JP2019141989A - Working tool - Google Patents

Abstract

To provide an improvement for establishing stable friction contact between a planetary roller and a driving surface in a working tool including a planetary roller type power transmission mechanism which transmits power in response to rearward movement of a spindle.SOLUTION: A power transmission mechanism 4 of a screw driver 1 includes a taper sleeve 41, a gear sleeve 47, a retainer 43, and a roller 45. The taper sleeve 41 and the gear sleeve 47 respectively have taper surfaces 411, 475. The gear sleeve 47 can move integrally with the spindle 3 in an anteroposterior direction relative to the taper sleeve 41. The roller 45 is at least partially disposed between the taper surfaces 411, 475 in a radial direction relative to a driving axis A1. The screw driver 1 includes a biasing spring 49 which restricts the roller 45 from moving in the anteroposterior direction relative to a body housing 11.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a work tool configured to rotationally drive a tip tool.

  2. Description of the Related Art A work tool is known that is configured to rotationally drive a tip tool attached to a front end portion of a spindle and includes a power transmission mechanism (clutch) that transmits motor power to the spindle in response to the pushing of the spindle. . For example, in Patent Document 1, a fixed hub having a tapered surface on the outer periphery and fixed to the housing, a cup-shaped drive gear having a tapered surface on the inner periphery and rotatably held on the spindle, and a fixed A planetary power transmission mechanism is disclosed that includes a planetary roller disposed between the hub and the taper surface of the drive gear, and a planetary roller holding member fixed to the spindle. When the drive gear is rotated by the power of the motor and the spindle is pushed rearward, the planetary roller frictionally contacts the fixed hub and the taper surface of the drive gear and revolves around the spindle axis while rotating. Thereby, the holding member of the planetary roller rotates around the axis integrally with the spindle.

JP 2012-135842 A

  In the power transmission mechanism described above, when the spindle is moved in the axial direction, the drive gear held by the spindle and the holding member of the planetary roller move in a direction toward or away from the fixed hub fixed to the housing. . On the other hand, the planetary roller is arranged loosely in a groove formed in the holding member. For this reason, the planetary roller may move in the axial direction, and the frictional contact with the tapered surface as the drive surface may become unstable.

  In view of such circumstances, the present invention establishes stable frictional contact between a planetary roller and a drive surface in a work tool having a planetary roller type power transmission mechanism that transmits power in accordance with the backward movement of the spindle. The purpose is to provide an improvement to do this.

  According to one aspect of the present invention, a work tool configured to rotationally drive a tip tool is provided. This work tool includes a housing, a spindle, a motor, and a power transmission mechanism.

  The spindle is supported by the housing so as to be movable in the front-rear direction along a predetermined drive shaft extending in the front-rear direction of the work tool and rotatable about the drive shaft. Further, the spindle has a front end portion configured to be detachable from the tip tool. The motor and the power transmission mechanism are accommodated in the housing. The power transmission mechanism includes a sun member, a ring member, and a carrier member that are arranged coaxially with the drive shaft, and a planetary roller that is rotatably held by the carrier member. The sun member and the ring member each have a first tapered surface and a second tapered surface that are inclined with respect to the drive shaft. One of the sun member and the ring member is configured to be movable in the front-rear direction integrally with the spindle with respect to the other. The planetary roller is at least partially disposed between the first tapered surface and the second tapered surface in the radial direction with respect to the drive shaft.

  The power transmission mechanism moves relative to the sun member and the ring member in a direction close to each other in accordance with the backward movement of the spindle, and the planetary roller is brought into a frictional contact state with the sun member and the ring member. It is comprised so that the motive power of a motor may be transmitted. Further, in the power transmission mechanism, the sun member and the ring member move relative to each other in a direction away from each other in accordance with the forward movement of the spindle, and the planetary roller is brought into a non-friction contact state with the sun member and the ring member. Therefore, the transmission of power is cut off. Furthermore, the work tool includes a restricting member configured to restrict the planetary roller from moving in the front-rear direction with respect to the housing. The “movement restriction” here is not limited to completely prohibiting movement, but includes a case where slight movement is allowed.

  The work tool according to this aspect includes a so-called planetary roller type power transmission mechanism. In this power transmission mechanism, at least a part of the planetary roller is disposed between the first taper surface of the sun member and the second taper surface of the ring member in the radial direction with respect to the drive shaft of the spindle (a direction orthogonal to the drive shaft). Has been. One of the sun member and the ring member is movable in the front-rear direction integrally with the spindle with respect to the other. On the other hand, the planetary roller is restricted from moving in the front-rear direction by a restriction member. Therefore, it is possible to reduce the possibility that the planetary roller moves in the front-rear direction with the relative movement of the sun member and the ring member, and the frictional contact with the first and second tapered surfaces becomes unstable.

  In one embodiment of the present invention, the carrier member may be held by the spindle so as to be movable in the front-rear direction with respect to the spindle. In other words, the carrier member may be independent of the spindle with respect to the longitudinal movement. The carrier member needs to be arranged at a position where the planetary roller can be held so as not to come off from between the first tapered surface of the sun member and the second tapered surface of the ring member. On the other hand, according to this aspect, the carrier member can be maintained at an appropriate position regardless of the movement of the spindle. Thereby, compared with the case where a carrier member moves integrally with a spindle, the restriction | limiting regarding the moving amount | distance of the front-back direction of a spindle can be reduced. In particular, when the planetary roller and the first and second tapered surfaces are worn, in order to establish stable frictional contact, the spindle needs to be pushed to a position where the sun member and the ring member are closer to each other. That is, it is necessary to increase the amount of movement of the spindle in the front-rear direction, but according to this aspect, it is possible to appropriately meet such needs.

  In one aspect of the present invention, the carrier member may be held non-rotatable around the drive shaft with respect to the spindle. The carrier member may be configured to rotate integrally with the spindle by the power transmitted via the planetary roller. According to this aspect, it is possible to realize a rational planetary roller type power transmission mechanism using the carrier member as an output member.

  In one aspect of the present invention, the restricting member may be configured to restrict the carrier member from moving in the front-rear direction with respect to the housing. According to this aspect, since the movement of the planetary roller and the carrier member in the front-rear direction is restricted by the restriction member, an appropriate positional relationship between the planetary roller and the carrier member can be more reliably maintained.

  In one aspect of the present invention, the restricting member may include a spring member that biases the spindle and the carrier member so as to be separated from each other in the front-rear direction. The spindle may be held at the foremost position by the biasing force of the spring member at all times. According to this aspect, when the pushing of the spindle is released while restricting the movement of the carrier member by the biasing force of the spring member, the spindle can be returned to the foremost position (that is, the initial position).

  In one aspect of the present invention, the ring member may be supported by the spindle so as to be movable in the front-rear direction integrally with the spindle and to be rotatable around the drive shaft. The spring member may be interposed between the carrier member and the ring member in the front-rear direction. The work tool may further include a receiving member that receives one end of the spring member on the ring member side in a state where the spring member is blocked from rotation of the ring member. According to this aspect, it is possible to prevent the spring member from rotating together with the ring member (so-called co-rotation) and the sliding portion between the spring member and the ring member from generating heat.

  In one aspect of the present invention, the ring member may be configured to be rotated by the power of the motor. The spring member may be configured to bias the ring member and the carrier member forward and backward so as to be separated from each other. In other words, the spring member also has a function of urging the ring member as the driving side member and the carrier member as the driven side member in the power transmission mechanism in the direction of interrupting transmission. According to this aspect, it is possible to realize a plurality of functions of restricting movement of the carrier member in the front-rear direction and blocking power transmission without increasing the number of components.

  In one aspect of the present invention, the ring member may have at least one communication hole that allows communication between the inside and the outside of the ring member. According to this aspect, the flow of air through the communication hole can be generated by the centrifugal force accompanying the drive of the power transmission mechanism (typically, the rotation of the ring member). Thereby, suppression of the local temperature rise in a power transmission mechanism and the smoother circulation of the lubricant distribute | arranged in the housing are realizable. As a result, it is possible to effectively reduce wear of the planetary roller and the first and second tapered surfaces and improve durability.

  1 aspect of this invention WHEREIN: The communicating hole may be formed in the area | region different from the area | region corresponding to a 2nd taper surface among ring members. According to this aspect, the communication hole can be easily formed in the ring member.

It is a side view of the screwdriver concerning a 1st embodiment. It is a longitudinal cross-sectional view of a screw driver. FIG. 3 is a partially enlarged view of FIG. 2. It is sectional drawing in the IV-IV line of FIG. FIG. 4 is a partially enlarged view of FIG. 3. It is the elements on larger scale of FIG. It is a disassembled perspective view of a spindle, a power transmission mechanism, and a position switching mechanism. FIG. 5 corresponds to a cross-sectional view taken along line VIII-VIII in FIG. 3 and is an explanatory view showing a non-friction contact state between a roller, a taper sleeve, and a gear sleeve. It is a longitudinal cross-sectional view of the screw driver in a state where the spindle is moved rearward from the initial position and the power transmission mechanism is in a transmittable state. FIG. 10 corresponds to a cross-sectional view taken along line XX in FIG. 9 and is an explanatory view showing a frictional contact state between a roller, a taper sleeve and a gear sleeve. FIG. 4 is a cross-sectional view taken along line XI-XI in FIG. 3 and is an explanatory view showing a state of the one-way clutch when the gear sleeve is driven to rotate in the forward direction. FIG. 12 is a cross-sectional view corresponding to FIG. 11, illustrating the state of the one-way clutch when the gear sleeve is driven to rotate in the reverse direction. FIG. 5 is a cross-sectional view corresponding to FIG. 4, illustrating the state where the lead sleeve and the gear sleeve are moved rearward. It is a longitudinal cross-sectional view of the screw driver in a state where the locator is in contact with the workpiece and the screw tightening operation is completed. It is a longitudinal cross-sectional view of the screw driver which concerns on 2nd Embodiment. It is sectional drawing in the XVI-XVI line of FIG. It is a disassembled perspective view of a spindle, a power transmission mechanism, and a position switching mechanism. FIG. 16 is a cross-sectional view corresponding to FIG. 15, illustrating the state where the gear sleeve is moved rearward. It is sectional drawing corresponding to FIG. 16, Comprising: It is explanatory drawing which shows the state by which the gear sleeve was moved back. It is a longitudinal cross-sectional view of the screw driver which concerns on 3rd Embodiment. It is sectional drawing in the XXI-XXI line | wire of FIG. It is a disassembled perspective view of a spindle, a power transmission mechanism, and a position switching mechanism. It is the elements on larger scale of FIG.

  Embodiments of the present invention will be described below with reference to the drawings.

[First Embodiment]
With reference to FIGS. 1-14, the screw driver 1 which concerns on 1st Embodiment is demonstrated. The screw driver 1 is an example of a work tool that rotationally drives the tip tool. More specifically, the screw driver 1 mounted on the spindle 3 can be rotationally driven to perform screw tightening work or screw loosening work. It is an example of a simple screw tightening tool.

  First, a schematic configuration of the screw driver 1 will be described. As shown in FIGS. 1 and 2, the screw driver 1 includes a main body portion 10 including a motor 2, a spindle 3, and the like, and a handle portion 17 including a grip portion 171. The main body 10 is formed in an elongated shape extending along a predetermined drive axis A1 as a whole. A driver bit 9 is detachably attached to one end of the main body 10 in the long axis direction (the extending direction of the drive shaft A1). The handle portion 17 is formed in a C shape as a whole, and is connected to the other end portion of the main body portion 10 in the long axis direction in a loop shape. A portion of the handle portion 17 that is separated from the main body portion 10 and linearly extends in a direction substantially orthogonal to the drive shaft A1 constitutes a grip portion 171 that is gripped by the user. One end portion of the grip portion 171 in the long axis direction is disposed on the drive shaft A1, and a trigger 173 that can be pulled by the user is provided at this one end portion. A power cable 179 that can be connected to an external AC power supply is connected to the other end of the gripping portion 171.

  In the screw driver 1 of the present embodiment, when the trigger 173 is pulled by the user, the motor 2 is driven. When the spindle 3 is pushed backward, the power of the motor 2 is transmitted to the spindle 3 and the driver bit 9 is rotationally driven. Thereby, screw tightening work and screw loosening work are performed.

  Hereinafter, the detailed configuration of the screw driver 1 will be described. In the following description, for the sake of convenience, the extending direction of the drive shaft A1 is defined as the front-rear direction of the screw driver 1, the side where the driver bit 9 is attached / detached is the front side, and the side where the gripping portion 171 is disposed is the rear side. Side. Further, the direction perpendicular to the drive axis A1 and corresponding to the extending direction of the gripping portion 171 is defined as the vertical direction, the side where the trigger 173 is disposed is the upper side, and the power cable 179 is connected. The side is defined as the lower side. Further, a direction orthogonal to the front-rear direction and the up-down direction is defined as the left-right direction.

  First, the main body portion 10 and the handle portion 17 will be briefly described. As shown in FIG. 2, the outline of the main body 10 is mainly formed by the main body housing 11. The main body housing 11 includes a cylindrical rear housing 12 that houses the motor 2, a cylindrical front housing 13 that houses the spindle 3, and a central housing 14 disposed between the rear housing 12 and the front housing 13. Including. Note that the front end portion of the central housing 14 has a partition wall 141 disposed so as to be substantially orthogonal to the drive shaft A1. The central housing 14 and the front housing 13 are fixed to the rear housing 12 with screws, so that the three housings are integrated as the main body housing 11. Details including the internal structure of the main body 10 will be described later.

  Further, a cylindrical locator 15 is detachably connected to the front end portion of the front housing 13 so as to cover the front end portion. The locator 15 is movable relative to the front housing 13 in the front-rear direction, and is fixed at an arbitrary position by the user. Thereby, the protrusion amount of the driver bit 9 from the locator 15, that is, the depth of screw tightening is set.

  As shown in FIG. 2, the outline of the handle portion 17 is mainly formed by a handle housing 18. The handle housing 18 is composed of left and right halves. The left half is integrally formed with the rear housing 12. The handle housing 18 accommodates a main switch 174, a rotation direction switch 176, and a controller 178.

  The main switch 174 is a switch for starting the motor 2, and is disposed in the grip 171 on the rear side of the trigger 173. The main switch 174 is normally maintained in an off state and is switched to an on state in accordance with a pulling operation of the trigger 173. The main switch 174 outputs a signal indicating an on state or an off state to the controller 178 via a wiring (not shown).

  A portion of the handle housing 18 connected to the lower end portion of the grip portion 171 and the lower rear end portion of the main body portion 10 (rear housing 12) has a rotation direction of the driver bit 9 (specifically, a rotation direction of the motor shaft 23). ) Is provided for switching. The user operates the switching lever 175 to change the direction of rotation of the motor shaft 23 in the direction in which the driver bit 9 tightens the screw 90 (also referred to as positive direction or screw tightening direction) or the direction in which the driver bit 9 loosens the screw 90. It can be set to one of (reverse direction, also referred to as screw loosening direction). The rotation direction switch 176 outputs a signal corresponding to the rotation direction set via the switching lever 175 to the controller 178 via a wiring (not shown).

  A controller 178 including a control circuit is disposed below the main switch 174. The controller 178 is configured to drive the motor 2 in accordance with the rotation direction indicated by the signal from the rotation direction switch 176 when the signal from the main switch 174 indicates an ON state.

  Hereinafter, a detailed configuration including the internal structure of the main body 10 will be described.

  As shown in FIG. 2, the motor 2 is accommodated in the rear housing 12. In the present embodiment, an AC motor is employed as the motor 2. A motor shaft 23 extending from the rotor 21 of the motor 2 extends below (in the front-rear direction) the drive shaft A1 below the drive shaft A1. The motor shaft 23 is rotatably supported by bearings 231 and 233 at the front end portion and the rear end portion. The front bearing 231 is supported by the partition wall 141 of the central housing 14, and the rear bearing 233 is supported by the rear end portion of the rear housing 12. Further, a fan 25 for cooling the motor 2 is fixed to a portion of the motor shaft 23 on the front side of the rotor 21 and is accommodated in the central housing 14. The front end portion of the motor shaft 23 projects into the front housing 13 through a through hole provided in the partition wall 141. A pinion gear 24 is formed at the front end of the motor shaft 23.

  As shown in FIGS. 3 and 4, the front housing 13 accommodates the spindle 3, the power transmission mechanism 4, and the position switching mechanism 5. Hereinafter, these detailed configurations will be described in order.

  As shown in FIGS. 3 and 4, the spindle 3 is a substantially cylindrical long member, and extends in the front-rear direction along the drive shaft A <b> 1. In the present embodiment, the spindle 3 is configured by integrally connecting a front shaft 31 and a rear shaft 32 that are separately formed and integrated. However, the spindle 3 may be constituted by only a single shaft. The spindle 3 has a flange 34 projecting radially outward at a central portion (specifically, a rear end portion of the front shaft 31) in the front-rear direction.

  The spindle 3 is supported by a bearing (specifically, an oilless bearing) 301 supported on the partition wall 141 of the central housing 14 and a bearing (specifically, a ball bearing) 302 supported on the front end of the front housing 13. It is supported so as to be rotatable around the drive shaft A1 and movable in the front-rear direction along the drive shaft A1. The spindle 3 is normally biased forward by a biasing force of a biasing spring 49 described later, and is held at a position where the front end surface of the flange 34 comes into contact with a stopper portion 135 provided in the front housing 13. ing. The position of the spindle 3 at this time is the foremost position (also referred to as the initial position) in the movable range of the spindle 3. Further, the front end portion of the spindle 3 (front shaft 31) protrudes from the front housing 13 into the locator 15. At the front end of the spindle 3 (front shaft 31), a bit insertion hole 311 is provided along the drive axis A1. When the steel ball urged by the leaf spring is engaged with the small diameter portion of the driver bit 9 inserted into the bit insertion hole 311, the driver bit 9 is detachably held.

  Hereinafter, the power transmission mechanism 4 will be described. As shown in FIGS. 3 and 4, the power transmission mechanism 4 of the present embodiment is mainly configured by a planetary mechanism including a tapered sleeve 41, a retainer 43, a plurality of rollers 45, and a gear sleeve 47. . The taper sleeve 41, the retainer 43, and the gear sleeve 47 are arranged coaxially with the spindle 3 (drive shaft A1). The taper sleeve 41, the retainer 43, the roller 45, and the gear sleeve 47 correspond to a sun member, a carrier member, a planetary member, and a ring member in the planetary mechanism, respectively. In this embodiment, the power transmission mechanism 4 is a so-called solar in which a taper sleeve 41 as a sun member is fixed, a gear sleeve 47 as a ring member operates as an input member, and a retainer 43 as a carrier member operates as an output member. The gear sleeve 47 and the retainer 43 (spindle 3) rotate in the same direction.

  The power transmission mechanism 4 is configured to transmit the power of the motor 2 to the spindle 3 or to block the power transmission. Specifically, in the power transmission mechanism 4, in the front-rear direction, as the gear sleeve 47 moves relative to or away from the taper sleeve 41, the retainer 43, and the roller 45, the roller 45 The taper sleeve 41 and the gear sleeve 47 are configured to be in a frictional contact state or a non-frictional contact state. As a result, the power transmission mechanism 4 is switched between a transmittable state in which the power of the motor 2 can be transmitted to the spindle 3 and a blocked state in which the power of the motor 2 cannot be transmitted to the spindle 3. That is, it can be said that the power transmission mechanism 4 of this embodiment is configured as a planetary roller friction clutch mechanism.

  Below, the detailed structure and arrangement | positioning of each member of the power transmission mechanism 4 are demonstrated.

  First, the taper sleeve 41 will be described. As shown in FIGS. 5-7, the taper sleeve 41 equivalent to a solar member is comprised as a cylindrical member. The taper sleeve 41 is fixed to the main body housing 11 (specifically, the partition wall 141) through the base 143 so as not to rotate around the drive shaft A1. The base 143 is fixed to the partition wall 141 on the front side of the bearing 301 that supports the rear end portion of the spindle 3 (rear shaft 32), and is integrated with the main body housing 11. The spindle 3 (specifically, the rear shaft 32) is inserted into the taper sleeve 41 so as to be loosely fitted, and is movable in the front-rear direction with respect to the taper sleeve 41 and is rotatable.

  The outer peripheral surface of the taper sleeve 41 is configured as a taper surface 411 that is inclined at a predetermined angle with respect to the drive shaft A1. More specifically, the outer shape of the taper sleeve 41 is a truncated cone shape that narrows toward the front (the diameter decreases), and the taper surface 411 tilts in a direction toward the drive axis A1 toward the front. It is configured as. In the present embodiment, the inclination angle of the tapered surface 411 with respect to the drive shaft A1 is set to approximately 4 degrees (approximately 8 degrees when viewed from a conical section).

  Next, the retainer 43 will be described. The retainer 43 as a carrier member is a member that holds a roller 45 as a planetary member in a rotatable manner. As shown in FIGS. 5 to 7, the retainer 43 includes a substantially circular bottom wall 431 having a through hole and a plurality of holding arms 434 protruding from the outer edge of the bottom wall 431. The holding arms 434 are spaced apart from each other in the circumferential direction. In this embodiment, the retainer 43 has ten holding arms 434. However, the number of holding arms 434 (and the number of rollers 45) can be changed as appropriate. The retainer 43 is positioned so that the bottom wall 431 is located on the front side (so that the holding arm 434 protrudes rearward), and with the taper sleeve 41 overlapping a part of the holding arm 434 in the radial direction with respect to the spindle 3. Thus, it is supported by the spindle 3 so that it cannot rotate and is movable in the front-rear direction. Each holding arm 434 protrudes rearward from the outer edge of the bottom wall 431 so as to form the same inclination angle as the tapered surface 411 of the tapered sleeve 41 with respect to the drive shaft A1 (that is, parallel to the tapered surface 411).

  As shown in FIGS. 6 and 7, a pair of grooves 321 are formed in the front portion of the rear end portion of the rear shaft 32 of the spindle 3 with the drive shaft A1 interposed therebetween. Each groove 321 has a U-shaped cross section and extends linearly in the front-rear direction. A steel ball 36 is arranged in each groove 321 so as to be able to roll. A pair of recesses 432 are formed on the rear surface (the surface on the holding arm 434 side) of the bottom wall 431 of the retainer 43 with the drive shaft A1 interposed therebetween. A part of the ball 36 disposed in the groove 321 is engaged with the recess 432. Furthermore, an annular recess 414 is formed at the center of the front end surface of the taper sleeve 41. Although details will be described later, the retainer 43 is biased rearward by a biasing spring 49, the ball 36 is disposed in a space defined by the recesses 414, 432, and the rear surface of the bottom wall 431 is the taper sleeve 41. It is held in contact with the front end surface. Note that the rear end of the holding arm 434 is disposed at a position spaced forward from the base 143.

  With such a configuration, the retainer 43 is engaged with the spindle 3 via the ball 36 in the radial direction and the circumferential direction of the spindle 3, and can rotate integrally with the spindle 3. The ball 36 can roll in the annular recess 414 of the taper sleeve 41, and the retainer 43 can rotate around the drive axis A 1 with respect to the taper sleeve 41 together with the spindle 3. On the other hand, the spindle 3 is movable in the front-rear direction with respect to the retainer 43 within a range in which the ball 36 can roll in the groove 321.

  As shown in FIGS. 5 to 7, the roller 45 corresponding to the planetary member is a columnar member. In the present embodiment, each roller 45 has a constant diameter and is held between adjacent holding arms 434 so as to be capable of rotating about a rotation axis substantially parallel to the tapered surface 411. The length of the roller 45 is set longer than that of the holding arm 434. Further, as shown in FIG. 8, in a state where the roller 45 is held by the holding arm 434, a part of the outer peripheral surface of the roller 45 slightly protrudes from the inner and outer surfaces of the holding arm 434 in the radial direction of the retainer 43. .

  Next, the gear sleeve 47 will be described. As shown in FIGS. 5 to 7, the gear sleeve 47 corresponding to the ring member is configured as a substantially cup-shaped member having an inner diameter larger than the outer diameters of the taper sleeve 41 and the retainer 43.

  The gear sleeve 47 has a bottom wall 471 having a through hole and a cylindrical peripheral wall 474 connected to the bottom wall 471. An outer ring 481 of a bearing (specifically, a ball bearing) 48 is fixed to a portion of the inner peripheral surface of the peripheral wall 474 in the vicinity of the bottom wall 471. The gear sleeve 47 is attached to the spindle 3 in such a direction that the bottom wall 471 is located on the front side (so as to open rearward), and on the front side of the retainer 43 so as to be rotatable with respect to the spindle 3 and movable in the front-rear direction. It is supported. More specifically, the rear shaft 32 of the spindle 3 is inserted into the through hole of the bottom wall 471 so as to be loosely fitted, and is inserted into the inner ring 483 of the bearing 48 so as to be slidable in the front-rear direction. Thereby, on the rear side of the bearing 48, a cylindrical internal space is formed between the spindle 3 and the peripheral wall 474. In this internal space, a part of the taper sleeve 41, the retainer 43 and the roller 45 and a biasing spring 49 described later are arranged. Further, gear teeth 470 that are always meshed with the pinion gear 24 are integrally formed on the outer periphery of the gear sleeve 47 (specifically, the peripheral wall 474), and the gear sleeve 47 is driven to rotate as the motor shaft 23 rotates. Is done.

  Of the peripheral wall 474 of the gear sleeve 47, the inner peripheral surface of the rear portion (portion on the opening end side) of the bearing 48 is inclined at the same angle as the tapered surface 411 of the tapered sleeve 41 with respect to the drive shaft A1 ( That is, it includes a tapered surface 475 (parallel to the tapered surface 411). That is, the taper surface 475 is formed as a conical surface that is inclined in the direction away from the drive shaft A1 toward the rear (the opening end of the gear sleeve 47). The roller 45 held by the retainer 43 has at least a portion (specifically, a front portion) positioned between the tapered surface 411 and the tapered surface 475 in the radial direction of the spindle 3 (direction orthogonal to the drive shaft A1). So that it is held.

  In the present embodiment, the power transmission mechanism 4 includes a biasing spring 49 interposed between the gear sleeve 47, the retainer 43, and the roller 45 in the front-rear direction. In this embodiment, the urging spring 49 is configured as a conical coil spring, and is arranged so that the end on the large diameter side is the rear side and the end on the small diameter side is the front side. More specifically, the end on the large diameter side is in contact with the large diameter washer 491, and the end on the small diameter side is in contact with the small diameter washer 493. The washer 491 is disposed so as to contact the front end surface of the holding arm 434 of the retainer 43. The washer 493 is disposed so as to contact the inner ring 483 of the bearing 48 attached in the gear sleeve 47 but not to the outer ring 481. That is, the urging spring 49 can rotate together with the retainer 43, but is blocked from the rotation of the gear sleeve 47.

  The urging spring 49 always urges the retainer 43 and the gear sleeve 47 in directions away from each other, that is, backward and forward via the washers 491 and 493, respectively. Accordingly, the retainer 43 is held at a position where the rear surface of the bottom wall 431 comes into contact with the front end surface of the taper sleeve 41 by the biasing force of the biasing spring 49, and its movement in the front-rear direction is restricted. Further, the roller 45 is held between the washer 491 and the front end surface of the base 143 fixed to the main body housing 11, and its movement in the front-rear direction is restricted. Here, “movement is restricted” does not mean that movement is completely prohibited, and slight movement may be allowed. In this embodiment, the distance between the washer 491 and the front end surface of the base 143 is set slightly longer than the roller 45 (that is, play is provided), and the movement of the roller 45 corresponding to this play is Is allowed. The biasing spring 49 may be in direct contact with the retainer 43 and the inner ring 483 without using the washers 491 and 493.

  Further, the gear sleeve 47 is urged forward by the urging force of the urging spring 49, whereby the spindle 3 is also urged forward via a thrust bearing 53, a lead sleeve 500 and a ball 508, which will be described later, and the flange 34 is It is held at the initial position where it abuts against the stopper portion 135.

  When the spindle 3 is disposed at the initial position, the roller 45 is loosely fitted between the tapered surface 411 of the tapered sleeve 41 and the tapered surface 475 of the gear sleeve 47 as shown in FIGS. (More specifically, spaced from the tapered surface 475) and in non-frictional contact with the tapered sleeve 41 and the gear sleeve 47. That is, the power transmission mechanism 4 is in a shut-off state. On the other hand, as shown in FIG. 9, the gear sleeve 47 moves rearward with respect to the main body housing 11 (close to the taper sleeve 41, the retainer 43 and the roller 45), and the taper surface 411 of the taper sleeve 41 and the gear sleeve 47 When the interval with the taper surface 475 is narrowed, the roller 45 is sandwiched between the taper surface 411 and the taper surface 475 as shown in FIG. 10 and is brought into frictional contact with the taper sleeve 41 and the gear sleeve 47. Thereby, the power transmission mechanism 4 shifts to a transmittable state. The operation of the power transmission mechanism 4 will be described in detail later.

  Hereinafter, the position switching mechanism 5 will be described. The position switching mechanism 5 is a mechanism that relatively moves the gear sleeve 47 and the front end portion of the spindle 3 away from each other in the front-rear direction when the gear sleeve 47 is rotationally driven in the reverse direction (screw loosening direction). It is. With this configuration, the position switching mechanism 5 allows the gear sleeve 47 to move rearward with respect to the spindle 3 when the gear sleeve 47 is rotationally driven in the reverse direction (screw loosening direction) with the spindle 3 placed in the initial position. It is moved and brought close to the retainer 43 and the roller 45. Hereinafter, details of the position switching mechanism 5 will be described.

  As shown in FIGS. 5 to 7, in the present embodiment, the position switching mechanism 5 is mainly configured by a one-way clutch 50, a lead sleeve 500 having a lead groove 507, and a ball 508.

  In the present embodiment, the one-way clutch 50 includes a cam groove 501 formed at the front end portion of the gear sleeve 47 and a ball 502, and the lead sleeve 500 is moved only when the gear sleeve 47 is driven to rotate in the reverse direction. It is configured to rotate integrally with the gear sleeve 47.

  As shown in FIGS. 7 and 11, the cam groove 501 is a groove that is recessed from the outer peripheral surface of the peripheral wall 474 at the front end portion of the gear sleeve 47 to the radially inner side of the gear sleeve 47, and is formed in the radial direction from the outer peripheral surface. In the forward direction (screw tightening direction) of the gear sleeve 47 indicated by an arrow A in the figure, the depth decreases from the upstream side to the downstream side (the reverse direction of the gear sleeve 47 indicated by the arrow B in the figure (screw loosening direction). ), The size increases from the upstream side toward the downstream side. In the present embodiment, four cam grooves 501 are provided at equal intervals in the circumferential direction around the drive shaft A1. A steel ball 502 is disposed in each cam groove 501. As shown in FIG. 11, the diameter of the ball 502 is set to be slightly larger than the depth of the deepest portion (that is, the upstream end portion in the positive direction) of the cam groove 501.

  As shown in FIGS. 5 to 7, the lead sleeve 500 is formed as a substantially cub-shaped member, and includes a bottom wall 505 having a through hole and a cylindrical peripheral wall 504 protruding from the outer edge of the bottom wall 505. Have. The lead sleeve 500 is arranged between the gear sleeve 47 and the flange 34 of the spindle 3 in a state where the bottom wall 505 is disposed on the front side and the rear shaft 32 of the spindle 3 is inserted into the through hole of the bottom wall 505 in a loose fit. Is arranged. Between the rear surface of the bottom wall 505 and the front end surface of the bottom wall 471 of the gear sleeve 47, a thrust bearing that receives a thrust load while allowing the lead sleeve 500 to rotate with respect to the gear sleeve 47 (specifically, a thrust ball bearing) 53 is arranged. Note that annular recesses having a U-shaped cross section are formed on the rear surface of the bottom wall 505 and the front end surface of the bottom wall 471, respectively. A ball as a rolling element of the thrust bearing 53 can roll in an annular track defined by these recesses.

  The inner diameter of the peripheral wall 504 is set to be slightly larger than the outer diameter of the front end portion of the gear sleeve 47 in which the cam groove 501 is formed, and the peripheral wall 504 is disposed so as to surround the outer peripheral surface of the front end portion of the gear sleeve 47. Has been. As shown in FIG. 11, in the deepest portion of the cam groove 501, the radial distance between the wall surface of the cam groove 501 and the inner peripheral surface of the peripheral wall 504 is set slightly larger than the diameter of the ball 502. Has been.

  With such a configuration, the one-way clutch 50 rotates the lead sleeve 500 integrally with the gear sleeve 47 only when the gear sleeve 47 is driven to rotate in the reverse direction. Specifically, as shown in FIG. 11, when the gear sleeve 47 is rotationally driven in the forward direction (arrow A direction in the figure), the ball 502 is the deepest part of the cam groove 501 (forward direction (arrow A direction)). Relative to the upstream end). The ball 502 rotates around the drive shaft A <b> 1 together with the gear sleeve 47 in a state of being freely fitted between the wall surface of the cam groove 501 and the inner peripheral surface of the peripheral wall 504. That is, the one-way clutch 50 is in a disconnected state, and the rotational force of the gear sleeve 47 is not transmitted to the lead sleeve 500.

  On the other hand, as shown in FIG. 12, when the gear sleeve 47 is rotationally driven in the reverse direction (the direction of arrow B in the figure), the ball 502 moves from the deepest portion of the cam groove 501 to the shallower portion (in the reverse direction (arrow B). Move relative to the upstream side). As a result, the ball 502 is sandwiched between the wall surface of the cam groove 501 and the inner peripheral surface of the peripheral wall 504, and the gear sleeve 47 and the lead sleeve 500 are integrated via the ball 502 by the frictional force due to the wedge action. That is, the one-way clutch 50 shifts to a transmittable state, and the lead sleeve 500 is rotated in the reverse direction together with the gear sleeve 47.

  The lead groove 507 and the ball 508 move the lead sleeve 500 relative to the spindle 3 in the front-rear direction with the rotation of the lead sleeve 500 around the drive axis A1, thereby causing the gear sleeve 47 and the retainer 43 and The roller 45 is configured to move relative to the front-rear direction. As shown in FIGS. 5 to 7, in the present embodiment, the lead groove 507 corresponds to a spiral groove (strictly speaking, a part of the spiral formed in the front end surface of the bottom wall 505 of the lead sleeve 500. Three grooves are formed at equal intervals in the circumferential direction so as to be separated from each other. More specifically, the lead groove 507 has a depth in the front-rear direction from the front end surface that decreases from the upstream side to the downstream side in the positive direction (screw tightening direction) of the gear sleeve 47 indicated by arrow A in FIG. (In the reverse direction (screw loosening direction) of the gear sleeve 47 indicated by the arrow B in FIG. 7, it increases from the upstream side toward the downstream side). A steel ball 508 is disposed in each lead groove 507.

  As described above, the gear sleeve 47 is always biased forward by the biasing spring 49 disposed between the retainer 43 and the gear sleeve 47 (specifically, the bearing 48). For this reason, as shown in FIGS. 5 and 6, the thrust bearing 53, the lead sleeve 500, and the ball 508 are also urged forward, and the ball 508 is in contact with the rear surface of the flange 34. The spindle 3 is also urged forward through the flange 34 and is always held at the initial position.

  With such a configuration, the relative positional relationship between the spindle 3 and the lead sleeve 500 in the front-rear direction changes according to the position of the ball 508 in the lead groove 507. More specifically, as shown in FIG. 4, when the ball 508 is disposed at the deepest portion of the lead groove 507 (that is, the upstream end portion in the forward direction), the flange 34 and the lead sleeve 500 in the front-rear direction are arranged. The distance is minimal. That is, the lead sleeve 500 is disposed at the foremost position within the movable range with respect to the spindle 3. In a state where the spindle 3 is disposed at the initial position, the gear sleeve 47 is disposed at the most separated position farthest from the retainer 43 and the roller 45 in the front-rear direction.

  On the other hand, when the one-way clutch 50 is operated as described above and the lead sleeve 500 is rotated in the reverse direction together with the gear sleeve 47, the ball 508 moves from the deepest portion of the lead groove 507 to the shallowest portion (in the reverse direction). Move relatively upstream). Since the ball 508 is in contact with the rear surface of the flange 34, the lead sleeve 500 moves away from the flange 34 against the urging force according to the relative movement of the ball 508 as shown in FIG. Move backward (with respect to spindle 3). As a result, the lead sleeve 500 moves the gear sleeve 47 backward against the spindle 3 against the urging force of the urging spring 49, that is, in a direction close to the retainer 43 and the roller 45. When the ball 508 is disposed at the shallowest portion, the distance between the flange 34 and the lead sleeve 500 in the front-rear direction is maximized. In a state where the spindle 3 is disposed at the initial position, the gear sleeve 47 is disposed at an intermediate position closer to the retainer 43 and the roller 45 than when disposed at the most separated position. That is, the relative positions of the gear sleeve 47, the retainer 43, and the roller 45 are switched from the most separated position to the intermediate position.

  Hereinafter, operations of the power transmission mechanism 4 and the position switching mechanism 5 accompanying the driving of the motor 2 and the movement of the spindle 3 will be described.

  First, in an initial state in which the motor 2 is not driven and an external force directed backward is not applied to the spindle 3, the spindle 3 is disposed at the initial position by the biasing force of the biasing spring 49. As described above, at this time, as shown in FIGS. 5 and 8, the roller 45 is in a non-frictional contact state with the taper sleeve 41 and the gear sleeve 47. That is, the power transmission mechanism 4 is in a shut-off state.

  When the forward direction (screw tightening direction) is set as the rotation direction of the motor shaft 23 via the switching lever 175, the screw driver 1 operates as follows to perform the screw tightening operation.

  When the trigger 173 is pulled by the user and the main switch 174 is turned on with the spindle 3 placed at the initial position, the controller 178 starts driving the motor 2. As shown by an arrow A in FIG. 11, the gear sleeve 47 is driven to rotate in the forward direction (screw tightening direction). As described above, since the one-way clutch 50 does not operate at this time, the rotational force of the gear sleeve 47 is not transmitted to the lead sleeve 500. Therefore, the gear sleeve 47, the retainer 43, and the roller 45 are maintained at the most separated position. Further, since the power transmission mechanism 4 is in the shut-off state, the rotational force of the gear sleeve 47 is not transmitted to the spindle 3 and the gear sleeve 47 is idled in the forward direction.

  As shown in FIG. 12, the ball 502 is sandwiched between the wall surface of the cam groove 501 and the inner peripheral surface of the peripheral wall 504 (that is, the gear sleeve 47, the retainer 43, and the roller 45 are disposed at intermediate positions). In the state), the screw loosening operation described later may end. In this case, the pinching of the ball 502 is released according to the rotation of the gear sleeve 47 in the forward direction, and the lead sleeve 500 is moved to the foremost position by the biasing force of the biasing spring 49 and the action of the lead groove 507 and the ball 508. Return. Thereby, the gear sleeve 47, the retainer 43, and the roller 45 are returned from the intermediate position to the most separated position.

  When the user moves the screw driver 1 forward (toward the workpiece 900) in the idling state of the gear sleeve 47 and presses the screw 90 engaged with the driver bit 9 against the workpiece 900, the spindle 3 The main body housing 11 is pushed rearward against the biasing force of the biasing spring 49. Pushed by the flange 34, the ball 508, the lead sleeve 500, the thrust bearing 53, and the gear sleeve 47 also move backward with respect to the main body housing 11 integrally with the spindle 3. On the other hand, the taper sleeve 41 is fixed to the main body housing 11, and the retainer 43 and the roller 45 are held in a state where movement in the front-rear direction with respect to the main body housing 11 is restricted. Therefore, the gear sleeve 47 approaches the taper sleeve 41, the retainer 43, and the roller 45 as it moves rearward, and the radial distance between the taper surface 411 of the taper sleeve 41 and the taper surface 475 of the gear sleeve 47 gradually increases. It narrows to.

  Accordingly, as shown in FIGS. 9 and 10, the roller 45 held by the retainer 43 is sandwiched between the tapered surface 411 and the tapered surface 475 to be in a frictional contact state (the roller 45 and the tapered surface 411). The frictional force due to the wedge action is generated at the contact portion with 475). That is, the gear sleeve 47, the retainer 43, and the roller 45 are disposed at a transmission position where the rotational force from the gear sleeve 47 to the retainer 43 can be transmitted via the roller 45. The roller 45 receives the rotation of the gear sleeve 47 and revolves while rotating on the taper surface 411 of the taper sleeve 41 to rotate the retainer 43 around the drive shaft A1. Since the retainer 43 is integrated with the spindle 3 in the circumferential direction around the drive shaft A1, the spindle 3 is also rotated together with the retainer 43. In this way, as the spindle 3 moves rearward from the initial position, the power transmission mechanism 4 shifts from the shut-off state to the transmittable state, and tightening of the screw 90 with respect to the workpiece 900 is started. The spindle 3 rotates in the same direction as the gear sleeve 47 at a speed slower than the rotation speed of the gear sleeve 47.

  When the tightening of the screw 90 to the workpiece 900 proceeds and the tip of the locator 15 comes into contact with the workpiece 900 as shown in FIG. 14, the portion that receives the pressing force shifts from the spindle 3 to the locator 15. Therefore, the pressing force on the spindle 3 gradually decreases. For this reason, it corresponds to the sum of the force by which the roller 45 is sandwiched between the taper surface 411 of the taper sleeve 41 and the taper surface 475 of the gear sleeve 47 (the pressing force of the spindle 3 and the force of urging the spindle 3 forward by the urging spring 49. As a result, the rotational force transmitted from the gear sleeve 47 to the spindle 3 also gradually decreases. When the rotational force transmitted from the gear sleeve 47 to the spindle 3 falls below the rotational force necessary for tightening the screw 90, the rotation of the screw 90 is stopped and the screw tightening operation is completed.

  On the other hand, when the reverse direction (screw loosening direction) is set as the rotation direction of the motor shaft 23 via the switching lever 175, the screw driver 1 operates as follows to perform the screw loosening operation.

  When the trigger 173 is pulled by the user and the main switch 174 is turned on with the spindle 3 placed at the initial position, the controller 178 starts driving the motor 2. As shown by an arrow B in FIG. 12, the gear sleeve 47 is rotationally driven in the reverse direction (screw loosening direction). As a result, the one-way clutch 50 operates to rotate the lead sleeve 500 in the reverse direction as described above, and the gear sleeve 47 is biased by the biasing spring 49 by the action of the lead groove 507 and the ball 508 as shown in FIG. It is moved backward in the direction approaching the retainer 43 and the roller 45 against the spindle 3 against the urging force. In other words, in the screw loosening operation, regardless of whether or not the spindle 3 is moved rearward (with the spindle 3 disposed at the initial position), the gear sleeve 47 is driven in accordance with the rotational drive of the gear sleeve 47 in the reverse direction. 47, the relative position of the retainer 43 and the roller 45 is switched from the most distant position to the intermediate position.

  As shown in FIG. 13, when the gear sleeve 47, the retainer 43, and the roller 45 are disposed at the intermediate position, the roller 45 is separated from the tapered surface 475 as in the case of being disposed at the most distant position. The taper sleeve 41 and the gear sleeve 47 are in a non-frictional contact state. Therefore, the rotational force of the gear sleeve 47 is not transmitted to the spindle 3. That is, the power transmission mechanism 4 is in a shut-off state, and the gear sleeve 47 is idled in the reverse direction.

  When the user moves the screw driver 1 forward and presses the driver bit 9 against the screw 90 fastened to the work piece 900 in the idling state of the gear sleeve 47, the spindle 3 is urged. The main body housing 11 is pushed rearward against the urging force of 49. The gear sleeve 47 is close to the taper sleeve 41, the retainer 43, and the roller 45, and the gear sleeve 47, the retainer 43, and the roller 45 are disposed at the transmission position. The roller 45 is sandwiched between the taper surface 411 and the taper surface 475 to be in a frictional contact state, the power transmission mechanism 4 is shifted from the shut-off state to the transmittable state, the screw 90 is loosened, and is removed from the workpiece 900. The

  As described above, during the screw loosening operation, the position switching mechanism 5 moves the gear sleeve 47 rearward relative to the spindle 3 than during the screw tightening operation, and the distance between the gear sleeve 47, the retainer 43, and the roller 45 in the front-rear direction. Has been made smaller. Therefore, the movement distance in the front-rear direction of the spindle 3 until the gear sleeve 47, the retainer 43, and the roller 45 are relatively moved from the intermediate position to the transmission position (in other words, the state where the power transmission mechanism 4 can transmit from the shut-off state during the screw loosening operation). The amount of movement of the spindle 3 or the amount of push-in until it shifts to is the distance that the gear sleeve 47, the retainer 43 and the roller 45 move relative to the transmission position from the most distant position (the power transmission mechanism 4 is This is smaller than the movement amount or push-in amount of the spindle 3 until the transition from the shut-off state to the transmittable state. In this embodiment, the moving distance during the screw loosening operation is set to be shorter by about 1 millimeter than the moving distance of the spindle 3 during the screw tightening operation. Thereby, the user can loosen the screw 90 fastened to the workpiece 900 without removing the locator 15 from the front housing 13.

  In the above description, the operation in the case where the spindle 3 is pushed rearward after the start of driving of the motor 2 is illustrated, but before the spindle 3 is pushed rearward and the power transmission mechanism 4 shifts to the transmittable state. The operation when the driving of the motor 2 is started is basically the same. In the case of the screw loosening operation, depending on the position of the spindle 3, the power transmission mechanism 4 shifts to the transmission state by being moved to the rear of the gear sleeve 47 by the position switching mechanism 5 in response to the start of driving of the motor 2. There is a case. Further, when the driving of the motor 2 is started after the spindle 3 is pushed rearward and the power transmission mechanism 4 shifts to the transmittable state, the rotation driving of the spindle 3 is started in response to the driving start of the motor 2. Will be.

[Second Embodiment]
Hereinafter, the screwdriver 100 according to the second embodiment will be described with reference to FIGS. 15 to 19. In addition, although the screw driver 100 of this embodiment is provided with the power transmission mechanism 6 and the position switching mechanism 7 different from the power transmission mechanism 4 and the position switching mechanism 5 (refer FIGS. 5-7) of 1st Embodiment. The other configuration is substantially the same as that of the screw driver 1. Therefore, in the following description, substantially the same configurations as those in the first embodiment are denoted by the same reference numerals, description thereof is omitted or simplified, and different configurations are mainly described.

  As shown in FIGS. 15 to 17, the power transmission mechanism 6 of the present embodiment includes a planetary mechanism including a tapered sleeve 41, a retainer 43, a plurality of rollers 45, and a gear sleeve 67 that are arranged coaxially. It is configured as a subject. The configuration of the power transmission mechanism 6 other than the gear sleeve 67 is substantially the same as the configuration of the power transmission mechanism 4 of the first embodiment.

  The gear sleeve 67 of this embodiment is configured as a substantially cup-shaped member having an inner diameter larger than the outer diameters of the taper sleeve 41 and the retainer 43, and the gear sleeve 47 of the first embodiment except for the configuration of the front end portion. It has the same configuration. More specifically, the gear sleeve 67 has a bottom wall 671 having a through hole and a cylindrical peripheral wall 674 connected to the bottom wall 671, and is rotatable relative to the spindle 3 on the front side of the retainer 43. Further, the spindle 3 is supported so as to be movable in the front-rear direction. In the internal space of the gear sleeve 67, a part of the taper sleeve 41, the retainer 43 and the roller 45 and an urging spring 49 are arranged. Further, gear teeth 670 that are always meshed with the pinion gear 24 are integrally formed on the outer periphery of the gear sleeve 67 (specifically, the peripheral wall 674). Similar to the peripheral wall 474 of the first embodiment, the inner peripheral surface of the peripheral wall 674 is inclined at the same angle as the tapered surface 411 of the tapered sleeve 41 with respect to the drive shaft A1 (that is, parallel to the tapered surface 411). including.

  Further, unlike the gear sleeve 47 of the first embodiment, the gear sleeve 67 of the present embodiment has a lead groove 707 formed in the front end portion (specifically, the front end surface of the bottom wall 671). The lead groove 707 has the same configuration as the lead groove 507 of the lead sleeve 500 of the first embodiment. That is, the lead groove 707 is formed as a spiral groove (strictly, a groove having a shape corresponding to a part of the spiral), and three lead grooves 707 are provided at regular intervals in the circumferential direction so as to be separated from each other. The lead groove 707 has a depth in the front-rear direction from the front end surface that decreases from the upstream side to the downstream side in the forward direction (screw tightening direction) of the gear sleeve 67 indicated by arrow A in FIG. In the reverse direction (screw loosening direction) of the gear sleeve 67 indicated by the arrow B, the gear sleeve 67 increases from the upstream side to the downstream side).

  Similarly to the position switching mechanism 5 of the first embodiment, when the gear sleeve 67 is rotationally driven in the reverse direction (screw loosening direction), the position switching mechanism 7 of the present embodiment also includes the gear sleeve 67 and the front end portion of the spindle 3. Are relatively moved in the direction away from each other in the front-rear direction. With this configuration, the position switching mechanism 7 allows the gear sleeve 67 to move rearward with respect to the spindle 3 when the gear sleeve 67 is rotationally driven in the reverse direction (screw loosening direction) with the spindle 3 in the initial position. It is moved and brought close to the retainer 43 and the roller 45.

  As shown in FIGS. 15 to 17, in the present embodiment, the position switching mechanism 7 is composed mainly of a one-way clutch 70, a flange sleeve 700, a lead groove 707 formed in the gear sleeve 67, and a ball 708. Has been.

  In the present embodiment, a known general-purpose one-way clutch is employed as the one-way clutch 70. The one-way clutch 70 is formed in a cylindrical shape, and is externally mounted on the rear shaft 32 on the rear side of the flange 34 of the spindle 3. The one-way clutch 70 is configured to be rotatable in the forward direction with respect to the spindle 3 but not rotatable in the reverse direction. The flange sleeve 700 includes a cylindrical peripheral wall 701 and a flange 703 that protrudes radially outward from the front end of the peripheral wall 701. An annular concave portion with which the ball 708 abuts is formed on the outer edge portion of the rear surface of the flange 703. The peripheral wall 701 is fixed to the outer periphery of the one-way clutch 70. In the front-rear direction, a thrust bearing that receives a thrust load while allowing the flange sleeve 700 to rotate with respect to the spindle 3 is provided between the rear surface of the flange 34 of the spindle 3 and the front surface of the flange 703 of the flange sleeve 700. Ball bearing) 53 is disposed. An annular recess having a U-shaped cross section is formed on the rear surface of the flange 34 and the front surface of the flange 703, respectively. A ball as a rolling element of the thrust bearing 53 can roll in an annular track defined by these recesses.

  The lead groove 707 and the ball 708 move the gear sleeve 67 relative to the spindle 3 in the front-rear direction as the gear sleeve 67 rotates around the drive axis A1 with respect to the flange sleeve 700. The gear sleeve 67 is configured to move relative to the retainer 43 and the roller 45 in the front-rear direction. As described above, in the present embodiment, the lead groove 707 is formed on the front end surface of the bottom wall 671 of the gear sleeve 67. A steel ball 708 is disposed in each lead groove 707.

  Further, as described above, the gear sleeve 67 is always biased forward by the biasing spring 49 disposed between the retainer 43 and the gear sleeve 67 (specifically, the bearing 48). Therefore, as shown in FIGS. 15 and 16, the spindle 3 is also urged forward through the ball 708, the flange sleeve 700, and the thrust bearing 53, and is always held at the initial position.

  With such a configuration, the relative positional relationship between the spindle 3 and the flange sleeve 700 and the gear sleeve 67 in the front-rear direction changes according to the position of the ball 708 in the lead groove 707. More specifically, as shown in FIGS. 15 and 16, when the ball 708 is disposed at the deepest portion (that is, the upstream end portion in the positive direction) of the lead groove 707, the flange 703 and the gear in the front-rear direction are arranged. The distance of the sleeve 67 is minimized. That is, the gear sleeve 67 is disposed at the foremost position within the movable range with respect to the spindle 3. In a state where the spindle 3 is disposed at the initial position, the gear sleeve 67 is disposed at the most separated position farthest from the retainer 43 and the roller 45 in the front-rear direction.

  At this time, by the urging force of the urging spring 49, the ball 708 disposed in the lead groove 707 is pressed against and engaged with an annular recess formed on the outer edge portion of the rear surface of the flange 703. As described above, the one-way clutch 70 and the flange sleeve 700 are rotatable in the forward direction with respect to the spindle 3. For this reason, when the gear sleeve 67 is driven to rotate in the forward direction, the flange sleeve 700 rotates in the forward direction together with the gear sleeve 67 by the frictional force between the flange 703 and the ball 708 held at the deepest portion of the lead groove 707. Is done. That is, when the gear sleeve 67 is rotationally driven in the forward direction, the one-way clutch 70 allows the flange sleeve 700 to rotate integrally with the gear sleeve 67.

  On the other hand, as described above, since the one-way clutch 70 cannot rotate in the reverse direction with respect to the spindle 3, when the gear sleeve 67 is driven to rotate in the reverse direction, the one-way clutch 70 causes the flange sleeve 700 to move to the spindle 3. Rotation in the opposite direction is prohibited. That is, the flange sleeve 700 is integrated with the spindle 3. For this reason, the gear sleeve 67 rotates relative to the flange sleeve 700 in the opposite direction. Accordingly, the ball 708 relatively moves from the deepest portion of the lead groove 707 to the shallowest portion (upstream side in the reverse direction). Since the ball 708 is in contact with the rear surface of the flange 703, the gear sleeve 67 rotates in the opposite direction in accordance with the relative movement of the ball 708 as shown in FIGS. In the direction away from the flange 703 against the urging force of 49 (rearward with respect to the spindle 3), that is, in the direction approaching the retainer 43 and the roller 45. When the ball 708 is disposed at the shallowest portion, the distance between the flange 703 and the gear sleeve 67 in the front-rear direction is maximized. In a state where the spindle 3 is disposed at the initial position, the gear sleeve 67 is disposed at an intermediate position closer to the retainer 43 and the roller 45 than when disposed at the most separated position. That is, the relative positions of the gear sleeve 67, the retainer 43, and the roller 45 are switched from the most separated position to the intermediate position.

[Third Embodiment]
The screw driver 110 according to the third embodiment will be described below with reference to FIGS. The screw driver 110 of this embodiment includes a power transmission mechanism 8 different from the screw driver 100 (see FIGS. 15 to 17) of the second embodiment, but the configuration other than the power transmission mechanism 8 is a screw driver. 100 is substantially the same. Therefore, below, about the structure substantially the same as the screw driver 100, the same code | symbol is attached | subjected, description is abbreviate | omitted or simplified, and a mainly different structure is demonstrated.

  As shown in FIGS. 20 to 22, the power transmission mechanism 8 of this embodiment is a planetary mechanism including a tapered sleeve 41, a retainer 83, a plurality of rollers 45, and a gear sleeve 87 that are arranged coaxially. It is configured as a subject. The configuration of the power transmission mechanism 8 other than the retainer 83 and the gear sleeve 87 is substantially the same as the configuration of the power transmission mechanism 6 (see FIGS. 15 to 17).

  Similar to the retainer 43 (see FIGS. 15 to 17) of the second embodiment, the retainer 83 of the present embodiment corresponds to a carrier member in the planetary mechanism, and is configured to hold the roller 45 in a rotatable manner. The retainer 83 has the same configuration as the retainer 43 except for the configuration of the front end. More specifically, the retainer 83 includes a substantially cylindrical bottom wall 831 having a through hole in the center, an annular flange portion 832 that protrudes radially outward from the front end portion of the bottom wall 831, and a peripheral edge of the flange portion 832. And a plurality of holding arms 834 protruding rearward from the rear surface of the portion. The bottom wall 831 and the holding arm 834 have substantially the same configuration as the bottom wall 431 and the holding arm 434 of the retainer 43. With such a configuration, the front end of the holding space of the roller 45 formed between the holding arms 45 adjacent in the circumferential direction is closed by the flange portion 832. In this embodiment, instead of omitting the washer 491 (see FIGS. 15 to 17), the front surface of the flange portion 832 functions as a spring receiving portion that receives a biasing force to the rear of the biasing spring 49. Further, the rear surface of the flange portion 832 contacts the front end of the roller 45 and functions as a restricting surface that restricts the forward movement of the roller 45.

  The retainer 83 is the same as the retainer 43, with the bottom wall 831 positioned in the front side (so that the holding arm 834 projects rearward), and with the holding arm 834 partially overlapping the tapered sleeve 41 in the radial direction. The spindle 3 is supported so that it cannot rotate with respect to the spindle 3 and is movable in the front-rear direction. Further, each holding arm 834 protrudes rearward from the rear surface of the peripheral edge portion of the flange portion 832 so as to form the same inclination angle as the tapered surface 411 of the tapered sleeve 41 with respect to the drive shaft A1.

  The gear sleeve 87 of the present embodiment is configured as a substantially cup-shaped member having substantially the same configuration as the gear sleeve 67 (see FIGS. 15 to 17) of the second embodiment. More specifically, the gear sleeve 87 has a substantially circular bottom wall 871 having a through-hole in the center and a cylindrical peripheral wall 874 connected to the bottom wall 871. The bottom wall 871 has substantially the same configuration as the bottom wall 671 of the gear sleeve 67. The basic configuration of the peripheral wall 874 is the same as that of the peripheral wall 674 of the gear sleeve 67 except that a communication hole 878 described later is provided. Specifically, an outer ring 481 of the bearing 48 is fixed in the front end portion of the peripheral wall 874. Further, gear teeth 870 that always mesh with the pinion gear 24 are integrally formed on the outer periphery of the gear sleeve 87 (specifically, the peripheral wall 874).

  As shown in FIG. 23, the rear portion of the inner peripheral surface of the peripheral wall 874 with respect to the rear end of the bearing 48 includes a tapered surface 875 and a cylindrical surface 876. The tapered surface 875 is a conical surface inclined at the same angle as the tapered surface 411 of the tapered sleeve 41 with respect to the drive shaft A1. The tapered surface 875 occupies the latter half of the inner peripheral surface of the peripheral wall 874. The cylindrical surface 876 is connected to the front end of the tapered surface 875, and extends in a generally cylindrical shape along the drive axis A1.

  The communication hole 878 is a through hole that penetrates the peripheral wall 874 in the radial direction, and communicates the inside (internal space) and the outside of the gear sleeve 87. In the present embodiment, the communication hole 878 is formed on the tapered surface 875 in the region R1 between the rear end of the peripheral wall 874 and the rear end of the bearing 48 (that is, the region defining the internal space of the gear sleeve 87). It is provided in a region different from the corresponding region R2, that is, a region R3 corresponding to the cylindrical surface 876. In other words, the communication hole 878 is normally disposed in a region that does not overlap the roller 45 in the radial direction. In the present embodiment, four communication holes 878 are provided at equal intervals in the circumferential direction.

  As shown in FIGS. 21 and 22, also in this embodiment, the gear sleeve 87 is supported by the spindle 3 so as to be rotatable relative to the spindle 3 and movable in the front-rear direction on the front side of the retainer 83. Yes. Further, in the internal space of the gear sleeve 87, a part of the taper sleeve 41, the retainer 83 and the roller 45, and a biasing spring 49 are disposed.

  In this embodiment, the end portion (front end portion) on the small diameter side of the biasing spring 49 contacts the washer 493 that contacts the inner ring 483 of the bearing 48, while the end portion (rear end portion) on the large diameter side is the retainer. 83 is in contact with the front surface of the flange portion 832. The urging spring 49 always urges the retainer 83 and the gear sleeve 87 in directions away from each other, that is, rearward and forward. Accordingly, the retainer 83 is held at a position where the rear surface of the bottom wall 831 comes into contact with the front end surface of the taper sleeve 41 by the biasing force of the biasing spring 49, and its movement in the front-rear direction is restricted. The roller 45 is held between the rear surface of the flange portion 832 of the retainer 83 and the front end surface of the base 143, and movement in the front-rear direction is restricted. Note that, as described in the first embodiment, “movement is restricted” here does not mean that movement is completely prohibited, and slight movement may be allowed. Further, when the gear sleeve 87 is urged forward by the urging force of the urging spring 49, the spindle 3 is also urged forward and held at the initial position.

  The operation of the power transmission mechanism 8 configured as described above is substantially the same as that of the power transmission mechanisms 4 and 6 of the first and second embodiments. Specifically, in the initial state, the spindle 3 is disposed at the initial position by the biasing force of the biasing spring 49, and the roller 45 is in non-friction contact with the taper surface 411 of the taper sleeve 41 and the taper surface 875 of the gear sleeve 87. Is in a state. That is, the power transmission mechanism 8 is in a cut-off state. Thereafter, as the spindle 3 is pushed backward against the biasing force of the biasing spring 49, the gear sleeve 87 approaches the taper sleeve 41, the retainer 83 and the roller 45. Then, the roller 45 held by the retainer 83 is sandwiched between the taper surface 411 and the taper surface 875 and is brought into a frictional contact state. Thereby, the power transmission mechanism 8 shifts from the shut-off state to the transmittable state.

  As described above, the screw drivers 1, 100, 110 of the first to third embodiments include the so-called planetary roller type power transmission mechanisms 4, 6, 8. In the power transmission mechanisms 4, 6, and 8, the roller 45 as the planetary member has a taper surface 411 of the taper sleeve 41 as the sun member in the radial direction with respect to the drive shaft A <b> 1 of the spindle 3 (direction orthogonal to the drive shaft A <b> 1). At least a part is disposed between the tapered surfaces 475, 675, and 875 of the gear sleeves 47, 67, and 87 as ring members. The gear sleeves 47, 67, 87 move in the front-rear direction integrally with the spindle 3 with respect to the taper sleeve 41. On the other hand, the roller 45 is restricted from moving in the front-rear direction with respect to the main body housing 11 by the biasing spring 49 (and the washer 491 or the retainer 83). Accordingly, the roller 45 moves in the front-rear direction in accordance with the relative movement of the gear sleeves 47, 67, 87 and the taper sleeve 41, and frictional contact between the roller 45 and the taper surface 411 and the taper surfaces 475, 675, 875 is not achieved. The possibility of becoming stable can be reduced. In the third embodiment, the movement of the roller 45 in the front-rear direction is restricted not via the washer 491 but via the retainer 83. Thereby, the number of parts can be reduced and assemblability can be improved.

  In the first to third embodiments, the retainers 43 and 83 as carrier members are held by the spindle 3 so as to be movable in the front-rear direction with respect to the spindle 3. In other words, the retainers 43 and 83 are independent from the spindle 3 with respect to the movement in the front-rear direction. The retainers 43 and 83 need to be disposed at positions where the rollers 45 can be held so that the rollers 45 do not come off between the tapered surface 411 and the tapered surfaces 475 675 875. On the other hand, in the above embodiment, the retainers 43 and 83 can be maintained at appropriate positions regardless of the movement of the spindle 3. Thereby, compared with the configuration in which the retainers 43 and 83 move integrally with the spindle 3 in the front-rear direction, it is possible to reduce restrictions on the amount of movement of the spindle 3 in the front-rear direction. In particular, when the roller 45 and the tapered surfaces 411, 475, 675, and 875 are worn, in order to establish stable frictional contact, the taper sleeve 41 and the gear sleeves 47, 67, and 87 are moved closer to each other (that is, It is necessary to push in the spindle 3 (to the rear). That is, it is necessary to increase the amount of movement of the spindle 3 in the front-rear direction. However, according to the power transmission mechanisms 4, 6, and 8 of the above-described embodiment, it is possible to appropriately meet such needs.

  Further, in the first to third embodiments, the retainers 43 and 83 are held so as not to rotate around the drive shaft A1 with respect to the spindle 3 and are integrated with the spindle 3 by the power transmitted via the roller 45. It is comprised so that it may rotate. That is, in the said embodiment, the rational planetary-roller type power transmission mechanism 4,6,8 which uses the retainers 43 and 83 as an output member is implement | achieved.

  In the first to third embodiments, the urging spring 49 restricts the retainers 43 and 83 from moving in the front-rear direction with respect to the main body housing 11 in addition to the roller 45. Thereby, the appropriate positional relationship between the roller 45 and the retainers 43 and 83 can be more reliably maintained. Further, in the above-described embodiment, the biasing spring 49 biases the spindle 3 and the retainers 43 and 83 forward and backward so as to be separated from each other. The spindle 3 is normally held at the foremost position (that is, the initial position) by the biasing force of the biasing spring 49. With such a configuration, when the push-in of the spindle 3 is released while restricting the movement of the retainers 43 and 83, the spindle 3 can be returned to the initial position.

  In the first to third embodiments, the gear sleeves 47, 67, 87 are supported by the spindle 3 so as to be movable in the front-rear direction integrally with the spindle 3 and rotatable about the drive shaft A1. . The biasing spring 49 is disposed between the retainers 43 and 83 and the gear sleeves 47, 67, and 87 (more specifically, the bearing 48 disposed in the gear sleeves 47, 67, and 87) in the front-rear direction. The end portions of the gear sleeves 47, 67, and 87 are received by washers 493 that are blocked from the rotation of the gear sleeves 47, 67, and 87. Therefore, the biasing spring 49 rotates together with the gear sleeves 47, 67, 87 (so-called co-rotation), and the sliding portion between the biasing spring 49 and the gear sleeves 47, 67, 87 generates heat. It becomes possible to prevent.

  In the first to third embodiments, the urging spring 49 urges the gear sleeves 47, 67, 87 and the retainers 43, 83 backward and forward so as to be separated from each other. In other words, the urging spring 49 is configured to interrupt transmission of the gear sleeves 47, 67, 87 as drive side members and the retainers 43, 83 as driven side members in the power transmission mechanisms 4, 6, and 8. It also has the function of energizing. As described above, by using the biasing spring 49, it is possible to realize a plurality of functions of restricting movement of the retainers 43 and 83 in the front-rear direction and blocking power transmission without increasing the number of parts.

  In the third embodiment, the peripheral wall 874 of the gear sleeve 87 is provided with a communication hole 878 that allows communication between the inside and the outside of the gear sleeve 87. For this reason, the flow of air through the communication hole 878 can be generated by the centrifugal force accompanying the rotation of the gear sleeve 87. Thereby, suppression of a local temperature rise and smoother circulation of the lubricant (for example, grease) arranged in the front housing 13 can be realized. As a result, it is possible to effectively reduce wear of the roller 45 and the tapered surfaces 411, 475, 675, and 875 and improve durability. Further, even when wear powder is generated, it can be effectively discharged to the outside of the gear sleeve 87 through the communication hole 878 together with the air flow, which leads to protection of the bearing 48.

  The above embodiment is merely an example, and the work tool according to the present invention is not limited to the configuration of the illustrated screwdrivers 1, 100, and 110. For example, the changes exemplified below can be added. These changes may be made by any one of them or a plurality of them independently or in combination with the screw driver 1, 100, 110 shown in the embodiment or the invention described in each claim. It can be adopted.

  In the above embodiment, the screw drivers 1, 100, and 110 as the screw tightening tools are exemplified, but the present invention is also applicable to other work tools configured to rotationally drive the tip tool. For example, a drilling tool (for example, an electric drill) that performs a drilling operation by rotating a drill bit, or a polishing tool (for example, an electric sander) that performs polishing by rotating an abrasive material (sandpaper or the like). Is also applicable.

  In the power transmission mechanisms 4, 6, and 8 as planetary roller friction clutch mechanisms, the configurations and arrangements of the sun member, ring member, carrier member, and planetary roller may be changed as appropriate. For example, the power transmission mechanisms 4, 6, and 8 do not need to have a so-called solar-type configuration in which the solar member is fixed to the main body housing 11 so as not to rotate as in the above embodiment, and the ring member is fixed. It may have a so-called planetary type or a so-called star type structure in which a carrier member is fixed. Moreover, although the said embodiment is a structural example to which the gear sleeves 47, 67, 87 as a ring member move to the front-back direction with respect to the taper sleeve 41 as a sun member, a sun member and a ring member are drive shafts. Any one of them may move integrally with the spindle 3 as long as it has tapered surfaces parallel to each other inclined with respect to A1 and can move relative to each other in the front-rear direction. One of the sun member and the ring member that moves integrally with the spindle 3 may be integrally formed with the spindle 3 as an output member.

  Further, in the above embodiment, the biasing spring 49 has the function of regulating the longitudinal movement of the retainer 43 as the carrier member, in addition to the function of regulating the movement of the roller 45 as the planetary member in the longitudinal direction. The function of urging toward the initial position and the direction in which power transmission is interrupted between the gear sleeves 47, 67, 87 as drive side members and the retainers 43, 83 as driven side members in the power transmission mechanisms 4, 6, 8 It has a function to energize. That is, the single biasing spring 49 performs a plurality of functions. However, these functions may be realized by separate members (for example, spring members).

  When the communication holes 878 are provided, the number, the arrangement position, the shape, the size, and the like are not limited to those illustrated in the third embodiment, and may be changed as appropriate. For example, at least one communication hole 878 may be provided at any position in the region R1 (see FIG. 23) between the rear end of the peripheral wall 874 and the rear end of the bearing 48. Further, the communication hole 878 may extend obliquely with respect to the radial direction, or may extend in a curved shape instead of a linear shape.

  In addition to the power transmission mechanisms 4, 6, and 8, the configurations of the main body housing 11, the motor 2, the spindle 3, and the position switching mechanisms 5 and 7 can be changed as appropriate. For example, a DC brushless motor using a rechargeable battery as a power source may be employed as the motor 2. The position switching mechanisms 5 and 7 may be omitted.

  Correspondence relations between the constituent elements of the embodiment and the modified example and the constituent elements of the invention are shown below. The screw drivers 1, 100, and 110 are examples of the “work tool” in the present invention. The driver bit 9 is an example of the “tip tool” in the present invention. The main body housing 11 is an example of the “housing” in the present invention. The spindle 3 is an example of the “spindle” in the present invention. The drive shaft A1 is an example of the “drive shaft” in the present invention. The motor 2 is an example of the “motor” in the present invention. The power transmission mechanisms 4, 6, and 8 are examples of the “power transmission mechanism” of the present invention. The taper sleeve 41 is an example of the “solar member” in the present invention. The gear sleeves 47, 67, 87 are examples of the “ring member” of the present invention. The retainers 43 and 83 are an example of the “carrier member” in the present invention. The roller 45 is an example of the “planetary roller” in the present invention. The tapered surface 411 is an example of the “first tapered surface” in the present invention. The tapered surfaces 475, 675, and 875 are examples of the “second tapered surface” in the present invention. The biasing spring 49 is an example of the “regulating member” and “spring member” in the present invention. The washer 493 is an example of the “receiving member” in the present invention. The communication hole 878 is an example of the “communication hole” in the present invention. The region R2 is an example of the “region corresponding to the second tapered surface” in the present invention. The region R3 is an example of the “region different from the region corresponding to the second tapered surface” in the present invention.

Furthermore, in view of the gist of the present invention and the above embodiment, the following configuration (mode) is constructed. Only one or a plurality of the following configurations may be employed in combination with the screwdrivers 1, 100, 110 according to the embodiments and modifications thereof, or the invention described in each claim.
[Aspect 1]
The ring member includes a cylindrical peripheral wall that surrounds the spindle in a circumferential direction around the drive shaft and has an inner peripheral surface including the second tapered surface,
At least a part of the carrier member is disposed in an internal space of the ring member defined by the spindle and the inner peripheral surface,
The spring member may be disposed in the internal space on the front side of the carrier member.
According to this aspect, the spring member can be arranged by effectively utilizing the internal space of the ring member, and the power transmission mechanism can be kept compact.
[Aspect 2]
In aspect 1,
The ring member has a stopper portion disposed on the front side of the spring member,
The spring member may be interposed between the carrier member and the stopper portion in the front-rear direction.
[Aspect 3]
In aspect 2,
The stopper portion may be a bearing having an inner ring rotatably supported by the spindle and an outer ring fixed to the inner peripheral surface.
According to the aspects 2 and 3, the spring member can be rationally interposed between the carrier member and the ring member in the front-rear direction. The bearing 48 is an example of the “stopper portion” and “bearing” in the first and second aspects.
[Aspect 4]
The ring member has a cylindrical peripheral wall portion around the drive shaft,
The communication hole may be a through-hole penetrating the peripheral wall portion.
[Aspect 5]
The inner peripheral surface of the ring member includes the second tapered surface and a cylindrical surface along the drive shaft,
The communication hole may be provided in a region of the ring member corresponding to the cylindrical surface.

DESCRIPTION OF SYMBOLS 1,100: Screw driver 10: Main body part 11: Main body housing 12: Rear part housing 13: Front part housing 135: Stopper part 14: Central housing 141: Partition wall 143: Base 15: Locator 17: Handle part 171: Grasping part 173 : Trigger 174: Main switch 175: Switching lever 176: Rotation direction switch 178: Controller 179: Power supply cable 18: Handle housing 2: Motor 21: Rotor 23: Motor shaft 231: Bearing 233: Bearing 24: Pinion gear 25: Fan 3 : Spindle 301: Bearing 31: Front shaft 311: Bit insertion hole 32: Rear shaft 321: Groove 34: Flange 36: Ball 4, 6: Power transmission mechanism 41: Tapered sleeve 411: Tapered surface 414: Recess 43: Retain 431: Bottom wall 432: Recess 434: Holding arm 45: Roller 47, 67: Gear sleeve 470, 670: Gear teeth 471, 671: Bottom wall 474, 674: Peripheral wall 475, 675: Tapered surface 48: Bearing 481: Outer ring 483 : Inner ring 49: biasing spring 491: washer 493: washer 5, 7: position switching mechanism 50, 70: one-way clutch 500: lead sleeve 501: cam groove 502: ball 504: peripheral wall 505: bottom wall 507, 707: lead groove 508, 708: Ball 53: Thrust bearing 700: Flange sleeve 701: Peripheral wall 703: Flange 9: Driver bit 90: Screw 900: Work piece A1: Drive shaft

Claims (9)

A work tool configured to rotationally drive a tip tool,
A housing;
A front end configured to be movable in the front-rear direction along a predetermined drive shaft extending in the front-rear direction of the work tool and supported by the housing so as to be rotatable around the drive shaft, so that the tip tool can be attached and detached. A spindle having a portion;
A motor housed in the housing;
A solar member, a ring member, and a carrier member that are arranged coaxially with the drive shaft, and a planetary roller that is rotatably held by the carrier member, and a power transmission mechanism housed in the housing,
The sun member and the ring member each have a first tapered surface and a second tapered surface inclined with respect to the drive shaft,
One of the sun member and the ring member is configured to be movable in the front-rear direction integrally with the spindle with respect to the other,
The planetary roller is at least partially disposed between the first tapered surface and the second tapered surface in a radial direction with respect to the drive shaft,
The power transmission mechanism is
The sun member and the ring member move relative to each other in accordance with the backward movement of the spindle, and the planetary roller is brought into frictional contact with the sun member and the ring member. Configured to transmit the power of the motor to the spindle; and
As the spindle moves forward, the sun member and the ring member move relative to each other in a direction away from each other, and the planetary roller is brought into a non-friction contact state with the sun member and the ring member. , Configured to cut off transmission of the power,
The work tool includes a restricting member configured to restrict the planetary roller from moving in the front-rear direction with respect to the housing. The work tool according to claim 1,
The work tool, wherein the carrier member is held by the spindle so as to be movable in the front-rear direction with respect to the spindle. The work tool according to claim 2,
The carrier member is held so as not to rotate around the drive shaft with respect to the spindle, and is configured to rotate integrally with the spindle by the power transmitted via the planetary roller. A work tool characterized by that. The work tool according to any one of claims 1 to 3,
The work tool is configured to restrict the carrier member from moving in the front-rear direction with respect to the housing. The work tool according to claim 4,
The restricting member includes a spring member that urges the spindle and the carrier member forward and backward so as to be separated from each other,
The work tool characterized in that the spindle is always held at the foremost position by the biasing force of the spring member. The work tool according to claim 5,
The ring member is supported by the spindle so as to be movable in the front-rear direction integrally with the spindle and to be rotatable around the drive shaft.
The spring member is interposed between the carrier member and the ring member in the front-rear direction,
The work tool further includes a receiving member that receives one end of the spring member on the ring member side in a state of being blocked from rotation of the ring member. The work tool according to claim 6,
The ring member is configured to be rotated by the power of the motor,
The work tool, wherein the spring member is configured to urge the ring member and the carrier member so as to be separated from each other in the front-rear direction. The work tool according to any one of claims 1 to 7,
The ring tool has at least one communication hole for communicating the inside and the outside of the ring member. The work tool according to claim 8,
The communication hole is formed in a region different from a region corresponding to the second tapered surface in the ring member.

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