Driving tool

Abstract

To improve the durability of the rack teeth of a driver that engage with engaging parts in a driving tool in which at least one of the engaging parts is movable with respect to a rotary shaft of a wheel.SOLUTION: A driving tool 1 has: a piston 13 that moves in a driving direction by gas pressure; and a driver 40 that moves integrally with the piston 13 to strike a piece to be driven. The driving tool 1 has: a plurality of rack teeth 41 formed on the driver 40 along the driving direction; and a wheel 22 having, on an outer periphery thereof, a plurality of engaging parts 25 that engage with the plurality of rack teeth 41. Rotation of the wheel 22 causes the driver 40 to move in a direction opposite to the driving direction. At least one of the plurality of engaging parts 25 of the wheel 22 is a forward / backward engaging part 25b movable with respect to a shaft member 21 of the wheel 22. The driver 40 has teeth grooves each of which is formed between the rack teeth 41 adjacent to each other. The teeth groove that receives the forward / backward engaging part 25b is a deep teeth groove 42a that is deeper than the other teeth grooves.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present disclosure relates to a driving tool for driving a driving tool such as a nail or staple into wood or the like. [Background technology]

[0002] Patent Document 1 discloses a gas spring type driving tool that uses the thrust of compressed gas as a striking force. The gas spring type driving tool has a piston that moves up and down within a cylinder and a driver that is integrally connected to the piston. The piston and driver are moved downward in the driving direction by gas pressure in an accumulator chamber. The driver strikes and ejects a driving tool below. After ejecting the driving tool, the piston and driver are returned in the opposite direction to the driving direction by a lift mechanism.

[0003] The driver has a plurality of engaged portions (rack teeth) arranged in a vertical direction. The lift mechanism has a wheel with a plurality of engaging portions that engage with the plurality of engaged portions. The plurality of engaging portions are arranged along the outer periphery of the wheel. The wheel is rotated by a drive source, for example, an electric motor. As the wheel rotates after the driving operation, the engaging portions sequentially mesh with the engaged portions of the driver. This causes the driver and piston to move upward in the counter-driving direction. As the piston moves upward in the counter-driving direction, the gas pressure in the accumulator chamber is increased. When the driver is moved upward to the upper movement end position, the engaging portions of the lift mechanism are disengaged from the engaged portions of the driver. This allows the driver to perform the driving operation again.

[0004] For example, if the nail driver jams in the driving passage or if the driver does not drive the nail to the correct depth, the driver stops at a position above the lower travel end. The wheel rotates as if it were operating normally, even when the driver is stopped at an incorrect position. As a result, the engaging portion does not engage with the rack teeth that it normally engages with, and the engaging portion and the bottom of the rack teeth interfere with each other. As described in Patent Document 1, a technology has been considered that allows the engaging portion to move relative to the wheel's rotation axis. By moving the engaging portion away from the driver, interference between the engaging portion and the bottom of the rack teeth can be eliminated.

[0005] A predetermined engaging portion separates from the driver when it engages with the bottom of the rack tooth. The driver is pushed in the driving direction by the gas pressure in the pressure accumulator. This causes a large load to be applied to the engagement point between the engaging portion and the bottom of the rack tooth. Repeated driving of the driver causes the bottom of the rack tooth to interfere with the engaging portion, which repeatedly applies a load. This may cause damage to the engaged portion. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] International Publication No. 2020 / 059666 Summary of the Invention [Problem to be solved by the invention]

[0007] Therefore, the present disclosure provides an improved durability of the rack teeth of the driver that engages with the engaging portions in a driving tool in which at least one of the engaging portions is movable relative to the rotation axis of the wheel. [Means for solving the problem]

[0008] According to one feature of the present disclosure, a driving tool has a piston that moves in a driving direction by gas pressure. The driving tool has a driver that is attached to the piston and moves integrally with the piston to strike the driving tool. The driving tool has a plurality of rack teeth formed on the driver along the driving direction. The driving tool has a wheel with a plurality of engagement portions on its outer periphery that engage with the plurality of rack teeth. Rotation of the wheel moves the driver in the counter-driving direction. At least one of the plurality of engagement portions of the wheel is an advancing / retracting engagement portion that is movable relative to the rotation axis of the wheel. The driver has tooth grooves between adjacent rack teeth. The tooth grooves that receive the advancing / retracting engagement portions are deep tooth grooves that are deeper than the other tooth grooves.

[0009] Therefore, the advance / retract engagement portion enters the deep tooth groove and engages with the bottom of the rack tooth. As a result, the advance / retract engagement portion first engages with the bottom of the rack tooth at a position deeper than the other engagement portions, and moves relative to the rotation axis of the wheel while continuing to engage with the bottom of the rack tooth. As a result, the advance / retract engagement portion is prevented from strong interference, such as collision with the bottom of the rack tooth, during movement. This makes it possible to prevent damage to the rack tooth due to engagement with the advance / retract engagement portion, and improve the durability of the rack tooth. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. [Figure 2] FIG. 2 is a cross-sectional view taken along line II-II in FIG. [Figure 3] FIG. 3 is a cross-sectional view taken along the line III-III in FIG. [Figure 4] FIG. 10 is a vertical cross-sectional view of the lift mechanism with the wheels positioned at the initial position. [Figure 5] FIG. 10 is a cross-sectional view of the lift mechanism with the wheels in the initial position. [Figure 6] 10 is a cross-sectional view of the lift mechanism and the driver, showing a state in which the wheel is in the initial position and the second engaging portion is engaged with the bottom of the second engaged portion. [Figure 7]10 is a cross-sectional view of the lift mechanism and the driver, showing a state in which the wheel is positioned between the initial position and the moving position and the second engaging portion is engaged with the second engaged portion. [Figure 8] 10 is a cross-sectional view of the lift mechanism and the driver, showing the state in which the wheel is in the moving position and the sixth engaging portion is engaged with the bottom of the sixth engaged portion. [Figure 9] 10 is a cross-sectional view of the lift mechanism and the driver, showing a state in which the wheel is located between the initial position and the moving position and the sixth engaging portion is engaged with the sixth engaged portion. [Figure 10] FIG. 2 is a side view of the piston and driver. [Figure 11] 10 is a cross-sectional view of the lift mechanism and the driver, showing a state in which the wheel is in the initial position and the first engagement portion is engaged with the engagement surface of the front rack tooth. [Figure 12] 10 is a cross-sectional view of the lift mechanism and the driver, showing a state in which the wheel is in the initial position and the second engagement portion is engaged with the engaged surface of the rack tooth when advanced. [Figure 13] 10 is a cross-sectional view of the lift mechanism and the driver, showing a state in which the wheel has moved to the moving position and the second engagement portion is engaged with the engaged surface of the rack tooth when advanced. [Figure 14] 10 is a cross-sectional view of the lift mechanism and the driver, showing the state in which the wheel is in the travel position and the outer position engagement portion is engaged with the engagement surface of the rack tooth after being advanced. [Figure 15] 10 is a cross-sectional view of the lift mechanism and the driver, showing the state in which the wheel is in the moving position and the seventh engagement portion is engaged with the engaged surface of the rack tooth when returning. [Figure 16] 10 is a cross-sectional view of the lift mechanism and the driver, showing the state in which the wheel has moved to the initial position and the seventh engagement portion is engaged with the engaged surface of the rack tooth when returning. [Figure 17] 10 is a cross-sectional view of the lift mechanism and the driver, showing the wheel in the initial position and the final engaging portion engaging the engaged surface of the final rack tooth. [Figure 18] FIG. 2 is a cross-sectional view of the area of ​​the driver where the rack teeth are provided. [Figure 19] 15 is a cross-sectional view of the lift mechanism and the driver in the driving tool of the comparative example, showing the same state as in FIG. 14. [Figure 20] FIG. 17 is a cross-sectional view of the lift mechanism and the driver in the driving tool of the comparative example, showing the same state as in FIG. 16 . DETAILED DESCRIPTION OF THE INVENTION

[0011] According to another feature of the present disclosure, the plurality of rack teeth includes a central rack tooth adjacent to the deep tooth groove in the counter-driving direction and an upstream rack tooth adjacent to the central rack tooth in the counter-driving direction. The pitch between the central rack tooth and the upstream rack tooth is wider than the pitch between the other adjacent rack teeth. Therefore, when the forward / backward engaging portion moves relative to the rotation axis of the wheel, the driver moves slightly back in the driving direction by the amount of movement of the forward / backward engaging portion. At this time, by providing a wide pitch between the central rack tooth and the upstream rack tooth, the engaging portion engaging with the bottom of the upstream rack tooth can retreat outside the tooth groove without interfering with the central rack tooth and the upstream rack tooth. This prevents damage to the upstream rack tooth and the central rack tooth 42.

[0012] According to another feature of the present disclosure, the plurality of rack teeth includes a downstream rack tooth adjacent to the central rack tooth in the driving direction. The pitch between the central rack tooth and the downstream rack tooth is narrower than the pitch between the other adjacent rack teeth. Therefore, after the advance / retract engagement portion moves relative to the rotation axis of the wheel, the engagement portion can smoothly advance toward the bottom of the downstream rack tooth without interfering with the downstream rack tooth. This prevents damage to the downstream rack tooth.

[0013] According to another feature of the present disclosure, the downstream rack teeth have a thinner tooth thickness than the central rack teeth and the upstream rack teeth. This prevents the advancing / retracting engaging portion from interfering with the downstream rack teeth when the advancing / retracting engaging portion enters the deep tooth groove. This prevents damage to the downstream rack teeth.

[0014] According to another feature of the present disclosure, the driving tool has a shaft member rotatably mounted to the tool body. A wheel is mounted on the shaft member so as to be slidable in the radial direction. The wheel rotates together with the shaft member around the center of the shaft member, and all of the multiple engagement portions slide radially relative to the shaft member. Therefore, the advance / retract engagement portion moves relative to the shaft member integrally with the other engagement portions and the wheel. This prevents the advance / retract engagement portion, which is engaged with the bottom of the rack teeth, from moving independently in an unintended manner. This prevents the advance / retract engagement portion from being unexpectedly disengaged from the bottom of the rack teeth.

[0015] According to another feature of the present disclosure, the advancing / retracting engagement portion enters the deep tooth groove and is pushed by the groove bottom of the deep tooth groove, moving relative to the rotation axis of the wheel. Therefore, while the advancing / retracting engagement portion is moving, the advancing / retracting engagement portion and the bottom of the rack tooth are continuously engaged with each other. This prevents the advancing / retracting engagement portion from momentarily separating from the bottom of the rack tooth. This prevents collision between the advancing / retracting engagement portion and the bottom of the rack tooth, thereby preventing damage to the rack tooth.

[0016] According to another feature of the present disclosure, the advancing / retracting engagement portion moves in the driving direction when it receives a force from the groove bottom of the deep tooth groove in the driving direction. Therefore, when the advancing / retracting engagement portion moves, the load that the advancing / retracting engagement portion applies to the bottom of the rack teeth in the direction opposite to the driving direction can be minimized. This further increases the durability of the rack teeth that engage with the advancing / retracting engagement portion.

[0017] According to another feature of the present disclosure, the wheel slides between an initial position where the advancing / retracting engagement portion is spaced apart from the shaft member and a moved position where the advancing / retracting engagement portion is close to the shaft member. One of the plurality of engagement portions is a first engagement portion that first engages with the driver when the driver is moved in the counter-driving direction. The plurality of engagement portions includes an outer position engagement portion located outside a reference circle that is centered on the axis of the rotation shaft and passes through the first engagement portion when the wheel is in the initial position, and an inner position engagement portion located inside the reference circle.

[0018] Therefore, during one rotation of the wheel, there are times when the wheel is located at the initial position, times when it moves from the initial position to the moving position, times when it is located at the moving position, and times when it moves from the moving position to the initial position. The outer position engaging portion and the inner position engaging portion can be provided so that at least one engaging portion engages with the bottom of the rack tooth at each timing. This makes it possible to stabilize the return movement of the driver due to the rotation of the wheel.

[0019] According to another feature of the present disclosure, the multiple engagement portions are arranged on the wheel so that they contact multiple rack teeth at equal angular intervals as the wheel rotates. Therefore, by rotating the wheel at a substantially constant speed, the driver can be returned to the standby position at a substantially constant speed. Therefore, the engagement portions can engage with the bottoms of the rack teeth without providing, for example, a speed adjustment mechanism for adjusting the rotational speed of the wheel. This allows the mechanism for rotating the wheel to be compact.

[0020] According to another feature of the present disclosure, the multiple engagement portions include a first engagement portion that first engages with the driver when moving the driver in the counter-driving direction, and a second engagement portion that engages with the driver after the first engagement portion. The forward / backward engagement portion is the second engagement portion. Therefore, when the driver stops in an incorrect position due to a nail jam or insufficient driving, the first engagement portion is the engagement portion that first interferes with the rack teeth. By eliminating interference between the first engagement portion and the rack teeth, the second engagement portion and other engagement portions after the first engagement portion can move the driver in the counter-driving direction without interfering with the rack teeth. By configuring the wheel to move from the initial position to the moving position when the second engagement portion engages with the bottom of the rack teeth, the first engagement portion can be smoothly retracted from the tooth gap between the rack teeth when the first engagement portion interferes with the rack teeth. This allows the driver's return motion to continue smoothly.

[0021] According to another feature of the present disclosure, a driving tool has a piston that moves in a driving direction by gas pressure. The driving tool has a driver that is attached to the piston and moves integrally with the piston to strike the driving tool. The driving tool has a plurality of rack teeth formed on the driver along the driving direction. The driving tool has a wheel with a plurality of engagement portions on its outer periphery that engage with the plurality of rack teeth. The driving tool has a shaft member to which the wheel is non-rotatably and radially slidably mounted as a rotation axis of the wheel. The rotation of the wheel moves the driver in the counter-driving direction. When the driver is moved in the counter-driving direction, the wheel slides relative to the shaft member from an initial position to a moved position away from the driver. The driver has tooth grooves between adjacent rack teeth. The tooth grooves include shallow tooth grooves that engage with one of the engagement portions when the wheel is in the initial position, and deep tooth grooves that engage with one of the engagement portions when the wheel is moved from the initial position to the moved position or when the wheel is in the moved position and that are deeper than the shallow tooth grooves.

[0022] Therefore, the engaging portion engages with the shallow tooth groove when the wheel is in the initial position. The engaging portion engages with the deep tooth groove when the wheel moves from the initial position to the moving position or when the wheel is located at the moving position. Therefore, while the driver is being moved in the counter-driving direction, one of the engaging portions can remain engaged with either the shallow tooth groove or the deep tooth groove. In particular, when the wheel moves from the initial position to the moving position, the engaging portion also moves in a direction retracting from the deep tooth groove. The engaging portion that engages with the tooth groove during and after movement from the initial position to the moving position is located at an outer position on the wheel so that the engagement is not released after the movement. By locating the engaging portion at an outer position during movement, the engaging portion can remain in the deep tooth groove even when the wheel is moved to the moving position. In this way, the rack teeth can be prevented from disengaging from the engaging portion while the driver is being moved in the counter-driving direction. This prevents the driver from inadvertently returning in the driving direction. Furthermore, by providing a deep tooth groove, the engaging portion can be prevented from interfering with the bottom of the rack tooth located on the driving direction side of the deep tooth groove. Thus, damage to the rack teeth due to the force received from the engaging portion can be suppressed, and the durability of the rack teeth can be increased.

[0023] According to another feature of the present disclosure, the wheel returns from the moving position to the initial position when the driver is moved in the counter-driving direction. The tooth groove includes a second deep tooth groove that engages with one of the engagement portions when the wheel returns from the moving position to the initial position and is deeper than the shallow tooth groove. The shaft member rotates approximately 180 degrees from when the wheel moves from the initial position to the moving position to when it returns to the initial position. Therefore, the engagement portion (advance / retreat engagement portion) is close to the driver just before returning from the moving position to the initial position. Therefore, the engagement portion can maintain a state of engagement with the second deep tooth groove when the wheel returns from the moving position to the initial position. When the wheel returns from the moving position to the initial position, the engagement portion also moves in a direction retracting from the second deep tooth groove. Because the advance / retreat engagement portion is close to the driver before returning to the initial position, the engagement portion can remain in the second deep tooth groove even when the wheel returns to the initial position. Therefore, while the driver is being moved in the anti-driving direction, the rack tooth on the driving direction side of the second deep tooth groove disengages from the engagement portion, preventing the driver from inadvertently returning in the driving direction. Furthermore, by providing a deep second deep tooth groove, it is possible to prevent the advance / withdraw engagement portion from interfering with the bottom of the rack tooth located on the driving direction side of the second deep tooth groove before returning to the initial position. This prevents damage to the rack tooth on the driving direction side of the second deep tooth groove due to force received from the engagement portion, improving durability.

[0024] According to another feature of the present disclosure, the rack teeth have engaged surfaces that engage with engaging portions of the wheel. The rack teeth include post-advance rack teeth that engage with one of the engaging portions when the wheel is in a moving position, and return rack teeth that engage with one of the engaging portions when the wheel returns from the moving position to an initial position. The engaged surfaces of the return rack teeth are inclined in the driving direction from the tip to the root of the return rack tooth with respect to a plane perpendicular to the axial direction of the driver, compared to the engaged surfaces of the post-advance rack teeth.

[0025] Therefore, the engaging portion engages with the engaged surface of the returning rack tooth at an earlier timing than when it engages with the engaged surface of the advancing rack tooth. This allows the timing of the wheel returning from the moved position to the initial position to be accelerated. By accelerating the timing of the wheel movement, the direction of wheel movement can be made closer to a direction perpendicular to the driving direction of the driver. This allows the distance that the engaging portion moves in the driving direction of the driver when the wheel returns from the moved position to the initial position to be shortened. This reduces the impact force generated between the engaging portion and the engaged surface of the returning rack tooth at the moment the wheel returns to the initial position. This prevents damage to the returning rack tooth and increases the durability of the returning rack tooth.

[0026] According to another feature of the present disclosure, the rack teeth include an advancing rack tooth that engages with one of the engaging portions when the wheel moves from the initial position to the moving position. The engaged surface of the advancing rack tooth is inclined from the tip to the root of the advancing rack tooth in the driving direction with respect to a plane perpendicular to the axial direction of the driver, compared to the engaged surface of the post-advancing rack tooth.

[0027] Therefore, the engaging portion engages with the engaged surface of the advancing rack tooth at an earlier timing than when it engages with the engaged surface of the advancing rack tooth. This allows the timing at which the wheel moves from the initial position to the moving position to be accelerated. By accelerating the timing at which the wheel moves, the direction of movement of the wheel can be made closer to a direction perpendicular to the driving direction of the driver. This allows the distance that the engaging portion moves in the driving direction of the driver when the wheel moves from the initial position to the moving position to be shortened. This reduces the impact force that occurs between the engaging portion and the engaged surface of the advancing rack tooth at the moment the wheel moves to the moving position. This prevents damage to the advancing rack tooth and increases the durability of the advancing rack tooth.

[0028] According to another feature of the present disclosure, the engaged surface of the advancing rear rack tooth is inclined in the driving direction from the tip to the root of the advancing rear rack tooth with respect to a plane perpendicular to the axial direction of the driver. This allows for an earlier transfer timing from the preceding engaging portion that engages with the engaged surface of the rack tooth preceding the advancing rear rack tooth to the engaging portion that engages with the engaged surface of the advancing rear rack tooth. Therefore, the engaging portion engages with the engaging surface of the advancing rear rack tooth before the preceding engaging portion moves to the tip of the preceding rack tooth. This reduces the bending moment generated at the root of the leading rack tooth, thereby improving the durability of the leading rack tooth.

[0029] Next, one embodiment of the present disclosure will be described with reference to FIGS. 1 to 10. As an example of the driving tool 1, a gas spring type driving tool is shown, which uses gas pressure in a pressure accumulator above a cylinder as a thrust for driving a driving tool N. In the following description, the driving direction of the driving tool N is defined as a downward direction, and the opposite driving direction is defined as an upward direction. A user of the driving tool 1 is positioned roughly on the left side of the driving tool 1 in FIG. 1. The side in front of the user is defined as the rear direction (user side), and the far side opposite the front side is defined as the front direction. The left and right directions are based on the user.

[0030] As shown in Figures 1 and 3, the driving tool 1 has a tool body 10. The tool body 10 has a configuration in which a cylinder 12 is housed in a generally cylindrical body housing 11. A piston 13 is housed in the cylinder 12 so that it can move up and down reciprocally. The upper part of the cylinder 12 above the piston 13 is connected to a pressure accumulator chamber 14. A compressed gas such as air is sealed in the pressure accumulator chamber 14. The gas pressure in the pressure accumulator chamber 14 acts as a thrust on the upper surface of the piston 13, moving it downward.

[0031] As shown in Figure 3, the lower part of the cylinder 12 is connected to a driving passage 2a of the driving nose 2 provided at the bottom of the tool body 10. The driving nose 2 is connected to a magazine 8 in which a large number of driving tools N (see Figure 1) are loaded. The driving tools N are supplied from the magazine 8 one by one to the driving passage 2a in a position extending upward and downward. A contact arm 3 that can slide up and down is provided at the bottom of the driving nose 2. The contact arm 3 moves upward when it comes into contact with the workpiece W to be driven.

[0032] As shown in Figure 3, a vertically long driver 40 is connected to the underside of the piston 13. The lower part of the driver 40 is inserted into the driving passage 2a. The driver 40 moves downward within the driving passage 2a due to the gas pressure in the pressure accumulator chamber 14 acting on the upper surface of the piston 13. The lower end of the driver 40 strikes a single driving tool N supplied into the driving passage 2a. The struck driving tool N is ejected from the ejection port 2b of the driving nose 2. The ejected driving tool N is driven into the workpiece W. A lower moving end damper 15 is arranged at the bottom of the cylinder 12 to absorb impact at the lower moving end of the piston 13.

[0033] As shown in Figure 3, a plurality of rack teeth 41 are provided on the right side of the driver 40. In this embodiment, ten rack teeth 41 are arranged in a row in the longitudinal direction (vertical direction) of the driver 40. Each rack tooth 41 is provided with a protrusion to the right and a bottom facing the driving direction (downward). The bottom of the rack tooth 41 (engaged surface) engages with an engaging portion 25 provided on the lift mechanism 20, which will be described later.

[0034] As shown in FIG. 1, a grip 4 that is held by the user is provided at the rear of the tool body 10. A trigger 5 that the user operates by pulling with their fingertips is provided on the underside of the front of the grip 4. The trigger 5 is pulled by pressing the contact arm 3 against the workpiece W and moving it upward relative to the driving nose 2. A battery mounting section 6 is provided at the rear of the grip 4. A battery pack 7 can be removably attached to the rear of the battery mounting section 6. The battery pack 7 can be removed from the battery mounting section 6 and repeatedly charged and used with a separately provided charger. The battery pack 7 can be used as a power source for other power tools. The battery pack 7 operates as a power source that supplies power to the drive section 30, which will be described later.

[0035] As shown in Figure 3, a lift mechanism 20 is connected to the right side of the driving nose 2. The lift mechanism 20 has the function of returning the piston 13 and driver 40 upward together after striking. When the lift mechanism 20 returns the piston 13 upward, the gas pressure in the pressure accumulator chamber 14 is increased.

[0036] As shown in FIG. 1, a drive unit 30 for operating the lift mechanism 20 is provided adjacent to the rear of the lift mechanism 20. The lift mechanism 20 and drive unit 30 are housed in a substantially cylindrical drive unit case 11a. The drive unit case 11a connects the lower part of the main body housing 11 and the lower part of the battery attachment part 6. The drive unit case 11a is provided integrally with the main body housing 11.

[0037] As shown in Figure 2, the drive unit 30 has an electric motor 31 as a drive source. The electric motor 31 is housed in a position in which the axis of the output shaft 31a (motor axis J) is aligned in the front-to-rear direction perpendicular to the driving direction (the direction perpendicular to the plane of the paper in Figure 2). The electric motor 31 is powered by the power of the battery pack 7 and is activated by pulling the trigger 5.

[0038] As shown in Figure 2, the output shaft 31a of the electric motor 31 is rotatably supported on the drive unit case 11a via bearings 31b and 31c. The front portion of the output shaft 31a is connected to a reduction gear train 32. The reduction gear train 32 is supported on the inner peripheral side of a substantially cylindrical gear train case 32a housed in the drive unit case 11a. The reduction gear train 32 uses a three-row planetary gear train. The three-row planetary gear train is arranged coaxially with one another and with the motor axis J. The rotational output of the electric motor 31 is reduced in speed by the reduction gear train 32, which includes the three-row planetary gear train, and is output to the front lift mechanism 20.

[0039] As shown in FIG. 2, the lift mechanism 20 has a shaft member 21 connected to a reduction gear train 32 and a wheel 22 supported by the shaft member 21. The lift mechanism 20 is housed in a substantially cylindrical mechanism case 29 housed in the drive unit case 11a. A rotation axis 21c of the shaft member 21 coincides with the motor axis J. The front part of the mechanism case 29 is closed by a lid portion 29a. The front end of the shaft member 21 is rotatably supported by a bearing 26 held in the mechanism case 29 via the lid portion 29a. The rear end of the shaft member 21 is supported by a carrier of the final stage of the reduction gear train 32. The carrier of the final stage of the reduction gear train 32 is rotatably supported by the mechanism case 29 via a bearing 27 provided on the outer periphery. When the electric motor 31 is started, the shaft member 21 and the wheel 22 of the lift mechanism 20 rotate together in the direction of arrow R shown in FIG. 3 (counterclockwise in FIG. 3). When the wheel 22 rotates in the direction of arrow R, the driver 40 is lifted upward.

[0040] As shown in Figures 4 and 5, a support member 21a that supports the wheel 22 is provided in the center of the shaft member 21 in the front-rear direction. The support member 21a is generally cylindrical and has a pair of support planes 21b that extend radially and are parallel to each other. The support member 21a has a spring accommodating portion 21e between the pair of support planes 21b. The spring accommodating portion 21e is recessed along the extension direction of the pair of support planes 21b. The spring accommodating portion 21e opens at the end surface of the support member 21a on the initial position direction side. A compression spring 24 that urges the wheel 22 radially is accommodated in the spring accommodating portion 21e.

[0041] As shown in FIG. 4, a flange portion 21d is provided at the rear of the shaft member 21. The flange portion 21d is rearward of the support member 21a and protrudes radially outward beyond the support member 21a in a disk shape. The front surface of the flange portion 21d abuts against the rear surface of the wheel 22. A lid member 28 is attached to the front of the shaft member 21 forward of the support member 21a. The lid member 28 is provided in a disk shape with approximately the same diameter as the outer periphery of the wheel 22. The lid member 28 is attached in front of the wheel 22 attached to the support member 21a. The rear surface of the lid member 28 abuts against the front surface of the wheel 22. The wheel 22 is sandwiched between the flange portion 21d and the lid member 28, thereby restricting movement in the front-to-rear direction.

[0042] As shown in FIGS. 4 and 5 , a mounting hole 23 is provided in the center of the wheel 22, allowing the support member 21a to be inserted therein. A pair of sliding surfaces 23a extending radially and parallel to each other is provided on the inner wall surface of the mounting hole 23. The distance between the pair of sliding surfaces 23a is approximately the same as the distance between the pair of support planes 21b provided on the support member 21a. By inserting the support member 21a into the mounting hole 23, the sliding surfaces 23a and the support planes 21b come into contact with each other. The sliding surfaces 23a slide against the support planes 21b, causing the wheel 22 to be displaced radially relative to the shaft member 21 within a certain range. As shown in FIG. 6 , the position of the wheel 22 when the center 22c of the wheel 22 is positioned on the rotation shaft 21c of the shaft member 21 is referred to as the initial position. As shown in FIG. 8 , the position of the wheel 22 when the center 22c of the wheel 22 is farthest from the rotation shaft 21c of the shaft member 21 is referred to as the moved position. The position of the wheel 22 shown in FIGS. 7 and 9 corresponds to an intermediate position between the initial position and the movement position.

[0043] 4 and 5, the compression spring 24 housed in the spring housing portion 21e of the support member 21a biases the wall surface of the mounting hole 23 in the radial direction of the wheel 22. The wheel 22 is biased from the movement position toward the initial position relative to the support member 21a. Therefore, when no external force is acting on the wheel 22, the wheel 22 is held in the initial position. When an external force of a certain level or greater acts on the wheel 22 in a direction toward the movement position, the wheel 22 moves from the initial position to the movement position against the biasing force of the compression spring 24.

[0044] 5, a plurality of engagement portions 25 are attached along the outer periphery of the wheel 22. In this embodiment, for example, ten engagement portions 25 are provided. Each engagement portion 25 uses a cylindrical shaft member (pin).

[0045] As shown in Figure 3, the left portion of the wheel 22 enters the driving passage 2a through a window 29b provided in the mechanism case 29. Within the driving passage 2a, each engagement portion 25 of the wheel 22 engages with the bottom of the rack teeth 41 of the driver 40. With at least one of the engagement portions 25 engaged with the bottom of the rack teeth 41 of the driver 40, the wheel 22 is rotated in the direction of arrow R. This causes the driver 40 and piston 13 to return upward.

[0046] As shown in FIG. 4, the wheel 22 has a front flange portion 22a and a rear flange portion 22b that are parallel to each other and spaced a fixed distance from each other in the front-to-rear direction. The front flange portion 22a and the rear flange portion are formed so that their radial projection shapes are the same. Each engagement portion 25 is held at a predetermined position in the circumferential direction of the wheel 22 by a through hole provided in the front flange portion 22a and a slot provided in the rear flange portion 22b. Each engagement portion 25 is supported by the wheel 22 so as to be rotatable about its own axis. This prevents a predetermined area of ​​the outer circumferential surface of each engagement portion 25 from continuously contacting the rack teeth 41. This prevents wear on the engagement portions 25.

[0047] As shown in Figure 5, the multiple engagement portions 25 are each at a different distance from the center 22c of the wheel 22. Furthermore, the circumferential interval between two adjacent engagement portions 25 is such that the angle in the circumferential direction relative to the center 22c is different. In this embodiment, ten engagement portions 25 are arranged at predetermined intervals over a range of approximately 3 / 4 of the circumference of the wheel 22. No engagement portions 25 are arranged over a range of approximately 1 / 4 of the circumference of the wheel 22. Hereinafter, the circumferential range where no engagement portions 25 are arranged is referred to as the relief portion 22d.

[0048] As shown in FIG. 5, the engagement portion 25 immediately behind the relief portion 22d in the rotational direction of the wheel 22 is referred to as the first engagement portion 25a. The center of the first engagement portion 25a is located on a reference circle C at a reference distance from the rotation axis 21c of the shaft member 21 when the wheel 22 is in the initial position. The engagement portion 25 immediately behind the first engagement portion 25a in the rotational direction of the wheel 22 is referred to as the second engagement portion 25b. The second engagement portion 25b is movable relative to the rotation axis 21c and is also referred to as the advancing / retreating engagement portion 25b in this disclosure. The engagement portion 25 five positions behind the first engagement portion 25a in the rotational direction of the wheel 22 is referred to as the sixth engagement portion 25d. The sixth engagement portion 25d is movable relative to the rotation axis 21c and is also referred to as the advancing / retreating engagement portion 25d in this disclosure. The two engagement portions 25 aligned immediately after the first engagement portion 25a in the rotational direction of the wheel 22 are referred to as outer position engagement portions 25c. The centers of the outer position engagement portions 25c are located radially outward from the reference circle C. The sixth engagement portion 25d and the three engagement portions 25 aligned before and after it in the rotational direction of the wheel 22 are referred to as inner position engagement portions 25e. The centers of the inner position engagement portions 25e are located radially inward from the reference circle C.

[0049] As shown in FIG. 5, two adjacent engagement portions 25 are angled with respect to the center 22c of the wheel 22. The angles are referred to as angles A1, A2, A3, A4, A5, A6, A7, A8, and A9 in the order of the rotational direction of the wheel 22, starting from the first engagement portion 25a. For angles A1 and A3, one of the two engagement portions 25 forming the angle is an outer position engagement portion 25c. For angle A2, both of the two engagement portions 25 forming the angle are outer position engagement portions 25c. For angles A4 and A7, one of the two engagement portions 25 forming the angle is an inner position engagement portion 25e. For angles A5 and A6, both of the two engagement portions 25 forming the angle are inner position engagement portions 25e. The angles A1 to A9 are set smaller as the distance from the center of each engagement portion 25 forming the angle to the center 22c of the wheel 22 increases, and larger as the distance decreases. Therefore, angles A1, A2, and A3 are smaller than angles A8 and A9. Angle A2 is smaller than angles A1 and A3. Angles A4, A5, A6, and A7 are larger than angles A8 and A9. Angles A5 and A6 are larger than angles A4 and A7.

[0050] As shown in FIG. 10 , the rack teeth 41 are arranged with approximately the same length from the axis of the driver 40 to the right end (tip). The second rack tooth 41 from the counter-driving direction (top) is the central rack tooth 42 in this disclosure. The rack tooth 41 adjacent to the counter-driving direction side of the central rack tooth 42, i.e., the top rack tooth 41, is the upstream rack tooth 43 in this disclosure. The rack tooth 41 adjacent to the central rack tooth 42 in the driving direction side, i.e., the third rack tooth 41 from the top, is the downstream rack tooth 44 in this disclosure. A tooth gap 43a is formed between the central rack tooth 42 and the upstream rack tooth 43. A deep tooth gap 42a deeper than the tooth gap 43a is formed between the central rack tooth 42 and the downstream rack tooth 44. A tooth gap 44a with approximately the same depth as the tooth gap 43a is formed on the driving direction side of the downstream rack tooth 44.

[0051] As shown in FIG. 10 , the sixth rack tooth 41 from the top is the central rack tooth 45 in the present disclosure. The rack tooth 41 adjacent to the central rack tooth 45 on the side opposite the driving direction, i.e., the fifth-highest rack tooth 41, is the upstream rack tooth 46 in the present disclosure. The rack tooth 41 adjacent to the central rack tooth 45 on the side opposite the driving direction, i.e., the seventh rack tooth 41 from the top, is the downstream rack tooth 47 in the present disclosure. A tooth groove 46a having approximately the same depth as the tooth groove 43a is formed between the central rack tooth 45 and the upstream rack tooth 46. A deep tooth groove 45a that is deeper than the tooth groove 46a and approximately the same depth as the deep tooth groove 42a is formed between the central rack tooth 45 and the downstream rack tooth 47. A tooth groove 47a having approximately the same depth as the tooth groove 46a is formed on the driving direction side of the downstream rack tooth 47. In other words, the deep tooth grooves 42a and 45a are formed deeper than the other tooth grooves.

[0052] As shown in FIG. 10 , the pitch 43b between the central rack tooth 42 and the upstream rack tooth 43 is larger than the pitch 42b between the central rack tooth 42 and the downstream rack tooth 44, and is also larger than the pitch 44b between the downstream rack tooth 44 and the fourth rack tooth 41 from the top. The pitch 42b is smaller than the pitch 44b. The pitch 46b between the central rack tooth 45 and the upstream rack tooth 46 is the same as the pitch 43b. The pitch 45b between the central rack tooth 45 and the downstream rack tooth 47 is the same as the pitch 42b. The pitch 47b between the downstream rack tooth 47 and the eighth rack tooth 41 from the top is the same as the pitch 44b. The other pitches between each rack tooth 41 are the same as the pitch 44b.

[0053] As shown in FIG. 10 , the tooth thickness 42c of the central rack tooth 42 and the tooth thickness 43c of the upstream rack tooth 43 are substantially the same. The tooth thickness 44c of the downstream rack tooth 44 is smaller than the tooth thickness 42c. The tooth thicknesses 45c and 46c of the central rack tooth 45 and the upstream rack tooth 46 are substantially the same as the tooth thickness 42c. The tooth thickness 47c of the downstream rack tooth 47 is substantially the same as the tooth thickness 44c. The other tooth thicknesses 41c of each rack tooth 41 are substantially the same as the tooth thickness 42c. In other words, the downstream rack teeth 44 and 47 are formed so that their tooth thicknesses 44c and 47c are thinner than those of the other rack teeth 41. The rack teeth 41 other than the central rack teeth 42 and 45, the upstream rack teeth 43 and 46, and the downstream rack teeth 44 and 47 are formed to have the same shape and are arranged at equal pitches.

[0054] Next, a series of steps in the driving operation of the driving tool 1 will be described. Figure 3 shows the standby state of the piston 13 and driver 40. In the standby state, the driver 40 and piston 13 are held stopped at a standby position slightly below the upper end of their movement. In this standby state, the engaging portion 25 immediately before the relief portion 22d engages with the bottom of the first (lowest) rack tooth 41 counting from the driving direction side.

[0055] In the standby state, the contact arm 3 shown in FIG. 1 moves upward and the trigger 5 is pulled, starting the electric motor 31. When the electric motor 31 is started, the wheel 22 shown in FIG. 3 rotates in the direction indicated by the arrow R. The engagement portion 25 immediately before the relief portion 22d moves the rack tooth 41 at the lowest end upward. This causes the piston 13 and driver 40 to move upward from the standby position to the upper end of movement. When the driver 40 moves to the upper end of movement, a driving tool N (see FIG. 1) is supplied from the magazine 8 into the driving passage 2a. When the driver 40 reaches the upper end of movement, just before driving, the engagement portion 25 of the wheel 22 disengages from the bottom of the rack tooth 41. This causes the piston 13 and driver 40 to move downward due to the gas pressure in the pressure accumulator chamber 14. As the driver 40 moves downward within the driving passage 2a, one driving tool N is struck.

[0056] When the driver 40 moves downward, all of the engaging portions 25 of the wheel 22 leave the driving passage 2a and are positioned inside the mechanism case 29. Therefore, the relief portions 22d of the wheel 22 are positioned inside the driving passage 2a. This prevents the engaging portions 25 from interfering with the rack teeth 41 of the driver 40, ensuring a smooth driving operation.

[0057] After the driving tool N strikes, the wheel 22 continues to rotate in the direction of arrow R with the driver 40 reaching its lowermost position. As shown in FIG. 6, the first engagement portion 25a engages with the bottom of the uppermost upstream rack tooth 43 among the rack teeth 41. This initiates a return motion that moves the piston 13 and driver 40 upward in the counter-driving direction. At the start of the return motion, the wheel 22 is biased by the compression spring 24 toward the driver 40, which is its initial position on the left. Therefore, the center 22c of the wheel 22 is located on the rotation axis 21c of the shaft member 21.

[0058] As shown in FIGS. 6 and 7 , the second engagement portion 25b engages with the bottom of the central rack tooth 42. The second engagement portion 25b is an outer position engagement portion 25c that is farther from the center 22c than the first engagement portion 25a. Therefore, when the wheel 22 is in the initial position, the second engagement portion 25b abuts against the groove bottom of the deep tooth groove 42a, which is deeper than the other tooth grooves, such as the tooth grooves 43a and 44a. The downstream rack tooth 44 has a thin tooth thickness 44c (see FIG. 10 ) so that the second engagement portion 25b does not interfere with the second engagement portion 25b when it enters the groove bottom of the deep tooth groove 42a. If the wheel 22 continues to rotate in the direction of arrow R while remaining in the initial position, the second engagement portion 25b will interfere with the bottom of the central rack tooth 42. The wheel 22 moves from the initial position to the rightward moving position against the biasing force of the compression spring 24 to avoid interference. For example, when the slide surface 23a is tilted in the direction opposite to the driving direction toward the driver 40, the wheel 22 moves to the moving position. The center 22c of the wheel 22 moves to the right of the rotation axis 21c of the shaft member 21.

[0059] 7, the wheel 22 moves from the initial position to the moving position at the timing when the second engagement portion 25b engages with the bottom of the central rack tooth 42. At this time, the wheel 22 momentarily moves downward and to the right, moving away from the driver 40. By providing the deep tooth groove 42a deeply, the engagement relationship between the second engagement portion 25b and the bottom of the central rack tooth 42 is maintained even while the wheel 22 is moving.

[0060] The pitch 43b between the upstream rack teeth 43 and the central rack teeth 42 is set wider than the other pitches, such as the pitches 42b and 44b (see FIG. 10). Therefore, when the wheel 22 moves from the initial position to the moving position and returns in the driving direction, the first engagement portion 25a can retreat from the tooth groove 43a without interfering with the upstream rack teeth 43 or the central rack teeth 42. The pitch 42b between the central rack teeth 42 and the downstream rack teeth 44 is set narrower than the other pitches, such as the pitches 42b and 44b (see FIG. 10). Therefore, after the wheel 22 moves to the moving position, the next outer position engagement portion 25c of the second engagement portion 25b can enter the tooth groove 44a without interfering with the central rack tooth 42.

[0061] As shown in Figures 9 and 10, the sixth engagement portion 25d engages with the bottom of the central rack tooth 45. The sixth engagement portion 25d is an inner position engagement portion 25e that is farther from the center 22c than the first engagement portion 25a. When the wheel 22 is in the moving position, the second engagement portion 25b abuts against the bottom of the central rack tooth 42 at a position shallower than the bottom of the deep tooth groove 45a. The downstream rack tooth 47 has a tooth thickness 47c thinner than the other rack teeth 41 so that the sixth engagement portion 25d does not interfere with the sixth engagement portion 25d when it enters the deep tooth groove 45a. As the wheel 22 continues to rotate in the direction of arrow R, the wheel 22 moves to the moving position, for example, when the slide surface 23a tilts toward the driver 40 in the driving direction. The center 22c of the wheel 22 moves rightward, approaching the rotation axis 21c of the shaft member 21.

[0062] 7, when the wheel 22 moves from the moving position to the initial position, it momentarily moves downward and to the left so as to approach the driver. By providing the deep tooth groove 45a deeply, the engagement relationship between the sixth engagement portion 25d and the bottom of the central rack tooth 45 is maintained even while the wheel 22 is moving.

[0063] 8 to 10, the pitch 46b between the upstream rack teeth 46 and the central rack teeth 45 is set wider than the other pitches. Therefore, when the wheel 22 moves from the moving position to the initial position, the inner position engagement portion 25e before the sixth engagement portion 25d can retreat from the deep tooth groove 45a without interfering with the upstream rack teeth 46 or the central rack teeth 45. The pitch 45b between the central rack teeth 45 and the downstream rack teeth 47 is set narrower than the other pitches. Therefore, after the wheel 22 moves to the moving position, the inner position engagement portion 25e next to the sixth engagement portion 25d can enter the tooth groove 47a without interfering with the central rack tooth 45.

[0064] As shown in Figure 3, when the engaging portion 25 immediately before the relief portion 22d engages with the bottom of the lowest rack tooth 41, the piston 13 and the driver 40 reach the standby position. For example, by appropriately controlling the time from the start of the electric motor 31, the electric motor 31 (see Figure 2) is stopped when the driver 40 and the piston 13 reach the standby position. This completes the series of driving operations. The standby position of the piston 13 and the driver 40 is set below the upper limit position. In one driving operation, the driver 40 is first moved up from the standby position to the upper limit position, and then moved down by gas pressure to perform the driving operation.

[0065] As described above, the driving tool 1 has a piston 13 that moves in the driving direction due to gas pressure, as shown in FIGS. 6 and 8 . The driving tool 1 also has a driver 40 that is attached to the piston 13 and moves integrally with the piston 13 to strike the driving tool. The driving tool 1 has a plurality of rack teeth 41 formed on the driver 40 along the driving direction. The driving tool 1 also has a wheel 22 with a plurality of engagement portions 25 on its outer periphery that engage with the rack teeth 41. Rotation of the wheel 22 moves the driver 40 in the direction opposite to the driving direction. At least one of the engagement portions 25 on the wheel 22 is an advancing / retracting engagement portion 25b, 25d that is movable relative to the shaft member 21 of the wheel 22. The driver 40 has tooth grooves between adjacent rack teeth 41. The tooth grooves that receive the advancing / retracting engagement portions 25b, 25d are deep tooth grooves 42a, 45a that are deeper than the other tooth grooves.

[0066] Therefore, the advance / retract engagement portions 25b, 25d enter the deep tooth grooves 42a, 45a and engage with the bottoms of the rack teeth 41. As a result, the advance / retract engagement portions 25b, 25d first engage with the bottoms of the rack teeth 41 at a position deeper than the other engagement portions 25, and move relative to the shaft member 21 of the wheel 22 while maintaining engagement with the bottoms of the rack teeth 41. Therefore, the advance / retract engagement portions 25b, 25d are prevented from strong interference, such as collisions with the bottoms of the rack teeth 41, during their movement. This makes it possible to prevent damage to the rack teeth 41 due to engagement with the advance / retract engagement portions 25b, 25d, and improve the durability of the rack teeth 41.

[0067] As shown in Figures 7 and 9, the rack teeth 41 include central rack teeth 42, 45 adjacent to the deep tooth grooves 42a, 45a in the counter-driving direction, and upstream rack teeth 43, 46 adjacent to the central rack teeth 42, 45 in the counter-driving direction. The pitches 43b, 46b between the central rack teeth 42, 45 and the upstream rack teeth 43, 46 are wider than the pitches between the other adjacent rack teeth 41. Therefore, when the advancing / retracting engagement portions 25b, 25d move relative to the shaft member 21 of the wheel 22, the driver 40 moves slightly back in the driving direction by the amount of movement of the advancing / retracting engagement portions 25b, 25d. By providing the wide pitches 43b, 46b between the central rack teeth 42, 45 and the upstream rack teeth 43, 46, the engagement portions 25 engaging with the bottoms of the upstream rack teeth 43, 46 can retreat to the outside of the tooth grooves without interfering with the central rack teeth 42, 45 and the upstream rack teeth 43, 46. This makes it possible to prevent damage to the upstream rack teeth 43, 46 and the central rack teeth 42, 45.

[0068] 7 and 9, the plurality of rack teeth 41 includes downstream rack teeth 44, 47 adjacent to the central rack teeth 42, 45 in the driving direction. The pitches 42b, 45b between the central rack teeth 42, 45 and the downstream rack teeth 44, 47 are narrower than the pitches between the other adjacent rack teeth 41. Therefore, after the advance / retract engagement portions 25b, 25d have moved relative to the rotation shaft 21c of the wheel 22, the engagement portion 25 can smoothly advance toward the bottoms of the downstream rack teeth 44, 47 without interfering with the downstream rack teeth 44, 47. This prevents damage to the downstream rack teeth 44, 47.

[0069] 6 and 8, the downstream rack teeth 44, 47 have thicknesses 44c, 47c that are thinner than the thicknesses 42c, 45c of the central rack teeth 42, 45 and the thicknesses 43c, 46c of the upstream rack teeth 43, 46. This prevents the advance / retract engagement portions 25b, 25d from interfering with the downstream rack teeth 44, 47 when the advance / retract engagement portions 25b, 25d enter the deep tooth grooves 42a, 45a. This prevents damage to the downstream rack teeth 44, 47.

[0070] 6 and 7 , the driving tool 1 has a shaft member 21 rotatably mounted on the tool body 10. A wheel 22 is mounted on the shaft member 21 so as to be slidable in the radial direction. The wheel 22 rotates together with the shaft member 21 around the center of the shaft member 21, and all of the multiple engagement portions 25 slide radially relative to the shaft member 21. Therefore, the advance / retract engagement portions 25b, 25d move integrally with the other engagement portions 25 and the wheel 22 relative to the shaft member 21. This prevents the advance / retract engagement portions 25b, 25d, which are engaged with the bottom portions of the rack teeth 41, from moving independently unexpectedly. This prevents the advance / retract engagement portions 25b, 25d from accidentally disengaging from the bottom portions of the rack teeth 41.

[0071] 6 to 9, the advance / retract engagement portions 25b, 25d enter the deep tooth grooves 42a, 45a and are pushed by the groove bottoms of the deep tooth grooves 42a, 45a, moving relative to the rotation shaft 21c of the wheel 22. Therefore, while the advance / retract engagement portions 25b, 25d are moving, the advance / retract engagement portions 25b, 25d are continuously engaged with the bottoms of the rack teeth 41. This prevents the advance / retract engagement portions 25b, 25d from momentarily separating from the bottoms of the rack teeth 41. This prevents collisions between the advance / retract engagement portions 25b, 25d and the bottoms of the rack teeth 41, and prevents damage to the rack teeth 41.

[0072] 6 to 9, the advance / retract engagement portions 25b, 25d move in the driving direction by receiving a force in the driving direction from the groove bottom of the deep tooth grooves 42a, 45a. Therefore, when the advance / retract engagement portions 25b, 25d are moving, it is possible to minimize the load in the counter-driving direction that the advance / retract engagement portions 25b, 25d apply to the bottom of the rack teeth 41. This further increases the durability of the rack teeth 41 that engage with the advance / retract engagement portions 25b, 25d.

[0073] 5 and 6, the wheel 22 slides between an initial position where the advance / retract engagement portions 25b, 25d are separated from the shaft member 21 and a moved position where the advance / retract engagement portions 25b, 25d are close to the shaft member 21. One of the multiple engagement portions 25 is a first engagement portion 25a that first engages with the driver 40 when the driver 40 is moved in the counter-driving direction. The multiple engagement portions 25 include an outer position engagement portion 25c that is located outside a reference circle C that is centered on the axis of the rotation shaft 21c and passes through the first engagement portion 25a when the wheel 22 is located in the initial position, and an inner position engagement portion 25e that is located inside the reference circle.

[0074] Therefore, during one rotation of the wheel 22, there are times when the wheel 22 is located at the initial position, times when the wheel 22 moves from the initial position to the moving position, times when the wheel 22 is located at the moving position, and times when the wheel 22 moves from the moving position to the initial position. The outer position engaging portion 25c and the inner position engaging portion 25e can be provided so that at least one engaging portion 25 engages with the bottom of the rack tooth 41 at any one of these times. This makes it possible to stabilize the return operation of the driver 40 due to the rotation of the wheel 22.

[0075] 5 and 6, the multiple engagement portions 25 are arranged on the wheel 22 so that they come into contact with multiple rack teeth 41 at equal angular intervals as the wheel 22 rotates. Therefore, by rotating the wheel 22 at a substantially constant speed, the driver 40 can be returned to the standby position at a substantially constant speed. Therefore, it is possible to engage the engagement portions 25 with the bottoms of the rack teeth 41 without providing, for example, a speed adjustment mechanism for adjusting the rotational speed of the wheel 22. This allows the mechanism for rotating the wheel 22 to be compact.

[0076] As shown in FIGS. 6 to 9 , the multiple engagement portions 25 include a first engagement portion 25a that first engages with the driver 40 when the driver 40 is moved in the counter-driving direction, and a second engagement portion 25b that engages with the driver 40 after the first engagement portion 25a. The forward / backward engagement portion 25b is the second engagement portion. Therefore, when the driver 40 stops in an incorrect position due to a nail jam or insufficient driving, the first engagement portion 25 that interferes with the rack teeth 41 is the first engagement portion 25a. By eliminating the interference between the first engagement portion 25a and the rack teeth 41, the second engagement portion 25b and the other engagement portions 25 can move the driver 40 in the counter-driving direction without interfering with the rack teeth 41. By configuring the wheel 22 to move from the initial position to the moving position when the second engagement portion 25b engages with the bottom of the rack teeth 41, the first engagement portion 25a can be smoothly retracted from the tooth gap between the rack teeth 41 when the first engagement portion 25a interferes with the rack teeth 41. Thus, the return movement of the driver 40 can be continued smoothly.

[0077] Next, a second embodiment of the present disclosure will be described with reference to Figures 11 to 18. A driving tool 50 of the second embodiment has a lift mechanism 51 and a driver 60 instead of the lift mechanism 20 and driver 40 shown in Figure 6. In the following explanation, only the parts that differ from the first embodiment will be described in detail.

[0078] As shown in FIG. 11, a vertically elongated driver 60 is coupled to the underside of the piston 13. The lower part of the driver 60 is inserted into the driving passage 2a. The driver 60 moves downward within the driving passage 2a due to gas pressure from the pressure accumulator chamber 14 (see FIG. 3) acting on the upper surface of the piston 13. The lower end of the driver 60 strikes a single driving tool supplied into the driving passage 2a. Multiple rack teeth 61 are provided on the right side of the driver 60. In this embodiment, nine rack teeth 61 are arranged vertically along the longitudinal direction of the driver 60. Each rack tooth 61 protrudes to the right, with its bottom facing the driving direction (downward). The bottom of the rack tooth 61 (engaged surface) engages with the engagement portion 54 of the lift mechanism 51.

[0079] As shown in FIG. 11, lift mechanism 51 is housed in a substantially cylindrical mechanism case 29 at the same position as lift mechanism 20 shown in FIG. 3. Lift mechanism 51 has a shaft member 21 connected to a reduction gear train 32 (see FIG. 2) and a wheel 52 supported by shaft member 21. When electric motor 31 (see FIG. 2) is started, shaft member 21 of lift mechanism 51 and wheel 52 rotate together in the direction of arrow R (counterclockwise in FIG. 11). As wheel 52 rotates in the direction of arrow R, driver 60 is lifted upward after striking the driving tool. As piston 13 integrated with driver 60 returns upward, the gas pressure in pressure accumulator chamber 14 (see FIG. 3) is increased.

[0080] As shown in FIG. 11 , a mounting hole 53 is provided in the center of the wheel 52, into which the support member 21a of the shaft member 21 can be inserted. A pair of sliding surfaces 53a extending radially and parallel to each other is provided on the inner wall surface of the mounting hole 53. The distance between the pair of sliding surfaces 53a is approximately the same as the distance between the pair of support planes 21b provided on the support member 21a. By inserting the support member 21a into the mounting hole 53, the sliding surfaces 53a and the support planes 21b face each other and come into contact. The sliding surfaces 53a slide against the support planes 21b, displacing the wheel 52 within a certain range in the radial direction relative to the shaft member 21. As shown in FIG. 11 , the position of the wheel 52 when the center 52a of the wheel 52 is positioned on the rotation axis 21c of the shaft member 21 is referred to as the initial position. As shown in FIG. 13 , the position of the wheel 52 when the center 52a of the wheel 52 is furthest away from the rotation axis 21c of the shaft member 21 is referred to as the moved position.

[0081] 11, the wheel 52 is biased by the compression spring 24 from the movement position toward the initial position relative to the support member 21a. Therefore, when no external force is acting on the wheel 52, the wheel 52 is held in the initial position. When an external force of a certain level or greater acts on the wheel 52 in a direction toward the movement position, the wheel 52 moves from the initial position to the movement position against the biasing force of the compression spring 24.

[0082] As shown in FIG. 11 , a plurality of engagement portions 54 are attached along the outer periphery of the wheel 52. In this embodiment, for example, nine engagement portions 54 are provided. Each engagement portion 54 uses a cylindrical shaft member (pin). Each engagement portion 54 is supported on the wheel 52 so as to be rotatable around its respective shaft center. The left portion of the wheel 52 enters the driving passage 2a through a window 29b provided in the mechanism case 29. In the driving passage 2a, at least one of the engagement portions 54 of the wheel 52 rotating in the direction of arrow R engages with the bottom portion (engaged surface) of the rack teeth 61 of the driver 60.

[0083] 11, the multiple engagement portions 54 are each at a different distance from the center 52a of the wheel 52. Furthermore, the circumferential interval between two adjacent engagement portions 54 is such that the angle in the circumferential direction relative to the center 52a is different. In this embodiment, nine engagement portions 54 are arranged at predetermined intervals over a range of approximately 3 / 4 of the circumference of the wheel 52. Approximately 1 / 4 of the range of the wheel 52 is provided as relief portions 52b where no engagement portions 54 are arranged.

[0084] As shown in FIG. 11 , the engagement portion 54 immediately behind the relief portion 52b in the rotational direction of the wheel 52 is referred to as the first engagement portion 54a. The engagement portion 54 aligned immediately behind the first engagement portion 54a in the rotational direction of the wheel 52 is referred to as the second engagement portion 54b. The second engagement portion 54b is movable relative to the rotation shaft 21c as the wheel 52 slides radially, and is also referred to as the advancing / retreating engagement portion 54b in this disclosure. The engagement portion 54 aligned six positions behind the first engagement portion 54a in the rotational direction of the wheel 52 is referred to as the seventh engagement portion 54f. The seventh engagement portion 54f is movable relative to the rotation shaft 21c as the wheel 52 slides radially, and is also referred to as the advancing / retreating engagement portion 54f in this disclosure. The three engagement portions 54 aligned between the first engagement portion 54a and the fifth engagement portion 54d are referred to as the outer position engagement portions 54c. The three engagement portions 54 lined up after the fifth engagement portion 54d are referred to as inner position engagement portions 54e. The engagement portion 54 immediately preceding the relief portion 52b in the rotational direction of the wheel 52 is referred to as the final engagement portion 54g. Two adjacent engagement portions 54 are angled with respect to the center 52a of the wheel 52. The longer the distance from the center of each engagement portion 54 forming the angle to the center 52a of the wheel 52, the smaller the angle becomes, and the shorter the distance, the larger the angle becomes.

[0085] 18, the rack teeth 61 are arranged with approximately the same length from the axis center of the driver 60 to the right end (tip). The second rack tooth 61 from the side opposite the driving direction (upper side) is the advancing rack tooth 63 in this disclosure. The seventh rack tooth 61 from the side opposite the driving direction is the returning rack tooth 65 in this disclosure. The ninth rack tooth 61 from the top, which is arranged at the bottom end, is the final rack tooth 67. The final rack tooth 67 is arranged with a length from the axis center of the driver 60 to the right end that is longer than the other rack teeth 61, for example, by 1 mm.

[0086] 18, the rack tooth 61 provided on the side opposite the driving direction from the advancing rack tooth 63, i.e., the top rack tooth 61, is the pre-advancing rack tooth 62 in this disclosure. The third to sixth rack teeth 61 from the top, which are provided between the advancing rack tooth 63 and the returning rack tooth 65, are the post-advancing rack tooth 64 in this disclosure. The eighth rack tooth 61 from the top, which is provided between the returning rack tooth 65 and the final rack tooth 67, is the post-return rack tooth 66 in this disclosure.

[0087] As shown in Fig. 18, a shallow tooth groove 62a is formed between the pre-advance rack tooth 62 and the advancing rack tooth 63. A deep tooth groove 63a that is deeper than the shallow tooth groove 62a, for example, by 1 mm or 2 mm, is formed on the driving direction side of the advancing rack tooth 63. A deep tooth groove 64a having substantially the same depth as the deep tooth groove 63a is formed on the driving direction side of the post-advance rack tooth 64. A second deep tooth groove 65a having substantially the same depth as the deep tooth groove 63a is formed on the driving direction side of the returning rack tooth 65. A shallow tooth groove 66a having substantially the same depth as the shallow tooth groove 62a is formed on the driving direction side of the post-returning rack tooth 66.

[0088] As shown in FIG. 18 , an engaged surface 62b, which is the lower surface of the pre-advance rack tooth 62, extends in a direction perpendicular to the axial direction (up-down direction) of the driver 60. An engaged surface 63b, which is the lower surface of the advancing rack tooth 63, is inclined downward to the left (from the tip of the advancing rack tooth 63 to the base) with respect to a plane perpendicular to the axial direction of the driver 60. An inclination angle 63d of the engaged surface 63b with respect to the plane perpendicular to the axial direction of the driver 60 is, for example, in the range of 5° to 15°, more preferably 8° to 12°. An engaged surface 64b, which is the lower surface of the post-advance rack tooth 64, is inclined downward to the left (from the tip of the post-advance rack tooth 64 to the base) with respect to a plane perpendicular to the axial direction of the driver 60. An inclination angle 64d of the engaged surface 64b with respect to the plane perpendicular to the axial direction of the driver 60 is smaller than the inclination angle 63d of the engaged surface 63b of the advancing rack tooth 63, and is, for example, in the range of 3° to 7°.

[0089] As shown in FIG. 18 , the engaged surface 65b, which is the lower surface of the return rack tooth 65, is inclined downward to the left (from the tip of the return rack tooth 65 to the base) with respect to a plane perpendicular to the axial direction of the driver 60. An inclination angle 65d of the engaged surface 65b with respect to the plane perpendicular to the axial direction of the driver 60 is larger than an inclination angle 63d of the engaged surface 63b of the advancing rack tooth 63 and is also larger than an inclination angle 64d of the engaged surface 64b of the advancing rack tooth 64. The inclination angle 65d is, for example, within a range of 13° to 23°, more preferably 16° to 20°. The engaged surface 66b, which is the lower surface of the rear return rack tooth 66, is inclined downward to the left with respect to a plane perpendicular to the axial direction of the driver 60. The inclination angle 66d of the engaged surface 66b with respect to the plane perpendicular to the axial direction of the driver 60 is smaller than the inclination angle 65d and is, for example, approximately the same as an inclination angle 64d of the engaged surface 64b of the advancing rack tooth 64. An engaged surface 67a, which is the lower surface of the final rack tooth 67, extends in a direction perpendicular to the axial direction of the driver 60 (the up-down direction).

[0090] As shown in Fig. 18, the tooth thickness of the rack teeth 61 in the vertical direction tends to be thinner as the inclination angle of the engaged surface increases and thicker as the inclination angle of the engaged surface decreases. That is, the tooth thickness 63c of the advancing rack teeth 63 is thinner than the tooth thickness 64c of the post-advancing rack teeth 64. The tooth thickness 65c of the returning rack teeth 65 is thinner than the tooth thickness 63c of the advancing rack teeth 63 and the tooth thickness 64c of the post-advancing rack teeth 64. The tooth thickness 66c of the post-returning rack teeth 66 is set to be approximately the same as the tooth thickness 64c of the post-advancing rack teeth 64. Since the pre-advancing rack teeth 62 engage with the engaging portions 54 (see Fig. 11) when the gas pressure is still low, the tooth thickness 62c is set to be thin, approximately the same as the tooth thickness 63c of the advancing rack teeth 63. The final rack tooth 67 has a tooth thickness 67b greater than that of the other rack teeth 61 in order to hold the driver 60 at the standby position with the gas pressure sufficiently high.

[0091] As shown in FIG. 18 , the pitches 68 of the multiple rack teeth 61 are spaced apart at unequal intervals. This allows the rack teeth 61 to engage with the engagement portion 54 of the lift mechanism 51 at approximately equal time intervals or each time the wheel 52 rotates by a predetermined rotation angle (see FIG. 11 ). The pitch 68b between the advancing rack tooth 63 and the post-advancing rack tooth 64 immediately below is larger than the pitch 68a between the pre-advancing rack tooth 62 and the advancing rack tooth 63, and is also larger than the pitch 68c between the post-advancing rack teeth 64. The pitch 68d between the post-advancing rack tooth 64 and the returning rack tooth 65 is slightly smaller than the pitch 68c between the post-advancing rack teeth 64. The pitch 68e between the returning rack tooth 65 and the post-returning rack tooth 66 is larger than the pitch 68d between the post-advancing rack tooth 64 and the returning rack tooth 65, and is approximately the same size as the pitch 68b between the advancing rack tooth 63 and the post-advancing rack tooth 64 immediately below. The pitch 68f between the rear return rack tooth 66 and the final rack tooth 67 is set to be approximately the same as or slightly larger than the pitch 68e between the return rack tooth 65 and the rear return rack tooth 66.

[0092] Next, we will explain the engagement between each rack tooth 61 and each engagement portion 54 when the driver 60 is moved upward in the direction opposite to the driving direction. As shown in Figure 11, after the driver 60 reaches the bottom end, the wheel 52 rotates in the direction of arrow R, causing the first engagement portion 54a to engage with the engaged surface 62b of the front rack tooth 62. This starts a return operation that moves the piston 13 and driver 60 upward in the direction opposite to the driving direction. At the start of the return operation, the wheel 52 is biased by the compression spring 24 toward the driver 60 on the left, and is positioned at its initial position.

[0093] As shown in FIG. 12 , when the wheel 52 further rotates in the direction of arrow R, the second engaging portion 54b engages with the engaged surface 63b of the advancing rack tooth 63. The engaged surface 63b is inclined in the driving direction (downward) from the tip to the root of the advancing rack tooth 63. Therefore, the second engaging portion 54b and the engaged surface 63b engage with each other earlier than if the engaged surface 63b were perpendicular to the axial direction of the driver 60. Therefore, when the second engaging portion 54b starts to engage with the engaged surface 63b, it engages with the engaged surface 63b at the bottom of the deep tooth groove 63a near the root of the advancing rack tooth 63. When the second engaging portion 54b and the engaged surface 63b start to engage with each other, the wheel 52 is in the initial position.

[0094] As shown in FIG. 13 , when the wheel 52 continues to rotate in the direction of arrow R while remaining in the initial position, the force in the driving direction that the second engagement portion 54b receives from the advancing rack tooth 63 becomes greater than the biasing force of the compression spring 24. Therefore, the wheel 52 instantaneously moves from the initial position to a moving position to the right relative to the shaft member 21 at the timing when the second engagement portion 54b engages with the engaged surface 63b of the advancing rack tooth 63. The movement direction from the initial position to the moving position includes a component in a direction away from the driver 60 and a component in the driving direction (downward). By setting the inclination angle 63d of the engaged surface 63b (see FIG. 18 ) to be large, the wheel 52 moves in a direction slightly inclined downward toward the right, in other words, in a direction with a small inclination angle with respect to a plane perpendicular to the axial direction of the driver 60. Therefore, the second engagement portion 54b moves only a small amount downward when the wheel 52 moves from the initial position to the moving position. This shortens the distance that the driver 60 instantaneously moves downward when the wheel 52 moves from the initial position to the moving position.

[0095] 14, when the wheel 52 in the movement position further rotates in the direction of arrow R, the engaging portion 54 sequentially engages with the engaged surface 64b of the post-advance rack tooth 64. The engaged surface 64b is inclined in the driving direction (downward) from the tip to the base of the post-advance rack tooth 64. Therefore, the engaging portion 54 and the engaged surface 64b engage with each other at an earlier timing than if the engaged surface 64b were perpendicular to the axial direction of the driver 60. Therefore, when the engaging portion 54 starts to engage with the engaged surface 64b, it engages with the engaged surface 64b at the groove bottom of the deep tooth groove 64a near the base of the post-advance rack tooth 64.

[0096] 15, when the wheel 52 further rotates in the direction of arrow R, the seventh engagement portion 54f engages with the engaged surface 65b of the return rack tooth 65. The engaged surface 65b is inclined in the driving direction (downward) from the tip to the base of the return rack tooth 65. Therefore, the seventh engagement portion 54f and the engaged surface 65b engage with each other at an earlier timing than if the engaged surface 65b were perpendicular to the axial direction of the driver 60. Therefore, when the seventh engagement portion 54f starts to engage with the engaged surface 65b, it engages with the engaged surface 65b at the groove bottom of the second deep tooth groove 65a, which is close to the base of the return rack tooth 65.

[0097] As shown in FIG. 16, when the wheel 52 continues to rotate in the direction of arrow R while remaining in the moving position, the force that the seventh engagement portion 54f receives from the return rack tooth 65 becomes greater than the frictional force between the sliding surface 53a of the wheel 52 and the support flat surface 21b of the shaft member 21. Therefore, the wheel 52 instantaneously moves from the moving position to the initial position to the right relative to the shaft member 21 at the timing when the seventh engagement portion 54f engages with the engaged surface 65b of the return rack tooth 65. At this time, the shaft member 21 has rotated approximately 180° from the time when the wheel 52 moved from the initial position to the moving position. The movement direction from the moving position to the initial position includes a component away from the driver 60 and a component in the driving direction (downward). The inclination angle 65d of the engaged surface 65b is greater than the inclination angle 63d of the advancing rack tooth 63 and the inclination angle 64d of the post-advance rack tooth 64 (see FIG. 18). Therefore, when the driver 60 approaches the upper end of its travel and the gas pressure is high, the wheel 52 can move in a direction slightly tilted downward toward the right, in other words, in a direction with a small angle of inclination relative to a plane perpendicular to the axial direction of the driver 60. Therefore, the seventh engagement portion 54f has a small amount of movement Ld in the driving direction when the wheel 52 moves from the travel position to the initial position. This shortens the distance that the driver 60 momentarily moves downward when the wheel 52 moves from the travel position to the initial position.

[0098] 17, when the final engagement portion 54g engages with the engagement surface 67a of the final rack tooth 67, the rotation of the wheel 52 stops. This holds the driver 60 in the standby position. By arranging the engagement surface 67a of the final rack tooth 67 so that it is perpendicular to the axial direction of the driver 60, the force that the final engagement portion 54g receives from the engagement surface 67a is along the axial direction of the driver 60. Therefore, the driver 60 can be stably held in the standby position against the force in the driving direction that is applied by the gas pressure.

[0099] 19 and 20 show a driving tool 70 as a comparative example to the second embodiment. A driver 71 of the comparative example is provided with a post-advance rack tooth 72 and a return rack tooth 73. The inner position engaging portion 54e immediately before the seventh engaging portion 54f enters the tooth groove 72a below the post-advance rack tooth 72 and engages with the engaged surface 72b. The seventh engaging portion 54f enters the tooth groove 73a below the return rack tooth 73 and engages with the engaged surface 73b. The engaged surfaces 72b, 73b are arranged perpendicular to the axial direction of the driver 71.

[0100] As shown in Figure 19, when the inner position engaging portion 54e immediately before the seventh engaging portion 54f begins to engage with the engaged surface 72b of the advancing rear rack tooth 72, the fifth engaging portion 54d, which is two positions before the seventh engaging portion 54f, has moved to the right end (tip) of the advancing rear rack tooth 72. Compared to Figure 14, the fifth engaging portion 54d has moved near the right end of the advancing rear rack tooth 64, but is positioned slightly to the left of the right end. The advancing rear rack teeth 64, 72 receive substantially the same magnitude of force from the fifth engaging portion 54d. Therefore, the bending moment generated at the base of the advancing rear rack tooth 72 by the force received from the fifth engaging portion 54d is greater than the bending moment generated at the base of the advancing rear rack tooth 64 by the force received from the fifth engaging portion 54d.

[0101] As shown in FIG. 20, when the wheel 52 moves from the moving position to the initial position, the seventh engagement portion 54f moves the same distance L in the moving direction of the wheel 52. Compared to FIG. 16, the timing at which the wheel 52 moves to the initial position is earlier in the second embodiment shown in FIG. 16 due to the inclination of the engaged surface 65b of the rack tooth 65 during return. Therefore, the moving direction of the wheel 52 when moving to the initial position is relatively inclined with respect to the axial direction of the driver 60 in the comparative example shown in FIG. 20. On the other hand, in the second embodiment shown in FIG. 16, it is closer to a direction perpendicular to the axial direction of the driver 60. Therefore, the moving distance Ld of the seventh engagement portion 54f in the driving direction is smaller in the second embodiment shown in FIG. 16 than in the comparative example shown in FIG. 20. As a result, the driver 60 of the second embodiment can shorten the distance by which the wheel 52 instantaneously returns downward when moving from the moving position to the initial position.

[0102] As described above, the driving tool 50 has a piston 13 that moves in the driving direction by gas pressure, as shown in FIG. 11 . The driving tool 50 also has a driver 60 that is attached to the piston 13 and moves integrally with the piston 13 to strike the driving tool. The driving tool 50 has a plurality of rack teeth 61 formed on the driver 60 along the driving direction. The driving tool 50 also has a wheel 52 that has a plurality of engaging portions 54 on its outer periphery that engage with the rack teeth 61. The driving tool 50 also has a shaft member 21 on which the wheel 52 is mounted as a rotation axis of the wheel 52, to which the wheel 52 is non-rotatably but radially slidably. The rotation of the wheel 52 moves the driver 60 in the counter-driving direction. When the driver 60 is moved in the counter-driving direction, the wheel 52 slides relative to the shaft member 21 from an initial position to a position away from the driver 60. The driver 60 has tooth spaces between adjacent rack teeth 61. The tooth grooves include shallow tooth grooves 62a, 66a with which the wheel 52 engages with one of the engagement portions 54 when the wheel 52 is in the initial position, and deep tooth grooves 63a, 64a that are deeper than the shallow tooth grooves 62a, 66a and that engage with one of the engagement portions 54 when the wheel 52 moves from the initial position to the moving position or when the wheel 52 is in the moving position.

[0103] Therefore, the engaging portion 54 engages with the shallow tooth grooves 62a, 66a when the wheel 52 is in the initial position. The engaging portion 54 engages with the deep tooth grooves 63a, 64a when the wheel 52 moves from the initial position to the moving position or when the wheel 52 is located at the moving position. Therefore, while the driver 60 is moving in the counter-driving direction, one of the engaging portions 54 can remain engaged with the shallow tooth grooves 62a, 66a or the deep tooth grooves 63a, 64a. In particular, when the wheel 52 moves from the initial position to the moving position, the second engaging portion 54b also moves in a direction retracting from the deep tooth groove 63a. The engaging portion 54, which engages with the tooth groove during and after movement from the initial position to the moving position, is positioned outward from the wheel 52 so that the engagement is not released after the movement. By locating the second engaging portion 54b in an outward position, the second engaging portion 54b can remain in the deep tooth groove 63a even when the wheel 52 moves to the moving position. In this way, the rack teeth 61 can be prevented from coming off the engaging portions 54 while the driver 60 is being moved in the direction opposite to the driving direction. This prevents the driver 60 from inadvertently returning in the driving direction. Furthermore, by providing the deep tooth grooves 63a, 64a deep, it is possible to prevent the engaging portions 54 from interfering with the engaged surfaces (bottoms) 63b, 64b of the advancing rack teeth 63 or the post-advancing rack teeth 64 located on the driving direction side of the deep tooth grooves 63a, 64a. This makes it possible to prevent damage to the rack teeth 61 due to the force received from the engaging portions 54, and improve the durability of the rack teeth 61.

[0104] As shown in FIG. 16 , the wheel 52 returns from the moving position to the initial position when the driver 60 is moved in the counter-driving direction. The tooth groove includes a second deep tooth groove 65a that engages with one of the engaging portions 54 and is deeper than the shallow tooth grooves 62a and 66a when the wheel 52 returns from the moving position to the initial position. The shaft member 21 rotates approximately 180 degrees from when the wheel 52 moves from the initial position to the moving position to when it returns to the initial position. Therefore, the seventh engaging portion 54f is close to the driver 60 immediately before returning from the moving position to the initial position. Therefore, the seventh engaging portion 54f can maintain its engagement with the second deep tooth groove 65a when the wheel 52 returns from the moving position to the initial position. When the wheel 52 returns from the moving position to the initial position, the seventh engaging portion 54f also moves in a direction retracting from the second deep tooth groove 65a. Because the seventh engagement portion 54f is close to the driver 60 before returning to the initial position, the seventh engagement portion 54f can remain in the second deep tooth groove 65a even when the wheel 52 returns to the initial position. Therefore, while the driver 60 is being moved in the counter-driving direction, the return rack tooth 65 on the driving direction side of the second deep tooth groove 65a is prevented from disengaging from the seventh engagement portion 54f. This prevents the driver 60 from accidentally returning in the driving direction. Furthermore, by providing a deep second deep tooth groove 65a, the seventh engagement portion 54f before returning to the initial position is prevented from interfering with the engaged surface (bottom) 65b of the return rack tooth 65 located on the driving direction side of the second deep tooth groove 65a. This prevents the return rack tooth 65 on the driving direction side of the second deep tooth groove 65a from being damaged by force from the engagement portion 54, thereby improving durability.

[0105] As shown in Figure 16, the rack tooth 61 has an engaged surface that engages with the engaging portion 54 of the wheel 52. The rack tooth 61 includes a post-advance rack tooth 64 that engages with one of the engaging portions 54 when the wheel 52 is in the moving position, and a return rack tooth 65 that engages with one of the engaging portions 54 when the wheel 52 returns from the moving position to the initial position. The engaged surface 65b of the return rack tooth 65 is inclined in the driving direction from the tooth tip to the tooth base of the return rack tooth 65 with respect to a plane perpendicular to the axial direction of the driver 60, compared to the engaged surface 64b of the post-advance rack tooth 64 (see Figure 18).

[0106] Therefore, the engaging portion 54 engages with the engaged surface 65b of the return rack tooth 65 at an earlier timing than when it engages with the engaged surface 64b of the advanced rack tooth 64. This allows the wheel 52 to return from the moved position to the initial position at an earlier timing. By advancing the movement timing of the wheel 52, the movement direction of the wheel 52 can be made closer to a direction perpendicular to the driving direction of the driver 60. This shortens the distance that the engaging portion 54 moves in the driving direction of the driver 60 when the wheel 52 returns from the moved position to the initial position. This reduces the impact force generated between the engaging portion 54 and the engaged surface 65b of the return rack tooth 65 when the wheel 52 returns to the initial position. This prevents damage to the return rack tooth 65 and increases the durability of the return rack tooth 65.

[0107] 13, the rack teeth 61 include an advancing rack tooth 63 that engages with one of the engaging portions 54 when the wheel 52 moves from the initial position to the moving position. The engaged surface 63b of the advancing rack tooth 63 is inclined from the tip to the base of the advancing rack tooth 63 in the driving direction with respect to a plane perpendicular to the axial direction of the driver 60, compared to the engaged surface 64b of the post-advancing rack tooth 64 (see FIG. 18).

[0108] Therefore, the engaging portion 54 engages with the engaged surface 63b of the advancing rack tooth 63 at an earlier timing than the engaging surface 64b of the advancing rack tooth 64. This allows the timing at which the wheel 52 moves from the initial position to the moving position to be accelerated. By advancing the timing at which the wheel 52 moves, the moving direction of the wheel 52 can be made closer to a direction perpendicular to the driving direction of the driver 60. This shortens the distance that the engaging portion 54 moves in the driving direction of the driver 60 when the wheel 52 moves from the initial position to the moving position. This reduces the impact force generated between the engaging portion 54, the advancing rack tooth 63, and the engaged surface 63b when the wheel 52 moves to the moving position. This prevents damage to the advancing rack tooth 63 and increases the durability of the advancing rack tooth 63.

[0109] As shown in Fig. 14, the engaged surface 64b of the advancing rear rack tooth 64 is inclined in the driving direction from the tip to the root of the advancing rear rack tooth 64 with respect to a plane perpendicular to the axial direction of the driver 60 (see Fig. 18). This makes it possible to speed up the timing of the transfer from the preceding engaging portion 54 that engages with the engaged surface of the rack tooth 61 preceding the advancing rear rack tooth 64 to the engaging portion 54 that engages with the engaged surface 64b of the advancing rear rack tooth 64. Therefore, the engaging portion 54 engages with the engaged surface 64b of the advancing rear rack tooth 64 before the preceding engaging portion 54 moves to the tip of the preceding rack tooth 61. This makes it possible to suppress the bending moment generated at the root of the leading rack tooth 61, thereby improving the durability of the leading rack tooth 61.

[0110] Various modifications can be made to the above-described embodiments. For example, the lift mechanism 20 is exemplified by a wheel 22 having ten engaging portions 25 and a driver 40 having ten rack teeth 41. The lift mechanism 51 is exemplified by a wheel 52 having nine engaging portions 54 and a driver 60 having nine rack teeth 61. However, the numbers of engaging portions 25 and rack teeth 41 are not limited to these and may be increased or decreased. The numbers of engaging portions 25 and rack teeth 41 are appropriately set depending on factors such as the stroke of the driver 40 and the size of the tool body 10.

[0111] The illustrated configuration shows that the wheel 22 moves from the initial position to the moving position when the second engagement portion 25b engages with the deep tooth groove 42a. The illustrated configuration shows that the wheel 22 moves from the moving position to the initial position when the sixth engagement portion 25d engages with the deep tooth groove 45a. The illustrated configuration shows that the wheel 52 moves from the initial position to the moving position when the second engagement portion 54b engages with the engaged surface 63b of the advancing rack tooth 63. The illustrated configuration shows that the wheel 52 moves from the moving position to the initial position when the seventh engagement portion 54f engages with the engaged surface 65b of the returning rack tooth 65. However, for example, by changing the number of engagement portions and rack teeth, the order of the engagement portions when the wheel moves can also be changed. Therefore, the order in which the deep tooth grooves and rack teeth having engaged surfaces inclined relative to the axial direction of the driver are provided may be changed as appropriate.

[0112] Although the pin-shaped engaging portion 25 has been exemplified, the shape of the engaging portion 25 is not limited thereto. For example, multiple engaging portions 25 may be provided in the shape of pinion teeth formed along the outer periphery of the wheel 22. Although the multiple rack teeth 41 formed at equal intervals in the longitudinal direction of the driver 40 have been exemplified, the shape of the rack teeth 41 is not limited thereto. For example, multiple rack teeth 41 may be formed at unequal intervals. A structure has been exemplified in which all engaging portions 25 rotate integrally with the wheel 22 around the rotation shaft 21c. Instead of this, for example, a configuration in which only the forward / backward engaging portions 25b, 25d are movable relative to the rotation shaft 21c may be used.

[0113] Although the driver 40 has been illustrated as having the deep tooth grooves 42a and 45a with approximately the same depth, they may have different depths. The driver 40 has been illustrated as having the pitch 43b between the upstream rack teeth 43 and the central rack teeth 42 and the pitch 46b between the upstream rack teeth 46 and the central rack teeth 45 with the same size. The driver 40 has also been illustrated as having the pitch 42b between the central rack teeth 42 and the downstream rack teeth 44 with the same size and the pitch 45b between the central rack teeth 45 and the downstream rack teeth 47 with the same size. Alternatively, the pitches may be different. The driver 40 has been illustrated as having the tooth thickness 44c of the downstream rack teeth 44 and the tooth thickness 47c of the downstream rack teeth 47 with approximately the same thickness, but they may have different thicknesses. The rack teeth 41 other than the central rack teeth 42 and 45, the upstream rack teeth 43 and 46, and the downstream rack teeth 44 and 47 have the same shape and are arranged at equal pitches. The shape and pitch of the other rack teeth 41 are not limited to this.

[0114] Although the driver 60 has been exemplified in which the deep tooth grooves 63a, 64a and the second deep tooth groove 65a have approximately the same depth, they may have different depths. The inclination angle, pitch, tooth thickness, etc. of the engaged surface of each rack tooth 61 are not limited to those exemplified and may be changed as appropriate. For example, each rack tooth 61 may have a different size. The engaged surface of the rack tooth 61 is not limited to being flat and may include a curved surface, and the curved surface may be inclined with respect to the axial direction of the driver 60. [Explanation of symbols]

[0115] 1...Driving tool 2... driving nose part, 2a... driving passage, 2b... injection port 3...Contact arm 4. Grip 5...Trigger 6...Battery mounting section 7. Battery pack 8...Magazine 10...Tool body 11...Main body housing, 11a...Drive unit case 12...Cylinder 13...Piston 14...Pressure chamber 15...Lower moving end damper 20...Lift mechanism 21... shaft member, 21a... support member, 21b... support plane, 21c... rotation shaft 21d... flange portion, 21e... spring accommodating portion 22...wheel, 22a...front flange portion, 22b...rear flange portion, 22c...center 22d...Relief 23...mounting hole, 23a...sliding surface 24...Compression spring (biasing member) 25...Engagement part 25a...first engagement part 25b…Second engaging part (advancing / retracting engaging part) 25c...Outer position engagement part 25d...Sixth engagement portion (advance / retreat engagement portion) 25e...Inner position engagement part 26, 27...Bearings 28...Cover member 29... mechanism case, 29a... lid portion, 29b... window portion 30...Drive unit 31...electric motor, 31a...output shaft, 31b, 31c...bearings 32...reduction gear train, 32a...gear train case 40...Driver 41...rack teeth (engaged portion), 41c...tooth thickness 42...Central rack tooth, 42a...Deep tooth groove, 42b...Pitch, 42c...Tooth thickness 43...Upstream rack tooth, 43a...Tooth space, 43b...Pitch, 43c...Tooth thickness 44...downstream rack tooth, 44a...tooth space, 44b...pitch, 44c...tooth thickness 45...Central rack tooth, 45a...Deep tooth groove, 45b...Pitch, 45c...Tooth thickness 46...Upstream rack tooth, 46a...Tooth space, 46b...Pitch, 46c...Tooth thickness 47...downstream rack tooth, 47a...tooth space, 47b...pitch, 47c...tooth thickness 50...Driving tool 51...Lift mechanism 52...wheel, 52a...center, 52b...relief 53...mounting hole, 53a...sliding surface 54...Engagement portion 54a...first engagement part 54b...Second engagement portion (advance / retreat engagement portion) 54c...Outer position engagement part 54d...Fifth engagement portion 54e...Inner position engagement part 54f...Seventh engaging part (advancing / retracting engaging part) 54g…Final engagement part 60...Driver 61...Rack teeth (engaged portion) 62...pre-advance rack tooth, 62a...shallow tooth groove, 62b...engaged surface, 62c...tooth thickness 63...advancing rack teeth, 63a...deep tooth groove, 63b...engaged surface, 63c...tooth thickness 63d…Inclination angle 64... Post-advance rack tooth, 64a... Deep tooth groove, 64b... Engaged surface, 64c... Tooth thickness 64d…Inclination angle 65...return rack tooth, 65a...second deep tooth groove (deep tooth groove), 65b...engaged surface 65c…Tooth thickness, 65d…Inclination angle 66...return rack tooth, 66a...shallow tooth groove, 66b...engaged surface, 66c...tooth thickness 66d…Inclination angle 67... final rack tooth, 67a... engaged surface, 67b... tooth thickness 68, 68a, 68b, 68c, 68d, 68e, 68f...Pitch 70...Driving tool 71...Driver 72...post-advance rack tooth, 72a...tooth groove, 72b...engaged surface 73...return rack tooth, 73a...tooth groove, 73b...engaged surface N...Driver W: Material to be driven J: Motor axis C...Reference circle A1~A9…Angle L...movement amount, Ld...movement amount (in the driving direction)

Claims

1. A driving tool, A piston that moves in the driving direction by gas pressure, a driver provided on the piston and moving integrally with the piston to strike the driving tool; a plurality of rack teeth formed on the driver along the driving direction; a wheel having a plurality of engaging portions on an outer periphery thereof that engage with the plurality of rack teeth, the wheel rotating to move the driver in the counter driving direction; At least one of the plurality of engagement portions of the wheel is an advance / retreat engagement portion that is movable relative to a rotation axis of the wheel, The driver has tooth spaces between adjacent rack teeth, A driving tool in which the tooth groove that receives the advance / retreat engagement portion is a deep tooth groove that is deeper than the other tooth grooves.

2. The driving tool according to claim 1, the plurality of rack teeth include a central rack tooth adjacent to the deep tooth groove in the counter driving direction and an upstream rack tooth adjacent to the central rack tooth in the counter driving direction, A driving tool in which the pitch of the central rack teeth and the upstream rack teeth is wider than the pitch of other rack teeth adjacent to each other.

3. The driving tool according to claim 2, the plurality of rack teeth include a downstream rack tooth adjacent to the central rack tooth on the side of the driving direction, A driving tool in which the pitch of the central rack teeth and the downstream rack teeth is narrower than the pitch of the other adjacent rack teeth.

4. The driving tool according to claim 3, The downstream rack teeth have a smaller tooth thickness than the central rack teeth and the upstream rack teeth.

5. The driving tool according to any one of claims 1 to 4, a shaft member rotatably attached to the tool body; A driving tool in which the wheel is attached to the shaft member so as to be slidable radially, the wheel rotates together with the shaft member around the shaft member, and all of the multiple engagement portions slide radially relative to the shaft member.

6. The driving tool according to any one of claims 1 to 4, The driving tool is configured such that the advancing / retreating engagement portion enters the deep tooth groove and is pushed by the groove bottom of the deep tooth groove to move relative to the rotation axis of the wheel.

7. The driving tool according to claim 6, The driving tool is configured such that the advancing / retreating engagement portion receives a force from the groove bottom of the deep tooth groove along the driving direction and moves in the driving direction.

8. The driving tool according to claim 5, the wheel slides between an initial position where the advance / retract engagement portion is separated from the shaft member and a moving position where the advance / retract engagement portion is close to the shaft member, one of the plurality of engaging portions is a first engaging portion that first engages with the driver when the driver is moved in the counter driving direction; The plurality of engagement portions include an outer position engagement portion located outside a reference circle that is centered on the axis of the rotation shaft and passes through the first engagement portion when the wheel is located at the initial position, and an inner position engagement portion located inside the reference circle.

9. The driving tool according to claim 8, A driving tool in which the plurality of engagement portions are arranged on the wheel so as to contact the plurality of rack teeth at equal angular intervals as the wheel rotates.

10. The driving tool according to any one of claims 1 to 4, the plurality of engaging portions include a first engaging portion that first engages with the driver when the driver is moved in the counter driving direction, and a second engaging portion that engages with the driver next to the first engaging portion; A driving tool in which the advance / retreat engagement portion is the second engagement portion.

11. A driving tool, A piston that moves in the driving direction by gas pressure, a driver provided on the piston and moving integrally with the piston to strike the driving tool; a plurality of rack teeth formed on the driver along the driving direction; a wheel having a plurality of engaging portions on its outer periphery that engage with the plurality of rack teeth; The wheel has a shaft member on which the wheel is mounted so as to be non-rotatable and slidable in a radial direction as a rotation axis of the wheel, and the rotation of the wheel moves the driver in a direction opposite to the driving direction, When the driver is moved in the counter driving direction, the wheel slides relative to the shaft member from an initial position to a moved position away from the driver, The driver has tooth spaces between adjacent rack teeth, A driving tool, wherein the tooth groove includes a shallow tooth groove with which the wheel engages with one of the engagement portions when the wheel is in the initial position, and a deep tooth groove that is deeper than the shallow tooth groove and engages with one of the engagement portions when the wheel moves from the initial position to the moving position or when the wheel is in the moving position.

12. The driving tool according to claim 11, When the driver is moved in the counter-driving direction, the wheel returns from the moved position to the initial position, The tooth groove includes a second deep tooth groove that engages with one of the engagement portions when the wheel returns from the moving position to the initial position and is deeper than the shallow tooth groove.

13. The driving tool according to claim 11 or 12, The rack teeth have engaged surfaces that engage with the engaging portions of the wheels, the rack teeth include an advancing rack tooth that engages with one of the engaging portions when the wheel is at the moving position, and a returning rack tooth that engages with one of the engaging portions when the wheel returns from the moving position to the initial position, A driving tool in which the engaged surface of the return rack tooth is inclined in a direction toward the driving direction from the tooth tip to the tooth base of the return rack tooth with respect to a plane perpendicular to the axial direction of the driver, compared to the engaged surface of the advance rack tooth.

14. The driving tool according to claim 13, the rack teeth include an advancing rack tooth that engages with one of the engaging portions when the wheel moves from the initial position to the moving position, A driving tool in which the engaged surface of the advancing rack tooth is inclined in a direction toward the driving direction from the tip to the base of the advancing rack tooth with respect to a plane perpendicular to the axial direction of the driver, compared to the engaged surface of the post-advancing rack tooth.

15. The driving tool according to claim 13, The engaged surface of the post-advance rack tooth is inclined from the tip to the base of the post-advance rack tooth in the driving direction with respect to a plane perpendicular to the axial direction of the driver.

Images