JP7231329B2 - screw tightening tool - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a screw tightening tool configured to rotationally drive a tip tool.

2. Description of the Related Art There is known a screw tightening 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. there is The screw tightening tool can perform screw tightening or screw loosening by rotating the tip tool in the forward or reverse direction. The pressure can be small. Therefore, Patent Literature 1 discloses a screwdriver that is configured to start power transmission from the drive gear to the spindle when the screw is loosened and the spindle is pushed in by a smaller amount than when the screw is tightened.

JP 2016-168662 A

In the screwdriver disclosed in Patent Literature 1, when the spindle is pushed to a predetermined position, the roller is sandwiched between the driving gear and the spring receiving member, and the spindle can be driven to rotate in the opposite direction. On the other hand, when the spindle is pushed further rearward than the predetermined position, the roller is sandwiched between the drive gear and the lock sleeve so that the spindle can be rotationally driven in the forward direction. In other words, in this screwdriver, power is transmitted through different paths during screw tightening and screw loosening operations, so the configuration of the power transmission mechanism is complicated.

SUMMARY OF THE INVENTION An object of the present invention is to provide a screw tightening tool having a power transmission mechanism with a more rational configuration.

According to one aspect of the invention, a screw tightening tool is provided that includes a spindle, a motor, and a power transmission mechanism.

The spindle is movably supported in the front-rear direction along a predetermined drive shaft extending in the front-rear direction of the screw tightening 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 power transmission mechanism includes a driving member and a driven member. The driving member is configured to be rotationally driven in the first direction or the second direction by power transmitted from the motor. The first direction corresponds to the direction in which the tip tool tightens the screw. The second direction is the opposite direction to the first direction and corresponds to the direction in which the tool bit loosens the screw. The driven member is configured to rotate integrally with the spindle about the drive shaft by power transmitted from the driving member rotating in the first direction or the second direction.

The driving member and the driven member are arranged so as to be relatively movable in the front-rear direction. Further, the driving member and the driven member move toward each other in the front-rear direction in accordance with the rearward movement of the spindle, and the power transmission from the driving member to the driven member is switched from the blocked state in which power transmission from the driving member to the driven member is impossible. It is configured to transition to a transmittable state in which power can be transmitted to. Furthermore, the screw tightening tool has a position switching mechanism. The position switching mechanism rotates one of the driving member and the driven member relative to the other of the driving member and the driven member in the front-rear direction when the driving member is rotationally driven in the second direction with the spindle in the forwardmost position. It is configured to be moved in the approaching direction.

In the power transmission mechanism of the screw tightening tool of this aspect, the drive member is rotationally driven in the first direction corresponding to the screw tightening work, or rotationally driven in the second direction corresponding to the screw loosening work. Also in, the rotational force is transmitted from the driving member to the driven member. In other words, power is transmitted through the same route during screw tightening and screw loosening. When the drive member is rotationally driven in the second direction in response to the screw loosening operation while the spindle is in the forwardmost position, the position switching mechanism switches one of the drive member and the driven member in the front-rear direction to The other of the drive member and the driven member is moved in a direction approaching the other. That is, during the screw loosening operation, even if the spindle is not pushed backward, the distance between the drive member and the driven member in the front-rear direction is shortened according to the rotational drive of the drive member in the second direction. As a result, the rearward movement amount (pushing amount) of the spindle required to shift the power transmission mechanism to the transmission-enabled state can be made smaller than that during the screw tightening operation. Thus, according to this aspect, power can be transmitted through the same path during screw tightening and screw loosening, and the screw loosening operation can be performed with a smaller pushing amount than during screw tightening. A power transmission mechanism can be realized.

In one aspect of the present invention, the position switching mechanism converts rotary motion about the drive shaft into linear motion in the front-rear direction in response to rotational driving of the drive member in the second direction, thereby You may be comprised so that one may be moved. That is, the position switching mechanism can be configured as a motion conversion mechanism. According to this aspect, it is possible to move one of the driving member and the driven member with a simple configuration.

In one aspect of the present invention, the position switching mechanism moves one of the driving member and the driven member by the action of the lead groove extending spirally around the drive shaft and the ball arranged in the lead groove. may be configured. According to this aspect, it is possible to realize a position switching mechanism that operates smoothly with a rolling ball.

In one aspect of the invention, the position switching mechanism may include a moving member and a one-way clutch. The moving member may be configured to rotate around the drive shaft to move the driving member in the front-rear direction in a direction closer to the driven member. The one-way clutch may be configured to rotate the moving member about the drive shaft integrally with the drive member only when the drive member is rotationally driven in the second direction. According to this aspect, it is possible to realize a rational configuration in which the moving member is rapidly rotated and the driving member is moved in response to the rotational driving of the driving member in the second direction.

In one aspect of the invention, the position switching mechanism may include a rotatable member rotatably arranged around the drive shaft and a one-way clutch. The one-way clutch allows the rotatable member to rotate integrally with the drive member about the drive axis relative to the spindle when the drive member is rotatably driven in the first direction, while the drive member rotates in the first direction. The rotatable member may be configured to inhibit rotation relative to the spindle about the drive axis when driven to rotate in two directions. The position switching mechanism moves the driving member, which rotates in the second direction relative to the rotatable member prohibited from rotating relative to the spindle by the one-way clutch, toward the driven member. may be configured. According to this aspect, it is possible to realize a rational configuration in which the driving member is rapidly linearly moved in the front-rear direction in response to the rotational driving of the driving member in the second direction.

In one aspect of the present invention, the power transmission mechanism may be configured as a friction clutch mechanism. According to this aspect, it is possible to reduce abnormal noise and wear of the engaging portion when the driving member and the driven member are engaged, as compared with a meshing engagement type clutch mechanism.

In one aspect of the present invention, the power transmission mechanism may be configured as a planetary speed reduction mechanism. According to this aspect, it is possible to realize both functions of transmission and transmission cutoff of power and speed reduction with a single power transmission mechanism.

In one aspect of the invention, the drive member may have second gear teeth that mesh with first gear teeth provided on the output shaft of the motor. According to this aspect, it is possible to realize a rational configuration for efficiently transmitting the power from the motor to the power transmission mechanism.

According to one aspect of the invention, a screw tightening tool is provided that includes a spindle, a motor, and a power transmission mechanism.

The spindle is movably supported in the front-rear direction along a predetermined drive shaft extending in the front-rear direction of the screw tightening 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 power transmission mechanism includes a driving member and a driven member. The driving member is configured to be rotationally driven in the first direction or the second direction by power transmitted from the motor. The first direction corresponds to the direction in which the tip tool tightens the screw. The second direction is the opposite direction to the first direction and corresponds to the direction in which the tool bit loosens the screw. The driven member is configured to rotate integrally with the spindle about the drive shaft by power transmitted from the driving member rotating in the first direction or the second direction.

The driving member and the driven member are arranged so as to be relatively movable in the front-rear direction. Further, the driving member and the driven member move toward each other in the front-rear direction in accordance with the rearward movement of the spindle, and the power transmission from the driving member to the driven member is switched from the blocked state in which power transmission from the driving member to the driven member is impossible. It is configured to transition to a transmittable state in which power can be transmitted to. Further, in the power transmission mechanism, the driving member is rotationally driven in the second direction more than the amount of rearward movement of the spindle from the cut-off state to the transmissible state when the driving member is rotationally driven in the first direction. It is configured such that the amount of movement in the case of being closed is smaller.

In the power transmission mechanism of the screw tightening tool of this aspect, the drive member is rotationally driven in the first direction corresponding to the screw tightening work, or rotationally driven in the second direction corresponding to the screw loosening work. Also in, the rotational force is transmitted from the driving member to the driven member. In other words, power is transmitted through the same route during screw tightening and screw loosening. In addition, the power transmission mechanism is configured such that the rearward movement amount (pushing amount) of the spindle required to shift the power transmission mechanism to the transmission enabled state is smaller during screw loosening than during screw tightening. there is Thus, according to this aspect, power can be transmitted through the same path during screw tightening and screw loosening, and the screw loosening operation can be performed with a smaller pushing amount than during screw tightening. A power transmission mechanism can be realized.

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;

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 shaft 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 493 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 493 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 loosening operation. 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

As described above, in the power transmission mechanism 4 of the screwdriver 1 of the present embodiment, when the gear sleeve 47 is rotationally driven in the forward direction corresponding to the screw tightening work, it rotates in the reverse direction corresponding to the screw loosening work. In either case, rotational force is transmitted from the gear sleeve 47 to the retainer 43 via the rollers 45 . In other words, power is transmitted through the same route during screw tightening and screw loosening. When the gear sleeve 47 is driven to rotate in the opposite direction while the spindle 3 is in the initial position, the position switching mechanism 5 moves the gear sleeve 47 relative to the retainer 43 and the roller 45 in response to the screw loosening operation. to move closer (backward). That is, during the screw loosening operation, even if the spindle 3 is not pushed backward, the gear sleeve 47 and the retainer 43, and the gear sleeve 47 and the roller 45 move in the front-rear direction according to the rotational driving of the gear sleeve 47 in the opposite direction. distance is shortened. As a result, the rearward movement amount (pushing amount) of the spindle 3 required to shift the power transmission mechanism 4 to the transmission enabled state can be made smaller than that during the screw tightening operation. Thus, according to the present embodiment, power can be transmitted through the same path during screw tightening and screw loosening, and the screw can be loosened with a smaller pushing amount than during screw tightening. power transmission mechanism 4 is realized.

Further, in the present embodiment, the position switching mechanism 5 converts the rotational motion around the drive shaft A1 into linear motion in the front-rear direction in response to the rotational driving of the gear sleeve 47 in the opposite direction, thereby rotating the gear sleeve 47 to the spindle position. 3 is configured to move backwards. That is, the position switching mechanism 5 is configured as a motion conversion mechanism. In particular, in this embodiment, the spiral lead groove 507 formed in the lead sleeve 500 and the ball 508 rolling in the lead groove 507 move the lead sleeve 500 to move the gear sleeve 47 relative to the spindle 3 . A configuration is adopted in which it is moved rearward. This realizes the position switching mechanism 5 that operates smoothly.

Furthermore, in the present embodiment, the position switching mechanism 5 causes the one-way clutch 50 to rotate the lead sleeve 500 integrally with the gear sleeve 47 around the drive shaft A1 only when the gear sleeve 47 is rotated in the opposite direction. This causes the lead sleeve 500 to move rearward with respect to the spindle 3, thereby causing the gear sleeve 47 to move rearward. Thus, in this embodiment, a rational configuration is realized in which the lead sleeve 500 is quickly rotated and the gear sleeve 47 is moved in response to the rotation of the gear sleeve 47 in the opposite direction.

In this embodiment, the power transmission mechanism 4 is configured as a friction clutch mechanism (more specifically, a planetary roller friction clutch mechanism). Therefore, compared with the case where a meshing engagement type clutch mechanism is adopted, abnormal noise when the gear sleeve 47 and the roller 45 are engaged (at the time of frictional contact) and wear of the roller 45 and the tapered surfaces 411 and 475 can be reduced. can be done. Furthermore, since the power transmission mechanism 4 is configured as a planetary speed reduction mechanism, a single mechanism realizes both power transmission and transmission cutoff and speed reduction functions. The gear sleeve 47 also has gear teeth 470 that mesh with the pinion gear 24 provided on the motor shaft 23 . This realizes a rational configuration for efficiently transmitting the power from the motor 2 to the power transmission mechanism 4 .

[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.

As described above, in the screwdriver 100 of the present embodiment as well, when the gear sleeve 67 is driven to rotate in the opposite direction with the spindle 3 in the initial position in response to the screw loosening operation, the position switching mechanism 7 moves the gear sleeve 67 closer (rearward) to the retainer 43 and rollers 45 . That is, during the screw loosening operation, even if the spindle 3 is not pushed backward, the gear sleeve 67 and the retainer 43, and the gear sleeve 67 and the roller 45 move forward and backward in accordance with the rotation of the gear sleeve 67 in the opposite direction. distance is shortened. As a result, the rearward movement amount (pushing amount) of the spindle 3 required to shift the power transmission mechanism 6 to the transmission enabled state can be made smaller than that during the screw tightening operation.

Also in the present embodiment, the position switching mechanism 7 converts the rotational motion around the drive shaft A1 into the linear motion in the front-rear direction in response to the rotational driving of the gear sleeve 67 in the opposite direction, thereby rotating the gear sleeve 67 to the spindle position. It is configured as a motion conversion mechanism that moves backward with respect to 3 . In particular, in this embodiment, the spiral lead groove 707 formed in the gear sleeve 67 and the action of the ball 708 rolling in the lead groove 707 move the gear sleeve 67 backward with respect to the spindle 3. is adopted. This realizes the position switching mechanism 7 that operates smoothly. Furthermore, in the present embodiment, when the gear sleeve 67 is rotationally driven in the reverse direction, the one-way clutch 70 prohibits the reverse rotation of the flange sleeve 700 relative to the spindle 3 (flange sleeve 700). Integrating the sleeve 700 with the spindle 3 ) causes the gear sleeve 67 to rotate relative to the flanged sleeve 700 , thereby moving the gear sleeve 67 rearwardly with respect to the spindle 3 . Thus, in this embodiment, a rational configuration is realized in which the gear sleeve 67 is rapidly moved in the front-rear direction in response to the rotational driving of the gear sleeve 67 in the opposite direction.

The above embodiment is merely an example, and the screw tightening tool according to the present invention is not limited to the configuration of the screwdrivers 1 and 100 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 adopted independently or in combination with the screwdrivers 1 and 100 shown in the embodiments, or the inventions described in each claim. sell.

For example, as the power transmission mechanisms 4 and 6, instead of planetary roller type friction clutch mechanisms, mesh type clutch mechanisms or other types of friction clutch mechanisms may be employed. For example, a single disc or multiple disc clutch mechanism or a cone clutch mechanism may be employed.

In the power transmission mechanisms 4 and 6 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 and 6 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 have a so-called planetary configuration or a so-called star configuration with a fixed carrier member.

A driving member (input member) that is driven by the power of the motor 2 and a driven member (output member) that rotates integrally with the spindle 3 by power transmitted from the driving member according to changes in the power transmission mechanisms 4 and 6. can also be changed. Further, when the gear sleeve 47 is driven to rotate in the opposite direction with the spindle 3 in the initial position, the position switching mechanisms 5 and 7 move one of the driving member and the driven member closer to the other in the longitudinal direction. Either member may be moved with respect to the spindle 3 as long as it can be moved in the direction of movement.

Further, the configuration for converting the rotational motion into linear motion in response to the reverse rotational motion of the driving member (the gear sleeves 47 and 67 in the above embodiment) is the lead grooves 507 and 707 and the balls 508 and 708 in the above embodiment. Not limited. For example, a configuration in which the drive member is moved by the action of a lead surface configured as a spiral curved surface around the drive shaft A1, a screw groove, and a screw thread that is screwed into the screw groove may be employed. For example, in the first embodiment, at least one of the front end surface of the lead sleeve 500 and the rear end surface of the flange 34 of the spindle 3 may be provided with a spiral curved lead surface around the drive shaft A1. Similar modifications are possible in the second embodiment. The number and configuration of lead grooves 507, 707 and balls 508, 708 may be changed as appropriate. Further, in the one-way clutch 50 of the first embodiment, the lead sleeve 500 and the gear sleeve 47 may be rotated integrally only when the gear sleeve 47 is driven to rotate in the opposite direction. you can Similarly, the one-way clutch 70 of the second embodiment only needs to prohibit the flange sleeve 700 from rotating together with the gear sleeve 67 only when the gear sleeve 67 is driven to rotate in the opposite direction, and its configuration can be changed as appropriate. may be

Correspondence between each component of the above embodiment and modifications and each component of the present invention is shown below. Each of the screwdrivers 1 and 100 is an example of the "screw tightening tool" 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. Each of the power transmission mechanisms 4 and 6 is an example of the "power transmission mechanism" of the present invention. Each of gear sleeves 47, 67 is an example of a "drive member" of the present invention. The retainer 43 and the rollers 45 as a whole are an example of the "driven member" of the present invention, and each of the retainer 43 and the rollers 45 is also an example of the "driven member" of the present invention. Each of the position switching mechanisms 5 and 7 is an example of the "position switching mechanism" of the present invention. Each of the lead grooves 507 and 707 is an example of the "lead groove" of the present invention, and each of the balls 508 and 708 is an example of the "ball" of the present invention. Lead sleeve 500 and one-way clutch 50 are examples of the "moving member" and "one-way clutch" of the present invention, respectively. Flanged sleeve 700 and one-way clutch 70 are examples of the "rotatable member" and "one-way clutch" of the present invention, respectively. Pinion gear 24 and gear teeth 470 are examples of "first gear teeth" and "second gear teeth", respectively.

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 screwdriver 1 of the embodiment, its modifications, or the inventions described in each claim.
[Aspect 1]
the spindle has a protrusion that protrudes radially with respect to the drive shaft;
The position switching mechanism includes a moving member supported by the spindle on the rear side of the projecting portion and on the front side of the driving member so as to be rotatable about the driving shaft and movable in the front-rear direction,
The screw tightening tool further comprises a biasing member that biases the moving member and the spindle forward via the driving member,
The moving member rotates in response to rotational driving of the driving member in the second direction, and moves backward with respect to the spindle against the biasing force of the biasing member, thereby moving the driving member. It may be moved backwards relative to the spindle.
According to this aspect, it is possible to realize a position switching mechanism with a simple configuration using the moving member and the biasing member. In addition, the flange 34 is an example of the "projection" in this aspect. The lead sleeve 500 is an example of the "moving member" in this aspect. The biasing spring 49 is an example of the "biasing member" in this aspect.
[Aspect 2]
In aspect 1,
The position switching mechanism is
a lead groove formed in the front end surface of the moving member and spirally extending around the drive shaft;
a ball arranged in the lead groove;
The moving member may be configured to rotate in response to rotational driving of the driving member in the second direction, and move backward with respect to the spindle by the action of the lead groove and the ball.
[Aspect 3]
In aspect 1 or 2,
The position switching mechanism includes a one-way clutch configured to rotate the moving member about the drive shaft integrally with the drive member only when the drive member is rotationally driven in the second direction. It's okay.
[Aspect 4]
said rotatable member having a protrusion projecting radially with respect to said drive shaft and located forward of said drive member;
the screw tightening tool further comprising a biasing member that biases the rotatable member and the spindle forward via the drive member;
The drive member may be configured to move rearwardly relative to the rotatable member against the biasing force of the biasing member while rotating in the second direction.
According to this aspect, it is possible to realize a position switching mechanism with a simple configuration using the rotatable member and the biasing member. In addition, the flange 34 is an example of the "projection" in this aspect. The lead sleeve 500 is an example of the "moving member" in this aspect. The biasing spring 49 is an example of the "biasing member" in this aspect.
[Aspect 5]
In aspect 4,
The position switching mechanism is
a lead groove formed in the front end surface of the drive member and spirally extending around the drive shaft;
a ball arranged in the lead groove while being in contact with the rear surface of the protrusion;
The driving member may be configured to move backward with respect to the spindle by the action of the lead groove and the ball while rotating in the second direction.

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 (5)

A screw tightening tool,
It is movable in the front-rear direction along a predetermined drive shaft extending in the front-rear direction of the screw tightening tool, is rotatably supported around the drive shaft, and has a front end configured to allow attachment and detachment of a tip tool. a spindle;
a motor;
By the power transmitted from the motor, a first direction corresponding to the direction in which the tip tool tightens the screw, or a direction opposite to the first direction and corresponding to the direction in which the tip tool loosens the screw. It is configured to rotate around the drive shaft integrally with the spindle by the power transmitted from the drive member that is rotationally driven in two directions and the drive member that rotates in the first direction or the second direction. and a power transmission mechanism including a driven member,
The driving member and the driven member are arranged so as to be relatively movable in the front-rear direction. configured to transition from a blocked state in which power transmission to a member is impossible to a transmission enabled state in which power transmission from the drive member to the driven member is possible;
When the drive member is driven to rotate in the second direction while the spindle is in the forwardmost position, the screw tightening tool rotates around the drive shaft in response to the drive member to rotate in the second direction. a position switching mechanism configured to move the driving member in a direction approaching the driven member in the front-rear direction by converting the rotary motion of to the linear motion in the front-rear direction prepared,
The power transmission mechanism is configured as a friction clutch mechanism,
The position switching mechanism is
a moving member configured to move the driving member in the front-rear direction in a direction closer to the driven member by rotating around the driving shaft;
and a one-way clutch configured to rotate the moving member about the drive shaft integrally with the drive member only when the drive member is rotationally driven in the second direction. screw tightening tool. A screw tightening tool,
It is movable in the front-rear direction along a predetermined drive shaft extending in the front-rear direction of the screw tightening tool, is rotatably supported around the drive shaft, and has a front end configured to allow attachment and detachment of a tip tool. a spindle;
a motor;
By the power transmitted from the motor, a first direction corresponding to the direction in which the tip tool tightens the screw, or a direction opposite to the first direction and corresponding to the direction in which the tip tool loosens the screw. It is configured to rotate around the drive shaft integrally with the spindle by the power transmitted from the drive member that is rotationally driven in two directions and the drive member that rotates in the first direction or the second direction. and a power transmission mechanism including a driven member,
The driving member and the driven member are arranged so as to be relatively movable in the front-rear direction. configured to transition from a blocked state in which power transmission to a member is impossible to a transmission enabled state in which power transmission from the drive member to the driven member is possible;
When the drive member is driven to rotate in the second direction while the spindle is in the forwardmost position, the screw tightening tool rotates around the drive shaft in response to the drive member to rotate in the second direction. a position switching mechanism configured to move the driving member in a direction approaching the driven member in the front-rear direction by converting the rotary motion of to the linear motion in the front-rear direction;
The power transmission mechanism is configured as a friction clutch mechanism,
The position switching mechanism is
a rotatable member rotatably disposed about the drive shaft;
When the drive member is rotationally driven in the first direction, the rotatable member is united with the drive member to rotate about the drive axis relative to the spindle; a one-way clutch configured to inhibit rotation of the rotatable member relative to the spindle about the drive shaft when the member is driven to rotate in the second direction;
The position switching mechanism moves the driving member, which rotates in the second direction relative to the rotatable member prohibited from rotating relative to the spindle by the one-way clutch, in a direction approaching the driven member. A screw tightening tool configured to be moved to the The screw tightening tool according to claim 1 or 2,
The position switching mechanism is configured to move the drive member by the action of a lead groove extending spirally around the drive shaft and a ball arranged in the lead groove. screw tightening tool. The screw tightening tool according to any one of claims 1 to 3 ,
The screw tightening tool, wherein the power transmission mechanism is configured as a planetary speed reduction mechanism. The screw tightening tool according to any one of claims 1 to 4 ,
A screw tightening tool, wherein the drive member has second gear teeth that mesh with first gear teeth provided on the output shaft of the motor.

Images