Impact tool

Abstract

To provide an impact tool that can suppress impact noise from being generated from a rear part of a housing, with a simple structure.SOLUTION: In an impact tool 1, a hammer 42 has a hammer body 420 and a hammer claw 421 and is rotated by driving force of a motor 3. An anvil 44 has an anvil shaft 441 in which a tip tool can be held on a tip, and an anvil claw 442, connected to the anvil shaft 441, which collides with the hammer claw 421 in a rotating direction of the hammer 42 as the hammer 42 rotates. A housing 2 houses at least a portion of the anvil 44, the hammer 42 and the motor 3. A holding base 5 is housed in the hosing 2, and is held in the housing 2 between the hammer 42 and the motor 3. At least a portion of the holding base 5 is formed of a hard member having sound insulation performance.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present disclosure relates to impact tools. [Background technology]

[0002] The impact tool of Patent Document 1 houses a motor and a hammer case in a housing. The hammer case includes an anvil to which a tool tip is attached and to which rotation is transmitted from the motor, and a striking mechanism that strikes the anvil. The striking mechanism includes a hammer and strikes the anvil.

[0003] The impact tool of Patent Document 1 further includes a noise suppression device for an impact tool to suppress noise generated from the impact tool. The noise suppression device for an impact tool includes a cover member that covers the hammer case from the front, a spring receiving member that is integral with the tool bit, and a coil spring that is disposed between the cover member and the spring receiving member. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2013-248703 A Summary of the Invention [Problem to be solved by the invention]

[0005] In an impact tool, an impact sound is generated by the collision between the anvil and the hammer inside the housing. This impact sound tends to propagate inside the housing from the front side where the anvil and the hammer are located to the rear side where the motor is located. In other words, the impact sound generated inside the housing tends to propagate from the front to the rear inside the housing. As a result, the impact sound emitted from the rear of the housing is relatively loud.

[0006] An object of the present disclosure is to provide an impact tool that can suppress impact noise emitted from a rear part of the housing with a simple structure. [Means for solving the problem]

[0007] An impact tool according to one aspect of the present disclosure includes a motor, a hammer, an anvil, a bearing, a housing, and a holder. The motor generates a driving force. The hammer has a hammer body and a hammer claw connected to the hammer body, and rotates by the driving force of the motor. The anvil has an anvil shaft capable of holding a tool tip at a tip in a direction of a rotation axis of the hammer, and an anvil claw connected to the anvil shaft and colliding with the hammer claw in a rotation direction of the hammer as the hammer rotates. The bearing rotatably supports the anvil shaft. The housing accommodates at least a part of the anvil, the hammer, and the motor. The holder is accommodated in the housing and is held by the housing between the hammer and the motor. At least a part of the holder is formed of a hard member having sound insulation properties. Effect of the Invention

[0008] According to the present disclosure, it is possible to suppress impact noise emitted from the rear of the housing with a simple structure. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a perspective view showing an impact tool according to an embodiment. [Diagram 2] FIG. 2 is a side cross-sectional view showing the impact tool. [Diagram 3] FIG. 3 is an exploded perspective view showing the impact tool. [Figure 4] FIG. 4 is a side cross-sectional view showing a boundary portion of the impact tool. [Diagram 5] FIG. 5 is a perspective view showing a hammer and an anvil of the impact tool. [Figure 6] FIG. 6 is an exploded perspective view showing a holding portion, a planetary gear mechanism, and a partition wall of the impact tool. [Figure 7] FIG. 7 is an exploded perspective view showing a holding portion and a planetary gear mechanism of the impact tool. [Figure 8] FIG. 8 is a perspective view showing a holding portion of the impact tool. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] The present disclosure relates generally to impact tools, and more particularly to an impact tool having a housing in which at least a portion of an anvil and a hammer are housed.

[0011] (Embodiment) Hereinafter, an impact tool according to an embodiment will be described with reference to the drawings. However, the following embodiment is merely one of various embodiments of the present disclosure. The following embodiment can be modified in various ways depending on the design, etc., as long as the object of the present disclosure can be achieved. In addition, each figure described in the following embodiment is a schematic diagram, and the size and thickness ratios of each component in the figure do not necessarily reflect the actual dimensional ratios.

[0012] In the following description, the direction in which the motor 3 and the hammer 42 are lined up in Fig. 2 is defined as the front-rear direction, the hammer 42 side as viewed from the motor 3 is defined as the front, and the motor 3 side as viewed from the hammer 42 is defined as the rear. In the following description, the direction in which the second part 22 and the grip part 24 are lined up in Figs. 1 and 2 is defined as the up-down direction, the second part 22 side as viewed from the grip part 24 is defined as the up, and the grip part 24 side as viewed from the second part 22 is defined as the down. In addition, the direction perpendicular to the front-rear direction and the up-down direction is defined as the left-right direction. However, these definitions are not intended to define the direction in which the impact tool is used.

[0013] (overview) As shown in FIG. 1 to FIG. 8, the impact tool 1 of this embodiment includes a motor 3, a hammer 42, an anvil 44, a bearing 49, a housing 2, and a holder 5. The hammer 42 generates a driving force. The hammer 42 has a hammer body 420 and a hammer claw 421 connected to the hammer body 420, and rotates by the driving force of the motor 3. The anvil 44 has an anvil shaft 441 capable of holding a tool tip at the tip in the direction of the rotation axis of the hammer 42, and an anvil claw 442 connected to the anvil shaft 441 and colliding with the hammer claw 421 in the rotation direction of the hammer 42 as the hammer 42 rotates. The bearing 49 rotatably supports the anvil shaft 441. The housing 2 accommodates at least a part of the anvil 44, the hammer 42, and the motor 3. The holder 5 is accommodated in the housing 2 and is held by the housing 2 between the hammer 42 and the motor 3. At least a part of the support table 5 is made of a hard material having sound insulation properties.

[0014] In the impact tool 1, the impact sound is generated by the collision between the hammer claw 421 and the anvil claw 442 in the housing 2, and the impact sound is likely to propagate from the front to the rear in the housing 2. Therefore, in the impact tool 1, at least a part of the holding base 5 held by the housing 2 in the housing 2 is formed from a hard material having sound insulation performance. As a result, the impact sound generated in the housing 2 and propagating from the front to the rear in the housing 2 is attenuated by hitting the holding base 5. In other words, with the simple structure in which at least a part of the holding base 5 is formed from a hard material having sound insulation performance, the impact sound reaching the rear part of the housing 2 can be reduced, and the impact sound emitted from the rear part of the housing 2 can be suppressed. Therefore, the impact tool 1 can suppress the impact sound emitted from the rear part of the housing 2 with a simple structure.

[0015] Furthermore, the housing 2 vibrates due to the impact force applied to the hammer 42 and the anvil 44. Sound generated by this vibration of the housing 2 is damped by the holding base 5 held by the housing 2. As a result, the sound generated by the vibration of the housing 2 can also be suppressed with a simple structure.

[0016] (detail) (1) Overall structure The impact tool 1 of this embodiment will be described in detail below.

[0017] The impact tool 1 of this embodiment is a portable power tool. The impact tool 1 is, for example, an electric impact wrench, which attaches fastening parts (bolts, nuts, etc.) to a work object and loosens the fastening parts attached to the work object. As shown in Fig. 2, the impact tool 1 includes a housing 2, a motor 3, a transmission mechanism 4, a holder 5, a drive circuit block 81, a control unit 82, and an operation unit 83.

[0018] (2) Housing 2, the housing 2 accommodates the motor 3, the transmission mechanism 4, the holder 5, a drive circuit block 81, and a control unit 82. The housing 2 has a first section 21, a second section 22, a grip section 24, and an attachment section 25. The first section 21 accommodates at least a part of the anvil 44 and the hammer 42. The second section 22 accommodates the motor 3. The first section 21 constitutes a motor case, and the second section 22 constitutes a drive section cover.

[0019] The first region 21 and the second region 22 are formed of separate members. A rear end of the first region 21 and a front end of the second region 22 form a boundary portion 23 where the first region 21 and the second region 22 contact each other.

[0020] (2.1) First part As shown in FIGS. 1 to 3, the first portion 21 has a cylindrical shape and includes a front wall 211, a side wall 212, and four mounting pieces 213.

[0021] The front wall 211 is disk-shaped. A through-hole 214 having a circular cross section is formed in the center of the front wall 211. An anvil shaft 441 of an anvil 44 (described later) housed in the first section 21 is inserted into the through-hole 214. A tip (front end) of the anvil shaft 441 is located forward of the front end of the first section 21. The side wall 212 is cylindrical and extends rearward from the outer circumferential edge of the front wall 211.

[0022] The four mounting pieces 213 are formed in a convex shape that protrudes outward from the peripheral edge of the rear end of the side wall 212. The mounting pieces 213 are formed with insertion holes 2131 (see FIG. 3) through which the screws B1 (see FIG. 1 and FIG. 3) are inserted.

[0023] 2, the first section 21 has an internal space 210 that is surrounded by a front wall 211 and a side wall 212 and has a circular cross section with an open rear face, and accommodates at least a part of an anvil 44 (described later) and the hammer 42 in the internal space 210. A part (a front part of the holder 5) (described later) is also accommodated in the internal space 210. The internal space 210 has a larger diameter at the rear end side than at the front end side, and the diameter increases toward the rear, forming a so-called bell shape.

[0024] (2.2)Second part As shown in FIGS. 1-3, the second portion 22 has a cylindrical shape and includes a rear wall 221, a side wall 222, and four mounting pieces 223.

[0025] The rear wall 221 has a disk shape. The side wall 222 has a cylindrical shape extending forward from the outer periphery of the rear wall 221.

[0026] The four mounting pieces 223 are formed in a convex shape that protrudes outward from the periphery of the front end of the side wall 222. The mounting pieces 223 are formed with screw holes 2231 (see FIG. 3) into which screws B1 (see FIG. 1 and FIG. 3) are screwed.

[0027] 2, the second section 22 has an internal space 220 that is circular in cross section and open at the front and is surrounded by a rear wall 221 and a side wall 222. The internal space 220 has a cylindrical shape extending in the front-rear direction.

[0028] 2 and 6, a disk-shaped partition wall 226 is formed slightly rearward of the front end (front opening) of the internal space 220, facing the rear wall 221 in the front-rear direction. The partition wall 226 divides the internal space 220 into an internal space 220a behind the partition wall 226 and an internal space 220b in front of the partition wall 226. The internal space 220a accommodates the motor 3, which will be described later. The internal space 220b also accommodates a part of the holder 5, which will be described later (the rear part of the holder 5).

[0029] (2.3) Boundary The boundary portion 23 is a portion where the rear end of the first portion 21 and the front end of the second portion 22 contact each other. That is, the boundary portion 23 is a portion that includes the rear end of the internal space 210 and the front end of the internal space 220b.

[0030] 4, an annular protruding wall 215 is formed on the inner periphery of the rear end face of the side wall 212 of the first portion 21, and an annular notch 216 is formed on the outer periphery of the rear end face of the side wall 212. An annular protruding wall 224 is formed on the outer periphery of the front end face of the side wall 222 of the second portion 22, and an annular notch 225 is formed on the inner periphery of the rear end face of the side wall 222. The protruding wall 215 and notch 216 of the first portion 21 and the protruding wall 224 and notch 225 of the second portion 22 constitute the boundary portion 23.

[0031] Then, the rear end surface of side wall 212 and the front end surface of side wall 222 are opposed to each other, and protruding wall 215 is fitted into notch 225 and protruding wall 224 is fitted into notch 216, so that the rear end portion of first portion 21 and the front end portion of second portion 22 come into contact with each other.

[0032] Furthermore, the first part 21 and the second part 22 are connected by screwing. More specifically, as shown in Fig. 3, the insertion holes 2131 provided in the four mounting pieces 213 of the first part 21 correspond one-to-one to the screw holes 2231 provided in the four mounting pieces 223 of the second part 22, and the corresponding insertion holes 2131 and screw holes 2231 are aligned. Then, the screw B1 is inserted through the insertion hole 2131 and screwed into the screw hole 2231, thereby connecting the first part 21 and the second part 22.

[0033] (2.4) Grip The grip portion 24 protrudes from the second portion 22. More specifically, the grip portion 24 protrudes from a side surface of the second portion 22. The grip portion 24 protrudes downward from the second portion 22. An operator can grasp the grip portion 24 to perform a fastening operation of a fastening member such as a screw.

[0034] (2.5) Mounting Part As shown in FIG. 1, the mounting part 25 has a rectangular parallelepiped shape. The mounting part 25 is connected to the lower end of the grip part 24. A rechargeable battery pack (not shown) is detachably attached to the mounting part 25. The impact tool 1 operates using the battery pack as a power source. In other words, the battery pack is a power source that supplies power to drive the motor 3. The battery pack may or may not be a component of the impact tool 1. The battery pack includes a battery pack configured by connecting a plurality of secondary batteries (e.g., lithium ion batteries) in series, and a case that houses the battery pack.

[0035] (3) Motor As shown in FIG. 2, the motor 3 is accommodated in the internal space 220a of the second portion 22 of the housing 2. The motor 3 is, for example, a brushless motor. The motor 3 includes a rotor 31 having a rotating shaft 311 and a permanent magnet, and a stator 32 having a coil. The rotor 31 rotates relative to the stator 32 due to electromagnetic interaction between the permanent magnet and the coil. The rotation of the rotor 31 causes the motor 3 to generate a driving force. The rotating shaft 311 is disposed so as to extend in the front-rear direction, and passes through an insertion hole 2262 of a partition wall 226 of the second portion 22 (see FIGS. 2 and 6). The tip (front end) of the rotating shaft 311 is located forward of the partition wall 226. The rotating shaft 311 rotates as the rotor 31 rotates.

[0036] The motor 3 is a servo motor. The torque and rotation speed of the motor 3 change according to the control by the control unit 82 (servo driver).

[0037] (4)Operation unit As shown in Figs. 1 and 2, the operating unit 83 protrudes from the grip portion 24. The operating unit 83 receives operations for controlling the rotation of the rotating shaft 311 of the motor 3. The motor 3 can be switched on and off by pulling the operating unit 83. In addition, the rotation speed of the rotating shaft 311 can be adjusted by the pulling amount of the operating unit 83. The larger the pulling amount, the faster the rotation speed of the rotating shaft 311.

[0038] (5) Control section The control unit 82 includes, for example, a microcontroller. The control unit 82 rotates or stops the rotating shaft 311 according to the pulling amount of the operation of pulling the operating unit 83, and also controls the rotation speed of the rotating shaft 311. The control unit 82 controls the rotation speed of the rotating shaft 311 by feedback control that controls the torque and rotation speed of the motor 3 so as to approach target values. The control unit 82 changes the rotation speed of the rotating shaft 311 by, for example, changing the power supplied to the motor 3.

[0039] The control unit 82 can change the rotation speed of the rotation shaft 311 to change the rotation speed of an anvil shaft 441 and a tool tip, which will be described later.

[0040] (6) Drive circuit block As shown in Fig. 2, the drive circuit block 81 is disposed behind the motor 3. The drive circuit block 81 includes a substrate and a plurality of electronic components mounted on the substrate. The plurality of electronic components include a plurality of power elements that configure an inverter circuit. Each of the power elements is, for example, a field effect transistor (FET) element.

[0041] The control unit 82 controls the motor 3 via the drive circuit block 81. That is, the control unit 82 controls the power supplied to the motor 3 via a plurality of FET elements (inverter circuits) by switching the plurality of FET elements of the drive circuit block 81 on and off.

[0042] (7) Transmission mechanism As shown in FIG. 2, the transmission mechanism 4 includes an impact mechanism 40, a planetary gear mechanism 48, and a bearing 49.

[0043] The impact mechanism 40 is configured to perform an impact operation that applies an impact force in the rotational direction of an anvil 44, which will be described later, when the tightening torque (load torque) that tightens the fastening parts exceeds a predetermined value. The impact force acts on a tool tip (not shown) attached to the tip of an anvil shaft 441, which will be described later. This makes it possible to apply a larger tightening torque to the fastening parts. In other words, the impact tool 1 is an electric impact driver that performs a fastening operation such as screw tightening while performing an impact operation by the impact mechanism 40.

[0044] The impact mechanism 40 includes a drive shaft 41, a hammer 42, a coil spring 43, an anvil 44, and two spherical steel balls 45. The drive shaft 41, the hammer 42, the coil spring 43, the steel balls 45, and a bearing 49 are housed in an internal space 210 of the first section 21. An anvil body 440, anvil claws 442, and a rear portion of anvil shaft 441 (described later) of the anvil 44 are housed in the internal space 210 of the first section 21. A front portion of the anvil shaft 441 is exposed to the front side of the first section 21.

[0045] The planetary gear mechanism 48 is housed in a holder 5, which will be described later, and is located within the housing 2 so as to face the boundary portion 23 of the housing 2 (see FIGS. 6 and 7). The holder 5 rotatably holds at least one gear included in the planetary gear mechanism 48. Details of the holder 5 will be described later.

[0046] As shown in Figs. 2, 6 and 7, the planetary gear mechanism 48 includes a sun gear 481, two planetary gears 482, and an annular internal gear 483. The sun gear 481 is located at the center of the internal gear 483, and is connected to the front end of the rotating shaft 311 of the motor 3, and rotates together with the rotating shaft 311. The planetary gear 482 is meshed with the sun gear 481 and the internal gear 483 between the sun gear 481 and the internal gear 483, and rotates on its own axis by the driving force transmitted from the sun gear 481 and revolves around the internal gear 483. A cylindrical drive shaft 41 extending along the front-rear direction is disposed in front of the planetary gear mechanism 48. The drive shaft 41 is connected to the two planetary gears 482, and the revolution motion of the planetary gear 482 is transmitted to the drive shaft 41, causing the drive shaft 41 to rotate. 2 and 5, a flange 411 is integrally formed at the rear end of the drive shaft 41. The shafts 484 (see FIG. 2) of the two planetary gears 482 are inserted into the flange 411, whereby the drive shaft 41 is connected to the two planetary gears 482.

[0047] The planetary gear mechanism 48 is a reduction gear device that converts the rotation speed and torque of the rotating shaft 311 of the motor 3 into a rotation speed and torque for rotating the fastening member. The torque of the rotating shaft 311 of the motor 3 is transmitted to the drive shaft 41 via the planetary gear mechanism 48. This causes the drive shaft 41 to rotate.

[0048] Two grooves 413 (see FIG. 2), which are semicircular grooves in cross section, are formed on the outer circumferential surface of the drive shaft 41. Each of the two grooves 413 extends on the outer circumferential surface of the drive shaft 41 in a direction inclined toward a direction intersecting the axial direction.

[0049] The hammer 42 is made of metal. The hammer 42 rotates by torque transmitted via the drive shaft 41, thereby rotating the anvil 44. Furthermore, the hammer 42 applies a striking force to the anvil 44 in the rotational direction by moving (translating) in the front-rear direction relative to the anvil 44 while rotating.

[0050] Specifically, as shown in Figures 2 and 5, the hammer 42 includes a cylindrical hammer body 420 and a pair of hammer claws 421 which are protrusions. The pair of hammer claws 421 are arranged at 180 degree intervals on the circular front surface of the hammer body 420. A through hole 422 penetrating in the front-rear direction is formed in the center of the hammer body 420 by a cylinder extending in the front-rear direction. The cross section of the through hole 422 is circular. The drive shaft 41 penetrates the through hole 422 in the front-rear direction.

[0051] Two grooves 423 (see FIG. 2), each of which is a semicircular groove in cross section, are formed on the inner circumferential surface of the through hole 422 of the hammer body 420. Each of the two grooves 423 extends on the inner circumferential surface of the through hole 422 in a direction inclined toward a direction intersecting the axial direction.

[0052] Two steel balls 45 are sandwiched between the two grooves 413 of the drive shaft 41 and the two grooves 423 of the hammer 42. The steel balls 45 are spherical. The two grooves 413 of the drive shaft, the two grooves 423 of the hammer 42, and the two steel balls 45 constitute a cam mechanism. That is, the torque of the drive shaft 41 is transmitted to the hammer 42 via the two steel balls 45, and the hammer 42 rotates. The steel balls 45 are housed in a cam groove formed by the grooves 413 and 423, and can move within the cam groove. The two steel balls 45 move along the cam groove, and the hammer 42 can move in the axial direction (front-rear direction) relative to the drive shaft 41. The two cam grooves are symmetrical with respect to one imaginary plane passing through the axial direction of the drive shaft 41.

[0053] Further, a coil spring 43 is provided behind the hammer body 420, and the coil spring 43 applies a spring force in the forward direction to the hammer 42. The hammer 42 moves backward against the spring force of the coil spring 43, and the retracted hammer 42 moves forward due to the spring force.

[0054] The anvil 44 is disposed in front of the hammer 42. The anvil 44 is made of metal. The anvil 44 rotates by the torque transmitted from the rotating hammer 42.

[0055] Specifically, as shown in FIG. 2 and FIG. 5, the anvil 44 includes an anvil body 440, an anvil shaft 441, and a pair of anvil claws 442. The anvil body 440 is cylindrical. The anvil shaft 441 is connected to the anvil body 440 and protrudes forward from the front surface of the anvil body 440 along the axial direction. The anvil shaft 441 corresponds to an output shaft protruding forward from the front surface of the anvil body 440. The pair of anvil claws 442 are arranged at 180 degree intervals on the outer periphery of the anvil body 440 and protrude from the side surface of the anvil body 440 in the radial direction of the anvil body 440. The anvil body 440 faces the hammer body 420 in the front-rear direction. The anvil claws 442 collide with the hammer claws 421 in the rotation direction of the hammer 42 as the hammer 42 rotates.

[0056] A tool tip (not shown) is attached to the tip (front end) of the anvil shaft 441. That is, the anvil shaft 441 has a structure capable of holding a tool tip at its tip in the direction of the rotation axis of the hammer 42. The tool tip is a bit for rotating fastening parts such as bolts and nuts.

[0057] The outer circumferential surface of the anvil 44 is supported by a bearing 49 (see FIG. 2). The bearing 49 rotatably supports the anvil 44. In this embodiment, the bearing 49 includes a first bearing 491 and a second bearing 492. The first bearing 491 is configured as a roller bearing that supports the outer periphery of the anvil body 440. The second bearing 492 is configured as a ball bearing that supports the outer periphery of the anvil shaft 441. The bearing 49 suppresses rocking, vibration, etc. of the rotating anvil 44. It is sufficient that the bearing 49 has a configuration that at least rotatably supports the anvil shaft 441.

[0058] Then, the drive shaft 41 is rotated by the torque transmitted from the motor 3 via the planetary gear mechanism 48, and the hammer 42 receives the torque transmitted from the drive shaft 41 via the above-mentioned cam mechanism and rotates around the drive shaft 41 as a rotation axis. If the hammer 42 is not performing an impact operation, the hammer 42 and the anvil 44 rotate together while the pair of hammer claws 421 of the hammer 42 contacts the pair of anvil claws 442 of the anvil 44 in the rotation direction. When the anvil 44 rotates, the anvil shaft 441 also rotates, and the tool bit also rotates. As a result, the fastening member also rotates due to the torque of the tool bit.

[0059] As the fastening member rotates and is tightened into a screw hole or the like, the axial force increases, and the fastening torque of the fastening member increases. When the fastening torque increases, the component of the force generated between the hammer 42 and the anvil 44 that moves the hammer 42 backward also increases. When the fastening torque reaches a predetermined value or more, the hammer 42 moves backward against the spring force of the coil spring 43. As the hammer 42 moves backward, the pair of hammer claws 421 of the hammer 42 climbs over the two anvil claws 442 of the anvil 44, and the hammer 42 rotates. Thereafter, the hammer 42 moves forward by the spring force of the coil spring 43. When the drive shaft 41 rotates approximately half a turn, the pair of hammer claws 421 of the hammer 42 collide with the side surfaces of the pair of anvil claws 442 of the anvil 44. That is, the hammer claws 421 collide with the anvil claws 442 every time the drive shaft 41 rotates approximately half a turn. That is, the hammer 42 applies a striking force (rotational striking force) to the anvil 44 every time the drive shaft 41 rotates approximately half a turn while repeatedly moving backward and forward.

[0060] (8) Holding stand The holder 5 is accommodated in the housing 2 and is held by the housing 2 between the hammer 42 and the motor 3 .

[0061] Specifically, the holder 5 is held on the inner surface of the housing 2 so that the outer circumferential surface of the holder 5 faces the boundary portion 23 of the housing 2. As shown in Figs. 6 to 8, the holder 5 has a cylindrical shape and includes a rear wall 51 and a side wall 52.

[0062] The rear wall 51 has a disk shape. As shown in FIG. 8, a first cylinder 53 extending rearward is formed at the center of the rear surface of the rear wall 51. A second cylinder 54 extending further rearward is formed on the rear surface of the first cylinder 53. A through hole 55 having a circular cross section is formed on the bottom surface of the second cylinder 54. The rotary shaft 311 of the motor 3 is inserted through the through hole 55. Two rectangular projections 56 extending from the side surface of the first cylinder 53 toward the outer periphery of the rear wall 51 are formed on the rear surface of the rear wall 51. The two projections 56 are arranged at 180 degree intervals on the outer periphery of the first cylinder 53 and protrude from the side surface of the first cylinder 53 in the radial direction of the first cylinder 53. The side wall 52 has a cylindrical shape extending forward from the outer periphery of the rear wall 51.

[0063] The support base 5 is disposed in front of the partition 226 with the rear wall 51 facing the partition 226 of the second section 22. As shown in Fig. 6, a substantially rectangular recess 2261 extending in the diameter direction is formed in the circular front surface of the partition 226. The width dimension of the center of the recess 2261 is larger than the width dimensions of both ends of the recess 2261. A through hole 2262 having a circular cross section is formed in the center of the recess 2261.

[0064] When the holder 5 is placed on the front surface of the partition wall 226, the protrusion 56 of the holder 5 is fitted into the recess 2261 of the partition wall 226, and the second cylinder 54 of the holder 5 is fitted into the insertion hole 2262 of the partition wall 226. As a result, the holder 5 is positioned with respect to the partition wall 226. The rotating shaft 311 of the motor 3 passes through the insertion hole 2262 of the partition wall 226 and the insertion hole 55 of the holder 5, and the tip (front end) of the rotating shaft 311 is positioned inside the holder 5. Then, the outer peripheral surface of the side wall 52 of the holder 5 is in close contact with the inner surface of the boundary portion 23, so that the holder 5 is held by the housing 2.

[0065] The planetary gear mechanism 48 is housed inside the side wall 52 of the support base 5. An annular internal gear 483 of the planetary gear mechanism 48 is attached to the side wall 52 along the inner circumference of the side wall 52. A sun gear 481 of the planetary gear mechanism 48 is located at the center of the annular internal gear 483. The front end of the rotating shaft 311 of the motor 3 is fitted into the rear end of the sun gear 481, and the sun gear 481 rotates together with the rotating shaft 311. The two planetary gears 482 of the planetary gear mechanism 48 are engaged with the sun gear 481 and the internal gear 483 between the sun gear 481 and the internal gear 483. The shafts 484 (see FIG. 2) of the two planetary gears 482 are inserted into the flange 411 of the drive shaft 41, so that the drive shaft 41 is connected to the two planetary gears 482.

[0066] Then, when the rear end of the first part 21 comes into contact with the front end of the second part 22 and the first part 21 is assembled to the second part 22, the holding base 5 is held on the inner surface of the housing 2 such that the outer peripheral surface of the holding base 5 faces the boundary part 23 of the housing 2. That is, the front end of the holding base 5 is located in the internal space 210 of the first part 21, and the rear end of the holding base 5 is located in the internal space 220b of the second part 22. In other words, the holding base 5 is located from the rear part of the internal space 210 of the first part 21 to the front part of the internal space 220 (220b) of the second part 22.

[0067] At least a part of the holding table 5 is made of a hard material having sound insulation properties. In this embodiment, the entire holding table 5 is made of a hard material having sound insulation properties.

[0068] In the impact tool 1, a drive shaft 41 extends forward from a planetary gear mechanism 48 held by a holder 5. A hammer 42 is attached to the front end of the drive shaft 41, and an anvil 44 is located in front of the hammer 42. Therefore, the hammer 42 and the anvil 44 are located in the internal space 210 of the first portion 21.

[0069] In the impact tool 1, the hammer claw 421 of the hammer 42 collides with the anvil claw 442 of the anvil 44, thereby performing an impact operation. At this time, the hammer claw 421 collides with the anvil claw 442 in the internal space 210 of the first part 21, generating an impact sound in the internal space 210. The internal space 210 has a so-called bell-shaped shape in which the diameter at the rear end side is larger than the diameter at the front end side, and the diameter increases toward the rear. In other words, the internal space 210 of the first part 21 has a shape in which the diameter increases toward the internal space 220 of the second part 22. Therefore, the impact sound generated in the internal space 210 is likely to propagate toward the rear of the internal space 210.

[0070] Therefore, in the impact tool 1 of this embodiment, the entire holding base 5 is formed of a hard material having sound insulation properties. As a result, the impact sound generated by the hammer claws 421 and the anvil claws 442 travels backward in the internal space 210, but is attenuated by hitting the holding base 5 near the boundary portion 23. Since the holding base 5 is formed of a hard material having sound insulation properties, the attenuation of the impact sound is greater than when a holding base made of resin or the like is used. Therefore, the impact sound propagating from the internal space 210 of the first portion 21 to the internal space 220b of the second portion 22 is suppressed, and the impact sound propagating from the second portion 22 (particularly the rear wall 221 of the second portion 22) to the outside of the housing 2 is suppressed.

[0071] It is not essential that the entire holding base 5 be made of a hard material having sound insulation properties. As long as sufficient sound insulation properties can be ensured, a portion of the holding base 5 may be made of a hard material having sound insulation properties, and the remainder of the holding base 5 may be made of resin or the like.

[0072] In this way, the impact tool 1 can reduce the impact noise that reaches the rear part of the housing 2 and suppress the impact noise emitted from the rear part of the housing 2 by using a simple structure in which at least a part of the holding base 5 is made of a hard material having sound insulation properties. Therefore, the impact tool 1 can suppress the impact noise emitted from the rear part of the housing 2 with a simple structure.

[0073] Furthermore, the housing 2 vibrates due to the impact force applied to the hammer 42 and the anvil 44. Sound generated by this vibration of the housing 2 is damped by the holding base 5 held by the housing 2. As a result, the sound generated by the vibration of the housing 2 can also be suppressed with a simple structure.

[0074] The higher the density of the hard member forming the holding base 5, the higher the sound insulation performance. However, the higher the density of the hard member, the heavier the impact tool 1 becomes, making it difficult for the operator to handle the impact tool 1. Therefore, the density of the hard member is set to 2.0 g / cm 3 More than 12.0g / cm 3 The density is preferably 2.0 g / cm or less. 3 is the maximum density of common resins. Density 12.0g / cm 3 is the density of lead. By setting the density of the hard material forming the holding base 5 within the above range, it is possible to achieve a good balance between the sound insulation performance and ease of handling of the impact tool 1.

[0075] Moreover, the hard member forming the holding base 5 is preferably made of metal. By using a metal hard member, sound insulation performance can be improved compared to the case where a holding base formed of a resin or the like is used.

[0076] In particular, the hard member forming the support table 5 is preferably made of aluminum. The density of aluminum is 2.7 g / cm 3 Therefore, by using aluminum for the hard member, it is possible to achieve a good balance between the sound insulation performance and ease of handling of the impact tool 1.

[0077] The hard member forming the support base 5 may be a metal other than aluminum. For example, the hard member may be iron. The density of iron is 7.87 g / cm 3 Therefore, by using iron as the hard member, it is possible to achieve a good balance between the sound insulation performance and ease of handling of the impact tool 1. The hard member may also be tungsten. The density of tungsten is 19.3 g / cm3 Therefore, by using tungsten for the hard member, it is possible to further improve the sound insulation performance.

[0078] (9) Variations Modifications of the embodiment will be listed below. The following modifications may be implemented in appropriate combination.

[0079] The position of the holder 5 is not limited to a position facing the boundary portion 23. The entire holder 5 may be located on the first portion 21 side (forward) of the boundary portion 23, i.e., within the internal space 210 of the first portion 21. Alternatively, the entire holder 5 may be located on the second portion 22 side (rear) of the boundary portion 23, i.e., within the internal space 220 (220b) of the second portion 22. The holder 5 may be located between the hammer 42 and the motor 3 within the housing 2.

[0080] The holder 5 is not limited to one that rotatably holds all the gears included in the planetary gear mechanism 48, but may be one that rotatably holds at least one gear included in the planetary gear mechanism 48.

[0081] The holder 5 is not limited to one that holds the planetary gear mechanism 48, and may be one that holds a member other than the planetary gear mechanism 48.

[0082] It is not essential that the first portion 21 and the second portion 22 of the housing 2 are made of separate members. The first portion 21 and the second portion 22 may be formed of a single member. In this case, the boundary portion 23 is a joint portion between the first portion 21 and the second portion 22.

[0083] (10) Summary The impact tool (1) of the first aspect of the embodiment includes a motor (3), a hammer (42), an anvil (44), a bearing (49), a housing (2), and a holder (5). The motor (3) generates a driving force. The hammer (42) has a hammer body (420) and a hammer claw (421) connected to the hammer body (420), and rotates by the driving force of the motor (3). The anvil (44) has an anvil shaft (441) capable of holding a tool tip at the tip in the direction of the rotation axis of the hammer (42), and an anvil claw (442) connected to the anvil shaft (441) and colliding with the hammer claw (421) in the rotation direction of the hammer (42) as the hammer (42) rotates. The bearing (49) rotatably supports the anvil shaft (441). The housing 2 accommodates at least a portion of the anvil 44, the hammer 42, and the motor 3. The holder 5 is accommodated in the housing 2 and is held by the housing 2 between the hammer 42 and the motor 3. At least a portion of the holder 5 is formed of a hard material having sound insulation properties.

[0084] The impact tool (1) described above can suppress the impact noise emitted from the rear part of the housing (2) with a simple structure.

[0085] In the impact tool (1) of the second aspect according to the embodiment, in the first aspect, the entire holding base (5) is preferably formed of the hard material.

[0086] The impact tool (1) described above can further suppress the impact noise emitted from the rear part of the housing (2) with a simple structure.

[0087] In the impact tool (1) according to the third aspect of the embodiment, in the first or second aspect, the density of the hard member is 2.0 g / cm 3 More than 12.0g / cm 3 It is preferable that:

[0088] The impact tool (1) described above can achieve a good balance between sound insulation performance and ease of use.

[0089] In the impact tool (1) of the fourth aspect according to the embodiment, in any one of the first to third aspects, the hard member is preferably made of metal.

[0090] The impact tool (1) described above can improve sound insulation performance compared to a case where a holding base (5) made of resin or the like is used.

[0091] In the impact tool (1) of the fifth aspect according to the embodiment, in the fourth aspect, the hard member is preferably made of aluminum.

[0092] The impact tool (1) described above can achieve a good balance between sound insulation performance and ease of use.

[0093] In the impact tool (1) of the sixth aspect according to the embodiment, in any one of the first to fifth aspects, the housing (2) has a first portion (21) that houses at least a part of the anvil (44) and the hammer (42), and a second portion (22) that houses the motor (3). The holding base (5) is preferably held by the housing (2) so as to face a boundary portion (23) where the first portion (21) and the second portion (22) are in contact with each other.

[0094] The impact tool (1) described above can suppress the impact noise emitted from the rear part of the housing (2) with a simple structure.

[0095] In the seventh aspect of the impact tool (1) according to the sixth aspect, it is preferable that the internal space (210) of the first portion (21) has a shape in which the diameter increases as it approaches the internal space (220) of the second portion (22).

[0096] The impact tool (1) described above can suppress the impact sound propagating within the first portion (21) toward the second portion (22) with a simple structure.

[0097] In the impact tool (1) of the eighth aspect of the embodiment, in any one of the first to seventh aspects, it is preferable that the holding base (5) rotatably holds at least one gear included in the planetary gear mechanism (48).

[0098] The impact tool (1) described above can suppress impact noise emitted from the rear of the housing (2) with a simple structure by using the holding base (5) that holds the planetary gear mechanism (48) as a soundproofing member. [Explanation of symbols]

[0099] 1 Impact tool 2. Housing 21 Part 1 210 Interior Space 22 Part 2 220 Interior Space 23 Boundary 3 Motor 42 Hammer 420 Hammer body 421 Hammer Claw 44 Anvil 441 Anvil shaft 442 Anvil Claw 48 Planetary Gear Mechanism 49 Bearings 5 Holding stand

Claims

1. A motor that generates a driving force; a hammer having a hammer body and a hammer claw connected to the hammer body and rotated by the driving force of the motor; an anvil having an anvil shaft capable of holding a tool at its tip in the direction of the rotation axis of the hammer, and anvil claws connected to the anvil shaft and colliding with the hammer claws in the rotation direction of the hammer as the hammer rotates; a bearing that rotatably supports the anvil shaft; a housing that accommodates at least a portion of the anvil, the hammer, and the motor; a holder that is accommodated in the housing and is held by the housing between the hammer and the motor, At least a part of the support base is formed of a hard material having sound insulation properties. Impact tool.

2. The entire holding table is formed of the hard member. The impact tool according to claim 1.

3. The density of the hard member is 2.0 g / cm ３ Above, 12.0g / cm ３ Is less than or equal to The impact tool according to claim 1.

4. The hard member is a metal. The impact tool according to claim 1.

5. The hard member is made of aluminum.

5. The impact tool according to claim 4.

6. the housing has a first portion that houses at least a portion of the anvil and the hammer, and a second portion that houses the motor; The support base is supported by the housing so as to face a boundary portion where the first portion and the second portion are in contact with each other. The impact tool according to claim 1.

7. The internal space of the first portion has a shape in which the diameter increases as it approaches the internal space of the second portion.

7. The impact tool according to claim 6.

8. The holding base rotatably holds at least one gear included in a planetary gear mechanism. The impact tool according to claim 1.

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