JPH0718259Y2 - Cutting blade rotating body of brush cutter - Google Patents

Description

[Detailed Description of the Invention] [Industrial field of application] The present invention relates to a cutting blade rotating body of a portable brush cutter used for mowing or the like.

[Prior Art] As a brush cutter of this type, as shown in FIG. 4, a screw portion b is provided at a tip end portion of a rotary shaft a, and a cup is formed by a nut c fastened to the male screw portion b. It is known that a plate-shaped cutting blade e is fastened and fixed to the tip end portion of the rotary shaft a through a blade-shaped cutting blade mounting bracket d.

Further, when the brush cutter is exclusively used for mowing, there are not a few examples in which a cutting blade rotating body having a flexible linear blade made of synthetic resin or the like is attached to the tip end portion of the rotary shaft. For example, as shown in Japanese Patent Laid-Open No. 63-32421, the cutting blade rotating body includes an upper case, a lower case that is openably and closably attached to a lower portion of the upper case, and vertically moves in both cases. A bobbin that is accommodated as much as possible and has a flexible linear blade made of synthetic resin wound around the outer periphery thereof, and a coil spring that presses the lower surface of the bobbin against the bottom surface of the lower case are provided. Then, when the number of flexible linear blades decreases, when the engagement state between the bobbin and the lower case is temporarily released during operation, the flexible linear blades come out of the case by a substantially constant size due to centrifugal force. It comes to wear.

[Problems to be solved by the invention] However, in the conventional cutting blade rotating body, a nut member is fixedly attached to the axial center part in the case, and the nut member is a rotary shaft from which the cutting blade mounting bracket and the nut are removed. It is adapted to be attached to the tip end portion of the rotary shaft by being screwed into the male thread portion. Moreover, the diameter and pitch of the male thread of the rotary shaft often differ depending on the manufacturer of the brush cutter, and if you want to use the rotary blade of the brush cutter with the blade rotor, use the male screw It is necessary to selectively purchase and install a specific cutting blade rotating body in which a nut member that fits the part is embedded. That is, such a structure has a completely different mounting structure from a plate-shaped cutting blade, and therefore, if a cutting blade rotating body of another manufacturer is purchased by mistake, it may not be mounted on the rotary shaft.

An object of the present invention is to eliminate such a problem by allowing the cutting blade rotating body to be fixed to the rotary shaft in the same manner as the plate-shaped cutting blade.

[Means for Solving the Problems] The present invention adopts the following configuration in order to achieve such an object.

That is, the cutting blade rotating body of the brush cutter according to the present invention comprises an upper case detachably fixed to a tip end portion of a rotary shaft, a lower case openably and closably attached to a lower end side of the upper case, and A bobbin that is housed in a case so as to be movable up and down, and around which a flexible wire blade is wound, and a bobbin that is disposed in the axial center portion of both cases and that pushes down the bobbin and the lower case and the lower case. In a cutting blade rotating body of a brush cutter that engages a concave and convex engaging portion formed on the bottom surface of the upper case, at least the axial center portion of the upper wall of the upper case is formed flat, and Make the upper end side of the coil spring larger than the lower end side to form a space in the axial center part,
The cutting blade mounting metal fitting and the nut arranged in the space are attached to the male screw portion of the rotary shaft penetrating the upper wall, and the upper case is attached to the rotary shaft.

[Operation] With such a configuration, this cutting blade rotating body can be attached to the tip end portion of the rotary shaft in the same manner as when the plate-shaped cutting blade is attached to the rotary shaft. . That is, on the external thread of the rotating shaft that penetrates the upper wall of the upper case,
Attach the cutting blade mounting bracket and nut that are also used when fixing the plate blade from the inside of the upper case, and tighten the upper wall with the cutting blade mounting bracket to fix the upper case to the rotating shaft. You can Then, while attaching the lower case to the upper case, the bobbins and the like are housed in both cases, and the bobbin and the lower case are engaged with each other by the coil spring, so that they rotate together with the rotating shaft. Will be done.
In addition, the space where the cutting blade fitting is arranged is formed by flattening the axial center portion of the upper wall of the upper case and by making the upper end side of the coil spring larger in diameter than the lower end side. It is possible to eliminate the fixed nut member from the cutting blade rotating body without increasing the diameter of the rotating body itself. The cutting blade mounting bracket and nut for fastening the plate-shaped cutting blade to the rotary shaft are originally mounted on the rotary shaft side as one part of the brush cutter, and are therefore sold by the manufacturer. Even if the screw pitch of the rotary shaft is different for each, no problem occurs.

[Embodiment] An embodiment of the present invention will be described below with reference to FIGS. 1 to 3.

As shown in FIG. 1, the cutting blade rotating body 1 is detachably fixed to the tip of the rotary shaft 2 of the brush cutter, and is detachably attached to the upper case 3 and the lower end of the upper case 3. A lower case 4 fitted with a lid, a bobbin 5 housed in both cases 3 and 4 so as to be vertically movable, and a flexible linear blade 6 wound around the outer circumference of the bobbin 5,
The coil spring 7 is provided.

The rotary shaft 2 has a base end portion connected to a prime mover (not shown), and a male screw portion 2a is formed at a tip portion thereof, and a cutting blade mounting bracket is provided by a nut 8 fastened to the male screw portion 2a. 9 is detachably attached. The cutting blade mounting bracket 9
It is cup-shaped and has a shaft through hole 9b in the axial center portion of the bottom wall 9a.

As shown in FIGS. 1 and 2, the upper case 3 has a cap-like shape, and the shaft center portion of the upper wall 3a is formed flat, and the shaft through hole 3b is provided in the center thereof. is there. The inner surface 3h of the upper wall 3a is formed with a plurality of concave engaging portions 3c at equal angular intervals in the circumferential direction, and the outer surface of the peripheral wall 3d has locking claws.
Formed 3e.

As shown in FIGS. 1 and 3, the lower case 4 is dish-shaped, and is similar to the concave engaging portion 3c of the upper case 3 in the peripheral portion of the insertion hole 4b provided in the central portion of the bottom surface 4a. Multiple concave engagement parts
Have 4c. Further, on the outer edge portion, a latching collar 4d for latching the latching claw 3e of the upper case 3 and a peripheral wall 3d of the upper case 3 are provided.
Protrusions 4e that are fitted and inserted into locking holes 3g formed in the lower surface 3f are provided respectively.

The bobbin 5 has a space in its axial center portion, and has a plurality of convex engagements on an upper surface 5a facing the inner surface 3h of the upper wall 3a of the upper case 3 and a lower surface 5b facing the bottom surface 4a of the lower case 4. The parts 5c are provided so as to project. The convex engaging portion 5c on the upper surface 5a side and the convex engaging portion 5c on the lower surface 5b side are arranged at equiangular positions on the circumference. In addition, a protrusion 5d is formed on the bottom of the bobbin 5,
The projecting portion 5d penetrates the insertion hole 4b of the lower case 4 and projects from the lower surface 4f of the lower case 4.

The flexible linear blade 6 is made of a synthetic resin, the base end of which is fixed to the outer circumference of the bobbin 5, and the distal end of the flexible linear blade 6 extends outward from a lead-out hole 3k provided in the peripheral wall 3d of the upper case 3. I am allowed.

The coil spring 7 is for pushing down the bobbin 5 to engage the convex engaging portion 5c of the lower surface 5b thereof with the concave engaging portion 4c of the lower case 4, and the lower end 7a is elastically contacted with the bottom portion of the bobbin 5. The upper end 7b is elastically contacted with the upper wall 3a of the upper case 3. The diameter of the coil spring 7 on the upper end 7b side is made larger than the diameter on the lower end 7a side to form a space 10 in the axial center portion thereof, and the cutting blade attachment fitting 9 is arranged in the space 10.
That is, the coil spring 7 of this embodiment has a tapered shape.

Thus, during normal use, the cutting blade rotating body 1 has a convex engaging portion 5c on the lower surface 5b side of the bobbin 5 and a concave engaging portion of the lower case 4.
Since 4c and 4c are engaged with each other by the coil spring 7, the flexible linear blade 6 is not extended to the outside due to centrifugal force during operation. On the other hand, when the number of the flexible linear blades 6 is reduced, the user temporarily presses the protruding portion 5d of the bobbin 5 against the ground to make the convex engaging portion 5c of the bobbin 5 concave to the concave engaging portion of the lower case 4. When separated from 4C, the concave engaging portion 5c on the upper surface 5a of the upper case 3
Engages with the concave engaging portion 3c. Here, since the concave engagement portion 4c of the lower case 4 and the concave engagement portion 3c of the upper case 3 are displaced in the circumferential direction, the bobbin 5 is momentarily moved by a dimension corresponding to the displacement. As it becomes idle, the flexible linear blade 6
Will be fed out by the centrifugal force. When the projecting portion 5d is released from the ground, the elastic engaging force of the coil spring 7 separates the convex engaging portion 5c of the upper surface 5a of the bobbin 5 from the concave engaging portion 3c of the upper case 3 and the convex engaging portion 5c of the lower surface 5b. Re-engages with the concave engaging portion 4c of the lower case 4. Also at that time, the bobbin 5 momentarily becomes idle, and the flexible linear blade is moved by a dimension corresponding to the displacement between the concave engaging portion 3c of the upper case 3 and the concave engaging portion 4c of the lower case 4. 6 will be paid out by the centrifugal force.

According to this structure, the male screw portion 2a of the rotary shaft 2 which penetrates the shaft through hole 3b of the upper case 3 from above is attached to the upper case 3
When the cutting blade mounting bracket 9 and the nut 8 are mounted from below, the nut 8 is tightened, and the upper wall 3a of the upper case 3 is tightened by the cutting blade mounting bracket 9 and the mounting plate 11. 3 can be securely fixed to the rotary shaft 2. Next, the bobbin 5 and the coil spring 7 are placed inside the upper case 3.
If the lower case 4 is attached to the lid while accommodating the like, these will rotate together with the rotary shaft 2. When a plate-shaped cutting blade is attached, it is preferable to remove the cutting blade rotating body 1 in the reverse order of this procedure and tighten the plate-shaped cutting blade between the cutting blade mounting bracket 9 and the mounting plate 11.

Therefore, in the case of such a configuration, the cutting blade rotating body 1 is moved to the rotary shaft 2 by using the cutting blade mounting bracket 9 and the nut 8 used when attaching the plate-shaped cutting blade to the rotary shaft 2. Can be installed on. That is, according to such a cutting blade rotary member 1, even if the pitch of the external thread 2a of the rotary shaft 2 varies depending on the manufacturer of the brush cutter, the cutting blade rotary member 1 can be easily attached to each brush cutter. Can be used.

In addition, the cutting blade rotating body 1 flattens the axial center portion of the upper wall 3a of the upper case 3 and the upper end of the coil spring 7.
Since the diameter of the 7b side is larger than that of the lower end 7a side and the space 10 for arranging the cutting blade mounting bracket 9 is formed inside the 7b side, the upper case 3 and the lower case 4, etc. may be increased in size. In addition, the nut member can be eliminated from the cutting blade rotating body 1.

Furthermore, if a general coil spring having the same diameter on the upper end side and the lower end side is used, the bobbin 5 is likely to tilt when a pressing force acts on one side of the protruding portion 5d, and the convex engaging portion on the upper surface 5a thereof is used. 5c and the convex engaging portion 5c of the lower surface 5b may simultaneously engage with the upper case 3 and the lower case 4, respectively, and the flexible linear blade 6 may not be extended.
If the diameter is tapered so that it gradually increases toward the upper end side, it is possible to effectively avoid such a problem.

The coil spring may have a stepped shape in which the diameter on the upper end side is larger than the diameter on the lower end side.

[Advantages of the Invention] Since the present invention has the above-described configuration, the cutting blade rotating body is attached to the rotary shaft in the same manner as when the plate-shaped cutting blade is attached to the rotary shaft of the brush cutter. You can As a result, it is possible to eliminate the complexity of wearing or not wearing it, depending on the machine and model.
It can be used simply and reliably by attaching it to the rotating shaft. Further, according to the present invention, the number of parts of the cutting blade rotating body can be reduced, and the cutting blade rotating body is not increased in size.

[Brief description of drawings]

1 to 3 show an embodiment of the present invention. FIG. 1 is a partial sectional view showing the inside of a cutting blade rotating body, FIG. 2 is a lower surface of an upper case, and FIG. It is a top view of a lower case. Fourth
The figure is an exploded front view showing a conventional example. 1 ... Cutting blade rotor, 2 ... Rotating shaft 2a ... Male thread part, 3 ... Upper case 3a ... Upper wall, 4 ... Lower case 4a ... Bottom surface, 4c ... Recessed engaging part 5 ... Bobbin , 5b ...... Lower surface 5c ...... Convex engagement part, 6 ... Flexible linear blade 7 ...... Coil spring 7a ...... Lower end, 7b ...... Upper 8 ...... Nut, 9 ...... Cut blade mounting bracket 10 ...... Space

Claims (1)

[Scope of utility model registration request] 1. An upper case detachably fixed to a tip portion of a rotary shaft, a lower case openably and closably attached to a lower end side of the upper case, and vertically movably housed in the both cases. Along with a bobbin having a flexible linear blade wound around it, the bobbin is arranged at the axial center of both cases, and the bobbin is pushed down to form a concave and convex engaging portion formed on the lower surface and the bottom surface of the lower case. In a cutting blade rotating body of a brush cutter, which comprises a coil spring to be engaged, at least an axial center portion of an upper wall of the upper case is formed flat, and an upper end side of the coil spring is positioned lower than a lower end side. A space is formed in the shaft center portion with a large diameter, and the cutting blade mounting metal fitting and the nut arranged in the space are attached to the male screw portion of the rotary shaft that penetrates the upper wall to attach the upper case to the rotary shaft. Of a brush cutter characterized by being attached to Blade rotor.