velocity change for the seed transport area in the release region is 26-75% of the vertical component of the velocity of the seed metering device at the respective upward- directed or downward- directed relative movement. This means a partial compensation for the velocity of the seeds at the release occasion for vertical movement of the seed metering device. This decreases the velocity changes for the seed transport area, which in its turn decreases risks of the seeds being missed when they are to be taken up by the seed metering element, (s.c. 'skips'). Furthermore in practical tests it has been shown that especially energy- rich frequencies for the vertical movements of the seed metering device, caused by soil irregularities, normally lie in the range 2-10 Hz. Calculations show that within the compensation range 26-75% irregularities in the seed distribution in the seed furrow are minimised at all frequencies in the range 2- 10 Hz.

Preferably, the drive device and seed metering device are arranged so that the vertical component of the increase and decrease, respectively, of the velocity of the seed metering element in the release region, corresponding to the increase and decrease, respectively, in rotational speed of the seed metering element, is 36-72%, preferably approx. 45%, of the vertical component of the velocity of the seed metering device at the upward-directed relative movement and downward-directed relative movement, respectively. Within the compensation range 36-72% irregularities in the seed distribution in the seed furrow are minimised at the most commonly occurring frequencies for vertical movements of the seed metering device. In practical tests it has been shown that the range 3-8 Hz includes frequencies that are considerably energy-richer than frequencies outside this range. Calculations show that within the compensation range 36-72% irregularities in the seed distribution in the seed furrow are minimised at all frequencies in the range 3-8 Hz.

The drive device preferably comprises a primary drive member that displays at least one primary axis of rotation the position of which in relation to the structural member is constant,

- in addition to which the at least one primary axis of rotation is orientated primarily perpendicularly to the intended direction of travel of the agricultural machine and primarily horizontally, - in addition to which the drive device comprises at least one secondary drive member adapted to be driven, directly or indirectly, by the primary drive member and to drive, directly or indirectly, the seed metering element.

The drive device can thereby be arranged so that the primary drive member, at metering of seeds from the seed metering device, at least in an engagement region for engagement with at least one of the secondary drive members, rotates either in a lefthand revolution or a righthand revolution viewed from the left in the intended direction of travel of the agricultural machine.

The primary drive member can comprise a primary drive wheel, and one of the secondary drive members can be a seed metering drive wheel that is fixedly connected to the seed metering element and concentric with the seed metering axle and adapted to be driven by the primary drive member via at least one additional secondary drive member. More specifically at least one of the at least one additional secondary drive member can comprise an endless flexible member. As an alternative at least one of the at least one additional secondary drive member can comprise a drive axle.

The drive device is preferably arranged so that a path angle between the direction of a movement of the seed metering device in relation to the structural member and an angled part of the path for the endless flexible member, at which angled part of the path the endless flexible member is adapted to be driving, is less than 90 degrees. This applies at least in a vicinity of a 'neutral position' for the seed metering device, i.e. in a position adopted by the seed metering device in the absence of soil irregularities. Furthermore the drive device can be arranged so that the path for the endless flexible member at one end of the mentioned angled part of the path extends around the primary drive wheel. That the endless flexible member is adapted to be driving at the angled end of the path means that in this part of the path it is exposed to draught forces for transference of movements from the primary drive member to the seed metering element. As is explained more closely below, at embodiments which display a path angle in the mentioned way there is a respective decrease and increase, at a respective downward-directed and upward-directed relative movement of the seed metering element, in the length of the mentioned angled part of the path, so that the rotational speed for the seed metering drive wheel decreases or increases respectively, so that the desired compensation of the seed metering velocity is achieved.

The path angle is preferably less than 85 degrees. As is explained more closely below a compensation KG of the seed metering velocity for vertical movements of the seed metering device can be expressed as KG=cos(α)*R3/R2, where α is the mentioned path angle between the angled path part of the endless flexible member and the direction of relative movement of the seed metering device, R2 is the radius of the seed metering drive wheel and R3 is the radial distance from the seed metering axle for a seed transport area described more closely below. If the path angle α is greater than 85 degrees it is required for a desired compensation that the relationship R3/R2 is relatively large. Since is the radial distance R3 from the seed metering axle for the seed transport area often is restricted with respect to other requirements in the design of the seed metering device, for achievement of a desired compensation the radius R2 of the seed metering drive wheel must be small. This means, especially in embodiments where the endless flexible member is a chain, a great risk for slack at the engagement between the endless flexible member and the seed metering drive wheel. This can in its turn cause uneven rotation movements of the seed metering element, which can contribute to an uneven seed distribution in the soil. However, if the path angle α is less than 85 degrees the desired compensation of the seed metering velocity can be achieved with a relatively large seed metering drive wheel, wherein the risk of slack in the drive is reduced.

The path angle is preferably less than 80 degrees. At path angles under 80 degrees the desired compensation of the seed metering velocity can be achieved with a relatively moderate gearing between the primary drive wheel and the seed metering drive wheel. This is especially an advantage at embodiments where the endless flexible member is a chain, since at chain operation commonly occurring slack at strong gearings is enhanced at the driven entity.

In certain embodiments the drive device can comprise a breakwheel which is adapted to be in engagement with the endless flexible member at one end of the angled part of its path, in addition to which the position of the rotation axle for the breakwheel is fixed in relation to the seed metering axle. This means that the position of the seed metering device is not critical for the compensation function described above. More precisely the dependence of the position of the seed metering device on the positions for parts in a linkage device for structural connection of the seed metering device with the structural member is decreased. In particular the seed metering device can be disposed relatively far backwards on the agricultural machine, which is often practically advantageous at agricultural machines of the actual type.

The drive device can comprise a chain tensioner which is adapted to be in engagement with the endless flexible member at a part of its path at which it is not driving.

A group of embodiments have a common characteristic in that the drive device is adapted so that the primary drive member, at metering of seeds from the seed metering device, at least in an engagement region for engagement with at least one of the secondary drive members, rotates in a righthand revolution viewed from the left in the intended direction of travel of the agricultural machine.

At such embodiments the drive device provides a gearing with an important characteristic that can be illustrated with the following theoretical example: If the rotation of the primary drive member is impeded, a vertical component of a small displacement of the seed metering axle in relation to the primary drive member is greater than a vertical component of a displacement for a portion of the seed transport area which is disposed in the release region. Through this is achieved the compensation according to the invention of velocity of the seeds at the release occasion for vertical movement of the seed metering device.

As is exemplified more closely below the primary drive member in certain embodiments comprises a primary drive wheel and in other embodiments an endless flexible member. The endless flexible member can be a chain, or alternatively a belt.

At certain embodiments, e.g. those in which the primary drive member is provided as a primary drive wheel or an untwisted flexible member, the drive device is arranged so that the entire primary drive member rotates in righthand revolution viewed from the left in the intended direction of travel of the agricultural machine. At other embodiments, e.g. those in which the primary drive member is provided as a twisted belt, (exemplified below with reference to Fig. 7), the drive device is arranged so that in such a case the part of the primary drive member which is in engagement with the at least one of the secondary drive members, rotates in righthand revolution viewed from the left in the intended direction of travel of the agricultural machine.

Since the primary drive member at metering of seeds from the seed metering device, at least in an engagement region for engagement with the at least one of the secondary drive members, rotates in righthand revolution viewed from the left in the intended direction of travel of the agricultural machine, as is explained more closely below, at a downward- directed movement of the seed metering element in relation to the primary drive member, the rotational speed for the seed metering element decreases. Since the seed metering element is adapted to release the seeds in a release region on a side of the seed metering axle on which the seeds are transported by the seed metering element with a downward-directed velocity component in relation to the seed metering axle, the downward-directed movement of the seed metering device is compensated by the decreased rotational speed, so that the increase in the downward-directed velocity of the seeds in the release region, in relation to the structural member, becomes less.

Conversely, at an upward-directed movement of the seed metering element in relation to the primary drive member, the rotational speed for the seed metering element increases. Thus the upward-directed movement of the seed metering device is compensated by the increased rotational speed, so that the decrease in downward- directed velocity of the seeds in the release region, in relation to the structural member, becomes less.

In embodiments in which the primary drive member comprises an endless flexible member this can be adapted to, in the engagement region for engagement with at least one of the secondary drive members, run primarily parallel with a direction in which the seed metering device is moveable in relation to the structural member. In embodiments in which the seed metering device is moveable primarily vertically in relation to the structural member the endless flexible member is thus adapted run primarily vertically in the mentioned engagement region.

Regardless of the form in which the primary drive member is provided one of the secondary drive members can be a seed metering drive wheel which is fixedly connected to the seed metering element and concentrically with the seed metering axle and adapted to be driven by the primary drive member via at least one additional secondary drive member. The at least one additional of the secondary drive members can be an axle-driven member comprising a drive axle, which extends at least partly in the intended direction of travel of the agricultural machine. The primary drive member can thereby comprise a primary drive wheel in the form of a conical primary cogwheel in engagement with a conical first axle cogwheel being a part of the axle member, and concentric with and fixedly connected to the drive axle. In addition the seed metering drive wheel can be a conical seed metering cogwheel in engagement with a conical second axle cogwheel being a part of the axle member, and concentric with and fixedly connected to the drive axle. Alternatively the primary drive member can be in engagement with the axle drive member by means of a worm gear and the seed metering drive wheel can be in engagement with the axle drive member by means of a second worm gear. Regardless of the type of angle gear used, where the primary drive member comprises a primary drive wheel, the axle drive member can be swingably arranged around the primary axis of rotation of the primary drive wheel.

In certain embodiments at least one of the secondary drive members can be an endless flexible member, e.g. in the form of a chain. Furthermore the primary drive member can comprise a primary drive wheel and the endless flexible member can be adapted to run around the primary drive wheel. In addition the endless flexible member can be adapted to run around the seed metering drive wheel. In the case where the endless flexible member is adapted to run around the primary drive wheel and the seed metering drive wheel a very simple construction with few component parts is obtained. Such a construction can also be provided with very little play or slack in the drive device. This is of great importance for achievement of the desired effect of rapidly changing the rotational speed of the seed metering element at vertical movements of the seed metering device, e.g. at soil irregularities.

Alternatively, where at least one of the secondary drive members comprises an endless flexible member the endless flexible member can be adapted to run around a secondary drive wheel which is fixedly connected to and concentric with an additional secondary drive member, which is in engagement with the seed metering drive wheel.

In the case at least one of the secondary drive members comprises an endless flexible member the primary drive member can comprise a primary drive wheel and the endless flexible member can be swingable around the primary axis of rotation of the primary drive wheel.

In certain embodiments, exemplified more closely below with reference to Figs. 20 and 21 , the drive device comprises a drive unit, in addition to which the agricultural machine also comprises an electronic control entity, velocity determining means adapted to send to the control entity signals which indicate the velocity of the agricultural machine, and movement determining means adapted to send to the control entity signals which indicate movements of the seed metering device, in addition to which the control entity is adapted to control the drive unit at least partly on the basis of the signals from the velocity determining means and the movement determining means. The drive unit can thereby comprise an electric motor or a hydraulic drive element.

The movement determining means preferably comprises a transmitter for acceleration measurement. This can be directly or indirectly fixedly connected to the seed metering device, and allows detection of the acceleration of the seed metering device in relation to the soil. Against a background of the aim of achieving an even distribution of seeds in the soil, such a transmitter gives a very relevant basis for adjustment of the rotational speed of the seed metering element. The movement determining means preferably comprises a position detector. The position detector can thereby be used to eliminate residual errors at integration of the values from the transmitter for acceleration measurement.

The seed metering device is preferably connected to the structural member by means of a linkage device which comprises at least one upper and at least one lower primary linkage element, which is via respective first joints connected to the structural member and via respective second joints connected to the seed metering device, wherein respective second joint is displaced in the intended direction of travel of the agricultural machine from respective first joint. The seed metering device is preferably connected to the primary linkage elements via a carrier device on which a seed furrow forming means is mounted. Alternatively the seed metering device can be connected to the structural member by means of some other type of device. E.g. a carrier device, on which a seed furrow forming means and seed metering device are mounted, can be connected to the structural member by means of a longitudinal bendable element which by means of bending allows a relative movement between the carrier device and the structural member.

DESCRIPTION OF DRAWINGS AND TABLES

The invention will be described below in detail with reference to the drawings, in which

- Fig. 1 shows a perspective view of a precision seed drill, seen obliquely from above and obliquely from the rear, according to an embodiment of the invention,

- Fig. 2 shows a side view of a row sowing entity being a part of the precision seed drill in Fig. 1 ,

- Fig. 3 shows a perspective view of a section vertical and parallel with the direction of travel of the precision seed drill of a seed metering device being a part of the row sowing entity in Fig. 2,

- Fig. 4 shows details in Fig. 3 with a drive device and a seed metering device (partly sectioned),

- Fig. 5 shows a drive device and a seed metering device (partly sectioned) according to an alternative embodiment of the invention,

- Fig. 6 shows a drive device and a seed metering device (partly sectioned) according to yet another alternative embodiment of the invention,

- Fig. 7 shows a drive device and a seed metering device (partly sectioned) according to an additional alternative embodiment of the invention, - Fig. 8 shows a side view of a row sowing entity according to yet another alternative embodiment of the invention,

- Fig. 9 shows details in Fig. 8 with a drive device and a seed metering device (partly sectioned),

- Fig. 10 shows a side view of a row sowing entity according to an additional alternative embodiment, - Figs. 11-19 show respective pairs of drive devices and seed metering devices (partly sectioned) according to additional alternative embodiments of the invention,

- Fig. 20 shows a schematic perspective view of parts of a precision seed drill with alternative embodiments of the invention, and

- Fig. 21 shows a more detailed perspective view of some of the parts in Fig. 20.

DETAILED DESCRIPTION

Fig. 1 shows a perspective view of an agricultural machine in the form of a precision seed drill 1 according to an embodiment of the invention. The precision seed drill comprises a number, in this example eight, row sowing entities 2, each fastened on a structural member 3 comprising a cross-running steel beam. The precision seed drill is, by means of a fastening member 5 arranged at at least one free end of a longitudinal structure detail 4, adapted to be coupled behind a draught vehicle and brought in a direction indicated by the arrow F in Fig. 1. Each one of the row sowing entities 2 is adapted at movement of the machine 1 over the soil to be sown to create a seed furrow in the direction of travel of the machine, to place one seed at a time along the seed furrow in order to create a row of seeds in the direction of travel F of the machine, and to close the seed furrow.

Fig. 2 shows a side view of one of the row sowing entities 2. This is by means of a linkage device 6, described more closely below, connected to the cross-running structural member 3. The row sowing entity 2 comprises a seed container 7 which communicates via a below more closely described seed metering device 8, adapted via a distribution member 8a, (in Fig. 2 indicated by broken lines), to distribute one seed at a time to a seed furrow 9a in the soil 9.

The row sowing entity 2 comprises a carrier device 21, which comprises the distribution member 8a, and on which a seed furrow forming means comprising two rotatable discs 10, (of which only one is visible in Fig. 2), is mounted and adapted to form the seed furrow 9a. The discs 10 are in this example placed beside each other in essentially the same position in the intended direction of travel F of the machine. However the discs 10 can alternatively be displaced relative to each other in the intended direction of travel F of the machine. The discs 10 are angled relative to each other and orientated so that relative to each other they diverge backwards and upwards. The discs 10 are at use of the machine adapted to during rotation partly intrude into the soil to a predeterminable depth D, and through their mentioned relative divergence displace soil to the sides for formation of the seed furrow 9a, wherein a lower orifice on the seed metering device 8a is disposed just behind the intrusion of the discs 10 in the soil 9. The relative divergence of the discs backwards and upwards means that their peripheries are closest to each other in the area where they intrude into the soil.

The row sowing entity 2 in this example also comprises here not more closely described after-cultivating members 202, adapted to close the seed furrow 9a. The row sowing entity 2 can also comprise not shown in Fig. 2 fore-cultivating members, as well as protective members between the lower orifice on the seed metering device 8a and the intrusion of the discs 10 into the soil 9.

The row sowing entity 2 is adapted to be borne up by two support wheels 11 , disposed on each side of the pair of discs 10, wherein the wheel axles of the support wheels 11 are disposed somewhat behind the disc axles in the intended direction of travel F of the machine. More precisely the support wheels 11 are distributed, (perpendicularly to the intended direction of travel of the machine 1), on each side of the pair of discs 10, and they are disposed in the vicinity of a respective disc 10. The support wheels 11 are adapted at use of the machine 1 to scrape off soil and suchlike which fastens on the respective disc 10. The sowing depth D is according to known technique adjustable through adjustment of the height of the support wheels 11 in relation to the discs 10. Fig. 3 shows a perspective view of a section vertical and parallel with the direction of travel of the agricultural machine of a seed metering device 8. This comprises a cylindrical case 802 and a from the case downward directed seed metering pipe 801, which communicates with the distribution member 8a (Fig. 2). The seed metering device 8 comprises a seed metering element 803, in the form of a round seed metering plate 803 which is arranged essentially concentrically in the case 802. (The appearance of the case 802 and the placement of the seed metering plate 803 therein can of course deviate from the example in Fig. 3.)

During use the seeds 91 are gravity- fed from the seed container 7 (Fig. 2) into the case 802 on one side of the seed metering plate 803. The seed metering plate 803 is adapted by means of a drive device described more closely below (Fig. 2, #401) to rotate in its plane around a primarily horizontally orientated seed metering axle 805 as is indicated in Fig. 3 with the arrow R. The seed metering plate 803 is adapted to in a circular, with the seed metering axle 805 concentric seed transport area 806 at a distance from the seed metering axle 805, take, transport and release seeds. More precisely the seed metering plate 803 in the seed transport area 806 displays a plurality of through suction holes 804 disposed at the same radial distance from the seed metering axles 805, in this example in the vicinity of the periphery of the seed metering plate 803, which suction holes 804 are distributed at equal distance from each other in the circumference of the seed metering plate 803. A fan (not shown) communicates with the seed metering device 8 and the seed metering device 8 is adapted by means of the fan to bring about a pressure fall over a portion of the seed metering plate 803. Through the pressure fall a seed fastens in each suction hole 804 and is transported towards the seed metering pipe 801. The seed metering device 8 is adapted to release the seeds on a side of the seed metering axle 805 on which the seeds are transported by the seed metering plate 803 with a downward-directed velocity component in relation to the seed metering axle 805. More precisely, at the seed metering pipe 801, in what here is called a release region SL (indicated in Fig. 3 by broken lines), the pressure fall is by means of a not shown pressure dividing means, e.g. in the form of a flexible wall, less than in other parts of the seed metering device 8. Due to the decreased pressure fall the seeds are released from the respective suction holes 804, in the release region SL, and fall down through the seed metering pipe 801.

The drive device 401 is according to known technique arranged so that the rotational speed of the seed metering element 803 around the seed metering axle 805 increases at an increase in the velocity of the agricultural machine, and vice versa.

The seed metering device 8 can within the framework for the invention be arranged in a large number of alternative ways. For example, as is also mentioned below, the seed metering device 8 can be orientated in alternative ways in relation to the agricultural machine, e.g. so that the seed metering element 803 extends primarily in a plane perpendicular to the direction of travel of the agricultural machine.

Furthermore the pressure fall obtained over the seed metering element 803 by means of the fan can be achieved with an atmospheric pressure on one side of the seed metering element 803 and a pressure deficit on the other side, or with a pressure head on one side of the seed metering element 803 and an atmospheric pressure on the other side. Instead of suction holes the seed metering plate 803 on one side can display at its periphery evenly distributed deepenings, each one adapted to take up a seed, in addition to which a smaller through hole in the bottom of the respective deepenings achieves by means of the pressure fall retaining the respective seed.

Alternatives to the pressure fall-caused uptake of seeds on the seed metering plate 803 can be provided. In one alternative the seed metering device can be arranged as something called in English "finger pickup meter", in which a number of cam- driven "fingers" are evenly distributed at the periphery of the seed metering plates, and each one adapted at rotation of the plate, by means of the cam drive, to pick up in a certain area one seed at a time and in another area release the seed. In the embodiment described with reference to Fig. 3, in which the seed metering axle 805 is primarily horizontal, the release region SL is disposed primarily in the same height position as the seed metering axle 805, so that the seed transport area 806 has a maximal downward-directed velocity component in release region SL. Alternatively release region SL can be disposed higher or lower than the seed metering axle 805, although on a side of the seed metering axle on which the seeds are transported with a downward-directed velocity component in relation to the seed metering axle.

As shown in Fig. 2 the linkage device 6, which connects the row sowing entity 2 with the structural member 3, comprises two upper and two lower primary linkage elements 601, 602, of which only one upper and one lower primary linkage element are visible in Fig. 2. The two upper primary linkage elements 601 , likewise the two lower primary linkage elements 602, have the same orientation, are disposed in the same position heightwise and in the intended direction of travel F of the agricultural machine, and are disposed a distance from each other in the cross-going direction of the agricultural machine. It should be pointed out that in alternative embodiments the linkage device 6 can display only one upper and one lower primary linkage element 601 , 602, or more than two upper and more than two lower primary linkage elements 601, 602.

Each one of the primary linkage elements 601, 602 is via respective first joints 603 connected to an anchoring member 301 being a part of the structural member 3, and via respective second joints 604 connected to a coupling portion 211 displayed by the carrier device 21. Respective second joint 604 is thereby displaced in the intended direction of travel F of the agricultural machine from respective first joint 603. The distance L between the first and second joint 603, 604 at the upper primary linkage element 601 is essentially equally large as the distance L between the first and second joint 603, 604 at the lower primary linkage element 602. Furthermore the distance between the first joint 603 at the, viewed in the intended direction of travel of the agricultural machine, left upper primary linkage element 601 and the first joint 603 at the left lower primary linkage element 602 is essentially equally large as the distance between the second joint 604 at the left upper primary linkage element 601 and the second joint 604 at the left lower primary linkage element 602. The equivalent also applies for the right primary linkage elements. In addition the first and the second joint 603, 604 at the left upper primary linkage element 601 are disposed at essentially the same position in the intended direction of travel F of the agricultural machine as the respective first and second joint 603, 604 at the left lower primary linkage element 602. The equivalent also applies for the right primary linkage elements.

As can be seen in Fig. 2 the seed metering device 8 and the seed container 7 are fixedly connected to the carrier device 21.

Here reference is to Fig. 4. The row sowing entity and thereby the seed metering device 8 are by means of the above described linkage device moveable primarily vertically in relation to the structural member 3, as is indicated in Fig. 4 with the double arrow VF. Such movement occurs at soil irregularities at use of the agricultural machine.

In this embodiment the drive device 401 comprises a primary drive member 411 comprising an endless flexible member 411 in the form of a chain 411, (in Fig. 4 partly represented by dashed lines). The chain 411 is adapted to run around two guide wheels 412 and a power transfer wheel 413, which is rotatable around the respective primary axes of rotation 414, 415, which are orientated primarily perpendicularly to the intended direction of travel F of the agricultural machine and primarily horizontally. The power transfer wheel 413 is adapted to transfer driving force to the chain 411. The guide wheels 412 and the power transfer wheel 413 are mounted on a drive device structure 416 fixedly connected to the structural member 3, and thus the position of the primary axes of rotation 414, 415 in relation to the structural member 3 is constant. However it should be noted that one of the guide wheels, in this embodiment the upper 412, can be arranged as a chain tensioner for maintenance of suitable tension in the chain 411.

The drive device 401 further comprises a secondary drive member in the form of a seed metering drive wheel 421, (in Fig. 4 only partly reproduced), which is fixedly connected to the seed metering element 803 and concentric with the seed metering axle 805. The seed metering drive wheel 421 is provided in the form of a chain wheel 421 and is adapted to be driven directly by the chain 411. The chain 411 is adapted to run primarily vertically between the guide wheels 412 in an engagement region IO for engagement with the seed metering drive wheel 421.

As is indicated by the arrow P in Fig. 4, the drive device is arranged so that the primary drive member 411, i.e. the chain 411, at metering of seeds from the seed metering device 8 rotates in righthand revolution viewed from the left in the intended direction of travel F of the agricultural machine. Furthermore, viewed in the intended direction of travel F of the agricultural machine, the seed metering plate 803 is disposed behind the chain 411, and the seed metering pipe 801 and the release region SL are disposed in front of the seed metering axle 805.

The drive device preferably comprises a chain tensioner (not shown) for maintenance of suitable tension in the chain 411.

At an upward-directed movement of the seed metering device 8 in relation to the structural member 3 the rotational speed of the seed metering plate 803 increases, and at a downward- directed movement of the seed metering device 8 in relation to the structural member 3 the rotational speed of the seed metering plate 803 decreases. This can easily be forestalled through a consideration of Fig. 4 on the assumption that the primary drive member 411 is kept still and the seed metering plate 803 is displaced small ways vertically: At an upward-directed or downward- directed movement of the seed metering plate 803 the suction holes 804 in the release region SL come to remain at the same level in relation to the structural member 3. Thus the velocity of the suction holes 804 in the release region SL comes to be 0 in relation to the structural member 3 at vertical movements of the row sowing entity and thereby of the seed metering device 8 in relation to the structural member 3. This means that the velocity of the seeds when these are released is not affected by vertical movements of the seed metering device 8, which in its turn means that irregularities in the seed distribution in the seed furrow can be strongly reduced. Thus this and other embodiments achieve, with a simple mechanical solution, an essential improvement of the precision in the seed furrow and or make possible a considerably higher velocity for the agricultural machine.

In the embodiment shown in Figs. 2-4 the seed metering velocity is completely compensated for the vertical relative movements of the seed metering device 8. This is achieved through the engagement radius of the seed metering drive wheel 421 and the radial distance of the seed transport area 806 from the seed metering axle 805 being the same.

Fig. 5 shows an alternative embodiment that corresponds with the embodiment shown in Figs. 2-4 with the exception that the seed metering velocity is only partly compensated for vertical movements of the seed metering device 8. This is achieved through the engagement radius of the seed metering drive wheel 421 being larger than the radial distance of the seed transport area 806 from the seed metering axle 805. More generally the agricultural machine is arranged so that the respective increase and decrease in the rotational speed of the seed metering element 803, at respective upward and downward-directed relative movement of the seed metering device 8, is responded to by a vertical component of a velocity change of the seed transport area 806 in the release region SL that is less than the respective upward- and downward-directed relative movement of the seed metering device 8. This decreases the velocity changes for the seed transport area, which in its turn decreases risks of the seeds being missed when these are to be taken up by the seed metering element, (s.c. 'skips'). For additional reasons explained above the compensation of the seed metering velocity is preferably 26-75%, and more preferred 36-72%, of the vertical component of the velocity of the seed metering device 8 in relation to the structural member.

Fig. 6 shows an alternative embodiment which corresponds with the embodiment shown in Figs. 2-4 with the exception that, viewed in the intended direction of travel F of the agricultural machine, the seed metering device 8 with the seed metering plate 803 is disposed in front of the engagement region in which the chain 411 runs primarily vertically between the guide wheels 412 for engagement with the seed metering drive wheel 421 , wherein the seed metering pipe 801 and the release region SL are disposed behind the seed metering axle 805.

As an alternative to the chain-/cogwheel operation shown embodiments in Figs. 2-6 the endless flexible member can be provided in the form of a belt, wherein the power transfer wheel 413, the guide wheels 412 and the seed metering drive wheel 421 are adapted to co-operate with the belt by means of friction, or, in the case where the endless flexible member is provided as a cogbelt, by means of cog engagement. Furthermore the seed metering drive wheel 421 can alternatively be adapted to be driven indirectly by the endless flexible member 411 via at least one additional drive member, e.g. comprising a wheel and/or an axle.

Here reference is to Fig. 7, which shows an alternative embodiment which corresponds with the embodiment shown in Figs. 2-4 with the exception that the primary drive member 411, in the form a belt 411, (in Fig. 7 represented by dashed lines), is twisted, wherein it, at metering of seeds from the seed metering device 8, in the engagement region IO for engagement with the seed metering drive wheel 421, rotates, as is indicated by the arrow P in Fig. 7, in righthand revolution viewed from the left in the intended direction of travel F of the agricultural machine. Due to the belt 411 being twisted it rotates in the area for engagement with the power transfer wheel 413 in the opposite direction, i.e. in lefthand rotation viewed from the left in the intended direction of travel F of the agricultural machine. Here reference is to Figs. 8 and 9 which show an additional alternative embodiment which corresponds with the embodiment shown in Figs. 2-4 with the following essential exceptions:

In this embodiment the drive device 401 comprises a primary drive member 411 comprising a primary drive wheel 411 in the form of a conical primary cogwheel 411, which is rotatable around a primary axis of rotation 414. The primary drive member 411 is mounted on a drive device structure 416 fixedly connected to the structural member 3, and thus the position of the primary axis of rotation 414 in relation to the structural member 3 is constant.

With reference especially to Fig. 9 the seed metering drive wheel 421 is provided in the form of a conical seed metering cogwheel 421, and is adapted to be driven by the primary drive wheel 411 via a secondary drive member 431 in the form of an axle-driven member 431 comprising a drive axle 432, which extends primarily in the intended direction of travel F of the agricultural machine. The primary drive wheel 411 is in engagement with a conical first axle cogwheel 433 which is a part of the axle drive member 431 and is concentric with and fixedly connected to the drive axle 432. The seed metering drive wheel 421 is in engagement with a conical second axle cogwheel 434 which is a part of the axle drive member 431 and is concentric with and fixedly connected to the drive axle 432.

The axle drive member 431 is journalled in bearings arranged in a suitable axle structure 435, (e.g. a not shown gearbox), schematically indicated in Fig. 9 by broken lines. The axle structure 435 is in its turn journalled in bearings around the primary axis of rotation 414, wherein the axle drive member 431 is swingably arranged around the primary axis of rotation 414. Thus the axle drive member 431 can, at movements VF of the seed metering device 8 in relation to the structural member 3, swing around the primary axis of rotation 414. As can be seen in Fig. 8 the distance LA between the primary axis of rotation 414 and the seed metering axle 805 is the same as the distance LL between respective first and second joints 603, 604 at the respective upper and lower primary linkage element 601, 602. Furthermore a conceptual line at the primary drive wheel 411 and the seed metering drive wheel 421 which cuts the primary axis of rotation 414 and the seed metering axle 805 is parallel with respective conceptual lines at the respective first and second joints 603, 604 which cut the axes of rotation for these joints. This causes the axle drive member 431 without length change to be able to follow movements of the seed metering axle 805.

As is indicated by the arrow P in Fig. 9, the drive device is arranged so that the primary drive wheel 411 at metering of seeds from the seed metering device 8 rotates in righthand revolution viewed from the left in the intended direction of travel F of the agricultural machine. Furthermore, viewed in the intended direction of travel F of the agricultural machine, the seed metering pipe 801 and the release region SL are disposed in front of the seed metering axle 805.

At an upward-directed movement of the seed metering device 8 in relation to the structural member 3 the rotational speed of the seed metering plate 803 increases, and at a downward-directed movement of the seed metering device 8 in relation to structural member 3 the rotational speed of the seed metering plate 803 decreases. This can easily be represented through a consideration of Fig. 9 under the assumption that the primary drive wheel 411 is kept still and the seed metering plate 803 is displaced small ways vertically: At an upward-directed movement of the seed metering plate 803 the axle drive member 431 with the axle structure 435 comes to swing around the primary axis of rotation 414 and the axle drive member 431 comes by means of the engagement of the first axle cogwheel 433 with the primary drive wheel 411 to rotate in righthand revolution in the intended direction of travel F of the agricultural machine. This means that the seed metering drive wheel 421 due to the engagement with the second axle cogwheel 434 comes to rotate in lefthand revolution in the view in Fig. 9. Thereby the seed metering plate 803 also comes to rotate in lefthand revolution in the view in Fig. 9. On condition that the gearing relation is as specified below, the suction holes 804 in the release region SL thereby come to remain at the same level in relation to the structural member 3. Thus the vertical velocity of the suction holes 804 in the release region SL comes to be essentially 0 in relation to the structural member 3 at vertical movements of the row sowing entity and thereby the seed metering device 8 in relation to the structural member 3.

Conversely at a downward-directed movement of the seed metering plate 803 the axle drive member 431 comes by means of the engagement of the first axle cogwheel 433 with the primary drive wheel 411 to rotate in lefthand revolution viewed in the intended direction of travel F of the agricultural machine. Thus the seed metering drive wheel 421 and the seed metering plate 803 come to rotate in righthand revolution in the view in Fig. 9. The suction holes 804 in the release region SL thereby come to remain at the same level in relation to the structural member 3.

In the embodiment in Figs. 8 and 9 the seed metering velocity is completely compensated for vertical movements of the seed metering device 8. This is achieved though the relationship between the gearing relation nl/n2 between the primary drive wheel 411 and the seed metering drive wheel 421, the radial distance RT of the seed transport area 806 from the seed metering axle 805 and the distance LA between the primary axis of rotation 414 and the seed metering axle 805 being such that: nl/n2=RT/(L A-RT). In an alternative embodiment the seed metering velocity can be only partly compensated for vertical movements of the seed metering device 8. This can be achieved through a higher gearing relation such that: nl/n2>RT/(LA- RT). For reasons explained above the compensation of the seed metering velocity is preferably 26-75%, and more preferably 36-72%, of the vertical component of the velocity of the seed metering device 8 in relation to the structural member.

Fig. 10 shows an alternative embodiment that corresponds with the embodiment shown in Figs. 8 and 9 with the following exception: The distance between the primary axis of rotation 414 and the seed metering axle 805 is different from, more precisely greater than, the distance between respective first and second joints 603, 604 at the respective upper and lower primary linkage element 601, 602. In addition the drive axle 432 comprises two parts, of which one is partly inserted into the other in such a way that relative rotation between the parts is prevented, with relative movement in the longitudinal direction of the drive axle 432 is possible. This can be achieved e.g. through the parts of the drive axle 432 being in engagement with each other by means of suitable complementary surface forms, e.g. s.c. splines or rectangular cross-section. Of course in an alternative embodiment the distance between the primary axis of rotation 414 and the seed metering axle 805 can be smaller than the distance between respective first and second joints 603, 604 at the respective upper and lower primary linkage element 601, 602.

It should be mentioned that the seed metering device 8 can alternatively be orientated so that the seed metering element 803 (Fig. 3) extends primarily perpendicularly to the intended direction of travel F of the agricultural machine. In such an embodiment the seed metering element 803 can be connected to a drive axle 432 (Fig. 10) via a cardan coupling or a similar device that permits angle changes between the seed metering element 803 and the drive axle 432. Furthermore the drive axle 432, as is described above with reference to Fig. 10, can comprise two parts, so as to permit a relative movement in the longitudinal direction of the drive axle 432.

Fig. 11 shows another alternative embodiment which corresponds with the embodiment shown in Figs. 8 and 9 with the exception that the seed metering drive wheel 421, viewed in the intended direction of travel F of the agricultural machine, is in engagement with the second axle cogwheel 434 behind the seed metering axle 805. Furthermore, viewed in the intended direction of travel F of the agricultural machine, the seed metering pipe 801 and the release region SL are disposed behind the seed metering axle 805. In order to achieve that the seed metering velocity is fully compensated for vertical movements of the seed metering device 8 the relationship between the gearing relation nl/n2 between the primary drive wheel 411 and the seed metering drive wheel 421, the radial distance RT of the seed transport area 806 from the seed metering axle 805 and the distance LA between the primary axis of rotation 414 and the seed metering axle 805 must be such that: nl/n2=RT/(LA+RT). Alternatively, if the seed metering velocity must be only partly compensated for vertical movements of the seed metering device 8, the gearing relation must be such that: nl/n2>RT/(LA+RT). For reasons explained above the compensation of the seed metering velocity is preferably 26-75%, and more preferably 36-72%, of the vertical component of the velocity of the seed metering device 8 in relation to the structural member.

As an alternative to the embodiments described with reference to Figs. 8-11 the primary drive wheel 411, viewed in the intended direction of travel F of the agricultural machine, can be in engagement with the first axle cogwheel 433 in front of the primary axis of rotation 414. In addition, or alternatively, the seed metering drive wheel 421 can be adapted to be driven indirectly by the axle drive member 431 via at least one additional drive member, e.g. comprising a wheel, a chain and/or an additional axle. As an additional alternative the primary drive wheel 411 and the seed metering drive wheel 421, preferably provided with straight cogs, can be in direct engagement with each other.

Here reference is to Fig. 12 which shows another alternative embodiment which corresponds with the embodiment shown in Figs. 8 and 9 with the following essential exceptions:

In this embodiment the drive device 401 comprises a primary drive member 411 comprising a primary drive wheel 411 in the form of a primary-chain wheel 411, which is rotatable around a primary axis of rotation 414. The seed metering drive wheel 421 is provided in the form of a seed metering cogwheel 421, and is adapted to be driven by the primary drive wheel 411 via a first and a second secondary drive member 441, 442. The first secondary drive member 441 comprises an endless flexible member 443, in the form of a chain, (in Fig. 12 partly represented by dashed lines), and a secondary-chain wheel 444 which is rotatable around a secondary axis of rotation 445, wherein the chain 443 runs around the primary- chain wheel 411 and the secondary-chain wheel 444. The second secondary drive member 442 provided as a secondary cogwheel which is fixedly connected to and concentric with the secondary-chain wheel 444, and in engagement with the seed metering cogwheel 421.

The drive device 401 in Fig. 12 is essentially orientated so that a conceptual line TL at the drive member which cuts their axes of rotation 414, 445, 421 extends primarily in the intended direction of travel F of the agricultural machine. Furthermore the secondary axis of rotation 445 and the seed metering axle 805 are journalled in bearings arranged on a suitable structure (not shown) so that they are swingable around the primary axis of rotation 414, wherein the mentioned line TL remains straight at swing movements around the primary axis of rotation 414. Furthermore the distance between the primary axis of rotation 414 and the seed metering axle 805 is the same as the distance between respective first and second joints 603, 604 (cf. Fig. 8) at the respective upper and lower primary linkage element 601, 602. Furthermore the conceptual line TL (Fig. 12) is parallel with respective conceptual lines at respective first and second joints 603, 604 (cf. Fig. 8) which cut the axes of rotation for these joints. This means that the endless flexible member 443 without length alteration can follow movements of the seed metering axle 805. The drive device preferably comprises a chain tensioner 417 for maintenance of suitable tension in the chain 443.

As in the embodiments described above at an upward-directed movement of the seed metering device 8 in relation to the structural member 3 the rotational speed of the seed metering plates 803 increases, and at a downward-directed movement of the seed metering device 8 in relation to the structural member 3 the rotational speed of the seed metering plates 803 decreases. Fig. 13 shows an alternative embodiment that corresponds with the embodiment shown in Fig. 12 with the following exception: The secondary axis of rotation 445 is journalled in bearings arranged on a structure (not shown) so that it is swingable around the primary axis of rotation 414, wherein the secondary axis of rotation 445 and the seed metering axle 805 are so arranged that their relative positions remain essentially constant during vertical movements VF of the seed metering device 8 VF in relation to the structural member 3. In this embodiment the distance between the primary axis of rotation 414 and the secondary axis of rotation 445 is the same as the distance between respective first and second joints 603, 604 (cf. Fig. 8) at the respective upper and lower primary linkage element 601 , 602. Furthermore a conceptual line TL (Fig. 13) at the primary- and secondary drive members 411, 441, 442, which cut the primary axis of rotation 414 and the secondary axis of rotation 445, is parallel with respective conceptual lines at respective first and second joints 603, 604 (cf. Fig. 8) which cut the axes of rotation for these joints. This means that the endless flexible member 443 without length alteration can follow movements of the secondary axis of rotation 445. The drive device preferably comprises a chain tensioner 417 for maintenance of suitable tension in the chain 443.

Fig. 14 shows an alternative embodiment which corresponds with the embodiment shown in Fig. 12 with the following exception: In this embodiment the seed metering drive wheel 421 is provided in the form of a seed metering- chain wheel 421, and is adapted to be driven by the primary drive wheel 411 via a secondary drive member 443, comprising an endless flexible member 443, in the form of a chain, (in Fig. 14 partly represented by dashed lines). Furthermore, viewed in the intended direction of travel F of the agricultural machine, the seed metering pipe 801 and the release region SL are disposed behind the seed metering axle 805. The distance between the primary axis of rotation 414 and the seed metering axle 805 is the same as the distance between respective first and second joints 603, 604 (cf. Fig. 8) at the respective upper and lower primary linkage element 601, 602. Furthermore a conceptual line (Fig. 14) at the primary drive wheel 411 and the seed metering drive wheel 421 which cuts the primary axis of rotation 414 and the seed metering axle 805, is parallel with respective conceptual lines at respective first and second joints 603, 604 (cf. Fig. 8) which cuts the axes of rotation for these joints. This means that the endless flexible member 443 without length alteration can follow movements of the seed metering axle 405. The drive device preferably comprises a chain tensioner 417 for maintenance of suitable tension in the chain 443.

Fig. 15 shows an alternative embodiment which corresponds with the embodiment shown in Fig. 14 with the following exception: As is indicated by the arrow P in Fig. 15, the drive device is arranged so that the primary drive wheel 411, at metering of seeds from the seed metering device 8 rotates in lefthand revolution viewed from the left in the intended direction of travel F of the agricultural machine. In addition in this embodiment the seed metering drive wheel 421 has a considerably greater diameter than the primary drive wheel 411, which means that the drive device 401 has a considerably lower gearing relation than that in the embodiment in Fig. 14. Furthermore, viewed in the intended direction of travel F of the agricultural machine, the seed metering pipe 801 and the release region SL are disposed in front of the seed metering axle 805.

Through suitable choice of distance LPF between the primary axis of rotation 414 and the seed metering axle 805, the radius Rl for the primary drive wheel 411, the radius R2 for the seed metering drive wheel 421 and the radial distance R3 from the seed metering axle 805 for the seed transport area 806, an advantageous compensation KG of the seed metering velocity for vertical movements of the seed metering device 8 in relation to the structural member 3 can be achieved. As is explained above this compensation KG is preferably such that a vertical component of an increase and decrease, respectively, in the velocity of the seed metering element 803 in the release region SL, corresponding to the increase and decrease, respectively, in the rotational speed of the seed metering element 803, is 26-75%, and more preferably 36-72%, of the vertical component of the velocity of the seed metering device 8 in relation to the structural member at the upward- directed movement and downward-directed movement, respectively. More precisely in the embodiment shown in Fig. 15 the compensation KG of the seed metering velocity for vertical relative movements of the seed metering device 8 can be determined according to: KG=R3/L*(1-R1/R2). For example with the measurements R3=l 15 mm, Rl=25 mm, L=350 mm and R2=100 mm a compensation KG of 25% is achieved.

Fig. 16 shows an alternative embodiment which corresponds with the embodiment shown in Fig. 15 with the following exception: Between the seed metering drive wheel 421 and the primary drive wheel 411 is disposed a breakwheel 418. The breakwheel 418 is adapted to be in engagement with the endless flexible member 443 in a portion of its path in which it is driving, in this embodiment at its upper path between the seed metering drive wheel 421 and the primary drive wheel 411. Furthermore the breakwheel 418 is arranged, through its position and its radius, so that the upper path 443 a of the endless flexible member 443 changes direction downward at the breakwheel 418. The drive device 401 thus displays an angled part 443 a of the path for the endless flexible member 443, between the breakwheel 418 and the primary drive wheel 411, at which angled part 443 a of the path the endless flexible member 443 is adapted to be driving.

The position of the axis of rotation for the breakwheel 418 is fixed in relation to the seed metering axle 805. In this embodiment this is achieved through the seed metering device 8 and the breakwheel 418 being mounted on a shared carrier device 21.

The drive device preferably comprises a chain tensioner 417 for maintenance of suitable tension in the chain 443. The chain tensioner 417 is disposed between the seed metering drive wheel 421 and the primary drive wheel 411, and is adapted to be in engagement with the endless flexible member 443 at its lower path 443b between the seed metering drive wheel 421 and the primary drive wheel 411. The distance between the primary axis of rotation 414 and the axis of rotation for the breakwheel 418 is essentially the same as the distance between respective first and second joints 603, 604 (cf. Fig. 8) at the respective upper and lower primary linkage element 601, 602. It should however be mentioned that in alternative embodiments the distance between the primary axis of rotation 414 and the axis of rotation for the breakwheel 418 can be differing from the distances between the first and second joints 603, 604 at the primary linkage elements 601, 602.

In the embodiment in Fig. 16, at movements of the seed metering element 8 in relation to the structural member 3, the direction of relative movements RB for the axis of rotation for the breakwheel 418 is orthogonal to a conceptual line CL which cuts the first and the second joint 603, 604 at the upper (or the lower) primary linkage element 601.

As mentioned above a path angle α between the angled part 443 a of the path for the endless flexible member 443, and the direction RB of a movement of the seed metering device 8 in relation to the structural member 3 is less than 90 degrees, preferably less than 85 degrees, most preferably less than 80 degrees. This means that at a downward-directed relative movement and upward- directed relative movement, respectively, for the seed metering element 8, the length of the angled part 443a of the path for the endless flexible member 443 decreases and increases, respectively, so that the rotational speed for the seed metering drive wheel 421 decreases and increases, respectively. Through this the position of the chain tensioner 417 is adjusted in order to compensate for the length change of the upper path 443a for the endless flexible member 443.

Through suitable choice of the path angle α between the angled path part 443 a of the path for the endless flexible member 443, and the direction RB of a movement of the seed metering device 8 in relation to the structural member 3, the radius R2 for the seed metering drive wheel 421 and the radial distance R3 from the seed metering axle 805 for the seed transport area 806, an advantageous compensation KG of the seed metering velocity for vertical movements of the seed metering device 8 in relation to the structural member 3 can be achieved. More precisely in the embodiment shown in Fig. 16 the compensation KG of the seed metering velocity for vertical relative movements of the seed metering device 8 is determined according to: KG=cos(α )*R3/R2. For example with the values α=75°, and R3/R2=1.5 a compensation KG of 39% is achieved.

Fig. 17 shows an alternative embodiment which corresponds with the embodiment shown in Fig. 16 with the following exception: As is indicated by the arrow P in Fig. 17, the drive device is arranged so that the primary drive wheel 411, at metering of seeds from the seed metering device 8 rotates in righthand revolution viewed from the left in the intended direction of travel F of the agricultural machine. Furthermore, viewed in the intended direction of travel F of the agricultural machine, the seed metering pipe 801 and the release region SL are disposed behind the seed metering axle 805. The breakwheel 418 is adapted to be in engagement with the endless flexible member 443 in a portion of its path in which it is driving, in this embodiment at its lower path between the seed metering drive wheel 421 and the primary drive wheel 411. Thus the drive device 401 displays, as in the embodiment in Fig. 16, an angled part 443a of the path for the endless flexible member 443 , between the breakwheel 418 and the primary drive wheel 411, at which angled part 443 a of the path the endless flexible member 443 is adapted to be driving.

In contrast to the embodiment in Fig. 16 the chain tensioner 417 is disposed between the seed metering drive wheel 421 and the primary drive wheel 411, and is adapted to be in engagement with the endless flexible member 443 at its upper path 443b between the seed metering drive wheel 421 and the primary drive wheel 411.

As in the embodiment in Fig. 16 a path angle α between the angled part 443a of the path for the endless flexible member 443, and the direction RB of a movement of the seed metering device 8 in relation to structural member 3 is less than 90 degrees, preferably less than 85 degrees, most preferably less than 80 degrees.

Fig. 18 shows an alternative embodiment which corresponds with the embodiment shown in Fig. 16 with the following exception: The drive device lacks breakwheel of the type shown in Fig. 16. The drive device 401 displays an angled part 443a of the path for the endless flexible member 443, between the seed metering drive wheel 421 and the primary drive wheel 411, at which angled part 443 a of the path the endless flexible member 443 is adapted to be driving. At movements of the seed metering element 8 in relation to the structural member 3, the direction of the relative movement RB for the seed metering axle 805 is orthogonal to the conceptual line CL.

In ways which correspond to that at the embodiment in Fig. 16 a path angle α between the angled part 443 a of the path for the endless flexible member 443, and the direction RB of a movement of the seed metering axle 805 in relation to the structural member 3 is less than 90 degrees, preferably less than 85 degrees, most preferably less than 80 degrees.

As alternative to the embodiments in Figs. 12-18 the endless flexible member can be adapted to run around a chain wheel which is fixedly connected to and concentric with a cogwheel which in its turn is in engagement with the primary drive wheel.

Fig. 19 shows an alternative embodiment which corresponds with the embodiment shown in Fig. 17 with the following exception: The embodiment in Fig. 19 lacks breakwheel 418 of the type which is shown in Fig. 17. The endless flexible member 443 is adapted to run around a first between-lying chain wheel 461 which is fixedly connected to and concentric with a second between-lying chain wheel 462 which in its turn is adapted to drive the seed metering drive wheel 421 via an additional endless flexible member 463. The drive device 401 displays an angled part 443 a of the path for the endless flexible member 443, at its lower path between the first between-lying chain wheel 461 and the primary drive wheel 411, at which angled part 443 a of the path the endless flexible member 443 is adapted to be driving. As in the embodiments in Figs. 16-18 a path angle α between the angled part 443a of the path for the endless flexible member 443, and the direction RB of a movement of the seed metering device 8 in relation to the structural member is less than 90 degrees, preferably less than 85 degrees, most preferably less than 80 degrees.

As an alternative to the chain-/cog engagement operation shown the embodiments in Figs. 12-19 the endless flexible member can be provided in the form of a belt which runs over wheels which are adapted to co-operate with the belt by means of friction, or at use of cogbelt, by means of cog engagement.

Fig. 20 shows a schematic perspective view of parts of a precision seed drill with alternative embodiments of the invention, which correspond with those described above, with the exception of the following essential differences. The embodiments in Fig. 20 have in common that the drive device 401 for the seed metering device 8, (which is fixedly mounted on the row sowing entity 2), comprises a drive unit 401 , in the form of an electric motor, a hydraulic drive element, or equiv., fixedly connected to the seed metering device 8. The agricultural machine also comprises an electronic control entity 451 , velocity determining means 452a, 452b adapted to send to the control entity 451 signals which indicate the velocity of the agricultural machine, and movement determining means 453a, 453b adapted to send to the control entity signals which indicate primarily vertical movements of the seed metering device 8. The control entity 451 is adapted to control the drive unit 401 at least partly on the basis of the signals from the velocity determining means 452a, 452b and the movement determining means 453a, 453b. The velocity determining means can be provided as a radar 452a, or alternatively as a rotation transmitter 452b, arranged at a cogwheel 454 or equiv. which is fixedly connected to and concentric with a transport wheel 455 for the agricultural machine. The rotation transmitter 452b can be a pulse transmitter of inductive or optical type, adapted to detect passage of existing cogs at the periphery of the cogwheel. Possible alternatives to such pulse transmitters are in themselves known and are not described more closely here. On the basis of the signals from the velocity determining means 452a, 452b the drive unit 401 is driven so that the velocity of the drive unit 401 increases at an increase in the velocity of the agricultural machine, and vice versa.

With reference to Fig. 21 the movement determining means can be provided as a position detector 453a arranged at the first joint 603 for one of the upper primary linkage elements 601, (or at some other suitable site, e.g. at one of the lower primary linkage elements 602). At vertical movements of the row sowing entity 2 in relation to the structural member 3 the position detector 453a detects the altered angle position of the upper primary linkage element 601. The control entity 451 is adapted on the basis of several sequential position determinations to determine the vertical velocity of the seed metering device 8.

Alternatively the movement determining means can be provided as a transmitter for acceleration measurement 453b which is fixedly mounted on the row sowing entity 2. Through this, as an alternative to the position shown in Fig. 21, the transmitter 453b can be fixedly mounted directly on the seed metering device 8. At vertical movements of the row sowing entity 2 in relation to the soil 9, e.g. due to a local soil irregularity, the transmitter 453b detects the acceleration of the row sowing entity 2, and the control entity 451 is adapted through integration of signals from the transmitter 453b to calculate the vertical velocity of the row sowing entity 2, and thereby that of the seed metering device 8. It should be noted that the movement determining means can alternatively comprise a combination of a position detector 453 a, e.g. of the type described above, and a transmitter of acceleration measurement 453b. The position detector 453a can thereby be used to eliminate residual errors at integration of values from the transmitter for acceleration measurement 453b.

On the basis of the signals from the movement determining means 453a, 453b the control entity 451 controls the drive unit 401 so that the velocity of this deviates from the velocity which is determined on the basis of the signals from the velocity determining means 452a, 452b, in such a way that the rotational speed of the seed metering element (Fig. 3, #803) increases at an upward-directed relative movement of the seed metering device 8, and the rotational speed of the seed metering element (Fig. 3, #803) decreases at a downward-directed relative movement of the seed metering device 8.

In the embodiments described above, viewed in the intended direction of travel F of the agricultural machine, the seed metering axle 805 is disposed behind the primary axis of rotation 414. However within the framework of the invention the agricultural machine can be arranged so that, viewed in the intended direction of travel F of the agricultural machine, the seed metering axle 805 is disposed in front of the primary axis of rotation 414.

Claims

1. An agricultural machine comprising at least one seed metering device (8) for distributing seeds to soil (9) over which the agricultural machine (1) moves, wherein the seed metering device (8) is connected to a structural member (3), being a part of the agricultural machine, in such a way that the seed metering device (8) is moveable at least partly vertically in relation to the structural member (3), in addition to which the seed metering device (8) comprises a seed metering element (803) which by means of a drive device (401) is rotatable around a seed metering axle (805) and adapted to, at a distance from the seed metering axle (805), take and release seeds (91), characterised in that the drive device (401) is adapted to increase the rotational speed of the seed metering element (803) at an upward-directed relative movement of the seed metering device (8), and to decrease the rotational speed of the seed metering element (803) at a downward-directed relative movement of the seed metering device (8).

2. An agricultural machine according to Claim 1, wherein the seed metering element is (803) adapted to release seeds (91) in a release region (SL), and the drive device (401) and the seed metering device (8) are arranged so that a vertical component of an increase and decrease, respectively, of the velocity of the seed metering element (803) in the release region (SL), corresponding to the increase and decrease, respectively, in rotational speed of the seed metering element (803), is 26-75% of the vertical component of the velocity of the seed metering device (8) at the upward-directed relative movement and downward- directed relative movement, respectively.

3. An agricultural machine according to Claim 2, wherein the drive device (401) and seed metering device (8) are arranged so that the vertical component of the increase and decrease, respectively, of the velocity of the seed metering element (803) in the release region (SL), corresponding to the increase and decrease, respectively, in rotational speed of the seed metering element (803), is 36-72% of the vertical component of the velocity of the seed metering device (8) at the upward-directed relative movement and downward-directed relative movement, respectively.

4. An agricultural machine according to any one of Claims 1-3, wherein the drive device (401) comprises a primary drive member (411) which displays at least one primary axis of rotation (414, 415) the position of which in relation to the structural member (3) is constant, - in addition to which the at least one primary axis of rotation (414, 415) is orientated primarily perpendicularly to the intended direction of travel (F) of the agricultural machine (F) and primarily horizontally,

- in addition to which the drive device (401) comprises at least one secondary drive member (421, 431, 443) adapted to be driven, directly or indirectly, by the primary drive member (411) and to drive, directly or indirectly, the seed metering element (803).

5. An agricultural machine according to Claim 4, wherein the primary drive member (411) comprises a primary drive wheel (411), and one of the secondary drive members (421) is a seed metering drive wheel (421) which is fixedly connected to the seed metering element (803) and concentric with the seed metering axle (805) and is adapted to be driven by the primary drive member (411) via at least one additional secondary drive member (443).

6. An agricultural machine according to Claim 5, wherein at least one of the at least one additional secondary drive member (443) comprises an endless flexible member (443).

7. An agricultural machine according to Claim 6, wherein the drive device (401) is arranged so that a path angle (α) between an angled part (443 a) of the path for the endless flexible member (443), at which angled part (443a) of the path the endless flexible member (443) is adapted to be driving, and the direction (RB) for a movement of the seed metering device (8) in relation to the structural member (3) is less than 90 degrees.

8. An agricultural machine according to Claim 7, wherein the drive device comprises a breakwheel (418) which is adapted to be in engagement with the endless flexible member (443) at one end of the angled part (443a) of its path, in addition to which the position of the axis of rotation for the breakwheel (418) is fixed in relation to the seed metering axle (805).

9. An agricultural machine according to any one of Claims 7-8, wherein the drive device comprises a chain tensioner (417) which is adapted to be in engagement with the endless flexible member (443) at a part of its path at which it is not driving.

10. An agricultural machine according to any one of Claims 4-9, wherein the drive device (401) is arranged so that the primary drive member (411), at metering of seeds from the seed metering device (8), at least in an engagement region (IO) for engagement with at least one of the secondary drive members (421 , 431 , 443), rotates in righthand revolution viewed from the left in the intended direction of travel (F) of the agricultural machine.

11. An agricultural machine according to Claim 10, wherein the primary drive member (411) comprises a primary drive wheel (411).

12. An agricultural machine according to Claim 10, wherein the primary drive member (411) comprises an endless flexible member (411).

13. An agricultural machine according to Claim 12, wherein the endless flexible member is adapted to, in the engagement region (IO) for engagement with at least one of the secondary drive members (421), run primarily parallel with a direction in which the seed metering device (8) is moveable in relation to the structural member (3).

14. An agricultural machine according to any one of Claims 10-13, wherein one of the secondary drive members (421) is a seed metering drive wheel (421) which is fixedly connected to the seed metering element (803) and concentric with the seed metering axle (805) and is adapted to be driven by the primary drive member (411) via at least one additional secondary drive member (431, 443).

15. An agricultural machine according to any one of the preceding claims, wherein the drive device (401) comprises a drive unit (401), in addition to which the agricultural machine also comprises an electronic control entity (451), velocity determining means (452a, 452b) adapted to send to the control entity (451) signals which indicate the velocity of the agricultural machine, and movement determining means (453a, 453b) adapted to send to the control (451) signals which indicate movements of the seed metering device (8), in addition to which the control entity (451) is adapted to control the drive unit (401) at least partly on the basis of the signals from the velocity determining means (452a, 452b) and the movement determining means (453a, 453b).