EP2207411A1

EP2207411A1 - Agricultural machine

Info

Publication number: EP2207411A1
Application number: EP08825889A
Authority: EP
Inventors: Alfonsus Jacobus Van Den Engel
Original assignee: Lely Patent NV
Current assignee: Lely Patent NV
Priority date: 2007-11-05
Filing date: 2008-10-03
Publication date: 2010-07-21
Anticipated expiration: 2028-10-03
Also published as: EP2207411B1; NL1034635C2; WO2009061176A1

Abstract

The invention relates to an agricultural machine comprising a frame (2) which is arranged to be connected to a pulling vehicle, two or more processing members (5), which are rotatably attached to the frame (2), and a driving device for driving the processing members (5) in a rotating manner, wherein the driving device comprises a main drive shaft (10), two drive shafts (14a, 14b) which are each arranged to drive one or more of the two or more processing members (5), and two drive couplings (12), wherein each of the two drive couplings connects the main drive shaft (10) to one of the two drive shafts (14a, 14b). The invention is characterized in that at least one of the drive couplings comprises at least one torsion element (17) which is arranged to allow a certain angular rotation between the drive shafts 14a, 14b.

Description

Agricultural machine

The invention relates to an agricultural machine according to the preamble of claim 1. Such a construction of an agricultural machine is, for example, used with a mower, tedder or rotary harrow.

In general, in agriculture there is a trend to enlarge the machines in use in order thus to enable a more efficient agricultural operation on a piece of land. With agricultural machines comprising rotating processing members this leads typically to an increasingly larger working width, and an increasing number of processing members being arranged in one row.

During processing ground or a crop which is lying on the ground it is possible that one of the processing members gets stuck on an obstacle, for example a pole, tree or big stone. It will then suddenly no longer be possible for the relevant processing member to rotate, while it is still being driven by the drive shaft. As a result thereof, the load which is exerted on the drive mechanism of the agricultural machine will suddenly increase quickly, resulting in a great risk of damage of the drive. In particular, there is a great risk of the tine wheels of a transmission being damaged as a result of a too great load.

It is known to place a slip coupling on the main drive mechanism of a haymaking machine in order to disconnect, at such a suddenly increasing load, the drive mechanism from the driving source, for example the motor of a tractor, in order to limit the maximum load and thus to prevent damage of the drive mechanism.

However, in particular in the case of larger agricultural machines, in which a larger number of processing members are rotating simultaneously, the mass moment of inertia of the driving device and the processing members is accordingly greater. Suddenly stopping such a large mass which is interconnected via the drive mechanism may still provide a momentary load which may lead to damage of the drive mechanism. In order to prevent the drive mechanism from being damaged, it would be possible, by means of a slip coupling or the like, to disconnect only the blocked processing member from the drive mechanism at a great load, so that the other processing members will be free to continue to rotate. However, this is only possible if the paths of movement of the processing members do not overlap. However, in a number of uses, such as in the case of a mower, tedder or rotary harrow, the paths of movement of the processing members overlap. For example, in the case of a tedder, each of the processing members usually comprises arms with tines fastened thereto. The arms are arranged relative to each other in such a manner that the arms of adjacent processing members rotate between each other. The processing members thus have overlapping paths of movement and should, therefore, be moved synchronously.

If, in such an agricultural machine, only the processing member which is suddenly blocked is disconnected, the arms of the adjacent processing member will run into the arms of the blocked processing member. This may lead to damage of the arms, for example serious deformation or breakage of the arms. In such an agricultural machine, such a disconnection of a single processing member is therefore unwanted.

EP 1 258 187 A2 discloses a drive mechanism for agricultural machines comprising a main drive shaft, two drive shafts each for driving a group of processing members and two drive couplings which each interconnect the main drive shaft and one of the drive shafts. Each drive coupling comprises its own slip coupling. A catching device is provided between the drive shafts. The catching device is a device to allow a maximum angular rotation between the two drive shafts and consequently the groups of processing members.

When one of the processing members is blocked by an obstacle, the relevant group of processing members is completely blocked and disconnected from the drive mechanism by means of the slip coupling. However, the other group of processing members continues to rotate until the catching device does not allow further relative rotation because a maximum angular rotation has been reached. Consequently, also the second group of processing members will be blocked. By using this drive mechanism, the processing members will not be stopped in one go, but in two phases. As a result thereof, the peak load will also be spread over two moments. A drawback of this drive mechanism is that two peak loads still occur in the system. Another drawback is that after one group of processing members has rotated relative to the other group of processing members, these members should be manually brought back into their initial positions. This extra action should be performed accurately, because an incorrect positioning of the processing members relative to each other may result in a worse functioning of the agricultural machine and also in an increased risk of damage when one of the processing members is blocked again.

DE 202007008591 U1 discloses a drive mechanism for agricultural machines which is based on the drive mechanism according to EP 1 258187 A2.

In this alternative drive mechanism, each drive coupling comprises an overload coupling, as in the drive mechanism of EP 1 258187 A2. However, instead of the catching device, there is provided a rotation-elastic spring element between the drive shafts. When one of the processing members is blocked, all processing members will be stopped as with the drive mechanism of EP 1 258187 A2.

However, the peak loads will be damped by the rotation-elastic spring element between the drive shafts.

The invention aims at providing an alternative drive mechanism for an agricultural machine, which reduces the risk of damage of the drive mechanism or processing members when one of the processing members suddenly gets stuck.

This object is achieved by means of an agricultural machine comprising: a frame which is arranged to be connected to a pulling vehicle, - two or more processing members which are rotatably attached to the frame, and a driving device for driving the processing members in a rotating manner, wherein the driving device comprises: a main drive shaft, - two drive shafts which are each arranged to drive one or more of the two or more processing members, and two drive couplings, wherein each of the two drive couplings connects the main drive shaft to one of the two drive shafts, characterized in that at least one of the drive couplings comprises at least one torsion element which is arranged to allow a certain angular rotation between the drive shafts.

A torsion element is an element which is capable of storing mechanical energy when it is distorted. By providing a torsion element between the two drive shafts, in the case of blocking of one of the processing members, the mechanical energy of a group of rotating processing members positioned at the other side of the torsion element is at least partially absorbed by the torsion element. The processing members are thus slowed down. This results in a lower momentary load of the drive mechanism and a reduced risk of damage/overload of the drive mechanism.

It is pointed out that, owing to the presence of the rotation-elastic spring element, the drive mechanism of DE 202007008591 IM also has a damping effect on the peak loads which result from a complete blockage of one of the processing members. However, this drive mechanism requires the presence of two extra overload couplings in the drive mechanism. In the system according to the present invention, these overload couplings are not required, because the torsion element is provided in the drive coupling between the main drive shaft and the respective drive shaft.

In this patent application, the term "drive coupling" is used to designate all elements which are disposed in the drive line between the main drive shaft and the drive shaft which drives the processing members. These elements may, for example, comprise gearboxes, shafts, and other drive elements, as well as a torsion element according to the present invention.

It is pointed out that a drive mechanism typically comprises elongate elements, such as shafts, which allow, by nature, a certain torsion. Distortion of such elements is generally unwanted. In this application, by the term torsion element is meant an element which is built-in in order to allow, on the contrary, torsion in the drive mechanism. The torsion element will typically have a substantially lower torsion rigidity than the other elements of the drive mechanism. The torsion element may also be used in an embodiment in which the paths of movement of the processing members overlap. Although it is not possible for the processing members to rotate freely relative to each other, there is usually room to make the processing members rotate relative to each other over a limited angle without adjacent processing members coming into contact with each other. This free angle of rotation may be used to have mechanical energy absorbed by the torsion element.

A torsion element has the additional advantage of elastically deforming during the distortion. As a result thereof, when the processing members are free to rotate relative to each other, by the elasticity of the torsion element the processing members will automatically be repositioned in their initial positions relative to each other. This initial position is preferably the position in which the processing member has a maximum free angle of rotation in both directions of rotation. If there is provided a speed reduction between the drive shaft and the rotating processing members, the free angle of rotation at the drive coupling may be greater than at the processing members. This has the advantage that there is more angular rotation available which may be used for damping the movement of the processing members. In one embodiment, the two drive shafts are in alignment and, between the two drive shafts, there is disposed an angle limiting device in order to limit a maximum angular rotation between the two drive shafts. In order to limit the maximum angular rotation between the two drive shafts, there may be provided an angle limiting device which prevents the relative rotation between two adjacent processing members from becoming greater than the free angle of rotation.

In one embodiment, the main drive shaft comprises a slip coupling. A torsion element being provided makes it possible to absorb peak loads. In order to prevent damage due to constant load there may be provided a slip coupling which limits the maximum constant load on the processing members. The invention will hereinafter be explained in further detail on the basis of an exemplary embodiment, under reference to the accompanying drawing in which:

Figure 1 shows a top view of an agricultural machine according to the invention; - Figure 2 shows a side view of the agricultural machine of Figure 1 , and

Figures 3 and 4 are a detailed view of part of the drive mechanism according to the invention.

Figures 1 and 2 show a tedder denoted as a whole by the reference numeral 1. The tedder comprises a frame 2 having a front end which is arranged to be coupled to a pulling vehicle in order to be pulled in the direction of travel R. Near the rear end of the frame 2 there is provided a wheel set 3 for supporting the frame 2. At the rear end of the frame 2 there are disposed two supporting arms 4 which extend at opposite sides of the frame 2. Each of the supporting arms 4 supports eight rotatable processing members 5. The processing members 5 comprise a number of arms 6 having a number of tines 7. A drive mechanism 8 is provided for driving the processing members 5 in a rotating manner. The supporting arms 4 are arranged to be folded in to a transport position in which the supporting arms 4 with the processing members 5 will be located on the supports 9. There is provided a hydraulic circuit with actuators for folding in the supporting arms 4 to the transport position and folding them out to the operative position.

The drive mechanism 8 comprises a main drive shaft 10, one end of which is arranged to be connected to a driving source, and another end of which is connected to a gearbox 11. The gearbox 11 is further operatively connected to two drive couplings 12 which are each connected, via a first transmission 13, to a drive shaft 14a, 14b. Each drive shaft 14a, 14b comprises for each of the eight processing members 5 a second transmission 15 and a shaft 16 by means of which the relevant processing member 5 is drivable in a rotating manner.

The processing members 5 rotate in overlapping paths of movement relative to the adjacent processing members 5. The processing members 5 are driven alternately in opposite directions of rotation so that the arms 6 having tines 7 of different processing members 5 will not run into each other during rotation. Despite of the overlapping paths of movement the processing members 5 do have a free angle of rotation, i.e. an angle over which a processing member 5 can rotate relative to an adjacent processing member 5 without abutting against the adjacent processing member 5. This free angle of rotation depends on the design of the processing members 5. For example for a rotary harrow having two arms per processing member, the free angle of rotation may be 90 degrees at the most in both directions. In one embodiment of a tedder as shown in Figures 1 and 2, this free angle of rotation of the processing members 5 is between 5 degrees and 20 degrees, for example 10 degrees, in both directions.

It is pointed out that the free angle of rotation is in particular important for the two middle processing members 5, because these are driven by different drive shafts 14.

Since the second transmission 15 has a speed reduction of approximately a factor three of the drive shaft 14a, 14b to the shaft 16, a free angle of rotation of 10 degrees for the processing members 5 is a free angle of rotation of 30 degrees for the drive shafts 14 relative to each other.

According to the invention, it is possible to use this free area of rotation to damp the movement of the processing members if one of the processing members is blocked. For this purpose, the connection of each of the drive couplings 12 to the first transmission 13 comprises a torsion element 17 which allows a certain torsion. The torsion element 17 is a flexible element which is capable of absorbing a mechanical energy by rotation of the torsion element 17. The torsion element may be any suitable flexible element such as a block or (open) cylinder made of a resilient material, such as rubber, or a torsion spring or a torsion bar.

In alternative embodiments, the torsion element 17 may be accommodated in the drive coupling 12 or at the other end of the drive coupling 12. By providing the torsion element 17, the mechanical energy which is present in the processing members as a result of the moment of inertia may be included in the torsion element 17.

If one of the crop processing members 5 of a first one of the drive shafts 14a is now completely blocked, for example by a tree or pole, all the crop processing members 5 on this first drive shaft 14a will be blocked immediately. However, the crop processing members 5 on the other drive shaft 14b are connected, via the drive couplings 12 and thus the torsion elements 17, to the blocked crop processing members 5, and due to the fact that the torsion elements absorb the movement, the movement of the group of processing members 5 on the second drive shaft will not be stopped suddenly but will be damped by the torsion elements 17.

Because the damping is based on an elastic deformation of the torsion elements 17, the crop processing members 5 will be brought back by spring action into their initial positions, after the rotation in which the movement is damped. It is thus not necessary manually to bring back the crop processing members to their initial positions.

The torsion elements 17 are preferably dimensioned in such a manner that at a maximum peak load, for example a sudden complete blockage of a crop processing member 5, a considerable part of the inertia of the crop processing members 5 of the other drive shaft can be damped in the free area of rotation of the crop processing members.

In order to be sure that the crop processing members will rotate, relative to each other, not further than the maximum free angle of rotation, there is provided an angle limiting device 18 which allows a maximum relative rotation of one drive shaft 14b relative to the other one 14a. This angle limiting device 18 is shown in more detail in Figures 3 and 4. The angle limiting device 18 comprises a first portion 19 which is coupled to the first drive shaft 14a and a second portion 20 which is coupled to the second drive shaft 14b. The first portion 19 comprises a pin 21 which is inserted in a slot 22 provided in the second portion 20.

The first portion 19 and the second portion 20 are shown in their initial positions in which they have a maximum free angle of rotation in both directions. In the embodiment shown this is 30 degrees in both directions. It is thus possible for the pin 21 to move through the slot 22 over 30 degrees in both directions before it abuts against the end of the slot 22 and is no longer able to rotate in the relevant direction.

Consequently, if the crop processing members 5 of a first drive shaft 14a are blocked, the torsion elements 17, by distortion, will at least partially damp the movement of the crop processing members of the second drive shaft 14b. As a result of the torsion, the first drive shaft 14a will rotate relative to the second drive shaft 14b. When the angular rotation between the first drive shaft 14a and the second drive shaft 14b amounts to 30 degrees, the pin 21 will abut against the end of the slot 22 and not allow a further relative rotation of the drive shafts 14a, 14b.

As a result thereof, the crop processing members 5 will also be blocked. The resulting peak load will be substantially smaller because a part of the mechanical energy is absorbed in the torsion elements 17. Subsequently, owing to the elastic energy of the torsion elements 17, the processing members will rotate in opposite direction until they return, possibly after some fluctuations, into their initial points, as shown in Figures 3 and 4. As already pointed out, there is thus no manual action needed to bring the crop processing members 5 into their desired positions relative to each other.

The maximum relative rotation of the first drive shaft 14a relative to the second drive shaft 14b is 30 degrees. This means that, if the first transmission 13 is a 1 :1 transmission, at equal torsion elements 17, each of the torsion elements 17 can absorb an angular rotation of 15 degrees. In practice, the first transmission will often also be an inertial transmission, so that the available torsion angle will be greater for each of the torsion elements 17.

In alternative embodiments, it is also possible to provide more or fewer torsion elements 17 between the drive shafts 14. The embodiment shown in the drawing has two drive shafts separated by means of torsion elements 17. It is further possible to provide more than two drive shafts between which one or more torsion elements are provided.

Claims

1. Agricultural machine comprising: a frame (2) which is arranged to be connected to a pulling vehicle, - two or more processing members (5) which are rotatably attached to the frame (2), and a driving device for driving the processing members (5) in a rotating manner, wherein the driving device comprises: a main drive shaft (10), - two drive shafts (14a, 14b), which are each arranged to drive one or more of the two or more processing members (5), and two drive couplings (12), wherein each of the two drive couplings connects the main drive shaft (10) to one of the two drive shafts (14a, 14b), characterized in that at least one of the drive couplings comprises at least one torsion element (17) which is arranged to allow a certain angular rotation between the drive shafts (14a, 14b).

2. Agricultural machine according to claim 1 , wherein both drive couplings (12) comprise a torsion element (17).

3. Agricultural machine according to claim 1 or 2, wherein the torsion element (17) is disposed at a connection between the drive shaft (14a/b) and the drive coupling (12) and/or at a connection between the drive coupling (12) and the main drive shaft (10).

4. Agricultural machine according to any one of claims 1-3, wherein the two drive shafts (14a, 14b) are in alignment and, between the two drive shafts (14a, 14b), there is disposed an angle limiting device (18) in order to limit a maximum angular rotation between the two drive shafts (14a/b).

5. Agricultural machine according to any one of claims 1-4, wherein the torsion element (17) comprises a torsion spring or torsion bar.

6. Agricultural machine according to any one of claims 1-5, wherein the main drive shaft (10) comprises an overload coupling.

7. Agricultural machine according to any one of claims 1-6, wherein the agricultural machine comprises a first group of eight processing members (5) which are driven by a first drive shaft (14a), and a second group of eight processing members (5) which are driven by a second drive shaft (14b).

8. Agricultural machine according to any one of claims 1-7, wherein a speed reduction is provided between the drive coupling (12) and the respective processing member (5).

9. Agricultural machine according to any one of claims 1-8, wherein the drive coupling (12) comprises a telescopic coupling.