Work equipment

Abstract

To provide a technique capable of suitably suppressing the over-rolling of a blade cover.SOLUTION: A working machine comprises: a rotary cutter; an output shaft fitted with the rotary cutter; a driving-motor rotationally driving the output shaft; a housing rotatably supporting the output shaft and storing the driving-motor; and a blade cover rotatably fitted with respect to the housing. The side wall part of the blade cover comprises a first stopper part and a second stopper part. The opposite part of the housing comprises a first stopper receiving part and a second stopper receiving part. When the blade cover is rolled to either of rolling directions, the first stopper part is abutted against the first stopper receiving part from the other side of the rolling directions in a first abutment position. When the blade cover is further rolled to either of the rolling directions from a state where the first stopper part is abutted against the first stopper receiving part, the second stopper part is abutted against the second stopper receiving part from the other side of rolling directions in a second abutment position.SELECTED DRAWING: Figure 7

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 including a rotary blade, an output shaft to which the rotary blade is attached, a prime mover that rotates and drives the output shaft, a housing that rotatably supports the output shaft and accommodates the prime mover, and a blade cover that is rotatably attached to the housing around a rotation axis that substantially coincides with the rotation axis of the output shaft. The blade cover includes a side wall that covers at least a portion of a side surface of the rotary blade. The housing includes a facing portion that faces a surface of the side wall opposite to the surface facing the side surface of the rotary blade. The side wall includes a first stopper portion. The facing portion includes a first stopper receiving portion. When the blade cover is rotated in one direction of rotation of the blade cover, the first stopper portion abuts against the first stopper receiving portion from the other side of the rotation direction at a first abutment position. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2015-164769 A Summary of the Invention [Problem to be solved by the invention]

[0004] In the work machine of Patent Document 1, the first stopper portion abuts against the first stopper receiving portion from the other side of the rotation direction, thereby suppressing excessive rotation of the blade cover in one rotation direction. In such a work machine, even when the first stopper portion abuts against the first stopper receiving portion, the first stopper receiving portion may ride up on the first stopper portion, causing the blade cover to further rotate in one rotation direction. In the work machine of Patent Document 1, if the blade cover further rotates in one rotation direction from a state in which the first stopper portion abuts against the first stopper receiving portion, excessive rotation of the blade cover cannot be suppressed. This specification provides a technology that can appropriately suppress excessive rotation of the blade cover. [Means for solving the problem]

[0005] The working machine disclosed in this specification includes a rotary blade, an output shaft to which the rotary blade is attached, a prime mover that rotates and drives the output shaft, a housing that rotatably supports the output shaft and accommodates the prime mover, and a blade cover that is rotatably attached to the housing around a rotation axis that substantially coincides with the rotation axis of the output shaft. The blade cover includes a side wall that covers at least a portion of a side surface of the rotary blade. The housing includes a facing portion that faces the surface of the side wall opposite to the surface facing the side surface of the rotary blade. The side wall includes a first stopper portion and a second stopper portion. The facing portion includes a first stopper receiving portion and a second stopper receiving portion. When the blade cover is rotated in one direction of rotation of the blade cover, the first stopper portion abuts against the first stopper receiving portion from the other side of the rotation direction at a first abutment position. When the blade cover is further rotated in one direction of the rotation direction from the state in which the first stopper portion abuts against the first stopper receiving portion, the second stopper portion abuts against the second stopper receiving portion from the other side of the rotation direction at a second abutment position.

[0006] According to the above configuration, the first stopper portion abuts against the first stopper receiving portion, thereby suppressing excessive rotation of the blade cover in one rotation direction. Furthermore, according to the above configuration, when the first stopper receiving portion rides up on the first stopper portion and the blade cover is further rotated in one rotation direction, the second stopper portion abuts against the second stopper receiving portion. Therefore, excessive rotation of the blade cover in one rotation direction is suppressed in two stages. According to the above configuration, excessive rotation of the blade cover can be appropriately suppressed. [Brief explanation of the drawings]

[0007] [Figure 1] 1 is an overall perspective view of a power cutter 10 according to an embodiment, as viewed from above on the front right. [Figure 2] 1 is a side view of the internal structure of a housing 14 of a power cutter 10 according to an embodiment, as viewed from the right. [Figure 3] 1 is an enlarged view of a rear handle 20 provided on the power cutter 10 according to the embodiment, viewed from the upper rear left side. [Figure 4] 1 is an enlarged view of a first side wall portion 162 of a blade cover 16 included in a power cutter 10 according to an embodiment, viewed from the right. [Figure 5] 1 is an enlarged view of a facing portion 142 of a blade arm 14b provided in the power cutter 10 according to the embodiment, viewed from the left. [Figure 6] 3 is an enlarged view of the excessive rotation suppression mechanism of the blade cover 16 in the power cutter 10 according to the embodiment, viewed from below. FIG. [Figure 7] 7 is a cross-sectional view of the power cutter 10 according to the embodiment, seen from the right, showing a state in which the first stopper portion 110 is in contact with the first stopper receiving portion 210 from the second direction side on the reference plane P shown in FIG. 6. FIG. [Figure 8] 7 is a view of the power cutter 10 according to the embodiment, viewed from the right, showing a state in which the third stopper portion 130 abuts against the third stopper receiving portion 230 from the first direction side on the reference plane P shown in FIG. 6. FIG. [Figure 9]1 is a diagram showing a predetermined range S1 of the rotary blade 12 that is necessarily covered by the blade cover 16 when the blade cover 16 is rotated arbitrarily within the movable range in the power cutter 10 according to the embodiment. 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, when the first stopper portion abuts against the first stopper receiving portion, the angle that the line connecting the second stopper portion and the pivot axis makes with the line connecting the second stopper receiving portion and the pivot axis may be in the range of 0°-2°.

[0012] If the blade cover rotates significantly between the state where the first stopper portion abuts the first stopper receiving portion and the state where the second stopper portion abuts the second stopper receiving portion, excessive rotation of the blade cover may not be properly suppressed. According to the above configuration, the angle between the line connecting the second stopper portion and the rotation axis and the line connecting the second stopper receiving portion and the rotation axis is within the range of 0°-2°. Therefore, from the state where the first stopper receiving portion abuts the first stopper portion, the second stopper portion abuts the second stopper receiving portion without the blade cover rotating significantly. According to the above configuration, excessive rotation of the blade cover can be more properly suppressed.

[0013] In one or more embodiments, the first abutment location and the second abutment location may be offset from one another in the radial direction.

[0014] When the first and second contact positions are not offset from each other in the radial direction of the rotation shaft, the first and second stopper receiving portions provided in the opposing portions are disposed so as to at least partially overlap in the circumferential direction of the rotation shaft. According to the above configuration, the first and second stopper receiving portions can be disposed without overlapping in the circumferential direction of the rotation shaft. Therefore, the opposing portions where the first and second stopper receiving portions are provided can be made smaller in size in the circumferential direction of the rotation shaft.

[0015] In one or more embodiments, the first abutment location may be offset radially outward from the second abutment location.

[0016] Typically, the blade cover is attached to the housing near the pivot shaft. In this case, when the first stopper receiving portion rides on the first stopper portion, the opposing portion and the side wall portion move apart as they move away from the pivot shaft. In this case, if the second stopper portion and the second stopper receiving portion are significantly separated from each other, the second stopper portion and the second stopper receiving portion may not abut, and excessive rotation of the blade cover may not be suppressed. According to the above configuration, the second abutment position is offset radially inward from the first abutment position, so that when the first stopper receiving portion rides on the first stopper portion, the second stopper portion and the second stopper receiving portion are prevented from moving apart significantly. Therefore, when the first stopper receiving portion rides on the first stopper portion, the second stopper portion and the second stopper receiving portion can be more reliably abutted against each other. According to the above configuration, excessive rotation of the blade cover can be more reliably suppressed.

[0017] In one or more embodiments, the side wall portion may further include a third stopper portion. The opposing portion may further include a third stopper receiving portion. When the blade cover is rotated in the other direction of rotation, the third stopper portion may abut against the third stopper receiving portion from the one side of the rotation direction at a third abutment position.

[0018] According to the above configuration, the third stopper portion abuts against the third stopper receiving portion, thereby suppressing excessive rotation of the blade cover in the other rotation direction. According to the above configuration, it is possible to suppress not only excessive rotation of the blade cover in one rotation direction but also excessive rotation of the blade cover in the other rotation direction.

[0019] In one or more embodiments, the output shaft may be rotationally driven in a predetermined rotational direction relative to the rotation axis, the one of the rotational directions may correspond to a forward direction of the rotational direction of the output shaft, and the other of the rotational directions may correspond to a reverse direction of the rotational direction of the output shaft.

[0020] For example, a situation in which torque sufficient to cause the first stopper receiving portion to ride up onto the first stopper portion may occur in the blade cover when torque from the rotary blade is transmitted to the blade cover via a foreign object or the like that has entered between the rotary blade and the blade cover. In this case, torque is generated in the blade cover in a direction that rotates the blade cover in a direction corresponding to the forward rotation direction of the rotary blade. According to the above configuration, the first stopper portion and the second stopper portion can suppress excessive rotation of the blade cover in a two-stage manner in a direction corresponding to the forward rotation direction of the rotary blade. According to the above configuration, excessive rotation of the blade cover can be more appropriately suppressed when torque from the rotary blade is transmitted to the blade cover.

[0021] In one or more embodiments, at least one of the first stopper portion, the second stopper portion, and the third stopper portion may be integrally formed with the side wall portion.

[0022] In the manufacturing process of an electric power tool, it is sometimes desirable to reduce the number of parts in the blade cover. With the above configuration, the number of parts in the blade cover can be reduced compared to when the first stopper portion, the second stopper portion, and the third stopper portion are separately attached to the side wall portion.

[0023] In one or more embodiments, at least one of the first stopper portion, the second stopper portion, and the third stopper portion may be formed separately from the side wall portion.

[0024] Typically, when the first stopper portion, the second stopper portion, and the third stopper portion are integrally formed with the side wall portion, the first stopper portion, the second stopper portion, and the third stopper portion are made of the same material as the material used for the side wall portion. However, there are cases where it is desirable to use a material different from the material used for the side wall portion for the first stopper portion, the second stopper portion, and the third stopper portion. According to the above configuration, at least one of the first stopper portion, the second stopper portion, and the third stopper portion can be made of a material different from the material used for the side wall portion.

[0025] In one or more embodiments, at least one of the first stopper receiving portion, the second stopper receiving portion, and the third stopper receiving portion may be formed integrally with the opposing portion.

[0026] In the manufacturing process of an electric power tool, it is sometimes desirable to reduce the number of parts in the housing. With the above configuration, the number of parts in the housing can be reduced compared to when the first stopper receiving portion, the second stopper receiving portion, and the third stopper receiving portion are separately attached to the opposing portions.

[0027] In one or more embodiments, at least one of the first stopper receiving portion, the second stopper receiving portion, and the third stopper receiving portion may be formed separately from the opposing portion.

[0028] Typically, when the first stopper receiving portion, the second stopper receiving portion, and the third stopper receiving portion are integrally formed with the opposing portion, the first stopper receiving portion, the second stopper receiving portion, and the third stopper receiving portion are made of the same material as that used for the opposing portion. However, there are cases where it is desirable to use a different material for the first stopper receiving portion, the second stopper receiving portion, and the third stopper receiving portion from that used for the opposing portion. With the above configuration, at least one of the first stopper receiving portion, the second stopper receiving portion, and the third stopper receiving portion can be made of a different material from that used for the opposing portion.

[0029] In one or more embodiments, the work machine may further include an output pulley fixed to the output shaft, an input shaft rotatably supported in the housing, an input pulley fixed to the input shaft, and a transmission belt stretched between the input pulley and the output pulley. The prime mover may rotationally drive the input shaft to rotationally drive the output shaft. The work machine may function as a power cutter.

[0030] Among working machines, power cutters, which rotate the rotary blade with a relatively large torque, are likely to generate torque on the blade cover that causes the first stopper receiving portion to ride up onto the first stopper portion. With the above configuration, excessive rotation of the blade cover can be appropriately suppressed in the power cutter.

[0031] (Example) (Configuration of Power Cutter 10) As shown in Figure 1, a power cutter 10, an example of a work machine, is a handheld power tool primarily used to cut materials such as stone and iron. The power cutter 10 includes a rotary blade 12, a housing main body 14a, a blade arm 14b, a blade cover 16, a front handle 18, a rear handle 20, a water supply hose 50, multiple battery packs 60, and a guide roller 70. In this specification, the housing main body 14a and the blade arm 14b may be collectively referred to as the "housing 14."

[0032] 2, the power cutter 10 further includes an electric motor 4, a control board 6, a battery interface 24, and a power transmission unit 8. The electric motor 4 is an example of a prime mover.

[0033] (Rotary blade 12) The rotary blade 12 is a disk-shaped blade having multiple cutting edges or grinding wheels on its outer periphery. The rotary blade 12 may be, for example, a diamond wheel. The rotary blade 12 is a so-called consumable item, and is therefore detachably attached to the blade arm 14b. The rotation axis of the rotary blade 12 extends in a direction perpendicular to the longitudinal direction of the blade arm 14b.

[0034] In this specification, when the power cutter 10 is placed on the placement surface H, the direction perpendicular to the placement surface H is defined as the up-down direction, the direction in which the power cutter 10 is placed on the placement surface H is defined as the up-down direction, and the direction from the power cutter 10 toward the placement surface H is defined as the down-down direction. Also, the direction perpendicular to the up-down direction and in which the rotation axis of the rotary blade 12 extends is defined as the left-right direction. The direction perpendicular to the up-down and left-right directions is defined as the front-rear direction, the direction from the rear handle 20 toward the front handle 18 is defined as the forward direction, and the direction from the front handle 18 toward the rear handle 20 is defined as the rearward direction.

[0035] (Guide roller 70) The guide roller 70 is attached below the housing 14. The guide roller 70 has a pair of left and right wheels 72 (see FIG. 1). When the power cutter 10 is placed on the mounting surface H, the pair of left and right wheels 72 are arranged so as not to come into contact with the mounting surface H. A user of the power cutter 10 can stably move the rotary blade 12 forward or backward relative to the object to be cut by performing work while the pair of left and right wheels 72 are in contact with any surface (such as the mounting surface H).

[0036] (Water supply hose 50) As shown in FIG. 1 , the water supply hose 50 is provided on the right side of the power cutter 10. The tip of the water supply hose 50 is connected via a plug 52 to a first side wall portion 162 of the blade cover 16 (described later). The base end of the water supply hose 50 is attached to the lower part of the rear handle 20. A water supply connector 54 is provided at the base end of the water supply hose 50. The water supply connector 54 is held by the housing main body 14a and can be connected to an external water source, such as a water faucet, via a hose (not shown). This allows the water supply hose 50 to supply water into the blade cover 16.

[0037] (Front handle 18 and rear handle 20) The front handle 18 and the rear handle 20 are each provided on the housing body 14a. The front handle 18 extends from above the housing body 14a to the right and left. One end of the front handle 18 is attached near the center of the right side of the housing body 14a, and the other end is attached to the lower part of the left side of the housing body 14a. The rear handle 20 extends rearward from the housing body 14a. Typically, a user holds the power cutter 10 by grasping the front handle 18 with their left hand and the rear handle 20 with their right hand. In this case, the user can adjust the posture of the power cutter 10 by changing the position at which they grasp the front handle 18.

[0038] As shown in Figure 3, the rear handle 20 is equipped with a main switch 30 that can be operated by the user with the fingers of the hand holding the rear handle 20. In this embodiment, when the user operates the main switch 30, the control board 6 (see Figure 2) starts supplying power to the electric motor 4 (see Figure 2), and when the operation of the main switch 30 is released, the control board 6 stops supplying power to the electric motor 4. As will be described in detail later, when power is supplied to the electric motor 4, the rotary blade 12 is driven to rotate. In other words, the power cutter 10 is configured to drive the rotary blade 12 to rotate only while the main switch 30 is being operated.

[0039] The rear handle 20 is further equipped with a lock-off switch 32. The lock-off switch 32 is held on the rear handle 20 so that it can slide left and right. Although not shown, when the lock-off switch 32 is not pushed to the right relative to the rear handle 20, the main switch 30 and the lock-off switch 32 mechanically interfere with each other, prohibiting operation of the main switch 30. When the lock-off switch 32 is pushed to the right relative to the rear handle 20, the main switch 30 and the lock-off switch 32 do not mechanically interfere with each other, allowing operation of the main switch 30.

[0040] The rear handle 20 further includes an operation button 34. In this embodiment, the control board 6 (see FIG. 2) starts or stops the supply of power to an illuminator (not shown) in response to the operation of the operation button 34. In other words, the operation button 34 is a button for switching the illuminator on and off.

[0041] (Multiple Battery Packs 60 and Battery Interface 24) 2, the plurality of battery packs 60 each include at least one secondary battery cell (not shown). The plurality of battery packs 60 are detachably attached to a battery interface 24 provided in the housing main body 14a, and can supply power to the electric motor 4.

[0042] (Control board 6) The control board 6 is housed in the housing main body 14a. The control board 6 is electrically connected to the multiple battery packs 60, adjusts the power supplied from the multiple battery packs 60, and supplies it to the electric motor 4. In this embodiment, since the electric motor 4 is a brushless motor, the control board 6 further includes an inverter circuit (not shown). The inverter circuit electrically connects the multiple battery packs 60 and the electric motor 4, converts DC power from the multiple battery packs 60 into three-phase AC power, and supplies it to the electric motor 4. The control board 6 is also electrically connected to an illuminator (not shown) provided in the housing 14, and can adjust the power supplied from the multiple battery packs 60 and supply it to the illuminator.

[0043] (electric motor 4) The electric motor 4 is accommodated in the housing main body 14a. In this embodiment, the electric motor 4 is a brushless motor, and includes a stator, a rotor, and a motor shaft (not shown). When power is supplied to the electric motor 4, the motor shaft starts to rotate.

[0044] (Power transmission part 8) The power transmission unit 8 includes an input shaft 81, an output shaft 85, an input pulley 82 fixed to the input shaft 81, an output pulley 84 fixed to the output shaft 85, and a transmission belt 83 stretched between the input pulley 82 and the output pulley 84.

[0045] The input shaft 81 and the input pulley 82 are rotatably supported by the housing 14. The rotation axes of the input shaft 81 and the input pulley 82 are arranged along the left-right direction. Although not shown, the input shaft 81 is connected to the motor shaft of the electric motor 4 via a reducer or the like housed in the housing main body 14a. Therefore, when the motor shaft rotates, the input shaft 81 also rotates simultaneously.

[0046] The transmission belt 83 is housed in the blade arm 14b together with the input pulley 82 and the output pulley 84. In this embodiment, the input pulley 82 and the output pulley 84 are toothed pulleys, and the transmission belt 83 is a toothed belt. The input pulley 82 and the transmission belt 83 mesh together. The output pulley 84 and the transmission belt 83 similarly mesh together. Therefore, when the input shaft 81 rotates, the input pulley 82 fixed to the input shaft 81 and the transmission belt 83 cause the output pulley 84 to rotate simultaneously.

[0047] The output pulley 84 and the output shaft 85 are rotatably supported by the housing 14. The rotation axes of the output pulley 84 and the output shaft 85 are arranged along the left-right direction. The rotary blade 12 is attached to the output shaft 85. Therefore, when the output pulley 84 rotates, the rotary blade 12 also rotates simultaneously via the output shaft 85. At this time, the rotary blade 12 rotates around the same rotation axis as the output shaft 85.

[0048] As described above, the power transmission unit 8 transmits power from the electric motor 4 to the rotary blade 12. This enables the rotary blade 12 to be rotationally driven by the electric motor 4 in the power cutter 10. In the power cutter 10 of this embodiment, the rotary blade 12 is configured to be rotationally driven in a predetermined rotation direction. In the power cutter 10 of this embodiment, the rotary blade 12 is configured to be rotationally driven clockwise when the power cutter 10 is viewed from the right.

[0049] (Blade Cover 16) As shown in FIG. 1, the blade cover 16 is disposed near the front end of the blade arm 14b and is attached to the blade arm 14b so as to be rotatable around the rotation axis of the output shaft 85 (see FIG. 2). That is, the rotation axis A (see FIG. 4) of the blade cover 16 extends along the left-right direction. Hereinafter, with respect to the rotation direction of the blade cover 16, a clockwise direction when the power cutter 10 is viewed from the right is defined as a first direction, and a counterclockwise direction when the power cutter 10 is viewed from the right is defined as a second direction. In this definition, the first direction corresponds to the forward direction of the rotation direction of the rotary blade 12, and the second direction corresponds to the reverse direction of the rotation direction of the rotary blade 12.

[0050] In this embodiment, an elastic member (not shown) that is pressed in the left-right direction is provided between the blade cover 16 and the blade arm 14b. Therefore, the blade cover 16 can be rotated only when the blade cover 16 is rotated against the frictional force that the elastic member exerts on the blade cover 16. In addition, a grip 160 that the user can hold is provided on the radial outer side of the blade cover 16. By holding the grip 160, the user can rotate the blade cover 16 relatively easily.

[0051] The blade cover 16 includes a first side wall 162 that covers a portion of the right side surface of the rotary blade 12, a second side wall 164 (see FIG. 6 ) that covers a portion of the left side surface of the rotary blade 12, and a peripheral wall 166 that connects the first side wall 162 and the second side wall 164 and covers a portion of the outer periphery of the rotary blade 12. In this embodiment, the first side wall 162, the second side wall 164, and the peripheral wall 166 are seamlessly formed as a single unit. A magnesium alloy is used for the first side wall 162, the second side wall 164, and the peripheral wall 166. In this embodiment, the first side wall 162 and the second side wall 164 each cover an angular range of 175° or more of the side surface of the rotary blade 12. Therefore, the blade cover 16 prevents dust generated by the rotary blade 12 from scattering toward the user.

[0052] As shown in FIG. 4 , the first side wall portion 162 includes a first stopper portion 110, a second stopper portion 120, and a third stopper portion 130. In this embodiment, the first stopper portion 110, the second stopper portion 120, and the third stopper portion 130 are seamlessly and integrally formed with the first side wall portion 162. For this reason, the first stopper portion 110, the second stopper portion 120, and the third stopper portion 130 are made of a magnesium alloy, as are the first side wall portion 162. The first stopper portion 110 is disposed relatively far from the rotation axis A of the blade cover 16. The second stopper portion 120 is disposed as close to the rotation axis A as possible without interfering with the attachment of the blade cover 16 to the blade arm 14b. The third stopper portion 130 is disposed between the first stopper portion 110 and the second stopper portion 120 in the radial direction of the rotation axis A.

[0053] The first stopper portion 110 is provided to protrude rightward from the first side wall portion 162. The first stopper portion 110 has, on the first direction side, a first stopper surface 112 that is approximately perpendicular to the circumferential direction of the rotation axis A. The first stopper portion 110 further has, on the second direction side of the first stopper surface 112, a first rib 114 that extends along the circumferential direction of the rotation axis A.

[0054] The second stopper portion 120 is provided to protrude rightward from the first side wall portion 162. The second stopper portion 120 has, on the first direction side, a second stopper surface 122 that is approximately perpendicular to the circumferential direction of the rotation axis A. The second stopper portion 120 further has, on the second direction side of the second stopper surface 122, a second rib 124 that extends along the circumferential direction of the rotation axis A.

[0055] The third stopper portion 130 is provided to protrude rightward from the first side wall portion 162. The third stopper portion 130 has, on the second direction side, a third stopper surface 132 that is approximately perpendicular to the circumferential direction of the rotation axis A. The third stopper portion 130 further has, on the first direction side of the third stopper surface 132, a third rib 134 that extends along the circumferential direction of the rotation axis A.

[0056] (Blade Arm 14b) As shown in FIG. 5, the blade arm 14b has a facing portion 142 that faces the right surface of the first side wall portion 162 (see FIG. 4) of the blade cover 16. In this embodiment, a magnesium alloy is used for the facing portion 142. The facing portion 142 is provided with, in order from the front, a second stopper receiving portion 220, a third stopper receiving portion 230, and a first stopper receiving portion 210 along the longitudinal direction of the blade arm 14b. The facing portion 142 also has a longitudinal rib 144 that connects to the first stopper receiving portion 210, the second stopper receiving portion 220, and the third stopper receiving portion 230 and extends along the longitudinal direction of the blade arm 14b. In this embodiment, the first stopper receiving portion 210, the second stopper receiving portion 220, the third stopper receiving portion 230, and the longitudinal rib 144 are seamlessly and integrally formed. For this reason, the first stopper receiving portion 210, the second stopper receiving portion 220, the third stopper receiving portion 230 and the longitudinal rib 144 are made of a magnesium alloy, just like the facing portion 142.

[0057] The first stopper receiving portion 210 is provided to protrude leftward from the facing portion 142. The first stopper receiving portion 210 extends along the short side direction of the blade arm 14b.

[0058] The second stopper receiving portion 220 is provided to protrude leftward from the opposing portion 142. The second stopper receiving portion 220 is provided to extend in the circumferential direction of the rotation axis A (see FIG. 4) of the blade cover 16. The second stopper receiving portion 220 has, on the second direction side, a second stopper receiving surface 222 that is approximately perpendicular to the circumferential direction of the rotation axis A.

[0059] The third stopper receiving portion 230 is provided to protrude leftward from the opposing portion 142. The third stopper receiving portion 230 has a substantially cylindrical shape.

[0060] (Blade cover 16 over-rotation suppression mechanism)

[0061] 6, when the power cutter 10 is viewed from below, the first stopper portion 110, the second stopper portion 120, the third stopper portion 130, the first stopper receiving portion 210, the second stopper receiving portion 220, the third stopper receiving portion 230, and the longitudinal rib 144 are arranged on a reference plane P that extends in the front-to-rear and up-down directions. The following description will be given using a cross-sectional view of the reference plane P.

[0062] (Suppression of excessive rotation of the blade cover 16 in the first direction) As shown in Fig. 7, when the blade cover 16 is rotated in the first direction, the first stopper portion 110 abuts against the first stopper receiving portion 210 from the second direction side at a first abutment position p1. When the first stopper portion 110 abuts against the first stopper receiving portion 210, the first stopper portion 110 and the first stopper receiving portion 210 exert reaction forces on each other, thereby restricting the rotation of the blade cover 16 in the first direction. Note that in the state shown in Fig. 7, the second stopper portion 120 and the second stopper receiving portion 220 are not in contact with each other.

[0063] When the first stopper portion 110 is in contact with the first stopper receiving portion 210, the angle θ1 formed by the line passing through the second stopper surface 122 and the rotation axis A and the line passing through the second stopper receiving surface 222 and the rotation axis A is within the range of 0° to 2°. In this embodiment, when the first stopper portion 110 is in contact with the first stopper receiving portion 210, the angle θ1 formed by the line passing through the second stopper surface 122 and the rotation axis A and the line passing through the second stopper receiving surface 222 and the rotation axis A is 1°. Therefore, when the blade cover 16 is further rotated in the first direction from the state in which the first stopper portion 110 is in contact with the first stopper receiving portion 210, after the first stopper portion 110 has rotated by 1°, the second stopper surface 122 abuts against the second stopper receiving surface 222 from the second direction side. Although not shown, when the second stopper portion 120 abuts against the second stopper receiving portion 220, the second stopper portion 120 and the second stopper receiving portion 220 exert a reaction force on each other, thereby suppressing the rotation of the blade cover 16 in the first direction. The position where the second stopper portion 120 abuts against the second stopper receiving portion 220 (second abutment position p2) is the position of the second stopper receiving surface 222. The second abutment position p2 is offset radially inward from the first abutment position p1 with respect to the rotation axis A.

[0064] As described above, normally, only the first stopper portion 110 and the first stopper receiving portion 210 function to prevent excessive rotation of the blade cover 16 in the first direction. The second stopper portion 120 and the second stopper receiving portion 220 function as a backup when, for example, the first stopper receiving portion 210 rides up on the first stopper portion 110. Therefore, excessive rotation of the blade cover 16 in the first direction is prevented in two stages.

[0065] (Suppression of excessive rotation of the blade cover 16 in the second direction) 8, when the blade cover 16 is rotated in the second direction, the third stopper portion 130 abuts against the third stopper receiver 230 from the first direction side at a third abutment position p3. The third abutment position p3 is offset radially inward from the first abutment position p1 in the radial direction of the rotation axis A, and is offset radially outward from the second abutment position p2 in the radial direction of the rotation axis A. When the third stopper portion 130 abuts against the third stopper receiver 230, the third stopper portion 130 and the third stopper receiver 230 exert reaction forces on each other, thereby restricting rotation of the blade cover 16 in the second direction.

[0066] (Blade cover 16 movement range) Furthermore, when the third stopper portion 130 is in contact with the third stopper receiving portion 230, the angle θ2 formed by the line passing through the first stopper surface 112 and the rotation axis A and the line passing through the first contact position p1 and the rotation axis A is 65°. Therefore, the movable range of the blade cover 16 is normally limited to within an angular range of 65° by the first stopper portion 110, the first stopper receiving portion 210, the third stopper portion 130, and the third stopper receiving portion 230.

[0067] 9, as long as the blade cover 16 is rotated within the above-described movable range, the blade cover 16 is configured to always cover a predetermined range S1 of the rotary blade 12. In this embodiment, the predetermined range S1 is behind the rotary blade 12 and is an angular range of approximately 110° around the entire circumference of the rotary blade 12. Because the user works while standing behind the rotary blade 12, the blade cover 16 of this embodiment can more appropriately prevent dust from scattering toward the user.

[0068] (Variation) In the above embodiment, the power cutter 10 has been described as an example of a working machine. In another embodiment, the working machine may be a working machine other than the power cutter 10. For example, the working machine may be an electric circular saw, a grinder, or the like.

[0069] In the above embodiment, a configuration has been described in which the electric motor 4 is provided as an example of the prime mover. In another embodiment, the prime mover may be a prime mover other than the electric motor 4. For example, the prime mover may be an engine.

[0070] In the above embodiment, the electric motor 4 is a brushless motor. In another embodiment, the electric motor 4 may be a motor other than a brushless motor. For example, the electric motor 4 may be a motor with brushes.

[0071] In the above embodiment, a configuration has been described in which the motor shaft of the electric motor 4 is connected to the input shaft 81 via a reducer or the like. In another embodiment, the motor shaft of the electric motor 4 may be connected to the input shaft 81 without a reducer or the like. In other words, the motor shaft of the electric motor 4 may function as the input shaft 81.

[0072] In the above embodiment, the input pulley 82 and the output pulley 84 are toothed pulleys, the transmission belt 83 is a toothed belt, and a configuration has been described in which power is transmitted between the input pulley 82, the transmission belt 83, and the output pulley 84 mainly by meshing of the teeth. In another embodiment, the input pulley 82 and the output pulley 84 may be pulleys other than toothed pulleys, and the transmission belt 83 may be a belt other than a toothed belt. For example, the input pulley 82 and the output pulley 84 may be V-grooved pulleys, and the transmission belt 83 may be a flat belt or a V-belt. In this case, power is transmitted between the input pulley 82, the transmission belt 83, and the output pulley 84 mainly by friction between the members.

[0073] In the above embodiment, a configuration has been described in which the work machine (power cutter 10) is equipped with multiple battery packs 60, and power is supplied from the multiple battery packs 60 to the electric motor 4. In another embodiment, the work machine (power cutter 10) may be equipped with a power cord that connects to an external power source instead of the multiple battery packs 60, and power may be supplied from the external power source to the electric motor 4 via the power cord. In yet another embodiment, the work machine (power cutter 10) may be equipped with a single battery pack instead of the multiple battery packs 60.

[0074] In the above embodiment, the configuration has been described in which the plurality of battery packs 60 is two battery packs. In another embodiment, the plurality of battery packs 60 may be three or more battery packs. For example, the plurality of battery packs 60 may be four battery packs.

[0075] In the above embodiment, the rotary blade 12 is configured to be driven to rotate clockwise when viewed from the right of the power cutter 10. In another embodiment, the rotary blade 12 may be configured to be driven to rotate counterclockwise when viewed from the right of the power cutter 10.

[0076] In the above embodiment, the rotary blade 12 is configured to be rotationally driven in a predetermined rotation direction. In another embodiment, the user may be able to arbitrarily select the rotation direction of the rotary blade 12, and the rotary blade 12 may be configured to be rotationally driven in the rotation direction selected by the user.

[0077] In the above embodiment, a configuration has been described in which a magnesium alloy is used for the first side wall portion 162, the second side wall portion 164, and the peripheral wall portion 166. In another embodiment, a material other than a magnesium alloy may be used for the first side wall portion 162, the second side wall portion 164, and the peripheral wall portion 166. For example, an aluminum alloy or the like may be used for the first side wall portion 162, the second side wall portion 164, and the peripheral wall portion 166.

[0078] In the above embodiment, a configuration has been described in which three sets of stoppers (first stopper portion 110 and first stopper receiving portion 210, second stopper portion 120 and second stopper receiving portion 220, and third stopper portion 130 and third stopper receiving portion 230) are provided in first side wall portion 162 and opposing portion 142. In another embodiment, four or more sets of stoppers may be provided in first side wall portion 162 and opposing portion 142. In yet another embodiment, only two sets of stoppers may be provided in first side wall portion 162 and opposing portion 142. In this case, third stopper portion 130 and third stopper receiving portion 230 may not be provided, and only first stopper portion 110 and first stopper receiving portion 210 and second stopper portion 120 and second stopper receiving portion 220 may be provided.

[0079] In the above embodiment, a configuration has been described in which the first stopper portion 110, the second stopper portion 120, and the third stopper portion 130 are seamlessly and integrally formed with the first side wall portion 162. In another embodiment, at least one of the first stopper portion 110, the second stopper portion 120, and the third stopper portion 130 may be formed separately from the first side wall portion 162. In this case, at least one of the first stopper portion 110, the second stopper portion 120, and the third stopper portion 130 formed separately from the first side wall portion 162 may be made of a material other than a magnesium alloy, such as an aluminum alloy.

[0080] In the above embodiment, a magnesium alloy is used for the facing portion 142. In another embodiment, a material other than a magnesium alloy may be used for the facing portion 142. For example, an aluminum alloy or the like may be used for the facing portion 142.

[0081] In the above embodiment, a configuration has been described in which the first stopper receiving portion 210, the second stopper receiving portion 220, and the third stopper receiving portion 230 are seamlessly and integrally formed with the opposing portion 142. In another embodiment, at least one of the first stopper receiving portion 210, the second stopper receiving portion 220, and the third stopper receiving portion 230 may be formed separately from the opposing portion 142. In this case, at least one of the first stopper receiving portion 210, the second stopper receiving portion 220, and the third stopper receiving portion 230 formed separately from the opposing portion 142 may be made of a material other than a magnesium alloy, such as an aluminum alloy.

[0082] In the above embodiment, a configuration has been described in which the angle θ1 formed by the line passing through the second stopper surface 122 and the rotation axis A and the line passing through the second stopper receiving surface 222 and the rotation axis A is within a range of 0°-2° when the first stopper portion 110 is in contact with the first stopper receiving portion 210. In another embodiment, the angle θ1 formed by the line passing through the second stopper surface 122 and the rotation axis A and the line passing through the second stopper receiving surface 222 and the rotation axis A when the first stopper portion 110 is in contact with the first stopper receiving portion 210 may be within a range of 0°-30° or within a range of 0°-90°.

[0083] In the above embodiment, the second abutment position p2 is offset radially inward from the first abutment position p1 in the radial direction of the rotation axis A, and the third abutment position p3 is offset radially inward from the first abutment position p1 and radially outward from the second abutment position p2 in the radial direction of the rotation axis A. In another embodiment, the first abutment position p1, the second abutment position p2, and the third abutment position p3 may have any positional relationship. For example, the first abutment position p1 may be offset radially inward from the second abutment position p2 in the radial direction of the rotation axis A, and the third abutment position p3 may be offset radially outward from the second abutment position p2 in the radial direction of the rotation axis A.

[0084] In the above embodiment, a configuration has been described in which the angle θ2 formed by the line passing through the first stopper surface 112 and the rotation axis A and the line passing through the first abutment position p1 and the rotation axis A is 65° when the third stopper portion 130 is in contact with the third stopper receiving portion 230. In another embodiment, the angle θ2 formed by the line passing through the first stopper surface 112 and the rotation axis A and the line passing through the first abutment position p1 and the rotation axis A when the third stopper portion 130 is in contact with the third stopper receiving portion 230 may be an angle other than 65°.

[0085] Unlike the above-described embodiment, the power cutter 10 may further include a battery pack cover that is an openable and closable cover that covers the multiple battery packs 60. In this case, the multiple battery packs 60 can be protected from water and dust.

[0086] Unlike the above-described embodiment, the power cutter 10 may further include a water tank connected to the water supply connector 54. In this case, there is no need to attach a hose or the like to connect the water supply connector 54 to an external water source, which further improves user operability. In addition, the power cutter 10 can be used even in places where water cannot be supplied from an external source, thereby improving user convenience.

[0087] (Correspondence) As described above, in one or more embodiments, the power cutter 10 (an example of a work machine) includes the rotary blade 12, the output shaft 85 to which the rotary blade 12 is attached, the electric motor 4 (an example of a prime mover) that rotates and drives the output shaft 85, the housing 14 that rotatably supports the output shaft 85 and accommodates the electric motor 4, and the blade cover 16 that is attached to the housing 14 so as to be rotatable about a rotation axis A (an example of a rotation axis that approximately coincides with the rotation axis of the output shaft) that coincides with the rotation axis of the output shaft 85. The blade cover 16 includes a first side wall 162 (an example of a side wall) that covers at least a portion of the side surface of the rotary blade 12. The housing 14 includes a facing portion 142 that faces the right surface of the first side wall 162 (an example of a surface opposite to the surface facing the side surface of the rotary blade). The first side wall 162 includes a first stopper portion 110 and a second stopper portion 120. The facing portion 142 includes a first stopper receiving portion 210 and a second stopper receiving portion 220. When the blade cover 16 is rotated in a first direction (an example of one rotation direction of the blade cover), the first stopper portion 110 abuts against the first stopper receiving portion 210 from the second direction (an example of the other rotation direction) at a first abutment position p1. When the blade cover 16 is further rotated in the first direction from a state in which the first stopper portion 110 abuts against the first stopper receiving portion 210, the second stopper portion 120 abuts against the second stopper receiving portion 220 from the second direction at a second abutment position p2.

[0088] According to the above configuration, the first stopper portion 110 abuts against the first stopper receiving portion 210, thereby suppressing excessive rotation of the blade cover 16 in the first direction. Furthermore, according to the above configuration, when the first stopper receiving portion 210 rides up on the first stopper portion 110, for example, and the blade cover 16 is further rotated in the first direction, the second stopper portion 120 abuts against the second stopper receiving portion 220. Therefore, excessive rotation of the blade cover 16 in the first direction is suppressed in two stages. According to the above configuration, excessive rotation of the blade cover 16 can be appropriately suppressed.

[0089] In one or more embodiments, when the first stopper portion 110 abuts the first stopper receiving portion 210, the angle θ1 that the line connecting the second stopper portion 120 and the rotation axis A makes with the line connecting the second stopper receiving portion 220 and the rotation axis A is in the range of 0°-2°.

[0090] If the blade cover 16 is rotated significantly between the state in which the first stopper portion 110 abuts against the first stopper receiving portion 210 and the state in which the second stopper portion 120 abuts against the second stopper receiving portion 220, excessive rotation of the blade cover 16 may not be appropriately suppressed. According to the above configuration, the angle θ1 formed by the line connecting the second stopper portion 120 and the rotation axis A with the line connecting the second stopper receiving portion 220 and the rotation axis A is within the range of 0°-2°. Therefore, from the state in which the first stopper receiving portion 210 abuts against the first stopper portion 110, the second stopper portion 120 abuts against the second stopper receiving portion 220 without the blade cover 16 being rotated significantly. According to the above configuration, excessive rotation of the blade cover 16 can be more appropriately suppressed.

[0091] In one or more embodiments, the first abutment position p1 and the second abutment position p2 are radially offset from one another.

[0092] When the first contact position p1 and the second contact position p2 are not offset from each other in the radial direction of the rotation axis A, the first stopper receiving portion 210 and the second stopper receiving portion 220 provided in the facing portion 142 are disposed so as to at least partially overlap in the circumferential direction of the rotation axis A. According to the above configuration, the first stopper receiving portion 210 and the second stopper receiving portion 220 can be disposed without overlapping in the circumferential direction of the rotation axis A. Therefore, the facing portion 142, in which the first stopper receiving portion 210 and the second stopper receiving portion 220 are provided, can be made smaller in size in the circumferential direction of the rotation axis A.

[0093] In one or more embodiments, the first abutment position p1 is offset radially outward from the second abutment position p2.

[0094] Generally, the blade cover 16 is attached to the housing 14 near the rotation axis A. In this case, when the first stopper receiving portion 210 rides up on the first stopper portion 110, the opposing portion 142 and the first side wall portion 162 move apart as they move away from the rotation axis A. At this time, if the second stopper portion 120 and the second stopper receiving portion 220 are significantly separated from each other, the second stopper portion 120 and the second stopper receiving portion 220 may not abut against each other, and excessive rotation of the blade cover 16 may not be suppressed. According to the above configuration, the second abutment position p2 is offset radially inward from the first abutment position p1, and therefore, when the first stopper receiving portion 210 rides up on the first stopper portion 110, the second stopper portion 120 and the second stopper receiving portion 220 are prevented from moving apart significantly. Therefore, when the first stopper receiving portion 210 rides up on the first stopper portion 110, the second stopper portion 120 and the second stopper receiving portion 220 can be more reliably brought into contact with each other. According to the above configuration, excessive rotation of the blade cover 16 can be more reliably suppressed.

[0095] In one or more embodiments, the first side wall portion 162 further includes a third stopper portion 130. The facing portion 142 further includes a third stopper receiving portion 230. When the blade cover 16 is rotated in the other rotation direction, the third stopper portion 130 abuts against the third stopper receiving portion 230 from the first direction side at a third abutment position p3.

[0096] According to the above configuration, the third stopper portion 130 restrains excessive rotation of the blade cover 16 in the second direction by abutting against the third stopper receiving portion 230. According to the above configuration, not only excessive rotation of the blade cover 16 in the first direction but also excessive rotation of the blade cover 16 in the second direction can be restrained.

[0097] In one or more embodiments, the output shaft 85 is driven to rotate clockwise (an example of a predetermined rotational direction relative to the rotation axis) when the power cutter 10 is viewed from the right. The first direction corresponds to the forward direction of rotation of the output shaft 85. The second direction corresponds to the reverse direction of rotation of the output shaft 85.

[0098] For example, a situation in which torque sufficient to cause the first stopper receiving portion 210 to ride up onto the first stopper portion 110 is generated in the blade cover 16 may occur when the torque of the rotary blade 12 is transmitted to the blade cover 16 via a foreign object or the like that has entered between the rotary blade 12 and the blade cover 16. In this case, torque is generated in the blade cover 16 in a direction that rotates the blade cover 16 in a first direction that corresponds to the forward direction of the rotation of the rotary blade 12. According to the above configuration, the first stopper portion 110 and the second stopper portion 120 can suppress excessive rotation of the blade cover 16 in the first direction that corresponds to the forward direction of the rotation of the rotary blade 12 in two stages. According to the above configuration, when the torque of the rotary blade 12 is transmitted to the blade cover 16, excessive rotation of the blade cover 16 can be more appropriately suppressed.

[0099] In one or more embodiments, at least one of the first stopper portion 110 , the second stopper portion 120 , and the third stopper portion 130 is integrally formed with the first sidewall portion 162 .

[0100] In the manufacturing process of the power cutter 10, it may be desirable to reduce the number of parts of the blade cover 16. According to the above configuration, the number of parts of the blade cover 16 can be reduced compared to when the first stopper portion 110, the second stopper portion 120, and the third stopper portion 130 are attached separately to the first side wall portion 162.

[0101] In one or more embodiments, at least one of the first stopper portion 110 , the second stopper portion 120 , and the third stopper portion 130 is formed separately from the first sidewall portion 162 .

[0102] Typically, when the first stopper portion 110, the second stopper portion 120, and the third stopper portion 130 are formed integrally with the first side wall portion 162, the first stopper portion 110, the second stopper portion 120, and the third stopper portion 130 are made of the same material as that used for the first side wall portion 162. Here, it may be desirable to use a material for the first stopper portion 110, the second stopper portion 120, and the third stopper portion 130 that is different from the material used for the first side wall portion 162. According to the above configuration, at least one of the first stopper portion 110, the second stopper portion 120, and the third stopper portion 130 can be formed using a material that is different from the material used for the first side wall portion 162.

[0103] In one or more embodiments, at least one of the first stopper receiving portion 210 , the second stopper receiving portion 220 , and the third stopper receiving portion 230 is integrally formed with the facing portion 142 .

[0104] In the manufacturing process of the power cutter 10, it may be desirable to reduce the number of parts of the housing 14. According to the above configuration, the number of parts of the housing 14 can be reduced compared to when the first stopper receiving portion 210, the second stopper receiving portion 220, and the third stopper receiving portion 230 are attached separately to the opposing portion 142.

[0105] In one or more embodiments, at least one of the first stopper receiving portion 210 , the second stopper receiving portion 220 , and the third stopper receiving portion 230 is formed separately from the facing portion 142 .

[0106] Typically, when the first stopper receiving portion 210, the second stopper receiving portion 220, and the third stopper receiving portion 230 are formed integrally with the facing portion 142, the first stopper receiving portion 210, the second stopper receiving portion 220, and the third stopper receiving portion 230 are made of the same material as that used for the facing portion 142. Here, it may be desirable to use a different material for the first stopper receiving portion 210, the second stopper receiving portion 220, and the third stopper receiving portion 230 from that used for the facing portion 142. According to the above configuration, at least one of the first stopper receiving portion 210, the second stopper receiving portion 220, and the third stopper receiving portion 230 can be formed using a different material from that used for the facing portion 142.

[0107] In one or more embodiments, the power cutter 10 further includes an output pulley 84 fixed to the output shaft 85, an input shaft 81 rotatably supported in the housing 14, an input pulley 82 fixed to the input shaft 81, and a transmission belt 83 stretched between the input pulley 82 and the output pulley 84. The electric motor 4 drives the input shaft 81 to rotate, thereby driving the output shaft 85 to rotate.

[0108] Among working machines, the power cutter 10, which rotates the rotary blade 12 with a relatively large torque, is likely to generate torque on the blade cover 16 that causes the first stopper receiving portion 210 to ride up onto the first stopper portion 110. With the above-described configuration, the power cutter 10 can appropriately prevent the blade cover 16 from rotating excessively. [Explanation of symbols]

[0109] 4: Electric motor 6: Control board 8: Power transmission section 10: Power cutter 12: Rotary blade 14: Housing 14a: Housing body 14b: Blade Arm 16: Blade cover 18: Front handle 20: Rear handle 24: Battery interface 30: Main switch 32: Lock-off switch 34: Operation button 50: Water supply hose 52: Plug 54: Water supply connector 60: Battery pack 70: Guide roller 72 :Wheel 81: Input shaft 82: Input pulley 83: Transmission belt 84: Output pulley 85: Output shaft 110: First stopper part 112: First stopper surface 114: First Rib 120: Second stopper part 122: Second stopper surface 124: Second Rib 130: Third stopper part 132: Third stopper surface 134: Third Rib 142: Opposing part 144: Longitudinal rib 160: Grip 162: First side wall portion 164: Second side wall portion 166: Peripheral wall part 210: First stopper receiving portion 220: Second stopper receiving part 222: Second stopper receiving surface 230: Third stopper receiving part A: Rotating axis H: Placement surface P: Reference plane S1: Predetermined range p1: 1st contact position p2: 2nd contact position p3: The third connecting position

Claims

1. A rotating blade and an output shaft to which the rotary blade is attached; a prime mover that rotates and drives the output shaft; a housing that rotatably supports the output shaft and accommodates the prime mover; a blade cover attached to the housing so as to be rotatable about a rotation axis that substantially coincides with the rotation axis of the output shaft, The blade cover includes a side wall portion that covers at least a part of a side surface of the rotary blade, the housing includes a facing portion facing a surface of the side wall portion opposite to a surface facing the side surface of the rotary blade, The side wall portion includes a first stopper portion and a second stopper portion, the opposing portion includes a first stopper receiving portion and a second stopper receiving portion, When the blade cover is rotated in one direction of the rotation direction of the blade cover, the first stopper portion abuts against the first stopper receiving portion from the other side of the rotation direction at a first abutment position, When the blade cover is further rotated in one of the rotation directions from a state in which the first stopper portion is in contact with the first stopper receiving portion, the second stopper portion abuts against the second stopper receiving portion from the other side of the rotation direction at a second abutment position.

2. 2. The work machine of claim 1, wherein when the first stopper portion is in contact with the first stopper receiving portion, an angle formed by a line connecting the second stopper portion and the pivot axis with a line connecting the second stopper receiving portion and the pivot axis is in the range of more than 0° and not more than 2°.

3. The work machine according to claim 1 or 2, wherein the first contact position and the second contact position are offset from each other in a radial direction of the rotation shaft.

4. The work machine according to claim 3 , wherein the first contact position is offset radially outward from the second contact position.

5. The side wall portion further includes a third stopper portion, The facing portion further includes a third stopper receiving portion, A work machine according to any one of claims 1 to 4, wherein when the blade cover is rotated in the other direction of the rotation direction, the third stopper portion abuts against the third stopper receiving portion from the one side of the rotation direction at a third abutment position.

6. the output shaft is rotationally driven in a predetermined rotation direction relative to the rotation axis, the one of the rotation directions corresponds to a forward direction of the rotation direction of the output shaft, The work machine according to claim 1 , wherein the other of the rotation directions corresponds to a direction opposite to the rotation direction of the output shaft.

7. The work machine according to claim 1 , wherein at least one of the first stopper portion and the second stopper portion is formed integrally with the side wall portion.

8. The work machine according to claim 1 , wherein at least one of the first stopper portion and the second stopper portion is formed separately from the side wall portion.

9. The work machine according to claim 1 , wherein at least one of the first stopper receiving portion and the second stopper receiving portion is formed integrally with the opposing portion.

10. The work machine according to claim 1 , wherein at least one of the first stopper receiving portion and the second stopper receiving portion is formed separately from the opposing portion.

11. an output pulley fixed to the output shaft; an input shaft rotatably supported in the housing; an input pulley fixed to the input shaft; a transmission belt stretched between the input pulley and the output pulley, the prime mover rotationally drives the input shaft to rotationally drive the output shaft, The work implement according to any one of claims 1 to 10, which functions as a power cutter.

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