AU713852B2

AU713852B2 - Cutting blades for lawn mowers

Info

Publication number: AU713852B2
Application number: AU28457/97A
Authority: AU
Inventors: Gaven Ray Dall'osto; Stephen Leonard Jackson; Steven Richard Miatt
Original assignee: Rover Mowers Ltd
Current assignee: Rover Mowers Ltd
Priority date: 1996-07-10
Filing date: 1997-07-02
Publication date: 1999-12-09
Anticipated expiration: 2017-07-02
Also published as: AU2845797A

Description

I Our Ref: 646662 P/00/011 Regulation 3:2

AUSTRALIA

Patents Act 1990

ORIGINAL

COMPLETE SPECIFICATION STANDARD PATENT Applicant(s): Address for Service: Invention Title: Rover Mowers Limited 155 Fison Avenue West Eagle Farm Queensland 4009

AUSTRALIA

DAVIES COLLISON CAVE Patent Trade Mark Attorneys Level 10, 10 Barrack Street SYDNEY NSW 2000 Cutting blades for lawn mowers The following statement is a full description of this invention, including the best method of performing it known to me:- 5020 P:\WPDOCS\DYS\SPECIE\ROVER.SPE 1/7/97 -1- CUTTING BLADES FOR LAWN MOWERS This invention relates generally to cutting blades for lawn mowers and more particularly for lawn mowers of the rotary type.

Rotary lawn mowers generally have a cutting blade assembly wherein two or more blades are mounted to a support disc which is in turn mounted for rotation about a generally upright axis of rotation. Usually the blades are mounted so they project radially outwardly •from the periphery of the support disc and have a cutting edge at the leading edge portion of 10 the blade and in some cases are provided with a fluted trailing edge portion, the purpose of which is to direct the clippings to a grass catcher.

It is an object of the present invention in one aspect to provide an improved cutting i "'"blade which is superior to currently known cutting blades. It is a further object of the present invention in another aspect to provide an improved blade assembly using blades in accordance with the first aspect.

According to one aspect of the present invention there is provided a blade which is suitable for use with a lawn mower which includes a blade support which is mounted for rotation about a rotation axis, the blade including a main body having a mounting section and a blade section, the mounting section being operatively connectable to the blade support for pivotal movement about a pivot axis which is generally parallel to the rotation axis of the support, the blade section of the blade when in use extending from a peripheral edge of the support and the blade including a leading edge portion a trailing edge portion with respect to the normal direction of rotation of the support, and a fluted section at the trailing edge portion which is inclined upwardly at an angle of from 450 to 700 with respect to the plane of the body of the blade section. Preferably, the angle of inclination is about 600.

The blade may further include a generally arcuate shaped transition or connecting region between the flute section and the mounting section.

P:\WPDOCS\DYS\SFICIE\ROVER.SPE 1797 -2- In one preferred embodiment the mounting section includes a generally flat plate like structure having a mounting hole therein for receiving a pin or similar fastening by which the blade is connected to the blade support so that the blade can pivot about the mounting pin.

Preferably, the mounting hole is disposed forwardly of the central longitudinal axis of the blade.

The blade section may preferably include a cutting edge at the leading edge of the blade section, the cutting edge preferably extending along the leading edge from the outermost part of the blade section and terminating in the region of the peripheral edge of the 10 blade support.

Preferably, the fluted section of the blade section is generally rectangular in shape and is inclined upward from a central region of the blade section terminating at the trailing edge of the blade section. Preferably, the arcuate shape connection section is shaped so it forms 15 a ramped surface which tends to cause the blade to pass under the blade support if a solid object is struck by the blade.

According to another aspect of the invention there is provided a blade which is suitable for use in a lawn mower which includes a blade support which is mounted for rotation about a rotation axis, the blade including a main body having a mounting section and a blade section, the mounting section being operatively connectable to the blade support for pivotal movement about a pivot axis which is generally parallel to the rotation axis of the support, the blade section of the blade when in use extending from a peripheral edge of the support and the blade including a leading edge portion and a trailing edge portion with respect to the normal direction of rotation of the support, and the blade being configured so that when mounted to the support its pivot axis is positioned on the mounting section such that when the support is rotating at a cutting speed the leading edge is inclined forwardly with the leading edge at the top end being forward at the leading edge inwardly thereof.

According to yet another aspect of the present invention there is provided a blade P:\WPDOCS\DYS\SPECIE\ROVER.SPE 1/797 -3which is suitable for use in a lawn mower which includes a blade support which is mounted for rotation about a rotation axis, the blade including a main body having a mounting section and a blade section, the mounting section being operatively connectable to the blade support for pivotal movement about a pivot axis which is generally parallel to the rotation axis of the support, the blade section of the blade when in use extending from a peripheral edge of the support and the blade including a leading edge portion and a trailing edge portion with respect to the normal direction of rotation of the support, and wherein the blade includes an upwardly inclined fluted section at the trailing edge portion and has a generally arcuate shape connecting region between the flute and the mounting section.

According to yet another aspect of the present invention there is provided a blade assembly which is suitable for use in a lawn mower, the blade assembly includes a blade osupport which is mounted for rotation about a rotation axis, and a plurality of blades, each blade including a main body having a mounting section and a blade section, the mounting 15 section being operatively connectable to the blade support for pivotal movement about a pivot axis which is generally parallel to the rotation axis of the support, the blade section of the blade when in use extending from a peripheral edge of the support and the blade including a leading edge portion and a trailing edge portion with respect to the normal direction of rotation of the support, and each blade being mounted to the support so that its pivot axis is positioned on the mounting section so that when the support is rotating at a cutting speed the leading edge is inclined forwardly with the leading edge at the top end being forward at the leading edge inwardly thereof. Preferably, the blades are of the structure described earlier.

Preferably, the blade section of the blade projects outwardly from the peripheral edges of the blade support. The blade support may be of any suitable shape or configuration and in one preferred form comprises generally disc-like element which is operatively mounted to a suitable drive shaft for rotation about its central axis.

Preferred embodiments of the invention will be hereinbefore described with reference P:\WPDOCS\DYS\SPECIE\ROVERSPE 117/97 -4to the accompanying drawings.

Figure 1 is a schematic view of a cutting blade assembly according to the present invention; Figure 2 is plan view of the assembly shown in Figure 1; a Figure 3 is a side elevation of the assembly shown in Figures 1 and 2; Figure 4 is a schematic view of a cutting blade according to the present invention; Figure 5 is a further view of the cutting blade shown in Figure Figure 6 is a plan view of the cutting blade shown in Figures 5 and 6; Figure 7 is a schematic end view of the cutting blade shown in Figures 5 to 7; Figure 8 is a side view of the blade shown in Figures 5 to 8; Figure 9 is a schematic view of a cutting blade assembly according to the present invention showing the disposition of the blades when the assembly is rotating and; Figure 10 is a schematic view showing the cutting blade when it impacts a solid object.

Referring to the drawings, a blade cutting assembly 10 is illustrated in Figure 1 and includes a dome shaped support disc 12 which is mounted for rotation in the direction of the arrow A as shown. The blade assembly includes four cutting blades 20, although it will be appreciated that more or less than four blades could be mounted to the support disc 12. The cutting blades 20 are mounted to the disc 12 and project outwardly from the peripheral edge P:\WPDOCS\DYS\SPECIE\ROVER.SPE 11/97 13 thereof.

The cutting blades 20 include a main body 22 having a mounting section 24 and a blade section 30. The mounting section 24 includes a generally flat rectangular part having a mounting hole 26 therein so that in use the blade can pivot about axis X-X.

The mounting hole 26 is positioned so that when the support disc is rotating the centre of gravity of the blade under centrifugal force against the resistance provided by the throwing i' flute causes the blade cutting edge to angle forward to optimise cutting performance. As 10 shown in Figure 9, the cutting edge is angled at an angle Y when the support disc is rotating.

o .o The blade section 30 of the main body includes a leading edge portion 31 having a •o cutter edge 35 thereon, a trailing edge portion 32, trailing portion being formed in the form of a fluted portion 33.

S. A connecting or transition region 34 extends between the blade section and the mounting section 24. With the cutting edge inclined forwardly cutting performance can be optimised.

i The flute portion provides a maximum surface area and is preferably kept within the range of angles of 450 to 700 (angle Z in figure The purpose of the fluted portion is to keep the grass clippings above the blades and moving around the mower chute to release to the grass catcher so as to minimise the amount of dropped grass clippings. The flute portion also keeps the grass clippings travelling at a sufficient rate to prevent adherence to the underside of the mower and finally the grass clippings are kept above the cutting edge to maximise cutting action on uncut grass; that is the grass clippings do not mask the cutting edge. It has been found that maintaining flute angle between 450 to 700 and preferably at about 600 optimises the performance of the cutting blade.

As mentioned the transition region 34 between the blade section 30 and the mounting P:\WPDOCS\DYS\SPECIE\ROVER.SPE 17/97 -6section 24 is generally curved in shape and preferably roll formed thereby allowing the blade to swing back if it strikes a rigid object. Because of the arcuate form the blade tends to roll under the support disc without sections of the disc or blade breaking away. This is best illustrated in Figure 10 wherein the blade is shown under the support disc after striking object Finally, it is to be understand that various alterations, modifications and/or additions may be incorporated into the various constructions and arrangements of parts without departing from the spirit or ambit of the invention.

o *ooo *0•

Claims

1. A blade which is suitable for use with a lawn mower which includes a blade support which is mounted for rotation about a rotation axis, the blade including a main body having a mounting section and a blade section, the mounting section being operatively connectable to the blade support for pivotal movement about a pivot axis which is generally parallel to the rotation axis of the support, the blade section of the blade when in use extending from a peripheral edge of the support and the blade including a leading edge portion a trailing edge portion with respect to the normal direction of rotation of the support, and a generally rectangular shaped fluted section at the trailing edge portion which is inclined upwardly at an angle of from 450 to 700 with respect to the plane of the body of the blade section. 000

2. A blade according to claim 1 wherein the angle of inclination is about 600. 0 96 b. 0: 15

3. A blade according to claim 1 or claim 2 including a generally arcuate shaped transition or connecting region between the flute section and the mounting section.

4. A blade according to any preceding claim wherein the mounting section includes a generally flat plate like structure having a mounting hole therein for receiving a pin or similar 20 fastening by which the blade is connected to the blade support so that the blade can pivot about the mounting pin.

A blade according to claim 4 wherein the mounting hole is disposed forwardly of the 0 central longitudinal axis of the blade.

6. A blade according to any preceding claim wherein the blade section includes a cutting edge at the leading edge of the blade section, the cutting edge preferably extends along the leading edge from the outermost part of the blade section and terminating in the region of the peripheral edge of the blade support. 1 P:\WPDOCS\DYS\SPECIE\ROVER.SPE 22/9/99 -8-

7. A blade according to any preceding claim wherein the fluted section of the blade section is inclined upward from a central region of the blade section terminating at the trailing edge of the blade section.

8. A blade according to any one of claims 3 to 7 wherein the arcuate shape connection section is shaped so it forms a ramped surface which tends to cause the blade to pass under the blade support if a solid object is struck by the blade.

9. A blade assembly which is suitable for use in a lawn mower, the blade assembly S" 10 includes a blade support which is mounted for rotation about a rotation axis, and a plurality of blades, each blade including a main body having a mounting section and a blade section, the mounting section being operatively connectable to the blade support for pivotal movement about a pivot axis which is generally parallel to the rotation axis of the support, the blade S• section of the blade when in use extending from a peripheral edge of the support and the oo .i S: i 15 blade including a leading edge portion and a trailing edge portion with respect to the normal direction of rotation of the support, and each blade being mounted to the support so that its pivot axis is positioned on the mounting section so that when the support is rotating at a cutting speed the leading edge is inclined forwardly with the leading edge at the top end being forward at the leading edge inwardly thereof, each blade further including a generally 20 rectangular shaped fluted section at the trailing edge portion which is inclined upwardly at an angle of between about 450 to 700 with respect to the plane of the body of the blade section.

A blade assembly according to claim 9 wherein each blade includes an upwardly inclined fluted section at the trailing edge portion and has a generally arcuate shape connecting region between the flute and the mounting section.

11. A blade substantially as hereinbefore described with reference to the accompanying drawings. 22/9/99 -9-

12. A blade assembly substantially as hereinbefore described with reference to the accompanying drawings. Dated this 22nd day of September, 1999 ROVER MOWERS LIMITED By Their Patent Attorneys DAVIES COLLISON CAVE 0O 0 00 *0 0O 0 0 00 505 9 00S