Impact tool

Abstract

To prevent a hammer from being tilted to a spindle.SOLUTION: An impact tool includes a motor, a spindle having at least a part arranged in front of the motor and rotated by the motor, a hammer arranged around the spindle, an anvil having at least a part arranged in front of the spindle and hit by the hammer in the rotation direction, and at least three balls arranged between the spindle and the hammer.SELECTED DRAWING: Figure 5

Description

[Technical field]

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

[0002] In the technical field related to impact tools, there is known an impact tool as disclosed in Patent Document 1. The impact tool disclosed in Patent Document 1 includes a spindle, a hammer disposed around the spindle, and a ball disposed between the spindle and the hammer. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-037560 Summary of the Invention [Problem to be solved by the invention]

[0004] In screw tightening work using an impact tool, for example, when a load equal to or greater than a predetermined value acts on the anvil, the rotation of the anvil and the hammer stops. When the spindle rotates while the rotation of the hammer is stopped, the hammer and the spindle slide against each other. If the hammer is tilted relative to the spindle when the hammer and the spindle slide against each other, the frictional force between the hammer and the spindle increases locally, which may result in excessive wear or seizure of at least one of the hammer and the spindle. As a result, the life of the impact tool may be shortened.

[0005] The technology disclosed in this specification aims to suppress inclination of the hammer with respect to the spindle. [Means for solving the problem]

[0006] The present specification discloses an impact tool. The impact tool may include a motor, a spindle at least a portion of which is disposed forward of the motor and rotated by the motor, a hammer disposed around the spindle, an anvil at least a portion of which is disposed forward of the spindle and struck in the rotational direction by the hammer, and a ball disposed between the spindle and the hammer. At least three balls may be disposed. Effect of the Invention

[0007] According to the technique disclosed in this specification, tilting of the hammer relative to the spindle is suppressed. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a front perspective view showing an impact tool according to an embodiment. [Diagram 2] FIG. 2 is a side view showing an upper portion of the impact tool according to the embodiment. [Diagram 3] FIG. 3 is a vertical cross-sectional view showing an upper portion of the impact tool according to the embodiment. [Figure 4] FIG. 4 is a cross-sectional view showing an upper portion of the impact tool according to the embodiment. [Diagram 5] FIG. 5 is a cross-sectional view showing an upper portion of the impact tool according to the embodiment. [Figure 6] FIG. 6 is an exploded perspective view showing a main part of the impact tool according to the embodiment. [Figure 7] FIG. 7 is a front view showing the spindle and the hammer according to the embodiment. [Figure 8] FIG. 8 is a top view showing the spindle according to the embodiment. [Figure 9] FIG. 9 is a bottom view showing the spindle according to the embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] In one or more embodiments, the impact tool may include a motor, a spindle at least a portion of which is disposed forward of the motor and rotated by the motor, a hammer disposed around the spindle, an anvil at least a portion of which is disposed forward of the spindle and struck in the rotational direction by the hammer, and a ball disposed between the spindle and the hammer. At least three balls may be disposed.

[0010] In the above configuration, at least three balls are disposed between the spindle and the hammer, so that inclination of the hammer with respect to the spindle is suppressed.

[0011] In one or more embodiments, the spindle may have a spindle groove in which at least a portion of the balls are disposed. The hammer may have a hammer groove in which at least a portion of the balls are disposed. The spindle grooves may be provided at equal intervals in the circumferential direction and in the same number as the number of balls. The hammer grooves may be provided at equal intervals in the circumferential direction and in the same number as the number of balls.

[0012] In the above configuration, each of the at least three balls can roll between the spindle groove and the hammer groove.

[0013] In one or more embodiments, the impact tool may have an internal space formed inside the spindle so as to extend forward from an opening provided on a rear end surface of the spindle. A lubricant may be stored in the internal space. A first supply port may be provided on an outer circumferential surface of the spindle to supply the lubricant from the internal space. The first supply port may be provided on the outer circumferential surface of the spindle rearward of the spindle groove.

[0014] In the above configuration, the lubricating oil in the internal space is supplied between the spindle and the hammer via the first supply port, so that wear between the spindle and the hammer is suppressed.

[0015] In one or more embodiments, a plurality of first supply ports may be provided in the circumferential direction.

[0016] In the above configuration, since a plurality of first supply ports are provided in the circumferential direction, the lubricating oil is evenly supplied between the outer circumferential surface of the spindle and the inner circumferential surface of the hammer.

[0017] In one or more embodiments, the impact tool may include a second supply port disposed at a front end of the spindle for supplying lubricant from the internal space to between the spindle and the anvil.

[0018] In the above configuration, the lubricating oil from the internal space is supplied between the spindle and the anvil via the second supply port, thereby suppressing wear of the spindle and the anvil.

[0019] 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.

[0020] In the embodiment, the direction parallel to the rotation axis AX of the motor 6 is referred to as the axial direction, the direction circumferential 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.

[0021] The rotation axis AX extends in the front-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 is appropriately referred to as the radially inner side, and a position farther from or away from the rotation axis AX is appropriately referred to as the radially outer side.

[0022] [Impact tools] Fig. 1 is a front perspective view showing the impact tool 1 according to the embodiment. Fig. 2 is a side view showing the upper part of the impact tool 1 according to the embodiment. Fig. 3 is a vertical cross-sectional view showing the upper part of the impact tool 1 according to the embodiment. Fig. 4 is a horizontal cross-sectional view showing the upper part of the impact tool 1 according to the embodiment. Fig. 5 is a cross-sectional view showing the upper part of the impact tool 1 according to the embodiment, which corresponds to the cross-sectional view taken along line AA in Fig. 3.

[0023] In the embodiment, the impact tool 1 is an impact driver, which is a type of screw tightening tool. The impact tool 1 includes a housing 2, a rear cover 3, a hammer case 4, a bearing box 24, a hammer case cover 51, a bumper 52, a motor 6, a reduction mechanism 7, a spindle 8, a striking mechanism 9, an anvil 10, a tool holding mechanism 11, a fan 12, a battery mounting section 13, a trigger lever 14, a forward / reverse rotation switching lever 15, an interface panel 16, a hand mode switching button 17, and a light assembly 18.

[0024] 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 disposed to the right of the left housing 2L. The left housing 2L and the right housing 2R are fixed together by a plurality of screws 2S. The housing 2 is composed of a pair of half housings.

[0025] The housing 2 has a motor accommodating portion 21, a grip portion 22, and a battery holding portion 23.

[0026] The motor accommodating portion 21 accommodates the motor 6. The motor accommodating portion 21 accommodates at least a portion of the hammer case 4. The motor accommodating portion 21 is cylindrical.

[0027] The grip portion 22 is held by an operator. The grip portion 22 extends downward from the motor housing portion 21. The trigger lever 14 is provided on an upper portion of the grip portion 22.

[0028] The battery holding portion 23 holds the battery pack 25 via the battery attachment portion 13. The battery holding portion 23 is connected to a lower end portion of the grip portion 22. The outer dimensions of the battery holding portion 23 are larger than the outer dimensions of the grip portion 22 in both the front-rear direction and the left-right direction.

[0029] The rear cover 3 is positioned so as to cover the opening at the rear end of the motor accommodating portion 21. The rear cover 3 is positioned behind the motor accommodating portion 21. The rear cover 3 accommodates at least a portion of the fan 12. The fan 12 is positioned inside the rear cover 3. The rear cover 3 holds a rear rotor bearing 37. The rear cover 3 is made of synthetic resin. The rear cover 3 is fixed to the rear end of the motor accommodating portion 21 with two screws 3S.

[0030] The motor accommodating portion 21 has an air intake port 19. The rear cover 3 has an air exhaust port 20. Air in the external space of the housing 2 flows into the internal space of the housing 2 through the air intake port 19. Air in the internal space of the housing 2 flows out to the external space of the housing 2 through the air exhaust port 20.

[0031] The hammer case 4 accommodates at least a part of the reduction mechanism 7, the spindle 8, the impact mechanism 9, and at least a part of the anvil 10. The hammer case 4 is made of metal. In the embodiment, the hammer case 4 is made of aluminum. The hammer case 4 is cylindrical. The hammer case 4 includes a large cylinder portion 4A, a small cylinder portion 4B, and a connecting portion 4C. The small cylinder portion 4B is disposed forward of the large cylinder portion 4A. The front end portion of the large cylinder portion 4A and the rear end portion of the small cylinder portion 4B are connected via the connecting portion 4C. The connecting portion 4C is annular. The outer diameter of the large cylinder portion 4A is larger than the outer diameter of the small cylinder portion 4B. The inner diameter of the large cylinder portion 4A is larger than the inner diameter of the small cylinder portion 4B.

[0032] The bearing box 24 accommodates at least a part of the reduction gear mechanism 7. The bearing box 24 holds the front rotor bearing 38 and the spindle bearing 44. The bearing box 24 is made of metal. The bearing box 24 is fixed to the rear of the hammer case 4. The bearing box 24 has a rear annular portion 24A and a front annular portion 24B. The front annular portion 24B is disposed forward of the rear annular portion 24A. The front end of the rear annular portion 24A and the rear end of the front annular portion 24B are connected via a connecting portion 24C. The connecting portion 24C is annular. The outer diameter of the rear annular portion 24A is smaller than the outer diameter of the front annular portion 24B. The inner diameter of the rear annular portion 24A is smaller than the inner diameter of the front annular portion 24B. The bearing box 24 and the hammer case 4 may be fixed by a screw portion or by fitting (light fitting). For example, a screw thread may be formed on the outer periphery of the front annular portion 24B, and a screw groove may be formed on the inner periphery of the large cylinder portion 4A. The bearing box 24 and the hammer case 4 may be fixed by coupling the screw thread of the front annular portion 24B with the screw groove of the large cylinder portion 4A. The bearing box 24 and the hammer case 4 may be fixed by fitting the front annular portion 24B into the large cylinder portion 4A. The front rotor bearing 38 is disposed radially inward of the rear annular portion 24A. The spindle bearing 44 is disposed radially inward of the connection portion 24C.

[0033] The hammer case 4 is sandwiched between the left housing 2L and the right housing 2R. A rear portion of the hammer case 4 is housed in the motor housing portion 21. The hammer case 4 is connected to a front portion of the motor housing portion 21. A bearing box 24 is fixed to each of the motor housing portion 21 and the hammer case 4.

[0034] The hammer case cover 51 protects the hammer case 4. The hammer case cover 51 suppresses contact between the hammer case 4 and objects around the hammer case 4. The hammer case cover 51 is disposed so as to cover the outer peripheral surface of the large cylinder portion 4A.

[0035] The bumper 52 protects the hammer case 4. The bumper 52 suppresses contact between the hammer case 4 and objects around the hammer case 4. The bumper 52 reduces impact when the hammer case 4 comes into contact with an object. The bumper 52 is disposed around the small cylinder portion 4B.

[0036] The motor 6 is a power source of 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 accommodating portion 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.

[0037] The stator 26 includes a stator core 28 , a rear insulator 29 , a front insulator 30 , and a coil 31 .

[0038] The stator core 28 includes a plurality of stacked steel plates. The steel plates are made of a metal whose main component is iron. The stator core 28 is cylindrical. The stator core 28 is disposed radially outward of the rotor 27. The stator core 28 has a plurality of teeth that support the coils 31.

[0039] The rear insulator 29 and the front insulator 30 are each an electrical insulating member made of synthetic resin. The rear insulator 29 and the front insulator 30 each electrically insulate the stator core 28 from the coil 31. The rear insulator 29 is fixed to the rear of the stator core 28. The front insulator 30 is fixed to the front of the stator core 28. The rear insulator 29 is arranged so as to cover a portion of the surface of the teeth. The front insulator 30 is arranged so as to cover a portion of the surface of the teeth.

[0040] The coil 31 is attached to the stator core 28 via the rear insulator 29 and the front insulator 30. A plurality of coils 31 are arranged. The coils 31 are arranged around the teeth of the stator core 28 via the rear insulator 29 and the front insulator 30. The coils 31 and the stator core 28 are electrically insulated by the front insulator 30 and the rear insulator 29. The multiple coils 31 are connected via fusing terminals 36.

[0041] The rotor 27 rotates about a rotation axis AX. The rotor 27 includes a rotor core 32, a rotor shaft 33, a rotor magnet 34A, and a sensor magnet 34B.

[0042] The rotor core 32 and the rotor shaft 33 are each made of steel. In this embodiment, the rotor core 32 and the rotor shaft 33 are integral with each other. A rear portion of the rotor shaft 33 protrudes rearward from a rear end surface of the rotor core 32. A front portion of the rotor shaft 33 protrudes forward from a front end surface of the rotor core 32.

[0043] The rotor magnet 34A is fixed to the rotor core 32. In the embodiment, the rotor magnet 34A is disposed around the rotor core 32. The sensor magnet 34B is fixed to the rotor core 32. In the embodiment, the sensor magnet 34B is disposed on the front end surface of the rotor core 32.

[0044] A sensor board 35 is attached to the front insulator 30. The sensor board 35 is fixed to the front insulator 30 with screws 30S. The sensor board 35 has an annular circuit board and a rotation detection element supported by the circuit board. At least a portion of the sensor board 35 faces the front end surface of the sensor magnet 34B. The rotation detection element detects the position of the sensor magnet 34B, thereby detecting the position of the rotor 27 in the rotational direction.

[0045] The rear end of the rotor shaft 33 is rotatably supported by a rear rotor bearing 37. The front end of the rotor shaft 33 is rotatably supported by a front rotor bearing 38. The rear rotor bearing 37 is held by the rear cover 3. The front rotor bearing 38 is held by the bearing box 24.

[0046] The front end of the rotor shaft 33 is disposed in the internal space of the hammer case 4 through an opening provided in the rear annular portion 24 A of the bearing box 24 .

[0047] A pinion gear 41 is fixed to a front end portion of the rotor shaft 33. The pinion gear 41 is connected to at least a part of the reduction mechanism 7. The rotor shaft 33 is connected to the reduction mechanism 7 via the pinion gear 41.

[0048] The reduction mechanism 7 connects the rotor shaft 33 and the spindle 8. A gear of the reduction mechanism 7 is driven by the rotor 27. 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 shaft 33. The reduction mechanism 7 is disposed forward of the stator 26. The reduction mechanism 7 includes a planetary gear mechanism.

[0049] 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 by 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.

[0050] The internal gear 43 is fixed to the large cylindrical portion 4A of the hammer case 4. The internal gear 43 is always non-rotatable relative to the hammer case 4.

[0051] When the rotor shaft 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 33.

[0052] Fig. 6 is an exploded perspective view showing a main part of the impact tool 1 according to the embodiment. Fig. 7 is a front view showing the spindle 8 and the hammer 47 according to the embodiment. Fig. 8 is a top view showing the spindle 8 according to the embodiment. Fig. 9 is a bottom view showing the spindle 8 according to the embodiment.

[0053] The spindle 8 is rotated about the rotation axis AX by the motor 6. The spindle 8 is rotated by the rotor 27. The spindle 8 rotates by the rotational force of the rotor 27 transmitted via the reduction mechanism 7. The spindle 8 transmits the rotational force of the motor 6 to the anvil 10 via a ball 48 and a hammer 47. At least a portion of the spindle 8 is disposed forward 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. At least a portion of the spindle 8 is disposed rearward of the anvil 10.

[0054] The spindle 8 has a spindle shaft portion 8A, a first flange portion 8B, a second flange portion 8C, a connecting portion 8D, and a spindle protrusion portion 8F.

[0055] The spindle shaft portion 8A is rod-shaped and long in the front-rear direction. The central axis of the spindle shaft portion 8A and the rotation axis AX are aligned. The first flange portion 8B extends radially outward from the rear end of the outer circumferential surface of the spindle shaft portion 8A. The second flange portion 8C is disposed rearward of the first flange portion 8B. The second flange portion 8C is annular. The connecting portion 8D connects a portion of the first flange portion 8B and a portion of the second flange portion 8C. The spindle protrusion 8F protrudes forward from the front end of the spindle shaft portion 8A. The front end of the pin 42P is supported by the first flange portion 8B. The rear end of the pin 42P is supported by the second flange portion 8C. The planetary gear 42 is disposed between the first flange portion 8B and the second flange portion 8C. The planetary gear 42 is rotatably supported by the first flange portion 8B and the second flange portion 8C via the pin 42P. The spindle bearing 44 is disposed inside the cylindrical portion 8E of the spindle 8 that protrudes rearward from the rear surface of the second flange portion 8C. The spindle bearing 44 holds the cylindrical portion 8E of the spindle 8. The spindle bearing 44 is held in the bearing box 24.

[0056] The striking mechanism 9 is driven 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. 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 striking mechanism 9 has a hammer 47, a ball 48, a coil spring 49, and a washer 50. The striking mechanism 9 including the hammer 47, the ball 48, the coil spring 49, and the washer 50 is housed in the large cylinder portion 4A of the hammer case 4.

[0057] The hammer 47 is disposed forward of the reduction mechanism 7. The hammer 47 is disposed around the spindle 8. The hammer 47 is disposed around the spindle shaft portion 8A. The hammer 47 is held by the spindle shaft portion 8A. The ball 48 is disposed between the spindle 8 and the hammer 47.

[0058] The hammer 47 has a body portion 47A, an outer cylinder portion 47B, an inner cylinder portion 47C, and a hammer protrusion portion 47D. The body portion 47A is disposed around the spindle shaft portion 8A. The body portion 47A is annular. The outer cylinder portion 47B and the inner cylinder portion 47C each protrude rearward from the body portion 47A. The outer cylinder portion 47B is disposed radially outward from the inner cylinder portion 47C. A recess 47E is defined by the rear surface of the body portion 47A, the inner peripheral surface of the outer cylinder portion 47B, and the outer peripheral surface of the inner cylinder portion 47C. The recess 47E is provided so as to be recessed forward from the rear end portion of the hammer 47. The recess 47E is ring-shaped. The spindle shaft portion 8A is disposed radially inward from the body portion 47A and the inner cylinder portion 47C. The inner cylinder portion 47C has an inner peripheral surface 47S that faces the outer peripheral surface 8S of the spindle shaft portion 8A. The outer peripheral surface 8S and the inner peripheral surface 47S are in contact with each other. The outer peripheral surface 8S and the inner peripheral surface 47S may be spaced apart from each other. The hammer protrusions 47D protrude forward from the body portion 47A. Two hammer protrusions 47D are provided.

[0059] 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.

[0060] The washer 50 is disposed inside the recess 47E. The washer 50 is supported by the hammer 47 via a plurality of balls 54. The balls 54 are disposed forward of the washer 50. The balls 54 are disposed between the rear surface of the body portion 47A and the front surface of the washer 50.

[0061] The coil spring 49 is disposed around the spindle shaft portion 8A. The rear end of the coil spring 49 is supported by the first flange portion 8B. The front end of the coil spring 49 is disposed inside the recess 47E and supported by a washer 50. The coil spring 49 constantly generates an elastic force that moves the hammer 47 forward.

[0062] The ball 48 is made of a metal such as steel. The ball 48 is disposed between the spindle shaft portion 8A and the body portion 47A. The spindle shaft portion 8A has a spindle groove 8G in which at least a portion of the ball 48 is disposed. The spindle groove 8G is provided on a portion of the outer circumferential surface of the spindle shaft portion 8A. The hammer 47 has a hammer groove 47G in which at least a portion of the ball 48 is disposed. The hammer groove 47G is provided on a portion of the inner circumferential surfaces of the body portion 47A and the inner cylinder portion 47C.

[0063] At least three balls 48 are provided in the circumferential direction. The same number of spindle grooves 8G as the number of balls 48 are provided on the outer peripheral surface of the spindle shaft portion 8A. The same number of hammer grooves 47G as the number of balls 48 are provided on the inner peripheral surfaces of the body portion 47A and the inner cylindrical portion 47C. In the embodiment, three balls 48 are provided in the circumferential direction. Three spindle grooves 8G are provided on the outer peripheral surface of the spindle shaft portion 8A. Three hammer grooves 47G are provided on the inner peripheral surfaces of the body portion 47A and the inner cylindrical portion 47C. The three spindle grooves 8G are provided at equal intervals in the circumferential direction. The three hammer grooves 47G are provided at equal intervals in the circumferential direction.

[0064] In the following description, the three balls 48 are referred to as a first ball 48, a second ball 48, and a third ball 48. The three spindle grooves 8G are referred to as a first spindle groove 8G, a second spindle groove 8G, and a third spindle groove 8G. The three hammer grooves 47G are referred to as a first hammer groove 47G, a second hammer groove 47G, and a third hammer groove 47G.

[0065] The first ball 48 is disposed between the first spindle groove 8G and the first hammer groove 47G. The second ball 48 is disposed between the second spindle groove 8G and the second hammer groove 47G. The third ball 48 is disposed between the third spindle groove 8G and the third hammer groove 47G. The ball 48 can roll on the inside of the spindle groove 8G and the inside of the hammer groove 47G. The hammer 47 can move along with the 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 8G and the hammer groove 47G.

[0066] The diameter Da of the spindle shaft portion 8A may be 2 to 4 times the diameter Df of the spindle protrusion 8F [2×Df≦Da≦2×Df], or 2.5 to 3.5 times the diameter Df of the spindle protrusion 8F [2.5×Df≦Da≦3.5×Df]. In the embodiment, the diameter Da of the spindle shaft portion 8A is about 3 times the diameter Df of the spindle protrusion 8F.

[0067] 8 and 9, each of the three spindle grooves 8G has a central spindle groove portion 800, a first spindle groove portion 801 inclined rearward from the central spindle groove portion 800 toward one circumferential side, and a second spindle groove portion 802 inclined rearward from the central spindle groove portion 800 toward the other circumferential side. As shown in Fig. 7, each of the three hammer grooves 47G has a central hammer groove portion 470, a first hammer groove portion 471 extending from the central hammer groove portion 470 toward one circumferential side, and a second hammer groove portion 472 extending from the central hammer groove portion 470 toward the other circumferential side.

[0068] The anvil 10 is disposed forward of the motor 6. The anvil 10 is an output part of the impact tool 1 that rotates based on the rotational force of the rotor 27. At least a portion of the anvil 10 is disposed forward of the spindle 8. At least a portion of the anvil 10 is disposed forward of the hammer 47. The anvil 10 is struck by the hammer 47 in the rotational direction.

[0069] The anvil 10 has an anvil shaft portion 10A and an anvil protrusion portion 10B. The anvil shaft portion 10A is rod-shaped and long in the front-rear direction. The central axis of the anvil shaft portion 10A coincides with the rotation axis AX. The anvil protrusion portion 10B is provided at the rear end portion of the anvil shaft portion 10A. The anvil protrusion portion 10B protrudes radially outward from the rear end portion of the anvil shaft portion 10A. Two anvil protrusion portions 10B are provided.

[0070] A tool hole 10C is provided in the front end surface of the anvil 10. An anvil recess 10D is provided in the rear end surface of the anvil 10. The tool hole 10C is formed to extend rearward from the front end surface of the anvil shaft portion 10A. A tool tip is inserted into the tool hole 10C. The tool tip is attached to the anvil 10. The anvil recess 10D is provided to be recessed forward from the rear end surface of the anvil 10. A spindle protrusion 8F is disposed in the anvil recess 10D.

[0071] 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 aligned. The anvil 10 rotates around the rotation axis AX. The anvil bearing 46 is disposed around the anvil shaft portion 10A. An O-ring 45 is disposed between the anvil bearing 46 and the anvil shaft portion 10A. The anvil bearing 46 is disposed inside the small cylinder portion 4B of the hammer case 4. The anvil bearing 46 is held by the small cylinder portion 4B of the hammer case 4. The hammer case 4 supports the anvil 10 via the anvil bearing 46. The anvil bearing 46 rotatably supports the front portion of the anvil shaft portion 10A. In the embodiment, two anvil bearings 46 are disposed in the front-rear direction.

[0072] A washer 56 is disposed in front of the anvil protrusion 10B. The washer 56 prevents contact between the front surface of the anvil protrusion 10B and the hammer case 4. A support member 57 is disposed behind the anvil bearing 46. The support member 57 is disposed so as to contact the rear surface of the outer ring of the anvil bearing 46. The support member 57 is ring-shaped. The support member 57 prevents the anvil bearing 46 from slipping rearward from the small cylinder portion 4B. The support member 57 is disposed in a groove provided on the inner surface of the small cylinder portion 4B.

[0073] The hammer protrusion 47D can come into contact with the anvil protrusion 10B. When the motor 6 is driven in a state in which the hammer protrusion 47D and the anvil protrusion 10B are in contact with each other, the anvil 10 rotates together with the hammer 47 and the spindle 8.

[0074] The anvil 10 is struck in the rotational direction by the hammer 47. For example, in a screw tightening operation, when the load acting on the anvil 10 becomes high, a situation may occur in which the anvil 10 cannot be rotated by the load of the coil spring 49 alone. When the anvil 10 cannot be rotated by the load of the coil spring 49 alone, 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 direction and the circumferential direction via the ball 48. Even if the rotation of the hammer 47 stops, the rotation of the spindle 8 continues by the power generated by the motor 6. When the spindle 8 rotates while the rotation of the hammer 47 is stopped, the ball 48 moves backward while being guided by each of the spindle groove 8G and the hammer groove 47G. When the spindle 8 rotates while the rotation of the hammer 47 is stopped, the outer peripheral surface 8S of the spindle 8 and the inner peripheral surface 47S of the hammer 47 slide against each other. The hammer 47 receives a force from the ball 48 and moves rearward along with the ball 48. That is, the hammer 47 moves rearward as the spindle 8 rotates while the rotation of the anvil 10 is stopped. As the hammer 47 moves rearward, the contact between the hammer protrusion 47D and the anvil protrusion 10B is released.

[0075] As described above, the coil spring 49 constantly generates an elastic force that moves the hammer 47 forward. The hammer 47 that has moved backward moves forward due to the elastic force of the coil spring 49. When the hammer 47 moves forward, it receives a force in the rotational direction from the ball 48. That is, the hammer 47 moves forward while rotating. When the hammer 47 moves forward while rotating, the hammer 47 comes into contact with the anvil protrusion 10B while rotating. As a result, the anvil protrusion 10B is struck in the rotational direction by the hammer protrusion 47D of the hammer 47. 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.

[0076] The tool holding mechanism 11 is disposed around the front part of the anvil 10. The tool holding mechanism 11 holds a tool bit inserted into a tool hole 10C of the anvil 10. The tool holding mechanism 11 is capable of attaching and detaching the tool bit.

[0077] The fan 12 is disposed behind the stator 26 of the motor 6. The fan 12 generates an airflow for cooling the motor 6. The fan 12 is fixed to at least a part of the rotor 27. The fan 12 is fixed to the rear of the rotor shaft 33 via a bush 12A. The fan 12 is disposed between the rear rotor bearing 37 and the stator 26. The fan 12 rotates with the rotation of the rotor 27. The rotor shaft 33 rotates, and the fan 12 rotates together with the rotor shaft 33. As the fan 12 rotates, air in the external space of the housing 2 flows into the internal space of the housing 2 through the intake port 19. The air that has flowed into the internal space of the housing 2 circulates through the internal space of the housing 2, thereby cooling the motor 6. As the fan 12 rotates, the air that has circulated through the internal space of the housing 2 flows out through the exhaust port 20 into the external space of the housing 2.

[0078] The battery mounting section 13 is disposed at the lower part of the battery holding section 23. The battery mounting section 13 is connected to the battery pack 25. The battery pack 25 is mounted to the battery mounting section 13. The battery pack 25 is detachable from the battery mounting section 13. The battery pack 25 is mounted to the battery mounting section 13 by being inserted into the battery mounting section 13 from the front of the battery holding section 23. The battery pack 25 is removed from the battery mounting section 13 by being removed forward from the battery mounting section 13. The battery pack 25 includes a secondary battery. In the embodiment, the battery pack 25 includes a rechargeable lithium ion battery. By being mounted to the battery mounting section 13, the battery pack 25 can supply power to the impact tool 1. The motor 6 is driven based on the power supplied from the battery pack 25.

[0079] The trigger lever 14 is provided on the grip portion 22. The trigger lever 14 is operated by an operator to start the motor 6. By operating the trigger lever 14, the motor 6 is switched between being driven and being stopped.

[0080] The forward / reverse switching lever 15 is provided on the upper part of the grip portion 22. 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.

[0081] The interface panel 16 is provided on the battery holding portion 23. The interface panel 16 is provided on the upper surface of the battery holding portion 23, further forward than the grip portion 22. The interface panel 16 has an operation button 16A. There may be one or more operation buttons 16A. In the embodiment, a plurality of operation buttons 16A are provided. The operation mode of the motor 6 is switched by an operator operating the operation button 16A.

[0082] The hand mode switching button 17 is provided on the upper part of the trigger lever 14. The hand mode switching button 17 is operated by an operator. By operating the hand mode switching button 17, the control mode of the motor 6 is switched.

[0083] The light assembly 18 emits illumination light. The light assembly 18 illuminates the anvil 10 and the periphery of the anvil 10 with illumination light. The light assembly 18 illuminates the front of the anvil 10 with illumination light. The light assembly 18 also illuminates the tool attachment attached to the anvil 10 and the periphery of the tool with illumination light. In the embodiment, the light assemblies 18 are disposed on the left and right sides of the large cylinder portion 4A of the hammer case 4.

[0084] The spindle 8 has an internal space 60. An opening is provided in the rear end surface of the spindle 8. The internal space 60 is formed inside the spindle 8 so as to extend forward from the opening provided in the rear end surface of the spindle 8. Lubricating oil is stored in the internal space 60. The lubricating oil includes grease. The front end of the pinion gear 41 is inserted into the rear end of the internal space 60 through the opening in the rear end surface of the spindle 8.

[0085] The spindle 8 has a first supply port 81 and a second supply port 82 .

[0086] The first supply port 81 is provided on the outer peripheral surface of the spindle shaft portion 8A. The first supply port 81 supplies the lubricating oil from the internal space 60 between the spindle 8 and the hammer 47. On the outer peripheral surface of the spindle shaft portion 8A, the first supply port 81 is provided rearward of the spindle groove 8G. The first supply port 81 supplies the lubricating oil between the outer peripheral surface 8S of the spindle shaft portion 8A and the inner peripheral surface 47S of the inner cylinder portion 47C. The first supply port 81 is connected to the internal space 60 via a first flow passage 91 formed inside the spindle shaft portion 8A. The first flow passage 91 is provided to extend radially outward from the internal space 60 so as to connect the internal space 60 and the first supply port 81. The lubricating oil contained in the internal space 60 flows through the first flow passage 91 toward the first supply port 81 due to the centrifugal force of the spindle 8. The lubricating oil supplied from the internal space 60 to the first supply port 81 via the first flow passage 91 is supplied between the outer circumferential surface 8S of the spindle shaft portion 8A and the inner circumferential surface 47S of the inner cylindrical portion 47C.

[0087] As described above, when the spindle 8 rotates while the hammer 47 is stopped from rotating, the outer peripheral surface 8S of the spindle 8 slides against the inner peripheral surface 47S of the hammer 47. By supplying lubricant between the outer peripheral surface 8S and the inner peripheral surface 47S, which are the sliding surfaces, wear or seizure of the outer peripheral surface 8S and the inner peripheral surface 47S is suppressed.

[0088] A plurality of first supply ports 81 are provided in the circumferential direction. In the embodiment, two first supply ports 81 are provided. In the circumferential direction, the position of one first supply port 81 is different from the position of the other first supply port 81. In the circumferential direction, one first supply port 81 and the other first supply port 81 are disposed at positions that differ by 180 degrees. In the front-rear direction, the position of one first supply port 81 and the position of the other first supply port 81 are substantially equal.

[0089] The relative angle between one first supply port 81 and the other first supply port 81 in the circumferential direction is an example. The number of first supply ports 81 does not have to be two, and may be one, or any number of three or more.

[0090] The second supply port 82 is provided at the front end of the spindle 8. The second supply port 82 supplies the lubricating oil from the internal space 60 between the spindle 8 and the anvil 10. The front end of the internal space 60 is connected to the second supply port 82. In the embodiment, the second supply port 82 is provided at the spindle protrusion 8F. The second supply port 82 supplies the lubricating oil between the surface of the spindle protrusion 8F and the inner surface of the anvil recess 10D. The lubricating oil supplied from the internal space 60 to the second supply port 82 is supplied between the surface of the spindle protrusion 8F and the inner surface of the anvil recess 10D.

[0091] [Impact tool operation] Next, the operation of the impact tool 1 will be described. For example, when performing a screw tightening operation on a work object, a tip tool (driver bit) used for the screw tightening operation is inserted into the tool hole 10C of the anvil 10. When performing a screw tightening operation, the forward / reverse switching lever 15 is operated so that the motor 6 rotates forward. The tip tool inserted into the tool hole 10C is held by the tool holding mechanism 11. After the tip tool is attached to the anvil 10, the operator holds 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 at the same time, the light assembly 18 is 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 revolves around the pinion gear 41 while rotating, in a state where it meshes with the internal teeth of the internal gear 43. The planetary gear 42 is rotatably supported by the spindle 8 via a pin 42P. Due to the revolution of the planetary gear 42, the spindle 8 rotates at a rotational speed lower than the rotational speed of the rotor shaft 33.

[0092] When the spindle 8 rotates (forward) with the hammer protrusion 47D and the anvil protrusion 10B in contact with each other, the anvil 10 rotates together with the hammer 47 and the spindle 8. The rotation of the anvil 10 progresses the screw tightening operation. When the anvil 10 rotates together with the hammer 47 and the spindle 8, the ball 48 is disposed between the central spindle groove 800 and the central hammer groove 470.

[0093] When a load equal to or greater than a predetermined value acts on the anvil 10 as the screw tightening operation progresses, the rotation of the anvil 10 and the hammer 47 stops. When the spindle 8 rotates while the hammer 47 is stopped rotating, the ball 48 moves backward while rolling between the second spindle groove 802 and the second hammer groove 472. The hammer 47 receives a force from the ball 48 and moves backward along with the ball 48. When the hammer 47 moves backward, the contact between the hammer protrusion 47D and the anvil protrusion 10B is released. The hammer 47 that has moved backward moves forward while rotating due to the elastic force of the coil spring 49. When the hammer 47 moves forward while rotating, the anvil 10 is struck in the rotation direction by the hammer 47. As a result, the anvil 10 rotates around the rotation axis AX with a high torque. Therefore, the screw is tightened to the work object with a high torque.

[0094] In the unscrewing operation, the forward / reverse switching lever 15 is operated so that the motor 6 is rotated in the reverse direction. When a load equal to or greater than a predetermined value acts on the anvil 10 as the unscrewing operation proceeds, the rotation of the anvil 10 and the hammer 47 stops. When the spindle 8 rotates while the rotation of the hammer 47 is stopped, the ball 48 moves backward while rolling between the first spindle groove 801 and the first hammer groove 471. The hammer 47 receives a force from the ball 48 and moves backward along with the ball 48. When the hammer 47 moves backward, the contact between the hammer protrusion 47D and the anvil protrusion 10B is released. The hammer 47 that has moved backward moves forward while rotating due to the elastic force of the coil spring 49. When the hammer 47 moves forward while rotating, the anvil 10 is struck by the hammer 47 in the rotation direction. As a result, the anvil 10 rotates around the rotation axis AX with a high torque.

[0095] When the spindle 8 rotates while the hammer 47 is stopped from rotating, the outer peripheral surface 8S of the spindle 8 and the inner peripheral surface 47S of the hammer 47 slide against each other. In the embodiment, three balls 48 are disposed between the spindle 8 and the hammer 47. Therefore, when the outer peripheral surface 8S of the spindle 8 and the inner peripheral surface 47S of the hammer 47 slide against each other, the inclination of the hammer 47 with respect to the spindle shaft portion 8A is suppressed. Since the inclination of the hammer 47 with respect to the spindle shaft portion 8A is suppressed, a local increase in the friction force between the outer peripheral surface 8S of the spindle 8 and the inner peripheral surface 47S of the hammer 47 is suppressed.

[0096] [effect] As described above, in the embodiment, the impact tool 1 includes the motor 6, the spindle 8 at least a portion of which is disposed forward of the motor 6 and rotated by the motor 6, the hammer 47 disposed around the spindle 8, the anvil 10 at least a portion of which is disposed forward of the spindle 8 and struck in the rotational direction by the hammer 47, and the ball 48 disposed between the spindle 8 and the hammer 47. At least three balls 48 are disposed in the circumferential direction.

[0097] In the above configuration, at least three balls 48 are disposed between the spindle 8 and the hammer 47, so that the inclination of the hammer 47 with respect to the spindle 8 is suppressed. Therefore, a local increase in the frictional force between the hammer 47 and the spindle 8 during sliding between the hammer 47 and the spindle 8 is suppressed. Therefore, excessive wear or seizure of at least one of the hammer 47 and the spindle 8 is suppressed.

[0098] In order to suppress the inclination of the hammer 47 with respect to the spindle 8, it is possible to increase the length of the inner cylindrical portion 47C in the front-rear direction to increase the contact area between the outer peripheral surface 8S and the inner peripheral surface 47S. However, if the length of the inner cylindrical portion 47C in the front-rear direction is increased, the overall length of the impact tool 1 increases, and there is a possibility that the workability of using the impact tool 1 decreases. In the embodiment, at least three balls 48 are arranged in the circumferential direction between the spindle 8 and the hammer 47, so that the inclination of the hammer 47 with respect to the spindle 8 is suppressed without increasing the length of the inner cylindrical portion 47C in the front-rear direction. That is, according to the present embodiment, it is possible to suppress the inclination of the hammer 47 with respect to the spindle 8 while suppressing the overall length of the impact tool 1 from increasing. The overall length of the impact tool 1 refers to the distance (length) between the rear end of the rear cover 3 and the front end of the anvil 10 in the front-rear direction.

[0099] In the embodiment, the spindle 8 has a spindle groove 8G in which at least a portion of the balls 48 are disposed. The hammer 47 has a hammer groove 47G in which at least a portion of the balls 48 are disposed. The spindle grooves 8G are provided at equal intervals in the circumferential direction on the outer circumferential surface of the spindle shaft portion 8A and in the same number as the number of the balls 48. The hammer grooves 47G are provided at equal intervals in the circumferential direction on a portion of the inner circumferential surface of the body portion 47A and the inner cylinder portion 47C of the hammer 47 and in the same number as the number of the balls 48.

[0100] In the above configuration, each of the at least three balls 48 can roll between the spindle groove 8G and the hammer groove 47G.

[0101] In the embodiment, the impact tool 1 has an internal space 60 formed inside the spindle 8 so as to extend forward from an opening provided on the rear end surface of the spindle 8. Lubricating oil is stored in the internal space 60. A first supply port 81 for supplying lubricating oil from the internal space 60 is provided on the outer circumferential surface of the spindle 8. The first supply port 81 is provided on the outer circumferential surface of the spindle 8 rearward of the spindle groove 8G.

[0102] In the above configuration, the lubricating oil in the internal space 60 is supplied between the spindle 8 and the hammer 47 via the first supply port 81, so that wear between the spindle 8 and the hammer 47 is suppressed.

[0103] In the embodiment, a plurality of first supply ports 81 are provided in the circumferential direction.

[0104] In the above configuration, since a plurality of first supply ports 81 are provided in the circumferential direction, the lubricating oil is evenly supplied between the outer circumferential surface of the spindle 8 and the inner circumferential surface of the hammer 47 .

[0105] In the embodiment, the impact tool 1 includes a second supply port 82 provided at the front end of the spindle 8 for supplying lubricating oil from the internal space 60 between the spindle 8 and the anvil 10 .

[0106] In the above configuration, the lubricating oil from the internal space 60 is supplied between the spindle 8 and the anvil 10 via the second supply port 82, so that wear of the spindle 8 and the anvil 10 is suppressed.

[0107] [Other embodiments] In the above-described embodiment, three balls 48 are arranged in the circumferential direction between the spindle shaft portion 8A and the hammer 47. Four balls 48 may be arranged in the circumferential direction between the spindle shaft portion 8A and the hammer 47, or five balls 48 may be arranged, or any number of balls 48 equal to or greater than six.

[0108] In the above-described embodiment, the first supply port 81 is provided rearward of the spindle groove 8G on the outer circumferential surface of the spindle shaft portion 8A. The first supply port 81 may be provided forward of the rear end of the spindle groove 8G. The first supply port 81 may be provided between the rear end and the front end of the spindle groove 8G in the front-rear direction.

[0109] In the above-described embodiment, the impact tool 1 is an impact driver. The impact tool 1 may be an impact wrench.

[0110] In the above-described embodiment, the power source of 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]

[0111] Reference Signs List 1...Impact tool, 2...Housing, 2L...Left housing, 2R...Right housing, 2S...Screw, 3...Rear cover, 3S...Screw, 4...Hammer case, 4A...Large cylinder portion, 4B...Small cylinder portion, 4C...Connection portion, 6...Motor, 7...Reduction mechanism, 8...Spindle, 8A...Spindle shaft portion, 8B...First flange portion, 8C...Second flange portion, 8D...Connection portion, 8E...Cylindrical portion, 8F...Spindle protrusion portion, 8G...Spindle groove, 8S...Outer periphery, 9...Impact mechanism, 10...Anvil, 10A...Anvil shaft portion, 10B...Anvil protrusion portion, 10C...Tool hole, 10D...anvil recess, 11...tool holding mechanism, 12...fan, 12A...bush, 13...battery mounting section, 14...trigger lever, 15...forward / reverse switching lever, 16...interface panel, 16A...operation button, 17...hand mode switching button, 18...light assembly, 19...air intake, 20...exhaust, 21...motor housing, 22...grip, 23...battery holding section, 24...bearing box, 24A...rear annular section, 24B...front annular section, 24C...connection section, 25...battery pack, 26...stator, 27...rotor, 2 8...Stator core, 29...Rear insulator, 30...Front insulator, 30S...Screw, 31...Coil, 32...Rotor core, 33...Rotor shaft, 34A...Rotor magnet, 34B...Sensor magnet, 35...Sensor board, 36...Fusing terminal, 37...Rear rotor bearing, 38...Front rotor bearing, 41...Pinion gear, 42...Planetary gear, 42P...Pin, 43...Internal gear, 44...Spindle bearing, 45...O-ring, 46...Anvil bearing, 47...Hammer, 47A...Body, 47B...Outer Cylinder portion, 47C...inner cylinder portion, 47D...hammer protrusion portion, 47E...recess, 47G...hammer groove, 47S...inner surface, 48...ball, 49...coil spring, 50...washer, 51...hammer case cover, 52...bumper, 54...ball, 56...washer, 57...support member, 60...internal space, 81...first supply port, 82...second supply port, 91...first flow path, 470...central hammer groove portion, 471...first hammer groove portion, 472...second hammer groove portion, 800...central spindle groove portion, 801...first spindle groove portion, 802...second spindle groove portion, AX...rotating shaft.

Claims

1. A motor, A spindle at least partially disposed forward of the motor and rotated by the motor, A hammer disposed around the spindle, An anvil at least partially disposed forward of the spindle and struck in a rotational direction by the hammer, At least three balls disposed between the spindle and the hammer, and comprising: An impact tool.

2. The spindle has a spindle groove in which at least a part of the balls are disposed, The hammer has a hammer groove in which at least a part of the balls are disposed, The spindle grooves are provided at equal intervals in the circumferential direction by the same number as the number of the balls, The hammer grooves are provided at equal intervals in the circumferential direction by the same number as the number of the balls, The impact tool according to claim 1.

3. An internal space formed inside the spindle so as to extend forward from an opening provided at the rear end surface of the spindle and in which lubricating oil is accommodated, A first supply port provided on the outer peripheral surface of the spindle for supplying the lubricating oil from the internal space, and comprising: The impact tool according to claim 2.

4. The first supply port is provided on the outer peripheral surface of the spindle behind the spindle groove, The impact tool according to claim 3.

5. A plurality of the first supply ports are provided in the circumferential direction, The impact tool according to claim 3.

6. A second supply port provided at the front end of the spindle for supplying the lubricating oil from the internal space between the anvil, and comprising: The impact tool according to claim 3.

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