JP4745166B2 - Brush cutter - Google Patents

Description

  The present invention relates to a brush cutter suitable for weed cutting.

  As a conventional brush cutter, the one shown in Patent Document 1 has been proposed. In this brush cutter, a rotary shaft is supported downwardly via a housing with respect to a tip portion of an operating rod held by an operator, and a circular saw is rotated by the rotary shaft. The circular saw is almost entirely covered with an upper cover and a lower cover, and recessed portions are provided on both the left and right sides of the upper cover and the lower cover so that a cut material such as weeds can enter.

On the other hand, what is shown in patent document 2 is proposed as a conventional brush cutter. The brush cutter is configured such that a center portion of a pair of upper and lower rotating disks is fitted and fixed to a rotating shaft supported by a housing, and a centrifugal blade is interposed between the rotating disks so as to be tiltable by a connecting pin. A protective cover is provided to cover the rotating disk from above and below.
Japanese Utility Model Publication No. 3-85820 JP-A 51-55086

  In the former brush cutter, the circular saw was actively rotated, so when an obstacle such as a small stone touched the tip of the circular saw, the sharp blade of the circular saw violently hit the obstacle. There was a problem that obstacles were scattered and the safety was lost due to collision.

  On the other hand, in the latter brush cutter, since the centrifugal blade is tiltably connected to the rotating disk, when an empty can or a wire hits the centrifugal blade, the impact can be reduced. However, since the centrifugal blade is connected to the rotating disk, the centrifugal blade is actively swiveled, and therefore, there is a problem that the scattering of the obstacle cannot be sufficiently prevented.

  The present invention was made paying attention to the problems existing in the prior art, and its purpose is to reduce the collision of the obstacle with the blade part of the rotary blade body during the mowing operation, The present invention is to provide a brush cutter that can rapidly reduce the rotational speed of the rotary blade body even if it collides, suppress the scattering of obstacles, and improve safety.

  In order to solve the above problems, the invention according to claim 1 is characterized in that a housing is attached to the tip of the operating rod, the rotating shaft projects downward from the housing, and a rotating disk is attached to the lower end of the rotating shaft. A rotating blade body having a donut plate shape with respect to the upper surface near the outer periphery of the rotating disk is rotatably supported by sliding frictional resistance due to the rotating motion of the rotating disk, and a plurality of convex portions are provided on the outer peripheral edge of the rotating disk, The convex portion is provided with an inclined portion that becomes higher with respect to the rotational direction of the rotating disk, and a radius from the rotational center of the rotating disk to the tip of the convex portion is formed on the rotating blade body from the rotational center. The gist is that it is set to be larger than the radius to the blade edge of the blade portion.

  According to a second aspect of the present invention, in the first aspect, a spacer portion is locally provided on the inner peripheral edge side of the rotary blade body so as to be positioned on the lower side, and the outer peripheral edge side of the rotary blade body is a rotary disk. The gist of the invention is that it is configured so as not to contact the upper surface.

  According to a third aspect of the present invention, in the first or second aspect, the outer peripheral edge of the rotary blade body is provided with a plurality of convex portions having inclined portions that become higher toward the subsequent side in the rotation direction of the rotary blade body. The gist is that a saw-toothed blade portion is formed on the inclined portion of each convex portion.

  According to the present invention, the tip of the convex portion having the inclined portion provided on the outer peripheral edge of the rotating disk is located outside the blade edge of the blade part of the rotating blade with respect to the radial direction of the rotating disk. During the weed mowing operation, the obstacle is pushed away by the inclined portion before the obstacle collides with the blade portion of the rotary blade body by the turning motion of the inclined portion of the convex portion. For this reason, possibility that an obstacle will collide with the blade part of a rotary blade will become low, scattering of an obstacle will be reduced, and safety will improve.

  Since the rotary blade is mounted in a free state in which the rotary blade is simply in contact with the upper surface of the rotary disk, when the rotary disk is rotated, the rotary blade is rotated by the contact frictional resistance between them. For this reason, even if an obstacle comes into contact with the blade part of the rotary blade, the rotation of the rotary disk is continued, but the rotational speed of the rotary blade is rapidly reduced, so that the kinetic energy applied to the obstacle is reduced. , Obstacles are prevented from being scattered and safety is improved.

Hereinafter, an embodiment embodying the present invention will be described with reference to FIGS.
As shown in FIG. 1, a covered cylindrical housing 12 is connected downward to the distal end portion of the operation rod 11 of the brush cutter so as to open the lower end. A rotating shaft 13 is rotatably supported in a predetermined position in the housing 12 by a pair of upper and lower radial ball bearings 14 and 15. The rotary shaft 13 is rotated by a drive shaft 16 penetrating the operation rod 11, a drive bevel gear 17A provided at the tip thereof, and a driven bevel gear 17B provided on the rotary shaft 13 so as to mesh with the drive shaft. The drive shaft 16 is connected to an engine (not shown) mounted on the base end portion of the operation rod 11 via a clutch box (not shown).

  As shown in FIG. 1, a disc-shaped rotating disk 21 is attached to the spline portion 13 a of the rotating shaft 13. A flange portion 13 b is formed integrally with the intermediate portion of the rotating shaft 13. Between the lower surface of the flange portion 13b and the upper surface of the rotating disk 21, an attachment plate 22 fitted to the spline portion 13a so as to be integrally rotatable is interposed. As shown in FIG. 1, a bulging portion 22 a is integrally formed on the lower surface of the mounting plate 22, and the bulging portion 22 a is fitted into a mounting hole 21 a formed at the center of the rotating disk 21. A mounting plate 23 fitted to the spline portion 13 a of the rotating shaft 13 is in contact with the lower surface of the rotating disk 21. The mounting plate 23 is pressed against the lower surface of the rotating disk 21 by a bolt 24 screwed into a screw hole formed in the lower end surface of the spline portion 13a, and rotates between the upper mounting plate 22 and the lower mounting plate 23. The disc 21 is clamped and fixed.

  As shown in FIGS. 2 and 3, the outer peripheral edge of the disk main body 21b of the rotating disk 21 is formed with a plurality of concave portions 21c and convex portions 21d at equal pitches at a plurality of locations (in this embodiment, five locations). . The disk main body 21b is formed with a number of circular holes 21e for weight reduction.

  As shown in FIG. 3, an inclined portion 21f is formed on the leading side of the convex portion 21d with respect to the rotation direction P of the rotating disk 21 so that the distance from the rotation center O of the rotating disk 21 increases toward the trailing side. Yes.

  As shown in FIG. 1, a rotating blade body 31 is mounted on the upper surface near the outer periphery of the rotating disk 21. As shown in FIG. 4, the rotary blade body 31 includes a donut plate-shaped ring portion 31 a and a large number (for example, 30 to 36 blades) 31 b of a saw-tooth shape formed on the outer peripheral edge of the ring portion 31 a. As shown in FIG. 1, the spacer portion 31c is formed by bending the upper and lower layers integrally with the inner periphery of the ring portion 31a. As shown in FIG. 1, a portion outside the spacer portion 31 c of the rotary blade body 31 is not in contact with the upper surface of the rotary disk 21.

  A holding ring 32 for holding the rotary blade 31 so as to be relatively rotatable at a predetermined position is fixed to the upper surface of the rotary disk 21 by screws 33 and nuts 34. That is, the disk main body 21b of the rotating disk 21 is provided with a plurality of holes 21g penetrating the screw 33 from below as shown in FIG. 3, and formed on the inner peripheral edge of the holding ring 32 as shown in FIG. The retaining ring 32 is fixed to the upper surface of the rotating disk 21 as shown in FIG. 1 by passing the screws 33 through the holes 32b of the plurality of brackets 32a and screwing the nuts 34 into the screws 33. The inner peripheral side of the rotary blade 31 is accommodated in the accommodation groove 35 so as to be relatively rotatable by the accommodation groove 35 formed between the upper surface of the rotating disk 21 and the lower surface of the holding ring 32.

  As shown in FIGS. 1 and 2, the radius R1 from the rotation center O of the rotary disk 21 to the tip of the convex portion 21d (the apex of the inclined portion 21f) is the cutting edge of the blade portion 31b of the rotary blade body 31. It is formed larger than the same radius R2.

Next, the operation of the brush cutter configured as described above will be described.
When the rotating shaft 13 is rotated, the mounting plates 22 and 23 and the rotating disk 21 are rotated via the spline portion 13a, whereby the free rotating blade body 31 is rotated by the sliding frictional resistance with the rotating disk 21. The In this state, when the rotating disk 21 approaches, for example, a weed cutting start portion, the weed enters the recess 21c of the rotating disk 21, so that the weed is cut by the blade portion 31b of the rotating blade body 31.

Next, effects of the brush cutter configured as described above will be listed together with the configuration.
(1) In the embodiment, the radius R1 from the rotation center O of the rotary disk 21 to the tip of the convex portion 21d (the apex of the inclined portion 21f) is the same radius of the blade edge of the blade portion 31b of the rotary blade body 31. It is formed larger than R2. For this reason, before the blade part 31b of the rotary blade 31 comes into contact with an obstacle such as a pebbles or a wire during the mowing operation, the obstacle is pushed away by the turning movement of the inclined part 21f of the convex part 21d. Damage to the blade portion 31b due to contact between the blade portion 31b and the blade portion 31b is prevented, scattering of obstacles is suppressed, and safety can be improved.

  (2) In the above-described embodiment, the rotary blade 31 is supported in a free state where the rotary blade 31 is simply in contact with the upper surface near the outer periphery of the disk main body 21b of the rotary disk 21. For this reason, when an obstacle is caught in the rotary blade body 31 during the mowing operation and an external impact of a predetermined value or more acts, the rotary blade body 31 slips on the upper surface of the rotary disk 21 and the rotary blade body 31 rotates. The speed is drastically reduced, scattering of obstacles can be suppressed, and safety can be improved. Moreover, it can also suppress that the blade part 31b of the rotary blade 31 is damaged.

  (3) In the above embodiment, since the spacer portion 31c is provided on the inner peripheral edge of the rotary blade body 31, the contact area between the disk main body 21b and the rotary blade body 31 can be reduced, and therefore the sliding friction resistance is small. Thus, when an obstacle comes into contact with the rotary blade 31, it is possible to promote a rapid decrease in the rotation speed of the rotary blade 31.

  (4) In the above embodiment, since the rotary disk 21 is attached to the lower end of the rotary shaft 13 and the rotary blade body 31 is mounted on the rotary disk 21, there is no need to perform special processing on the housing 12. The brush cutter housing 12 and the rotary shaft 13 can be used as they are.

In addition, the said embodiment can also be changed and embodied as follows.
As shown in FIG. 5, a large number of convex portions 31e having inclined portions 31d that become higher toward the trailing side with respect to the rotation direction P of the rotary blade body 31 with respect to the outer peripheral edge of the ring portion 31a of the rotary blade body 31 (for example, 10-25) may be provided, and a saw blade-shaped blade portion 31f may be formed in series on the inclined portion 31d of each convex portion 31e. The blade portion 31f is sharpened like a band saw, for example. The inclination angle α with respect to the rotation direction P of the inclined portion 31d is set in a range of 2 degrees to 15 degrees, for example. In this other example, since the recessed part 31g is formed between each convex part 31e, each blade part 31f can be made to collide with a weed, and a weed can be cut appropriately. It was also found through experiments that soft weeds can be properly cut.

  As shown in FIG. 6, with respect to the outer peripheral edge of the ring portion 31 a of the rotary blade body 31, an inclined portion 31 d (inclination angle α with respect to the rotation direction P is higher with respect to the rotation direction P of the rotary blade body 31 toward the subsequent side). For example, it is set in the range of 50 degrees to 80 degrees.) A plurality of convex portions 31e are provided at many locations, and the inclined portion 31d of each convex portion 31e is substantially V-shaped (including a semi-elliptical shape) in plan view. The blade portion 31h may be formed. The back surface of the blade portion 31h is substantially V-shaped (see the broken line). In this other example, the weed capturing effect by the V-shaped blade portion 31h is improved as compared with the semi-arc shaped blade portion in plan view, and the weed cutting operation can be appropriately performed.

-You may provide the number of the convex parts 21d of the said rotation disc 21 in 2 places, 3 places, 4 places, and 6 places-9 places.
The spacer 31c may be separated from the rotary blade body 31 and formed separately.

  -You may make it join the cutting blade formed separately in the blade part 31b of the said rotary blade body 31 shown in FIG. You may make it join the sawtooth-shaped blade part 31f formed separately in the inclined part 31d shown in FIG. You may make it join the blade part 31h formed separately in the inclined part 31d shown in FIG.

The technical ideas other than the claims grasped from the embodiment will be described below.
(1) The brush cutter according to any one of claims 1 to 3, wherein a retaining ring for retaining an inner peripheral edge of the rotating blade body is detachably attached to the rotating disk. .

In this brush cutter, it is possible to easily replace the rotary blade body by removing the holding ring.
(2) In any one of claims 1 to 3, a plurality of protrusions are formed on the outer peripheral edge of the rotary blade body, and the inclined portion on the leading side with respect to the rotation direction of the rotary blade body of each protrusion. Is a brush cutter having a V-shaped blade portion in plan view.

  (3) It is a rotary blade used in a brush cutter, and the outer peripheral edge of the ring portion of the rotary blade is provided with a plurality of convex portions having inclined portions that become higher toward the subsequent side in the rotation direction, A rotary blade used in a brush cutter, wherein sawtooth-shaped blade portions are formed in series on the inclined portion of each convex portion.

  (4) It is a rotary blade used for a brush cutter, and convex portions having inclined portions that become higher toward the trailing side in the rotation direction are formed at a plurality of locations on the outer peripheral edge of the rotary blade body. A rotary blade used in a brush cutter is characterized in that a substantially V-shaped blade portion is formed on the inclined portion in plan view.

The principal part longitudinal cross-sectional view which actualized the brush cutter of this invention. The top view of the principal part of a brush cutter. The exploded perspective view of a rotation disc, a mounting plate, and a bolt. The disassembled perspective view of a housing, a mounting plate, a rotary blade body, and a holding ring. The perspective view which shows another embodiment of a rotary blade body. The perspective view which shows another embodiment of a rotary blade body.

Explanation of symbols

  O ... center of rotation, P ... direction of rotation, R1 ... radius, R2 ... radius, 12 ... housing, 13 ... rotating shaft, 21 ... rotating disk, 21d, 31e ... convex, 21f, 31d ... inclined portion, 31 ... rotating blade Body, 31b, 31f ... blade part, 31c ... spacer part.

Claims (3)

A rotary blade body in which a housing is attached to the tip of the operation rod, the rotary shaft projects downward from the housing, a rotary disk is attached to the lower end of the rotary shaft, and a donut plate shape is formed on the upper surface near the outer periphery of the rotary disk Is supported by a sliding frictional resistance due to the rotational motion of the rotating disk, and a plurality of convex portions are provided on the outer peripheral edge of the rotating disk, and the convex portions are inclined portions that become higher toward the trailing side in the rotational direction of the rotating disk. And the radius from the rotation center of the rotating disk to the tip of the convex portion is set to be larger than the radius from the rotation center to the blade edge of the blade portion formed on the rotary blade body. And brush cutter. In Claim 1, the spacer part is locally provided in the inner peripheral edge side of the rotary blade body so as to be positioned on the lower side, and the outer peripheral edge side of the rotary blade body is configured not to contact the upper surface of the rotary disk. A brush cutter characterized by In Claim 1 or 2, the outer peripheral edge of the rotary blade body is provided with a plurality of convex portions having inclined portions that become higher toward the trailing side in the rotational direction of the rotary blade body, and the inclined portion of each convex portion has A brush cutter, wherein a saw blade portion is formed.

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