Note: Descriptions are shown in the official language in which they were submitted.
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- S P E C I F I C A T I O N
TITLE OF TPlE INVENTION
- Hand-held ~lachine
BACKGROUND OF THE INVENTION AND RELATED ART STATEMENT
This invention relates to an improvement in hand-held
machines such as cleavers which are driven by a small engine.
Generally a hand-held machine such as a cleaver
comprises an operational means like a cutter blade which is
rotatably provided at an end of a drive shaft pipe which
connects the operational means with a driving mechanism
such as an engine to rotate the means at high speed.
Since the length of the drive shaft pipe of -the
aforementioned hand-held machines is generally determined
to allow the users to work in a comfortable posture, the
length between the driving mechanism and means tends to
become long. They inconveniently require extensive space
during transportation and storage, and present problems in
working efficiency depending on the location or topography
of the land.
In order to solve such problems, there has been
proposed a hand-held machine wherein a drive shaft pipe
which is telescopically constructed internally houses a
shaft of the driving mechanism side with a joint of a
special shape and another shaft of the operational means
side which can receive the joint of the special shape.
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However, the proposed machine is not completely free of
problems as it has inferior sectional strength on the drive
shaft, and rotational force cannot be transmitted smoothly
due to the play on the joint.
SUMMARY OF THE INVENTION
Accordingly this invention aims to provide a hand-
held machine having an operational means which is attached
rotatably at an end of a drive shaft pipe, and which is
connected to a driving mechanism via a drive shaft for
rotation. The drive shaft pipe comprises a drive shaft pipe
of smaller diameter on the side of the operational means
and another drive shaft pipe of slightly larger diameter on
the side of the driving mechanism to which said smaller
diameter pipe is inserted while the drive shaft comprises
a shaft of circular section on the side of the driving
mechanism and another shaft pipe on the side of operational
means to which said circular section shaft is inserted. At
least one one-way clutch is provided at an end of the shaft
pipe on the side of the operational means to be engaged
with said circular section shaft. A fixing means is
attached on the larger diameter drive shaft pipe for fixedly
retaining the smaller diameter drive shaft pipe in the axial
direction thereof so as to prevent the sectional strength
from deteriorating as well as to enhance smooth transmission
of revolutional force.
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In this invention hand-held machine, the rotational force
of a driving mechanism such as an engine is transmitted to the
operational means via a drive shaft with a circular section, a
one-way clutch and a drive shaft pipe on the side of the
operational means. A bearing member is provided inside the
drive shaft pipe in a manner to be flexibly retained in order
to axially support the shaft so that the displacement of the
shaft may be prevented even at the time of rotation~
The drive shaft with the circular section on the side of
the driving mechanism may have a smaller diameter at a portion
thereof. If the diameter is designed too small to be
connected to the other shaft with the one-way clutch, the
transmission of the rotational force may be suspended if
necessary. Moreover, if a switching means is mounted on the
fixing means, and is operated by a switch provided on the
smaller diameter drive shaft pipe in the longitudinal
direction, risks which otherwise may be produced when a user
grips the shaft at a position too close to the operational
means could be avoided in advance.
In accordance with one aspect of the invention there is
provided a hand-held machine comprising: a drive shaft pipe
means which is extendable in the lengthwise direction thereof;
an operational means rotatably attached at an end of said
drive shaft pipe means; a driving mechanism coupled to the
another end of said drive shaft pipe means; drive shaft means
rotatably mounted in said drive shaft pipe means, said drive
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shaft means being extendable in the lengthwise direction
thereof and being coupled at one end to said operational means
and at another end to said driving mechanism; said drive shaft
pipe means comprising a first pipe section of given diameter
on the side of said operational means, and a second pipe
section of a different diameter than said first pipe section
on the side of said driving mechanism, the smaller diameter of
said first and second pipe sections being slidably inserted in
the other of said pipe sections for extending or contracting
the drive shaft pipe means in the lengthwise direction
thereof; said drive shaft means comprising a first drive shaft
member of substantially circular outer periphery provided on
the side of said driving mechanism, and a second pipe-like
drive shaft member provided on the side of said operational
means, said first drive shaft member being engaged with and
inserted in said second drive shaft member for extending and
contracting said drive shaft means in the lengthwise direction
thereof; at least one one-way clutch coupled to said second
pipe-like drive shaft member at an end portion thereof which
is engaged with said first drive shaft member, said at least
one one-way clutch being movable along said first drive shaft
on the driving mechanism side and operatively coupling said
drive shaft member together to transmit rotary motion from
said driving mechanism to said operational means via said
drive shaft members; means for disengaging said driving
mechanism from said operational means responsive to the length
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of said drive shaft type means becoming shorter than a
predetermined length, said disengaging means being operatively
coupled to at least one of said one-way clutch and said
driving mechanism; and fixing means provided on said drive
shaft pipe means where said first and second drive shaft pipe
sections are engaged with each other, to fixedly support the
smaller diameter drive shaft pipe section at an axial position
relative to the larger diameter drive shaft pipe section.
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 is a perspective view showing a cleaver as a
preferred embodiment of the hand-held machine according to
this invention.
Fig. 2 is a sectional view of essential elements of
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the cleaver shown in Fig. 1.
Figs. 3 and 4 are partially omitted sectional views
showing another embodiment of the cleaver as a preferred
embodiment of the present invention.
Fig. 5 is a perspective view of the essential
elements of the cleaver shown in Fig. 4.
Figs. 6 and 7 are sectional views of the other
embodiment corresponding to the ones in Fig. 5.
THE PREFERRED EMBODIMENTS OF THE INVENTION
The preferred embodiments of the hand-held machine
or the cleaver in accordance with the present invention is
now described in more detail referring to attached drawings.
In Figs. 1 and 2 the cleaver according to this
invention comprises a nylon cord cutter 12 which is rotatably
mounted on an end of a drive shaft pipe 10 as a means of
cleaving. The cleaver cuts and cleaves weeds and grass by
the cutter 12 which is driven to rotate at high speed by
the output from an engine 14 which is transmitted via a
drive shaft 16.
The drive shaft pipe 10 comprises a drive shaft pipe
10a having a smaller diameter on the side of the nylon code
cutter 12, and another drive shaft pipe 10b on the side of
the engine having a slightly larger diameter so as to
receive the first pipe 10a and move axially in a telescopic
mode.
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The drive shaft 16 comprises a first shaft 16a on the
side of the engine 14 having a circular section, a second
pipe shaft 16b which sheathes the shaft 16a on the side of
the means, and a one-way clutch 18 provided at one end of
the shaft 16b which is actuated by normal rotation of the
shaft 16a. Although a solid shaft is used as the shaft 16a
of the circular section in this embodiment, a pipe
may be used for minimizing the weight of the device.
An end of- the drive shaft pipe lOb is attached
with a sleeve-like cover member 20 and a fixing means 22 is
provided on the cover member 20. By manipulation of said
fixing means 22 with a knob, the drive shaft pipe lOa may be
retained fixedly at a predetermined axial position. Suitable
stop means should be provided at respective ends of drive
shaft pipes lOa and lOb.
A bearing member 24 of the shaft 16a is provided
movably in the drive shaft pipe lOb, and is attached with
a coil spring 26 to the main body of driving mechanism
including the engine 14 via the drive shaft pipe lQb (refer
to Fig. 2).
The cleaver thus structured is operated in practice
as follows: the drive shaft pipe lOa and the shaft 16a of
circular section are slided along the drive shaft pipe lOb
and the shaft 16b for a suitable distance by manipulating
the fixing means 22 to have a desired length, and the length
of the drive shaft pipe 10 is fixed with the fixing means 22.
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The rotational force of the engine 14 is transmitted
constantly as it is to the nylon code cutter 12 via the
shaft 16a, one-way clutch 18 and the shaft 16b. As the
rotational force is constantly transmitted to nylon code
cutter 12 intact, there will be no chattering or deterio-
ration in sectional strength. Further, when the cleaver
is used at a relatively flat place having a small gradient,
lengths of the drive shaft pipe 10 and the drive shaft 16
may be determined arbitrarily simply by manipulating the
fixing means 22.
Due to the effect of the coil spring 26 used for
flexibly retaining the bearing 24 in the axial direction,
the shaft 16a is conveniently supported axially so that
no displacement of the shaft 16 would be produced at the
time of rotation.
Fig. 3 shows another cleaver embodying this invention
hand-held machine wherein a steel cutter blade 28 receiving
substantially no load at the time of rotation is used as a
cleaving means in place of the nylon code cutter on which
load is constantly applied. Further, a one-way clutch 18a
which is actuated with the normal rotation of the shaft 16a
and another one-way clutch 18b which is actuated with the
reverse rotation of the shaft 16a are provided adjacent to
each other at the end of the shaft on the side of the means
16b, and the shaft 16a is reduced in diameter at a pre-
determined position.
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This embodiment not only achieves an effect similar
to the first embodiment but also conveniently prevents
vibration or noises with the effect of the pair of one-way
clutches which may otherwise be caused by the inertia of
the steel cutter blade 28 when the revolution rate of the
engine is once reduced and then increased. Even if the
length of the shaft is adjusted erroneously too short, the
transmission of the rotational power is broken instantaneously
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at the point/when the shaft 16a is aligned with the one-way
clutch 18a where the diameter is narrowed to thereby further
secure the safety of the users.
If the bearing of the one-way clutch 18b is made of
such elastic materials as rubber, the impact felt on the
device when the steel cutter contacts a stone or the like
will not cause a bite by the one-way clutch into the shaft.
This also contributes to reduction of manufacture cost.
Figs. 4 and 5 show another cleaver embodying the
hand-held machine according to this invention wherein an
engine switch 32 is provided on the fixing means 22, and
a lever 34 for the switch 32 is attached in a manner to
extend over a flat handle section 36 on the surface of the
shaft lOa longitudinally.
In addition to the effect similar to the first
embodiment, this embodiment can avoid various types of
dangers which might otherwise be inflicted on the users.
For instance, if the length of the engine shaft is excessively
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sharte~ed,. or the shaft is twisted from the housing means
peripherally to disengage the lever 34 from the section 36,
the engine 14 will be suspended instantly. Similar effect
can be attained even if the lever 34 of the switch 32 is
structured to extend over a slit 40 opened on the peripheral
surface of the drive shaft pipe lOa via a hole 38 (refer to
Fig. 6) or the switch is replaced by a magnetic switch 42
having a magnet 44 as an operational means thereof positioned
inside of the pipe lOa (refer to Fig. 7).
As stated above, as this invention hand-held machine
can adjust the length thereof arbitrarily, it can enhance
workability as well as minimize the space necessary for
transportation or storage. Moreover, the rotational force
of the driving mechanism can securely be transmitted to the
operational means via the shaft, one-way clutch and opera-
tional side shaft, the problems encountered in the prior
art such as the reduction of sectional area can be avoided
to further secure effective operation. It can effectively
prevent vibration or noises and can secure the safety of
users.
Although description is made in the foregoing
statement on preferred embodiments of this invention hand-
held machine, it should be understood that the present .
invention is in no way limited to these~~.embodiments, and
~.ario~s ch~nges and modifications in design can be made
within the scope of this invention without departing from
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the spirit of the present invention.
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