Earth working – With drive means for tool or cleaner – Guided by walking attendant
Reexamination Certificate
2003-01-09
2004-11-30
Novosad, Christopher J. (Department: 3671)
Earth working
With drive means for tool or cleaner
Guided by walking attendant
C172S123000
Reexamination Certificate
active
06823947
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to an improvement in walk-behind cultivators.
BACKGROUND OF THE INVENTION
Common walk-behind cultivators operate by rotation of tillage tines provided on rotor shafts, being propelled with the tillage tines. Those cultivators are called front-tine cultivators. In recent years, however, front-rotary cultivators, that is, walk-behind cultivators with tillage tines arranged forward of the bodies provided with driving wheels have been developed.
Having the tillage tines at the front of the bodies, the front-rotary cultivators facilitate cultivation in headlands, allowing operators to look forward during operation, providing good workability, and thus attracting attention (See, e.g., Japanese Patent No. 3015821 and Japanese Utility Model Laid-Open Publication No. SHO-56-97903).
The words “headlands” mean areas left unplowed by a cultivator cultivating a rectangular-shaped field, moving back and forth in parallel with one side thereof, for example, because it temporarily stops working at the opposite ends of the field for turning or the like.
A cultivator in Japanese Patent No. 3015821 is called a down-cut cultivator with tillage tines rotated from the upper front of a traveling direction toward the ground and is mainly used to break up soil.
A cultivator in Japanese Utility Model Laid-Open Publication No. SHO-56-97903 is called an up-cut cultivator with tillage tines rotated from the upper rear of a traveling direction toward the ground and is mainly used to weed a field.
As an example of such front-rotary cultivators, the cultivator of Japanese Patent No. 3015821 will be generally described with reference to
FIG. 16
hereof.
A front-rotary cultivator
200
shown in
FIG. 16
is a walk-behind cultivator with a transmission case
203
provided below a body
202
to which an engine
201
is mounted, the transmission case
203
being integrally molded with a rear mission case
204
and a front rotary case
205
, a pair of left and right driving wheels
207
,
207
mounted on an axle
206
protruded from a rear portion of the mission case
204
, a rotary countershaft
208
provided in a front portion of the mission case
204
, a plurality of tillage tines
210
mounted on a rotor shaft
209
protruded from a front portion of the rotary case
205
, and a chain
213
running in the rotary case
205
between a driving sprocket
211
of the rotary countershaft
208
and a driven sprocket
212
of the rotor shaft
209
.
The engine
201
is a horizontal engine with an output shaft
214
protruded laterally. A belt
218
runs between a driving pulley
215
mounted on the output shaft
214
and a driven pulley
217
mounted on an input shaft
216
protruded from the side of the mission case
204
to transmit the power of the engine
201
to the transmission. The power of the engine
201
can thus drive the pair of left and right driving wheels
207
,
207
via the axle
206
and drive the tillage tines
210
via the rotary countershaft
208
, chain
213
and rotor shaft
209
.
The tillage tines
210
of the front-rotary cultivator
200
are arranged in four rows across the width of the body
202
(across the two sides of the figure sheet). All the tillage tines
210
rotate with the rotor shaft
209
in one direction for cultivation. Reference numeral
219
denotes a tension roller as a main clutch and
220
a handle bar.
Cultivation with the tillage tines
210
can cause a so-called dashing phenomenon (or jumping phenomenon) in which the cultivation reaction force causes the tillage tines
210
to bound upward. The dashing phenomenon caused reduces the linearity in travel of the cultivator
200
, resulting in insufficient cultivation performance and poor finish of cultivation. This tendency is more noticeable especially as the cultivator
200
is lighter in weight.
The above conventional art arranges the engine
201
between the rear axle
206
and the front rotor shaft
209
to shift the center of gravity of the cultivator
200
forward, thereby to apply part of the weight of the engine
201
to the tillage tines
210
. As a result, the degree of digging of the tillage tines
210
into the ground Gr
21
can be somewhat increased and the occurrence of the dashing phenomenon can be somewhat prevented.
Only with such a structure, however, there is a limit to the increase in degree of digging of the tillage tines
210
and the prevention of the dashing phenomenon. To solve the problem, it seems possible to arrange the engine
201
or a heavy load such as a counterweight in front of or above the tillage tines
210
to increase the distribution of weight to the tillage tines
210
. The center of gravity of the cultivator
200
is, however, too much offset forward, making the handle bar
220
heavier. Especially in the operation of pushing down the handle bar
220
to lift the tillage tines
210
to turn the cultivator
200
, the pushing-down force is increased, reducing the operability. Only changing the center of gravity of the cultivator
200
forward thus inexpediently increases the workload of the operator.
Thus desired is a front-rotary cultivator with tillage tines arranged at the front of the body equipped with driving wheels, being able to prevent the occurrence of the dashing phenomenon, increase cultivation performance and also reduce the workload of the operator.
SUMMARY OF THE INVENTION
According to the present invention, there is provided a walk-behind cultivator, which comprises: a body; an engine provided on the body; left and right driving wheels provided to the body and driven by the engine; and a plurality of tillage tines provided at the front of the body and driven by the engine, the tillage tines comprising: a plurality of forward-rotating tines arranged in the center of the width of the body; and a plurality of reverse-rotating tines arranged outward of the forward-rotating tines in the transverse direction of the body, the reverse-rotating tines being arranged in the same phase in a side view.
Arranging the forward-rotating tines of the tillage tines in the center of the body width and arranging the reverse-rotating tines transversely outward of the forward-rotating tines allow the forward-rotating tines to (forwardly) rotate from the upper front of the traveling direction toward the ground and the reverse-rotating tines to (reversely) rotate from the upper rear of the traveling direction toward the ground.
The direction of the cultivation reaction forces against the forward-rotating tines is forward and upward of the traveling direction of the walk-behind cultivator, that is, opposite to the rotation direction of the forward-rotating tines. The direction of the cultivation reaction forces against the reverse-rotating tines is rearward of the traveling direction of the walk-behind cultivator, that is, opposite to the rotation direction of the reverse-rotating tines. The cultivation reaction forces against the forward-rotating tines and the cultivation reaction forces against the reverse-rotating tines act in opposite directions.
When all the tillage tines are forward-rotating tines, the cultivation reaction force is larger, making it difficult to prevent the occurrence of a dashing phenomenon due to the cultivation reaction force. In this invention, the cultivation reaction force arising from cultivation with the forward-rotating tines can be cancelled to some extent by the cultivation reaction force arising from cultivation with the reverse-rotating tines. As a result, the occurrence of a dashing phenomenon can be prevented.
With the walk-behind cultivator being propelled, the forward-rotating tines in the center of the body width can rotate forward to dig into the ground for cultivation, digging out the cultivated soil rearward of the cultivator body.
Arranging the reverse-rotating tines in the same phase in a side view allows the reverse-rotating tines arranged transversely outward of the forward-rotating tines to rotate reversely, with the walk-behind cultivator being propelled, to simultaneously dig into the ground,
Kanbara Fumiyoshi
Kobayashi Hideaki
Nagaoka Masatoshi
Ohta Yoshitaka
Adams & Wilks
Honda Giken Kogyo Kabushiki Kaisha
Novosad Christopher J.
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