power tools

Abstract

To improve a safety device of an electric tool.SOLUTION: An electric tool is equipped with a motor 2, a final output shaft, a tool body 10, a detection device 5, and a brake device 6. The motor has a motor body portion 20 that includes a stator 21 and a rotor 23, and a motor shaft 25 that is extended from the rotor and can rotate around a first rotation axis A1. The final output shaft 3 is driven to rotate around a second rotation axis A2 by torque transmitted from the motor shaft. The tool body stores the motor and the final output shaft. The detection device is configured to detect a lock state of the final output shaft. The brake device is a mechanical brake device and is configured to directly act on the motor shaft and brake the motor shaft according to the detection of the lock state.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a power tool configured to rotationally drive a final output shaft. [Background technology]

[0002] During operation of a power tool such as a hammer drill, the final output shaft may become unable to rotate (also called a locked state or a blocked state) due to, for example, the bit bit becoming caught in the workpiece. In such a case, an excessive reaction torque may act on the tool body (housing), causing the tool body to rotate excessively around the rotation axis of the final output shaft (also called a kickback phenomenon). For this reason, for example, Patent Document 1 proposes a drill tool equipped with a safety device. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 4223584 Summary of the Invention [Problem to be solved by the invention]

[0004] In the safety device described above, when a locked state is detected, a structural member provided on the tool body and a structural member provided on the spindle frictionally engage with each other to brake the spindle. Because the rotational speed of the spindle, which is the final output shaft, is slower than the rotational speed of the motor, the spindle generates a relatively large torque. Therefore, a correspondingly large force is required to brake the rotating spindle.

[0005] SUMMARY OF THE INVENTION In view of the above circumstances, an object of the present invention is to provide an improved safety device for a power tool. [Means for solving the problem]

[0006] According to one aspect of the present disclosure, there is provided a power tool including a motor, a final output shaft, a tool body, a detection device, and a brake device. The motor has a motor body and a motor shaft. The motor body includes a stator and a rotor. The motor shaft extends from the rotor and is rotatable about a first rotation axis. The final output shaft is configured to be driven to rotate about a second rotation axis by torque transmitted from the motor shaft. The tool body houses the motor and the final output shaft. The detection device is configured to detect a locked state of the final output shaft. The brake device is a mechanical brake device. The brake device is configured to directly act on the motor shaft to brake the motor shaft in response to detection of the locked state.

[0007] In the power tool of this aspect, if the final output shaft becomes locked for some reason, the brake device, which is a safety device, brakes the motor shaft, thereby preventing the tool body from rotating excessively around the second axis. The brake device is configured to act directly on the motor shaft. Therefore, the motor shaft can be braked with a smaller force than when the brake device acts directly on the final output shaft, thereby preventing excessive rotation of the tool body. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a cross-sectional view of a hammer drill according to a first embodiment. [Figure 2] FIG. 2 is a partially exploded perspective view of the hammer drill. [Figure 3] FIG. 2 is a partially enlarged view of FIG. [Figure 4] FIG. 4 is a cross-sectional view taken along line IV-IV in FIG. [Figure 5] FIG. 5 is a cross-sectional view taken along line VV in FIG. 4, showing an initial state in which the brake device is not in operation. [Figure 6] 6 is a cross-sectional view corresponding to FIG. 5, showing a braking state in which the brake device is activated. [Figure 7]FIG. 10 is a partially exploded perspective view of a hammer drill according to a second embodiment. [Figure 8] FIG. [Figure 9] 9 is a cross-sectional view taken along line IX-IX in FIG. 8, showing an initial state in which the brake device is not in operation. [Figure 10] 10 is a cross-sectional view corresponding to FIG. 9, showing a braking state in which the brake device is activated. DETAILED DESCRIPTION OF THE INVENTION

[0009] In one or more embodiments of the present disclosure, the power tool may further include a transmission mechanism configured to transmit torque of the motor shaft to the final output shaft. The brake device may be disposed in the power transmission path between the motor and the transmission mechanism. This configuration allows the brake device to be disposed relatively close to the motor and to efficiently brake the motor shaft.

[0010] In one or more embodiments of the present disclosure, the power tool may further include a fan disposed between the motor body and the brake device in the extension direction of the first rotation axis and configured to rotate integrally with the motor shaft. The fan may be configured to generate an airflow that cools the motor body and the brake device. This configuration allows both the motor body and the brake device to be efficiently cooled.

[0011] In one or more embodiments of the present disclosure, the power tool may further include a solenoid operably coupled to the brake device. The solenoid may be configured to be activated in response to detection of a locked state to activate the brake device. This configuration allows the brake device to be quickly activated using the solenoid, which is a relatively inexpensive electrical component.

[0012] In one or more embodiments of the present disclosure, the brake device may include a first rotating member fixed to the motor shaft so as to be rotatable integrally with the motor shaft, which provides a streamlined configuration for directly acting on the motor shaft to brake the motor shaft.

[0013] In one or more embodiments of the present disclosure, a brake device may include a brake member, at least one first biasing member, and a pressing member. The brake member may be configured to brake the motor shaft by frictionally engaging with the first rotating member. The at least one first biasing member may be configured to bias the brake member in a direction away from the first rotating member. The pressing member may be configured to press the brake member against the first rotating member against the biasing force of the at least one first biasing member in response to detection of a locked state. This configuration realizes a rational configuration that can brake the motor shaft by moving the pressing member.

[0014] In one or more embodiments of the present disclosure, the brake member may have a second surface frictionally engageable with the first surface of the first rotating member. The pressing member may be configured to rotate about a fulcrum and move the brake member linearly relative to the first rotating member while the first surface and the second surface are substantially parallel. With this configuration, rotating the pressing member moves the brake member linearly, enabling the first surface and the second surface to effectively contact each other over a relatively wide range.

[0015] In one or more embodiments of the present disclosure, the brake device may include a second rotating member, at least one second biasing member, and a stopper. The second rotating member may be configured to be rotatable about a first rotation axis in response to rotation of the motor shaft and the first rotating member while frictionally engaging with the first rotating member. The at least one second biasing member may be configured to bias the second rotating member toward the first rotating member and frictionally engage with the first rotating member. The stopper may be normally disposed at a first position that does not interfere with the second rotating member, and may be configured to move to a second position that can interfere with the second rotating member in response to detection of a locked state, thereby stopping the rotation of the second rotating member. This configuration realizes a rational configuration that allows braking of the motor shaft by moving the stopper.

[0016] In one or more embodiments of the present disclosure, the at least one second biasing member may be at least one disc spring, which allows for the at least one second biasing member to exert a high load while occupying a small space.

[0017] In one or more embodiments of the present disclosure, the second rotating member may have a plurality of interference portions arranged at equal intervals in a circumferential direction around the first rotation axis. The stopper may be configured to stop rotation of the second rotating member by abutting against any one of the plurality of interference portions. This configuration reduces imbalance during rotation and realizes a second rotating member that can be quickly stopped by the stopper.

[0018] In one or more embodiments of the present disclosure, the motor may be a brushed motor. With this configuration, even if the rotor and motor shaft continue to rotate due to inertia after the power supply to the brushed motor is stopped, the brake device can brake the motor shaft to stop the rotation.

[0019] Hereinafter, several exemplary but non-limiting embodiments of the present disclosure will be described in detail with reference to the drawings. In the following embodiments, a hammer drill is exemplified as a power tool configured to rotationally drive a final output shaft.

[0020] [First embodiment] A hammer drill 1A according to a first embodiment will be described below with reference to Figures 1 to 6. The hammer drill 1A is a power tool capable of performing an operation of rotating a tool bit 91 around a predetermined drive axis A2 (hereinafter referred to as a rotation operation) and an operation of linearly driving the tool bit 91 along the drive axis A2 (hereinafter referred to as an impact operation). The hammer drill 1A is an example of a so-called rotary tool and also an example of an impact tool.

[0021] First, the schematic configuration of the hammer drill 1A will be described with reference to Fig. 1. As shown in Fig. 1, the outer shell of the hammer drill 1A is mainly formed by a tool body 10 and a handle 17 connected to the tool body 10.

[0022] The tool body 10 is a hollow body also referred to as a housing, and houses the spindle 3, motor 2, drive mechanism 4, etc. The spindle 3 is a long cylindrical member. One axial end of the spindle 3 is configured as a tool holder 32. The tool holder 32 is configured to coaxially and removably hold a tool bit 91. The long axis of the spindle 3 defines a drive axis A2 of the tool bit 91. The tool body 10 extends along the drive axis A2. The tool holder 32 is disposed within one end of the tool body 10 in the extension direction of the drive axis A2 (hereinafter also simply referred to as the drive axis direction).

[0023] The handle 17 is a long, hollow body that is gripped by the user. One axial end of the handle 17 is connected to the other end of the tool body 10 in the drive axis direction (the end opposite to where the tool holder 32 is disposed). The handle 17 extends in a direction intersecting (more specifically, approximately perpendicular to) the drive axis A2 so as to protrude from the other end of the tool body 10. A power cord 179 that can be connected to an external AC power source extends from the protruding end of the handle 17. The handle 17 has a trigger 171 that is pressed (pulled) by the user. When the trigger 171 is pressed, the motor 2 is energized, the drive mechanism 4 is driven, and an impact operation and / or a rotation operation is performed.

[0024] The detailed configuration of the hammer drill 1A will be described below. For convenience, in the following description, the direction in which the drive shaft A2 extends (the longitudinal direction of the tool body 10) is defined as the front-rear direction of the hammer drill 1A. In the front-rear direction, the side on which the tool holder 32 is arranged is defined as the front side of the hammer drill 1A, and the opposite side (the side to which the handle 17 is connected) is defined as the rear side. Furthermore, the direction perpendicular to the drive shaft A2 and roughly corresponding to the longitudinal direction of the handle 17 is defined as the up-down direction of the hammer drill 1A. In the up-down direction, the side on which the handle 17 is connected to the tool body 10 is defined as the upper side, and the protruding end side of the handle 17 is defined as the lower side. Furthermore, the direction perpendicular to the front-rear direction and the up-down direction is defined as the left-right direction.

[0025] First, the detailed configuration of the tool body 10 will be described.

[0026] As shown in FIG. 1 , the tool body 10 has a cylindrical front end portion. This cylindrical portion is referred to as a barrel portion 131. The rest of the tool body 10 other than the barrel portion 131 is formed in a generally rectangular box shape. The internal space of the tool body 10 is divided into two spaces by a partition wall 15 disposed inside the tool body 10 so as to intersect with the drive shaft A2. In this embodiment, the partition wall 15 is fitted into the inner periphery of the tool body 10 and is fixedly held by the tool body 10 (substantially immovable relative to the tool body 10). However, the partition wall 15 may be formed integrally with the tool body 10 (as a part of the tool body 10).

[0027] The space behind the partition 15 mainly accommodates the motor 2. The space in front of the partition 15 mainly accommodates the spindle 3 and the drive mechanism 4. Hereinafter, the part of the tool body 10 corresponding to the space behind the partition 15 (i.e., the space accommodating the motor 2) will be referred to as the rear housing section 11. Also, the part of the tool body 10 (including the barrel section 131) corresponding to the space in front of the partition 15 (i.e., the space accommodating the spindle 3 and the drive mechanism 4) will be referred to as the front housing section 13. Because the spindle 3 and the drive mechanism 4 basically require lubrication, a lubricant (e.g., grease) is placed inside the front housing section 13. The partition 15 substantially isolates the internal space of the rear housing section 11 (the space accommodating the motor 2) from the lubricant. As will be described in detail later, the partition 15 also functions as a support for bearings of various shafts.

[0028] The internal configuration (elements) of the tool body 10 will be described below.

[0029] 1, in addition to the motor 2, the rear housing section 11 also accommodates the fan 27, the brake device 6, and the solenoid 8. As described above, the front housing section 13 accommodates the spindle 3 and the drive mechanism 4. These elements will be described below in order.

[0030] In this embodiment, the motor 2 is a brushed motor driven by power supplied from an external AC power source. As shown in FIG. 1 , the motor 2 includes a motor main body 20 and a motor shaft 25. The motor main body 20 includes a stator 21 fixed to the tool body 10 and a rotor 23 disposed radially inside the stator 21. The motor shaft 25 extends from the rotor 23 and is configured to rotate integrally with the rotor 23. In this embodiment, the rotation axis A1 of the motor shaft 25 extends directly below and parallel to the drive shaft A2. An imaginary plane P including the drive shaft A2 and the rotation axis A1 passes through the substantial center of the hammer drill 1A in the left-right direction and extends in the up-down direction.

[0031] The motor shaft 25 is supported by two bearings 251, 252 to be rotatable around the rotation axis A1 relative to the tool body 10. The front bearing 251 is supported by the partition wall 15. The rear bearing 252 is supported by the rear end of the tool body 10 (more specifically, by the motor housing that accommodates the motor body 20 in the rear accommodating section 11). The front end of the motor shaft 25 penetrates the partition wall 15 and protrudes into the front accommodating section 13. A drive gear 461 is fixed to the portion protruding into the front accommodating section 13.

[0032] The fan 27 is fixed to a portion of the motor shaft 25 between the motor main body 20 and the front bearing 251 (partition wall 15). More specifically, the fan 27 is disposed in front of and adjacent to the motor main body 20. The fan 27 rotates integrally with the motor shaft 25 to generate an airflow for cooling the motor 2.

[0033] The brake device 6 is disposed between the motor 2 and the drive mechanism 4 in the power transmission path. More specifically, the brake device 6 is disposed between the motor main body 20 and the bearing 251 in the extending direction of the motor shaft 25 (i.e., the front-rear direction). Even more specifically, the brake device 6 is disposed between the fan 27 and the bearing 251 (partition wall 15) (i.e., on the opposite side of the fan 27 from the motor main body 20). Although detailed illustration is omitted, in this embodiment, an air intake port is provided at the rear of the tool main body 10 (rear housing 11), and an exhaust port is provided around the brake device 6. Therefore, air that flows into the tool main body 10 from the air intake port in response to the rotation of the fan 27 flows forward inside the rear housing 11, cooling the motor 2 and the brake device 6, and then flows out from the exhaust port. In this manner, in this embodiment, an arrangement that efficiently cools the motor 2 and the brake device 6 is realized.

[0034] The brake device 6 is configured to be actuated by a solenoid 8 to brake the motor shaft 25 if the spindle 3 becomes unable to rotate (locked) for some reason. The solenoid 8 is disposed above the motor 2 inside the rear housing portion 11. The brake device 6 and the solenoid 8 will be described in detail later.

[0035] The spindle 3 is the final output shaft of the hammer drill 1A. As shown in FIG. 1 , the spindle 3 is disposed in the front housing 13 and supported rotatably around the drive axis A2 relative to the tool body 10. The front half of the spindle 3 forms a tool holder 32. A tool bit 91 is inserted into the front end of the tool holder 32 so that its longitudinal axis coincides with the drive axis A2. The tool holder 32 holds the tool bit 91 in a state where it is permitted to move axially relative to the tool holder 32 but is restricted from rotating about its axis. The rear half of the spindle 3 forms a cylinder 33 that slidably holds a piston 413 (described later).

[0036] The drive mechanism 4 is operably connected to the motor 2 (motor shaft 25) and configured to drive the tool bit 91 using power from the motor 2. In this embodiment, the drive mechanism 4 includes an impact mechanism 41 configured to perform an impact operation and a rotation transmission mechanism 46 configured to perform a rotation operation. The impact mechanism 41 is configured to convert the rotational motion of the motor shaft 25 into linear motion and transmit the linear motion to the impact element, thereby driving the tool bit 91 linearly along the drive axis A2. The rotation transmission mechanism 46 is configured to transmit the torque of the motor shaft 25 to the spindle 3, thereby driving the tool bit 91 to rotate about the drive axis A2.

[0037] Although detailed illustrations and descriptions are omitted, in this embodiment, the impact mechanism 41 has a swinging member that swings back and forth in response to the rotation of the motor shaft 25, causing the piston 413 to reciprocate along the drive axis A2 within the cylinder 33. The impact bolt 415 strikes the tool bit 91 in response to the reciprocating movement of the piston 413, thereby linearly driving the tool bit 91. The rotation transmission mechanism 46 includes a drive gear 461 of the motor shaft 25, a driven gear 463 fixed to the outer periphery of the cylinder 33, and a plurality of gears operatively connected to these gears. The rotation transmission mechanism 46 rotates the spindle 3 (tool holder 32) in response to the rotation of the motor shaft 25. Note that the impact mechanism 41 and the rotation transmission mechanism 46 may each have any known configuration different from the above-described example.

[0038] In this embodiment, the hammer drill 1A has three operation modes: an impact mode (hammering only) in which only an impact operation is performed, a rotation mode (rotation only) in which only an impact operation is performed, and a rotation impact mode (hammering with rotation) in which an impact operation and an impact operation are performed simultaneously. Although detailed illustrations and descriptions are omitted, the drive mechanism 4 operates according to the operation mode selected by the user via the operating member.

[0039] The internal configuration (elements) of the handle 17 will be described below.

[0040] A trigger 171 is disposed at the upper end of the handle 17. A switch 172 is disposed inside the handle 17 adjacent to the rear side of the trigger 171. The switch 172 is normally kept off and is configured to be turned on when the trigger 171 is pressed.

[0041] A controller (control unit) 5 is disposed below the switch 172 in the handle 17. Although not shown in detail, the controller 5 includes a control circuit 51 mounted on a circuit board, an acceleration sensor 53, etc. The acceleration sensor 53 is configured to output a signal indicating the detected acceleration to the control circuit 51.

[0042] The controller 5 is electrically connected to the switch 172, the solenoid 8, and the like via electric wires (not shown). In this embodiment, the control circuit 51 of the controller 5 drives the motor 2 when the switch 172 is turned on. Furthermore, as will be described in detail later, the control circuit 51 is configured to start the solenoid 8 and operate the brake device 6 based on the detection result of the acceleration sensor 53.

[0043] The braking device 6 will be described in detail below.

[0044] As shown in FIGS. 2 to 5, the braking device 6 includes a brake rotor 61, a braking member 63, a biasing member 65, and a pressing member 67.

[0045] The brake rotor 61 is fixed to the motor shaft 25 between the fan 27 and the bearing 251, and rotates integrally with the motor shaft 25 around the rotation axis A1. The brake rotor 61 includes a sleeve 611 fixed to the motor shaft 25, and a disk-shaped disc portion 615 that protrudes radially outward from the sleeve 611. A front surface 617 of the annular outer periphery of the disc portion 615 is disposed so as to be approximately perpendicular to a straight line extending in the front-to-rear direction. The brake rotor 61 is formed of metal (for example, iron).

[0046] The brake member 63 is disposed in front of the brake rotor 61 (between the brake rotor 61 and the bearing 251). The brake member 63 is disposed so as to be movable linearly in the front-to-rear direction relative to the motor shaft 25 and the brake rotor 61. In this embodiment, the brake member 63 is an annular member having an opening in the center as a whole, and is disposed around the motor shaft 25. The brake member 63 is configured to brake the motor shaft 25 by frictionally engaging with the brake rotor 61, and includes a backing plate 631 and a friction material 636.

[0047] The receiving plate 631 includes an annular central portion and a plurality of protrusions 634 protruding radially outward from the central portion. The protrusions 634 are spaced apart from one another in the circumferential direction around the rotation axis A1. Three of the protrusions 634 (specifically, the lower, upper-left, and upper-right protrusions 634) are each provided with a guide hole 635. Meanwhile, three guide pins 151 are fixed to the partition wall 15 and protrude rearward, respectively, corresponding to the guide holes 635. Because the partition wall 15 is substantially immovable relative to the tool body 10, the guide pins 151 can be said to be fixed to the tool body 10. The guide pins 151 are slidably inserted into the guide holes 635 and stably guide the forward-rearward movement of the brake member 63 relative to the motor shaft 25 and the brake rotor 61. The receiving plate 631 is made of metal (e.g., iron).

[0048] The friction material 636 is formed in an annular shape. The friction material 636 has a size and shape that roughly matches the outer periphery of the brake rotor 61, and is fixed to the rear surface of the center of the backing plate 631. A rear surface 637 of the friction material 636 of the brake member 63 is disposed substantially parallel to and faces the front surface 617 of the brake rotor 61. The rear surface 637 is a friction surface that can frictionally engage with the front surface 617 of the brake rotor 61. Note that the brake member 63 may be formed as a single member made of metal (for example, iron), and the rear surface thereof can frictionally engage with the front surface 617 of the brake rotor 61.

[0049] The biasing members 65 are configured to bias the brake member 63 in a direction away from the brake rotor 61 (i.e., forward). In this embodiment, four biasing members 65 are arranged spaced apart from one another in the circumferential direction around the rotation axis A1. More specifically, the four biasing members 65 are arranged substantially symmetrically, with two on the left and two on the right side of the plane P (see FIG. 4 ). Furthermore, two on the upper and two on the lower side of the rotation axis A1. In this embodiment, a compression coil spring is used for the biasing members 65. The biasing members 65 are arranged in a compressed state between the tool body 10 (the spring receiving portion 113 of the rear housing portion 11) and the brake member 63 (the protrusion 634) in the front-rear direction, and constantly bias the brake member 63 forward relative to the tool body 10.

[0050] The pressing member 67 is operably connected to the solenoid 8, which will be described later, and is configured to move (more specifically, rotate) in response to activation of the solenoid 8, thereby pressing the brake member 63 against the brake rotor 61 against the biasing force of the biasing member 65. In this embodiment, the pressing member 67 is a frame-shaped member that is generally home base-shaped (pentagonal) overall, and has a shape that is approximately symmetrical with respect to the plane P. The pressing member 67 is also made of metal.

[0051] The pressing member 67 has two fulcrum protrusions 671 , two pressing protrusions 673 , and an engagement hole 675 .

[0052] Each fulcrum protrusion 671 is a protrusion that protrudes forward. When the fulcrum protrusion 671 is cut in a cross section perpendicular to the left-right direction, the cross section has a substantially semicircular shape. The two fulcrum protrusions 671 are arranged at the lower end of the pressing member 67, spaced apart in the left-right direction. The fulcrum protrusions 671 are arranged substantially symmetrically with respect to the plane P.

[0053] Each pressing protrusion 673 is a protrusion that protrudes rearward. The pressing protrusions 673 are arranged substantially in the vertical center of the two pressing members 67 (more specifically, at positions that overlap with the rotation axis A1 when viewed from the side), and are spaced apart in the left-right direction. The pressing protrusions 673 are arranged substantially symmetrically with respect to the plane P.

[0054] The engagement hole 675 is a hole that penetrates the upper end of the pressing member 67 in the front-rear direction. A long connecting member 68 is inserted into the engagement hole 675 and extends in the front-rear direction. The connecting member 68 is a rod-shaped member, and a disk-shaped head 681 with a diameter larger than that of the engagement hole 675 is fixed to the front end of the connecting member 68. The connecting member 68 is inserted into the engagement hole 675 with the head 681 disposed in front of the pressing member 67. The rear end of the connecting member 68 is connected to a plunger 83 of the solenoid 8, which will be described later.

[0055] The pressing member 67 is disposed between the brake member 63 and the partition wall 15 in the front-rear direction so as to be rotatable in the front-rear direction. More specifically, as shown in FIG. 5 , two recesses 153 are formed in the lower end of the partition wall 15, spaced apart in the left-right direction. Each recess 153 is formed with a semicircular cross section that matches the fulcrum protrusion 671. The fulcrum protrusion 671 engages with the recess 153. With this configuration, the pressing member 67 is rotatable in the front-rear direction relative to the tool body 10 and, ultimately, the brake member 63, using the two fulcrum protrusions 671 as fulcrums (around axes extending in the left-right direction). The two pressing protrusions 673 are disposed at positions facing the brake member 63 (specifically, the left central portion and the right central portion of the receiving plate 631) in the front-rear direction, respectively.

[0056] As described above, the biasing member 65 constantly biases the brake member 63 forward, and therefore the pressing member 67 is also biased forward via the brake member 63. For this reason, as shown in Fig. 5, the pressing member 67 is normally held in a position where its upper end (the portion below the engagement hole 675) abuts against the stopper 155 provided on the partition wall 15 from behind (hereinafter also referred to as the initial position).

[0057] The brake member 63 is held in a position where a front surface 633 at the center of the receiving plate 631 abuts against a pressing protrusion 673 of the pressing member 67 from behind. The pressing protrusion 673 abuts against the brake member 63 at approximately the center in the up-down direction of the brake member 63, symmetrically with respect to the plane P. At this time, a rear surface (friction surface) 637 of the friction material 636 of the brake member 63 is spaced forward from a front surface 617 of the outer periphery of the brake rotor 61. Hereinafter, the position of the brake member 63 when the pressing member 67 is in the initial position (when the rear surface 637 is spaced from the front surface 617) (the position shown in FIG. 5) will also be referred to as the spaced position.

[0058] The solenoid 8 will be described in detail below.

[0059] 1 and 5, the solenoid 8 is disposed radially outside the motor main body 20 within the tool body 10. More specifically, the solenoid 8 is disposed directly above the motor main body 20 within the rear housing portion 11. In this embodiment, the rotation axis A1 of the motor shaft 25 is positioned below the drive axis A2, so a space is formed directly above the motor main body 20 within the rear housing portion 11. This space is therefore effectively utilized as an arrangement space for the solenoid 8.

[0060] The solenoid 8 is a well-known electrical component configured to convert electrical energy into mechanical energy of linear motion by using a magnetic field generated by passing a current through a coil. The solenoid may also be called a solenoid actuator, a linear solenoid, etc.

[0061] Although detailed illustration is omitted, the solenoid 8 includes a coil housed in a frame and a plunger 83 that can move linearly in response to the supply of current to the coil. The solenoid 8 is arranged so that the movement axis A3 of the plunger 83 extends substantially parallel to the rotation axis A1 (i.e., in the front-to-rear direction). This arrangement makes it possible to most efficiently utilize the space directly above the motor main body 20. The front end of the plunger 83 protrudes forward from the frame and is connected to the rear end of the connecting member 68. In other words, the plunger 83 and the pressing member 67 are operably connected via the connecting member 68.

[0062] In this embodiment, the solenoid 8 is a so-called pull-type solenoid, and the plunger 83 is normally disposed in the foremost position (the position shown in FIG. 5). When a current is applied to the coil, the plunger 83 moves linearly rearward along the movement axis A3, and the connecting member 68 also moves linearly rearward together with the plunger 83, as shown in FIG.

[0063] As the plunger 83 moves rearward, it pulls the upper end of the pressing member 67 rearward via the head 681 at the front end of the connecting member 68. As a result, the pressing member 67 rotates rearward (clockwise as viewed from the left) from the initial position with the fulcrum protrusion 671 as the fulcrum, against the biasing force of the biasing member 65. The pressing member 67 rotates with the pressing protrusion 673 in contact with the brake member 63, thereby moving the brake member 63 rearward and pressing the brake member 63 against the brake rotor 61. Hereinafter, the position of the pressing member 67 at this time (the position shown in FIG. 6) will also be referred to as the pressing position.

[0064] While the pressing member 67 rotates, the brake member 63 is guided by the guide pin 151 and moves linearly rearward while the rear surface 637 of the friction material 636 is substantially parallel to the front surface 617 of the brake rotor 61. Note that, due to the arrangement of the biasing member 65 and the pressing protrusion 673 described above, the pressing member 67 can press and move the brake member 63 in a balanced manner against the biasing force of the biasing member 65 in response to the rotation.

[0065] The brake member 63 is pressed against the brake rotor 61, and a rear surface 637 of the brake member 63 comes into contact with and frictionally engages with a front surface 617 of the brake rotor 61, thereby braking the motor shaft 25 via the brake rotor 61. Note that the term "frictional engagement" refers to engagement due to frictional force, and is a concept that also includes a state in which engagement occurs in a sliding state. Hereinafter, the position of the brake member 63 where the rear surface 637 of the brake member 63 and the front surface 617 of the brake rotor 61 frictionally engage (the position shown in FIG. 6) is also referred to as the contact position.

[0066] The operation of the hammer drill 1A will now be described.

[0067] As described above, when the trigger 171 is pressed and the switch 172 is turned on, the control circuit 51 of the controller 5 energizes the motor 2 and starts driving the motor 2. The drive mechanism 4 operates according to the selected operation mode.

[0068] While driving the motor 2, the control circuit 51 determines whether a lock state has occurred based on the acceleration detected by the acceleration sensor 53 (the signal from the acceleration sensor 53). The acceleration detected by the acceleration sensor 53 is a physical quantity (index) that indicates the rotation state of the tool body 10 about the drive axis A2, and therefore the lock state of the spindle 3. Any method may be used to determine whether a lock state has occurred. For example, a method may be employed in which it is determined that a lock state has occurred when the detected acceleration or a value calculated based on the acceleration (e.g., angular acceleration) exceeds a predetermined threshold value.

[0069] When the control circuit 51 determines that a locked state has occurred (i.e., when it detects that a locked state has occurred), it stops supplying electricity to the motor 2, i.e., stops driving the motor 2. Furthermore, the control circuit 51 activates the solenoid 8 at substantially the same timing as (or immediately before or after) stopping the supply of electricity to the motor 2, thereby actuating the brake device 6. As described above, the plunger 83 and the connecting member 68 are pulled rearward, and the pressing member 67 moves the brake member 63 from the separated position to the contact position (see FIG. 6).

[0070] Even when the supply of electricity to the motor 2 is stopped, the rotor 23 and motor shaft 25 of the motor 2 tend to continue rotating due to inertia. In response to this, the brake member 63, located at the contact position, frictionally engages with the brake rotor 61 to brake the motor shaft 25 of the motor 2. The brake rotor 61 decelerates and rotates together with the motor shaft 25 while sliding against the brake member 63, and then stops rotating. When the rotation of the motor shaft 25 stops, the operation of the drive mechanism 4 also stops. Note that the motor 2 of this embodiment is a brushed motor, which is more difficult to brake electrically than a brushless DC motor. Therefore, this embodiment employs a mechanical brake device 6 to quickly stop the motor shaft 25 after the supply of electricity to the motor 2 is stopped.

[0071] Thereafter, when the trigger 171 is released and the switch 172 is turned off, the control circuit 51 stops the supply of current to the solenoid 8. Alternatively, the control circuit 51 may stop the supply of current after a predetermined time has elapsed since the plunger 83 was activated. This causes the plunger 83 to return to the forward-most position. In response to the return of the plunger 83 to the forward-most position, the braking member 63 returns from the contact position to the separated position due to the biasing force of the biasing member 65, and the pressing member 67 returns from the pressing position to the initial position (see FIG. 5).

[0072] As described above, in this embodiment, if the spindle 3, which is the final output shaft of the hammer drill 1A, becomes locked for some reason, the brake device 6, which is a safety device, directly acts on the motor shaft 25 to brake it. This makes it possible to prevent the tool body 10 from rotating excessively around the drive shaft A2 due to reaction torque. The brake device 6 is also configured to act directly on the motor shaft 25. Therefore, the motor shaft 25 can be braked with a smaller force than when the brake device 6 acts directly on the spindle 3, which is the final output shaft, and excessive rotation of the tool body 10 can be prevented.

[0073] Furthermore, since the brake device 6 is disposed between the motor 2 and the drive mechanism 4 (rotation transmission mechanism 46) in the power transmission path, it can brake the motor shaft 25 efficiently at a position relatively close to the motor 2. Furthermore, the brake device 6 can be disposed in a position less susceptible to the influence of the lubricant than if it were to act directly on the spindle 3. In particular, in this embodiment, the brake device 6 is disposed in the rear housing portion 11, which is separated by the partition wall 15 from the front housing portion 13 in which the lubricant is disposed. Therefore, the brake device 6 can be easily and reliably isolated from the lubricant.

[0074] In this embodiment, the solenoid 8 operably connected to the brake device 6 (pressing member 67) activates the brake device 6. More specifically, the control circuit 51 of the controller 5 activates the solenoid 8 in response to detection of a locked state, thereby operating the brake device 6. The solenoid 8 is a relatively inexpensive electrical component. Therefore, a configuration that quickly activates the brake device 6 in response to detection of a locked state can be realized at relatively low cost. Furthermore, since the solenoid 8, which is an electrical component, is also disposed in the rear housing portion 11, the solenoid 8 can be protected from lubricant and the solenoid 8 can be easily connected to the brake device 6 (pressing member 67). Furthermore, the brake device 6 and the solenoid 8 can be disposed in their entirety in a relatively small space.

[0075] Furthermore, in this embodiment, the brake rotor 61 and the brake member 63 brake the motor shaft 25 by frictionally engaging with each other. The brake member 63 is normally biased by the biasing member 65 and disposed in the separated position, but is moved to the contact position by the pressing member 67 in response to detection of a locked state, and is pressed against the brake rotor 61 to frictionally engage with it. In this embodiment, a rational configuration is realized in which the motor shaft 25 can be braked simply by moving the pressing member 67 in response to activation of the solenoid 8. In particular, in this embodiment, the pressing member 67 rotates about the fulcrum protrusion 671, thereby moving the brake member 63 linearly and effectively bringing the rear surface 637 of the brake member 63 into contact with the front surface 617 of the brake rotor 61 over a relatively wide range.

[0076] The correspondence between the configuration (features) of the first embodiment and the configuration (features) of the present disclosure is shown below. However, the configuration (features) of the embodiment are merely examples and do not limit the configuration (features) of the present disclosure or the present invention.

[0077] The hammer drill 1A is an example of a "power tool." The motor 2, the motor main body 20, the stator 21, the rotor 23, and the motor shaft 25 are examples of a "motor," a "motor main body," a "stator," a "rotor," and a "motor shaft," respectively. The rotating shaft A1 is an example of a "first rotating shaft." The spindle 3 (tool holder 32) is an example of a "final output shaft." The drive shaft A2 is an example of a "second rotating shaft." The tool main body 10 is an example of a "tool main body." The controller 5 (control circuit 51) is an example of a "detection device." The braking device 6 is an example of a "braking device."

[0078] The drive mechanism 4 (rotation transmission mechanism 46) is an example of a "transmission mechanism." The fan 27 is an example of a "fan." The solenoid 8 is an example of a "solenoid." The brake rotor 61 is an example of a "first rotating member." The brake member 63, the biasing member 65, and the pressing member 67 are examples of a "brake member," a "first biasing member," and a "pressing member," respectively. The front surface 617 of the brake rotor 61 is an example of a "first surface of the first rotating member." The rear surface 637 of the brake member 63 is an example of a "second surface of the brake member."

[0079] [Second embodiment] A hammer drill 1B according to a second embodiment will now be described with reference to Figures 7 to 10. The hammer drill 1B is equipped with a brake device 7 that is different from the brake device 6 of the hammer drill 1A of the first embodiment. The manner in which the brake device 7 is connected to the solenoid 8 is also different from that of the first embodiment. However, apart from these configurations, the hammer drill 1B has substantially the same configuration as the hammer drill 1A. Therefore, in the following description, substantially the same configurations will be assigned the same reference numerals as in the first embodiment, and illustrations and descriptions will be omitted or simplified as appropriate. Features that differ from the first embodiment will mainly be described.

[0080] 7 to 9, the brake device 7 of the hammer drill 1B is disposed between the fan 27 and the bearing 251 (partition wall 15) in the extending direction of the motor shaft 25 (i.e., the front-rear direction) (i.e., on the opposite side of the fan 27 from the motor main body 20). The solenoid 8 is disposed directly above the motor 2 in the rear housing portion 11.

[0081] The brake device 7 includes a first rotor 71, a second rotor 72, a biasing member 75, and a stopper 77.

[0082] The first rotor 71 is fixed to the motor shaft 25 between the fan 27 and the bearing 251, and rotates integrally with the motor shaft 25 around the rotation axis A1. The first rotor 71 includes a sleeve 711 fixed to the motor shaft 25, and a disk-shaped disk portion 715 that protrudes radially outward from the sleeve 711. The first rotor 71 is made of metal (for example, iron).

[0083] The second rotor 72 is formed in an annular shape overall. The outer diameter of the second rotor 72 is larger than the outer diameter of the disk portion 715 of the first rotor 71. A recess that roughly matches the disk portion 715 is formed on the front side of the second rotor 72. The second rotor 72 is disposed on the rear side of the first rotor 71 and is fitted into the outer periphery of the disk portion 715 from the rear side. The second rotor 72 is formed of metal (for example, iron). The second rotor 72 is also provided with two protrusions 725 that protrude radially outward. The two protrusions 725 have the same shape and are disposed diagonally across the rotation axis A1.

[0084] The biasing member 75 is configured to bias the second rotor 72 toward the first rotor 71 and press it against the first rotor 71. In this embodiment, a disc spring is used for the biasing member 75, which is capable of exerting a high load while saving space. The biasing member 75 is disposed in a compressed state between the second rotor 72 and a retaining ring 712 in the front-rear direction. The retaining ring 712 is fixed to the sleeve 711 of the first rotor 71 on the rear side of the second rotor 72. A rear surface 717 of the outer periphery of the disk portion 715 of the first rotor 71 and a front surface 722 (bottom surface of the recess) of the second rotor 72 are normally frictionally engaged by the biasing force of the biasing member 75. Therefore, as the motor shaft 25 and the first rotor 71 rotate, the second rotor 72 also rotates. As in the first embodiment, a friction material may be fixed to one of the first rotor 71 and the second rotor 72.

[0085] The stopper 77 is operably connected to the solenoid 8, and is configured to move (more specifically, move linearly) in response to activation of the solenoid 8, thereby interfering with (contacting) the second rotor 72 and stopping the rotation of the second rotor 72. In this embodiment, the stopper 77 is a cylindrical pin, and is arranged so that its movement axis A4 extends parallel to the rotation axis A1 (i.e., in the front-to-rear direction).

[0086] The front portion of the stopper 77 is disposed within a guide hole 157 formed in the partition wall 15 so as to be slidable in the front-rear direction. A guide member 16 having a guide hole 161 is fixed to the rear surface of the partition wall 15. The guide hole 161 is formed in a portion of the guide member 16 rearward of and facing the guide hole 157. The stopper 77 is slidable in the front-rear direction within the guide hole 161. The guide hole 157 and the guide hole 161 stably guide the movement of the stopper 77 in the front-rear direction. The movement axis A4 of the stopper 77 intersects with the movement path of the protrusion 725 (the area through which the protrusion 725 passes) when the second rotor 72 rotates.

[0087] The manner in which the brake device 7 (stopper 77) and the solenoid 8 are connected will be described below.

[0088] As shown in FIG. 8 , the stopper 77 and the plunger 83 of the solenoid 8 are operably connected via a connecting member 78. The connecting member 78 is a plate-like member that is bent into an L-shape when viewed from the side, and includes a first portion 781 that extends in the front-rear direction and a second portion 782 that extends downward from the front end of the first portion 781. The rear end of the first portion 781 is connected to the front end of the plunger 83. A support hole 783 is formed in the second portion 782. The stopper 77 is supported by the connecting member 78 while being inserted into the support hole 783 so as to be slidable in the front-rear direction.

[0089] A flange portion 771 that protrudes radially outward is provided at approximately the center of the stopper 77 in the front-rear direction (a portion that is always positioned outside the guide hole 157). The stopper 77 is inserted into the support hole 783 so that the flange portion 771 faces the rear surface of the second portion 782. A biasing member 79 is disposed between the guide member 16 and the flange portion 771 in the front-rear direction. The biasing member 79 is a compression coil spring. The biasing member 79 is mounted on the stopper 77 in a compressed state with its front end abutting against the flange portion 771 and its rear end abutting against the guide member 16. Therefore, the stopper 77 is always biased by the biasing member 79 in a direction away from the guide member 16 (forward), and the flange portion 771 is held in a position where it abuts against the rear surface of the second portion 782.

[0090] In the initial state where no current is supplied to the solenoid 8, the plunger 83 and the connecting member 78 are at the forwardmost positions within their respective movable ranges. Therefore, the stopper 77 is also at the forwardmost position within its movable range. At this time, the rear end of the stopper 77 is located forward of the second rotor 72. Therefore, the stopper 77 is not located on the movement path of the protrusion 725 of the second rotor 72. In other words, even when the second rotor 72 rotates, the stopper 77 does not physically interfere with the protrusion 725. For this reason, hereinafter, the forwardmost position of the stopper 77 (the position shown in FIG. 8) is also referred to as the non-interference position.

[0091] When a current is applied to the coil, the plunger 83 moves linearly rearward along the movement axis A3. The connecting member 78 moves linearly rearward together with the plunger 83, causing the stopper 77 to move linearly rearward along the movement axis A4 against the biasing force of the biasing member 79. When the solenoid 8 is activated and the stopper 77 moves to the rearmost position within its movable range as shown in FIG. 10, the rear end of the stopper 77 is positioned rearward of the rear end of the second rotor 72. The stopper 77 is disposed on the movement path of the protrusion 725, and physically interferes with (abuts against) the protrusion 725 when the second rotor 72 rotates. For this reason, hereinafter, the rearmost position of the stopper 77 (the position shown in FIG. 10) is also referred to as the interference position. When the stopper 77 abuts against the protrusion 725 of the second rotor 72 at the interference position, it stops the rotation of the second rotor 72 and brakes the motor shaft 25 via the first rotor 71.

[0092] The operation of the hammer drill 1B will now be described.

[0093] When the trigger 171 is pressed and the switch 172 is turned on, the control circuit 51 of the controller 5 energizes the motor 2 and starts driving the motor 2. The drive mechanism 4 operates in accordance with the selected operation mode.

[0094] While driving the motor 2, the control circuit 51 determines whether a locking state has occurred based on the acceleration detected by the acceleration sensor 53 (the signal from the acceleration sensor 53). When the control circuit 51 determines that a locking state has occurred (i.e., when it detects the occurrence of a locking state), it stops the supply of electricity to the motor 2, i.e., stops the driving of the motor 2. The control circuit 51 also activates the solenoid 8 at substantially the same timing as the de-energization of the motor 2 (or immediately before or after the de-energization), thereby actuating the brake device 7. As described above, the plunger 83 and the connecting member 78 are pulled rearward, and the stopper 77 is moved from the non-interference position to the interference position (see FIG. 10).

[0095] Even when the power supply to the motor 2 is stopped, the rotor 23 and motor shaft 25 of the motor 2 tend to continue rotating due to inertia. In response to this, the stopper 77 disposed at the interference position abuts against the second rotor 72, immediately stopping the rotation of the second rotor 72. When the second rotor 72 stops rotating, the first rotor 71 decelerates and rotates together with the motor shaft 25 while sliding relative to the second rotor 72, and then stops rotating. In this embodiment, an impact occurs due to the abutment (collision) between the stopper 77 and the second rotor 72 (protrusion 725). In response to this, this impact can be buffered by causing slippage between the second rotor 72 and the first rotor 71, which is integrated with the motor shaft 25. When the rotation of the motor shaft 25 stops, the operation of the drive mechanism 4 also stops.

[0096] Thereafter, when the control circuit 51 stops supplying current to the solenoid 8, the plunger 83 returns to the forward-most position. In response to the return of the plunger 83 to the forward-most position, the connecting member 78 also returns to the forward-most position, and the biasing force of the biasing member 79 returns the stopper 77 from the interference position to the non-interference position (see FIG. 8).

[0097] As described above, in this embodiment, similar to the first embodiment, if the spindle 3 falls into a locked state for some reason, the brake device 7, which is a safety device, directly acts on the motor shaft 25 to brake it in response to activation of the solenoid 8. This makes it possible to prevent the tool body 10 from rotating excessively around the drive axis A2 due to reaction torque. Furthermore, because the brake device 7 is configured to act directly on the motor shaft 25, it can brake the motor shaft 25 with a smaller force than when it acts directly on the spindle 3, thereby preventing excessive rotation of the tool body 10. Furthermore, in this embodiment, the brake device 7 and solenoid 8 are also disposed in the rear housing portion 11. Therefore, similar to the first embodiment, protection from lubricants and easy connection between the solenoid 8 and the brake device 7 (stopper 77) are realized.

[0098] Furthermore, in this embodiment, the first rotor 71 and the second rotor 72 are normally pressed against each other by the biasing force of the biasing member 75, causing frictional engagement and rotating together to transmit torque. Then, in response to detection of a locked state, the stopper 77 is moved from the non-interference position to the interference position, stopping the rotation of the second rotor 72 and braking the motor shaft 25 via the first rotor 71. In this embodiment, a rational configuration is realized in which the motor shaft 25 can be braked simply by moving the stopper 77 in response to activation of the solenoid 8. Furthermore, the second rotor 72 has two protrusions 725 arranged diagonally (i.e., equidistantly spaced circumferentially) that can interfere with the stopper 77 in the interference position. This suppresses imbalance during rotation and realizes a second rotor 72 that can be quickly stopped by the stopper 77.

[0099] The correspondence between the configuration (features) of the second embodiment and the configuration (features) of the present disclosure is shown below. However, the configuration (features) of the embodiment are merely examples and do not limit the configuration (features) of the present disclosure or the present invention. Note that descriptions of configurations that are substantially the same as those of the first embodiment will be omitted.

[0100] The hammer drill 1B is an example of a "power tool." The brake device 7 is an example of a "brake device." The first rotor 71 is an example of a "first rotating member." The second rotor 72, the biasing member 75, and the stopper 77 are examples of a "second rotating member," a "second biasing member," and a "stopper," respectively. The biasing member 75 is an example of a "disc spring." The protrusion 725 is an example of an "interference portion."

[0101] The above-described embodiments are merely examples, and the power tools according to the present disclosure are not limited to the hammer drills 1A and 1B illustrated in the above-described embodiments. For example, the following non-limiting modifications may be made. Furthermore, at least one of these modifications may be adopted in combination with at least a portion of the configuration (feature) of the hammer drills 1A and 1B, or at least one of the configuration (feature) recited in the claims.

[0102] For example, in the above-described embodiments, hammer drills 1A and 1B capable of rotating and striking operations are given as specific examples of power tools having a final output shaft configured to be rotationally driven. However, the power tool according to the present disclosure may be embodied as an electric drill capable of rotating only, or as a tightening tool capable of tightening nuts and bolts. Furthermore, the power tool according to the present disclosure may be applied to, for example, a hammer drill having two operating modes, a striking mode and a rotary striking mode.

[0103] The hammer drills 1A and 1B may be configured to operate on power supplied from a rechargeable battery instead of an external AC power source. In this case, instead of the power cord 179, a battery attachment section to which a battery can be attached or detached may be provided, for example, at the lower end of the handle 17.

[0104] The motor 2 may be disposed such that the rotation axis A1 of the motor shaft 25 intersects with the drive axis A2. The configuration of the tool body 10 may be changed in accordance with the change in the arrangement of the motor 2. For example, the tool body 10 may be formed in an L-shape. The internal space of the tool body 10 does not need to be partitioned by the partition wall 15, and may be partitioned at another position. Note that the brake devices 6, 7 are preferably disposed in a space within the tool body 10 where no lubricant is disposed.

[0105] The configuration and arrangement of the fan 27, and the arrangement of the air flow path (intake port) and exhaust port) within the tool body 10 may be different from those of the above embodiment. For example, the fan 27 may be arranged behind the motor body 20. Also, for example, a fan capable of drawing air from two axial directions (front and rear) may be used as the fan 27.

[0106] In the above embodiment, an example has been described in which the control circuit 51 of the controller 5 detects the occurrence of a locked state based on the acceleration detected by the acceleration sensor 53. However, the hammer drills 1A and 1B may be provided with another type of detector (e.g., a speed sensor, an angular velocity sensor, or an angular acceleration sensor) capable of detecting the rotational state of the tool body 10 about the drive axis A2, instead of the acceleration sensor 53. Alternatively, the hammer drills 1A and 1B may be provided with a detector that detects a physical quantity other than the rotational state of the tool body 10 (e.g., a load acting on the tool bit 91), and the control circuit 51 may detect the occurrence of a locked state based on the detected physical quantity. Furthermore, the acceleration sensor 53 or another detector may be provided separately from the controller 5 (control circuit 51). The control circuit 51 and the acceleration sensor 53 may be disposed in the tool body 10, rather than in the handle 17.

[0107] The configuration of the brake devices 6, 7 (for example, the components, and the shape, number, and arrangement of each component) can be changed as appropriate. Modifications that can be adopted in the brake devices 6, 7 are listed below.

[0108] The brake member 63 of the brake device 6 may be provided with a plurality of friction materials that can frictionally engage with the front surface 617 of the brake rotor 61. The brake member 63 may be configured to move, for example, in the radial direction of the brake rotor 61. The brake rotor 61 and the brake member 63 may be configured so that their conical surfaces frictionally engage with each other, rather than their surfaces perpendicular to the rotation axis A1. The guide structure of the brake member 63 may be formed by a member different from the guide pin 151 (for example, an inner wall portion of the tool body 10). The number of guide pins 151 may be any number other than four.

[0109] The number and arrangement of the fulcrum protrusions 671 and / or the pressing protrusions 673 of the pressing member 67 are not limited to those in the above embodiment. Furthermore, the pressing member 67 may not have the fulcrum protrusions 671 and / or the pressing protrusions 673, as long as it can press the brake member 63 against the brake rotor 61. For example, the pressing member 67 may be rotatably supported by a support shaft supported by the tool body 10 (rear housing portion 11). The pressing member 67 may be configured to move linearly in the front-to-rear direction to press the brake member 63 against the brake rotor 61. Alternatively, the pressing member 67 may be omitted. For example, the brake member 63 may be operably connected to the plunger 83 (connecting member 68) and move in response to activation of the solenoid 8.

[0110] The first rotor 71 and the second rotor 72 of the brake device 7 may be configured so that their conical surfaces frictionally engage with each other, rather than with surfaces perpendicular to the rotation axis A1. The number of protrusions 725 on the second rotor 72 may be one, or may be three or more. However, in order to suppress imbalance during rotation of the second rotor 72, it is preferable that the plurality of protrusions 725 be arranged at equal intervals in the circumferential direction. Furthermore, a portion of the second rotor 72 other than the protrusions may be able to come into contact with the stopper 77. For example, an arc-shaped groove may be formed in the disk-shaped second rotor 72, and the stopper 77 may engage with this groove to stop the rotation of the second rotor 72.

[0111] The stopper 77 may have another shape (for example, a rectangular column shape) as long as it can interfere with (abut against) the protrusion 725 at the interference position to stop the rotation of the second rotor 72. The stopper 77 may be formed by a part of the connecting member 78. The stopper 77 may also be movable in the radial direction of the second rotor 72 between the non-interference position and the interference position. The guide structure of the stopper 77 may be formed by a part other than the partition wall 15 or the guide member 16 (for example, an inner wall portion of the tool body 10).

[0112] The connecting members 68 and 78 may each have a shape different from that of the above embodiment, or may be composed of multiple members connected to each other. Furthermore, the connecting manner between the connecting member 68 and the pressing member 67 and the connecting manner between the connecting member 78 and the stopper 77 may be different from that of the above embodiment.

[0113] The biasing members 65, 75 may each be a different type of spring (e.g., tension spring, torsion spring) or an elastic body (e.g., elastomer) from that in the above embodiment. The number and arrangement of the biasing members 65, 75 may also be different from that in the above embodiment.

[0114] The solenoid 8 may be a push-type solenoid instead of a pull-type solenoid. In this case, for example, in the brake device 6, the brake member 63 (and the pressing member 67) may be disposed between the brake rotor 61 and the solenoid 8 in the front-rear direction. Also, in the brake device 7, the stopper 77 may be disposed in the initial state at the rearmost position where it cannot interfere with the protrusion 725 of the second rotor 72, and may be moved to the frontmost position where it can interfere with the protrusion 725 in response to activation of the solenoid 8. A plurality of solenoids 8 may be provided.

[0115] Furthermore, in consideration of the spirit of the present invention, the above-described embodiments, and their modifications, the following aspects are constructed. At least one of the following aspects can be adopted in combination with the above-described embodiments, their modifications, and at least one of the configurations (features) described in each claim. [Aspect 1] The brake device is a friction brake mechanism that exerts braking force by frictional engagement between a plurality of members. [Aspect 2] At least a portion of the brake member that frictionally engages with the first rotating member is made of a friction material. According to this aspect, the brake member can brake the first rotating member efficiently. The friction material 636 is an example of a "friction material." [Aspect 3] At least one guide is provided to linearly guide the brake member between a spaced position where the second surface is spaced from the first surface of the first rotating member and a contact position where the second surface abuts and frictionally engages with the first surface. According to this embodiment, the movement of the brake member can be stabilized. The guide pin 151 is an example of the "guide" of this embodiment. [Aspect 4] The pressing member has a plurality of pressing protrusions that protrude in a direction approaching the brake member and come into contact with the brake member. The pressing protrusion 673 is the "pressing protrusion" of this embodiment. [Aspect 5] The internal space of the tool body is divided by a partition wall into at least a first space in which the motor is disposed and a second space in which the final output shaft and the transmission mechanism are disposed together with a lubricant, and the brake device is disposed in the second space. According to this aspect, the partition wall can reliably isolate the motor main body and the brake device from the lubricant. The partition wall 15 is an example of the "partition wall" of this aspect. The internal space of the rear housing portion 11 is an example of the "first space." The internal space of the front housing portion 13 is an example of the "second space." [Aspect 6] The partition supports a bearing that rotatably supports the motor shaft. According to this embodiment, a rational configuration is realized in which the partition wall that separates the first space from the second space is used as a support for the bearing. Bearing 251 is an example of the "bearing" of this embodiment. [Aspect 7] The solenoid is disposed in the first space. According to this aspect, the brake device and the solenoid are disposed together with the motor in the first space, which does not require lubricant, and therefore the solenoid and the brake device can be easily connected. [Aspect 8] The solenoid is disposed on a straight line that is perpendicular to the first rotation axis and passes through the motor main body. According to this aspect, the solenoid is disposed radially outward of the motor main body, and therefore the solenoid and the brake device can be disposed relatively compactly in the direction in which the first rotation axis (rotation axis of the motor shaft) extends. [Aspect 9] The solenoid is configured to move linearly parallel to the first axis of rotation and includes an actuator operatively connected to the braking device. According to this aspect, the solenoid can be arranged relatively compactly in the radial direction of the motor main body. The plunger 83 is an example of the "actuating portion" of this aspect. [Aspect 10] The actuator is operatively coupled to the biasing member and configured to move the biasing member upon actuation. [Aspect 11] The actuator is operatively coupled to the stopper and configured to move the stopper upon actuation. [Aspect 12] The stopper is configured to move linearly in parallel with the extending direction of the first rotation shaft. [Aspect 13] The detection device is configured to detect the locked state based on a rotation state of the tool body about the second rotation axis. When the final output shaft is locked, the tool body rotates around the second rotation axis, and therefore, according to this aspect, the detection device can appropriately detect the locked state. [Aspect 14] The power tool further includes a detector for detecting the rotation state of the tool body around the second rotation axis. The acceleration sensor 53 is an example of a "detector." [Aspect 15] The power tool further includes a controller configured to activate the solenoid in response to detecting the locked condition. The control circuit 51 of the controller 5 is an example of the "control device" of this embodiment. [Aspect 16] The first rotation axis and the second rotation axis are parallel to each other. [Explanation of symbols]

[0116] 1A, 1B: hammer drill, 10: tool body, 11: rear housing, 113: spring receiving part, 13: front housing, 131: barrel part, 15: partition, 151: guide pin, 153: recess, 155: stopper, 157: guide hole, 16: guide member, 161: guide hole, 17: handle, 171: trigger, 172: switch, 179: power cord, 2: motor, 20: motor body, 21: stem motor, 23: rotor, 25: motor shaft, 251: bearing, 252: bearing, 27: fan, 3: spindle, 32: tool holder, 33: cylinder, 4: drive mechanism, 41: impact mechanism, 413: piston, 415: impact bolt, 46: rotation transmission mechanism, 461: drive gear, 463: driven gear, 5: controller, 51: control circuit, 53: acceleration sensor, 6: brake device, 61: brake brake rotor, 611: sleeve, 615: disk portion, 617: front surface, 63: brake member, 631: receiving plate, 633: front surface, 634: convex portion, 635: guide hole, 636: friction material, 637: rear surface, 65: biasing member, 67: pressing member, 671: fulcrum protrusion, 673: pressing protrusion, 675: engagement hole, 68: connecting member, 681: head, 7: brake device, 71: first rotor, 711: sleeve, 7 12: retaining ring, 715: disk portion, 717: rear surface, 72: second rotor, 722: front surface, 725: protrusion, 75: biasing member, 77: stopper, 771: flange portion, 78: connecting member, 781: first portion, 782: second portion, 783: support hole, 79: biasing member, 8: solenoid, 83: plunger, 91: tip tool, A1: rotation axis, A2: drive axis, A3: moving axis, A4: moving axis, P: plane

Claims

1. a motor having a motor body including a stator and a rotor, and a motor shaft extending from the rotor and rotatable around a first rotation axis; a final output shaft configured to be rotationally driven about a second rotation axis by torque transmitted from the motor shaft; a tool body that houses the motor and the final output shaft; a detection device configured to detect a locked state of the final output shaft; a mechanical brake device configured to directly act on the motor shaft to brake the motor shaft in response to detection of the locked state; an operating portion operably connected to the brake device, the brake device includes: (i) a first rotating member fixed to the motor shaft so as to be rotatable integrally with the motor shaft; (ii) a brake member; (iii) at least one first biasing member that biases the brake member in a direction away from the first rotating member; and (iv) a pressing member; The pressing member is rotated around a fulcrum by the operating unit in response to detection of the locked state, At least a portion of the rotated pressing member presses the brake member, The pressed brake member is pressed against the first rotating member against the biasing force of the at least one first biasing member, and brakes the motor shaft by frictionally engaging with the first rotating member. Power tools.

2. The power tool according to claim 1, a transmission mechanism configured to transmit the torque of the motor shaft to the final output shaft; The power tool, wherein the first rotating member of the brake device is disposed between the motor body and the transmission mechanism in a power transmission path.

3. The power tool according to claim 1 or 2, a fan disposed between the motor body and the brake device in the extending direction of the first rotation shaft and configured to rotate integrally with the motor shaft; The power tool, wherein the fan is configured to generate an airflow that cools the motor body and the brake device.

4. The power tool according to any one of claims 1 to 3, the operating unit is a solenoid, The power tool is characterized in that the solenoid is activated in response to detection of the locked state, and is configured to move an end of the pressing member so as to approach the first rotating member.

5. The power tool according to any one of claims 1 to 4, The brake member may further include at least one guide that linearly guides the brake member between a spaced position where the brake member is spaced from the first rotating member and a contact position where the brake member is in contact with the first rotating member, the brake member has a second surface capable of frictionally engaging with the first surface of the first rotating member; When the brake member is pressed by the rotated pressing member, (i) the brake member moves linearly by being guided by the at least one guide, and (ii) the second surface moves linearly relative to the first rotating member while being substantially parallel to the first surface, and is pressed against the first surface, thereby frictionally engaging with the first surface to brake the motor shaft. Power tools.

6. The power tool according to any one of claims 1 to 5, The pressing member has a plurality of pressing protrusions that protrude in a direction approaching the brake member, The plurality of pressing protrusions come into contact with the brake member and press the brake member as the pressing member rotates. Power tools.

7. a motor having a motor body including a stator and a rotor, and a motor shaft extending from the rotor and rotatable around a first rotation axis; a final output shaft configured to be rotationally driven about a second rotation axis by torque transmitted from the motor shaft; a tool body that houses the motor and the final output shaft; a detection device configured to detect a locked state of the final output shaft; a mechanical brake device configured to directly act on the motor shaft to brake the motor shaft in response to detection of the locked state; an operating portion operably connected to the brake device, The braking device is a first rotating member fixed to the motor shaft so as to be rotatable integrally with the motor shaft; a second rotating member that is frictionally engaged with the first rotating member and that is rotatable about the first rotation axis in response to rotation of the motor shaft and the first rotating member; at least one second biasing member that biases the second rotating member toward the first rotating member and frictionally engages the first rotating member to brake the motor shaft; a stopper that is normally positioned at a first position where it cannot interfere with the second rotating member, and that is configured to stop the rotation of the second rotating member by being moved by the operating unit to a second position where it can interfere with the second rotating member in response to detection of the locked state.

8. The power tool according to claim 7, The power tool, wherein the at least one second biasing member is at least one disc spring.

9. The power tool according to claim 7 or 8, the second rotating member has a plurality of interference portions arranged at equal intervals in a circumferential direction around the first rotating shaft, The power tool is characterized in that the stopper is configured to stop rotation of the second rotating member by abutting against any one of the plurality of interference portions.

10. A power tool according to any one of claims 7 to 9, the operating unit is a solenoid, The power tool is characterized in that the solenoid is activated in response to detection of the locked state, and moves the stopper.

11. The power tool according to any one of claims 1 to 10, The electric power tool is characterized in that the motor is a brushed motor.

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