JP5173078B2 - Brush cutter with removable battery pack - Google Patents

Description

  The present invention relates to a brush cutter used for a weeding operation such as weeds. In particular, the present invention relates to a brush cutter to which a battery pack can be attached and detached.

  Patent document 1 discloses a brush cutter. The brush cutter includes an operating rod, a cutting blade unit provided at the front end of the operating rod, a main unit provided at the rear end of the operating rod, and a transmission shaft provided inside the operating rod. ing. The cutting blade unit can rotatably support the cutting blade. The main unit has a built-in motor for driving the cutting blade. The transmission shaft extends from the main body unit to the cutting blade unit, and transmits the output torque of the motor from the main body unit to the cutting blade unit.

  The main body unit is formed with a battery pack mounting portion for slidably receiving the battery pack, and power is supplied to the motor from the battery pack mounted on the battery pack mounting portion. The battery pack mounting part is provided on the lower surface of the main unit, and is configured such that the sliding direction of the battery pack in the battery pack mounting part is parallel to the central axis of the operating rod.

JP 2006-31828 A

A user of a brush cutter often holds an operating rod when attaching or detaching a battery pack to or from a main unit. However, in the conventional brush cutter, the sliding direction of the battery pack at the battery pack mounting part is parallel to the central axis of the operating rod, and the direction in which the user applies force to the operating rod and the battery pack is It coincides with the axial direction of the cocoon. For this reason, when the user applies a force to attach or detach the battery pack, the hand holding the operating rod may slide along the operating rod. In particular, since the brush cutter is mainly used outdoors, dust and moisture are often attached to the operation rod. In this case, the hand holding the operating rod becomes more slippery, and it may take much time to attach and detach the battery pack.
In view of the above-described phenomenon, the present invention provides a brush cutter that can easily attach and detach a battery pack.

A brush cutter embodied by the present invention includes an operating rod, a cutting blade unit, a main body unit, and a motor. The cutting blade unit is provided at the front end of the operating rod and rotatably supports the cutting blade. The main unit is provided at the rear end of the operation rod. The motor drives the cutting blade. The brush cutter further includes a handle gripped by the user and a switch for rotating the motor. The handle is provided at an intermediate position of the operating rod. The switch is provided on the handle.

A battery pack mounting part is formed in the main unit. The battery pack mounting portion slidably receives a battery pack that supplies power to the motor. In this brush cutter, the sliding direction of the battery pack at the battery pack mounting portion forms an angle with respect to the central axis of the operating rod. That is, the sliding direction of the battery pack in the battery pack mounting portion is not parallel to the axial direction of the operating rod.
According to this configuration, when the user attaches / detaches the battery pack while holding the operating rod, the direction in which the user applies force to the operating rod and the battery pack does not coincide with the axial direction of the operating rod. For this reason, the hand holding the operating rod is difficult to slip along the operating rod. The user can easily attach and detach the battery pack.

  The sliding direction of the battery pack in the battery pack mounting portion is more preferable as it forms a larger angle with respect to the central axis of the operation rod. In particular, when the sliding direction of the battery pack in the battery pack mounting portion is at an angle of 45 degrees or more with respect to the central axis of the operating rod, the hand holding the operating rod is significantly prevented from slipping. be able to. Furthermore, if the sliding direction of the battery pack in the battery pack mounting portion is substantially orthogonal to the central axis of the operating rod, it is possible to more reliably prevent the hand holding the operating rod from slipping.

In the brush cutter, when the operating rod is provided at the front part of the main unit, the battery pack mounting part is preferably provided at the rear part of the main unit. That is, it is preferable that the operation unit and the battery pack mounting portion are provided on the main unit so as to be located on opposite sides.
According to this configuration, when the user attaches and detaches the battery pack while holding the operating rod, the brush cutter is significantly prevented from rotating about the operating rod as the central axis. The user can easily apply force to the operation rod and the battery pack, and can easily attach and detach the battery pack.

In the brush cutter, when the rotation axis of the cutting blade and the central axis of the operating rod are positioned in the vertical plane, it is preferable that the sliding direction of the battery pack in the battery pack mounting portion is parallel to the vertical plane. .
According to this configuration, when the user attaches / detaches the battery pack while holding the operating rod, the posture of the brush cutter is not easily lost, and the battery pack can be attached / detached more easily.

In the above brush cutter, when the rotation axis of the cutting blade and the central axis of the operating rod are positioned in the vertical plane, and the central axis of the operating rod is positioned in the horizontal plane, the battery pack is attached to the battery pack mounting portion. It is preferable that the sliding direction at the time faces downward and the sliding direction at the time of removing the battery pack at the battery pack mounting portion faces upward.
When attaching and detaching the battery pack to and from the main unit, the posture of the brush cutter can be stabilized if the main unit is placed on the ground. At this time, if the sliding direction when the battery pack is attached in the battery pack mounting portion is facing downward, and the sliding direction when the battery pack is detached in the battery pack mounting portion is facing upward, the battery pack and the grip are held. Hands that do not interfere with the ground.

  According to the present invention, a brush cutter capable of easily attaching and detaching a battery pack is realized.

The figure which shows the external appearance of the brush cutter of an Example. Sectional drawing which shows the structure of a main body unit. III-III sectional view taken on the line in FIG. IV-IV sectional view taken on the line in FIG. The figure which shows the sliding direction of a battery pack. The figure which shows the fixation structure of the operating rod in a main body unit. Sectional drawing which shows the structure of a cutting blade unit. The figure which shows the modification of a main body unit.

First, preferred forms for carrying out the present invention will be listed.
(Mode 1) The operating rod has a hollow shape (pipe shape) and preferably extends linearly.
(Mode 2) The operating rod is preferably provided with a handle for the user to hold. In this case, the handle preferably has a pair of left handle and right handle.
(Mode 3) When the operating rod is provided at the front of the main unit and the battery pack mounting portion is formed at the rear of the main unit, the battery pack mounting portion is positioned on an extension line of the central axis of the operating rod. It is preferable. According to this configuration, when the user attaches / detaches the battery pack while holding the operating rod, it is possible to more effectively prevent the brush cutter from rotating about the operating rod.
(Mode 4) The torque transmission path from the motor to the cutting blade is adjacent to the driving side connecting shaft connected to the motor side, and is adjacent to the driving side connecting shaft in the axial direction and connected to the cutting blade side. Preferably, a driven side connecting shaft and a coil spring wound around both the driving side connecting shaft and the driven side connecting shaft are provided. In this case, it is preferable that the winding direction of the coil spring from the drive side connection shaft to the driven side connection shaft is the same direction as the rotation direction of the drive side connection shaft. According to this configuration, it is possible to limit the torque transmitted from the motor to the cutting blade when the motor is started or when an excessive external force is applied to the cutting blade.
(Embodiment 5) It is preferable that the main unit has a grounding surface that comes into contact with the ground when the brush cutter is placed on the ground. In this case, the grounding surface is preferably positioned below the battery pack attached to the battery pack mounting portion. According to such a configuration, when the battery pack is attached / detached with the brush cutter placed on the ground, the battery pack and the user's hand holding the battery pack do not interfere with the ground.

Embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows the appearance of the brush cutter 10 of this embodiment. The brush cutter 10 is an electric tool used for a mowing work such as weeds.
As shown in FIG. 1, the brush cutter 10 includes an operating rod 30, a cutting blade unit 20 provided at the front end 30 a of the operating rod 30, and a main body unit 40 provided at the rear end 30 b of the operating rod 30. I have. The operating rod 30 has a hollow pipe shape and extends linearly. The cutting blade 12 is rotatably attached to the cutting blade unit 20. The main unit 40 accommodates a motor 46 (see FIG. 2) for driving the cutting blade 12. In addition, a battery pack 70 that supplies power to the motor 46 is detachably attached to the main unit 40. A transmission shaft 32 is rotatably accommodated in the operation rod 30. The transmission shaft 32 extends from the main body unit 40 to the cutting blade unit 20, and transmits the output torque of the motor 46 from the main body unit 40 to the cutting blade unit 20.

The operation rod 30 is provided with a handle 34 for a user to hold. The handle 34 includes a right handle 34a and a left handle 34b. A trigger-type start switch 33 is provided on the right handle 34a. The start switch 33 is electrically connected to the main unit 40 by an electric cord 36. The electric cord 36 is routed from the main unit 40 to the right handle 34a along the operating rod 30. When the start switch 33 is turned on, the motor 46 of the main unit 40 rotates. When the start switch 33 is turned off, the motor 46 of the main unit 40 stops.
The main unit 40 is provided with a stand 66. The stand 66 is provided so as to protrude from the main unit 40. The stand 66 supports the brush cutter 10 by contacting the ground when the brush cutter 10 is placed on the ground.

  The configuration of the main unit 40 will be described with reference to FIGS. 2, 3, and 4. FIG. 2 is a cross-sectional view showing the configuration of the main unit 40. The cross-sectional view shown in FIG. 2 shows a cross section of the cutting plane including the rotation axis Y (see FIG. 7) of the cutting blade 12 and the central axis X of the operating rod 30. FIG. 3 shows a cross-sectional view taken along line III-III in FIG. FIG. 4 shows a cross-sectional view taken along line IV-IV in FIG. Here, the central axis X of the operating rod 30 is also the rotational axis X of the transmission shaft 32.

  As shown in FIG. 2, the main body unit 40 includes a main body housing 42. A rear end 30 b of the operation rod 30 is fixed to the front portion 40 a of the main unit 40. A battery pack mounting portion 64 to which the battery pack 70 is attached and detached is provided on the rear portion 40b of the main body unit 40. The above-mentioned stand 66 is detachably bolted to the lower part of the main body housing 42. A ground contact surface 66 a for abutting against the ground or the like is formed at the tip of the stand 66. The electric cord 36 described above extends from the inside of the main body housing 42 to the outside, and is routed to the operation rod 30 beyond the stand 66.

As shown in FIGS. 3 and 4, the stand 66 is formed with a cord passage portion 68 for allowing the electric cord 36 to pass therethrough. The cord passage portion 68 has a notch shape extending from the periphery of the stand 66. The notch-shaped cord passage portion 68 extends from the substantial center of the ground contact surface 66 a of the stand 66 toward the main unit 40. The notch-shaped cord passage portion 68 has a width that decreases from the ground contact surface 66 a of the stand 66 toward the main body unit 40.
When the cord passage portion 68 is formed in the stand 66, it is possible to prevent the electric cord 36 from being sandwiched between the ground surface 66a of the stand 66 and the ground when the brush cutter 10 is placed on the ground. The shape of the cord passage portion 68 may be a notch shape as in the present embodiment, or may be a hole shape that penetrates the stand 66. However, if the cord passage portion 68 has a notch shape, the electric cord 36 can be easily placed in the cord passage portion 68 at the time of manufacturing the brush cutter 10 or at the time of reassembly after repair. In particular, when the width of the cord passage portion 68 increases toward the opening side, the operation of arranging the electric cord 36 on the cord passage portion 68 becomes easier. Further, when the notch-shaped cord passage portion 68 extends from the ground contact surface 66a of the stand 66 toward the main body unit 40, the strength reduction of the stand 66 due to the formation of the cord passage portion 68 can be suppressed.

  As shown in FIGS. 2 and 4, the main body housing 42 includes a motor 46 for driving the cutting blade 12, a first gear 50 fixed to the output shaft 48 of the motor 46 so as not to be relatively rotatable, and a first gear 50. A second gear 52 engaged with the first gear 50 is provided. The rear end 32b of the transmission shaft 32 is fixed to the second gear 52 through a connecting member 54 so as not to be relatively rotatable. The output torque of the motor 46 is transmitted to the transmission shaft 32 via the first gear 50 and the second gear 52. Here, the second gear 52 is larger than the first gear 50, and the number of teeth of the second gear 52 is larger than the number of teeth of the first gear 50. Thereby, the output torque of the motor 46 is amplified between the first gear 50 and the second gear 52. That is, the first gear 50 and the second gear 52 constitute a first reduction mechanism that amplifies the output torque of the motor 46 between the motor 46 and the transmission shaft 32. A cooling fan 49 is provided on the output shaft 48 of the motor 46.

  As shown in FIG. 4, the rotation axis M of the motor 46 is positioned below the rotation axis X of the transmission shaft 32. More precisely, the rotation of the motor 46 is performed when the rotation axis Y of the cutting blade 12 and the rotation axis X of the transmission shaft 32 are positioned in the vertical plane and the rotation axis X of the transmission shaft 32 is positioned in the horizontal plane. The axis M is located vertically below the rotation axis X of the transmission shaft 32. According to this configuration, when the user grips the handle 34 and performs the brushing work, the balance of the brush cutter 10 is easily stabilized. The rotation axis M of the motor 46 may be positioned above the rotation axis X of the transmission shaft 32. Even with this configuration, the balance of the brush cutter 10 is relatively stable.

  Next, with reference to FIG. 2 and FIG. 5, an attachment structure of the battery pack 70 in the main body unit 40 will be described. As shown in FIG. 2, a battery pack mounting portion 64 is formed on the rear portion 40 b of the main unit 40. The battery pack mounting part 64 has a structure in which the battery pack 70 can be attached and detached. As shown in FIG. 5, the battery pack mounting portion 64 receives the battery pack 70 so as to be slidable. Arrows Z <b> 1 and Z <b> 2 in FIG. 5 indicate the sliding direction of the battery pack 70 in the battery pack mounting portion 64. The sliding direction of the battery pack 70 in the battery pack mounting portion 64 is substantially orthogonal to the central axis X of the operation rod 30. A downward arrow Z1 indicates a sliding direction when the battery pack 70 is attached, and an upward arrow Z2 indicates a sliding direction when the battery pack 70 is removed. Thus, the sliding direction when the battery pack 70 is attached to the battery pack mounting portion 64 faces downward, and the sliding direction when the battery pack 70 is removed from the battery pack mounting portion 64 faces upward. To be precise, when the rotation axis Y of the cutting blade 12 and the central axis X of the operating rod 30 are positioned in the vertical plane, and the central axis X of the operating rod 30 is positioned in the horizontal plane, the battery pack mounting portion 64 is configured such that the sliding direction when the battery pack 70 is attached faces downward in the vertical direction, and the sliding direction when the battery pack 70 is detached in the battery pack mounting portion 64 faces vertically upward.

As described above, in the brush cutter 10 of the present embodiment, the sliding direction (Z1, Z2) of the battery pack 70 in the battery pack mounting portion 64 is not parallel to the central axis X of the operating rod 30 and the operating rod 30 An angle is formed with respect to the central axis X. According to this configuration, when the user attaches / detaches the battery pack 70 while holding the operating rod 30, the hand holding the operating rod 30 is difficult to slip, and it is easy to apply force to the operating rod 30 and the battery pack 70. Thereby, the battery pack 70 can be easily attached and detached. Here, the sliding direction (Z1, Z2) of the battery pack 70 does not necessarily need to be orthogonal to the central axis X of the operating rod 30. However, it is preferable that the angle formed by the slide direction (Z1, Z2) of the battery pack 70 and the central axis X of the operation rod 30 is as large as possible, and it has been confirmed that a remarkable effect can be obtained particularly when the angle is 45 ° or more.
In the brush cutter 10 of the present embodiment, the sliding direction when the battery pack 70 is attached to the battery pack mounting portion 64 faces downward, and the sliding direction when the battery pack 70 is removed from the battery pack mounting portion 64 faces upward. It is configured as follows. As a result, when the battery pack 70 is attached / detached with the stand 66 and the brush cutter 10 placed on the ground, the battery pack 70 or the user's hand holding it may interfere with the ground. Absent.

  Here, the positional relationship between the battery pack 70 attached to the main unit 40 and the rotation axis X of the motor 46 and the rotation axis Y of the transmission shaft 32 will be described. The battery pack 70 is attached to the rear portion 40 b of the main unit 40 and is positioned on an extension line of the rotation axis X of the motor 46 and the rotation axis Y of the transmission shaft 32. Further, the battery pack 70 has a substantially rectangular parallelepiped shape, and the longitudinal direction of the battery pack 70 is directed in the vertical direction in FIG. That is, the longitudinal direction of the battery pack 70 attached to the main unit 40 coincides with the direction in which the rotation axis X of the motor 46 and the rotation axis Y of the transmission shaft 32 are arranged. Thus, the direction in which the rotation axis X of the motor 46 and the rotation axis Y of the transmission shaft 32 are aligned (that is, the direction in which the output shaft 48 and the transmission shaft 32 of the motor 46 are aligned) is the battery pack 70 mounted on the main unit 40. If the structure coincides with the longitudinal direction, the main unit 40 can be made relatively small.

  Next, a connection structure between the main unit 40 and the operating rod 30 will be described with reference to FIGS. The front portion 40a of the main unit 40 is provided with a hook fixing portion 56 that protrudes in a cylindrical shape. The heel fixing portion 56 is bolted to the main body housing 42. A hook insertion hole 58 is formed in the hook fixing portion 56. A rear end portion of the operation rod 30 (a partial length range including the rear end 30b) is inserted into the rod insertion hole 58. A cylindrical sleeve 38 formed of an elastomer is provided at the rear end portion of the operation rod 30. The rear end portion of the operation rod 30 is inserted into the rod insertion hole 58 of the rod fixing portion 56 together with the sleeve 38. A slit 56a is formed in the heel fixing portion 56 so that the heel insertion hole 58 is enlarged when the operation rod 30 is inserted. The operation rod 30 inserted into the rod insertion hole 58 is fixed by two bolts 60 and 62.

FIG. 6 shows a state where the operating rod 30 is removed from the rod fixing portion 56. As shown in FIG. 6, the sleeve 38 is fitted to the outer peripheral surface of the operation rod 30. The sleeve 38 has a tapered shape, and its diameter decreases from one end 38a to the other end 38b. That is, the diameter of the sleeve 38 is reduced toward the rear end 30 b of the operation rod 30. When the sleeve 38 has a tapered shape, the operation rod 30 can be easily inserted into the rod insertion hole 58 together with the sleeve 38. A convex portion 38p is formed on the inner surface of the sleeve 38a. The convex portion 38p is engaged with a concave portion (through hole) 30c formed in the operation rod 30. This prevents the sleeve 38 from moving with respect to the operation rod 30 when the operation rod 30 is inserted into the rod insertion hole 58 together with the sleeve 38.
The rod insertion hole 58 of the rod fixing portion 56 has a shape corresponding to the operation rod 30 to which the sleeve 38 is fixed. As shown in FIG. 6, the first insertion portion 58a into which the operation rod 30 is directly inserted, the second portion 58c into which the operation rod 30 is inserted together with the sleeve 38, and the first portion 58a. Step part 58b formed between the second part 58c and the second part 58c. The first portion 58 a has a constant diameter along the axial direction so as to correspond to the shape of the operation rod 30. The second portion 58 c has a tapered shape whose diameter changes along the axial direction so as to correspond to the shape of the sleeve 38.

The operation rod 30 is made of a general-purpose pipe material and has a simple cylindrical shape. Therefore, the operation rod 30 can be adopted not only for the brush cutter 10 of this embodiment but also for other models. In the brush cutter 10 of the present embodiment, an operation rod of a brush cutter that uses an engine as a power source is used. However, when the operation rod 30 is commonly used by a plurality of models, an erroneous assembly of the operation rod 30 may occur at the manufacturing site of the brush cutter 10. That is, there may be a problem that the operating rod 30 prepared for manufacturing the brush cutter 10 of this embodiment is used for manufacturing other models.
In the brush cutter 10 according to the present embodiment, the sleeve 38 is provided in the operating rod 30 to prevent the operating rod 30 from being assembled into another model. In this way, by providing the operating rod 30 having a simple shape with the sleeve 38 having a specific shape, the operating rod 30 can be prevented from being assembled into another model. At this time, the sleeve 38 functions as an adapter member for fitting the operation rod 30 to the rod insertion hole 58. When the operating rod 30 is commonly used by two models, it is preferable that one model has a structure that requires the sleeve 38 and the other model has a structure that does not require the sleeve 38. With regard to this embodiment, the engine type brush cutter that uses the operation rod 30 in common has a structure in which the sleeve 38 is unnecessary. Therefore, when the sleeve 38 is attached, the operation rod 30 cannot be assembled to the engine type brush cutter.

  Next, the configuration of the cutting blade unit 20 will be described with reference to FIG. As shown in FIG. 7, the scissor blade unit 20 is provided with a hook fixing portion 22. A hook insertion hole 24 is formed in the hook fixing portion 22. A front end portion of the operation rod 30 (a partial length range including the front end 30a) is inserted into the rod insertion hole 24. The cutting blade unit 14 is rotatably provided with a cutting blade shaft 14. A disc-shaped cutting blade 12 is attached to the cutting blade shaft 14. In addition, instead of the disc-shaped cutting blade 12, a string-shaped cutting blade such as a nylon cord can be attached to the cutting blade shaft 14. The cutting blade unit 20 is provided with a safety cover 26.

  The cutting blade unit 20 is provided with a third gear 18 and a fourth gear 16. The third gear 18 is fixed to the front end 32 a of the transmission shaft 32 so as not to be relatively rotatable. The fourth gear 16 is fixed to the cutting blade shaft 14 so as not to be relatively rotatable, and is engaged with the third gear 18. The third gear 18 and the fourth gear 16 are bevel gears. Torque from the transmission shaft 32 is transmitted to the cutting blade shaft 14 via the third gear 18 and the fourth gear 16. Here, the fourth gear 16 is larger than the third gear 18, and the number of teeth of the fourth gear 16 is larger than the number of teeth of the third gear 18. Thereby, the torque from the transmission shaft 32 is amplified between the third gear 18 and the fourth gear 16. That is, the third gear 18 and the fourth gear 16 constitute a second reduction mechanism that amplifies the torque from the transmission shaft 32 between the transmission shaft 32 and the cutting blade shaft 14. In the brush cutter 10, the output torque of the motor 46 is such that the first gear 50 and the second gear 52 (first reduction mechanism) provided in the main body unit 40, the third gear 18 provided in the cutting blade unit 20, and The fourth gear 16 (second reduction mechanism) is amplified in two stages.

  As described above, the brush cutter 10 is configured such that the sliding direction of the battery pack 70 in the battery pack mounting portion 64 forms an angle with respect to the central axis X of the operation rod 30. Accordingly, when the user attaches / detaches the battery pack 70 while holding the operating rod 30, the hand holding the operating rod 30 is difficult to slip, and the operation of attaching / detaching the battery pack 70 is easy.

  In the brush cutter 10, a cord passage portion 68 for allowing the electric cord 36 to pass is formed in the stand 66 of the main unit 40. Thereby, when the brush cutter 10 is placed on the ground, the electric cord 36 is not sandwiched between the stand 66 and the ground, and the electric cord 36 is prevented from being damaged.

  In the brush cutter 10, a sleeve 38 (adapter member) is fixed to the outer peripheral surface of the rear end portion of the operation rod 30, and the main unit 40 receives the rear end portion of the operation rod 30 to which the sleeve 38 is fixed. A scissors insertion hole 58 is formed. According to this structure, it is possible to prevent the operating rod 30 from being erroneously used for manufacturing other models.

  In the brush cutter 10, a reduction mechanism that amplifies the output torque of the motor 46 is provided in each of the main body unit 40 and the cutting blade unit 20. That is, in the main body unit 40, the first reduction mechanism is configured by the first gear 50 and the second gear 52, and in the cutting blade unit 20, the second reduction mechanism is configured by the third gear 18 and the fourth gear 16. It is configured. According to this structure, the output torque of the motor 46 can be greatly amplified without increasing the size of the main unit 40 or the cutting blade unit 20. As a result, it is possible to employ a small motor of high rotation type (low torque type) as the motor 46.

  FIG. 8 shows a modification of the main unit 40. In the modification shown in FIG. 8, the connection structure of the second gear 52 and the transmission shaft 32 is changed in the main body unit 40 described above. That is, the drive side connecting shaft 54a is fixed to the second gear 52 so as not to be relatively rotatable, and the driven side connecting shaft 54b is fixed to the transmission shaft 32 so as not to be relatively rotatable. The driving side connecting shaft 54a and the driven side connecting shaft 54b are adjacent to each other in the axial direction, but a gap is provided between them.

  A coil spring 55 is wound around the drive side connection shaft 54a and the driven side connection shaft 54b so as to straddle both. That is, the drive side connecting shaft 54a is inserted into the inner hole of the coil spring 55 from one end thereof, and the driven side connecting shaft 54b is inserted from the other end thereof. The coil spring 55 is a square spring whose wire has a square cross-sectional shape. The natural inner diameter of the coil spring 55 is smaller than the outer diameter of the drive side connection shaft 54a and the driven side connection shaft 54b, and the coil spring 55 is elastically deformed so as to tighten the drive side connection shaft 54a and the driven side connection shaft 54b. Yes. Thereby, the torque from the drive side connection shaft 54 a is transmitted to the driven side connection shaft 54 b via the coil spring 55.

The winding direction of the coil spring 55 from the drive side connection shaft 54a toward the driven side connection shaft 54b is the same as the rotation direction of the drive side connection shaft 54a, and the rotational speed of the driven side connection shaft 54b is higher than that of the drive side connection shaft 54a. When it is slow, the coil spring 55 is elastically deformed so that its inner diameter increases. Therefore, for example, when the motor 46 is started up, the inner diameter of the coil spring 55 is increased, so that torque transmission from the drive side connection shaft 54a to the driven side connection shaft 54b is limited. As a result, when the operation of the brush cutter 10 is started, the cutting blade 12 is gently driven. Further, even when the cutting blade 12 comes into contact with a stone or the like and a strong braking force is applied to the cutting blade 12, the torque from the driving side connecting shaft 54a to the driven side connecting shaft 54b is increased by increasing the inner diameter of the coil spring 55. Transmission is interrupted. Thereby, breakage of the cutting blade 12 and kickback of the brush cutter 10 (an event in which the brush cutter 10 is flipped by a reaction from the contact object) are prevented.
On the other hand, when the rotational speed of the driven side connecting shaft 54b is higher than that of the driving side connecting shaft 54a, the inner diameter of the coil spring 55 is reduced and both are strongly connected. Therefore, after the motor 46 is stopped, the cutting blade 12 is prevented from continuing to rotate by inertia.

  The torque transmission structure using the coil spring 55 described above can be provided on the cutting blade unit 20 side instead of the main unit 40 side. That is, the driving side connecting shaft 54 a is provided at the front end 32 a of the transmission shaft 32, the driven side connecting shaft 54 b is provided at the third gear 18, and the driving side connecting shaft 54 a and the driven side connecting shaft 54 b are connected by the coil spring 55. Good. Alternatively, this torque transmission structure can be provided between the output shaft 48 of the motor 46 and the first gear 50.

As mentioned above, although embodiment of this invention was described in detail, these are only illustrations and do not limit a claim. The technology described in the claims includes various modifications and changes of the specific examples illustrated above.
The technical elements described in this specification or the drawings exhibit technical usefulness alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. The technology illustrated in this specification or the drawings achieves a plurality of objects at the same time, and achieving one of the objects itself has technical utility.

10: Brush cutter 12: Cutting blade 20: Cutting blade unit 24: Scissor insertion hole 30: Operation rod 32: Transmission shaft 36: Electric cord 38: Sleeve 40: Body unit 46: Motor 48: Output shaft 64: Battery pack mounting portion 66: Stand 68: Cord passage part 70: Battery pack

Claims (7)

An operation rod,
A cutting unit that is provided at a front end of the operation rod and rotatably supports the cutting blade;
A main unit provided at the rear end of the operation rod;
A motor for driving the cutting blade ;
A handle provided at an intermediate position of the operating rod and gripped by a user;
The handle is provided with a switch for rotating the motor ,
The main unit is formed with a battery pack mounting portion that slidably receives a battery pack that supplies power to the motor,
The brush cutter according to claim 1, wherein a sliding direction of the battery pack in the battery pack mounting portion forms an angle of 45 degrees or more with respect to a central axis of the operation rod.   The brush cutter according to claim 1, wherein a sliding direction of the battery pack in the battery pack mounting portion is substantially orthogonal to a central axis of the operation rod. The main unit has a grounding surface that comes into contact with the ground when the brush cutter is placed on the ground,
The brush cutter according to claim 1 or 2, wherein the grounding surface is positioned below a battery pack attached to the battery pack mounting portion. The operating rod is provided at the front of the main unit,
The brush cutter according to any one of claims 1 to 3, wherein the battery pack mounting portion is provided at a rear portion of the main body unit. The brush cutter according to claim 4 , wherein the battery pack mounting portion is located on an extension line of a central axis of the operation rod.   The sliding direction of the battery pack in the battery pack mounting portion is parallel to the vertical plane when the rotation axis of the cutting blade and the central axis of the operating rod are positioned in the vertical plane. Item 6. A brush cutter according to any one of Items 1 to 5.   When the rotation axis of the cutting blade and the central axis of the operating rod are positioned in a vertical plane, and the central axis of the operating rod is positioned in a horizontal plane, when the battery pack is attached to the battery pack mounting portion The brush cutter according to any one of claims 1 to 6, wherein a sliding direction faces downward, and a sliding direction when the battery pack is removed from the battery pack mounting portion faces upward.

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