WO2013187812A1

WO2013187812A1 - Rotary attachment of a power driven garden tool

Info

Publication number: WO2013187812A1
Application number: PCT/SE2012/050634
Authority: WO
Inventors: Matias Nybacka; Ricky Sundkvist; Stefan Valfridsson
Original assignee: Husqvarna Ab
Priority date: 2012-06-13
Filing date: 2012-06-13
Publication date: 2013-12-19
Also published as: DE112012006534T5

Abstract

Embodiments herein relate to a rotary attachment of a power driven garden tool, which rotary attachment (100) comprises a core member (110) having a cylindrical configuration and an envelope surface (111). The core member (110) is arranged to be rotatably coupled to a rotary attachment receiving portion of the power driven garden tool, so as to be rotatable about a central longitudinal axis of rotation (112). The rotary attachment also comprises a working tool (120), attached to the core member (110) so as to rotate therewith. The rotary attachment is characterized in that the core member (110) comprises at least one air gap providing element (115) extending between two axially spaced apart positions along the envelope surface (111) of the core member (110).

Description

ROTARY ATTACHMENT OF A POWER DRIVEN GARDEN TOOL

TECHNICAL FIELD

Embodiments herein relate to rotary attachments of power driven garden tools, which rotary attachments comprise a core member having a cylindrical configuration, and a working tool, attached to the core member.

BACKGROUND OF THE INVENTION

A variety of rotary attachments of power driven garden tools exist on the market. An example of such a rotary attachment is a broom brush roller which may be attached to a ride-on lawn mower. Other examples include walk-behind cultivators and tillers. Rotary attachments of this kind may also be connected to hand-held garden tools.

A common problem for the above described types of rotary attachments is that flexible elongate members, such as grass, tiny twigs and different types of strings or threads, may become tightly wrapped around the core member of the rotary attachment. Such entwined flexible elongate members are generally hard to disentangle. When an operator of the power driven garden tool performs a maintenance operation of the tool, he or she generally uses a separate cutting tool, such as a knife, to cut off and remove the entwined flexible elongate members. Then, the operator needs to exert a reasonable amount of pressure towards the flexible elongate member and the core member in order to cut off the flexible elongate member. There is a risk that the core member becomes damaged, and furthermore, the cutting operation may be difficult and troublesome. There exist arrangements aimed at simplifying the maintenance of a rotary attachment of a cleaning tool by means of reducing the risk of flexible elongate members becoming tightly wrapped around the rotary attachment. However, those kinds of arrangements are generally complicated, expensive and sensitive, and have proven not to be suitable for rotary attachments arranged to perform rough operations such as tilling and/or ground sweeping.

Accordingly, there remains a need for an alternative arrangement providing a simplified maintenance operation of rotary attachments of power driven garden tools. SUMMARY OF THE INVENTION

Embodiments herein aim to provide an arrangement providing a simplified maintenance operation of rotary attachments of power driven garden tools.

This is provided through a rotary attachment of a power driven garden tool, which rotary attachment comprises a core member, having a cylindrical configuration and an envelope surface. The core member is arranged to be rotatably coupled to a rotary attachment receiving portion of the power driven garden tool, so as to be rotatable about a central longitudinal axis of rotation. The rotary attachment furthermore comprises a working tool. The working tool is attached to the core member so as to rotate therewith. The rotary attachment comprises at least one air gap providing element extending between two axially spaced apart positions along the envelope surface of the core member. The presence of an air gap providing element makes it easier to remove any flexible elongate element which has unintentionally become entwined around the circumference of the core member during operation of the power driven garden tool.

The air gap providing element, extending between two axially spaced positions along the envelope surface ensures that somewhere along the circumference of the core member there is a distance between the flexible elongate element and the core member.

A cutting tool, such as a knife may then be used to cut off the flexible elongate element in a position where there is an air gap between the flexible elongate element and the core member. Thanks to the air gap, less effort is needed to cut off the flexible elongate element.

When the edge of the cutting tool is pressed towards the flexible elongate member in a position where there is an air gap between the flexible elongate member and the core member, the pressed portion of the flexible elongate member will move slightly towards the core member. Such a movement would not have been possible if there would have been no air gap. The movement ensures that there is an extra tension in the extension direction of the flexible elongate member, so as to ease the cutting operation. According to an embodiment, the air gap providing element comprises at least one guiding surface neighbouring a portion of the envelope surface.

The guiding surface functions as a support and guiding means for a cutting blade of a cutting tool used to cut off flexible elongate members which may become wrapped around the core member during use of the garden tool. The guiding surface can be used to guide the cutting blade across the flexible elongate member. Thereby, the risk of slipping is reduced and the cut becomes distinct. Thereby the cutting operation is rendered more efficient than if no air gap providing element would have been present.

According to an embodiment, the air gap providing element is defined by a ridge protruding from the envelope surface of the core member.

The provision of an air gap providing element embodied as a ridge minimizes the risk of debris, dust and soil squeezing into the air gap providing element. Cleaning and maintenance of the rotary attachment is thereby facilitated.

BRIEF DESCRIPTION OF THE DRAWINGS

In the following, embodiments herein will be described in greater detail by way of example only with reference to attached drawings, in which

Fig. 1 is a perspective view of a portion of a power driven garden tool, with a rotary attachment embodied as a broom brush roller,

Fig. 2 is a perspective view of the rotary attachment of Fig. 1 ,

Fig. 3 is a perspective view of a core member of the rotary attachment of Fig. 2,

Fig. 4 is a perspective view of a portion of a power driven garden tool, with a rotary attachment embodied as a tiller/cultivator,

Fig. 5 is a perspective view of a rotary attachment of Fig. 4,

Fig. 6 is a perspective view of a portion of the rotary attachment of Fig. 5,

Fig. 7 is a schematic cross sectional view of a core member according to an embodiment, Fig. 8 is a detail view of a portion of the core member of Fig. 7,

Fig. 9 is a detail view of a portion of the core member of Fig. 7, and a portion of a flexible elongate member,

Fig. 10 is a schematic cross sectional view of a core member according to an

embodiment, Fig. 11 is a detail view of a portion of the core member of Fig. 10, and a portion of a flexible elongate member,

Fig. 12 is a schematic cross sectional view of a core member according to an

embodiment,

Fig. 13 is a detail view of a portion of the core member of Fig. 12, and a portion of a flexible elongate member,

Fig. 14 is a schematic cross sectional view of a core member according to an

embodiment,

Fig. 15 is a schematic cross sectional view of a core member according to an

embodiment,

Fig. 16 is a schematic cross sectional view of a core member according to an

embodiment,

Fig. 17 is a schematic cross sectional view of a core member according to an

embodiment.

Still other objects and features of embodiments herein will become apparent from the following detailed description considered in conjunction with the accompanying drawings. It is to be understood, however, that the drawings are designed solely for purposes of illustration and not as a definition of the limits hereof, for which reference should be made to the appended claims. It should be further understood that the drawings are not necessarily drawn to scale and that, unless otherwise indicated, they are merely intended to conceptually illustrate the structures and procedures described herein.

DESCRIPTION OF PREFERRED EMBODIMENTS First embodiment - broom brush roller

Referring to Fig. 1 , a rotary attachment 100 embodied as a broom brush roller 100 is shown. The power driven garden tool to which the broom brush roller is arranged to be coupled may be e.g. a ride-on lawnmower. The broom brush roller is attached to a rotary attachment receiving portion of the garden tool, and is rotatable relative to a body portion of the garden tool.

The rotary attachment is rotatable about an axis of rotation 112. The axis of rotation 112 defines a longitudinal or axial direction of the rotary attachment 100. According to the embodiment shown in Figs. 1 -3, the rotary attachment 100 comprises a core member 110 embodied as a roller 110 and a working tool 120 embodied as a set of brush bristles 120.

The roller has a first end 113, a second end 114 and an envelope surface 111 .

The brush bristles extend in a radial direction from the envelope surface 111 of the roller. In the embodiment shown in Fig. 3, end portions of the brush bristles are inserted into holes formed in the envelope surface of the roller, so as to attach the brush bristles to the roller.

In order to optimize the performance of the broom brush roller, the bristles may be arranged in helically shaped rows.

According to embodiments herein, the core member 110 comprises at least one air gap providing element 115. The core member shown in Fig. 3 comprises an air gap providing element embodied as a ridge 115. In the embodiment shown in Figs. 1 -3, the ridge 115 extends from the first end 113 of the roller to the second end 114 of the roller 110. The ridge protrudes from the envelope surface 111 of the roller.

Alternatively, the air gap providing element 115 may extend only along a portion of the core member. Several air gap providing elements may be arranged in sequence in the longitudinal direction.

Schematic cross sectional views of an air gap providing element 115 according to the one of Figs. 1 -3 are shown in Figs. 7-9.

According to embodiments herein, the air gap providing element 115 comprises at least one guiding surface 116. The guiding surface functions as a support and guiding means for a cutting blade of a cutting tool used to cut off flexible elongate members 200 which may become wrapped around the core member during use of the garden tool. The guiding surface 116 borders on a first guiding surface neighboring portion 111 a of the envelope surface.

An envelope surface neighboring portion 116a of the guiding surface 116 has an extension direction that differs significantly from the extension direction of the first guiding surface neighboring portion 111a.

According to an embodiment, the radius of curvature of the corner between the envelope surface neighboring portion 116a of the guiding surface 116 and the first guiding surface neighboring portion 111a is less than 0.4 mm.

The guiding surface 116 is preferably smooth. Thereby, it is easy for an operator to move a cutting blade along the guiding surface when cutting off entwined flexible elongate members 200.

The air gap providing element disclosed in Figs. 1 -3 and in Figs. 7-9 comprises two opposed guiding surfaces 116, which together define the ridge 115.

Function of the air gap providing element

As the broom brush roller rotates, the brush bristles sweep away gravel and dirt present on the ground surface that is treated. During operation, the brush bristles may

unintentionally catch any flexible elongate members present on the ground surface. The flexible elongate members, such as blades of grass, ropes, strings, twigs etc. may then become tightly wrapped around the circumference of the core member.

As long as the circumference of the core member is continuous, the flexible elongate members will abut on the envelope surface all the way around the circumference of the core member. However, the air gap providing element 115 defines an irregularity in the envelope surface 111 . A flexible elongate member 200 which is tightly wound around the core member 110 will extend such that it follows the shortest way possible around the circumference of the core member. In the embodiment shown in Figs. 1 -3 and Figs. 7-9, this means that the flexible elongate member 200 will take a short cut between the edge of the ridge 115 and a portion of the envelope surface which is positioned at a certain distance from the ridge. Thereby, an air gap 130 is provided between the flexible elongate member 200 and the core member 110, as shown in Fig. 9.

A cutting tool, such as a knife may then be used to cut off the flexible elongate element in a position where there is an air gap 130 between the flexible elongate element and the core member. Thanks to the air gap, less effort is needed to cut off the flexible elongate member 200.

When the edge of the cutting tool is pressed towards the flexible elongate member 200 in a position where there is an air gap between the flexible elongate member 200 and the core member 110, the pressed portion of the flexible elongate member 200 will move slightly towards the core member. Such a movement would not have been possible if there would have been no air gap. The movement ensures that there is an extra tension in the extension direction of the flexible elongate member 200, so as to ease the cutting operation.

Furthermore, the presence of an air gap prevents the cutting blade from touching the envelope surface until all fibers which may be present in the flexible elongate member are cut off. Thereby, the cutting operation is rendered more efficient than if the envelope surface would abut on the portion of the flexible elongate member on which the cutting operation is performed.

The presence of an air gap also makes it easier to adjust the position of the cutting blade so as to obtain a favorable cutting position. It makes it easier to reach the flexible elongate member from different directions.

A guiding surface 116 of the air gap providing member 115 can be used to guide the cutting blade across the flexible elongate member 200. Thereby, the risk of slipping is reduced and the cut becomes distinct. Thereby the cutting operation is rendered more efficient than if no air gap providing element would have been present. Second embodiment - tiller/cultivator

Referring to Fig. 4, a rotary attachment 100 embodied as a cultivator unit 100 is shown. The power driven garden tool to which the cultivator unit 100 is arranged to be coupled may e.g. be a walk behind garden tool, a hand-held garden tool or a ride-on garden tool.

The cultivator unit may comprise one or several core members 110 to which the cultivator blades 120 are attached.

Fig. 5 illustrates a core member to which a cultivator blade is attached by means of a working tool attachment member 140.

Fig. 6 illustrates a core member 110 and a working tool attachment member 140. In the embodiment shown in Figs. 4-6, the working tool attachment member 140 and the core member 110 are integrally formed.

The core member shown in Figs. 5 and 6 comprises three air gap providing elements. The number of air gap providing elements can be one or more.

The appearance and functionality of the air gap providing elements of the cultivator unit are similar to the ones of the broom brush roller embodiment.

Schematic cross sectional views of an air gap providing element 115 according to the one of Figs. 4-6 are shown in Figs. 7-9. Several air gap providing elements 115 may be arranged in sequence in the longitudinal direction. Working tools 120, such as cultivator blades 120, may be arranged between these sequentially arranged air gap providing elements 115.

Air gap providing members 115 could also be arranged on an envelope surface of the working tool attachment member 140.

In the embodiments shown in Figs. 1 -9 the air gap providing elements are configured as ridges which extend from the envelope surface of the core member. In order to achieve an adequate air gap between an entwined flexible elongate member 200 and the envelope surface of the core member, the ridge may have a height 115h of at least 1.5 mm in a radial direction. As shown in Figs. 7-9, a ridge may be defined by two opposing guiding surfaces 116.

However, an air gap providing element 115 may also be defined by means of a ridge having another cross sectional shape, such as a square shape or a rounded shape. In Fig. 16, two exemplary ridge shapes according to embodiments herein are schematically shown in cross section.

As shown in Figs. 10-11 and in Fig. 14, 15 and 17, the air and air gap providing element may also be defined by a groove 115 formed in the core member. The groove may have a variety of shapes. The rectangular groove 115 shown in Figs. 10- 11 comprises two guiding surfaces 116 adjoined by a bottom surface.

The groove may also have a rounded shape or a V shape, as shown in Fig. 14. As shown in Fig. 11 , when the air gap providing element 115 is a groove, an air gap 130 is provided since the entwined flexible elongate member 200 will take a shortcut between two portions of the envelope surface neighboring the groove.

As shown in Figs. 12-13, an air gap providing element may also be defined by means of one guiding surface 116, extending between a first portion of the envelope surface and a second portion of the envelope surface. The first portion and the second portion may be arranged at different distances from the axis of rotation of the core member. Fig. 13 illustrates how an air gap is provided between an entwined flexible elongate member 200 and the core member in that case.

According to embodiments herein the guiding surface or surfaces of an air gap providing element is/are preferably smooth. According to some embodiments herein, the core member has an essentially circular cross section. However the core member may have a variety of alternative cross sectional shapes. According to some embodiments, the air gap providing member extends essentially linearly in a direction which is parallel to the axis of rotation of the rotary attachment.

According to other embodiments, the air gap providing member extends helically around the core member.

According to some embodiments, the air gap providing member is formed integrally with the core member. Alternatively, the air gap providing member may be a separate part which is attached to the core member.

The above-described embodiments may be varied within the scope of the following claims. Thus, while there have been shown and described and pointed out fundamental novel features of the embodiments herein, it will be understood that various omissions and substitutions and changes in the form and details of the devices illustrated, and in their operation, may be made by those skilled in the art. For example, it is expressly intended that all combinations of those elements and/or method steps which perform substantially the same function in substantially the same way to achieve the same results are equivalent. Moreover, it should be recognized that structures and/or elements and/or method steps shown and/or described in connection with any disclosed form or embodiment herein may be incorporated in any other disclosed or described or suggested form or embodiment as a general matter of design choice.

Claims

1 . A rotary attachment of a power driven garden tool, which rotary attachment (100) comprises

a core member (110), having a cylindrical configuration and an envelope surface (111 ), wherein the core member (110) is arranged to be rotatably coupled to a rotary attachment receiving portion of the power driven garden tool, so as to be rotatable about a central longitudinal axis of rotation (112),

a working tool (120) attached to the core member (110) so as to rotate therewith, characterized in that the core member (110) comprises at least one air gap providing element (115) extending between two axially spaced apart positions along the envelope surface (111 ) of the core member (110).

2. A rotary attachment according to claim 1 , wherein the air gap providing element (115) comprises at least one guiding surface (116) neighboring a portion of the envelope surface (111 ).

3. A rotary attachment according to any of the previous claims, wherein the air gap

providing element (115) is defined by a ridge (115) protruding from the envelope surface (111 ) of the core member (110).

4. A rotary attachment according to claim 3 wherein the ridge (115) extends at least 1 .5 mm from the envelope surface of the core member.

5. A rotary attachment according to any of the preceding claims, wherein the air gap providing element (115) extends continuously from a first (113) end to a second end

(114) of the core member (110).

6. A rotary attachment according to any of the preceding claims wherein the air gap providing element (115) extends essentially linearly parallel to the axis of rotation (112) of the core member.

7. A rotary attachment according to any of claims 1 -5, wherein the air gap providing element (115) extends helically between the two axially spaced apart positions along the envelope surface (111 ) of the core member (110).

8. A rotary attachment according to any of the preceding clams, wherein the working tool (120) extends in a radial direction from the envelope surface (111 ) of the core member (110).

9. A rotary attachment according to any of the preceding claims, wherein the core

member (110) is a broom brush roller (110) and wherein the working tool (120) comprises bristles of a broom brush.

10. A rotary attachment according to any of claims 1 -8, wherein the working tool (120) is a tiller blade (120).

1 1 . A rotary attachment according to any of claims 1 -8, wherein the working tool is a

cultivator blade (120).

12. A rotary attachment according to any of the preceding claims, wherein the power driven garden tool is a walk-behind garden tool.

13. A rotary attachment according to any of claims 1 -11 , wherein the power driven garden tool is a handheld garden tool.

14. A rotary attachment according to any of claims 1 -11 , wherein the power driven garden tool is a ride-on garden tool.

15. A power driven garden tool comprising a rotary attachment according to any of the preceding claims.