JP2532137Y2 - String head structure of brush cutter - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a string head structure of a brush cutter used for mowing and the like, and more specifically, automatically cuts a string-shaped cutting blade from a string head when the string-shaped cutting blade is broken at a tip end side. The present invention relates to a string head structure of a brush cutter that can be pulled out from a brush cutter.

[0002]

2. Description of the Related Art In a string-shaped blade-type brush cutter, with use,
The string-shaped cutting blade may be torn at the distal end side, in which case it is necessary to return the string-shaped cutting blade to an appropriate length. JP 61
JP-A-88813 and JP-A-63-32421 use a centrifugal force applied to a string-shaped cutting blade to automatically remove the string-shaped cutting blade from the string head when the string-shaped cutting blade is torn. Disclosed is a structure of a cord-shaped blade-type brush cutter to be pulled out. In this structure, the string-shaped cutting blade is drawn out through an outlet hole in the wall of the string head, and is not equipped with a means for preventing the string-shaped cutting blade from being pulled into the string head.

[0003]

SUMMARY OF THE INVENTION In a string-type blade-type brush cutter, during operation, the string-shaped blade is fully extended by centrifugal force against its own elastic force. In a conventional string-type cutting blade-type brush cutter that can automatically pull out the string-shaped cutting blade, when the string-shaped cutting blade is torn in the vicinity of the lead-out hole of the string head, the string-shaped cutting blade in the extended state is retracted. As a result, not only is it difficult to automatically adjust the length of the string-shaped cutting blade, but also it is difficult to automatically adjust the length of the string-shaped cutting blade from the string head. Need to be decomposed.

An object of the present invention is to provide a brush cutter having a function capable of automatically returning a drawn-out length of a string-shaped cutting blade to an appropriate length. The purpose of the present invention is to prevent the tip of the string-shaped cutting blade from entering the string head.

[0005]

The present invention will be described with reference to the drawings corresponding to the embodiments. The string head structure of the brush cutter (10) of the present invention has the following elements (a) to (e). (A) A cord-shaped cutting blade that is rotatable relative to the rotation shaft (26)
Reel (24) is wound (38) (b) the rotation axis (26) and rotates integrally with at least partially covers the inner wall portion of the radially outer reel (38) (34) (c) A string-shaped cutting blade provided on the inner wall part (34) outward in the radial direction
(24) Outer wall located radially outward from inner wall (34)
Part (62) and the inner lead-out part (88) at right angles to the radial direction.
It is provided on the outer wall part (62) unevenly and cuts radially outward.
An outer outlet portion (70) for leading the blade (24) to the rotating shaft (26).
On the other hand, it is integrated in the rotation direction and movable in the radial direction.
The reel (38) is locked in the rotation direction at the radial inner position.
While the string-shaped cutting blade (24) is being connected to the inner wall (34) by the outer wall (62).
Between the reels (3
While releasing the lock of 8), the inner wall portion (34) by the outer wall portion (62)
Radial moving part that releases the pinching force of the cord-shaped cutting blade (24) between
Lumber (60) (e) Radial shift during rotation with an appropriate length of cord-shaped cutting blade (24)
It is larger than the centrifugal force of the moving member (60) but smaller than the proper length.
Radial moving member rotating with a cut length of cord-shaped cutting blade (24)
The radial moving member (6
Urging member (84) that urges (0) radially inward

[0006]

[Action] When the string-shaped cutting blade (24) is at an appropriate length, the resistance of the string-shaped cutting blade (24) to rotation is large, and the rotation speed of the string head (20) is small. Therefore, the radial moving member (60)
The radial moving member (60) is pulled radially inward by the biasing member (84) and is at the radially inner position. As a result, the radial moving member (60) is
(38), the rotational force of the rotating shaft (26) is transmitted to the reel (38) via the radial moving member (60), and the radial moving member (60) and the reel (38) are rotated. ) Rotates integrally with the rotation shaft (26). Also, the outer wall of the radial moving member (60)
(62) approaches the inner wall portion (34), and the string-shaped cutting blade (24) is a stepped inner lead-out portion (88) and an outer lead-out portion (step) of the inner wall portion (34) and the outer wall portion (62). 70), is pulled out of the string head (20), and in the portion between the inner outlet portion (88) and the outer outlet portion (70), the outer wall portion (62) and the inner wall portion (34) Is pressed in the radial direction, and the displacement is restrained.

When the string-shaped cutting blade (24) is torn, the string-shaped cutting blade (24)
Is the inner wall portion between the inner outlet portion (88) and the outer outlet portion (70).
(34) and the outer wall (62), the string head (20)
You are prevented from being drawn inside. On the other hand, string-shaped cutting blade (24)
Due to the decrease in the length, the resistance of the string-shaped cutting blade (24) to the rotation of the string head (20) decreases, and the rotation speed of the string head (20) increases. Thereby, the centrifugal force applied to the string-shaped cutting blade (24) and the radial moving member (60) increases, and the radial moving member (60)
Moves radially outward against the biasing member (84), and assumes a radially outward position. As a result, the reel (38) is unlocked in the rotational direction by the radial moving member (60), and can be relatively rotated with respect to the rotating shaft (26) and the radial moving member (60), The outer wall of the radial moving member (60) (6
2) is separated from the inner wall portion (34), and the string-shaped cutting blade (24) is provided with an inner wall portion (34) and an outer wall portion (62) between the inner outlet portion (88) and the outer outlet portion (70). ) Is released. Thus, the reel (38) relatively rotates by the centrifugal force applied to the string-shaped cutting blade (24), and the string-shaped cutting blade (24) is pulled out of the string head (20) according to the centrifugal force.

When the cord-shaped cutting blade (24) is pulled out to a predetermined length, the resistance of the cord-shaped cutting blade (24) to the rotation of the cord head (20) increases, and the rotational speed of the cord head (20) is increased. Is reduced, the radial moving member (60) is again moved to the radial inner position by the biasing member (84), and the reel (38) is moved to the radial moving member (60).
And the cord-shaped cutting blade (24) has an inner wall portion (34) and an outer wall portion (34) at a portion between the inner outlet portion (88) and the outer outlet portion (70). 62) and the displacement is restrained.

[0009]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. FIG. 12 is a schematic overall view of the brush cutter 10. At the upper end of the pipe 12, a power unit 14 is attached, and a handle 16
Is fixed to a portion of the pipe 12 near the power unit 14 and protrudes upward. The gear case 18 is attached to a lower end portion of the pipe 12, and the rotary head 20 is connected to a drive shaft 22 protruding downward from the gear case 18, and rotates integrally with the drive shaft 22.
Two nylon cords 24 as cord-like cutting blades extend outward from diametrically opposite locations on the periphery of the rotary head 20.

FIGS. 1, 2 and 3 each show a rotary head.
FIG. 20 is a vertical sectional view, a bottom view, and a side view of 20. FIG.
FIG. 1 is an exploded perspective view of a rotary head 20 schematically showing a part of the rotary head 20 with some parts omitted. The mounting shaft 26 is screwed with the drive shaft 22 in the screw hole 28 so as to rotate integrally with the drive shaft 22. The upper case 30 has a circular upper wall portion 32 and a cylindrical wall portion 34 hanging down from a peripheral portion of the upper wall portion 32, and has a mounting shaft.
The mounting shaft 26 is fitted at the center until it comes into contact with the step portion 36 of 26, and rotates integrally with the mounting shaft 26 by fitting the mounting shaft 26 into a regular hexagonal cross section (FIG. 11).

FIGS. 4 and 5 are a vertical sectional view and a bottom view of the reel 38, respectively. 1, 4 and 5,
The reel 38 has an upper flange 40 and a lower flange 42 at upper and lower ends, respectively, and a plurality of notch grooves 44 are formed in the peripheral portion of the lower flange 42 at equal angular intervals in the circumferential direction. . The reel 38 is rotatably fitted to a boss having a circular cross section of the upper case 30 at a center in a circular hole. 2
The nylon cord 24 is wound around a reel 38,
It can be extended with the rotation of 38.

FIGS. 6 and 7 are a vertical sectional view of the lower case 46 and a plan view in which a half of one side is partially omitted. In FIGS. 1, 6 and 7, the circular base portion 48 has the lower flange 42 of the reel 38 mounted on the upper surface thereof so as to be relatively rotatable. The regular octagonal hole 50 penetrates the lower case 46 along the center line, the lower end of the mounting shaft 26 is inserted, and the lower case 46 is attached to the mounting shaft 26 by fitting a regular octagonal cross section. 26
And rotate together. The pair of arc-shaped upright wall portions 51 (FIGS. 6 and 7) extend along the peripheral edge of the lower case 46, and have radial guide portions 52 therebetween at positions directly opposite in the circumferential direction. The radial guide portion 52 includes an overhang portion 54 that horizontally projects outward in the radial direction, a pair of vertical guide surfaces 58 that face each other in parallel with the width of the overhang portion 54, and a slightly higher position than the overhang portion 54. Each of the vertical guide surfaces 58 has a horizontal groove 56 extending horizontally.

FIGS. 8, 9 and 10 show centrifugal bodies 60 respectively.
3 is a front view, a plan view, and a side view of FIG. 1 and FIGS.
In FIG. 10, a rectangular base 68 extends horizontally,
The lower case 46 is slidably mounted on the overhanging base 54.
The upright wall portion 62 stands upright from the outer side of the base portion 68. The step-shaped block portion 64 is formed on the upper surface side of the base portion 68 along the edge on the inner side of the base portion 68, and at the lower step portion, the lower surface of the circular base portion 48 of the lower case 46. , And is fitted in the notch groove 44 of the reel 38 at the upper step.
The width of the block portion 64 is the width of the notch groove 44 of the reel 38 (FIG. 5).
Is equal to The linear ridges 66 are formed on both sides of the base 68 and extend linearly between both ends of the base 68. The centrifugal body 60 is fitted to the radial guide portion 52 of the lower case 46 such that the linear protrusion 66 is slidably fitted into the linear groove 56 of the radial guide portion 52 of the lower case 46. The rotary head 20 is guided by the radial direction guide 52 in the radial direction. The outlet 70 is formed at the upper edge of the upright wall 62,
72 is formed on the vertical surface of the lower step portion of the block portion 64 so as to project radially inward of the rotary head 20.

1 to 3, a knob 74 having a circular cross section is shown.
The boss 76 having a circular cross section is fitted into a hole in the center of the lower surface of the lower case 46 so as to be rotatable relative to the lower case 46. The bolt 78 has a head portion 80 having a square cross section fitted into the center of the knob 74, and a shaft portion 82 projecting from the knob 74 and screwing to the lower end portion of the mounting shaft 26. By the rotation of the knob 74, the bolt 78 rotates integrally with the knob 74, and the shaft 82 is screwed into the mounting shaft 26, whereby the knob 74 is moved to the lower case.
The 46 and the upper case 30 are fastened to the step 36 of the mounting shaft 26, and the mounting shaft 26, the lower case 46, and the centrifugal body 60 rotate integrally with the mounting shaft 26. The extension coil spring 84 is hung on the hook screw 86 screwed to the lower case 46 and the loop 72 of the block portion 64 at the radially inner and outer ends of the rotary head 20 to radially move the centrifugal body 60 in the radial direction. Energize inward. The nylon cord 24 wound around the reel 38 is drawn out of the rotary head 20 through the outlet 88 of the cylindrical wall 34 of the upper case 30 and the outlet 70 of the upright wall 62 of the centrifugal body 60. . The outlets 88 and 70 have step heights that are lower and higher, respectively, and the nylon cord 24 is bent and extends between the cylindrical wall portion 34 and the upright wall portion 62. The centrifugal body 60 has an upright wall 62 at a radially inner position.
Is brought closer to the cylindrical wall portion 34 of the upper case 30, the bent portion of the nylon cord 24 is pressed against the cylindrical wall portion 34, and the displacement of the nylon cord 24 is restrained.

The operation of the embodiment will be described. When the nylon cord 24 has an appropriate length, the resistance of the nylon cord 24 to rotation is large, and the rotation speed of the rotary head 20 is small. Therefore, the centrifugal force applied to the centrifugal body 60 is small, and the centrifugal body 60 is radially guided by the extension coil spring 84 while being guided in the radial direction by the radial guide portion 52 of the lower case 46, and is radially inward. In position. As a result, the centrifugal body 60 has the block portion 64 fitted into the notch groove 44 of the lower flange 42 of the reel 38 from the outside in the radial direction, and is in a state of being mutually locked with the reel 38 in the rotational direction. The rotational force of the shaft 26 is transmitted to the reel 38 via the lower case 46 and the centrifugal body 60, and the centrifugal body 60 and the reel 38 rotate integrally with the mounting shaft 26, the upper case 30, and the lower case 46. The upright wall portion 62 of the centrifugal body 60 is formed by the cylindrical wall portion 34 of the upper case 30.
, The nylon cord 24 is drawn out of the rotary head 20 through the outlets 88 and 70 of the cylindrical wall portion 34 and the upstanding wall portion 62 at the steps, and the portion between the outlets 88 and 70 The cylindrical wall portion 34 of the upper case 30 and the upright wall portion 62 of the centrifugal body 60
, And the displacement in the radial direction is restrained.

When the nylon cord 24 is torn, the nylon cord 24 is held inside the rotary head 20 by the pressure between the cylindrical wall 34 of the upper case 30 and the upright wall 62 of the centrifugal body 60 between the outlets 88 and 70. You are prevented from being drawn into. On the other hand, due to the decrease in the length of the nylon cord 24, the resistance of the nylon cord 24
20 rotation speed increases. With this, nylon cord
The centrifugal force applied to 24 and the centrifugal body 60 increases, and the centrifugal body 60
Radially outward (FIGS. 1 and 2)
(In the direction of arrow A) of FIG.
As a result, the reel 38 is unlocked in the rotational direction by the centrifugal body 60, and the upper case 30, the lower case 46, and the centrifugal body
In addition to being rotatable relative to 60, the upright wall portion 62 of the centrifugal body 60 is separated from the cylindrical wall portion 34 of the upper case 30, and the nylon cord 24 stands upright with the cylindrical wall portion 34 between the outlets 88 and 70. The pinching by the wall portion 62 is released. Thus, the reel 38 relatively rotates by the centrifugal force applied to the nylon cord 24, and the nylon cord 24
Pulled out of the.

When the nylon cord 24 is pulled out to a predetermined length, the nylon cord with respect to the rotation of the rotary head 20 is rotated.
24, the rotational speed of the rotary head 20 is reduced, and the centrifugal body 60 is again moved to the radially inward position by the tension coil spring 84, and another notch groove of the reel 38 in the block portion 64 is formed. The reel 38 is engaged with the reel 38 in the rotating direction, and the reel 38 is again rotated integrally with the mounting shaft 26, the upper case 30, the lower case 46, and the like. Further, the nylon cord 24 is pinched by the cylindrical wall portion 34 of the upper case 30 and the upright wall portion 62 of the centrifugal body 60 in a portion between the outlets 88 and 70.

In the embodiment shown, the outlets 70, 88 are
As shown in FIG. 3 and FIG. 3, the rotary head 20 is stepped in the axial direction, but may be stepped in the circumferential direction of the rotary head 20. In the illustrated embodiment, the outlets 70 and 88 are open on the upper and lower sides, respectively, but may be circular holes. In the illustrated embodiment, a nylon cord 24 is used as the string-shaped cutting blade, but the string-shaped cutting blade may be made of a material other than nylon.

[0019]

According to the present invention, the string-shaped cutting blade wound on the reel is pulled out of the string head through the stepped inner and outer lead-out portions of the inner wall and the outer wall. The wall is formed on the radial moving member,
The radial moving member moves in the radial direction according to the centrifugal force and the urging force of the urging member, and is locked to the reel at the radially inner position, rotates integrally with the reel, and passes through the outer wall portion. The string-shaped cutting blade is pressed against the inner wall. Therefore, even when the string-shaped cutting blade is torn in the vicinity of the string head, the string-shaped cutting blade is prevented from being pulled into the string head, and when a predetermined centrifugal force is applied to the string-shaped cutting blade, the radiation occurs. The direction moving member moves to the radially outer position, the rotation of the reel and the pinching force of the string-shaped cutting blade by the inner wall and the outer wall are released, and the string-shaped cutting blade is automatically pulled out to an appropriate length. be able to.

[Brief description of the drawings]

FIG. 1 is a vertical sectional view of a rotary head.

FIG. 2 is a bottom view of the rotary head.

FIG. 3 is a side view of the rotary head.

FIG. 4 is a vertical sectional view of a reel.

FIG. 5 is a bottom view of the reel.

FIG. 6 is a vertical sectional view of a lower case.

FIG. 7 is a plan view in which a half part on one side of a lower case is partially omitted.

FIG. 8 is a front view of a centrifuge.

FIG. 9 is a plan view of a centrifuge.

FIG. 10 is a side view of the centrifuge.

FIG. 11 is an exploded perspective view of the rotary head schematically showing a part with parts omitted.

FIG. 12 is a schematic overall view of a brush cutter.

[Explanation of symbols]

 Reference Signs List 10 brush cutter 20 rotating head (string head) 24 nylon cord (string-shaped cutting blade) 26 mounting shaft (rotating shaft) 34 cylindrical wall portion (inner wall portion) 38 reel 60 centrifugal body (radially moving member) 62 upright wall portion (Outer wall portion) 70 Outlet (outer outlet) 84 Tension coil spring (biasing member) 88 Outlet (inner outlet)

Claims (1)

(57) [Scope of request for utility model registration] 1. A reel (38) which is rotatable relative to a rotating shaft (26) and around which a string-shaped cutting blade (24) is wound, and (b ) is integral with the rotating shaft (26). The reel (38)
Inner wall part (3
4), (c) provided on the inner wall portion (34),
An inner lead-out portion (88) for leading out the cord-shaped cutting blade (24); (d) an outer portion located radially outward from the inner wall portion (34);
Inwardly extending in the direction perpendicular to the side wall (62) and the radial direction
Radiation direction provided on the outer wall part (62) at a level different from the part (88)
An outer lead-out part (70) for leading the cord-shaped cutting blade (24) outward.
Integrated in the direction of rotation with respect to the rotation axis (26) and radiated
It is movable in the direction, and the rotation direction is in the radial inner position
While holding the reel (38), the cord-shaped cutting blade (24)
The outer side wall (62) pinches and releases the inner side wall (34).
At the outer position in the shooting direction, the reel (38) is locked in the rotation direction.
While releasing, the inner wall portion (34) by the outer wall portion (62)
Radial movement to release the pinching force of the cord-shaped cutting blade (24) during
Member (60), and (e) the release during rotation with the cord-shaped cutting blade (24) of the appropriate length.
It is larger than the centrifugal force of the shooting direction moving member (60), but it is
The above-mentioned rotating with the cord-shaped cutting blade (24) of the length torn off
A biasing member (84) for biasing the radial moving member (60) inward in the radial direction with a biasing force smaller than the centrifugal force of the radial moving member (60). Payment machine string head structure.