Impact tool

Abstract

To downsize an impact tool.SOLUTION: An impact tool 1 includes: a motor 3 for generating a driving force; a spindle 41 which holds a planetary gear 482, and is rotated by the motor 3; an anvil 44 which is arranged on a side opposite to the planetary gear 482 in an axial direction of a rotation axis of the spindle 41; a main hammer 42a which is rotatable around a rotation axis of the spindle 41 as a central axis, is movable along the central axis, and rotates the anvil 44 around the rotation axis; a sub hammer 42b having a cylindrical part storing the main hammer 42a; a first bearing 493 which is arranged between the sub hammer 42b and the spindle 41, and receives a load in a radial direction to the rotation axis; a gear base 5 for storing the planetary gear 482 and an inner gear 483; and a second bearing 492 which is arranged between the sub hammer 42b and the gear base 5, and receives a load in a radial direction to the rotation axis.SELECTED DRAWING: Figure 2

Description

[Technical Field]

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

[0002] Patent Document 1 discloses an impact tool. The impact tool of Patent Document 1 includes an inner hammer (main hammer) supported by a spindle rotated by a motor, and an outer hammer (sub-hammer) disposed around the inner hammer and rotating together with the inner hammer. In the impact tool of Patent Document 1, the outer hammer is supported by a hammer case via a bearing. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2023-90351 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the impact tool of Patent Document 1, the spindle is supported by the bearing holder via a bearing on the motor side of the outer hammer, which increases the size of the impact tool.

[0005] The present disclosure aims to make impact tools more compact. [Means for solving the problem]

[0006] An impact tool according to one aspect of the present disclosure includes a motor, a spindle, an anvil, a main hammer, an auxiliary hammer, a first bearing, a gear base, and a second bearing. The motor generates a driving force. The spindle holds planetary gears and is rotated by the motor. The anvil is disposed on the opposite side of the planetary gears in the axial direction of the rotation shaft of the spindle. The main hammer is rotatable about the rotation shaft of the spindle as a central axis and is movable along the central axis, causing the anvil to rotate around the rotation shaft. The auxiliary hammer has a cylindrical portion in which the main hammer is housed and through which the spindle is inserted, and rotates integrally with the main hammer. The first bearing is disposed between the auxiliary hammer and the spindle and receives a radial load with respect to the rotation shaft. The gear base houses the planetary gears and an internal gear that engages with the planetary gears. The second bearing is disposed between the secondary hammer and the gear base, and receives a load in the radial direction relative to the rotation shaft. [Effects of the Invention]

[0007] According to the impact tool according to one aspect of the present disclosure, it is possible to reduce the size of the impact tool. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a perspective view showing an impact tool according to an embodiment. [Figure 2] FIG. 2 is a side cross-sectional view showing the impact tool. [Figure 3] FIG. 3 is a partial exploded view showing a main part of the impact tool. [Figure 4] FIG. 4 is a partial exploded view showing the transmission mechanism of the impact tool. DETAILED DESCRIPTION OF THE INVENTION

[0009] The present disclosure relates generally to impact tools, and more particularly to an impact tool having a housing that houses a primary hammer, a secondary hammer, and an anvil.

[0010] (Embodiment) An impact tool according to an embodiment will be described below with reference to the drawings. However, the embodiment described below is merely one of various embodiments of the present disclosure. The embodiment described below can be modified in various ways depending on the design, etc., as long as the object of the present disclosure can be achieved. Furthermore, each drawing described in the embodiment described below is a schematic drawing, and the ratios of the sizes and thicknesses of the components in the drawing do not necessarily reflect the actual dimensional ratios.

[0011] In the following description, the direction in which the motor 3 and spindle 41 are lined up in Fig. 2 is defined as the front-to-rear direction, the spindle 41 side as viewed from the motor 3 is defined as the front, and the motor 3 side as viewed from the spindle 41 is defined as the rear. In the following description, the direction in which the second parts 22 and 23 and the grip part 24 are lined up in Figs. 1 and 2 is defined as the up-down direction, the second parts 22 and 23 side as viewed from the grip part 24 is defined as the top, and the grip part 24 side as viewed from the second parts 22 and 23 is defined as the bottom. However, these definitions are not intended to define the direction in which the impact tool is used.

[0012] (overview) As shown in FIGS. 1 to 4 , the impact tool 1 of this embodiment includes a motor 3, a spindle 41, an anvil 44, a primary hammer 42a, a secondary hammer 42b, a first bearing 493, a gear base 5, and a second bearing 492. The motor 3 generates a driving force. The spindle 41 holds a planetary gear 482 and is rotated by the motor 3. The anvil 44 is disposed on the opposite side of the spindle 41 from the planetary gear 482 in the axial direction of the rotation shaft of the spindle 41. The primary hammer 42a is rotatable around the rotation shaft of the spindle 41 as a central axis, is movable along the central axis, and rotates the anvil 44 about the rotation shaft. The secondary hammer 42b has a cylindrical portion that houses the primary hammer 42a and through which the spindle 41 is inserted, and rotates integrally with the primary hammer 42a. The first bearing 493 is disposed between the secondary hammer 42b and the spindle 41, and receives a load in the radial direction with respect to the rotation axis. The gear base 5 houses the planetary gear 482 and the internal gear 483 that engages with the planetary gear 482. The second bearing 492 is disposed between the secondary hammer 42b and the gear base 5, and receives a load in the radial direction with respect to the rotation axis. The impact tool 1 of this embodiment also includes a shim 6 between the spindle 41 and the gear base 5.

[0013] In the impact tool 1, the load applied to the anvil 44 in the thrust direction relative to the rotation axis can be received by the gear base 5 via the spindle 41 and the shim 6 without affecting the rotary impact mechanism. Therefore, the rotary impact performance of the impact tool 1 can be improved.

[0014] (detail) (1) Overall structure The impact tool 1 of this embodiment will be described in detail below.

[0015] The impact tool 1 of this embodiment is a portable power tool. The impact tool 1 is, for example, an electric impact wrench that attaches fasteners (bolts, nuts, etc.) to a work object and loosens fasteners attached to the work object. As shown in FIGS. 1 to 4 , the impact tool 1 includes a motor 3, a spindle 41, an anvil 44, a main hammer 42a, an auxiliary hammer 42b, a first bearing 493, a gear base 5, and a second bearing 492. The impact tool 1 also includes a housing 2, an operating unit 83, and a torque sensor 47.

[0016] (2) Housing As shown in FIG. 2, the housing 2 accommodates the motor 3, the spindle 41, the anvil 44, the main hammer 42a, the secondary hammer 42b, the first bearing 493, the gear base 5, the second bearing 492, and the torque sensor 47 (see FIG. 3). As shown in FIG. 2, the housing 2 has a first section 21, second sections 22 and 23, a third section 221, a grip section 24, and an attachment section 25. The first section 21 accommodates at least a portion of the anvil 44 and the torque sensor 47. The second sections 22 and 23 accommodate the motor 3. The first section 21 constitutes a cover, and the second sections 22 and 23 and the third section 221 constitute a case.

[0017] The first region 21 and the second regions 22 and 23 are formed as separate members. The rear end of the first region 21 and the front end of the second regions 22 and 23 form a boundary where the first region 21 and the second regions 22 and 23 contact each other. More specifically, as shown in FIG. 2 , the inner circumferential surfaces of the front end portions 231 of the second regions 22 and 23 cover the outer circumferential surface of the rear wall 215 of the first region 21.

[0018] The second portions 22 and 23 are formed as separate members from the third portion 221. The rear ends of the second portions 22 and 23 and the front end of the third portion 221 form a boundary where the second portions 22 and 23 and the third portion 221 contact each other.

[0019] (2.1) First part 1 and 3, the first portion 21 has a cylindrical shape and includes a front wall 211, a side wall 212, a rear wall 215, and four mounting pieces 213. The first portion 21 corresponds to the cover of the present disclosure.

[0020] The front wall 211 has a cylindrical shape. An insertion hole 214 with 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 insertion hole 214. The tip (front end) of the anvil shaft 441 is located forward of the front end of the first section 21. The side wall 212 has a cylindrical shape extending rearward from the outer circumferential edge of the front wall 211.

[0021] 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 through which screws B1 (see FIGS. 1 and 3) are inserted.

[0022] The rear wall 215 has a cylindrical shape and extends rearward from the peripheral edge of the rear end of the side wall 212. As shown in FIG.

[0023] 2, the first section 21 has an internal space that is circular in cross section and open at the rear, surrounded by a front wall 211 and a side wall 212, and accommodates at least a part of an anvil 44 (described later) and a torque sensor 47. The internal space has a diameter larger at the rear end than at the front end, and the diameter increases toward the rear, forming a so-called bell shape.

[0024] (2.2) Second and third parts 1 and 3, the second portions 22 and 23 are cylindrical in shape. The second portions 22 and 23 include side walls and four mounting pieces 223. The second portions 22 and 23 correspond to the case of the present disclosure.

[0025] 2, the second portions 22 and 23 have an internal space with a circular cross section that is surrounded by side walls and is open at the front and rear. The internal space has a cylindrical shape that extends in the front-to-rear direction.

[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. The mounting pieces 223 are formed with screw holes into which screws B1 (see FIGS. 1 and 3) are screwed.

[0027] The first part 21 and the second parts 22 and 23 are connected by screw fastening. More specifically, as shown in Fig. 1 , the insertion holes provided in each of the four mounting pieces 213 of the first part 21 correspond one-to-one to the screw holes provided in each of the four mounting pieces 223 of the second parts 22 and 23, and the corresponding insertion holes and screw holes are aligned. Then, a screw B1 is inserted through the insertion hole and screwed into the screw hole, thereby connecting the first part 21 and the second parts 22 and 23.

[0028] 1, the third portion 221 has a disk shape. The third portion 221 is disposed behind the second portions 22 and 23.

[0029] (2.3) Grip The grip portion 24 protrudes from the second portions 22 and 23. More specifically, the grip portion 24 protrudes from the side surfaces of the second portions 22 and 23. The grip portion 24 protrudes downward from the second portions 22 and 23. An operator can grasp the grip portion 24 to perform the work of fastening a fastening member such as a screw.

[0030] (2.4) Mounting part As shown in FIG. 1, the mounting portion 25 has a rectangular parallelepiped shape. The mounting portion 25 is connected to the lower end of the grip portion 24. A rechargeable battery pack (not shown) is detachably attached to the mounting portion 25. The impact tool 1 operates using the battery pack as a power source. That is, 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 multiple secondary batteries (e.g., lithium ion batteries) in series, and a case that houses the battery pack.

[0031] (3) Motor As shown in FIG. 2, the motor 3 is accommodated in the internal space of the second portions 22 and 23 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. Electromagnetic interaction between the permanent magnet and the coil causes the rotor 31 to rotate relative to the stator 32. The rotation of the rotor 31 causes the motor 3 to generate a driving force. The rotating shaft 311 is disposed to extend in the front-rear direction. The rotation of the rotor 31 causes the rotating shaft 311 to rotate.

[0032] (4)Operation section As shown in FIG. 1, the operating unit 83 protrudes from the grip portion 24. The operating unit 83 receives operations for controlling the rotation of the rotary shaft 311 of the motor 3. By pulling the operating unit 83, the motor 3 can be switched on and off. Furthermore, the rotation speed of the rotary shaft 311 can be adjusted by the amount of pulling the operating unit 83. The greater the amount of pulling, the faster the rotation speed of the rotary shaft 311.

[0033] (5) Transmission mechanism The transmission mechanism includes an impact mechanism, a planetary gear mechanism 48, and a bearing 49. The bearing 49 includes a bearing 491, a second bearing 492, and a first bearing 493.

[0034] The impact mechanism is configured to perform an impact operation that applies an impact force in the rotational direction of the 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 the 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 wrench that performs fastening work such as screw tightening while performing an impact operation using the impact mechanism.

[0035] The impact mechanism includes a spindle 41, a main hammer 42a, a secondary hammer 42b, a coil spring 43, an anvil 44, and two steel balls 45 which are spherical bodies.

[0036] The planetary gear 482 of the planetary gear mechanism 48 is located within the housing 2 behind the anvil 44 and held by a carrier of the spindle 41. That is, the planetary gear 482 is held by the spindle. The carrier of the spindle 41 is provided at one of the two ends of the spindle 41, the rear end opposite the front end facing the anvil 44. That is, the anvil 44 is located on the opposite side of the planetary gear 482 in the axial direction of the rotation shaft of the spindle 41.

[0037] As shown in FIGS. 2 and 3 , 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 rotation shaft 311 of the motor 3 to rotate together with the rotation shaft 311. In this embodiment, the sun gear 481 is formed integrally with the front end of the rotation shaft 311 of the motor 3. 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 due to the driving force transmitted from the sun gear 481 and revolves around the internal gear 483. A cylindrical spindle 41 extending in the front-to-rear direction is disposed in front of the planetary gear mechanism 48. The spindle 41 is connected to the two planetary gears 482, and the orbital motion of the planetary gear 482 is transmitted to the spindle 41, causing the spindle 41 to rotate. 2 and 3, shafts 484 (see FIG. 2) of two planetary gears 482 are inserted into the rear end of the spindle 41. That is, the spindle 41 is connected to the two planetary gears 482.

[0038] 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 spindle 41 via the planetary gear mechanism 48. This causes the spindle 41 to rotate.

[0039] Two grooves, each having a semicircular cross section, are formed on the outer peripheral surface of spindle 41. Each of the two grooves extends in a direction inclined toward a direction intersecting the axial direction on the outer peripheral surface of spindle 41.

[0040] The primary hammer 42a is made of metal. The primary hammer 42a rotates by torque transmitted via the spindle 41, thereby rotating the anvil 44. Furthermore, the primary hammer 42a moves (translates) in the front-to-rear direction relative to the anvil 44 while rotating, thereby applying a striking force to the anvil 44 in the rotational direction.

[0041] Specifically, as shown in Fig. 2, the primary hammer 42a has a pair of protrusions, namely, hammer claws 421. The pair of hammer claws 421 are arranged at 180-degree intervals. A through-hole 422 penetrating in the front-rear direction is formed in the center of the primary hammer 42a by a cylindrical body extending in the front-rear direction. The cross section of the through-hole 422 is circular. The spindle 41 passes through the through-hole 422 in the front-rear direction.

[0042] Two grooves 423 (see FIG. 2), which are semicircular grooves in cross section, are formed on the inner circumferential surface of the through hole 422 of the primary hammer 42a. 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.

[0043] Two steel balls 45 are sandwiched between the two grooves of the spindle 41 and the two grooves 423 of the primary hammer 42a. The steel balls 45 are spherical. The two grooves of the spindle 41, the two grooves 423 of the primary hammer 42a, and the two steel balls 45 form a cam mechanism. That is, the torque of the spindle 41 is transmitted to the primary hammer 42a via the two steel balls 45, causing the primary hammer 42a to rotate. The steel balls 45 are housed in a cam groove formed by the grooves of the spindle 41 and the grooves 423, and can move within the cam groove. The movement of the two steel balls 45 along the cam groove allows the primary hammer 42a to move in the axial direction (front-to-back direction) relative to the spindle 41. The two cam grooves are symmetrical with respect to a virtual plane passing through the axial direction of the spindle 41.

[0044] A coil spring 43 is provided behind the primary hammer 42a, and the coil spring 43 applies a spring force to the primary hammer 42a in the forward direction. The primary hammer 42a moves backward against the spring force of the coil spring 43, and the retracted primary hammer 42a moves forward due to the spring force.

[0045] The secondary hammer 42b is made of metal. The secondary hammer 42b rotates integrally with the primary hammer 42a. The secondary hammer 42b has a cylindrical portion that houses the primary hammer 42a, the coil spring 43, and the anvil body 440 of the anvil 44. A through hole that penetrates the cylindrical portion of the secondary hammer 42b in the front-rear direction is formed. The cross section of the through hole is circular. The spindle 41 penetrates the through hole in the front-rear direction.

[0046] The secondary hammer 42b has a peripheral portion 425 that protrudes toward the motor 3 (rearward). The peripheral portion 425 is cylindrical. The inner peripheral surface of the peripheral portion 425 of the secondary hammer 42b is journaled by a first bearing 493 (FIG. 2). The first bearing 493 rotatably supports the secondary hammer 42b. The first bearing 493 is configured, for example, as a ball bearing that journals the inner periphery of the secondary hammer 42b. The first bearing 493 receives a radial load relative to the rotation axis of the spindle 41. In addition, the first bearing 493 suppresses oscillation and vibration of the rotating secondary hammer 42b.

[0047] The anvil 44 is disposed in front of the primary hammer 42a. The anvil 44 includes an anvil body 440 and an anvil shaft 441. The anvil body 440 and the anvil shaft 441 are formed of metal. The anvil body 440 and the anvil shaft 441 rotate due to torque transmitted from the rotating primary hammer 42a.

[0048] The anvil body 440 has a pair of anvil claws 442. The pair of anvil claws 442 are arranged at 180-degree intervals and protrude in the radial direction of the anvil body 440. The anvil body 440 faces the primary hammer 42a in the front-to-rear direction. As the primary hammer 42a rotates, the anvil claws 442 collide with the hammer claws 421 in the rotational direction of the primary hammer 42a.

[0049] The anvil shaft 441 is disposed axially forward from the front surface of the anvil body 440. The anvil shaft 441 is an output shaft that rotates in synchronization with the anvil body 440. A tool bit (not shown) is attached to the tip (front end) of the anvil shaft 441. That is, the anvil shaft 441 has a structure that can hold a tool bit at its tip in the direction of the rotation axis of the primary hammer 42a. The tool bit is a bit for rotating fastening parts such as bolts and nuts.

[0050] The outer circumferential surfaces of the anvil shaft 441 and the anvil body 440 are journaled by bearings 491 (see FIG. 2). The bearings 491 rotatably support the anvil shaft 441. The bearings 491 are, for example, roller bearings that journal the outer circumferential surfaces of the anvil body 440 and the anvil shaft 441. The bearings 491 suppress oscillation, vibration, and the like of the rotating anvil body 440 and the anvil shaft 441. It is sufficient that the bearings 491 have a configuration that at least rotatably supports the anvil shaft 441.

[0051] The spindle 41 is rotated by torque transmitted from the motor 3 via the planetary gear mechanism 48, and the primary hammer 42a receives torque transmitted from the spindle 41 via the above-mentioned cam mechanism and rotates around the spindle 41 as a rotation axis. When the primary hammer 42a is not performing a striking operation, the primary hammer 42a and the anvil body 440 rotate together while the pair of hammer claws 421 of the primary hammer 42a contacts the pair of anvil claws 442 of the anvil body 440 in the rotation direction. When the anvil body 440 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.

[0052] As the fastening member rotates and is tightened into a screw hole or the like, the axial force increases, and the tightening torque of the fastening member increases. As the tightening torque increases, the component of the force generated between the primary hammer 42a and the anvil body 440 that moves the primary hammer 42a backward also increases. When the tightening torque reaches a predetermined value or greater, the primary hammer 42a moves backward against the spring force of the coil spring 43. As the primary hammer 42a moves backward, the pair of hammer claws 421 of the primary hammer 42a climb over the two anvil claws 442 of the anvil body 440, causing the primary hammer 42a to rotate. Thereafter, the primary hammer 42a moves forward due to the spring force of the coil spring 43. When the spindle 41 rotates approximately half a turn, the pair of hammer claws 421 of the primary hammer 42a collide with the side surfaces of the pair of anvil claws 442 of the anvil body 440. That is, every time the spindle 41 makes approximately a half rotation, the hammer claw 421 collides with the anvil claw 442. In other words, the primary hammer 42a applies a striking force (rotational striking force) to the anvil body 440 every time the spindle 41 makes approximately a half rotation while repeatedly moving backward and forward.

[0053] (6) Control unit The control unit includes a torque sensor 47. The torque sensor 47 measures the torque applied to the anvil shaft 441. The control unit controls the rotation speed of the rotating shaft 311, for example, by feedback control that controls the torque of the anvil shaft measured by the torque sensor 47 so that it approaches a target value. The control unit changes the rotation speed of the rotating shaft 311, for example, by changing the power supplied to the motor 3.

[0054] (7) Gear base The gear base 5 is accommodated in the housing 2 and is held by the housing 2 between the secondary hammer 42 b and the motor 3 .

[0055] As shown in FIGS. 2 to 4, the gear base 5 has a cylindrical shape and includes a rear wall 51 and a side wall 52. The rear wall 51 has a disk shape. The rear wall 51 has a through-hole through which the rotating shaft 311 of the motor 3 is inserted. The side wall 52 has a cylindrical shape that extends forward from the outer periphery of the rear wall 51.

[0056] The planetary gear mechanism 48 is housed inside the side wall 52 of the gear base 5. That is, the gear base 5 houses a planetary gear 482 and an internal gear 483 that engages with the planetary gear 482. The annular internal gear 483 of the planetary gear mechanism 48 is attached to the side wall 52 along an inner circumferential surface 522 of the side wall 52. The 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 rotation 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 rotation shaft 311. The two planetary gears 482 of the planetary gear mechanism 48 are meshed with the sun gear 481 and the internal gear 483 between the sun gear 481 and the internal gear 483. The spindle 41 is connected to the two planetary gears 482 by inserting the shafts 484 (see FIG. 2) of the two planetary gears 482 into the spindle 41 .

[0057] A shim 6 is disposed between the rear wall 51 of the gear base 5 and the spindle 41 (see FIGS. 2 and 3). The shim 6 is, for example, ring-shaped. As a result, in the impact tool 1, a thrust load applied to the anvil 44 in the direction of the rotation axis can be received by the gear base 5 via the spindle 41 and the shim 6 without affecting the rotary impact mechanism. This improves the rotary impact performance of the impact tool 1. It also prevents overheating and seizure due to sliding between the spindle 41 and the gear base 5. The impact tool 1 may include a thrust ball bearing or a thrust roller bearing instead of the shim 6. This configuration also improves the rotary impact performance of the impact tool 1, as described above.

[0058] A second bearing 492 is disposed inside the side wall 52 of the gear base 5. The outer circumferential surface of the secondary hammer 42b is journaled by the second bearing 492 (see FIG. 2). The second bearing 492 rotatably supports the secondary hammer 42b. The second bearing 492 is, for example, a ball bearing that journals the outer periphery of the secondary hammer 42b. The second bearing 492 receives a radial load relative to the rotation shaft of the spindle 41. The second bearing 492 also suppresses oscillation and vibration of the rotating secondary hammer 42b. As shown in FIG. 2, the second bearing 492 is disposed at a position overlapping with the first bearing 493 in the axial direction of the rotation shaft of the spindle 41. This allows the length of the transmission mechanism in the axial direction of the rotation shaft of the spindle 41 to be shortened. This therefore allows the length of the impact tool 1 in the front-to-rear direction to be reduced.

[0059] Here, the inner peripheral surface of the second bearing 492 is in close contact with the outer peripheral surface of the secondary hammer 42b, and a gap is formed between the outer peripheral surface of the second bearing 492 and the inner peripheral surface 522 of the gear base 5. As a result, when assembling or disassembling the impact tool 1, the second bearing 492 and the secondary hammer 42b can be handled as an integrated structure, making handling easier.

[0060] Furthermore, the outer peripheral surface of the side wall 52 of the gear base 5 is covered by the inner peripheral surface of the rear wall 215 of the first portion 21. As described above, the inner peripheral surfaces of the front end portions 231 of the second portions 22 and 23 cover the outer peripheral surface of the rear wall 215 of the first portion 21. Therefore, the side wall 52 of the gear base 5 is covered by the inner peripheral surface of the rear wall 215 of the first portion 21. This facilitates attachment and detachment of the first portion 21 and the gear base 5 while maintaining the precision of the bearing during manufacture and maintenance of the impact tool 1. Furthermore, because the gear base 5 is sandwiched between the first portion 21 and the second portions 22 and 23, the gear base 5 can be fixed to the housing 2 without using screws or claws. This facilitates assembly and disassembly of the impact tool 1.

[0061] At least a part of the gear base 5 is made of metal. The gear base 5 is made of, for example, an aluminum alloy. This allows the sound insulation of the gear base 5 to block sounds that reach the user of the impact tool 1 in particular. This makes it possible to improve the quietness of the impact tool 1.

[0062] (8) Effects The impact tool 1 according to the first embodiment includes a motor 3, a spindle 41, an anvil 44, a primary hammer 42a, a secondary hammer 42b, a first bearing 493, a gear base 5, and a second bearing 492. The motor 3 generates a driving force. The spindle 41 holds a planetary gear 482 and is rotated by the motor 3. The anvil 44 is disposed on the opposite side of the planetary gear 482 in the axial direction of the rotation shaft of the spindle 41. The primary hammer 42a is rotatable about the rotation shaft of the spindle 41 as a central axis, is movable along the central axis, and rotates the anvil 44 about the rotation shaft. The secondary hammer 42b has a cylindrical portion that houses the primary hammer 42a and through which the spindle 41 is inserted, and rotates integrally with the primary hammer 42a. The first bearing 493 is disposed between the secondary hammer 42b and the spindle 41 and receives a load in the radial direction relative to the rotation shaft. The gear base 5 accommodates the planetary gear 482 and the internal gear 483 that engages with the planetary gear 482. The second bearing 492 is disposed between the secondary hammer 42b and the gear base 5, and receives a load in the radial direction with respect to the rotation axis.

[0063] Therefore, when the spindle 41, the secondary hammer 42b, and the gear base 5 are arranged in this order in the radial direction of the rotation shaft, the first bearing 493 and the second bearing 492 can be arranged to overlap in the axial direction of the rotation shaft. This allows the impact tool 1 to be made smaller.

[0064] Furthermore, the impact tool 1 according to the first embodiment includes a shim 6 between the spindle 41 and the gear base 5.

[0065] Therefore, in the impact tool 1, the thrust load applied to the anvil 44 relative to the rotation axis can be received by the gear base 5 via the spindle 41 and the shim 6 without affecting the rotary impact mechanism. This improves the rotary impact performance of the impact tool 1. It also reduces the risk of seizure caused by sliding between the spindle 41 and the gear base 5.

[0066] The impact tool 1 according to the first embodiment includes cases 22 and 23 and a cover 21. The cases 22 and 23 house the motor 3. The cover 21 houses the secondary hammer 42b. The inner circumferential surface of the cover 21 covers the outer circumferential surface 521 of the gear base 5. The inner circumferential surfaces of the cases 22 and 23 cover the outer circumferential surface of the cover 21. This facilitates attachment and detachment of the first portion 21 and the gear base 5 while maintaining the precision of the support during manufacture and maintenance of the impact tool 1. Furthermore, because the gear base 5 is sandwiched between the first portion 21 and the second portions 22 and 23, the gear base 5 can be fixed to the housing 2 without using screws or nails. This facilitates assembly and disassembly of the impact tool 1.

[0067] Furthermore, in the impact tool 1 according to the first embodiment, the inner peripheral surface of the second bearing 492 is in close contact with the outer peripheral surface of the secondary hammer 42b. A gap is formed between the outer peripheral surface of the second bearing 492 and the inner peripheral surface of the gear base 5. Therefore, when assembling or disassembling the impact tool 1, the second bearing 492 and the secondary hammer 42b can be handled as an integrated structure, making handling easier.

[0068] In the impact tool 1 according to the first embodiment, the material of the gear base 5 contains metal. This allows the gear base 5 to have sound insulation properties, thereby making it possible to improve the quietness of the impact tool 1.

[0069] Furthermore, in the impact tool 1 according to the first embodiment, the anvil 44 includes an anvil body 440 and an anvil shaft 441 that is separate from the anvil body 440. The anvil body 440 is rotated by the primary hammer 42a. The anvil shaft 441 is rotated by the anvil body 440. This reduces vibration of the anvil shaft 441 caused by the primary hammer 42a, making it possible to improve the quietness of the impact tool 1.

[0070] Moreover, the impact tool 1 according to the first embodiment includes a torque sensor 47. The torque sensor 47 measures the torque of the anvil 44. This makes it possible for the impact tool 1 to control the rotation speed of the anvil 44 by, for example, feedback control.

[0071] (Aspect) The impact tool (1) according to the first aspect includes a motor (3), a spindle (41), an anvil (44), a primary hammer (42a), a secondary hammer (42b), a first bearing (493), a gear base (5), and a second bearing (492). The motor (3) generates a driving force. The spindle (41) holds a planetary gear (482) and is rotated by the motor (3). The anvil (44) is disposed on the opposite side of the planetary gear (482) in the axial direction of the rotation shaft of the spindle (41). The primary hammer (42a) is rotatable about the rotation shaft of the spindle (41) as a central axis and is movable along the central axis, causing the anvil (44) to rotate about the rotation shaft. The secondary hammer (42b) has a cylindrical portion in which the primary hammer (42a) is housed and through which the spindle (41) is inserted, and rotates integrally with the primary hammer (42a). The first bearing (493) is disposed between the secondary hammer (42b) and the spindle (41) and receives a load in the radial direction with respect to the rotation shaft. The gear base (5) houses the planetary gear (482) and the internal gear (483) that engages with the planetary gear (482). The second bearing (492) is disposed between the secondary hammer (42b) and the gear base (5) and receives a load in the radial direction with respect to the rotation shaft.

[0072] According to the impact tool (1) of the above aspect, when the spindle (41), the secondary hammer (42b), and the gear base (5) are arranged in this order in the radial direction of the rotation shaft, the first bearing (493) and the second bearing (492) can be arranged so as to overlap in the axial direction of the rotation shaft, thereby making it possible to reduce the size of the impact tool (1).

[0073] The impact tool (1) according to the second aspect is the same as that of the first aspect, and further includes a shim (6) between the spindle (41) and the gear base (5).

[0074] According to the impact tool 1 of the above aspect, the thrust load applied to the anvil 44 relative to the rotation axis can be received by the gear base 5 via the spindle 41 and the shim 6. This improves the rotary impact performance of the impact tool 1. Furthermore, according to the impact tool 1 of the above aspect, it is possible to reduce the risk of seizure due to sliding between the spindle 41 and the gear base 5.

[0075] The impact tool (1) according to a third aspect is the impact tool (1) of the first or second aspect, further including a case (22, 23) and a cover (21). The case (22, 23) houses the motor (3). The cover (21) houses the secondary hammer (42b). The inner peripheral surface of the cover (21) covers the outer peripheral surface (521) of the gear base (5). The inner peripheral surface of the case (22, 23) covers the outer peripheral surface of the cover (21).

[0076] According to the impact tool 1 of the above aspect, the cover 21 and the gear base 5 can be easily attached and detached while maintaining the precision of the bearing during manufacturing and maintenance of the impact tool 1. Furthermore, the gear base 5 is sandwiched between the cover 21 and the cases 22, 23. Therefore, the impact tool 1 can be easily assembled and disassembled.

[0077] In the impact tool (1) according to the fourth aspect, in any one of the first to third aspects, the inner peripheral surface of the second bearing (492) is in close contact with the outer peripheral surface of the secondary hammer (42b), and a gap is formed between the outer peripheral surface of the second bearing (492) and the inner peripheral surface of the gear base (5).

[0078] According to the impact tool (1) of the above aspect, when assembling or disassembling the impact tool (1), the second bearing (492) and the secondary hammer (42b) can be handled as an integrated structure, making handling easy.

[0079] In the impact tool (1) according to the fifth aspect, in any one of the first to fourth aspects, the material of the gear base (5) includes metal.

[0080] According to the impact tool (1) of the above aspect, the sound insulation of the gear base (5) makes it possible to improve the quietness of the impact tool (1).

[0081] In the impact tool (1) according to the sixth aspect, in any one of the first to fifth aspects, the anvil (44) includes an anvil body (440) and an anvil shaft (441). The anvil body (440) is rotated by the primary hammer (42a). The anvil shaft (441) is rotated by the anvil body (440).

[0082] According to the impact tool (1) of the above aspect, it is possible to reduce the vibration of the anvil shaft (441) caused by the primary hammer (42a), thereby improving the quietness of the impact tool (1).

[0083] The impact tool (1) according to a seventh aspect is the impact tool (1) of any one of the first to sixth aspects, further including a torque sensor (47). The torque sensor (47) measures the torque of the anvil (44).

[0084] According to the impact tool (1) of the above aspect, it is possible to control the rotation speed of the anvil (44) by, for example, feedback control. [Explanation of symbols]

[0085] 1 impact tool 21 Part 1 (Cover) 22, 23 Second part (case) 3 motors 41 Spindle 42a Main Hammer 42b Secondary hammer 44 Anvil 440 Anvil body 441 Anvil shaft 47 Torque sensor 482 Planetary Gear 483 Internal Gear 493 First bearing 492 Second bearing 5 Gear Base 521 Outer surface 6. Sim

Claims

1. a motor that generates a driving force; a spindle that holds a planetary gear and is rotated by the motor; an anvil disposed on the opposite side of the planetary gear in the axial direction of the rotation shaft of the spindle; a main hammer that is rotatable about the rotation axis of the spindle as a central axis and that is movable along the central axis, and that rotates the anvil around the rotation axis; a secondary hammer that rotates integrally with the primary hammer and has a cylindrical portion through which the primary hammer is housed and through which the spindle is inserted; a first bearing disposed between the secondary hammer and the spindle and configured to receive a load in a radial direction relative to the rotation shaft; a gear base that houses the planetary gears and an internal gear that engages with the planetary gears; a second bearing disposed between the secondary hammer and the gear base and adapted to receive a load in a radial direction relative to the rotation shaft; Impact tool.

2. further comprising a shim between the spindle and the gear base; The impact tool according to claim 1 .

3. a case that houses the motor; a cover that houses the secondary hammer, an inner circumferential surface of the cover covering an outer circumferential surface of the gear base; The inner peripheral surface of the case covers the outer peripheral surface of the cover. The impact tool according to claim 1 .

4. an inner peripheral surface of the second bearing is in close contact with an outer peripheral surface of the secondary hammer, a gap is formed between an outer peripheral surface of the second bearing and an inner peripheral surface of the gear base; The impact tool according to claim 1 .

5. the material of the gear base comprises a metal; The impact tool according to claim 1 .

6. The anvil an anvil body that is rotated by the main hammer; an anvil shaft rotated by the anvil body; The impact tool according to claim 1 .

7. Further provided is a torque sensor that measures the torque of the anvil. The impact tool according to claim 1 .

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