Note: Descriptions are shown in the official language in which they were submitted.
BACKGROUND OF THE INVENTION
The invention is directed to a rotary lawnmower ha-ring a two part
housing enclosing and carrying the drive motor. The dri~e motor has
an output shaft adapted for carrying the cutting knife. The wheels of the
lawnmower are mounted on the lower part of the housing as are means
for mounting a handle.
In the conventional rotary lawnmower, the motor is mounted on a
lower housing equipped with a peripheral wall facing downwardly to de-
fine an encLosed space wherein the cutting knife is mounted. In addition,
conducting surfaces directed downwardly from the upper surface of the
lower housing body are provided to conduct the grass clippings and the
air stream generated by the rotation of the cutting knife to the grass
outlet port in the desired manner. The motor is covered by an upper
housing part which constitutes the motor hood. The upper housing part
is then secured to the upper surface of the lower housing part. In ad-
dition, the wheels are mounted to the lower housing part outside of the
downwardly extending peripheral wall thereof. The lower hou,sing part
aLso carries means for securing the lawnmower handle.
The conventional rotary lawnmower also has uneven surface con-
tour in the space defined by the lower part of the housing and surround-
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ing the cutting knife. The uneven surface contour often includes angled
conducting paths on which grass clippings can become lodged making it
very difficult to clean,
The wheels of the conventional~ lawnmower are often disposed lat-
erally outside of the lower housing part so that the wheels will not be-
come blocked by grass clippings as is the case when the wheels are
disposed in the cutting region. However, with the wheels mounted out-
side of the lower housing part, it is not possible to come close to ob-
jects such as walls or trees during the grass cutting operation. In such
a situation it is necessary to perform a trimming operation which is
usually done manually. Further, the wheels can become jammed in
bushes and branches.
SUMMARY OF THE INVENTION
In view of the foregoing, it is an object of the invention to provide
a rotary lawnmower which has a relatively low profile and which has
smooth, easy to clean surfaces especially in the cutting region.
The foregoing object is achieved with the lawnmower according to
the invention by providing a dish-like body defining the chassis of the
lawnmower and having an upwardly extending side wall and a substantially
continuous bottom wall. A motor equipped with an output drive shaft has
a free end and is mounted in the dish-like body so as to cause the free
end of the drive shaft to penetrate the bottom wall for carrying a cutting
blade thereon. A cover interfaces with the dish-like body to conjointly
define therewith a housing enclosing the motor.
According to another feature of the invention, the cover can be of
a dome-like configuration having a lower edge conjointly defining an
interface line with the upper edge of the side wall of the dish-like body.
Thus, the housing of the motor is made up of two parts of which
the lower part is configured as a deep dish opening in the upward
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direction and the upper part is also dish-like or dome-like and opens in
a downward direction. These two parts conjointly define the space for
receiving the motor. Because of this configuration, the drive shaft of
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the motor can be relatively short since it must only penetrate the bottom
wall of the dish-like body. It is necessary for the bottom wall to be
above the cutting plane of the cutting knife only a small distance at the
region of the bottom wall where the shaft penetrates the latter.
In addition, the bottom wall surface can be formed so as to be re-
latively smooth so that it is easy to clean. The dome like cover serves
primarily for covering the total inner region of the dish-like body and
increases the stability of the entire housing because of its connection
with the lower dish-like body.
In order to achieve a form for the bottom wall surface which faci-
litates the flow of the grass clippings and the air currents generated by
the cutting knife, an upwardly curved recessed passage is formed in the
bottom wall in the region of the cutting knife. The passage is of an-
nular or spiral configuration and is disposed in concentric relationship
to the motor drive shaft. This passage can be in the form of the upper
half of a toroid.
This kind of configuration of the bottom surface is also known in
conventional lawnmowers; however, the arcuate passage in such lawn-
mowers is formed in a massive base plate having no upwardly extending
peripheral wall and the housing is not made up of two interfacing dish-
like parts. In the conventional lawnmower, the drive motor is simply
mounted atop the base plate and the upper part of the motor is covered
by a small motor hood.
In contrast thereto, the chassis of the lawnmower according to the
invention forms also a part of the housing of the motor and both the
dish-like body defining this chassis and the dome-like cover are pre-
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Eerably made ~of synthetic material. These parts can be made without
difficulty by an injection molding process.
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~ In order to achieve for the lawnmower according to the invention
!~,' the capability of cutting close to walls and trees while at the same time
preventing blockage of the wheels through bushes and branches, the low-
;~ er dish-like body has chambers formed therein which open downwardly
for receiving therein the wheels so that the wheels are within the lower
housing body.
Preferably, the cover is configured so that it has wall portions
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which extend downwardly toward the interface line between the cover and
the lower dish-like body. In this way, the side wall of the lower dish-
like body does not have to extend upwardly all the way to an elevation
corresponding to the upper end of the drive motor whereat a ventilating
fan is mounted.
It is also an object of the invention to provide a lawnmower which
provides improved noise attenuation.
This is achieved according to still another feature of the invention
wherein an upwardly extending annular wall is provided within the housing
conjointly defined by the dish-like body and the cover. The annular
wall is arranged in surrounding relation to the motor and is preferably
formed in one piece with the dish-like body. The annular wall supple-
ments the noise attenuation achieved by the enclosed housing defined by
the dish-like body and cover.
The above objects and advantages of the invention will become
more apparant from a consideration of the detailed description to follow
taken in conjunction with the drawing annexed hereto.
BRIEF DESCRIPTION OF THE DRAWING
FIG. 1 is a perspective view of the lawnmower according to the
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invention;
FIG. 2 is an elevation view, partially in section, of the lawnmower
according to the invention;
FIG. 3 is an elevation view of the lawnmower with the cover shown
; separated from the lower, dish-like body;
FIG. 4 is a plan view of the lawnmower of FIG. 1 with two break-
out portions showing the motor and wheel mounting arrangement respect-
ively;
FIG. 5 is an elevation schematic diagram showing how the wheel
can be positioned at three different elevations; and, `~
FIG. 6 is a section view taken through one of the wheel compart-
ments of the dish-like body of the housing.
DESCRIPTION OF THE PREFERRED
EMBODIMENTS OF THE INVENTION - `
Referring now to FIGS. 1 and 2, the housing of the lawnmower in-
cludes a dish-like body 1 and a dome-like cover 2. The cover 2 and
dish-like body 1 are joined to each other along an interface line 3. The
side wa~l 4 of the dish-like body is directed upwardly and the cover 2
has edges 5 which can be configured so as to overlap to a degree the
upwardly extending side wall 4 of the dish-like body 1. The dish-like
body 1 is provided with projections 6 which extend upwardly and the
cover is provided with corresponding projections 7 extending in the down-
ward direction. By means of corresponding pairs of these projections,
the cover 2 and dish-like body 1 can be secured to each other with the
aid of screws 8.
Referring to FIGS. 2, 3 and 4, an electric motor 9 is mounted in
the dish-like body 1. The motor 9 is surrounded laterally by an up-
wardly extending annular wall 10 formed as an integral part of the dish-
like body 1. The wall 10 is in turn, surrounded by the upwardly extend-
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ing side wall 4 of the dish-like body 1. This configuration achieves ex-
cellent cooling and improves noise attenuation. The motor is connected
with a capacitor 11 by means of leads 12 on the one hand and with a
connecting cable 13 for the power supply on the other hand.
Referring to FIG. 2 a ventilator 14 is mounted at the upper end of
the motor shaft and is provided with a marking 15 (FIG. 4) so that ro-
tation of the motor will be indicated during operation and even after the
motor is disconnected. The marking is viewed through a window 16 in
the upper part of the cover 2.
The lower free end of the motor shaft penetrates the opening 17 in
the bottom wall 18 of the dish-like body 1 and carries a ventilator 19 as
well as a cutting knife 2 O.
As FIG. 2 illustrates, the dish-like body includes the bottom wall
18 which defines a substantially continuous bottom surface and which in-
cludes a surface region 21 defining a conducting path of arcuate section
formed in concentric relationship to the opening 17. The surface region
21 of the bottom wall 18 corresponds to the upper half of a toroid and is
curved upwardly as shown in FIG. 2. In this way, there is achieved a
cutting space which facilitates the flow of air and grass clippings. The
cutting space is defined by a smooth surface having no corners wherein
grass clippings can collect and which is easy to clean. This semi-tor-
oidal arcuate region leads to the grass discharge outlet 39. The grass
outlet is covered from above with a hood 22.
The dish-like body 1 has receiving means 23 formed thereon for
removably holding a handle 24 of the lawnmower.
The wheels 25 of the lawnmower are held in chambers 26 open in
a downward direction. The chambers 26 are located within the dish-
like body 1 at the lateral peripheral regions thereof and are substantially
sealed off with respect to the space enclosed by the dish-like body 1 and
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the cover 2. These chambers 26 are formed in the dish-like body 1
and are made as one piece therewith.
The wheels 25 are held with respective bolts 27 as shown in FIG.
6. The bolts 27 have a four-flat profile 28 when viewed from the
threaded portion thereof. The four-flat profile 28 is directly adjacent
the screw-head 29. A bearing bushing 30 is mounted on the threaded
bolts 27 for accommodating the wheel 25 and is pressed against the
four-flat profile 28 with the aid of a wing-nut 31. The bushing 30 ex-
tends outwardly beyond the inner edge of the wheel 25 so that the wing-
nut 31 will not come into contact therewith thereby permitting free ro-
tation of the wheel.
The bolt 27 serves as the wheel axle and is mounted in one of the
openings 32, 33 or 34 at the inner chamber wall on the one hand, and
by means of one of three correspondingly aligned latching openings 35,
36 and 37 in the outer wall (FIG. 5) on the other hand. The openings
35, 36 and 37 in the outer wall are lozenge-shaped as shown in FIG. 5
and are formed so that the four-flat profile 28 can be securely received
therein. In order to ensure that the four-flat profile 28 is secured in
position with respect to the sides of the lozenge-shaped openings and to
ensure that the wing-nut 31 will press the bolt head 29 against the outer
surface of the chamber wall, the threaded bolt 27 is also held in the
opening 33 (FIG. 6) so that a stationary axle is provided for the wheel
25.
In order to adjust the height of the wheel 25 with reference to the
bottom surface of the bottom wall 18 of dish-like body 1, the wing-nut
31 is loosened so that the four-flat profile 28 can be pulled laterally
out of the latching opening 36. In this way the free end of the threaded
bolt 27 comes free of the opening 33. Should it be desired to reduce
the distance of the bottom surface of the dish-like body 1 from the
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ground the threaded bolt is pulled from the outer chamber wall and
moved upwardly to the opening 37 and is then pushed inwardly again so
that the four-flat profile comes into engagement with the opening 37.
At the same time, the free end of the threaded bolt 27 is guided into
the opening 34 in the inner chamber wall. Then the wing-nut 31 is
again tightened and the threaded bolt 27 again constitutes a stationary
ax~e for the wheel 25.
As shown in FIG. 2, the bottom wall 18 of the dish-like body 1
includes a relatively flat region 38 which extends substantially into the
cutting plane of the cutting knife 20. The space for the air flow and the
removal of the grass clippings is achieved by annular recess means
having surface 21 formed in the bottom wall 18 and located concentrically
to the opening 17. The spacing between the cutting knife 20 and the -
lower end of the motor is substantially smaller than it is in conventional
lawnmowers having a housing made up of two parts.
Further, the motor is completely surrounded by the dish-like body
1 and cover 2 as well as laterally by the annular wall so that a subst-
antial attenuation of noise results.
It is apparent that the dish-like body 1 and cover 2 can be simply
made by means of an injection molding process whereby, for example,
the lower dish-like body is formed with projections 8 and the chambers
26 as well as the annular wall 10. In corresponding fashion, the dome-
like cover 2 can likewise be formed to have the corresponding projec-
tions 7.
Although the drive motor disclosed in connection with the above
description is an electric motor, it should be understood that other drive
motors such as a gasoline engine could be utilized.
