WO2011073773A1

WO2011073773A1 - Protection device for bush-cutters and corresponding bush-cutter

Info

Publication number: WO2011073773A1
Application number: PCT/IB2010/003258
Authority: WO
Inventors: Dennis Serafin
Original assignee: Serafin Luigi & C. S.N.C
Priority date: 2009-12-16
Filing date: 2010-12-15
Publication date: 2011-06-23
Also published as: IT1398213B1; ITVI20090294A1

Abstract

The present invention concerns a protection device (2; 102) for bush cutters comprising a guide rod (8), a head (10) provided with a rotatable cutting tool (12) that during rotation defines a substantially circular cutting plane (18), a motor suited to operate the cutting tool (12), wherein the protection device (2; 102) comprises a coupling (6; 106) suited to fix it to the bush cutter. The protection device (2; 102) is carried out as a guard (4; 104) with a substantially flat base surface that, when installed on the bush cutter, mainly extends along the axis of the rod (8) inclined by an angle (α) with respect to the cutting plane (18). Furthermore, the perimeter of the base surface describes, at least partially at the level of the radial portion and, in the axial direction (Y), at the level of the front perimeter portion of the cutting plane (18), an arc (β) that coincides with or slightly projects beyond the perimeter of the cutting plane (18), wherein the arc (β) is provided at least on part of its extension with a downward folded edge (16; 116) suited to cover the front perimeter portion of the cutting plane (18) in the axial direction (Y).

Description

PROTECTION DEVICE FOR BUSH-CUTTERS AND CORRESPONDING

BUSH-CUTTER.

DESCRIPTION

Technical field of the invention

The present invention concerns a protection device for bush cutters comprising a guide rod, a head provided with a rotatable cutting tool that during rotation defines a substantially circular cutting plane, a motor suited to operate said cutting tool, wherein the protection device comprises a coupling that allows it to be fixed to said bush cutter. The invention also concerns a corresponding bush cutter.

State of the art

Bush cutters are tools that are used for cutting grass, brushwood, bushes and young tree trunks, as well as for cleaning undergrowth.

A typical bush cutter is portable and comprises a rod that is used to handle it, usually provided with a corresponding grip, and a head provided with a cutting tool that can be operated via a motor with a corresponding torque.

Cutting tools are mainly divided into two categories, that is, tools provided with a cutting wire and tools provided with a cutting blade, often in the shape of a disc.

Bush cutters are not used on large surfaces, but are usually employed to finish small areas that are difficult to access for normal lawn mowers, like for example the perimeter areas of poles, trees, walls, pavements etc. They are also used for areas where grass or other types of vegetation is/are too high and does/do not allow a lawn mower to pass therethrough.

The market offers a wide range of bush cutters that in most cases are also provided with a rear gravel guard intended to protect the operator from stones, pieces of plants or other objects projected by the cutting tool while it rotates. During use of the bush cutter, however, the guard does not prevent the front portion of the bush cutter from representing a danger for third parties, animals, plants or objects, which may be damaged or injured by the cutting tool. Furthermore, objects may be projected in front of or beside the operator, also in this case with the risk of hitting objects or people.

Finally, free access to the cutting tool from the front may cause untimely wear of or undesired damage to the cutting tool.

Description of the invention It is the object of the present invention to provide a protection device and a corresponding bush cutter that overcome the drawbacks described above. In particular, it is one object of the present invention to propose a protection device suited to protect both third parties and objects from the cutting tool, and the cutting tool itself from excessive wear and/or damage.

The objects illustrated above are achieved by a protection device for bush cutters comprising a guide rod, a head provided with a rotatable cutting tool that during rotation defines a substantially circular cutting plane, a motor suited to operate said cutting tool, wherein the protection device includes a coupling suited to fix it to said bush cutter and is characterized in that said protection device, when installed on the bush cutter, is suited to cover at least partially the radial portion and in the axial direction the front perimeter portion of said cutting plane.

The expression "protection of the perimeter portion in the axial direction" means a protection that extends following the perimeter also in the direction of the rotation axis of the cutting tool that defines the cutting plane.

A device of the type described above makes it possible to protect third parties, animals and objects from the cutting portion and, on the other hand, the cutting portion is protected from wear or damage due to any accidental contact with poles, walls etc. Obviously, the larger the portion of the perimeter guarded by the protection device, the higher the degree of protection provided. Excessive protection may negatively affect the manoeuvrability of the bush cutter. If the protection device covers at least partially also the radial portion of the cutting plane, this prevents even more the projection of stones or other objects that, for example, may injure/damage people or machines.

The cutting tool may for example be a wire but even a blade.

According to a preferred variant embodiment of the invention, the protection device is carried out as a guard with a substantially flat base surface that, when the device is installed on the bush cutter, mainly extends along the axis of the rod, inclined by a given angle with respect to the cutting plane. Furthermore, at least in the area that covers the front perimeter portion of the cutting plane when the device is installed on the bush cutter, the perimeter of the above mentioned base surface describes an arc that coincides with or slightly projects from the perimeter of the cutting plane itself; at least on part of its extension said arc features an edge folded downwards and suited to cover the front perimeter portion of the cutting plane along its axial direction.

When installed on the bush cutter, the guard follows the rod along its extension and covers a radial portion of the cutting plane or, in other words, the projection of the guard on the cutting plane coincides with at least part of the radial portion of the cutting plane.

Gravel or other objects projected upwards by the cutting tool can thus be stopped by the guard that is located above the radial portion of the cutting plane. Moreover, a guard is very simple to construct and therefore reduces production costs.

An arc that practically imitates the delimitation of the cutting plane and coincides with it or projects from it only slightly guarantees that the cutting tool can be brought very near walls, poles, trunks etc without coming into contact with them and thus making it possible to cut the grass even near them. The downward folded edge, which practically guards the movement of the wire or rotating blade, prevents the contact of the latter with people, animals or objects.

In order to allow the operating range of the cutting tool to be exploited to the highest degree, the arc should be selected so that it coincides with the perimeter of the cutting plane and the entire protection device should be located slightly above the wire in order to allow the latter to work up to the limit of the protection device.

Alternatively, in order to better cover the wire or the blade, it is preferable for the arc to project from the cutting plane, and for the protection device to be more or less at the height of the rotating cutting tool.

In this last case the grass, which is very near obstacles like walls and poles, is not cut to the degree determined by the extension of the projection of the edge beyond the cutting plane.

The rod is generally straight. It is installed so as to be inclined with respect to the cutting plane in order to facilitate work. An angle of inclination of approximately 30° has proven to be very useful.

The fact that the configuration of the guard towards the back follows the inclination of the rod creates a space between the protection device and the cutting plane, in this way avoiding the accumulation of cut grass under the protection device and preventing the grass from clogging the cutting tool. The cut grass may also be projected laterally. According to an advantageous variant embodiment of the invention, the part of said guard limited by the arc is slightly lifted with respect to the plane formed by said base surface.

This configuration makes it possible to arrange the front portion of the protection device so that it is parallel to the surface to be cut and therefore to the cutting plane, thus guarding the front portion of the cutting plane in an optimal way and moving the guard near the radial portion of the same cutting plane.

Advantageously, said arc describes a sector of a circle ranging from approximately 90° to approximately 180°. This range ensures a good balance between protection of a wide area of the front cutting plane and good accessibility to the cutting tool.

According to a preferred embodiment of the invention said guard is provided with at least one opening, preferably made above the cutting plane.

Even the said opening, as well as the inclined and raised position of the guard with respect to the cutting plane, prevents the shredded grass from accumulating under the protection device and winding around the head of the cutting tool.

In fact, if the grass is very high, once it has been cut it rests on said protection device, which, as already said, prevents it from winding around the head of the cutting tool and spares the operator the bothersome need to stop to remove it. Furthermore, very high grass is not crushed by the guard and the successive grass cutting operation is not affected. Furthermore, an opening saves material, thus reducing costs and weight.

The larger is the opening, the least grass is crushed, but more gravel or other objects may be projected out and the protection device is less stable, therefore the size of the opening must be selected trying to find the best possible balance among the needs mentioned above: good protection against projected objects, low weight, low material consumption, high stability of the guard.

Obviously, the guard may be provided with further openings, even far from the edge, in order to lighten the guard and save material.

The coupling of the device preferably allows the protection device to be fixed to the rod. Advantageously, said coupling is a first channel created on the side opposite said arc that can be connected to a counter piece in which a second channel is formed, thus enclosing the rod in a fixed manner between the two channels.

These two channels work like two half shells with semi-circular cross section that when connected to each other - for example by means of screws and nuts - enclose the rod in a fixed manner.

This type of coupling that can be moved along the rod makes it possible to adjust the height of the protection device on the rod, so that the protection device adapts to the inclination of the rod, which can be variable and chosen, for example, based on the height of the operator.

Furthermore, the specific coupling just described makes it possible to install said protection device on most of the different types of bush cutters available on the market, thus making the same protection device substantially universal. The proposed coupling thus allows a bush cutter to be provided with a protection device according to the invention even after its purchase.

It is possible to conceive also other couplings that guarantee that the protection device can be securely and removably fastened to the rod.

It may be necessary to vary the inclination of the protection device with respect to the cutting plane. Therefore, according to a very advantageous embodiment of the invention said protection device is provided with a positioning means in order to allow it to be inclined with respect to said cutting plane, independently of the inclination determined by the rod.

According to a preferred embodiment of the invention, said positioning means is a hole made in said first channel, through which it is possible to insert, in direct or indirect contact with said rod, a dowel whose position inside said hole can be adjusted. The dowel insertion depth allows a fine adjustment of the inclination of the protection device.

The variant embodiment with indirect contact also includes, on the first channel, at the height of the above mentioned hole, a flexible tang that, when the protection device is installed on the bush cutter, is interposed between the above mentioned dowel and the rod.

In this way it is possible to avoid any direct contact between the rod and the dowel, a situation in which the rod may wear out, for example because of scratches.

Again, in a preferred variant embodiment of the invention, if the cutting tool is a wire, the protection device comprises a wire-cutting knife that makes it possible to maintain said wire at such a length that it perfectly coincides with said protection device.

This makes it possible to prevent the wire from hitting against obstacles that are external to the protection device, even in the case where said protection device is slightly above the cutting plane, as previously explained.

Said wire-cutting knife is preferably located in the side perimeter portion of the protection device with its cutting blade arranged substantially parallel to the rotation axis of the wire, so as to limit the extension of the latter beyond the perimeter of the protection device.

The protection device is preferably injection moulded in a single piece. Production therefore requires reduced processing, which makes the protection device inexpensive.

To make the device it is possible to use the most different plastic materials with suitable characteristics, like for example good resistance to impacts and humidity, and a certain degree of rigidity. A metal protection device can also be conceived.

Another aspect of the invention concerns a bush cutter comprising a guide rod, a head provided with a rotatable cutting tool that during rotation defines a substantially circular cutting plane, a motor suited to operate the cutting tool and, optionally, a rear gravel guard, said bush cutter comprising also a protection device according to the invention.

The present invention has achieved the object to provide a protection device and a corresponding bush cutter that overcome the above mentioned drawbacks of the known art.

In particular, the present invention proposes a protection device suited to protect both third parties and objects from the cutting tool, and the cutting tool from excessive wear and/or damage.

Furthermore, the protection device according to the invention is simple to produce and can be installed on bush cutters that are not provided with such a protection device, even after their purchase.

The protection device disclosed herein furthermore prevents the grass from being crushed during the cutting operation and the cut material from accumulating under the protection device.

Variant embodiments of the invention are the subject of the dependent claims. They will be highlighted in greater detail in the descriptions of preferred embodiments of the invention that are supplied as indicative, non-limiting examples with reference to the enclosed drawings.

Brief description of the drawings

- Figure 1 shows an axonometric view of a protection device according to the invention installed on a bush cutter;

- Figure 2 shows a side view of the protection device installed on a bush cutter shown in Figure 1 ;

- Figure 3 shows an axonometric view of another example of embodiment of a protection device carried out according to the invention;

- Figure 4 shows a top view of the protection device of Figure 3;

- Figure 5 shows a side view of the protection device of Figure 3;

- Figure 6 shows a rear view of the protection device of Figure 3;

- Figure 7 shows an axonometric view of a counter piece for a coupling of the protection device of Figure 3;

- Figure 8 shows a top view of the counter piece shown in Figure 7;

- Figure 9 shows a front view of the counter piece shown in Figure 7.

Description of the examples of embodiment

In Figure 1 a protection device is indicated as a whole by 2. The protection device 2 is carried out as a guard 4 mounted on a rod 8 by means of a coupling 6. On the end of the rod 8 shown in the figure there is a head 10 provided with a cutting tool 12 (in this case a wire) that can be rotated in the direction X by means of a motor not illustrated herein. The rod is also provided with a rear gravel guard 14.

The guard 4 is substantially flat and elliptical in shape, and above the head 10 it has a wide opening 5. Its edge 16 is folded downwards.

The portion of the guard 4 and of its edge 16 indicated by the arc-shaped segment β protect the front perimeter portion of the cutting plane 18 shown in Figure 2.

The protection device 2 of the invention is preferably but not necessarily provided with a wire-cutting knife 19 located along the side perimeter of the protection device 2 itself and having its cutting blade substantially parallel to the rotation axis of the cutting tool 12 (in the case at hand, the wire), as shown in Figures 1 and 2.

Figure 2 shows a side view of the protection device 2 of Figure 1. The reference number 18 indicates the cutting plane defined by the rotation of the wire mounted on the head 10. The rod 8 is inclined by an angle a with respect to the cutting plane 18. The downward folded edge 16 protects a portion of the front perimeter of the cutting plane, even in the axial direction defined by the rotation axis Y.

Figure 3 shows an axonometric view of another example of embodiment of a protection device 102. The protection device is carried out with a substantially flat guard 104 whose edge 116 is folded downwards. The coupling 106 is carried out with a channel 107 suited to house a rod not illustrated herein. A hole 109 made in the channel 107 makes it possible to insert a dowel for the fine adjustment of the inclination of the protection device 102.

In addition to a relatively large opening 105 (which serves to allow the grass to be expelled) there is a plurality of further holes 120 near the coupling 106 intended to reduce the quantity of material used to make the protection device as well as the weight of the latter.

Figure 4 shows a top view of the protection device 102 of Figure 3. The reference numbers that are already known are not explained again for the sake of brevity.

Two holes 122 serve to insert screws to connect the coupling 106 to a counter piece provided with a second channel and illustrated in Figures 7-9, intended to enclose the rod not illustrated herein.

Figure 5 shows a side view of the protection device 102 of Figure 3. This view makes it easier to notice that the guard - and with this its edge 116 - in its front portion 124 opposite the coupling 106 is slightly raised with respect to the substantially flat surface of the guard 104, thus improving the way in which the front portion 124 adapts to the cutting plane.

Figure 6, showing a rear view of the protection device 102 of Figure 3, illustrates from a different perspective the raised configuration of the front portion 124 with respect to the substantially flat surface of the guard 104.

Figure 7 shows a device 150 that serves as a counter piece for the coupling 106 of the protection device 102 shown in Figures 3-6. A channel with cross section in the shape of a semicircle 152 is suited to accommodate a rod not illustrated herein.

Screws (also inserted in the holes 122 of Figure 4) can be inserted through the holes 154, thus connecting the counter piece 150 and the coupling 106 that in this way enclose a rod of a bush cutter not illustrated herein.

Figure 8, showing a top view of the counter piece 150 of Figure 7, and Figure 9, showing a front view of the counter piece 150, serve only to illustrate the counter piece 150 of the coupling 106 in greater detail and according to different perspectives.

If in the construction phase modifications falling within the scope of the following claims are made to the protection device or the bush cutter of the invention, said modifications must all be considered protected by the present patent.

Where technical features mentioned in any claim are followed by reference signs, those reference sings have been included for the sole purpose of increasing the intelligibility of the claims and accordingly such reference signs do not have any limiting effect on the protection of each element identified by way of example by such reference signs.

Claims

1) Protection device (2; 102) for bush cutters comprising a guide rod (8), a head (10) provided with a rotatable cutting tool (12) that during rotation defines a substantially circular cutting plane (18), a motor suited to operate said cutting tool (12), wherein the protection device (2; 102) includes a coupling (6; 06) suited to fix it to said bush cutter, characterized in that it is carried out in the form of a guard (4; 104) with a substantially flat base surface that when installed on the bush cutter extends mainly along the axis of said rod (8) inclined by an angle (a) in relation to the cutting plane (18) and the perimeter of said base surface describes, at least partially at the level of the radial portion and, in the axial direction (Y), at the level of the front perimeter portion of said cutting plane (18), an arc (β) that coincides with or slightly projects beyond the perimeter of said cutting plane (18), wherein said arc (β) is provided at least on part of its extension with a downward folded edge (16; 116) suited to cover said front perimeter portion of said cutting plane (18) in the axial direction (Y) of the latter.

2) Protection device according to claim 1), characterized in that the part of said guard (124) limited by said arc (β) is slightly lifted with respect to the plane formed by said base surface.

3) Protection device according to claim 1) or 2), characterized in that said arc (β) describes a sector of a circle from approximately 90° to approximately 180°.

4) Protection device according to any of the preceding claims, characterized in that said guard (4; 104) is provided with at least one opening (5; 105).

5) Protection device according to any of the preceding claims, characterized in that said coupling (106) is a first channel (107) created on the side opposite said arc that can be connected to a counter piece (150) in which a second channel (152) is formed, enclosing said rod in a fixed manner between the two channels.

6) Protection device according to any of the preceding claims, characterized in that it is provided with a positioning means so that it can be inclined in relation to said cutting plane (18).

7) Protection device according to claim 6), characterized in that said positioning means is a hole (109) made in said first channel (107) through which it is possible to insert, in direct or indirect contact with said rod, a dowel whose position inside said hole (109) can be adjusted.

8) Protection device according to any of the preceding claims, characterized in that it is moulded by injection as a single piece.

9) Protection device according to any of the preceding claims, characterized in that it comprises a wire-cutting knife (19) located along the side perimeter of said protection device (2) and having its cutting blade arranged substantially parallel to the rotation axis of said cutting tool (12).

10) Bush cutter comprising a guide rod (8), a head (10) with a rotatable cutting tool (12) that during rotation defines a substantially circular cutting plane (18), a motor suited to operate the cutting tool (12) and optionally a rear gravel guard (14), characterized in that it also comprises a protection device (2; 102) according to any one of the claims from 1) to 9).