Driving tool

Abstract

To provide a gas spring-type driving tool that moves a driver forward by gas pressure and makes a driving jig drive, and makes a lift mechanism return the driver to an upper stand-by position, which is configured so that gas pressure is applied indirectly to a planetary gear device that rotates a wheel when the wheel of the lift mechanism engages with the driver and which is configured so that durability of a gear housing can be improved while securing compactness of the planetary gear device.SOLUTION: An elastic body 50 is interposed between an aluminum die-cast molded second housing 47 and an internal gear 43d on a third stage planetary gear row 43. The elastic body 50 is made to receive and buffer force in a rotating direction applied through a lift mechanism 20 to the third stage planetary gear row 43, so that durability of the second housing 47 can be improved.SELECTED DRAWING: Figure 8

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 connected to the piston and moves downward as a unit to strike the driving tool. The piston and driver move downward in the driving direction due to the gas pressure in the pressure accumulator.

[0003] The piston and driver are returned in the direction opposite to the driving direction by a lift mechanism located on the side of the driving nose. The lift mechanism has a wheel that engages with the driver. The wheel is housed in a wheel housing that is integral with the driving nose. The wheel is rotated by an electric motor. The rotational output of the electric motor is transmitted to the wheel via a planetary gear device. A gear housing that houses the planetary gear device is connected to the wheel housing. The driver is returned in the direction opposite to the driving direction as the wheel is rotated by the electric motor. At this time, gas pressure from the pressure accumulator is applied to the driver. Patent Document 1 discloses a connection structure that increases the durability of the gear housing against the force (indirect action of gas pressure) applied to the gear housing via the planetary gear device when the driver is returned. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 6627990 Summary of the Invention [Problem to be solved by the invention]

[0005] The connection structure of Patent Document 1 has a meshing portion around the motor axis at the connecting portion of the wheel housing and the gear housing, and an elastic body is interposed in the meshing portion, making it difficult to make the planetary gear device compact in the motor axis direction.This disclosure aims to ensure the compactness of the planetary gear device while increasing the durability of the gear housing. [Means for solving the problem]

[0006] According to one aspect of the present disclosure, a driving tool includes a piston that advances in the driving direction, for example, by gas pressure, and a driver that is integral with the piston and advances to strike the driving tool. The driving tool includes, for example, a wheel that engages with the driver to retract the driver, and an electric motor that rotates forward to rotate the wheel and retract the driver. The driving tool includes, for example, a planetary gear device that reduces the output of the electric motor and outputs it to the wheel, and a gear housing that houses the planetary gear device. The driving tool includes, for example, an elastic body that is provided between the internal gear of the planetary gear device and the gear housing and that receives force from the internal gear when the electric motor rotates forward.

[0007] Therefore, when the screwdriver is moved backward in the counter-driving direction by the forward rotation of the electric motor, the force applied to the internal gear is borne by the elastic body. This increases the durability of the gear housing against the force received from the internal gear when the screwdriver is moved backward. Because the elastic body is provided between the internal gear of the planetary gear device and the gear housing, an increase in size in the direction of the central axis (direction of the motor axis) of the planetary gear device is avoided. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is an overall right side view of a driving tool according to a first embodiment. [Figure 2] 2 is a cross-sectional view taken along line II-II in FIG. 1, showing a vertical cross-sectional view of the tool body. FIG. [Figure 3] 3 is a cross-sectional view taken along the line III-III in FIG. 1, showing a cross-sectional view of the lift mechanism. [Figure 4] 4 is a cross-sectional view of the planetary gear device taken along line IV-IV in FIG. 1. FIG. [Figure 5] FIG. 4 is an enlarged view of a portion V in FIG. 3, showing the lift mechanism and the planetary gear unit. [Figure 6] 5. This is an enlarged view of the planetary gear device taken along the line VI-VI in FIG. [Figure 7] FIG. 2 is a perspective view of a third stage planetary gear train. [Figure 8] FIG. 10 is a perspective view showing a state in which a third-stage planetary gear train is housed in a second housing. [Figure 9] FIG. [Figure 10] FIG. 10 is a cross-sectional view of a planetary gear device according to a second embodiment. [Figure 11] FIG. 10 is an exploded perspective view of the carrier of the second-stage planetary gear train and the sun gear of the third-stage planetary gear train. DETAILED DESCRIPTION OF THE INVENTION

[0009] In one or more embodiments, for example, a planetary gear device includes a plurality of planetary gear trains arranged in series. The elastic body is interposed between the internal gear of the final planetary gear train and the gear housing. Therefore, the force applied from the final internal gear to the gear housing is buffered by the elastic body, thereby increasing the durability of the gear housing.

[0010] In one or more embodiments, for example, the internal gear has a plurality of outer peripheral protrusions that protrude radially outward. For example, the gear housing has a plurality of inner peripheral protrusions that protrude from its inner peripheral surface toward the internal gear. For example, an elastic body is interposed between each of the outer peripheral protrusions and the inner peripheral protrusions. For example, the rotational force applied via the outer peripheral protrusions when the driver is retracted is received by the elastic body. Therefore, the force around the central axis of the internal gear is reliably buffered by the elastic body.

[0011] In one or more embodiments, for example, the outer peripheral convex portion has an elastic body receiving surface that contacts the elastic body. The elastic body receiving surface extends, for example, perpendicular to a tangent to the outer peripheral surface of the internal gear. Therefore, the force around the central axis of the internal gear is efficiently applied to the elastic body. This allows efficient cushioning by the elastic body. Also, radial displacement of the elastic body is suppressed.

[0012] In one or more embodiments, the elastic body is, for example, a rubber member. For example, grooves are formed on the surface of the elastic body. The grooves facilitate elastic deformation of the elastic body. This prevents the elastic body from bulging out to the side, while providing efficient cushioning through the elastic deformation of the elastic body.

[0013] In one or more embodiments, the elastic body is, for example, a hexahedron. The elastic body has grooves, for example, a groove along the central axis direction of the internal gear and a groove perpendicular to the central axis direction. Therefore, a cross-shaped groove is provided on the surface of the elastic body. The cross-shaped groove suppresses lateral expansion of the elastic body, while the elastic body provides efficient cushioning.

[0014] In one or more embodiments, for example, the gear housing includes a first housing made of resin and a second housing made of metal that are joined together along the central axis of the internal gear. For example, the second housing houses the internal gear of the final stage of the planetary gear train. Therefore, the elastic body provides cushioning for the second housing. This increases the durability of the second housing made of metal.

[0015] In one or more embodiments, for example, the second housing has a boss portion for coupling that is inserted into the inner periphery of the first housing. For example, an elastic body is disposed on the same circumference as the boss portion. This allows the elastic body to be disposed between the second housing and the internal gear while avoiding an increase in the radial size of the second housing.

[0016] In one or more embodiments, for example, the driver reciprocates in a direction perpendicular to a line parallel to the central axis of the internal gear. The elastic body is disposed, for example, in an area on the opposite side of the internal gear from the driver, with respect to the central axis of the internal gear. Therefore, since the elastic body is not disposed in the area on the driver side, the gear housing can be made thinner. This allows for a more compact radial size of the driving nose portion of the gear housing, while the elastic body is disposed in a necessary area to cushion the gear housing.

[0017] In one or more embodiments, for example, a washer is provided that covers the internal gear and the elastic body and restricts the internal gear and the elastic body from being displaced in the axial direction of the internal gear. Therefore, the washer restricts the displacement of the internal gear and the elastic body in the axial direction of the internal gear. As a result, the displacement of the elastic body in the axial direction of the internal gear is restricted by the washer common to the internal gear, without the need for an additional restricting member.

[0018] In one or more embodiments, for example, a planetary gear device includes multiple planetary gear trains arranged in series along a power transmission path. The planetary gear train includes a sun gear, multiple planetary gears meshed with the sun gear, and a carrier that rotatably supports each of the multiple planetary gears. For example, the sun gear of a planetary gear train downstream of the power transmission path is provided on the carrier of an upstream planetary gear train, excluding the final stage of the power transmission path. For example, the carrier of the upstream planetary gear train and the sun gear of the downstream planetary gear train are connected by a separate member so that they can move relative to each other. Therefore, the sun gear moves relative to the carrier (with a suitable clearance), thereby aligning the sun gear with the multiple planetary gears that mesh with the sun gear. This reduces the load on the planetary gear train and increases the durability of the planetary gear train.

[0019] In one or more embodiments, for example, the sun gear and the carrier are separate components that are splined together, thereby ensuring the alignment of the planetary gear train while efficiently transmitting the power of the electric motor to the wheels. [Example]

[0020] Next, a first example, which is one of the embodiments of the present disclosure, will be described with reference to Figures 1 to 9. As an example of the driving tool 1, a gas spring type driving tool will be shown, which uses gas pressure in a pressure accumulator above a cylinder as thrust for driving a driving tool N. In the following description, the driving direction of the driving tool N will be referred to as a downward direction, and the opposite driving direction will be referred to as an upward direction. A user of the driving tool 1 is positioned approximately to the left of the driving tool 1 in Figure 1. The side in front of the user will be referred to as the rear direction (user side), and the back side opposite the front side will be referred to as the forward direction. The left and right directions are based on the user.

[0021] As shown in Figures 1 to 3, the driving tool 1 has a tool body 10. The tool body 10 has a configuration in which a cylinder 12 is accommodated in a generally cylindrical body housing 11. A piston 13 is accommodated in the cylinder 12 so that it can reciprocate up and down. 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, causing it to move downward (forward in the driving direction).

[0022] 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 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.

[0023] A vertically long driver 15 is connected to the underside of the piston 13. The lower part of the driver 15 enters the driving passage 2a. The driver 15 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 15 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 17 is arranged at the bottom of the cylinder 12 to absorb impact at the lower moving end of the piston 13.

[0024] A plurality of engaged portions 16 are provided on the right side of the driver 15. In the first embodiment, ten engaged portions 16 are arranged at regular intervals in the longitudinal direction (vertical direction) of the driver 15. Each engaged portion 16 is formed in a rack tooth shape and is provided so as to protrude to the right. The engaged portions 16 engage with an engaging portion 25 provided on the lift mechanism 20, which will be described later.

[0025] 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. A battery attachment 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 attachment section 6. The battery pack 7 can be removed from the battery attachment section 6 and repeatedly charged and used with a separately provided charger. The battery pack 7 can also 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.

[0026] 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 the driver 15 together upward after striking. When the lift mechanism 20 returns the piston 13 upward, the gas pressure in the pressure accumulator chamber 14 is increased.

[0027] A drive unit 30 for operating the lift mechanism 20 is provided in parallel 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 to the lower part of the battery attachment part 6. The drive unit case 11a is provided integrally with the main body housing 11. The main body housing 11 and the drive unit case 11a are made of resin and have a left and right half structure.

[0028] As shown in Figure 2, the lift mechanism 20 has a rotary shaft 21 connected to a planetary gear unit 40 (described later) and a wheel 22 supported by the rotary shaft 21. The wheel 22 is housed in a substantially cylindrical wheel case 29. The wheel case 29 is provided integrally with a lower case 12a that closes the lower part of the cylinder 12. A lower moving end damper 17 is held on the inner circumferential side of the lower case 12a.

[0029] The rotation axis of the rotary shaft 21 coincides with the motor axis J. The front side of the rotary shaft 21 is rotatably supported by a wheel case 29 via a bearing 26. The rear side of the rotary shaft 21 is connected to a carrier of the final stage of a planetary gear device 40. The carrier of the final stage of the planetary gear device 40 is rotatably supported by the wheel case 29 via a bearing 27 provided on the outer periphery. When the electric motor 31 is started (rotating forward), the rotary shaft 21 and the wheel 22 of the lift mechanism 20 rotate together in the direction of arrow R shown in FIG. 2 (counterclockwise in FIG. 2).

[0030] A plurality of engagement portions 25 are provided along the outer periphery of the wheel 22. In the first embodiment, for example, ten engagement portions 25 are provided. Each engagement portion 25 uses a cylindrical shaft member (pin). The ten engagement portions 25 are provided in an area covering approximately three-quarters of the circumference. The remaining area of ​​one-quarter of the circumference is used as a relief area where no engagement portions 25 are located.

[0031] 2, the left portion of the wheel 22 enters the driving passage 2a from inside the wheel case 29. Within the driving passage 2a, each engaging portion 25 of the wheel 22 engages with the engaged portion 16 of the driver 15. As the wheel 22 rotates in the direction of arrow R, the engaging portions 25 sequentially engage with the engaged portions 16 of the driver 15, causing the driver 15 and piston 13 to return upward.

[0032] As shown in Figure 3, the drive unit 30 has an electric motor 31 as a drive source. The electric motor 31 is housed in a motor case 32. The motor case 32 is held within the drive unit case 11a. The electric motor 31 is housed in an orientation in which the axis of the output shaft 33 (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 3). The electric motor 31 is powered by the power of the battery pack 7 and is started (rotated in the forward direction) when the trigger 5 is pulled.

[0033] An output shaft 33 of the electric motor 31 is rotatably supported by a motor case 32 via front and rear bearings 34, 35. A front portion of the output shaft 33 protrudes from the front portion of the motor case 32 and is connected to a planetary gear unit 40. A drive gear 33a is provided on the front portion of the output shaft 33.

[0034] The planetary gear device 40 is housed in a substantially cylindrical gear housing 45. The planetary gear device 40 uses a three-stage planetary gear train 41, 42, 43. The three-stage planetary gear trains 41, 42, 43 are 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 planetary gear device 40, which includes the three-stage planetary gear train 41, 42, 43, and is output to the lift mechanism 20.

[0035] The gear housing 45 has a first housing 46 made of resin and a second housing 47 made of metal that are joined together along the direction of the motor axis J. The first housing 46 made of resin houses the first stage planetary gear train 41 and the second stage planetary gear train 42. A rear portion 46a of the first housing 46 is joined to the front portion of the motor case 32.

[0036] The third stage planetary gear train 43 is housed in a metal second housing 47. The second housing 47 is integrally formed with the wheel case 29 of the lift mechanism 20. Therefore, in the first embodiment, the lower case 12a, the wheel case 29, and the second housing 47 are integrally formed with one another. In the first embodiment, the lower case 12a, the wheel case 29, and the second housing 47 are formed as an integral part made of aluminum die-cast.

[0037] As shown in Figure 5, the first stage planetary gear train 41 has three planetary gears 41a, one carrier 41b, and one internal gear 41c. The three planetary gears 41a are meshed with the drive gear 33a. The drive gear 33a corresponds to the sun gear of the first stage planetary gear train 41. The internal gear 41c is fixed along the inner surface of the first housing 46. The three planetary gears 41a are meshed with the internal gear 41c. The three planetary gears 41a are rotatably supported by one carrier 41b via support shafts 41d.

[0038] A sun gear 42a of the second-stage planetary gear train 42 is formed integrally with the front surface of the carrier 41b of the first-stage planetary gear train 41. Although not shown in the figure, a one-way clutch mechanism is interposed between the first-stage planetary gear train 41 and the second-stage planetary gear train 42 to restrict reverse rotation of the planetary gear device 40 (a rotational operation that rotates the wheel 22 in the direction opposite to the R direction).

[0039] Three planetary gears 42b mesh with the sun gear 42a. The three planetary gears 42b are rotatably supported by one carrier 42c via support shafts 42e. The three planetary gears 42b mesh with one internal gear 42d. The internal gear 42d is fixed along the inner surface of the first housing 46. An annular interposing member 44 is sandwiched between the internal gear 42d of the second-stage planetary gear train 42 and the internal gear 41c of the first-stage planetary gear train 41. This restricts displacement of the internal gears 41c, 42d in the direction of the motor axis J.

[0040] A sun gear 43a of the third-stage planetary gear train 43 is integrally formed on the front surface of the carrier 42c of the second-stage planetary gear train 42. The third-stage planetary gear train 43, which is the final stage, is housed in a second housing 47 made of metal. As shown in FIGS. 6 and 7, five planetary gears 43b mesh with the sun gear 43a. The five planetary gears 43b are rotatably supported by one carrier 43c via support shafts 43e. The five planetary gears 43b mesh with the inner periphery of one internal gear 43d.

[0041] 5, an annular interposing member 49 is sandwiched between the internal gear 43d of the third-stage planetary gear train 43 and the internal gear 42d of the second-stage planetary gear train 42. This restricts displacement of the internal gears 42d, 43d in the direction of the motor axis J.

[0042] The carrier 43c of the third-stage planetary gear train 43 is rotatably supported on the inner periphery of the second housing 47 via a bearing 27. The rotary shaft 21 is coupled to the carrier 43c via, for example, a spline shaft portion 21a. This allows the carrier 43c and the wheel 22 to rotate integrally. Therefore, when the electric motor 31 rotates forward, the carrier 43c rotates in the direction indicated by arrow C in FIG. 6, which causes the wheel 22 to rotate in the direction indicated by arrow R in FIG. 2, and the driver 15 is returned upward.

[0043] 6 and 7, the internal gear 43d is supported along the inner peripheral surface of the second housing 47. Four outer peripheral protrusions 43f are provided on the outer periphery of the internal gear 43d so as to protrude outward. Four inner peripheral protrusions 47a are provided on the inner peripheral surface of the second housing 47 so as to protrude inward.

[0044] One elastic body 50 is interposed between each of the four outer peripheral convex portions 43f and the four inner peripheral convex portions 47a. When the carrier 43c of the third-stage planetary gear train 43 rotates in the direction of arrow C in FIG. 6, a force P is applied to the internal gear 43d in the direction opposite to arrow C (the direction of arrow L). The force P is received by the four elastic bodies 50. The force P corresponds to an external force that is indirectly exerted by gas pressure applied to the driver 15 via the wheel 22 and the third-stage planetary gear train 43. The force P is applied intermittently in accordance with the engagement and disengagement of the engaging portion 25 of the wheel 22 with the engaged portion 16 of the driver 15.

[0045] Each outer peripheral protrusion 43f has an elastic body receiving surface 43g that comes into contact with the elastic body 50. Each elastic body receiving surface 43g extends perpendicular to a tangent to the outer peripheral surface of the internal gear 43d, thereby allowing the elastic body 50 to be elastically deformed efficiently by the force P.

[0046] 3 and 8, a boss portion 47b for coupling to the first housing 46 is provided at the rear end portion of the second housing 47. The boss portion 47b is formed in a circular ring shape that protrudes rearward along the rear end surface of the second housing 47. The boss portion 47b is inserted into the inner periphery of the front portion of the first housing 46, and the first housing 46 and the second housing 47 are coaxially coupled to each other.

[0047] As shown in Figures 6 and 8, four locations on the annular boss 47b are removed to accommodate four elastic bodies 50 on the same circumference. This allows the second housing 47 to be more compact in the radial direction than in a configuration in which a larger-diameter boss is provided continuously around the entire circumference of the elastic bodies 50. The four elastic bodies 50 are located in region E1, which is approximately halfway around the annular boss 47b and is on the side opposite the driver 15. By not locating elastic bodies 50 in region E2 on the driver 15 side, the second housing 47 can be placed closer to the driver 15. This allows the driving nose 2 to be more compact.

[0048] The thickness of the region E2 of the second housing 47, which is approximately halfway around the driver 15 side, is thinner than the thickness of the region E1 on the opposite side from the driver. This also allows the second housing 47 to be positioned closer to the driver 15, thereby making the driving nose 2 more compact.

[0049] One elastic body 50 is shown alone in Figure 9. In the first embodiment, each elastic body 50 is, for example, a hexahedral rubber member. Each elastic body 50 has an inner side surface 50a and an outer side surface 50b that are perpendicular to the radial direction of the second housing 47. The vertical length m and horizontal length n of the two side surfaces 50a, 50b are set to the same dimensions. A vertical groove 51 and a horizontal groove 52 are provided on the two side surfaces 50a, 50b so as to intersect in a cross shape.

[0050] When the electric motor 31 rotates forward, the elastic body 50 receives a force P from the outer peripheral convex portion 43f of the internal gear 43d and elastically deforms so that the groove width of the vertical groove 51 narrows. This prevents an increase in the thickness k of the elastic body 50 (a radial expansion of the second housing 47). Therefore, the elastic body 50 elastically deforms and efficiently absorbs the force P without requiring a large space to allow elastic deformation in the thickness k direction. This allows the second housing 47 to be made more compact in the radial direction.

[0051] Each elastic body 50 has two side surfaces 50a, 50b with the same vertical length m and horizontal length n (m = n). Each of the two side surfaces 50a, 50b has a vertical groove 51 and a horizontal groove 52 that intersect in a cross shape. This allows the elastic body 50 to be interposed between the outer peripheral convex portion 43f and the inner peripheral convex portion 47a, with the grooves inverted in the direction of the motor axis J, the direction in which the force P is applied, and the radial direction of the second housing 47. This improves the ease of assembly of the elastic body 50.

[0052] As shown in Fig. 5, one washer 48 is interposed between the third-stage planetary gear train 43 and the second-stage planetary gear train 42. The washer 48 covers the rear of the planet gear 43b, internal gear 43d, and elastic body 50 of the third-stage planetary gear train 43. This restricts displacement of the internal gear 43d and elastic body 50 in the direction of the motor axis J. The washer 48, which restricts displacement of the planet gear 43b and internal gear 43d of the third-stage planetary gear train 43, restricts displacement of the elastic body 50. Because displacement is restricted by a common member, displacement of the elastic body 50 in the direction of the motor axis J is restricted without incurring a complex configuration, as would be the case if a separate restricting member were added.

[0053] According to the first embodiment configured as described above, four elastic bodies 50 are interposed between the internal gear 43d of the planetary gear unit 40 and the second housing 47. The elastic bodies 50 receive the force P in the rotational direction (L direction) applied from the internal gear 43d when the driver 15 moves backward. This buffers the force P received from the internal gear 43d by the elastic bodies 50, thereby increasing the durability of the second housing 47.

[0054] According to the first embodiment, the elastic body 50 is provided between the internal gear 43d of the planetary gear device 40 and the second housing 47, thereby avoiding an increase in size in the central axis direction (direction of the motor axis J) of the planetary gear device 40.

[0055] According to the first embodiment, an elastic body 50 is interposed between each of the four outer peripheral convex portions 43f of the internal gear 43d and each of the four inner peripheral convex portions 47a of the second housing 47. The four elastic bodies 50 reliably buffer the force P in the rotational direction (L direction) that is applied to the second housing 47 via the internal gear 43d, thereby increasing the durability of the second housing 47.

[0056] According to the first embodiment, the outer peripheral protrusion 43f of the internal gear 43d has an elastic body receiving surface 43g that comes into contact with the elastic body 50. The elastic body receiving surface 43g extends perpendicular to a tangent to the outer peripheral surface of the internal gear 43d. This allows the force P about the central axis of the internal gear 43d to be efficiently applied to the elastic body 50. Therefore, cushioning by the elastic body 50 is efficiently performed. Furthermore, displacement and elastic deformation of the elastic body 50 in the radial direction (radial direction of the second housing 47) are suppressed.

[0057] According to the first embodiment, two side surfaces 50a, 50b of the elastic body 50 are provided with a vertical groove 51 extending in the direction of the motor axis J and a horizontal groove 52 extending in the direction of rotation about the motor axis J. Therefore, when the elastic body 50 receives a force P from the internal gear 43d and is elastically deformed during forward rotation of the electric motor 31 (when the driver 15 moves backward), the groove width of the vertical groove 51 narrows. This prevents the elastic body 50 from expanding sideways (in the radial direction of the second housing 47), while providing efficient cushioning through the elastic deformation of the elastic body 50.

[0058] According to the first embodiment, the gear housing 45 has a first housing 46 made of resin and a second housing 47 made of metal that are joined together along the central axis (motor axis J) of the internal gear 43d. The internal gear 43d of the third-stage planetary gear train 43, which is the final stage, is housed in the second housing 47. Therefore, the elastic body 50 cushions the second housing 47, thereby increasing its durability.

[0059] According to the first embodiment, the second housing 47 has a boss portion 47b for coupling that is inserted into the inner circumferential side of the first housing 46. The four elastic bodies 50 are arranged on the same circumference as the boss portion 47b. This prevents the second housing 47 from becoming large in the radial direction, and allows the elastic bodies 50 to be arranged efficiently between the second housing 47 and the internal gear 43d.

[0060] According to the first embodiment, the driver 15 reciprocates vertically, perpendicular to a line parallel to the central axis (motor axis J) of the planetary gear unit 40. The elastic body 50 is disposed in region E1, which is on the opposite side of the central axis of the planetary gear unit 40 from the driver 15. Therefore, the elastic body 50 is not disposed in region E2 on the driver 15 side, which makes it possible to thin region E2 of the second housing 47. This allows the second housing 47 of the driving nose 2 to be made more compact in the radial direction, while the elastic body 50 is disposed in a necessary region, cushioning the second housing 47.

[0061] According to the first embodiment, the rear of the third stage planetary gear train 43 is covered with one washer 48. The washer 48 restricts displacement of the planetary gear 43b, the internal gear 43d, and the elastic body 50 in the direction of the motor axis line J. This restricts displacement of the elastic body 50 without adding a separate restricting member, thereby avoiding a complicated configuration.

[0062] Various modifications can be made to the first embodiment described above. For example, although the configuration in which four elastic bodies 50 are interposed between the internal gear 43d and the second housing 47 has been exemplified, the number of elastic bodies may be changed to one or more than two.

[0063] Although the gear housing 45 that houses the planetary gear unit 40 is divided into a first housing 46 made of resin and a second housing 47 made of metal, the illustrated buffer mechanism can also be applied to an integrated gear housing. The gear housing may be made of either resin or metal.

[0064] Although a three-stage planetary gear train 41, 42, 43 has been exemplified, the present invention can be applied to a planetary gear device having a one-stage, two-stage, or four or more stages of planetary gear train.

[0065] Although a configuration in which an elastic body 50 is interposed between the third-stage planetary gear train 43 and the gear housing 45 has been exemplified, in addition to this, a configuration in which an elastic body is disposed between the first-stage or second-stage planetary gear train 41, 42 on the upstream side (the electric motor 31 side) and the gear housing 45 may also be used.

[0066] FIG. 10 shows a planetary gear unit 55 according to a second embodiment. The planetary gear unit 55 of the second embodiment has, from the upstream side (electric motor 31 side) of the power transmission path, a first-stage planetary gear train 41, a second-stage planetary gear train 56, and a third-stage planetary gear train 58. As in the first embodiment, an elastic body 50 is interposed between the third-stage planetary gear train 58 (the final stage) and the gear housing 45. The planetary gear unit 40 of the second embodiment differs from the first embodiment in that the carrier 57 of the second-stage planetary gear train 56, which is one stage before the final stage, and the sun gear 59 of the third-stage planetary gear train 58 are separate members. Members and configurations that do not require change will be designated by the same reference numerals and their description will be omitted.

[0067] As shown in Figure 11, for example, four planetary gears 42b are supported on a carrier 57 of a second-stage planetary gear train 56. Each of the four planetary gears 42b is rotatably supported via a support shaft 42e. The planetary gears 42b are meshed with a sun gear 42a. The sun gear 42a is integrally provided on a carrier 41b of the first-stage planetary gear train 41. The planetary gears 42b are meshed with an internal gear 42d. The internal gear 42d is fixed along the inner circumferential surface of a first housing 46 made of resin.

[0068] A circular recess 57a is provided on the front surface of the carrier 57. A coupling hole 57b is provided at the center of the recess 57a. The coupling hole 57b penetrates the carrier 57 in the thickness direction. The recess 57a and the coupling hole 57b are provided coaxially with the motor axis J. A spline hole is used for the coupling hole 57b.

[0069] A sun gear 59 is coupled to the front surface of the carrier 57. A flange portion 59a is provided at the rear of the sun gear 59. A coupling shaft portion 59b is provided at the rear surface of the flange portion 59a. A spline shaft is used for the coupling shaft portion 59b. The coupling shaft portion 59b is provided coaxially with the sun gear 59. The coupling shaft portion 59b is inserted into the coupling hole 57b, and the sun gear 59 is involute spline coupled to the front surface of the carrier 57. The spline coupling integrates the carrier 57 and the sun gear 59 with each other for rotation around the motor axis J.

[0070] The flange portion 59a is inserted into the bottomed recess 57a, thereby restricting rearward displacement of the sun gear 59. The washer 48 protrudes from the front side of the flange portion 59a, thereby restricting forward displacement of the sun gear 59.

[0071] As in the first embodiment, the final-stage planetary gear 43b meshes with the sun gear 59. The planetary gear 43b is supported by a carrier 43c. The rotary shaft 21 is splined to the center of the carrier 43c. The final-stage carrier 43c is supported on the inner periphery of the metal second housing 47 via a bearing 27.

[0072] According to the second embodiment, the sun gear 59 of the third-stage planetary gear train 58, which is the final stage, and the carrier 57 of the second-stage planetary gear train 56, which is adjacent to the final stage, are separate members. The sun gear 59 and the carrier 57, which are separate members, are splined together, thereby creating a primarily radial loose fit relationship between them. This provides an aligning effect for the sun gear 59 relative to the planet gear 43b of the third-stage planetary gear train 58. The aligning effect of the sun gear 59 reduces the load on the third-stage planetary gear train 58, thereby improving its durability.

[0073] A spline shaft portion may be provided on the carrier of the second-stage planetary gear train, and a spline hole may be provided on the sun gear of the third-stage planetary gear train, and the two may be spline-coupled.

[0074] Although the configuration in which the sun gear 59 of the final-stage third-stage planetary gear train 58 and the carrier 57 of the second-stage planetary gear train 56 adjacent to the final stage are spline-connected has been exemplified, the spline connection may be replaced by, for example, a connection between a hexagonal shaft portion and a hexagonal hole. By connecting a polygonal shaft portion (e.g., a hexagonal) with a polygonal hole, an appropriate clearance (mainly radial displacement) can be provided between the two, thereby enabling the sun gear 59 to be aligned with the final-stage planetary gear 43b.

[0075] In the second embodiment, the spline shaft portion 21a of the rotary shaft 21 may be omitted, and the rotary shaft 21 may be integrally provided with the carrier 43c of the third planetary gear train 58, which is the final stage.

[0076] In the second embodiment, in addition to or instead of the configuration in which the sun gear 59 of the final third-stage planetary gear train 58 is splined to the carrier 57 of the second-stage planetary gear train 56 (alignment action of the sun gear 59), the sun gear 42a of the second-stage planetary gear train 56 may be splined to the carrier 41b of the first-stage planetary gear train 41 (alignment action of the sun gear 42a).

[0077] The driving tool 1 of the first and second embodiments is an example of a driving tool in one aspect of the present disclosure. The piston 13 of the first and second embodiments is an example of a piston in one aspect of the present disclosure. The driver 15 of the first and second embodiments is an example of a driver in one aspect of the present disclosure. The driving tool N of the first and second embodiments is an example of a driving tool in one aspect of the present disclosure. The wheel 22 of the first and second embodiments is an example of a wheel in one aspect of the present disclosure. The electric motor 31 of the first and second embodiments is an example of an electric motor in one aspect of the present disclosure.

[0078] The planetary gear device 40 of the first and second embodiments is an example of a planetary gear device according to an aspect of the present disclosure. The second housing 47 of the first and second embodiments is an example of a gear housing according to an aspect of the present disclosure. The internal gear 43d of the first and second embodiments is an example of an internal gear according to an aspect of the present disclosure. The force P of the first and second embodiments is an example of a force according to an aspect of the present disclosure. The elastic body 50 of the first and second embodiments is an example of an elastic body according to an aspect of the present disclosure. [Explanation of symbols]

[0079] W: Material to be driven 1...Driving tool N...Driver 2...Driving nose part 2a... firing passage, 2b... ejection 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 12a...Lower case 13...Piston 14...Accumulation chamber 15...Driver 16...Engaged portion 17...Lower moving end damper 20...Lift mechanism 21...Rotation axis 21a...Spline shaft 22...Wheels 25...Engagement part 26, 27...Bearings 29…Wheel case 30...Drive unit 31...Electric motor J: Motor axis 32...Motor case 33...Output shaft 33a...Drive gear 34, 35...Bearings 40...Planetary gear unit 41...First stage planetary gear train 41a... planetary gear, 41b... carrier, 41c... internal gear, 41d... support shaft 42...Second stage planetary gear train 42a...Sun gear, 42b...Planet gear, 42c...Carrier, 42d...Internal gear 42e…Spindle 43...Third stage planetary gear train 43a...Sun gear, 43b...Planet gear, 43c...Carrier, 43d...Internal gear 43e...support shaft, 43f...periphery protrusion, 43g...elastic body receiving surface 44...Interposition member 45...Gear housing 46...First housing (plastic) 46a...rear 47...Second housing (metal) 47a...inner peripheral convex portion, 47b...boss portion 48...Washer 49...Interposition member 50...Elastic body 50a,50b…side 51...Vertical groove 52...Yokomizo 55...Planetary gear device (second embodiment) 56...Second stage planetary gear train 57...Career 57a...recess, 57b...coupling hole 58...Third stage planetary gear train 59...Sun Gear 59a... flange portion, 59b... connecting shaft portion

Claims

1. A driving tool, A piston that moves forward in the driving direction by gas pressure, a driver that is integral with the piston and moves forward to strike the driving tool; a wheel that engages the driver to cause the driver to move backward; an electric motor that rotates forward to rotate the wheel and move the driver backward; a planetary gear device that reduces the output of the electric motor and outputs the reduced output to the wheels; a gear housing that accommodates the planetary gear device; A driving tool having an elastic body provided between the internal gear of the planetary gear device and the gear housing, the elastic body receiving force from the internal gear when the electric motor is rotating in the forward direction.

2. The driving tool according to claim 1, The planetary gear device comprises a plurality of planetary gear trains arranged in series, The driving tool, wherein the elastic body is interposed between the internal gear of the final stage planetary gear train and the gear housing.

3. The driving tool according to claim 1 or 2, the internal gear has a plurality of outer peripheral protrusions that protrude radially outward, the gear housing has a plurality of inner peripheral protrusions protruding from an inner peripheral surface toward the internal gear, A driving tool in which the elastic body is interposed between each of the outer peripheral convex portion and the inner peripheral convex portion, and the rotational force applied through the outer peripheral convex portion when the driver is retracted is received by the elastic body.

4. The driving tool according to claim 3, The outer peripheral convex portion has an elastic body receiving surface that contacts the elastic body, and the elastic body receiving surface extends perpendicular to a tangent to the outer peripheral surface of the internal gear.

5. The driving tool according to claim 1 or 2, the elastic body is a rubber member, A driving tool in which a groove portion is formed on the surface of the elastic body.

6. The driving tool according to claim 5, the elastic body is a hexahedron, The driving tool has, as the groove portion, a groove that runs along the central axis direction of the internal gear and a groove that is perpendicular to the central axis direction.

7. The driving tool according to claim 2, the gear housing includes a first housing made of resin and a second housing made of metal that are joined together along a central axis of the internal gear, A driving tool in which the internal gear of the final stage of the planetary gear train is housed in the second housing.

8. The driving tool according to claim 7, the second housing has a boss portion for coupling that is inserted into the inner periphery of the first housing, The driving tool has the elastic body arranged coaxially with the boss portion.

9. The driving tool according to claim 1 or 2, the driver reciprocates in a direction perpendicular to a line parallel to the central axis of the internal gear, The elastic body is disposed in an area opposite the driver with respect to the central axis of the internal gear.

10. The driving tool according to claim 1 or 2, The driving tool has a washer that covers the internal gear and the elastic body and restricts the internal gear and the elastic body from being displaced in the direction of the central axis of the internal gear.

11. The driving tool according to claim 1 or 2, the planetary gear device comprises a plurality of planetary gear trains arranged in series along a power transmission path; the planetary gear train includes a sun gear, a plurality of planetary gears meshed with the sun gear, and a carrier that rotatably holds each of the plurality of planetary gears; the sun gear of the planetary gear train on the downstream side of the power transmission path is provided on the carrier of the planetary gear train on the upstream side of the power transmission path excluding the final stage, A driving tool in which the carrier of the upstream planetary gear train and the sun gear of the downstream planetary gear train are connected by separate members so as to be able to move relative to each other.

12. The driving tool according to claim 11, The sun gear and the carrier, which are separate members, are spline-connected to each other.

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