GB2433867A

GB2433867A - An electric powered grass cutting machine with the power produced by an engine driven a generator

Info

Publication number: GB2433867A
Application number: GB0600072A
Authority: GB
Inventors: Alexander Dow; Martin Dow
Original assignee: Individual
Current assignee: Individual
Priority date: 2006-01-04
Filing date: 2006-01-04
Publication date: 2007-07-11
Anticipated expiration: 2026-01-04
Also published as: GB2433867B; GB0600072D0

Abstract

A mechanically propelled machine for cutting grass consists of an engine fuelled by liquid or gas driving a generator. Electric power from the generator is controlled and fed to an electric motor or motors driving the machine. The machine is fitted with reciprocating multi toothed cutters 9 driven by electric motors 10 and fitted to the front or rear of the machine. The electric motors are mounted with the axis of rotation vertical to the drive of the cutters via a crank pin rotating on a vertical axis. The machine is steered by its front wheels 2.

Description

A powered machine for cutting grass This invention is concerned with

machines for grass cutting, primarily but not exclusively for domestic use, and specifically those powered by petrol or diesel engines or other means of prime mover and on which the user sits to control the operation.

Domestic grass cutting machines exist where the forward or backward speed of the machine is controlled by a number of gears or by an infinitely variable drive mechanism generally known as hydrostatic drive driving the rear wheels and where the drive to the grass cutting device is by belt, the actual cutting being by a number of blades being rotated on a vertical axis More expensive commercial or semi-commercial machines have what are known as cylinder cutters where a series of horizontal blades rotate against fixed blades which are driven by a mechanical drive consisting of shafts and gears. The position of the vertical rotating blade cutter is normally in a central position between the front and rear wheels and in more expensive commercial machines the cylinder cutter or cutters are usually at the back of the machine behind the rear wheels but are occasionally positioned at the front of the machine in which case rear wheels are normally used for steering in order to simplif,' the cutter drive Both the types of machine drive mechanisms in use on domestic machines are cumbersome in operation, it being necessary to halt and restart the motion of the machine in order to change gears where used by removing the tension of the primary drive belt which is crude and unsatisfactory in use. The hydrostatic method of varying the speed is superior but leaves much to be desired and is usually operated by an insensitive mechanical connection. The disadvantage of the vertically rotating centrally mounted cutter is that it is impossible to drive directly up to grass to be cut and in many cases it is not possible to cut difficult areas around bushes etc. It also requires a relatively large amount of power which makes it expensive initially and to operate. This type of cutter is also available in a form known as sell mulching, which is a system of mulching the cut grass within the cutter housing and distributing it in a form which is less visible. If this system, which is not satisfactory in wet conditions, is not used the grass distribution is often poor and generally unsightly. The cylinder type cutter sometimes used on more expensive machines is good but the drive connection on these machines is complicated and generally too expensive for domestic use. Additionally the cylinder cutter mounted at the back suffers the same disadvantages as the centrally mounted rotating blade cutter, and where mounted at the front with rear steering again has similar manoeuvrabiity problems. All in all the conventional domestic and semi-commercial rideon mower is cumbersome in operation, expensive to run, and limited in its sphere of operation.

To overcome these problems this invention proposes to use electrical power to independently variably control both the forward and an backward speed of the machine as well as to be able independently to drive at a variable speed the grass cutter or cutters with the electrical power being provided by a petrol, deisel or gas prime mover driving a generator, as well as to provide superior cutting manoeuvrability at a lower basic cost and cost to run.

The actual grass cutting device or devices may be a scissor type of cutter consisting of a multiple toothed reciprocating toothed blade moving on a fixed toothed blade where the number of teeth on the moving blade may be similar or either smaller or greater than the number of teeth on the fixed blade.

A machine embodying the main features of such a machine consists of a platform or chassis generally similar to existing mowers preferably with four wheels, but not exclusively four, in number, at least one of which but possibly all, are driven by one or more electric motors.

Like almost all domestic machines the front wheels would normally but not necessarily be steerable. The rear wheels of my invention would normally but not necessarily be the drive wheels driven by an electric motor with a differential gear or by two separate motors..

The advantage of two separate motors one for each wheel over a single motor with differential gear is that in the event of one of the wheels losing grip all drive is not lost. Electric power for the motor or motors would be provided by a petrol, diesel or gas engine driving an electric generator, the variation in speed of the mower both forwards and backwards being controlled by an electronic or electrical system for varying the power delivered to the drive motor or motors, the engine normally running at a constant speed. Such electrical system of speed control is already in use on disability mobility and other type vehicles. Electrical braking would be provided but a mechanical brake would also be provided and could be by direct pressure on the rear tyres. Power from the generator is also separately fed to a motor or motors operating the grass cutting device or devices which might be at the front or rear of the machine or possibly both. The position of a single cutter might also be variable, interchangeable front or rear to suit differing circumstances. The cutter unit itseff would preferably but not exclusively be a multi-toothed scissor type of cutter generally of the type used for cutting hedges, but with finer teeth and maybe a faster operating speed and modified tooth profile where the tooth pitch of the top blade is similar, greater or smaller than the tooth pitch of the lower blade, and operated by its own motor or motors. A front cutter would enable the machine to be manoeuvred so as to approach the grass to be cut directly and the rear cutter would be better able to distribute the cut grass which might otherwise become clogged in the parts of the machine immediately behind the cutter. The advantage of the multi toothed cutter is that it uses a great deal less power than the normally used vertical axis rotating blade cutter and can be mounted close to the machine when used in the front or rear position. It can also distribute the cut grass evenly and finely for when it is not required to be collected. However the cutter might also be a cylinder type, and could also alternatively be in the front, centre or behind the machine and could include its own motive powered collecting system. As previously stated it would be possible to have differing types of cutting devices and these could be interchangeable and at interchangeable positions, using the same motor.

The height of the cutter would be adjustable by either a hand or foot mechanism. The method of varying the cutter height does not form part of this invention.

The driving wheels, normally the rear two, would be either driven by a single motor via a differential gear or each wheel being driven by its dedicated motor with any gearing if required. in the event of four wheels being driven by four separate motors the machine would be capable of operating on very severe inclines or sites of poor adhesion not capable of being

S

cut by existing mowers.. The cutter or cutters would be driven by an independent motor or motors and the rate of operation could be controlled independently of the speed of the machine, if so desired. The engine driving the generator, and the generator itself might be at the back of the machine beneath the seat of the driver, or any other suitable position if desired, and a lead-acid accumulator would be incorporated to start the motor, but also a deep cycle type could be included and used to operate the machine for short periods without the engine running if desired. The drive motor or motors for operating the cutter or cutters with their appropriate operating connection would be adjacent to the cutters and in the attached example diagram is shown vertically mounted in the centre position of the machine above the cutter.

Such a machine would be less costly to make, lighter in weight, more efficient at cutting in awkward positions, and considerably more easily controlled than existing grass cutting machines.

The invention will now be described solely by way of one example only of the application of the features of the patent and with reference to the accompanying drawings: Fiigure 1 shows a general arrangement of a light weight mower suitable for domestic use for cutting up to about one acre including sloping grass.

Figure 2 shows a possible design arrangement for mounting a front and rear mounted scissor type cutter driven by electric motors.

Figure 3 shows a possible method of providing the reciprocating motion of the moving cutter driven by an electric motor mounted with its axis of rotation vertical.

In figure 1 a machine is described by way of an example which would be advantageously of use where adhesion might also be an important factor, but would also be ideally suitable for use in medium/large sized domestic gardens. Here the front wheels are stearable and cutters are fitted at the front and rear of the machine The machine consists of a platform (1) with two front wheels (2) and two rear wheels (3) both two rear wheels in the particular model described being driven by independent electric motors with including any required gearing (4).

The front wheels are steerably controlled by a steering wheel (5). Either front or rear or all of the wheels could be but need not be sprung. The engine, either liquid or gas fuelled, coupled to the generator providing the electric current for operating the machine and possibly including the battery, all not indicated, might be housed in the compartment (6) at the rear of the machine beneath the seat (7). Alternatively the batteries could be housed in the front pedestal.(8) should space be not large enough to contain all three items. In this machine toothed cutters (9) are shown at the front and rear of the machine projecting outside the width of the machine on one side, in this case the right side, and are driven by their dedicated electric motors (10) mounted on cradles (11) which are adjustable in height by any conventionally used mechanisms, and which would be operated through linkage not shown either by foot or by hand, the front cradle and cutter being shown lowered and the rear cradle Alternatively one cutter-motor unit could be alternately fitted to the front or rear position depending on the usage required.. It is possible that in some cases the cutter would be required to be shielded by a protective guard, not shown, to prevent personal damage, although examples exist of such cutters being legally operated without guards, for instance for hedge trimming. The front pedestal has a fascia panel with instrumentation and switches etc. and supports the steering column. and might have operating levers or/or other controls for operating the machine such as forward/reverse control. Levers (12) might be used for raising and lowering the cradles and a foot pedal (13) might be used to control speed. The machine need not conform to the construction and arrangement of components described above which is given only as in indication of one form in which a machine could be constructed embodying the features of this patent. The machine as described here would particularly be beneficially used in medium to large domestic being capable of operation with considerably less power requirement and hence economy in running and first cost, and particularly would be simple to operate and with its front cutter would be capable of reaching areas of grass not possible with central or rear cutter only machines. The system based on two or four motor driven wheels would be ideal for use on relatively steeper embankments. The features described above are all known in themselves and are in use independently for other purposes, and it is the combination of these features that is novel and uniquely put to use with great benefit.

In figure 2. is shown in more detail a cutter mounting that might be used on the machine as described above. Here the front cutters are shown consisting of an upper toothed blade (1) capable of sliding on a stationary lower toothed blade (2) guided in its movement by a number of slots (3) in the upper blade, co-operating with fixed pins in the lower blade (4). The motor (5), with its axis vertical, and the housing for the mechanism to convert its rotary action to a reciprocating movement is mounted on an extension of the lower cutter plate, and brackets (6) attached to this plate connect the cutters to a cradle (7) which pivots on brackets attached to the chassis of the machine (8). The cradle may be raised and lowered by any suitable mechathsni, and springs (9) take some of the weight of the assembly. A seal (10) is provided between the moving upper cutter and the housing of mechanism driving the upper cutter to retain lubrication and prevent ingress of moisture and mud etc. generally. It will be seen that the mechanism, its housing, the motor, and the direction of the cutting blades themselves are all reversed as a unit on the cradle which is then mounted with the hinged end in front of the cutters to provide an assembly for when the cutter is mounted at the rear of the machine (11) A further description of the mechanism itself is given in figure 3 In figure 3. a method is shown of translating the rotary motion of the motor shaft into the reciprocating motion of the upper cutter. Here the lower cutter (1) is rigidly fixed to the cradle and the upper cutter (2) is controlled to a sliding motion by a number of slots (3) co-operating with pins (4) rigidly fixed in the lower cutter, .and where the tooth pitch of the upper cutter is greater and stroke is greater than the tooth pitch of the lower cutter. A pin (5) is attached to a crank (6) on the motor shaft (7) which co-operates within a slot (8) in the upper cutter in such a way that the rotary motion of the motor shaft causes the upper cutter to reciprocate back and forth on the lower cutter. The description here is not intended to show the actual construction of the mechanism but to show the only the principle on which it operates

Claims

Claim 1. A mechanically propelled machine for cutting grass consisting

of an engine fuelled by liquid or gas driving a generator where electric power from the generator is variably controlled and fed to an electric motor or motors driving the machine.

Claim
2. A machine as described in claim I. where the power to the electric motor or motors driving machine can also be independently controlled and fed to an electric motor or motors to operate the cutter or cutters..

Claim
3. A machine as described in claims I and 2 above where the front wheels are stearable and where the cutter is at the front of the machine.

Claim
4. A machine as described in claims 1 and 2 above where the front wheels are stearable and where the cutter is at the rear of the machine.

Claim
5. A machine as described in claims I and 2 above where the front wheels are steerable and where the cutters are situated at both back and front of the machine.

Claim
6. A machine as described in claims 1 and 2 above where the front wheels are steerable and where a single cutter may be mounted either at he back or the front of the machine Claim 7 A machine as described in claims I and 2 above where the cutter is a reciprocating multi-toothed type where the tooth pitch of the upper blade is similar to the tooth pitch of the lower blade.

Claim 8 A machine as described in claims I and 2 above where the cutter is a reciprocating multi-toothed type where the tooth pitch and stroke of the lower blade is either smaller or larger than the tooth pitch of the lower blade.

Claim 9 A machine as descried in claim 2 where the electric motor driving the cutter is mounted with its axis of rotation vertical to drive the cutter via a crank pin rotating on a vertical axis Claim 10 A machine generally as described.above.

Amendments to the claims have been filed as follows Claim I. A powered machine for cuttiiig grass where the cutting device consists of a reciprocating multi-toothed blade or blades co-operating with a fixed multi-toothed blade or blades said reciprocating blade or blades being powered by an electric motor or motors where said cutting device is mounted in front of the front wheels of the machine which are steerable.

Claim 2 A powered machine for cutting grass as in claim 1 where the electric power for driving the cutting device is provided by a generator driven by a liquid or gas powered prime mover.

Claim 3. A powered machine for cutting grass as in claims I or 2 where at least one of the driving wheels of the machine is driven by at least one electric motor and where the electric power to drive said wheel or wheels is provided by an electric generator driven by a liquid or gas powered prime mover.

Claim 4. A powered machine for cutting grass as in any claim above where the electric power to drive the cutter and the electric power to drive the machine may be varied independently so as to vary the speed of the cutter and br machine independently.

Claim 5 A powered machine for cutting grass as in claim 1 where the the motor or motors driving the cutting device are mounted substantially within the line of the.front wheels Claim 6. A powered machine for cuffing grass as in any of the above claims where the cutting device is mounted at the front of the machine on a height adjustable chassis and a second cutting device is mounted on a height adjustable chassis or rack at the rear of the machine Claim
7. A powered machine for cutting grass as in any of the above claims where the cutting device is mounted at the front of the machine on a height adjustable chassis but may be interchangeably mounted as a unit with its motor on a height adjustable chassis or rack behind the rear wheels of the machine.

Claim.
8. A powered machine for cutting grass as in any of the claims above where the shaft of the motor or motors driving the cutting device or devices are mounted with their shafts substantially verticaL Claim
9. A powered machine for cutting grass where the cutting device consists of a reciprocating multi-toothed blade or blades co-operating with a fixed multi-toothed blade or blades where the pitch of the teeth of the fixed blade or blades is either greater or less than the pitch of the teeth of the reciprocating blade Claim
10. A powered machine for cutting grass as generally described.