Cutlery – Cutting tools – Plural cooperating blades
Reexamination Certificate
1998-06-11
2001-07-24
Payer, Hwei-Siu (Department: 3724)
Cutlery
Cutting tools
Plural cooperating blades
C030S216000, C030S223000
Reexamination Certificate
active
06263579
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a hand-held power working machine, and in particular to a power transmission device for a working member and to the clipper blades (saw blades), which are designed to be disposed at the front portion of a power working machine such as a hedge trimmer.
2. The Prior Art
A hand-held power working machine, such as a hedge trimmer, is generally constituted by a prime mover case housing a prime mover, such as an internal combustion engine, a mount base portion supporting a transmission case housing a power transmission device, such as gears, to be actuated by the prime mover, a working portion comprising clipper blades to be actuated via the aforementioned power transmission device by the prime mover, and a handling portion attached to the prime mover case, the transmission case or the mount base portion. The handling portion is constituted, for the convenience of manipulation thereof, by a front handle portion and a rear handle portion. For the purpose of protecting an operator's hand gripping the front handle portion from accidents, a hand protector is attached to a portion in front of the front handle. The working portion comprising the clipper blades, etc. is disposed below the hand protector.
According to another type of conventional hand-held power working machine provided with a working portion comprising clipper blades, a prime mover, such as an internal combustion engine, is attached to one end portion of a long manipulating rod, and the working portion (comprising the clipper blades) is mounted, together with a transmission case, on the other end portion of the long manipulating rod. The rotating power of the prime mover is transmitted via a transmission shaft passed through the manipulating rod to the transmission case. Then, through a transmission device housed in the transmission case, the rotating power is further transmitted to the clipper blades of the working portion, thereby allowing the clipper blades to be driven reciprocatively so as to perform the cutting of lawns and other vegetation. (See, for example, Japanese Utility Model Publication H/6-905.)
FIG. 4
shows a cross-sectional view of a transmission case
50
and a working portion
60
comprising clipper blades
61
and
62
of the aforementioned hand-held power working machine.
FIG. 5
shows the clipper blades
61
and
62
, and a reciprocating movement-guiding arm
65
(
66
) for guiding the reciprocating movement of the clipper blades
61
and
62
. As shown in
FIG. 4
, a main drive shaft
51
, to be driven by the power of the prime mover (not shown), is rotatably supported in the transmission case
50
. A driving rotor
52
provided with a pair of upper and lower eccentric circular cams
52
a
and
52
b
differing in phase from each other is drivably attached to the main shaft
51
.
The working portion
60
is constituted by a pair of clipper blades
61
and
62
which are superimposed one upon the other. The clipper blades
61
and
62
are respectively provided not only with a plurality of cutting edges
61
c
and
62
c
formed at predetermined intervals on both sides of each blade (see FIG.
5
), but also with a plurality of guiding slots
61
a
and
62
a
which are formed at predetermined intervals along the center line and in the longitudinal direction of each of the clipper blades
61
and
62
.
On the upper surface of the upper clipper blade
61
, there is disposed an upper blade-supporting plate
64
which is supported or cantilevered by the transmission case
50
by means of securing bolts
68
and locknuts
69
. There is also disposed, on the bottom surface of the lower clipper blade
62
, a lower blade-supporting plate
67
, which is secured by a plurality of guiding screws
70
which are introduced from the bottom side of the lower blade-supporting plate
67
into the guiding slots
61
a
and
62
a
so as to allow the tip end portions thereof to protrude from the upper blade-supporting plate
64
and to be clamped by locknuts
71
. The pair of the upper and lower clipper blades
61
and
62
are disposed in such a manner that, even in the aforementioned secured condition, they are capable of reciprocatively moving in the longitudinal direction thereof as guided by the combination of the guiding screws
70
within the guiding slots
61
a
and
62
a
. Guide collars
71
a
of appropriate height are positioned around the screws
70
to space the upper and lower plates
64
and
67
apart by the necessary distance.
As shown in
FIG. 5
, the reciprocating movement-guiding arms
65
and
66
are not only provided at the proximal end portion thereof with elliptical openings
65
a
and
66
a
, respectively, the minor axis of which is almost the same as that of the eccentric circular cams
52
a
and
52
b
, but are also provided at the distal end portion thereof with coupling members
65
b
and
66
b
each having a circular head.
The proximal end portions of the clipper blades
61
and
62
facing the aforementioned reciprocating movement-guiding arms
65
and
66
are provided with cutout engaging portions
61
b
and
62
b
, each having a shape conforming with the shape of the circular coupling members
65
b
and
66
b
. Namely, the cutout engaging portions
61
b
and
62
b
are adapted to be engaged with the coupling members
65
b
and
66
b
, while the elliptical openings
65
a
and
66
a
of the reciprocating movement-guiding arms
65
and
66
are adapted to be engaged with the eccentric circular cams
52
a
and
52
b.
The transmission case
50
, constructed as explained above, and the working portion
60
, comprising the clipper blades
61
and
62
, are interconnected in such a manner that when the main shaft
51
is rotated, thereby to rotate the driving rotor
52
, the pair of upper and lower eccentric circular cams
52
a
and
52
b
(differing in phase from each other) are caused to rotate, thereby causing the clipper blades
61
and
62
to reciprocate, guided by the reciprocating movement-guiding arms
65
and
66
, in opposite directions to each other with a phase shift of 180 degrees, thus making it possible to carry out the cutting of vegetation and the like.
According to the conventional hand-held power working machine, the reciprocating movement-guiding arms
65
and
66
are designed to be separated from the clipper blades
61
and
62
through disengagement of the circular coupling members
65
b
and
66
b
from the cutout engaging portions
61
b
and
62
b
. Accordingly, when it is desired to replace or sharpen the clipper blades
61
and
62
, the clipper blades
61
and
62
can be separated from the reciprocating movement-guiding arms
65
and
66
by first unfastening and removing the locknuts
71
from the guiding male screws
70
and then dismounting the lower blade-supporting plate
67
from the upper blade-supporting plate
64
.
However, since the reciprocating movement-guiding arms
65
and
66
are provided at the proximal end portions thereof with the elliptical openings
65
a
and
66
a
, respectively, to allow them to be reciprocatively driven by the driving rotor
52
(through the pair of upper and lower eccentric circular cams
52
a
and
52
b
), the reciprocating movement-guiding arms
65
and
66
are required to have a wide width in the direction perpendicular to the direction of reciprocation. Accordingly, a raw material plate of relatively large width is required for the manufacture of the reciprocating movement-guiding arms
65
and
66
. At the same time, to ensure a sufficient structural strength in the region where the elliptical openings
65
a
and
66
a
are formed, the material plate must be of relatively large thickness or, alternatively, the ring portion surrounding the elliptical openings
65
a
and
66
a
must be enlarged in width. This design also involves a troublesome working during manufacture.
Further, since the reciprocating movement-guiding arms
65
and
66
are integrated with the clipper blades
61
and
62
through the engagement between the circular hea
Baker & Botts L.L.P.
Kioritz & Corporation
Payer Hwei-Siu
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