GB2459100A

GB2459100A - Trimmer

Info

Publication number: GB2459100A
Application number: GB0806377A
Authority: GB
Inventors: Ian Zetterstrom Smith; Edward Martin; Douglas James Begg
Original assignee: Husqvarna AB
Current assignee: Husqvarna AB
Priority date: 2008-04-08
Filing date: 2008-04-08
Publication date: 2009-10-14
Anticipated expiration: 2028-04-08
Also published as: GB0806377D0; GB2459100B; WO2009124697A1

Abstract

A trimmer comprises a cutting head 4 having a guard 5 housing a cutter 6 rotatable in a plane substantially normal to the axis of rotation of the cutting head, the guard partially surrounding the swept path of the cutter, and the guard is provided with a plant guard portion 10. Preferably the plant guard portion is movable and pivotally connected to the guard by hinges. Both the guard and plant guard portions may be made of polypropylene. The trimmer may be driven by an internal combustion engine or an electric motor. Advantageously inadvertent damage to plants is avoided.

Description

Trimmer This invention relates to a trimmer, and in particular to a grass trimming device provided with means for protecting plants from the cutting path swept out by the cutter of the trimmer.

A known grass trimming device (a string trimmer) comprises a cutting head mounted at one end of a shaft, an operator handle being positioned at the other end of the shaft.

The cutting head includes a cutter constituted by a rotatable flexible cutting line. The cutting head can be moved relative to the shaft, to position the cutter generally horizontal for grass trimming, or generally vertical for edge trimming. Such a trimmer can be used in commercial or domestic applications, and may be powered by an electric motor or an internal combustion engine.

When trimming grass, the rotating cutting line is used to cut grass and other soft vegetation by simply moving the trimmer in such a way that the swept path of the cutting line comes into contact with the vegetation to be severed.

A potential problem with this type of trimmer occurs when the trimmer is to be used in close proximity to plants that are not intended to be cut, such as decorative flowers and shrubs. In such a situation, it can be difficult to achieve effective grass trimming without damage to other plants, owing to the trimmer being difficult to control, the cutting plane being difficult to observe, or to windage from the cutter causing plants to be drawn or blown into the path of the cutting line.

EP 893050 discloses a trimmer provided with a wire guard, guarding part of the swept path of the cutting line. Owing to the limited area guarded by such a wire guard, this device has limited effect. The device also requires an additional part to be fixed to the grass trimmer.

EP 1121858 discloses a trimmer provided with a more substantial plant guard that can be rotated so that it is effective in both lawn trimming and lawn edging orientations.

This plant guard is quite large and relatively complex, consisting of several parts and associated fixing means. This complexity adds additional cost to that of the basic trimmer.

An aim of the invention is to alleviate or overcome these problems, and to provide a trimmer with a simple but effective plant guard at minimal cost.

The present invention provides a trimmer comprising a cutting head having a guard housing a cutter rotatable in a plane substantially normal to the axis of rotation of the cutting head, the guard partially surrounding the swept path of the cutter, wherein the guard is provided with a plant guard portion.

In a preferred embodiment, the plant guard portion is movable between a first, operative position in which it extends radially in close proximity to or beyond that part of the swept path not surrounded by the guard, and a second, non-operative position in which it does not extend radially beyond that part of the swept path.

Preferably, the plant guard portion is integrally formed with the guard, and more preferably, the guard and the plant guard portion are an integral injection moulded member. Advantageously, the injection moulded member is made of polypropylene.

In a preferred embodiment, the plant guard portion is a substantially laminar, part-annular member.

Preferably, the plant guard portion is pivotally connected to the guard. The plant guard portion may be pivotally connected to the guard by hinges positioned at the two ends of the part-annular member. Advantageously, the axes of the two hinges are angled relative to one another, and the axes of the two hinges lie in a common plane.

Said common plane may lie at an angle to the plane of the swept path of the cutter.

In a preferred embodiment, the laminar plant guard portion curves in one direction away from said common plane when in its first position, and curves in the opposite direction when in its second position. Advantageously, the curved configurations of the laminar plant guard portion in the first and second positions are mirror images of one another with respect to said common plane..

Preferably, the pivotal connection between the plant guard portion and the guard is such that the plant guard portion moves through an over-centre snapping position as it moves between its first and second positions, and the plant guard portion is maintained stably in each of its first and second positions.

In another preferred embodiment, the plant guard portion is a separate member. In this case, the hinges are integrally formed with either the plant guard portion or the guard.

The invention thus provides a grass trimmer comprising an elongate shaft, a handle at one end of the shaft end and a cutting mechanism at the other end of the shaft. The cutting mechanism further consists of a motor-driven cutting head housed within a debris guard. The cutting head contains a cutting line which is allowed to protrude from the cutting head in a radial direction, that is normal to the axis of rotation of the cutting head. The debris guard is configured to protect the operator from debris thrown by the cutting line, while allowing a portion of the swept path of the cutting line is to unguarded allowing grass and vegetation to enter the swept path of the cutting line. The debris guard is furthermore configured to incorporate a simple plant guard for use when trimming in close proximity to plants that require protection from the cutting line. The plant guard can be integrated with the debris guard, and can easily moved and retained in a first position (where it acts as a plant guard) and in a second position (where it does not interfere with normal trimming or edging actions).

The invention will now be described in greater detail, by way of example, with reference to the drawings, in which: Figure 1 is a perspective view of a grass trimmer constructed in accordance with the invention, and shows a plant guard in its operational (protecting) position; Figure 2 is a perspective view of the trimmer of Figure 1 with the plant guard in its non-operational (non-protecting) position; Figure 3 is a side view of the lower portion of the trimmer showing its cutting head and debris guard, and showing the plant guard in its operational position, and the plant guard in its non-operational position in dotted lines; Figure 4 is a side view similar to that of Figure 3 showing the plant guard in its non-operational position, and the plant guard in its operational position in dotted lines; Figure 5 is an underside view of the debris guard with the plant guard in its operational position; and Figure 6 is an underside view of the debris guard with the plant guard in its non-operational position Referring to the drawings, Figure 1 shows a grass trimmer having an elongate shaft 1, a main handle 2 at one end of the shaft, and a motor housing 3 at the other end of the shaft. The motor housing 3 houses an electric motor (not shown) which drives a cutting head 4 housed within a debris guard 5. The cutting head 4 contains at least one flexible cutting line 6 which protrudes from the cutting head in a radial direction, that is normal to the axis of rotation of the cutting head. The distal end of the main handle 2 defines a hand-grippable portion 7. A steady handle 8 is provided at the lower end of the main handle 2 adjacent to the upper end of the shaft 1.

In use, the trimmer is held and guided using the handles 2 and 8. For grass trimming, the cutting head 4 is orientated so that the rotational axis of the motor and the cutting head 4 is generally vertical, and the resulting plane of the swept path of the cutting line 6 is generally horizontal. Activation of a switch 9 provided within the portion 7 of the main handle 2 results in a supply of electricity to the motor, and rotation of the cutting head 4. The trimmer is then guided in such a manner that the swept path of the cutting line 6 comes into contact with grass or other vegetation to be cut. When cutting is complete, release of the switch 9 removes power from the motor, and rotation of the cutting head 4 stops.

The debris guard 5 partially surrounds the cutting head 4 and the cutting line 6 in such a manner that the cutting line has an effective cutting range which extends somewhat less than 1800, and so the debris guard prevents debris (such as cut grass, soil or small stones) being thrown towards the user. The debris guard 5 includes an integrally-formed plant guard 10, and is an injection moulded member made of polypropylene or a similar polymer.

The debris guard 5 is generally formed in the shape of a portion of an inverted dish, and is shaped to surround a significant portion of the swept path of the cutting line 6, particularly the portion towards the rear of the unit when used for grass trimmer so as to protect the user from thrown debris.

When the trimmer is being used in areas where accidental damage to plants is to be avoided, the plant guard 10 is positioned in its operative position, as shown in Figure 3. In this position, the plant guard 10 offers a degree of protection from accidental plant damage, particularly to flowers, shrubs and young trees. When the trimmer is being used in an area where accidental damage to vegetation is not probable, for example in long overgrown conditions, the plant guard 10 can be lifted to the non-operative position shown in Figure 4. This position allows the overgrown vegetation to easily enter the swept path of the cutting line 6.

For lawn edging, the cutting head 4 is orientated so that the rotational axis of the motor and the cutting head 4 is generally horizontal, and the resulting plane of the swept path of the cutting line 6 is generally vertical. Activation of the switch 9 results in supply of electricity to the motor and rotation of the cutting head 4. The trimmer is then guided in such a manner that the swept path of the cutting line 6 comes into contact with, and follows, the edge of a lawn. For lawn edging, the plant guard 10 is positioned in its non-operative position as shown in Figure 4, allowing the cutting line 6 to reach the lawn edge and to prevent the plant guard 10 being an obstruction.

The plant guard 10 is ideally an integral part of the debris guard 5, the debris guard 5 being produced as an injection moulding incorporating live hinges using the flexible nature of the material and known design techniques to facilitate reliable relative movement between the plant guard and the main part of the debris guard.

The front portion of the main part of the debris guard 5 is cut away so that grass (or other vegetation) to be trimmed can be cut by the cutting line 6 when the trimmer moves in the direction of the arrow A in Figure 1, or by a side-to-side motion indicated by the double sided arrow E in Figure 1. The plant guard 10 is designed in such a way that, in its operational position (see Figures 3 and 5), it protrudes from the main part of the debris guard 5 above the plane of the swept path of the cutting line 6, and its distal end is radially positioned beyond the swept path (indicated by a dotted circle in Figure 5) of the cutting line 6. In its non-operational position (see Figures 4 and 6), the plant guard 10 is angled further away from the swept path of the cutting line 6 so that, its distal end is within the swept path (indicated by a dotted circle in Figure 6), and so does not interfere with the cutting action of the cutting line.

The plant guard 10 has two functional positions, an operational position (see Figures 3 and 8) where the plant guard helps prevent inadvertent damage to plants, and a non-operational position (see Figures 4 and 6) where the plant guard is positioned away from the swept path of the cutting line 6 and in such a position that it does not interfere with normal grass trimming or lawn edging. To achieve these two functional positions, the plant guard 10 is hinged to the main part of the debris guard 5 at two hinges BB and CC (see Figure 5). The axes of the two hinges BB, CC sit in a common plane XX, and are angled towards one another at an angle Y (see Figure 5).

The plant guard 10 of the debris guard S when in its operational position, takes a generally curved form sitting below the plane XX (see Figure 3). This curved form gives the plant guard 10 some inherent strength and stifihess so that it naturally maintains its shape. In addition, because the hinges BB, CC are at an angle to one another, they act against one another to prevent uncontrolled or self-hinging of the plant guard 10, thereby maintaining the position of the plant guard.

Because the debris guard 5 is manufactured from a flexible material, it is possible with manual intervention to force the plant guard 10 to change position by pivoting about the two hinges BB and CC. This is achieved by forcing the plant guard 10 in the appropriate direction, as illustrated by the arrow D in Figure 3 or the arrow E in Figure 4, depending on the final position to be achieved. Such a movement is achieved by allowing a small amount of flex within the debris guard 5 close to the axes of the hinges BB, CC, and by allowing some deflection and twisting within the plant guard 10. When a point is reached where the plant guard 10 passes beyond the plane XX, the natural strength and stiffness of the plant guard takes over and allows the plant guard to complete the action by returning to its natural configuration and maintaining a new position mirroring its previous position. This change in position is shown by dotted lines in Figures 3 and 4. This over-centre snapping movement of the plant guard 10 is similar to the movement of the peak of a baseball cap which has two stable positions, one in which it is pushed up over centre, and the other in which it is pushed down over centre.

It will be apparent that modifications could be made to the trimmer described above.

For example, the plant guard 10 could be a separate part rather than being formed integrally with the debrisguard 5. In this case, the hinges could be formed integrally with either the guard 5 or the plant guard 10. It would also be possible to use an internal combustion engine in plane of the electric motor.

It would also be possible for the plant guard 10 to extend, in its operative position, radially in close proximity to the radial extent of the swept path of the cutting line 6.

This would enable trimming to be carried right up to an obstacle such as a tree or a wall.

Claims

Claims 1. A trimmer comprising a cutting head having a guard housing a cutter rotatable in a plane substantially normal to the axis of rotation of the cutting head, the guard partially surrounding the swept path of the cutter, wherein the guard is provided with a plant guard portion.
2. A trimmer as claimed in claim 1, wherein the pJant guard portion is movable between a first, operative position in which it extends radially in close proximity to or beyond that part of the swept path not surrounded by the guard, and a second, non-operative position in which it does not extend radially beyond that part of the swept path.
3. A trimmer as claimed in claim I orclaim 2, wherein the plant guard portion is integrally formed with the guard.
4. A trimmer as claimed in claim 3, wherein the guard and the plant guard portion are an integral injection moulded member.
5. A trimmer as claimed in claim 4, wherein the injection moulded member is made of polypropylene.
6. A trimmer as claimed in any one of claims I to 5, wherein the plant guard portion is a substantially laminar, part-annular member.
7. A trimmer as claimed in claim 6, wherein the plant guard portion is pivotally connected to the guard.
8. A trimmer as claimed in claim 7, wherein the plant guard portion is pivotally connected to the guard by hinges positioned at the two ends of the part-annular member.
9. A trimmer as claimed in claim 8, wherein the axes of the two hinges are angled relative to one another.
10. A trimmer as claimed in claim 8 or claim 9, wherein the axes of the two hinges lie in a common plane.
11. A trimmer as claimed in claim 10, wherein said common plane lies at an angle to the plane of the swept path of the cutter.
12. A trimmer as claimed in claim 11, wherein the laminar plant guard portion curves in one direction away from said common plane when in its first position, and curves in the opposite direction when in its second position.
13. A trimmer as claimed in claim 12, wherein the curved configurations of the laminar plant guard portion in the first and second positions are mirror images of one another with respect to said common plane.
14. A trimmer as claimed in any one of claims 7 to 13, wherein the pivotal connection between the plant guard portion and the guard is such that the plant guard portion moves through an over-centre snapping position as it moves between its first and second positions, and the plant guard portion is maintained stably in each of its first and second positions.
15. A trimmer as claimed in claim 2, or in any one of claims 7 to 14 when appendent to claim 2, wherein the plant guard portion is a separate member.
16. A trimmer as claimed in claim 15 when appendent to claim 8, wherein the hinges are integrally formed with the plant guard portion.
17. A trimmer as claimed in claim 15 when appendent to claim 8, wherein the hinges are integrally formed with the guard.
18. A trimmer substantially as hereinbefore described with reference to, and as illustrated by, the drawings.