Lawn edger

A lawn edger having a motor (14) arranged with a vertical axis of rotation, a fan and cutter assembly (15) within a hollow frame (11), cutting blades (17) being below the fan blades (16) and extending not only radially outwardly from the axis of rotation but also axially downwardly so that they slope towards the cutting edges, and cutting is affected over a small segment of the periphery of the cutting blades, for example, by tilting the lawn edger to one side.

This invention relates to a power operated machine which is useful for 
cutting grass, for example for edging an area of lawn. 
BACKGROUND OF THE INVENTION 
Power operated lawn edgers have been proposed heretofore, and in some 
instances they rely upon blades which rotate about a horizontal axis which 
is transverse to the direction of movement of the implement. This 
arrangement works particularly well but requires considerable power input, 
and the object of this invention is to provide a much simpler device which 
requires less power input, but is nevertheless effective both in the 
cutting of grass and the disposing of it. 
One of the problems which is encountered with lawnmowers and lawn-edging 
machines is the tendency for impact of grass, stones, grit and the like to 
cause blunting of the cutter blades, and one object of this invention is 
to provide improvements whereby this effect is less than with some prior 
art machines. Another problem which is encountered is that if the blades 
are driven about a horizontal axis, for example, they can encounter 
unyielding substrates and cause considerable damage, and another object of 
the invention is to provide improvements whereby the likelihood of such 
damage is substantially reduced. 
BRIEF SUMMARY OF THE INVENTION 
Briefly, in this invention a lawn edger has a motor arranged with a 
vertical axis of rotation, a fan and cutter assembly within a hollow 
frame, the cutter blades being below the fan blades and extending not only 
radially outwardly from the axis of rotation but also axially downwardly 
so that they slope towards the cutting edges, and cutting is effected over 
a small segment of the periphery of the cutting blades, for example, by 
tilting the lawn edger to one side. 
More specifically, the invention consists of a lawn edger comprising a 
hollow frame, ground engaging wheels supporting the frame, a motor carried 
by the frame having a rotor with a vertical axis of rotation, a fan and 
cutter assembly within the hollow frame, said fan and cutter assembly 
comprising a plurality of fan blades which extend outwardly from the axis 
of rotation, and a plurality of cutting blades beneath the fan blades and 
which extend axially downwardly and radially outwardly from the axis of 
rotation, and means coupling the rotor to the fan and cutter assembly for 
driving the latter. 
Since cutting is effected over a small segment, there is a gradual lead 
into and out of the cutting zone by the blades as they traverse their path 
of travel and this does much towards limiting the damage to blades due to 
encountering unyielding obstructions. Furthermore, the under surfaces of 
the blades will abrade against the substrate with which they co-operate 
and this provides a "self-sharpening" action. 
Notwithstanding the above however it is still possible for damage to occur 
and in an embodiment of the invention this damage is further reduced by 
having the blades sufficiently flexible and resilient that they are 
deflectable upwardly against the underside of respective fan blades, or 
hinged and springloaded downwardly. The cutter blades can for example be 
of spring steel strip or can be of a moulded polymeric material such as 
polyurethane. 
Heretofore lawn edgers have usually been constructed to be supported by at 
least three wheels, but is is desirable with this invention that an edger 
can be tilted in any direction, and in one embodiment of the invention 
there is a ground wheel located on the axis of rotation, and a pair of 
half wheels on a transverse axle rearwardly thereof, the half wheels being 
movable together to constitute a single wheel, or being separable to 
constitute two transversely spaced wheels. When the half wheels are 
together the edger can be tilted transversely as well as in a fore and aft 
direction, and when they are separated the machine can be stably supported 
by three ground engaging surfaces.

DESCRIPTION OF THE EMBODIMENT 
In this embodiment, a lawn edger 10 comprises a hollow frame 11 which is 
supported by ground engaging wheels 12 and 13. 
A motor 14 (in this embodiment depicted as an electric motor but an engine 
can be used in lieu thereof) is carried on the hollow frame 11, and is 
coupled by appropriate coupling means to a fan and cutter assembly 15. The 
coupling means in this embodiment would typically comprise a dish-like 
member which is arranged to be frictionally engaged by the throw out 
members of a centrifugal clutch (not separately shown), this being 
particularly convenient because the motor 14 can then be withdrawn from 
the hollow frame 11 with a minimum of disassembly. 
As best seen in FIGS. 5 and 6, the fan and cutter assembly comprises fan 
blades 16 and cutting blades 17. In FIG. 5 the cutting blade 17 forms part 
of a unitary moulding of high durometer polyurethane elastomer, while in 
FIG. 6 the cutting blades 17 are formed from strip spring steel. In both 
instances however the cutting blades are sufficiently flexible and 
resilient to be deflectable upwardly against a respective fan blade 16. In 
the described embodiment, each cutting blade 17 is located directly below 
a respective fan blade 16. It will be noted that the cutting blades 17 
extend axially downwardly as well as radially outwardly from the axis of 
rotation designated `A`. 
The hollow frame 11 is mostly circular, but is generally also of volute 
shape as can be seen best in FIG. 2, and comprises an upper wall 21 which 
is located over spigots 22 and retained to the main part of the frame 23 
by fasteners (not shown), above an opening designated 24 of sufficient 
diameter that the fan and cutter assembly 15 can be lifted from the main 
part of the frame 23 for maintenance purposes, for example for replacement 
of cutting blades 17. (See FIG. 3). 
Also as shown best in FIG. 3, the hollow frame 11 comprises a lower wall 26 
which is generally discoid in shape, and this is fixed with respect to the 
main portion of the frame 23, but the lower wall 26 and the side wall 27 
are each discontinuously about their respective peripheries to provide an 
inlet opening 28 which extends only part way around the periphery of the 
hollow frame 11, the hollow frame 11 also having walls 29 defining an 
outlet opening 30. As seen best in FIGS. 1 and 2, the outlet opening 30 
has secured to it a refuse container 31 which may be a "hard wall" 
container as illustrated or may be a pervious bag. 
There is provided a shutter 34 which may be secured over the inlet opening 
28, and also a suction hood 35, the opening in the side wall 27 of the 
hollow frame 11 extending sufficiently that the shutter 34 and the suction 
hood 35 will close that opening, but alternatively, the shutter 34 can be 
moved around to replace the closure otherwise effected by the suction hood 
35 leaving an opening in the side wall laterally of the path of travel of 
the lawn edger 10. Thus the lawn edger 10 can be effective in edging a 
lawn laterally of the axis of rotation `A`, or it can be used for suction 
pickup of particulate material. It may be noted that although the hollow 
frame 11 is of partly volute shape, the air flow does not follow the 
normal path of air flow in the usual type of centrifugal fan, but rather 
the flow is induced by the periphery of the fan and cutter assembly 15, 
which, in this rotation, entrains air either from the suction hood 35 or 
through the opening 28, and causes that air to pass outwardly through the 
outlet opening 30. 
As explained previously, it is desirable that the edger should be capable 
of being tilted either transversely or longitudinally. In order to achieve 
a longitudinal tilt, the ground engaging wheel 13 is coaxial with the axis 
of rotation `A`, that is, the point of contact between the wheel 13 and 
the ground, enables a universal tilt to take place. However, this 
universal tilt can only take place when the ground engaging half wheels 12 
are contiguous with one another as shown in full lines in FIG. 2. FIG. 2 
illustrates a transverse shaft 38 along which the half wheels 12 can be 
moved axially, and also spacers 39 hinged to the hollow frame 11, and 
positionable over the shaft 38 to either retain the half wheels 12 
contiguous with one another so as to constitute a single wheel, or 
alternatively, to separate the half wheels 12 as shown in dotted lines in 
FIG. 2, thereby providing a tricycle support for the lawn edger. 
Other aspects of the machine, for example, the handle 41, are in accordance 
with known art. 
Whether the cutting blades 17 are of resilient elastomer as shown in FIG. 5 
or are of strip spring steel as shown in FIG. 6, they can nevertheless be 
deflected upwardly by engagement with an unyielding substrate, and their 
path of rotation will be such in both instances as to effect a 
"self-sharpening" condition. 
The facility of having an either bicycle or tricycle support is of 
considerable value, since it enables the lawn edger to be used with a much 
larger range of possible conditions than can be achieved when either one 
or the other is used alone.