JP7136705B2 - Work tools - Google Patents

Description

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

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

JP 2012-135842 A

In the power transmission mechanism described above, when the spindle is moved in the axial direction, the drive gear and planetary roller holding members held by the spindle move toward or away from the fixed hub fixed to the housing. . On the other hand, the planetary rollers are loosely fitted in grooves formed in the holding member. Therefore, there is a possibility that the planetary roller will move in the axial direction and the frictional contact with the tapered surface as the driving surface will become unstable.

In view of such circumstances, the present invention provides a work tool having a planetary roller type power transmission mechanism that transmits power according to the backward movement of the spindle, and establishes stable frictional contact between the planetary roller and the drive surface. The purpose is to provide improvements for

According to one aspect of the invention, a work tool configured to rotationally drive a tool bit 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 around the drive shaft. Also, the spindle has a front end configured to allow attachment and detachment of the tip tool. The motor and power transmission mechanism are housed in the housing. The power transmission mechanism includes a sun member, a ring member, and a carrier member arranged coaxially with the drive shaft, and planetary rollers rotatably held by the carrier member. The sun member and 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 longitudinally relative to the other integrally with the spindle. At least a portion of the planetary roller is disposed between the first tapered surface and the second tapered surface in the radial direction with respect to the drive shaft.

In the power transmission mechanism, the sun member and the ring member move relative to each other in accordance with the rearward movement of the spindle, and the planetary rollers are brought into frictional contact with the sun member and the ring member, thereby causing the spindle to move. It is configured to transmit the power of the motor. Further, the power transmission mechanism relatively moves the sun member and the ring member in a direction away from each other in accordance with the forward movement of the spindle so that the planetary rollers are brought into non-frictional contact with the sun member and the ring member. and is configured to block the transmission of power. Further, the work tool includes a restricting member configured to restrict the planetary roller from moving forward and backward with respect to the housing. It should be noted that the term "restriction of movement" as used herein is not limited to completely prohibiting movement, but includes the case where slight movement is permitted.

The work tool of this aspect includes a so-called planetary roller type power transmission mechanism. In this power transmission mechanism, at least a portion of the planetary roller is arranged between the first tapered surface of the sun member and the second tapered surface of the ring member in the radial direction (direction orthogonal to the drive shaft) of the spindle with respect to the drive shaft. It is One of the sun member and the ring member is movable fore and aft relative to the other together with the spindle. On the other hand, the planetary rollers are restricted from moving in the front-rear direction by the restricting member. Therefore, it is possible to reduce the possibility that the planetary rollers move in the front-rear direction due to the relative movement of the sun member and the ring member, resulting in unstable frictional contact with the first and second tapered surfaces.

In one aspect of the invention, the carrier member may be held by the spindle so as to be movable forward and backward relative to the spindle. In other words, the carrier member may be independent of the spindle with respect to forward and backward movement. The carrier member should be positioned to hold the planetary rollers from dislodging between the first tapered surface of the sun member and the second tapered surface of the ring member. In contrast, according to this aspect, it is possible to maintain the carrier member in an appropriate position regardless of the movement of the spindle. As a result, restrictions on the amount of movement of the spindle in the front-rear direction can be reduced compared to the case where the carrier member moves integrally with the spindle. In particular, as the planetary rollers and the first and second tapered surfaces wear, the spindle must be pushed to a position where the sun and ring members are closer together in order to establish stable frictional contact. In other words, it is necessary to increase the amount of movement of the spindle in the longitudinal direction, but according to this aspect, it is possible to appropriately meet such needs.

In one aspect of the invention, the carrier member may be non-rotatably held relative to the spindle about the drive axis. The carrier member may be configured to rotate integrally with the spindle by power transmitted via planetary rollers. According to this aspect, it is possible to realize a reasonable planetary roller type power transmission mechanism that uses 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 forward and backward 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 restricting member, it is possible to more reliably maintain an appropriate positional relationship between the planetary roller and the carrier member.

In one aspect of the invention, the restricting member may include a spring member that biases the spindle and carrier member away from each other in the front-rear direction. The spindle may be held at the forwardmost position at all times by the biasing force of the spring member. According to this aspect, it is possible to return the spindle to the forwardmost position (that is, the initial position) when the pushing of the spindle is released while the movement of the carrier member is restricted by the biasing force of the spring member.

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 together 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 longitudinal 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 of being 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 from generating heat in the sliding portion between the spring member and the ring member.

In one aspect of the invention, the ring member may be configured to be rotated by power of a motor. The spring member may then be configured to urge the ring member and the carrier member forwardly and rearwardly away 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, the spring member can realize a plurality of functions of restricting the movement of the carrier member in the front-rear direction and interrupting power transmission without increasing the number of parts.

In one aspect of the present invention, the ring member may have at least one communication hole that communicates the inside and the outside of the ring member. According to this aspect, the centrifugal force accompanying the driving of the power transmission mechanism (typically, the rotation of the ring member) can generate air flow through the communication hole. As a result, it is possible to suppress a local temperature rise in the power transmission mechanism and achieve smoother circulation of the lubricant arranged in the housing. As a result, wear of the planetary rollers and the first and second tapered surfaces can be effectively reduced, and durability can be improved.

In one aspect of the present invention, the communication hole may be formed in a region of the ring member that is different from the region corresponding to the second tapered surface. According to this aspect, the communication hole can be easily formed in the ring member.

1 is a side view of a screwdriver according to a first embodiment; FIG. It is a longitudinal cross-sectional view of a screwdriver. FIG. 3 is a partially enlarged view of FIG. 2; 4 is a cross-sectional view taken along line IV-IV of FIG. 3; FIG. 4 is a partially enlarged view of FIG. 3; FIG. FIG. 5 is a partially enlarged view of FIG. 4; 3 is an exploded perspective view of a spindle, a power transmission mechanism, and a position switching mechanism; FIG. FIG. 4 is a cross-sectional view corresponding to the VIII-VIII line in FIG. 3, and is an explanatory diagram showing a non-frictional contact state between the roller and the tapered sleeve and gear sleeve. FIG. 4 is a vertical cross-sectional view of the screwdriver with the spindle moved backward from the initial position and the power transmission mechanism in a state where power can be transmitted; FIG. 10 is an explanatory view corresponding to a cross-sectional view taken along line XX of FIG. 9 and showing a state of frictional contact between the roller and the tapered sleeve and the gear sleeve; FIG. 4 is a cross-sectional view taken along line XI-XI of FIG. 3 and is an explanatory view showing the state of the one-way clutch when the gear sleeve is rotationally driven in the forward direction; FIG. 12 is a cross-sectional view corresponding to FIG. 11 and an explanatory view showing the state of the one-way clutch when the gear sleeve is rotationally driven in the reverse direction; FIG. 5 is a cross-sectional view corresponding to FIG. 4 and an explanatory view showing a state in which the lead sleeve and gear sleeve have been moved rearward; FIG. 4 is a longitudinal sectional view of the screwdriver with the locator in contact with the workpiece and the screw tightening operation completed. It is a longitudinal cross-sectional view of a screwdriver according to a second embodiment. FIG. 16 is a cross-sectional view taken along line XVI-XVI of FIG. 15; 3 is an exploded perspective view of a spindle, a power transmission mechanism, and a position switching mechanism; FIG. FIG. 16 is a cross-sectional view corresponding to FIG. 15 and an explanatory view showing a state in which the gear sleeve has been moved rearward; FIG. 17 is a cross-sectional view corresponding to FIG. 16 and an explanatory view showing a state in which the gear sleeve has been moved rearward; It is a longitudinal cross-sectional view of a screwdriver according to a third embodiment. 21 is a cross-sectional view taken along line XXI-XXI of FIG. 20; FIG. 3 is an exploded perspective view of a spindle, a power transmission mechanism, and a position switching mechanism; FIG. FIG. 22 is a partially enlarged view of FIG. 21;

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[First embodiment]
A screwdriver 1 according to a first embodiment will be described with reference to FIGS. 1 to 14. FIG. The screwdriver 1 is an example of a work tool that rotates a tip tool. More specifically, by rotating a driver bit 9 attached to a spindle 3, it is possible to perform screw tightening and screw loosening operations. It is an example of a screw tightening tool.

First, a schematic configuration of the screwdriver 1 will be described. As shown in FIGS. 1 and 2, the screwdriver 1 includes a main body portion 10 including a motor 2, a spindle 3, etc., and a handle portion 17 including a grip portion 171. As shown in FIGS. The body portion 10 as a whole is formed in an elongated shape extending along a predetermined drive axis A1. A driver bit 9 is detachably attached to one end of the main body 10 in the longitudinal direction (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 longitudinal direction in a loop shape. A portion of the handle portion 17 that is separated from the main body portion 10 and extends linearly in a direction substantially perpendicular to the drive axis A1 constitutes a grip portion 171 that is gripped by the user. One end portion of the grip portion 171 in the longitudinal direction is arranged 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 grip portion 171 .

In the screwdriver 1 of this embodiment, when the user pulls the trigger 173, the motor 2 is driven. Further, 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, a screw tightening operation and a screw loosening operation are performed.

A detailed configuration of the screwdriver 1 will be described below. In the following description, for convenience, the extending direction of the drive shaft A1 is defined as the front-rear direction of the screwdriver 1, the side where the driver bit 9 is attached and detached is the front side, and the side where the grip portion 171 is arranged is the rear side. side and stipulate. Further, the direction perpendicular to the drive axis A1 and corresponding to the extending direction of the grip portion 171 is defined as the vertical direction. side is defined as the bottom side. Further, a direction orthogonal to the front-rear direction and the up-down direction is defined as the left-right direction.

First, the body portion 10 and the handle portion 17 will be briefly described. As shown in FIG. 2 , the outer shell of the body portion 10 is mainly formed by a body housing 11 . The 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 arranged between the rear housing 12 and the front housing 13 . include. The front end portion of the central housing 14 has a partition wall 141 arranged substantially perpendicular to the drive shaft A1. By fixing the central housing 14 and the front housing 13 to the rear housing 12 with screws, 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.

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

As shown in FIG. 2 , the outer shell of the handle portion 17 is mainly formed by the handle housing 18 . The handle housing 18 is composed of left and right halves. The left half-split body is integrally formed with the rear housing 12 . The handle housing 18 houses 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 arranged inside the grip portion 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 response to the 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 wiring (not shown).

The rotation direction of the driver bit 9 (specifically, the rotation direction of the motor shaft 23) is provided in the portion of the handle housing 18 that connects the lower end of the grip portion 171 and the lower rear end of the main body 10 (rear housing 12). ) is provided. By operating the switching lever 175, the user can change the rotation direction of the motor shaft 23 to the direction in which the driver bit 9 tightens the screw 90 (also referred to as the positive direction or the screw tightening direction) or the direction in which the driver bit 9 loosens the screw 90. (also referred to as reverse direction or 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 wiring (not shown).

A controller 178 containing control circuitry is located below the main switch 174 . The controller 178 is configured to drive the motor 2 according to 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.

A detailed configuration including the internal structure of the main body 10 will be described below.

As shown in FIG. 2, the rear housing 12 houses the motor 2 . In this embodiment, an AC motor is used as the motor 2 . A motor shaft 23 extending from the rotor 21 of the motor 2 extends below the drive shaft A1 and parallel to the drive shaft A1 (in the front-rear direction). The motor shaft 23 is rotatably supported by bearings 231 and 233 at its front and rear ends. 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 of the rear housing 12 . 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 housed in the central housing 14 . A front end portion of the motor shaft 23 protrudes 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 . These detailed configurations will be described in order below.

As shown in FIGS. 3 and 4, the spindle 3 is a substantially cylindrical elongated member extending in the front-rear direction along the drive shaft A1. In this embodiment, the spindle 3 is configured by integrally connecting a front shaft 31 and a rear shaft 32 which are separately formed. However, the spindle 3 may also consist of only a single shaft. The spindle 3 has a flange 34 protruding radially outward at a central portion in the front-rear direction (more specifically, the rear end portion of the front shaft 31).

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. , is rotatable about the drive shaft A1 and is supported so as to be movable in the front-rear direction along the drive shaft A1. The spindle 3 is normally urged forward by the urging force of an urging spring 49 to be described later, and is held at a position where the front end surface of the flange 34 contacts a stopper portion 135 provided inside the front housing 13 . ing. The position of the spindle 3 at this time is the forwardmost position (also referred to as the initial position) in the movable range of the spindle 3 . A front end portion of the spindle 3 (front shaft 31 ) protrudes from the front housing 13 into the locator 15 . A bit insertion hole 311 is provided at the front end of the spindle 3 (front shaft 31) along the drive axis A1. A steel ball biased by a leaf spring engages the small diameter portion of the driver bit 9 inserted into the bit insertion hole 311 to retain the driver bit 9 detachably.

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

Moreover, the power transmission mechanism 4 is configured to transmit the power of the motor 2 to the spindle 3 or to block the transmission of the power. Specifically, in the power transmission mechanism 4, as the gear sleeve 47 moves toward or away from the tapered sleeve 41, the retainer 43, and the roller 45 in the front-rear direction, the roller 45 It is configured to be in frictional contact or non-frictional contact with the tapered sleeve 41 and the gear sleeve 47 . Thereby, 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 the present embodiment is configured as a planetary roller type friction clutch mechanism.

The detailed configuration and arrangement of each member of the power transmission mechanism 4 will be described below.

First, the tapered sleeve 41 will be described. As shown in FIGS. 5 to 7, the tapered sleeve 41 corresponding to the sun member is configured as a tubular member. The tapered sleeve 41 is fixed to the body housing 11 (specifically, the partition wall 141) through the base 143 so as not to rotate about 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 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 loosely inserted into the tapered sleeve 41 and is movable in the longitudinal direction and rotatable with respect to the tapered sleeve 41 .

The outer peripheral surface of the tapered sleeve 41 is configured as a tapered surface 411 that is inclined at a predetermined angle with respect to the drive shaft A1. More specifically, the outer shape of the tapered sleeve 41 is a truncated cone that tapers forward (the diameter decreases), and the tapered surface 411 is a conical surface that slopes forward in a direction approaching the drive shaft A1. is configured as In this 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 in the cross section of the cone).

Next, the retainer 43 will be explained. A retainer 43 as a carrier member is a member that rotatably holds rollers 45 as a planetary member. As shown in FIGS. 5 to 7, the retainer 43 has a substantially circular bottom wall 431 with through holes and a plurality of holding arms 434 protruding from the outer edge of the bottom wall 431 . The retaining arms 434 are circumferentially spaced apart from each other. Although the retainer 43 has ten holding arms 434 in this embodiment, the number of holding arms 434 (and the number of rollers 45) can be changed as appropriate. The retainer 43 is positioned with the bottom wall 431 facing forward (so that the retaining arms 434 protrude rearward), and with the retaining arms 434 partially overlapped with the tapered sleeves 41 in the radial direction. is supported by the spindle 3 so as to be non-rotatable and 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 axis 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 rotatably arranged in each groove 321 . A pair of recesses 432 are formed on the rear surface of the bottom wall 431 of the retainer 43 (the surface on the side of the holding arm 434) with the drive shaft A1 interposed therebetween. A portion of ball 36 located within groove 321 engages recess 432 . Further, an annular concave portion 414 is formed in the central portion of the front end face of the tapered sleeve 41 . Although details will be described later, the retainer 43 is biased rearward by a biasing spring 49 , the balls 36 are arranged in the spaces defined by the recesses 414 and 432 , and the rear surface of the bottom wall 431 faces the tapered sleeve 41 . It is held in contact with the front end face. The rear end of the holding arm 434 is arranged at a position spaced forward from the base 143 .

With such a configuration, the retainer 43 is engaged with the spindle 3 via the balls 36 in the radial direction and the circumferential direction of the spindle 3 and is rotatable integrally with the spindle 3 . The ball 36 can roll in the annular recess 414 of the tapered sleeve 41, and the retainer 43 can rotate with respect to the tapered sleeve 41 together with the spindle 3 around the drive axis A1. 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 balls 36 can roll within the grooves 321 .

As shown in FIGS. 5 to 7, the roller 45 corresponding to the planetary member is a cylindrical member. In this embodiment, each roller 45 has a constant diameter and is held between adjacent holding arms 434 so as to rotate around a rotation axis generally parallel to the tapered surface 411 . Note that the length of the roller 45 is set longer than that of the holding arm 434 . Further, as shown in FIG. 8 , when 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 explained. As shown in FIGS. 5 to 7, the gear sleeve 47, which corresponds to a ring member, is configured as a substantially cup-shaped member having an inner diameter larger than the outer diameters of the tapered sleeve 41 and the retainer 43. As shown in FIGS.

The gear sleeve 47 has a bottom wall 471 with 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 near the bottom wall 471 . The gear sleeve 47 is oriented so that the bottom wall 471 is located on the front side (so as to open rearward), is on the front side of the retainer 43, and is attached to the spindle 3 so as to be rotatable and movable in the front-rear direction with respect to the spindle 3. Supported. More specifically, the rear shaft 32 of the spindle 3 is loosely inserted through the through hole of the bottom wall 471 and is inserted through the inner ring 483 of the bearing 48 so as to be slidable in the front-rear direction. Thereby, a cylindrical internal space is formed between the spindle 3 and the peripheral wall 474 on the rear side of the bearing 48 . In this internal space, the tapered sleeve 41, the retainer 43, part of the roller 45, and an urging spring 49, which will be described later, are arranged. Gear teeth 470 are integrally formed on the outer periphery of the gear sleeve 47 (specifically, the peripheral wall 474) to constantly mesh with the pinion gear 24, and the gear sleeve 47 is rotationally driven as the motor shaft 23 rotates. be done.

Of the peripheral wall 474 of the gear sleeve 47, the inner peripheral surface of the portion behind the bearing 48 (portion on the open end side) 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 tapered surface 411). That is, the tapered surface 475 is formed as a conical surface that is inclined rearward (open end of the gear sleeve 47) in a direction away from the drive shaft A1. At least a portion (specifically, a front portion) of the roller 45 held by the retainer 43 is located between the tapered surface 411 and the tapered surface 475 in the radial direction of the spindle 3 (direction orthogonal to the drive axis A1). It is held like this.

Further, in this embodiment, the power transmission mechanism 4 includes a biasing spring 49 interposed between the gear sleeve 47 and the retainer 43 and rollers 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 on the rear side and the end on the small diameter side is on the front side. More specifically, the large-diameter end abuts the large-diameter washer 491 , and the small-diameter end abuts the small-diameter washer 493 . The washer 491 is arranged to contact the front end surface of the holding arm 434 of the retainer 43 . The washer 493 is positioned so as to contact the inner ring 483 of the bearing 48 mounted within the gear sleeve 47 but not the outer ring 481 . That is, the biasing spring 49 is rotatable with the retainer 43 but blocked from rotation of the gear sleeve 47 .

The biasing spring 49 always biases the retainer 43 and the gear sleeve 47 away from each other, that is, rearward and forward, respectively, via washers 491 and 493 . As a result, the retainer 43 is held at a position where the rear surface of the bottom wall 431 contacts the front end surface of the tapered sleeve 41 by the biasing force of the biasing spring 49, and its longitudinal movement 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 longitudinal movement is restricted. Note that "movement is restricted" as used herein does not mean that movement is completely prohibited, and slight movement may be permitted. 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 for this play is Allowed. The biasing spring 49 may directly contact the retainer 43 and the inner ring 483 without the washers 491 and 493 interposed therebetween.

Further, the gear sleeve 47 is urged forward by the urging force of the urging spring 49, so that 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. It is held at the initial position in contact with the stopper portion 135 .

5 and 8, 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 when the spindle 3 is arranged at the initial position. (more specifically, spaced apart from tapered surface 475 ) and is in non-frictional contact with tapered sleeve 41 and gear sleeve 47 . That is, the power transmission mechanism 4 is in the disconnected state. On the other hand, as shown in FIG. 9, the gear sleeve 47 moves rearward with respect to the main body housing 11 (approaching the tapered sleeve 41, the retainer 43 and the rollers 45), and the tapered surface 411 of the tapered sleeve 41 and the gear sleeve 47 move toward each other. When the distance to tapered surface 475 is narrowed, roller 45 is sandwiched between tapered surface 411 and tapered surface 475 and brought into frictional contact with tapered sleeve 41 and gear sleeve 47, as shown in FIG. As a result, the power transmission mechanism 4 shifts to the transmission enabled state. The operation of the power transmission mechanism 4 will be detailed later.

The position switching mechanism 5 will be described below. The position switching mechanism 5 is a mechanism that relatively moves the gear sleeve 47 and the front end portion of the spindle 3 in the front-rear direction away from each other when the gear sleeve 47 is rotationally driven in the opposite direction (screw loosening direction). is. With this configuration, the position switching mechanism 5 moves the gear sleeve 47 rearward with respect to the spindle 3 when the gear sleeve 47 is rotationally driven in the opposite direction (screw loosening direction) with the spindle 3 arranged at the initial position. It is moved so that it approaches the retainer 43 and the rollers 45 . Details of the position switching mechanism 5 will be described below.

As shown in FIGS. 5 to 7, in this embodiment, the position switching mechanism 5 is mainly composed of a one-way clutch 50, a lead sleeve 500 having lead grooves 507, and balls 508. FIG.

In this embodiment, the one-way clutch 50 includes a cam groove 501 formed in the front end of the gear sleeve 47 and balls 502, and the lead sleeve 500 is engaged only when the gear sleeve 47 is driven to rotate in the opposite 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 radially inward of the gear sleeve 47 from the outer peripheral surface of the peripheral wall 474 at the front end of the gear sleeve 47 and extends radially from the outer peripheral surface. The depth 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 the figure (the reverse direction (screw loosening direction) of the gear sleeve 47 indicated by arrow B in the figure. ), the size increases from the upstream side to the downstream side). In this embodiment, four cam grooves 501 are provided at regular intervals in the circumferential direction around the drive shaft A1. A steel ball 502 is arranged in each cam groove 501 . As shown in FIG. 11, the diameter of the ball 502 is set slightly larger than the depth of the deepest portion of the cam groove 501 (that is, the upstream end in the positive direction).

As shown in FIGS. 5 to 7, the lead sleeve 500 is formed as a substantially tube-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 disposed between the gear sleeve 47 and the flange 34 of the spindle 3 in a state in which the bottom wall 505 is disposed on the front side and the rear shaft 32 of the spindle 3 is loosely inserted through the through hole of the bottom wall 505 . are placed in Between the rear surface of the bottom wall 505 and the front end surface of the bottom wall 471 of the gear sleeve 47, there is provided a thrust bearing (more specifically, a thrust ball bearing) that receives a thrust load while allowing rotation of the lead sleeve 500 with respect to the gear sleeve 47. 53 are arranged. Note that the rear surface of the bottom wall 505 and the front end surface of the bottom wall 471 are each formed with an annular concave portion having a U-shaped cross section. Balls as rolling elements of the thrust bearing 53 can roll within the annular raceways defined by these recesses.

The inner diameter of the peripheral wall 504 is set slightly larger than the outer diameter of the front end of the gear sleeve 47 in which the cam groove 501 is formed, and the peripheral wall 504 is arranged to surround the outer peripheral surface of the front end of the gear sleeve 47. It is As shown in FIG. 11, at the deepest part 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. It is

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 rotationally driven in the reverse direction. Specifically, as shown in FIG. 11, when the gear sleeve 47 is rotationally driven in the positive direction (the direction of arrow A in the figure), the ball 502 moves toward the deepest portion of the cam groove 501 (the direction of the arrow A). relative to the upstream end of the ). The ball 502 rotates about the drive shaft A1 together with the gear sleeve 47 while being loosely 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 the disengaged 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 opposite direction (the direction of arrow B in the figure), the ball 502 moves from the deepest part of the cam groove 501 to a shallower portion (in the opposite direction (the direction of arrow B)). direction)). 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 due to the frictional force due to the wedging action. That is, the one-way clutch 50 shifts to a transmission-enabled state, and the lead sleeve 500 rotates in the opposite direction together with the gear sleeve 47 .

The lead groove 507 and the balls 508 move the lead sleeve 500 relative to the spindle 3 in the front-rear direction as the lead sleeve 500 rotates about the drive axis A1. It is configured to move relative to the roller 45 in the front-rear direction. As shown in FIGS. 5 to 7, in this embodiment, the lead groove 507 is a spiral groove (strictly speaking, it corresponds to a part of the spiral) formed in the front end surface of the bottom wall 505 of the lead sleeve 500. Three grooves are provided at equal intervals in the circumferential direction while being spaced apart from each other. More specifically, the depth of the lead groove 507 in the front-rear direction from the front end surface decreases from upstream to downstream in the positive direction (screw tightening direction) of the gear sleeve 47 indicated by arrow A in FIG. (increase from the upstream side to the downstream side in the opposite direction (screw loosening direction) of the gear sleeve 47 indicated by arrow B in FIG. 7). A steel ball 508 is placed in each lead groove 507 .

As described above, the gear sleeve 47 is always urged forward by the urging spring 49 disposed between the retainer 43 and the gear sleeve 47 (specifically, the bearing 48). 5 and 6, the thrust bearing 53, the lead sleeve 500, and the ball 508 are also urged forward, and the ball 508 contacts the rear surface of the flange 34. As shown in FIGS. The spindle 3 is also urged forward via the flange 34 and normally held in the initial position.

With this 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 arranged in the deepest part (that is, the upstream end in the positive direction) of the lead groove 507, the flange 34 and the lead sleeve 500 are aligned in the front-rear direction. distance is minimal. That is, the lead sleeve 500 is arranged at the forwardmost position within the movable range with respect to the spindle 3 . When the spindle 3 is arranged at the initial position, the gear sleeve 47 is arranged at the farthest position away from the retainer 43 and the rollers 45 in the front-rear direction.

On the other hand, when the one-way clutch 50 operates as described above and the lead sleeve 500 rotates together with the gear sleeve 47 in the opposite direction, the balls 508 move from the deepest part of the lead groove 507 to the shallowest part (in the opposite direction). 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 biasing force in accordance with the relative movement of the ball 508, as shown in FIG. Move (backwards relative to spindle 3). This causes the lead sleeve 500 to move the gear sleeve 47 backward with respect to the spindle 3 against the biasing force of the biasing spring 49 , that is, in a direction closer to the retainer 43 and the rollers 45 . When the ball 508 is arranged at the shallowest position, the distance between the flange 34 and the lead sleeve 500 in the fore-and-aft direction is maximized. With the spindle 3 in the initial position, the gear sleeve 47 is in an intermediate position closer to the retainer 43 and rollers 45 than in the farthest position. That is, the relative positions of the gear sleeve 47, retainer 43, and roller 45 are switched from the farthest position to the intermediate position.

The operation 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 below.

First, in an initial state in which the motor 2 is not driven and no external force directed backward is acting on the spindle 3 , the spindle 3 is arranged at the initial position by the biasing force of the biasing spring 49 . As described above, at this time, roller 45 is in non-frictional contact with tapered sleeve 41 and gear sleeve 47, as shown in FIGS. That is, the power transmission mechanism 4 is in the disconnected state.

When the positive direction (screw tightening direction) is set as the rotation direction of the motor shaft 23 via the switching lever 175, the screwdriver 1 operates as follows to accomplish the screw tightening work.

When the user pulls the trigger 173 to turn on the main switch 174 while the spindle 3 is in the initial position, the controller 178 starts driving the motor 2 . As indicated by arrow A in FIG. 11, the gear sleeve 47 is rotationally driven in the positive direction (screw tightening direction). As described above, the one-way clutch 50 does not operate at this time, so the rotational force of the gear sleeve 47 is not transmitted to the lead sleeve 500 . Therefore, the gear sleeve 47, retainer 43, and roller 45 are maintained at the farthest positions. In addition, since the power transmission mechanism 4 is in the blocked state, the rotational force of the gear sleeve 47 is not transmitted to the spindle 3 either, and the gear sleeve 47 idles forward.

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 arranged at an intermediate position). state), the screw loosening operation, which will be described later, may end. In this case, the clamping of the ball 502 is released in response to the forward rotation of the gear sleeve 47, and the action of the biasing force of the biasing spring 49, the lead groove 507 and the ball 508 moves the lead sleeve 500 to the forwardmost position. return. As a result, the gear sleeve 47, the retainer 43, and the roller 45 are returned from the intermediate position to the farthest position.

When the user moves the screwdriver 1 forward (toward the workpiece 900) while the gear sleeve 47 is idling, and presses the screw 90 engaged with the driver bit 9 against the workpiece 900, the spindle 3 It is pushed rearward relative to the body housing 11 against the biasing force of the biasing spring 49 . Pushed by flange 34 , ball 508 , lead sleeve 500 , thrust bearing 53 and gear sleeve 47 also move rearward relative to main body housing 11 together with spindle 3 . On the other hand, the tapered sleeve 41 is fixed to the body housing 11 , and the retainer 43 and the rollers 45 are held in a state where movement in the front-rear direction with respect to the body housing 11 is restricted. Therefore, the gear sleeve 47 approaches the tapered sleeve 41, the retainer 43, and the roller 45 as it moves rearward, and the radial distance between the tapered surface 411 of the tapered sleeve 41 and the tapered surface 475 of the gear sleeve 47 gradually increases. 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 frictional contact (the roller 45 and the tapered surface 411 are in contact with each other). , 475 due to the wedge action). That is, the gear sleeve 47 , the retainer 43 , and the rollers 45 are arranged at a transmission position where the torque from the gear sleeve 47 to the retainer 43 can be transmitted via the rollers 45 . The roller 45 rotates and revolves on the tapered surface 411 of the tapered sleeve 41 in response to the rotation of the gear sleeve 47, and rotates 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 A<b>1 , the spindle 3 rotates together with the retainer 43 . In this way, as the spindle 3 moves backward from the initial position, the power transmission mechanism 4 shifts from the cut-off state to the transmission enabled state, and tightening of the screw 90 to the workpiece 900 is started. The spindle 3 rotates in the same direction as the gear sleeve 47 at a speed lower than the rotation speed of the gear sleeve 47 .

As the tightening of the screw 90 to the workpiece 900 progresses and the tip of the locator 15 comes into contact with the workpiece 900 as shown in FIG. As a result, the pressing force against the spindle 3 gradually decreases. Therefore, the force of sandwiching the roller 45 by the tapered surface 411 of the tapered sleeve 41 and the tapered surface 475 of the gear sleeve 47 (corresponding to the sum of the pressing force of the spindle 3 and the force of the biasing spring 49 biasing the spindle 3 forward) ), and thus the rotational force transmitted from the gear sleeve 47 to the spindle 3 gradually decreases. Then, when the rotational force transmitted from the gear sleeve 47 to the spindle 3 falls below the rotational force required for tightening the screw 90, the screw 90 stops rotating and the screw tightening operation ends.

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

When the user pulls the trigger 173 to turn on the main switch 174 while the spindle 3 is in the initial position, the controller 178 starts driving the motor 2 . As indicated by arrow B in FIG. 12, the gear sleeve 47 is rotationally driven in the opposite direction (screw loosening direction). As a result, the one-way clutch 50 operates as described above to rotate the lead sleeve 500 in the opposite direction, and as shown in FIG. is moved rearwardly relative to the spindle 3 in a direction toward the retainer 43 and the rollers 45 against the biasing force of . In other words, in the screw loosening operation, regardless of whether or not the spindle 3 is moved backward (while the spindle 3 is in the initial position), the gear sleeve 47 is rotated in the opposite direction. 47, retainer 43 and roller 45 are switched from the farthest position to the intermediate position.

As shown in FIG. 13, even when the gear sleeve 47, the retainer 43, and the roller 45 are arranged at the intermediate position, the roller 45 is separated from the tapered surface 475 as in the case of being arranged at the farthest position. and is in non-frictional contact with tapered sleeve 41 and gear sleeve 47 . Therefore, the rotational force of gear sleeve 47 is not transmitted to spindle 3 . That is, the power transmission mechanism 4 is in the disconnected state, and the gear sleeve 47 idles in the opposite direction.

In the idling state of the gear sleeve 47, when the user moves the screwdriver 1 forward to press and engage the screwdriver bit 9 against the screw 90 tightened in the workpiece 900, the spindle 3 is pushed by the biasing spring. It is pushed rearward relative to the body housing 11 against the biasing force of 49 . The gear sleeve 47 is adjacent to the tapered sleeve 41, retainer 43 and roller 45, and the gear sleeve 47, retainer 43 and roller 45 are arranged in the transmission position. The roller 45 is sandwiched between the tapered surface 411 and the tapered surface 475 to be in frictional contact, the power transmission mechanism 4 shifts from the cutoff state to the transmission enabled state, the screw 90 is loosened, and the workpiece 900 is removed. be.

As described above, during the screw loosening operation, the gear sleeve 47 is moved rearward with respect to the spindle 3 by the position switching mechanism 5 than during the screw tightening operation, and the distance between the gear sleeve 47 and the retainer 43 and the rollers 45 in the longitudinal direction is adjusted. is made smaller. Therefore, the distance that the gear sleeve 47, the retainer 43, and the roller 45 move from the intermediate position to the transmission position in the longitudinal direction of the spindle 3 (in other words, when the power transmission mechanism 4 is loosened, the power transmission mechanism 4 moves from the cut-off state to the transmission enabled state). ) is the movement distance of the gear sleeve 47, the retainer 43 and the roller 45 from the farthest position to the transmission position (the power transmission mechanism 4 during the screw tightening operation). The amount of movement or pushing of the spindle 3 from the blocked state to the transmissible state). In this embodiment, the movement distance during screw loosening is set to be approximately 1 mm shorter than the movement distance of the spindle 3 during screw tightening. This allows the user to loosen the screw 90 tightened into the workpiece 900 without removing the locator 15 from the front housing 13 .

In the above description, the operation when the spindle 3 is pushed backward after the start of driving the motor 2 has been exemplified. The operation when the driving of the motor 2 is started is basically the same. In the case of screw loosening work, depending on the position of the spindle 3, the position switching mechanism 5 moves the gear sleeve 47 rearward in response to the start of driving the motor 2, thereby shifting the power transmission mechanism 4 to the transmission state. sometimes. Further, when the spindle 3 is pushed backward and the driving of the motor 2 is started after the power transmission mechanism 4 is shifted to the transmission-enabled state, the rotational driving of the spindle 3 is started in response to the start of the driving of the motor 2. will be

[Second embodiment]
A screwdriver 100 according to a second embodiment will be described below with reference to FIGS. 15 to 19. FIG. The screwdriver 100 of the present embodiment includes a power transmission mechanism 6 and a position switching mechanism 7 that are different from the power transmission mechanism 4 and the position switching mechanism 5 (see FIGS. 5 to 7) of the first embodiment. , and other configurations are substantially the same as those of the screwdriver 1 . Therefore, in the following description, substantially the same configurations as those of the first embodiment are denoted by the same reference numerals, descriptions thereof are omitted or simplified, and different configurations are mainly described.

As shown in FIGS. 15 to 17, the power transmission mechanism 6 of this embodiment is a planetary mechanism including a tapered sleeve 41, a retainer 43, a plurality of rollers 45, and a gear sleeve 67 arranged coaxially. It is composed as the 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 tapered sleeve 41 and the retainer 43, and is identical to the gear sleeve 47 of the first embodiment except for the configuration of the front end. It has a similar 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 with respect to the spindle 3 on the front side of the retainer 43. Moreover, it is supported by the spindle 3 so as to be movable in the front-rear direction. In the internal space of the gear sleeve 67, the tapered sleeve 41, the retainer 43, part of the rollers 45, and the urging spring 49 are arranged. In addition, gear teeth 670 that always mesh with the pinion gear 24 are integrally formed on the outer circumference 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 a tapered surface 675 that is inclined at the same angle as the tapered surface 411 of the tapered sleeve 41 with respect to the drive axis 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 this 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 grooves 707 are formed as spiral grooves (strictly speaking, grooves having a shape corresponding to a part of the spiral), and are spaced from each other and provided at equal intervals in the circumferential direction. The depth of the lead groove 707 in the front-rear direction from the front end face decreases from upstream to downstream in the positive direction (screw tightening direction) of the gear sleeve 67 indicated by arrow A in FIG. In the opposite direction (screw loosening direction) of the gear sleeve 67 indicated by the arrow B, it increases from the upstream side to the downstream side).

Similarly to the position switching mechanism 5 of the first embodiment, the position switching mechanism 7 of the present embodiment also rotates the gear sleeve 67 and the front end of the spindle 3 when the gear sleeve 67 is rotationally driven in the opposite direction (screw loosening direction). are relatively moved away from each other in the longitudinal direction. With this configuration, the position switching mechanism 7 moves the gear sleeve 67 rearward with respect to the spindle 3 when the gear sleeve 67 is rotationally driven in the opposite direction (screw loosening direction) with the spindle 3 arranged at the initial position. It is moved so that it approaches the retainer 43 and the rollers 45 .

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

In this embodiment, a well-known general-purpose one-way clutch is employed as the one-way clutch 70 . The one-way clutch 70 has a cylindrical shape and is 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 has a cylindrical peripheral wall 701 and a flange 703 projecting radially outward from the front end of the peripheral wall 701 . An annular recess is formed in the outer edge of the rear surface of the flange 703 with which the ball 708 abuts. A peripheral wall 701 is fixed to the outer periphery of the one-way clutch 70 . 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 in the longitudinal direction, a thrust bearing (more specifically, a thrust ball bearing) 53 are arranged. Note that the rear surface of the flange 34 and the front surface of the flange 703 are each formed with an annular concave portion having a U-shaped cross section. Balls as rolling elements of the thrust bearing 53 can roll within the annular raceways defined by these recesses.

The lead groove 707 and the balls 708 move the gear sleeve 67 relative to the spindle 3 in the longitudinal direction as the gear sleeve 67 rotates about 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 rollers 45 in the front-rear direction. As described above, the lead groove 707 is formed in the front end surface of the bottom wall 671 of the gear sleeve 67 in this embodiment. A steel ball 708 is placed in each lead groove 707 .

Further, as described above, the gear sleeve 67 is always urged forward by the urging 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 via the ball 708, the flange sleeve 700 and the thrust bearing 53, and is normally held at the initial position.

With this 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 arranged in the deepest part (that is, the upstream end in the positive direction) of the lead groove 707, the flange 703 and the gear in the front-to-rear direction The sleeve 67 distance is minimized. That is, the gear sleeve 67 is arranged at the forwardmost position within the movable range with respect to the spindle 3 . When the spindle 3 is arranged at the initial position, the gear sleeve 67 is arranged at the farthest position away from the retainer 43 and the rollers 45 in the front-rear direction.

At this time, the urging force of the urging spring 49 pushes the ball 708 arranged in the lead groove 707 into engagement with the annular recess formed in the outer edge of the rear surface of the flange 703 . As described above, the one-way clutch 70 and the flanged sleeve 700 are rotatable in the positive direction with respect to the spindle 3 . Therefore, when the gear sleeve 67 is driven to rotate in the positive direction, the frictional force between the flange 703 and the ball 708 held at the deepest part of the lead groove 707 causes the flange sleeve 700 to rotate in the positive direction together with the gear sleeve 67. be 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 together with the gear sleeve 67 .

On the other hand, as described above, the one-way clutch 70 cannot rotate in the reverse direction with respect to the spindle 3. Therefore, when the gear sleeve 67 is rotated in the reverse direction, the one-way clutch 70 causes the flange sleeve 700 to rotate toward the spindle 3. Rotation in the opposite direction is prohibited. That is, the flange sleeve 700 is integrated with the spindle 3 . Therefore, the gear sleeve 67 rotates in the opposite direction relative to the flange sleeve 700 . Accordingly, the ball 708 relatively moves from the deepest portion of the lead groove 707 to the shallowest portion (upstream in the opposite direction). Since the ball 708 abuts the rear surface of the flange 703, the gear sleeve 67 rotates in the opposite direction in response to the relative movement of the ball 708, as shown in FIGS. It moves away from the flange 703 (rearward with respect to the spindle 3 ) against the biasing force of 49 , that is, toward the retainer 43 and rollers 45 . When the ball 708 is arranged at the shallowest position, the distance between the flange 703 and the gear sleeve 67 in the fore-and-aft direction is maximized. With the spindle 3 in the initial position, the gear sleeve 67 is in an intermediate position closer to the retainer 43 and rollers 45 than in the farthest position. That is, the relative positions of the gear sleeve 67, retainer 43, and roller 45 are switched from the farthest position to the intermediate position.

[Third embodiment]
A screwdriver 110 according to the third embodiment will be described below with reference to FIGS. 20 to 23. FIG. The screwdriver 110 of this embodiment includes a power transmission mechanism 8 different from the screwdriver 100 of the second embodiment (see FIGS. 15 to 17). 100 and substantially the same. Therefore, hereinafter, substantially the same configurations as those of the screwdriver 100 are denoted by the same reference numerals, descriptions thereof are omitted or simplified, and different configurations are mainly described.

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 arranged coaxially. Constructed 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. 15-17).

The retainer 83 of this embodiment, like the retainer 43 of the second embodiment (see FIGS. 15 to 17), corresponds to a carrier member in the planetary mechanism, and is configured to hold the roller 45 rotatably. 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 protruding 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 retaining arms 834 projecting rearwardly from the rear face of the part. Bottom wall 831 and holding arm 834 have substantially the same configuration as bottom wall 431 and holding arm 434 of retainer 43 . With such a configuration, the front end of the holding space for the rollers 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 the rearward biasing force 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 forward movement of the roller 45 .

Like the retainer 43, the retainer 83 is oriented so that the bottom wall 831 is located on the front side (so that the retaining arms 834 protrude rearward), and in a state in which the retaining arms 834 partially overlap the tapered sleeves 41 in the radial direction. , is supported by the spindle 3 so as to be non-rotatable with respect to the spindle 3 and to be movable in the longitudinal direction. Each holding arm 834 protrudes rearward from the rear surface of the peripheral 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 this 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 with a through hole in the center and a cylindrical peripheral wall 874 connected to the bottom wall 871 . Note that 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 it has a communication hole 878 which will be described later. Specifically, the outer ring 481 of the bearing 48 is fixed within the front end of the peripheral wall 874 . In addition, gear teeth 870 that always mesh with the pinion gear 24 are integrally formed on the outer circumference of the gear sleeve 87 (specifically, the peripheral wall 874).

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

The communication hole 878 is a through hole penetrating the peripheral wall 874 in the radial direction, and communicates between 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, in a region R3 corresponding to the cylindrical surface 876. FIG. In other words, the communication hole 878 is arranged in a region that does not normally overlap the roller 45 in the radial direction. Moreover, in this embodiment, the four communication holes 878 are provided at regular intervals in the circumferential direction.

As shown in FIGS. 21 and 22, also in this embodiment, the gear sleeve 87 is on the front side of the retainer 83 and is supported by the spindle 3 so as to be rotatable with respect to the spindle 3 and to be movable in the longitudinal direction. there is Further, in the internal space of the gear sleeve 87, the tapered sleeve 41, the retainer 83, part of the rollers 45, and the urging spring 49 are arranged.

In this embodiment, the small-diameter end (front end) of the biasing spring 49 contacts the washer 493 that contacts the inner ring 483 of the bearing 48, while the large-diameter end (rear end) contacts the retainer. It abuts on the front surface of the flange portion 832 of 83 . The biasing spring 49 always biases the retainer 83 and the gear sleeve 87 away from each other, ie rearward and forward, respectively. As a result, the retainer 83 is held at a position where the rear surface of the bottom wall 831 abuts the front end surface of the tapered sleeve 41 by the biasing force of the biasing spring 49, and its longitudinal movement is restricted. Further, 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 its longitudinal movement is restricted. As described in the first embodiment, "movement is restricted" does not mean that movement is completely prohibited, and slight movement may be permitted. Further, the gear sleeve 87 is urged forward by the urging force of the urging spring 49, so that 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 urging force of the urging spring 49 places the spindle 3 at the initial position, and the roller 45 is in non-frictional contact with the tapered surface 411 of the tapered sleeve 41 and the tapered surface 875 of the gear sleeve 87 . in a state. That is, the power transmission mechanism 8 is in the disconnected state. After that, as the spindle 3 is pushed backward against the biasing force of the biasing spring 49 , the gear sleeve 87 approaches the tapered sleeve 41 , the retainer 83 and the rollers 45 . Then, the roller 45 held by the retainer 83 is sandwiched between the tapered surface 411 and the tapered surface 875 to be in frictional contact. As a result, the power transmission mechanism 8 shifts from the cut-off state to the transmission enabled state.

As described above, the screwdrivers 1, 100, 110 of the first to third embodiments are equipped with 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 is aligned with the tapered surface 411 of the tapered sleeve 41 as the sun member in the radial direction with respect to the drive axis A1 of the spindle 3 (direction orthogonal to the drive axis A1). , at least partially between the tapered surfaces 475, 675, 875 of the gear sleeves 47, 67, 87 as ring members. The gear sleeves 47 , 67 , 87 move forward and backward integrally with the spindle 3 with respect to the tapered sleeve 41 . On the other hand, the roller 45 is restricted from moving forward and backward with respect to the body housing 11 by the biasing spring 49 (and the washer 491 or the retainer 83). Therefore, the roller 45 moves in the front-rear direction as the gear sleeves 47, 67, 87 and the tapered sleeve 41 move relative to each other, and the frictional contact between the roller 45 and the tapered surface 411 and the tapered surfaces 475, 675, 875 becomes impossible. The probability of becoming stable can be reduced. Note that, in the third embodiment, movement of the roller 45 in the front-rear direction is regulated via the retainer 83 instead of the washer 491 . As a result, the number of parts can be reduced and the ease of assembly can be improved.

Further, 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, 83 are independent of the spindle 3 with respect to forward and backward movement. The retainers 43 and 83 need to be arranged at positions capable of holding the rollers 45 so as not to come off between the tapered surface 411 and the tapered surfaces 475 , 675 and 875 . In contrast, in the above-described embodiment, the retainers 43 and 83 can be maintained at appropriate positions regardless of the movement of the spindle 3 . As a result, compared to a configuration in which the retainers 43 and 83 move integrally with the spindle 3 in the front-rear direction, restrictions on the amount of movement of the spindle 3 in the front-rear direction can be reduced. In particular, as roller 45 and tapered surfaces 411, 475, 675, 875 wear, it is necessary to move tapered sleeve 41 and gear sleeves 47, 67, 87 closer together (i.e., to establish stable frictional contact). further backwards) the spindle 3 has to be pushed in. In other words, it is necessary to increase the amount of movement of the spindle 3 in the front-rear direction, but the power transmission mechanisms 4, 6, and 8 of the above embodiments can appropriately meet such needs.

Furthermore, in the first to third embodiments, the retainers 43 and 83 are held so as not to rotate about the drive shaft A1 with respect to the spindle 3, and are integrated with the spindle 3 by power transmitted through the rollers 45. is configured to rotate to That is, in the above-described embodiments, rational planetary roller type power transmission mechanisms 4, 6, 8 using the retainers 43, 83 as output members are realized.

In addition, in the first to third embodiments, the biasing spring 49 also restricts the retainers 43 and 83 from moving forward and backward with respect to the body housing 11 in addition to the roller 45 . Thereby, the appropriate positional relationship between the rollers 45 and the retainers 43, 83 can be maintained more reliably. Further, in the above embodiment, the biasing spring 49 biases the spindle 3 and the retainers 43, 83 forward and rearward away from each other. The spindle 3 is normally held at the forwardmost position (that is, the initial position) by the biasing force of the biasing spring 49 . With such a configuration, the movement of the retainers 43 and 83 can be restricted, and the spindle 3 can be returned to the initial position when the pushing of the spindle 3 is released.

Further, 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 longitudinal direction together with the spindle 3 and to be rotatable around the drive shaft A1. . The biasing spring 49 is arranged in the longitudinal direction between the retainers 43, 83 and the gear sleeves 47, 67, 87 (more specifically, the bearings 48 arranged in the gear sleeves 47, 67, 87). , the ends of the gear sleeves 47, 67, 87 are received by washers 493 blocked from rotation of the gear sleeves 47, 67, 87. Therefore, it is possible to prevent the urging spring 49 from rotating together with the gear sleeves 47, 67, 87 (so-called co-rotation), and the sliding portions of the urging spring 49 and the gear sleeves 47, 67, 87 from generating heat. preventable.

Further, in the first to third embodiments, the bias spring 49 biases the gear sleeves 47, 67, 87 and the retainers 43, 83 rearward and forward away from each other. In other words, the biasing spring 49 moves the gear sleeves 47, 67, 87 as driving side members in the power transmission mechanisms 4, 6, 8 and the retainers 43, 83 as driven side members in the direction of blocking transmission. It also has an energizing function. By using the biasing spring 49 in this way, it is possible to realize a plurality of functions of restricting the movement of the retainers 43 and 83 in the longitudinal direction and interrupting power transmission without increasing the number of parts.

Further, in the third embodiment, the peripheral wall 874 of the gear sleeve 87 is provided with a communication hole 878 that communicates between the inside and the outside of the gear sleeve 87 . Therefore, the centrifugal force accompanying the rotation of the gear sleeve 87 can generate air flow through the communication hole 878 . As a result, it is possible to suppress a local temperature rise and achieve smoother circulation of the lubricant (for example, grease) disposed in the front housing 13 . As a result, wear of the roller 45 and the tapered surfaces 411, 475, 675, 875 can be effectively reduced, and durability can be improved. Moreover, even if abrasion powder is generated, it can be effectively discharged to the outside of the gear sleeve 87 through the communication hole 878 along with the air flow, which leads to protection of the bearing 48 as well.

The above embodiments are merely examples, and the work tool according to the present invention is not limited to the configuration of the screwdrivers 1, 100, 110 illustrated. For example, the modifications exemplified below can be made. It should be noted that any one of these modifications, or a plurality thereof, may be used independently or in combination with the screwdrivers 1, 100, and 110 shown in the embodiments, or the inventions described in each claim. can be adopted.

In the above embodiments, the screwdrivers 1, 100, 110 are used as screw tightening tools, but the present invention is also applicable to other work tools configured to rotate a tip tool. For example, drilling tools (e.g., electric drills) that perform drilling work by rotating a drill bit, and abrasive tools (e.g., electric sanders) that perform sanding work by rotating an abrasive material (sandpaper, etc.). is also applicable.

In the power transmission mechanisms 4, 6, 8 as planetary roller friction clutch mechanisms, the configuration and arrangement of the sun member, the ring member, the carrier member, and the planetary rollers 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 sun member is non-rotatably fixed to the main body housing 11 as in the above embodiment, and the ring member is fixed. It may also have a so-called planetary configuration with a fixed carrier member or a so-called star configuration with a fixed carrier member. In the above embodiment, the gear sleeves 47, 67 and 87 as ring members move in the longitudinal direction with respect to the tapered sleeve 41 as the sun member. Either of them may move integrally with the spindle 3 as long as it has parallel tapered surfaces that are inclined with respect to A1 and is relatively movable in the front-rear direction. Also, one of the sun member and the ring member that moves integrally with the spindle 3 may be formed integrally with the spindle 3 as an output member.

In the above-described 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 longitudinal movement of the roller 45 as the planetary member. The function of biasing toward the initial position and the direction of blocking the power transmission of the gear sleeves 47, 67, 87 as driving side members and the retainers 43, 83 as driven side members in the power transmission mechanisms 4, 6, 8. It has a function of urging to That is, the single biasing spring 49 exhibits multiple functions. However, these functions may be realized by separate members (for example, spring members).

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

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

Correspondence between each component of the above embodiment and modifications and each component of the present invention is shown below. The screwdrivers 1, 100, 110 are examples of the "working tool" of the present invention. The driver bit 9 is an example of the "tip tool" of the present invention. The body housing 11 is an example of the "housing" of the present invention. The spindle 3 is an example of the "spindle" of the present invention. The drive shaft A1 is an example of the "drive shaft" of the present invention. The motor 2 is an example of the "motor" of the present invention. The power transmission mechanisms 4, 6 and 8 are examples of the "power transmission mechanism" of the present invention. The tapered sleeve 41 is an example of the "sun member" of the present invention. Gear sleeves 47, 67, 87 are examples of "ring members" of the present invention. The retainers 43, 83 are examples of the "carrier member" of the present invention. Roller 45 is an example of the "planetary roller" of the present invention. The tapered surface 411 is an example of the "first tapered surface" of the present invention. The tapered surfaces 475, 675, 875 are examples of the "second tapered surface" of the present invention. The urging spring 49 is an example of the "limiting member" and the "spring member" of the present invention. The washer 493 is an example of the "receiving member" of the present invention. The communication hole 878 is an example of the "communication hole" of 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 "a 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-described embodiments, the following configurations (modes) are constructed. Only one or more of the following configurations can be employed in combination with the screwdrivers 1, 100, 110 of the embodiments and modifications thereof, or the inventions described in each claim.
[Aspect 1]
The ring member has a cylindrical peripheral wall surrounding the spindle in the circumferential direction around the drive shaft and having an inner peripheral surface including the second tapered surface,
at least a portion of the carrier member is disposed in an inner space of the ring member defined by the spindle and the inner peripheral surface;
The spring member may be arranged in the interior 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 arranged in front of the spring member,
The spring member may be interposed between the carrier member and the stopper portion in the longitudinal 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 aspects 2 and 3, the spring member can be reasonably interposed between the carrier member and the ring member in the front-rear direction. Note that the bearing 48 is an example of the "stopper" and the "bearing" in aspects 1 and 2.
[Aspect 4]
The ring member has a cylindrical peripheral wall portion centered on the drive shaft,
The communication hole may be a through hole penetrating through 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.

1, 100: Screwdriver 10: Body 11: Body housing 12: Rear housing 13: Front housing 135: Stopper 14: Central housing 141: Partition wall 143: Base 15: Locator 17: Handle 171: Grip 173 : Trigger 174: Main switch 175: Switching lever 176: Rotation direction switch 178: Controller 179: Power 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 : Balls 4, 6 : Power transmission mechanism 41 : Tapered sleeve 411 : Tapered surface 414 : Recess 43 : Retainer 431 : Bottom wall 432: Recess 434: Holding arm 45: Rollers 47, 67: Gear sleeves 470, 670: Gear teeth 471, 671: Bottom walls 474, 674: Peripheral walls 475, 675: Tapered surface 48: Bearing 481: Outer ring 483: Inner ring 49: bias 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: workpiece A1: drive shaft

Claims (9)

A work tool configured to rotationally drive a tip tool,
a housing;
A front end that 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 around the drive shaft, and is detachably attached to the tip tool. a spindle having a portion;
a motor housed in the housing;
a power transmission mechanism housed in the housing, comprising a sun member, a ring member, and a carrier member arranged coaxially with the drive shaft; and planetary rollers rotatably held by the carrier member;
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 longitudinal direction integrally with the spindle with respect to the other;
At least part of the planetary roller is arranged 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
As the spindle moves rearward, the sun member and the ring member relatively move toward each other, and the planetary rollers are brought into frictional contact with the sun member and the ring member. configured to transmit power of the motor to a spindle; and
As the spindle moves forward, the sun member and the ring member move away from each other, and the planetary rollers are brought into non-frictional contact with the sun member and the ring member. , configured to block transmission of the power,
The work tool includes a restricting member configured to restrict movement of the planetary roller in the longitudinal direction with respect to the housing ,
A work tool , wherein the carrier member is held by the spindle so as to be movable in the longitudinal direction with respect to the spindle . A work tool according to claim 1 ,
The carrier member is held so as not to rotate about the drive shaft with respect to the spindle, and is configured to rotate integrally with the spindle by the power transmitted through the planetary rollers. A work tool characterized by: The work tool according to claim 1 or 2 ,
The work tool, wherein the restricting member is configured to restrict the movement of the carrier member in the longitudinal direction with respect to the housing. A work tool according to claim 3 ,
the regulating member includes a spring member that biases the spindle and the carrier member forward and backward, respectively, away from each other;
A work tool, wherein the spindle is normally held at the forwardmost position by the biasing force of the spring member. A work tool configured to rotationally drive a tip tool,
a housing;
A front end that 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 around the drive shaft, and is detachably attached to the tip tool. a spindle having a portion;
a motor housed in the housing;
a power transmission mechanism housed in the housing, comprising a sun member, a ring member, and a carrier member arranged coaxially with the drive shaft; and planetary rollers rotatably held by the carrier member;
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 longitudinal direction integrally with the spindle with respect to the other;
At least part of the planetary roller is arranged 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
As the spindle moves rearward, the sun member and the ring member relatively move toward each other, and the planetary rollers are brought into frictional contact with the sun member and the ring member. configured to transmit power of the motor to a spindle; and
As the spindle moves forward, the sun member and the ring member move away from each other, and the planetary rollers are brought into non-frictional contact with the sun member and the ring member. , configured to block transmission of the power,
The work tool includes a restricting member configured to restrict movement of the planetary rollers and the carrier member in the longitudinal direction with respect to the housing,
the regulating member includes a spring member that biases the spindle and the carrier member forward and backward, respectively, away from each other;
A work tool, wherein the spindle is normally held at the forwardmost position by the biasing force of the spring member. The work tool according to claim 4 or 5 ,
The ring member is supported by the spindle so as to be movable in the longitudinal 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 comprises 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. A 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 bias the ring member and the carrier member away from each other in the front-rear direction. The work tool according to any one of claims 1 to 7,
A work tool, wherein the ring member has at least one communication hole that communicates the inside and the outside of the ring member. A work tool according to claim 8,
A work tool, wherein the communication hole is formed in a region of the ring member that is different from a region corresponding to the second tapered surface.

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