JP7219686B2 - Support pole and work machine - Google Patents

Description

The technology disclosed in this specification relates to a support rod and a working machine.

Patent Literature 1 discloses a support rod. The support rod includes a pipe, a shaft, three bearings, a first spring, and a second spring. The pipe is stretchable in the longitudinal direction. The shaft extends longitudinally inside the pipe. The bearings move longitudinally relative to the pipe as the pipe expands and contracts to rotatably support the shaft. The first spring contacts one end of the bearing. The second spring contacts the other end of the bearing. The pipe has an outer pipe and an inner pipe. The outer pipe accommodates the bearing inside. The inner pipe is inserted through the outer pipe and is longitudinally movable with respect to the outer pipe. The three bearings are equally spaced in the longitudinal direction.

JP 2013-005729 A

In the above support rod, the three bearings suppress the vibration of the pipe caused by the rotation of the shaft. Each of the three bearings supports the shaft at one point, and the effect of suppressing the vibration of the pipe due to the rotation of the shaft is insufficient. This specification discloses a technique capable of suppressing vibration of a pipe accompanying rotation of a shaft.

This specification discloses a support rod. The support rod includes a pipe, a shaft, a first moving body, a first spring, and a second spring. The pipe is stretchable in the longitudinal direction. The shaft extends longitudinally inside the pipe. The first moving body moves longitudinally with respect to the pipe as the pipe expands and contracts. The first spring contacts one longitudinal end of the first moving body. The second spring contacts the other longitudinal end of the first moving body. The pipe has an outer pipe and an inner pipe. The outer pipe accommodates the first moving body inside. The inner pipe is inserted through the outer pipe and is longitudinally movable with respect to the outer pipe. The first moving body has at least two first bearings that rotatably support the shaft. The longitudinal distance between at least two first bearings adjacent to each other is always smaller than the respective longitudinal lengths of the first and second springs.

In the above configuration, since the first moving body has at least two first bearings, the first moving body supports the shaft at a plurality of points. In addition, since the first moving body moves in the longitudinal direction with respect to the pipe as the pipe expands and contracts, the first moving body remains at the post-movement position due to the at least two first bearings even if the pipe expands and contracts. support the shaft. For these reasons, compared with the case where the shaft is supported at one point, it is possible to suppress the vibration of the pipe due to the rotation of the shaft.

Fig. 3 is a side view of the working machine 2 of the embodiment in a contracted state; Fig. 3 is a cross-sectional view of the working machine 2 of the embodiment near the main unit 6; Fig. 3 is a cross-sectional view of the vicinity of the tool unit 8 of the working machine 2 of the embodiment; Fig. 3 is a cross-sectional view of the vicinity of the first moving body 62 of the working machine 2 of the embodiment; FIG. 3 is a cross-sectional view of the vicinity of a second moving body 64 of the working machine 2 of the embodiment; FIG. 10 is a cross-sectional view of the vicinity of the third moving body 66 of the working machine 2 of the embodiment; 4 is a cross-sectional view of the vicinity of the first moving body 62 with the working machine 2 of the embodiment extended. FIG.

In one or more embodiments, a work machine may include a pipe, a body unit, a tool unit, a shaft, and a gearbox. The main unit is provided at the rear end of the pipe and may include a prime mover. The tool unit is provided at the tip of the pipe and may include a tip tool. The shaft is located inside the pipe and may transmit the power of the prime mover to the bit. The gearbox may be arranged between the shaft and the bit. The speed increaser may make the number of rotations of the tip tool higher than the number of rotations of the shaft.

In the above configuration, even if the rotation speed of the tip tool is set high in order to secure the workability of the tip tool, the rotation speed of the shaft is lower than the rotation speed of the tip tool. Therefore, compared to the case where the number of rotations of the shaft is equal to or higher than the number of rotations of the tip tool, it is possible to suppress the vibration of the working machine caused by the rotation of the shaft. As a result, it is possible to suppress both the deterioration of the working ability due to the tip tool and the deterioration of the vibration of the working machine.

In one or more embodiments, the work machine may further include a speed reducer positioned between the shaft and the prime mover. The speed reducer may have a shaft rotation speed lower than that of the prime mover.

With the above configuration, the number of revolutions of the shaft can be reduced compared to a work machine in which no speed reducer is arranged between the shaft and the prime mover. Therefore, it is possible to suppress the vibration of the working machine due to the rotation of the shaft.

In one or more embodiments, the number of rotations of the prime mover may be higher than the number of rotations of the accessory tool.

With the above configuration, it is possible to obtain a torque larger than the output torque of the prime mover in the tip tool.

In one or more embodiments, the speed reducer may comprise a helical gear.

In the above configuration, tooth contact of the gear is distributed compared to spur gears. Therefore, it is possible to suppress the vibration of the working machine due to the torque fluctuation of the gear.

In one or more embodiments, the gearbox may comprise bevel gears.

With the above configuration, the rotation axis of the tip tool can be changed with respect to the rotation axis of the shaft.

In one or more embodiments, the prime mover may be a motor.

When the prime mover is an engine, the vibration of the engine itself is extremely large, so the vibration of the working machine is caused by the vibration of the engine itself, not the vibration accompanying the rotation of the shaft. On the other hand, when the prime mover is a motor, since the motor itself hardly vibrates, the vibration of the working machine is caused by the vibration accompanying the rotation of the shaft. In the above configuration, vibration of the working machine can be suppressed as compared with the case where the prime mover is an engine.

In one or more embodiments, the support rod may comprise a pipe, a shaft, a first mover, a first spring, and a second spring. The pipe may be longitudinally stretchable. The shaft may extend longitudinally inside the pipe. The first mover may move longitudinally relative to the pipe as the pipe expands and contracts. The first spring may contact one longitudinal end of the first moving body. The second spring may contact the other longitudinal end of the first moving body. The pipe may comprise an outer pipe and an inner pipe. The outer pipe may accommodate the first moving body inside. The inner pipe is inserted through the outer pipe and may be longitudinally movable with respect to the outer pipe. The first moving body may comprise at least two first bearings that rotatably support the shaft. The longitudinal distance between at least two first bearings adjacent to each other may always be smaller than the respective longitudinal lengths of the first spring and the second spring.

In the above configuration, since the first moving body has at least two first bearings, the first moving body supports the shaft at a plurality of points. In addition, since the first moving body moves in the longitudinal direction with respect to the pipe as the pipe expands and contracts, the first moving body remains at the post-movement position due to the at least two first bearings even if the pipe expands and contracts. support the shaft. For these reasons, compared with the case where the shaft is supported at one point, it is possible to suppress the vibration of the pipe due to the rotation of the shaft.

In one or more embodiments, the first moving body may further include a holding portion that holds a constant longitudinal distance between at least two adjacent first bearings.

In the above configuration, even if the pipe expands or contracts, the distance between at least two adjacent first bearings in the longitudinal direction is constant. Therefore, even when the length of the pipe changes due to expansion and contraction, it is possible to stably suppress the vibration of the pipe due to the rotation of the shaft.

In one or more embodiments, the first mover may further comprise a first support that supports the at least two first bearings and the retainer.

In the above configuration, at least two first bearings and the holding portion can be integrated by the first support portion.

In one or more embodiments, the support rod may further include a second moving body provided at one end of the inner pipe that is inserted into the outer pipe. The second moving body may have a second bearing that rotatably supports the shaft.

According to the inventor's studies, it has been found that vibration of the inner pipe is likely to occur at one end of the inner pipe as the shaft rotates. In the above configuration, the second bearing provided on the one end of the inner pipe can suppress the vibration of the pipe due to the rotation of the shaft.

In one or more embodiments, the second mover may further comprise a second support that supports the second bearing. The second support may be inserted through one end of the inner pipe.

With the above configuration, the second moving body can be provided at the one end of the inner pipe by a simple operation of inserting the second support portion into the one end of the inner pipe.

In one or more embodiments, an engaged portion may be formed at one end of the inner pipe. The second moving body may be arranged on the second supporting portion and may further include an engaging portion that engages with the engaged portion.

In the above configuration, when the second moving body is provided at one end of the inner pipe, the engaging portion engages with the engaged portion. Therefore, it is possible to prevent the second moving body from coming off the one end of the inner pipe.

In one or more embodiments, the first spring may have a similar configuration as the second spring.

In the above configuration, even if the pipe expands and contracts, the length of the first spring and the length of the second spring are the same. Therefore, it is possible to easily design the position of the first moving body in the longitudinal direction of the expandable pipe.

In one or more embodiments, the support rod may comprise at least two first movers.

In the above configuration, the vibration of the pipe caused by the rotation of the shaft can be further suppressed as compared with the case where the support rod is provided with one first moving body.

In one or more embodiments, a work machine may include a support rod, a body unit, and a tool unit. The body unit is provided at the rear end of the support rod and may include a prime mover. The tool unit is provided at the tip of the support rod and may include a tip tool. The support rod may comprise a pipe, a shaft, a first mover, a first spring, and a second spring. The pipe may be longitudinally stretchable. The shaft may extend longitudinally inside the pipe. The first mover may move longitudinally relative to the pipe as the pipe expands and contracts. The first spring may contact one longitudinal end of the first moving body. The second spring may contact the other longitudinal end of the first moving body. The pipe may comprise an outer pipe and an inner pipe. The outer pipe may accommodate the first moving body inside. The inner pipe is inserted through the outer pipe and may be longitudinally movable with respect to the outer pipe. The first moving body may comprise at least two first bearings that rotatably support the shaft. The longitudinal distance between at least two first bearings adjacent to each other may always be smaller than the respective longitudinal lengths of the first spring and the second spring.

In the above configuration, since the first moving body has at least two first bearings, the first moving body supports the shaft at a plurality of points. In addition, since the first moving body moves in the longitudinal direction with respect to the pipe as the pipe expands and contracts, the first moving body remains at the post-movement position due to the at least two first bearings even if the pipe expands and contracts. support the shaft. For these reasons, it is possible to suppress the vibration of the pipe due to the rotation of the shaft, as compared with the structure in which the shaft is supported at one point. As a result, vibration of the working machine can be suppressed.

(Example)
A working machine 2 according to an embodiment will be described with reference to FIGS. 1 to 7 . The working machine 2 is a pole saw and is used for pruning tall branches. As shown in FIG. 1 , the working machine 2 includes a support rod 4 , a body unit 6 and a tool unit 8 . The body unit 6 is provided at the rear end of the support rod 4 . A tool unit 8 is provided at the tip of the support rod 4 . In this embodiment, the longitudinal direction of the working machine 2 is called the front-rear direction, the direction perpendicular to the front-rear direction is called the left-right direction, and the direction perpendicular to the front-rear direction and the left-right direction is called the up-down direction.

As shown in FIG. 2, the body unit 6 includes a body pipe 10, a stopper 11, a body housing 12, a motor 14, a speed reducer 16, and a control board . The body pipe 10 extends in the front-rear direction. The body pipe 10 is fixed to the rear end of the support rod 4 via a stopper 11 .

The body housing 12 is fixed to the body pipe 10 . The body housing 12 includes a grip portion 22 , a housing portion 24 and a handle portion 26 . The grip part 22 is gripped by an operator. The grip portion 22 is positioned at the front portion of the main body housing 12 . The body pipe 10 is inserted through the inside of the grip portion 22 . A trigger lock 30 and a trigger 32 are arranged on the grip portion 22 . When the trigger lock 30 is not pushed in, the pushing operation of the trigger 32 is prohibited, and when the trigger lock 30 is pushed in, the pushing operation of the trigger 32 is permitted.

The housing portion 24 is arranged at the rear portion of the grip portion 22 . A handle portion 26 is arranged on the rear lower surface of the housing portion 24 . The handle portion 26 is held by the hand opposite to the hand holding the grip portion 22 by the operator. A battery B is detachably attached to the rear surface of the housing portion 24 . Battery B is, for example, a lithium ion battery.

The housing portion 24 houses the motor 14 , the speed reducer 16 and the control board 18 . The motor 14 is a prime mover, such as a brushless motor. A motor shaft 14a of the motor 14 extends in the front-rear direction. When the trigger 32 is pushed while the trigger lock 30 is pushed, the motor 14 is driven under the control of the control board 18 .

The speed reducer 16 is arranged between the motor shaft 14 a of the motor 14 and a shaft 60 to be described later, and transmits the rotation of the motor shaft 14 a to the shaft 60 . The reduction gear 16 includes a first reduction gear 36 and a second reduction gear 38 . The first reduction gear 36 and the second reduction gear 38 are helical gears. The first reduction gear 36 is connected to the front end of the motor shaft 14 a of the motor 14 . The second reduction gear 38 is connected to the rear end portion of the shaft 60 via the shaft receiving portion 40 . The second reduction gear 38 meshes with the first reduction gear 36 . The second reduction gear 38 is vertically aligned with the first reduction gear 36 . When the first reduction gear 36 rotates around the rotation axis extending in the front-rear direction, the second reduction gear 38 rotates around the rotation axis extending in the front-rear direction. The number of teeth of the first reduction gear 36 is smaller than the number of teeth of the second reduction gear 38 . The rotation speed of the second reduction gear 38 is lower than the rotation speed of the first reduction gear 36 . As a result, the rotation speed of the shaft 60 becomes lower than the rotation speed of the motor shaft 14 a of the motor 14 .

As shown in FIG. 3, the tool unit 8 includes a tool housing 42, a gearbox 44, a drive shaft 46, a sprocket 48, a guide bar 49, and a sprocket cover 50. A tool housing 42 houses a gearbox 44 .

Gearbox 44 is disposed between shaft 60 and sprocket 48 to transmit rotation of shaft 60 to sprocket 48 . The speed increasing gear 44 includes a first speed increasing gear 51 and a second speed increasing gear 52 . The first speed-up gear 51 and the second speed-up gear 52 are bevel gears. The first speed increasing gear 51 is connected to the front end portion of the shaft 60 via the shaft receiving portion 43 . The second speed increasing gear 52 is connected to the drive shaft 46 . The second speed increasing gear 52 meshes with the first speed increasing gear 51 . When the first speed increasing gear 51 rotates around the rotating shaft extending in the front-rear direction, the second speed increasing gear 52 rotates around the rotating shaft extending in the left-right direction. The number of teeth of the second speed increasing gear 52 is smaller than the number of teeth of the first speed increasing gear 51 . The rotational speed of the second speed increasing gear 52 is higher than the rotational speed of the first speed increasing gear 51 . As a result, the rotation speed of the drive shaft 46 becomes higher than the rotation speed of the shaft 60 . In addition, the gear ratio in the speed reducer 16 (that is, the ratio of the number of teeth of the second reduction gear 38 to the number of teeth of the first reduction gear 36) and the gear ratio in the speed increaser 44 (that is, the first speed up gear 51 ) is greater than one. As a result, the rotation speed of the drive shaft 46 is lower than the rotation speed of the motor shaft 14 a of the motor 14 .

The drive shaft 46 extends in the left-right direction. A left end portion of the drive shaft 46 extends to the outside of the tool housing 42 . A sprocket 48 is fitted near the left end of the drive shaft 46 . A sprocket 48 is located outside the tool housing 42 . As drive shaft 46 rotates, sprocket 48 rotates at the same rotational speed as drive shaft 46 .

A saw chain (not shown) is laid over the sprocket 48 and the guide bar 49 . Guide bar 49 is secured to the exterior of tool housing 42 by fasteners. The longitudinal direction of the guide bar 49 is the front-rear direction, and the lateral direction of the guide bar 49 is the vertical direction. As the sprocket 48 rotates, the saw chain travels along the circumference of the guide bar 49 . As a result, an object to be cut such as a branch is cut.

As shown in FIG. 3, the support rod 4 includes a pipe 54, a shaft 60, a plurality of (two in this embodiment) first moving bodies 62 (see FIG. 4), and a second moving body 64 (see FIG. 4). 5), a third moving body 66 (see FIG. 6), and a plurality of (three in this embodiment) springs 68 (see FIG. 4). The pipe 54 has an outer pipe 56 and an inner pipe 58 . The outer pipe 56 is a cylinder extending in the front-rear direction. A rear end portion of the outer pipe 56 is fixed to the main pipe 10 via a stopper 11 (see FIG. 2). The outer pipe 56 accommodates two first moving bodies 62 and a third moving body 66 inside. The inner pipe 58 is inserted through the outer pipe 56 from the rear end of the inner pipe 58 . The inner pipe 58 is a cylinder extending in the front-rear direction. The inner pipe 58 is fixed to the tool housing 42 via fasteners 59 . The outer diameter of the inner pipe 58 is smaller than the inner diameter of the outer pipe 56 .

The support rod 4 further includes a pipe holder 72, a stopper 74, a sleeve 76, and a retainer 78 (see FIG. 5). A rear portion 72a of the pipe holder 72 is fixed to the front end portion of the outer pipe 56 with a screw (not shown). A male threaded portion 82 is formed on the outer peripheral surface of the front portion 72 b of the pipe holder 72 . An inner peripheral surface of the front portion 72b of the pipe holder 72 is formed with an inclined portion 84 whose diameter decreases toward the rear.

Stopper 74 is cylindrical. A female screw portion 86 is formed on the inner peripheral surface of the stopper 74 . When the male threaded portion 82 is screwed into the female threaded portion 86 , the stopper 74 is fixed to the pipe holder 72 .

The sleeve 76 is a cylinder that is discontinued at one point in the circumferential direction. When the female threaded portion 86 is not screwed onto the male threaded portion 82 , the inner diameter of the sleeve 76 is larger than the outer diameter of the outer peripheral surface of the inner pipe 58 , and the sleeve 76 does not sandwich the inner pipe 58 . In this state, the inner pipe 58 can move forward and backward with respect to the outer pipe 56 . As a result, the pipe 54 can expand and contract. Thereby, the operator can adjust the length of the pipe 54 according to the working environment (for example, the height of the high branch to be pruned, etc.). When the male threaded portion 82 is screwed into the female threaded portion 86, the sleeve 76 contacts the inclined portion 84 of the pipe holder 72, and the opening of the sleeve 76 becomes narrower than in the initial state. As a result, the inner diameter of the sleeve 76 is reduced and the sleeve 76 clamps the inner pipe 58 . In this state, the inner pipe 58 cannot move forward and backward with respect to the outer pipe 56 . As a result, the pipe 54 cannot expand and contract. Thereby, the operator can fix the pipe 54 to a desired length.

As shown in FIG. 5, the retainer 78 is fitted to the outer peripheral surface of the inner pipe 58 in the vicinity of the rear end thereof. The retainer 78 extends around the outer peripheral surface of the inner pipe 58 in the circumferential direction. The diameter of the outer peripheral surface of the retainer 78 is larger than the diameter of the inner peripheral surface of the front portion 72 b of the pipe holder 72 . The retainer 78 abuts on the rear end of the front portion of the pipe holder 72 in the front-rear direction. This can prevent the inner pipe 58 from coming off the outer pipe 56 .

As shown in FIG. 4, the shaft 60 extends longitudinally inside the outer pipe 56 and the inner pipe 58 . Shaft 60 transmits the power of motor 14 to sprocket 48 . The shaft 60 can extend and contract in the front-rear direction. The shaft 60 is driven by the motor 14 to rotate around an axis extending in the front-rear direction.

The two first moving bodies 62 are arranged inside the outer pipe 56 . Although not shown, the two first moving bodies 62 are arranged between the second moving body 64 and the third moving body 66 in the longitudinal direction of the pipe 54 . The first moving body 62 includes a plurality of (two in this embodiment) first bearings 90 , first holders 92 and bushes 98 . The two first bearings 90 are arranged apart from each other in the front-rear direction. The two first bearings 90 rotatably support the shaft 60 via bushings 98 . In one first moving body 62 , the shaft 60 is supported at two points by two first bearings 90 . A bushing 98 is sandwiched between the first bearing 90 and the shaft 60 . Bushing 98 rotates as shaft 60 rotates.

The first holder 92 is made of resin material. The first holder 92 does not rotate even when the shaft 60 rotates. The first holder 92 has a holding portion 94 and a support portion 96 . The holding portion 94 is sandwiched between the two first bearings 90 . The holding portion 94 keeps the distance L1 between the two first bearings 90 constant in the front-rear direction. The support portion 96 supports the two first bearings 90 and the holding portion 94 . Specifically, the support portion 96 is formed integrally with the holding portion 94 . The support portion 96 sandwiches the first bearing 90 with the holding portion 94 . Thereby, the support portion 96 integrates the two first bearings 90 and the holding portion 94 .

As shown in FIG. 5, the second moving body 64 includes a second bearing 102, a second holder 104, and a bush 109. As shown in FIG. The second bearing 102 has a configuration similar to that of the first bearing 90 . The second bearing 102 rotatably supports the shaft 60 via a bush 109 . Bushing 109 is sandwiched between second bearing 102 and shaft 60 . Bushing 109 rotates as shaft 60 rotates.

The second holder 104 is made of resin material. The second holder 104 does not rotate even when the shaft 60 rotates. The second holder 104 includes a support portion 106 , an insertion portion 108 and an engaging portion 110 . The support portion 106 supports the second bearing 102 . Specifically, the support portion 106 sandwiches the second bearing 102 in the front-rear direction. The diameter of the outer peripheral surface of the support portion 106 is larger than the diameter of the inner peripheral surface of the inner pipe 58 . The support portion 106 abuts on the rear end portion of the inner pipe 58 in the front-rear direction. The insertion portion 108 extends forward from the front end portion of the support portion 106 . The insertion portion 108 is a cylinder slightly smaller in diameter than the inner peripheral surface of the inner pipe 58 . The engaging portion 110 protrudes outward from the outer peripheral surface of the insertion portion 108 . A rear end portion of the inner pipe 58 is formed with an engaged portion 112 penetrating through the inner pipe 58 in the thickness direction. When the inserting portion 108 is inserted through the rear end portion of the inner pipe 58 , the engaging portion 110 is engaged with the engaged portion 112 . Thereby, the second holder 104 , that is, the second moving body 64 is fixed to the rear end portion of the inner pipe 58 .

As shown in FIG. 6 , the third moving body 66 has a third bearing 116 , a third holder 118 and a bushing 126 . The third bearing 116 has a configuration similar to that of the first bearing 90 . Third bearing 116 rotatably supports shaft 60 via bush 126 . Bushing 126 is sandwiched between third bearing 116 and shaft 60 . Bushing 126 rotates as shaft 60 rotates.

The third holder 118 is made of resin material. The third holder 118 does not rotate even when the shaft 60 rotates. The third holder 118 includes a support portion 120 , an insertion portion 122 and a stepped portion 124 . The support portion 120 sandwiches the third bearing 116 in the front-rear direction. The support portion 120 is inserted through the rear end portion of the outer pipe 56 . A rear end portion of the support portion 120 is in contact with the main pipe 10 . The insertion portion 122 extends rearward from the rear end portion of the support portion 120 . The body pipe 10 is inserted through the insertion portion 122 . The insertion portion 122 is inserted through the rear end portion of the outer pipe 56 . The insertion portion 122 is fixed to the main pipe 10 by a stopper 128 . The stepped portion 124 protrudes outward from the rear portion of the outer peripheral surface of the insertion portion 122 . The stepped portion 124 is sandwiched between the rear end portion of the outer pipe 56 and the stopper 11 in the front-rear direction. With these, the third holder 118 , that is, the third moving body 66 is fixed to the rear end portion of the outer pipe 56 .

Each of the three springs 68 has a similar configuration (eg, same spring coefficient and same length). One spring 68 is in contact with the rear end of the second moving body 64 and the front end of the first moving body 62 . Another spring 68 abuts the rear end of the first moving body 62 and the front end of the other first moving body 62 . The remaining one spring 68 is in contact with the rear end of the other first moving body 62 and the front end of the third moving body 66 . Springs 68 equalize the distance between the second moving body 64 and the first moving body 62, the distance between the adjacent first moving bodies 62, and the distance between the first moving body 62 and the third moving body 66 in the longitudinal direction. held.

Next, behaviors of the two first moving bodies 62, the second moving body 64, the third moving body 66 and the three springs 68 when the pipe 54 expands and contracts will be described. As shown in FIG. 4, when the pipe 54 is in its most contracted state, the three springs 68 are most contracted. When the pipe 54 is in the most contracted state, the distance L2 between the second moving body 64 and the first moving body 62, the distance L2 between the adjacent first moving bodies 62, and the first moving body 62 are and the third moving body 66 are kept the same by the spring 68 . Vibration of the pipe 54 due to the rotation of the shaft 60 is suppressed compared to the case where the two first moving bodies 62, the second moving bodies 64, and the third moving bodies 66 are not arranged at regular intervals. Note that the interval L2 is longer than the interval L1 between the two first bearings 90 in the front-rear direction, and is the same as the length of the spring 68 in the most contracted state.

When the inner pipe 58 is moved forward with respect to the outer pipe 56 to extend the pipe 54 to the maximum length, the second movable body 64 moves forward together with the movement of the inner pipe 58 . On the other hand, the third moving body 66 is fixed to the rear end of the outer pipe 56 and does not move forward. As a result, the three contracted springs 68 are expanded, and the two first moving bodies 62 arranged between the second moving body 64 and the third moving body 66 are moved to the inner pipe 58. It moves inside the outer pipe 56 in the moving direction. Since the three springs 68 have the same configuration, the lengths of the three springs 68 after extension are the same. Therefore, as shown in FIG. 7, when the pipe 54 is extended to its maximum length, the distance L3 between the second moving body 64 and the first moving body 62 and the distance L3 between the first moving body 62 and the adjacent first moving body 62 in the front-rear direction. , and the distance L3 between the first moving body 62 and the third moving body 66 are kept the same by the springs 68 . Even if the shaft 60 rotates while the pipe 54 is extended to its maximum length, the two first moving bodies 62, the second moving bodies 64, and the third moving bodies 66 are not arranged at regular intervals. , the vibration of the pipe 54 accompanying the rotation of the shaft 60 is suppressed. Note that the distance L3 is longer than both the distances L1 and L2 and is the same as the length of the spring 68 in its most extended state.

In this embodiment, the work machine 2 includes a pipe 54 , a body unit 6 , a tool unit 8 , a shaft 60 and a gearbox 44 . As shown in FIG. 2 , the main unit 6 is provided at the rear end of the pipe 54 and has the motor 14 . As shown in FIG. 3 , the tool unit 8 is provided at the tip of the pipe 54 and has a sprocket 48 . A shaft 60 is located inside the pipe 54 and transmits the power of the motor 14 to the sprocket 48 . Gearbox 44 is arranged between shaft 60 and sprocket 48 . The gearbox 44 makes the rotation speed of the sprocket 48 higher than the rotation speed of the shaft 60 . In the above configuration, even if the rotation speed of the sprocket 48 is set high in order to ensure the cutting ability of the saw chain that rotates due to the rotation of the sprocket 48, the rotation speed of the shaft 60 is equal to the rotation speed of the sprocket 48. lower than the number Therefore, compared to the case where the rotation speed of shaft 60 is equal to or higher than the rotation speed of sprocket 48, vibration of work implement 2 caused by rotation of shaft 60 can be suppressed. As a result, it is possible to suppress both the deterioration of the cutting ability of the saw chain that rotates due to the rotation of the sprocket 48 and the deterioration of the vibration of the work implement 2 .

The work implement 2 further includes a speed reducer 16 arranged between the shaft 60 and the motor 14 . The speed reducer 16 makes the rotation speed of the shaft 60 lower than the rotation speed of the motor 14 . With the above configuration, the rotation speed of shaft 60 can be reduced compared to work machine 2 in which reduction gear 16 is not arranged between shaft 60 and motor 14 . Therefore, vibration of work implement 2 accompanying rotation of shaft 60 can be suppressed.

Also, the rotation speed of the motor 14 is higher than the rotation speed of the sprocket 48 . With the above configuration, the sprocket 48 can obtain torque larger than the output torque of the motor 14 .

Also, the speed reducer 16 has a helical gear. In the above configuration, tooth contact of the gear is distributed compared to spur gears. Therefore, it is possible to suppress the vibration of the work implement 2 due to the torque fluctuation of the gear.

Further, the gearbox 44 has a bevel gear. In the above configuration, the rotation axis of sprocket 48 can be changed with respect to the rotation axis of shaft 60 .

Also, the prime mover is the motor 14 . If the prime mover is an engine, the vibration of the engine itself is extremely large. On the other hand, when the prime mover is the motor 14 , the motor 14 hardly vibrates. In the above configuration, vibration of work implement 2 can be suppressed as compared with the case where the prime mover is an engine.

In this embodiment, the support rod 4 comprises a pipe 54, a shaft 60, a first moving body 62 and two springs 68. The pipe 54 can be extended and contracted in the front-rear direction. The shaft 60 extends longitudinally inside the pipe 54 . The first moving body 62 moves back and forth with respect to the pipe 54 when the pipe 54 expands and contracts. One spring 68 is in contact with one end of the first moving body 62 in the front-rear direction. Another spring 68 is in contact with the other end of the first moving body 62 in the front-rear direction. The pipe 54 has an outer pipe 56 and an inner pipe 58 . The outer pipe 56 accommodates the first moving body 62 inside. The inner pipe 58 is inserted through the outer pipe 56 and is movable in the front-rear direction with respect to the outer pipe 56 . As shown in FIG. 4 , the first moving body 62 has two first bearings 90 that rotatably support the shaft 60 . The distance L1 in the front-rear direction between the two first bearings 90 adjacent to each other is always smaller than the length of the spring 68 in the front-rear direction. In the above configuration, the first moving body 62 has two first bearings 90, so the first moving body 62 supports the shaft 60 at two points. In addition, since the first moving body 62 moves in the longitudinal direction with respect to the pipe 54 as the pipe 54 expands and contracts, the first moving body 62 is supported by the two first bearings 90 even if the pipe 54 expands and contracts. The shaft 60 is supported at the position after movement. For these reasons, compared to the case where the shaft 60 is supported at one point, vibration of the pipe 54 accompanying the rotation of the shaft 60 can be suppressed.

In addition, as shown in FIG. 4, the first moving body 62 further includes a holding portion 94 that holds a constant distance L1 between the two first bearings 90 adjacent to each other in the longitudinal direction. In the above configuration, even if the pipe 54 expands and contracts, the distance L1 in the front-rear direction between the two first bearings 90 adjacent to each other is constant. Therefore, even when the length of the pipe 54 changes due to expansion and contraction, the vibration of the pipe 54 due to the rotation of the shaft 60 can be stably suppressed.

Moreover, as shown in FIG. 4, the first moving body 62 further includes a support portion 96 that supports the two first bearings 90 and the holding portion 94 . In the above configuration, the two first bearings 90 and the holding portion 94 can be integrated by the support portion 96 .

Further, as shown in FIG. 5, the support rod 4 further includes a second moving body 64 provided at one end of the inner pipe 58 on the side where the outer pipe 56 is inserted. The second moving body 64 has a second bearing 102 that rotatably supports the shaft 60 . According to the inventor's study, it has been found that the pipe 54 is likely to vibrate at one end of the inner pipe 58 as the shaft 60 rotates. In the above configuration, the vibration of the pipe 54 caused by the rotation of the shaft 60 can be suppressed by the second bearing 102 of the second moving body 64 provided at one end of the inner pipe 58 .

Moreover, as shown in FIG. 5, the second moving body 64 further includes a support portion 106 that supports the second bearing 102 . The support portion 106 is inserted through one end of the inner pipe 58 . In the above configuration, the second moving body 64 can be provided at one end of the inner pipe 58 by a simple operation of inserting the support portion 106 through the one end of the inner pipe 58 .

Further, as shown in FIG. 5, an engaged portion 112 is formed at one end of the inner pipe 58 . The second moving body 64 is arranged on the support portion 106 and further includes an engaging portion 110 that engages with the engaged portion 112 . When the second moving body 64 is provided at one end of the inner pipe 58 , the engaging portion 110 engages with the engaged portion 112 . Therefore, it is possible to prevent the second moving body 64 from coming off the one end of the inner pipe 58 .

Also, the two springs 68 have the same configuration. In the above configuration, even if the pipe 54 expands and contracts, the two springs 68 have the same length. Therefore, the position of the first movable body 62 in the front-rear direction can be easily designed in the expandable pipe 54 .

Moreover, as shown in FIG. 4, the support rod 4 has two first moving bodies 62 . In the above configuration, vibration of the pipe 54 caused by the rotation of the shaft 60 can be further suppressed as compared with the case where the support rod 4 is provided with one first moving body 62 .

Moreover, as shown in FIG. 1 , the work machine 2 includes a support rod 4 , a body unit 6 and a tool unit 8 . The body unit 6 is provided at the rear end of the support rod 4 and has a motor 14 . The tool unit 8 is provided at the tip of the support rod 4 and has a sprocket 48 . The support rod 4 has a pipe 54 , a shaft 60 , a first moving body 62 and two springs 68 . The pipe 54 can be extended and contracted in the front-rear direction. The shaft 60 extends longitudinally inside the pipe 54 . The first moving body 62 moves back and forth with respect to the pipe 54 when the pipe 54 expands and contracts. One spring 68 is in contact with one end of the first moving body 62 in the front-rear direction. Another spring 68 is in contact with the other end of the first moving body 62 in the front-rear direction. The pipe 54 has an outer pipe 56 and an inner pipe 58 . The outer pipe 56 accommodates the first moving body 62 inside. The inner pipe 58 is inserted through the outer pipe 56 and is movable in the front-rear direction with respect to the outer pipe 56 . As shown in FIG. 4 , the first moving body 62 has two first bearings 90 that rotatably support the shaft 60 . The distance L1 in the front-rear direction between the two first bearings 90 adjacent to each other is always smaller than the length of the spring 68 in the front-rear direction. In the above configuration, the first moving body 62 has two first bearings 90, so the first moving body 62 supports the shaft 60 at two points. In addition, since the first moving body 62 moves in the longitudinal direction with respect to the pipe 54 as the pipe 54 expands and contracts, the first moving body 62 is supported by the two first bearings 90 even if the pipe 54 expands and contracts. The shaft 60 is supported at the position after movement. For these reasons, compared to the case where the shaft 60 is supported at one point, vibration of the pipe 54 accompanying the rotation of the shaft 60 can be suppressed. As a result, vibration of the work implement 2 can be suppressed.

The first holder 92, the second holder 104, and the third holder 118 are made of resin material. In the above configuration, even if the holders 92, 104, 118 come into contact with the pipe 54 as the shaft 60 rotates, the holders 92, 104, 118 do not contact the pipe 54 as compared to the case where the holders 92, 104, 118 are made of a metal material. The impact caused by contact is small. Therefore, vibration of the pipe 54 accompanying rotation of the shaft 60 can be suppressed.

(correspondence relationship)
The sprocket 48 is an example of the "tip tool", and the rotation speed of the sprocket 48 is an example of the "rotation speed of the tip tool". The spring 68 is an example of a "first spring" and a "second spring". The support portion 96 is an example of a "first support portion", and the support portion 106 is an example of a "second support portion". The front-rear direction is an example of the "longitudinal direction."

Although specific examples of the present invention have been described in detail above, these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and changes of the specific examples illustrated above.

The number of rotations of the drive shaft 46 according to one embodiment may be higher than the number of rotations of the motor shaft 14 a of the motor 14 .

A gear included in the speed reducer 16 according to one embodiment is not limited to a helical gear. The speed reducer 16 may include, for example, a bevel gear or a spur gear.

The gears included in the gearbox 44 according to one embodiment are not limited to bevel gears. The gearbox 44 may include, for example, a helical gear or a spur gear.

The body unit 6 according to one embodiment may have an engine instead of the motor 14 .

In the working machine 2 according to one embodiment, power may be supplied by a power cord instead of the battery B.

In one embodiment, intermediate springs may be arranged between the first bearings 90 adjacent to each other in place of the retainers 94 . The intermediate spring may be a spring that is less stretchable than the spring 68 (that is, has a higher spring constant). In this case, the length of the intermediate spring is always smaller than the length of the spring 68 even if the pipe 54 expands and contracts.

The second moving body 64 according to one embodiment may be engaged with the rear end of the inner pipe 58 without being inserted therethrough.

The engaged portion may be formed in the support portion 106 of the second moving body 64 according to one embodiment, and the engaging portion may be formed in the inner pipe 58 .

Each of the three springs 68 according to one embodiment may have a different configuration. For example, each of the three springs 68 may have different spring constants and different lengths.

The first moving body 62 according to one embodiment may have three or more first bearings 90 .

The support rod 4 according to one embodiment may have one first moving body 62 or may have three or more first moving bodies 62 .

The work machine 2 according to one embodiment may be, for example, a pole hedge trimmer, a brush cutter, or a palm tree cutter.

The pipe 54 according to one embodiment may be a flexible pipe.

The first holder 92, the second holder 104, and the third holder 118 according to one embodiment may be made of a metallic material.

The technical elements described in this specification or in the drawings exhibit technical usefulness alone or in various combinations, and are not limited to the combinations described in the claims as of the filing. In addition, the techniques illustrated in this specification or drawings can achieve a plurality of purposes at the same time, and achieving one of them has technical utility in itself.

2 : Working machine 4 : Support rod 6 : Main unit 8 : Tool unit 14 : Motor 16 : Reduction gear 36 : First reduction gear 38 : Second reduction gear 44 : Speed increaser 46 : Drive shaft 48 : Sprocket 51 : Second 1 speed increasing gear 52 : second speed increasing gear 54 : pipe 56 : outer pipe 58 : inner pipe 60 : shaft 62 : first moving body 64 : second moving body 66 : third moving body 68 : spring 90 : first Bearing 92: first holder 94: holding portions 96, 106, 120: support portion 102: second bearing 104: second holders 108, 122: insertion portion 110: engaging portion 112: engaged portion 116: third bearing 118: Third holder 124: Stepped portion

Claims (9)

a support rod,
a longitudinally expandable pipe;
a shaft extending longitudinally within the pipe;
a first moving body that moves in the longitudinal direction with respect to the pipe when the pipe expands and contracts;
a first spring contacting one longitudinal end of the first moving body;
a second spring contacting the other end in the longitudinal direction of the first moving body,
The pipe is
an outer pipe that accommodates the first moving body therein;
an inner pipe inserted through the outer pipe and movable in the longitudinal direction with respect to the outer pipe;
the first moving body includes at least two first bearings that rotatably support the shaft;
The support rod, wherein the longitudinal distance between the at least two first bearings adjacent to each other is always smaller than the respective longitudinal lengths of the first spring and the second spring. 2. The support rod according to claim 1, wherein said first moving body further comprises a holding portion that holds said at least two adjacent first bearings at a constant distance in said longitudinal direction. 3. The support rod according to claim 2, wherein said first moving body further comprises a first support portion that supports said at least two first bearings and said holding portion. further comprising a second moving body provided at one end of the inner pipe on the side where the outer pipe is inserted,
4. The support rod according to any one of claims 1 to 3, wherein said second moving body comprises a second bearing that rotatably supports said shaft. The second moving body further includes a second support that supports the second bearing,
5. The support rod according to claim 4, wherein said second support portion is inserted through said one end of said inner pipe. An engaged portion is formed at the one end of the inner pipe,
6. The support rod according to claim 5, wherein said second moving body is disposed on said second support portion, and further includes an engaging portion that engages said engaged portion. The support rod according to any one of claims 1 to 6, wherein said first spring has the same configuration as said second spring. 8. The support pole according to any one of claims 1 to 7, comprising at least two of said first moving bodies. a working machine,
a support rod;
a body unit provided at the rear end of the support rod and provided with a prime mover;
a tool unit provided at the tip of the support rod and having a tip tool,
The support rod is
a longitudinally expandable pipe;
a shaft extending longitudinally within the pipe;
a first moving body that moves in the longitudinal direction with respect to the pipe when the pipe expands and contracts;
a first spring contacting one longitudinal end of the first moving body;
a second spring contacting the other end in the longitudinal direction of the first moving body,
The pipe is
an outer pipe that accommodates the first moving body therein;
an inner pipe inserted through the outer pipe and movable in the longitudinal direction with respect to the outer pipe,
the first moving body includes at least two first bearings that rotatably support the shaft;
The working machine, wherein the distance between the at least two adjacent first bearings in the longitudinal direction is always smaller than the lengths of the first spring and the second spring in the longitudinal direction.

Images