Work equipment

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

Technical Field

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

Background Art

[0002] In the driver drill (working machine) described in Patent Document 1 below, the driving force of the motor is transmitted to the spindle by a transmission mechanism composed of a planetary gear mechanism, and the spindle rotates to perform tightening processing on a workpiece. The planetary gear mechanism of the driver drill is composed of a three-stage planetary gear mechanism section, and the rotation speed of the spindle can be changed by switching the transmission path of the planetary gear mechanism by the operation of an operator. Specifically, when the operator operates the switch of the switching mechanism, the second ring of the second-stage planetary gear mechanism section moves back and forth, and switches to a state where the rotation of the second ring is permitted or restricted.

[0003] Regarding 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 peripheral portion of the case that houses the planetary gear mechanism, and is connected to the second ring through an opening formed in the case.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In the above-mentioned driver drill, if the switching member were to fall out of the opening of the case, the connection between the switching member and the second ring would be released. Also, for example, if lubricant such as grease used in the planetary gear mechanism were to scatter from the opening of the case to the outside of the case, there is a risk that the lubricant would leak from the housing. Therefore, in these cases, the reliability of the driver drill would decrease, and there is room for improvement in terms of enhancing the reliability of the above-mentioned driver drill.

[0006] The present invention aims to provide a work machine that can improve reliability, taking the above facts into consideration. [Means for solving the problem]

[0007] One or more embodiments of the present invention provide a motor and a device that transmits the driving force of the motor to an output unit to rotate the output unit. Reduction mechanism and, A chuck is connected to the front end of the output unit, the driving force of the motor is transmitted via the reduction mechanism and the output unit, and a tip tool can be attached to it. The aforementioned Reduction mechanism A case that houses the motor and has an opening that allows communication between the inside and outside, a motor spacer that closes one end of the case and supports the drive shaft of the motor, and Reduction mechanism A switching mechanism for switching the drive transmission path, Operated by the worker A switching operation unit and a movably mounted part on the outer circumference of the case, the switching operation unit and the Reduction mechanism A switching member that connects the two, and a member formed on the switching member that is inserted into the opening and the Reduction mechanism A connecting part connected to and When the operator operates the switching control unit, the drive transmission path of the reduction mechanism is switched, and the rotational torque of the tip tool is switched. Switching mechanism and the switching member The connecting portion prevents the connecting member from falling out of the opening, which would cause the connection between the switching operation unit and the reduction mechanism to be disconnected. The work machine is equipped with a retaining portion for preventing detachment, which is integrally provided with the motor spacer, extends from the motor spacer toward the outside of the opening, and covers the connecting portion and at least a part of the opening from the outside.

[0008] One or more embodiments of the present invention are: The retaining portion is positioned outside the connecting portion with a gap between them. It is a work machine.

[0009] One or more embodiments of the present invention are: The retaining portion is positioned adjacent to the outer circumferential surface of the case, and a recess is formed on the inner surface of the retaining portion facing the outer circumferential surface of the case to accommodate a part of the connecting portion. It is a work machine.

[0010] One or more embodiments of the present invention are: The connecting portion has a tip portion that is inserted into the opening, and the retaining portion covers the tip portion. It is a work machine. [Effects of the Invention]

[0011] According to one or more embodiments of the present invention, reliability can be improved. [Brief explanation of the drawing]

[0012] [Figure 1] This is a longitudinal cross-sectional view showing a driver drill according to this embodiment. [Figure 2] This is a magnified longitudinal cross-sectional view of the drive force transmission mechanism shown in Figure 1. [Figure 3] Figure 2 is a perspective view of the gear case, taken from the left front. [Figure 4] Figure 2 is a rear view of the entire shift arm, as seen from the rear. [Figure 5] Figure 4 is a side view from the right, showing the assembly state of the shift arm into the gear case. [Figure 6] Figure 5 is a rear-view cross-sectional view showing an example of an arm stopper formed on the housing. [Modes for carrying out the invention]

[0013] The following description will explain the driver drill 1 as a work machine according to this embodiment, using the drawings. The arrows UP, FR, and RH shown in the drawings indicate the top, front, and right sides of the driver drill 1, respectively. In the following description, when using the directions of up / down, front / back, and left / right, unless otherwise specified, these refer to the up / down, front / back, and left / right directions of the driver drill 1.

[0014] As shown in Figure 1, the driver drill 1 is configured as an electric power tool that performs tightening and other operations by attaching a cutting tool to a chuck 35 provided at the front end of the driver drill 1 and applying rotational force to the cutting tool.

[0015] The driver drill 1 includes a housing 10 that forms the outer contour of the driver drill 1, a motor 20 housed in the housing 10, and a driving force transmission mechanism 30 that transmits the driving force of the motor 20 to a spindle 33. Further, the driver drill 1 has a switching mechanism 60 for switching the driving transmission path of a speed reduction mechanism 40 in the driving force transmission mechanism 30. Hereinafter, each component of the driver drill 1 will be described.

[0016] (Regarding the housing 10) When viewed from the right side, the housing 10 is formed in a hollow substantially I-shaped configuration. Specifically, the housing 10 includes an upper housing portion 10A that forms the upper end portion of the housing 10 and extends in the front-rear direction, a handle portion 10B that extends downward from the middle portion in the front-rear direction of the upper housing portion 10A, and a lower housing portion 10C that forms the lower end portion of the housing 10. Note that the housing 10 is composed of a plurality of housing members, and the housing 10 is formed by assembling these housing members to each other.

[0017] A trigger 12 is provided at the upper end portion of the handle portion 10B. The trigger 12 protrudes forward from the handle portion 10B and is configured to be operable to be pulled backward. A switch mechanism 14 is provided on the handle portion 10B at the rear side of the trigger 12. The switch mechanism 14 has a switch (not shown), and when the trigger 12 is pulled, the switch is switched 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 operating state of the trigger 12 is output from the switch to the controller 16. Further, a battery 18 is detachably mounted in the lower housing portion 10C. The battery 18 is electrically connected to the controller 16, and power is supplied to the motor 20 by the battery 18.

[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 consists of a drive shaft 21 whose axial direction is in the front-rear direction, a rotor 22 which is integrally rotatable with respect to the drive shaft 21, and a substantially cylindrical stator 23 which is located 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. On the other hand, 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 substantially disc shape with the front-to-rear direction as the thickness direction and is attached to the rear end of the gear case 31, which will be described later. The front end of the drive shaft 21 protrudes forward of the motor spacer 32 and is located inside the gear case 31. A pinion gear 21A is provided at the front end of the drive shaft 21.

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

[0022] (Regarding the gear case 31) As shown in Figure 3, the gear case 31 is formed in a substantially stepped cylindrical shape with the front-to-back direction as the axial direction, and the diameter of the front part of the gear case 31 is set to be smaller than the diameter of the rear part of the gear case 31. The gear case 31 is housed in the front part of the upper housing part 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, which serves as an output part with the front-to-back direction as the axial direction, is provided in the front part of the gear case 31, and the spindle 33 is arranged coaxially with the drive shaft 21 of the motor 20. The 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 the driving force from the motor 20 is transmitted to the tip tool attached to the chuck 35.

[0023] A threaded portion 31A, composed of male threads, is formed on the outer circumference of the front part of the gear case 31, and the nut 51 of the clutch mechanism 50, which will be described later, is screwed onto the threaded portion 31A. A clutch dial 36 is also provided on the radially outer side of the front part 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, which will be described later. A through hole 36A is formed through the front wall of the clutch dial 36, and the front end of the spindle 33 protrudes forward from the through hole 36A.

[0024] (Regarding the reduction mechanism 40) As shown in Figure 2, the reduction mechanism 40 is housed in the rear of the gear case 31. The reduction mechanism 40 is composed of 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, which is positioned 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 it. Internal teeth are formed on the inner circumference of the first ring gear 41. A plurality of first planetary gears 42 are provided between these internal teeth and the pinion gear 21A, and the first planetary gears 42 mesh with the pinion gear 21A and the first ring gear 41. A first disc-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. In other words, the pinion gear 21A is configured as a sun gear. A sun gear 43A protruding forward is formed in the center of the first carrier 43.

[0025] The second-stage planetary gear mechanism in the reduction gear 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-rear direction. Specifically, it is configured to be movable between a rotation restriction position (position shown in Figure 2) and a rotation permission position (not shown) which is 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 in a way that prevents relative rotation. 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 in a way that allows relative rotation. The second ring gear 44 is 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 is formed on the outer circumference of the second ring gear 44, which is open radially outward and extends circumferentially. The engagement groove 44A is formed around the entire circumference of the second ring gear 44.

[0026] Internal teeth are formed on the inner circumference of the second ring gear 44. Multiple second planetary gears 45 are provided between these internal teeth and the sun gear 43A, and the second planetary gears 45 mesh with the sun gear 43A and the second ring gear 44. A disc-shaped second carrier 46 is provided on the front side 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 planetary gear mechanism in the reduction gear 40 has a ring-shaped third ring gear 47, which is positioned radially outward of the sun gear 46A and rotatably supported by the gear case 31. Multiple engaging protrusions 47A are formed on the front surface of the third ring gear 47. The engaging protrusions 47A engage with a clutch mechanism 50, which will be described later, and the clutch mechanism 50 holds the third ring gear 47 in a non-rotatable position. Internal teeth are formed on the inner circumference of the third ring gear 47. A third planetary gear 48 is provided between these 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 disc-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 in a way that prevents relative rotation. As a result, the rotational force of the motor 20 is transmitted by the reduction mechanism 40, causing the spindle 33 to rotate.

[0028] In other words, as described above, at the rotation restriction position of the second ring gear 44, the rotation of the second ring gear 44 is restricted, so the rotation of the first carrier 43 is reduced by the second-stage planetary gear mechanism and transmitted to the third carrier 49 and spindle 33. That is, the spindle 33 and the cutting tool rotate at 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, so 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 reduced by the second-stage planetary gear mechanism, and the spindle 33 and the cutting tool rotate at high speed and with low torque.

[0029] (Regarding the clutch mechanism 50) As shown in Figure 2, the clutch mechanism 50 is composed of a nut 51, a thrust plate 52, a clutch spring 53, and a plurality of balls 54. The nut 51 is formed in a substantially cylindrical shape with the front-rear direction as its axial direction. A threaded portion 51A is provided on the inner circumference of the nut 51, and a female thread is formed on the threaded portion 51A. The nut 51 is fitted onto the front of the gear case 31, and the threaded portion 51A is screwed into the threaded portion 31A of the gear case 31. In addition, a flange portion 51B that protrudes radially outward is formed on the front end of the nut 51, and the flange portion 51B is positioned close to the radially inward side of the clutch dial 36 and is connected to the clutch dial 36 so as to be able to rotate integrally with the clutch dial 36 and so as to be able to rotate relative to it in the front-rear direction. As a result, when the clutch dial 36 is rotated by an operator, the nut 51 rotates relative to the gear case 31 together with the clutch dial 36. Furthermore, at this time, the screw connection between the nut 51 and the gear case 31 causes the nut 51 to move relative to the gear case 31 and the clutch dial 36 in the front-rear direction. Specifically, the nut 51 is configured to move between a separated position (the position shown above the spindle 33 in Figure 2) and a closer position (the position shown below the spindle 33 in Figure 2) which is a rearward movement from the separated position.

[0030] The thrust plate 52 is formed in a substantially annular shape with the front-to-back direction being the thickness direction. The thrust plate 52 is externally fitted to the front part of the gear case 31 and is located at the rear end of the front part. The clutch spring 53 is configured as a compression coil spring. The clutch spring 53 is externally fitted to the nut 51, the front end of the clutch spring 53 is locked to the flange portion 51B, and the rear end of the clutch spring 53 is locked to the thrust plate 52. As a result, the clutch spring 53 biases the thrust plate 52 toward the rear.

[0031] The ball 54 is inserted into the rear of the gear case 31 through a ball hole 31B (see Figure 3) formed in the gear case 31 and positioned 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 toward the rear. When the reduction mechanism 40 is operated, the engaging projection 47A of the third ring gear 47 engages with the ball 54, holding the third ring gear 47 in a non-rotatable position, and the driving force of the motor 20 is transmitted to the spindle 33. On the other hand, when the torque transmitted to the spindle 33 reaches its upper limit during tightening work, the ball 54, pressed by the engaging projection 47A of the third ring gear 47, is displaced toward the front together with the thrust plate 52 against the biasing force of the clutch spring 53, and the ball 54 overcomes the engaging projection 47A. This causes the third ring gear 47 to rotate, interrupting the transmission of power to the spindle 33.

[0032] Furthermore, by rotating the clutch dial 36 to move the nut 51 from the separated position to the rear (closed position), the amount of compression 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 work can be changed. Note that in the close position of the nut 51, the rear end of the nut 51 abuts the thrust plate 52 from the front. For this reason, the movement of the thrust plate 52 toward the front is restricted, and the clutch mechanism 50 is set to be inactive.

[0033] (Regarding the switching mechanism 60) The switching mechanism 60 is configured as a mechanism for changing the drive transmission path of the reduction mechanism 40 by switching the position of the second ring gear 44 of the reduction mechanism 40 to a rotation restriction position or a rotation permission position. As shown in Figures 2, 4, and 5, the switching mechanism 60 is configured to include an operating knob 62 (broadly understood as an element that can be considered as a switching operation part), a shift arm 64 as a switching member, and an arm stopper 66 as a retaining part for maintaining the assembled state of the shift arm 64. The shift arm 64 is assembled to the outer circumference of the gear case 31 and connects the operating knob 62 and the second ring gear 44. For this reason, the assembly part of the shift arm 64 in the gear case 31 will be described first, and then the various components 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 circumference 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 substantially cylindrical shape with the left-right direction as the axial direction and protrude outward in the left-right direction from the outer circumference of the gear case 31. The mounting bosses 31C are positioned above the axis of the gear case 31. A pair of left and right openings 31D are formed through the outer circumference of the gear case 31 below the mounting bosses 31C, and the inside and outside of the gear case 31 are in communication through the openings 31D. Furthermore, the vertical position of the openings 31D is substantially aligned with the axis of the gear case 31, and the openings 31D are positioned radially outward from the engagement groove 44A of the second ring gear 44. The opening 31D is formed in a substantially elongated shape with the front-to-back direction as its longitudinal direction, and the length of the opening 31D in the front-to-back direction is set such that the opening 31D is located radially outward of the engagement groove 44A that moves between the rotation restriction position and the rotation permission position.

[0035] As shown in Figures 1 and 2, the operating knob 62 is formed in the shape of a substantially rectangular, elongated plate with the vertical direction being the thickness direction and the front-to-back direction being the longitudinal direction. The operating knob 62 is positioned above the rear end of the gear case 31 and is slidably connected to the upper housing portion 10A in the front-to-back direction. Specifically, the operating knob 62 is configured to slide between a low-speed position (the position shown in Figures 1 and 2) and a high-speed position (not shown) obtained by sliding forward from the low-speed position. The low-speed position of the operating knob 62 corresponds to the rotation restriction position of the second ring gear 44, and the high-speed position of the operating knob 62 corresponds to the rotation permission position of the second ring gear 44. A knob portion 62A for operating the operating knob 62 is formed in the middle of the operating knob 62 in the front-to-back direction, and the knob portion 62A protrudes upward from the operating knob 62 and is exposed from the upper housing portion 10A so as to be operable upward. A knob groove 62B is formed on the front end portion of the lower surface of the operating 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 an elastic wire and is formed in a substantially inverted U-shape that opens downward when viewed from the rear. Specifically, the shift arm 64 is composed of a knob-side connecting portion 64A that extends in the left-right direction, a pair of left and right first arm portions 64B that extend from both longitudinal ends of the knob-side connecting portion 64A in a direction that slopes downward as it moves outward in the left-right direction, and a pair of left and right second arm portions 64C that extend downward from the lower ends of the first arm portions 64B. A support portion 64D is formed at the upper end of the second arm portion 64C, which is wound in a substantially 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 the mounting boss 31C of the gear case 31 is inserted into the support portion 64D, so that the shift arm 64 is rotatably supported by the mounting boss 31C. In other words, the shift arm 64 is supported on the outer circumference of the gear case 31 so as to be rotatable in the left-right direction as the axial direction.

[0037] The knob-side connecting portion 64A is inserted into the knob groove portion 62B of the operating knob 62 and engages with the operating knob 62 in the front-rear direction. As a result, the shift arm 64 rotates around the axis of the mounting boss 31C in conjunction with the front-rear sliding of the operating knob 62, and is positioned at either the low-speed position (indicated by the solid line in Figure 5) or the high-speed position (indicated by the dashed line in Figure 5). At the lower end of the second arm portion 64C, a ring-side connecting portion 64E is formed as a connecting portion that is bent inward in the left-right direction. The ring-side connecting 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 connecting 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 connecting 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 operating knob 62 is slid by the operator, the second ring gear 44 is switched to the rotation restriction position or the rotation permission position.

[0038] As shown in Figure 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 substantially rectangular plate shape with the left-right direction being the thickness direction and the front-rear direction being the longitudinal direction, and the rear end of the arm stopper 66 is connected to the outer circumference of the motor spacer 32. In other words, the arm stoppers 66 are formed integrally with the motor spacer 32. The arm stoppers 66 are positioned adjacent to the left and right outer sides of the lower end of the second arm portion 64C of the shift arm 64, with a small gap between them. That is, the arm stoppers 66 cover the lower end of the second arm portion 64C from the opening side of the opening 31D of the gear case 31. Furthermore, the external shape of the arm stoppers 66 is set so that, when viewed from the left and right outer side, the arm stoppers 66 cover the entire opening 31D. In other words, the arm stoppers 66 are 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. Furthermore, the inner surface of the arm stopper 66 (the surface facing the outer surface of the gear case 31) is positioned spaced outward in the left-right direction from the outer surface of the gear case 31 in order to allow rotation of the operating knob 62.

[0039] (Effects and Effects) Next, the effects and functions of this embodiment will be described.

[0040] In the driver drill 1 configured as described above, when the operator pulls the trigger 12, the motor 20 is driven, and the driving force of the motor 20 is transmitted to the spindle 33 by the reduction mechanism 40, causing the cutting tool to rotate together with the spindle 33. Furthermore, when the torque transmitted to the spindle 33 reaches its upper limit, the clutch mechanism 50 is activated, and the drive transmission to the spindle 33 is interrupted. Specifically, the third ring gear 47 of the reduction mechanism 40 rotates relative to the ball 54 against the biasing force of the clutch spring 53. This interrupts the drive transmission to the spindle 33. In addition, by rotating the clutch dial 36 and moving the nut 51 to the rear, the amount of compression 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 operating knob 62 of the switching mechanism 60 through the operator's operation, the drive transmission path of the reduction mechanism 40 is switched, and the rotational torque of the tip tool is set to low torque or high torque. This allows the operator to switch the rotational torque of the tip tool to low torque or high torque depending on the work content, such as during tightening work. Specifically, by setting the operating knob 62 to the low speed position, the shift arm 64 positions the second ring gear 44 to the rotation restriction position, and the rotational torque of the tip tool becomes high torque. On the other hand, by setting the operating knob 62 to the high speed position, the shift arm 64 positions the second ring gear 44 to the rotation permission position, and the rotational torque of the tip tool becomes low torque.

[0042] Here, in the switching mechanism 60 for switching the drive transmission path of the reduction mechanism 40, a shift arm 64 is mounted on the outer circumference of the gear case 31 so as to be rotatable in the left-right direction as the axial direction. A ring-side connecting portion 64E is formed on the second arm portion 64C of the shift arm 64, and the ring-side connecting portion 64E is inserted through the opening 31D of the gear case 31 and into the engagement groove 44A of the second ring gear 44 of the reduction mechanism 40. In this way, the shift arm 64 connects the ring-side connecting portion 64E and the second ring gear 44. In addition, an arm stopper 66 is provided on the motor spacer 32 that closes the rear end of the gear case 31, and the arm stopper 66 covers the ring-side connecting portion 64E from the left-right outside and is positioned with a small gap on the left-right outside of the ring-side connecting portion 64E. Therefore, the displacement of the ring-side connecting portion 64E on the left-right outside (the opening side of the opening 31D) is limited by the arm stopper 66. This prevents the ring-side connecting portion 64E from falling out of the opening 31D by the arm stopper 66. Furthermore, the arm stopper 66 prevents the scattering of lubricants such as grease from the opening 31D within the gear case 31. As a result, leakage of lubricants such as grease from the housing 10 is suppressed. Thus, the reliability of the driver drill 1 can be improved.

[0043] Furthermore, 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. In other words, 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 out of the opening 31D of the gear case 31, even if an operator comes into contact with the shift arm 64 during assembly of the housing 10. Therefore, the ease of assembly of the driver drill 1 can be improved.

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

[0045] In this embodiment, the arm stopper 66 is formed in a substantially rectangular plate shape with the plate thickness direction in the left-right direction and extending in the front-rear direction, and is positioned spaced apart on the left-right outer side of the gear case 31. In other words, a predetermined gap is formed between the arm stopper 66 and the outer circumference of the gear case 31 for positioning the second arm portion 64C of the shift arm 64. Alternatively, the arm stopper 66 may be configured to be positioned adjacent to the radially outer side of the gear case 31. That is, the plate thickness of the arm stopper 66 may be increased compared to this embodiment, and a recess 66A for accommodating the shift arm 64 (see the recess 66A shown by the dotted line in Figure 5) may be formed on the inner surface of the arm stopper 66 (the surface facing the gear case 31). In this case, for example, even if the arm stopper 66 deforms inward in the left-right direction due to aging or other reasons, the inner surface of the arm stopper 66 will contact the outer surface of the gear case 31, thus preventing the arm stopper 66 from contacting the second arm portion 64C of the shift arm 64. Therefore, the operation of the shift arm 64 can be maintained smoothly. Furthermore, since the part of the arm stopper 66 other than the recess 66A is positioned adjacent to the outer surface of the gear case 31, it is possible to prevent lubricants such as grease that have leaked from the opening 31D into the recess 66A 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] Furthermore, 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 then fixed to the motor spacer 32 to integrate 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 Figure 6, the arm stopper 66 may be integrally formed on the inner circumferential surface of the upper housing portion 10A and positioned adjacent to the left-right outer side of the second arm portion 64C of the shift arm 64. [Explanation of Symbols]

[0048] 1…Driver drill (work implement), 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. Motor and, A reduction mechanism that transmits the driving force of the motor to the output unit to rotate the output unit, A chuck is connected to the front end of the output unit, the driving force of the motor is transmitted via the reduction mechanism and the output unit, and a tip tool can be attached to it. A case that houses the reduction mechanism and has an opening that communicates the inside and outside, A motor spacer that closes one end of the case and supports the drive shaft of the motor, A switching mechanism for switching the drive transmission path of the reduction mechanism, comprising: a switching operation unit operated by an operator; a switching member movably mounted on the outer circumference of the case and connecting the switching operation unit and the reduction mechanism; and a connecting unit formed on the switching member, inserted through the opening and connected to the reduction mechanism, wherein when the switching operation unit is operated by an operator, the drive transmission path of the reduction mechanism is switched, and the rotational torque of the tip tool is switched. A retaining portion for preventing the connecting portion of the switching member from falling out of the opening and thus disengaging the connection between the switching operation portion and the reduction mechanism by the switching member, the retaining portion being integrally provided with the motor spacer, extending from the motor spacer toward the outside of the opening, and covering the connecting portion and at least a part of the opening from the outside, A vehicle used for construction work.

2. The work machine according to claim 1, wherein the retaining portion is arranged outside the connecting portion with a gap.

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

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

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