Edge trimming tool assembly and power tool

Abstract

An edge cutting tool assembly (1) is disclosed that is configured to cut plants around an edge forming part (50). The assembly (1) includes a drive shaft (3) and a cutting tool (5) that is configured to rotate about a rotation axis (ax) by the drive shaft (3) such that a radially outer portion (5') of the cutting tool (5) follows a circular path (c). The assembly (1) includes a guard (7) having a first guard portion (11) that covers a portion of a region (A) formed inside the circular path (c) when viewed from a first direction (d1) parallel to the rotation axis (ax), and a second guard portion (12) that covers a portion of the region (A) when viewed from a second direction (d2) parallel to the rotation axis (ax) and opposite to the first direction (d1). The present disclosure further relates to a power tool (2) including the edge cutting tool assembly (1).

Description

Technical Field

[0001] The present disclosure relates to an edge trimming tool assembly configured to cut plants around an edge forming portion. The present disclosure further relates to a power tool including the edge trimming tool assembly.

Background Art

[0002] Trimmer devices, also called string trimmers, line trimmers, and brush cutters, are a type of power tool used to cut grass and other types of plants. The trimmer device includes a cutting tool having a trimmer line that is rotated at a speed sufficient to cut plants during rotation of the cutting tool by a centripetal force acting on the trimmer line that gives rigidity to the trimmer line. The cutting tool can be rotated using, for example, an electric motor or an internal combustion engine.

[0003] Trimmer devices are typically designed to be held such that the trimmer line orbits in a generally horizontal plane during operation. Further, trimmer devices typically include a guard that covers the upper side of the cutting tool to prevent the scattering of residues during cutting from the trimmer device as well as other types of objects and particles during use of the trimmer device.

[0004] When designing a power tool such as a trimmer device, there are several common problems. One problem is ergonomics. That is, it is advantageous if the user can simply use the trimmer device ergonomically. Another problem is user-friendliness. That is, it is advantageous if the trimmer device is designed to be simple and intuitive to use. Yet another problem is the cutting result, which can be defined as the uniformity of cutting. The uniformity of cutting can be defined as the uniformity of the length of the plants being cut (i.e., whether the plants in a given area are cut to a uniform length).

[0005] A further problem is safety. That is, the trimmer device is preferably designed to be safely usable. However, usually, a powerful motor is required to rotate the cutting tool, and a high rotational speed is usually required to enable the cutting tool to cut plants. This can make it difficult to obtain a trimmer that is safe to use, at least for some specific tasks.

[0006] One task that is difficult to perform using a trimmer device is cutting the plants around an edge forming part having a generally vertical section. An example of such an edge forming part is the edge forming part surrounding a bunker on a golf course.

[0007] Today, some users use a trimmer device of the above type when cutting such an edge forming part and hold the trimmer device in an unintended operating position where the trimmer line orbits in a substantially vertical plane. Such an operation can pose a danger to the user and nearby people, is not ergonomic, and can cause non-uniform cutting results.

[0008] Furthermore, some users, such as green keepers on a golf course, modify various tools that can assist in performing edge cutting in an appropriate manner. Those modified products are not developed by experts for such use. Furthermore, they are usually not ergonomic, and the cutting results can be non-uniform. Additionally, products modified for a purpose other than the intended one can pose a danger to the user and nearby people.

[0009] Furthermore, generally, it is advantageous if products such as power tools and related assemblies have conditions and / or characteristics suitable for being manufactured and assembled in a cost-effective manner. SUMMARY OF THE INVENTION PROBLEMS TO BE SOLVED BY THE INVENTION

[0010] The object of the present invention is to overcome or at least mitigate at least some of the above-mentioned problems and drawbacks.

Means for Solving the Problem

[0011] According to a first aspect of the present invention, the object is achieved by an edge cutting tool assembly configured to cut plants around an edge forming part. The assembly includes a drive shaft and a cutting tool connected to the drive shaft. The cutting tool is configured to rotate around a rotation axis by the drive shaft so that an outer radial portion of the cutting tool orbits a circular path in a rotation plane. The assembly includes a guard having a first guard portion covering a part of a region formed inside the circular path when viewed from a first direction parallel to the rotation axis, and a second guard portion covering a part of the region when viewed from a second direction parallel to the rotation axis and opposite to the first direction.

[0012] Since the guard of the cutting tool assembly includes the first and second guard portions each covering a part of the region when viewed from respective directions parallel to the rotation axis, while providing conditions for improved cutting results, a cutting tool assembly is provided that is simple, ergonomic, and has conditions for more safely cutting plants around the edge forming part.

[0013] This is because one of the first and second guard portions can be moved along a substantially vertical section of the edge forming part, thereby ensuring a predetermined distance between the rotation plane of the cutting tool and the edge forming part. By ensuring a predetermined distance between the rotation plane of the cutting tool and the edge forming part, the cutting result (i.e., the uniformity of cutting) can be improved. Further, a cutting tool assembly is provided that requires less skill of the user to obtain a more uniform cutting result around the edge forming part. In other words, a cutting tool assembly is provided in which the influence of the user's skill on the cutting result is reduced.

[0014] Furthermore, a cutting tool assembly is provided that enables a safer and more ergonomic operation of the cutting tool assembly, in which the first and second guard portions of the guard of the cutting tool assembly cover a portion of the area when viewed from respective directions parallel to the axis of rotation, so that the radially outer portion of the cutting tool orbits in a substantially perpendicular plane of rotation.

[0015] Accordingly, a cutting tool assembly is provided that overcomes or at least mitigates at least some of the above-described problems and drawbacks. As a result, the above object is achieved. Optionally, each of the first guard portion and the second guard portion covers more than 30% or more than 50% of the area when viewed from the first direction and the second direction, respectively. Thereby, while providing conditions for improved cutting results, a cutting tool assembly is provided that has conditions for simply, ergonomically, and more safely cutting plants around the edge forming portion.

[0016] Optionally, each of the first guard portion and the second guard portion overlaps more than 70% of the other of the first guard portion and the second guard portion when viewed from the first direction and the second direction, respectively. Thereby, while providing conditions for improved cutting results, a cutting tool assembly is provided that has conditions for simply, ergonomically, and more safely cutting plants around the edge forming portion.

[0017] Optionally, the cutting tool includes a tubular elongated support, the drive shaft is disposed inside the tubular elongated support, and the drive shaft includes a connection portion for connecting the output shaft of the power unit to the drive shaft. Thereby, a cutting tool assembly is provided that has conditions for being simply, safely, ergonomically, and intuitively used integrally with the power unit.

[0018] Optionally, the guard is attached to the mounting section of the tubular elongate strut, and the angle between the rotational plane and the vector from the mounting section towards the connection portion is within the range of 10 degrees - 85 degrees, or within the range of 59 degrees - 79 degrees. Thereby, a cutting tool assembly is provided that enables a safer and more ergonomic operation of the cutting tool assembly while the cutting tool is held in a position such that the radially outer portion of the cutting tool orbits in a substantially perpendicular rotational plane.

[0019] Optionally, a portion of the tubular elongate strut located between the mounting section and the connection portion is substantially straight. Thereby, a cutting tool assembly is provided that has conditions for being simple, safe, ergonomic, and intuitively used integrally with the power unit.

[0020] Optionally, the drive shaft has flexibility and the tubular elongate strut has a curved portion. Thereby, a cutting tool assembly is provided that has conditions and characteristics suitable for being manufactured and assembled in a cost - efficient manner, while having conditions for being simple, ergonomic, and safely cutting plants around the edge forming portion.

[0021] Optionally, the curved portion is disposed between the mounting section and the cutting tool. Thereby, a cutting tool assembly is provided that has conditions and characteristics suitable for being manufactured and assembled in a cost - efficient manner, while having conditions for being simple, ergonomic, and safely cutting plants around the edge forming portion. Further, a cutting tool assembly is provided that has conditions for being compact.

[0022] Optionally, each of the connection portion and the first guard portion is disposed on a first surface of the rotational plane. Thereby, a cutting tool assembly is provided that has conditions for being simple, ergonomic, and safely cutting plants around the edge forming portion.

[0023] The cutting guard includes a first edge portion disposed radially outside the cutting tool, and the first edge portion connects the first guard portion and the second guard portion. Thereby, a cutting tool assembly is provided that has conditions for more safely cutting plants around the edge forming portion. This is because the first edge portion can prevent residues, as well as other types of objects and particles, from scattering radially from the cutting tool during cutting.

[0024] Optionally, a tubular elongated support is attached to the first edge portion. Thereby, a cutting tool assembly is provided that has conditions and characteristics suitable for being manufactured and assembled in a cost-effective manner, while being simple, ergonomic, and having conditions for safely cutting plants around the edge forming portion. Further, a cutting tool assembly is provided that has conditions of rigidity and durability.

[0025] Optionally, the first edge portion is in an arc shape having a radius of curvature within the range of 80% - 130% of the distance between the rotation axis and the first edge portion. Thereby, a cutting tool assembly is provided that has conditions for being compact and lightweight, while being simple, ergonomic, and having conditions for safely cutting plants around the edge forming portion. Further, a cutting tool assembly is provided in which the guard is less likely to get caught (e.g., by plants) during operation.

[0026] Optionally, the arc length of the first edge portion is within the range of 50% - 500% of the distance between the rotation axis and the first edge portion, or within the range of 100% - 250%. Thereby, a cutting tool assembly is provided that has conditions for more safely cutting plants around the edge forming portion. This is because the first edge portion can prevent residues, as well as other types of objects and particles, from scattering from the cutting tool along most of the circumference of the circular path of the radially outer portion of the cutting tool during cutting.

[0027] Optionally, the guard comprises a second edge portion disposed opposite the first edge portion. Thereby, a cutting tool assembly is provided that has conditions for more safely cutting plants around the edge forming portion. This is because the second edge portion can prevent residues, as well as other types of objects and particles, from scattering in the radial direction of the cutting tool during cutting.

[0028] Optionally, the second edge portion connects the first guard portion and the second guard portion. Thereby, a cutting tool assembly is provided that has conditions for more safely cutting plants around the edge forming portion.

[0029] Optionally, the second edge portion forms a ground engaging portion for maintaining a predetermined distance between the axis of rotation and the ground surface by abutting contact with the ground surface. Thereby, while providing conditions for improved cutting results, a cutting tool assembly is provided that has conditions for more simply, more ergonomically, and more safely cutting plants around the edge forming portion. This is because one of the first and second guard portions can be used to maintain a predetermined distance between the rotational plane of the cutting tool and a generally perpendicular section of the edge forming portion, while the second edge portion can be used to maintain a predetermined distance between the axis of rotation and the ground surface adjacent to a generally perpendicular section of the edge forming portion.

[0030] Furthermore, a cutting tool assembly is provided in which the second edge portion forms a ground engaging portion for maintaining a predetermined distance between the axis of rotation and the ground surface, whereby scattering of objects and particles from the ground surface can be significantly reduced. As an example, when the cutting tool assembly according to an embodiment of the present specification is used to cut plants around the edge forming portion of a bunker on a golf course, the second edge portion is used up to a predetermined distance between the axis of rotation and the sand surface of the bunker, thereby avoiding scattering of sand during operation of the cutting tool assembly. Such sand scattering can pose a danger to the user and nearby people and can cause an undesirable movement of sand from the bunker to the adjacent turf surface.

[0031] Optionally, the second edge portion is in the shape of an arc having a radius of curvature within the range of 80% - 130% of the distance between the axis of rotation and the second edge portion. Thereby, a cutting tool assembly is provided that has conditions for being compact and lightweight while having conditions for simply, ergonomically, and safely cutting plants around the edge forming portion. Further, a cutting tool is provided that is less likely to catch on the second guard portion when moving above a surface such as the ground surface or the sand surface of a bunker on a golf course.

[0032] Optionally, the arc length of the second edge portion is within the range of 3% - 180% of the distance between the axis of rotation and the second edge portion, or within the range of 25% - 90%. Thereby, a cutting tool assembly is provided that can efficiently maintain a predetermined distance between the axis of rotation and the ground surface using the second guard portion.

[0033] Optionally, the guard surrounds the cutting tool in a plane parallel to the axis of rotation. Thereby, a cutting tool assembly is provided that has conditions for a rigid and durable guard while having conditions for simply, ergonomically, and more safely cutting plants around the edge forming portion.

[0034] Optionally, the guard comprises a first aperture in a first face of the plane including the axis of rotation, and the cutting tool has an effective radius greater than the distance from the axis of rotation to the edge of the first aperture. Thereby, by simply moving the cutting tool assembly so that the first aperture in the first face of the plane is moved towards the plant, a cutting tool assembly is provided that has conditions for simply, efficiently, ergonomically and safely cutting the plants around the edge forming part.

[0035] Optionally, the guard comprises a second aperture in a second face of the plane, and the cutting tool has an effective radius greater than the distance from the axis of rotation to the edge of the second aperture. Thereby, a cutting tool assembly is provided that has even simpler, more efficient and more ergonomic conditions for cutting the plants around the edge forming part. This is because the cutting tool assembly can be moved such that the first aperture in the first face of the plane or the second aperture in the second face of the plane is moved towards the plant.

[0036] Optionally, the cutting tool comprises a bevel gear assembly, and the cutting tool is connected to the drive shaft via the bevel gear assembly. Thereby, a cutting tool assembly is provided that has conditions and characteristics suitable for being manufactured and assembled in a cost-effective manner, while having conditions for simply, ergonomically and safely cutting the plants around the edge forming part. Further, a cutting tool assembly is provided that has conditions for being compact.

[0037] According to a second aspect of the invention, the object is achieved by a power tool comprising a power unit having an output shaft and a motor configured to rotate the output shaft, the power tool comprising an edge cutting tool assembly according to some embodiments of the present disclosure, wherein the drive shaft of the edge cutting tool assembly is connected or connectable to the output shaft of the power unit.

[0038] The power tool includes a cutting tool assembly according to several embodiments, providing conditions for improved cutting results while offering a simple, ergonomic, and safer way to cut plants around the edge forming part.

[0039] Furthermore, the first and second guard parts of the guard of the cutting tool assembly of the power tool each cover a part of the area when viewed from respective directions parallel to the axis of rotation, enabling a safer and more ergonomic operation while the cutting tool is held such that the radially outer part of the cutting tool orbits in a substantially perpendicular plane of rotation.

[0040] Accordingly, a power tool is provided that overcomes or at least mitigates at least some of the above-described problems and drawbacks. As a result, the above object is achieved. Further features and advantages of the present invention can become apparent by examining the appended claims and the following detailed description.

[0041] Various aspects of the present invention, including its specific features and advantages, can be readily understood from the embodiments described in the following detailed description and the accompanying drawings.

Brief Description of the Drawings

[0042]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

DETAILED DESCRIPTION OF THE INVENTION

[0043] Here, aspects of the present invention will be described more fully. Like numbers refer to like elements throughout. Well-known functions or structures are not necessarily described in detail for brevity and / or clarity.

[0044] FIG. 1 shows a perspective view of a power tool 2 according to some embodiments of the present disclosure. The power tool 2 includes a power unit 6 having an output shaft 4 and a motor 8 configured to rotate the output shaft 4. According to the illustrated embodiment, the motor 8 of the power unit 6 is an electric motor. According to further embodiments, the motor 8 of the power unit 6 may be an internal combustion engine.

[0045] According to the illustrated embodiment, the power unit 6 includes a handle portion 61, a safety switch 63, and an actuator 65, where each of the safety switch 63 and the actuator 65 is disposed on the handle portion 61 of the power unit 6. Further, according to the illustrated embodiment, the power unit 6 includes a user interface 67 that enables a user to transition the power unit 6 between an activated state and a deactivated state. The user interface 67 may include an input unit (such as a button, knob, etc.) that enables such a transition between the activated state and the deactivated state.

[0046] According to the illustrated embodiment, the power unit 6 has a control configuration that starts the operation of the motor 8 when the power unit 6 is in an activated state and each of the safety switch 63 and the actuator 65 is pressed, and thus starts the rotation of the output shaft 4 of the power unit 6. The drive shaft 4 of the power unit 6 is disposed inside the tubular column 64 of the power unit 6. The outer surface of the tubular column 64 may function as a second handle portion of the power unit 6.

[0047] The power tool 2 further includes an edge trimming tool assembly 1. As further described herein, the edge trimming tool assembly 1 is configured to trim plants particularly around the edge forming portion. For the sake of brevity and clarity, the edge trimming tool assembly 1 is referred to as the "trimming tool assembly" or simply "assembly 1" at several places in this specification. Since the power tool 2 includes the trimming tool assembly 1, the power tool 2 may also be referred to as a trimmer device, an edge trimmer device, a lawn mower, a string trimmer, a line trimmer, etc. when referred to in this specification.

[0048] The trimming tool assembly 1 includes a drive shaft 3 and a trimming tool 5 connected to the drive shaft 3. As further described herein, the trimming tool 5 is configured to rotate about the axis of rotation by the drive shaft 3 such that the radially outer portion 5' of the trimmer line of the trimming tool 5 orbits in a circular path. According to the illustrated embodiment, the trimming tool assembly 1 includes a tubular elongated support 23, in which case the drive shaft 3 is disposed inside the tubular elongated support 23.

[0049] The trimming tool 5 may be any other type of trimming tool known in the art (e.g., a grass blade). According to the illustrated embodiment, the drive shaft 3 of the cutting tool assembly 1 is connectable to the output shaft 4 of the power unit 6. More specifically, according to the illustrated embodiment, the drive shaft 3 of the cutting tool assembly 1 comprises a connection portion 25 for connecting the output shaft 4 of the power unit 6 to the drive shaft 3. The power tool 2 may comprise a splined interface between the output shaft 4 of the power unit 6 and the connection portion 25 of the drive shaft 3 of the cutting tool assembly 1. Further, according to the illustrated embodiment, the power tool 2 comprises a locking assembly 69 disposed on the tubular column 64 of the power unit 6 for locking the tubular column 64 to the tubular elongate support 23 of the cutting tool assembly 1.

[0050] According to the illustrated embodiment, the cutting tool assembly 1 may be provided and sold as a separate unit intended to be used with a power unit 6 (such as the power unit 6 according to the embodiment shown in FIG. 1). However, the cutting tool assembly 1 according to the present disclosure may also be used with another type of power unit, such as a power unit comprising an internal combustion engine.

[0051] Furthermore, according to a further embodiment, the power tool 2 referred to herein may be provided and sold as a separate unit, the power tool 2 comprising the power unit 6 and the cutting tool assembly 1, in which case the drive shaft 3 of the cutting tool assembly 1 may be permanently connected to the output shaft 4 of the power unit 6. According to such an embodiment, the output shaft 4 of the power unit 6 and the drive shaft 3 of the cutting tool assembly 1 may be different parts of the same component.

[0052] FIG. 2 shows an exploded view of some of the components of the cutting tool assembly 1 shown in FIG. 1. In the following, unless otherwise indicated, FIGS. 1 and 2 are referred to simultaneously. According to the illustrated embodiment, the cutting tool assembly 1 comprises an elongate support 23 in which a drive shaft 3 is arranged. Further, the cutting tool assembly 1 comprises a gear assembly 28, in which case the cutting tool 5 is connected to the drive shaft 3 via the gear assembly 28, as can be explained in more detail below.

[0053] Furthermore, the cutting tool assembly 1 comprises a guard 7. The guard 7 may also be referred to as a trimmer guard, for example. The guard 7 comprises a first guard part 11 which covers a part of the cutting tool 5 from a first side of the rotational plane of the radially outer part 5' of the cutting tool 5. Further, the guard 7 comprises a second guard part 12 which covers a part of the cutting tool 5 from a second side of the rotational plane of the radially outer part 5' of the cutting tool 5.

[0054] In FIG. 1, a first direction d1 and a second direction d2 are shown. The first direction d1 is directed towards the first guard part 11 of the guard 7 and is parallel to the axis of rotation of the cutting tool 5. Similarly, the second direction d2 is directed towards the second guard part 12 of the guard 7 and is parallel to the axis of rotation of the cutting tool 5. The second direction d2 is opposite to the first direction d1.

[0055] FIG. 3 shows the cutting tool assembly 1 shown in FIG. 1 when viewed along the second direction d2 shown in FIG. 1, i.e. from the direction straight towards the second guard part 12 of the guard 7. In FIG. 3, a part of the tubular elongate support 23 of the cutting tool assembly 1 has been omitted for the sake of brevity and clarity. Further, in FIG. 3, the axis of rotation ax of the cutting tool 5 is shown. As can be understood from the above, the viewing direction in FIG. 3 coincides with the direction of the axis of rotation ax.

[0056] Unless otherwise indicated, the following refers to FIGS. 1 - 3 simultaneously. As described above, the trimming tool 5 is configured to rotate about the axis of rotation ax by means of the drive shaft 3 such that the radially outer part 5' of the trimming tool 5 follows a circular path c in the plane of rotation. The plane of rotation of the radially outer part 5' of the trimming tool 5 is perpendicular to the axis of rotation of the trimming tool 5. According to the illustrated embodiment, the radially outer part 5' of the trimming tool 5 is the radially outer part 5' of the trimmer line 51 of the trimming tool 5.

[0057] FIG. 3 shows the region A formed inside the circular path c. As can be seen by comparing FIGS. 1 and 3, the second guard part 12 of the guard 7 covers a part of the region A when viewed from the second direction d2 parallel to the axis of rotation ax.

[0058] FIG. 4 shows the trimming tool assembly 1 shown in FIG. 1 when viewed along the first direction d1 shown in FIG. 1, i.e., from the direction directly facing the first guard part 11 of the guard 7. In FIG. 4, a part of the tubular elongate support 23 of the trimming tool assembly 1 is omitted for the sake of brevity and clarity. Further, FIG. 4 shows the axis of rotation ax of the trimming tool 5. The viewing direction in FIG. 4 coincides with the direction of the axis of rotation ax.

[0059] As can be seen by comparing FIGS. 1 and 4, the first guard part 11 of the guard 7 covers a part of the region A formed inside the circular path c when viewed from the first direction d1 parallel to the axis of rotation ax. The region A formed inside the circular path c may also be referred to herein as the region A surrounded by the circular path c of the radially outer part 5' of the trimming tool 5 when mentioned.

[0060] Unless otherwise indicated, reference is made simultaneously to FIGS. 1-4. The area A formed inside the circular path c may be calculated by squaring the effective radius r of the cutting tool 5 and multiplying the squared effective radius r by π. The effective radius r may be the intended effective radius r of the cutting tool 5 and may correspond to the radius of the trimmer line 51 of the intended length measured radially from the axis of rotation ax of the cutting tool 5 to the radially outer portion 5' of the cutting tool 5 when extending radially from the axis of rotation ax of the cutting tool 5.

[0061] Since the guard 7 comprises the first and second guard portions 11, 12, a cutting tool assembly 1 is provided that provides conditions for improved cutting results while having conditions for simply, ergonomically and more safely cutting the plants around the edge forming part, as further explained herein.

[0062] Furthermore, since the first and second guard portions 11, 12 of the guard 7 each cover a part of the area A when viewed from their respective directions parallel to the axis of rotation, a cutting tool assembly 1 is provided that enables a safer and more ergonomic operation of the cutting tool assembly 1 with the cutting tool 5 held such that the rotational plane of the radially outer portion 5' of the cutting tool 5 is substantially perpendicular, as further explained herein.

[0063] According to the illustrated embodiment, each of the first and second guard portions 11, 12 covers approximately 65% of the area A when viewed from the first direction d1 and the second direction d2, respectively. According to further embodiments, each of the first and second guard portions 11, 12 may cover more than 30% or more than 50% of the area A when viewed from the first and second directions d1, d2, respectively.

[0064] Furthermore, as can be seen by comparing FIGS. 3 and 4, according to the illustrated embodiment, each of the first and second guard portions 11, 12 overlaps approximately 100% of the other of the first and second guard portions 11, 12 when viewed from the first and second directions d1, d2, respectively. In other words, according to the illustrated embodiment, the surface area of the first guard portion 11 when viewed from the first direction d1 substantially corresponds to the surface area of the second guard portion 12 when viewed from the second direction d2. According to further embodiments, each of the first and second guard portions 11, 12 may overlap 70% or more or 85% or more of the other of the first and second guard portions 11, 12 when viewed from the first and second directions d1, d2, respectively.

[0065] FIG. 5 shows the cutting tool assembly 1 shown in FIG. 1 held in the intended use position with respect to the edge forming portion 50. As shown in FIG. 5, the guard 7 is attached to the attachment section 23' of the tubular elongated support 23. The attachment section 23' is also shown in FIG. 2. FIG. 5 shows the rotational plane rP of the radially outer portion of the cutting tool 5.

[0066] As can be seen in FIG. 5, according to the illustrated embodiment, each of the connection portion 25 of the drive shaft 3 and the first guard portion 11 is disposed on the first face S1' of the rotational plane rP, while the gear assembly 28 is disposed on the second face S2' of the rotational plane rP, where the second face S2' is opposite to the first face S1'.

[0067] According to the illustrated embodiment, the angle a1 between the rotational plane rP and the vector v from the attachment section 23' towards the connection portion 25 is approximately 69 degrees. According to further embodiments, the angle a1 between the rotational plane rP and the vector v from the attachment section 23' towards the connection portion 25 may be in the range of 10 degrees - 85 degrees or in the range of 59 degrees - 79 degrees. According to the illustrated embodiment, the angle a1 is measured in a plane perpendicular to the plane containing the axis of rotation, i.e., the rotational plane rP of the cutting tool 5.

[0068] Unless otherwise indicated, reference is made simultaneously to FIGS. 1-5 below. According to the illustrated embodiment, the drive shaft 3 of the cutting tool assembly 1 has flexibility, in which case the tubular elongate support 23 has a curved portion 26. Further, according to the illustrated embodiment, the curved portion 26 is disposed between the mounting section 23' and the cutting tool 5. Further, according to the illustrated embodiment, a portion 24 of the tubular elongate support 23 located between the mounting section 23' and the connecting portion 25 is substantially straight.

[0069] According to a further embodiment, the portion 24 of the tubular elongate support 23 located between the mounting section 23' and the connecting portion 25 may also comprise one or more curved portions. Further, according to some embodiments, the drive shaft 3 of the cutting tool assembly 1 may be rigid, in which case all sections of the tubular elongate support 23 are substantially straight. According to such embodiments, as with the other embodiments described herein, the cutting tool assembly 1 may comprise one or more additional gear assemblies 28 in addition to those shown in FIGS. 2 and 5.

[0070] As shown in FIGS. 1-5, according to the illustrated embodiment, the cutting guard 7 comprises a first edge portion 13 disposed radially outside the cutting tool 5, in which case the first edge portion 13 connects the first and second guard portions 11, 12. According to the illustrated embodiment, the tubular elongate support 23 is attached to the first edge portion 13 of the guard 7. However, the guard 7 may be attached to the tubular elongate support 23 in another manner.

[0071] As shown in FIG. 3, according to the illustrated embodiment, the first edge portion 13 has an arc shape with a radius of curvature r13, and the radius of curvature r13 is approximately 100% of the distance D13 between the rotation axis ax and the first edge portion 13. According to a further embodiment, the radius of curvature r13 of the first edge portion 13 may be in the range of 80% - 130% of the distance D13 between the rotation axis ax and the first edge portion 13. The distance D13 between the rotation axis ax and the first edge portion 13 may be measured between the rotation axis ax of the cutting tool 5 and the radially outer portion of the first edge portion 13.

[0072] Also, according to the illustrated embodiment, the arc length L13 of the first edge portion 13 is approximately 155% of the distance D13 between the rotation axis ax and the first edge portion 13. According to a further embodiment, the arc length L13 of the first edge portion 13 may be in the range of 50% - 500% of the distance D13 between the rotation axis ax and the first edge portion 13, or may be in the range of 100% - 250%.

[0073] In this way, the first edge portion 13 can effectively prevent the scattering of residues during cutting from the cutting tool 5, as well as other types of objects and particles during the operation of the cutting tool assembly 1.

[0074] Furthermore, as shown in FIGS. 1 - 5, according to the illustrated embodiment, the guard 7 includes a second edge portion 15. According to the illustrated embodiment, the second edge portion 15 is disposed opposite to the first edge portion 13 and also connects the first and second guard portions 11, 12. According to a further embodiment, the guard 7 may include an open section radially outside the cutting tool 5 at a position opposite to the first edge portion 13.

[0075] The fact that each of the first and second edge portions 13, 15 according to the illustrated embodiment connects the first and second guard portions 11, 12 means that the guard 7 surrounds the cutting tool 5 in a plane P2 parallel to the rotation axis ax, as shown in FIG. 4.

[0076] As shown in FIG. 3, according to the illustrated embodiment, the second edge portion 15 has an arc shape with a radius of curvature r15, and the radius of curvature r15 is approximately 100% of the distance D15 between the rotation axis ax and the second edge portion 15. According to a further embodiment, the radius of curvature r15 of the second edge portion 15 may be within the range of 80% - 130% of the distance D15 between the rotation axis ax and the second edge portion 15.

[0077] According to the illustrated embodiment, the arc length L15 of the second edge portion 15 is approximately 57% of the distance D15 between the rotation axis ax and the second edge portion 15. According to a further embodiment, the arc length L15 of the second edge portion 15 may be within the range of 3% - 180% of the distance D15 between the rotation axis ax and the second edge portion 15, or within the range of 25% - 90%. The distance D15 between the rotation axis ax and the second edge portion 15 may be measured between the rotation axis ax of the cutting tool 5 and the radially outer portion of the second edge portion 15.

[0078] FIG. 4 shows a plane P1 including the rotation axis ax of the cutting tool 5. Since the plane P1 includes the rotation axis ax, the plane P1 extends through the rotation axis ax and is parallel to the rotation axis ax. Further, according to the illustrated embodiment, the plane P1 extends through the tubular elongated support 23 of the cutting tool assembly 1.

[0079] As can be seen in FIGS. 1 - 5, according to the illustrated embodiment, the first and second guard portions 11, 12 and the first and second edge portions 13, 15 integrally form a disk-shaped object having one notch section on each side of the plane P1 including the rotation axis ax.

[0080] In other words, as shown in FIG. 4, according to the illustrated embodiment, the guard 7 has a first aperture 21 on a first face S1 of a plane P1 including the rotation axis ax, and a second aperture 22 on a second face S2 of the plane P1 including the rotation axis ax. Further, as can be seen in FIG. 4, the cutting tool 5 has an effective radius r greater than a distance D21 from the rotation axis ax to an edge 21' of the first aperture 21, and an effective radius r greater than a distance D22 from the rotation axis ax to an edge 22' of the second aperture 22. In this way, the cutting tool assembly 1 can be used conveniently, efficiently, and safely to cut plants around the edge forming part 50, as will be further described below.

[0081] According to the illustrated embodiment, the plane P1 forms a symmetry plane of the guard 7, in which case the design and dimensions of the guard 7 on the second face S2 of the plane P1 substantially correspond to the design and dimensions of the guard 7 on the first face S1 of the plane P1. In other words, according to the illustrated embodiment, the design and dimensions of the guard 7 on the second face S2 of the plane P1 substantially correspond to a mirror image of the design and dimensions of the guard 7 on the first face S1 of the plane P1. Therefore, the plane P1 may also be referred to as the symmetry plane P1 of the guard 7 when referred to herein.

[0082] The edges 21', 22' of the first and second apertures 21, 22 form the boundary surfaces of a notch section of the disk-shaped object (i.e., the disk-shaped object formed by the first and second guard parts 11, 12 and the first and second edge parts 13, 15 of the guard 7) described above. As can be best seen in FIGS. 3 and 4, according to the illustrated embodiment, the edges 21', 22' of the first and second apertures 21, 22 are concave in a plane parallel to the rotation plane of the cutting tool 5, and each of them has a radius of curvature greater than the effective radius r of the cutting tool 5. However, according to further embodiments, the guard 7 and the first and second apertures 21, 22 may have other designs.

[0083] As shown in FIG. 5, according to the illustrated embodiment, the second edge portion 15 forms a ground engaging portion for maintaining a predetermined distance D15 between the rotation axis ax and the ground surface 52 by abutting contact against the ground surface 52.

[0084] More specifically, in the example of FIG. 5, the edge forming portion 50 includes a vertical section 53 and a ground surface 52 that is located adjacent to the vertical section 53 and is positioned below the vertical section 53 when viewed with respect to the local gravity vector gv. The vertical section 53 of the edge forming portion 50 is substantially parallel to the local gravity vector. Further, FIG. 5 shows a second ground surface 54.

[0085] As described above, in FIG. 5, the mowing tool assembly 1 is shown in its intended use position with respect to the edge forming portion 50. In the intended use position of the mowing tool assembly 1 according to the embodiments herein, the rotation plane rP of the mowing tool 5 is substantially parallel to the local gravity vector gv. In other words, the rotation axis ax of the mowing tool 5 is substantially perpendicular to the local gravity vector gv when the mowing tool assembly 1 according to the embodiments herein is in its intended use position. Further, according to the illustrated embodiment, the mowing tool assembly 1 is configured such that the rotation axis ax of the mowing tool 5 faces in the direction towards the user of the mowing tool assembly 1, as further described herein.

[0086] As described above and as can also be seen in FIG. 5, the second edge portion 15 can be used to maintain a predetermined distance D15 between the rotation axis ax and the ground surface 52 by abutting contact against the ground surface 52. Further, the first guard portion 11 is configured to maintain a predetermined distance D11 between the rotation plane rP of the mowing tool 5 and the substantially vertical section 53 of the edge forming portion 50 by abutting contact against the substantially vertical section 53 of the edge forming portion 50.

[0087] Accordingly, due to the features of the cutting tool assembly 1, the user can guide the cutting tool assembly 1 so that the guard 7 and the cutting tool 5 are moved laterally in both directions along the edge forming portion 50, enabling the user to cut plants in the generally vertical section 53 of the edge forming portion more safely, quickly, and conveniently. Since the first guard portion 11 can be used to maintain a predetermined distance D11 between the rotational plane rP of the cutting tool 5 and the generally vertical section 53 of the edge forming portion 50, it is possible to obtain a predetermined uniform cutting height in the generally vertical section 53 of the edge forming portion 50. The second edge portion 15 is used to maintain a predetermined distance D15 between the rotational axis ax and the ground surface 52, thereby making it possible to avoid the scattering of substances (such as sand) from the ground surface 52.

[0088] In the example shown in FIG. 5, the user may stand on the second ground surface 54 shown in FIG. 5. However, even if it is not optimal, the user may stand on the ground surface 52 and may utilize the second guard portion 12 to maintain a predetermined distance between the rotational plane rP of the cutting tool 5 and the vertical section 53 of the edge forming portion 50.

[0089] According to the illustrated embodiment, the predetermined distances D11, D15 are fixed predetermined distances D11, D15. However, according to further embodiments, one or more portions of the guard 7 may be arranged adjustably with respect to the cutting tool 5 so that one or both of the predetermined distances D11, D15 can be adjusted by the user.

[0090] FIG. 6 shows a second perspective view of the cutting tool assembly 1 described with reference to FIGS. 1 - 5. As can be best seen in FIG. 6, according to the illustrated embodiment, the first guard portion 11 of the guard 7 includes a central opening 33. The central opening 33 overlaps at least a portion of the cutting tool 5 when viewed from the first direction shown in FIG. 1. The rotational axis of the cutting tool 5 extends through the central opening 33.

[0091] FIG. 7 shows a cross-section of the cutting tool 5 of the cutting tool assembly 1, the gear assembly 28, and a portion of the tubular elongate support 23 according to the embodiment shown in FIGS. 1-6. Further, in FIG. 7, a portion of the drive shaft 3 can be seen.

[0092] As described above, the drive shaft 3 may be flexible. According to such an embodiment, the drive shaft 3 may include a wound high-tension wire, a coil-shaped body, etc. that are designed to transmit rotational motion and power through a curved path. According to the illustrated embodiment, the tubular elongate support 23 includes a liner 35 that acts as a protective outer casing for the drive shaft 3 so that the drive shaft 3 can rotate smoothly even in the curved section of the tubular elongate support 23.

[0093] According to the illustrated embodiment, the gear assembly 28 includes a first bevel gear 37 connected to the drive shaft 3 and a second bevel gear 38 connected to the trimmer unit shaft 39. The cutting tool shaft 39 includes a mounting section 41 for mounting the cutting tool 5 to the cutting tool shaft 39. According to the illustrated embodiment, the cutting tool 5 is attached to the mounting section 41 of the cutting tool shaft 39 by a fastener 43. According to the illustrated embodiment, the fastener 43 is a nut screwed onto the threaded portion of the cutting tool shaft 39. According to a further embodiment, the cutting tool 5 may be attached to the mounting section 41 of the cutting tool shaft 39 in another manner (e.g., by another type of fastener such as a bolt).

[0094] The central opening 33 shown in FIG. 6 enables the user to access the fastener 43 in a quick and straightforward manner without the need to disassemble the guard 7 of the cutting tool assembly 1. According to the illustrated embodiment, the gear assembly 28 is attached to the second guard portion 12 of the guard 7 at the attachment section 45 of the gear assembly 28. The attachment section 45 of the gear assembly 28 is also shown in FIG. 5. The gear assembly 28 may be attached to the second guard portion 12 of the guard 7 by an elongate fastening element protruding into the attachment section 45 of the gear assembly 28.

[0095] According to the illustrated embodiment, the central opening 33 is circular in shape and has a diameter smaller than the diameter of the cutting tool 5 measured in a direction perpendicular to the axis of rotation ax of the cutting tool 5. A user of the cutting tool assembly 1 according to the illustrated embodiment can remove the cutting tool 5 from the guard 7 by removing the fastener 43 from the threaded portion of the cutting tool shaft 39 and removing an elongate fastener protruding into the attachment section 45 of the gear assembly 28. The user can then remove the cutting tool 5 from the guard 7 through one of the first and second apertures 21, 22 shown in FIGS. 4 and 5. In this way, the user can remove the cutting tool 5 from the guard 7 in a quick and straightforward manner without the need to disassemble the guard 7 of the cutting tool assembly 1.

[0096] The user may wish to remove the cutting tool 5 from the guard 7, for example, when performing service and maintenance on the cutting tool 5, when wishing to clean the cutting tool 5 and / or the guard 7, and / or when wishing to replace the trimmer line 51 of the cutting tool 5. However, according to the illustrated embodiment, the user can also replace the trimmer line 51 of the cutting tool 5 without the need to remove the cutting tool 5 from the guard 7 by accessing the cutting tool 5 through one or both of the first and second apertures 21, 22 shown in FIGS. 4 and 5.

[0097] As can be understood from the above, the cutting tool shaft 39 is configured to rotate around the rotation axis ax of the cutting tool 5 during operation. The first and second bevel gears 37, 38 form a bevel gear assembly 27, in which case the cutting tool 5 is connected to the drive shaft 3 via the bevel gear assembly 27. The bevel gear assembly 27 enables the rotation axis ax3 of the drive shaft 3 to be angled with respect to the rotation axis ax of the cutting tool 5. Therefore, the bevel gear assembly 27 reduces the need for the tubular elongated support 23 to bend significantly. According to a further embodiment, the cutting tool assembly 1 may comprise another type of gear assembly, such as a spur gear assembly.

[0098] Hereinafter, reference will be made simultaneously to FIGS. 1-7 for explanation. The expression "substantially parallel", when used in this specification, may include that the angle between the objects referred to is less than 10 degrees or less than 7 degrees.

[0099] The expression "substantially perpendicular to" may include that the angle between the objects referred to is within the range of 80 degrees - 100 degrees or within the range of 83 degrees - 97 degrees when used in this specification.

[0100] The expression "substantially linear", when used in this specification, may include that the object referred to deviates by less than 10% from the planar shape. The expression "substantially perpendicular", when used in this specification, may include that the angle between the object referred to and the local gravity vector gv at the position of the cutting tool assembly 1 is less than 20 degrees or less than 10 degrees.

[0101] The expression "substantially corresponding", when used in this specification, may include that the aspects, objects, distances, or dimensions referred to deviate from each other by less than 10%. The above are examples of various embodiments, and it can be understood that the present invention is defined only by the appended independent claims. Those skilled in the art can understand that the embodiments may be modified without departing from the scope of the present invention as defined by the appended independent claims, and that various features of the embodiments may be combined to create embodiments other than those described herein.

[0102] As used herein, the term "comprising" is open-ended and includes one or more of the recited features, elements, steps, components, or functions, but does not exclude the presence or addition of one or more other features, elements, steps, components, functions, or groups thereof.

Claims

1. An edge cutting tool assembly (1) configured to cut plants around an edge forming part (50), said assembly (1) comprising a drive shaft (3) and a cutting tool (5) connected to said drive shaft (3), said cutting tool (5) is configured to rotate around a rotation axis (ax) by said drive shaft (3) such that a radially outer part (5') of said cutting tool (5) orbits a circular path (c) in a rotation plane (rP), said assembly (1) comprises a guard (7) having a first guard part (11) covering a part of a region (A) formed inside said circular path (c) when viewed from a first direction (d1) parallel to said rotation axis (ax), and a second guard part (12) covering a part of said region (A) when viewed from a second direction (d2) parallel to said rotation axis (ax) and opposite to said first direction (d1), said guard (7) comprises a second edge part (15) arranged opposite to said first edge part (13), said second edge part (15) forms a ground engaging part for maintaining a predetermined distance (D15) between said rotation axis (ax) and a ground surface (52) by abutting contact with the ground surface (52), assembly (1).

2. Each of said first guard part (11) and said second guard part (12) covers more than 30% or more than 50% of said region (A) when viewed from said first direction (d1) and said second direction (d2) respectively, the assembly (1) according to claim 1.

3. Each of said first guard part (11) and said second guard part (12) overlaps more than 70% of the other of said first guard part (11) and said second guard part (12) when viewed from said first direction (d1) and said second direction (d2) respectively, the assembly (1) according to claim 1 or 2.

4. said cutting tool (5) comprises a tubular elongate support (23), said drive shaft (3) is arranged inside said tubular elongate support (23), said drive shaft (3) comprises a connection part (25) for connecting an output shaft (4) of a power unit (6) to said drive shaft (3), the assembly (1) according to any one of claims 1 to 3.

5. The guard (7) is attached to the attachment section (23') of the tubular elongate support (23), and the angle (a1) between the rotational plane (rP) and the vector (v) from the attachment section (23') towards the connection portion (25) is within the range of 10 degrees - 85 degrees or within the range of 59 degrees - 79 degrees, the assembly (1) according to claim 4.

6. The drive shaft (3) has flexibility and the tubular elongate support (23) has a curved portion (26), the assembly (1) according to claim 4 or 5.

7. Each of the connection portion (25) and the first guard portion (11) is arranged on the first face (S1') of the rotational plane (rP), the assembly (1) according to any one of claims 4 to 6.

8. The cutting guard (7) comprises a first edge portion (13) arranged radially outside the cutting tool (5), and the first edge portion (13) connects the first guard portion (11) and the second guard portion (12), the assembly (1) according to any one of claims 1 to 7.

9. The second edge portion (15) connects the first guard portion (11) and the second guard portion (12), the assembly (1) according to any one of claims 1 to 8.

10. The second edge portion (15) is in the shape of an arc having a radius of curvature (r15) within the range of 80% - 130% of the distance (D15) between the rotational axis (ax) and the second edge portion (15), the assembly (1) according to any one of claims 1 to 9.

11. The guard (7) surrounds the cutting tool (5) in a plane (P2) parallel to the rotational axis (ax), the assembly (1) according to any one of claims 1 to 10.

12. The guard (7) comprises a first aperture (21) in the first face (S1) of a plane (P1) containing the rotational axis (ax), and the cutting tool (5) has an effective radius (r) greater than the distance (D21) from the rotational axis (ax) to the edge (21') of the first aperture (21), the assembly (1) according to any one of claims 1 to 11.

13. The guard (7) comprises a second aperture (22) in a second face (S2) of the plane (P1), and the cutting tool (5) has an effective radius (r) greater than the distance (D22) from the axis of rotation (ax) to the edge (22') of the second aperture (22), the assembly (1) according to claim 12.

14. The cutting tool (5) comprises a bevel gear assembly (27), and the cutting tool (5) is connected to the drive shaft (3) via the bevel gear assembly (27), the assembly (1) according to any one of claims 1 to 13.

15. An electric tool (2), a power unit (6) comprising an output shaft (4) and a motor (8) configured to rotate the output shaft (4), an edge cutting tool assembly (1) according to any one of claims 1 to 14, and the drive shaft (3) of the edge cutting tool assembly (1) is connected or connectable to the output shaft (4) of the power unit (6), an electric tool (2).

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