Note: Descriptions are shown in the official language in which they were submitted.
108;~875
Background of the Invention
The present invention relates to a cultivator device,
and more particularlv, to a powered, hand-held cultivator of
the type used for cultivation of a small garden or flower beds.
Cultivation of a garden plot is a time-consuming but
necessary task to ensure vegetable plants having good yield.
Typically, a gardener will use an implement, such as a hoe, to
loosen and turn the soil between adjacent rows of plants. This
is done for several reasons. Any weeds growing in this area
are destroyed. At the same time, earth which has become hard
and packed down from watering the plants is loosened. This
allows air to penetrate the soil and, additionally, facilitates
~atering the plants. Since this sort of cultivation can be
extremely time cons-~ing and requires substantial physical
labor, several power-driven implements have been developed for
cultivation.
U. S. patent No. 2,888,084 issued May 26, 1959 to
Trecker, shows a hand-held cultivator which is powered by a
lawn mower. The cultivator includes either one or two culti-
vator blade units, each unit being rotatable about a verticalaxis and including a number of blades. The single blade con-
figuration of the Trecker devicc would be very difficult to
use since rotation of the blade will apply a lateral force to
the implement. The dual blade confiyuration is limited in its
depth of cul~ivation and would not appear to move easily
through the soil.
Another type of power-driven cultivator tool has
blade units which rotate in a vertical plane about horizontal
,
~,1 ' ' ' ~ j
~,.. , . - : . .
- , : - .
:1~83875
axes. Cultivators of this sort facilitate movement through
the soil because the blades are rotated in the direction of
movement and are nct completely submerged below ground level.
Since the blade units are ~ypically positioned on opposite
sides of the cultivator housing, however, this type of culti-
vator will leave uncultivated a strip of soil directly be-
neath the housing. It will therefore be necessa~y to make
multiple passes in order to ensure complete cultivation.
Additionally, vibration and upward reaction of cultivators
of this type may become excessive depending upon soil
conditions.
As shown in U. S. patent No. 1,021,228 issued
March 26, 1912 to Ayers, and in U. S. patent No. 368,082
~; issued Auguct 9, 1887 to Featherstone, cotton choppers
suited ~or above ground operation have used multiple blades
15 r~tating on oblique axes. U. S. patent No. 2,787,106
issued February 26, 1952 to Brown shows a hand-operated
cultivator having octagonal blades which are freely rota-
tably mounted and positionable in oblique axes. Finally,
~` U. S. patent No. 2,363,268 issued November ?1, 1944 to
Schiel et al, shows a thinning device having a notched
cutter disc rotatable about oblique axes. The notches
align to permit only evenly spaced plants to continue to
grow with the remainder of the plants being cut by the
blade edges.
It is seen, therefore, that there is a need for
a hand-held power cultivator having stable operating char-
acteristics and operable to cultivate across the éntire
width of the cultivator.
--3--
.
.
1083875
SUMMARY OF THE INVENTION
The invention in ones aspect provides a hand-held
power cultivator comprising a housing, an electric drive motor
in said housing, reduction gearing connected to said drive
motor, means in the bottom of said housing rotatably support-
ing a pair of output shafts in angled relation to each other
and to a vertical plane extending therebetween, said shafts
being inclined outwardly at an angle of less than 45 to said
vertical plane and being laterally spaced from each other,
gear drive means interconnecting said shafts to reduction
gearing providing for counter-rotational movement of said
shafts to each other, and a separate tined ground tiller
carried on each of said shafts at the lower ends thereof,
each of said ground tillers having a support portion terminated
in a plurality of peripherally arranged, outwardly angled
tines which are proportioned to engage the ground underlying
the tiller, and which move about circular inclined paths, said
paths being in non-intersecting relation, and the adjacent
said tines at their closest proximity in said paths being
angled to extend substantially parallel to said vertical plane.
Accordingly, it is an object of the present invention
to provide a cultivator device having blades which are rotated
about axes inclined to the ground; to provide such a cultivator
in which the blades rotate in planes which intersect generally
beneath the center of the cultivator; to provide such a
cultivator in which the planes of rotation form an angle
substantially less than 45 to the ground being cultivated;
to provide such a cultivator in which the individual blades :;
may pass alternately across the center line of the cultivator;
and to provide such a cultivator in which stable operation
is ensured.
These and other objects and advantaqes of the
invention will be apparent from the following description, the
accompanying drawings, and the appended claims.
-4-
1(~83875
Brief Description of the Drawings
Fig. 1 is a side view of the cultivator of the
present inventlon;
Fig. 2 is an enlarged view of the cultivator
S with portions broken away and in section;
Fig. 3 is an enlarged partial view of the culti-
vator as seen looking left to right in Fig. 1, with portions
broken away and in section;
Fig. 4 i.s a view of an alternative blade arrange-
ment as seen looking up toward the bottom of the cultivator;
Fig. 5 is a bottom view of another alternative
blade construction;
Fig. 6 is a side view of the blade arrangement of
Fig. 5;
Fig. 7 i8 a sectional view of a single blade taken
generally along the line 7-7 in Fig. 6;
Fig. 8 is a rear elevational view of another
embodiment of the invention;
Fig. 9 is a side elevational view of the embodi-
ment of Fig. 8;
Fig. 10 is a partial enlarged sectian through the
, housing taken generally along the line 10-10 of Fig. 9;
Fig. 11 is a bottom plan view of the modified
soil agitator employed with the embodiment of Fig. 8;
Fig. 12 is a side elevational view of the agitator
of Fig. 11; and
Fig. 13 is a sectional view through one of the
~, . .
~, tines taken generally along the line 13-13 of Fig. 12.
,
.
_5_
.
,
., ~ . . . .
1083875
Description of the Preferred Embodiments
Pigs. 1, 2 and 3 illustrate one preferred embodi-
ment of the present invention. A hou,sing 15 is provided
for mounting a plurality of cultivator blade means 20 and
21 which rotate to cultivate the soil. Blade means 20 and
21 are mounted on the housing exterior and are rotatable
about axes which are oblique to the vertical axis of the
cultivator and which form an inverted V, as seen in Fig. 3.
The blade means thus rotate in planes which intersect gen-
erally beneath the center of the housing. The tips of theblades may project out of these planes and include working
edges. Since the blade means are not confined to a single
blade, it is clear that they wlll not rotate in a single
plane. Each point on the blade means will define a plane,
during rotation which will converge with a plane defined
by a corresponding point on the other blade means.
A power means in housing 15 is provided for
driving the cultivator blade means 20 and 21. Th,e power
means comprises an electrical motor 22 and a d~ive train
for transferring power from the motor 22 to the cultivator
blade means 20 and 21. The drive train includes a spur
gear 23, idler gear 25, spur gear 27, worm 31, work shaft
,30, and worm gears 33 and 36. Spur gear 23, spur gear 27,
and worm gears 33 and 36 may typically be formed from plas-
tic with idler gear 25 formed of powdered metal and wor~ 31made of steel.
Motor 22 may typically comprise a 1/4 horsepower,
universal motor with a no-load speed of 24',000 rpm. Gears
23, 25, and 27 provide a 2-to-1 reduction in rotational
1083875
speed. There is a further 30-to-1 reduction between worm
31 and worm gears 33 and 36, thus providing an overall
60-to-1 reduction speed between motor shaft 38 and blade
sha~ts 40 and 42. Thus, the theoretical no-load operating
speed of ~he blade means 20 and 21 would be 400 rpm. In
operation, of course, the loading on ~he motor reduces the
rotational speed of blade means 20 and 21 to approximately
200 rpm.
The handle 43 includes a grip 44. A trigger
switch 45 controls thé application of electrical power
from the power cord 46 to the electrical motor 22.
The blade configuration shown in Figs. 1 and 3
i8 such that blade means 20 and 21 will approach, but will
not pass through, a v¢rtical plane extending along the
center of the cultiva~or in the direction of cultivator
movement. The minimum distance be~ween blades 47 and 48
may be on the order of 1/4 to 1/2 inch. Because soil has
a relatively low column strength, the slight lateral vibra-
tion of the cultivator will ensure that even the soil in
the gap between blades ~7 and ~8 will be cultivated. In
operation the device may work into the soil approximately
to the level shown in Fig. 3. Shields 50 and 52 are pro-
vided to prevent stones or other debris from being thrown
by the blades.
~ecause of the oblique rotational planes of the
blade means of the device, lateral vibration of the culti-
vator will be ~inimized. Further, if the blades should
las3s7s
strike a rock or other obstruction, the oblique planes of
rotation will minimize the amount of upward thrust exerted
on the cultivator. A portion of the thrust will be lateral
and this will tend to be opposed by the other blade and
soil adjacent the opposite side of the device. It should
be noted that the angle formed between the plane of rota-
tion of one of the blade means 20 and 21 and the ground
surface is substantially less than 45. When so configured,
the blade sections 47 and 48 extend substantially downward
into the soil as they pass adjacent the center of the
housing.
Fig. 4 shows an alternative embodiment of blade
structure. As indicated by the dashed lines, the some-
what larger diameter blade means 20a and 21a provided in
this embodiment hav0 tips which alternately pAqs through
a vertical plane extendin~ along the center of the culti-
vator in the direction of cultivator movement. The blades,
of course, must be synchronized as shown, so that they
will intermesh during rotakion.
' Another alternative blade structure is shown in
Figs. 5, 6 and 7. Thi~'cultivator blade mechanism is
constructed of plastic material and, may typically be
formed b~v injection molding. A blade disc piece 55 has
a plurality of individual blades or tines 57 which extend
obliquely from the plane of the disc 55. Each blade, as
shown in Fig. 7, is square in cross-section. It' should be
noted that edges 60 extend in the direction of-blade mo~e- ' '
ment and provide a type of cutting edge. This blade con-
stFuction is suitable for cultivating'situations in which
, . . .
-8-
, ~
. .-. . , ~ . .. . .
~083875
the soil is looser, and offers le~s resistance. The blade
construction of Figs. 5-7 provides somewhat more flexible
tines and edges which are not so sharp and unyielding.
Another embodiment of the invention is illus-
trated in Figs. 8-13. Referring first to Figs. 8 and 9,
a hand-held and hand guided cultiva'or constructed accord-
ing to this i.nvention is shown as having a housing 80 corres-
ponding in function to the housing 15 previously described.
The housing 80 is injection molded of plastic material and
is formed in,split halves 80a and 80b and suitably joined
together. A handle tube 82 is mounted on the rear of the
housing and extends at an angle therefrom and terminates
in a grip 83 which preferably incorporates an electric
trigger switch 84. Spaced a short distance downwardly on,
lS the handle tube 82 from the grip 83 is a sid~ grip 85
clamped to the handle tube 82 by a wing nut assembly 86.
The side grip 85'may be used to assist in the guided move-
ment o~ ~he cultivator.
The housing 80 is provided with a skirt 88 which
extends outwardly and downwardly about the sides and the
rear of the housing 80. The skirt 88 is thus provided with
lower depending side shield portions 90 and a rear rake or
,spreading portion 92. The portion 92 is formed with notches
or teeth 93, as shown, and serves to smooth and spread the
cultivated dirt.
The housing 80 supports the electric drive motor
22 therein, the motor and gearing arrangement being identical
with that o~ the'embodiment described in connection with
_9_
,,, . ' , ~
.. . .
10~33875
Figs. 1-3. Thus, the motor 22 has mounted on its drive
shaft a spur gear 23 shown in outline form, which drives
the intermediate idler gear 25 and a driven spur gear 27,
all in the manner previously described. The gear 27 is
mounted on the worm shaft 30, with a worm gear 31 thereon.
The worm-driven spur gears are again essentially
identical to those previously described except that these
spur gears are mounted in a capsule or subassembly housing
95. One of the housings 95 is shown in elevation in Fig.
10 ,as having been withdrawn from the housing 80. The gear
housings 95 are split into respective upper and lower
sections 95a and 95b and capture therebetween the worm-
engaging spur gears 98. The gears 98 correspond to the
gears 33 and 36 previously described. For this purpose,
the worm-driven spur gears 98 may be formed of a plastic
material for engagement with the steel worm 31, and are
mounted on steel shafts 100. The upper end of each
shaft 100 is received within an upper collar bushing 102,
- which has its collar received on the inside surface of
the housing portion 95a to form a thruqt bearing with the
adjacent surface of the gear 98. Similarly, a lower collar
bushing 103, which may be identical to the bushing 102,
is received within the lower housing portion 9Sb, again
with the collar being positioned adjacent the inside surface
and adjacent the gear 98 to form a second thrust surface.
The shaft 100 extends through the bushing 103 to
the exterior of the housing for supporting and retaining a
soil agitator thereon indicated generally at 110. As in
~10--
.. . .
108387S
the above embodiments, a pair of identical soil agitators
110 are thus employed, mounted on a pair of output shafts
100 which are positioned in angled relation to each other
and to a vertical plane extending therebetween. The
S shafts 100 are preferably inclined outwaraly at an angle
of about 30 to such vertical plane and about 60 to each
other. The worm 31 and the gears 98 thus define worm gear
drive means which interconnect the shafts to the reduction
gearing 23, 25 and 27, proviaing for counter-rotational
movements of the outwardly angled shafts to each other.
The soil agitatorsllO are tined ground tillers
and one of these tillers is carried on the lower ends of
each of the shafts 100. The construction of the tillers
of thi~ embodiment, as seen in Figs. 11 and 12, include a
generally radially extending support portion 115 termi-
nating in a plurality of perlpherally arranged, outwaraly
angled tines 120. The tines 120 are proport oned to engage
the earth undeJlying the tiller. The agitators 110 are
preferably molded of a high strength plastic material such
as a nylon. Preferably, the arcuate spaces between the
adjacent tines is removed as indicated at 122, thus
defining individual generally radially extending legs
115a formed as an integral part of the supporting portion
115. The legs 115a are reinforced by radially extending
ribs 123 on the lower surfa.ces thereof. The center of
the support portion 115 defines a hub 125 which is pro-
portioned to be engaged over a flattened end of the
shaft 100.
1083875
The individual tines 120 are somewhat tapered 50
that they are broader at their tops than at their bottoms,
and are preferably square in cross-section throughout their
length and oriented so that an edge 130 is presentsd to the
soil, in the direction of rotation, in the manner described
in connection with the embodi~aents shown in Figs. 5-7. In
addition, the tines extend outwardly and downwardly at an
angle of about 60 to the plane of the support portion 115
and about 30 to their axes of rotation. The tines pass
adjacent a vertical plane therebetween, as represented by
the parting line 130 in Fig. 10.
At their closest points, the adjacent tines 120
are substantially vertical to the ground and parallel to
each other, and are spaced from each other a distance "X" as
shown in Fig. 10. The distance "X" is lesc~ than the
arcuate spacing betw~en the adjacent tines on one of the
agitators and is also less than the radius of the tines
130 from the shaft 100. A narrow colurnn or band of earth
is not directly intercepted by the cultivators, but this
narrow column of earth is not self-supporting and is
therefore effective cultivated.
The soil agitators 110 thus provide for soil
agitation in non-parallel planes and create a stirring or
mixing of the underlying soil. The primary cutting and
mixing work is achieved by the downwardly angled tines 120
which present their sloping edges 130 to the soil.
.
-12-
1~83875
In use, a cultivator is placed in a garden in
which the soil is to be cultivated. When the switch 84
is activated, the motor turns the individual agitators
in counter-rotation fashion so that at their closest point
defined by the dimension "X" in Fig. 10, the agitators
are turning in such a direction as to tend to propel the
unit forwardly along the ground. The fact that the shafts
lO0 are set at only a small angle to the ground, and the
agitators themselves are thus inclined at a correspondingly
small angle to the ground, reduces the tendency for the
cultivator to run on top of the grour.d along the surface
at high speed, as is common with cultivators as described
under the "background" section of this application.
Additionally, once the agitators begin to work the yround
underlying the cuLtivator, the cultivator remains easy to
handie and control since the tines 120 extend into the
ground and the force tending to pull the cultivator forwardly
is substantially counteracted by a reverse thrust which is
imparted by the tines at the outer portion of their orbits.
Thus, for all practical purposes, when the cultivator is
being used, the unit is in substantial equilibrium, and
the entire cultivator remains relatively stable on the
ground and is easy to control. Each ayitator is in itself
substantially balanced when the earth beneath the cultivator
is being worked, so that it is not necessary to hold the
cultivator perfectly ievel with respect to the ground in
order to obtain this counter-balancing and easy-to-control
condition. The shields 90 define a nominal distance to
~ -13-
~083875
which the cultivator works and prevents stones or other
debris from being propelled outwardly. The teeth 93 act
as a rake and tend to redistribute and spread the 50il
at the rear of the cultivator.
The cultivatin~ action is particularly effective
and i5 controlled by allowing the unit to move forward, or
even moving the same backwardR or sideways. The shield
portions 90 tend to confine the dirt and prevent the qame
and entrained rocks and the like from being propelled
o~twardly while the rear shield portion 90 tends to
redistribute the cultivated earth.
While the forms of apparatus herein described
constitute preferred embodiments of this invention, it
i9 to be understood that the invention is not. limited to
thes~ precise forms of apparatus, and that changes may
be made therein without departing from the scope of the
invention.
~hat ;~ c~
~13a-
.
