Electric tool

Abstract

The invention provides an electric tool. An electric power tool (1) is provided with a motor (4), an output unit (5), a fan (46), a housing (2), a brush holding member (67), and a non-conductive cover member (105), the housing (2) housing the motor (4) and the output unit (5) and having an air inlet (44) that sucks in external air as the fan (46) rotates and an air outlet (47) that discharges the suctioned air, and the motor (4) is disposed in the middle of an air flow flowing between the air inlet (44) and the air outlet (47); the brush holding member (67) is disposed on the downstream side of the intake port (44) and has a brush (76) and a conductive biasing member (77) that biases the brush (76) toward the commutator (15). The cover member (105) is disposed between the biasing member (77) and the intake port (44), and covers the biasing member (77). Therefore, the insulation distance between the air inlet and the force application component can be ensured, and the motor and the electric brush can be efficiently cooled.

Description

Technical Field

[0001] The invention relates to an electric tool such as a hammer drill. Background Art

[0002] An AC machine having a brushed motor is known in electric power tools such as hammer drills. The brush is held by an annular brush holder through which a rotor passes, and is pressed toward a commutator by a metal urging member such as a spring spring. A fan is provided at the front of the rotor. When the fan rotates as the rotor rotates, an airflow is generated that draws in external air from an air inlet provided in the housing and exhausts air from an air outlet provided in the radial outer side of the fan. The motor and the brushes are cooled by the airflow (for example, Japanese Patent Publication No. 2022-124291). Summary of the invention

[0003] In order to improve the cooling effect of the motor and brushes, it is desirable to set the air inlet close to the brush holder. However, when the force-applying component that applies force to the brush is conductive, the air inlet needs to be located away from the vicinity of the brush holder in order to ensure the insulation distance between the air inlet and the force-applying component. Therefore, there is a concern that cooling cannot be performed efficiently.

[0004] An object of the present invention is to provide an electric tool capable of efficiently cooling a motor and a brush while ensuring an insulation distance between an air inlet and a biasing member.

[0005] One aspect of the present invention is an electric tool including a motor, an output unit, a fan, a housing, a brush holding member, and a cover member, wherein: The motor has a stator and a rotor, wherein the rotor has a commutator and a rotating shaft. The output unit is driven by the motor to operate; The fan is arranged on the rotating shaft; The housing accommodates the motor and the output unit, and the housing has an air inlet and an exhaust port, the air inlet sucks in external air as the fan rotates; the exhaust port discharges the sucked air, and the housing is such that the motor is arranged in the middle of the airflow flowing between the air inlet and the exhaust port; The brush holding member is arranged on the downstream side of the air inlet, and the brush holding member has a brush and a biasing member, wherein the brush abuts against the commutator; the biasing member has conductivity and biases the brush toward the commutator; The cover member has non-conductivity and is attachable to and detachable from the housing. The cover member is disposed between the urging member and the air inlet to cover the urging member.

[0006] According to the present invention, the motor and the brush can be cooled efficiently while ensuring the insulation distance between the air intake port and the urging member. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 This is a three-dimensional view of the hammer drill as viewed from the rear. Figure 2 It is the rear view of the hammer drill. Figure 3 yes Figure 2 AA section view. Figure 4 yes Figure 2 Partial cross-sectional view of BB. Figure 5 It is a partially enlarged rear view of the hammer drill in the forward rotation position with the rear housing omitted. Figure 6 It is a perspective view of the hammer drill with the rear housing omitted. Figure 7 This is an exploded perspective view of the forward / reverse switching unit and the wire holder. Figure 8 yes Figure 2 A partial enlarged cross-sectional view of CC. Fig. 9 It is a partially enlarged rear view of the hammer drill in the reverse position with the rear housing omitted. Fig.10 is the inverted equivalent of Figure 2 A partial enlarged cross-sectional view of CC. [Explanation of Reference Numerals] 1: hammer drill; 2: front housing; 3: rear housing; 4: motor; 5: output unit; 6: switch; 7: anti-vibration mechanism; 8: motor housing; 9: outer housing; 10: inner housing; 11: connection unit; 12: motor housing; 13: stator; 14: rotor; 16: rotating shaft; 17: front cylinder; 18: rear cylinder; 20: tool holder; 40: outer cylinder; 41: handle; 44: rear air inlet; 45: upper air inlet; 46: Fan; 47: exhaust port; 50: rubber sleeve; 51: coil spring; 60: bearing retaining portion; 61: arm portion; 65: forward and reverse switching unit; 66: unit base; 67: brush base; 75: brush holder; 76: carbon brush; 77: spring spring; 81-83: wire; 85: wire holder; 86: annular portion; 87: support plate portion; 89: fitting piece; 89a: air permeable portion; 105: cover portion; B: tool head; R: airflow. DETAILED DESCRIPTION

[0008] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. Figure 1This is a perspective view of a hammer drill as an example of an electric tool as seen from the rear. Figure 2 It is the rear view of the hammer drill. Figure 3 It is the AA section view. The hammer drill 1 includes a front housing (first housing) 2 and a rear housing (second housing) 3 as housings. The front housing 2 is provided with a motor 4 and an output unit 5. The rear housing 3 is provided with a switch 6. The front case 2 and the rear case 3 are relatively movable in the front-rear direction. An anti-vibration mechanism 7 described later is provided between the front case 2 and the rear case 3 .

[0009] The front housing 2 has a motor housing 8, an outer housing 9, and an inner housing 10. The motor housing 8 is made of resin. The motor housing 8 has a connecting portion 11 on the front side and a motor housing portion 12 on the rear side. The connecting portion 11 is in the shape of a square cylinder and is fixed to the outer housing 9 by screws. The motor housing portion 12 is in the shape of a cylinder having a smaller diameter than the connecting portion 11. The motor housing portion 12 houses the motor 4 inside.

[0010] The motor 4 has a stator 13 and a rotor 14. The rotor 14 has a commutator 15 and a rotating shaft 16. The motor 4 is housed in the motor housing 12 with the rotating shaft 16 facing the front-rear direction. The rotating shaft 16 penetrates the connecting portion 11 and protrudes into the inner housing 10.

[0011] The outer shell 9 is made of resin and has a front cylinder 17 and a rear cylinder 18. The front cylinder 17 is a cylinder extending forward and having a circular cross section. The rear cylinder 18 is a cylinder with a larger diameter than the front cylinder 17. The connecting portion 11 of the motor housing 8 is connected to the rear cylinder 18. The front cylinder 17 is arranged at an eccentric position on the upper side of the rear cylinder 18. A side handle 19 can be installed on the front cylinder 17.

[0012] The output portion 5 has a tool holder (final output shaft) 20, a piston cylinder 21, a hammer 22 and a striker 23. The tool holder 20 is cylindrical and is coaxially accommodated in the front cylinder 17. The tool holder 20 is rotatably held by the front cylinder 17 and the inner housing 10. The front end of the tool holder 20 protrudes forward from the front cylinder 17. An operating sleeve 24 is provided at the front end of the tool holder 20. The operating sleeve 24 can be detached and operated by the tool head (top tool) B at the front end of the tool holder 20. A gear 25 is installed outside the tool holder 20 in the rear cylinder 18.

[0013] The front end of the piston cylinder 21 has an opening. The piston cylinder 21 is accommodated in the rear part of the tool holder 20 in a manner that it can move forward and backward. The hammer 22 is accommodated in the piston cylinder 21 in a manner that it can move forward and backward through the air chamber 26. The striker 23 is accommodated in the tool holder 20 in front of the hammer 22 in a manner that it can move forward and backward.

[0014] In the output part 5, an intermediate shaft 27 is rotatably provided below the tool holder 20. The intermediate shaft 27 is parallel to the tool holder 20. The front end of the rotating shaft 16 of the motor 4 has a pinion 28. The pinion 28 protrudes to the upper side of the intermediate shaft 27. The intermediate shaft 27 has a first gear 29 at the rear portion thereof, which is rotatable together with the intermediate shaft 27. The first gear 29 meshes with a pinion 28. The intermediate shaft 27 has a second gear 30 at the front portion thereof, which is rotatable and is provided separately from the intermediate shaft 27. The second gear 30 meshes with the gear 25 of the tool holder 20. In front of the first gear 29, a boss sleeve 31 is externally mounted on the intermediate shaft 27 in a manner that is rotatable and is provided separately from the intermediate shaft 27. A swing arm 33 is held upward on the boss sleeve 31 via a swash bearing 32 whose axis is tilted. The top end of the swing arm 33 is connected to the rear end of the piston cylinder 21.

[0015] A first clutch 34 and a second clutch 35 are spline-coupled between the boss sleeve 31 and the second gear 30. The first clutch 34 engages with the boss sleeve 31 in the retracted position. Thus, the rotation of the intermediate shaft 27 is transmitted to the boss sleeve 31 via the first clutch 34. When the first clutch 34 advances and is separated from the boss sleeve 31, the rotation of the intermediate shaft 27 is no longer transmitted to the boss sleeve 31. The second clutch 35 is engaged with the second gear 30 in the forward position. Thus, the rotation of the intermediate shaft 27 is transmitted to the second gear 30 via the second clutch 35, and is transmitted to the gear 25 and the tool holder 20. When the second clutch 35 is retracted and separated from the second gear 30, the rotation of the intermediate shaft 27 is no longer transmitted to the second gear 30 and the tool holder 20.

[0016] Two plates 36 are provided below the intermediate shaft 27 so as to be movable forward and backward. The two plates 36 are engaged with the first clutch 34 and the second clutch 35. The position of each plate 36 can be changed by a switching knob 37. The switching knob 37 is provided on the lower surface of the rear cylinder 18 so as to be rotatable. The switching knob 37 has an eccentric pin 38 protruding upward. The eccentric pin 38 is engaged with each plate 36. A locking plate 39 that can be engaged with or separated from the second gear 30 is engaged with the switching knob 37. Thus, by rotating the switching knob 37, the front and rear positions of the plates 36 are switched via the eccentric pin 38. That is, by switching the front and rear positions of the first clutch 34 and the second clutch 35, the electric drill mode, the hammer drill mode, the neutral mode, and the hammer mode can be selected. Each operation mode will be described later.

[0017] The rear housing 3 is made of resin and is composed of a pair of split housings 3a and 3b on the left and right. The split housings 3a and 3b are assembled by a plurality of screws screwed in from the right side. The rear housing 3 has an outer cylinder portion 40 on the front side. The outer cylinder portion 40 covers the motor housing portion 12 from the rear. The front end of the outer cylinder portion 40 has the same shape as the connecting portion 11 of the motor housing 8. At the rear of the outer cylinder portion 40, a handle portion 41 extending downward is integrally formed. The switch 6 is accommodated in the upper portion of the handle portion 41. The switch 6 causes the trigger 42 to protrude forward. The switch 6 is connected to a power cord 43 . The power cord 43 is led out from the lower end of the handle portion 41 .

[0018] A plurality of rear air inlets (air inlets) 44 are formed on both sides of the rear surface of the outer cylinder 40. A plurality of upper air inlets (second air inlets) 45 are formed on the rear upper surface of the outer cylinder 40. A fan 46 as a centrifugal fan is mounted on the rotating shaft 16 in the connecting portion 11. A plurality of exhaust ports 47 are formed on the lower surface and the right side surface of the connecting portion 11.

[0019] The vibration-proof mechanism 7 includes a rubber bush 50 and a coil spring 51 . The rubber sleeve 50 is interposed between the connection portion 11 of the motor housing 8 and the outer tube portion 40 of the rear housing 3. The rubber sleeve 50 is a square tube in the shape of a bellows. The front end of the rubber sleeve 50 engages with the rear end face of the connection portion 11. The rear end of the rubber sleeve 50 engages with the front end face of the outer tube portion 40.

[0020] The rubber bush 50 covers the entire circumference and seals the space between the front housing 2 and the rear housing 3. The rubber bush 50 expands and contracts in the axial direction as the front housing 2 and the rear housing 3 move relative to each other in the front and rear directions. The coil spring 51 is interposed between the motor housing portion 12 and the outer tube portion 40 inside the rear housing 3. One coil spring 51 is arranged on the upper side of the motor housing portion 12. Two coil springs 51 are arranged on the left and right sides of the lower side of the motor housing portion 12. A front receiving plate 52 extending in the left-right direction is erected on the upper surface of the motor housing portion 12. A rear receiving plate 53 extending in the left-right direction is provided on the inner surface of the outer tube portion 40 behind the front receiving plate 52. The upper coil spring 51 is arranged in the front-to-back direction between the front receiving plate 52 and the rear receiving plate 53.

[0021] A pair of left and right front spring receiving portions 54 ( Figure 5 A pair of left and right rear spring receiving portions 55 are formed on the inner surface of the outer tube portion 40 behind each front spring receiving portion 54. The two coil springs 51 on the lower side are arranged between the front spring receiving portion 54 and the rear spring receiving portion 55 in the front-rear direction. Accordingly, the front housing 2 and the rear housing 3 are urged in the direction of separation from each other through the rubber sleeve 50 and the three coil springs 51. However, when the rear housing 3 is in the retreated position away from the front housing 2, Figure 3 As shown, the upper limit portion 56 and the threaded boss 57 are in contact with each other. The upper limit portion 56 protrudes forward from the front receiving plate 52. The threaded boss 57 protrudes to the right from the left split shell 3a. In addition, on the lower side of the motor housing portion 12, the rear ribs 58 in the left and right directions are in contact with the front ribs 59 in the left and right directions. The rear ribs 58 protrude downward from the motor housing portion 12. The front ribs 59 protrude upward from the inner surface of the outer tube portion 40 in front of the rear ribs 58. Accordingly, the rear shell 3 is normally pressed against the upper limit portion 56 and the threaded boss 57, and the rear ribs 58 and the front ribs 59 are in contact with each other. Figure 3 Apply force to the retreat position.

[0022] Also like Figures 4 to 7 As shown, a bearing retaining portion 60 is provided on the rear side of the motor housing portion 12. The diameter of the bearing retaining portion 60 is smaller than that of the motor housing portion 12. The bearing retaining portion 60 is in the shape of an end cap and has an opening in the front. The bearing retaining portion 60 is coaxially connected to the rear surface of the motor housing portion 12 through upper and lower arms 61. The arm portion 61 extends in the front-to-back direction. The bearing retaining portion 60 retains a bearing 62 on the inner surface of the rear side and supports the rear end of the rotating shaft 16. The arm portion 61 is in the shape of a concentric arc centered on the axis of the rotating shaft 16. The commutator 15 of the rotor 14 is exposed on the left and right between the two arms 61. A pair of step portions 63 are formed at the rear end of each arm portion 61. Each step portion 63 is recessed toward the front side than the rear surface of the bearing retaining portion 60.

[0023] A forward / reverse switching unit 65 is assembled on the rear surface of the motor housing portion 12. The forward / reverse switching unit 65 includes a unit base 66 and a brush base 67. The unit base 66 is disc-shaped. The left and right sides of the unit base 66 are coaxially fastened to the motor housing portion 12 by screws from the rear. Figure 7 and Figure 8 As shown, the unit base 66 has a pair of fixed contacts 68. The fixed contacts 68 are arc-shaped when viewed from behind. The pair of fixed contacts 68 are arranged at point-symmetrical positions with the axis of the unit base 66 as the center.

[0024] Four terminal holding portions 70 ( Figure 8 ). The four terminal holding portions 70 are located at the vertices of the quadrilateral when viewed from behind. A terminal terminal 71 is provided on each terminal holding portion 70. Figure 5 , 6, 7, and 10, four connection terminals 72 are provided. The four connection terminals 72 are electrically connected to the four terminal terminals 71. A pair of connection terminals 72 located at the upper left and lower right diagonal positions in a rear view among the four connection terminals 72 are formed integrally with the fixed contact 68. The pair of connection terminals 72 located at the lower left and upper right on the other diagonal line are respectively connected to the wires 81 and 82 described later.

[0025] The brush base (brush holding member) 67 is assembled to the rear surface of the unit base 66 in a coaxially rotatable manner. The brush base 67 is in the shape of a short cylinder. The brush base 67 has a pair of brush holders 75 at point-symmetrical positions in the diameter direction. Each brush holder 75 accommodates a carbon brush (brush) 76. The carbon brush 76 is urged toward the axial center side of the brush base 67 by a spring spring (urging member) 77 provided in the brush holder 75. Accordingly, the commutator 15 is pressed from between the two arm portions 61.

[0026] A pair of movable contacts 78 are provided on the brush base 67. Figure 7 As shown, the movable contact 78 is integrally held by the brush base 67 via a pair of holding blocks 73 mounted on the brush base 67. Thus, the movable contact 78 is electrically connected to the carbon brush 76. The movable contact 78 is located on a concentric circle of the fixed contact 68 of the unit base 66. The movable contact 78 can contact or separate from the fixed contact 68 as the brush base 67 rotates. An operation protrusion 79 is provided on the circumferential surface of the upper side of the brush base 67. The operation protrusion 79 protrudes radially outward from the outer circumferential surface of the brush base 67. Figure 1 As shown, the operation protrusion 79 penetrates a window 80 provided on the upper surface of the rear housing 3 and is exposed upward.

[0027] The forward / reverse switching unit 65 can rotate the brush base 67 from the outside via the operating protrusion 79. By rotating the brush base 67, the movable contact 78 is brought into contact with or separated from the fixed contact 68, thereby switching the direction of current flow. Accordingly, the rotation direction of the rotor 14 is switched. That is, the brush base 67 can be switched between the forward rotation position, the reverse rotation position, and the neutral position. In the forward rotation position, the movable contact 78 contacts the fixed contact 68 in the forward rotation direction. In the reverse rotation position, the movable contact 78 contacts the fixed contact 68 in the reverse rotation direction. In the neutral position, the movable contact 78 is in the middle of the forward rotation position and the reverse rotation position and does not contact the fixed contact 68. Figure 1 to Figure 6 The normal position indicates that the operation protrusion 79 is located at the left end of the window 80. When the operation protrusion 79 is tilted toward the right end of the window 80, it becomes the reverse position. When the operation protrusion 79 is operated toward the center of the window 80 in the left-right direction, it becomes the neutral position.

[0028] like Figure 5 , Figure 6 As shown, the stator 13 and the switch 6 are electrically connected via three wires (wiring) 81, 82, and 83. The wires 81 and 82 are connected to the other pair of connection terminals 72 that do not have the fixed contact 68, and are led out from the unit base 66. The wire 83 is connected to the connection terminal ( Figure 5 The upper left connection terminal 72 is led out from the motor housing portion 12. The respective lead wires 81 to 83 are held on the rear side of the motor housing portion 12 via a lead wire holder 85 assembled to the bearing holding portion 60.

[0029] The wire holder (wiring holding member) 85 is made of resin. Figure 7 As shown, the wire holder 85 has an annular portion 86 and a support plate portion 87 .

[0030] The annular portion 86 is in the shape of an annulus having an inner diameter larger than that of the bearing holding portion 60. A pair of engaging pieces 88 are formed at the upper and lower inner peripheries of the annular portion 86. The pair of engaging pieces 88 are respectively engaged with the upper and lower step portions 63 of the arm portion 61. A pair of interlocking pieces 89 are formed at the left and right sides of the annular portion 86. The pair of interlocking pieces 89 are interlocked with the bearing holding portion 60. The interlocking pieces 89 are in the shape of an arc plate that expands radially outward as the front end interlocked with the bearing holding portion 60 moves toward the rear. At the front end of each interlocking piece 89, a hook portion 90 protruding inwardly is formed covering the entire length. However, a ventilating portion 89a is provided at the circumferential center of each interlocking piece 89. The ventilating portion 89a is formed by forming a notch from the front end of the interlocking piece 89 to near the rear end.

[0031] like Figure 4 , Figure 8 As shown, the hook portion 90 is locked to the front end of the bearing holding portion 60 from the front. This restricts the annular portion 86 from moving backward. A pair of clamping claws 91 are formed on the front surface of the annular portion 86 below the fitting piece 89. Each clamping claw 91 protrudes backward. On the upper surface of the annular portion 86, a first retaining portion 92 and a second retaining portion 93 are arranged side by side. The first retaining portion 92 is a plate-shaped portion extending in the front-rear direction and protruding upward. A first locking piece 94 is formed integrally with the upper end of the first retaining portion 92 in a horizontal direction. The first locking piece 94 is L-shaped when viewed from above and protrudes to the left. The second holding portion 93 is arranged on the right side of the first holding portion 92. The second holding portion 93 is a plate-shaped portion extending in the front-rear direction and protruding upward. At the front end of the second holding portion 93, a second locking piece 95 is integrally formed toward the front. The second locking piece 95 is in an inverted U shape when viewed from the side, and is a notch with a central portion in the up-down direction opening forward.

[0032] The support plate portion 87 includes a longitudinal plate 96 and a transverse plate 97. The longitudinal plate 96 is erected upward from the upper rear end of the annular portion 86 in front of the first holding portion 92 and the second holding portion 93. The transverse plate 97 extends forward from the upper end of the longitudinal plate 96. A first opening 98 is formed on the longitudinal plate 96 in front of the first holding portion 92. The first opening 98 is quadrilateral when viewed from behind. A second opening 99 is formed on the longitudinal plate 96 in front of the second holding portion 93. The second opening 99 is in an inverted L shape when viewed from behind.

[0033] A pair of locking grooves 100 are formed on both left and right sides of the vertical plate 96. The locking grooves 100 are cut in an upwardly inclined shape from the side edges of the vertical plate 96 toward the left and right center sides, and then cut in a straight upward direction. A flange 101 is formed in the center of the horizontal plate 97 in the left-right direction. The flange 101 protrudes rearward. The flange 101 is located above the first holding portion 92 and the second holding portion 93 without contact. A notch 102 is formed in the center of the left-right direction at the front of the horizontal plate 97. The notch 102 is open to the front.

[0034] The assembly of the wire holder 85 is described. The position of the engaging piece 88 is aligned with the step portion 63, and the annular portion 86 is engaged with the bearing holding portion 60 from the rear. Then, the bearing holding portion 60 is engaged between the pair of engaging pieces 89, and the hook portion 90 is engaged with the front end of the bearing holding portion 60 to prevent it from being disengaged to the rear. At this time, the horizontal plate 97 is located above the brush base 67. A protrusion 103 is formed on the upper surface of the motor housing portion 12. The protrusion 103 protrudes rearward. In the assembled state of the wire holder 85, the protrusion 103 is fitted into the front part of the notch 102 of the horizontal plate 97, blocking the front of the notch 102. The operating protrusion 79 penetrates the notch 102 at the rear of the protrusion 103 and protrudes upward.

[0035] like Figure 5 , Figure 6 As shown in the figure, the starting end 81a of the wire 81 shown by the single-dot chain line is led out from the unit base 66 to the rear outside the brush base 67. After that, the wire 81 is clamped by the clamping claw 91 of the wire holder 85. The wire 81 clamped by the clamping claw 91 extends upward behind the bearing holding part 60 with slack, and the middle part 81b is locked by the first locking piece 94 from the bottom. The middle part 81b locked by the first locking piece 94 is led out to the right side from the first holding part 92 and is locked by the second locking piece 95 from the left side. The vertical plate 96 is located in front of the first locking piece 94 and the second locking piece 95. The wire 81 can be locked without any obstacles through the first opening 98 and the second opening 99. After winding back, the middle part 81b is restricted from moving forward by the vertical plate 96.

[0036] The lead wire 81 led out to the right from the second locking piece 95 is wound back downward behind the bearing holding portion 60. And the terminal portion 81c is connected to the switch 6. That is, the lead wire 81 is led out from a position below the axis of the motor housing portion 12, and the intermediate portion 81b is held in the left-right direction by the lead holder 85 at a position above the axis. Thereafter, the lead wire 81 is wound back again to a position below the axis and connected to the switch 6.

[0037] The starting end 82a of the wire 82 shown by the double-dashed line is led out from the unit base 66 to the rear outside the brush base 67. After that, the wire 82 is clamped in the clamping groove 100 on the right side of the longitudinal plate 96 from the front. After the wire 82 clamped in the clamping groove 100 is led out to the rear, the middle part 82b is wound back to the left side with some slack. In addition, the middle part 82b is clamped in the second clamping piece 95 from the right side and is led out to the left side of the second clamping piece 95. The middle part 82b can be clamped without any obstacle through the second opening 99. Accordingly, the middle part 82b is restricted from moving forward by the longitudinal plate 96.

[0038] The lead wire 82 led out from the second locking piece 95 is wound back downward behind the bearing holding portion 60. And the terminal portion 82c is connected to the switch 6. That is, the middle portion 82b of the lead wire 82 is held in the left-right direction by the lead holder 85 at a position above the axis of the motor housing portion 12. Thereafter, the lead wire 82 is wound back to a position below the axis and connected to the switch 6.

[0039] The starting end 83a of the wire 83 shown by the three-dot chain line is led out from the motor housing portion 12 to the rear outside the unit base 66. After that, the wire 83 is clamped in the clamping groove 100 on the left side of the longitudinal plate 96 from the front. After the wire 83 clamped in the clamping groove 100 is led out to the rear, the middle portion 83b is wound back to the right side in a loose state. In addition, the middle portion 83b is clamped in the second clamping piece 95 from the left side and is led out to the right side of the second clamping piece 95. The middle portion 83b can be clamped without obstacles through the second opening portion 99. Accordingly, the middle portion 83b is restricted from moving forward by the longitudinal plate 96.

[0040] The lead wire 83 led out to the right from the second locking piece 95 is wound back downward behind the bearing holding portion 60. And the terminal portion 83c is connected to the switch 6. That is, the middle portion 83b of the lead wire 83 is held in the left-right direction by the lead holder 85 at a position above the axis of the motor housing portion 12. Thereafter, the lead wire 83 is wound back to a position below the axis and connected to the switch 6.

[0041] A cover portion (cover member) 105 is formed on each fitting piece 89 of the annular portion 86. Each cover portion 105 has a circular arc plate-shaped cross section. Each cover portion 105 is continuously formed from the rear end of the fitting piece 89 with a slightly smaller width in the circumferential direction and extends forward as it approaches the radial outer side. According to this, if Figure 5 , Figure 6 and Figure 8 As shown, each cover portion 105 covers each spiral spring 77 from the rear and radially outward. At this time, each cover portion 105 is located between the left and right rear air inlet 44 and the spring spring 77. Therefore, the spring spring 77 cannot be visually confirmed from the rear air inlet 44. Fig. 9 and Fig.10 As shown, this is also true even when the brush base 67 is switched to the reverse position in the forward / reverse switching unit 65. That is, each cover 105 covers the entire movement range (approximately 45°) of the spring spring 77 from the rear and radially outward, covering both the forward position and the reverse position.

[0042] The operation of the hammer drill 1 configured as above will be described. First, the switch knob 37 is switched to the electric drill mode. Then, the first clutch 34 reaches the forward position and is disengaged from the boss sleeve 31, and the second clutch 35 reaches the forward position and is engaged with the second gear 30. As a result, the rotation of the intermediate shaft 27 is not transmitted to the boss sleeve 31 but is transmitted to the second gear 30. Here, when the trigger 42 is pressed to turn on the switch 6, the motor 4 is driven to rotate the rotating shaft 16. Then, the tool holder 20 is rotated via the first gear 29, thereby rotating the tool head B at the top. Since the boss sleeve 31 does not rotate, no striking action occurs. The intermediate shaft 27, the second clutch 35, the second gear 30, the gear 25, and the tool holder 20 are an example of the rotating mechanism of the present invention.

[0043] Next, the switch knob 37 is switched to the hammer drill mode. Then, the first clutch 34 reaches the retracted position and engages with the boss sleeve 31 , and the second clutch 35 is held in the forward position. Thus, the rotation of the intermediate shaft 27 is transmitted to the boss sleeve 31 via the first clutch 34 . Therefore, when the trigger 42 is pressed in to drive the motor 4, the tool holder 20 is rotated via the intermediate shaft 27, thereby rotating the top tool head B. At the same time, the boss sleeve 31 rotates and the swing arm 33 swings back and forth, so that the piston cylinder 21 reciprocates. According to this, the hammer 22 reciprocates and strikes the tool head B via the striker 23. The intermediate shaft 27, the first clutch 34, the boss sleeve 31, the tilt bearing 32, the swing arm 33, the piston cylinder 21, the hammer 22, and the striker 23 are an example of the striking mechanism of the present invention.

[0044] Next, the switch knob 37 is switched to the hammer mode. Then, the first clutch 34 is held in the reverse position, and the second clutch 35 reaches the reverse position and is separated from the second gear 30. Thus, the rotation of the intermediate shaft 27 is transmitted only to the boss sleeve 31. Therefore, when the trigger 42 is pushed in to drive the motor 4, the piston cylinder 21 reciprocates, and the tool head B is struck by the hammer 22 via the striker 23. The tool holder 20 does not rotate. When the switch knob 37 is switched to neutral, the lock plate 39 engaged with the second gear 30 in the hammer mode is separated from the second gear 30. Thus, the tool holder 20 is freely rotatable together with the second gear 30, and the tool head B can be adjusted to any angle around the axis.

[0045] In this way, when the hammer drill 1 is used, the operator holding the handle 41 presses the rear housing 3 forward by hand. Then, the rear housing 3 overcomes the biasing force of the coil springs 51 of the vibration-proof mechanism 7 and moves forward. Accordingly, the threaded boss 57 is separated from the upper limit portion 56, and the front rib 59 is separated from the rear rib 58. As a result, even if vibration is generated in the output portion 5 or the motor housing portion 12 of the front housing 2, it is attenuated by the coil springs 51 and is not easily transmitted to the rear housing 3. Therefore, the vibration transmitted to the hand of the operator holding the handle 41 can be reduced, and discomfort is not easily generated. At this time, the bearing holding portion 60 of the front housing 2 and the handle portion 41 of the rear housing 3 are relatively close. However, the wires 81 to 83 are held by the wire holder 85 in the left-right and up-down directions behind the bearing holding portion 60 and therefore do not interfere with the handle portion 41.

[0046] The wires 81 to 83 are connected between the motor housing portion 12 on the vibration generating side and the switch 6 in the rear housing 3, and thus transmit the vibration from the motor housing portion 12. However, the wires 81 to 83 are held in a state where the middle portions 81b, 82b, and 83b are respectively wound back in the left and right directions and have slack, by the wire holder 85. Thus, the wires 81 to 83 are not easily bent due to vibration, and damage or deterioration is effectively suppressed. In addition, the wires 81 to 83 are separated from the left and right inner surfaces of the handle portion 41 and are held on the rear surface side of the bearing holding portion 60. Therefore, it is also possible to prevent the wires 81 to 83 from being caught between the wire holder 85 and the handle portion 41. In particular, the fitting pieces (protective parts) 89 are located on the left and right sides of the wires 81 to 83 passing through the rear surface side of the bearing holding portion 60. Therefore, the wires 81 to 83 are not easily spread to the left and right, and interference with the brush holder 75, the spring spring 77, etc. is prevented. In this way, the wires 81 to 83 are protected.

[0047] When the fan 46 rotates together with the rotating shaft 16, as shown in FIG. Figure 8 As shown by the middle dotted line, the outside air sucked from the rear air inlet 44 and the upper air inlet 45 passes through the outer cylinder 40 and the motor housing 12 and is discharged from the exhaust ports 47. Thus, the forward / reverse switching unit 65 and the motor 4 located in the middle of the air flow R are cooled. Here, even if the spring spring 77 having conductivity is located in front of the left and right rear air inlet 44, the cover portion 105 provided on the wire holder 85 is arranged between the rear air inlet 44 and the spring spring 77. Thus, the insulation distance between the rear air inlet 44 and the spring spring 77 is ensured, and even if foreign matter enters from the rear air inlet 44, a short circuit is unlikely to occur.

[0048] In addition, even if the cover 105 is provided, the air permeable portion 89a is formed on each engaging piece 89. Therefore, most of the air sucked from the rear air inlet 44 flows toward the motor 4 through the air permeable portion 89a as shown by the dotted arrow a. A part of the air bypasses the outside of the cover 105 and flows toward the motor 4 as shown by the dotted arrow b. In this way, the airflow R can be reliably brought into contact with the commutator 15 and the carbon brush 76. Fig.10 As shown, this also applies when the brush holder 67 is switched to the reverse position in the forward / reverse switching unit 65 .

[0049] Thus, the motor 4 and the output unit 5 are accommodated in the front housing 2 of the hammer drill 1 of the embodiment. The motor 4 has a stator 13 and a rotor 14. The rotor 14 has a commutator 15 and a rotating shaft 16. The output unit 5 is driven by the motor 4. The hammer drill 1 has a brush base 67. The brush base 67 has a carbon brush 76 and a spring spring 77. The carbon brush 76 abuts against the commutator 15. The spring spring 77 has conductivity and applies force to the carbon brush 76 toward the commutator 15. The fan 46 is provided on the rotating shaft 16. The rear housing 3 has a rear air inlet 44 and an exhaust port 47. The rear air inlet 44 sucks in external air as the fan 46 rotates, and the exhaust port 47 discharges the sucked air. The motor 4 is arranged in the middle of the air flow R flowing between the rear air inlet 44 and the exhaust port 47. The brush base 67 is arranged on the downstream side of the rear air inlet 44 of the air flow R. A non-conductive (resin in this case) cover 105 , which is disposed between the spiral spring 77 and the rear air intake port 44 and covers the spiral spring 77 , is detachably provided with respect to the front case 2 together with the wire holder 85 .

[0050] According to this structure, even if the spring spring 77 that urges the carbon brush 76 is conductive, it is not necessary to shift the position of the rear air inlet 44 in order to ensure the insulation distance between the rear air inlet 44 and the spring spring 77. That is, the insulation distance between the rear air inlet 44 and the spring spring 77 can be ensured, and the motor 4 and the carbon brush 76 can be cooled efficiently.

[0051] The housing includes a front housing 2 and a rear housing 3 assembled to the front housing 2. The cover 105 is provided in the motor housing portion 12 of the front housing 2. The rear air intake 44 is provided in the rear housing 3. According to this, the cover portion 105 can be easily assembled to the motor housing portion 12 before assembling the rear case 3 . The front housing 2 accommodates the motor 4 and the output unit 5. The rear housing 3 has a handle 41. This reduces the possibility that dust or the like generated by the operation of the delivery unit 5 is sucked in from the rear air intake port 44 on the handle portion 41 side. The brush base 67 can switch the position of the carbon brush 76 relative to the commutator 15 between the forward rotation position and the reverse rotation position of the rotor 14 by rotating the brush base 67 around the commutator 15 . The cover 105 covers the movement range of the spring spring 77 as the brush base 67 rotates. According to this, even if the brush base 67 is switched forward and reversely, the insulation distance between the rear air intake port 44 and the spiral spring 77 can be always ensured.

[0052] The output unit 5 is provided in the front housing 2. The motor 4 is housed behind the output unit 5 with the rotating shaft 16 facing the front-rear direction. A pair of carbon brushes 76 are arranged on both sides of the brush base 67. The rear air inlet 44 is provided on both sides of the rear housing 3. According to this, the left and right carbon brushes 76 can be efficiently cooled by the air sucked from the left and right rear air intake ports 44 . The hammer drill 1 includes a wire holder 85 that is detachable from the front housing 2 and is used to hold the wires 81 to 83 led out from the motor 4. The cover 105 is provided on the wire holder 85. According to this, the cover 105 can be easily attached to and detached from the front housing 2 using the wire holder 85 . The hammer drill 1 has a fitting piece 89 provided on the wire holder 85 to prevent the held wires 81 to 83 from interfering with the carbon brush 76 and the spiral spring 77. The cover 105 is provided on the fitting piece 89. According to this, the cover portion 105 can be easily installed using the fitting piece 89 .

[0053] The urging member is a spring 77 . Thus, the carbon brush 76 can be urged toward the commutator 15 at a constant tension at all times. The upper surface of the rear housing 3 has an upper air inlet 45 . According to this, the air volume of the airflow R can be increased. The output unit 5 includes a rotating mechanism and a striking mechanism. The rotating mechanism rotates the tool holder 20 holding the tool bit B as the rotating shaft 16 rotates, and the striking mechanism strikes the tool bit B as the rotating shaft 16 rotates. According to this, in the hammer drill 1 having the rotating mechanism and the striking mechanism, the insulation distance between the rear air inlet 44 and the spring spring 77 can be ensured, and the motor 4 and the carbon brush 76 can be efficiently cooled.

[0054] Next, modified examples of the present invention will be described. The shape of the cover is not limited to that of the embodiment. For example, the cross section of the cover may be L-shaped instead of arc-shaped. The cover may be attached to the fitting piece as a separate component from the fitting piece. The cover portion may not be large enough to cover the entire movement range of the clockwork spring between the normal rotation position and the reverse rotation position, but may be provided in plurality at positions covering the clockwork spring at the normal rotation position and the clockwork spring at the reverse rotation position, respectively. The cover portion may not be formed continuously with the fitting piece of the wire holder. The cover portion may be formed continuously with the annular portion of the wire holder.

[0055] The shape of the wire holder can also be changed appropriately. For example, the shape or size of the air-permeable portion of the interlocking piece can also be changed. The air-permeable portion can also be absent. The disassembly structure of the annular portion to the bearing holding portion can also be changed. The shape of the holding portion or the locking piece of the wire can also be changed. The two electrical components connected by the wire are not limited to the motor and the switch. The two electrical components can also be, for example, a motor and a controller. The cover member may not be provided on the wire holder. The cover member may be independently attachable to and detachable from the bearing holding portion or the motor housing portion. The shape of the brush base can also be changed as appropriate. For example, the operation protrusion may not be provided on the upper side, but may be provided on the lateral side of either the left or right side, and may protrude from a window provided on the side surface of the housing. The urging member is not limited to the spring, and may be a leaf spring or a coil spring.

[0056] The hammer drilling method is not limited to the embodiment. For example, in the vibration-proof mechanism, the number and position of the coil springs can be changed appropriately. It can also be an elastic component other than the coil spring. It is also possible not to have a vibration-proof mechanism. Accordingly, the housing can also be a structure that is not divided into front and back. The selectable operation modes are not limited to three. The position of the switching knob can also be changed as appropriate. The striking action may also be a structure in which the piston reciprocates in a fixed cylinder instead of in a piston cylinder. It may also be a structure in which there is no striker but the hammer directly strikes the tool head. The striking action may also be a structure in which the crank mechanism is used instead of the boss sleeve. There may also be only one clutch. The electric tool is not limited to the hammer drill of the embodiment, and the present invention can also be applied to other electric tools such as electric hammers and electric drills.

Claims

1. An electric tool, characterized in that: It comprises a motor (4), an output unit (5), a fan (46), a housing (2, 3), a brush holding component (67) and a cover component (105), wherein: The motor (4) comprises a stator (13) and a rotor (14), wherein the rotor (14) comprises a commutator (15) and a rotating shaft (16). The output unit (5) is driven by the motor (4) to operate; The fan (46) is arranged on the rotating shaft (16); The housing (2, 3) accommodates the motor (4) and the output unit (5), and the housing (2, 3) has an air inlet (44) and an air outlet (47), the air inlet (44) sucks in external air as the fan (46) rotates; the air outlet (47) discharges the sucked air, and the housing (2, 3) is such that the motor (4) is arranged in the middle of an airflow flowing between the air inlet (44) and the air outlet (47); The brush holding member (67) is arranged on the downstream side of the air inlet (44), and the brush holding member (67) has a brush (76) and a force applying member (77), wherein the brush (76) abuts against the commutator (15); the force applying member (77) is conductive and applies force to the brush (76) toward the commutator (15); The cover member (105) is non-conductive and can be attached or detached relative to the housing (2, 3). The cover member (105) is arranged between the force applying member (77) and the air inlet (44) to cover the force applying member (77).

2. The electric tool (1) according to claim 1, characterized in that: The housing (2, 3) comprises a first housing (2) and a second housing (3). The second housing (3) is assembled to the first housing (2). The cover member (105) is provided on the first housing (2). The air inlet (44) is provided in the second housing (3).

3. The electric tool (1) according to claim 2, characterized in that: The first housing (2) accommodates the motor (4) and the output unit (5). The second housing (3) has a handle portion (4).

4. The electric tool (1) according to any one of claims 1 to 3, characterized in that: The brush holding member (67) is capable of switching the position of the brush (76) relative to the commutator (15) between a forward rotation position and a reverse rotation position of the rotor (14) by rotating the brush holding member (67) around the commutator (15). The cover member (105) covers a moving range of the urging member (77) as the brush holding member (67) rotates.

5. The electric tool (1) according to any one of claims 1 to 4, characterized in that: The output portion (5) is arranged at the front portion of the housing (2, 3), The motor (4) is housed behind the output portion (5) with the rotating shaft (16) facing the front-rear direction. A pair of brushes (76) are arranged on the left and right sides of the brush holding member (67). The air inlet (44) is arranged on the left and right sides of the shell (2, 3).

6. The electric tool (1) according to any one of claims 1 to 5, characterized in that: It also has a wiring holding component (85), which is detachable relative to the housing (2, 3) and is used to hold wiring (81-83) led out from the motor (4). The cover member (105) is provided on the wiring holding member (85).

7. The electric tool (1) according to claim 6, characterized in that: A protection portion (89) is provided on the wiring holding member (85) to prevent the held wiring (81-83) from interfering with the brush (76) and the biasing member (77). The cover member (105) is provided on the protection portion (89).

8. The electric tool (1) according to any one of claims 1 to 7, characterized in that: The force applying component (77) is a spring (77).

9. The electric tool (1) according to claim 5, characterized in that: The housing (2, 3) has a second air inlet (45) on the upper surface.

10. The electric tool (1) according to any one of claims 1 to 9, characterized in that: The output part (5) has a rotating mechanism and a striking mechanism, wherein: The rotating mechanism rotates the final output shaft (20) holding the top tool (B) as the rotating shaft (16) rotates; The striking mechanism strikes the tip tool (B) as the rotating shaft (16) rotates.

Images