Work machine

Abstract

The present invention improves reliability. In a switching mechanism 60 of a driver drill 1, a shift arm 64 is mounted to the outer peripheral portion of a gear case 31 so as to be rotatable about a left-right direction as the axial direction. A second arm portion 64C of the shift arm 64 is formed with a ring-side link portion 64E. The ring-side link portion 64E is passed through an opening portion 31D of the gear case 31 and is linked with a second ring gear 44. Further, a motor spacer 32 is fitted with an arm stopper 66. The arm stopper 66 covers the ring-side link portion 64E from the outer side thereof in the left-right direction, and is disposed on the outer side in the left-right direction of the ring-side link portion 64E, with a small gap therebetween. In this way, the arm stopper 66 can prevent the ring-side link portion 64E from falling off from the opening portion 31D.

Description

Work equipment

[0001] The present invention relates to a work machine.

[0002] In the driver drill (working machine) described in Patent Document 1 below, a transmission mechanism including a planetary gear mechanism transmits the driving force of a motor to a spindle, causing the spindle to rotate and perform processes such as fastening workpieces. The planetary gear mechanism of the driver drill is composed of a three-stage planetary gear mechanism, and the rotation speed of the spindle can be changed by switching the transmission path of the planetary gear mechanism through operation by the operator. Specifically, when the operator operates a switch in the switching mechanism, the second ring of the second-stage planetary gear mechanism moves back and forth, switching between a state in which rotation of the second ring is permitted and a state in which rotation is restricted.

[0003] To explain this switching mechanism, a switching member (not shown) is provided in the housing, and the switch and the second ring are connected by the switching member. This switching member is provided on the outer periphery of the case that houses the planetary gear mechanism, and is connected to the second ring by passing through an opening formed in the case.

[0004] JP 2011-245609 A

[0005] In the driver drill, if the switching member falls off the opening of the case, the connection between the switching member and the second ring will be released. Furthermore, if a lubricant, such as grease, used in the planetary gear mechanism splashes out of the case through the opening, the lubricant may leak from the housing. In these cases, the reliability of the driver drill is reduced, and the driver drill has room for improvement in terms of reliability.

[0006] SUMMARY OF THE INVENTION In consideration of the above, an object of the present invention is to provide a work machine that can improve reliability.

[0007] One or more embodiments of the present invention are a work machine comprising a motor, a transmission mechanism that transmits the driving force of the motor to an output section to rotate the output section, a case that houses the transmission mechanism and has an opening that connects the inside to the outside, a connecting section that is movably attached to the outer periphery of the case, passes through the opening, and is connected to the transmission mechanism, and a retaining section that covers the connecting section from the opening side of the opening and prevents the connecting section from falling off from the opening.

[0008] One or more embodiments of the present invention are a work machine in which the case is formed in a cylindrical shape, one end of the case is provided with a motor spacer that closes one end of the case and supports the drive shaft of the motor, and the anti-detachment portion is integrally formed with the motor spacer.

[0009] In one or more embodiments of the present invention, the motor and the case are housed in a housing, and the retaining portion is integrally provided with the housing.

[0010] One or more embodiments of the present invention are a work machine having a switching member that switches the power transmission path of the transmission mechanism when rotated, wherein the anti-pullout portion is arranged adjacent to the outer peripheral surface of the case, and a recess that accommodates a portion of the switching member is formed on the surface of the anti-pullout portion adjacent to the case.

[0011] One or more embodiments of the present invention may provide improved reliability.

[0012] Fig. 4 is a longitudinal sectional view showing a driver drill according to the present embodiment. Fig. 5 is a longitudinal sectional view showing an enlarged view of the driving force transmission mechanism shown in Fig. 1. Fig. 2 is a perspective view of the gear case shown in Fig. 2, seen from diagonally front left. Fig. 6 is a rear view showing the entire shift arm shown in Fig. 2, seen from the rear. Fig. 7 is a side view of the shift arm shown in Fig. 4, seen from the right, showing the assembled state to the gear case. Fig. 8 is a sectional view of an example in which the arm stopper shown in Fig. 5 is formed on a housing, seen from the rear.

[0013] The driver drill 1 as a work machine according to this embodiment will be described below with reference to the drawings. Note that the arrows UP, FR, and RH shown as appropriate in the drawings respectively indicate the upper side, front side, and right side of the driver drill 1. In the following description, when the up / down, front / rear, and left / right directions are used, they refer to the up / down, front / rear, and left / right directions of the driver drill 1 unless otherwise specified.

[0014] As shown in FIG. 1, the driver drill 1 is configured as an electric tool that attaches a tool tip to a chuck 35 provided at the front end of the driver drill 1 and applies a rotational force to the tool tip to perform fastening processing or the like.

[0015] The driver drill 1 includes a housing 10 that forms the outer shell of the driver drill 1, a motor 20 housed in the housing 10, and a drive force transmission mechanism 30 that transmits the drive force of the motor 20 to a spindle 33. The driver drill 1 also includes a switching mechanism 60 that switches the drive transmission path of the reduction mechanism 40 in the drive force transmission mechanism 30. Each component of the driver drill 1 will be described below.

[0016] (Regarding the Housing 10) The housing 10 is formed into a hollow, generally I-shape when viewed from the right side. Specifically, the housing 10 includes an upper housing portion 10A that forms the upper end of the housing 10 and extends in the front-to-rear direction, a handle portion 10B that extends downward from a central portion of the upper housing portion 10A in the front-to-rear direction, and a lower housing portion 10C that forms the lower end of the housing 10. The housing 10 is composed of multiple housing members that are assembled together to form the housing 10.

[0017] A trigger 12 is provided at the upper end of the handle portion 10B, and the trigger 12 protrudes forward from the handle portion 10B and can be pulled rearward. A switch mechanism 14 is provided on the handle portion 10B behind the trigger 12. The switch mechanism 14 has a switch (not shown), and pulling the trigger 12 switches the switch from off to on.

[0018] A controller 16 is provided in the lower housing portion 10C. A switch of the switch mechanism 14 is electrically connected to the controller 16, and an output signal corresponding to the operation state of the trigger 12 is output from the switch to the controller 16. A battery 18 is also detachably attached to the lower housing portion 10C. The battery 18 is electrically connected to the controller 16, and supplies power to the motor 20.

[0019] (Regarding the Motor 20) The motor 20 is housed in the rear end of the upper housing portion 10A and is electrically connected to the controller 16. The motor 20 includes a drive shaft 21 whose axial direction is the front-to-rear direction, a rotor 22 connected to the drive shaft 21 so as to be rotatable integrally therewith, and a substantially cylindrical stator 23 disposed radially outward of the rotor 22.

[0020] The rear end of the drive shaft 21 is rotatably supported by a rear motor bearing 24 fixed to the housing 10. Meanwhile, the front end portion of the drive shaft 21 is rotatably supported by a front motor bearing 25 fixed to a motor spacer 32. The motor spacer 32 is formed in a generally circular plate shape with its thickness direction in the front-to-rear direction, and is attached to the rear end of a gear case 31 (described later). The front end of the drive shaft 21 protrudes forward of the motor spacer 32 and is disposed within the gear case 31. A pinion gear 21A is provided at the front end of the drive shaft 21.

[0021] (Regarding the driving force transmission mechanism 30) As shown in Figures 1 and 2, the driving force transmission mechanism 30 is composed of a gear case 31 as a case that forms the outer shell of the driving force transmission mechanism 30, a reduction mechanism 40 as a transmission mechanism that transmits the driving force of the motor 20 to the spindle 33, and a clutch mechanism 50 that cuts off the transmission of driving force to the spindle 33 when the transmission torque to the spindle 33 reaches an upper limit value.

[0022] (Regarding the Gear Case 31) As shown in FIG. 3 , the gear case 31 is formed in a generally stepped cylindrical shape with its axial direction aligned in the front-to-rear direction. The diameter of the front portion of the gear case 31 is smaller than the diameter of the rear portion of the gear case 31. The gear case 31 is housed within the front portion of the upper housing portion 10A. The motor spacer 32 described above is fitted into the rear end of the gear case 31, and the rear end of the gear case 31 is closed by the motor spacer 32. A spindle 33 serving as an output section with its axial direction aligned in the front-to-rear direction is provided in the front portion of the gear case 31. The spindle 33 is arranged coaxially with the drive shaft 21 of the motor 20. A front end portion of the spindle 33 is rotatably supported by a bearing 34 provided at the front end of the gear case 31. A chuck 35 is connected to the front end of the spindle 33, and driving force from the motor 20 is transmitted to a tool bit attached to the chuck 35.

[0023] A threaded portion 31A formed by a male screw is formed on the outer periphery of the front portion of the gear case 31, and a nut 51 of a clutch mechanism 50 (described later) is threaded onto the threaded portion 31A. A clutch dial 36 is provided on the radially outer side of the front portion of the gear case 31. The clutch dial 36 is formed in a substantially cylindrical shape that is open to the rear, and is rotatably connected to the gear case 31 via the nut 51 (described later). An insertion hole 36A is formed through the front wall of the clutch dial 36, and the front end of the spindle 33 protrudes forward through the insertion hole 36A.

[0024] (Regarding the Reduction Mechanism 40) As shown in FIG. 2 , the reduction mechanism 40 is housed in the rear portion of the gear case 31. The reduction mechanism 40 is configured with a three-stage planetary gear mechanism. The first-stage planetary gear mechanism in the reduction mechanism 40 has a ring-shaped first ring gear 41. The first ring gear 41 is disposed radially outward of the pinion gear 21A of the motor 20 and is connected to the gear case 31 so as not to rotate relative to the first ring gear 41. Internal teeth are formed on the inner periphery of the first ring gear 41. A plurality of first planetary gears 42 are provided between the internal teeth and the pinion gear 21A, and the first planetary gears 42 are meshed with the pinion gear 21A and the first ring gear 41. A first disk-shaped first carrier 43 is provided in front of the pinion gear 21A, and the first planetary gears 42 are rotatably supported by the first carrier 43. That is, the pinion gear 21A functions as a sun gear. A sun gear 43A is formed at the center of the first carrier 43 and protrudes forward.

[0025] The second-stage planetary gear mechanism in the reduction mechanism 40 has a ring-shaped second ring gear 44, which is connected to the radially outer side of the sun gear 43A. The second ring gear 44 is configured to be movable relative to the gear case 31 in the front-to-rear direction. Specifically, the second ring gear 44 is configured to be movable between a rotation restriction position (position shown in FIG. 2 ) and a rotation permission position (not shown) moved rearward from the rotation restriction position. In the rotation restriction position of the second ring gear 44, the second ring gear 44 is connected to the gear case 31 so as not to rotate relative to the gear case 31. On the other hand, in the rotation permission position of the second ring gear 44, the second ring gear 44 is connected to the gear case 31 so as to be rotatable relative to the gear case 31. The second ring gear 44 is configured to be switched between the rotation restriction position and the rotation permission position by a switching mechanism 60, which will be described later. An engagement groove 44A that is open radially outward and extends circumferentially is formed on the outer periphery of the second ring gear 44, and the engagement groove 44A is formed around the entire circumferential circumference of the second ring gear 44.

[0026] Internal teeth are formed on the inner periphery of the second ring gear 44. A plurality of second planetary gears 45 are provided between the internal teeth and the sun gear 43A, and the second planetary gears 45 are meshed with the sun gear 43A and the second ring gear 44. A disc-shaped second carrier 46 is provided in front of the sun gear 43A, and the second planetary gears 45 are rotatably supported by the second carrier 46. A sun gear 46A protruding forward is formed in the center of the second carrier 46.

[0027] The third-stage planetary gear mechanism in the reduction mechanism 40 has a ring-shaped third ring gear 47. The third ring gear 47 is disposed radially outward of the sun gear 46A and rotatably supported by the gear case 31. A plurality of engagement protrusions 47A are formed on the front surface of the third ring gear 47. The engagement protrusions 47A engage with a clutch mechanism 50 (described later), which holds the third ring gear 47 non-rotatably. Internal teeth are formed on the inner periphery of the third ring gear 47. A third planetary gear 48 is provided between the internal teeth and the sun gear 46A, and the third planetary gear 48 meshes with the sun gear 46A and the third ring gear 47. A disk-shaped third carrier 49 is provided in front of the sun gear 46A, and the third planetary gear 48 is rotatably supported by the third carrier 49. A mating hole 49A is formed through the center of the third carrier 49. The rear end of the spindle 33 is connected to the mating hole 49A so as not to rotate relative to the third carrier 49. As a result, the rotational force of the motor 20 is transmitted by the reduction mechanism 40, causing the spindle 33 to rotate.

[0028] That is, as described above, at the rotation restriction position of the second ring gear 44, the rotation of the second ring gear 44 is restricted, and the rotation of the first carrier 43 is decelerated by the second-stage planetary gear mechanism and transmitted to the third carrier 49 and spindle 33. That is, the spindle 33 and the tool bit rotate at a low speed and with high torque. On the other hand, at the rotation permission position of the second ring gear 44, the rotation of the second ring gear 44 is permitted, and the second ring gear 44 rotates together with the first carrier 43 and the second carrier 46. Therefore, the rotation of the first carrier 43 is not decelerated by the second-stage planetary gear mechanism, and the spindle 33 and the tool bit rotate at a high speed and with low torque.

[0029] (Regarding the Clutch Mechanism 50) As shown in FIG. 2 , the clutch mechanism 50 includes a nut 51, a thrust plate 52, a clutch spring 53, and a plurality of balls 54. The nut 51 is formed in a generally cylindrical shape with its axial direction aligned in the front-to-rear direction. A threaded portion 51A is provided on the inner periphery of the nut 51, and a female thread is formed on the threaded portion 51A. The nut 51 is fitted onto the front portion of the gear case 31, and the threaded portion 51A is threadedly engaged with the threaded portion 31A of the gear case 31. A flange portion 51B protruding radially outward is formed on the front end of the nut 51. The flange portion 51B is disposed adjacent to the radially inner side of the clutch dial 36 and is coupled to the clutch dial 36 so as to be rotatable integrally with the clutch dial 36 and rotatable relative thereto in the front-to-rear direction. As a result, when the clutch dial 36 is rotated by an operator, the nut 51 rotates together with the clutch dial 36 relative to the gear case 31. At this time, the nut 51 moves in the front-to-rear direction relative to the gear case 31 and the clutch dial 36 due to the threaded connection between the nut 51 and the gear case 31. Specifically, the nut 51 is configured to be movable between a separated position (a position shown above the spindle 33 in FIG. 2) and an approach position (a position shown below the spindle 33 in FIG. 2) moved rearward from the separated position.

[0030] The thrust plate 52 is formed in a generally annular plate shape with its thickness extending in the front-to-rear direction. The thrust plate 52 is fitted onto the front portion of the gear case 31 and is located at the rear end of the front portion. The clutch spring 53 is configured as a compression coil spring. The clutch spring 53 is fitted onto the nut 51, with the front end of the clutch spring 53 engaged with the flange portion 51B and the rear end of the clutch spring 53 engaged with the thrust plate 52. As a result, the clutch spring 53 urges the thrust plate 52 rearward.

[0031] The ball 54 is inserted into the rear portion of the gear case 31 through a ball hole 31B (see FIG. 3 ) formed in the gear case 31 and is disposed between the thrust plate 52 and the third ring gear 47. As a result, the biasing force of the clutch spring 53 is transmitted to the ball 54 via the thrust plate 52, and the ball 54 presses the third ring gear 47 rearward. When the reduction mechanism 40 is in operation, the engaging protrusion 47A of the third ring gear 47 engages with the ball 54, thereby preventing the third ring gear 47 from rotating and transmitting the driving force of the motor 20 to the spindle 33. On the other hand, when the torque transmitted to the spindle 33 reaches an upper limit during a tightening operation or the like, the ball 54, pressed by the engaging protrusion 47A of the third ring gear 47, is displaced forward together with the thrust plate 52 against the biasing force of the clutch spring 53, and the ball 54 overcomes the engaging protrusion 47A. This causes the third ring gear 47 to rotate, and the transmission of drive power to the spindle 33 is cut off.

[0032] Furthermore, by rotating the clutch dial 36 and moving the nut 51 rearward (toward the approaching position) from the distant position, the amount of compressive deformation of the clutch spring 53 increases, and the biasing force of the clutch spring 53 increases. Therefore, by rotating the clutch dial 36, the upper limit of the torque transmitted to the spindle 33 during tightening or other operations can be changed. Note that when the nut 51 is in the approaching position, the rear end of the nut 51 abuts against the thrust plate 52 from the front. Therefore, the forward movement of the thrust plate 52 is restricted, and the clutch mechanism 50 is set to a non-operating state.

[0033] (Regarding the Switching Mechanism 60) The switching mechanism 60 is configured as a mechanical unit that switches the position of the second ring gear 44 of the reduction mechanism 40 between a rotation restricting position and a rotation permitting position to change the drive transmission path of the reduction mechanism 40. As shown in FIGS. 2 , 4 , and 5 , the switching mechanism 60 includes an operation knob 62 (which is broadly understood as an element that can be understood as a switching operation unit), a shift arm 64 as a switching member, and an arm stopper 66 as a retaining unit that maintains the assembled state of the shift arm 64. The shift arm 64 is assembled to the outer periphery of the gear case 31 and connects the operation knob 62 and the second ring gear 44. For this reason, the assembly portion of the shift arm 64 in the gear case 31 will be described first, and then each component of the switching mechanism 60 will be described.

[0034] As shown in Figures 3 and 5, a pair of left and right mounting bosses 31C are formed on the outer periphery of the rear end portion of the gear case 31 at positions corresponding to the second ring gear 44. The mounting bosses 31C are formed in a generally cylindrical shape with the left-right direction as the axial direction and protrude outward in the left-right direction from the outer periphery of the gear case 31. The mounting bosses 31C are located above the axis of the gear case 31. A pair of left and right openings 31D are formed through the outer periphery of the gear case 31 below the mounting bosses 31C, and the openings 31D connect the interior and exterior of the gear case 31. The vertical positions of the openings 31D are generally aligned with the axis of the gear case 31, and the openings 31D are located radially outward of the engagement groove 44A of the second ring gear 44. The opening 31D is formed in the shape of an approximately elongated hole with the longitudinal direction being the front-to-rear direction, and the length of the opening 31D in the front-to-rear direction is set so that the opening 31D is positioned radially outside the engagement groove 44A, which moves between a rotation restriction position and a rotation permission position.

[0035] As shown in FIGS. 1 and 2 , the operation knob 62 is formed in a generally rectangular, elongated plate shape with its thickness extending vertically and its length extending longitudinally. The operation knob 62 is located above the rear end of the gear case 31 and is coupled to the upper housing portion 10A so as to be slidable in the longitudinal direction. Specifically, the operation knob 62 is slidable between a low-speed position (shown in FIGS. 1 and 2 ) and a high-speed position (not shown) slid forward from the low-speed position. The low-speed position of the operation knob 62 corresponds to a rotation-restricted position of the second ring gear 44, and the high-speed position of the operation knob 62 corresponds to a rotation-permitted position of the second ring gear 44. A knob portion 62A for operating the operation knob 62 is formed in a longitudinally intermediate portion of the operation knob 62. The knob portion 62A protrudes upward relative to the operation knob 62 and is exposed from the upper housing portion 10A so as to be operable upward. A knob groove 62B that is open downward is formed in the front end portion of the lower surface of the operation knob 62, and the knob groove 62B extends in the left-right direction and penetrates in the left-right direction.

[0036] As shown in Figures 2, 4, and 5, the shift arm 64 is made of elastic wire and has a generally inverted U-shape that opens downward when viewed from the rear. Specifically, the shift arm 64 includes a knob-side connecting portion 64A extending in the left-right direction, a pair of left and right first arm portions 64B extending outward in the left-right direction from both longitudinal ends of the knob-side connecting portion 64A and sloping downward as they extend outward in the left-right direction, and a pair of left and right second arm portions 64C extending downward from the lower end of the first arm portion 64B. Support portions 64D are formed at the upper ends of the second arm portions 64C and are wound in a generally circular shape when viewed from the left-right direction. The shift arm 64 is positioned to fit into the upper part of the gear case 31 from above, and a mounting boss 31C of the gear case 31 is inserted into the support portions 64D, so that the shift arm 64 is rotatably supported by the mounting boss 31C. That is, the shift arm 64 is supported on the outer periphery of the gear case 31 so as to be rotatable about its axial direction in the left-right direction.

[0037] The knob-side coupling portion 64A is inserted into the knob groove portion 62B of the operation knob 62 and engages with the operation knob 62 in the front-rear direction. As a result, the shift arm 64 rotates about the axis of the mounting boss 31C in conjunction with the sliding of the operation knob 62 in the front-rear direction, and is positioned at either the low-speed position (position indicated by the solid line in FIG. 5 ) or the high-speed position (position indicated by the two-dot chain line in FIG. 5 ). A ring-side coupling portion 64E is formed at the lower end of the second arm portion 64C as a coupling portion bent inward in the left-right direction. The ring-side coupling portion 64E is inserted into the opening 31D of the gear case 31 so as to be movable in the front-rear direction. The tip of the ring-side coupling portion 64E protrudes into the gear case 31 from the opening 31D and is inserted into the engagement groove 44A of the second ring gear 44, and the ring-side coupling portion 64E and the second ring gear 44 are engaged in the front-rear direction. As a result, the operating knob 62 and the second ring gear 44 are connected by the shift arm 64, and when the operator slides the operating knob 62, the second ring gear 44 switches between a rotation-restricted position or a rotation-permitted position.

[0038] As shown in FIG. 5 , the arm stoppers 66 are provided on the left and right outer sides of the second arm portion 64C of the shift arm 64. The arm stoppers 66 are formed in a generally rectangular plate shape with the plate thickness direction in the left-right direction and the longitudinal direction in the front-rear direction. The rear end of the arm stopper 66 is connected to the outer periphery of the motor spacer 32. That is, the arm stopper 66 is formed integrally with the motor spacer 32. The arm stopper 66 is disposed adjacent to the lower end of the second arm portion 64C of the shift arm 64 on the left-right outer side with a small gap therebetween. That is, the arm stopper 66 covers the lower end of the second arm portion 64C from the opening side of the opening 31D of the gear case 31. The outer shape of the arm stopper 66 is set so that the arm stopper 66 covers the entire opening 31D when viewed from the left-right outer side. That is, the arm stopper 66 is set to cover the lower end of the second arm portion 64C within the rotation range of the lower end of the second arm portion 64C. The inner surface of the arm stopper 66 (the surface facing the outer peripheral surface of the gear case 31) is positioned spaced outward in the left-right direction from the outer peripheral surface of the gear case 31 so as to allow the operating knob 62 to rotate.

[0039] (Operation and Effect) Next, the operation and effect of this embodiment will be described.

[0040] In the driver drill 1 configured as described above, when the operator pulls the trigger 12 to drive the motor 20, the driving force of the motor 20 is transmitted to the spindle 33 via the speed reduction mechanism 40, causing the tool bit to rotate together with the spindle 33. Furthermore, when the torque transmitted to the spindle 33 reaches an upper limit, the clutch mechanism 50 is activated, cutting off the transmission of drive force to the spindle 33. Specifically, the third ring gear 47 of the speed reduction mechanism 40 rotates relative to the ball 54 against the biasing force of the clutch spring 53, thereby cutting off the transmission of drive force to the spindle 33. Furthermore, by rotating the clutch dial 36 and moving the nut 51 rearward, the amount of compressive deformation of the clutch spring 53 increases. This allows the operator to change the upper limit of the torque transmitted to the spindle 33.

[0041] Furthermore, by operating the operation knob 62 of the switching mechanism 60, the operator switches the drive transmission path of the reduction gear mechanism 40 and sets the rotational torque of the tool bit to low or high. This allows the rotational torque of the tool bit to be switched between low and high depending on the type of work, such as tightening. Specifically, by setting the operation knob 62 to the low-speed position, the shift arm 64 positions the second ring gear 44 in the rotation-restricted position, and the rotational torque of the tool bit becomes high. On the other hand, by setting the operation knob 62 to the high-speed position, the shift arm 64 positions the second ring gear 44 in the rotation-permitted position, and the rotational torque of the tool bit becomes low.

[0042] In the switching mechanism 60 for switching the drive transmission path of the reduction mechanism 40, a shift arm 64 is attached to the outer periphery of the gear case 31 so as to be rotatable about its axis in the left-right direction. A ring-side coupling portion 64E is formed on a second arm portion 64C of the shift arm 64. The ring-side coupling portion 64E is inserted through an opening 31D of the gear case 31 and into an engagement groove 44A of a second ring gear 44 of the reduction mechanism 40. This connects the ring-side coupling portion 64E and the second ring gear 44 together by the shift arm 64. In addition, an arm stopper 66 is provided on the motor spacer 32 closing the rear end of the gear case 31. The arm stopper 66 covers the ring-side coupling portion 64E from the outside in the left-right direction and is positioned outside the ring-side coupling portion 64E with a small gap therebetween. Therefore, the arm stopper 66 limits the outward displacement of the ring-side coupling portion 64E in the left-right direction (the opening side of the opening 31D). As a result, the arm stopper 66 can prevent the ring-side connecting portion 64E from falling off from the opening 31D. The arm stopper 66 can also prevent lubricant such as grease from scattering from the opening 31D inside the gear case 31. As a result, it is possible to prevent lubricant such as grease from leaking from the housing 10. As a result, the reliability of the driver drill 1 can be improved.

[0043] As described above, the arm stopper 66 covers the lower end of the second arm portion 64C of the shift arm 64 from the outside in the left-right direction. That is, the arm stopper 66 also functions as a protector member that protects the second arm portion 64C. This prevents the ring-side connecting portion 64E of the shift arm 64 from falling off the opening 31D of the gear case 31, even if an operator touches the shift arm 64 during assembly of the housing 10, for example. This improves the ease of assembly of the driver drill 1.

[0044] Furthermore, as described above, the arm stopper 66 is formed integrally with the motor spacer 32. This allows the arm stopper 66 to be provided by utilizing the motor spacer 32 that supports the drive shaft 21 of the motor 20. This contributes to reducing the number of parts of the driver drill 1 and also contributes to cost reduction.

[0045] In the present embodiment, the arm stopper 66 is formed in a generally rectangular plate shape with its thickness in the left-right direction and extending in the front-rear direction, and is disposed at a distance outside the gear case 31 in the left-right direction. In other words, a predetermined gap is formed between the arm stopper 66 and the outer periphery of the gear case 31 to accommodate the second arm portion 64C of the shift arm 64. Alternatively, the arm stopper 66 may be configured to be disposed adjacent to the radially outer side of the gear case 31. That is, the plate thickness of the arm stopper 66 may be made thicker than in the present embodiment, and a recess 66A (see recess 66A indicated by dotted lines in FIG. 5 ) that accommodates the shift arm 64 may be formed on the inner surface of the arm stopper 66 (the surface facing the gear case 31). In this case, even if the arm stopper 66 deforms inward in the left-right direction due to aging or the like, the inner surface of the arm stopper 66 abuts against the outer peripheral surface of the gear case 31, preventing the arm stopper 66 from contacting the second arm portion 64C of the shift arm 64. This allows the shift arm 64 to maintain proper operation. Furthermore, because the portion of the arm stopper 66 other than the recess 66A is positioned adjacent to the outer peripheral surface of the gear case 31, lubricant such as grease that has leaked into the recess 66A from the opening 31D is prevented from falling between the gear case 31 and the arm stopper 66. As a result, the reliability of the driver drill 1 can be further improved.

[0046] In addition, in this embodiment, the arm stopper 66 is provided integrally with the motor spacer 32, but the arm stopper 66 may be configured separately from the motor spacer 32 and fixed to the motor spacer 32, thereby integrating the arm stopper 66 with the motor spacer 32.

[0047] Furthermore, the arm stopper 66 may be provided on a member other than the motor spacer 32. For example, as shown in Fig. 6, the arm stopper 66 may be integrally formed on the inner peripheral surface of the upper housing portion 10A and disposed adjacent to the outer side of the second arm portion 64C of the shift arm 64 in the left-right direction.

[0048] DESCRIPTION OF SYMBOLS 1...Driver drill (working machine), 10...Housing, 20...Motor, 31...Gear case (case), 31D...Opening, 32...Motor spacer, 33...Spindle (output part), 40...Reduction mechanism (transmission mechanism), 64...Shift arm (switching member), 64E...Ring side connecting part (connecting part), 66...Arm stopper (retaining part), 66A...Recess

Claims

1. A motor; a transmission mechanism for transmitting a driving force of the motor to an output portion to rotate the output portion; a case that houses the transmission mechanism and has an opening that communicates with the inside and the outside; a motor spacer that closes one end of the case and supports a drive shaft of the motor; a switching mechanism for switching a drive transmission path of the transmission mechanism, the switching mechanism including: a switching operation unit; a switching member movably attached to an outer periphery of the case and connecting the switching operation unit and the transmission mechanism; and a connecting portion formed on the switching member, inserted into the opening, and connected to the transmission mechanism; a retaining portion for maintaining an assembled state of the switching member, the retaining portion being integrally provided on the motor spacer, extending from the motor spacer toward an outside of the opening, and covering the connecting portion and at least a part of the opening from the outside of the opening; A work machine equipped with the above.

2. A work machine as described in Claim 1, wherein the anti-slip portion is arranged with a gap on the outside of the connecting portion.

3. The retaining portion is disposed adjacent to an outer peripheral surface of the case, The work machine according to claim 1 , wherein a recess is formed on an inner surface of the retaining portion that faces the outer circumferential surface of the case, the recess accommodating a part of the connecting portion.

4. The connecting portion has a tip portion that is inserted into the opening, The work machine according to claim 1 , wherein the retaining portion covers the tip portion.