AU617991B2 - Mowing apparatus - Google Patents

Description

MICHAEL J. GRANT To: The Commissioner of Patents J AUSTRALI A PATENTS ACT 17 9 9 COMPLETE SPECIFICATION

ORIGINAL

(FOR OFFICE USE) Class Int Class Application Number: Lodged: Complete Specification Lodged: Accepted: Published: Priority: tic Related Art: Name of Applicant(s): .CO.NNECT.I.ONS..DES.LG.N Address of Applicant(s): Ma.s.i. on..P.l.ac.e. h.ir.rs.i.de. Victoria, 3116 o A c t u a l In v e n t o r (s Address for Service: PATENT ATTORNEY SERVICES, 1025 Whitehorse Road, Box Hill, Victoria 3128 Complete specification for the invention entitled: MOWING APPARATUS The following statement is a full description of this invention, including the best meThod of performing it known to i.i x ;i--s MOWING APPARATUS This invention relates to vegetation mowing or trimming apparatus, particularly Lor mowing domestic lawns, park areas, sporting or playing fields and the like but the invention is also applicable to agricultural uses for example, The commonly known and available lawn mowers are one of two types, The first type is a "disc" or "slasher" mower having blades in the form of plates which are secured to the outer edge of a disc which is generally horizontal. The disc is rotatable about a vertical shaft so that the blades move horizontally to cut the grass to the desired height, The second type of mower is a "reel type" having part helical blades which are mounted around a horizontal axle extending at right angles to the linc of movement of the mower, The helical blades cut the grass by forming a scissor or shears-tpe action at a fixed horizontal plate which is advanced into the grass t; to be mown. Both of these types of mowers can be relatively expensive, heavy, require large amounts of energy to drive the blades S, and can be difficult to service due to complicated construction.

t 4 o It is an object of the present invention to provide a mowing apparatus which is relatively simple in construction and operation and which can be made and operated relatively cheaply, •It is a preferred object to provide a mowing apparatus which can o: :be of light weight and furthermore can be simple to repair or service.

According to the present invention there is provided a mowing apparatus for mowing vegetation, the mowing apparatus including: :o a frame which is movable along a path line over vegetable matter to be mowed; a plurality of flexible cutting blades for cutting the vegetable matter, each blade being comprised by a finger or prong which is mounted at one end and has a cutting tip at the other end, the cutting blades being mounted by rotary mounting means which is rotatable relative to the frame about a rotation axis, each blade being mounted so as to be generally upright as it passes through the vegetable matter and as the cutting tip cuts the vegetable matter; and drive means for driving the rotary mounting means about the rotation axis as the frame is moved along the path line,

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i c JI i i i i i I~~ In the preferred embodiment, the rotation axis is a generally horizontal rotation axis, the flexible cutting blades being mounted to the mounting means so as to extend generally radially away from the rotation axis whereby the cutting blades move towards and away from the vegetable matter as rotation of the rotary mounting means occurs, the rotation axis being at an angle to the path li.ne not equal to 900 so that as the mowing apparatus moves along the path line and the rotary mounting means rotates so that the tips of the blades cut the vegetable matter at their lowest points of movement, there is a component of movement of the cutting blades transverse to the path line.

Preferably the rotation axis is at an angle to the path line of greater than 0° and less than 90°. Preferably the rotation axis is at an angle of greater than 45° to the path line. The angle of the ,rotation axis to the path line may be between 600 and Preferably at least two of the blades are spaced apart along an axle extending along the rotation axis so that the tips of the spaced blades follow different cutting paths through the vegetable matter as the frame is moved along the path line. The spaced cutting blades may be arranged along the rotatable axle having a centre line which constitutes the rotation axis, the frame including an inverted U shaped frame member, the two extremities of the'U shaped frame member providing mountings for the opposite ends of the axle. The d?'lv2 means may comprise a motor driving the axle at a point generally 25 midway along its length.

The angle of the rotation axis to the path line may be selectively variable to enable user control of cutting action of the blades. The mowing apparatus may include ground engaging wheels mounted to the frame for rotation about parallel or collinear wheel mounting axes, the angle defined between the wheel mounting axes and the rotation axis being selectively variable to provide variability of the rotation axis relative to the path line.

-r Preferably the blades extend generally radially away from and are arranged at different angles to the rotation axis when viewed along that axis, the blades being arranged at angular intervals around the axis to provide a balanced weight distribution and to limit the number of blades cutting the vegetable matter at any instant.

Possible and preferred features of the present invention will now be described with particular reference to the accompanying drawings.

However it is to be understood that the features illustrated in and described with reference to the drawings are not to be construed as limiting on the scope of the invention. In the drawings: Fig. 1 is a front elevational view at right angles to the blade axle of a mowing apparatus according to the present invention, Fig. 2 is a schematic top plan view showing the cutting paths of the blades as the mower is moved along the path line, Fig. 3 is a side view of an embodiment showing variable cutting height ?ossibilities, Fig. 4 is a top plan view of a single blade tip sweep pattern when the mower is moving, Fig. 5 is a view along the path line showing the path of travel of one blade and its vegetation cutting effect, Fig. 6 is a schematic top plan view of an alternative mowing apparatus according to the present invention, and Fig. 7 is a schematic top plan view of a third embodiment of a mowing apparatus according to the present invention.

The mowing apparatus according to the embodiment of the present invention shown in Figs. 1 and 2 includes a frame 10 which is movable along a path line 11 over the matter to be mowed or trimmed. The apparatus may be usable as a vegetation trimming tool, e.g. for trimming hedges, but it will be generally convenient to describe the invention in relation to mowing grass. The frame 10 is mounted on ground engaging wheels 12. Two wheels 12 are provided at opposite sides of the frame 10 relative to the path line 11. A handle 13 extends upwardly and rearwardly from the frame 10 enabling the user to operate the mower. The handle 13 may be tubular and of light weight similar to a golf buggy handle.

The mowing apparatus further includes a plurality of cutting blades 20 for cutting the grass 15 or other matter to be mowed or trimmed, the blades 20 being mounted for rotation about an axis 21 (Fig. 2) which is generally horizontal for grass mowing. The blades j _i I ii 1 move generally orthogonally towards and away from the grass or matter as rotation about the axis 21 occurs. Furthermore the rotation axis 21 in top plan view in use is at an angle of other than 900 to the path line 11. For higher angles, say approaching 90', the blades 20 may have or shaped cutting tips to contact and cut the grass. The mowing apparatus includes drive means 30 for rotating the blades 20 about the rotation axis 21 as the frame 10 is moved along the path line 11.

In the illustrated embodiments the rotation axis 21 is generally horizontal so that each blade 20 moves in a generally vertical plane as it moves towards and away from the ground. With this arrangement as a blade 20 encounters any grass 15 towards the lowest point of movement of its tip, it will cut through the grass, provided its speed is sufficiently high.

The rotation axis 21 in top plan view (Fig. 2) is at an angle to the path line 11 so that a substantial component of the movement of the tip of the blade 20 is at right angles to the path line. This may also be seen in Figs. 4 and 5, particularly Fig. 5 which is a view along the path line 11 and which shows the path 22 of the blade tip and a section through the swath 23 that will be cut by the blade tip as the apparatis advances along the rath line 11.

The angle of the plane of rotation of the blade 20 to the path line 11 may be between 10' and 80' degrees, and preferably less than 450, say between 15' and 30'. That is, the rotation axis 21 is preferably at more tian 45', say between 600 and 750, to the path line 11. In the preferred embodiment illustrated the plane of blade rotation is at an angle of about 200 to the path line 11 blade rotation axis 21 of about 700 to the path line 11).

The angle of the rotation axis 21 to the path line 11 in top plan view may be selectively variable to enable user control of the cutting action of the blade tip. Such angle variability may be achieved for example by enabling selective angling of the ground engaged wheels 12 relative to the rotation axis 21. An ornamental mowing pattern can be achieved by selecting certain angles or by moving the blades 20 axially, e.g. by axially reciprocating the axle 24 to which the blades 20 are mounted.

A plurality of cutting blades 20 are arranged along 3 single rotatable axle 24 the centre line of which constitutes the rotation axis 21. The axle 24 may be for example about 600mm in length. The

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11- 11- i ~II frame 10 includes an inverted U shaped frame member 16, the two extremities of the U shaped frame member 16 providing mountings for the opposite ends of the axle 24. The axle 24 is mounted at its opposite ends by means of suitable bearings 25. Relatively short length cylindrical collars 26 may be provided at the ends of the U shaped frame member 16 in which the bearings 25 are located, the collars 26 providing protection for the bearings 25 against damage by debris or the like. The U shaped frame member 16 is comprised of two L shaped pieces 16a, 16b removably connected together, e.g. by connecting bolts 17. Removal of the bolts 17 will enable the U shaped member 16 to be disassembled enabling the rotatable axle 24 to be removed from its mounting bearings In another possible embodiment (not shown) there may be provided two or more rotatable axles with blades being provided at points along the axles. The axles may be "ganged", i.e. with one behind ar ther relative to the path line 11. Alternatively there may be two I axles arranged generally side by side and one at (90+8) 0 to the path line 11 and the other at to the path line 11.

There may be provided any suitable number of cutting blades 26 For example ten blades 20 may be provided equally spaced along the rotatable axle 24 in the preferred embodiment. The blades 20 are in form of fingers or prongs with tips 27 shaped to suit. The blades 4 may be made of any suitable material such a plastics material or metal rods or wires, sharpened if required blunt for domestic t use, sharp for professional use). Preferably the blades 20 are flexible and may yield if they strike an object, such as a person's foot or an obstacle. The blades 20 may taper slightly from a mounting end 29 to an outer cutting tip 27. The mounting end 29 may have an enlarged head 31 enabling the blade 20 to be passed through a hole 32 passing through the rotatable axle 24, the head 31 limiting the extent to which the tip 27 projects from the axle 24 thereby controlling the cutting action. Any suitable means, including using a tight frictional fit of the blade 20 at the head end 29 in the hole 32 through the axle 24, may be used to secure the blade 20 to the axle 24. The blades 20 may be readily removable for damaged blade replacement or for replacing blade sets suitable for different mowing conditions wet or dry grass, different grass lengths, different grass types).

The blades 20 may be for example about 150mm in length. The ten blades 20 provided in one possible preferred embodiment may be arranged at different angles to the axle 24 when viewed along the rotation axis. For example as shown in Fig. 3 the blades 20, 20a may be arranged at 360 intervals around the axle 24 thereby providing a balanced weight distribution and limiting the number of blades cutting at any instant thereby minimising friction.

The drive means 30 may be of any suitable construction and operation. In the preferred arrangement of Figs. 1 to 3 Ehe mowing apparatus includes a drive motor 32 which may be an internal combustion engine or in the preferred embodiment it may be an electric motor. In the case where an electrical motor is provided, this motor 32 may be mounted to the frame 10, say at the top centre of the U shaped frame member 16. The drive shaft 33 of the motor 32 extends generally horizontally, parallel to the rotatable axle 24.

There is provided a pulley 34 on the motor shaft 33 and an equal diameter (or other size) pulley 35 on the rotatable axle 24 at the centre thereof and a drive belt 36 is used to convey drive from the motor 32 to the axle 24. It will be appreciated that the belt 36 may be a friction drive to the pulleys 34,35 or may he for example a toothed belt for synchronous drive.

The electric motor 32 of the preferred embodiment may be for example a 12 volt DC motor, 24 volt DC motor or 240 volt AC motor.

The power required is expected to be relatively small compared to conventional mower configurations and it is believed that a motor 32 having a power rating of say 120 watts or 1/4 horsepower may be suitable.

The speed of rotation of the axle 24 may be for example 3900 r.p.m. (about 65 giving a blade tip speed of 200 k.p.h.

(assuming a 300mm diameter circular movement of the blade tip 27).

At this speed the blade tips 27 will cut very cleanly through grass blades. Also the slim shape and configuration of cutting blades will not create any appreciable air flow or grass tossing action and therefore the cut grass will drop to the ground immediately below the mower blades 20 and not be thrown significantly away from the blades Also stones etc. are not thrown by the blades 20. Because of thr very clean cutting action, low power only is needed and it may be possible to operate the mower from a relatively light weight battery, preferably a rechargeable battery carried on the mowing apparatus.

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An electronic current draw control unit (not shown) may be provided to enable automatic compensation for variations in load on the motor 32, thus minimising power consumption.

The mowing apparatus preferably includes a casing 40 or shielding mounted to the frame 10 and covering the cutting blades 20 and axle 24 so that debris is not thrown upwardly from the mowing zone towards the operator. Also the casing 40 will protect against inadvertently inserting a hand or foot into the path of the cutting blades although using blunt flexible plastic blades may minimise the possibility of the user sustaining an injury.

The cutting height of the apparatus may be selectively adjustable in any convenient manner. For example the axle 24 and mountings may be arranged to be located at different heights relative to the frame For example as shown in Fig. 3 the opposite ends of the U shaped frame member 16 may be provided with a plurality of vertically spaced mounting positions 41 for the axle 2d and mountings. In this arrangement, to avoid difficulties with a belt motor drive from above the axle 24 as shown in Fig. 1, the drive means 30 as shown in Fig. 7 may comprise a motor 30 (or motors) mounted at one end (or opposite ends) of the axle 24, the axle 24 being driven directly by the motor shaft(s). Alternatively, the drive means 30 may comprise a motor encased in the axle 24. In Fig. 6, the drive means 30 is mounted centrally on the axle 24, e.g. with the axle 24 itself constituting the motor shaft.

In Fig. 4 there shown, approximately full scale two consecutive sweeps of the same blade tip, showing separation of about 23.8mm, assuming 200 angle of the plane of the tip movement to the path line 11, 300mm diameter circular tip movement, 4 k.p.h. forward speed along the path line 11 and 2800 r.p.m. rotational speed.

It will be seen that the mowing apparatus according to the preferred embodiment of the present invention as described herein and illustrated can be particularly simple in construction enabliny easy assembly and relatively cheap materials and components to be used.

Because of the simplicity of construction and operation, the apparatus is believed to be of low cost and high reliability. The apparatus can be of very light weight (say about 8kg excluding battery), be cheap to run, generate low noise and can be safe in operation. The apparatus can also be very siniple to service and repair.

8 T It is to be understood that various alterations, modifications and/or additions may be made to the features of the possible and preferred embodiment(s) of the invention as herein described without departing from the spirit and scope of the invention as defined in the appended claims.

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Claims (3)

1. 2. A mowing apparatus as claimed in Claim 1 wherein the rotation axis is a generally horizontal rotation axis, the flexible cutting blades being mounted to the mounting means so as to extend generally radially away from the rotation axis whereby the cutting blades move towards and away from the vegetable matter as rotation of the rotary mounting means occurs, the rotation axis being at an angle to the path line not equal to 90' so that as the mowing apparatus moves along the path line and the rotary mounting means rotates so that the tips of the blades cut the vegetable matter at their lowest points of movement, there is a component of movement of the cutting blades transverse to the path line.
2. 3. A mowing apparatus as claimed in Claim 2 wherein the rotation axis is at an angle to the path line of greater than 0* and less than
3. 900. 4. A mowing apparatus as claimed in Claim 2 or 3 wherein the rotation axis is at an angle of greater than 450 to the path line. A mowing apparatus as claimed in Claim 4 wherein the angle of the rotation axis to the path line is between 600 and 75 6. A mowing apparatus as claimed in any one of Claims 2 to 5 wherein the mounting means includes a generally horizontal. rotatable axle extending along the rotation axis, and at least two of the blades are spaced apart along the axle so that the tips of the spaced blaces .C ~follow different cutting paths through the vegetable matter as the (Qs frame is moved along the path line. I 7. A mowing apparatus as claimed in Claim 6 wherein the spaced cutting blades are arranged along the rotatable axle havi.ng a centre line which constitutes the rotation axis, the frame including an inverted U shaped frame member, the two extremities of the U shaped frame member providing mountings for the opposite ends of the axle, 8, A mowing apparatus as claimed in Claim 6 or 7 wherein the drive means comprises a motor driving the axle at a point generally midway along its length. 9, A mowing apparatus as claimed in one of Claims 2 to 8 wherein the angle of the rotation axis to the path line is selectively variable to enable user control of cutting action of the blades. A mowing apparatus as claimed in Claim 9 wherein the mowing apparatus includes ground engaging wheels mounted to the frame for rotation about parallel or collinear wheel mounting axes, the angle defined between the wheel mounting axes and the rotation axis being selectively variable to provide variability of the rotation axis relative to the path line. 11, A mowing apparatus as claimed in any one of Claims 2 to wherein the blades extend generally radially away from and are arranged at different angles to the rotation axis when viewed along -that axis, the blades being arranged at angular intervals around The axis to provide a balanced weight distribution and to limit the number of blades cutting the vegetable matter at any instant. 12. A mowing apparatus substantially as herein before described with particular reference to the accompanying drawings, Dated this 18th day of September, 1991 PATENT ATTORNEY SERVICES Attorneys for CONNECTIONS DESIGN PTY. LTD, II