Power tool

Abstract

To provide a power tool which can efficiently cool a motor and a brush while securing an insulation distance between an inlet and an urging member.SOLUTION: In a front housing 2 of a power tool, a motor 4 and an output unit are accommodated, and a brush base 67 is arranged including: a carbon brush 76 contacting with a commutator 15; and an electric conductive spiral spring 77 urging the carbon brush 76 toward the commutator 15 side. In a rear side housing 3, a rear inlet 44 sucking outside air in response to rotation of a fan and an outlet discharging sucked air are respectively formed, the motor 4 is arranged along an airflow R flowing between the rear inlet 44 and the outlet, and the brush base 67 is arranged downstream of the rear inlet 44 in the airflow R. In the front side housing 2, a non-conducting cover 105 arranged between the spiral spring 77 and the rear inlet 44 and covering the spiral spring 77 is removably arranged with a lead wire holder 85.SELECTED DRAWING: Figure 8

Description

[Technical field]

[0001] The present disclosure relates to power tools, such as hammer drills. [Background technology]

[0002] AC machines equipped with brushed motors are known for power tools such as hammer drills. The brushes are held in a ring-shaped brush holder through which the rotor passes, and are pressed against a commutator by a metal biasing member such as a spiral spring. Meanwhile, a fan is provided in front of the rotor. When the fan rotates with the rotation of the rotor, outside air is drawn in through an intake port provided in the housing, and an airflow is generated that is exhausted from an exhaust port provided on the radial outside of the fan. This airflow cools the motor and brushes (for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2022-124291 A Summary of the Invention [Problem to be solved by the invention]

[0004] To improve the cooling effect of the motor and brushes, it is desirable to locate the air intake near the brush holder. However, if the biasing member that biases the brushes is conductive, it becomes necessary to position the air intake away from the brush holder in order to ensure an insulating distance between the air intake and the biasing member. This may result in inefficient cooling.

[0005] Therefore, an object of the present disclosure is to provide an electric tool that can efficiently cool the motor and brushes while ensuring an insulation distance between the air intake and the biasing member. [Means for solving the problem]

[0006] In order to achieve the above object, the present disclosure provides a motor having a stator and a rotor, and an output section that is operated by driving the motor, which is accommodated in a housing, and a brush holding member having a brush that contacts a commutator provided on the rotor and a conductive biasing member that biases the brush toward the commutator is provided, A fan is provided on the rotating shaft of the rotor, and the housing is formed with an intake port that draws in outside air as the fan rotates, and an exhaust port that expels the sucked in air.The motor is positioned in the air flow between the intake port and the exhaust port, and a brush holding member is positioned downstream of the intake port in the air flow.This is an electric tool. The present disclosure is characterized in that a non-conductive cover member that is disposed between the urging member and the air intake port and covers the urging member is removably provided on the housing. Effect of the Invention

[0007] According to the present disclosure, by employing a cover member, even if the biasing member that biases the brush is conductive, it is not necessary to shift the position of the air intake to ensure an insulating distance between the air intake and the biasing member. In other words, the motor and the brush can be efficiently cooled while ensuring an insulating distance between the air intake and the biasing member. [Brief description of the drawings]

[0008] [Figure 1] FIG. 2 is a rear perspective view of the hammer drill. [Diagram 2] FIG. [Diagram 3] 3 is a cross-sectional view taken along line AA in FIG. 2. [Figure 4] FIG. 3 is a partial cross-sectional view taken along line BB in FIG. [Diagram 5] FIG. 2 is a partially enlarged rear view of the hammer drill with the rear housing omitted (in the normal rotation position). [Figure 6] FIG. 2 is a perspective view of the hammer drill with the rear housing omitted. [Figure 7] FIG. 4 is an exploded perspective view of the forward / reverse switching unit and the lead wire holder. [Figure 8] 3 is a partially enlarged cross-sectional view taken along the line CC in FIG. 2. [Figure 9] FIG. 2 is a partially enlarged rear view of the hammer drill with the rear housing omitted (reverse rotation position). [Figure 10] 3 is a partially enlarged cross-sectional view corresponding to line CC in FIG. 2 at a reverse rotation position. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] In one embodiment of the present disclosure, the housing may comprise a first housing and a second housing assembled to the first housing, with the cover member being provided on the first housing and the air intake being provided on the second housing. According to this configuration, the cover member can be easily attached to the first housing before the second housing is attached. In one embodiment of the present disclosure, a first housing may house the motor and the output portion, and a second housing may include a handle portion. This configuration reduces the risk of dust and other particles generated by the operation of the output section being sucked in through the intake port on the handle portion side. In one embodiment of the present disclosure, the brush holding member can be rotated around the commutator to switch the position of the brush relative to the commutator between a forward rotation position and a reverse rotation position of the rotor, and the cover member may cover the range of movement of the biasing member that accompanies the rotation of the brush holding member. According to this configuration, even if the brush holding member is switched between forward and reverse directions, an insulating distance can always be ensured between the air intake port and the biasing member.

[0010] In one embodiment of the present disclosure, the output unit may be provided at the front of the housing, the motor may be accommodated behind the output unit with its rotating shaft facing in the fore-and-aft direction, the brushes may be arranged in pairs on the left and right sides of the brush holding member, and air intakes may be provided on the left and right sides of the housing. According to this configuration, the left and right brushes can be efficiently cooled by air drawn in through the left and right air intakes. In one embodiment of the present disclosure, a wiring holding member for holding wiring drawn out from the motor may be removably provided on the housing, and the cover member may be provided on the wiring holding member. According to this configuration, the cover member can be easily attached to and detached from the housing by utilizing the wiring holding member. In one embodiment of the present disclosure, the wiring holding member is provided with a protective portion that prevents interference between the held wiring and the brush and the urging member, and the cover member may be provided on the protective portion. According to this configuration, the cover member can be easily provided by utilizing the protective portion.

[0011] In one embodiment of the present disclosure, the biasing member may be a spiral spring. According to this configuration, the brush can be always biased against the commutator with a constant tension. In one embodiment of the present disclosure, a second air intake may be provided on the top surface of the housing. This configuration can increase the volume of the airflow. In one embodiment of the present disclosure, the output section may have a rotation mechanism that rotates a final output shaft that holds a tool bit in accordance with the rotation of the rotation shaft, and an impact mechanism that impacts the tool bit in accordance with the rotation of the rotation shaft. According to this configuration, in a hammer drill having a rotation mechanism and an impact mechanism, the motor and the brushes can be efficiently cooled while ensuring an insulation distance between the air intake and the biasing member. EXAMPLES

[0012] Hereinafter, an embodiment of the present disclosure will be described with reference to the drawings. FIG. 1 is a rear perspective view of a hammer drill, which is an example of a power tool, FIG. 2 is a rear view of the hammer drill, and FIG. 3 is a cross-sectional view taken along line AA. The hammer drill 1 has a front housing 2 and a rear 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 housing 2 and the rear housing 3 are capable of moving relative to each other in the front-rear direction. Between the front housing 2 and the rear housing 3, a vibration isolation mechanism 7, which will be described later, is provided. The front housing 2 is an example of a first housing of the present disclosure, and the rear housing 3 is an example of a second housing of the present disclosure.

[0013] The front housing 2 includes a motor housing 8, an outer housing 9, and an inner housing 10. The motor housing 8 is made of resin and includes a front connecting portion 11 and a rear motor accommodating portion 12. The connecting portion 11 is in the shape of a rectangular tube, and is screwed to the outer housing 9. The motor accommodating portion 12 is in the shape of a cylinder with a smaller diameter than the connecting portion 11, and accommodates the motor 4 inside. The motor 4 has a stator 13 and a rotor 14. The rotor 14 is equipped with a commutator 15 and a rotating shaft 16. The motor 4 is accommodated in the motor accommodating section 12 with the rotating shaft 16 facing in the front-rear direction. The rotating shaft 16 penetrates the connecting section 11 and protrudes into the inner housing 10.

[0014] The outer housing 9 is made of resin and has a front tubular portion 17 and a rear tubular portion 18. The front tubular portion 17 is tubular with a circular cross section that extends forward. The rear tubular portion 18 is tubular with a larger diameter than the front tubular portion 17. The connecting portion 11 of the motor housing 8 is connected to the rear tubular portion 18. The front tubular portion 17 is disposed in an eccentric position above the rear tubular portion 18. A side handle 19 can be attached to the front tubular portion 17. The output section 5 has a tool holder 20, a piston cylinder 21, a striker 22, and an impact bolt 23. The tool holder 20 is cylindrical, coaxially housed in the front cylindrical portion 17, and rotatably held by the front cylindrical portion 17 and the inner housing 10. The front end of the tool holder 20 protrudes forward from the front cylindrical portion 17. An operation sleeve 24 is provided at the front end of the tool holder 20. The operation sleeve 24 is provided to attach and detach the bit B at the front end of the tool holder 20. A gear 25 is fitted to the exterior of the tool holder 20 inside the rear cylindrical portion 18. The tool holder 20 is an example of a final output shaft of the present disclosure. The bit B is an example of a tool tip of the present disclosure.

[0015] The piston cylinder 21 is open at its front end and is housed in the rear of the tool holder 20 so as to be movable back and forth. The striker 22 is housed in the piston cylinder 21 so as to be movable back and forth via an air chamber 26. The impact bolt 23 is housed in the tool holder 20 in front of the striker 22 so as to be movable back and forth. In the output section 5, an intermediate shaft 27 parallel to the tool holder 20 is rotatably provided below the tool holder 20. The rotating shaft 16 of the motor 4 has a pinion 28 formed at its front end protruding above the intermediate shaft 27. The intermediate shaft 27 is provided at its rear with a first gear 29 that meshes with the pinion 28 and is capable of rotating integrally with the intermediate shaft 27. The intermediate shaft 27 is provided at its front with a second gear 30 that is capable of rotating separately. The second gear 30 meshes with the gear 25 of the tool holder 20. A boss sleeve 31 is separately and rotatably mounted on the intermediate shaft 27 in front of the first gear 29. An arm 33 is held facing upward by the boss sleeve 31 via a swash bearing 32 whose axis is inclined. The tip of the arm 33 is connected to the rear end of the piston cylinder 21.

[0016] Two first and second clutches 34, 35 are splined between the boss sleeve 31 and the second gear 30. The first clutch 34 engages with the boss sleeve 31 in the retracted position. Therefore, 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 separates 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 engages with the second gear 30 in the forward position. Therefore, the rotation of the intermediate shaft 27 is transmitted to the second gear 30 via the second clutch 35, and is further transmitted to the gear 25 and the tool holder 20. When the second clutch 35 retracts and moves away 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.

[0017] Two plates 36, 36 that engage with both clutches 34, 35 are provided below the intermediate shaft 27 so as to be movable back and forth. The position of each plate 36 can be changed by a changeover knob 37. The changeover knob 37 is provided on the underside of the rear cylindrical portion 18 so as to be rotatable. The changeover knob 37 has an eccentric pin 38 that protrudes upward. The eccentric pin 38 engages with each plate 36. A lock plate 39 that can be engaged with and disengaged from the second gear 30 engages with the changeover knob 37. Therefore, by rotating the switching knob 37, the front-rear position of each plate 36 can be switched via the eccentric pin 38. In other words, by switching the front-rear positions of the first and second clutches 34, 35, it is possible to select drill mode, hammer drill mode, neutral, or hammer mode. Each operation mode will be described later.

[0018] The rear housing 3 is made of resin and consists of a pair of left and right half housings 3a, 3b. The half housings 3a, 3b are assembled with a number of screws screwed in from the right side. The front side of the rear housing 3 is provided with an outer cylinder portion 40 that covers the motor accommodating portion 12 from the rear. The front end of the outer cylinder portion 40 has the same outer shape as the connecting portion 11 of the motor housing 8. A handle portion 41 extending downward is integrally formed at the rear of the outer cylinder portion 40. The switch 6 is accommodated in the upper part of the handle portion 41, with a trigger 42 protruding forward. A power cord 43 is connected to the switch 6. The power cord 43 is pulled out from the lower end of the handle portion 41. A plurality of rear intake ports 44, 44... are formed on the left and right sides of the rear surface of the outer cylinder portion 40. A plurality of upper intake ports 45, 45... are formed on the upper rear surface of the outer cylinder portion 40. A fan 46, which is a centrifugal fan, is attached to the rotating shaft 16 inside the connecting portion 11. A plurality of exhaust ports 47, 47... are formed on the lower surface and right side surface of the connecting portion 11, respectively. The rear intake port 44 is an example of an intake port of the present disclosure. The upper intake port 45 is an example of a second intake port of the present disclosure.

[0019] The vibration isolation mechanism 7 includes a rubber sleeve 50 and a coil spring 51 . The rubber sleeve 50 is interposed between the connecting portion 11 of the motor housing 8 and the outer tubular portion 40 of the rear housing 3. The rubber sleeve 50 is a bellows-shaped rectangular tube, with its front end engaging with the rear end surface of the connecting portion 11 and its rear end engaging with the front end surface of the outer tubular portion 40. The rubber sleeve 50 closes the gap between the front housing 2 and the rear housing 3 over the entire circumference, and expands and contracts in the axial direction in accordance with the relative movement of the two housings 2, 3 forward and backward. The coil spring 51 is interposed between the motor accommodating portion 12 and the outer cylinder portion 40 inside the rear housing 3. One coil spring 51 is arranged on the upper side of the motor accommodating portion 12, and two coil springs 51 are arranged on the left and right sides on the lower side of the motor accommodating portion 12. A front receiving plate 52 extending in the left-right direction is erected on the upper surface of the motor accommodating portion 12. A rear receiving plate 53 extending in the left-right direction is provided on the inner surface of the outer cylinder portion 40 behind the front receiving plate 52. The upper coil spring 51 is arranged in the front-rear direction between the front receiving plate 52 and the rear receiving plate 53.

[0020] A pair of left and right front spring bearings 54, 54 (FIG. 5) are provided on the rear surface of the connecting portion 11 below the motor accommodating portion 12. A pair of left and right rear spring bearings 55, 55 are formed on the inner surface of the outer cylinder portion 40 behind each front spring bearing 54. The two lower coil springs 51, 51 are arranged in the front-rear direction between the front spring bearings 54, 54 and the rear spring bearings 55, 55. Therefore, the front housing 2 and the rear housing 3 are biased in a direction away from each other by the rubber sleeve 50 and the three coil springs 51. However, in the retracted position where the rear housing 3 is separated from the front housing 2, as shown in FIG. 3, an upper stopper 56 protruding forward from the front receiving plate 52 abuts against a screw boss 57 protruding rightward from the left half housing 3a. Also, on the lower side of the motor housing 12, a left-right rear rib 58 protruding downward from the motor housing 12 abuts against a left-right front rib 59 protruding upward from the inner surface of the outer tube portion 40 in front of the rear rib 58. Therefore, in a normal state, the rear housing 3 is biased to the retracted position shown in FIG. 3 where the upper stopper 56 abuts against the screw boss 57 and the rear rib 58 abuts against the front rib 59.

[0021] As shown in Figs. 4 to 7, a bearing holder 60 is provided on the rear side of the motor housing 12. The bearing holder 60 is smaller in diameter than the motor housing 12 and is in the form of a cap that opens forward. The bearing holder 60 is coaxially connected to the rear surface of the motor housing 12 by upper and lower arm portions 61, 61 extending in the front-rear direction. The bearing holder 60 holds a bearing 62 on its rear inner surface and supports the rear end of the rotating shaft 16. The arm portions 61, 61 are formed in a concentric arc shape centered on the axis of the rotating shaft 16. The commutator 15 of the rotor 14 is exposed to the left and right between the arm portions 61, 61. A pair of step portions 63, 63 recessed forward from the rear surface of the bearing holder 60 are formed on the rear ends of the arm portions 61, 61, respectively.

[0022] A forward / reverse switching unit 65 is attached to the rear surface of the motor accommodating portion 12. The forward / reverse switching unit 65 includes a unit base 66 and a brush base 67. The unit base 66 is disk-shaped, and two left and right points are screwed coaxially from the rear to the motor accommodating portion 12. As shown in Figures 7 and 8, the unit base 66 is provided with a pair of fixed contacts 68, 68. The fixed contacts 68, 68 are arc-shaped when viewed from behind, and are disposed in point-symmetric positions with respect to the axis of the unit base 66. An insulator provided at the rear of the stator 13 of the motor 4 is formed with four terminal holders 70, 70... (FIG. 8) located at the vertices of a rectangle in rear view. Each terminal holder 70 is provided with a terminal 71. The unit base 66 is provided with four connection terminals 72, 72... electrically connected to the four terminals 71, as shown in FIGS. 5, 6, 7, and 10. Of the four connection terminals 72, a pair of connection terminals 72, 72 located at the upper left and lower right diagonally in rear view are formed integrally with the fixed contacts 68, 68. Lead wires 81, 82, which will be described later, are connected to the other pair of connection terminals 72, 72 located at the lower left and upper right diagonally.

[0023] The brush base 67 is coaxially and rotatably mounted on the rear surface of the unit base 66. The brush base 67 is short and cylindrical, and has a pair of brush holders 75, 75 arranged in diametrical positions at point symmetrical positions. Each brush holder 75 accommodates a carbon brush 76. The carbon brush 76 is biased toward the axial center of the brush base 67 by a spiral spring 77 provided in the brush holder 75, and presses the commutator 15 between the arms 61, 61. The brush base 67 is an example of a brush holding member of the present disclosure. The carbon brush 76 is an example of a brush of the present disclosure. The spiral spring 77 is an example of a biasing member of the present disclosure. A pair of movable contacts 78, 78 are provided on the brush base 67. The movable contacts 78, 78 are held integrally on the brush base 67 via a pair of holding blocks 73, 73 attached to the brush base 67, and are electrically connected to the carbon brushes 76, 76, as shown in Fig. 7. The movable contacts 78, 78 are positioned concentrically with the fixed contacts 68, 68 of the unit base 66, and can be brought into contact with and separated from the fixed contacts 68, 68 as the brush base 67 rotates. An operation protrusion 79 is provided on the upper peripheral surface of the brush base 67. The operation protrusion 79 protrudes radially outward from the outer peripheral surface of the brush base 67 and, as shown in FIG. 1, penetrates a window 80 provided on the upper surface of the rear housing 3 to be exposed upward.

[0024] Therefore, in the forward / reverse switching unit 65, the brush base 67 can be rotated from the outside via the operation protrusion 79. By rotating the brush base 67, the movable contacts 78, 78 are moved toward and away from the fixed contacts 68, 68 to switch the direction of current flow, thereby switching the rotation direction of the rotor 14. That is, the brush base 67 can be switched between a forward rotation position where the movable contacts 78, 78 contact the fixed contacts 68, 68 in the forward rotation direction, a reverse rotation position where the movable contacts 78, 78 contact the fixed contacts 68, 68 in the reverse rotation direction, and a neutral position between the forward rotation positions where the movable contacts 78, 78 do not contact the fixed contacts 68, 68. FIGS. 1 to 6 show the forward rotation position where 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, the reverse rotation position is set, and when the operation protrusion 79 is tilted toward the center in the left-right direction, the neutral position is set.

[0025] As shown in Figures 5 and 6, the stator 13 and the switch 6 are electrically connected by three lead wires 81, 82, and 83. Of these, two of the lead wires 81, 82 are connected to another pair of connection terminals 72, 72 on which the fixed contacts 68, 68 are not formed, and are drawn out from the unit base 66. The remaining lead wire 83 is connected to one of the connection terminals (the upper left connection terminal in Figure 5) 72 on which the fixed contacts 68, 68 are formed, and is drawn out from the motor accommodating portion 12. Each of the lead wires 81 to 83 is held at the rear side of the motor accommodating portion 12 via a lead wire holder 85 assembled to the bearing holding portion 60. The lead wires 81 to 83 are an example of the wiring of the present disclosure. The lead wire holder 85 is made of resin, and has a ring portion 86 and a support plate portion 87 as shown in FIG. The lead wire holder 85 is an example of a wiring holding member of the present disclosure.

[0026] The ring portion 86 is in the shape of a ring with an inner diameter larger than that of the bearing holder 60. A pair of engagement pieces 88, 88 that engage with the upper and lower step portions 63, 63 of the arm portions 61, 61, respectively, are formed on the inner circumference of the ring portion 86. A pair of fitting pieces 89, 89 that fit into the bearing holder 60 are formed on the left and right sides of the ring portion 86. The fitting pieces 89, 89 are in the shape of an arc plate that expands radially outward from the front end that fits into the bearing holder 60 toward the rear. A hook 90 that protrudes inward is formed over the entire length at the front end of each fitting piece 89. However, a ventilation portion 89a that is cut out from the front end to near the rear end is provided at the circumferential center of each fitting piece 89. 4 and 8, the hook 90 engages with the front end of the bearing holder 60 from the front to restrict rearward movement of the ring portion 86. A pair of clamping claws 91, 91 protruding rearward are formed on the front surface of the ring portion 86 below the fitting pieces 89, 89. A first retaining portion 92 and a second retaining portion 93 are provided side by side on the upper surface of the ring portion 86. The first retaining portion 92 is a plate-like member extending in the front-rear direction and protruding upward. A first locking piece 94 that is L-shaped in plan view and protrudes to the left is integrally formed sideways at the upper end of the first retaining portion 92. The second holding portion 93 is a plate-like member extending in the front-rear direction and protruding upward on the right side of the first holding portion 92. A second locking piece 95 having an inverted U-shape in side view and a notch opening forward at the center in the up-down direction is integrally formed facing forward at the front end of the second holding portion 93.

[0027] The support plate portion 87 has a vertical plate 96 and a horizontal plate 97. The vertical plate 96 rises upward from the upper rear end of the ring portion 86 in front of the first and second holding portions 92, 93. The horizontal plate 97 extends forward from the upper end of the vertical plate 96. A first opening 98 that is rectangular in rear view is formed in the vertical plate 96 in front of the first holding portion 92. A second opening 99 that is inverted L-shaped in rear view is formed in the vertical plate 96 in front of the second holding portion 93. A pair of locking grooves 100, 100 are formed on the left and right sides of the vertical plate 96. The locking grooves 100, 100 are cut in an upward slant from the side edges of the vertical plate 96 toward the center on the left and right sides, and then cut straight up. An eaves portion 101 protruding rearward is formed in the left-right center of the horizontal plate 97. The eaves portion 101 is located above but not in contact with the first holding portion 92 and the second holding portion 93. A notch portion 102 that opens forward is formed in the left-right center of the front portion of the horizontal plate 97.

[0028] To assemble the lead wire holder 85, the engagement pieces 88, 88 are aligned with the steps 63, 63, and the ring portion 86 is fitted into the bearing holder 60 from the rear. Then, the bearing holder 60 fits between the engagement pieces 89, 89, and the hooks 90, 90 engage with the front end of the bearing holder 60, preventing it from slipping out rearward. At this time, the horizontal plate 97 is located above the brush base 67. A protrusion 103 that protrudes rearward is formed on the upper surface of the motor accommodating portion 12. When the lead wire holder 85 is in an assembled state, the protrusion 103 fits into the front portion of a notch 102 of the horizontal plate 97 to close the front of the notch 102. The operation projection 79 provided on the brush base 67 penetrates the notch 102 behind the protrusion 103 and protrudes upward.

[0029] As shown in Figs. 5 and 6, among the three lead wires 81 to 83, the lead wire 81 indicated by the dashed line has a starting end 81a that is drawn out rearward from the unit base 66 outside the brush base 67. The lead wire 81 is then clamped by the clamping claws 91, 91 of the lead wire holder 85. The lead wire 81 clamped by the clamping claws 91, 91 extends upward behind the bearing holder 60 in a slack state, and the middle portion 81b is locked from below by the first locking piece 94 of the first holder 92. The middle portion 81b locked to the first locking piece 94 is pulled out to the right from the first holder 92 and locked from the left by the second locking piece 95 of the second holder 93. A vertical plate 96 is located in front of the first and second locking pieces 94, 95, but the first and second openings 98, 99 are formed, so that the lead wire 81 can be locked without any problems. After the wiring is completed, the vertical plate 96 restricts the forward movement of the intermediate portion 81b. The lead wire 81 drawn out to the right from the second locking piece 95 is routed downward behind the bearing holding portion 60. Then, the end portion 81c is connected to the switch 6. That is, the lead wire 81 is drawn out from below the axis of the motor accommodating portion 12, and the middle portion 81b is held in the left-right direction by the lead wire holder 85 above the axis. Thereafter, the lead wire 81 is again routed downward from the axis and connected to the switch 6.

[0030] The lead wire 82, indicated by the two-dot chain line, has a starting end 82a that is drawn out rearward from the unit base 66 outside the brush base 67. The lead wire 82 is then locked from the front into a locking groove 100 on the right side of a vertical plate 96 of the lead wire holder 85. After being pulled out rearward, the lead wire 82 locked into the locking groove 100 is routed to the left with the middle portion 82b left in a slack state. The middle portion 82b is then locked from the right side by a second locking piece 95 of the second holding portion 93, and is pulled out to the left of the second locking piece 95. The locking of the middle portion 82b can also be performed without hindrance by the second opening 99, and forward movement is restricted by the vertical plate 96. The lead wire 82 drawn out from the second locking piece 95 is routed downward behind the bearing holding portion 60. Then, the end portion 82c is connected to the switch 6. That is, the lead wire 82 has an intermediate portion 82b held in the left-right direction by the lead wire holder 85 above the axis of the motor accommodating portion 12. Thereafter, the lead wire 82 is routed downward from the axis and connected to the switch 6.

[0031] The lead wire 83, indicated by a three-dot chain line, has a starting end 83a that is drawn rearward from the motor housing portion 12 outside the unit base 66. The lead wire 83 is then locked from the front into a locking groove 100 on the left side of the vertical plate 96. After being pulled rearward, the lead wire 83 locked into the locking groove 100 is routed to the right with the middle portion 83b left slack. The middle portion 83b is then locked from the left side by the second locking piece 95 of the second holding portion 93 and drawn to the right of the second locking piece 95. The locking of the middle portion 83b can also be performed without hindrance by the second opening 99, and forward movement is restricted by the vertical plate 96. The lead wire 83 drawn out to the right side from the second locking piece 95 is routed downward behind the bearing holding portion 60. Then, the terminal end 83c is connected to the switch 6. That is, the lead wire 83 has a middle portion 83b held in the left-right direction by the lead wire holder 85 above the axis of the motor accommodating portion 12. Thereafter, the lead wire 83 is routed downward from the axis and connected to the switch 6.

[0032] Cover portions 105, 105 are formed on the fitting pieces 89, 89 of the ring portion 86. Each cover portion 105 is formed continuously with a slightly small width from the rear end of the fitting piece 89 in the circumferential direction, and has an arc-shaped cross section that extends forward as it moves radially outward. Therefore, as shown in FIGS. 5, 6 and 8, each cover portion 105 covers each spiral spring 77 from the rear and from the radially outer side. At this time, each cover portion 105 is positioned between the left and right rear air intake ports 44 and the spiral spring 77, so that the spiral spring 77 cannot be seen from the rear air intake ports 44. This is the same even when the brush base 67 is switched to the reverse rotation position in the forward / reverse switching unit 65, as shown in Figures 9 and 10. That is, each cover portion 105 covers the entire movement range (about 45°) of the spiral spring 77 between the forward rotation position and the reverse rotation position from the rear and from the radially outer side. The cover portion 105 is an example of a cover member of the present disclosure.

[0033] The operation of the hammer drill 1 constructed as above will now be described. First, the switch knob 37 is switched to the drill mode. Then, the first clutch 34 is in the forward position and separates from the boss sleeve 31, and the second clutch 35 is in the forward position and engages with the second gear 30. Therefore, the rotation of the intermediate shaft 27 is not transmitted to the boss sleeve 31, but is transmitted to the second gear 30. When the trigger 42 is pressed to turn on the switch 6, the motor 4 is driven to rotate the rotary shaft 16. This rotates the tool holder 20 via the first gear 29, rotating the bit B at the tip. Since the boss sleeve 31 does not rotate, no impact 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 a rotation mechanism of the present disclosure.

[0034] Next, the switch knob 37 is switched to the hammer drill mode. Then, the first clutch 34 is in the backward position and engages with the boss sleeve 31, and the second clutch 35 remains in the forward position. Therefore, 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 to drive the motor 4, the tool holder 20 rotates via the intermediate shaft 27, rotating the bit B at the tip. At the same time, the boss sleeve 31 rotates and the arm 33 swings back and forth, causing the piston cylinder 21 to reciprocate. As a result, the striker 22 reciprocates, striking the bit B via the impact bolt 23. The intermediate shaft 27, the first clutch 34, the boss sleeve 31, the swash bearing 32, the arm 33, the piston cylinder 21, the striker 22, and the impact bolt 23 are an example of an impact mechanism of the present disclosure.

[0035] Next, the switch knob 37 is switched to the hammer mode. Then, the first clutch 34 remains in the rearward position, and the second clutch 35 moves to the rearward position and moves away from the second gear 30. Therefore, the rotation of the intermediate shaft 27 is transmitted only to the boss sleeve 31. Therefore, when the trigger 42 is pressed to drive the motor 4, the piston cylinder 21 reciprocates, and the bit B is struck by the striker 22 via the impact bolt 23. The tool holder 20 does not rotate. When the switching knob 37 is switched to neutral, the lock plate 39 that has been engaged with the second gear 30 in the hammer mode is separated from the second gear 30. Therefore, the tool holder 20 together with the second gear 30 becomes free to rotate, and the bit B can be adjusted to any angle around the axis.

[0036] Thus, when using the hammer drill 1, the rear housing 3 is pressed forward by the hand of an operator holding the handle portion 41. Then, the rear housing 3 moves forward against the bias of each coil spring 51 of the vibration-proof mechanism 7. Thus, the screw boss 57 moves away from the upper stopper 56, and the front rib 59 moves away from the rear rib 58. As a result, even if vibrations occur in the output portion 5 or the motor accommodating portion 12 of the front housing 2, they are damped by each coil spring 51 and are not easily transmitted to the rear housing 3. Therefore, the vibrations transmitted to the hand of the operator holding the handle portion 41 are reduced, making it less likely that the operator will feel uncomfortable. At this time, the bearing holding portion 60 of the front housing 2 and the handle portion 41 of the rear housing 3 come relatively close to each other. However, the lead wires 81 to 83 are held in the left-right and up-down directions by the lead wire holder 85 behind the bearing holding portion 60, so they do not interfere with the handle portion 41.

[0037] And, since the lead wires 81 to 83 are connected between the motor accommodating section 12 on the vibration generating side and the switch 6 in the rear housing 3, the vibration from the motor accommodating section 12 is transmitted to them. However, the lead wires 81 to 83 are held in a slack state with intermediate portions 81b, 82b, and 83b of the lead wires 81 to 83 routed in the left-right direction by the lead wire holder 85. Therefore, the lead wires 81 to 83 are less likely to bend due to vibration, and damage and deterioration are effectively suppressed. Furthermore, since the lead wires 81-83 are held on the rear side of the bearing holding part 60 away from the left and right inner surfaces of the handle part 41, it is possible to prevent the lead wires 81-83 from being pinched between the lead wire holder 85 and the handle part 41. In particular, since the fitting pieces 89, 89 are located on the left and right of the lead wires 81-83 passing through the rear side of the bearing holding part 60, the lead wires 81-83 are prevented from spreading out to the left and right, preventing interference with the brush holder 75, the spiral spring 77, etc. This leads to protection of the lead wires 81-83. The fitting piece 89 is an example of a protective portion of the present disclosure.

[0038] On the other hand, when the fan 46 rotates together with the rotary shaft 16, as shown by the dotted line in Fig. 8, outside air is sucked in from the rear intake port 44 and the upper intake port 45, passes through the outer cylinder portion 40 and the motor housing portion 12, and is exhausted from each exhaust port 47, generating an air flow R. Thus, the forward / reverse switching unit 65 and the motor 4, which are positioned in the middle of the air flow R, are cooled. Here, even if the conductive spiral springs 77 are located in front of the left and right rear air intakes 44, respectively, the cover portion 105 provided on the lead wire holder 85 is disposed between the rear air intakes 44 and the spiral springs 77. Therefore, an insulation distance between the rear air intakes 44 and the spiral springs 77 is ensured, and even if a foreign object enters through the rear air intakes 44, a short circuit is unlikely to occur. Even when the cover parts 105, 105 are provided in this manner, the ventilation part 89a is formed in each fitting piece 89, so that most of the air sucked in from the rear air intake port 44 flows toward the motor 4 through the ventilation part 89a as indicated by the dotted arrow a, and part of the air flows toward the motor 4 by going around the outside of the cover part 105 as indicated by the dotted arrow b. This allows the air flow R to reliably come into contact with the commutator 15 and the carbon brushes 76. This is the same even when the brush base 67 of the forward / reverse switching unit 65 is switched to the reverse rotation position as shown in FIG. 10.

[0039] In this way, the hammer drill 1 of the above embodiment accommodates, within the front housing 2, the motor 4 including the stator 13 and rotor 14, and the output section 5 which is operated by driving the motor 4, and is also provided with a brush base 67 having a carbon brush 76 which abuts against the commutator 15 provided on the rotor 14, and a conductive spiral spring 77 which urges the carbon brush 76 towards the commutator 15. In addition, a fan 46 is provided on the rotating shaft 16 of the rotor 14, and the rear housing 3 is formed with a rear intake port 44 that draws in outside air as the fan 46 rotates, and an exhaust port 47 that expels the sucked in air, and the motor 4 is positioned in the middle of the air flow R flowing between the rear intake port 44 and the exhaust port 47, and a brush base 67 is positioned downstream of the rear intake port 44 in the air flow R. A non-conductive (here, made of resin) cover portion 105 that is disposed between spiral spring 77 and rear air intake port 44 and covers spiral spring 77 is removably provided on front housing 2 together with lead wire holder 85. According to this configuration, even if the spiral spring 77 that biases the carbon brush 76 is conductive, it is not necessary to shift the position of the rear air intake 44 in order to ensure an insulation distance between the rear air intake 44 and the spiral spring 77. In other words, the motor 4 and the carbon brush 76 can be efficiently cooled while ensuring an insulation distance between the rear air intake 44 and the spiral spring 77.

[0040] The housing consists of a front housing 2 and a rear housing 3 assembled to the front housing 2, with a cover portion 105 provided in the motor accommodating portion 12 of the front housing 2 and a rear air intake 44 provided in the rear housing 3. Therefore, the cover portion 105 can be easily attached to the motor accommodating portion 12 before the rear housing 3 is attached. The front housing 2 accommodates a motor 4 and an output portion 5 , and the rear housing 3 has a handle portion 41 . Therefore, the risk of dust and the like generated by the operation of the output portion 5 being sucked in through the rear intake port 44 on the handle portion 41 side is reduced. The brush base 67 can be rotated around the commutator 15 to switch the position of the carbon brush 76 relative to the commutator 15 between a forward rotation position and a reverse rotation position of the rotor 14, and the cover portion 105 covers the range of movement of the spiral spring 77 that accompanies the rotation of the brush base 67. Therefore, even if the brush base 67 is switched between forward and reverse directions, an insulation distance between the rear air intake port 44 and the spiral spring 77 can always be ensured.

[0041] The output unit 5 is provided in the front housing 2, the motor 4 is accommodated behind the output unit 5 with the rotating shaft 16 facing in the fore-and-aft direction, the carbon brushes 76 are arranged in pairs on the left and right sides of the brush base 67, and the rear air intakes 44 are provided on the left and right sides of the rear housing 3. Therefore, the left and right carbon brushes 76 can be efficiently cooled by the air sucked in through the left and right rear air intake ports 44. A lead wire holder 85 for holding lead wires 81 to 83 drawn out from the motor 4 is detachably provided on the front housing 2, and a cover portion 105 is provided on the lead wire holder 85. Therefore, the cover portion 105 can be easily attached to and detached from the front housing 2 by utilizing the lead wire holder 85 . The lead wire holder 85 is provided with a fitting piece 89 for preventing interference between the held lead wires 81 to 83 and the carbon brush 76 and the spiral spring 77 . Therefore, the cover portion 105 can be easily provided by utilizing the fitting piece 89 .

[0042] The biasing member is a spiral spring 77 . Therefore, the carbon brush 76 can be biased against the commutator 15 with a constant tension at all times. An upper air intake port 45 is provided on the upper surface of the rear housing 3. Therefore, the volume of the airflow R can be increased. The output unit 5 has a rotation mechanism that rotates a tool holder 20 that holds a bit B in accordance with the rotation of the rotation shaft 16, and a striking mechanism that strikes the bit B in accordance with the rotation of the rotation shaft 16. Therefore, in the hammer drill 1 having a rotation mechanism and an impact mechanism, the motor 4 and the carbon brushes 76 can be efficiently cooled while ensuring an insulation distance between the rear intake port 44 and the spiral spring 77.

[0043] Modifications of the present disclosure will be described below. The shape of the cover portion is not limited to that of the above embodiment. For example, the cross section of the cover portion may be L-shaped instead of arc-shaped. The cover portion may be attached to the fitting piece as a separate member. The cover portion does not have to be large enough to cover the entire range of movement of the spiral spring between the forward rotation position and the reverse rotation position, and multiple cover portions may be provided at positions to cover the spiral spring in the forward rotation position and the spiral spring in the reverse rotation position, respectively. The cover portion does not have to be formed contiguous with the fitting piece of the lead wire holder, but may be formed contiguous with the ring portion of the lead wire holder. The shape of the lead wire holder can also be modified as appropriate. For example, the shape and size of the ventilation portion of the fitting piece may be changed. The ventilation portion need not be present. The structure for attaching and detaching the ring portion to the bearing holding portion can also be modified. The shapes of the lead wire holding portion and the locking piece can also be modified. The two electrical components connected by the lead wire are not limited to a motor and a switch. The two electrical components may be, for example, a motor and a controller. The cover member does not have to be provided on the lead wire holder. The cover member may be provided independently on the bearing holding portion or the motor accommodating portion so as to be detachable therefrom. The shape of the brush base can also be modified as appropriate. For example, the operation protrusion may be provided on either the left or right side instead of the top, and may protrude from a window provided on the side of the housing. The biasing member is not limited to a spiral spring, but a leaf spring or a coil spring may also be used.

[0044] The configuration of the hammer drill is not limited to that of the above embodiment. For example, the number and positions of the coil springs in the vibration-proof mechanism can be changed as appropriate. Elastic members other than coil springs can also be used. However, the vibration-proof mechanism does not have to be provided. Therefore, the housing may have a structure that is not divided into front and rear portions. The selectable operation modes are not limited to three. The position of the switch knob can also be changed as needed. The impact operation may be a structure in which a piston reciprocates inside a fixed cylinder instead of a piston cylinder. A structure in which a striker directly strikes the bit without an impact bolt may be used. The impact operation may be a structure using a crank mechanism instead of a boss sleeve. There may be only one clutch. The power tool is not limited to the hammer drill of the above embodiment, and the present disclosure can be applied to other power tools such as an electric hammer and an electric drill. [Explanation of symbols]

[0045] 1 hammer drill, 2 front housing, 3 rear housing, 4 motor, 5 output section, 6 switch, 7 vibration isolation mechanism, 8 motor housing, 9 outer housing, 10 inner housing, 11 connection section, 12 motor housing section, 13 stator, 14 rotor, 16 rotating shaft, 17 front cylinder section, 18 rear cylinder section, 20 tool holder, 40 outer cylinder section, 41 handle section, 44 rear air intake, 45 upper air intake, 4 6··Fan, 47··Exhaust port, 50··Rubber sleeve, 51··Coil spring, 60··Bearing holder, 61··Arm, 65··Forward / reverse switching unit, 66··Unit base, 67··Brush base, 75··Brush holder, 76··Carbon brush, 77··Spiral spring, 81~83··Lead wire, 85··Lead wire holder, 86··Ring, 87··Support plate, 89··Mating piece, 89a··Ventilation section, 105··Cover, B··Bit, R··Air flow.

Claims

1. The housing contains a motor including a stator and a rotor, and an output unit that operates by the drive of the motor, and also includes a brush holding member having a brush that contacts a commutator provided on the rotor, and a conductive biasing member that biases the brush toward the commutator, A fan is provided on the rotating shaft of the rotor, and the housing has an intake port for drawing in outside air as the fan rotates and an exhaust port for discharging the drawn-in air, and the motor is positioned in the middle of the airflow between the intake port and the exhaust port, and the brush holding member is positioned downstream of the intake port in the airflow, in an electric power tool, A power tool characterized in that a non-conductive cover member is detachably provided in the housing, positioned between the biasing member and the air intake port and covering the biasing member.

2. The power tool according to claim 1, wherein the housing comprises a first housing and a second housing assembled to the first housing, the cover member is provided on the first housing, and the air intake port is provided on the second housing.

3. The power tool according to claim 2, characterized in that the first housing houses the motor and the output unit, and the second housing has a handle.

4. The brush holding member can switch the position of the brush relative to the commutator between the forward rotation position and the reverse rotation position of the rotor by rotating it around the commutator. The power tool according to any one of claims 1 to 3, characterized in that the cover member covers the range of movement of the biasing member accompanying the rotation of the brush holding member.

5. The power tool according to any one of claims 1 to 3, characterized in that the output unit is provided at the front of the housing, the motor is housed behind the output unit with its rotation axis facing in the front-rear direction, the brushes are arranged in pairs on the left and right sides of the brush holding member, and the air intake ports are provided on the left and right sides of the housing.

6. The power tool according to any one of claims 1 to 3, characterized in that a wiring retaining member for holding wiring drawn out from the motor is detachably provided in the housing, and the cover member is provided on the wiring retaining member.

7. The power tool according to claim 6, wherein the wiring holding member is provided with a protective portion to prevent interference between the held wiring and the brush and the biasing member, and the cover member is provided on the protective portion.

8. The power tool according to any one of claims 1 to 3, characterized in that the biasing member is a coil spring.

9. The power tool according to claim 5, characterized in that a second air intake port is provided on the upper surface of the housing.

10. The power tool according to any one of claims 1 to 3, characterized in that the output unit has a rotation mechanism that rotates a final output shaft that holds the tip tool in conjunction with the rotation of the rotation shaft, and a striking mechanism that strikes the tip tool in conjunction with the rotation of the rotation shaft.

Images