JP7178255B2 - Rotary power transmission device for brush cutter and brush cutter - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present disclosure relates to a rotary force transmission device for a brush cutter configured to transmit a rotary force generated by a rotary force generation device to a cutting blade via a transmission shaft member, and to a brush cutter.

In the brush cutter, a prime mover such as a two-cycle engine is connected to the cutting blade via a clutch or a transmission shaft member, and the driving force generated by the prime mover is transmitted to the cutting blade via the clutch or the transmission shaft member. Some are configured to rotate the cutting blades. The transmission shaft member is formed in an elongated rod shape and housed in the operating lever. An operator of the bush cutter cuts weeds and the like by operating a handle attached to an operating rod. In general, a lawn mower uses an internal combustion engine that vibrates a lot, so the large vibration of the prime mover is directly transmitted to the handle via the transmission shaft member and the operating rod. The vibrations transmitted to the handle may lead to deterioration of operability of the brush cutter and increase of fatigue of the operator.

It is known that brush cutters generate vibrations in addition to the vibrations of the prime mover. After the motor is started, the clutch is engaged at about 4,000 rpm, but vibration occurs due to the shock when the clutch is engaged. After the clutch is engaged, the rotation speed is increased to about 8,000 rpm, which is the normal rotation speed. During the increase, torque fluctuations caused by uneven rotation of the prime mover cause large-amplitude vibrations in the transmission shaft member. In addition, immediately after the cutting blade comes into contact with shrubs or the like while the brush cutter is in use and the cutting blade momentarily stops or is in an extremely decelerated state, the rotation of the cutting blade is instantly restored and the power transmission shaft member Vibration also occurs due to over-rotation of the . These vibrations appear as torsional vibration caused by torsion of the transmission shaft and bending vibration caused by deflection of the transmission shaft.

Some bush cutters are configured to transmit a driving force (rotational force) via a coil spring (see Patent Document 1, for example). In Patent Document 1, a coil spring is arranged between a motor-side transmission shaft portion and a cutting-blade-side transmission shaft portion, and the rotation of the motor-side transmission shaft portion is transmitted to the cutting-blade-side transmission shaft portion via the coil spring. A lawn mower is disclosed that is configured to.

More specifically, in the bush cutter disclosed in Patent Document 1, each of the motor-side transmission shaft member and the cutting-blade-side transmission shaft member has a tip surface abutting portion that receives the tip surface of the wire rod of the coil spring. there is When the motor-side transmission shaft member rotates, the tip surface abutting portion of the motor-side transmission shaft member contacts one tip surface of the wire rod of the coil spring, causing the coil spring to rotate in conjunction with the rotation of the motor-side transmission shaft member. . When the coil spring rotates, the other tip surface of the wire rod of the coil spring comes into contact with the tip surface abutting portion of the cutting-blade-side transmission shaft member, rotating the cutting-blade-side transmission shaft member in conjunction with the rotation of the coil spring. The twisting and bending of the coil spring that transmits rotation absorbs the above-described torsional vibration and bending vibration.

JP 2010-17175 A

In the bush cutter disclosed in Patent Document 1, each of the motor-side transmission shaft member, the cutting-blade-side transmission shaft member, and the coil spring is not configured to restrain other members. In other words, the coil spring has a natural length and is axially movable between the motor-side transmission shaft member and the cutting-blade-side transmission shaft member. Further, when the motor-side transmission shaft member is not rotating, there is a clearance between the tip surface abutment portions of the motor-side transmission shaft member and the cutting-blade-side transmission shaft member and the tip surface of the wire rod of the coil spring. is provided. Therefore, at the start of rotation transmission by the coil spring, a loud noise ( contact sound) was generated. A bush cutter may be activated multiple times in a day, and if a loud noise is generated each time the mower is activated, the operator may feel uncomfortable.

In view of the circumstances described above, an object of at least one embodiment of the present invention is to provide a rotary force of a brush cutter capable of suppressing abnormal noise caused by contact of the coil spring with other parts at the start of rotation transmission by the coil spring. An object of the present invention is to provide a transmission device.

(1) A rotary force transmission device for a bush cutter according to at least one embodiment of the present invention,
A rotary force transmission device for a bush cutter configured to transmit a rotary force generated by a rotary force generator to a cutting blade via a coil spring,
a first shaft member including a first side seat contact portion configured to be able to contact one side seat of the coil spring;
a second shaft member including a second side seat contact portion configured to contact the other side seat of the coil spring;
It is disposed between the first shaft member and the second shaft member, and connects the first shaft member and the second shaft member via both end surfaces of the wire rod of the coil spring. the coil spring configured to transmit rotational force between;
The coil spring is sandwiched between the first side seat contact portion and the second side seat contact portion to retain the coil spring in an axially and/or torsionally compressed state. and a compressed state holding device.

According to the configuration (1) above, the rotary force transmission device for a bush cutter has a coil spring sandwiched between the first side seat contact portion and the second side seat contact portion. A compression retainer configured to retain axially and/or torsionally compressed condition is provided. Therefore, in the rotary force transmission device of the bush cutter, the compression state holding device causes one side seat of the coil spring to abut against the first side seat abutting portion and the other side seat of the coil spring to contact the first side seat. 2 is in contact with the side seat contact portion. According to the above configuration, the tip surface of the wire rod of the coil spring is brought into contact with the first tip surface contact portion or the second tip surface contact portion in a state in which frictional resistance is generated between the contacting members. can be done. In a state where frictional resistance is generated between the contacting members, the first shaft member, the second shaft member, and the coil spring are restrained by other members compared to the case where the frictional resistance is not generated. Since the vibration of these members is suppressed, it is possible to suppress (contact noise) generated when the tip surface of the wire of the coil spring contacts the first tip surface contact portion or the second tip surface contact portion. can be done.

Further, according to the configuration (1) above, in the rotary force transmission device for a bush cutter, the coil spring is in contact with the first shaft member or the second shaft member when rotation transmission by the coil spring is started. , the coil spring can be slid, so that it is possible to suppress the vibration generated at the start of rotation transmission by the coil spring.
Further, according to the configuration (1) above, in the rotary force transmission device for a bush cutter, the first shaft member, the second shaft member, and the coil spring are restrained by other members, so that the first shaft member It is possible to suppress bending (tilting) of the member or the second shaft member with respect to the other shaft member. By suppressing bending of the first shaft member and the second shaft member with respect to the other shaft member, bending vibration of the rotational force transmission device can be suppressed.

(2) In some embodiments, in the rotary force transmission device for a bush cutter described in (1) above, the compressed state holding device is connected to the second shaft member to move the second shaft member. A movement limiting member configured to limit movement of the member away from the first shaft member.

According to the configuration (2) above, in the rotary force transmission device for a bush cutter, the second shaft member is moved away from the first shaft member by the movement restricting member connected to the second shaft member. By limiting , the compressed state of the coil spring can be maintained. Therefore, according to the above configuration, the rotary force transmission device for the bush cutter can suppress the abnormal noise generated at the start of rotation transmission by the coil spring with a simple configuration.

(3) In some embodiments, in the rotary force transmission device for a bush cutter described in (2) above, the compressed state holding device moves the first shaft member along the direction in which the axis extends. and a biasing member configured to bias toward the second shaft member, and the movement restricting member is configured to receive a reaction force of the biasing member.

According to the configuration (3) above, since the movement restricting member receives the reaction force of the biasing member, the first shaft member is moved to the second shaft member along the direction in which the axis extends. can be biased toward Since the coil spring is compressed by the biasing force of the biasing member, it can maintain an appropriate compressed state.

(4) In some embodiments, in the rotary force transmission device for a bush cutter according to (3) above, the first shaft member is a cylinder extending along the direction in which the axis extends. The second shaft member further includes an insertion shaft configured to be insertable into the tubular portion, and the movement restricting member extends from the first shaft in the direction in which the axis extends. A reaction force receiving portion located on the opposite side of the shaft member to the second shaft member and extending along a direction intersecting the direction in which the axis extends, and coupled to the insertion shaft portion. the biasing member is disposed between the reaction force receiving portion of the movement restricting member and the first shaft member in the direction in which the axis extends. rice field.

According to the configuration (4) above, the first shaft member, the second shaft member and the coil spring are restrained by other members by the movement restricting member and the biasing member. can be suppressed from bending (tilting) with respect to the first shaft member. Further, in the rotary force transmission device of the bush cutter, the biasing member absorbs the movement of the first shaft member and the second shaft member along the axial direction and the deflection with respect to other shaft members. It is possible to effectively suppress the vibration that occurs in the

(5) In some embodiments, in the rotary force transmission device for a brush cutter described in (4) above, the reaction force receiving portion has an outer dimension in a direction perpendicular to the direction in which the axis extends. It was configured to be larger than the insertion shaft portion.

According to the configuration (5) above, since the reaction force receiving portion is connected to the second shaft member, when the second shaft member is tilted with respect to the first shaft member, the second shaft member Tilts in conjunction with Here, if the outer dimensions of the reaction force receiving portion are large, the amount of movement in the direction in which the axis of the outer peripheral side portion extends when the reaction force receiving portion is tilted increases accordingly. Power can be exerted quickly. Therefore, according to the above configuration, the reaction force receiving portion has a larger outer dimension in the direction orthogonal to the direction in which the axis extends than the insertion shaft portion. , the biasing force of the biasing member can be exerted quickly. Therefore, according to the above configuration, the biasing force of the biasing member can be rapidly exerted, so that vibrations occurring in the rotational force transmission device can be effectively suppressed.

(6) In some embodiments, in the rotary force transmission device for a bush cutter according to (4) or (5) above, the movement restricting member is positioned closer to the first shaft than to the reaction force receiving portion. The urging member further includes a small-diameter portion that is provided on the member side and is configured such that one end portion abuts on the first shaft member and that is formed to have a diameter smaller than that of the reaction force receiving portion. It has an outer dimension smaller than that of the reaction force receiving portion and is arranged on the outer periphery of the small diameter portion.

According to the above configuration (6), the movement restricting member is connected to the second shaft member with one end of the small diameter portion in contact with the first shaft member. It is possible to prevent a decrease in the connecting force connecting the reaction force receiving portion and the second shaft member when damaged. In addition, since one end of the small diameter portion of the movement restricting member is in contact with the first shaft member, the distance between the reaction force receiving portion and the end of the first shaft member on the side of the reaction force receiving portion is reduced. can be prevented from fluctuating, and the biasing member arranged on the outer periphery of the small-diameter portion can exert a stable biasing force. Further, the movement restricting member is connected to the second shaft member, and one end of the small diameter portion is in contact with the first shaft member. Since the one end prevents the second shaft member from tilting with respect to the first shaft member, it is possible to effectively suppress the second shaft member from tilting with respect to the first shaft member.

(7) In some embodiments, in the rotary force transmission device for a brush cutter according to any one of (4) to (6) above, the biasing member has one end in the direction in which the axis extends. contacts the reaction force receiving portion, and the other end in the direction in which the axis extends contacts the end surface of the first shaft member.

According to the configuration (7) above, the biasing member has one end in the direction in which the axis extends that contacts the reaction force receiving portion, and the other end in the direction that the axis extends contacts the first shaft member. Therefore, when the first shaft member or the second shaft member moves or bends along the axial direction, the biasing force of the biasing member is applied to the first shaft member or the second shaft member. It can be quickly exerted on the member. Therefore, according to the above configuration, the biasing force of the biasing member can be rapidly exerted, so that vibrations occurring in the rotational force transmission device can be effectively suppressed.

(8) In some embodiments, the rotary force transmission device for a brush cutter according to any one of (4) to (7) above, wherein the rotary force transmission device for a brush cutter includes a drum of a clutch drum. Further comprising, the first shaft member is a drum fixing portion configured to be fixed to an opening formed in a wall portion extending along a direction intersecting the direction in which the axis of the drum extends. wherein one end of the biasing member in the direction in which the axis extends contacts the reaction force receiving portion, and the other end in the direction in which the axis extends contacts the wall surface. Configured.

According to the configuration (8) above, the drum fixing portion of the first shaft member is fixed to the opening formed in the wall surface portion of the drum. That is, the first shaft member is provided integrally with the drum. One end of the biasing member in the direction in which the axis extends contacts the reaction force receiving portion, and the other end in the direction in which the axis extends contacts the wall surface of the drum. When the or second shaft member moves or bends along the axial direction, the biasing force of the biasing member can be quickly exerted on the first shaft member or the second shaft member. . Therefore, according to the above configuration, the biasing force of the biasing member can be rapidly exerted, so that vibrations occurring in the rotational force transmission device can be effectively suppressed.

(9) A bush cutter according to at least one embodiment of the present invention includes a rotational force generating device configured to generate a rotational force, and the rotational force generated by the rotational force generating device is transmitted through a coil spring. A cutting blade configured to transmit power, and a torque transmitting device according to any one of (1) to (8) above.
According to the above configuration, the rotational force transmission device can suppress abnormal noise caused by the contact of the coil spring with other parts at the start of transmission of rotation by the coil spring.

According to at least one embodiment of the present invention, there is provided a rotary force transmission device for a brush cutter capable of suppressing abnormal noise caused by the contact of the coil spring with other parts at the start of rotation transmission by the coil spring.

1 is a schematic cross-sectional view schematically showing the configuration of a bush cutter according to an embodiment of the present invention; FIG. 1 is a schematic partial enlarged cross-sectional view showing an enlarged centrifugal clutch casing and a torque transmission device in a brush cutter according to an embodiment of the present invention; FIG. 1 is a schematic cross-sectional view schematically showing the configuration of a rotary force transmission device for a bush cutter according to a first embodiment of the present invention; FIG. It is a schematic perspective view which shows a part of drive-side shaft member. It is a schematic perspective view which shows a part of driven side shaft member. FIG. 6 is a schematic cross-sectional view schematically showing the configuration of a rotary force transmission device for a bush cutter according to a second embodiment of the present invention; FIG. 11 is a schematic cross-sectional view schematically showing the configuration of a rotary force transmission device for a bush cutter according to a third embodiment of the present invention; FIG. 11 is a schematic cross-sectional view schematically showing the configuration of a rotary force transmission device for a bush cutter according to a fourth embodiment of the present invention; FIG. 4 is a schematic cross-sectional view taken along the line AA in FIG. 3, showing a schematic configuration of a rotational force transmission mechanism provided between the through-hole of the drive-side shaft member and the insertion shaft portion of the driven-side shaft member; It is a schematic cross-sectional view schematically shown.

Several embodiments of the present invention will now be described with reference to the accompanying drawings. However, the dimensions, materials, shapes, relative arrangements, etc. of the components described as embodiments or shown in the drawings are not intended to limit the scope of the present invention, and are merely illustrative examples. do not have.
For example, expressions denoting relative or absolute arrangements such as "in a direction", "along a direction", "parallel", "perpendicular", "center", "concentric" or "coaxial" are strictly not only represents such an arrangement, but also represents a state of relative displacement with a tolerance or an angle or distance to the extent that the same function can be obtained.
For example, expressions such as "identical", "equal", and "homogeneous", which express that things are in the same state, not only express the state of being strictly equal, but also have tolerances or differences to the extent that the same function can be obtained. It shall also represent the existing state.
For example, expressions that express shapes such as squares and cylinders do not only represent shapes such as squares and cylinders in a geometrically strict sense, but also include irregularities and chamfers to the extent that the same effect can be obtained. The shape including the part etc. shall also be represented.
On the other hand, the expressions "comprising", "including", or "having" one component are not exclusive expressions excluding the presence of other components.
In addition, the same code|symbol may be attached|subjected about the same structure and description may be abbreviate|omitted.

FIG. 1 is a schematic cross-sectional view schematically showing the construction of a bush cutter according to one embodiment of the present invention.
A bush cutter 1 according to some embodiments of the present invention, as shown in FIG. a cutting blade unit 2 including a cutting blade unit 2, a rotational force transmission device 3, and an operating rod 4 configured to rotatably support a transmission shaft member 12. Although the details will be described later, the brush cutter 1 transmits the rotational force generated by the rotational force generating device 11 to the cutting blade 21 (the cutting blade unit 2) via the rotational force transmission device 3 and the transmission shaft member 12. is configured to

The rotational force generator 11 (motor) is configured to generate rotational force (driving force) for rotating the cutting blade 21 . The rotational force generator 11 may be an internal combustion engine such as a 2-stroke engine or a 4-stroke engine, or an electric motor.

As shown in FIG. 1, the operation rod 4 is composed of a long cylindrical operation rod body 41 extending along the direction in which the axis LA extends, and an inner peripheral wall (inside) of the operation rod body 41. and at least one bearing 42 mounted thereon.

As shown in FIG. 1, the bearing 42 rotatably supports the long rod-shaped transmission shaft member 12 extending in the same direction as the operation rod main body 41, that is, along the direction in which the axis LA extends. Support. The bearing 42 includes an oil-impregnated bearing that supports the transmission shaft member 12 and an elastic rubber attached to the outer periphery of the oil-impregnated bearing.

As shown in FIG. 1, the operating rod main body 41 has a distal end portion 411 located on the cutting blade unit 2 side (left side in the drawing) which can rotate the bevel gear 22 connected to the distal end portion 121 of the transmission shaft member 12 . supported by A cutting blade casing 20 of the cutting blade unit 2 that houses the bevel gear 22 is attached to the distal end portion 411 .
As shown in FIG. 1, the operating rod main body 41 has the centrifugal clutch casing 5 attached to a base end portion 412 located on the base end side (right side in the drawing). In the illustrated embodiment, the operating rod main body 41 is a covering member made of a tubular rubber material configured to closely fit onto the outer periphery of the base end portion 412, as shown in FIG. 2 which will be described later. 17, and a cylindrical metal material configured to be closely fitted to the outer periphery of the covering member 17 and to be closely fitted to the inner peripheral surface of the operating rod mounting portion 514 of the centrifugal clutch casing 5. It is attached to the centrifugal clutch casing 5 via a sleeve 18 which is formed as follows.

The centrifugal clutch casing 5 accommodates a later-described centrifugal clutch drum 52 (see FIG. 2). The base end portion 412 is attached to the rotational force generator 11 via the centrifugal clutch casing 5 or the like.

As shown in FIG. 1, the cutting blade unit 2 includes the cutting blade casing 20 described above, the bevel gear 22 described above, and a cutting blade support shaft configured to be rotatably supported in the cutting blade casing 20. 23 , a bevel gear 24 fixed to the base end side (upper side in the drawing) of the cutting blade support shaft 23 , and the above-described cutting blade 21 fixed to the distal end portion of the cutting blade support shaft 23 . The bevel gear 24 meshes with the bevel gear 22 connected to the transmission shaft member 12 . The rotational force generated by the rotational force generator 11 is transmitted to the bevel gear 22 via the rotational force transmission device 3 and the transmission shaft member 12 . The rotational force transmitted to the bevel gear 22 is transmitted to the cutting blade 21 via the bevel gear 24 and the cutting blade support shaft 23 to rotate the cutting blade 21 .

The rotational force transmission device 3 is attached to the base end portion 122 of the transmission shaft member 12, as shown in FIG.

FIG. 2 is a schematic partially enlarged cross-sectional view showing an enlarged centrifugal clutch casing and a torque transmission device in the bush cutter according to one embodiment of the present invention. Hereinafter, the side on which the rotational force generator 11 is positioned (left side in FIG. 2) in the direction in which the axis LA extends is referred to as the proximal side, and the side on which the cutting blade 21 is positioned (right side in FIG. 2) is referred to as the distal side.

The brush cutter 1 transmits the rotational force generated by the rotational force generating device 11 to the rotating mechanism portion 54 and the drum 53 of the centrifugal clutch drum 52 and the driving side shaft member 6 of the rotational force transmission device 3 as shown in FIG. , the coil spring 8, the driven side shaft member 7, and the transmission shaft member 12 in this order, the power is transmitted to the cutting blade 21 (cutting blade unit 2). A detailed description will be given below.

As shown in FIG. 2, the centrifugal clutch casing 5 includes a housing 51 configured to be fixed to the rotational force generator 11 with a fastening device such as a screw.
As shown in FIG. 2, the housing 51 rotatably accommodates a drum 53 of a centrifugal clutch drum 52 forming a centrifugal clutch. The centrifugal clutch drum 52 includes a drum 53 and a rotating mechanism section 54 .

In the illustrated embodiment, the housing 51 contains a device fixing portion 511 configured to be fixed to the rotational force generating device 11 and at least a portion of the drum 53, as shown in FIG. A drum accommodating portion 512 configured, a bearing accommodating portion 513 configured to accommodate the bearing 13, and an operation-rod attachment portion 514 configured to be attached to the base end portion 412 of the operation-rod main body 41. include.

In the embodiment shown in FIG. 2, the housing 51 is provided with a device fixing portion 511, a drum housing portion 512, a bearing housing portion 513, and an operating rod mounting portion 514 in this order from the base end side (left side in the drawing). A device fixing portion 511, a drum housing portion 512, a bearing housing portion 513, and an operating rod mounting portion 514 are integrally formed. Each of the drum housing portion 512, the bearing housing portion 513, and the operating rod mounting portion 514 is formed concentrically, and at least a portion thereof extends along the direction extending along the axis LA. The device fixing portion 511 protrudes from the end located on the base end side of the outer surface of the drum accommodating portion 512 and extends along a direction intersecting (perpendicular to) the axis LA.

As shown in FIG. 2, the drum 53 is formed in a bottomed cylindrical shape that opens toward the base end side (left side in the drawing). That is, as shown in FIG. 2, the drum 53 includes a peripheral wall portion 531 extending along the axis LA, and an inner surface 534 of the peripheral wall portion 531 protruding from an edge portion on the tip side in the direction in which the axis LA extends. and wall portions 532 extending along intersecting (perpendicular) directions.
As shown in FIG. 2 , the drum 53 is configured to accommodate the rotation mechanism 54 of the centrifugal clutch drum 52 in an internal space 533 defined by a peripheral wall portion 531 and a wall surface portion 532 .

As shown in FIG. 2, the rotation mechanism 54 is connected to the rotation force generator 11, and when the rotation speed exceeds a predetermined speed, the rotation mechanism 54 is pressed against the inner surface 534 of the peripheral wall 531 of the drum 53 by centrifugal force. create frictional resistance between The rotation mechanism section 54 uses the frictional resistance to transmit the rotational force transmitted from the rotational force generator 11 to the drum 53 .

As shown in FIG. 2, the drum 53 is configured to be fixed with the drum fixing portion 61 of the drive-side shaft member 6 inserted into an opening 535 formed in the center of the wall surface portion 532 . there is In some embodiments, drum fixture 61 is secured to opening 535 by welding or crimping, crimping, or the like.

As shown in FIG. 2, the drive-side shaft member 6 is rotatably supported by the bearings 13 described above.
In the illustrated embodiment, as shown in FIG. 2, the drive-side shaft member 6 has a base end portion 62 whose end face 621 on the base end side (left side in the drawing) abuts against an outer surface 536 of the wall surface portion 532; The above-described drum fixing portion 61 that protrudes from an end surface 621 of the base end portion 62 and is formed in a cylindrical shape having an outer dimension smaller than that of the base end portion 62, and the end surface of the base end portion 62 on the tip side (right side in the figure). and a covering portion 63 protruding from the base end portion 622 and formed in a cylindrical shape having an outer dimension smaller than that of the base end portion 62 . The drum fixing portion 61 and the covering portion 63 extend along the direction in which the axis LB of the driving side shaft member 6 extends.

In the illustrated embodiment, the drive-side shaft member 6 has an annular groove 632 formed in the outer peripheral surface 631 of the covering portion 63, as shown in FIG. A retaining ring 14 is fitted in the annular groove 632 . A portion of the covering portion 63 between the base end portion 62 and the annular groove 632 in the direction in which the axis LB extends is a supported portion 63A that is inserted into the bearing 13 and supported by the bearing 13 . Since the inner peripheral portion of the bearing 13 is sandwiched between the end surface 622 of the base end portion 62 and the retaining ring 14, movement in the direction in which the axis LA extends is restricted.

In the illustrated embodiment, the bearing 13 is made of a metal material and fits into the bearing receiving portion 513 of the housing 51, as shown in FIG. An annular groove 55 is formed on the proximal end side of the inner peripheral surface 515 of the bearing housing portion 513 . A retaining ring 15 is fitted in the annular groove 55 .
Moreover, as shown in FIG. 2, the bearing accommodating portion 513 has a locking surface 516 that protrudes from the inner peripheral surface 515 to the distal side of the annular groove 55 and faces the proximal side. Since the outer peripheral portion of the bearing 13 is sandwiched between the locking surface 516 of the bearing accommodating portion 513 and the retaining ring 15, movement in the direction in which the axis LA extends is restricted.

In another embodiment, the bearing 13 is made of a resin material and is molded simultaneously with the bearing housing portion 513 described above. In this case, the movement of the bearing 13 in the direction in which the axis LA extends with respect to the bearing accommodating portion 513 is restricted, so the annular groove 55 and the retaining ring 15 described above are unnecessary.

The drive-side shaft member 6 rotatably supported by the bearing 13 rotates about the axis LB of the drive-side shaft member 6 upon transmission of rotational force from the drum 53 . The axis LB is arranged coaxially with the axis LA.

FIG. 3 is a schematic cross-sectional view schematically showing the configuration of the rotary force transmission device for the bush cutter according to the first embodiment of the present invention. FIG. 4 is a schematic perspective view showing a portion of the drive-side shaft member. FIG. 5 is a schematic perspective view showing part of the driven side shaft member. FIG. 4 omits the annular groove 632 described above. An arrow R in FIG. 4 indicates the direction of rotation of the drive-side shaft member 6 .
As shown in FIGS. 2 and 3, the rotational force transmission device 3 includes the driving side shaft member 6, the driven side shaft member 7, the coil spring 8, and the compression state holding device 9 described above. As shown in FIGS. 2 and 3, the rotational force transmission device 3 is configured to transmit the rotational force transmitted to the driving side shaft member 6 to the driven side shaft member 7 via the coil spring 8. .

As shown in FIG. 3, the coil spring 8 has a shape in which a wire is spirally wound multiple times. In the illustrated embodiment, the tip surfaces 81 and 83 of the coil spring 8 have a shape as if they were cut in a direction intersecting the axis of the wire. In the illustrated embodiment, as shown in FIG. 3, the coil spring 8 has a rectangular cross-sectional shape with respect to the axis of the wire. In other embodiments, the coil spring 8 may have a circular or elliptical cross-sectional shape with respect to the axis of the wire.

As shown in FIG. 2, the driven side shaft member 7 is fixed to the base end portion 122 of the transmission shaft member 12 described above so as not to rotate relative to it. The transmission shaft member 12 is configured to rotate in conjunction with the rotation of the driven side shaft member 7 .

In the illustrated embodiment, as shown in FIG. 2, the driven-side shaft member 7 has an opening in the center of the distal end surface 771 of the cylindrical portion 77 located on the distal end side, and extends along the axis LC. A shaft hole 78 is formed extending along the direction in which the . A female spline 781 is formed on the inner peripheral surface of the shaft hole 78 . 2, a male spline 123 configured to mesh with the female spline 781 is formed on the outer peripheral surface of the base end portion 122 of the transmission shaft member 12. As shown in FIG. The transmission shaft member 12 is inserted into the shaft hole 78 from the tip side, and the male spline 123 meshes with the female spline 743 , so that the transmission shaft member 12 rotates in conjunction with the rotation of the driven side shaft member 7 .
In another embodiment, the driven side shaft member 7 may be configured so as not to rotate relative to the transmission shaft member 12 by press fitting or welding, or may be formed integrally with the transmission shaft member 12. may be

As shown in FIG. 3, the drive-side shaft member 6 includes a tip surface contact portion 65 configured to be able to contact a tip surface 81 on the base end side (left side in the figure) of the wire of the coil spring 8, and a coil and a side seat abutting portion 66 configured to be able to contact the side seat 82 on the base end side of the spring 8 .
As shown in FIG. 3, the driven-side shaft member 7 includes a tip surface contact portion 72 configured to be able to contact a tip surface 83 on the tip side (right side in the figure) of the wire of the coil spring 8, and a coil spring. a side seat abutting portion 73 configured to be able to abut on the side seat 84 on the base end side of 8.

In the illustrated embodiment, the drive-side shaft member 6 includes a coil spring abutment portion 64 configured to protrude from the inner circumference of the base end portion 62, as shown in FIG. In other words, the base end portion 62 is configured to protrude from the outer circumference of the coil spring contact portion 64 . The coil spring contact portion 64 is formed integrally with the base end portion 62 .
The coil spring contact portion 64 includes a tip surface contact portion 65 and a side seat contact portion 66, as shown in FIG. The tip surface contact portion 65 includes a helical end surface 661 which is provided at the tip end portion 641 of the coil spring contact portion 64 and extends around the axis LB in the circumferential direction. The side seat contact portion 66 includes a side step surface 651 formed between one end and the other end of the spiral end surface 661 .

In the illustrated embodiment, the driven side shaft member 7 includes a coil spring contact portion 71 as shown in FIG.
The coil spring contact portion 71 includes a tip surface contact portion 72 and a side seat contact portion 73, as shown in FIG. The distal end face contact portion 72 includes a spiral end face 731 that is provided at the proximal end portion 711 of the coil spring contact portion 71 and that extends around the axis LC in the circumferential direction. The side seat contact portion 73 includes a side step surface 721 formed between one end and the other end of the spiral end surface 731 .
In the embodiment shown in FIG. 2 , the tubular portion 77 described above is provided so as to coaxially protrude from an end surface 712 on the tip side of the coil spring contact portion 71 . The tubular portion 77 is formed to have a smaller diameter than the coil spring contact portion 71 . The covering portion 63 described above has a length covering the entire length of the coil spring 8 and the entire length of the cylindrical portion 77 in the direction in which the axis LA extends.

As shown in FIG. 3 , the side seat 82 on the base end side of the coil spring 8 contacts the side seat contact portion 66 . A tip surface 81 on the tip side of the coil spring 8 contacts the tip surface contact portion 65 when the coil spring 8 transmits a rotational force.
Further, as shown in FIG. 3 , the side seat 84 on the distal end side of the coil spring 8 contacts the side seat contact portion 73 . A tip surface 83 on the tip side of the coil spring 8 contacts the tip surface contact portion 72 when the coil spring 8 transmits a rotational force.
When the coil spring 8 does not transmit the rotational force, the tip surface 81 of the coil spring 8 does not have to contact the tip surface contact portion 65, and the tip surface 83 of the coil spring 8 does not have to contact the tip surface contact portion 65. , may not be in contact with the tip surface contact portion 72 .

In the illustrated embodiment, as shown in FIGS. 3 and 4, the drive-side shaft member 6 is a cylindrical coil that coaxially protrudes from an end portion 641 on the tip side of the coil spring contact portion 64 . A spring insertion portion 67 (cylindrical portion) and a through hole 68 that extends from a distal end surface 671 of the coil spring insertion portion 67 along the direction in which the axis LB extends and penetrates the driving side shaft member 6. include. As shown in FIG. 3, the coil spring insertion portion 67 is formed to have a diameter smaller than that of the coil spring contact portion 64 and is configured to be insertable into the coil spring 8 .
3 and 5, the driven-side shaft member 7 is a cylindrical member that coaxially protrudes from an end portion 711 of the coil spring contact portion 71 on the distal end side. an insertion shaft portion 75 coaxially protruding from a distal end surface 741 of the coil spring insertion portion 74; and an internal threaded portion 76 formed in the . As shown in FIG. 3, the coil spring insertion portion 74 is formed to have a larger diameter than the insertion shaft portion 75 and a smaller diameter than the coil spring contact portion 71, and is configured to be insertable into the coil spring 8. It is

As shown in FIG. 3 , the driven side shaft member 7 is arranged such that the side seat contact portion 73 faces the side seat contact portion 66 of the driving side shaft member 6 . The coil spring 8 is arranged between the side seat contact portion 66 and the side seat contact portion 73 . The side seat 82 on the proximal side of the coil spring 8 faces the side seat contact portion 66 of the drive side shaft member 6 , and the side seat 84 on the distal end side faces the side seat contact portion 73 of the driven side shaft member 7 . are placed facing each other.

As shown in FIG. 3, the coil spring insertion portion 67 of the driving side shaft member 6 is inserted into the coil spring 8 from the base end side, and the coil spring insertion portion 74 of the driven side shaft member 7 is inserted from the distal end side. It is inserted in the coil spring 8. The axis LC of the driven side shaft member 7 is arranged coaxially with the axis LB and the axis LA by inserting the insertion shaft portion 75 of the driven side shaft member 7 into the through hole 68 of the driving side shaft member 6. there is

As shown in FIG. 3, the coil spring 8 is configured to transmit rotational force between the driving side shaft member 6 and the driven side shaft member 7 via a tip end surface 81 and a tip end surface 83. .
When the coil spring 8 is rotated by the rotational force transmitted to the driving side shaft member 6 , the distal end surface 81 on the base end side is brought into contact with the distal end surface contact portion 65 of the driving side shaft member 6 . The coil spring 8 rotates in the same direction as the drive-side shaft member 6 by transmitting the rotational force of the drive-side shaft member 6 via the tip surface 81 .
When the coil spring 8 of the driven-side shaft member 7 rotates in conjunction with the drive-side shaft member 6 , the tip end face 83 of the coil spring 8 contacts the tip end face contact portion 72 of the driven-side shaft member 7 . be. The driven-side shaft member 7 rotates around the axis LC of the driven-side shaft member 7 in the same direction as the coil spring 8 when the rotational force of the coil spring 8 is transmitted through the tip surface contact portion 72 . .

As shown in FIG. 3 , a gap G is provided between the inner peripheral surface 681 of the through hole 68 and the outer peripheral surface 752 of the insertion shaft portion 75 . The gap G can regulate excessive bending vibration in the direction perpendicular to the axis LA. In addition, the coil spring 8 is twisted and bent within the range of the gap G, that is, within the range where the through hole 68 and the insertion shaft portion 75 do not interfere with each other, thereby absorbing torsional vibration and bending vibration. It has become. As shown in FIG. 3, in the drive-side shaft member 6, the gap between the inner peripheral surface 633 of the covering portion 63 covering the outer peripheral side of the coil spring 8 and the outer peripheral surface 672 of the coil spring insertion portion 67 is The wire diameter of the coil spring 8 is larger than that of the coil spring 8 to the extent that the spring 8 can be twisted or bent.

As shown in FIG. 3, the compressed state holding device 9 is configured such that the coil spring 8 is sandwiched between the side seat contact portion 66 of the driving side shaft member 6 and the side seat contact portion 73 of the driven side shaft member 7 to hold the coil spring 8 therebetween. 8 in compression. Here, the compressed state means a state in which the coil spring 8 can exhibit elastic force (restoring force) with respect to the driving side shaft member 6 and the driven side shaft member 7 . The compressed state holding device 9 keeps the side seat 84 on the tip side of the coil spring 8 in close contact with the side seat contact portion 73 of the driven side shaft member 7 even when the driving side shaft member 6 and the coil spring 8 are not rotating. In addition, the base end side side seat 82 of the coil spring 8 is brought into close contact with the side seat contact portion 66 of the driving side shaft member 6 .

In the illustrated embodiment, as shown in FIG. 3 , the compressed state holding device 9 is coupled to the driven side shaft member 7 to prevent movement of the driven side shaft member 7 away from the drive side shaft member 6 . It includes a movement limiting member 90 configured to limit.

In the embodiment shown in FIG. 3 , the movement restricting member 90 includes an annular member 91 having a through hole 911 , a shaft portion inserted through the through hole 911 of the annular member 91 , and a distal end of the shaft portion extending to the driven side shaft member 7 . and a fastening member 92 (bolt) screwed into the female threaded portion 76 formed on the insertion shaft portion 75 of the connector. The drive-side shaft member 6 includes a concave portion 611 formed on the inner peripheral side of the drum fixing portion 61 by the drum fixing portion 61 protruding from the base end portion 62 . As shown in FIG. 3 , the annular member 91 is accommodated in the recess 611 , and the outer peripheral portion of the front end side surface 912 is engaged with the bottom surface 612 of the recess 611 .

According to the above configuration, since the proximal surface 913 of the annular member 91 is engaged with the head portion of the fastening member 92 screwed to the insertion shaft portion 75, the annular member 91 does not move proximally. is restricted. The driven-side shaft member 7 is pushed toward the distal end side away from the drive-side shaft member 6 by the compressed coil spring 8 , but the annular member 91 connected to the driven-side shaft member 7 via the fastening member 92 . However, since it is engaged with the drive-side shaft member 6, its movement in the direction away from the drive-side shaft member 6 is restricted. The movement restricting member 90 restricts the movement of the driven side shaft member 7 to keep the coil spring in a compressed state.

Further, according to the above configuration, by replacing the fastening member 92 or adjusting the torque applied by the fastening member 92, even after fastening the fastening member 92 to the driven side shaft member 7, the fastening The tightening force (axial force) of the member 92 can be adjusted (readjusted). By adjusting the tightening force of the fastening member 92, the coil spring 8 can be adjusted to a compressed state suitable for vibration absorption.

In one embodiment, the annular member 91 discussed above comprises a plain washer. In this case, it is inexpensive and readily available.
Also, in some embodiments, the annular member 91 described above includes a thrust bearing configured to receive thrust forces. In this case, when the coil spring 8 starts to transmit rotation, it is possible to suppress the hitting vibration caused by the movement of the driven side shaft member 7 along the direction in which the axis LA extends.

In addition, in the embodiment shown in FIG. 3, a gap C1 is provided between the distal end surface 671 of the coil spring insertion portion 67 and the distal end surface 741 of the coil spring insertion portion 74. A gap C<b>2 is provided between 751 and a surface 912 on the distal end side of the annular member 91 . In this case, tightening the fastening member 92 pushes the drive-side shaft member 6 and the coil spring 8 toward the distal end side, so that the coil spring 8 can be further compressed. When the coil spring 8 is in a desired compressed state, the gaps C1 and C2 may not exist.

The rotary force transmission device 3 of the bush cutter 1 according to some embodiments includes, for example, as shown in FIG. It is arranged between the driven side shaft member 7 including the portion 73 and the drive side shaft member 6 and the driven side shaft member 7 described above, and through both tip surfaces 81 and 83 of the wire of the coil spring 8, A coil spring 8 configured to transmit rotational force between the driving side shaft member 6 and the driven side shaft member 7, and the side seat contact portion 66 and the side seat contact portion 73 sandwich the coil spring 8. and a compression holding device 9 configured to hold the coil spring 8 axially and/or torsionally compressed.

According to the above configuration, the rotational force transmission device 3 of the bush cutter 1 sandwiches the coil spring 8 between the side seat contact portion 66 and the side seat contact portion 73 so that the coil spring 8 is moved in the axial direction. and/or a compressed state holding device 9 configured to hold it in torsionally compressed state. For this reason, the rotational force transmission device 3 of the brush cutter 1 causes the side seat 82 to contact the side seat contact portion 66 by the compressed state holding device 9, and the other side seat 84 of the coil spring 8 to contact the side seat contact portion 66. It is brought into contact with the side seat contact portion 73 . According to the above configuration, the tip surfaces 81 and 83 of the wire rod of the coil spring 8 are brought into contact with the tip surfaces while frictional resistance is generated between the contacting members (the driving side shaft member 6 and the driven side shaft member 7). It can be brought into contact with the portion 65 and the tip surface contact portion 72 . In the state where frictional resistance is generated between the contacting members, the drive side shaft member 6, the driven side shaft member 7 and the coil spring 8 are restrained by other members compared to the case where the frictional resistance is not generated. Since the vibration of these members is suppressed, the contact noise generated when the tip surfaces 81 and 83 of the wire of the coil spring come into contact with the tip surface contact portion 65 and the tip surface contact portion 72 is suppressed. be able to.

According to the above configuration, the rotational force transmission device 3 of the bush cutter 1 is configured such that the coil spring 8 is in contact with the driving side shaft member 6 and the driven side shaft member 7 when the rotation transmission by the coil spring 8 is started. , the coil spring 8 is slid, so that the vibration generated at the start of rotation transmission by the coil spring 8 can be suppressed.
Further, according to the above configuration, in the rotary force transmission device 3 of the bush cutter 1, the driving side shaft member 6, the driven side shaft member 7 and the coil spring 8 are restrained by other members, so that the driving side shaft member 6 and the driven side shaft member 7 can be suppressed from bending (tilting) with respect to the other shaft member. By suppressing the bending of the drive-side shaft member 6 and the driven-side shaft member 7 with respect to the other shaft member, the bending vibration of the rotational force transmission device 3 can be suppressed.

In some embodiments, for example, as shown in FIG. 3 , the above-described compressed state holding device 9 is connected to the driven side shaft member 7 so as to move the driven side shaft member 7 away from the drive side shaft member 6 . It includes the movement limiting member 90 described above configured to limit movement. In this case, the rotational force transmission device 3 of the bush cutter 1 restricts the movement of the driven-side shaft member 7 away from the drive-side shaft member 6 by the movement restricting member 90 connected to the driven-side shaft member 7 . By doing so, the compressed state of the coil spring 8 can be maintained. Therefore, according to the above configuration, the torque transmission device 3 of the bush cutter 1 can suppress abnormal noise generated at the start of rotation transmission by the coil spring 8 with a simple configuration.

In some other embodiments, the compressed state holding device 9 is configured to be connected to the driving side shaft member 6 to restrict movement of the driving side shaft member 6 away from the driven side shaft member 7. may include a travel restricting member. That is, the drive-side shaft member 6 may be the first shaft member or the second shaft member. The same applies to several embodiments described later.

FIG. 6 is a schematic cross-sectional view schematically showing the configuration of a rotary force transmission device for a bush cutter according to a second embodiment of the present invention.
In some embodiments, for example, as shown in FIG. 6, the compressed state holding device 9 described above includes the movement restricting member 90 described above and the driving side shaft member 6 driven along the direction in which the axis line LA extends. and a biasing member 93 configured to bias toward the side shaft member 7 .

In the illustrated embodiment, the biasing member 93 includes an elastic member arranged in a compressed state in the direction in which the axis LA extends, as shown in FIG. As the elastic member, an annular disk spring or spring washer that can exert a large restoring force with a small amount of deformation, or an annular plate with a corrugated shape that can receive the thrust load evenly around the circumference. A washer and the like are included. Disc springs, spring washers, and wave washers are widely used in industrial machines and the like, and are inexpensive and have spring constants suitable for absorbing vibrations in rotational force transmission devices.

In the illustrated embodiment, the movement limiting member 90 discussed above includes the annular member 91 discussed above and the fastening member 92 discussed above, as shown in FIG. The biasing member 93 is arranged on the distal end side of the annular member 91 and accommodated in the recess 611 together with the annular member 91 . The biasing member 93 has a proximal end in contact with the outer peripheral portion of the distal end side surface 912 of the annular member 91 , and a distal end in contact with the bottom surface 612 of the concave portion 611 of the driving side shaft member 6 . ing. According to the above configuration, since the annular member 91 of the movement restricting member 90 receives the reaction force, the biasing member 93 moves the driving side shaft member 6 toward the driven side shaft member 7 along the direction in which the axis line LA extends. can be activated by Since the coil spring 8 is compressed by the biasing force of the biasing member 93, it can maintain an appropriate compressed state.

In some embodiments, for example, as shown in FIG. 6, the drive-side shaft member 6 described above extends along the direction in which the axis LA extends, and has a coil spring insert having the through-hole 68 described above. The above-described driven side shaft member 7 including the portion 67 (cylindrical portion) includes the above-described insertion shaft portion 75 configured to be insertable into the through hole 68 of the coil spring insertion portion 67 . The movement restricting member 90 described above is located on the opposite side (base end side) of the driven side shaft member 7 with respect to the driving side shaft member 6 in the direction in which the axis line LA extends, and the axis line LA extends. including the above-described annular member 91 (reaction force receiving portion) extending along a direction intersecting (perpendicular to) the direction, and a fastening member 92 (connecting portion) configured to be connected to the insertion shaft portion 75 . . The biasing member 93 described above is arranged between the annular member 91 and the drive-side shaft member 6 in the direction in which the axis LA extends.

According to the above configuration, the driving side shaft member 6, the driven side shaft member 7, and the coil spring 8 are restrained by other members by the movement restricting member 90 and the biasing member 93, so that the driven side shaft member 7 can be suppressed from bending (inclining) with respect to the drive-side shaft member 6 . Further, in the rotary force transmission device 3 of the brush cutter 1, the biasing member 93 absorbs the axial movement of the driving side shaft member 6 and the driven side shaft member 7 and the bending of the other shaft members. Vibration occurring in the force transmission device 3 can be effectively suppressed.

In some embodiments, as shown in FIG. 6, the above-described annular member 91 (reaction force receiving portion) has an outer dimension D2 in the direction orthogonal to the direction in which the axis LA extends, which is equal to that of the insertion shaft portion 75. It was configured to be larger than the external dimension D1.
In the illustrated embodiment, dimension D2 is greater than 1.5 times dimension D1. Preferably, it is greater than twice the outer dimension D1. Also, the outer dimension D2 is smaller than the inner diameter of the peripheral wall portion 531 of the drum 53 . In the illustrated embodiment, the outer dimension D2 is smaller than the inner diameter of the drum fixture 61 .

According to the above configuration, the annular member 91 is connected to the driven side shaft member 7 via the fastening member 92. Therefore, when the driven side shaft member 7 tilts with respect to the drive side shaft member 6, the driven side shaft It tilts in conjunction with the member 7. Here, if the outer dimension D2 of the annular member 91 is large, the amount of movement of the outer peripheral portion in the direction in which the axis LA extends when the annular member 91 is tilted increases accordingly. Power can be exerted quickly. Therefore, according to the above configuration, since the outer dimension D2 of the annular member 91 is larger than the outer dimension D1 of the insertion shaft portion 75, compared to the case where the outer dimension D2 is the same as the outer dimension D1, the urging force is reduced. The biasing force of the member 93 can be rapidly exerted. Therefore, according to the above configuration, the biasing force of the biasing member 93 can be rapidly exerted, so that the vibration generated in the rotational force transmission device 3 can be effectively suppressed.

In some embodiments, for example, as shown in FIG. 6, one end of the biasing member 93 in the direction in which the axis LA extends contacts the annular member 91 (reaction force receiving portion) and The other end in the direction in which LA extends is configured to abut on the bottom surface 612 of the drive-side shaft member 6 (the end surface of the first shaft member). In this case, one end of the biasing member 93 in the direction in which the axis LA extends contacts the annular member 91, and the other end in the direction in which the axis LA extends contacts the driving side shaft member 6. Therefore, when the drive-side shaft member 6 or the driven-side shaft member 7 moves or bends along the axial direction, the biasing force of the biasing member 93 is applied to the drive-side shaft member 6 or the driven-side shaft member 7. It can be demonstrated quickly. Therefore, according to the above configuration, the biasing force of the biasing member 93 can be rapidly exerted, so that the vibration generated in the rotational force transmission device 3 can be effectively suppressed.

FIG. 7 is a schematic cross-sectional view schematically showing the configuration of a rotary force transmission device for a bush cutter according to a third embodiment of the present invention.
In some embodiments, as shown in FIG. 7, the movement restricting member 90 described above is provided closer to the driving side shaft member 6 (front end side) than the annular member 91 (reaction force receiving portion). It further includes a small-diameter portion 96 configured such that one end portion (end face 942 on the distal end side) abuts against the shaft member 6 and is formed to have a diameter smaller than that of the annular member 91 (reaction force receiving portion). The biasing member 93 described above has an outer dimension smaller than that of the annular member 91 and is arranged on the outer circumference of the small diameter portion 96 .

In the illustrated embodiment, the movement limiting member 90 described above includes the fastening member 92 described above and a stepped member 94, as shown in FIG.
The stepped member 94 includes the above-described annular member 91 (large diameter portion) and the above-described small diameter portion 96 integrally formed with the annular member 91, as shown in FIG. In other words, the stepped member 94 has a stepped recess 95 formed on the distal end side so as to be recessed inwardly from the base end portion (annular member 91). A biasing member 93 is attached to the stepped concave portion 95 .

In the embodiment shown in FIG. 7, the distal end surface 942 of the stepped member 94 abuts the distal surface 751 of the insertion shaft portion 75 and the bottom surface 612 of the recess 611 . The biasing member 93 has an end on the base end side that contacts the stepped surface 951 of the stepped recess 95 (surface 912 on the tip side of the annular member 91 ), and an end on the tip end that contacts the recess 611 of the drive side shaft member 6 . is in contact with the bottom surface 612 of the . The stepped member 94 has a through hole 941 through which the shaft portion of the fastening member 92 can be inserted, and is connected to the insertion shaft portion 75 via the fastening member 92 that is inserted through the through hole 941 .

According to the above configuration, the movement restricting member 90 is connected to the driven side shaft member 7 in a state where the end surface 942 (one end portion of the small diameter portion 96) of the stepped member 94 on the distal end side is in contact with the driving side shaft member 6. Therefore, when the biasing member 93 is worn or damaged, it is possible to prevent a reduction in the connecting force connecting the annular member 91 (reaction force receiving portion) and the driven side shaft member 7 . Further, in the movement restricting member 90, the end surface 942 on the tip side of the stepped member 94 is in contact with the drive-side shaft member 6, so that the annular member 91 (reaction force receiving portion) and the bottom surface 612 of the recess 611 (drive-side shaft It is possible to prevent fluctuations in the distance between the member 6 and the end of the member 6 on the side of the reaction force receiving portion, and thus to allow the biasing member 93 arranged on the outer periphery of the small diameter portion 96 to exhibit a stable biasing force. can.
In addition, since the movement restricting member 90 is connected to the driven side shaft member 7 and the tip end surface 942 of the stepped member 94 is in contact with the drive side shaft member 6, the driven side shaft member 7 is Since the end surface 942 prevents tilting with respect to the drive-side shaft member 6 , tilting of the driven-side shaft member 7 with respect to the drive-side shaft member 6 can be effectively suppressed.

FIG. 8 is a schematic cross-sectional view schematically showing the configuration of a rotary force transmission device for a bush cutter according to a fourth embodiment of the present invention.
In some embodiments, as shown in FIG. 8, the biasing member 93 described above has one end in the direction in which the axis LA extends, as shown in FIG. ), and the other end in the extending direction of the axis LA is configured to abut on the wall surface portion 532 described above. In this case, the outer dimensions of the annular member 91 and the biasing member 93 can be made larger than those of the above-described several embodiments.

In the illustrated embodiment, the annular member 91 (reaction force receiving portion) described above has an outer dimension D3 in a direction orthogonal to the direction in which the axis LA extends, as shown in FIG. It was configured to be larger than the external dimension D1.
In the embodiment shown in FIG. 8, the outer dimension D3 is greater than the outer diameter of the drum fixing portion 61 and more than three times the outer dimension D1. Preferably, it is greater than five times the outer dimension D1. Also, the outer dimension D3 is smaller than the inner diameter of the peripheral wall portion 531 of the drum 53 .

According to the above configuration, the drive side shaft member 6 has the drum fixing portion 61 fixed to the opening 535 formed in the wall surface portion 532 of the drum 53 . That is, the drive-side shaft member 6 is provided integrally with the drum 53 . One end of the biasing member 93 in the direction in which the axis LA extends contacts the annular member 91 (reaction force receiving portion), and the other end in the direction in which the axis LA extends contacts the wall surface portion 532 of the drum 53 . Since they are in contact with each other, their external dimensions are large, and when the drive-side shaft member 6 and the driven-side shaft member 7 move or bend along the axial direction, they drive the biasing force of the biasing member 93 . The side shaft member 6 and the driven side shaft member 7 can be quickly exerted. Therefore, according to the above configuration, the biasing force of the biasing member 93 can be rapidly exerted, so that the vibration generated in the rotational force transmission device 3 can be effectively suppressed.

9 is a schematic cross-sectional view corresponding to the AA line of FIG. 3, showing a rotational force transmission mechanism provided between the through hole of the driving side shaft member and the insertion shaft portion of the driven side shaft member. 1 is a schematic cross-sectional view schematically showing the configuration of . An arrow R in FIG. 9 indicates the rotation direction of the driving side shaft member 6 and the driven side shaft member 7 . In FIG. 9, the covering portion 63 of the drive-side shaft member 6, the coil spring 8, and the like are omitted.

In some embodiments, the rotational force transmission device 3 is configured to transmit rotational force directly from the driving side shaft member 6 to the driven side shaft member 7 as shown in FIG. A mechanism section 31 is further provided.
In the illustrated embodiment, the rotational force transmission mechanism 31 includes, as shown in FIG. a second meshing portion 35 arranged alternately with the tooth spaces 37 in the circumferential direction and configured to be meshed with the first meshing portion 32 .

In the embodiment shown in FIG. 9, the first engaging portion 32 is formed on the outer peripheral surface 752 of the insertion shaft portion 75, and the second engaging portion 35 is formed on the inner peripheral surface 681 of the through hole 68. . In another embodiment, the first meshing portion 32 is formed on the outer peripheral surface 713 of the coil spring contact portion 71, and the second meshing portion 35 is formed on the inner peripheral surface 633 of the covering portion 63. may

As shown in FIG. 9 , the groove width W2 of the tooth spaces 37 of the second meshing portion 35 is configured to be longer than the tooth thickness W1 of the teeth 33 of the first meshing portion 32 . When the coil spring 8 is not transmitting the rotational force, the wall surface 331 positioned on the downstream side in the rotational direction R of the tooth 33 and the wall surface 371 (mating portion) positioned on the upstream side in the rotational direction R of the tooth groove 37 is larger than the sum of the distance between the tip surface 81 of the coil spring 8 and the tip surface contact portion 65 and the distance between the tip surface 83 of the coil spring 8 and the tip surface contact portion 72 designed to be wide.

After starting to transmit the rotational force, the coil spring 8 is twisted and twisted so as to absorb the torsional vibration that occurs when the rotation of the driven side shaft member 7 lags behind the rotation of the drive side shaft member 6. Absorb vibrations. When the coil spring 8 is twisted by a predetermined angle, or when the coil spring 8 wears out, the wall surface 311 and the wall surface 371 contact each other, and the drive-side shaft member 6 is driven by the rotational force transmission mechanism 31 . A rotational force is transmitted directly to the side shaft member 7 .

According to the above configuration, the rotational force transmission mechanism 31 prevents excessive load from being applied to the coil spring 8 due to the compressive force (frictional force) in the axial direction of the compressed state holding device 9 and prevents the coil spring 8 from beating and wearing. can be suppressed.

As shown in FIG. 1, the bush cutter 1 according to some embodiments includes the above-described rotational force generator 11, the above-described cutting blade 21, and the above-described rotational force transmission device 3. As shown in FIG. According to the above configuration, the rotational force transmission device 3 can suppress abnormal noise caused by the contact of the coil spring with other parts at the start of rotation transmission by the coil spring.

The present invention is not limited to the above-described embodiments, and includes modifications of the above-described embodiments and modes in which these modes are combined as appropriate.

For example, in some of the embodiments described above, the compressed state holding device 9 included one biasing member 93, but may include multiple biasing members 93, and these multiple biasing members 93 may be , the members may be of the same type or of different types.
Further, in some of the above-described embodiments, the annular member 91 and the biasing member 93 of the compressed state holding device 9 are subjected to surface treatment or coated with a lubricant such as grease so that the bottom surface 612 of the drive side shaft member 6 and the like are Wear and damage of the annular member 91 and the biasing member 93 due to contact with the contact may be prevented. In this case, the rotational force transmission device 3 can stably suppress vibration over a long period of time.

1 brush cutter 11 rotational force generator 12 transmission shaft member 13 bearings 14, 15 retaining ring 17 covering member 18 sleeve 2 cutting blade unit 20 cutting blade casing 21 cutting blades 22, 24 bevel gear 23 cutting blade support shaft 3 rotational force transmission device 31 Rotational force transmission mechanism portions 32, 35 Engaging portions 33, 36 Teeth 34, 37 Tooth grooves 4 Operation rod 41 Operation rod main body 42 Bearing 5 Centrifugal clutch casing 51 Housing 52 Centrifugal clutch drum 53 Drum 54 Rotation mechanism portion 55 Annular groove 6 Drive Side shaft member 61 Drum fixing portion 62 Base end portions 621, 622 End surface 63 Coating portion 63A Supported portion 631 Outer peripheral surfaces 64, 71 Coil spring contact portions 65, 72 Tip surface contact portions 66, 73 Side seat contact portion 67 , 74 coil spring insertion portion 68 through hole 7 driven side shaft member 75 insertion shaft portion 76 female screw portion 77 cylindrical portion 78 shaft hole 8 coil springs 81, 83 tip surfaces 82, 84 side seat 9 compressed state holding device 90 movement limiting member 91 Annular member 92 Fastening member 93 Biasing member 121, 411 Tip part 122, 412 Base end part 511 Device fixing part 512 Drum housing part 513 Bearing housing part 514 Operating rod mounting part 531 Peripheral wall part 532 Wall surface part 533 Internal space 534 Inner surface 535 Openings C1, C2, G Gap LA, LB, LC Axis

Claims (6)

A rotary force transmission device for a bush cutter configured to transmit a rotary force generated by a rotary force generator to a cutting blade via a coil spring,
a first shaft member including a first side seat abutment configured to be able to contact one side seat of the coil spring;
a second shaft member including a second side seat contact portion configured to contact the other side seat of the coil spring;
It is arranged between the first shaft member and the second shaft member, and connects the first shaft member and the second shaft member via both end surfaces of the wire rod of the coil spring. the coil spring configured to transmit rotational force between;
The coil spring is sandwiched between the first side seat contact portion and the second side seat contact portion to hold the coil spring in an axially and/or torsionally compressed state. and a compressed state holding device ,
The compressed state holding device includes a movement restricting member coupled to the second shaft member and configured to restrict movement of the second shaft member in a direction away from the first shaft member,
The compressed state holding device further includes a biasing member configured to bias the first shaft member toward the second shaft member along the direction in which the axis extends,
the movement restricting member is configured to receive a reaction force of the biasing member;
The first shaft member further includes a tubular portion extending along the direction in which the axis extends,
The second shaft member further includes an insertion shaft configured to be insertable into the tubular portion,
The movement restricting member is positioned opposite to the second shaft member with respect to the first shaft member in the direction in which the axis extends, and in a direction that intersects the direction in which the axis extends. a reaction force receiving portion extending along and a connecting portion configured to connect to the insertion shaft;
The biasing member is arranged between the reaction force receiving portion of the movement restricting member and the first shaft member in the direction in which the axis extends.
Rotary power transmission device for brush cutters. 2. The rotary force transmission device for a bush cutter according to claim 1 , wherein said reaction force receiving portion is configured to have an outer dimension larger than said insertion shaft portion in a direction orthogonal to the direction in which said axis extends. The movement restricting member is provided closer to the first shaft member than the reaction force receiving portion, and is configured such that one end thereof abuts on the first shaft member, and is positioned closer to the reaction force receiving portion than the reaction force receiving portion. further including a small diameter portion formed to have a small diameter;
3. The rotary force transmission device for a bush cutter according to claim 1 , wherein the biasing member has an outer dimension smaller than that of the reaction force receiving portion and is disposed on the outer circumference of the small diameter portion. The biasing member has one end in the direction in which the axis extends and contacts the reaction force receiving portion, and the other end in the direction in which the axis extends contacts the end face of the first shaft member. 4. The rotary force transmission device for a bush cutter according to any one of claims 1 to 3 , wherein: The rotary force transmission device for the brush cutter further includes a drum of the clutch drum,
The first shaft member further includes a drum fixing portion configured to be fixed to an opening formed in a wall portion extending along a direction intersecting the direction in which the axis of the drum extends. ,
The biasing member is configured such that one end in the direction in which the axis extends contacts the reaction force receiving portion and the other end in the direction in which the axis extends contacts the wall surface. Item 5. A rotary force transmission device for a bush cutter according to any one of Items 1 to 4 . a rotational force generator configured to generate a rotational force;
a cutting blade configured to transmit the rotational force generated by the rotational force generator through a coil spring;
A brush cutter comprising the torque transmission device according to any one of claims 1 to 5 .

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