Impact tools

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 in this specification relates to impact tools.

Background Art

[0002] In the technical field related to impact tools, impact tools as disclosed in Patent Document 1 are known. 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

Summary of the Invention

Problems to be Solved by the Invention

[0004] For example, in a screw tightening operation using an impact tool, 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 has stopped, the hammer and the spindle slide. When the hammer and the spindle slide, if the hammer tilts with respect to the spindle, the frictional force between the hammer and the spindle increases locally, and as a result, at least one of the hammer and the spindle may be excessively worn or seized. As a result, the life of the impact tool may be shortened.

[0005] The technology disclosed in this specification aims to suppress the tilting of the hammer with respect to the spindle.

Means for Solving the Problems

[0006] This specification discloses an impact tool. The impact tool may comprise a motor, a spindle rotated by the motor and at least part of which is positioned in front of the motor, a hammer positioned around the spindle, an anvil struck in the rotational direction by the hammer and at least part of which is positioned in front of the spindle, and a ball positioned between the spindle and the hammer. There may be at least three balls. [Effects of the Invention]

[0007] The techniques disclosed herein suppress the inclination of the hammer relative to the spindle. [Brief explanation of the drawing]

[0008] [Figure 1] Figure 1 is a front perspective view showing an impact tool according to an embodiment. [Figure 2] Figure 2 is a side view showing the upper part of the impact tool according to the embodiment. [Figure 3] Figure 3 is a longitudinal cross-sectional view showing the upper part of the impact tool according to the embodiment. [Figure 4] Figure 4 is a cross-sectional view showing the upper part of the impact tool according to the embodiment. [Figure 5] Figure 5 is a cross-sectional view showing the upper part of the impact tool according to the embodiment. [Figure 6] Figure 6 is an exploded perspective view showing the main components of an impact tool according to an embodiment. [Figure 7] Figure 7 is a front view showing the spindle and hammer according to the embodiment. [Figure 8] Figure 8 is a top view showing a spindle according to an embodiment. [Figure 9] Figure 9 is a bottom view showing a spindle according to an embodiment. [Modes for carrying out the invention]

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

[0010] In the above configuration, at least three balls are placed between the spindle and the hammer, which suppresses the hammer from tilting relative to the spindle.

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

[0012] In the above configuration, each of 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 the rear end face of the spindle. Lubricating oil may be contained in the internal space. A first supply port for supplying lubricating oil from the internal space may be provided on the outer circumferential surface of the spindle. The first supply port may be provided on the outer circumferential surface of the spindle behind the spindle groove.

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

[0015] In one or more embodiments, the first supply port may be provided in multiple locations in the circumferential direction.

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

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

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

[0019] Hereinafter, embodiments will be described with reference to the drawings. In the embodiments, the terms left, right, front, rear, up, and down are used to describe the positional relationship of each part. These terms indicate the relative position or direction based on the center of the impact tool 1. The impact tool 1 has a motor 6 as a power source.

[0020] In the embodiments, the direction parallel to the rotation axis AX of the motor 6 is appropriately referred to as the axial direction, the direction around the rotation axis AX is appropriately referred to as the circumferential direction or the rotational direction, and the radial direction of the rotation axis AX is appropriately referred to as the radial direction.

[0021] The rotation axis AX extends in the front-rear direction. One side in the axial direction is the front, and the other side in the axial direction is the rear. Also, in the radial direction, a position close to the rotation axis AX or a direction approaching it is appropriately referred to as the inner radial side, and a position far from the rotation axis AX or a direction separating from it is appropriately referred to as the outer radial side.

[0022] [Impact Tool] Figure 1 is a front perspective view showing the impact tool 1 according to the embodiment. Figure 2 is a side view showing the top of the impact tool 1 according to the embodiment. Figure 3 is a longitudinal cross-sectional view showing the top of the impact tool 1 according to the embodiment. Figure 4 is a transverse cross-sectional view showing the top of the impact tool 1 according to the embodiment. Figure 5 is a cross-sectional view showing the top of the impact tool 1 according to the embodiment, and corresponds to the view taken along line AA in Figure 3.

[0023] In this embodiment, the impact tool 1 is an impact driver, which is a type of screw tightening tool. The impact tool 1 comprises 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 switching lever 15, an interface panel 16, a hand-held mode switching button 17, and a light assembly 18.

[0024] Housing 2 is made of synthetic resin. In this embodiment, housing 2 is made of nylon. 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 fastened together by a number of screws 2S. Housing 2 consists of a pair of split housings.

[0025] The housing 2 includes a motor housing section 21, a grip section 22, and a battery holding section 23.

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

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

[0028] The battery holder 23 holds the battery pack 25 via the battery mounting section 13. The battery holder 23 is connected to the lower end of the grip section 22. In both the front-to-back and left-to-right directions, the external dimensions of the battery holder 23 are larger than the external dimensions of the grip section 22.

[0029] The rear cover 3 is positioned to cover the opening at the rear end of the motor housing 21. The rear cover 3 is located behind the motor housing 21. The rear cover 3 houses at least a portion of the fan 12. The fan 12 is located inside the rear cover 3. The rear cover 3 holds the rear rotor bearing 37. The rear cover 3 is made of synthetic resin. The rear cover 3 is secured to the rear end of the motor housing 21 by two screws 3S.

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

[0031] The hammer case 4 houses at least a portion of the reduction mechanism 7, the spindle 8, the striking mechanism 9, and at least a portion of the anvil 10. The hammer case 4 is made of metal. In embodiments, the hammer case 4 is made of aluminum. The hammer case 4 is cylindrical. The hammer case 4 includes a large cylindrical section 4A, a small cylindrical section 4B, and a connecting section 4C. The small cylindrical section 4B is positioned in front of the large cylindrical section 4A. The front end of the large cylindrical section 4A and the rear end of the small cylindrical section 4B are connected via the connecting section 4C. The connecting section 4C is annular. The outer diameter of the large cylindrical section 4A is larger than the outer diameter of the small cylindrical section 4B. The inner diameter of the large cylindrical section 4A is larger than the inner diameter of the small cylindrical section 4B.

[0032] The bearing box 24 houses at least a portion of the reduction 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 positioned 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 threads or by a snap-fit ​​(light fitting). For example, threads may be formed on the outer circumference of the front annular portion 24B, and thread grooves may be formed on the inner circumference of the large cylindrical portion 4A. The bearing box 24 and the hammer case 4 may be fixed by the connection of the threads of the front annular portion 24B and the thread grooves of the large cylindrical portion 4A. The bearing box 24 and the hammer case 4 may be fixed by fitting the front annular portion 24B into the large cylindrical portion 4A. The front rotor bearing 38 is positioned radially inward of the rear annular portion 24A. The spindle bearing 44 is positioned radially inward of the connecting portion 24C.

[0033] The hammer case 4 is sandwiched between the left housing 2L and the right housing 2R. The rear of the hammer case 4 is housed in the motor housing 21. The hammer case 4 is connected to the front of the motor housing 21. The bearing box 24 is fixed to both the motor housing 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 it. The hammer case cover 51 is positioned to cover the outer circumferential 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 it. The bumper 52 mitigates the impact when it comes into contact with an object. The bumper 52 is positioned around the small cylindrical portion 4B.

[0036] Motor 6 is the power source for impact tool 1. Motor 6 is an inner rotor type brushless motor. Motor 6 has a stator 26 and a rotor 27. The stator 26 is supported by a motor housing 21. At least a portion of the rotor 27 is positioned inside the stator 26. The rotor 27 rotates relative to the stator 26. The rotor 27 rotates around a rotation axis AX that extends 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 multiple laminated steel plates. The steel plates are metal plates mainly composed of iron. The stator core 28 is cylindrical. The stator core 28 is positioned radially outward from the rotor 27. The stator core 28 has multiple teeth that support the coil 31.

[0039] The rear insulator 29 and the front insulator 30 are both electrically insulating components made of synthetic resin. Each of the rear insulator 29 and the front insulator 30 electrically insulates 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 positioned to cover a portion of the surface of the teeth. The front insulator 30 is positioned to cover a portion of the surface of the teeth.

[0040] The coil 31 is mounted on the stator core 28 via a rear insulator 29 and a front insulator 30. Multiple 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. Multiple coils 31 are connected via a fusing terminal 36.

[0041] The rotor 27 rotates around the 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 integrated. The rear portion of the rotor shaft 33 protrudes rearward from the rear end face of the rotor core 32. The front portion of the rotor shaft 33 protrudes forward from the front end face of the rotor core 32.

[0043] The rotor magnet 34A is fixed to the rotor core 32. In this embodiment, the rotor magnet 34A is arranged around the rotor core 32. The sensor magnet 34B is fixed to the rotor core 32. In this embodiment, the sensor magnet 34B is arranged on the front end face 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 by 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 rotational position of the rotor 27 by detecting the position of the sensor magnet 34B.

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

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

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

[0048] The reduction gear 7 connects the rotor shaft 33 and the spindle 8. The gears of the reduction gear 7 are driven by the rotor 27. The reduction gear 7 transmits the rotation of the rotor 27 to the spindle 8. The reduction gear 7 rotates the spindle 8 at a rotational speed lower than the rotational speed of the rotor shaft 33. The reduction gear 7 is positioned in front of the stator 26. The reduction gear 7 includes a planetary gear mechanism.

[0049] The reduction gear 7 has a plurality of planetary gears 42 arranged around a pinion gear 41 and an internal gear 43 arranged around the plurality of planetary gears 42. Each of the pinion gear 41, planetary gears 42, and internal gear 43 is housed in a hammer case 4. Each of the plurality of planetary gears 42 meshes with the pinion gear 41. The planetary gears 42 are rotatably supported on a spindle 8 via pins 42P. The spindle 8 is rotated by the planetary gears 42. The internal gear 43 has internal teeth that mesh with the planetary gears 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 immobile relative to the hammer case 4.

[0051] When the rotor shaft 33 rotates due to 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 revolving of the planetary gear 42, the spindle 8 connected to the planetary gear 42 via pin 42P rotates at a lower rotational speed than the rotational speed of the rotor shaft 33.

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

[0053] The spindle 8 is rotated by the motor 6 around the rotation axis AX. The spindle 8 is rotated by the rotor 27. The spindle 8 rotates due to 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 the ball 48 and hammer 47. At least a portion of the spindle 8 is positioned in front of the motor 6. The spindle 8 is positioned in front of the stator 26. At least a portion of the spindle 8 is positioned in front of the rotor 27. At least a portion of the spindle 8 is positioned in front of the reduction mechanism 7. At least a portion of the spindle 8 is positioned behind 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 a rod-shaped structure that is long in the front-rear direction. The central axis of the spindle shaft portion 8A coincides with the rotation axis AX. 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 positioned rearward of the first flange portion 8B. The second flange portion 8C is annular. The connecting portion 8D connects a part of the first flange portion 8B and a part of the second flange portion 8C. The spindle projection 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 positioned 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 positioned inside the cylindrical portion 8E of the spindle 8, which 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 a motor 6. The rotational force of the motor 6 is transmitted to the striking mechanism 9 via a reduction gear 7 and a spindle 8. The striking mechanism 9 strikes the anvil 10 in a rotational direction based on the rotational force of the spindle 8, which is rotated by the motor 6. The striking mechanism 9 includes a hammer 47, a ball 48, a coil spring 49, and a washer 50. The striking mechanism 9, including the hammer 47, ball 48, coil spring 49, and washer 50, is housed in the large cylindrical section 4A of the hammer case 4.

[0057] The hammer 47 is positioned in front of the reduction mechanism 7. The hammer 47 is positioned around the spindle 8. The hammer 47 is positioned around the spindle shaft portion 8A. The hammer 47 is held by the spindle shaft portion 8A. The ball 48 is positioned 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 projection portion 47D. The body portion 47A is arranged 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 arranged radially outward from the inner cylinder portion 47C. A recess 47E is defined by the rear surface of the body portion 47A, the inner circumferential surface of the outer cylinder portion 47B, and the outer circumferential surface of the inner cylinder portion 47C. The recess 47E is provided so as to recess forward from the rear end of the hammer 47. The recess 47E is ring-shaped. The spindle shaft portion 8A is arranged radially inward from the body portion 47A and the inner cylinder portion 47C. The inner cylinder portion 47C has an inner circumferential surface 47S that faces the outer circumferential surface 8S of the spindle shaft portion 8A. The outer circumferential surface 8S and the inner circumferential surface 47S are in contact. However, the outer circumferential surface 8S and the inner circumferential surface 47S may be separated. The hammer projection 47D protrudes forward from the body portion 47A. Two hammer projections 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 gear 7 and the spindle 8. The hammer 47 is rotatable together with the spindle 8, which is rotated by the motor 6, based on the rotational force of the spindle 8. The axis of rotation of the hammer 47, the axis of rotation of the spindle 8, and the axis of rotation AX of the motor 6 coincide. The hammer 47 rotates around the axis of rotation AX.

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

[0061] The coil spring 49 is positioned 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 positioned inside the recess 47E and supported by the 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 positioned 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 positioned. The spindle groove 8G is provided on a part 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 positioned. The hammer groove 47G is provided on a part of the inner circumferential surface 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 are provided on the outer circumferential surface of the spindle shaft portion 8A as the number of balls 48. The same number of hammer grooves 47G are provided on the inner circumferential surfaces of the body portion 47A and the inner cylinder portion 47C as the number of balls 48. In this embodiment, three balls 48 are provided in the circumferential direction. Three spindle grooves 8G are provided on the outer circumferential surface of the spindle shaft portion 8A. Three hammer grooves 47G are provided on the inner circumferential surfaces of the body portion 47A and the inner cylinder 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, each of the three balls 48 will be referred to as the first ball 48, the second ball 48, and the third ball 48. Each of the three spindle grooves 8G will be referred to as the first spindle groove 8G, the second spindle groove 8G, and the third spindle groove 8G. Each of the three hammer grooves 47G will be referred to as the first hammer groove 47G, the second hammer groove 47G, and the third hammer groove 47G.

[0065] The first ball 48 is positioned between the first spindle groove 8G and the first hammer groove 47G. The second ball 48 is positioned between the second spindle groove 8G and the second hammer groove 47G. The third ball 48 is positioned between the third spindle groove 8G and the third hammer groove 47G. The balls 48 can roll inside the spindle groove 8G and inside the hammer groove 47G, respectively. The hammer 47 is movable with the balls 48. The spindle 8 and the hammer 47 can move relative to each other in the axial and rotational directions, respectively, within the range of motion defined by the spindle groove 8G and the hammer groove 47G.

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

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

[0068] The anvil 10 is positioned in front of the motor 6. The anvil 10 is the output section of the impact tool 1, which rotates based on the rotational force of the rotor 27. At least a portion of the anvil 10 is positioned in front of the spindle 8. At least a portion of the anvil 10 is positioned in front of the hammer 47. The anvil 10 is struck in the rotational direction by the hammer 47.

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

[0070] A tool hole 10C is provided on the front end face of the anvil 10. An anvil recess 10D is provided on the rear end face of the anvil 10. The tool hole 10C is formed to extend rearward from the front end face of the anvil shaft portion 10A. A tip tool is inserted into the tool hole 10C. The tip tool is mounted on the anvil 10. The anvil recess 10D is provided to recess forward from the rear end face of the anvil 10. A spindle projection 8F is positioned in the anvil recess 10D.

[0071] The anvil 10 is rotatably supported by an anvil bearing 46. The axis of rotation of the anvil 10 coincides with the axis of rotation of the hammer 47, the axis of rotation of the spindle 8, and the axis of rotation AX of the motor 6. The anvil 10 rotates around axis AX. The anvil bearing 46 is positioned around the anvil shaft portion 10A. An O-ring 45 is positioned between the anvil bearing 46 and the anvil shaft portion 10A. The anvil bearing 46 is positioned inside the small cylindrical portion 4B of the hammer case 4. The anvil bearing 46 is held in the small cylindrical 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 this embodiment, two anvil bearings 46 are positioned in the front-rear direction.

[0072] A washer 56 is positioned in front of the anvil projection 10B. The washer 56 prevents contact between the front surface of the anvil projection 10B and the hammer case 4. A support member 57 is positioned behind the anvil bearing 46. The support member 57 is positioned 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 coming out of the cylindrical portion 4B. The support member 57 is positioned in a groove provided on the inner circumferential surface of the cylindrical portion 4B.

[0073] The hammer projection 47D can contact the anvil projection 10B. When the motor 6 is driven while the hammer projection 47D and the anvil projection 10B are in contact, 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 screw tightening work, if the load acting on the anvil 10 becomes high, a situation may arise where the load of the coil spring 49 alone is insufficient to rotate the anvil 10. When the load of the coil spring 49 alone is insufficient to rotate the anvil 10, the rotation of the anvil 10 and the hammer 47 stops. The spindle 8 and the hammer 47 are relatively movable in the axial and circumferential directions, respectively, via the ball 48. Even if 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 ball 48 moves backward, guided by the spindle groove 8G and the hammer groove 47G, respectively. When the spindle 8 rotates while the rotation of the hammer 47 is stopped, the outer circumferential surface 8S of the spindle 8 and the inner circumferential surface 47S of the hammer 47 slide against each other. The hammer 47 receives force from the ball 48 and moves backward along with the ball 48. That is, the hammer 47 moves backward as the spindle 8 rotates while the rotation of the anvil 10 is stopped. As the hammer 47 moves backward, contact between the hammer projection 47D and the anvil projection 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, which has moved backward, moves forward due to the elastic force of the coil spring 49. When the hammer 47 moves forward, it receives a rotational force from the ball 48. That is, the hammer 47 moves forward while rotating. As the hammer 47 moves forward while rotating, it comes into contact with the anvil projection 10B while rotating. As a result, the anvil projection 10B is struck in the rotational direction by the hammer projection 47D of the hammer 47. The anvil 10 is subjected to both the power of the motor 6 and the inertial force of the hammer 47. Therefore, the anvil 10 can rotate around the rotation axis AX with high torque.

[0076] The tool holding mechanism 11 is positioned around the front of the anvil 10. The tool holding mechanism 11 holds the tip tool inserted into the tool hole 10C of the anvil 10. The tool holding mechanism 11 is detachable from the tip tool.

[0077] The fan 12 is positioned behind the stator 26 of the motor 6. The fan 12 generates an airflow to cool the motor 6. The fan 12 is fixed to at least a portion 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 positioned between the rear rotor bearing 37 and the stator 26. The fan 12 rotates with the rotation of the rotor 27. As the rotor shaft 33 rotates, the fan 12 rotates together with the rotor shaft 33. 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 intake port 19. The air that flows 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 exhaust port 20.

[0078] The battery mounting section 13 is located below the battery holding section 23. The battery mounting section 13 is connected to the battery pack 25. The battery pack 25 is mounted in the battery mounting section 13. The battery pack 25 is detachable from the battery mounting section 13. The battery pack 25 is mounted in 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 pulled forward from the battery mounting section 13. The battery pack 25 includes a secondary battery. In an embodiment, the battery pack 25 includes a rechargeable lithium-ion battery. By being mounted in 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 located on the grip portion 22. The trigger lever 14 is operated by the operator to start the motor 6. By operating the trigger lever 14, the motor 6 is switched between running and stopping.

[0080] The forward / reverse rotation switch lever 15 is located on the upper part of the grip section 22. The forward / reverse rotation switch lever 15 is operated by the operator. When the forward / reverse rotation switch lever 15 is operated, the rotation direction of the motor 6 is switched from one direction to the other. When the rotation direction of the motor 6 is switched, the rotation direction of the spindle 8 is switched.

[0081] The interface panel 16 is provided on the battery holder 23. The interface panel 16 is provided on the upper surface of the battery holder 23, forward of the grip 22. The interface panel 16 has an operation button 16A. There may be one or more operation buttons 16A. In this embodiment, there are multiple operation buttons 16A. The operating mode of the motor 6 is switched when the operator operates the operation buttons 16A.

[0082] The handheld mode switching button 17 is located on the top of the trigger lever 14. The handheld mode switching button 17 is operated by the operator. When the handheld mode switching button 17 is operated, 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 its surroundings with illumination light. The light assembly 18 illuminates the area in front of the anvil 10 with illumination light. The light assembly 18 also illuminates the tip tool attached to the anvil 10 and its surroundings with illumination light. In this embodiment, the light assembly 18 is positioned on the left and right sides of the large cylindrical portion 4A of the hammer case 4.

[0084] The spindle 8 has an internal space 60. An opening is provided on the rear end face of the spindle 8. The internal space 60 is formed inside the spindle 8 so as to extend forward from the opening provided on the rear end face of the spindle 8. Lubricating oil is contained in the internal space 60. The lubricating oil contains grease. The front end of the pinion gear 41 is inserted into the rear end of the internal space 60 through the opening on the rear end face 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 circumferential surface of the spindle shaft portion 8A. The first supply port 81 supplies lubricating oil from the internal space 60 between the spindle 8 and the hammer 47. On the outer circumferential surface of the spindle shaft portion 8A, the first supply port 81 is provided behind the spindle groove 8G. The first supply port 81 supplies lubricating oil between the outer circumferential surface 8S of the spindle shaft portion 8A and the inner circumferential surface 47S of the inner cylinder portion 47C. The first supply port 81 is connected to the internal space 60 via a first flow path 91 formed inside the spindle shaft portion 8A. The first flow path 91 is provided so as to extend radially outward from the internal space 60 to connect the internal space 60 and the first supply port 81. Due to the centrifugal force of the spindle 8, the lubricating oil contained in the internal space 60 flows through the first flow path 91 toward the first supply port 81. The lubricating oil supplied from the internal space 60 to the first supply port 81 via the first flow path 91 is supplied between the outer circumferential surface 8S of the spindle shaft portion 8A and the inner circumferential surface 47S of the inner cylinder portion 47C.

[0087] As described above, when the spindle 8 rotates while the hammer 47 is stopped, the outer circumferential surface 8S of the spindle 8 and the inner circumferential surface 47S of the hammer 47 slide against each other. By supplying lubricating oil between the sliding surfaces, the outer circumferential surface 8S and the inner circumferential surface 47S, wear or seizure of the outer circumferential surface 8S and the inner circumferential surface 47S is suppressed.

[0088] Multiple first supply ports 81 are provided in the circumferential direction. In this 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 positioned 180 degrees apart. In the front-rear direction, the position of one first supply port 81 and the other first supply port 81 are substantially equal.

[0089] Note that the relative angle between one first supply port 81 and the other first supply port 81 in the circumferential direction is just an example. Also, there are not necessarily two first supply ports 81; there 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 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 this embodiment, the second supply port 82 is provided on the spindle protrusion 8F. The second supply port 82 supplies 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 Tools] Next, the operation of the impact tool 1 will be described. For example, when performing a screw tightening operation on a workpiece, the 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 rotation switch lever 15 is operated so that the motor 6 rotates in the forward direction. The tip tool inserted into the tool hole 10C is held by the tool holding mechanism 11. After the tip tool is mounted on the anvil 10, the operator grips the grip portion 22 with their right hand, for example, and pulls the trigger lever 14 with their right index finger. When the trigger lever 14 is pulled, power is supplied from the battery pack 25 to the motor 6, the motor 6 starts up, and the light assembly 18 lights up at the same time. When the motor 6 starts up, 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 rotates on its own axis while revolving around the pinion gear 41, meshing with the internal teeth of the internal gear 43. The planetary gear 42 is rotatably supported on the spindle 8 via a pin 42P. Due to the revolution of the planetary gear 42, the spindle 8 rotates at a lower rotational speed than the rotational speed of the rotor shaft 33.

[0092] When the spindle 8 rotates (forward) while the hammer projection 47D and the anvil projection 10B are in contact, the anvil 10 rotates together with the hammer 47 and spindle 8. The rotation of the anvil 10 drives the screw tightening operation. When the anvil 10 is rotating together with the hammer 47 and spindle 8, the ball 48 is positioned between the central spindle groove 800 and the central hammer groove 470.

[0093] If a load exceeding a predetermined value is applied to the anvil 10 as the screw tightening operation progresses, the rotation of the anvil 10 and the hammer 47 will stop. When the spindle 8 rotates while the rotation of the hammer 47 is stopped, the ball 48 rolls backward between the second spindle groove 802 and the second hammer groove 472. The hammer 47 receives the force from the ball 48 and moves backward along with the ball 48. As the hammer 47 moves backward, the contact between the hammer projection 47D and the anvil projection 10B is released. The hammer 47, having moved backward, moves forward while rotating due to the elastic force of the coil spring 49. As the hammer 47 moves forward while rotating, the anvil 10 is struck in the rotational direction by the hammer 47. As a result, the anvil 10 rotates around the rotation axis AX with high torque. Therefore, the screw is tightened to the workpiece with high torque.

[0094] During the screw removal operation, the forward / reverse switching lever 15 is operated so that the motor 6 rotates in the reverse direction. If a load exceeding a predetermined value is applied to the anvil 10 as the screw removal operation progresses, 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 rolls backward between the first spindle groove 801 and the first hammer groove 471. The hammer 47 receives the force from the ball 48 and moves backward along with the ball 48. As the hammer 47 moves backward, the contact between the hammer projection 47D and the anvil projection 10B is released. The hammer 47, having moved backward, moves forward while rotating due to the elastic force of the coil spring 49. As the hammer 47 moves forward while rotating, the anvil 10 is struck in the rotational direction by the hammer 47. As a result, the anvil 10 rotates around the rotation axis AX with high torque.

[0095] When the spindle 8 rotates while the hammer 47 is stopped, the outer circumferential surface 8S of the spindle 8 and the inner circumferential surface 47S of the hammer 47 slide against each other. In this embodiment, three balls 48 are positioned between the spindle 8 and the hammer 47. Therefore, when the outer circumferential surface 8S of the spindle 8 and the inner circumferential 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 localized increase in the frictional force between the outer circumferential surface 8S of the spindle 8 and the inner circumferential surface 47S of the hammer 47 is suppressed.

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

[0097] In the above configuration, at least three balls 48 are positioned between the spindle 8 and the hammer 47, which suppresses the tilting of the hammer 47 relative to the spindle 8. Therefore, during sliding between the hammer 47 and the spindle 8, a localized increase in frictional force between the hammer 47 and the spindle 8 is suppressed. Consequently, excessive wear or seizure of at least one of the hammer 47 and the spindle 8 is suppressed.

[0098] To suppress the inclination of the hammer 47 relative to the spindle 8, one possible solution is to increase the length of the inner cylinder portion 47C in the front-rear direction to increase the contact area between the outer surface 8S and the inner surface 47S. However, increasing the length of the inner cylinder portion 47C in the front-rear direction would increase the overall length of the impact tool 1, potentially reducing the workability of using the impact tool 1. In this embodiment, at least three balls 48 are arranged circumferentially between the spindle 8 and the hammer 47, so the inclination of the hammer 47 relative to the spindle 8 is suppressed without increasing the length of the inner cylinder portion 47C in the front-rear direction. In other words, according to this embodiment, it is possible to suppress the inclination of the hammer 47 relative to the spindle 8 while suppressing an increase in the overall length of the impact tool 1. 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 this embodiment, the spindle 8 has a spindle groove 8G in which at least some of the balls 48 are arranged. The hammer 47 has a hammer groove 47G in which at least some of the balls 48 are arranged. The spindle grooves 8G are provided at equal intervals in the circumferential direction on the outer surface of the spindle shaft portion 8A, in the same number as the number of balls 48. The hammer grooves 47G are provided at equal intervals in the circumferential direction on a portion of the inner surface of the body portion 47A and inner cylinder portion 47C of the hammer 47, in the same number as the number of balls 48.

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

[0101] In this 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 face of the spindle 8. Lubricating oil is contained in the internal space 60. A first supply port 81 is provided on the outer circumferential surface of the spindle 8 to supply lubricating oil from the internal space 60. The first supply port 81 is provided on the outer circumferential surface of the spindle 8 behind the spindle groove 8G.

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

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

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

[0105] In this embodiment, the impact tool 1 is provided with a second supply port 82 located at the front end of the spindle 8, which supplies lubricating oil from the internal space 60 between the spindle 8 and the anvil 10.

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

[0107] [Other embodiments] In the embodiment described above, three balls 48 are arranged circumferentially between the spindle shaft portion 8A and the hammer 47. Four balls 48 may be arranged circumferentially between the spindle shaft portion 8A and the hammer 47, five balls may be arranged, or any number of six or more balls may be arranged.

[0108] In the above-described embodiment, the first supply port 81 is provided on the outer circumferential surface of the spindle shaft portion 8A behind the spindle groove 8G. The first supply port 81 may be provided in front 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 embodiment, the impact tool 1 is assumed to be an impact driver. The impact tool 1 may also be an impact wrench.

[0110] In the above-described embodiment, the power source for the impact tool 1 does not have to be the battery pack 25, but may also be a commercial power source (AC power source). [Explanation of Symbols]

[0111] 1…Impact tool, 2…Housing, 2L…Left housing, 2R…Right housing, 2S…Screw, 3…Rear cover, 3S…Screw, 4…Hammer case, 4A…Large cylinder section, 4B…Small cylinder section, 4C…Connecting section, 6…Motor, 7…Reduction mechanism, 8…Spindle, 8A…Spindle shaft section, 8B…First flange section, 8C…Second flange section, 8D…Connecting section, 8E…Cylindrical section, 8F…Spindle protrusion, 8G…Spindle groove, 8S…Outer surface, 9…Impact mechanism, 10…Anvil, 10A…Anvil shaft section, 10B…Anvil projection, 10C…Tool Hole, 10D…Anvil recess, 11…Tool holding mechanism, 12…Fan, 12A…Bush, 13…Battery mounting section, 14…Trigger lever, 15…Forward / reverse rotation switch lever, 16…Interface panel, 16A…Operation button, 17…Handheld mode switch button, 18…Light assembly, 19…Air intake, 20…Exhaust port, 21…Motor housing, 22…Grip section, 23…Battery holder, 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 section, 47B…External 47C...Inner cylinder section, 47D...Hammer projection section, 47E...Recess section, 47G...Hammer groove, 47S...Inner circumferential 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 section, 471...First hammer groove section, 472...Second hammer groove section, 800...Central spindle groove section, 801...First spindle groove section, 802...Second spindle groove section, AX...Rotation shaft.

Claims

1. Motor and, A spindle, which is rotated by the motor, has a rod-shaped spindle shaft portion that is long in the front-to-back direction and is positioned at least in front of the motor, A hammer arranged around the spindle shaft portion, An anvil, at least a portion of which is positioned in front of the spindle and which is struck in the rotational direction by the hammer, It comprises three balls positioned between the spindle shaft portion and the hammer, The spindle has a spindle groove provided on a part of the outer circumferential surface of the spindle shaft portion, in which at least a portion of the balls are arranged. The hammer has a hammer groove in which at least a portion of the ball is placed, The spindle grooves are provided at equal intervals in the circumferential direction in the same number as the number of balls. The hammer grooves are provided at equal intervals in the circumferential direction in the same number as the number of balls. Each of the three spindle grooves has a central spindle groove portion, a first spindle groove portion that inclins rearward from the central spindle groove portion toward one side in the circumferential direction, and a second spindle groove portion that inclins rearward from the central spindle groove portion toward the other side in the circumferential direction. Each of the three hammer grooves has a central hammer groove, a first hammer groove extending from the central hammer groove to one side in the circumferential direction, and a second hammer groove extending from the central hammer groove to the other side in the circumferential direction. Impact tools.

2. An internal space is formed inside the spindle, extending forward from an opening provided on the rear end face of the spindle, and containing lubricating oil, The spindle comprises a first supply port provided on its outer circumferential surface for supplying the lubricating oil from the internal space, The impact tool according to claim 1.

3. The first supply port is provided on the outer circumferential surface of the spindle, behind the spindle groove. The impact tool according to claim 2.

4. The first supply port is provided in multiple locations in the circumferential direction. The impact tool according to claim 2.

5. The front end of the spindle is provided with a second supply port for supplying lubricating oil from the internal space to the anvil, The impact tool according to claim 2.

6. Motor and, A spindle, at least a portion of which is positioned in front of the motor and rotated by the motor, A hammer positioned around the spindle, An anvil, at least a portion of which is positioned in front of the spindle and which is struck in the rotational direction by the hammer, The system comprises at least three balls positioned between the spindle and the hammer, The spindle has a spindle shaft portion having a spindle groove in which at least a portion of the balls are arranged, and a spindle projection portion that protrudes forward from the front end of the spindle shaft portion and is arranged in an anvil recess provided on the rear end face of the anvil, The diameter of the spindle shaft portion is between 2 and 4 times the diameter of the spindle protrusion. Impact tools.

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