CN111757793A - Working tool - Google Patents

Abstract

In a power tool having a planetary roller power transmission mechanism that performs power transmission in response to rearward movement of a main spindle, an improvement is provided for establishing stable frictional contact of a planetary roller with a driving surface. A power transmission mechanism (4) of an electric screwdriver (1) comprises a taper sleeve (41), a gear sleeve (47), a retainer (43) and a roller (45). The taper sleeve (41) and the gear sleeve (47) have taper surfaces (411, 475), respectively. The gear sleeve (47) is movable in the forward and backward directions relative to the tapered sleeve (41) integrally with the main shaft (3). At least a part of the roller (45) is disposed between the tapered surfaces (411, 475) in the radial direction with respect to the drive shaft (A1). The electric screwdriver (1) is provided with an urging spring (49), and the urging spring (49) limits the roller (45) to move in the front-back direction relative to the main body shell (11).

Description

Working tool

Technical Field

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

Background

A power transmission mechanism (clutch) is known which is configured to rotationally drive a tool bit attached to a distal end portion of a spindle and to transmit power of a motor to the spindle in response to press-fitting of the spindle. For example, japanese patent laid-open publication No. 2012-135842 discloses a planetary power transmission mechanism having a fixed hub, a drive gear, a planetary roller (planetary roller), and a holding member for the planetary roller. The fixed hub has a tapered surface (tapered surface) on the outer periphery and is fixed to the housing. The cup-shaped drive gear has a tapered surface on an inner periphery and is rotatably held to the main shaft. The planetary rollers are disposed between the stationary hub and the tapered surface of the drive gear. The holding member of the planetary roller is fixed to the main shaft. The drive gear is rotated by power of the motor, and when the main shaft is pushed rearward, the planetary rollers revolve around the main shaft while rotating in frictional contact with the fixed hub and the tapered surfaces of the drive gear. Accordingly, the holding member of the planetary roller rotates around the shaft integrally with the main shaft.

Disclosure of Invention

In the above power transmission mechanism, when the main shaft moves in the axial direction, the drive gear held by the main shaft and the holding member of the planetary roller move in a direction approaching or separating from the fixed hub fixed to the housing. On the other hand, the planetary rollers are disposed in a groove formed in the holding member in a clearance fit manner. Therefore, the planetary roller may move in the axial direction and may be unstable in frictional contact with the tapered surface as the drive surface.

In view of the above, it is an object of the present invention to provide an improvement for establishing a stable frictional contact between a planetary roller and a driving surface in a power tool having a planetary roller type power transmission mechanism that transmits power in response to a backward movement of a main spindle.

According to an aspect of the present invention, there is provided a power tool configured to rotationally drive a tip tool. The work tool has a housing, a spindle, a motor, and a power transmission mechanism.

The spindle is supported by the housing so as to be movable in a front-rear direction along a predetermined drive shaft extending in the front-rear direction of the power tool and rotatable about the drive shaft. The spindle has a tip portion configured to be attachable to and detachable from the tip tool. The motor and the power transmission mechanism are housed in the case. The power transmission mechanism includes a sun member, a ring member, a carrier member, and planetary rollers. The sun member, the ring member, and the carrier member are disposed coaxially with the drive shaft. The planetary rollers are rotatably held by the carrier member. The sun member and the ring member have 1 st and 2 nd tapered surfaces, respectively, which are inclined with respect to the drive shaft. One of the sun member and the ring member is configured to be movable in the front-rear direction integrally with the main shaft relative to the other. At least a part of the planetary roller is disposed between the 1 st tapered surface and the 2 nd tapered surface in a radial direction with respect to the drive shaft.

The power transmission mechanism is configured to transmit power of the motor to the main shaft by relatively moving the sun member and the ring member in a direction to approach each other in response to backward movement of the main shaft, and bringing the planetary rollers into frictional contact with the sun member and the ring member. The power transmission mechanism is configured such that the sun member and the ring member are relatively moved in a direction away from each other in response to the forward movement of the main shaft, and the planetary rollers are brought into non-frictional contact with the sun member and the ring member, thereby blocking the transmission of power. The work tool further includes a regulating member configured to regulate the movement of the planetary roller in the forward and backward direction with respect to the housing. The term "restriction of movement" used herein is not limited to the complete prohibition of movement, but also includes the case where slight movement is permitted.

The power tool of the present embodiment includes a so-called planetary roller type power transmission mechanism. In the power transmission mechanism, at least a part of the planetary rollers is disposed between the 1 st tapered surface of the sun member and the 2 nd tapered surface of the ring member in a radial direction of the main shaft with respect to the drive shaft (a direction orthogonal to the drive shaft). One of the sun member and the ring member is movable in the front-rear direction integrally with the main shaft relative to the other. In contrast, the planetary rollers are restricted from moving in the front-rear direction by the restricting member. Therefore, the planetary rollers move in the front-rear direction along with the relative movement of the sun member and the ring member, and the possibility that the frictional contact between the 1 st tapered surface and the 2 nd tapered surface becomes unstable can be reduced.

In one aspect of the present invention, the carrier member may be held to the main shaft so as to be movable in the front-rear direction with respect to the main shaft. In other words, the planet carrier member may be independent of the main shaft with respect to movement in the forward and rearward directions. The carrier member needs to be disposed at a position where the planetary rollers can be held so that the planetary rollers do not come off between the 1 st tapered surface of the sun member and the 2 nd tapered surface of the ring member. In contrast, according to the present embodiment, the carrier member can be held at an appropriate position regardless of the movement of the main shaft. Accordingly, compared to the case where the carrier member moves integrally with the main shaft, the restriction on the amount of movement of the main shaft in the front-rear direction can be reduced. In particular, when the planetary rollers or the 1 st and 2 nd tapered surfaces are worn, the main shaft needs to be pressed into a position where the sun member and the ring member are closer to each other in order to establish stable frictional contact. That is, the amount of movement of the main shaft in the front-rear direction needs to be increased, but this aspect can also appropriately cope with this demand.

In one aspect of the present invention, the carrier member may be held to the main shaft so as not to be rotatable about the drive shaft. The carrier member may be configured to rotate integrally with the main shaft by power transmitted via the planetary rollers. According to this aspect, a rational planetary roller type power transmission mechanism can be realized in which the carrier member is the output member.

In one aspect of the present invention, the restricting member may be configured to restrict the movement of the carrier member in the front-rear direction with respect to the case. According to this aspect, the movement of the planetary rollers and the carrier member in the front-rear direction is restricted by the restricting member, and therefore the proper positional relationship between the planetary rollers and the carrier member can be more reliably maintained.

In one aspect of the present invention, the restricting member may include a spring member that urges the main shaft and the carrier member away from each other in the front-rear direction. Also, the main shaft can be normally held at the most forward position by the urging force of the spring member. According to this aspect, when the main shaft is released from being pushed in while the movement of the carrier member is regulated by the biasing force of the spring member, the main shaft can be returned to the most forward position (i.e., the initial position).

In one aspect of the present invention, the ring member may be supported by the main shaft so as to be movable in the front-rear direction integrally with the main shaft and rotatable about the drive shaft. The spring member may be interposed between the carrier member and the ring member in the front-rear direction. The power tool may further include a receiving member that receives one end of the spring member on the ring member side in a state where the receiving member does not rotate with rotation of the ring member. According to this aspect, the spring member can be prevented from rotating together with the ring member (so-called co-rotation), or heat can be prevented from being generated at the sliding portion between the spring member and the ring member.

In one aspect of the present invention, the ring member may be configured to be rotated by power of a motor. The spring member may be configured to bias the ring member and the carrier member forward and backward so as to be away from each other. In other words, the spring member also has a function of biasing the ring member, which is the driving-side member in the power transmission mechanism, and the carrier member, which is the driven-side member, in the direction of interrupting the transmission. According to this aspect, a plurality of functions such as restriction of movement of the carrier member in the front-rear direction and interruption of power transmission can be achieved by the spring member without increasing the number of components.

In one aspect of the present invention, the annular member may have at least 1 communication hole that communicates the inside and the outside of the annular member. According to this aspect, the air flow can be generated through the communication hole by the centrifugal force generated in association with the driving of the power transmission mechanism (typically, the rotation of the ring member). This can suppress a local temperature rise in the power transmission mechanism and achieve smoother circulation of the lubricant disposed in the housing. As a result, wear of the planetary roller, the 1 st tapered surface, and the 2 nd tapered surface can be effectively reduced, and durability can be improved.

In an aspect of the present invention, the communication hole may be formed in a region of the annular member other than a region corresponding to the 2 nd tapered surface. According to this aspect, the communication hole can be easily formed in the ring member.

Drawings

Fig. 1 is a side view of an electric driver (Screwdriver) according to embodiment 1.

Fig. 2 is a longitudinal sectional view of the electric screwdriver.

Fig. 3 is a partially enlarged view of fig. 2.

Fig. 4 is a sectional view IV-IV of fig. 3.

Fig. 5 is a partially enlarged view of fig. 3.

Fig. 6 is a partially enlarged view of fig. 4.

Fig. 7 is an exploded perspective view of the main shaft, the power transmission mechanism, and the position switching mechanism.

Fig. 8 is a sectional view VIII-VIII of fig. 3, which corresponds to the roller, and is an explanatory diagram showing a non-frictional contact state between the roller, the taper sleeve (taper sleeve), and the gear sleeve (gear sleeve).

Fig. 9 is a longitudinal sectional view of the electric screwdriver in a state where the spindle is moved rearward from the home position and the power transmission mechanism is in a transmittable state.

Fig. 10 corresponds to the cross-sectional X-X view of fig. 9, and is an explanatory diagram showing a frictional contact state between the roller and the taper sleeve and the gear sleeve.

Fig. 11 is a cross-sectional view XI-XI of fig. 3, which is an explanatory diagram showing a state of the one-way clutch in a case where the gear sleeve is rotationally driven in the forward direction.

Fig. 12 is a cross-sectional view corresponding to fig. 11, and is an explanatory diagram showing a state of the one-way clutch in a case where the gear sleeve is rotationally driven in the reverse direction.

Fig. 13 is a cross-sectional view corresponding to fig. 4, and is an explanatory diagram showing a state in which a guide sleeve (lead sleeve) and a gear sleeve are moved rearward.

Fig. 14 is a longitudinal sectional view of the electric screwdriver in a state where the retainer (locator) is in contact with the workpiece and the screw tightening operation is completed.

Fig. 15 is a longitudinal sectional view of the electric screwdriver according to embodiment 2.

Fig. 16 is a cross-sectional view of XVI-XVI of fig. 15.

Fig. 17 is an exploded perspective view of the main shaft, the power transmission mechanism, and the position switching mechanism.

Fig. 18 is a sectional view corresponding to fig. 15, and is an explanatory diagram showing a state in which the gear sleeve is moved rearward.

Fig. 19 is a sectional view corresponding to fig. 16, and is an explanatory diagram showing a state in which the gear sleeve is moved rearward.

Fig. 20 is a longitudinal sectional view of the electric screwdriver according to embodiment 3.

Fig. 21 is a sectional view XXI-XXI of fig. 20.

Fig. 22 is an exploded perspective view of the main shaft, the power transmission mechanism, and the position switching mechanism.

Fig. 23 is a partially enlarged view of fig. 21.

Detailed Description

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

[ embodiment 1]

The electric driver 1 according to embodiment 1 will be described with reference to fig. 1 to 14. The electric screwdriver 1 is an example of a power tool that rotationally drives a tip tool. More specifically, the electric driver 1 is an example of a screw tightening tool that can perform a screw tightening operation or a screw loosening operation by driving and rotating a driver bit 9 attached to the spindle 3.

First, a schematic configuration of the electric driver 1 will be explained. As shown in fig. 1 and 2, the electric driver 1 includes: a main body 10 including a motor 2, a spindle 3, and the like; and a handle portion 17 including a grip portion 171. The main body portion 10 is formed in an elongated shape extending along a predetermined drive shaft a1 (drive axis a 1). The driver bit 9 is detachably attached to one end portion in the longitudinal direction of the main body 10 (the extending direction of the drive shaft a 1). The grip portion 17 is formed in a C-shape as a whole, and is annularly connected to the other end portion in the longitudinal direction of the main body portion 10. The portion of the grip portion 17 that is separated from the main body portion 10 and linearly extends in a direction substantially orthogonal to the drive shaft a1 constitutes a grip portion 171 to be gripped by a user. Further, one end portion of the grip 171 in the longitudinal direction is disposed on the drive shaft a 1. A trigger 173 that can be operated by a user is provided at the one end portion. A power cable 179 connectable to an external ac power source is connected to the other end of the grip 171.

In the electric screwdriver 1 of the present embodiment, the motor 2 is driven when the user pulls the operation trigger 173. When the spindle 3 is pushed rearward, the power of the motor 2 is transmitted to the spindle 3 to rotate the driver bit 9. Accordingly, the screw fastening operation or the screw loosening operation is performed.

Next, the detailed structure of the electric driver 1 will be explained. In the following description, for convenience of explanation, the extending direction (axial direction) of the drive shaft a1 is defined as the front-rear direction of the electric driver 1. In the front-rear direction, the side on which the driver bit 9 is attached and detached is defined as the front side, and the side on which the grip 171 is disposed is defined as the rear side. A direction perpendicular to the drive shaft a1 and corresponding to the extending direction of the grip portion 171 is defined as the vertical direction. In the vertical direction, the side on which the trigger 173 is disposed is defined as the upper side, and the side to which the power cable 179 is connected is defined as the lower side. The directions orthogonal to the front-rear direction and the up-down direction are defined as the left-right direction.

First, the main body 10 and the grip 17 will be briefly described. As shown in fig. 2, the outer contour of the main body portion 10 is mainly formed by the main body housing 11. The main body casing 11 includes: a cylindrical rear housing 12 that houses the motor 2; a cylindrical front housing 13 that houses the spindle 3; and a center housing 14 disposed between the rear housing 12 and the front housing 13. The front end portion of the center housing 14 has a partition wall 141 disposed substantially orthogonal to the drive shaft a 1. The center case 14 and the front case 13 are fixed to the rear case 12 with screws, whereby 3 cases are integrated into the main body case 11. Further, the details of the internal structure including the main body 10 will be described on the rear surface.

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

As shown in fig. 2, the outer contour of the handle portion 17 is mainly formed by the handle housing 18. The handle case 18 is formed of a left and right split body. In addition, the left split body is formed integrally 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 disposed in the grip 171 on the rear side of the trigger 173. The main switch 174 is normally maintained in an off state and is switched to an on state in response to a pulling operation of the trigger 173. The main switch 174 outputs a signal indicating an on state or an off state to the controller 178 through a wiring not shown.

A switching lever 175 is provided in a portion of the handle housing 18 connected to a lower end portion of the grip portion 171 and a lower rear end portion of the main body portion 10 (rear housing 12), and the switching lever 175 switches a rotation direction of the driver bit 9 (in detail, a rotation direction of the motor shaft 23). The user can set the rotational direction of the motor shaft 23 to one of the direction in which the driver bit 9 fastens the screw 90 (forward direction, also referred to as screw fastening direction) and the direction in which the driver bit 9 unscrews the screw 90 (reverse direction, also referred to as screw unscrewing direction) by operating the switching lever 175. The rotation direction switch 176 outputs a signal corresponding to the rotation direction set via the switching lever 175 to the controller 178 through a wiring not shown.

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

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

As shown in fig. 2, the motor 2 is housed in the rear housing 12. In the present embodiment, an ac motor is used as the motor 2. The motor shaft 23 extending from the rotor 21 of the motor 2 extends below the drive shaft a1 in parallel with the drive shaft a1 (in the front-rear direction). The front end portion and the rear end portion of the motor shaft 23 are rotatably supported by bearings 231, 233. The front bearing 231 is supported by the partition wall 141 of the center housing 14, and the rear bearing 233 is supported by the rear end of the rear housing 12. Fan 25 for cooling motor 2 is fixed to a portion of motor shaft 23 on the front side of rotor 21 and is housed in center housing 14. The 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 24 is formed at the front end of the motor shaft 23.

As shown in fig. 3 and 4, the main shaft 3, the power transmission mechanism 4, and the position switching mechanism 5 are housed in the front housing 13. The detailed structure of these components will be described in turn.

As shown in fig. 3 and 4, the main shaft 3 is a substantially cylindrical elongated member extending in the front-rear direction along the drive shaft a 1. In the present embodiment, the spindle 3 is configured to be fixedly connected to and integrated with a front shaft 31 and a rear shaft 32, which are formed separately. However, the main shaft 3 may be constituted by only a single shaft. The main shaft 3 has a flange 34 protruding radially outward at a central portion in the front-rear direction (more specifically, a rear end portion of the front shaft 31).

The main shaft 3 is supported by a bearing (specifically, an oilless bearing) 301 and a bearing (specifically, a ball bearing) 302 so as to be rotatable about a drive axis a1 and movable in the front-rear direction along a drive shaft a 1. The bearing 301 is supported by the partition wall 141 of the center housing 14. The bearing 302 is supported at the front end of the front housing 13. The spindle 3 is normally biased forward by biasing force of a biasing spring 49 described later, and is held at a position where the front end surface of the flange 34 abuts against a stopper 135 provided in the front housing 13. The position of the spindle 3 at this time is the most forward position (also referred to as the initial position) within the movable range of the spindle 3. Further, the front end of the spindle 3 (front shaft 31) protrudes from the front housing 13 into the retainer 15. A tool bit insertion hole 311 is provided along the drive shaft a1 at the tip end of the spindle 3 (the front shaft 31). A steel ball biased by a leaf spring (leaf spring) engages with the small diameter portion of the driver bit 9 inserted into the bit insertion hole 311, whereby the driver bit 9 is detachably held.

Next, the power transmission mechanism 4 will be explained. As shown in fig. 3 and 4, the power transmission mechanism 4 of the present embodiment is mainly configured by a planetary mechanism including a taper sleeve 41, a retainer (retainer)43, a plurality of rollers 45, and a gear sleeve 47. The taper sleeve 41, the retainer 43, and the gear sleeve 47 are arranged coaxially with the main shaft 3 (drive shaft a 1). The taper sleeve 41, the cage 43, the rollers 45, and the gear sleeve 47 correspond to a sun member, a carrier member, a planetary member, and a ring member in the planetary mechanism, respectively. In the present embodiment, the power transmission mechanism 4 is configured as a so-called sun planetary reduction mechanism in which the conical sleeve 41 as a sun member is fixed, the gear sleeve 47 as an annular member operates as an input member, and the cage 43 as a carrier member operates as an output member. Therefore, the gear sleeve 47 and the holder 43 (the spindle 3) rotate in the same direction.

The power transmission mechanism 4 is configured to transmit or block the power of the motor 2 to the spindle 3. Specifically, the power transmission mechanism 4 is configured such that the rollers 45 are brought into a frictional contact state or a non-frictional contact state with the taper sleeve 41 and the gear sleeve 47 as the gear sleeve 47 moves in the front-rear direction relative to each other in a direction of approaching or separating from the taper sleeve 41, the retainer 43, and the rollers 45. Accordingly, 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, the power transmission mechanism 4 of the present embodiment can be configured as a planetary roller type friction clutch mechanism.

Next, the detailed structure and arrangement of the components of the power transmission mechanism 4 will be described.

First, the tapered sleeve 41 will be explained. As shown in fig. 5 to 7, the tapered sleeve 41 corresponding to the sun member is configured as a cylindrical member. The tapered sleeve 41 is fixed to the main body case 11 (specifically, the partition wall 141) by the base 143 so as not to rotate around the drive shaft a 1. The base 143 is fixed to the partition wall 141 on the front side of the bearing 301 that supports the rear end portion of the spindle 3 (rear shaft 32), and is integrated with the main body case 11. The spindle 3 (more specifically, the rear shaft 32) is inserted through the tapered sleeve 41 in a clearance fit manner, and is rotatable while being movable in the front-rear direction with respect to the tapered sleeve 41.

The outer peripheral surface of the tapered sleeve 41 is configured as a tapered surface 411 inclined at a predetermined angle with respect to the drive shaft a 1. Specifically, the tapered sleeve 41 has a truncated cone shape whose outer shape is tapered (diameter is reduced) toward the front. The tapered surface 411 is configured as a conical surface inclined in a direction approaching the drive shaft a1 as it approaches the front. In the present embodiment, the inclination angle of the tapered surface 411 with respect to the drive axis a1 is set to approximately 4 degrees (approximately 8 degrees when viewed in a cross section of a cone).

Next, the retainer 43 will be explained. The cage 43 as a carrier member is a member that rotatably holds the rollers 45 as a planetary member. As shown in fig. 5 to 7, the retainer 43 includes: a bottom wall 431 having a substantially circular shape and having a through hole; and a plurality of retaining arms 434 protruding from the outer edge of the bottom wall 431. The holding arms 434 are arranged apart from each other in the circumferential direction. In the present embodiment, the retainer 43 has 10 holding arms 434, but the number of the holding arms 434 (and the number of the rollers 45) can be changed as appropriate. The holder 43 is disposed in such a direction that the bottom wall 431 is positioned on the front side (so that the holding arm 434 protrudes rearward). The holder 43 is supported by the spindle 3 so as to be unrotatable relative to the spindle 3 and movable in the forward-backward direction in a state where a part of the holding arm 434 overlaps the tapered sleeve 41 in the radial direction. Each of the holding arms 434 projects rearward from the outer edge of the bottom wall 431 at the same inclination angle as the tapered surface 411 of the tapered socket 41 with respect to the drive shaft a1 (i.e., parallel to the tapered surface 411).

As shown in fig. 6 and 7, a pair of grooves 321 is formed in a front portion of a rear end portion of the rear shaft 32 of the main shaft 3 with a drive shaft a1 interposed therebetween. Each groove 321 has a U-shaped cross section, and each groove 321 extends linearly in the front-rear direction. Steel balls 36 are arranged in each groove 321 in a rollable manner. Further, a pair of recesses 432 are formed on the rear surface (surface on the side of the holding arm 434) of the bottom wall 431 of the holder 43 with the drive shaft a1 interposed therebetween. A part of the balls 36 disposed in the groove 321 is engaged with the concave portion 432. An annular recess 414 is formed in the center of the distal end surface of the tapered sleeve 41. Specifically, the retainer 43 is biased rearward by the biasing spring 49, and the balls 36 are disposed in the space defined by the recesses 414 and 432, and are held in a state where the rear surface of the bottom wall 431 is in contact with the front end surface of the tapered sleeve 41. Further, the rear end of the holding arm 434 is disposed at a position separated from the base 143 toward the front side.

According to this configuration, the cage 43 is engaged with the main shaft 3 by the balls 36 in the radial direction and the circumferential direction of the main shaft 3, and is rotatable integrally with the main shaft 3. The balls 36 are able to roll in the annular recess 414 of the tapered sleeve 41, and the cage 43 is able to rotate about the drive shaft a1 with respect to the tapered sleeve 41 together with the spindle 3. On the other hand, the spindle 3 is movable in the forward and backward direction with respect to the holder 43 within a range in which the balls 36 can roll in the grooves 321.

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

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

The gear sleeve 47 has: a bottom wall 471 having a through hole; and a peripheral wall 474 having a cylindrical shape and connected to the bottom wall 471. The outer race 481 of the bearing (more specifically, 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 disposed in a front direction (so as to open rearward) with the bottom wall 471 positioned at the front side. The gear sleeve 47 is supported by the spindle 3 at a position forward of the holder 43 so as to be rotatable with respect to the spindle 3 and movable in the front-rear direction. More specifically, the rear shaft 32 of the spindle 3 is inserted through the through hole of the bottom wall 471 in a clearance fit manner, and is inserted through the inner ring 483 of the bearing 48 so as to be slidable in the front-rear direction. Accordingly, a cylindrical inner space is formed between the main shaft 3 and the peripheral wall 474 on the rear side of the bearing 48. In the internal space, a part of the taper sleeve 41, the retainer 43, and the roller 45, and an urging spring 49 described later are disposed. Further, gear teeth 470 that constantly mesh with the pinion gear 24 are integrally formed on the outer periphery of the gear sleeve 47 (specifically, the peripheral wall 474). Therefore, the gear sleeve 47 is rotationally driven in accordance with the rotation of the motor shaft 23.

An inner peripheral surface of a portion (a portion on the opening end side) of the peripheral wall 474 of the gear sleeve 47 on the rear side of the bearing 48 includes a tapered surface 475, and the tapered surface 475 is inclined at the same angle as the tapered surface 411 of the tapered sleeve 41 (i.e., is parallel to the tapered surface 411) with respect to the drive shaft a 1. That is, the tapered surface 475 is formed as a conical surface that is inclined in a direction away from the drive shaft a1 as it approaches the rear (the open end of the gear sleeve 47). The roller 45 held by the holder 43 is held so that at least a part (specifically, a front part) thereof is positioned between the tapered surface 411 and the tapered surface 475 in the radial direction of the spindle 3 (a direction orthogonal to the drive shaft a 1).

In the present embodiment, the power transmission mechanism 4 includes the biasing spring 49, and the biasing spring 49 is interposed between the gear sleeve 47, the retainer 43, and the roller 45 in the front-rear direction. In the present embodiment, the biasing spring 49 is configured as a conical coil spring, and is disposed such that the end portion on the large diameter side is the rear side and the end portion on the small diameter side is the front side. More specifically, the end on the large diameter side abuts against the large diameter spacer 491, and the end on the small diameter side abuts against the small diameter spacer 493. The spacer 491 is disposed so as to abut against the front end face of the holding arm 434 of the holder 43. The washer 493 is disposed so as to abut against the inner ring 483 but not against the outer ring 481 of the bearing 48 mounted in the gear sleeve 47. That is, the biasing spring 49 is rotatable together with the holder 43, but is not rotated in association with the rotation of the gear sleeve 47.

The biasing spring 49 always biases the holder 43 and the gear sleeve 47 in the direction away from each other, that is, rearward and forward, through the spacers 491 and 493. Accordingly, the retainer 43 is held by the biasing force of the biasing spring 49 at a position where the rear surface of the bottom wall 431 abuts against the front end surface of the tapered sleeve 41, and is restricted from moving in the front-rear direction thereof. The roller 45 is held between the spacer 491 and the front end face of the base 143 fixed to the main body case 11, and is restricted from moving in the front-rear direction. Here, the term "restricting movement" does not mean that movement is completely prohibited, and slight movement may be permitted. In the present embodiment, the distance between the pad 491 and the front end face of the base 143 is set to be slightly longer than the roller 45 (i.e., a play is provided), and the movement of the roller 45 is allowed by the play. The biasing spring 49 may directly contact the holder 43 and the inner ring 483 without interposing the spacers 491, 493 therebetween.

Further, the gear sleeve 47 is biased forward by the biasing force of the biasing spring 49, whereby the spindle 3 is also biased forward by a thrust bearing (thrust bearing)53, a guide sleeve 500, and balls 508, which will be described later, and is held at an initial position where the flange 34 abuts against the stopper portion 135.

When the spindle 3 is disposed at the initial position, as shown in fig. 5 and 8, the rollers 45 are disposed between the tapered surface 411 of the tapered sleeve 41 and the tapered surface 475 of the gear sleeve 47 in a clearance fit manner (more specifically, are separated from the tapered surface 475), and are in a non-frictional contact state with the tapered sleeve 41 and the gear sleeve 47. That is, the power transmission mechanism 4 is in the disengaged state. On the other hand, when the gear sleeve 47 moves backward (approaches the taper sleeve 41, the holder 43, and the rollers 45) with respect to the main body housing 11 as shown in fig. 9 and the interval between the taper surface 411 of the taper sleeve 41 and the taper surface 475 of the gear sleeve 47 becomes narrow, the rollers 45 are sandwiched between the taper surface 411 and the taper surface 475 and brought into a frictional contact state with the taper sleeve 41 and the gear sleeve 47 as shown in fig. 10. Accordingly, the power transmission mechanism 4 shifts to the transmittable state. The operation of the power transmission mechanism 4 will be described later.

Next, the position switching mechanism 5 will be explained. The position switching mechanism 5 is a mechanism that relatively moves the gear sleeve 47 and the tip end portion of the main shaft 3 in a direction away from each other in the front-rear direction when the gear sleeve 47 is rotationally driven in the reverse direction (screw loosening direction). According to this configuration, when the gear sleeve 47 is rotationally driven in the reverse direction (screw loosening direction) in a state where the main shaft 3 is disposed at the initial position, the position switching mechanism 5 moves the gear sleeve 47 rearward with respect to the main shaft 3, and approaches the retainer 43 and the roller 45. Next, the position switching mechanism 5 will be described in detail.

As shown in fig. 5 to 7, in the present embodiment, the position switching mechanism 5 includes a one-way clutch 50, a guide sleeve 500 having a guide groove (lead groove)507, and balls 508.

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

As shown in fig. 7 and 11, the cam groove 501 is a groove recessed from the outer peripheral surface of the peripheral wall 474 of the front end portion of the gear sleeve 47 toward the inside in the radial direction of the gear sleeve 47. The depth of the cam groove 501 in the radial direction from the outer peripheral surface is smaller from the upstream side to the downstream side in the forward direction (screw tightening direction) of the gear sleeve 47 indicated by an arrow a in the figure (larger from the upstream side to the downstream side in the reverse direction (screw loosening direction) of the gear sleeve 47 indicated by an arrow B in the figure). In the present embodiment, 4 cam grooves 501 are provided at equal intervals in the circumferential direction around the drive shaft a 1. A steel ball 502 is disposed in each cam groove 501. As shown in fig. 11, the diameter of the ball 502 is set to be slightly larger than the depth of the deepest portion (i.e., the upstream side end portion in the positive direction) in the cam groove 501.

As shown in fig. 5 to 7, the guide sleeve 500 is formed into a substantially cup-shaped member, and includes: a bottom wall 505 having a through hole; and a peripheral wall 504 having a cylindrical shape and protruding from an outer edge of the bottom wall 505. The guide sleeve 500 is disposed between the gear sleeve 47 and the flange 34 of the spindle 3 in a state where the bottom wall 505 is disposed on the front side and the rear shaft 32 of the spindle 3 is inserted into the through hole of the bottom wall 505 in a clearance fit manner. A thrust bearing (more specifically, a thrust ball bearing)53 is disposed between the rear surface of the bottom wall 505 and the front end surface of the bottom wall 471 of the gear sleeve 47. The thrust bearing 53 receives a thrust load while allowing the guide sleeve 500 to rotate relative to the gear sleeve 47. Further, annular concave portions having a U-shaped cross section are formed on the rear surface of the bottom wall 505 and the front end surface of the bottom wall 471, respectively. Balls as rolling elements of the thrust bearing 53 can roll in a circular orbit defined by the concave portions.

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

With this configuration, the one-way clutch 50 rotates the guide 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 forward direction (the direction of arrow a in the figure), the balls 502 move relatively to the deepest portion (the upstream end portion in the forward direction (the direction of arrow a)) of the cam groove 501. The balls 502 are disposed between the wall surface of the cam groove 501 and the inner peripheral surface of the peripheral wall 504 in a clearance fit manner, and rotate together with the gear sleeve 47 about the drive shaft a 1. 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 guide sleeve 500.

On the other hand, as shown in fig. 12, when the gear sleeve 47 is rotationally driven in the reverse direction (the direction of arrow B in the figure), the balls 502 move relatively from the deepest portion of the cam groove 501 to a shallower portion (the upstream side in the reverse direction (the direction of arrow B)). Accordingly, 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 guide sleeve 500 are integrated by the ball 502 due to a frictional force generated by the wedge action. That is, the one-way clutch 50 shifts to the transmittable state, and the guide sleeve 500 rotates in the reverse direction together with the gear sleeve 47.

The guide grooves 507 and the balls 508 are configured to move the guide sleeve 500 relative to the main shaft 3 in the front-rear direction as the guide sleeve 500 rotates about the drive shaft a1, and to move the gear sleeve 47 relative to the holder 43 and the rollers 45 in the front-rear direction as well. As shown in fig. 5 to 7, in the present embodiment, the guide groove 507 is formed as a spiral groove (strictly speaking, a groove having a shape corresponding to a part of a spiral) formed in the distal end surface of the bottom wall 505 of the guide sleeve 500. The guide grooves 507 are provided at 3 equally spaced intervals in the circumferential direction apart from each other. More specifically, the depth of the guide groove 507 in the front-rear direction from the front end surface is smaller from the upstream side to the downstream side in the forward direction (screw tightening direction) of the gear sleeve 47 indicated by an arrow a in fig. 7 (larger from the upstream side to the downstream side in the reverse direction (screw loosening direction) of the gear sleeve 47 indicated by an arrow B in fig. 7). A steel ball 508 is disposed in each guide groove 507.

As described above, the gear sleeve 47 is always biased forward by the biasing spring 49 disposed between the holder 43 and the gear sleeve 47 (more specifically, the bearing 48). Therefore, as shown in fig. 5 and 6, the thrust bearing 53, the guide sleeve 500, and the balls 508 are also biased forward, and the balls 508 abut against the rear surface of the flange 34. The spindle 3 is also biased forward by the flange 34 and normally held at the initial position.

With this configuration, the relative positional relationship between the spindle 3 and the guide sleeve 500 in the front-rear direction changes according to the position of the ball 508 in the guide groove 507. More specifically, as shown in fig. 4, when the balls 508 are disposed at the deepest portion (i.e., the upstream end portion in the positive direction) of the guide grooves 507, the distance between the flange 34 and the guide sleeve 500 in the front-rear direction is smallest. That is, the guide sleeve 500 is disposed at the forefront position within the movable range with respect to the spindle 3. In a state where the spindle 3 is disposed at the initial position, the gear sleeve 47 is disposed at the farthest position from the retainer 43 and the rollers 45 in the front-rear direction.

On the other hand, when the one-way clutch 50 is operated as described above and the guide sleeve 500 rotates in the reverse direction together with the gear sleeve 47, the balls 508 move relatively from the deepest portion of the guide groove 507 to the shallowest portion (upstream side in the reverse direction). The balls 508 abut on the rear surface of the flange 34, and therefore, as shown in fig. 13, the guide sleeve 500 moves in a direction away from the flange 34 (rearward with respect to the main shaft 3) against the biasing force in response to the relative movement of the balls 508. Accordingly, the guide bush 500 moves the gear bush 47 rearward with respect to the spindle 3, i.e., in a direction approaching the retainer 43 and the roller 45 against the biasing force of the biasing spring 49. When the balls 508 are arranged at the shallowest portion, the distance between the flange 34 and the guide sleeve 500 in the front-rear direction is the largest. In the state where the spindle 3 is disposed at the initial position, the gear sleeve 47 is disposed at a position closer to the intermediate position between the retainer 43 and the roller 45 than the case where it is disposed at the farthest position. That is, the relative positions of the gear sleeve 47, the holder 43, and the roller 45 are switched from the farthest position to the intermediate position.

Next, the operations of the power transmission mechanism 4 and the position switching mechanism 5 that are associated with the driving of the motor 2 and the movement of the main shaft 3 will be described.

First, in an initial state where the motor 2 is not driven and no external force is applied to the spindle 3 in the rearward direction, the spindle 3 is disposed at the initial position by the biasing force of the biasing spring 49. As described above, at this time, as shown in fig. 5 and 8, the rollers 45 are in a non-frictional contact state with the taper sleeve 41 and the gear sleeve 47. That is, the power transmission mechanism 4 is in the disengaged state.

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

When the main switch 174 is turned on by the user pulling the operation trigger 173 in a state where the spindle 3 is disposed at the home position, the controller 178 starts driving the motor 2. As indicated by an arrow a in fig. 11, the gear sleeve 47 is rotationally driven in the forward direction (screw fastening direction). At this time, since the one-way clutch 50 is not operated as described above, the rotational force of the gear sleeve 47 is not transmitted to the guide sleeve 500. Thus, the gear sleeve 47, the retainer 43, the roller 45 are held in the most distant position. Further, since the power transmission mechanism 4 is in the disengaged state, the rotational force of the gear sleeve 47 is not transmitted to the spindle 3, and the gear sleeve 47 idles in the forward direction.

As shown in fig. 12, in a state where the ball 502 is held between the wall surface of the cam groove 501 and the inner peripheral surface of the peripheral wall 504 (that is, in a state where the gear sleeve 47, the holder 43, and the roller 45 are arranged at intermediate positions), a screw loosening operation described later may be ended. In this case, in response to the gear sleeve 47 rotating in the forward direction, the ball 502 is released from being pinched, and the guide sleeve 500 returns to the most forward position by the biasing force of the biasing spring 49 and the action of the guide groove 507 and the ball 508. Accordingly, the gear sleeve 47, the holder 43, and the roller 45 return from the intermediate position to the farthest position.

In the idle state of the gear sleeve 47, when the user moves the electric screwdriver 1 forward (one side of the workpiece 900) and presses the screw 90 engaged with the screwdriver bit 9 against the workpiece 900, the spindle 3 is pushed backward with respect to the main body housing 11 against the biasing force of the biasing spring 49. When pressed by the flange 34, the balls 508, the guide sleeve 500, the thrust bearing 53, and the gear sleeve 47 also move rearward relative to the main body housing 11 integrally with the main shaft 3. On the other hand, the taper sleeve 41 is fixed to the main body housing 11, and the retainer 43 and the roller 45 are held in a state where movement in the front-rear direction with respect to the main body housing 11 is restricted. Therefore, the gear sleeve 47 approaches the taper sleeve 41, the holder 43, and the roller 45 as it moves rearward, and the distance between the taper surface 411 of the taper sleeve 41 and the taper surface 475 of the gear sleeve 47 in the radial direction gradually decreases.

Accordingly, as shown in fig. 9 and 10, the roller 45 held by the holder 43 is sandwiched between the tapered surface 411 and the tapered surface 475 to be in a frictional contact state (frictional force due to wedge action is generated at a contact portion between the roller 45 and the tapered surfaces 411 and 475). That is, the gear sleeve 47, the holder 43, and the rollers 45 are arranged at positions where the rotational force can be transmitted from the gear sleeve 47 to the holder 43 via the rollers 45. The roller 45 revolves while rotating on the tapered surface 411 of the tapered sleeve 41 by the rotation of the gear sleeve 47, and rotates the retainer 43 around the drive shaft a 1. The holder 43 is integrated with the spindle 3 in the circumferential direction around the drive shaft a1, and therefore, the spindle 3 also rotates together with the holder 43. In this way, in response to the spindle 3 moving rearward from the initial position, the power transmission mechanism 4 shifts from the cut-off state to the transmission-enabled state, and starts screwing the screw 90 into the workpiece 900. The spindle 3 rotates in the same direction as the gear sleeve 47 at a speed slower than the rotational speed of the gear sleeve 47.

When the screw 90 is screwed into the workpiece 900 and the distal end portion of the positioner 15 abuts against the workpiece 900 as shown in fig. 14, the portion receiving the pressing force is shifted from the spindle 3 to the positioner 15, and thus the pressing force on the spindle 3 gradually decreases. Therefore, the force (corresponding to the sum of the pressing force of the spindle 3 and the force of biasing the spindle 3 forward by the biasing spring 49) of holding the rollers 45 between the tapered surface 411 of the tapered sleeve 41 and the tapered surface 475 of the gear sleeve 47, and the rotational force transmitted from the gear sleeve 47 to the spindle 3 also gradually decreases. When the rotational force transmitted from the gear sleeve 47 to the spindle 3 is lower than the rotational force required to tighten the screw 90, the rotation of the screw 90 is stopped, and the screw tightening operation is completed.

On the other hand, when the reverse direction (screwing direction) is set as the rotation direction of the motor shaft 23 by the switching lever 175, the electric screwdriver 1 operates as follows to perform the screwing operation.

When the main switch 174 is turned on by the user pulling the operation trigger 173 with the spindle 3 disposed at the initial position, the controller 178 starts driving the motor 2. As shown by an arrow B in fig. 12, the gear sleeve 47 is rotationally driven in the reverse direction (screw loosening direction). Accordingly, as described above, the one-way clutch 50 operates to rotate the guide sleeve 500 in the reverse direction. As shown in fig. 13, the gear sleeve 47 moves rearward with respect to the main shaft 3, i.e., in a direction approaching the retainer 43 and the roller 45, against the biasing force of the biasing spring 49 by the action of the guide groove 507 and the ball 508. That is, during the screw loosening operation, regardless of the presence or absence of the backward movement of the spindle 3 (in a state where the spindle 3 is disposed at the initial position), the relative positions of the gear sleeve 47, the holder 43, and the roller 45 are switched from the farthest apart position to the intermediate position in response to the gear sleeve 47 being rotationally driven in the reverse direction.

As shown in fig. 13, even when the gear sleeve 47, the holder 43, and the rollers 45 are disposed at the intermediate positions, the rollers 45 are separated from the tapered surface 475 and are in a non-frictional contact state with the tapered sleeve 41 and the gear sleeve 47, as in the case where the rollers 45 are disposed at the farthest positions. Therefore, the rotational force of the gear sleeve 47 is not transmitted to the spindle 3. That is, the power transmission mechanism 4 is in the disengaged state, and the gear sleeve 47 idles in the reverse direction.

When the user moves the electric screwdriver 1 forward in the idling state of the gear sleeve 47 to press the driver bit 9 against the screw 90 fastened to the workpiece 900 and engage the screw 90 with the screw, the spindle 3 is pushed rearward with respect to the main body housing 11 against the biasing force of the biasing spring 49. The gear sleeve 47 is close to the taper sleeve 41, the holder 43, and the roller 45, and the gear sleeve 47, the holder 43, and the roller 45 are arranged at the transfer position. The roller 45 is sandwiched between the tapered surface 411 and the tapered surface 475 to be in a frictional contact state, the power transmission mechanism 4 is switched from the cut state to the transmission-enabled state, and the screw 90 is loosened and removed from the workpiece 900.

As described above, when the screw loosening operation is performed, the gear sleeve 47 is moved rearward relative to the main shaft 3 by the position switching mechanism 5 than when the screw tightening operation is performed, and the distance between the gear sleeve 47 and the retainer 43 and the roller 45 in the front-rear direction is reduced. Therefore, the movement distance of the main shaft 3 in the front-rear direction until the gear sleeve 47, the holder 43, and the roller 45 are relatively moved from the intermediate position to the transmission position (in other words, the movement amount or the press-in amount of the main shaft 3 until the power transmission mechanism 4 is transferred from the cut-off state to the transmittable state during the screw loosening operation) is smaller than the movement distance until the gear sleeve 47, the holder 43, and the roller 45 are relatively moved from the farthest position to the transmission position (the movement amount or the press-in amount of the main shaft 3 until the power transmission mechanism 4 is transferred from the cut-off state to the transmittable state during the screw tightening operation). In the present embodiment, the moving distance during the screw loosening operation is set to be shorter than the moving distance of the spindle 3 during the screw tightening operation by about 1 mm. Accordingly, the user can unscrew the screw 90 screwed into the workpiece 900 without removing the retainer 15 from the front housing 13.

In the above description, the operation in the case where the main shaft 3 is pushed backward after the motor 2 is started to be driven has been described, but the operation in the case where the motor 2 is started to be driven before the main shaft 3 is pushed backward and the power transmission mechanism 4 shifts to the transmission-enabled state is basically the same. In addition, in the case of the screw loosening operation, depending on the position of the main shaft 3, the gear sleeve 47 may be moved rearward by the position switching mechanism 5 in response to the start of driving of the motor 2, and the power transmission mechanism 4 may be shifted to the transmission state. When the main shaft 3 is pushed backward and the power transmission mechanism 4 is shifted to a transmission-enabled state and then the motor 2 is started to be driven, the rotation driving of the main shaft 3 is started in response to the start of the driving of the motor 2.

As described above, in the power transmission mechanism 4 of the electric screwdriver 1 according to the present embodiment, the rotational force is transmitted from the gear sleeve 47 to the holder 43 through the rollers 45 in both the case where the gear sleeve 47 is rotationally driven in the forward direction in response to the screw tightening operation and the case where the gear sleeve 47 is rotationally driven in the reverse direction in response to the screw loosening operation. That is, the transmission of the power is performed through the same path during the screw tightening operation and the screw loosening operation. When the gear sleeve 47 is rotated in the reverse direction in a state where the main shaft 3 is located at the initial position in response to the screw loosening operation, the position switching mechanism 5 moves the gear sleeve 47 in a direction (rearward) toward the cage 43 and the roller 45. That is, even if the spindle 3 is not pushed backward during the screw loosening operation, the distance between the gear sleeve 47 and the retainer 43 and the distance between the gear sleeve 47 and the roller 45 in the front-rear direction are shortened in response to the gear sleeve 47 being rotationally driven in the reverse direction. Accordingly, the amount of movement (the amount of press-fitting) of the spindle 3 to move backward, which is required to shift the power transmission mechanism 4 to the transmittable state, can be set smaller than that in the screw fastening operation. As described above, according to the present embodiment, the power transmission mechanism 4 can transmit power through the same path during the screw tightening operation and the screw loosening operation, and can perform the screw loosening operation with a smaller pressing amount than during the screw tightening operation.

In the present embodiment, the position switching mechanism 5 is configured to convert the rotational motion around the drive shaft a1 into a linear motion in the front-rear direction in response to the gear sleeve 47 being rotationally driven in the reverse direction, and thereby move the gear sleeve 47 rearward with respect to the main shaft 3. That is, the position switching mechanism 5 is configured as a motion conversion mechanism. In particular, in the present embodiment, the gear sleeve 47 is configured to move rearward with respect to the main shaft 3 by moving the guide sleeve 500 by the action of the spiral guide groove 507 formed in the guide sleeve 500 and the balls 508 rolling in the guide groove 507. Accordingly, the position switching mechanism 5 can be operated smoothly.

In the present embodiment, only when the gear sleeve 47 is rotationally driven in the reverse direction, the one-way clutch 50 rotates the guide sleeve 500 around the drive shaft a1 integrally with the gear sleeve 47, and the position switching mechanism 5 moves the guide sleeve 500 rearward with respect to the main shaft 3, thereby moving the gear sleeve 47 rearward. In this way, the following reasonable configuration is realized in the present embodiment: the guide sleeve 500 is rapidly rotated in response to the gear sleeve 47 being rotationally driven in the reverse direction, thereby moving the gear sleeve 47.

In the present embodiment, the power transmission mechanism 4 is configured as a friction type clutch mechanism (specifically, a planetary roller type friction clutch mechanism). Therefore, compared to the case of using the clutch mechanism of the mesh engagement type, it is possible to reduce abnormal noise when the gear sleeve 47 engages with the roller 45 (at the time of frictional contact), and wear of the roller 45 or the tapered surfaces 411 and 475. Further, since the power transmission mechanism 4 is configured as a planetary reduction mechanism, two functions of power transmission, power transmission interruption, and speed reduction can be realized by a single structure. In addition, the gear sleeve 47 has gear teeth 470 that mesh with the pinion gear 24 provided on the motor shaft 23. This realizes a reasonable structure that can efficiently transmit the power from the motor 2 to the power transmission mechanism 4.

[ 2 nd embodiment ]

Next, an electric driver 100 according to embodiment 2 will be described with reference to fig. 15 to 19. The electric 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 fig. 5 to 7) of embodiment 1, but the other configurations are substantially the same as those of the electric screwdriver 1. Therefore, the same reference numerals are given to the same components as those of embodiment 1 to omit or simplify the description, and different components will be mainly described below.

As shown in fig. 15 to 17, the power transmission mechanism 6 of the present embodiment is mainly configured by a planetary mechanism including a taper sleeve 41, a retainer 43, a plurality of rollers 45, and a gear sleeve 67, which are coaxially arranged. The structure of the power transmission mechanism 6 other than the gear sleeve 67 is substantially the same as that of the power transmission mechanism 4 of embodiment 1.

The gear sleeve 67 of the present 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 has the same configuration as the gear sleeve 47 of embodiment 1 except for the configuration of the distal end portion of the gear sleeve 67. More specifically, the gear sleeve 67 includes: a bottom wall 671 having a through hole; and a peripheral wall 674 which is cylindrical and connected to the bottom wall 671. The gear sleeve 67 is supported by the spindle 3 at a position forward of the holder 43 so as to be rotatable with respect to the spindle 3 and movable in the forward and backward directions. In the inner space of the gear sleeve 67, the biasing spring 49 and the tapered sleeve 41, the retainer 43, and a part of the roller 45 are arranged. Further, gear teeth 670 that constantly mesh with the pinion gear 24 are integrally formed on the outer periphery of the gear sleeve 67 (specifically, the peripheral wall 674). Like the peripheral wall 474 of the embodiment 1, the inner peripheral surface of the peripheral wall 674 includes a tapered surface 675, and the tapered surface 675 is inclined with respect to the drive shaft a1 at the same angle as the tapered surface 411 of the tapered sleeve 41 (i.e., parallel to the tapered surface 411).

The gear sleeve 67 of the present embodiment has a guide groove 707 formed in a front end portion (specifically, a front end surface of the bottom wall 671), unlike the gear sleeve 47 of embodiment 1. The guide groove 707 has the same structure as the guide groove 507 of the guide sleeve 500 of embodiment 1. That is, the guide groove 707 is formed as a spiral groove (strictly speaking, a groove having a shape corresponding to a part of a spiral). The guide grooves 707 are provided with 3 strips away from each other and equally spaced in the circumferential direction. The depth of the guide groove 707 in the front-rear direction from the front end surface decreases from the upstream side to the downstream side in the forward direction (screw tightening direction) of the gear sleeve 67 indicated by an arrow a in fig. 17 (increases from the upstream side to the downstream side in the reverse direction (screw loosening direction) of the gear sleeve 67 indicated by an arrow B in fig. 17).

The position switching mechanism 7 of the present embodiment is configured to relatively move the gear sleeve 67 and the tip end portion of the main shaft 3 in the forward and backward direction in a direction away from each other when the gear sleeve 67 is rotationally driven in the reverse direction (screw loosening direction) as in the position switching mechanism 5 of embodiment 1. According to this configuration, when the gear sleeve 67 is rotationally driven in the reverse direction (screw loosening direction) in a state where the main shaft 3 is disposed at the initial position, the position switching mechanism 7 moves the gear sleeve 67 rearward with respect to the main shaft 3, and approaches the retainer 43 and the roller 45.

As shown in fig. 15 to 17, in the present embodiment, the position switching mechanism 7 is mainly configured by the one-way clutch 70, a flange sleeve (flange sleeve)700, a guide groove 707 formed in the gear sleeve 67, and balls 708.

In the present embodiment, a known general-purpose one-way clutch is used as the one-way clutch 70. The one-way clutch 70 is formed in a cylindrical shape and is externally attached to the rear shaft 32 on the rear side of the flange 34 of the main shaft 3. The one-way clutch 70 is configured to be rotatable in the forward direction and not rotatable in the reverse direction with respect to the main shaft 3. The flange sleeve 700 includes a cylindrical peripheral wall 701 and a flange 703 projecting radially outward from a distal end of the peripheral wall 701. An annular recess against which the balls 708 abut is formed in an outer edge portion of the rear surface of the flange 703. The peripheral wall 701 is fixed to the outer periphery of the one-way clutch 70. In the front-rear direction, a thrust bearing (specifically, a thrust ball bearing)53 is disposed between the rear surface of the flange 34 of the main shaft 3 and the front surface of the flange 703 of the flange sleeve 700. The thrust bearing 53 receives a thrust load while allowing the flange sleeve 700 to rotate with respect to the main shaft 3. Further, annular recesses having a U-shaped cross section are formed in the rear surface of the flange 34 and the front surface of the flange 703, respectively. Balls as rolling elements of the thrust bearing 53 can roll in a circular orbit defined by the concave portions.

The guide groove 707 and the balls 708 are configured to move the gear sleeve 67 relative to the main shaft 3 in the forward and backward direction as the gear sleeve 67 rotates about the drive shaft a1 with respect to the flange sleeve 700, and thereby move the gear sleeve 67 relative to the cage 43 and the rollers 45 in the forward and backward direction. As described above, in the present embodiment, the guide groove 707 is formed in the front end surface of the bottom wall 671 of the gear sleeve 67. A steel ball 708 is disposed in each guide groove 707.

As described above, the gear sleeve 67 is always biased forward by the biasing spring 49 disposed between the holder 43 and the gear sleeve 67 (more specifically, the bearing 48). Therefore, as shown in fig. 15 and 16, the main shaft 3 is also biased forward by the balls 708, the flange sleeve 700, and the thrust bearing 53, and is normally held at the initial position.

According to this structure, the relative positional relationship between the main shaft 3 and the flange sleeve 700 and the gear sleeve 67 in the front-rear direction changes in accordance with the position of the balls 708 in the guide grooves 707. More specifically, as shown in fig. 15 and 16, when the balls 708 are disposed at the deepest portion (i.e., the upstream end portion in the positive direction) of the guide groove 707, the distance between the flange 703 and the gear sleeve 67 in the front-rear direction is smallest. That is, the gear sleeve 67 is disposed at the foremost position within the movable range with respect to the spindle 3. In the state where the spindle 3 is arranged at the initial position, the gear sleeve 67 is arranged at the farthest position from the retainer 43 and the rollers 45 in the front-rear direction.

At this time, the balls 708 disposed in the guide grooves 707 are pressed by the biasing force of the biasing springs 49 and engaged with annular recesses formed in the outer edge portion of the rear surface of the flange 703. As described above, the one-way clutch 70 and the flange sleeve 700 can rotate in the forward direction with respect to the main shaft 3. Therefore, when the gear sleeve 67 is rotationally driven in the forward direction, the flange sleeve 700 rotates in the forward direction together with the gear sleeve 67 due to the frictional force between the flange 703 and the balls 708 held in the deepest portion of the guide groove 707. That is, when the gear sleeve 67 is rotationally driven in the forward direction, the one-way clutch 70 allows the flange sleeve 700 to rotate integrally with the gear sleeve 67.

On the other hand, as described above, the one-way clutch 70 cannot rotate in the reverse direction with respect to the main shaft 3. Therefore, when the gear sleeve 67 is driven to rotate in the reverse direction, the flange sleeve 700 is inhibited from rotating in the reverse direction with respect to the main shaft 3 by the one-way clutch 70. Namely, the flange bushing 700 is integrated with the main shaft 3. Therefore, the gear sleeve 67 is relatively rotated in the reverse direction with respect to the flange sleeve 700. Along with this, the balls 708 move relatively from the deepest portion of the guide groove 707 to the shallowest portion (upstream side in the opposite direction). Since the balls 708 come into contact with the rear surface of the flange 703, the gear sleeve 67 moves in a direction away from the flange 703 (rearward with respect to the spindle 3), that is, in a direction approaching the cage 43 and the rollers 45 against the biasing force of the biasing spring 49 while rotating in the reverse direction in response to the relative movement of the balls 708, as shown in fig. 18 and 19. When the balls 708 are arranged at the shallowest portion, the distance between the flange 703 and the gear sleeve 67 in the front-rear direction is the largest. In the state where the spindle 3 is arranged at the initial position, the gear sleeve 67 is arranged at a position closer to the intermediate position between the retainer 43 and the roller 45 than the case where it is arranged at the farthest position. That is, the relative positions of the gear sleeve 67, the holder 43, and the roller 45 are switched from the farthest position to the intermediate position.

As described above, in the electric screwdriver 100 according to the present embodiment, when the gear sleeve 67 is rotationally driven in the reverse direction in a state where the spindle 3 is at the initial position in response to the screw loosening operation, the position switching mechanism 7 moves the gear sleeve 67 in a direction (rearward) to approach the holder 43 and the roller 45. That is, even if the spindle 3 is not pushed backward during the screw loosening operation, the distance between the gear sleeve 67 and the retainer 43 in the front-rear direction and the distance between the gear sleeve 67 and the roller 45 in the front-rear direction are shortened in response to the gear sleeve 67 being rotationally driven in the reverse direction. Accordingly, the amount of movement (the amount of press-fitting) of the spindle 3 to move backward, which is required to shift the power transmission mechanism 6 to the transmittable state, can be set smaller than that in the screw fastening operation.

In the present embodiment, the position switching mechanism 7 is configured as a motion conversion mechanism that converts a rotational motion around the drive shaft a1 into a linear motion in the front-rear direction in response to the gear sleeve 67 being rotationally driven in the reverse direction, and thereby moves the gear sleeve 67 rearward relative to the main shaft 3. In particular, the following structure is adopted in the present embodiment: the gear sleeve 67 is moved rearward relative to the main shaft 3 by the spiral guide groove 707 formed in the gear sleeve 67 and the balls 708 rolling in the guide groove 707. This realizes the position switching mechanism 7 that operates smoothly. In the present embodiment, when the gear sleeve 67 is driven to rotate in the reverse direction, the one-way clutch 70 prohibits the flange sleeve 700 from rotating relative to the main shaft 3 in the reverse direction (integrates the flange sleeve 700 with the main shaft 3), and the position switching mechanism 7 rotates the gear sleeve 67 relative to the flange sleeve 700, thereby moving the gear sleeve 67 rearward relative to the main shaft 3. In this way, in the present embodiment, an appropriate configuration is achieved in which the gear sleeve 67 is quickly moved in the front-rear direction in response to the gear sleeve 67 being rotationally driven in the reverse direction.

[ embodiment 3]

Next, the electric driver 110 according to embodiment 3 will be described with reference to fig. 20 to 23. The electric driver 110 of the present embodiment includes a power transmission mechanism 8 different from the electric driver 100 of embodiment 2 (see fig. 15 to 17), but the configuration other than the power transmission mechanism 8 is substantially the same as the electric driver 100. Therefore, the same reference numerals are used to omit or simplify the description of the structure substantially the same as that of the electric driver 100, and the description of the different structure will be mainly made below.

As shown in fig. 20 to 22, the power transmission mechanism 8 of the present embodiment is mainly configured by a planetary mechanism including a taper sleeve 41, a holder 83, a plurality of rollers 45, and a gear sleeve 87, which are coaxially arranged. The power transmission mechanism 8 other than the holder 83 and the gear sleeve 87 has substantially the same configuration as the power transmission mechanism 6 (see fig. 15 to 17).

The cage 83 of the present embodiment corresponds to a carrier member in the planetary mechanism, and is configured to rotatably hold the rollers 45, as in the cage 43 of embodiment 2 (see fig. 15 to 17). The holder 83 has the same structure as the holder 43 except for the structure of the tip end portion. More specifically, the holder 83 includes: a bottom wall 831 having a substantially cylindrical shape and a through hole in a central portion thereof; a flange portion 832 having a ring shape and protruding radially outward from a front end portion of the bottom wall 831; and a plurality of holding arms 834 projecting rearward from a rear surface of a peripheral portion of the flange portion 832. The bottom wall 831 and the holding arm 834 have substantially the same structure as the bottom wall 431 and the holding arm 434 of the holder 43. According to this structure, the front ends of the holding spaces of the rollers 45 formed between the circumferentially adjacent holding arms 45 are closed by the flange portions 832. In the present embodiment, instead of omitting the spacer 491 (see fig. 15 to 17), the front surface of the flange portion 832 functions as a spring seat portion that receives a rearward biasing force of the biasing spring 49. The rear surface of the flange portion 832 abuts against the front end of the roller 45, and functions as a restricting surface for restricting the forward movement of the roller 45.

The retainer 83 is disposed in a direction in which the bottom wall 831 is located on the front side (so that the retaining arm 834 protrudes rearward), similarly to the retainer 43. The holder 83 is supported by the spindle 3 so as to be non-rotatable with respect to the spindle 3 and movable in the forward and backward directions in a state where a part of the holding arm 834 overlaps the taper sleeve 41 in the radial direction. Each of the retaining arms 834 protrudes rearward from the rear surface of the peripheral edge portion of the flange portion 832 so as to have the same inclination angle as the tapered surface 411 of the tapered sleeve 41 with respect to the drive shaft a 1.

The gear hub 87 of the present embodiment is configured as a substantially cup-shaped member having substantially the same configuration as the gear hub 67 (see fig. 15 to 17) of embodiment 2. More specifically, the gear sleeve 87 includes: a bottom wall 871 having a substantially circular shape and a through hole in a central portion thereof; a peripheral wall 874, which is cylindrical, is connected to the bottom wall 871. Additionally, the bottom wall 871 has substantially the same result as the bottom wall 671 of the gear sleeve 67. The peripheral wall 874 has the same basic structure as the peripheral wall 674 of the gear sleeve 67 except for having a communication hole 878 described later. Specifically, the outer race 481 of the bearing 48 is fixed to the front end portion of the peripheral wall 874. Further, gear teeth 870 that constantly mesh with the pinion gear 24 are integrally formed on the outer periphery of the gear sleeve 87 (specifically, the peripheral wall 874).

As shown in fig. 23, the inner peripheral surface of the peripheral wall 874 includes a tapered surface 875 and a cylindrical surface 876 at a portion rearward of the rear end of the bearing 48. The tapered surface 875 is a conical surface inclined with respect to the drive shaft a1 at the same angle as the tapered surface 411 of the tapered sleeve 41. The tapered surface 875 occupies the rear half of the inner peripheral surface of the peripheral wall 874. A cylindrical surface 876 is attached to the forward end of the tapered surface 875 and extends generally cylindrically along the drive axis a 1.

The communication hole 878 is a through hole penetrating the peripheral wall 874 in the radial direction, and communicates the inside (inner space) and the outside of the gear sleeve 87. In the present embodiment, the communication hole 878 is provided in a region R3 corresponding to the cylindrical surface 876, which is a region different from the region R2 corresponding to the tapered surface 875, in the region R1 (i.e., the region defining the internal space of the gear sleeve 87) between the rear end of the peripheral wall 874 and the rear end of the bearing 48. In other words, the communication hole 878 is arranged in a region that does not normally overlap with the roller 45 in the radial direction. In the present embodiment, the 4 communication holes 878 are provided at equal intervals in the circumferential direction.

As shown in fig. 21 and 22, in the present embodiment, the gear sleeve 87 is also supported by the spindle 3 at a position forward of the holder 83 so as to be rotatable with respect to the spindle 3 and movable in the front-rear direction. Further, in the internal space of the gear sleeve 87, the taper sleeve 41, the retainer 83, a part of the roller 45, and the biasing spring 49 are arranged.

In the present embodiment, the small-diameter side end portion (front end portion) of the biasing spring 49 abuts against the pad 493, and the large-diameter side end portion (rear end portion) abuts against the front surface of the flange portion 832 of the retainer 83, wherein the pad 493 abuts against the inner ring 483 of the bearing 48. The biasing spring 49 always biases the holder 83 and the gear sleeve 87 in directions away from each other, that is, in the rear and front directions. Accordingly, the retainer 83 is held by the biasing force of the biasing spring 49 at a position where the rear surface of the bottom wall 831 abuts on the front end surface of the tapered sleeve 41, and is restricted from moving in the front-rear direction. 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 is restricted from moving in the front-rear direction. As described in embodiment 1, the term "restricting movement" herein does not mean that movement is completely prohibited, and may allow slight movement. Further, the gear sleeve 87 is biased forward by the biasing force of the biasing spring 49, so that the spindle 3 is also biased forward and held at the initial position.

The operation of the power transmission mechanism 8 configured as described above is substantially the same as the power transmission mechanisms 4 and 6 according to embodiments 1 and 2. Specifically, in the initial state, the spindle 3 is disposed at the initial position by the biasing force of the biasing spring 49, and the rollers 45 are in a non-frictional contact state with the tapered surface 411 of the tapered sleeve 41 and the tapered surface 875 of the gear sleeve 87. That is, the power transmission mechanism 8 is in the disengaged state. After that, as the spindle 3 is pushed rearward against the biasing force of the biasing spring 49, the gear sleeve 87 approaches the taper sleeve 41, the holder 83, and the roller 45. The rollers 45 held by the retainer 83 are sandwiched between the tapered surface 411 and the tapered surface 875, and are in a frictional contact state. Accordingly, the power transmission mechanism 8 can be shifted from the disengaged state to the transmittable state.

As described above, the electric screwdrivers 1, 100, 110 according to embodiments 1 to 3 described above have the so-called planetary roller type power transmission mechanisms 4, 6, 8, respectively. In the power transmission mechanisms 4, 6, and 8, at least a part of the planetary roller 45 is disposed between the tapered surface 411 of the tapered sleeve 41 as the sun member and the tapered surfaces 475, 675, and 875 of the gear sleeves 47, 67, and 87 as the ring members in the radial direction (direction orthogonal to the drive shaft a1) of the main shaft 3 with respect to the drive shaft a 1. The gear sleeves 47, 67, 87 move in the front-rear direction integrally with the main shaft 3 with respect to the taper sleeve 41. On the other hand, the roller 45 is restricted from moving in the front-rear direction with respect to the main body housing 11 by the biasing spring 49 (and the spacer 491 or the holder 83). Therefore, the roller 45 moves in the front-rear direction in association with the relative movement of the gear sleeves 47, 67, 87 and the taper sleeve 41, and the possibility that the frictional contact between the roller 45 and the taper surface 411 and the taper surfaces 475, 675, 875 becomes unstable can be reduced. In embodiment 3, the movement of the rollers 45 in the front-rear direction is restricted by the retainer 83 without using the spacers 491. Accordingly, the number of parts can be reduced, and the assembling property can be improved.

In addition, in the above-described embodiments 1 to 3, the retainers 43, 83 as the carrier members are held by the main shaft 3 so as to be movable in the front-rear direction with respect to the main shaft 3. In other words, the retainers 43, 83 are independent of the spindle 3 with respect to the movement in the front-rear direction. The retainers 43, 83 need to be arranged in positions that keep the rollers 45 from disengaging from between the tapered surface 411 and the tapered surfaces 475, 675, 875. In contrast, in the above embodiment, the retainers 43 and 83 can be held at appropriate positions regardless of the movement of the spindle 3. Accordingly, compared to a structure in which the retainers 43 and 83 and the spindle 3 are moved in the front-rear direction integrally, the restriction on the amount of movement of the spindle 3 in the front-rear direction can be reduced. In particular, when the rollers 45, the tapered surfaces 411, 475, 675, 875 wear, the spindle 3 needs to be pressed into a position where the tapered sleeve 41 and the gear sleeves 47, 67, 87 are closer to each other (i.e., more rearward) in order to establish stable frictional contact. That is, it is necessary to increase the amount of movement of the main shaft 3 in the front-rear direction, but this need can be met by the power transmission mechanisms 4, 6, and 8 according to the above embodiments.

In the above-described embodiments 1 to 3, the retainers 43 and 83 are held by the main shaft 3 so as to be unrotatable about the drive shaft a1, and are configured to rotate integrally with the main shaft 3 by the power transmitted via the rollers 45. That is, in the above embodiment, the planetary roller type power transmission mechanisms 4, 6, and 8 having the retainers 43 and 83 as output members are realized.

In addition, in the above-described embodiments 1 to 3, the biasing spring 49 restricts the movement of the retainers 43 and 83 in the front-rear direction with respect to the main body housing 11 in addition to the movement of the roller 45. This makes it possible to more reliably maintain the proper positional relationship between the roller 45 and the retainers 43 and 83. In the above embodiment, the biasing spring 49 biases the spindle 3 and the retainers 43 and 83 forward and backward, respectively, so as to be spaced apart from each other. And, the spindle 3 is normally held at the most forward position (i.e., the initial position) by the urging force of the urging spring 49. With this configuration, when the movement of the retainers 43 and 83 is restricted and the pushing of the spindle 3 is released, the spindle 3 can be returned to the initial position.

In the above-described embodiments 1 to 3, the gear sleeves 47, 67, 87 are supported by the main shaft 3 so as to be movable in the front-rear direction integrally with the main shaft 3 and rotatable about the drive shaft a 1. The biasing spring 49 is disposed between the retainers 43, 83 and the gear sleeves 47, 67, 87 (more specifically, the biasing spring is disposed in the bearings 48 in the gear sleeves 47, 67, 87) in the front-rear direction, but the end portions on the gear sleeves 47, 67, 87 side are received by spacers 493, which do not rotate with the rotation of the gear sleeves 47, 67, 87. Therefore, the biasing spring 49 can be prevented from rotating together with the gear sleeves 47, 67, 87 (so-called co-rotation), or heat generation at the sliding portions of the biasing spring 49 and the gear sleeves 47, 67, 87 can be prevented.

In the above embodiments 1 to 3, the biasing spring 49 biases the gear sleeves 47, 67, 87 and the retainers 43, 83 rearward and forward so as to be apart from each other. In other words, the biasing spring 49 also has a function of biasing the gear sleeves 47, 67, 87 serving as the driving-side members and the retainers 43, 83 serving as the driven-side members in the power transmission mechanisms 4, 6, 8 in the direction of interrupting transmission. Thus, by using the biasing spring 49, it is possible to realize a plurality of functions such as restriction of movement of the retainers 43, 83 in the front-rear direction and interruption of power transmission without increasing the number of components.

In the above-described embodiment 3, the peripheral wall 874 of the gear sleeve 87 is provided with the communication hole 878 for communicating the inside and the outside of the gear sleeve 87. Therefore, the air flow can be generated through the communication hole 878 by the centrifugal force generated by the rotation of the gear sleeve 87. This can suppress a local temperature rise and achieve smooth 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. Even when abrasion powder is generated, the abrasion powder can be efficiently discharged to the outside of the gear sleeve 87 through the communication hole 878 in association with the flow of air, and therefore the bearing 48 can be protected.

The above embodiments are merely examples, and the power tool according to the present invention is not limited to the configuration of the illustrated electric screwdriver 1, 100, 110. For example, the variations exemplified below can be added. Any one or more of these modifications may be used independently or in combination with the electric screwdriver 1, 100, or 110 described in the embodiments or the claims.

In the above-described embodiments, the electric screwdrivers 1, 100, and 110 as the screw tightening tool are exemplified, but the present invention can be applied to other working tools configured to rotationally drive the tip tool. For example, the present invention can be applied to a punching tool (e.g., an electric drill) for performing a punching operation by rotationally driving a drill, a polishing tool (e.g., an electric sander) for performing a polishing operation by rotationally driving a polishing member (e.g., sandpaper), and the like.

In the power transmission mechanisms 4, 6, and 8 as the friction clutch mechanisms of the planetary roller type, the configurations and arrangements of the sun member, the ring member, the carrier member, and the planetary rollers may be appropriately changed. For example, the power transmission mechanisms 4, 6, and 8 may have a so-called planetary gear type in which a ring member is fixed or a so-called carrier type in which a carrier member is fixed, without having a so-called sun type in which a sun member is fixed to the main body case 11 so as not to be rotatable as in the above-described embodiments. In addition, although the above embodiment is a configuration example in which the gear sleeves 47, 67, 87 as the ring members are moved in the front-rear direction with respect to the tapered sleeve 41 as the sun member, any one of the sun member and the ring members may be moved integrally with the main shaft 3 as long as it has tapered surfaces parallel to each other and inclined with respect to the drive shaft a1 and is relatively movable in the front-rear direction. Further, one of the sun member and the ring member that moves integrally with the main shaft 3 may be formed integrally with the main shaft 3 as an output member.

In the above embodiment, the biasing spring 49 has a function of restricting the movement of the roller 45 as the planetary member in the front-rear direction, a function of biasing the main shaft 3 to the initial position, and a function of biasing the gear sleeve 47, 67, 87 as the driving-side member and the holder 43, 83 as the driven-side member in the power transmission mechanisms 4, 6, 8 in the direction of cutting off the power transmission, in addition to a function of restricting the movement of the holder 43 as the planetary member in the front-rear direction. That is, the single urging spring 49 serves a plurality of functions. However, these functions may be realized by different members (for example, spring members), respectively.

When the communication holes 878 are provided, the number, arrangement position, shape, size, and the like thereof are not limited to those in embodiment 3, and may be appropriately changed. For example, at least 1 communication hole 878 may be provided at any position in a region R1 (see fig. 23) from the rear end of the peripheral wall 874 to the rear end of the bearing 48. The communication hole 878 may extend obliquely with respect to the radial direction, or may extend not linearly but curvedly.

The structure of the main body case 11, the motor 2, the main shaft 3, and the position switching mechanisms 5 and 7 can be appropriately modified in addition to the power transmission mechanisms 4, 6, and 8. For example, the motor 2 may be a dc brushless motor using a rechargeable battery as a power source. The position switching mechanisms 5 and 7 may be omitted.

The following shows the correspondence between each component of the above-described embodiment and modification and each component of the present invention. The electric screwdrivers 1, 100, and 110 are examples of the "power tool" of the present invention. The driver bit 9 is an example of the "tip tool" of the present invention. The main body case 11 is an example of the "case" 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. The gear sleeves 47, 67, 87 are examples of "ring members" of the present invention. The cages 43 and 83 are an example of the "carrier member" of the present invention. The roller 45 is an example of the "planetary roller" of the present invention. The tapered surface 411 is an example of the "1 st tapered surface" of the present invention. The tapered surfaces 475, 675, 875 are examples of the "2 nd tapered surface" of the present invention. The biasing spring 49 is an example of the "regulating member" and the "spring member" in the present invention. The spacer 493 is an example of a "receiving member" according to 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 2 nd tapered surface" in the present invention. The region R3 is an example of the "region different from the region corresponding to the 2 nd tapered surface" in the present invention.

In view of the gist of the present invention and the above-described embodiments, the following structure (embodiment) is constructed. Any one or more of the following configurations can be used in combination with the electric screwdrivers 1, 100, and 110 and the modifications thereof of the embodiments or the claims.

[ means 1]

Can be as follows:

the annular member has a peripheral wall in a cylindrical shape surrounding the main shaft in a circumferential direction around the drive shaft and having an inner peripheral surface including the 2 nd taper surface,

at least a part of the carrier member is disposed in an inner space of the ring member defined by the main shaft and the inner peripheral surface,

the spring member is disposed in the internal space on a front side of the carrier member.

According to this aspect, the spring member can be disposed by effectively using the internal space of the annular member, and the power transmission mechanism can be kept compact.

[ means 2]

In the mode 1, it may be:

the ring member has a stopper portion disposed on a front side of the spring member,

the spring member is interposed between the carrier member and the stopper portion in the front-rear direction.

[ means 3]

In the mode 2, the following may be used:

the stopper portion is a bearing having an inner ring and an outer ring, wherein the inner ring is rotatably supported by the main shaft; the outer ring is 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. The bearing 48 is an example of the "stopper portion" and the "bearing" in the embodiments 1 and 2.

[ means 4]

Can be as follows: the annular member has a cylindrical peripheral wall portion centered on the drive shaft,

the communication hole is a through hole penetrating the peripheral wall portion.

[ means 5]

Can be as follows: the inner peripheral surface of the annular member includes the 2 nd taper surface and a cylindrical surface along the drive shaft,

the communication hole is provided in a region of the annular member corresponding to the cylindrical surface.

In view of the gist of the above-described embodiment, the following embodiments 6 to 19 are constructed with the object of providing a screw fastening tool having a power transmission mechanism with a more rational structure. Any one or more of the embodiments 6 to 19 may be used independently of the claims, or may be used in combination with the electric screwdrivers 1, 100, and 110 and the modifications thereof of the embodiments, or the claims.

[ means 6]

A screw tightening tool, characterized in that,

has a main shaft, a motor and a power transmission mechanism, wherein,

a spindle supported to be movable in a front-rear direction along a predetermined drive shaft extending in a front-rear direction of the screw tightening tool and rotatable about the drive shaft, and having a front end portion configured as a detachable tip tool;

the power transmission mechanism includes a driving member and a driven member, wherein the driving member is rotationally driven in a1 st direction or a 2 nd direction by power transmitted from the motor, the 1 st direction is a direction corresponding to a direction in which the tip tool fastens a screw, and the 2 nd direction is a direction opposite to the 1 st direction and corresponds to a direction in which the tip tool unscrews the screw; the driven member is configured to rotate around the drive shaft integrally with the main shaft by the power transmitted from the driving member rotating in the 1 st direction or the 2 nd direction,

the driving member and the driven member are arranged to be relatively movable in the front-rear direction, and are configured to move in a direction approaching each other in the front-rear direction in response to a backward movement of the main shaft, and to shift from a blocked state in which power transmission from the driving member to the driven member is disabled to a transmittable state in which power transmission from the driving member to the driven member is enabled,

the screw tightening tool includes a position switching mechanism configured to move one of the driving member and the driven member in the front-rear direction in a direction approaching the other of the driving member and the driven member when the driving member is rotationally driven in the 2 nd direction with the main shaft located at a foremost position.

In the power transmission mechanism of the screw tightening tool of this aspect, the rotational force is transmitted from the driving member to the driven member in both the case where the driving member is rotationally driven in the 1 st direction in response to the screw tightening operation and the case where the driving member is rotationally driven in the 2 nd direction in response to the screw loosening operation. That is, the transmission of the power is performed through the same path during the screw tightening operation and the screw loosening operation. When the driving member is driven to rotate in the 2 nd direction in accordance with the screw loosening operation with the main shaft located at the foremost position, the position switching mechanism moves one of the driving member and the driven member in the front-rear direction in a direction approaching the other of the driving member and the driven member. That is, even if the main shaft is not pushed backward during the unscrewing operation, the distance between the driving member and the driven member in the front-rear direction is shortened in response to the driving member being rotationally driven in the 2 nd direction. Accordingly, the amount of movement (press-in amount) of the spindle to move backward, which is required to shift the power transmission mechanism to the transmittable state, can be set smaller than that in the screw fastening operation. As described above, according to this aspect, it is possible to realize a rational power transmission mechanism that can transmit power through the same path during the screw tightening operation and the screw loosening operation and can perform the screw loosening operation with a smaller pushing amount than during the screw tightening operation.

The electric screwdrivers 1, 100, and 110 of the above embodiments are examples of the "screw fastening tool" of the present embodiment. The spindle 3 is an example of the "spindle" of the present embodiment. The drive shaft a1 is an example of the "drive shaft" of the present embodiment. The motor 2 is an example of the "motor" of the present embodiment. The power transmission mechanisms 4, 6, and 8 are examples of the "power transmission mechanism" of the present embodiment. The gear sleeves 47, 67, and 87 are examples of the "driving member" of the present embodiment. The retainers 43, 83 and the rollers 45 are all an example of the "driven member" of the present embodiment, and the retainers 43, 83 and the rollers 45 are also an example of the "driven member" of the present embodiment. The position switching mechanisms 5 and 7 are examples of the "position switching mechanism" of the present embodiment.

Note that, instead of the planetary roller type friction clutch mechanism, a mesh type clutch mechanism or another type of friction clutch mechanism may be employed as the power transmission mechanisms 4, 6, and 8. For example, a single-plate or multi-plate type disc clutch mechanism or a cone clutch mechanism may be employed. In the power transmission mechanisms 4, 6, and 8 as the planetary roller type friction clutch mechanisms, the configurations and arrangements of the sun member, the ring member, the carrier member, and the planetary rollers may be appropriately changed. For example, the power transmission mechanisms 4, 6, and 8 may have a so-called planetary gear type in which a ring member is fixed or a so-called carrier type in which a carrier member is fixed, without having a so-called sun type in which a sun member is fixed to the main body case 11 so as not to be rotatable as in the above-described embodiments. In response to the change of the power transmission mechanisms 4 and 6, a driving member (input member) driven by the power of the motor 2 and a driven member (output member) rotated integrally with the main shaft 3 by the power transmitted from the driving member can be changed. When the gear sleeve 47 is rotationally driven in the reverse direction in a state where the main shaft 3 is at the initial position, the position switching mechanisms 5 and 7 may move either the driving member or the driven member relative to the main shaft 3, as long as one of the driving member and the driven member can be moved in a direction approaching the other in the front-rear direction.

[ means 7]

The screw tightening tool according to mode 6, characterized in that,

the position switching mechanism is configured to move the one of the driving member and the driven member by converting a rotational motion around the driving shaft into a linear motion in the front-rear direction in response to the driving member being rotationally driven in the 2 nd direction.

According to this aspect, the position switching mechanism is configured as a motion conversion mechanism. According to this aspect, one of the driving member and the driven member can be moved with a simple configuration.

[ means 8]

The screw tightening tool according to mode 7, characterized in that,

the position switching mechanism is configured to drive the one of the driving member and the driven member by an action of a guide groove extending spirally around the driving shaft and a ball; the ball is disposed in the guide groove.

According to this aspect, the position switching mechanism can be operated smoothly by the rolling balls. The guide grooves 507 and 707 are examples of "guide grooves" in the present embodiment, and the balls 508 and 708 are examples of "balls" in the present embodiment.

The structure for converting rotational motion into linear motion in response to the rotational motion of the driving member (the gear sleeve 47, 67, 87 of the above embodiment) in the opposite direction is not limited to the guide grooves 507, 707 and the balls 508, 708 of the above embodiment. For example, the driving member may be moved by the action of a guide surface configured as a spiral curved surface around the drive shaft a1, a screw groove, and a screw thread engaged with the screw groove. For example, in embodiment 1, a guide surface having a spiral curved shape around the drive shaft a1 may be provided on at least one of the front end surface of the guide sleeve 500 and the rear end surface of the flange 34 of the main shaft 3. The same modification can be made in embodiment 2. The number and structure of the guide grooves 507 and 707 and the balls 508 and 708 may be appropriately changed. The configuration of the one-way clutch 50 according to embodiment 1 may be appropriately modified so long as the guide sleeve 500 and the gear sleeve 47 are rotated integrally only when the gear sleeve 47 is driven to rotate in the reverse direction. Similarly, the configuration of the one-way clutch 70 according to embodiment 2 may be appropriately modified so long as the flange sleeve 700 is prohibited from rotating together with the gear sleeve 67 only when the gear sleeve 67 is rotationally driven in the reverse direction.

[ means 9]

The screw tightening tool according to mode 7 or 8, characterized in that,

the position switching mechanism includes a moving member and a one-way clutch, wherein,

the moving member is configured to move the driving member in a direction approaching the driven member in the front-rear direction by rotating about the driving shaft;

the one-way clutch is configured to rotate the moving member around the drive shaft integrally with the drive member only when the drive member is rotationally driven in the 2 nd direction.

According to this aspect, an appropriate configuration can be achieved in which the driving member is moved by rotating the moving member quickly in response to the driving member being rotationally driven in the 2 nd direction. The guide sleeve 500 and the one-way clutch 50 are examples of the "moving member" and the "one-way clutch" in the present embodiment, respectively.

[ means 10]

The screw tightening tool according to mode 7 or 8, characterized in that,

the position switching mechanism includes a rotatable member and a one-way clutch, wherein,

the rotatable member is configured to be rotatable about the drive shaft;

the one-way clutch is configured to permit the rotatable member to rotate around the drive shaft integrally with the drive member relative to the spindle when the drive member is rotationally driven in the 1 st direction, and to prohibit the rotatable member from rotating around the drive shaft relative to the spindle when the drive member is rotationally driven in the 2 nd direction,

the position switching mechanism is configured to move the driving member, which is prevented from moving in the 2 nd direction relative to the rotatable member, which is prevented from rotating relative to the main shaft by the one-way clutch, in a direction to approach the driven member.

According to this aspect, an appropriate configuration can be achieved in which the driving member is driven to rotate in the 2 nd direction, and the driving member is quickly moved linearly in the front-rear direction. The flange sleeve 700 and the one-way clutch 70 are examples of the "rotatable member" and the "one-way clutch" in the present embodiment, respectively.

[ means 11]

A screw tightening tool, characterized in that,

has a main shaft, a motor and a power transmission mechanism, wherein,

a spindle supported to be movable in a front-rear direction along a predetermined drive shaft extending in a front-rear direction of the screw tightening tool and rotatable about the drive shaft, and having a front end portion configured as a detachable tip tool;

the power transmission mechanism includes a driving member and a driven member, wherein the driving member is rotationally driven in a1 st direction and a 2 nd direction by power transmitted from the motor, the 1 st direction is a direction corresponding to a direction in which the tip tool fastens a screw, and the 2 nd direction is a direction opposite to the 1 st direction and corresponds to a direction in which the tip tool unscrews the screw; the driven member is configured to rotate around the drive shaft integrally with the main shaft by the power transmitted from the driving member rotating in the 1 st direction or the 2 nd direction,

the driving member and the driven member are arranged to be relatively movable in the front-rear direction, and are configured to move in a direction approaching each other in the front-rear direction in response to a backward movement of the main shaft, and to shift from a blocked state in which power transmission from the driving member to the driven member is disabled to a transmittable state in which power transmission from the driving member to the driven member is enabled,

the power transmission mechanism is configured such that the amount of movement when the drive member is rotationally driven in the 2 nd direction is smaller than the amount of movement when the main shaft is moved rearward from the cut-off state to the transmittable state when the drive member is rotationally driven in the 1 st direction.

In the power transmission mechanism of the screw tightening tool of this aspect, the rotational force is transmitted from the driving member to the driven member regardless of whether the driving member is rotationally driven in the 1 st direction in response to the screw tightening operation or in the 2 nd direction in response to the screw loosening operation. That is, the transmission of the power is performed through the same path during the screw tightening operation and the screw loosening operation. The power transmission mechanism is configured such that the amount of movement (the amount of pressing) of the rearward movement of the main shaft required to shift the power transmission mechanism to the transmittable state during the screw loosening operation can be made smaller than during the screw tightening operation. As described above, according to this aspect, it is possible to realize a rational power transmission mechanism that can transmit power through the same path during the screw tightening operation and the screw loosening operation, and that can perform the screw loosening operation with a smaller pushing amount than during the screw tightening operation.

[ means 12]

The screw tightening tool according to any one of aspects 6 to 11, characterized in that,

the power transmission mechanism is configured as a friction clutch mechanism.

According to this aspect, noise and wear of the engagement portion when the driving member and the driven member are engaged can be reduced as compared with a mesh engagement type clutch mechanism.

[ means 13]

The screw tightening tool according to any one of aspects 6 to 12, characterized in that,

the power transmission mechanism is configured as a planetary reduction mechanism.

According to this aspect, the power transmission cutoff function, and the deceleration function can be achieved by the single power transmission mechanism.

[ means 14]

The screw tightening tool according to any one of aspects 6 to 13, characterized in that,

the driving part has 2 nd gear teeth, and the 2 nd gear teeth are meshed with 1 st gear teeth arranged on the output shaft of the motor.

According to this aspect, a reasonable structure for efficiently transmitting the power from the motor to the power transmission mechanism can be realized. The pinion gear 24 and the gear teeth 470 are examples of "1 st gear tooth" and "2 nd gear tooth", respectively.

[ means 15]

Can be as follows:

the main shaft has a protruding portion that protrudes in a radial direction with respect to the drive shaft,

the position switching mechanism includes a moving member supported by the main shaft on a rear side of the projection and on a front side of the driving member so as to be rotatable about the drive shaft and movable in the front-rear direction,

the screw tightening tool further includes a biasing member for biasing the moving member and the spindle forward by the driving member,

the moving member rotates in response to the driving member being rotationally driven in the 2 nd direction, and moves backward with respect to the main shaft against the biasing force of the biasing member, thereby moving the driving member backward with respect to the main shaft.

According to this aspect, the position switching mechanism having a simple configuration can be realized by using the moving member and the urging member. The flange 34 is an example of the "protruding portion" in the present embodiment. The guide sleeve 500 is an example of the "moving member" in the present embodiment. The biasing spring 49 is an example of a "biasing member" in the present embodiment.

[ means 16]

In the mode 15, the following may be used:

the position switching mechanism includes a guide groove and a ball, wherein,

the guide groove is formed on the front end surface of the moving component and extends spirally around the driving shaft;

the ball is disposed in the guide groove,

the moving member rotates in response to the rotational driving of the driving member in the 2 nd direction, and moves backward with respect to the main shaft by the guide groove and the balls.

[ means 17]

In the mode 15 or 16, there may be:

the position switching mechanism includes a one-way clutch configured to rotate the moving member around the drive shaft integrally with the drive member only when the drive member is rotationally driven in the 2 nd direction.

[ means 18]

Can be as follows: the rotatable member has a protruding portion protruding in a radial direction with respect to the drive shaft and disposed on a front side of the drive member,

the screw tightening tool further includes a biasing member for biasing the rotatable member and the spindle forward by the driving member,

the driving member is configured to move rearward relative to the rotatable member against the biasing force of the biasing member while rotating in the 2 nd direction.

According to this aspect, the position switching mechanism having a simple structure can be realized by using the rotatable member and the urging member. The flange 34 is an example of the "protruding portion" in the present embodiment. The guide sleeve 500 is an example of the "moving member" in the present embodiment. The biasing spring 49 is an example of a "biasing member" in the present embodiment.

[ means 19]

In the mode 18, the following may be used:

the position switching mechanism includes a guide groove and a ball, wherein,

the guide groove is formed on the front end surface of the driving part and extends spirally around the driving shaft,

the ball is disposed in the guide groove in a state of being in contact with a rear surface of the protruding portion,

the driving member is configured to move backward with respect to the main shaft by the guide groove and the balls while rotating in the 2 nd direction.

Description of the reference numerals

1. 100, and (2) a step of: an electric screwdriver; 10: a main body portion; 11: a main body housing; 12: a rear housing; 13: a front housing; 135: a limiting part; 14: a central housing; 141: a partition wall; 143: a base; 15: a positioner; 17: a handle portion; 171: a grip portion; 173: a trigger; 174: a master switch; 175: a switch lever; 176: a rotation direction switch; 178: a controller; 179: a power cable; 18: a handle housing; 2: a motor; 21: a rotor; 23: a motor shaft; 231: a bearing; 233: a bearing; 24: a pinion gear; 25: a fan; 3: a main shaft; 301: a bearing; 31: a front shaft; 311: a tool bit insertion hole; 32: a rear shaft; 321: a groove; 34: a flange; 36: a ball bearing; 4. 6: a power transmission mechanism; 41: a tapered sleeve; 411: a conical surface; 414: a recess; 43: a holder; 431: a bottom wall; 432: a recess; 434: a holding arm; 45: a roller; 47. 67: a gear sleeve; 470. 670: gear teeth; 471. 671: a bottom wall; 474. 674: a peripheral wall; 475. 675: a conical surface; 48: a bearing; 481: an outer ring; 483: an inner ring; 49: a force application spring; 491: a gasket; 493: a gasket; 5. 7: a position switching mechanism; 50. 70: a one-way clutch; 500: a guide sleeve; 501: a cam slot; 502: a ball bearing; 504: a peripheral wall; 505: a bottom wall; 507. 707: a guide groove; 508. 708: a ball bearing; 53: a thrust bearing; 700: a flange sleeve; 701: a peripheral wall; 703: a flange; 9: a screwdriver bit; 90: a screw; 900: a workpiece to be processed; a1: a drive shaft.

Claims (9)

1. A power tool configured to drive a tip tool to rotate,

the work tool is characterized in that the work tool is provided with a tool,

comprises a shell, a main shaft, a motor and a power transmission mechanism, wherein,

a spindle supported by the housing so as to be movable in a front-rear direction along a predetermined drive shaft extending in a front-rear direction of the work tool and rotatable about the drive shaft, the spindle having a tip end portion to which the tip tool is detachably attached;

the motor is accommodated in the housing;

the power transmission mechanism includes a sun member, a ring member, and a carrier member disposed coaxially with the drive shaft, and a planetary roller rotatably held by the carrier member, and is housed in the housing,

the sun member and the ring member have 1 st and 2 nd tapered surfaces, respectively, that are inclined with respect to the drive shaft,

one of the sun member and the ring member is configured to be movable in the front-rear direction integrally with the main shaft relative to the other,

at least a part of the planetary roller is disposed between the 1 st tapered surface and the 2 nd tapered surface in a radial direction with respect to the drive shaft,

the power transmission mechanism is configured such that,

the sun member and the ring member are relatively moved in a direction to approach each other in response to the backward movement of the main shaft, and the planetary rollers are brought into frictional contact with the sun member and the ring member, whereby the power of the motor can be transmitted to the main shaft, and the power of the motor can be transmitted to the main shaft

The power transmission mechanism is configured such that,

the sun member and the ring member are relatively moved in a direction away from each other in response to the forward movement of the main shaft, and the planetary rollers are brought into non-frictional contact with the sun member and the ring member, thereby cutting off the transmission of the power,

the work tool has a restricting member configured to restrict movement of the planetary roller in the forward-backward direction with respect to the housing.

2. The work tool of claim 1,

the carrier member is held by the main shaft so as to be movable in the front-rear direction with respect to the main shaft.

3. The work tool of claim 2,

the carrier member is held by the main shaft so as to be incapable of rotating around the drive shaft, and is configured to rotate integrally with the main shaft by the power transmitted via the planetary rollers.

4. The work tool according to any one of claims 1 to 3,

the restriction member is configured to restrict movement of the carrier member in the front-rear direction with respect to the case.

5. The work tool of claim 4,

the restricting member includes spring members that urge the main shaft and the carrier member forward and backward, respectively, so as to be apart from each other,

the spindle is normally held in a forwardmost position by the loading force of the spring member.

6. The work tool of claim 5,

the ring member is supported by the main shaft so as to be movable in the front-rear direction integrally with the main shaft and rotatable about the drive shaft,

the spring member is interposed between the carrier member and the ring member in the front-rear direction,

the power tool further includes a receiving member that receives one end of the spring member on the ring member side in a state where the receiving member does not rotate with rotation of the ring member.

7. The work tool of claim 6,

the ring member is configured to be rotated by the power of the motor,

the spring member is configured to urge the ring member and the carrier member away from each other in the front-rear direction.

8. The work tool according to any one of claims 1 to 7,

the annular member has at least 1 communication hole that communicates the inside and outside of the annular member.

9. The work tool of claim 8,

the communication hole is formed in a region of the annular member other than a region corresponding to the 2 nd tapered surface.

Images