JP2014148000A - Power tool - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power tool in which a movable member can be stopped at a targeted position even if a turning member receives a force in a reverse direction caused by reaction generated when the turning member turns inertially to thereby collides with a stopper at a limit position after a driving part stops driving.SOLUTION: A pair of protrusion parts 47b protruding from the outer peripheral side of a ring gear (one example of a movable member) to a radial outer side are inserted in slide holes 40a of a transmission case 40 and cam holes 46 of a turning plate 42 constituting a shift-position changeover part. Each of the cam holes 46 has an operation hole part 46a extending to a direction slanting toward the peripheral direction of the turning plate 42, and the holding hole parts 46b which are continuously bored at both ends of the operation hole part 46a and extend at a prescribed angle θ to the peripheral direction of the turning plate 42. Even if the turning plate 42 receives a force in a reverse direction caused by reaction generated when the turning plate 42 turns inertially to thereby collides with the stopper at a limit position upon changing a shift position, the slide resistance between the sidewall face 46c of the holding hole 46b having the prescribed angle θ to a turning direction and the protrusion part 47b is imparted to the turning plate 42 and thereby, the turn of the turning plate 42 in the reverse direction is suppressed.

Description

  The present invention relates to a power tool that changes the speed ratio of a speed change mechanism unit that shifts the power of a power source and transmits rotation to a rotation output unit on which a tip tool is mounted.

  As an example of this type of power tool, an electric tool such as an electric screwdriver is known. The electric tool is a motor (an example of a power source) provided in the main body housing, a transmission mechanism that changes the rotation of the motor, a rotation that rotates at a speed that is changed by the transmission mechanism, and that can be mounted with a tip tool. (For example, patent documents 1-3).

  For example, Japanese Patent Application Laid-Open Publication Nos. HEI-A-H11-31359 and JP-A No. 2004-133270 disclose a transmission device that performs switching of a transmission gear ratio (reduction ratio) of a transmission mechanism unit with power of a transmission actuator (an example of a drive unit). This type of transmission includes a transmission mechanism and a transmission switching unit that performs an operation of switching a transmission ratio of the transmission mechanism. The control unit switches the gear ratio of the transmission mechanism unit by driving the shift actuator and driving the shift switching unit with the power.

  The transmission switching unit includes a rotation plate (for example, a circular sleeve) that can rotate along the outer periphery of the transmission case, and a support member attached to a movable member made of, for example, a ring gear in the transmission mechanism unit includes a transmission case. Are inserted into a slide hole formed along the axial direction and a cam hole formed along the direction inclined to the rotation direction of the rotation plate. Then, the rotation plate rotates, the support member moves along the cam hole, the movable member slides in the axial direction of the transmission, and the transmission gear that meshes with the movable member is changed to change the speed. The ratio is switched. In an electric tool having this type of transmission, the control unit has an automatic transmission function for switching the transmission ratio by driving the transmission actuator based on the detected value of the operating load, and also when the user operates the transmission switching operation unit. The gear ratio is switched by the control unit driving the gear shifting actuator in the driving direction corresponding to the operation signal.

JP 2012-16760 A JP 2012-30347 A Japanese Unexamined Patent Publication No. 2009-56590 (for example, FIG. 23)

  By the way, in the above transmission, it is necessary to stop the rotating plate at a target position (target allowable position) at the time of shifting. For example, there is a configuration in which a brake circuit for stopping the speed change actuator is provided. However, if the brake circuit is provided, the structure becomes complicated, and depending on the type of motor (for example, a brush motor), a component (for example, a brush) may be provided. Since it is consumed early, it is necessary to increase the size of the motor in order to ensure its life, and as a result, there is a possibility that the power tool must be enlarged.

  When the brake circuit is not provided, after the drive of the speed change actuator is stopped, the rotation plate is inertially rotated. Therefore, the rotation of the rotation plate is restricted with the target stop position as a limit position. However, there is a case in which the rotating plate that has been rotated by inertia is rotated (reversed) in the opposite direction slightly by the reaction that collides at the limit position, and the rotating plate may deviate from the target position. The cam hole has an operating hole portion that is inclined with respect to the circumferential direction of the rotating plate, and a holding hole portion that is continuously drilled at both ends of the operating hole portion and extends along the circumferential direction of the rotating plate. The support member is held in an axially immovable state at the end (end) of the holding hole. However, if the rotating plate rotates slightly in the reverse direction, the support member returns to the vicinity of the operating hole. For example, even if the rotating plate is rotated slightly in the reverse direction due to vibration of the electric tool during work, the support member reaches the operating hole, the restriction of the movable member in the axial direction is removed, and an unexpected gear ratio is There was a risk of switching.

  Of course, the above-mentioned problem is not limited to an electric tool, and if it includes a transmission that is driven by an electric drive unit such as a shift actuator, for example, a pneumatic tool that is driven using pneumatic pressure as a power source, Or, it applies to all power tools including a hydraulic tool driven by using hydraulic pressure as a power source.

  The present invention has been made in order to solve the above-mentioned problems, and its purpose is to reverse the reverse direction when the rotating member coasts and collides at the limit position after the driving of the driving unit is stopped. An object of the present invention is to provide a power tool capable of stopping a movable member at a target position even when receiving a force.

  In order to achieve the above object, a power tool includes a power source, a transmission mechanism that transmits rotational power of the power source to a rotation output unit on which a tip tool is detachably mounted, and a transmission that houses the transmission mechanism. A transmission case, and the transmission mechanism unit includes a transmission gear and a movable member that is slidable in the axial direction of the transmission gear and that engages or disengages from the transmission gear. A power tool capable of shifting in multiple stages by moving the movable member, wherein a slide hole provided in the transmission case along the axial direction and an outer periphery of the transmission case in the axial direction A rotating member having a working hole which is provided so as to be rotatable about the rotation direction and which extends through the direction inclined with respect to the rotating direction and is arranged to overlap the slide hole, and protrudes from the movable member As A support member inserted through the slide hole and the operating hole, a drive unit that drives the rotation member to rotate along the outer periphery of the transmission case, and the drive unit switches the rotation stage of the rotation member. When the rotation member is driven to rotate in a predetermined direction, the rotation member is rotated in a direction opposite to the predetermined direction by a reaction force received when the rotation of the rotation member is restricted at the limit position. And a reverse rotation suppressing portion that suppresses through engagement between the support member and the rotating member. Note that the engagement between the support member and the rotating member means both sliding, restraining of the supporting member by the rotating member, locking of both, and a change in the direction of the reaction force with respect to the direction of collision of both. It is a concept that includes a collision.

  Further, in the power tool, the reverse rotation suppressing portion rotates in the opposite direction by increasing sliding friction between the support member and the rotating member in both end regions of the rotating range of the rotating member. It is preferable to apply a braking force by the sliding friction to the rotating member.

  In the power tool, the reverse rotation suppressing portion is a hole portion that is continuously drilled at both ends of the operating hole and extends in a direction inclined with respect to the circumferential direction of the rotating member. Is preferred.

  Furthermore, in the power tool, the rotation member includes a hole portion that is continuously drilled at both ends of the operation hole and extends along a circumferential direction of the rotation member, and the reverse rotation suppression portion includes the hole. It is preferable that the support member that hits the end of the portion includes a slope that applies a reaction force in a direction intersecting the longitudinal direction of the hole.

  Further, in the power tool, the reverse rotation suppressing portion includes a second hole portion that extends from a longitudinal end portion of the hole portion in a direction of a reaction force that the support member that hits the inclined surface receives from the inclined surface. It is preferable to have.

  Even after the driving member stops driving, the movable member can be stopped at the target position even if the rotating member is inertially rotated and receives a reverse force due to a reaction when the rotating member collides at the limit position.

The sectional side view of the electric tool in 1st Embodiment. The schematic block diagram of an automatic transmission. The schematic front view which shows a transmission unit. (A)-(c) is a schematic cross section explaining the speed change of a speed change mechanism part. The side view which shows the reverse rotation suppression part provided in the shift switching part. The side view which shows the reverse rotation suppression part of the other example different from FIG. 5 provided in the gear change switching part. (A), (b) is a schematic side view which shows the principal part of the gear change switching part in a comparative example. The side view which shows the reverse rotation suppression part provided in the gear change switching part in 2nd Embodiment. The side view explaining the effect | action of a cam hole.

(First embodiment)
Hereinafter, a first embodiment will be described with reference to FIGS. FIG. 1 shows a state where a part of the housing of the electric power tool is removed.

  As shown in FIG. 1, an electric tool 10 as an example of a power tool of the present embodiment is a hand-held type that can be held with one hand, and is used as, for example, an electric drill driver. The electric tool 10 includes an electric tool body 11 and a battery pack 12 that is attached to the electric tool body 11 so as to be detachable. The housing 13 that forms the outline of the electric power tool body 11 includes a bottomed cylindrical body 14 (only the rear half is shown in FIG. 1) and an axis L (axial direction) from the middle of the longitudinal direction of the body 14. And a handle portion 15 extending in a direction intersecting with (downward in FIG. 1). Further, the electric power tool 10 has a square plate-like battery pack mounting portion 15a at the lower end of the handle portion 15, and the battery pack 12 is mounted on the battery pack mounting portion 15a. The electric power tool 10 of this example is a rechargeable type that uses the battery pack 12 as a driving power source.

  A motor 16 that is driven by electric power from the battery pack 12 is positioned near the base end (closest to the left end in FIG. 1) in the body portion 14 in a state in which the rotation axis is substantially coincident with the axis line of the body portion 14. It is arranged. This motor 16 consists of a brush motor or a brushless motor, for example. Next to the output shaft side of the motor 16 (right side in FIG. 1), a speed change unit 17 that receives the rotation of the motor 16 and changes speed (decelerates) is disposed.

  The speed change unit 17 shown in FIG. 1 decelerates the rotation input from the motor 16 and outputs it to the power transmission mechanism unit 18. The power transmission mechanism 18 transmits the rotation decelerated by the transmission unit 17 to the drive shaft 19. The drive shaft 19 is connected to a rotation output unit 20 (chuck unit) provided at the tip of the body unit 14. The rotation output unit 20 has a chuck function, and a tip tool 21 (a bit or the like) is detachably attached to the tip portion thereof. For this reason, the tip tool 21 rotates together with the rotation output unit 20 at the rotation speed decelerated by the transmission unit 17. Further, the power transmission mechanism unit 18 is configured to lock a torque limiter that cuts off power transmission to the drive shaft 19 and a lock that locks the drive shaft 19 in a non-rotatable state when the drive shaft 19 is stopped when a load greater than a setting is applied to the drive shaft 19 A mechanism and the like (both not shown) are provided. Note that the rotation output unit 20 may be an output unit having a screw part to which a tip tool can be screwed instead of the chuck part.

  As shown in FIG. 1, the trigger switch 22 is located at a front position slightly below the connection portion of the handle portion 15 with the body portion 14, that is, a position corresponding to the index finger of the hand on the side where the user grips the handle portion 15. Is provided. The trigger switch 22 includes a trigger lever 23 (operation lever) that is operated by the user when driving the electric tool 10, and a switch 24 that is switched on and off in accordance with the operation of the trigger lever 23 in the handle portion 15. Prepare. The trigger lever 23 protrudes forward from the handle portion 15 in a state of being biased by, for example, a spring. The switch 24 outputs a signal having a value corresponding to the operation amount (retraction amount) of the trigger lever 23 when the trigger lever 23 is turned on.

  Further, as shown in FIG. 1, in the vicinity of the connection portion of the body portion 14 with the handle portion 15, the forward / reverse operation that is operated by the user when the rotation direction of the rotation output portion 20 is switched between forward rotation and reverse rotation. A changeover switch 25 (rotation direction changeover lever) is provided. The forward / reverse selector switch 25 can be switched between, for example, a forward rotation position when the rotation output unit 20 is rotated forward and a reverse rotation position when the rotation output unit 20 is reversed. Of course, the rotation output unit 20 may be switched to a neutral position when neither forward rotation nor reverse rotation is performed.

  Further, a shift changeover switch 26 (an example of a shift changeover operation unit) for switching the gear ratio of the transmission unit 17 is provided on the upper surface of the body portion 14. The gear change switch 26 is a switch for switching between fixing a desired gear ratio for determining the rotation speed of the rotation output unit 20 to a desired one or performing an automatic gear change. The speed change switch 26 is, for example, a slide switch. By sliding the position in the front-rear direction, for example, high speed low torque drive (H gear), low speed high torque drive (L gear), and automatic speed change (AUTO) One of the three drive modes can be selected. The gear change switch 26 outputs a signal corresponding to one operation position selected at that time among the three operation positions corresponding to the three drive modes.

  Further, as shown in FIG. 1, a control unit 27 (a control board as an example) is disposed in the battery pack mounting unit 15a. The control unit 27 controls the motor 16 and is electrically connected to the motor 16 via the trigger switch 22 and wiring. The forward / reverse selector switch 25 is also connected to the control unit 27. For this reason, when the user pulls in the trigger lever 23, the motor 16 is driven to rotate in the rotation direction corresponding to the operation position of the forward / reverse selector switch 25 at that time. Further, if the user pushes the trigger lever 23, the rotation of the motor 16 is decelerated by the transmission unit 17 at a gear ratio corresponding to the operation position of the gear change switch 26 at that time, and the rotation output unit at the reduced speed. 20 rotates. The power transmission mechanism portion 18 has an impact function that causes the rotation output portion 20 to output a high torque when the load applied to the drive shaft exceeds a set load and the hammer strikes the anvil by the biasing force of the spring. But you can.

Next, a detailed configuration for switching the transmission ratio of the transmission unit 17 will be described with reference to FIGS.
As shown in FIG. 2, the transmission unit 17 to which the rotation shaft of the motor 16 is coupled includes a transmission 31 and a ring gear RG (internal gear) as an example of a movable member that constitutes the transmission 31 in the axial direction. A shift switching unit 32 that is moved to switch the transmission ratio of the transmission 31 and a shift actuator 33 as an example of a drive unit that drives the shift switching unit 32 are provided. The control unit 27 that performs overall control of the electric power tool 10 is electrically connected to various components of the input system such as the shift changeover switch 26, the trigger switch 22, and the forward / reverse changeover switch 25.

  Based on the input signal from the trigger switch 22, the control unit 27 activates and stops the motor 16 via the motor drive circuit 34 and adjusts the rotational speed during operation. While the trigger switch 22 is being operated, the control unit 27 controls the speed of the motor 16 at a rotational speed corresponding to the operation amount (the pulling amount of the trigger lever 23).

  In addition, the control unit 27 performs control to switch the transmission unit 17 to the designated speed ratio by driving the speed change actuator 33 to the drive position corresponding to the designated speed ratio via the speed change drive circuit 35. The control unit 27 controls the rotation direction of the shift actuator 33 and the drive power supplied by the PWM control by a control signal output to the shift drive circuit 35.

  In the automatic transmission mode, the control unit 27 detects the load torque applied to the tip tool 21 mounted on the rotation output unit 20 based on the current value of the motor 16 and the transmission ratio of the transmission unit 17, and detects the detected load. Automatic shift control is performed to switch to a gear ratio according to the torque by driving the shift actuator 33. In addition, the control unit 27 performs control to stop the driving of the motor 16 when detecting the lock of the motor 16 based on at least one of the detected load torque and the detected rotational speed value of the motor 16.

  As shown in FIGS. 2 and 3, the transmission 31 includes a cylindrical transmission case 40 and a transmission mechanism 41 accommodated in the transmission case 40. The speed change mechanism 41 of this embodiment is composed of, for example, a three-stage planetary gear mechanism. In FIG. 3, only the ring gear RG is shown for the speed change mechanism 41.

  The transmission mechanism unit 41 includes a plurality of transmission gears and a ring gear RG having teeth that can mesh with the teeth of the plurality of transmission gears. The ring gear RG is in the axial direction of the drive shaft 19 (see FIG. 1) ( The gear ratio can be switched between two stages by moving it in the left-right direction in FIG. 2 and meshing with a predetermined transmission gear. The detailed configuration of the transmission mechanism 41 will be described later.

  As shown in FIGS. 2 and 3, on the outer peripheral side of the ring gear RG, a semi-cylindrical (arc-shaped) rotating plate 42 (cam member) partially cut off on the upper side rotates around the axial direction of the ring gear RG. It is arranged in a state where it can be rotated (swingable). The rotating plate 42 includes a main body 43 having a semi-cylindrical shape along the outer surface of the ring gear RG, and an engaging portion 44 projecting radially outward from the main body 43 (lower side in FIGS. 2 and 3). And have.

  The speed change actuator 33 shown in FIG. 2 is driven in order to switch the speed ratio by moving the ring gear RG in the axial direction. The speed change actuator 33 is rotated by a speed change motor 33a that can rotate in both forward and reverse directions, a speed reduction portion 33b that transmits the drive force of the speed change motor 33a by decelerating, and a drive force that is transmitted via the speed reduction portion 33b. Output gear 33c.

  As shown in FIG. 3, the output gear 33 c meshes with the tooth portion 44 a of the engaging portion 44. For this reason, when the speed change actuator 33 is driven forward / reversely, the rotation plate 42 is reciprocally rotated within a predetermined angle range through the meshing of the output gear 33 c and the engagement portion 44. Here, as shown in FIG. 3, the shift switching unit 32 is provided with a stopper 45 for restricting the rotation range of the rotation plate 42. In this example, a pair of stoppers 45 are provided at positions where the stoppers 45 can abut against both end surfaces of the engaging portion 44 in the rotation direction. When the rotating plate 42 rotates in the clockwise direction in FIG. 3, the left end surface in FIG. 3 of the engaging portion 44 abuts on the left stopper 45 and is thus restricted to the position shown in FIG. At this time, the ring gear RG is disposed at the first engagement position (the position indicated by the broken line in FIG. 2). On the other hand, when the rotating plate 42 rotates counterclockwise from the position shown in FIG. 3, the right end surface in FIG. 3 of the engaging portion 44 comes into contact with the right stopper 45, thereby being restricted to the contacted position. The At this time, the ring gear RG is disposed at the second engagement position (the position of the two-dot chain line in FIG. 2).

  In addition, as long as the stopper 45 can restrict | limit the rotation range of the rotation board 42, the arrangement position and a control mechanism can be changed arbitrarily. For example, a stopper may be disposed so as to contact the main body 43 of the rotating plate 42. In this case, an insertion portion such as a hole or a notch is formed in the rotation plate 42, and the rod-shaped stopper inserted into the insertion portion hits both end surfaces in the longitudinal direction of the insertion portion, thereby restricting the rotation range of the rotation plate. The structure to do may be sufficient. Further, the stopper 45 may abut against another member that rotates together with the rotation plate 42 to restrict the rotation range of the rotation plate.

  As shown in FIGS. 2 and 3, a pair of cam holes 46 are formed in the portion of the main body 43 near the both ends in the circumferential direction. As shown in FIG. 3, the cam hole 46 is continuously drilled in an operating hole portion 46 a extending along a direction inclined with respect to the circumferential direction of the rotating plate 42 and both end portions of the operating hole portion 46 a. And a holding hole 46b extending substantially along the circumferential direction.

  As shown in FIG. 3, a groove portion RGa extending along the circumferential direction is formed on the outer circumferential surface of the ring gear RG accommodated in the transmission case 40 so as to be movable in the axial direction. A support member 47 made of a metal wire rod having an arc-shaped portion and a shape in which both end portions protrude radially outward is engaged with the groove portion RGa. The support member 47 includes a support portion 47a having a semicircular arc shape when viewed from the front shown in FIG. 3 along the outer peripheral surface of the ring gear RG, and a pair of projecting portions 47b extending linearly outward from both ends of the support portion 47a in the radial direction. And have. The pair of projecting portions 47b are inserted from the inside into a pair of slide holes 40a extending along the axial direction penetrating the transmission case 40, and at a position partially overlapping with the slide holes 40a in the rotating plate 42. It is inserted through a pair of cam holes 46 (see FIGS. 5 and 6). The slide hole 40a is formed by a long hole or notch extending in the axial direction.

  The speed change actuator 33 shown in FIG. 2 changes the position of the ring gear RG in the axial direction by rotating the rotation plate 42 of the speed change switching unit 32, and changes the speed change gear with which the ring gear RG meshes. Thus, the gear ratio of the transmission mechanism 41 is switched. The speed change actuator 33 includes a position detector 33d that can detect from the rotation amount of the output gear 33c that the ring gear RG has been changed to the correct target position. The control unit 27 drives the speed change actuator 33 until it is detected that the ring gear RG has reached the target position based on the detection signal of the position detection unit 33d, and detects that the ring gear RG has reached the target position. Then, the drive of the shift actuator 33 is stopped. Of course, the control unit 27 may set a target position to stop driving the speed change actuator 33 earlier than the target position, with some expectation of inertial rotation after the power supply to the speed change actuator 33 is cut off.

  In the present embodiment, the ring gear RG is engaged with the H gear (high-speed transmission gear) at the relatively first engagement position indicated by the broken line in FIG. The low torque mode (hereinafter also simply referred to as “high speed mode”) is set. Further, the ring gear RG moves forward from the first engagement position, so that the engagement state with the H gear is released. Further, when the ring gear RG moves to the relatively second engagement position indicated by a two-dot chain line in FIG. 2, the ring gear RG engages with the L gear (low speed side transmission gear). The torque mode (hereinafter also simply referred to as “low speed mode”) is set.

Next, the detailed structure of the speed change mechanism 41 will be described with reference to FIG.
As shown in FIG. 4, the transmission 31 includes a transmission case 40 that is substantially cylindrical and has a shape in which central portions of both end portions in the axial direction are opened, and a transmission mechanism 41 that is housed in the transmission case 40. have. The transmission mechanism 41 is constituted by a planetary gear transmission mechanism including planetary gear trains 51 to 53 having a plurality of stages (three stages as an example). The first stage planetary gear train 51 is located on the input side and is driven by the motor 16. A plurality of planetary gears 55 arranged around the sun gear 54 and the planetary gear 55 are rotatably supported. A carrier 56 and a ring gear 57 located on the outer periphery of the planetary gear 55 are provided. The carrier 56 has a tooth portion that protrudes radially outward on the outer periphery, and a central gear portion 58 that serves as an input gear for the second stage planetary gear train 52 at the center of rotation. Around the central gear portion 58, a plurality of planetary gears 59 constituting the second stage planetary gear train 52 are arranged.

  The second stage planetary gear 59 is rotatably supported by the second stage carrier 60. The second-stage carrier 60 has a central gear portion 61 at the output-side central portion, and a plurality of planetary gears 62 constituting the third-stage planetary gear train 53 are arranged around the central gear portion 61. Has been. The planetary gear 62 is rotatably supported by a third-stage carrier 63, and meshes with a third-stage ring gear 64 disposed outside the planetary gear 62. The third-stage carrier 63 is rotated by the revolution of the third-stage planetary gear 62, and an output shaft 65 projects from the center thereof. The output shaft 65 rotates at a rotation speed corresponding to the gear ratio at that time. To do.

The first-stage ring gear 57 included in the first-stage planetary gear train 51 is fixed to the inner wall surface of the transmission case 40 and cannot rotate.
The second stage planetary gear train 52 has a ring gear RG that is slidable in the axial direction around the second stage planetary gear 59. The second-stage ring gear RG has a tooth portion protruding radially inward on the inner periphery thereof, and a tooth portion recessed inward in the radial direction on the outer peripheral surface of the end portion on the output side.

  The second stage ring gear RG is arranged so that the teeth of the second stage planetary gear 59 and the transmission case are engaged with the teeth of the first stage carrier 56 and the teeth of the second stage planetary gear 59. It moves in the range of the position where it engages with the fixed tooth portion 66 projecting radially inward at 40. In the present embodiment, the carrier 56, the planetary gear 59, and the fixed tooth portion 66 constitute an example of a transmission gear that engages or disengages a ring gear RG that is an example of a movable member.

  In the electric power tool 10 of the present embodiment, as shown in FIG. 4A, when the second stage ring gear RG is in a position where it meshes with the first stage carrier 56 and the second stage planetary gear 59. However, it becomes a high speed low torque mode (non-deceleration mode). Further, as shown in FIG. 4C, the position where the second stage ring gear RG meshes with the second stage planetary gear 59 and the fixed tooth portion 66 is in the low speed high torque mode (deceleration mode). .

The third stage ring gear 64 disposed on the outer periphery of the third stage planetary gear 62 in the third stage planetary gear train 53 is fixed to the transmission case 40.
The plurality of first-stage planetary gears 55 mesh with each other between the sun gear 54 and the first-stage ring gear 57, as shown in FIG. The plurality of second stage planetary gears 59 mesh between the central gear portion 58 of the first stage carrier 56 and the second stage ring gear RG. The plurality of third-stage planetary gears 62 mesh with the central gear portion 61 of the second-stage carrier 60 and the third-stage ring gear 64.

  The second-stage ring gear RG has a support member 47 projecting radially outward, and the support member 47 is slid in the axial direction by moving the support member 47 along the axial direction. . The second-stage ring gear RG of the present embodiment has a groove portion RGa formed in an annular shape on the outer peripheral surface thereof, and the support member 47 is fitted in the groove portion RGa. Accordingly, the ring gear RG can slide in the axial direction while following the movement in the axial direction of the support member 47 while rotating.

  The support member 47 has a pair of projecting portions 47b projecting radially outward from the outer peripheral surface of the ring gear RG at both ends thereof. The pair of projecting portions 47 b protrudes outward from the transmission case 40 through a slide hole 40 a extending in the axial direction formed in the transmission case 40.

  As shown in FIG. 5, the rotation plate 42 has a working hole 46a extending along a direction inclined with respect to the turning direction (circumferential direction), and is continuously drilled at both ends of the working hole 46a. The above-described cam hole 46 having a holding hole portion 46b that is provided and extends substantially along the rotation direction is formed. The rotating plate 42 is attached such that its cam hole 46 overlaps with the pair of slide holes 40a on the transmission case 40 side. A pair of projecting portions 47 b penetrating the slide holes 40 a to the outside are inserted into the pair of cam holes 46.

  When the rotating plate 42 is rotated along the outer peripheral surface of the transmission case 40, the protruding portion 47b moves along the operating hole 46a extending in a direction inclined with respect to the rotating direction of the rotating plate 42. Thus, the support member 47 moves in the axial direction along the slide hole 40a. Following the movement of the support member 47 in the axial direction, the ring gear RG shown in FIGS. 2 and 4 moves in the axial direction.

  As shown in FIG. 5, when the protrusion 47b of the support member 47 is located at one end in the longitudinal direction of the cam hole 46 (the end on the L side in FIG. 5), the second stage ring gear RG is The second stage planetary gear 59 and the fixed tooth portion 66 of the transmission case 40 mesh with each other. At this time, the low speed high torque mode is set. When the support member 47 is positioned at the other longitudinal end of the cam hole 46 (the H-side end in FIG. 5), the second-stage ring gear RG is connected to the first-stage carrier 56 and the second-stage carrier 56. Engage with the planetary gear 59 of the eye. At this time, the high speed low torque mode is set.

Next, an example of the reverse rotation suppression unit will be described with reference to FIGS.
As shown in FIG. 5, the holding hole portion 46 b constituting the cam hole 46 extends in an oblique direction that makes a predetermined angle θ with respect to the circumferential direction of the rotating plate 42 in detail. In the example shown in FIG. 5, the holding hole 46b is inclined in a direction opposite to the direction in which the operating hole 46a is inclined. For this reason, one of the pair of side wall surfaces (inner wall surfaces) facing each other in the width direction of the holding hole portion 46b is when the rotation plate 42 that has been inertially rotated at the time of shifting reaches the rotation limit position (limit position). The side wall surface 46c (the left side wall surface in FIG. 5) has a predetermined angle θ that can slide with the protrusion 47b to generate a sliding resistance when the counterclockwise rotation is caused by the reaction.

  Moreover, the example of the cam hole 46 formed in the rotation board 42 shown in FIG. 6 may be sufficient. That is, the holding hole 46b of the cam hole 46 shown in FIG. 6 is inclined in the same direction as the direction in which the operating hole 46a is inclined, and in an oblique direction that forms a predetermined angle θ with respect to the circumferential direction of the rotating plate 42. It extends. For this reason, one of the pair of side wall surfaces (inner wall surfaces) facing each other in the width direction of the holding hole portion 46b rotates in the reverse direction due to the reaction when the rotating plate 42 that has rotated by inertia during shifting reaches the limit position. A side wall surface 46d (a right side wall surface in FIG. 6) having a predetermined angle θ that can slide to generate sliding resistance when sliding is formed.

  The predetermined angle θ of the present embodiment is the distance between the inner wall surface of the holding hole 46b when the rotating plate 42 rotates by inertia and rotates in the direction opposite to the predetermined direction due to the reaction when the rotating plate collides at the limit position. The sliding resistance between the projecting portion 47b is increased and the sliding resistance is set to an angle at which the projecting portion 47b can be braked so that it can be arranged closer to the end of the holding hole portion 46b than the operating hole portion 46a. Yes.

  As an example, the predetermined angle θ is preferably 1 degree or greater and 30 degrees or less. In particular, 3 degrees or more and 15 degrees or less are preferable. Here, if the predetermined angle θ is too small, for example, less than 1 degree, the protruding portion 47b is placed in the holding hole 46b due to a gap in the width direction corresponding to the difference between the width of the holding hole 46b and the outer diameter of the protruding portion 47b. Easily move to the side wall surface 46c or 46d without sliding, and even when sliding, the sliding resistance is small and the required braking force is difficult to obtain. In addition, when the predetermined angle θ is less than 3 degrees, the braking force is slightly insufficient and is within an allowable range, but the amount of deviation from the end position of the holding hole 46b of the protrusion 47b toward the working hole 46a is large. There is a case. And if it is 3 degree | times or more, sufficient sliding resistance will be easy to be obtained and the protrusion part 47b can be arrange | positioned as aimed near the terminal position of the holding hole part 46b.

  In order to obtain sliding resistance, the axial displacement between the longitudinal ends of the holding hole 46b is more than the gap corresponding to the difference between the width of the holding hole 46b and the outer diameter of the protrusion 47b. It is desirable that the predetermined angle θ be large enough. In this example, the predetermined angle θ at which necessary sliding resistance is obtained is determined in consideration of the value of the gap determined from the design allowable value of the electric power tool 10.

  On the other hand, if the predetermined angle θ is too large, for example, more than 30 degrees, the sliding resistance between the protruding portion 47b and the side wall surface of the holding hole portion 46b becomes slightly excessive in the process of rotating the rotating plate 42 in the predetermined direction, and Since the driving load of the motor 33a is increased, smooth shifting of the transmission unit 17 is slightly difficult. If it is 30 degrees or less, a relatively smooth shift can be achieved while suppressing excessive sliding resistance. In particular, if it is 15 degrees or less, an appropriate sliding resistance can be obtained, and a remarkably smooth speed change can be realized.

  Further, for example, the length of the holding hole 46b in the longitudinal direction is set to a value more than twice the outer diameter of the protruding portion 47b in consideration of the rotational displacement of the rotating plate 42 due to the vibration of the electric tool 10 during work. It is preferable. When the predetermined angle θ is given an inclination exceeding 15 degrees to the holding hole portion 46b having this length, the ring gear is moved when the protruding portion 47b is displaced in the holding hole portion 46b due to the rotational displacement of the rotation plate 42. RG will shift in the axial direction. The predetermined angle θ is preferably 15 degrees or less from the viewpoint of minimizing the axial displacement of this type of ring gear RG. Of course, the predetermined angle θ is not limited to 30 degrees or less, and any angle can be appropriately selected as long as the effect is obtained.

Next, the operation of the electric power tool 10 configured as described above will be described.
By operating the trigger lever 23, the electric power tool 10 is driven to rotate the rotation output unit 20, and the tip tool 21 mounted on the power tool 10 is rotated, so that work corresponding to the tip tool 21 is performed. For example, if the tip tool 21 is a driver bit, a screw is tightened by a screwdriver, and if the drill bit is a drill bit, drilling or the like is performed.

  When the trigger lever 23 is operated, the rotation of the motor 16 is changed (decelerated) via the transmission unit 17, and the changed rotation is transmitted to the power transmission mechanism 18 and the rotation output unit 20. 21 rotates. At this time, the tip tool 21 rotates forward or backward corresponding to the selected position of the forward / reverse selector switch 25.

  When shifting the power tool 10, the user operates the shift changeover switch 26. For example, when it is desired to drive in the low speed mode, the gear change switch 26 is operated to the low speed position. At this time, a low speed selection signal is input from the shift changeover switch 26 to the control unit 27. When it is desired to drive in the high speed mode, the gear change switch 26 is operated to the high speed position. At this time, a high speed selection signal is input to the control unit 27 from the gear change switch 26.

  When detecting the change of operation of the gear change switch 26, the control unit 27 drives the gear shift actuator 33 to rotate the rotating plate 42, thereby slidingly moving the ring gear RG. At this time, when the low speed selection signal is input, the control unit 27 drives the speed change motor 33a to rotate forward, for example. Thereby, the transmission unit 17 is switched from the H gear to the L gear. Further, when the high speed selection signal is input, the control unit 27 drives the speed change motor 33a, for example, in the reverse direction. Thereby, the transmission unit 17 is switched from the L gear to the H gear. Then, when the position detecting unit 33d detects that the output gear 33c has been rotated by a predetermined rotation angle and has reached the target position while the transmission motor 33a is being driven, the control unit 27 stops driving the transmission motor 33a. Let

  Here, when there is no brake function (function to stop the motor immediately when the power is shut off by a regenerative diode or the like), the speed change motor 33a of the present embodiment rotates by inertia even after the power supply is cut off. For this reason, the rotating plate 42 is also inertially rotated in a predetermined direction by inertial rotation of the speed change motor 33a. Due to this inertial rotation, the rotating plate 42 collides with the stopper 45, or the protruding portion 47b collides with the end wall surface of the holding hole 46b. A force in a direction opposite to a predetermined direction is exerted on the rotating plate 42 due to the collision reaction when the rotating plate 42 reaches the limit position. At this time, for example, a force when the rotating plate 42 that is bent for a moment at the time of collision is restored also acts as a force in a direction opposite to a predetermined direction.

  However, as shown in FIG. 5 or 6, the holding hole 46 b is inclined at a predetermined angle θ with respect to the circumferential direction of the rotating plate 42 (that is, the rotating direction). For this reason, when the rotating plate 42 tries to rotate in the reverse direction, the protruding portion 47b slides relatively strongly on the side wall surface 46c or 46d of the holding hole portion 46b. It acts as a braking force that brakes the reverse rotation of the plate 42. In addition, the predetermined angle θ at this time is set to a value that stays at a target position within an allowable range near the end position of the holding hole 46b without the protrusion 47b returning to the vicinity of the operating hole 46a. As a result, the rotation of the rotation plate 42 in the reverse direction is suppressed, the rotation plate 42 stops at a target position within an allowable range without greatly deviating from the target position, and the protrusion 47b is held in the holding hole 46b. It is held near the end position.

  FIG. 7 shows a comparative example when the holding hole portion of the cam hole extends along the circumferential direction of the rotating plate at a predetermined angle θ = 0 degrees. The cam hole 71 formed in the rotating plate 70 shown in FIG. 7A is along a direction that forms an oblique angle with respect to the axial direction and the circumferential direction, like the operation hole portion 46a shown in FIGS. The working hole 71a extends and the holding hole 71b extends along the circumferential direction of the rotating plate 70 (that is, the predetermined angle θ = 0).

  Here, at the time of shifting, the shifting motor 33a rotates inertially in a predetermined direction even after the power supply is cut off, and the rotating plate 70 has a predetermined reaction force due to a collision reaction when the rotating plate 70 reaches the limit position. A force in the direction opposite to the direction works. At this time, since the holding hole 71b of the rotating plate 70 extends along the circumferential direction, the rotating plate 70 rotates in the reverse direction without receiving a large sliding resistance from the protruding portion 47b of the support member 47. Move. As a result, as shown in FIG. 7B, for example, the protrusion 47b is located near the operation hole 71a in the holding hole 71b. In this case, for example, due to the vibration of the electric power tool 10 during work, the rotation plate 70 is only slightly rotated, so that the protrusion 47b reaches the operation hole 71a, and the restriction of the support member 47 in the axial direction is removed. . The support member 47 that is out of the regulation is easy to move along the operating hole 71a due to vibration of the electric power tool 10 during work, and when it moves, the ring gear RG has an unexpected gear ratio due to sliding movement. Switching may occur.

  However, in the case of the rotating plate 42 having the cam hole 46 in the present embodiment, the rotating plate 42 that has received a force in the direction opposite to the predetermined direction due to the reaction at the time of collision at the limit position tries to rotate in the reverse direction. At this time, the rotating plate 42 receives a braking force due to a sliding resistance between the protruding portion 47b and the side wall surface 46c or 46d. For this reason, even if the rotation plate 42 rotates in the direction opposite to the predetermined direction, the rotation amount (return amount) at that time can be kept small. As a result, the projecting portion 47 b is positioned closer to the end of the holding hole portion 46 b of the cam hole 46. For this reason, for example, even if the rotating plate 42 is slightly rotated due to vibration of the electric power tool 10 during work, the protruding portion 47b is still held in the holding hole 46b. Movement is restricted. Therefore, the sliding movement of the ring gear RG in the axial direction is avoided, and unexpected gear ratio switching can be suppressed. In addition, in the inertial rotation process of the rotation plate 42 in a predetermined direction after the power supply to the speed change actuator 33 is cut off, the side wall surface opposite to the side wall surfaces 46c and 46d of the holding hole 46b and the protruding portion 47b. And the sliding resistance reduces the rotational speed of the rotational plate 42, and this deceleration also contributes to hold the protruding portion 47b in the vicinity of the end position of the holding hole 46b.

  Further, during the operation of operating the trigger switch 22 with the shift changeover switch 26 in the AUTO position, the control unit 27 drives the shift actuator 33 according to the detected work load, so that the transmission unit 17 is It is automatically switched to the gear ratio according to the work load. Similarly, at the time of gear change in this case, the protrusion 47b of the support member 47 is held at a target position within an allowable range near the end position of the holding hole 46b.

As described above in detail, according to the present embodiment, the following effects can be obtained.
(1) Suppressing the rotation of the rotating plate 42 that inertially rotates in a predetermined direction after the power supply of the speed change actuator 33 is rotated in the direction opposite to the predetermined direction by a reaction force when colliding at the limit position. As an example of the reverse rotation suppressing portion, the holding hole portion 46b of the cam hole 46 is formed so that its longitudinal direction extends at a predetermined angle θ with respect to the circumferential direction of the rotating plate 42. Therefore, the rotation of the rotating plate 42 in the reverse direction is caused by sliding resistance through sliding (an example of engagement) between the support member 47 and the side wall surface 46c or 46d of the holding hole 46b in the rotating plate 42. Since the braking force (sliding resistance) which suppresses can be provided, the rotation amount to the reverse direction of the rotation board 42 can be restrained small. For this reason, even if it does not provide a brake circuit, rotation of the rotating plate 42 in a direction opposite to the predetermined direction can be suppressed. Therefore, the rotating plate 42 can be stopped at the target position within the allowable range. As a result, even if the rotating plate 42 is slightly rotated in the reverse direction due to the vibration of the electric tool 10 during the subsequent work, the projecting portion 47b is held in the holding hole 46b. Can be avoided.

  (2) A holding hole 46b (an example of a hole) continuously drilled at both ends of the working hole 46a is formed so as to be inclined at a predetermined angle θ with respect to the circumferential direction of the rotating plate 42. Since it is a structure, a rotation suppression part can be comprised comparatively easily only by changing the shape of the cam hole 46 of the rotation board 42. FIG.

  (3) Since the predetermined angle θ is in the range of 1 to 30 degrees, an appropriate sliding resistance can be imparted, and an overload of the speed change motor 33a due to an excessive sliding resistance can be avoided to smoothly switch the gear ratio. realizable. In particular, when the predetermined angle θ is set in the range of 3 to 15 degrees, the braking force by the sliding resistance can be applied more appropriately, and the gear ratio can be switched more smoothly.

(Second Embodiment)
Next, a second embodiment will be described with reference to FIGS. This 2nd Embodiment is an example from which the hole shape of a cam hole differs. Hereinafter, the same components as those in the first embodiment are denoted by the same reference numerals, description thereof will be omitted, and only different portions will be described.

  As shown in FIG. 8, the cam hole 46 formed in the rotating plate 42 of the present embodiment has an operation hole portion 46a similar to that of the first embodiment. Further, the cam hole 46 is continuously drilled at both ends in the longitudinal direction of the operation hole 46a, and a holding hole 46b as an example of a hole extending along the circumferential direction of the rotating plate 42, and a holding hole It has the extended hole part 46e as an example of the 2nd hole part pierced so that it may extend in the direction which cross | intersects the longitudinal direction continuously to the edge part of the longitudinal direction of the part 46b. A slope 46f is formed at the end of the holding hole 46b in the longitudinal direction to apply a reaction force in a direction intersecting the longitudinal direction of the holding hole 46b to the protrusion 47b of the support member 47 that has collided with the end face. Yes. The inclined surface 46f is inclined with respect to the longitudinal direction of the holding hole 46b in a direction that can apply a reaction force toward the extending hole 46e to the protruding portion 47b that collides with the inclined surface 46f. In other words, the extending hole portion 46e extends in the direction of the reaction force received from the inclined surface 46f by the protruding portion 47b that hits the inclined surface 46f at the end portion (terminal) in the longitudinal direction of the holding hole portion 46b.

  In addition, at the portion of the extension hole 46e facing the inclined surface 46f, the rotation plate 42 starts to rotate for changing the gear ratio while the protrusion 47b is restrained in the extension hole 46e. Sometimes, a guide surface 46g is provided for guiding the protruding portion 47b restrained in the extending hole portion 46e to the holding hole portion 46b.

Next, the operation of the transmission unit 17 in the second embodiment will be described.
At the time of shifting, the shifting motor 33a rotates by inertia even after the power supply is cut off, thereby rotating the rotating plate 42 in a predetermined direction. As a result, the slope 46f located at the end of the holding hole 46b of the rotating plate 42 collides with the protrusion 47b. At this time, the protrusion 47b receives a reaction force in the direction intersecting with the longitudinal direction of the holding hole 46b (the white arrow direction in FIGS. 8 and 9) from the inclined surface 46f, and moves to the extension hole 46e side. As shown by a two-dot chain line in FIG.

  Further, the rotating plate 42 receives a reaction force in a direction (left direction in FIGS. 8 and 9) intersecting the rotating direction when the inclined surface 46f collides with the protruding portion 47b. Therefore, the component in the reverse direction of the reaction force received by the rotating plate 42, that is, the force that attempts to rotate the rotating plate 42 in the reverse direction is suppressed. For this reason, the rotation speed in the reverse direction of the rotation plate 42 when the protrusion 47b moves to the extension hole 46e side becomes slow. From this point, the protrusion 47b becomes the extension hole 46e. It becomes easy to be restrained.

  When the protrusion 47b is constrained in the extension hole 46e, the rotation of the rotation plate 42 in the direction opposite to the predetermined direction is restricted, and the protrusion 47b is held at the end position of the holding hole 46b. The Further, since the protruding portion 47b is restrained in the extending hole portion 46e, the rotation of the rotating plate 42 is restricted even when the electric tool 10 is being vibrated, for example. Therefore, unexpected gear ratio switching can be avoided.

According to the second embodiment, the following effects can be obtained.
(4) As an example of the reverse rotation suppressing portion, an inclined surface 46f inclined with respect to the longitudinal direction is formed at the end of the holding hole portion 46b in the longitudinal direction, and the protruding portion 47b hitting the inclined surface 46f has a longitudinal direction of the holding hole portion 46b. Added a reaction force in the crossing direction. Therefore, the protrusion 47b that hits the slope 46f receives a force in a direction intersecting the circumferential direction of the rotating plate 42, and the force in the reverse direction is weakened, so that the reverse rotation of the rotating plate 42 can be suppressed.

  (5) As an example of the reverse rotation suppressing portion, the extension hole portion 46e (second second) extends from the end in the longitudinal direction of the holding hole portion 46b in the direction of the reaction force that the protrusion portion 47b hits the inclined surface 46f receives from the inclined surface 46f. An example of a hole). Therefore, the protrusion 47b that has moved in the direction intersecting with the longitudinal direction of the rotating plate 42 when it hits the inclined surface 46f is restrained in the extension hole 46e, and the rotation of the rotating plate 42 in the direction opposite to the predetermined direction is suppressed. it can.

  (6) When the rotating plate 42 starts to rotate in order to change the gear ratio while the protruding portion 47b is disposed (restrained) in the extending hole portion 46e, the protruding portion 47b is extended to the extending hole portion. A guide surface 46g for guiding from 46e to the holding hole 46b was provided. Therefore, the gear ratio can be quickly switched by smoothly rotating the rotating plate 42 from the state in which the protruding portion 47b is constrained in the extending hole portion 46e.

The embodiment may have the following aspects.
In the first embodiment, among the pair of side wall surfaces of the holding hole 46b, the side wall surface that is not the side wall surfaces 46c, 46d may be extended straight in the circumferential direction. Even if it is this structure, a sliding resistance (braking force) can be provided in the process in which the rotation board 42 rotates in the reverse direction at least. Further, the side wall surface of the holding hole portion 46b that is not the side wall surfaces 46c, 46d is straightly extended in the circumferential direction until the power supply cut-off position (drive stop position) to the speed change actuator 33, and the holding hole portion is positioned beyond the drive stop position. You may give the inclination of predetermined angle (theta) in the terminal side of 46b. According to this configuration, it is possible to apply a braking force due to sliding resistance to the rotating plate 42 that rotates by inertia while suppressing a load during driving of the speed change actuator 33.

  In each of the above-described embodiments, the shape of the side wall surfaces 46c and 46d viewed in a side view shown in FIGS. 5, 6, and 8 may be a curved shape (curved surface) instead of a linear shape (flat surface). Even if the side wall surface of the holding hole portion 46b is a curved surface, sliding resistance with the protruding portion 47b can be applied to the rotating plate 42. For example, a curved surface shape in which a predetermined angle θ (in this case, an angle formed by an imaginary line in contact with the curved surface with respect to the circumferential direction of the rotating plate 47) is increased toward the end of the holding hole 46b. According to this configuration, it becomes easier to hold the protrusion 47b near the end of the holding hole 46b.

  In the second embodiment, the extension hole 46e (an example of the second hole) may be eliminated. When the projecting portion 47b collides with the inclined surface 46f, the projecting portion 47b receives a force in a direction crossing the circumferential direction. For this reason, the component opposite to the predetermined direction of the reaction force received when the rotating plate 42 reaches the restricting position is relaxed, and thereby the amount of rotation of the rotating plate 42 in the reverse direction can be suppressed small.

  In the second embodiment, the extending direction of the extending hole 46e may be opposite to the holding hole 46b. That is, the pair of extending hole portions 46e are configured to extend in directions approaching each other in the axial direction (for example, the left-right direction in FIG. 8). Even with this configuration, the same effect as in the second embodiment can be obtained.

  The engagement between the support member and the rotation member for the reverse rotation suppression unit to suppress the rotation (reverse rotation) of the rotation member in the reverse direction may be locking of both. For example, a concave curved surface having substantially the same curvature as the outer peripheral surface of the projecting portion 47b is formed on the end surface of the holding hole 46b, and the projecting portion 47b projects with the momentum when the rotating plate 42 collides at the limit position. The portion 47b is fitted to the concave curved surface and is configured to be locked at the end position of the holding hole portion 46b.

  In each of the above embodiments, the restricting portion that restricts the rotating plate 42 at the limit position is not limited to at least one of the stopper 45 and the end surface of the holding hole portion 46b. In short, a restricting portion that can restrict the rotation of the rotating plate at the limit position is sufficient.

The rotating member is not limited to a plate shape such as a rotating plate. For example, a rotating block member having a concave curved surface along the outer periphery of the transmission case may be used.
The transmission mechanism 41 for switching the transmission ratio is not limited to the planetary gear mechanism, and may be changed to another known gear mechanism. In this case, the movable member is not limited to the ring gear, and may be any speed change member that can move so as to be engageable and disengageable with the speed change gear in the applied gear mechanism. Further, the moving direction of the movable member is not limited to the axial direction of the transmission case, and may be the radial direction as long as the gear ratio can be switched.

  -The drive unit is not limited to an actuator having a motor, but an electric type that can output power for rotating a rotating plate and can be controlled by a control unit, such as a motor alone, an electric cylinder, a solenoid, an electrostrictive actuator, etc. If it is a thing.

  In each of the above embodiments, the gear ratio is the second speed mode (low speed high torque / high speed low torque), but a speed mode higher than the third speed mode, for example, the fourth speed mode, the fifth speed mode, and the sixth speed mode is adopted. You can also. In this case, the rotating plate is provided with a plurality of cam holes as in Patent Documents 1 to 3, and the cam hole 46 shown in FIG. 5 or 6 is adopted as at least one of the plurality of cam holes, The cam hole 46 shown in FIGS. 8 and 9 may be employed.

  In each of the above embodiments, the speed change mechanism 41 is a speed reduction mechanism, but may be a speed increase mechanism or a speed change mechanism capable of both speed reduction and speed increase. Furthermore, a speed change mechanism unit in which constant speed is added to these may be used.

-Although the electric tool is made rechargeable, it may be applied to a non-rechargeable AC electric tool.
Furthermore, the electric tool is not limited to an electric drill driver, and the movable member of the speed change mechanism that changes the power of the power source is a rotating member along the outer periphery of the transmission case by the power of the drive part such as a speed change actuator. It can be similarly applied to other electric tools in which the shift ratio of the speed change mechanism is switched by the movement of the movable member. For example, the present invention can be applied to an electric impact driver, hammer drill, impact wrench, circular saw, jigsaw, screw driver, vibration driver, grinder, nailing machine, and the like.

  The power tool is not limited to an electric tool, and may be a power tool that is driven by air pressure. In addition, a power tool driven by hydraulic pressure may be used. That is, as long as the gear ratio of the transmission mechanism is switched by the power of the drive unit (for example, an actuator), the power source that outputs the power for shifting to the transmission mechanism unit is electric, pneumatic, Any known method such as a hydraulic method may be used.

The technical idea grasped from the embodiment and the modifications will be described below.
(Technical thought 1) When the rotation plate starts to rotate in a state where the support member is disposed in the second hole, the support member is moved from the second hole to the hole. The power tool according to claim 5, wherein a guide surface (46g) for guiding is provided.

  DESCRIPTION OF SYMBOLS 10 ... Electric tool as an example of a power tool, 13 ... Housing, 16 ... Motor which is an example of a power source, 17 ... Transmission unit, 20 ... Rotation output part, 21 ... Tip tool, 26 ... Shift change switch, 31 ... Shift , 32... Gear change switching unit, 33... Speed change actuator as one example of drive unit, 40... Transmission case, 40 a... Slide hole, 41. 46 ... cam hole, 46a ... working hole portion constituting an example of working hole, 46b ... constituting an example of reverse rotation suppressing portion and holding hole portion as an example of hole portion, 46c ... side constituting an example of reverse rotation suppressing portion Wall surface, 46d: side wall surface constituting an example of the reverse rotation suppressing portion, 46e: extending hole portion as an example of the second hole portion, 46f ... inclined surface, 47 ... supporting member, 47b: constituting an example of the reverse rotation suppressing portion. Protrusion, 56 Career as an example of the transmission gears (first stage), 59 ... planet gear as an example of a transmission gear, 66 ... fixed wheel as an example of the transmission gears, RG ... ring gear (internal gear) as an example of the movable member.

Claims (5)

A power source, a transmission mechanism that transmits rotational power of the power source to a rotation output unit on which a tip tool is detachably mounted, and a transmission case that houses the transmission mechanism unit are provided in the housing, The transmission mechanism includes a transmission gear and a movable member that is slidable in the axial direction of the transmission gear and that engages or disengages from the transmission gear. By moving the movable member, a plurality of stages are provided. A power tool capable of shifting,
A slide hole provided in the transmission case along the axial direction;
The outer periphery of the transmission case is provided so as to be rotatable about the axial direction, and has a working hole that is provided along a direction inclined with respect to the rotating direction and is disposed so as to overlap the slide hole. A moving member;
A support member protruding from the movable member and inserted through the slide hole and the operation hole;
A drive unit that drives the rotation member to rotate along the outer periphery of the transmission case;
When the driving unit rotates the rotating member in a predetermined direction to a position where the gear shift stage is switched, the rotation due to the reaction force received when the rotation of the rotating member is restricted at the limit position A reverse rotation suppression unit that suppresses rotation of the member in the direction opposite to the predetermined direction through engagement of the support member and the rotation member;
A power tool characterized by comprising:   The reverse rotation suppressing portion increases sliding friction between the support member and the rotation member in both end regions of the rotation range of the rotation member, and causes the sliding member to rotate in the reverse direction. The power tool according to claim 1, wherein a braking force by dynamic friction is applied.   2. The reverse rotation suppressing portion is a hole portion that is continuously drilled at both ends of the operating hole and extends in a direction inclined with respect to a circumferential direction of the rotating member. Or the power tool of 2. The rotating member includes a hole that is continuously drilled at both ends of the operating hole and extends along a circumferential direction of the rotating member;
2. The power tool according to claim 1, wherein the reverse rotation suppressing portion includes an inclined surface that applies a reaction force in a direction intersecting with a longitudinal direction of the hole portion to the support member that hits an end portion of the hole portion. .   The reverse rotation suppressing portion has a second hole portion that extends in a direction of a reaction force received from the inclined surface by the support member that has hit the inclined surface from an end portion in a longitudinal direction of the hole portion. Item 5. The power tool according to Item 4.