Work machine

Abstract

To provide a work machine which can suppress a first planetary gear from having one-sided contact with a first sun gear or a first internal gear.SOLUTION: A work machine comprises: a driving-motor; a power transmission part; an implement part; and a housing. The power transmission part includes: a first planetary gear mechanism; a bevel gear; a first bearing; and a second bearing. The bevel gear includes: a gear part; and a shaft part. The first planetary gear mechanism includes: a first carrier which rotates integrally with the shaft part; a first planetary gear which is rotatably supported by the first carrier; a first internal gear which is disposed outside of the first planetary gear; and a first sun gear which is disposed inside of the first planetary gear. The first bearing is directly or indirectly supported by the housing to rotatably support the shaft part. The second bearing is directly or indirectly supported by the housing to rotatably support the first carrier.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The technology disclosed in this specification relates to a work machine. [Background technology]

[0002] Patent Document 1 discloses a work machine. The work machine includes a prime mover, a power transmission unit connected to the prime mover, a working unit connected to the power transmission unit, and a housing that accommodates the prime mover and the power transmission unit. The power transmission unit includes a first planetary gear mechanism, a bevel gear, a first bearing, and a second bearing. The bevel gear includes a gear unit connected to the working unit and a shaft unit that can rotate integrally with the gear unit. The first planetary gear mechanism includes a first carrier fixed to the shaft unit, a first planetary gear rotatably supported by the first carrier, a first internal gear disposed outside the first planetary gear to mesh with the first planetary gear, and a first sun gear disposed inside the first planetary gear to mesh with the first planetary gear. The first bearing is supported directly or indirectly by the housing and rotatably supports the shaft unit. The second bearing is supported directly or indirectly by the housing, and rotatably supports the shaft portion. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Chinese Utility Model No. 209954711 Summary of the Invention [Problem to be solved by the invention]

[0004] In the above-described work machine, a force acts in a predetermined direction on the gear portion of the bevel gear due to a reaction force that the working unit receives from the work object. When this occurs, the shaft portion of the bevel gear tilts in a direction opposite to the predetermined direction, with the first bearing or the second bearing as a fulcrum. This causes the first carrier to deviate in a direction perpendicular to the rotation axis, causing the first planetary gear to come into partial contact with the first sun gear or the first internal gear. This specification provides technology that can prevent the first planetary gear from coming into partial contact with the first sun gear or the first internal gear. [Means for solving the problem]

[0005] The working machine disclosed in this specification may include a prime mover, a power transmission unit connected to the prime mover, a working unit connected to the power transmission unit, and a housing that accommodates the power transmission unit. The power transmission unit may include a first planetary gear mechanism, a bevel gear, a first bearing, and a second bearing. The bevel gear may include a gear unit connected to the working unit and a shaft unit that can rotate integrally with the gear unit. The first planetary gear mechanism may include a first carrier that can rotate integrally with the shaft unit, a first planetary gear rotatably supported by the first carrier, a first internal gear arranged outside the first planetary gear to mesh with the first planetary gear, and a first sun gear arranged inside the first planetary gear to mesh with the first planetary gear. The first bearing may be supported directly or indirectly by the housing and may rotatably support the shaft unit. The second bearing may be supported directly or indirectly by the housing, and may rotatably support the first carrier.

[0006] In the above configuration, the second bearing prevents the first carrier from deviating in a direction perpendicular to the rotation axis. Therefore, even if a force in a predetermined direction acts on the gear portion of the bevel gear due to a reaction force that the working unit receives from the work object, the shaft portion of the bevel gear can be prevented from tilting in a direction opposite to the predetermined direction with the first bearing as a fulcrum. This configuration prevents the first planetary gear from coming into partial contact with the first sun gear or the first internal gear. [Brief explanation of the drawings]

[0007] [Figure 1] 1 is a perspective view of a work machine 2 according to an embodiment. [Figure 2] 2 is a side view of the internal structure of the rear part of the work machine 2 according to the embodiment, as viewed from the right. FIG. [Figure 3] 2 is a cross-sectional view of the vicinity of a power transmission unit 36 ​​of a work machine 2 according to an embodiment, as viewed from above. [Figure 4] 2 is a side view of the internal structure of the front part of the work machine 2 according to the embodiment, as viewed from the right. FIG. [Figure 5] 4 is a cross-sectional view of the vicinity of a power transmission unit 36 ​​of a work machine 2 according to a comparative example, viewed from above. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0008] Representative, non-limiting embodiments of the present invention are described in detail below with reference to the drawings. This detailed description is intended simply to provide those skilled in the art with details for implementing preferred embodiments of the present invention, and is not intended to limit the scope of the present invention. Furthermore, the additional features and inventions disclosed can be used separately or in conjunction with other features and inventions to provide further improved work machines.

[0009] Furthermore, the combinations of features and steps disclosed in the following detailed description are not essential to practicing the invention in its broadest sense, but are described solely to specifically illustrate exemplary embodiments of the invention. Furthermore, the various features of the following exemplary embodiments and those described in the claims do not necessarily have to be combined in the exact embodiments described herein or in the exact order listed to provide additional and useful embodiments of the invention.

[0010] All features described in this specification and / or claims are intended to be disclosed individually and independently of one another as limitations to the specific features described in the original disclosure and claims, apart from the configuration of features described in the examples and / or claims. Furthermore, all numerical ranges and group or aggregate descriptions are intended to disclose intermediate configurations thereof as limitations to the specific features described in the original disclosure and claims.

[0011] In one or more embodiments, a work machine may include a prime mover, a power transmission unit connected to the prime mover, a working unit connected to the power transmission unit, and a housing that accommodates the power transmission unit. The power transmission unit may include a first planetary gear mechanism, a bevel gear, a first bearing, and a second bearing. The bevel gear may include a gear unit connected to the working unit and a shaft unit that can rotate integrally with the gear unit. The first planetary gear mechanism may include a first carrier that can rotate integrally with the shaft unit, a first planetary gear rotatably supported by the first carrier, a first internal gear disposed outside the first planetary gear to mesh with the first planetary gear, and a first sun gear disposed inside the first planetary gear to mesh with the first planetary gear. The first bearing may be directly or indirectly supported by the housing and may rotatably support the shaft unit. The second bearing may be supported directly or indirectly by the housing, and may rotatably support the first carrier.

[0012] In one or more embodiments, the first internal gear may be fixed to the housing.

[0013] According to the above configuration, the first planetary gear mechanism can function as a reduction mechanism having a large reduction ratio.

[0014] In one or more embodiments, the first planetary gear mechanism may further include a sleeve integrally formed with the first internal gear, and the second bearing may be directly supported by the sleeve.

[0015] According to the above configuration, the support structure for the second bearing can be simplified.

[0016] In one or more embodiments, the sleeve may abut against the first bearing with respect to the central axis direction of the first bearing.

[0017] According to the above configuration, the sleeve formed integrally with the first internal gear can function as a retainer for the first bearing, thereby simplifying the support structure for the first bearing.

[0018] In one or more embodiments, the power transmission unit may further include a second planetary gear mechanism. The second planetary gear mechanism may include a second carrier rotatable integrally with the first sun gear, a second planetary gear rotatably supported by the second carrier, a second internal gear disposed outside the second planetary gear so as to mesh with the second planetary gear, and a second sun gear disposed inside the second planetary gear so as to mesh with the second planetary gear.

[0019] According to the above configuration, the rotation can be reduced in each of the first planetary gear mechanism and the second planetary gear mechanism.

[0020] In one or more embodiments, the second internal gear may be separate from the first internal gear.

[0021] The first planetary gear mechanism and the second planetary gear mechanism differ in input rotation speed, torque, reduction ratio to be achieved, etc., and therefore the strength and rigidity required for the first internal gear and the second internal gear differ. With the above configuration, because the first internal gear and the second internal gear are separate, they can be made of materials and have sizes that match the strength and rigidity required for each.

[0022] In one or more embodiments, the working portion may include a first blade and a second blade movable relative to the first blade between an open position and a closed position. The working implement may function as a handheld pruning shears.

[0023] According to the above configuration, in a work machine that functions as pruning shears, it is possible to prevent the first planetary gear from coming into partial contact with the first sun gear or the first internal gear.

[0024] In one or more embodiments, the prime mover may comprise an electric motor.

[0025] According to the above configuration, in a work machine in which a working part is driven by an electric motor, it is possible to prevent the first planetary gear from coming into partial contact with the first sun gear or the first internal gear.

[0026] (Example) The work machine 2 shown in Fig. 1 is a pair of pruning shears that is mainly used to cut tree branches, etc. The work machine 2 is an electrically powered work machine that operates using power supplied from an external power source (not shown) via a power connector 4. The work machine 2 can be held and carried by a user in one hand.

[0027] The work machine 2 includes a housing 6, a working unit 8 that performs cutting work, an operation unit 10 that can be operated by the user, and a display unit 12 that displays various information to the user. The working unit 8 includes a fixed blade 14 and a movable blade 16 that can rotate relative to the fixed blade 14. The operation unit 10 includes a trigger lever 18, a power switch 20, and an open position adjustment switch 22. The work machine 2 rotates the movable blade 16 relative to the fixed blade 14 in response to a pull-up operation of the trigger lever 18. The housing 6 also includes a gripping portion 24 that the user can hold with one hand, a front storage portion 26 located forward of the gripping portion 24, a rear storage portion 28 located rearward of the gripping portion 24, and a protection portion 30 that protects the fingers of the user operating the trigger lever 18. The trigger lever 18 and the protection portion 30 are located below the front storage portion 26.

[0028] In this specification, the longitudinal direction of the grip portion 24 is defined as the front-rear direction. In the front-rear direction, the direction from the grip portion 24 toward the working portion 8 is defined as the front direction, and the opposite direction is defined as the rear direction. The direction perpendicular to the front-rear direction and along the rotation axis Rx of the movable blade 16 is defined as the left-right direction. In the left-right direction, the direction from the movable blade 16 toward the fixed blade 14 is defined as the left direction, and the opposite direction is defined as the right direction. The direction perpendicular to the front-rear direction and the left-right direction is defined as the up-down direction. In the up-down direction, the direction from the protector 30 toward the trigger lever 18 is defined as the up direction, and the opposite direction is defined as the down direction.

[0029] The power switch 20 and the open position adjustment switch 22 are disposed on the upper surface of the rear storage section 28. The power switch 20 is a switch for switching the main power supply of the work machine 2 on and off. The open position adjustment switch 22 is a switch for adjusting the open position of the movable blade 16. The display section 12 is disposed on the upper surface of the front storage section 26. The display section 12 includes an LED (not shown) for displaying the on / off state of the main power supply, etc.

[0030] The work machine 2 further includes a control device 32 (see FIG. 2), an electric motor 34 (see FIG. 2), and a power transmission unit 36 ​​(see FIG. 3).

[0031] As shown in Fig. 2, the control device 32 is accommodated inside the rear accommodation portion 28. The control device 32 is electrically connected to the power connector 4, the operation unit 10, the display unit 12 (see Fig. 1), and the electric motor 34. The control device 32 includes a power supply circuit (not shown) for adjusting the power supplied via the power connector 4, and a control circuit (not shown) for controlling the operation of the operation unit 10, the display unit 12, and the electric motor 34. The power supplied from an external power source via the power connector 4 is adjusted by the power supply circuit of the control device 32 and then supplied to the operation unit 10, the display unit 12, and the electric motor 34.

[0032] The electric motor 34 is, for example, a DC brushless motor, such as a coreless motor, and is housed inside the grip portion 24. An output shaft 38 (see FIG. 3) of the electric motor 34 extends in the front-rear direction.

[0033] As shown in FIG. 3, the power transmission unit 36 ​​is accommodated inside the front accommodation portion 26. The power transmission unit 36 ​​includes a gear piece 40, a gear housing 42, a bevel gear 44, a first planetary gear mechanism 46, a second planetary gear mechanism 48, a third planetary gear mechanism 50, a first bearing 52, and a second bearing 54. The gear housing 42 is fixed to the front accommodation portion 26. The bevel gear 44 is accommodated inside the gear housing 42. The bevel gear 44 includes a gear portion 56 and a shaft portion 58. The gear portion 56 and the shaft portion 58 are formed seamlessly and integrally.

[0034] As shown in FIG. 4, an opening 42a is formed on the right surface of the gear housing 42. The gear portion 56 of the bevel gear 44 meshes with a gear portion 40a (see FIG. 3) formed on the left surface of the gear piece 40 via the opening 42a. The gear piece 40 is fixed to the movable blade 16, and the gear piece 40 and the movable blade 16 rotate integrally around the rotation axis Rx. Therefore, when the bevel gear 44 rotates clockwise as viewed from the front, the gear piece 40 and the movable blade 16 rotate clockwise as viewed from the right (i.e., in the direction in which the movable blade 16 closes). Conversely, when the bevel gear 44 rotates counterclockwise as viewed from the front, the gear piece 40 and the movable blade 16 rotate counterclockwise as viewed from the right (i.e., in the direction in which the movable blade 16 opens).

[0035] 3, a first bearing mounting portion 42b is formed in the gear housing 42. The first bearing 52 is mounted to the first bearing mounting portion 42b so that its central axis is aligned in the front-to-rear direction. The shaft portion 58 of the bevel gear 44 is rotatably supported by the first bearing 52.

[0036] The first planetary gear mechanism 46 includes a first carrier 60, a first planetary gear 62, a first sun gear 64, a first internal gear 66, and a cylindrical sleeve 68. The shaft portion 58 of the bevel gear 44 is fitted into a fitting hole 60a formed in the first carrier 60 rearward of the first bearing 52, and the bevel gear 44 and the first carrier 60 rotate integrally. The first carrier 60 rotatably supports the first planetary gear 62 via a pin 60b. The first internal gear 66 is disposed outside the first planetary gear 62 and meshes with the first planetary gear 62. The first sun gear 64 is disposed inside the first planetary gear 62 and meshes with the first planetary gear 62. The first planetary gear mechanism 46 functions as a reduction mechanism that reduces the rotation speed of the first sun gear 64 and transmits it to the first carrier 60.

[0037] The cylindrical sleeve 68 is disposed in front of the first internal gear 66. The cylindrical sleeve 68 and the first internal gear 66 are seamlessly formed as a single unit. The second bearing 54 is attached to the cylindrical sleeve 68 so that its central axis is aligned in the front-to-rear direction. The first carrier 60 is rotatably supported by the second bearing 54. The gear housing 42 is formed with a cylindrical sleeve attachment portion 42c having a female thread on its inner circumferential surface. The cylindrical sleeve 68 is formed with a male thread on its outer circumferential surface that corresponds to the female thread on the cylindrical sleeve attachment portion 42c. The cylindrical sleeve 68 is fixed to the gear housing 42 by threading onto the cylindrical sleeve attachment portion 42c. When the cylindrical sleeve 68 is fixed to the gear housing 42, the front end of the cylindrical sleeve 68 abuts against the rear end of the first bearing 52. Therefore, the cylindrical sleeve 68 functions as a retainer that prevents the first bearing 52 from falling off the gear housing 42.

[0038] The second planetary gear mechanism 48 includes a second carrier 70, a second planetary gear 72, a second sun gear 74, and a second internal gear 76. The second carrier 70 is formed seamlessly and integrally with the first sun gear 64, and the second carrier 70 and the first sun gear 64 rotate integrally. The second carrier 70 rotatably supports the second planetary gear 72 via a pin 70a. The second internal gear 76 is disposed outside the second planetary gear 72 and meshes with the second planetary gear 72. The second sun gear 74 is disposed inside the second planetary gear 72 and meshes with the second planetary gear 72. The second planetary gear mechanism 48 functions as a reduction mechanism that reduces the rotation of the second sun gear 74 and transmits it to the second carrier 70.

[0039] The third planetary gear mechanism 50 includes a third carrier 80, a third planetary gear 82, a third sun gear 84, and a third internal gear 86. The third carrier 80 is formed seamlessly and integrally with the second sun gear 74, and the third carrier 80 and the second sun gear 74 rotate integrally. The third carrier 80 rotatably supports the third planetary gear 82 via a pin 80a. The third internal gear 86 is disposed outside the third planetary gear 82 and meshes with it. The third sun gear 84 is disposed inside the third planetary gear 82 and meshes with it. The third planetary gear mechanism 50 functions as a reduction mechanism that reduces the rotation of the third sun gear 84 and transmits it to the third carrier 80. The second internal gear 76 and the third internal gear 86 are formed seamlessly and integrally. The second internal gear 76 and the third internal gear 86 are fixed to the first internal gear 66 and the front housing portion 26 .

[0040] The output shaft 38 of the electric motor 34 is fitted into a fitting groove 84a formed in the third sun gear 84, and the output shaft 38 and the third sun gear 84 rotate integrally. Therefore, when the electric motor 34 is driven, the rotation of the output shaft 38 is reduced in speed by each of the third planetary gear mechanism 50, the second planetary gear mechanism 48, and the first planetary gear mechanism 46, and then transmitted to the bevel gear 44, and then to the movable blade 16 via the gear piece 40.

[0041] When the work machine 2 performs a cutting operation, a reaction force that the movable blade 16 receives from the workpiece acts to press the gear piece 40 against the gear portion 56 of the bevel gear 44, and a leftward force acts on the gear portion 56 of the bevel gear 44. If the second bearing 54 that rotatably supports the first carrier 60 were not present as shown in FIG. 5 , when a leftward force acts on the gear portion 56 of the bevel gear 44, the portion of the shaft portion 58 of the bevel gear 44 rearward of the first bearing 52 would tilt rightward. In this case, the first carrier 60 would be displaced rightward, which could cause the first planetary gear 62 to come into partial contact with the first sun gear 64 or the first internal gear 66.

[0042] 3, the work machine 2 of this embodiment includes a second bearing 54 that rotatably supports the first carrier 60. Therefore, even if a leftward force acts on the gear portion 56 of the bevel gear 44, the rightward displacement of the first carrier 60 is restrained by the second bearing 54, and the portion of the shaft portion 58 of the bevel gear 44 that is rearward of the first bearing 52 does not tilt rightward. This prevents the first planetary gear 62 from coming into partial contact with the first sun gear 64 or the first internal gear 66.

[0043] (Variation) In the above embodiment, the working machine 2 is a pair of pruning shears, and the working unit 8 includes the fixed blade 14 and the movable blade 16. However, the working machine 2 may be another type of working machine, and the working unit 8 may be another type of working unit. For example, the working machine 2 may be a cutter, a riveter, a grinder, or the like.

[0044] Instead of being provided with the power connector 4, the work machine 2 may be provided with a battery pack attachment portion (not shown) to which a rechargeable battery pack (not shown) can be attached and detached.

[0045] The electric motor 34 may be replaced with a motor of a different type (for example, a brushed motor, a cored motor).

[0046] (Features of the embodiment) As described above, in one or more embodiments, the work machine 2 includes the electric motor 34 (an example of a prime mover), the power transmission unit 36 ​​connected to the electric motor 34, the working unit 8 connected to the power transmission unit 36, and the housing 6 that accommodates the power transmission unit 36. The power transmission unit 36 ​​includes a first planetary gear mechanism 46, a bevel gear 44, a first bearing 52, and a second bearing 54. The bevel gear 44 includes a gear unit 56 connected to the working unit 8, and a shaft unit 58 that can rotate integrally with the gear unit 56. The first planetary gear mechanism 46 includes a first carrier 60 that is rotatable integrally with the shaft portion 58, a first planetary gear 62 that is rotatably supported on the first carrier 60, a first internal gear 66 that is arranged outside the first planetary gear 62 to mesh with the first planetary gear 62, and a first sun gear 64 that is arranged inside the first planetary gear 62 to mesh with the first planetary gear 62. The first bearing 52 is supported directly or indirectly by the housing 6, and rotatably supports the shaft portion 58. The second bearing 54 is supported directly or indirectly by the housing 6, and rotatably supports the first carrier 60.

[0047] In the above configuration, the second bearing 54 restrains the first carrier 60 from deviating in a direction perpendicular to the rotation axis. Therefore, even if a force acts in a predetermined direction on the gear portion 56 of the bevel gear 44 due to a reaction force that the working unit 8 receives from the work object, the shaft portion 58 of the bevel gear 44 can be prevented from tilting in a direction opposite to the predetermined direction with the first bearing 52 as a fulcrum. With this configuration, it is possible to prevent the first planetary gear 62 from coming into partial contact with the first sun gear 64 or the first internal gear 66.

[0048] In one or more embodiments, the first internal gear 66 is fixed to the housing 6 .

[0049] According to the above configuration, the first planetary gear mechanism 46 can function as a reduction mechanism having a large reduction ratio.

[0050] In one or more embodiments, the first planetary gear mechanism 46 further includes a cylindrical sleeve 68 (an example of a sleeve) formed integrally with the first internal gear 66. The second bearing 54 is supported directly on the cylindrical sleeve 68.

[0051] According to the above configuration, the support structure for the second bearing 54 can be simplified.

[0052] In one or more embodiments, the cylindrical sleeve 68 abuts the first bearing 52 in the direction of the central axis of the first bearing 52 .

[0053] According to the above configuration, the cylindrical sleeve 68 formed integrally with the first internal gear 66 can function as a retainer for the first bearing 52. The support structure for the first bearing 52 can be simplified.

[0054] In one or more embodiments, the power transmission section 36 further includes a second planetary gear mechanism 48. The second planetary gear mechanism 48 includes a second carrier 70 that is rotatable integrally with the first sun gear 64, a second planetary gear 72 that is rotatably supported on the second carrier 70, a second internal gear 76 that is disposed outside the second planetary gear 72 and meshes with the second planetary gear 72, and a second sun gear 74 that is disposed inside the second planetary gear 72 and meshes with the second planetary gear 72.

[0055] According to the above configuration, the rotation can be reduced in each of the first planetary gear mechanism 46 and the second planetary gear mechanism 48.

[0056] In one or more embodiments, the second internal gear 76 is separate from the first internal gear 66 .

[0057] The first planetary gear mechanism 46 and the second planetary gear mechanism 48 differ in the input rotation speed, torque, reduction ratio to be achieved, etc., and therefore differ in the strength and rigidity required for the first internal gear 66 and the second internal gear 76. With the above configuration, the first internal gear 66 and the second internal gear 76 are separate bodies, and therefore can be made of materials and sized to suit the strength and rigidity required for each.

[0058] In one or more embodiments, the working unit 8 includes a fixed blade 14 (an example of a first blade) and a movable blade 16 (an example of a second blade) that is movable between an open position and a closed position relative to the fixed blade 14. The working implement 2 functions as a handheld pruning shears.

[0059] According to the above configuration, in the work implement 2 that functions as pruning shears, it is possible to prevent the first planetary gear 62 from coming into contact with the first sun gear 64 or the first internal gear 66 on one side.

[0060] In one or more embodiments, the prime mover of the implement 2 is an electric motor 34 .

[0061] According to the above configuration, in the work machine 2 in which the working unit 8 is driven by the electric motor 34, it is possible to prevent the first planetary gear 62 from coming into partial contact with the first sun gear 64 or the first internal gear 66. [Explanation of symbols]

[0062] 2: Work equipment 4: Power connector 6: Housing 8: Working section 10:Operation unit 12: Display section 14: Fixed blade 16: Movable blade 18: Trigger lever 20: Power switch 22: Open position adjustment switch 24: Grip part 26: Front storage compartment 28: Rear storage compartment 30:Protective part 32: Control device 34: Electric motor 36: Power transmission section 38: Output shaft 40: Gear piece 40a: Gear section 42: Gear housing 42a: Opening 42b: First bearing mounting part 42c: Cylindrical sleeve mounting part 44: Bevel gear 46: First planetary gear mechanism 48: Second planetary gear mechanism 50: 3rd planetary gear mechanism 52: First bearing 54: Second bearing 56: Gear section 58: Shaft section 60: First carrier 60a: fitting hole 60b: Pin 62: First planetary gear 64: First sun gear 66: 1st internal gear 68: Cylindrical sleeve 70: Second career 70a: pin 72: Second planetary gear 74: Second sun gear 76: 2nd internal gear 80: Third carrier 80a: pin 82: Third planetary gear 84: 3rd Sun Gear 84a: Fitting groove 86: 3rd internal gear

Claims

1. A work machine, The prime mover and a power transmission unit connected to the prime mover; a working unit connected to the power transmission unit; a housing that accommodates the power transmission unit, The power transmission unit is a first planetary gear mechanism; Bevel gear and A first bearing; A second bearing is provided, The bevel gear is a gear portion connected to the working portion; a shaft portion that can rotate integrally with the gear portion, The first planetary gear mechanism comprises: a first carrier that is rotatable integrally with the shaft portion; a first planetary gear rotatably supported on the first carrier; a first internal gear disposed outside the first planetary gear so as to mesh with the first planetary gear; a first sun gear disposed inside the first planetary gear so as to mesh with the first planetary gear; the first bearing is directly or indirectly supported by the housing and rotatably supports the shaft portion; The second bearing is supported directly or indirectly by the housing and rotatably supports the first carrier.

2. The work machine according to claim 1 , wherein the first internal gear is fixed to the housing.

3. the first planetary gear mechanism further includes a sleeve formed integrally with the first internal gear, 3. The work machine according to claim 1, wherein the second bearing is directly supported by the sleeve.

4. 4. The work machine according to claim 3, wherein the sleeve abuts against the first bearing in the direction of the central axis of the first bearing.

5. the power transmission unit further includes a second planetary gear mechanism, The second planetary gear mechanism is a second carrier that is rotatable integrally with the first sun gear; a second planetary gear rotatably supported by the second carrier; a second internal gear disposed outside the second planetary gear so as to mesh with the second planetary gear; The work machine according to claim 1 , further comprising a second sun gear disposed inside the second planetary gear so as to mesh with the second planetary gear.

6. The work machine according to claim 5 , wherein the second internal gear is separate from the first internal gear.

7. The working unit includes a first blade and a second blade movable relative to the first blade between an open position and a closed position; 7. The implement according to claim 1, which functions as a hand-held pruning shears.

8. 8. The work implement of claim 1, wherein the prime mover comprises an electric motor.

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