power tools

Abstract

To provide an electric power tool which can reduce the possibility of noise generation.SOLUTION: A hammer drill as an example of an electric power tool has a motor housing, a field and armature for a motor, two brushes, and a brush holder unit (BHU). The field is fixed to the motor housing and has a plurality of field coils. The armature is rotatable relative to the field and has a commutator. Each brush can come into contact with the commutator. The BHU holds each brush. The BHU comprises: two contact rails 82 connected with corresponding field coils; two first terminals 92 capable of being brought into contact with either of the contact rails 82; two second terminals 94 electrically connected with the corresponding brushes; and a choke coil 96 interposed between the first terminals 92 and the second terminals 94.SELECTED DRAWING: Figure 11

Description

Technical Field

[0001] The present invention relates to power tools such as hammer drills.

Background Art

[0002] As shown in Japanese Patent No. 6309881 (Patent Document 1), a hammer drill using an electric motor is known. "

Prior Art Document

Patent Document

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the above hammer drill, noise may be generated due to electromagnetic interference (EMI: Electro Magnetic Interference) caused by rectification of the electric motor. Therefore, in power tools, a technology for reducing the possibility of noise generation is expected.

Means for Solving the Problems

[0005] This specification discloses a power tool. The power tool may have a housing and a field fixed to the housing and having a field coil. The power tool may have an armature that is rotatable with respect to the field and has a commutator. The power tool may include a brush that can contact the commutator. The field coil and the brush may be electrically connected to each other via a choke coil.

Effects of the Invention

[0006] According to the power tool of the present disclosure, the possibility of noise generation is reduced. [Brief explanation of the drawing]

[0007] [Figure 1] This is a left side view of the hammer drill related to this disclosure. [Figure 2] This is a rear view with the cover open, as shown in Figure 1. [Figure 3] This is a central longitudinal section of Figure 2. [Figure 4] Figure 2 is a partially exploded perspective view. [Figure 5] Figure 3 is a perspective view including the cross-section along line AA. [Figure 6] Figure 3 is a perspective view including the cross-section along line BB. [Figure 7] Figure 2 is an exploded perspective view of the BHU from the rear. [Figure 8] Figure 2 is an exploded perspective view of the BHU as seen from the front. [Figure 9] Figure 7 is an enlarged perspective view of the fixed housing and a portion of the front end of the terminal section and lead wire terminal section of the contact rail in the BHU. [Figure 10] Figure 7 is an exploded perspective view of the BHU, showing the terminal sections for connecting each brush. [Figure 11] Figure 7 is a perspective view of the BHU, showing the terminal sections for connecting each brush and each contact rail. [Figure 12] Figure 11 is a cross-sectional view along line CC. [Figure 13] Figure 12 is a cross-sectional view along the DD line. [Modes for carrying out the invention]

[0008] The hammer drill according to this disclosure may have a housing, a field fixed to the housing and having a field coil, and an armature rotatable relative to the field and having a commutator. The hammer drill may have two brushes, each capable of contacting the commutator. The hammer drill may have a brush holder unit that holds each brush. The brush holder unit may have a fixed housing and two contact rails held in the fixed housing and electrically connected to the field coil. The brush holder unit may have a movable housing that holds the two brushes and moves relative to the fixed housing. The brush holder unit may have two first terminals held in the movable housing and capable of contacting either of the contact rails as the movable housing moves. The brush holder unit may have two second terminals held in the movable housing and electrically connected to the corresponding brushes. The brush holder unit may have a choke coil interposed between at least one first terminal and at least one second terminal. In this case, the generation of noise is suppressed.

[0009] The brush holder unit may have a terminal holding member that holds one first terminal and one second terminal. The first and second terminals may be held in a movable housing via the terminal holding member. In this case, the first and second terminals are provided in a cohesive and easy-to-handle manner. The first terminal, the second terminal, and the terminal retaining member may be integrally molded. In this case, the first terminal and the second terminal are more firmly attached to the terminal retaining member. The terminal retaining member may have a recess for inserting a choke coil. In this case, the terminal retaining member also serves as the case for the choke coil, and these components are provided in a compact manner. A hole may be provided in a portion between the first terminal and the second terminal in the terminal holding member. In this case, by cutting the connection body of the first terminal and the second terminal through the hole, the first terminal and the second terminal can be formed more easily. Also, a mode without a choke coil can be selected more easily. The first terminal may have an enclosing shape surrounding the contact rail. In this case, the contact property of the first terminal with respect to the contact rail becomes better, and chatter is suppressed. An arch-shaped arch portion may be provided at a portion of the contact rail that contacts the first terminal. In this case, The first terminal makes more reliable contact with the corresponding contact rail. This more reliable contact suppresses chattering when the first terminal receives the arch. The first terminal may have a guide portion that spreads outward. In this case, the first terminal can receive the contact rail more smoothly. The contact rail may extend in the direction of the rotation axis of the armature. In this case, a larger space is secured inside the contact rail, or the outer shape of the contact rail becomes more compact. The contact rail may be made of brass. In this case, the contact rail becomes stronger against at least one of friction and heat. The contact rail may have an arc-shaped rail portion and a terminal portion that intersects the rail portion. Also, the terminal portion may be electrically connected to the field coil. In this case, the contact rail can be installed more easily.

[0010] The fixed housing has a box-shaped portion, and the tip of the terminal portion may enter the box-shaped portion. In this case, the terminal portion is protected. The tip of the terminal portion does not have to protrude from the tip of the box-shaped portion. In this case, the terminal portion is protected. Also, the terminal portion is more reliably connected to the member at the connection destination by the guidance of the box-shaped portion. The movable housing may have a flat surface or a continuous curved surface on the side opposite to the fixed housing. In this case, wind or the like is guided more smoothly. The fixed housing may be attached to the housing. In this case, the brush holder unit is arranged more efficiently with respect to the motor. The housing may include a motor housing and an outer housing. The motor housing may hold a field. The outer housing may be movable with respect to the motor housing. A telescopic member may be interposed between the motor housing and the outer housing. In this case, at least one of shock and vibration is alleviated.

[0011] Hereinafter, embodiments of the present disclosure and modifications thereof will be described as appropriate based on the drawings. The front-rear, up-down, left-right in the embodiments and modifications is defined for convenience of explanation, and may change depending on the working situation and the state of the moving members, etc. Note that the present disclosure is not limited to the following embodiments and modifications.

[0012] FIG. 1 is a left side view of a hammer drill 1 which is an example of a power tool (percussion tool) according to the present disclosure. FIG. 2 is a rear lid view of FIG. 1. FIG. 3 is a central longitudinal sectional view of FIG. 2. FIG. 4 is a partially exploded perspective view of FIG. 2. FIG. 5 is a perspective view including a cross section taken along line A-A of FIG. 3. FIG. 6 is a perspective view including a cross section taken along line B-B of FIG. 3. The hammer drill 1 includes a housing 2, a power unit 4, a trigger unit 5, a power cable 6, an intermediate unit 7, an output unit 8, and an auxiliary handle 10. The axial direction of the power unit 4 is the front-rear direction. The axial direction of the output unit 8 is the front-rear direction.

[0013] The housing 2 directly or indirectly holds various members. The housing 2 includes a gear housing 20, a motor housing 22, and an outer housing 24.

[0014] The gear housing 20 is cylindrical. The gear housing 20 extends in the front-rear direction. The gear housing 20 holds the intermediate unit 7. The gear housing 20 has multiple exhaust ports 20V. Each exhaust port 20V is located on the lower left and lower right sides of the gear housing 20.

[0015] The motor housing 22 is cylindrical. The motor housing 22 extends in the front-to-back direction.

[0016] The rear of the outer housing 24 forms the outer casing of the handle portion 26. The handle portion 26 extends in the vertical direction. The direction roughly perpendicular to the front-rear and vertical directions is the left-right direction. The outer housing 24 is split in half horizontally. The left side of the outer housing 24 has multiple screw bosses 27. Each screw boss 27 contains a screw for joining the left and right sides of the outer housing 24 together as a single unit. The outer housing 24 has a plurality of air intake ports 24A. Each air intake port 24A is located in the lower left and lower right parts of the central part of the outer housing 24 in the front-to-back direction.

[0017] The dimensions in the vertical, horizontal, and vertical directions of the central part 22C of the motor housing 22 are smaller than the dimensions in the vertical, horizontal, and vertical directions of the front part 22F of the motor housing 22. The dimensions in the vertical, horizontal, and vertical directions of the rear portion 22B of the motor housing 22 are smaller than the dimensions in the vertical, horizontal, and vertical directions of the central portion 22C of the motor housing. The central part 22C of the motor housing and the rear part 22B of the motor housing hold the power unit 4.

[0018] The upper part of the outer housing 24 is positioned outside the central part 22C and the rear part 22B of the motor housing. An expandable member 28 is interposed between the front end of the outer housing 24 and the rear end of the front part 22F of the motor housing. The expandable member 28 is elastic. The expandable member 28 is a bellows. The outer housing 24 is movable in the front-rear direction relative to the motor housing 22. As the outer housing 24 moves, the telescopic member 28 extends and retracts. The outer housing 24 is positioned behind the motor housing 22 when the telescopic member 28 is at its natural length or closest to its natural length (normal state). The outer housing 24 moves forward relative to the motor housing 22 from the normal state (forward state). The interposition of such expandable member 28 suppresses vibrations generated in the power unit 4, intermediate unit 7, output unit 8, etc.

[0019] An elongated hole 24S is provided on the upper surface of the outer housing 24. The elongated hole 24S extends to the left and right. An outer rib 24B is formed on the inner surface of the outer housing 24. The outer rib 24B protrudes inward relative to the surrounding portion. The outer rib 24B is positioned above the handle portion 26 in the right outer housing 24. The outer rib 24B extends in the front, back, left, and right directions. The outer rib 24B may also be positioned at the upper end of the handle portion 26, the left outer housing 24, or other parts. Furthermore, a central rib 24J is formed on the inner surface of the outer housing 24 (Figure 5). The central rib 24J protrudes inward relative to the surrounding portion. The central rib 24J is positioned above the handle portion 26 in the left outer housing 24. The central rib 24J extends in the front, back, left, and right directions. The central rib 24J is positioned to the left of the outer rib 24B. The central rib 24J faces the outer rib 24B. The central rib 24J may also be positioned at other locations, such as the upper end of the handle portion 26, the portion not facing the outer rib 24B, and the right outer housing 24.

[0020] The power unit 4 includes a motor 29, a plurality (2) of brushes 30, a brush holder unit (BHU) 31, and a fan 32. Motor 29 is electric. The motor 29 has a field 33 (stator) and an armature 34 (rotor). The field 33 has a field core 35 and a plurality of field coils 36. The field core 35 is cylindrical. The field core 35 is fixed to the housing 2. Each field coil 36 is wound around a plurality of projections on the inner surface of the field core 35. The armature 34 comprises a motor shaft 40, an armature core 42, a plurality of armature coils 44, and a commutator 45. The motor shaft 40 extends in the front-rear direction. The motor shaft 40 has a pinion gear portion 40G at its front end (Figure 1). The armature core 42 is fixed to the center of the motor shaft 40 in the front-rear direction. The armature core 42 has a plurality of slots. Each armature coil 44 is wound around the corresponding slot of the armature core 42. The commutator 45 is cylindrical. The commutator 45 has a plurality of conductive portions. Each conductive portion is arranged in the circumferential direction of the motor shaft 40. The armature coils 44 are electrically connected to each conductive portion in a predetermined manner.

[0021] The rear end of the motor shaft 40 is rotatably supported by a rear bearing 46. The rear bearing 46 is held within the rear end of the rear portion 22B of the motor housing. A commutator 45 is positioned between the rear bearing 46 and the armature core 42. A left opening 22L is provided in the portion of the rear portion 22B of the motor housing to the left of the commutator 45. A right opening 22R is provided in the portion of the rear portion 22B of the motor housing to the right of the commutator 45. The front end of the motor shaft 40 is rotatably supported by a front bearing (not shown). The front bearing is held within the rear end of the gear housing 20. The motor shaft 40 is rotatable around its own central axis.

[0022] Each brush 30 is made of carbon. A BHU 31 is positioned radially outward from the rear 22B of the motor housing. The BHU 31 is ring-shaped or cylindrical. The BHU 31 holds each brush 30.

[0023] The fan 32 is attached integrally with the motor shaft 40 on the circumferential outer side of the motor shaft 40. Fan 32 is a centrifugal fan. The fan 32 is positioned between the pinion gear section 40G and the armature 34. The fan 32 is located inside the front part 22F of the motor housing.

[0024] The trigger unit 5 includes a trigger switch 50 and a trigger 52. A trigger 52 is attached to the plunger used for switching the trigger switch 50. The trigger switch 50 is located on the handle section 26. The front of the trigger 52 is exposed from the front of the central part in the vertical direction of the outer housing 24. When the trigger 52 is operated backward by the user, the state of the trigger switch 50 is switched. The trigger 52 has a trigger projection 52P at its upper part that protrudes upward from the surrounding portion.

[0025] The power cable 6 is electrically connected to the trigger switch 50 and the motor 29.

[0026] The intermediate section 7 includes a power transmission mechanism 60 and a striking mechanism 62 (Figure 1). The power transmission mechanism 60 includes an intermediate shaft 64 and a cylinder 66. The intermediate shaft 64 extends in the front-rear direction. The rear end of the intermediate shaft 64 meshes with the pinion gear portion 40G of the motor shaft 40. The intermediate shaft 64 is rotatable around its own central axis. The cylinder 66 is cylindrical. The outer surface of the rear end of the cylinder 66 meshes with the front end of the intermediate shaft 64. The cylinder 66 is rotatable around its own central axis. The striking mechanism 62 has a pivot shaft 70 and a striking section 72. The pivot shaft 70 is connected to an intermediate shaft 64. The pivot shaft 70 is located radially outward from the intermediate shaft 64. The pivot shaft 70 extends upward from the intermediate shaft 64. The pivot shaft 70 oscillates with the rotation of the intermediate shaft 64, with its upper end moving back and forth. The striking section 72 includes a piston and a striker, as well as an air chamber between them. The striking section 72 extends back and forth. The rear part of the striking section 72 is located inside the cylinder 66. The striking section 72 is connected to the tip of the pivot shaft 70. The striking section 72 is movable in the back and forth direction with the oscillation of the pivot shaft 70.

[0027] The output unit 8 includes a tip tool holder 78 (Figure 1). The tip tool holder 78 is cylindrical. The tip tool holder 78 can be fitted with a tip tool such as a drill bit. The tip tool holder 78 is connected to the cylinder 66 at the front of the cylinder 66. The central axis of the tip tool holder 78 is in line with the central axis of the cylinder 66. The tip tool holder 78 is integral with the cylinder 66 and is rotatable around its own central axis. The front end of the striking portion 72 is adjacent to or inside the rear end of the tip tool holder portion 78, and is capable of striking the tip tool inside the tip tool holder portion 78. Furthermore, the rotation of the cylinder 66 by the power transmission mechanism 60 is transmitted to the tip tool via the tip tool holding part 78.

[0028] The auxiliary handle 10 is mounted to the outside of the gear housing 20. The auxiliary handle 10 is removable.

[0029] Figures 7 and 8 are exploded perspective views of the BHU31. The BHU31 includes an immovable housing 80, a plurality (2) of contact rails 82, a movable housing 84, a plurality (2) of elastic leaf springs 85, a plurality (2) of brush connection terminals 86, a plurality (2) of brush holders 88, and a plurality (2) of lead wires 89.

[0030] The fixed housing 80 includes a fixed housing body 80M, a rail holding portion 80R, a plurality (2) of protrusions 80C, and a plurality (4) of terminal holding portions 80T. The fixed housing body 80M is ring-shaped. The rail retaining portion 80R is formed at the rear of the fixed housing body 80M so as to be recessed forward. The rail retaining portion 80R is ring-shaped. Each projection 80C protrudes rearward from the rear end surface of the fixed housing body 80M. Each terminal holding portion 80T protrudes forward from the front of the fixed housing body 80M. Each terminal holding portion 80T has a hole 80H and a box-shaped portion 80B. The hole 80H extends in the front-to-back direction. The box-shaped portion 80B is located at the front end of the terminal holding portion 80T. The front and radially inward sides of the box-shaped portion 80B are open. The box-shaped portion 80B has four surfaces: a rear surface, a top surface, a bottom surface, and a radially outward surface. The box-shaped portion 80B is connected to the hole 80H at its rear surface. Some surfaces of the box-shaped portion 80B may be omitted. The fixed housing 80 is attached to the outside of the rear end of the central part 22C of the motor housing. The fixed housing body 80M is positioned behind the rear end surface of the central part 22C of the motor housing. Each terminal holding part 80T is positioned on the upper right, lower right, upper left, and lower left outer sides of the rear of the central part 22C of the motor housing.

[0031] Each contact rail 82 is made of metal (brass). Each contact rail 82 has a rail section 82R and a terminal section 82T. Hereinafter, the contact rail 82 located on the upper side may be called the upper contact rail 82U, and the contact rail 82 located on the lower side may be called the lower contact rail 82D. The rail section 82R is arc-shaped and semicircular. The rail section 82R is plate-shaped. The rail section 82R extends in the circumferential and longitudinal directions. A first arch section 82F is provided at the first end of the rail section 82R. A second arch section 82S is provided at the second end of the rail section 82R. The radius of curvature of the first arch section 82F is smaller than the radius of curvature of the other parts of the rail section 82R. The first arch section 82F bulges radially outward relative to the other parts of the rail section 82R. The second arch section 82S is formed similarly to the first arch section 82F. The first arch section 82F is provided at the left end of the upper contact rail 82U and at the right end of the lower contact rail 82U. The second arch section 82S is provided at the right end of the upper contact rail 82U and at the left end of the lower contact rail 82U. The second arch section 82S may be different from the first arch section 82F. At least one of the first arch section 82F and the second arch section 82S may be omitted. The terminal section 82T is in the shape of a bent plate. The terminal section 82T is connected in a continuous line to the middle section of the rail section 82R. The terminal section 82T intersects with the rail section 82R. As shown in Figure 9, each contact rail 82 is held in the fixed housing 80 by the terminal portion 82T being inserted into the hole 80H of the corresponding terminal holding portion 80T. The front end of each terminal portion 82T reaches the corresponding box-shaped portion 80B. The front end of each terminal portion 82T is located behind the front end of the box-shaped portion 80B. That is, the front end of each terminal portion 82T does not protrude from the corresponding box-shaped portion 80B, but is recessed relative to the front end of the corresponding box-shaped portion 80B. On the other hand, the rail portion 82R is positioned in the rail holding portion 80R.

[0032] The front end of each terminal section 82T is protected by the corresponding box-shaped section 80B. The front end of each terminal section 82T is in contact with the terminal (not shown) of the corresponding field coil 36 and is electrically connected. Each terminal of each field coil 36 is held by a terminal plate (not shown). The fixed housing 80 and each contact rail 82 are mounted to the terminal plate by moving forward. At this time, each box-shaped portion 80B first comes into contact with the terminal plate, and each box-shaped portion 80B is guided by the terminal plate. Then, the front end of each terminal portion 82T makes contact with the corresponding terminal on the terminal plate. This contact between the front end of each terminal portion 82T and the terminal of the field coil 36, accompanied by such guidance, ensures that the contact is made more reliable.

[0033] The movable housing 84 includes a movable housing body 84M, a plurality (2) of brush holder holding parts 84H, a plurality (2) of terminal holes 84P, a plurality (2) of slits 84S, a lever part 84V, a rib 84B, a projection 84J, and a recessed part 84R. The movable housing body 84M is ring-shaped or cylindrical. Each brush holder holding portion 84H is formed to be recessed forward relative to the rear end surface of the movable housing body 84M. The rear end surface of the movable housing body 84M is divided into two arc shapes by each brush holder holding portion 84H. The rear surfaces connecting these rear end surfaces to the radial inner surface of the movable housing body 84M are inclined surfaces 84C. Each inclined surface 84C is flat or a continuous curved surface. Each inclined surface 84C narrows as it moves forward, getting closer to the other inclined surfaces 84C, that is, the gaps become narrower as it moves forward (forward narrowing). Each inclined surface 84C is shaped like a mortar. Each terminal hole 84P is drilled in the corresponding inclined surface 84C. Each terminal hole 84P is adjacent to the corresponding brush holder retaining portion 84H. Each slit 84S is arc-shaped. Each slit 84S is opened in the corresponding inclined surface 84C. The lever portion 84V protrudes radially outward from the upper part of the circumferential surface of the movable housing body 84M. Rib 84B protrudes radially outward from the lower rear end face of the movable housing body 84M. Rib 84B extends circumferentially. Rib 84B is adjacent to the right brush holder retaining portion 84H. In the illustration, rib 84B is adjacent to the right end of the outer rib 24B. In the illustration, rib 84B is located to the right rear of the outer rib 24B. The projection 84J protrudes downward from the lower circumferential surface of the movable housing body 84M. When viewed from the rear, the projection 84J is located on the opposite side of the lever portion 84V from the central axis of the movable housing body 84M. The projection 84J is adjacent to the rib 84B. The projection 84J is located to the left front of the rib 84B. The recessed portion 84R is formed in the front part of the movable housing body 84M so as to be a ring-shaped recess.

[0034] The movable housing 84 is rotatably connected to the fixed housing 80. The rail holding section 80R and the rail section 82R are fitted into the recessed section 84R. Furthermore, a corresponding protrusion 80C is placed inside each slit 84S. The upper part of the lever portion 84V protrudes from the upper surface of the outer housing 24. The lever portion 84V is inserted into the elongated hole 24S of the outer housing 24. The user can rotate the movable housing 84 relative to the fixed housing 80 by operating the upper part of the lever 84V left and right. The movable housing 84 is rotatable from a first position (as shown in the figure) where the lever 84V is located at the right end of the elongated hole 24S, to a second position where the lever 84V is located at the left end of the elongated hole 24S. Furthermore, the movable housing 84 may move relative to the fixed housing 80 in ways other than rotational movement. For example, the movable housing 84 may reciprocate by linear sliding relative to the fixed housing 80.

[0035] Each leaf spring 85 is made of metal (stainless steel). Each leaf spring 85 is plate-shaped. Each leaf spring 85 extends in the front-to-back direction. Each leaf spring 85 can be locked to a plurality of locking parts (not shown) arranged in an arc shape in the movable housing 84. By sequentially locking each leaf spring 85 to its corresponding locking part, a clicking sensation is provided to the rotational movement of the movable housing 84 relative to the fixed housing 80.

[0036] Figure 10 is an exploded perspective view of each brush connection terminal 86. Figure 11 is a perspective view of each brush connection terminal 86 and each contact rail 82. Figure 12 is a cross-sectional view of Figure 11 along line CC. Figure 13 is a cross-sectional view of Figure 12 along line DD. Each brush connection terminal section 86 includes a case 90 as a terminal holding member, a first terminal 92, a second terminal 94, and a choke coil 96.

[0037] The case 90 is made of synthetic resin. The case 90 is a curved plate shape that extends in the circumferential and front-to-back directions. The case 90 has a terminal holding portion 90T and a recess 90V. The terminal holding portion 90T has a radial hole 90H. The recess 90V is an inner curved surface and is provided adjacent to the terminal holding portion 90T. The recess 90V is recessed radially outward relative to the rest of the inner curved surface.

[0038] The first terminal 92 is held in the front portion of the hole 90H in the terminal holding portion 90T. The first terminal 92 is made of metal. The first terminal 92 protrudes forward from the terminal holding portion 90T. The front part of the first terminal 92 is exposed from the case 90. The front part of the first terminal 92 has a base 92B, a turn portion 92T, a tip portion 92E, a curved portion 92C, a plurality (2) first guide portions 92F, and a plurality (2) second guide portions 92S. The base portion 92B extends in the front-rear direction. The front end of the base portion 92B connects to the turn portion 92T. The turn section 92T is "U" shaped when viewed from above. The tip section 92E extends forward and backward. The front end of the tip section 92E connects to the turn section 92T. The tip section 92E and the base section 92B are aligned vertically and are parallel to each other. The distance between the tip section 92E and the base section 92B is approximately the same as the bulge dimensions of the first arch section 82F and the second arch section 82S in the rail section 82R. The curved section 92C is connected to the rear end of the tip section 92E. The curved section 92C is bent in a direction that approaches the rear end of the base section 92B. Note that the curved section 92C may be omitted. Two first guide portions 92F are provided for each brush connection terminal portion 86, positioned on the circumferential central side of the brush connection terminal portion 86 at the base portion 92B and on the circumferential central side of the brush connection terminal portion 86 at the tip portion 92E. Each first guide portion 92F protrudes circumferentially from the base portion 92B or the tip portion 92E. The spacing between each first guide portion 92F increases as it moves away from the base portion 92B or the tip portion 92E. Each first guide portion 92F spreads outward. Two second guide portions 92S are provided for each brush connection terminal portion 86, positioned at the circumferential end of the brush connection terminal portion 86 on the base portion 92B and at the circumferential end of the brush connection terminal portion 86 on the tip portion 92E. Each second guide portion 92S protrudes circumferentially from the base portion 92B or the tip portion 92E. The spacing between each second guide portion 92S increases as it moves away from the base portion 92B or the tip portion 92E. Each second guide portion 92S spreads outward.

[0039] The second terminal 94 is held in the front portion of the hole 90H in the terminal holding portion 90T. The second terminal 94 is made of metal. The second terminal 94 protrudes rearward from the terminal holding portion 90T. The rear of the second terminal 94 is exposed from the case 90.

[0040] The choke coil 96 has a core 96C and a winding 96L. Core 96C is made of ferrite (ceramics containing iron oxide). Core 96C is elongated in the circumferential direction. The 96L winding is wound around the 96C core. The choke coil 96 has a first coil terminal 96F and a second coil terminal 96S. The first coil terminal 96F is electrically connected to the first terminal 92 by soldering or the like. The second coil terminal 96S is electrically connected to the second terminal 94 by soldering or the like. The choke coil 96 is placed in the recessed 90V. Furthermore, the choke coil 96 may be interposed only between the pair of first terminals 92 and second terminals 94. Alternatively, the choke coil 96 may be positioned in other locations between the field coil 36 and the brush 30. For example, the choke coil 96 may be positioned on each contact rail 82.

[0041] The first terminal 92 and the second terminal 94 are originally a single terminal, as indicated by the dotted line at the connecting portion 92L in Figure 10. The terminal and the case 90 are integrally molded. In this case, the connecting portion 92L is located inside the hole 90H and is exposed from the case 90. If the choke coil 96 is not required, the terminal section 86 for connecting each brush is used as a single integrated terminal. On the other hand, if a choke coil 96 is required, part or all of the connecting portion 92L is removed by cutting or the like, and after the first terminal 92 and the second terminal 94 are separated, the first coil terminal 96F of the choke coil 96 is electrically connected to the first terminal 92, and the second coil terminal 96S is electrically connected to the second terminal 94. The integrated terminal, or the first terminal 92 and the second terminal 94, are more firmly attached to the case 90 by integral molding. Furthermore, accommodating the presence or absence of the choke coil 96 can be done more easily by simply selecting whether or not to cut the connecting portion 92L. Furthermore, the first terminal 92 and the second terminal 94 may be formed separately. Also, the first terminal 92, the second terminal 94, and the case 90 may be manufactured by a method other than integral molding.

[0042] Each brush connection terminal 86 is fixed within the recess 84R of the movable housing 84. Each brush connection terminal 86 is positioned at a location corresponding to the space between the rail portion 82R of each contact rail 82 in the circumferential direction. The second terminal 94 of each brush connection terminal section 86 is inserted into the terminal hole 84P of the corresponding movable housing 84.

[0043] Each brush holder 88 holds the corresponding brush 30. Each brush holder 88 includes a brush case 100, an elastic spiral spring 102, and a brush terminal 104. The brush case 100 holds the brush 30. The brush case 100 is held in the brush holder holding section 84H. The spiral spring 102 is held in the brush case 100. The spiral spring 102 pushes the brush 30 radially inward. The brush 30 is in contact with the commutator 45 on its radially inward surface. Each brush 30 passes through either the left opening 22L or the right opening 22R. The brush terminal 104 is electrically connected to the brush 30. The brush terminal 104 is electrically connected to the second terminal 94.

[0044] Each lead wire 89 has a lead wire body 89M and a lead wire terminal portion 89T. Each lead wire terminal portion 89T is made of metal and is in the shape of a bent plate. Each lead wire terminal portion 89T is electrically connected to the lead wire body 89M (the conductor inside its sheath). As shown in Figure 9, each lead wire terminal portion 89T is held in the fixed housing 80 by being inserted into the hole 80H of the corresponding terminal holding portion 80T. The front end of each lead wire terminal portion 89T reaches the corresponding box-shaped portion 80B. The front end of each lead wire terminal portion 89T is located behind the front end of the box-shaped portion 80B. That is, the front end of each lead wire terminal portion 89T does not protrude from the corresponding box-shaped portion 80B, but is recessed relative to the front end of the corresponding box-shaped portion 80B. The front end of each lead wire terminal section 89T is protected by the corresponding box-shaped section 80B. The front end of each lead wire terminal 89T is in contact with the terminal of the corresponding field coil 36, and is electrically connected to it. When the fixed housing 80 and each contact rail 82 are attached to the terminal plate, each box-shaped portion 80B first makes contact with the terminal plate, and each box-shaped portion 80B is guided onto the terminal plate. Then, the front end of each lead wire terminal portion 89T makes contact with the corresponding terminal on the terminal plate. This contact between the front end of each lead wire terminal portion 89T and the field coil 36 terminals, accompanied by such guidance, ensures that the contact is made more reliable. Furthermore, each lead wire body 89M is electrically connected to the power cable 6 or the trigger switch 50. Furthermore, each lead wire 89 does not necessarily have to be included as a component of BHU31.

[0045] When the outer housing 24 is in its normal state and the trigger 52 is not operated backward (trigger 52 is not operated), and the movable housing 84 is in the first position (as shown in the figure), the first terminal 92 of each brush connection terminal 86 is in contact with the first arch portion 82F of the corresponding contact rail 82. Each first arch portion 82F is surrounded by a base portion 92B, a turn portion 92T, a tip portion 92E, and a curved portion 82C (enclosure shape of the first terminal 92). When the movable housing 84 is rotated to the second position described above, each first terminal 92 moves away from the corresponding first arch portion 82F and approaches and contacts the adjacent second arch portion 82S. At this time, the second guide portion 92S of each first terminal 92 first receives the second arch portion 82S in the widened portion and guides the second arch portion 82S between the base portion 92B and the tip portion 92E. When the movable housing 84 is in the second position described above, each first terminal 92 is in contact with the corresponding second arch portion 82S. Each second arch portion 82S is surrounded by a base portion 92B, a turn portion 92T, a tip portion 92E, and a curved portion 82C (enclosure shape of the first terminal 92). Through at least one of the following: the enclosing shape of the first terminal 92, guidance by the second guide portion 92S, and the formation of the second arch portion 82S, each first terminal 92 makes more reliable contact with the corresponding contact rail 82. This more reliable contact suppresses chattering when the first terminal 92 receives the second arch portion 82S.

[0046] Furthermore, when the outer housing 24 is in its normal state and the movable housing 84 is rotated from the second position to the first position, each first terminal 92 moves away from the corresponding second arch portion 82S and approaches and contacts the adjacent first arch portion 82F. At this time, the first guide portion 92F of each first terminal 92 first receives the first arch portion 82F in the widened portion and guides the first arch portion 82F between the base portion 92B and the tip portion 92E. Through at least one of the following: the enclosing shape of the first terminal 92, guidance by the first guide portion 92F, and the formation of the first arch portion 82F, each first terminal 92 makes more reliable contact with the corresponding contact rail 82. This more reliable contact suppresses chattering when the first terminal 92 receives the first arch portion 82F.

[0047] The size of the radially inward space of the rail portion 82R of the contact rail 82 is larger due to the extension of the rail portion 82R in the circumferential and longitudinal directions (direction of the motor shaft 40) compared to the case where the rail portion 82R extends in the circumferential and vertical directions while maintaining the same radial size. Therefore, by widening the radially inward space of the BHU31 in accordance with the increased space, it becomes easier to guide the airflow from the fan32 into the motor29, resulting in improved cooling efficiency for the motor29. Furthermore, it becomes possible to install other structures in the expanded space. For example, the radially inward space of the ring-shaped or cylindrical BHU31 is expanded, and the internal space of the rear motor housing 22B is expanded accordingly. The holding structure for the rear bearing 46, which is located in this internal space, is then made more robust. More specifically, new ribs are provided to hold the rear bearing 46, the number of such ribs is increased, or the thickness of at least one of the ribs and the rear motor housing 22B is increased. Alternatively, the radial size of the rail section 82R is smaller than when the rail section 82R extends in the circumferential and vertical directions while the size of the space radially inside the rail section 82R remains the same. Thus, a more compact design is achieved.

[0048] Furthermore, when the outer housing 24 is in the normal state described above, and the movable housing 84 is in a position between the first position and the second position (intermediate position) during rotational movement, the projection 84J of the movable housing 84 is positioned behind the trigger projection 52P. Therefore, in this case, the user's backward operation of the trigger 52 is suppressed by the contact of the trigger projection 52P with the projection 84J. Furthermore, when the outer housing 24 is in the normal state described above and the movable housing 84 is in an intermediate position, the projection 84J of the movable housing 84 is located in front of the central rib 24J of the outer housing 24. Therefore, in this case, the forward movement of the outer housing 24 is suppressed by the contact of the central rib 24J with the projection 84J. If the movable housing 84 is not in an intermediate position, the projection 84J is located above the central rib 24J, so the suppression of the forward movement of the outer housing 24 is released, and the forward movement of the outer housing 24 is permitted.

[0049] Furthermore, when the outer housing 24 is in the normal state or the forward state described above, and the movable housing 84 is in the first position described above, and the trigger 52 is operated backward by the user, the projection 84J is positioned to the left of the trigger projection 52P. Therefore, at this time, the user's operation to move the movable housing 84 to the second position described above is suppressed by the contact of the projection 84J with the left side of the trigger projection 52P. On the other hand, when the outer housing 24 is in the normal state or the forward state described above, and the movable housing 84 is in the second position described above, and the trigger 52 is operated backward by the user, the projection 84J is positioned to the right of the trigger projection 52P. Therefore, at this time, the user's operation to move the movable housing 84 to the first position described above is suppressed by the contact of the projection 84J with the right side of the trigger projection 52P.

[0050] Furthermore, when the movable housing 84 is in the first position described above, and the outer housing 24 moves from the normal state to the forward state described above, the outer rib 24B approaches the rib 84B and is positioned to the right of the rib 84B. Therefore, at this time, the leftward operation of the lever portion 84V for moving the movable housing 84 to the second position described above is suppressed by the contact of the rib 84B with the outer rib 24B. On the other hand, when the outer housing 24 is in the normal state described above and the movable housing 84 is in the second position described above, the left end of the rib 84B is located to the upper right rear of the outer rib 24B. In this case, when the outer housing 24 moves from the normal state described above to the forward position described above, the outer rib 24B approaches the rib 84B and is located to the lower left of the rib 84B. Therefore, at this time, the rightward operation of the lever portion 84V for moving the movable housing 84 to the first position described above is suppressed by the contact of the rib 84B with the outer rib 24B.

[0051] In the BHU31, the brush 30 and brush holder 88 are arranged on the left and right sides. Therefore, the BHU31 is more compact in the vertical direction compared to the case where the brush 30 and brush holder 88 are arranged vertically. Furthermore, the BHU31 reduces the amount of downward protrusion. Consequently, the trigger unit 5 can be positioned closer to the central axis (work axis) of the output unit 8, improving work efficiency. Furthermore, the amount of upward and downward protrusion of the BHU31 is reduced. Consequently, the amount of movement of the outer housing 24 and the BHU31 held therein in the front-rear direction can be made larger compared to when the brush 30 and brush holder 88 are arranged vertically.

[0052] Next, an example of the operation of this hammer drill 1 will be explained. When the user operates the trigger 52 backward while the movable housing 84 is in the first position described above, the trigger switch 50 turns on, and power from the power cable 6 is supplied to the field coil 36 via a pair of lead wires 89, brushes 30, brush connection terminals 86, and contact rails 82. Each field coil 36 is electrically connected to the corresponding brush 30 via each brush connection terminal 86 and each contact rail 82. As a result, the armature 34 is rotated in the first rotational direction (forward rotation). The amount of rotation of the armature 34 corresponds to the amount the trigger 52 is operated backward. The choke coils 96 of each brush connection terminal 86 cut the high-frequency components of the power, suppress the generation of EMI, and suppress noise caused by high-frequency components. When the trigger 52 is operated backward, the user's operation to move the movable housing 84 to the second position described above is suppressed by the contact of the projection 84J with the left part of the trigger upper projection 52P. The user can switch the movable housing 84 from the first position to the second position by operating the lever portion 84V to the left, without operating the trigger 52 backward. During the switching process, backward operation of the trigger 52 is suppressed by the contact of the trigger upper projection 52P with the projection 84J. Also, forward movement of the outer housing 24 during the switching process is suppressed by the contact of the central rib 24J with the projection 84J. With the movable housing 84 in the second position described above, when the user operates the trigger 52 backward, the trigger switch 50 turns on, and power from the power cable 6 is supplied to the field coil 36 in the reverse direction, as the contact position of the brush connection terminal 86 with the contact rail 82 changes, causing each brush 30 to contact the commutator 45 in the reverse relationship compared to the first position. Each field coil 36 is electrically connected to the corresponding brush 30 via each brush connection terminal 86 and each contact rail 82. As a result, the armature 34 is rotated in the second rotation direction (reverse rotation). The amount of rotation of the armature 34 corresponds to the amount the trigger 52 is operated backward. The choke coil 96 of each brush connection terminal 86 cuts the high-frequency components of the power, suppresses the generation of EMI, and suppresses noise caused by high-frequency components. When the trigger 52 is operated backward, the user's movement of the movable housing 84 to the first position described above is suppressed by the contact of the projection 84J with the right side of the trigger projection 52P.

[0053] The rotation of the armature 34 causes the motor shaft 40 to rotate. The rotation of the motor shaft 40 is transmitted, after being reduced in speed, to the output unit 8, to which the end tool is attached, via the power transmission mechanism 60. The rotation of the motor shaft 40 is also appropriately converted into an impact force to strike the end tool by the impact mechanism 62. The workpiece is processed (operated) by the rotation of the output unit 8, which is accompanied by appropriate impacts. At least one of the vibrations and shocks generated during processing is mitigated by the forward and backward movement of the outer housing 24 and the interposition of the expandable / contractible member 28. When the outer housing 24 moves forward, the rotational movement of the movable housing 84 is suppressed by the contact of the rib 84B with the outer rib 24B.

[0054] Furthermore, as the motor shaft 40 rotates, the fan 32 rotates, drawing in air from each intake port 24A. The drawn-in air passes through the inside and outside of the motor 29 and other parts of the hammer drill 1, and exits from the exhaust port 20V. This airflow (wind) cools the internal mechanisms of the hammer drill 1, including the motor 29. In particular, since each inclined surface 84C of the movable housing 84 is flat or a continuous curved surface and also tapers towards the front, air can be smoothly guided into the motor 29. A portion of the air from each intake port 24A enters the motor housing 22 through the left opening 22L and the right opening 22R.

[0055] Furthermore, this disclosure is not limited to the above-described forms and their modifications, and may be further modified as appropriate, for example, as follows: The housing can be configured in various ways, such as the motor housing and gear housing being integrated, or at least one of these housings being further divided.

[0056] The power cable 6 may be replaced with a battery mounting section and a battery mounted thereon, allowing the device to be powered by battery power; the striking mechanism 62 may be omitted; the number of at least one of the various coils and lead wires may be increased or decreased; the number of various screws and screw holes may be increased or decreased; the arrangement of various protrusions and recesses may be changed; the contact rail 82 may be made of a material other than brass; and at least one of the various engaging parts and connecting parts, screw fastening parts, holding parts, and mounting parts may be changed to at least one of other structures and types. In short, the number, arrangement, presence or absence of installation, material, structure, type, etc., of at least one of the various components and parts may be changed as appropriate. Furthermore, this disclosure may also be applied to other types of hammer drills, or other power tools, gardening tools, power work machines, etc. [Explanation of symbols]

[0057] 1. Hammer drill (power tool), 2. Housing, 22. Motor housing, 24. Outer housing, 28. Telescopic member, 29. Motor, 30. Brush, 31. BHU (Brush holder unit), 33. Field, 34. Armature, 36. Field coil, 45. Commutator, 80. Fixed housing, 80B. Box-shaped part, 82. Contact rail, 82R. Rail part, 82T. Terminal part, 84. Movable housing, 84C. Inclined surface (flat surface, continuous curved surface), 90. Case (terminal holding member), 90H. Hole, 90V. Recess, 92. First terminal, 92F. First guide part (guide part), 92S. Second guide part (guide part), 94. Second terminal, 96. Choke coil.

Claims

1. Housing and It is fixed to the housing and has a field coil, An armature that is rotatable with respect to the field and has a commutator, Two brushes, each capable of contacting the commutator, A brush holder unit that holds each of the aforementioned brushes, It is equipped with, The aforementioned brush holder unit is Fixed housing and A first contact rail and a second contact rail are held in the fixed housing and electrically connected to the field coil, A movable housing that holds the two brushes and moves relative to the fixed housing, The movable housing holds two first terminals, which are capable of contacting the first and second contact rails, respectively, in response to the movement of the movable housing by the user's operation. The movable housing holds two second terminals which are electrically connected to the corresponding brushes, A first terminal holding member that holds one of the first terminals and the corresponding second terminal, and a second terminal holding member that holds the other of the first terminals and the corresponding second terminal, It has, A choke coil can be interposed between one of the first terminals and the corresponding second terminal, and between the other first terminal and the corresponding second terminal, and when the choke coil is interposed between one of the first terminals and the corresponding second terminal, the first terminal holding member holds the choke coil, and when the choke coil is interposed between the other first terminal and the corresponding second terminal, the second terminal holding member holds the choke coil. One of the first terminals and the corresponding second terminal are held in the movable housing via the first terminal holding member, and the other first terminal and the corresponding second terminal are held in the movable housing via the second terminal holding member. In the first terminal holding member, a hole is provided in the portion between the first terminal and the second terminal for separating the first terminal and the second terminal, which are integrated when the choke coil is not interposed, when the choke coil is interposed. In the second terminal holding member, a hole is provided in the portion between the first terminal and the second terminal for separating the first terminal and the second terminal, which are integrated when the choke coil is not interposed, when the choke coil is interposed. A power tool characterized by the following features.

2. The first terminal and the corresponding second terminal, which are integrated together, and the first terminal holding member are integrally molded, The other first terminal and the corresponding second terminal, which are integrated together, and the second terminal holding member are integrally molded. The power tool according to feature 1.

3. The first terminal holding member has a recess for inserting one of the choke coils, The second terminal holding member has a recess for inserting the other choke coil. The power tool according to claim 1 or 2.

4. One of the first terminals has an enclosure shape that surrounds the first contact rail, The other first terminal has an enclosure shape that surrounds the second contact rail. The power tool according to any one of claims 1 to 3.

5. The portion of the first contact rail that contacts the first terminal is provided with an arch-shaped arch portion that bulges out relative to the other portion of the first contact rail. An arched portion is provided in the portion of the second contact rail that contacts the first terminal, and which bulges out relative to the rest of the second contact rail. The power tool according to any one of claims 1 to 4.

6. The first terminal has a guide portion that extends outward. The power tool according to any one of claims 1 to 5.

7. The first contact rail extends in the direction of the rotation axis of the armature, The second contact rail extends in the direction of the rotation axis of the armature. The power tool according to any one of claims 1 to 6.

8. The first contact rail is made of brass, The second contact rail is made of brass. The power tool according to any one of claims 1 to 7.

9. The first contact rail has an arc-shaped rail portion and a terminal portion that intersects the rail portion. The second contact rail has an arc-shaped rail portion and a terminal portion that intersects the rail portion. The power tool according to any one of claims 1 to 8.

10. The terminal portion is electrically connected to the field coil. The power tool according to feature 9.

11. The aforementioned fixed housing has a box-shaped portion, The tip of the terminal portion is contained within the box-shaped portion. The power tool according to claim 9 or 10.

12. The tip of the terminal portion does not protrude from the tip of the box-shaped portion. The power tool according to feature 11.

13. The movable housing has a flat surface or a continuous curved surface on the side opposite to the fixed housing to smoothly guide the airflow. The power tool according to any one of claims 1 to 12.

14. The fixed housing is attached to the housing The power tool according to any one of claims 1 to 13.

15. The housing includes a motor housing and an outer housing. The motor housing holds the field, The outer housing is movable relative to the motor housing. The power tool according to any one of claims 1 to 14.

16. An expandable member is interposed between the motor housing and the outer housing. The power tool according to feature 15.

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