GB2359475A

GB2359475A - Vegetation cutting device

Info

Publication number: GB2359475A
Application number: GB0105600A
Authority: GB
Inventors: John Toy
Original assignee: Individual
Current assignee: Individual
Priority date: 2001-03-07
Filing date: 2001-03-07
Publication date: 2001-08-29
Also published as: GB0105600D0

Abstract

A vegetation cutting device 10 includes a rotor 12 and at least one blade 13, 14 which may have one or two cutting edges. Rotor 12 includes blade engagement means 12a which allow blade 13, 14 to be engaged by effecting a sliding of the blade 13, 14 relative to rotor 12. The blade engagement means 12a may be two mutually facing channels G formed on the rotor 2 into which the blade 13, 14 is introduced. The distance between channels G may decrease towards the outer end of the rotor 12. The assembly 10 allows simple replacement of blades 13,14.

Description

2359475

PATENTS ACT 1977 A10275GB-DJL/ACL Title: Improvements Relating to Vegetation Cutting Devices Description of Invention

This invention relates to a vegetation cutting device such as a lawn mower, particularly but not exclusively a lawn mower of the kind in which cutting is effected by a blade which rotates in use about a generally vertical c axis.

A blade in a vegetation cutting device such as a lawn mower usually has one or more cutting edges which become blunt with use, particularly if the cutting edges encounter obstacles such as stones whilst in use. In order to improve the performance of a cutting device including at least one blunt cutting edoe it is known to sharpen the cutting edge or provide the cuttine, edce on a c c c C) C Y blade which may be replaced with a new, sharp, blade.

Where is a replaceable blade is used, it is known to attach the blade to a rotor by means of fasteners such as screws.

According to a first aspect of the invention 1 provide a vegetation cutting device including a rotor and blade assembly, the assembly including at least one blade with at least one cuttino edge, characterised in that the rotor includes blade engagement formation means adapted to engage the blade to retain the blade, in use, relative to the rotor, the blade engagement formation means and the blade being configured to permit the blade to be engaged with the rotor by effecting sliding of the blade relative to the rotor.

Thus assembly of and removal of the blade fi.om the rotor may be achieved by effecting sliding movement of the blade relative to the rotor in or out of engagement with the blade engaging formation means.

Thus, by virtue of the invention. a user may replace a blade with a blunt cutting edge of a blade of a vegetation cutting device such as a lawiiniower, 1 2 thus avoiding having to sharpen the cutting edge, which task can be time consuming and difficult for an unskilled user.

In addition, the vegetation cutting device may be provided with a blade without having to use fasteners such as screws which can rust and become clogged with dirt and vegetation cuttings during use, to attach the blade relative to a rotor.

Preferably the device is of the kind in which the rotor is in use, rotatable on a drive shaft of the cutting device for rotation about an axis coincident with a longitudinal axis of the drive shaft, the blade being slidable into engagement with the rotor in a direction generally normal to the axis of the rotor about which the rotor, in use, rotates.

The blade engagement formation means of the rotor may be configured such that when the blade is located in the, in use, position, further substantial radially outward movement of the blade relative to the rotor is prevented. For example, the blade engagement formation means may include two generally mutually facing channels, the distance between the channels decreasing towards a radially outer end of the rotor. The blade may have a pali- of opposed edge portions the distance between which decreases towards the radially outer end of the blade, the edges in use, each belii,, received by a respective one of the channels.

Thus by virtue of the configuration of the blade engagement formation means and the blade, when the edges of the blade are in engagement with the channels, further radially outward movement of the blade is prevented, and because the forces to which the blade is subjected in use as the drive shaft 1 ily ui 1 1 rotates, pr man -ge the blade radially outward. the blade is securely held by the channels and no fasteners are essential to secure the blade to the rotor.

For further security, preferably the rotor between the channels, is generally flat, although this may, have strengthening ribs or the like, and at least 0 where the blade extends along the rotor between the channels, the blade is generally in contact with the rotor.

A part of the blade preferably extends radially outwardly beyond the rotor, the outwardly extending part of the blade having at least one cutting edge, although the blade may have opposed cutting edges. Although only one cutting edge will be used as the blade rotates, the provision of two opposed cutting edges, allows the blade to be reversed when one cutting edge is blunted, to allow use of the other sharp cutting edge.

In a preferred arrangement, the rotor includes a generally central hub portion to which the drive shaft of the cutting device is, in use, connected, from which hub portion extend radially outwardly generally in opposite directions, two rotor arms to each of which a blade is, in use, connected.

According to a second aspect of the invention 1 provide a rotor and blade assembly for a vegetation cutting device according to the first aspect of the invention.

According to a third aspect of the invention I provide a rotor for a rotor and blade assembly according to the second aspect of the invention.

According to a fourth aspect of the invention 1 provide a blade for a rotor and blade assembly according to the second aspect of the invention.

c According to a fifth aspect of the invention 1 provide a method of assembling a rotor and blade assembly, for a vegetation cutting device of the first aspect of the invention including the steps of sliding the blade relative to and along the rotor until the blade engagement formation means of the rotor and the blade en-age.

According to a sixth aspect of the invention 1 provide a method of repairing a vegetation cutting device which includes a rotor with a blunted cutting edge or a rotor and blade assembly of the second aspect of the invention in which the blade is blunted, the nietliod including detaching the rotor or rotor and blade assembly from the remainder of the device, and attaching to the 1 AM 4 device a rotor and blade assembly of the second aspect of the invention, wherein the blade of the rotor and blade assembly is a sharp blade.

An embodiment of the invention will now be described by way of example only with reference to the drawing which is an illustration of a rotor and blade assembly for a vegetation cutting device according to the first aspect of the invention.

Referring now to the drawing there is shown a rotor and blade assembly including a rotor 12 and a first 1 3) and a second 14 blade. Each blade 13, 14 has a first end 13a, 14a which is provided with a sharp cutting edge.

The rotor 12 has a hub portion 12b which is adapted to be connected to a drive shaft which is rotated by motive means about a longitudinal axis A of the drive shaft. There is an aperture 15 through the hub portion 12b of the rotor 12, located generally centrally of the rotor 12, by means of which the rotor may be connected to a connection part of the drive shaft. Radially outwardly of the hub portion 12b the rotor has two arms 12c. The rotor 12 is generally flat, although tips of the arms 12c are inclined at a small angle to the remainder of the rotor 12. The rotor 12 is connected to the drive shaft such that it rotates generally in a plane normal to the axis A.

Spacing means may be provided which may be inserted between the rotor 12 and an engagement portion of the drive shaft, in order to alter the position of the rotor 12 relative to the drive shaft e.g. to alter the height to which vegetation may be cut. Two apei-tures 17 are provided in the rotor 12 to facilitate engagement of the spacing means with the rotor 12. Con-esponding apertures may also be provided in the blades 13), 14, such that the spacing means may also co-operate with the blades 13. 14.

The rotor 12 is narrower at the tips of the arnis 12c than at the hub portion 12b, i.e. the width of the rotor 12 is greatest at the centre of the rotor 12 and decreases gradually fl-om the hub portion 12b outwardly.

The rotor 12 includes four blade engagement formations 12a each of which extends along a respective edge of the rotor 12. The blade engagement formations 12a are each adapted to co-operate with an engagement portion 13c, 14c of one of the blades 1 14 and retain the blade 1 14 in use, relative to the rotor 12.

The rotor 12 is fabricated from metal sheet cut (pressed) to an appropriate shape and the blade engagement formations 12a are, in this example four outwardly externally edge portions of the rotor 12 which have been bent inwardly through approximately 180', such that there is formed a channel G between each of the bent over edge portions and the remainder of the rotor, which channels G are each approximately of the same depth as the thickness of each blade 13, 14.

Each blade 13, 14 is of decreasing width fl-om the radially inwardly most ends towards the outermost ends with the sharp cutting edge. When in the, in use, position, the blades 13), 14 extend radially outwardly of the axis A in mutually opposite directions. The drawing shows the first blade 13 coupled to the rotor 12 in the In use, position, and the second blade 14 out of engagement with the rotor 12. Thus opposite edges 13c, 14c of a blade 13), 14 may be inserted into the channels with a slidino movement radially outwardly along the rotor 12 until movement of the blade 13, 14 normal to the axis A is restricted as the blade engagement formations 12a and the edges of the blade engage.

There is a generally senii-circular portion 16 cut out from the innermost end 13b, 14b of each blade 13, 14 so that when the blades 13, 14 are located in the rotor 12 the innermost arnis 13b, 14b extend around the aperture 15 in the hub portion 12b of the rotor 122 to allow passage of the connection pail of the drive shaft through the aperture 15 and pernilt connection of the rotor 12 to the drive shaft.

When the blades 13), 14 are in the, in use, position, the outermost ends (tips) 13a, 14a of the blades 13, 14 including the cutting edges, extend radially t> 6 outwardly of the ends 12c of the rotor 12, and generally the entire length of each blade engagement formation 12a is in contact with an edge 13c, 14c of one of the blades 13, 14. Thus, as the edges of the rotor 12 and blades taper towards the ends 13a, 14a, further movement of the blades 13), 14 relative to the rotor 12 in a generally radially outward direction is prevented. Inward movement is prevented by the semi-cliculai. formations 16 co-operating with the connection part of the driveshaft or a fixing for fixing the drive shaft and the rotor 12, which passes through the aperture 15.

As the ends 12c of the rotor 12 are inclined towards the blades 13, 14, when the blades 13, 14 are in the, in use, position, in the rotor 12, blades 13, 14 are forced to bend to conform with the shape of the rotor 12, and therefore the outward most ends 13a, 14a of the blades are also inclined with respect to the remainder of the blades 13), 14. The assembly 10 is attached to the drive shaft such that the ends 13a, 14a of the blades 13, 14 are inclined towards the drive shaft.

VVIen it is desired to remove a blade 13), 14, for example if the blade is blunted or if it is desired to fit a different type of blade, the rotor 12 is detached fl-om the drive shaft, and the blades 13, 14 are slid out of engagement with the rotor 12. If the blades 13, 14 do not slide out relatively easily, for example if a blade is i-usted or caked in dirt or orass cuttiii(2s, a uset. may strike the outwardly most end]')a, 14a of the blade 13, 14 in order to loosen the blade 13, 14 and facilitate removal of the blade 13, 14 fl-oni the rotor 12.

Typically the rotor 12 is made froin a metal such as steel or stainless steel, but it may be made from any other suitably rigid material, or combination or materials. The blades 13, 14 inav be inade from the same material as the rotor 12, but are preferably made fi-oiii a inore resillient material providing a sufficiently sharp cutting edge, spring steel foi- example, in order to reduce the risk of the blades breaking on encounterino a hard obstacle such as a stone when in use.

7 Typically the rotor and blade assembly 10 is used in a vegetation cutting device in which the axis A is generally vertical such as a "Flyrn jTM. The cutting device is provided with motive means for rotating the drive shaft, which may be an electric motor, an internal combustion en-ine or any other motor means, and rotation of the rotor 12 causes the cutting edges of the blades 13), 14 to cut material such as vegetation with which the blades 13), 14 come into contact.

The invention is not restricted to the embodiment described above. the configuration of the rotor and blades may vary.

For example, the rotor 12 may be designed to hold more than two blades.

The cutting edges of the blade 13, 14 may be smooth or may be serrated.

Each blade 13, 14 may have two opposite cutting edges as shown in the drawing, in which case when a cuttim, ed,,e on the leadino edge 13c, 14c of the blade 13), 14 needs replacing, the user may reinsert the blade 13, 14 in the rotor 12 inseiled such that the other, nonblunted cutting edge is positioned at the leading edge 13c, 14c. Altei-nativel,, each blade 13), 14 may have only one cutting edge.

The edges of the rotor 12 and the blades 13), 14 need not be tapered, another method of restricting further radially outward movement of the blade 13, 14 relative to the rotor 12 when the blade 13, 14 is in the in use. position may be employed. For example, each blade 13, 14 may be provided with a stop member which extends fi-om the blade 1 '), 14 at the second end 1 3b, 14b and which abuts against a corresponding stop member provided on the rotor 12 when the blade 13, 14 is in the in use position, and restricts further radially outward movement of the blade 13, 14 relative to the rotor 12.

Moreover, further radially inward iiio,,,,einent of the blade 13), 14 need not be prevented by the innermost ends 13b, 14b of each blade cooperating with the connection pail of the drive shaft. The blades 13, 14 may,, for 8 example, be shorter than described above, and therefore may not co- operate with the drive shaft. Instead each blade 13), 14 may be provided with a stop member which abuts against a corresponding stop member provided on the rotor 12 when the blade is in the in use position, and restricts radially inward movement of the blade 13), 14 relative to the rotor 12. The corresponding stop member may be attached to the rotor 12 after insertion of the blade 13), 14 in the in use position in the rotor 12, or the blade 13), 14 may be flexed during d contact with the correspondin(l stop member until the blade insertion to avol 1 13, 14 is in the in use position.

The blade engagement formations 12a of the rotor 12 need not have the configuration described above; any other configuration by means of which a blade may coupled to the rotor through relative sliding movement of the blade, and without the need for additional fasteners, may be employed.

The blade engagement formations 12a of the rotor 12 may extend along a shorter portion of the outwardly external edge portions of the rotor 12 than that described above. In this case, in order to retain the blade 13, 14 seated generally in contact with the rotor 12 during use, a clamping means may be pided which may be connected to the rotor 12 once the blade 13, 14 is in the rovi 1 in use position such that the blade 13), 14 is clamped in place between the rotor 12 and the clamping means. Such a clainpino means could also be usefully c c ided where the blades 13, 14 are pailiciflarly, long, and may extend along provi the length of the blades 13), 14.

When the rotor 12 is connected to the drive shaft for use, the second ends 13b, 14b of the blades 13), 14 may be also engaged with the connecting pail of the drive shaft. For example, apertures may be provided in the second ends 13b, 14b of the blades 13, 14 in order to facilitate connection to the drive shaft.

The features disclosed in the foregoing description, or the following claims, or the accompanying drawings, expressed in thelir specific forms or in

C 9 terms of a means for performing the disclosed function, or a method or process for attaining the disclosed result, as appropriate, may, separately, or in any combination of such features, be utilised for realising the invention in diverse forms thereo

Claims

1. A vegetation cutting device including a rotor and blade assembly, the assembly including at least one blade with at least one cutting edge, characterised in that the rotor includes blade engagement formation means adapted to engage the blade to retain the blade, in use, relative to the rotor, the blade engagement formation means and the blade being configured to permit the blade to be engaged with the rotor by effecting sliding of the blade relative to the rotor.

2. A device according to claim 1 characterised in that, the rotor is in use, rotatable on a drive shaft of the cutting device for rotation about an axis coincident with a longitudinal axis of the drive shaft, the blade being slidable into engagement with the rotor in a direction generally normal to the axis of the rotor about which the rotor, in use, rotates.

3. A device according to claim 1 or cialin 2 characterised in that the blade engagement formation means of the rotor I's cotifigured such that when the 0 blade is located in the, in use, position, fur-ther substantial radially outward movement of the blade relative to the rotor is prevewed.

4. A device according to claim 3 characterised in that the blade engagement means includes two generally mutually facing clianriels, the distance between the channels decreasing towards a radially outermost end of the rotor.

Z-1- A device according to claim 4 characterised in that the blade has a pair of opposed edge portions the distaiice betweeii which decreases towards the 11 radially outermost end of the blade, the edges in use, each being received by a respective one of the channels.

6. A device according to claim 5 characterised in that the rotor is, between the channels, generally flat and at least where the blade extends along the rotor between the channels, the blade is 7. A device according to any one of the preceding claims characterised in that in use, the blade extends radially outwardly beyond the rotor, the outwardly extending pail of the blade having at least one cutting edge.

c generally in contact with the rotor.

8. A device according to any one of the preceding claims characterised in that the rotor includes a generally central hub portion to which a drive shaft of the cutting device is, in use, connected, from which hub portion extend radially outwardly generally in opposite directions, two rotor arms to each of which a blade is, in use, connected.

9. A vegetation cutting device substantially, as liereinbefore described with reference to the accompanying drawing.

10. A rotor and blade assembly for a ve(yetation cuttim, device according to any one of the preceding clalims.

A rotor and blade assembly substantially, as hereinbefore described with reference to and as shown In the accompanying drawing.

c 12. A rotor for a rotor and blade assembly according to claim 10 or claim 12 13. A blade for a rotor and blade assembly according to claim 10 or claim 11.

14. A method of assembling a rotor and blade assembly for a vegetation cutting device of any one of claims 1 to 9 characterised in that the method includes the steps of sliding the blade relative to and along the rotor until the blade engagement formation means of the rotor and the blade engage.

C> 15. A method of assembling a rotor and blade assembly substantially as hereinbefore described with reference to the accompanying drawing.

Z:> 16. A method of repairing a vegetation cutting device which includes a rotor C) with a blunted cutting edge or a rotor and blade assembly of claim 10 or claim 11 in which the blade is blunted, the method including detaching the rotor or rotor and blade assembly from the remainder of the device, and attaching to the device a rotor and blade assembly of claim 10 or claim 11, wherein the blade of the rotor and blade assembly is a sharp blade.

17. A method of repairing a ve(letation cutting device substantially as c hereinbefore described with reference to the accompanying drawing.

c 18. Any novel feature or novel combination of features described herein and/or shown in the accompanying draw1110 WI