Impact tool

Abstract

To provide an impact toll that is suppressed from enlarging in size.SOLUTION: An impact tool is provided with: a motor; a spindle that has a spindle shaft part and a flange part provided at a rear portion of the spindle shaft part, which is rotated by rotation force of the motor; an anvil, arranged closer to a front side than the spindle, which has an anvil shaft part to which a tip tool is attached and an anvil protrusion part that protrudes from the anvil shaft part to outside in a radial direction; and a hammer that has a base part arranged around the spindle shaft part, a front-side ring part that protrudes forward from an outer periphery portion of the base part and a hammer protrusion part that protrudes from an inner peripheral surface of the front-side ring part to inside in the radial direction to hammer the anvil protrusion part in a rotation direction. A front surface of the hammer protrusion part is arranged closer to the front side than the front surface of the base part. The base part has a groove formed at a boundary between the hammer protrusion part and the base part.SELECTED DRAWING: Figure 9

Description

[Technical Field]

[0001] The technology disclosed herein relates to impact tools. [Background technology]

[0002] BACKGROUND ART In the technical field of impact tools, an impact assembly such as that disclosed in Patent Document 1 is known. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Chinese Utility Model No. 205651274 Summary of the Invention [Problem to be solved by the invention]

[0004] In order to improve the workability when using an impact tool, a technique is required to prevent the impact tool from becoming larger.

[0005] The technology disclosed in this specification aims to prevent the impact tool from becoming larger in size. [Means for solving the problem]

[0006] This specification discloses an impact tool. The impact tool may include a spindle having a motor, a spindle shaft, and a flange provided at the rear of the spindle shaft and rotated by the rotational force of the motor; an anvil disposed forward of the spindle and having an anvil shaft to which a tool bit is attached and an anvil protrusion protruding radially outward from the anvil shaft; a base disposed around the spindle shaft; a front ring protruding forward from the outer periphery of the base; and a hammer having a hammer protrusion protruding radially inward from the inner periphery of the front ring and striking the anvil protrusion in the rotational direction. The front surface of the hammer protrusion may be disposed forward of the front surface of the base. The base may have a groove provided at the boundary with the hammer protrusion. [Effects of the Invention]

[0007] According to the technology disclosed in this specification, the impact tool is prevented from becoming large. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a front perspective view showing an impact tool according to a first embodiment. [Figure 2] FIG. 2 is a perspective view showing the impact tool according to the first embodiment, seen from behind. [Figure 3] FIG. 3 is a side view showing the impact tool according to the first embodiment. [Figure 4] FIG. 4 is a vertical cross-sectional view showing the impact tool according to the first embodiment. [Figure 5] FIG. 5 is a vertical cross-sectional view showing an upper portion of the impact tool according to the first embodiment. [Figure 6] FIG. 6 is a cross-sectional view showing the upper part of the impact tool according to the first embodiment. [Figure 7] FIG. 7 is an exploded perspective view of a part of the impact tool according to the first embodiment, seen from the front. [Figure 8]FIG. 8 is an exploded perspective view showing a part of the impact tool according to the first embodiment, as seen from the rear. [Figure 9] FIG. 9 is a front perspective view showing the hammer according to the first embodiment. [Figure 10] FIG. 10 is a view of the hammer according to the first embodiment as seen from the front. [Figure 11] FIG. 11 is a rear perspective view showing the hammer according to the first embodiment. [Figure 12] FIG. 12 is a vertical cross-sectional view showing the hammer according to the first embodiment. [Figure 13] FIG. 13 is a cross-sectional view showing the hammer according to the first embodiment. [Figure 14] FIG. 14 is a front perspective view showing the cup washer according to the first embodiment. [Figure 15] FIG. 15 is a schematic diagram showing the relationship between the anvil and the hammer according to the comparative example. [Figure 16] FIG. 16 is a schematic diagram showing the relationship between the anvil and the hammer according to the first embodiment. [Figure 17] FIG. 17 is a vertical cross-sectional view showing an upper portion of an impact tool according to the second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] In one or more embodiments, the impact tool may include a motor, a spindle having a spindle shaft and a flange provided at a rear portion of the spindle shaft and rotated by the rotational force of the motor, an anvil disposed forward of the spindle and having an anvil shaft to which a tool bit is attached, and an anvil protrusion protruding radially outward from the anvil shaft, a base disposed around the spindle shaft, a front ring protruding forward from an outer periphery of the base, and a hammer protruding radially inward from an inner periphery of the front ring and striking the anvil protrusion in the rotational direction. The front surface of the hammer protrusion may be disposed forward of the front surface of the base. The base may have a groove provided at the boundary with the hammer protrusion.

[0010] In the above configuration, the grooves provided in the base portion prevent the contact area between the hammer protrusion and the anvil protrusion from becoming smaller, while also preventing the impact tool from becoming larger in size in the axial direction parallel to the rotational shaft of the motor. Furthermore, the contact area between the hammer protrusion and the anvil protrusion is prevented from becoming smaller, preventing excessive force from being applied to the hammer protrusion. This prevents wear on the hammer protrusion and shortens the life of the hammer.

[0011] In one or more embodiments, the base portion may have a first front surface and a second front surface disposed at a different position from the first front surface in the circumferential direction and forward of the first front surface. One circumferential end of the first front surface may be connected to the other circumferential end of the front surface of the hammer protrusion via a first connecting surface. One circumferential end of the second front surface may be connected to the other circumferential end of the first front surface via a second connecting surface. The first connecting surface may include a first flat surface parallel to the rotation axis of the hammer, at least a portion of which faces the struck surface of the anvil protrusion, and a first curved surface connecting a rear end of the first flat surface to the one circumferential end of the first front surface. The groove may be defined by the first front surface, the first connecting surface, and the second connecting surface.

[0012] In the above configuration, the first flat surface and the first front surface are connected via the first curved surface, which prevents stress from concentrating on the boundary between the first flat surface and the first front surface, thereby preventing cracks from occurring in the hammer, for example.

[0013] In one or more embodiments, the outer circumferential surface of the front ring portion may be angled radially inward toward the front.

[0014] With the above-described configuration, the increase in the radial size of the hammer is suppressed. Since the increase in the radial size of the hammer is suppressed, the increase in the radial size of the front part of the hammer case is also suppressed.

[0015] In one or more embodiments, the front ring portion may be positioned radially outward of the anvil projection, and the front ring portion and at least a portion of the anvil projection may be axially aligned.

[0016] In the above configuration, the moment of inertia of the hammer increases when the hammer protrusion strikes the anvil protrusion, thereby increasing the striking force.

[0017] In one or more embodiments, the second connecting surface may include a second flat surface parallel to the rotation axis of the hammer and facing the first flat surface, and a second curved surface connecting a rear end of the second flat surface to the other circumferential end of the first front surface. The distance between the first flat surface and the second flat surface may be smaller than the circumferential dimension of the anvil protrusion.

[0018] In the above configuration, the second flat surface and the first front surface are connected via the second curved surface, which prevents stress from concentrating at the boundary between the second flat surface and the first front surface. This prevents cracks from occurring in the hammer, for example. Furthermore, the distance between the first flat surface and the second flat surface, which indicates the width of the groove, is smaller than the circumferential dimension of the anvil protrusion, allowing the anvil protrusion to rotate smoothly without getting caught in the groove.

[0019] In one or more embodiments, the distance between the first plane and the second plane may be greater than the sum of the radii of the first curved surface and the second curved surface.

[0020] In the above configuration, a first curved surface and a second curved surface are formed inside the groove. For example, if the radius of each of the first curved surface and the second curved surface is 0.5 mm, the width of the groove may be about 4 mm.

[0021] In one or more embodiments, the bearing may include a coil spring disposed around the spindle shaft portion, a washer disposed rearward of the base portion and supporting a front end of the coil spring, and a support ball disposed in a support groove provided in a rear surface of the base portion and supporting a front surface of the washer. The position of the support groove and the position of at least a portion of the second front surface may be the same in both the radial and circumferential directions.

[0022] With the above configuration, the hammer can be made smaller.

[0023] In one or more embodiments, the hammer may have a rear ring portion that projects rearwardly from the outer periphery of the base portion.

[0024] In the above configuration, the moment of inertia of the hammer increases when the hammer protrusion strikes the anvil protrusion, thereby increasing the striking force.

[0025] In one or more embodiments, the hammer may have a support ring portion that protrudes rearward from the inner periphery of the base portion and is supported on the spindle shaft portion via the hammer ball. A washer may be disposed radially between the rear ring portion and the support ring portion.

[0026] In the above configuration, the front end of the coil spring fits between the rear ring portion and the support ring portion, which prevents the impact tool from becoming too large in the axial direction parallel to the rotational shaft of the motor.

[0027] In one or more embodiments, the washer may be located forward of the rear end of the hammer ball.

[0028] In the above configuration, the impact tool is prevented from becoming larger in size in the axial direction parallel to the rotation shaft of the motor.

[0029] Hereinafter, an embodiment will be described with reference to the drawings. In the embodiment, the positional relationship of each part will be described using the terms left, right, front, rear, top, and bottom. These terms indicate relative positions or directions based on the center of the impact tool 1. The impact tool 1 has a motor 6 as a power source.

[0030] In the embodiment, the direction parallel to the rotation axis AX of the motor 6 is referred to as the axial direction, the direction circumferentially around the rotation axis AX is referred to as the circumferential direction or rotation direction, and the radial direction of the rotation axis AX is referred to as the radial direction.

[0031] The rotation axis AX extends in the front-to-rear direction. One axial side is the front, and the other axial side is the rear. In addition, in the radial direction, a position closer to or approaching the rotation axis AX will be referred to as the radially inner side, and a position farther from or away from the rotation axis AX will be referred to as the radially outer side.

[0032] [First embodiment] A first embodiment will be described. <Impact tool> Fig. 1 is a front perspective view of the impact tool 1 according to this embodiment. Fig. 2 is a rear perspective view of the impact tool 1 according to this embodiment. Fig. 3 is a side view of the impact tool 1 according to this embodiment. Fig. 4 is a vertical cross-sectional view of the impact tool 1 according to this embodiment.

[0033] In this embodiment, the impact tool 1 is an impact driver, which is a type of screw tightening tool, and includes a housing 2, a hammer case 4, a hammer case cover 5A, a bumper 5B, a housing cover 5C, a motor 6, a speed reduction mechanism 7, a spindle 8, a striking mechanism 9, an anvil 10, a tool holding mechanism 11, a fan 12, a battery mounting portion 13, a trigger lever 14, a forward / reverse rotation switching lever 15, an operation display portion 16, a light 17, and a controller 18.

[0034] The housing 2 is made of synthetic resin. In this embodiment, the housing 2 is made of nylon. The housing 2 includes a left housing 2L and a right housing 2R located to the right of the left housing 2L. The left housing 2L and the right housing 2R are fixed together with a plurality of screws 2S. The housing 2 is made up of a pair of split housing halves.

[0035] The housing 2 has a motor accommodating portion 21, a grip portion 22, and a battery holding portion 23.

[0036] The motor accommodating portion 21 accommodates the motor 6. The motor accommodating portion 21 has a cylindrical portion 21A and a rear plate portion 21B that is integrally connected to the rear end portion of the cylindrical portion 21A. The motor accommodating portion 21 accommodates at least a portion of the hammer case 4.

[0037] The grip portion 22 is held by an operator and extends downward from the motor housing portion 21. The trigger lever 14 is provided on the upper portion of the grip portion 22.

[0038] The battery holding portion 23 holds the battery pack 25 via the battery attachment portion 13. The battery holding portion 23 is connected to the lower end of the grip portion 22. The external dimensions of the battery holding portion 23 are larger than the external dimensions of the grip portion 22 in both the front-rear and left-right directions.

[0039] The motor accommodating section 21 has an intake port 19 and an exhaust port 20. The exhaust port 20 is provided rearward of the intake port 19. Air in the external space of the housing 2 flows into the internal space of the housing 2 through the intake port 19. Air in the internal space of the housing 2 flows out to the external space of the housing 2 through the exhaust port 20.

[0040] The hammer case 4 houses at least a portion of the reduction mechanism 7, the spindle 8, the striking mechanism 9, and the anvil 10. At least a portion of the reduction mechanism 7 is disposed inside the bearing box 24. The reduction mechanism 7 includes a plurality of gears.

[0041] The hammer case 4 is made of metal. In this embodiment, the hammer case 4 is made of aluminum. The hammer case 4 is cylindrical. The hammer case 4 is connected to the front part of the motor accommodating section 21. A bearing box 24 is fixed to the rear part of the hammer case 4. A cylindrical outer surface is formed on the outer periphery of the bearing box 24. A cylindrical inner surface is formed on the inner periphery of the hammer case 4. The bearing box 24 is fitted to the rear part of the hammer case 4 via an O-ring 24A. The cylindrical outer surface of the bearing box 24 and the cylindrical inner surface of the hammer case 4 are connected via the O-ring 24A, thereby fixing the bearing box 24 and the hammer case 4. The hammer case 4 is sandwiched between the left housing 2L and the right housing 2R. At least a portion of the hammer case 4 is housed in the motor accommodating section 21. The bearing box 24 is fixed to both the motor accommodating section 21 and the hammer case 4.

[0042] The hammer case cover 5A covers at least a portion of the surface of the hammer case 4. The bumper 5B is attached to the front end of the hammer case 4. The hammer case cover 5A and the bumper 5B protect the hammer case 4. The hammer case cover 5A and the bumper 5B prevent contact between the hammer case 4 and objects around the hammer case 4. The housing cover 5C covers at least a portion of the surface of the housing 2.

[0043] The motor 6 is a power source for the impact tool 1. The motor 6 is an inner rotor type brushless motor. The motor 6 has a stator 26 and a rotor 27. The stator 26 is supported by the motor housing 21. At least a portion of the rotor 27 is disposed inside the stator 26. The rotor 27 rotates relative to the stator 26. The rotor 27 rotates about a rotation axis AX extending in the front-rear direction.

[0044] The reduction mechanism 7 connects the rotor 27 and the spindle 8. The reduction mechanism 7 transmits the rotation of the rotor 27 to the spindle 8. The reduction mechanism 7 rotates the spindle 8 at a rotational speed lower than the rotational speed of the rotor 27. The reduction mechanism 7 is disposed forward of the motor 6. The reduction mechanism 7 includes a planetary gear mechanism. The reduction mechanism 7 has a plurality of gears. The gears of the reduction mechanism 7 are driven by the rotor 27.

[0045] The spindle 8 rotates by the rotational force of the rotor 27 transmitted by the reduction mechanism 7. The spindle 8 is disposed forward of at least a portion of the motor 6. The spindle 8 is disposed forward of the stator 26. At least a portion of the spindle 8 is disposed forward of the rotor 27. At least a portion of the spindle 8 is disposed forward of the reduction mechanism 7. The spindle 8 is disposed rearward of the anvil 10.

[0046] The striking mechanism 9 strikes the anvil 10 in the rotational direction based on the rotational force of the spindle 8 rotated by the motor 6. The rotational force of the motor 6 is transmitted to the striking mechanism 9 via the reduction mechanism 7 and the spindle 8.

[0047] The anvil 10 is an output shaft of the impact tool 1 that rotates based on the rotational force of the rotor 27. The anvil 10 is disposed forward of the motor 6. The anvil 10 has a tool hole 10A into which a tool bit is inserted. The tool hole 10A is provided at the front end of the anvil 10. The tool bit is attached to the anvil 10.

[0048] The tool holding mechanism 11 holds the tool bit inserted into the tool hole 10A of the anvil 10. The tool holding mechanism 11 is arranged around the front part of the anvil 10. The tool holding mechanism 11 is capable of attaching and detaching the tool bit.

[0049] The fan 12 generates an airflow for cooling the motor 6. The fan 12 is disposed rearward of the stator 26 of the motor 6. The fan 12 is fixed to at least a portion of the rotor 27. As the fan 12 rotates, air from the external space of the housing 2 flows into the internal space of the housing 2 through the air intake port 19. The air that has flowed into the internal space of the housing 2 cools the motor 6 by circulating through the internal space of the housing 2. As the fan 12 rotates, the air that has circulated through the internal space of the housing 2 flows out into the external space of the housing 2 through the air exhaust port 20.

[0050] The battery attachment section 13 is connected to the battery pack 25. The battery pack 25 is attached to the battery attachment section 13. The battery pack 25 is detachable from the battery attachment section 13. The battery attachment section 13 is disposed below the battery holding section 23. The battery pack 25 is attached to the battery attachment section 13 by being inserted into the battery attachment section 13 from the front of the battery holding section 23. The battery pack 25 is removed from the battery attachment section 13 by being pulled forward from the battery attachment section 13. The battery pack 25 includes a secondary battery. In the embodiment, the battery pack 25 includes a rechargeable lithium-ion battery. When attached to the battery attachment section 13, the battery pack 25 can supply power to the impact tool 1. The motor 6 is driven by the power supplied from the battery pack 25.

[0051] The trigger lever 14 is operated by an operator to start the motor 6. Operating the trigger lever 14 switches between driving and stopping the motor 6. The trigger lever 14 is provided on the grip portion 22.

[0052] The forward / reverse switching lever 15 is operated by an operator. By operating the forward / reverse switching lever 15, the rotation direction of the motor 6 is switched from one of the forward direction and the reverse direction to the other. By switching the rotation direction of the motor 6, the rotation direction of the spindle 8 is switched. The forward / reverse switching lever 15 is provided on the upper part of the grip portion 22.

[0053] The operation display unit 16 has a plurality of operation buttons 16A. When the operator operates the operation buttons 16A, the operation mode of the motor 6 is switched. The operation display unit 16 is provided on the battery holding unit 23. The operation display unit 16 is provided on the upper surface of the battery holding unit 23, further forward than the grip unit 22.

[0054] The light 17 emits illumination light. The light 17 illuminates the anvil 10 and the area around the anvil 10 with the illumination light. The light 17 illuminates the area in front of the anvil 10 with the illumination light. The light 17 also illuminates the tool attachment attached to the anvil 10 and the area around the tool attachment with the illumination light. The light 17 is disposed above the trigger lever 14.

[0055] The controller 18 outputs a control signal to control the motor 6. The controller 18 includes a substrate on which a plurality of electronic components are mounted. Examples of the electronic components mounted on the substrate include a processor such as a CPU (Central Processing Unit), a non-volatile memory such as a ROM (Read Only Memory) or storage, a volatile memory such as a RAM (Random Access Memory), a transistor, and a resistor. The controller 18 is housed in a battery holding unit 23.

[0056] Fig. 5 is a vertical cross-sectional view showing an upper part of the impact tool 1 according to this embodiment. Fig. 6 is a horizontal cross-sectional view showing an upper part of the impact tool 1 according to this embodiment. Fig. 7 is an exploded perspective view from the front showing a part of the impact tool 1 according to this embodiment. Fig. 8 is an exploded perspective view from the rear showing a part of the impact tool 1 according to this embodiment.

[0057] The hammer case 4 has a first cylindrical portion 401, a second cylindrical portion 402, and a case connecting portion 403. The first cylindrical portion 401 is arranged around the striking mechanism 9. The second cylindrical portion 402 is arranged forward of the first cylindrical portion 401. The outer diameter of the second cylindrical portion 402 is smaller than the outer diameter of the first cylindrical portion 401. The case connecting portion 403 is arranged to connect the front end of the first cylindrical portion 401 and the outer circumferential surface of the second cylindrical portion 402. The rear end of the second cylindrical portion 402 protrudes rearward from the case connecting portion 403.

[0058] The motor 6 has a stator 26 and a rotor 27. The stator 26 has a stator core 28, a front insulator 29, a rear insulator 30, and a coil 31. The rotor 27 rotates about a rotation axis AX. The rotor 27 has a rotor core portion 32, a rotor shaft portion 33, a rotor magnet 34, and a sensor magnet 35.

[0059] The stator core 28 is disposed radially outward of the rotor 27. The stator core 28 includes a plurality of stacked steel plates. The steel plates are metal plates whose main component is iron. The stator core 28 is cylindrical. The stator core 28 has a plurality of teeth that support the coils 31.

[0060] The front insulator 29 is provided in the front portion of the stator core 28. The rear insulator 30 is provided in the rear portion of the stator core 28. The front insulator 29 and the rear insulator 30 are each an electrical insulating member made of synthetic resin. The front insulator 29 is arranged so as to cover part of the surface of the teeth. The rear insulator 30 is arranged so as to cover part of the surface of the teeth.

[0061] The coil 31 is attached to the stator core 28 via the front insulator 29 and the rear insulator 30. Multiple coils 31 are arranged. The coils 31 are arranged around the teeth of the stator core 28 via the front insulator 29 and the rear insulator 30. The coils 31 and the stator core 28 are electrically insulated by the front insulator 29 and the rear insulator 30. The multiple coils 31 are connected via fusing terminals 38.

[0062] The rotor core 32 and the rotor shaft 33 are both made of steel. The rotor shaft 33 protrudes in the front-to-rear direction from the end face of the rotor core 32. The rotor shaft 33 includes a front shaft portion 33F that protrudes forward from the front end face of the rotor core 32 and a rear shaft portion 33R that protrudes rearward from the rear end face of the rotor core 32.

[0063] The rotor magnet 34 is fixed to the rotor core portion 32. The rotor magnet 34 is cylindrical. The rotor magnet 34 is arranged around the rotor core portion 32.

[0064] The sensor magnet 35 is fixed to the rotor core portion 32. The sensor magnet 35 has an annular shape. The sensor magnet 35 is disposed on the front end surface of the rotor core portion 32 and the front end surface of the rotor magnet 34.

[0065] A sensor board 37 is attached to the front insulator 29. The sensor board 37 is fixed to the front insulator 29 with screws 29S. The sensor board 37 has a disk-shaped circuit board with a hole in the center and a rotation detection element supported by the circuit board. At least a portion of the sensor board 37 faces the sensor magnet 35. The rotation detection element detects the position of the sensor magnet 35 of the rotor 27, thereby detecting the position of the rotor 27 in the rotational direction.

[0066] The rotor shaft portion 33 is rotatably supported by a rotor bearing 39. The rotor bearing 39 includes a front rotor bearing 39F that rotatably supports the front shaft portion 33F, and a rear rotor bearing 39R that rotatably supports the rear shaft portion 33R.

[0067] The front rotor bearing 39F is held in the bearing box 24. The bearing box 24 has a recess 241 recessed forward from the rear surface of the bearing box 24. The front rotor bearing 39F is disposed in the recess 241. The rear rotor bearing 39R is held by the rear plate portion 21B. The front end of the rotor shaft portion 33 is disposed in the internal space of the hammer case 4 through an opening in the bearing box 24.

[0068] The fan 12 is fixed to the rear of the rear shaft portion 33R via a bushing 12A. The fan 12 is disposed between the rear rotor bearing 39R and the stator 26. The fan 12 rotates due to the rotation of the rotor 27. As the rotor shaft portion 33 rotates, the fan 12 rotates together with the rotor shaft portion 33.

[0069] A pinion gear 41 is formed on the front end of the rotor shaft portion 33. The pinion gear 41 is connected to at least a part of the reduction mechanism 7. The rotor shaft portion 33 is connected to the reduction mechanism 7 via the pinion gear 41.

[0070] The reduction mechanism 7 has a plurality of planetary gears 42 arranged around the pinion gear 41, and an internal gear 43 arranged around the plurality of planetary gears 42. The pinion gear 41, the planetary gear 42, and the internal gear 43 are each housed in the hammer case 4. Each of the plurality of planetary gears 42 meshes with the pinion gear 41. The planetary gear 42 is rotatably supported on the spindle 8 via a pin 42P. The spindle 8 is rotated by the planetary gear 42. The internal gear 43 has internal teeth that mesh with the planetary gear 42. The internal gear 43 is rotationally fixed to the bearing box 24. The internal gear 43 is always non-rotatable relative to the bearing box 24. The bearing box 24 is rotationally fixed relative to the left housing 2L and the right housing 2R.

[0071] When the rotor shaft portion 33 is rotated by the drive of the motor 6, the pinion gear 41 rotates, and the planetary gear 42 revolves around the pinion gear 41. The planetary gear 42 revolves while meshing with the internal teeth of the internal gear 43. Due to the revolution of the planetary gear 42, the spindle 8 connected to the planetary gear 42 via the pin 42P rotates at a rotational speed lower than the rotational speed of the rotor shaft portion 33.

[0072] The spindle 8 rotates due to the rotational force of the motor 6. The spindle 8 transmits the rotational force of the motor 6 to the anvil 10 via the striking mechanism 9. The spindle 8 has a spindle shaft portion 801 and a flange portion 802 provided at the rear of the spindle shaft portion 801. The planetary gear 42 is rotatably supported on the flange portion 802 via a pin 42P. The rotation axis of the spindle 8 coincides with the rotation axis AX of the motor 6. The spindle 8 rotates around the rotation axis AX. The spindle 8 is rotatably supported by a spindle bearing 44. A protrusion 803 is provided at the rear end of the spindle 8. The protrusion 803 protrudes rearward from the flange portion 802. The protrusion 803 is arranged to surround the spindle bearing 44.

[0073] The bearing box 24 is disposed around at least a portion of the periphery of the spindle 8. The spindle bearing 44 is held in the bearing box 24. The bearing box 24 has a protrusion 242 that protrudes forward from the front surface of the bearing box 24. The spindle bearing 44 is disposed around the protrusion 242.

[0074] The striking mechanism 9 has a hammer 47, a hammer ball 48, a coil spring 50, and a washer 53. The striking mechanism 9 including the hammer 47, the hammer ball 48, the coil spring 50, and the washer 53 is housed in a first cylindrical portion 401 of the hammer case 4. The first cylindrical portion 401 is disposed around the hammer 47.

[0075] The hammer 47 is disposed forward of the speed reduction mechanism 7. The hammer 47 is disposed around the spindle shaft portion 801. The hammer 47 is supported by the spindle shaft portion 801.

[0076] The hammer 47 is rotated by the motor 6. The rotational force of the motor 6 is transmitted to the hammer 47 via the reduction mechanism 7 and the spindle 8. The hammer 47 can rotate together with the spindle 8 based on the rotational force of the spindle 8 rotated by the motor 6. The rotation axis of the hammer 47, the rotation axis of the spindle 8, and the rotation axis AX of the motor 6 coincide with each other. The hammer 47 rotates around the rotation axis AX.

[0077] Fig. 9 is a perspective view of the hammer 47 according to this embodiment, seen from the front. Fig. 10 is a view of the hammer 47 according to this embodiment as seen from the front. Fig. 11 is a perspective view of the hammer 47 according to this embodiment as seen from the rear. Fig. 12 is a vertical cross-sectional view of the hammer 47 according to this embodiment. Fig. 13 is a horizontal cross-sectional view of the hammer 47 according to this embodiment.

[0078] The hammer 47 has a base portion 471 , a front ring portion 472 , a rear ring portion 473 , a support ring portion 474 , and a hammer protrusion portion 475 .

[0079] The base portion 471 is disposed around the spindle shaft portion 801. The base portion 471 is annular. The spindle shaft portion 801 is disposed inside the base portion 471.

[0080] The front ring portion 472 protrudes forward from the outer periphery of the base portion 471. The front ring portion 472 is cylindrical. An outer periphery surface 472A of the front ring portion 472 is inclined radially inward toward the front.

[0081] The rear ring portion 473 protrudes rearward from the outer periphery of the base portion 471. The rear ring portion 473 is cylindrical.

[0082] The support ring portion 474 protrudes rearward from the inner periphery of the base portion 471. The support ring portion 474 is cylindrical. The support ring portion 474 is disposed around the spindle shaft portion 801. The support ring portion 474 is supported by the spindle shaft portion 801 via the hammer ball 48.

[0083] The hammer protrusion 475 protrudes radially inward from the inner circumferential surface of the front ring portion 472. The hammer protrusion 475 protrudes forward from the front surface of the base portion 471. A front surface 83 of the hammer protrusion 475 is disposed forward of the front surface of the base portion 471. The front surface of the front ring portion 472 and the front surface 83 of the hammer protrusion 475 are disposed in the same plane. Two hammer protrusions 475 are disposed in the circumferential direction.

[0084] A recess 476 is formed by the rear surface of the base portion 471, the inner peripheral surface of the rear ring portion 473, and the outer peripheral surface of the support ring portion 474. The recess 476 is formed so as to be recessed forward from the rear surface of the hammer 47.

[0085] As shown in FIGS. 12 and 13, the position of the rear end 473R of the outer ring portion 473 and the position of the rear end 474R of the support ring portion 474 are the same in the front-rear direction.

[0086] The base portion 471 has grooves 90 formed at the boundary with the hammer protrusion 475. The grooves 90 extend in the radial direction. The grooves 90 are formed on one circumferential side and the other circumferential side of the hammer protrusion 475.

[0087] The front surface of the base portion 471 includes a first front surface 81 and a second front surface 82 that is disposed at a different position in the circumferential direction from the first front surface 81. The second front surface 82 is disposed forward of the first front surface 81.

[0088] One circumferential end of the first front surface 81 is connected to the other circumferential end of the front surface 83 of the hammer protrusion 475 via a first connecting surface 84. One circumferential end of the second front surface 82 is connected to the other circumferential end of the first front surface 81 via a second connecting surface 85. A groove 90 provided on the other circumferential side of the hammer protrusion 475 is defined by the first connecting surface 84 connected to the first circumferential end of the first front surface 81 and the first circumferential end of the first front surface 81, and the second connecting surface 85 connected to the other circumferential end of the first front surface 81.

[0089] The groove 90 provided on one circumferential side of the hammer protrusion 475 is defined by the first front surface 81, a first connecting surface 84 connected to the other circumferential end of the first front surface 81, and a second connecting surface 85 connected to one circumferential end of the first front surface 81.

[0090] The first connecting surface 84 includes a first flat surface 84A and a first curved surface 84B. The first flat surface 84A is parallel to the rotation axis AX of the hammer 47. The first flat surface 84A is disposed to extend radially. In a groove 90 provided on the other circumferential side of the hammer protrusion 475, the first curved surface 84B is disposed to connect the rear end of the first flat surface 84A to one circumferential end of the first front surface 81. In a groove 90 provided on the one circumferential side of the hammer protrusion 475, the first curved surface 84B is disposed to connect the rear end of the first flat surface 84A to the other circumferential end of the first front surface 81.

[0091] The second connecting surface 85 includes a second flat surface 85A and a second curved surface 85B. The second flat surface 85A is parallel to the rotation axis AX of the hammer 47. The second flat surface 85A is disposed to extend radially. In one groove 90, the second flat surface 85A is disposed to face the first flat surface 84A. In the groove 90 provided on the other circumferential side of the hammer protrusion 475, the second curved surface 85B is disposed to connect the rear end of the second flat surface 85A to the other circumferential end of the first front surface 81. In the groove 90 provided on one circumferential side of the hammer protrusion 475, the second curved surface 85B is disposed to connect the rear end of the second flat surface 85A to one circumferential end of the first front surface 81.

[0092] The hammer ball 48 is made of metal such as steel. The hammer ball 48 is disposed between the spindle shaft portion 801 and the hammer 47. The spindle 801 has a spindle groove 804 in which at least a portion of the hammer ball 48 is disposed. The spindle groove 804 is provided on a portion of the outer circumferential surface of the spindle shaft portion 801. The hammer 47 has a hammer groove 477 in which at least a portion of the hammer ball 48 is disposed. The hammer groove 477 is provided on a portion of the inner circumferential surface of the support ring portion 474. The hammer ball 48 is disposed between the spindle groove 804 and the hammer groove 477. The hammer ball 48 can roll inside the spindle groove 804 and inside the hammer groove 477. The hammer 47 is movable along with the hammer ball 48. The spindle 8 and the hammer 47 can move relative to each other in the axial direction and the rotational direction within a movable range defined by the spindle groove 804 and the hammer groove 477 .

[0093] The coil spring 50 is disposed around the spindle shaft portion 801. In this embodiment, the coil spring 50 includes a first coil spring 51 and a second coil spring 52 disposed in parallel to each other. The second coil spring 52 is disposed radially inward of the first coil spring 51.

[0094] The rear end of the first coil spring 51 and the rear end of the second coil spring 52 are supported by the flange portion 802. The front end of the first coil spring 51 and the front end of the second coil spring 52 are disposed inside the recess 476. A washer 53 is disposed inside the recess 476. The front end of the first coil spring 51 and the front end of the second coil spring 52 are supported by the washer 53. The washer 53 is ring-shaped. Each of the first coil spring 51 and the second coil spring 52 constantly generates an elastic force that moves the hammer 47 forward.

[0095] The washer 53 is disposed rearward of the base portion 471. The washer 53 supports the front end portion of the coil spring 50. In the radial direction, the washer 53 is disposed between the rear ring portion 473 and the support ring portion 474. The washer 53 is disposed inside the recess 476. The washer 53 is supported by the hammer 47 via a plurality of support balls 54. When the hammer 47 is disposed at the frontmost position within the movable range of the hammer 47 in the front-rear direction, the washer 53 is disposed forward of the rear end portion of the hammer ball 48.

[0096] The support ball 54 is disposed in a support groove 478 provided in the rear surface of the base portion 471. The support ball 54 supports the front surface of the washer 53. The support groove 478 is provided in a ring shape so as to surround the rotation axis AX.

[0097] The position of the support groove 478 and the position of at least a portion of the second front surface 82 are the same in both the radial and circumferential directions. The base portion 471 has a thin portion in which the groove 90 is provided and a thick portion in which the groove 90 is not provided. The thin portion includes the first front surface 81. The thick portion includes the second front surface 82. The support groove 478 is provided in the thick portion of the base portion 471.

[0098] The anvil 10 has an anvil shaft portion 101 , an anvil protrusion portion 102 , and an anvil convex portion 103 .

[0099] The anvil shaft portion 101 is disposed forward of the spindle 8 and the hammer 47. A tool bit is attached to the anvil shaft portion 101. A tool hole 10A into which the tool bit is inserted is provided so as to extend rearward from the front end portion of the anvil shaft portion 101.

[0100] 5, the rear end 10B of the tool hole 10A is located at the same position as at least a portion of the front ring portion 472 in the front-rear direction. The rear end 10B of the tool hole 10A may also be located at the same position as at least a portion of the base portion 471. This shortens the axial length, which indicates the distance between the rear end of the rear plate portion 21B and the front end of the anvil 10 in the front-rear direction.

[0101] The anvil protrusion 102 protrudes radially outward from the rear of the anvil shaft portion 101. The anvil protrusion 102 is struck in the rotational direction by the hammer protrusion 475. The anvil protrusion 102 has a struck surface 104 that is struck by the hammer protrusion 475. The struck surface 104 is parallel to the rotation axis AX of the anvil 10. At least a portion of the first flat surface 84A of the hammer protrusion 475 faces the struck surface 104 of the anvil protrusion 102.

[0102] The front ring portion 472 is disposed radially outward of the anvil projection 102. In the axial direction, the position of the front ring portion 472 and the position of at least a portion of the anvil projection 102 are the same. The outer periphery of the anvil projection 102 and the inner periphery of the front ring portion 472 are spaced apart.

[0103] The base portion 471 is disposed rearward of the anvil protrusion 102. The rear surface of the anvil protrusion 102 and the front surface of the base portion 471 are spaced apart.

[0104] The anvil protrusion 103 protrudes rearward from the rear end of the anvil 10. The spindle 8 is disposed behind the anvil 10. A spindle recess 805 is provided at the front end of the spindle shaft portion 801. The anvil protrusion 103 is disposed in the spindle recess 805.

[0105] As shown in FIG. 6, at least a portion of the outer peripheral surface of the spindle shaft portion 801 is the hammer sliding surface 8A on which the support ring portion 474 of the hammer 47 slides. At least a portion of the inner peripheral surface of the spindle recess 805 is the anvil sliding surface 8B on which the anvil protrusion 103 of the anvil 10 slides. The anvil sliding surface 8B is disposed radially inward of the hammer sliding surface 8A. In the front-rear direction, the hammer sliding surface 8A and the anvil sliding surface 8B at least partially overlap. Because the hammer sliding surface 8A and at least a portion of the anvil sliding surface 8B are positioned in the same position in the front-rear direction, the axial length, which indicates the distance between the rear end of the rear plate portion 21B and the front end of the anvil 10 in the front-rear direction, is shortened.

[0106] 6 and 13, at least a part of the inner circumferential surface of the support ring portion 474 of the hammer 47 is a sliding surface 479 on which the hammer sliding surface 8A of the spindle shaft portion 801 slides. The front end of the sliding surface 479 is disposed forward of the washer 53. By disposing the sliding surface 479 forward of the washer 53, the dimension of the hammer 47 in the front-to-rear direction is shortened.

[0107] The anvil 10 is rotatably supported by the anvil bearing 46. The rotation axis of the anvil 10, the rotation axis of the hammer 47, the rotation axis of the spindle 8, and the rotation axis AX of the motor 6 are all coincident. The anvil 10 rotates around the rotation axis AX. The anvil bearing 46 is disposed around the anvil shaft portion 101. The anvil bearing 46 is disposed inside the second cylindrical portion 402 of the hammer case 4. The anvil bearing 46 is held in the second cylindrical portion 402 of the hammer case 4. The anvil bearing 46 rotatably supports the front portion of the anvil shaft portion 101. An O-ring 45 is disposed between the anvil bearing 46 and the anvil shaft portion 101. The O-ring 45 contacts the outer periphery of the anvil shaft portion 101 and the inner periphery of the anvil bearing 46.

[0108] In this embodiment, two anvil bearings 46 are arranged in the axial direction, and two O-rings 45 are arranged in the axial direction.

[0109] The hammer protrusion 475 can come into contact with the anvil protrusion 102. When the motor 6 is driven while the hammer 47 and the anvil protrusion 102 are in contact with each other, the anvil 10 rotates together with the hammer 47 and the spindle 8.

[0110] The anvil 10 is struck in the rotational direction by the hammer 47. For example, during a screw tightening operation, if the load acting on the anvil 10 becomes too high, a situation may arise in which the anvil 10 cannot be rotated by the load of the coil spring 50 alone. When the load of the coil spring 50 alone cannot rotate the anvil 10, the rotation of the anvil 10 and the hammer 47 stops. The spindle 8 and the hammer 47 can move relative to each other in the axial and circumferential directions via the hammer ball 48. Even when the rotation of the hammer 47 stops, the rotation of the spindle 8 continues due to the power generated by the motor 6. When the spindle 8 rotates while the rotation of the hammer 47 is stopped, the hammer ball 48 moves rearward while being guided by the spindle groove 804 and the hammer groove 477. The hammer 47 receives force from the hammer ball 48 and moves rearward along with the hammer ball 48. That is, the hammer 47 moves rearward by rotating the spindle 8 while the rotation of the anvil 10 is stopped. When the hammer 47 moves rearward, the contact between the hammer 47 and the anvil protrusion 102 is released.

[0111] As described above, the coil spring 50 constantly generates an elastic force that moves the hammer 47 forward. After moving backward, the hammer 47 moves forward due to the elastic force of the coil spring 50. When the hammer 47 moves forward, it receives a rotational force from the hammer ball 48. That is, the hammer 47 moves forward while rotating. When the hammer 47 moves forward while rotating, the hammer protrusion 475 comes into contact with the anvil protrusion 102 while rotating. As a result, the anvil protrusion 102 is struck in the rotational direction by the hammer protrusion 475. Both the power of the motor 6 and the inertial force of the hammer 47 act on the anvil 10. Therefore, the anvil 10 can rotate around the rotation axis AX with high torque.

[0112] The tool holding mechanism 11 includes a ball 71 , a sleeve 73 , and a coil spring 74 .

[0113] The anvil shaft portion 101 has a support recess 76 that supports the ball 71. The support recess 76 is formed on the outer surface of the anvil shaft portion 101. In this embodiment, two support recesses 76 are formed in the anvil shaft portion 101.

[0114] The balls 71 are movably supported on the anvil 10. The balls 71 are arranged in the support recesses 76. The balls 71 are arranged one per support recess 76.

[0115] A through hole connecting the inner surface of the support recess 76 and the inner surface of the tool hole 10A is formed in the anvil shaft portion 101. The diameter of the ball 71 is smaller than the diameter of the through hole. With the ball 71 supported by the support recess 76, it is disposed inside the tool hole 10A via at least a portion of the ball 71. The ball 71 can fix a tool bit inserted into the tool hole 10A. The ball 71 is movable between an engagement position where the tool bit is fixed and a release position where the tool bit is released from the engagement position.

[0116] The sleeve 73 is a cylindrical member. The sleeve 73 is disposed around the anvil shaft portion 101. The sleeve 73 is movable around the anvil shaft portion 101 between a blocking position that blocks radially outward movement of the balls 71 and an allowing position that allows radially outward movement of the balls 71.

[0117] The sleeve 73 is disposed in the blocking position, thereby preventing the ball 71 from moving radially outward. The sleeve 73 is disposed in the blocking position, thereby maintaining the bit tool fixed by the ball 71.

[0118] When the sleeve 73 is moved to the permissible position, the ball 71 is permitted to move radially outward. When the sleeve 73 is placed at the permissible position, the state in which the tool bit is fixed by the ball 71 can be released.

[0119] The coil spring 74 generates an elastic force that moves the sleeve 73 to the blocking position. The coil spring 74 is disposed around the anvil shaft portion 101. The blocking position is set rearward of the allowable position. The coil spring 74 generates an elastic force that moves the sleeve 73 rearward.

[0120] In this embodiment, the impact tool 1 includes a cup washer 61 for preventing contact between the anvil protrusion 102 and the hammer case 4. In this embodiment, the cup washer 61 prevents contact between the front surface of the anvil protrusion 102 and the rear end of the second cylindrical portion 402. The second cylindrical portion 402 receives the load from the anvil protrusion 102 via the cup washer 61.

[0121] The cup washer 61 is supported by the hammer case 4. In this embodiment, the outer periphery of the cup washer 61 is disposed in a groove 404 provided in the inner periphery of the first cylindrical portion 401. The impact tool 1 also includes a suppression member 62 that suppresses the cup washer 61 from slipping out rearward from the groove 404.

[0122] 14 is a front perspective view showing the cup washer 61 according to this embodiment. The cup washer 61 has an inner ring portion 611, an outer ring portion 612, and a connecting ring portion 613.

[0123] The inner ring portion 611 is disposed so as to face the front surface of the anvil protrusion 102. The inner ring portion 611 contacts the rear end surface of the anvil bearing 46.

[0124] The outer ring portion 612 is disposed around the anvil bearing 46. The outer ring portion 612 is disposed radially outward of the inner ring portion 611 and forward of the inner ring portion 611. In the axial direction (front-rear direction), the position of the outer ring portion 612 and the position of at least a portion of the anvil bearing 46 are the same. The outer ring portion 612 is supported by the hammer case 4. The outer ring portion 612 is disposed in a groove portion 404 provided on the inner circumferential surface of the first cylindrical portion 401.

[0125] At least a part of the rear surface of case connecting portion 403 faces the front surface of outer ring portion 612. The rear surface of case connecting portion 403 and the front surface of outer ring portion 612 face each other with a gap therebetween.

[0126] The connecting ring portion 613 is disposed so as to connect the outer edge of the inner ring portion 611 and the inner edge of the outer ring portion 612 .

[0127] In this embodiment, the anvil bearing 46 is a ball bearing. The anvil bearing 46 has an inner ring, balls, and an outer ring. The inner ring of the anvil bearing 46 contacts the O-ring 45. The balls are arranged radially between the inner ring and the outer ring. The balls contact each of the inner ring and the outer ring. Multiple balls are arranged circumferentially. The outer ring is arranged radially outward of the inner ring and the balls. The outer ring of the anvil bearing 46 contacts the inner circumferential surface of the second cylindrical portion 402.

[0128] In this embodiment, the inner ring portion 611 contacts the rear end surface of the outer ring of the anvil bearing 46. The inner ring portion 611 does not contact the inner ring of the anvil bearing 46.

[0129] The suppression member 62 engages with both the hammer case 4 and the cup washer 61. The suppression member 62 is supported by the hammer case 4. The suppression member 62 is disposed in the groove portion 404. The suppression member 62 prevents the cup washer from slipping out rearward. The suppression member 62 is exemplified by a snap ring or a C-ring. The suppression member 62 is disposed in the groove portion 404 so as to contact the rear surface of the outer ring portion 612. The outer ring portion 612 is supported by the hammer case 4 via the suppression member 62.

[0130] The cup washer 61 and the restraining member 62 prevent the anvil bearing 46 from falling off rearward.

[0131] <Hammer action> Fig. 15 is a schematic diagram showing the relationship between the anvil and the hammer according to a comparative example. Fig. 16 is a schematic diagram showing the relationship between the anvil 10 and the hammer 47 according to this embodiment.

[0132] 16 , as the hammer 47 rotates, the anvil protrusion 102 is struck by the hammer protrusion 475. In this embodiment, the groove 90 is provided in the base portion 471 at a position adjacent to the hammer protrusion 475, which prevents the contact area HS between the hammer protrusion 475 and the anvil protrusion 102 from becoming smaller, while also preventing the impact tool 1 from becoming larger in the axial direction. Furthermore, since the contact area HS between the hammer protrusion 475 and the anvil protrusion 102 is prevented from becoming smaller, excessive force is prevented from being applied to the hammer protrusion 475. This prevents wear on the hammer protrusion 475 and shortens the life of the hammer 47.

[0133] As shown in FIG. 15, if the base portion 471J does not have a groove 90, the contact area HJ between the hammer protrusion 475J and the anvil protrusion 102 will be small. In the example shown in FIG. 15, the front surface 82J of the base portion 471J and the front surface 83J of the hammer protrusion 475J are connected via a flat surface 84AJ and a curved surface 84BJ. The curved surface 84BJ is provided to prevent stress concentration in the hammer protrusion 475J. To ensure that the struck surface 104 of the anvil protrusion 102 is properly struck by the hammer protrusion 475J, it is necessary for the flat surface 84AJ to contact the struck surface 104 and for contact between the curved surface 84BJ and the struck surface 104 to be prevented. Because it is necessary to prevent contact between the curved surface 84BJ and the struck surface 104, the contact area HJ between the flat surface 84AJ and the struck surface 104 will be small. The contact area HJ can be increased by increasing the axial dimensions of the hammer protrusion 475J and the anvil protrusion 102. However, increasing the axial dimensions of the hammer protrusion 475J and the anvil protrusion 102 increases the size of the impact tool in the axial direction. If the impact tool becomes larger, the workability using the impact tool may decrease.

[0134] As shown in FIG. 16 , in this embodiment, a groove 90 is provided in the base portion 471, preventing a reduction in the contact area HS between the hammer protrusion 475 and the anvil protrusion 102 without increasing the axial dimension of the hammer protrusion 475. In this embodiment, the second front surface 82 of the base portion 471 and the front surface 83 of the hammer protrusion 475 are connected via the groove 90. The groove 90 is defined by the first front surface 81, the first flat surface 84A, the first curved surface 84B, the second flat surface 85A, and the second curved surface 85B. The first curved surface 84B prevents stress concentration in the hammer protrusion 475. To ensure that the struck surface 104 of the anvil protrusion 102 is properly struck by the hammer protrusion 475, it is necessary for the first flat surface 84A to contact the struck surface 104 and for contact between the first curved surface 84B and the struck surface 104 to be prevented. The groove 90 expands the first plane 84A rearward, thereby preventing a decrease in the contact area HS between the first plane 84A and the struck surface 104. Therefore, it is possible to prevent the contact area HS between the hammer protrusion 475 and the anvil protrusion 102 from becoming smaller, while also preventing the impact tool 1 from becoming larger in the axial direction.

[0135] 7, 10, and 16, in this embodiment, the distance Wa between the first flat surface 84A and the second flat surface 85A is smaller than the circumferential dimension of the anvil protrusion 102. The distance Wa indicates the width of the groove 90. The cross section of the first curved surface 84B and the cross section of the second curved surface 85B are each arc-shaped. The distance Wa between the first flat surface 84A and the second flat surface 85A is larger than the sum of the radii of the first curved surface 84B and the second curved surface 85B.

[0136] <Operation of impact tool> Next, the operation of the impact tool 1 will be described. For example, when performing a screwdriver operation on a workpiece, a tool bit (driver bit) to be used for the screwdriver operation is inserted into the tool hole 10A of the anvil 10. The tool bit inserted into the tool hole 10A is held by the tool holding mechanism 11. After the tool bit is attached to the anvil 10, the operator grips the grip portion 22 with, for example, the right hand and pulls the trigger lever 14 with the index finger of the right hand. When the trigger lever 14 is pulled, power is supplied from the battery pack 25 to the motor 6, the motor 6 is started, and the light 17 is simultaneously turned on. When the motor 6 is started, the rotor shaft 33 of the rotor 27 rotates. When the rotor shaft 33 rotates, the rotational force of the rotor shaft 33 is transmitted to the planetary gear 42 via the pinion gear 41. The planetary gear 42, meshed with the internal teeth of the internal gear 43, revolves around the pinion gear 41 while rotating on its axis. The planetary gear 42 is rotatably supported by the spindle 8 via a pin 42P. The revolution of the planetary gear 42 causes the spindle 8 to rotate at a rotation speed lower than the rotation speed of the rotor shaft portion 33.

[0137] When the spindle 8 rotates while the hammer protrusion 475 and the anvil protrusion 102 are in contact with each other, the anvil 10 rotates together with the hammer 47 and the spindle 8. As the anvil 10 rotates, the screw tightening operation progresses.

[0138] As the screw tightening operation progresses, if a load greater than a predetermined value acts on the anvil 10, the rotation of the anvil 10 and the hammer 47 stops. When the spindle 8 rotates while the hammer 47 is stopped, the hammer 47 moves rearward. As the hammer 47 moves rearward, contact between the hammer protrusion 475 and the anvil protrusion 102 is released. The hammer 47, which has moved rearward, moves forward while rotating due to the elastic force of the first coil spring 51 and the second coil spring 52. As the hammer 47 moves forward while rotating, the anvil protrusion 102 is struck in the rotational direction by the hammer protrusion 475. As a result, the anvil 10 rotates around the rotation axis AX with high torque. Therefore, the screw is tightened into the workpiece with high torque.

[0139] <Effects> As described above, in this embodiment, the impact tool 1 may include the motor 6, the spindle 8 having the spindle shaft 801 and the flange 802 provided at the rear of the spindle shaft 801 and rotating by the rotational force of the motor 6, the anvil 10 having the anvil shaft 101 disposed forward of the spindle 8 and to which a tool bit is attached, and the anvil protrusion 102 protruding radially outward from the anvil shaft 101, and the hammer 47 having the base 471 disposed around the spindle shaft 801, the front ring 472 protruding forward from the outer periphery of the base 471, and the hammer protrusion 475 protruding radially inward from the inner circumferential surface of the front ring 472 and striking the anvil protrusion 102 in the rotational direction. The front surface 83 of the hammer protrusion 475 may be disposed forward of the front surface of the base 471. The base portion 471 may have a groove 90 provided at the interface with the hammer protrusion portion 475 .

[0140] In the above configuration, the groove 90 is provided in the base portion 471, which prevents the contact area between the hammer protrusion 475 and the anvil protrusion 102 from becoming smaller, while also preventing the impact tool 1 from becoming larger in size in the axial direction parallel to the rotation axis AX of the motor 6. In addition, since the contact area between the hammer protrusion 475 and the anvil protrusion 102 is prevented from becoming smaller, excessive force is prevented from being applied to the hammer protrusion 475. As a result, wear on the hammer protrusion 475 is prevented, and the life of the hammer 47 is prevented from being shortened.

[0141] In this embodiment, the base portion 471 may have a first front surface 81 and a second front surface 82 that is positioned circumferentially different from the first front surface 81 and is positioned forward of the first front surface 81. One circumferential end of the first front surface 81 may be connected to the other circumferential end of the front surface 83 of the hammer protrusion 475 via a first connecting surface 84. One circumferential end of the second front surface 82 may be connected to the other circumferential end of the first front surface 81 via a second connecting surface 85. The first connecting surface 84 may be parallel to the rotation axis AX of the hammer 47 and may include a first flat surface 84A, at least a portion of which faces the struck surface 104 of the anvil protrusion 102, and a first curved surface 84B that connects a rear end of the first flat surface 84A to one circumferential end of the first front surface 81. The groove 90 may be defined by the first front surface 81, the first connecting surface 84, and the second connecting surface 85.

[0142] In the above configuration, the first flat surface 84A and the first front surface 81 are connected via the first curved surface 84B, which prevents stress from concentrating on the boundary between the first flat surface 84A and the first front surface 81. This prevents cracks from occurring in the hammer 47, for example.

[0143] In this embodiment, the outer circumferential surface 472A of the front ring portion 472 may be inclined radially inward toward the front.

[0144] The above configuration prevents the hammer 47 from becoming larger in the radial direction. Since the hammer 47 is prevented from becoming larger in the radial direction, the front part of the hammer case 4 is also prevented from becoming larger in the radial direction.

[0145] In the present embodiment, the front ring portion 472 may be disposed radially outward of the anvil protrusion 102. The position of the front ring portion 472 and the position of at least a portion of the anvil protrusion 102 may be the same in the axial direction.

[0146] In the above configuration, the moment of inertia of the hammer 47 increases when the hammer protrusion 475 strikes the anvil protrusion 102, thereby increasing the striking force.

[0147] In the present embodiment, the second connecting surface 85 may include a second flat surface 85A that is parallel to the rotation axis of the hammer 47 and faces the first flat surface 84A, and a second curved surface 85B that connects a rear end of the second flat surface 85A to the other circumferential end of the first front surface 81. A distance Wa between the first flat surface 84A and the second flat surface 85A may be smaller than a circumferential dimension Wb of the anvil protrusion 102.

[0148] In the above configuration, the second flat surface 85A and the first front surface 81 are connected via the second curved surface 85B, which prevents stress from concentrating at the boundary between the second flat surface 85A and the first front surface 81. This prevents, for example, cracks from occurring in the hammer 47. Furthermore, the distance Wa between the first flat surface 84A and the second flat surface 85A, which indicates the width of the groove 90, is smaller than the circumferential dimension Wb of the anvil protrusion 102, so the anvil protrusion 102 can rotate smoothly without getting caught in the groove 90.

[0149] In this embodiment, the distance Wa between the first flat surface 84A and the second flat surface 85A may be greater than the sum of the radius of the first curved surface 84B and the radius of the second curved surface 85B.

[0150] In the above configuration, first curved surface 84B and second curved surface 85B are formed inside groove 90. For example, if the radius of each of first curved surface 84B and second curved surface 85B is 0.5 mm, the width of the groove may be approximately 4 mm.

[0151] In this embodiment, the bearing may include a coil spring 50 arranged around the spindle shaft portion 801, a washer 53 arranged behind the base portion 471 and supporting a front end of the coil spring 50, and a support ball 54 arranged in a support groove 478 provided in the rear surface of the base portion 471 and supporting a front surface of the washer 53. The position of the support groove 478 and the position of at least a part of the second front surface 82 may be the same in both the radial and circumferential directions.

[0152] In the above configuration, the hammer 47 can be made smaller.

[0153] In this embodiment, the hammer 47 may have a rear ring portion 473 that protrudes rearward from the outer periphery of the base portion 471.

[0154] In the above configuration, the moment of inertia of the hammer 47 increases when the hammer protrusion 475 strikes the anvil protrusion 102, thereby increasing the striking force.

[0155] In this embodiment, the hammer 47 may have a support ring portion 474 that protrudes rearward from the inner periphery of the base portion 471 and is supported by the spindle shaft portion 801 via the hammer ball 48. The washer 53 may be disposed between the rear ring portion 473 and the support ring portion 474 in the radial direction.

[0156] In the above configuration, the front end of the coil spring 50 fits between the rear ring portion 473 and the support ring portion 474, so that the impact tool 1 is prevented from becoming larger in size in the axial direction parallel to the rotation axis AX of the motor 6.

[0157] In this embodiment, the washer 53 may be disposed forward of the rear end of the hammer ball 48 .

[0158] In the above configuration, the impact tool 1 is prevented from becoming larger in size in the axial direction parallel to the rotation axis AX of the motor 6.

[0159] [Second embodiment] A second embodiment will be described below. Components that are the same as or equivalent to those in the above-described embodiment will be given the same reference numerals, and descriptions of those components will be simplified or omitted.

[0160] 17 is a vertical cross-sectional view showing the upper part of the impact tool 1 according to this embodiment. In this embodiment, the anvil bearing 460 that rotatably supports the anvil shaft portion 101 is a plain bearing. The inner ring portion 611 of the cup washer 61 contacts the rear end surface of the anvil bearing 46.

[0161] The anvil bearing 460 is disposed around the anvil shaft portion 101. Two O-rings 45 are disposed between the anvil shaft portion 101 and the anvil bearing 460. The O-rings 45 are disposed radially inward of the anvil bearing 460. The O-rings 45 improve the sealing performance of the boundary between the anvil bearing 460 and the anvil shaft portion 101. The O-rings 45 also suppress vibrations transmitted from the anvil shaft portion 101 to the anvil bearing 460.

[0162] [Other embodiments] In the above-described embodiment, the impact tool 1 is an impact driver. The impact tool 1 may be an impact wrench.

[0163] In the above-described embodiment, the power source for the impact tool 1 does not have to be the battery pack 25, and may be a commercial power source (AC power source). [Explanation of symbols]

[0164] 1...impact tool, 2...housing, 2L...left housing, 2R...right housing, 2S...screw, 4...hammer case, 5A...hammer case cover, 5B...bumper, 5C...housing cover, 6...motor, 7...reduction mechanism, 8...spindle, 8A...hammer sliding surface, 8B...spindle sliding surface, 9...impact mechanism, 10...anvil, 10A...tool hole, 10B...rear end, 11...tool holding mechanism, 12...fan, 12A...bush, 13...battery mounting section, 14...trigger lever, 15...forward / reverse switching lever, 16...operation display section, 16A...operation button, 17...light, 18...control Roller, 19...intake port, 20...exhaust port, 21...motor housing section, 21A...cylindrical section, 21B...rear plate section, 22...grip section, 23...battery holding section, 24...bearing box, 24A...O-ring, 25...battery pack, 26...stator, 27...rotor, 28...stator core, 29...front insulator, 29S...screw, 30...rear insulator, 31...coil, 32...rotor core section, 33...rotor shaft section, 33F...front shaft section, 33R...rear shaft section, 34...rotor magnet, 35...sensor magnet, 37...sensor board, 38...fusing terminal, 39...rotor rotor bearing, 39F...front rotor bearing, 39R...rear rotor bearing, 41...pinion gear, 42...planetary gear, 42P...pin, 43...internal gear, 44...spindle bearing, 45...O-ring, 46...anvil bearing, 47...hammer, 48...hammer ball, 50...coil spring, 51...first coil spring, 52...second coil spring, 53...washer, 54...support ball, 61...cup washer, 62...restraining member, 71...ball, 73...sleeve, 74...coil spring, 76...support recess, 81...first front surface, 8 2...second front surface, 83...front surface, 84...first connecting surface, 84A...first flat surface, 84B...first curved surface, 85...second connecting surface, 85A...second flat surface, 85B...second curved surface, 90...groove, 101...anvil shaft portion, 102...anvil protrusion portion, 103...anvil convex portion, 104...striking surface, 241...recess, 242...convex portion, 401...first cylindrical portion, 402...second cylindrical portion, 403...case connecting portion, 404...groove portion, 460...anvil bearing, 471...base portion, 472...front ring portion, 472A...outer peripheral surface, 473...rear ring portion, 473R...rear end portion, 474...support ring portion, 474R...rear end portion,475...Hammer protrusion portion, 476...Recess portion, 477...Hammer groove, 478...Support groove, 479...Sliding surface, 611...Inner ring portion, 612...Outer ring portion, 613...Connecting ring portion, 801...Spindle shaft portion, 802...Flange portion, 803...Convex portion, 804...Spindle groove, 805...Spindle recess portion, AX...axis of rotation.

Claims

1. A motor, a spindle shaft portion, and a flange portion provided at the rear portion of the spindle shaft portion, and a spindle that rotates by the rotational force of the motor, an anvil that is disposed forward of the spindle, and has an anvil shaft portion to which a tip tool is attached, and an anvil protrusion that protrudes radially outward from the anvil shaft portion, a base portion disposed around the spindle shaft portion, a front ring portion that protrudes forward from the outer peripheral portion of the base portion, and a hammer that protrudes radially inward from the inner peripheral surface of the front ring portion and strikes the anvil protrusion in the rotational direction, and has a hammer protrusion, The front surface of the hammer protrusion is disposed forward of the front surface of the base portion, The base portion has a groove provided at the boundary with the hammer protrusion, An impact tool.

2. The base portion has a first front surface and a second front surface that are disposed at a position different from the first front surface in the circumferential direction and are disposed forward of the first front surface, One circumferential end portion of the first front surface is connected to the other circumferential end portion of the front surface of the hammer protrusion via a first connection surface, One circumferential end portion of the second front surface is connected to the other circumferential end portion of the first front surface via a second connection surface, The first connection surface is parallel to the rotation axis of the hammer and includes a first plane at least a part of which faces the struck surface of the anvil protrusion, and a first curved surface that connects the rear end portion of the first plane and the one circumferential end portion of the first front surface, The groove is defined by the first front surface, the first connection surface, and the second connection surface, The impact tool according to claim 1.

3. The outer peripheral surface of the front ring portion is inclined radially inward toward the front, The impact tool according to claim 1.

4. The front ring portion is disposed radially outside the anvil protrusion, In the axial direction, the position of the front ring portion and at least a part of the position of the anvil protrusion are the same, The impact tool according to claim 1.

5. The second connection surface is parallel to the rotation axis of the hammer and includes a second plane that faces the first plane, and a second curved surface that connects the rear end portion of the second plane and the other circumferential end portion of the first front surface, The distance between the first plane and the second plane is smaller than the circumferential dimension of the anvil protrusion, The impact tool according to claim 2.

6. The distance between the first plane and the second plane is greater than the sum of the radius of the first curved surface and the radius of the second curved surface. The impact tool according to claim 5.

7. A coil spring disposed around the spindle shaft portion; A washer disposed behind the base portion and supporting the front end portion of the coil spring; A support ball disposed in a support groove provided on the rear surface of the base portion and supporting the front surface of the washer, and comprising: In each of the radial direction and the circumferential direction, the position of the support groove and at least a part of the position of the second front surface are the same. The impact tool according to claim 2.

8. The hammer has a rear ring portion protruding rearward from the outer peripheral portion of the base portion. The impact tool according to claim 7.

9. The hammer has a support ring portion protruding rearward from the inner peripheral portion of the base portion and supported by the spindle shaft portion via a hammer ball. In the radial direction, the washer is disposed between the rear ring portion and the support ring portion. The impact tool according to claim 8.

10. The washer is disposed in front of the rear end portion of the hammer ball. The impact tool according to claim 9.

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