Patent Application
20180343802
This application is related to Italian Patent Application No. 102015000021005 filed on Jun. 5, 2015, the disclosure of which is incorporated by reference.
The present invention relates to a star-wheel rake.
As is known, rakes are used in farming for turning over forage after cutting and accumulating the processed material in rows, normally referred to as windrows.
One of the commonly used rakes is the star-wheel type.
A star-wheel rake comprises a plurality of rakes or star wheels, which are idly mounted on a frame about respective parallel axes and, in practice, form rotating rakes. The rake wheels, with the same diameter, are oblique with respect to a direction of travel in the working configuration and are set in rotation by contact with the ground during the forward travel of the rake. Each rake wheel is equipped with an outer ring of coplanar teeth, shaped to collect the forage and move it sideways due to the combine effect of the rake advancing in the direction of travel and the rotation of the rake wheel about the respective axis. Furthermore, the rake wheels are placed side by side so that the forage moved from the more forward wheels with respect to the direction of travel is collected by the more rearward adjacent wheels. In this way, the rake wheels define a working front and move the forage collected on the working front during forward movement towards a discharge side of the rake, where a windrow is formed. The upstream (more forward) wheels along the working front can partially overlap the immediately adjacent more downstream (more rearward) wheels, to avoid losing the material being processed.
Star-wheel rakes have the advantage of a very simple structure, which does not require specially provided drives for the rake wheels. As already mentioned, the rake wheels are actually idle and rotate due the effect of contact of the teeth with the ground during forward movement. Star-wheel rakes are therefore inexpensive and relatively immune to malfunctioning, and this makes their use fairly widespread.
However, the same mechanism that drives the rake wheels, also causes soil and dust to be raised, which mixes with the collected forage and accumulates in the windrows. Dirt in the forage is obviously unwelcome, because it may interfere with the aeration and drying process and, in general, degrades the quality of the product. Thus, on one hand, star-wheel rakes are inexpensive and good value for money, but on the other, the results they provide are often unsatisfactory.
The object of the present invention is therefore to provide a star-wheel rake that enables overcoming or at least mitigating the described limitations and, in particular, allows significantly reducing the accumulation of dirt in the windrows.
According to the present invention, a star-wheel rake is provided as defined in 1.
The present invention will now be described with reference to the accompanying drawings, which illustrate some non-limitative embodiments, in which:
Referring to
In the example shown, the frame 2 comprises a support bar 5 and a drawbar 6. The support bar 5 extends transversely in a travel direction D of the rake 1 in the working configuration and supports the raking units 3 in a rotational manner.
The drawbar 6 has a first end fastened to the support bar 5 and a second end fitted with a three-point hitch 7 for connection to a means of transport, for example a tractor 8 (partly and schematically shown only in
In the embodiment shown here, the rake 3 is adapted to be carried by the tractor 8 and therefore it has no support wheels. Nevertheless, it is understood that the rake could still be towed, in which case the frame could be provided with one or more support wheels.
Each raking unit 3 comprises a front rake wheel 10 and a rear drive wheel 11. It is understood that hereinafter the terms “front” and “rear” and their derivatives are with reference to the travel direction D in the working configuration. For example, the front end of the drawbar 6 carries the three-point hitch 7, while the rear end is fastened to the support bar 5.
The front rake wheels 10 may be conventional rake wheels (also known as star wheels). In particular, the front rake wheels 10 are substantially planar and are provided with respective outer rings of teeth 10a, shaped so as to collect the forage and move it sideways during forward movement of the rake 1.
The rear drive wheels 11 may be of the same type as the front rake wheels 10, of a different size in the embodiment described and illustrated herein. In this case, in use, the teeth 11a are in contact with the ground to set the rear drive wheels 11 in rotation when the rake proceeds in the travel direction D.
The front rake wheels 10 and the rear drive wheels 11 of the rake 1 are mounted on the frame 2 with respective parallel rotation axes.
The front rake wheel 10 and the rear drive wheel 11 of each raking unit 3 are coupled to each other such that the rotation of the rear drive wheel 11, due to the effect of contact with the ground during forward movement, causes rotation of the front rake wheel 10. Furthermore, the two wheels are arranged such that the front rake wheel 10 is raised when the rear drive wheel 11 is in contact with the ground.
In one embodiment, the front rake wheel 10 and the rear drive wheel 11 of each raking unit 3 (except for a raking unit 3a placed at a discharge side of the rake 1) are coaxial and angularly fixed with respect to each other, even though idly mounted as a whole on the frame 2. For example, the front rake wheel 10 and the rear drive wheel 11 are mounted on a same hub 14, which is in turn fitted on a respective shaft 15 fastened to the frame 2. Furthermore, the front rake wheel 10 has a smaller diameter D1 than the diameter D2 of the rear drive wheel 11.
In the raking unit 3a on the discharge side of the rake 1, the front rake wheel 10 and the rear drive wheel 11 have respective parallel and separate rotation axes. In particular, the rotation axis of the rear drive wheel 11 of the raking unit 3a is offset with respect to the rotation axis of the front rake wheel 10 and displaced towards the adjacent raking unit 3. In practice, with respect to a direction of flow of the processed forage, the rotation axis of the rear drive wheel 11 of the raking unit 3a is displaced upstream with respect to the rotation axis of the front rake wheel 10. In one embodiment, the connection between the front rake wheel 10 and the rear drive wheel 11 of the raking unit 3a is obtained by a double cardan joint 12. Alternatively, it is possible to use other transmission means, such as a crown and pinion coupling or a belt coupling. Furthermore, the rear drive wheel 11 of the raking unit 3a is arranged at the rear of the support bar 5 of the frame 2, while all the other wheels 10, 11 are arranged at the front. In a different embodiment, not shown, the rear drive wheels 11 of all the raking unit 3a are arranged at the rear of the support bar 5 of the frame 2.
The rotation axes of the front rake wheels 10 and of the rear drive wheels 11 are parallel to each other and oblique with respect to the travel direction D of the rake 1 in the working configuration. The front rake wheels 10 are arranged side by side and partially overall each other and define a working front, between the discharge side (where raking unit 3a is positioned) and an upstream side opposite to the discharge side, and a flow direction F along the working front from the upstream side towards the discharge side. The rake wheels 10 that are more upstream with respect to the flow direction F are arranged in front of rake wheels 10 immediately downstream, so as to facilitate collection of the forage.
In one embodiment in particular, the front rake wheel 10 of each raking unit 3 has a respective portion interposed between the front rake wheel 10 and the rear drive wheel 11 of the respective adjacent upstream raking unit 3. Similarly, the rear drive wheel 11 of each raking unit 3 has a respective portion interposed between the front rake wheel 10 and the rear drive wheel 11 of the respective adjacent downstream raking unit 3.
In use, the rake 1 is connected to the tractor 8 via a three-point hitch 7 and is carried at a height such that the rear drive wheels 11 of the raking units 3 are in contact with the ground. The rear drive wheels 11 rotate due to the combined effect of moving forward in the travel direction D and of contact with the ground, causing the respective front rake wheels 10 to be driven in rotation. The forage is collected by the front rake wheels 10 along the working front and moved along the flow direction F to the discharge side, where a windrow is formed. The front rake wheels 10, having a smaller diameter with respect to the rear drive wheels 11, are raised above the ground and do not raise dirt when working. Obviously, the contact of the rear drive wheels 11 with the ground raises dirt and soil, which however cannot mix with the forage transferred by the front rake wheels 10 due to the forward movement of the rake 1 in the direction of travel. Furthermore, the rear drive wheel 11 of the raking unit 3a is offset towards the inside of the working front with respect to the corresponding front rake wheel 10 and can discharge the dirt at a certain distance from the windrow without mixing it with the forage.
The rake 1 thus has the advantages of star-wheel rakes (in particular the simple structure and low costs) and, in addition, enables drastically reducing contamination of the forage with dust, soil and other dirt.
The fact of having separate wheels for driving force and for forage collection also allows greater freedom in the design of the rake. For example, the rear drive wheels could have different characteristics with respect to the front rake wheels and be specifically designed to improve rolling and reduce dust cloud formation. The front rake wheels could instead be optimized for the collection and transfer of forage.
According to the embodiment shown in
Furthermore, the front rake wheels 310 are coupled to the rear drive wheel 311 such that the rotation of the rear drive wheel 311, due to the effect of contact with the ground during forward movement, causes rotation of all the front rake wheels 310 of the raking unit 303. In one embodiment in particular, the rear drive wheel 311 is rigidly coupled to one of the front rake wheels 310 and the front rake wheels 310 are coupled to each other, for example by drive belts 312. Advantageously, the front rake wheel 310 rigidly coupled to the rear drive wheel 311 is not the one positioned on the discharge side of the rake 300, to avoid contamination of the forage collected in the windrow. However, in an embodiment not shown, the rear drive wheel can transmit drive to the front rake wheel on the discharge side by drive members that allow offsetting the rotation axes, so that the rear drive wheel can be distanced from the discharge side, as in the raking unit 3a in
In an embodiment that is not shown, a star-wheel rake may comprise a plurality of raking units arranged side by side to form a working front and each having a plurality of front rake wheels (for example, two or three) coupled to a same rear drive wheel.
Finally, it is clear that modifications and variants can be made to the described rake, without departing from the scope of the present invention, as defined in the appended claims.
