Power tool

Abstract

The present application provides an electric power tool. The electric power tool has a motor, a final output shaft, a tool body, a detection device and a braking device. The motor has a motor body portion and a motor shaft, wherein the motor body portion includes a stator and a rotor; the motor shaft is arranged to extend 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 braking device is a mechanical braking device and is configured to act directly on the motor shaft to brake the motor shaft in response to the locked state being detected. Accordingly, an improved safety device for an electric power tool can be provided.

Description

Technical Field

[0001] The present invention relates to an electric tool configured to drive a final output shaft to rotate. Background Technology

[0002] During the operation of power tools such as hammer drills, the final output shaft may sometimes become unable to rotate (also known as a locked or blocked state) due to reasons such as the tip tool biting into the workpiece. In this case, excessive reaction torque acts on the tool body (housing), which may cause the tool body to rotate excessively about the rotation axis of the final output shaft (also known as a kickback). Therefore, for example, Patent Document 1 proposes a drilling tool with a safety device. [Existing technical documents] [Patent Literature]

[0003] Patent Document 1: Japanese Patent Publication No. 4223584 Summary of the Invention [The technical problem that the invention aims to solve]

[0004] In the aforementioned safety device, in response to the detection of a locked state, the spindle is braked by frictional engagement between a structural component on the tool body and a structural component on the spindle. Since the spindle, which serves as the final output shaft, rotates at a lower speed than the motor, it generates a relatively large torque. Therefore, a correspondingly large force is required to brake the rotating spindle.

[0005] In view of the above, the object of the present invention is to provide an improvement in the safety device for power tools. [Technical solutions used to solve technical problems]

[0006] According to one aspect of the present invention, a power tool is provided, comprising a motor, a final output shaft, a tool body, a detection device, and a braking 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 braking device is a mechanical braking device. The braking device is configured to directly act on the motor shaft to brake it in response to detecting a locked state.

[0007] In this type of power tool, if the final output shaft becomes locked for some reason, a braking device, acting as a safety device, brakes the motor shaft, thus preventing excessive rotation of the tool body around the second axis. Furthermore, the braking device is configured to act directly on the motor shaft. Therefore, compared to the case where the braking force is directly applied to the final output shaft, a smaller force can be used to brake the motor shaft, suppressing excessive rotation of the tool body. Attached Figure Description

[0008] Figure 1 This is a cross-sectional view of the hammer drill according to the first embodiment. Figure 2 This is a partial 3D exploded view of the hammer drill. Figure 3 yes Figure 1 A magnified view of a portion of the image. Figure 4 yes Figure 3 Sectional view IV-IV. Figure 5 yes Figure 4 The VV sectional view represents the initial state in which the braking device is not in operation. Figure 6 Is with Figure 5 The corresponding sectional view shows the braking state after the braking device has been activated. Figure 7 This is a partial exploded perspective view of the hammer drill according to the second embodiment. Figure 8 This is a partial sectional view of a hammer drill. Figure 9 yes Figure 8 The IX-IX sectional view represents the initial state where the braking device is not in operation. Figure 10 Is with Figure 9 The corresponding sectional view shows the braking state after the braking device has been activated. Explanation of reference numerals in the attached figures 1A, 1B: Hammer drill; 10: Tool body; 11: Rear receiving part; 113: Spring support part; 13: Front receiving part; 131: Cylindrical part; 15: Partition wall; 151: Guide pin; 153: Recess; 155: Limiting element; 157: Guide hole; 16: Guide component; 161: Guide hole; 17: Handle; 171: Trigger; 172: Switch; 179: Power cord; 2: Motor; 20: Motor body; 21: Stator; 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: Rotary transmission mechanism; 461: Drive gear; 463: Driven gear; 5: Controller; 51: Control circuit; 53: Accelerometer; 6: Braking device; 61: Brake disc 611: rotor; 615: disc; 617: front surface; 63: braking component; 631: support plate; 633: front surface; 634: protrusion; 635: guide hole; 636: friction element; 637: rear surface; 65: force-applying component; 67: pressing component; 671: fulcrum protrusion; 673: pressing protrusion; 675: engaging hole; 68: connecting component; 681: head; 7: braking device; 71: first brake disc; 711: sleeve; 71 2: Retaining ring; 715: Disc; 717: Rear surface; 72: Second brake disc; 722: Front surface; 725: Protrusion; 75: Force-applying component; 77: Limiting component; 771: Flange; 78: Connecting component; 781: First part; 782: Second part; 783: Support hole; 79: Force-applying component; 8: Solenoid; 83: Piston; 91: Top tool; A1: Rotation axis; A2: Drive axis; A3: Movement axis; A4: Movement axis; P: Plane. Detailed Implementation

[0009] In one or more embodiments of the invention, the power tool may further include a transmission mechanism configured to transmit torque from the motor shaft to a final output shaft. A braking device may also be disposed between the motor and the transmission mechanism in the power transmission path. According to this configuration, the braking device can be positioned relatively close to the motor, thereby efficiently braking the motor shaft.

[0010] In one or more embodiments of the present invention, the power tool may further include a fan configured to be disposed between the motor body and the braking device in the extension direction of the first rotation axis, and to rotate integrally with the motor shaft. The fan may be configured to generate an airflow for cooling the motor body and the braking device. According to this configuration, both the motor body and the braking device can be cooled efficiently.

[0011] In one or more embodiments of the invention, the power tool may also include a solenoid that is operatively connected to the braking device. The solenoid may be configured to activate in response to the detection of a locked state, thereby engaging the braking device. According to this configuration, the braking device can be quickly engaged using a relatively inexpensive electrical component, namely the solenoid.

[0012] In one or more embodiments of the present invention, the braking device may include a first rotating component fixed to the motor shaft in a manner that allows it to rotate integrally with the motor shaft. According to this structure, a reasonable configuration can be achieved to brake the motor shaft by directly acting on it.

[0013] In one or more embodiments of the present invention, the braking device may include a braking member, at least one first force-applying member, and a pressing member. The braking member may also be configured to brake the motor shaft through frictional engagement with a first rotating member. The at least one first force-applying member may also be configured to apply force to the braking member in a direction away from the first rotating member. The pressing member may also be configured to press the braking member against the first rotating member in response to detecting a locked state, overcoming the force of the at least one first force-applying member. According to this structure, a reasonable structure is achieved that allows braking of the motor shaft by moving the pressing member.

[0014] In one or more embodiments of the present invention, the braking member may have a second surface capable of frictionally engaging with a first surface of the first rotating member. The pressing member may also be configured to rotate about a fulcrum, causing the braking member to move linearly relative to the first rotating member with the first and second surfaces substantially parallel. According to this configuration, by rotating the pressing member, the braking member can be moved linearly, thereby enabling effective contact between the first and second surfaces over a relatively wide range.

[0015] In one or more embodiments of the present invention, the braking device may include a second rotating member, at least one second force-applying member, and a limiting member. The second rotating member may also be configured to rotate about a first rotation axis in response to the rotation of the motor shaft and the first rotating member, while in a state of frictional engagement with the first rotating member. The at least one second force-applying member may also be configured to apply force to the second rotating member against the first rotating member, causing it to frictionally engage with the first rotating member. The limiting member may also be configured to be positioned in a first position where it can never interfere with the second rotating member, and to move to a second position where it can interfere with the second rotating member in response to the detection of a locked state, thereby stopping the rotation of the second rotating member. According to this structure, a reasonable structure can be achieved that allows braking of the motor shaft by moving the limiting member.

[0016] In one or more embodiments of the present invention, at least one second force-applying component may be at least one disc spring. According to this structure, at least one second force-applying component that saves space and can perform high loads can be achieved.

[0017] In one or more embodiments of the present invention, the second rotating member may have a plurality of interference portions arranged at equal intervals in the circumferential direction about the first rotation axis. The limiting member may also be configured to stop the rotation of the second rotating member by abutting against any one of the plurality of interference portions. According to this structure, a second rotating member that suppresses imbalance during rotation and can be quickly stopped by the limiting member can be realized.

[0018] In one or more embodiments of the present invention, the motor may be a brushed motor. According to this structure, even if the rotor and motor shaft continue to rotate due to inertia after the power to the brushed motor has been stopped, the motor shaft can be braked by a braking device to stop the rotation.

[0019] Hereinafter, several representative and non-limiting embodiments of the present invention will be specifically described with reference to the accompanying drawings. In the following embodiments, a hammer drill is illustrated as an example of a power tool configured to drive the final output shaft to rotate.

[0020] [First Implementation Method] Below, refer to Figures 1-6 The hammer drill 1A according to the first embodiment will be described. The hammer drill 1A is an electric tool capable of performing the following actions: driving the tip tool 91 to rotate about a predetermined drive axis A2 (hereinafter referred to as rotation action) and driving the tip tool 91 linearly along the drive axis A2 (hereinafter referred to as impact action). The hammer drill 1A is an example of a so-called rotation tool and also an example of an impact tool.

[0021] First, refer to Figure 1 A general description of the structure of hammer drill 1A is provided. For example... Figure 1 As shown, the outer contour of the hammer drill 1A is mainly formed by the tool body 10 and the handle 17 connected to the tool body 10.

[0022] The tool body 10 is a hollow body, also referred to as the housing, used to house the spindle 3, motor 2, and drive mechanism 4. The spindle 3 is an elongated cylindrical component. One axial end of the spindle 3 is configured as a tool holder 32. The tool holder 32 is configured to hold the tip tool 91 coaxially and detachably. The long axis of the spindle 3 defines the drive axis A2 of the tip tool 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 extending direction of the drive axis A2 (hereinafter also referred to as the drive axis direction).

[0023] The handle 17 is a long, hollow body held by the user. One axial end of the handle 17 is connected to the other end of the tool body 10 in the drive shaft direction (the end opposite to the end where the tool holder 32 is located). The handle 17 extends from the other end of the tool body 10 in a direction intersecting (more specifically, approximately orthogonal) the drive shaft A2. A power cord 179 extends from the protruding end of the handle 17, allowing connection to an external AC power source. 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, and the drive mechanism 4 is driven, thereby performing an impact action and / or a rotational action.

[0024] The detailed structure of the hammer drill 1A will now be described. For convenience, in the following description, the extension direction of the drive axis A2 (the long axis direction of the tool body 10) will be defined as the front-rear direction of the hammer drill 1A. In the front-rear direction, the side where the tool holder 32 is located will be defined as the front side of the hammer drill 1A, and the opposite side (the side connected to the handle 17) will be defined as the rear side. Furthermore, the direction orthogonal to the drive axis A2 and approximately corresponding to the long axis direction of the handle 17 will be defined as the vertical direction of the hammer drill 1A. In the vertical direction, the side where the handle 17 is connected to the tool body 10 will be defined as the upper side, and the protruding end side of the handle 17 will be defined as the lower side. Additionally, the direction orthogonal to both the front-rear and vertical directions will be defined as the left-right direction.

[0025] First, the detailed structure of the tool body 10 will be explained.

[0026] like Figure 1 As shown, the tool body 10 has a cylindrical front end. This cylindrical portion is referred to as the cylindrical portion 131. The portion of the tool body 10 other than the cylindrical 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, which is arranged inside the tool body 10 in a manner intersecting the drive axis A2. In this embodiment, the partition wall 15 is embedded in the inner periphery of the tool body 10 and is held in a fixed position by the tool body 10 (it cannot move substantially relative to the tool body 10). However, the partition wall 15 may also be formed integrally with the tool body 10 (as part of the tool body 10).

[0027] The space behind the partition wall 15 primarily houses the motor 2. The space in front of the partition wall 15 primarily houses the spindle 3 and the drive mechanism 4. Hereinafter, the portion of the tool body 10 corresponding to the space behind the partition wall 15 (i.e., the space housing the motor 2) will be referred to as the rear housing portion 11. The portion of the tool body 10 corresponding to the space in front of the partition wall 15 (i.e., the space housing the spindle 3 and the drive mechanism 4) (including the cylindrical portion 131) will be referred to as the front housing portion 13. Since the spindle 3 and the drive mechanism 4 require lubrication, a lubricant (e.g., grease) is placed in the front housing portion 13. The partition wall 15 substantially isolates the internal space of the rear housing portion 11 (the space housing the motor 2) from the lubricant. Furthermore, the partition wall 15 also functions as a support for bearings of various shafts, as will be described in detail later.

[0028] The following is an explanation of the structure (structural elements) within the main body 10 of the tool.

[0029] like Figure 1 As shown, in addition to the motor 2, a fan 27, a braking device 6, and a solenoid 8 are also arranged in the rear housing 11. Furthermore, as described above, the main shaft 3 and the drive mechanism 4 are housed in the front housing 13. These structural elements will now be described in detail.

[0030] In this embodiment, motor 2 is a brushed motor, driven by electrical power supplied from an external AC power source. Figure 1 As shown, the motor 2 has a motor body 20 and a motor shaft 25. The motor 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 is configured to extend from the rotor 23 and rotate integrally with the rotor 23. In this embodiment, the rotation axis A1 of the motor shaft 25 extends parallel to the drive axis A2 directly below it. An imaginary plane P containing the drive axis 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 on the tool body 10 by two bearings 251 and 252 in a manner that allows it to rotate about the rotation axis A1. The front bearing 251 is supported by a partition wall 15. The rear bearing 252 is supported at the rear end of the tool body 10 (more specifically, the motor housing of the motor body 20 is housed in the rear receiving portion 11). The front end of the motor shaft 25 passes through the partition wall 15 and protrudes into the front receiving portion 13. A drive gear 461 is fixed to the portion protruding into the front receiving portion 13.

[0032] The fan 27 is fixed in the part between the motor body 20 and the front bearing 251 (partition wall 15) in the motor shaft 25. More specifically, the fan 27 is arranged adjacent to the motor body 20 in front of the motor body 20. The fan 27 generates an airflow for cooling the motor 2 by rotating integrally with the motor shaft 25.

[0033] The braking device 6 is disposed between the motor 2 and the drive mechanism 4 in the power transmission path. More specifically, the braking device 6 is disposed between the motor body 20 and the bearing 251 in the extending direction (i.e., the front-to-back direction) of the motor shaft 25. More specifically, the braking device 6 is disposed between the fan 27 and the bearing 251 (partition wall 15) (i.e., on the side opposite to the motor body 20 across the fan 27). Although detailed illustrations are omitted, in this embodiment, an air inlet is provided at the rear of the tool body 10 (rear receiving portion 11), and an exhaust port is provided around the braking device 6. Therefore, as the fan 27 rotates, the air flowing into the tool body 10 from the air inlet flows forward in the rear receiving portion 11 while cooling the motor 2 and the braking device 6, and flows out from the exhaust port. Thus, in this embodiment, a configuration that efficiently cools the motor 2 and the braking device 6 can be achieved.

[0034] The braking device 6 is configured to brake the motor shaft 25 by operating the solenoid 8 when the main shaft 3 becomes stuck in a state where it cannot rotate (locked state) for some reason. The solenoid 8 is disposed above the motor 2 within the rear receiving portion 11. The braking device 6 and the solenoid 8 will be described in detail later.

[0035] Spindle 3 is the final output shaft of hammer drill 1A. For example... Figure 1 As shown, the spindle 3 is disposed within the front receiving portion 13 and supported on the tool body 10 in a manner that allows it to rotate about the drive axis A2. The front half of the spindle 3 constitutes a tool holder 32. The tip tool 91 is inserted into the front end of the tool holder 32 with its long axis aligned with the drive axis A2. The tip tool 91 is held by the tool holder 32 in a state that allows the tip tool 91 to move axially relative to the tool holder 32 while restricting the tip tool 91 from rotating about the axis. The rear half of the spindle 3 constitutes a cylinder 33 that slidably holds the piston 413, which will be described later.

[0036] The drive mechanism 4 is configured to be operatively connected to the motor 2 (motor shaft 25) and to drive the tip tool 91 via the power of the motor 2. In this embodiment, the drive mechanism 4 includes an impact mechanism 41 configured to perform an impact action and a rotation transmission mechanism 46 configured to perform a rotation action. The impact mechanism 41 is configured to drive the tip tool 91 linearly along the drive axis A2 by converting the rotational motion of the motor shaft 25 into linear motion and transmitting it to the impact structure element. The rotation transmission mechanism 46 is configured to drive the tip tool 91 to rotate about the drive axis A2 by transmitting the torque of the motor shaft 25 to the spindle 3.

[0037] Although detailed illustrations and descriptions are omitted, in this embodiment, in the impact mechanism 41, a swinging member that oscillates in the back-and-forth direction in response to the rotation of the motor shaft 25 causes the piston 413 to reciprocate within the cylinder 33 along the drive axis A2. The striker 415 impacts the tip tool 91 in response to the reciprocating motion of the piston 413, thereby driving the tip tool 91 linearly. 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 movably connected to the aforementioned gear. The rotation transmission mechanism 46 rotates the spindle 3 (tool holder 32) in response to the rotation of the motor shaft 25. Furthermore, the impact mechanism 41 and the rotation transmission mechanism 46 may each employ any known structure different from the example described above.

[0038] Furthermore, in this embodiment, the hammer drill 1A has three operating modes: an impact mode that only performs impact action, a rotation mode that only performs rotational action, and a rotational impact mode that performs both impact and rotational action. Although detailed illustrations and explanations are omitted, the drive mechanism 4 operates in response to the operating mode selected by the user through the operating components.

[0039] The following describes the structure (structural elements) within the handle 17.

[0040] A trigger 171 is disposed at the upper end of the handle 17. Inside the handle 17, adjacent to the rear side of the trigger 171, a switch 172 is disposed. The switch 172 is configured to remain open under normal conditions and to be turned on in response to pressing the trigger 171.

[0041] Additionally, a controller (control unit) 5 is located below the switch 172 within the handle 17. Although detailed illustrations are omitted, the controller 5 includes a control circuit 51 mounted on a circuit board, an acceleration sensor 53, and the like. 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, solenoid 8, etc., via wires not shown. In this embodiment, when the switch 172 is in the ON state, the control circuit 51 of the controller 5 drives the motor 2. In addition, the control circuit 51 is configured to start the solenoid 8 based on the detection result of the acceleration sensor 53, so as to activate the braking device 6. Details will be described later.

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

[0044] like Figures 2-5 As shown, the braking device 6 has a brake rotor 61, a braking component 63, a force-applying component 65, and a pressing component 67.

[0045] The brake disc 61 is fixed to the motor shaft 25 between the fan 27 and the bearing 251, and rotates integrally with the motor shaft 25 about the rotation axis A1. The brake disc 61 includes a sleeve 611 fixed to the motor shaft 25 and a disc-shaped portion 615 protruding radially outward from the sleeve 611. The front surface 617 of the annular outer periphery of the disc portion 615 is configured to be substantially orthogonal to a straight line extending in the front-rear direction. The brake disc 61 is formed of metal (e.g., iron).

[0046] A braking component 63 is disposed on the front side of the brake disc 61 (between the brake disc 61 and the bearing 251). The braking component 63 is configured to move linearly in the front-rear direction relative to the motor shaft 25 and the brake disc 61. In this embodiment, the braking component 63 is generally an annular component with an opening in the center and is disposed around the motor shaft 25. The braking component 63 is configured to brake the motor shaft 25 by frictional engagement with the brake disc 61, and the braking component 63 includes a support plate 631 and a friction element 636.

[0047] The support plate 631 includes an annular central portion and a plurality of protrusions 634 projecting radially outward from the central portion. The protrusions 634 are spaced apart from each other in the circumferential direction about the rotation axis A1. Guide holes 635 are provided on three of the protrusions 634 (specifically, the lower, upper left, and upper right protrusions 634). On the other hand, three guide pins 151 are fixed to the partition wall 15, corresponding to the guide holes 635, and protrude rearward. Since the partition wall 15 cannot move substantially relative to the tool body 10, it can also be said that the guide pins 151 are fixed to the tool body 10. The guide pins 151 are slidably inserted into the guide holes 635, stably guiding the movement of the braking component 63 relative to the motor shaft 25 and the brake disc 61 in the front-rear direction. Furthermore, the support plate 631 is formed of metal (e.g., iron).

[0048] The friction element 636 is formed in an annular shape. The friction element 636 has a size and shape that substantially matches the outer periphery of the brake disc 61 and is fixed to the rear surface of the central portion of the support plate 631. The rear surface 637 of the friction element 636 of the brake component 63 is arranged substantially parallel to and opposite to the front surface 617 of the brake disc 61. The rear surface 637 is a friction surface capable of frictionally engaging with the front surface 617 of the brake disc 61. Alternatively, the brake component 63 may be formed as a single component made of metal (e.g., iron), whose rear surface is capable of frictionally engaging with the front surface 617 of the brake disc 61.

[0049] The force-applying component 65 is configured to apply force to the braking component 63 in a direction away from the brake disc 61 (i.e., forward). In this embodiment, the four force-applying components 65 are arranged spaced apart from each other in the circumferential direction about the rotation axis A1. More specifically, the four force-applying components 65 are located in the aforementioned plane P (refer to...) Figure 4 Two force-applying components 65 are arranged substantially symmetrically on the left and right sides of the tool body 10. Additionally, two force-applying components 65 are arranged above and below the rotation axis A1. In this embodiment, the force-applying components 65 are compression coil springs. The force-applying components 65 are arranged in a compressed state between the tool body 10 (spring support portion 113 of the rear receiving portion 11) and the braking component 63 (protrusion 634) in the front-rear direction, always applying a forward force to the braking component 63 relative to the tool body 10.

[0050] The pressing member 67 is configured to be operatively connected to the solenoid 8 (described later) and to move (more specifically, rotate) in response to the actuation of the solenoid 8, thereby overcoming the force of the force-applying member 65 and pressing the braking member 63 against the brake disc 61. In this embodiment, the pressing member 67 is generally a home-base pentagonal frame-shaped member with a shape that is generally symmetrical with respect to the plane P. Furthermore, the pressing member 67 is made of metal.

[0051] The pressing component 67 has two fulcrum protrusions 671, two pressing protrusions 673, and a locking hole 675.

[0052] Each fulcrum protrusion 671 is a forward-projecting protrusion. The cross-sectional shape of the fulcrum protrusion 671 when cut with a section orthogonal to the left-right direction is approximately semi-circular. The two fulcrum protrusions 671 are separated in the left-right direction at the lower end of the pressing member 67. Furthermore, the fulcrum protrusions 671 are substantially symmetrically arranged with respect to the plane P.

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

[0054] The engaging hole 675 is a hole that penetrates the upper end of the pressing member 67 in the front-to-back direction. An elongated connecting member 68 is inserted into the engaging hole 675 and extends in the front-to-back direction. The connecting member 68 is a rod-shaped component, and a disc-shaped head 681 with a diameter larger than the engaging hole 675 is fixed to its front end. The connecting member 68 is inserted into the engaging hole 675 with its head 681 positioned in front of the pressing member 67. The rear end of the connecting member 68 is connected to the plunger 83 of the solenoid 8, which will be described later.

[0055] The pressing member 67 is rotatably disposed between the braking member 63 and the partition wall 15 in the front-rear direction. More specifically, as... Figure 5 As shown, two recesses 153 are formed separately in the left-right direction at the lower end of the partition wall 15. Each recess 153 is formed with a semi-circular cross-section that matches the fulcrum protrusion 671. The fulcrum protrusion 671 engages with the recess 153. With this structure, the pressing member 67 can rotate relative to the tool body 10 and then relative to the braking member 63 in the front-back direction with the two fulcrum protrusions 671 as fulcrums (about the axis extending in the left-right direction). The two pressing protrusions 673 are respectively positioned in the front-back direction facing the braking member 63 (specifically, the left and right central portions of the support plate 631).

[0056] As described above, since the force-applying member 65 always applies a forward force to the braking member 63, the pressing member 67 is also applied a forward force via the braking member 63. Therefore, as Figure 5 As shown, the pressing member 67 is always held in the position where its upper end (the part below the engagement hole 675) abuts against the limiting member 155 provided on the partition wall 15 from the rear (hereinafter also referred to as the initial position).

[0057] Furthermore, the brake member 63 is held in a position where its front surface 633, located at the center of the support plate 631, abuts against the pressing protrusion 673 of the pressing member 67 from the rear. Moreover, the pressing protrusion 673 abuts against the brake member 63 approximately at its center in the vertical direction, symmetrically with respect to plane P. At this time, the rear surface (friction surface) 637 of the friction element 636 of the brake member 63 moves forward away from the front surface 617 of the outer periphery of the brake disc 61. The position of the brake member 63 when the pressing member 67 is in its initial position (when the rear surface 637 is separated from the front surface 617) will also be described below. Figure 5The position shown is called the separation position.

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

[0059] like Figure 1 and Figure 5 As shown, the solenoid 8 is disposed radially outside the motor body 20 within the tool body 10. More specifically, the solenoid 8 is disposed directly above the motor body 20 within the rear receiving portion 11. In this embodiment, since the rotation axis A1 of the motor shaft 25 is located below the drive axis A2, a space is formed directly above the motor body 20 within the rear receiving portion 11. Therefore, this space is utilized efficiently as the placement space for the solenoid 8.

[0060] A solenoid is a well-known electrical component that converts electrical energy into mechanical energy for linear motion by utilizing the magnetic field generated when current flows through a coil. A solenoid can also be called a solenoid actuator, linear solenoid, etc.

[0061] Detailed illustrations omitted. The solenoid 8 includes a coil housed within a frame and a plunger 83 capable of linear movement in response to energizing the coil. The solenoid 8 is configured such that the axis of movement A3 of the plunger 83 extends substantially parallel (i.e., in the front-to-back direction) to the axis of rotation A1. This configuration allows for the most efficient use of the space directly above the motor body 20. The front end of the plunger 83 protrudes forward from the frame and connects to the rear end of the connecting member 68. That is, the plunger 83 and the pressing member 67 are movably connected via the connecting member 68.

[0062] In this embodiment, the solenoid 8 is a so-called pull solenoid, and the plunger 83 is always positioned at the foremost position. Figure 5 (as shown in the image). When current flows through the coil, as... Figure 6 As shown, the plunger 83 moves backward in a straight line along the moving axis A3, and the connecting part 68 also moves backward in a straight line as part of the plunger 83.

[0063] As the plunger 83 moves rearward, the head 681 at the front end of the connecting member 68 stretches the upper end of the pressing member 67 rearward. Accordingly, the pressing member 67 overcomes the force of the force-applying member 65 and rotates rearward (clockwise when viewed from the left) from its initial position, using the fulcrum protrusion 671 as a fulcrum. The pressing member 67 rotates while the pressing protrusion 673 is in contact with the braking member 63, thereby moving the braking member 63 rearward and pressing it against the brake disc 61. The position of the pressing member 67 at this time will be described below. Figure 6 The position shown is called the pressing position.

[0064] During the rotation of the pressing member 67, the braking member 63 is guided by the guide pin 151 and moves rearward in a straight line with the rear surface 637 of the friction member 636 substantially parallel to the front surface 617 of the brake disc 61. Furthermore, through the arrangement of the force-applying member 65 and the pressing protrusion 673, the pressing member 67 can respond to rotation and overcome the force of the force-applying member 65 to press the braking member 63 in a balanced and good manner, causing it to move.

[0065] The braking component 63 is pressed against the brake disc 61, and the rear surface 637 of the braking component 63 abuts and frictionally engages with the front surface 617 of the brake disc 61. In response, the braking component 63 brakes the motor shaft 25 via the brake disc 61. Furthermore, frictional engagement refers to engagement through frictional force, and also includes the concept of engagement in a sliding state. The position of the braking component 63 in which the rear surface 637 of the braking component 63 frictionally engages with the front surface 617 of the brake disc 61 will be described below. Figure 6 The position shown is called the contact position.

[0066] The operation of hammer drill 1A will be explained below.

[0067] As described above, when trigger 171 is pressed and switch 172 is turned on, control circuit 51 of controller 5 powers motor 2, starting the drive of motor 2. Drive mechanism 4 operates in response to the selected operating mode.

[0068] During the operation of the drive motor 2, the control circuit 51 determines whether a locking state has occurred based on the acceleration detected by the accelerometer 53 (the signal from the accelerometer 53). The acceleration detected by the accelerometer 53 is a physical quantity (indicator) representing the rotational state of the tool body 10 about the drive axis A2, and thus the locking state of the spindle 3. Furthermore, any method can be used to determine whether a locking state has occurred. For example, a method can be used to determine that a locking state has occurred if the detected acceleration, or a value calculated based on the acceleration (e.g., angular acceleration), exceeds a predetermined threshold.

[0069] When a locked state is detected (i.e., when a locked state is detected), the control circuit 51 stops energizing the motor 2, thus stopping the drive of the motor 2. Additionally, the control circuit 51 activates the solenoid 8 at essentially the same moment as the energization of the motor 2 is stopped (or just before or immediately after the energization is stopped), thereby engaging the braking device 6. As described above, the plunger 83 and the connecting member 68 are pulled rearward, and the braking member 63 is moved from the disengaged position to the engaged position by pressing the member 67 (see reference). Figure 6 ).

[0070] Even after power to the motor 2 is stopped, the rotor 23 and motor shaft 25 of the motor 2 will continue to rotate due to inertia. In contrast, the braking member 63, positioned at the contact position, brakes the motor shaft 25 of the motor 2 by frictionally engaging with the brake disc 61. The brake disc 61, while sliding relative to the braking member 63, decelerates and rotates together with the motor shaft 25, then stops rotating. By stopping the rotation of the motor shaft 25, the operation of the drive mechanism 4 also stops. Furthermore, since the motor 2 in this embodiment is a brushed motor, it is more difficult to perform electrical braking compared to a brushless DC motor. Therefore, in this embodiment, a mechanical braking device 6 is used, employing a structure that rapidly stops the motor shaft 25 after power to the motor 2 is stopped.

[0071] Subsequently, when the trigger 171 is released and the switch 172 is disconnected, the control circuit 51 stops energizing the solenoid 8. Alternatively, the control circuit 51 may also stop energizing after a predetermined time elapsed since the plunger 83 was activated. Accordingly, the plunger 83 returns to its forward position. In response to the plunger 83 returning to its forward position, the braking component 63 returns to its disengaged position from the contact position by the force applied by the force application component 65, and the pressing component 67 returns to its initial position from the pressed position (see reference). Figure 5 ).

[0072] As described above, in this embodiment, if the spindle 3, which serves as the final output shaft of the hammer drill 1A, becomes locked for some reason, the braking device 6, acting as a safety device, directly acts on the motor shaft 25 to brake it. This prevents the tool body 10 from excessively rotating around the drive axis A2 due to the reaction torque. Furthermore, the braking device 6 is configured to act directly on the motor shaft 25. Therefore, compared to the case where the braking device acts directly on the spindle 3, which serves as the final output shaft, a smaller force can be used to brake the motor shaft 25 to suppress excessive rotation of the tool body 10.

[0073] Furthermore, the braking device 6 is positioned between the motor 2 and the drive mechanism 4 (rotational transmission mechanism 46) in the power transmission path, thus enabling efficient braking of the motor shaft 25 at a position relatively close to the motor 2. Additionally, compared to the case where the braking device acts directly on the main shaft 3, it can be positioned in a location less susceptible to the effects of lubricant. In particular, in this embodiment, the braking device 6 is positioned within the rear receiving portion 11, which is divided relative to the front receiving portion 13 where lubricant is disposed, by the partition wall 15. Therefore, the braking device 6 can be easily and reliably isolated from the lubricant.

[0074] In this embodiment, the solenoid 8, operably connected to the braking device 6 (pressing member 67), activates the braking device 6. More specifically, the control circuit 51 of the controller 5 activates the solenoid 8 in response to detecting a locked state, thereby activating the braking device 6. The solenoid 8 is a relatively inexpensive electrical component. Therefore, a structure that allows the braking device 6 to operate rapidly in response to detecting a locked state can be achieved at a lower cost. Furthermore, since the solenoid 8, as an electrical component, is also disposed within the rear receiving portion 11, it can be protected from the effects of lubricant, and the solenoid 8 and the braking device 6 (pressing member 67) can be easily connected. Additionally, the braking device 6 and the solenoid 8 can be configured as a whole within a smaller space.

[0075] In this embodiment, the brake disc 61 and the brake member 63 brake the motor shaft 25 by frictional engagement. The brake member 63 is normally positioned in the disengaged position by the force-applying member 65, but in response to a detected locked state, it is moved to the contact position by the pressing member 67 and pressed against the brake disc 61 for frictional engagement. In this embodiment, a reasonable structure for braking the motor shaft 25 can be achieved simply by moving the pressing member 67 in response to the actuation of the solenoid 8. In particular, in this embodiment, the pressing member 67 rotates around the pivot protrusion 671, thereby causing the brake member 63 to move linearly, enabling effective contact between the rear surface 637 of the brake member 63 and the front surface 617 of the brake disc 61 over a relatively wide range.

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

[0077] Hammer drill 1A is an example of a "power tool". Motor 2, motor body 20, stator 21, rotor 23, and motor shaft 25 are examples of "motor", "motor body", "stator", "rotor", and "motor shaft", respectively. Rotation axis A1 is an example of a "first rotation axis". Spindle 3 (tool holder 32) is an example of a "final output axis". Drive axis A2 is an example of a "second rotation axis". Tool body 10 is an example of a "tool body". Controller 5 (control circuit 51) is an example of a "detection device". Braking device 6 is an example of a "braking device".

[0078] Drive mechanism 4 (rotation transmission mechanism 46) is an example of a "transmission mechanism". Fan 27 is an example of a "fan". Solenoid 8 is an example of a "sowary". Brake disc 61 is an example of a "first rotating component". Braking component 63, force-applying component 65, and pressing component 67 are examples of "braking component", "first force-applying component", and "pressing component", respectively. Front surface 617 of brake disc 61 is an example of a "first surface of the first rotating component". Rear surface 637 of brake component 63 is an example of a "second surface of the brake component".

[0079] [Second Implementation] Below, refer to Figures 7-10 The hammer drill 1B according to the second embodiment will be described. The hammer drill 1B has a braking device 7 that differs from the braking device 6 of the hammer drill 1A in the first embodiment. Furthermore, the connection method between the braking device 7 and the solenoid 8 also differs from that in the first embodiment. On the other hand, apart from these structures, the hammer drill 1B has a substantially identical structure to the hammer drill 1A. Therefore, in the following description, substantially identical structures will be labeled with the same reference numerals as in the first embodiment, and illustrations and descriptions will be appropriately omitted or simplified; the main focus will be on describing features that differ from the first embodiment.

[0080] like Figures 7-9 As shown, the braking device 7 of the hammer drill 1B is arranged between the fan 27 and the bearing 251 (partition wall 15) in the extending direction (i.e., the front-to-back direction) of the motor shaft 25 (i.e., on the side opposite to the motor body 20 across the fan 27). The solenoid 8 is arranged directly above the motor 2 in the rear receiving portion 11.

[0081] The braking device 7 has a first brake disc 71, a second brake disc 72, a force-applying component 75, and a limiting component 77.

[0082] The first brake disc 71 is fixed to the motor shaft 25 between the fan 27 and the bearing 251, and rotates integrally with the motor shaft 25 about the rotation axis A1. The first brake disc 71 includes a sleeve 711 fixed to the motor shaft 25 and a disc-shaped portion 715 protruding radially outward from the sleeve 711. The first brake disc 71 is formed of metal (e.g., iron).

[0083] The second brake disc 72 is integrally formed in an annular shape. The outer diameter of the second brake disc 72 is larger than the outer diameter of the disc portion 715 of the first brake disc 71. A recess that substantially matches the disc portion 715 is formed on the front surface side of the second brake disc 72. The second brake disc 72 is disposed on the rear side of the first brake disc 71 and is embedded from the rear side into the outer periphery of the disc portion 715. The second brake disc 72 is formed of metal (e.g., iron). In addition, two protrusions 725 protruding radially outward are provided on the second brake disc 72. The two protrusions 725 have the same shape and are arranged diagonally across the axis of rotation A1.

[0084] The force-applying member 75 is configured to apply force to the second brake disc 72 against the first brake disc 71 and press it onto the first brake disc 71. In this embodiment, the force-applying member 75 is a disc spring that saves space and can perform high loads. The force-applying member 75 is disposed between the second brake disc 72 and the retaining ring 712 in a compressed state in the front-rear direction. The retaining ring 712 is fixed to the sleeve 711 of the first brake disc 71 on the rear side of the second brake disc 72. The rear surface 717 of the outer periphery of the disc portion 715 of the first brake disc 71 and the front surface 722 (bottom surface of the recess) of the second brake disc 72 are always in frictional engagement through the force of the force-applying member 75. Therefore, the second brake disc 72 also rotates in response to the rotation of the motor shaft 25 and the first brake disc 71. Furthermore, similar to the first embodiment, a friction member may also be fixed to one of the first brake disc 71 and the second brake disc 72.

[0085] The limiting member 77 is configured to be operatively connected to the solenoid 8 and to move (specifically, linearly) in response to the actuation of the solenoid 8, thereby interfering with (aggregating with) the second brake disc 72 and stopping the rotation of the second brake disc 72. In this embodiment, the limiting member 77 is a cylindrical pin, and its movement axis A4 is arranged to extend parallel to the rotation axis A1 (i.e., in the front-rear direction).

[0086] The front portion of the limiting member 77 is configured to slide in the front-rear direction within a guide hole 157 formed on the partition wall 15. Additionally, 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 the guide member 16, located behind and facing the guide hole 157. The limiting member 77 can slide in the front-rear direction within the guide hole 161. The guide holes 157 and 161 stably guide the movement of the limiting member 77 in the front-rear direction. Furthermore, the movement axis A4 of the limiting member 77 intersects the movement path of the protrusion 725 (the area traversed by the protrusion 725) when the second brake disc 72 rotates.

[0087] The connection method between the braking device 7 (limiting member 77) and the solenoid 8 will be explained below.

[0088] like Figure 8 As shown, the limiting member 77 and the plunger 83 of the solenoid 8 are movably connected via a connecting member 78. The connecting member 78 is a plate-shaped member bent into an L-shape when viewed from the side, and includes a first portion 781 extending in the front-rear direction and a second portion 782 extending 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 limiting member 77 is supported by the connecting member 78 in a state where it can slide through the support hole 783 in the front-rear direction.

[0089] A flange 771 protruding radially outward is provided at approximately the center of the limiting member 77 in the front-rear direction (the portion always disposed outside the guide hole 157). The limiting member 77 is inserted into the support hole 783 with the flange 771 facing the rear surface of the second portion 782. In the front-rear direction, a force-applying member 79 is disposed between the guide member 16 and the flange 771. The force-applying member 79 is a compression coil spring. The force-applying member 79 is externally mounted on the limiting member 77 in a compressed state with its front end abutting against the flange 771 and its rear end abutting against the guide member 16. Therefore, the limiting member 77 is always subjected to force by the force-applying member 79 in a direction away from the guide member 16 (front), and the flange 771 is held in the position abutting 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 component 78 are in their foremost positions within their respective movable ranges. Therefore, the limiting member 77 is also in its foremost position within its movable range. At this time, the rear end of the limiting member 77 is positioned forward of the second brake disc 72. Therefore, the limiting member 77 is not located on the movement path of the protrusion 725 of the second brake disc 72. That is, even if the second brake disc 72 rotates, the limiting member 77 will not physically interfere with the protrusion 725. Therefore, the foremost position of the limiting member 77 will be described below (…). Figure 8 The position shown is called the non-interference position.

[0091] When current flows through the coil, the plunger 83 moves rearward in a straight line along the moving axis A3. The connecting member 78 moves rearward in a straight line integrally with the plunger 83, causing the limiting member 77 to move rearward in a straight line along the moving axis A4, overcoming the force of the force-applying member 79. Figure 10 As shown, in response to the actuation of the solenoid 8, when the limiting member 77 moves to its rearmost position within its movable range, the rear end of the limiting member 77 is located further rearward than the rear end of the second brake disc 72. The limiting member 77 is positioned on the movement path of the protrusion 725, and when the second brake disc 72 rotates, the limiting member 77 physically interferes (abuts) with the protrusion 725. Therefore, the rearmost position of the limiting member 77 will also be described below. Figure 10The position shown is called the interference position. The limiting member 77 abuts against the protrusion 725 of the second brake disc 72 at the interference position, thereby stopping the rotation of the second brake disc 72 and braking the motor shaft 25 via the first brake disc 71.

[0092] The operation of hammer drill 1B will be explained below.

[0093] When trigger 171 is pressed and switch 172 is turned on, control circuit 51 of controller 5 powers motor 2, starting the drive of motor 2. Drive mechanism 4 operates in response to the selected operating mode.

[0094] During the operation of the motor 2, the control circuit 51 determines whether a locking state has occurred based on the acceleration detected by the acceleration sensor 53 (signal from the acceleration sensor 53). When the control circuit 51 determines that a locking state has occurred (i.e., when a locking state is detected), it stops energizing the motor 2, thus stopping the drive of the motor 2. Furthermore, the control circuit 51 activates the braking device 7 by starting the solenoid 8 at substantially the same moment as stopping energizing the motor 2 (or just before or immediately after stopping energizing). As described above, the plunger 83 and the connecting member 78 are pulled rearward, and the limiting member 77 moves from the non-interference position to the interference position (see reference). Figure 10 ).

[0095] Even if power to motor 2 is stopped, the rotor 23 and motor shaft 25 of motor 2 will continue to rotate due to inertia. In contrast, the limiting member 77, positioned in the interference position, abuts against the second brake disc 72, immediately stopping its rotation. When the second brake disc 72 stops rotating, the first brake disc 71, while sliding relative to the second brake disc 72, decelerates and rotates together with the motor shaft 25 before stopping. In this embodiment, an impact is generated due to the contact (collision) between the limiting member 77 and the second brake disc 72 (protrusion 725). In contrast, this impact is buffered by the sliding between the second brake disc 72 and the first brake disc 71, which is integrated with the motor shaft 25. Since the rotation of the motor shaft 25 stops, the operation of the drive mechanism 4 also stops.

[0096] Then, when the control circuit 51 stops energizing the solenoid 8, the plunger 83 resets to its foremost position. In response to the plunger 83 resetting to its foremost position, the connecting member 78 also resets to its foremost position, and through the force of the force-applying member 79, the limiting member 77 resets from the interference position to the non-interference position (see...). Figure 8 ).

[0097] As explained above, in this embodiment, similar to the first embodiment, when the spindle 3 becomes locked for some reason, in response to the starting of the solenoid 8, the braking device 7, acting as a safety device, directly acts on the motor shaft 25 to brake it. This prevents the tool body 10 from excessively rotating around the drive axis A2 due to the reaction torque. Furthermore, since the braking device 7 is configured to act directly on the motor shaft 25, compared to the case where it acts directly on the spindle 3, a smaller force is used to brake the motor shaft 25, thereby preventing excessive rotation of the tool body 10. Additionally, in this embodiment, since the braking device 7 and the solenoid 8 are disposed within the rear receiving portion 11, similar to the first embodiment, it is possible to protect the braking device 7 and the solenoid 8 from the effects of lubricant and to facilitate connection between the solenoid 8 and the braking device 7 (limiting member 77).

[0098] Furthermore, in this embodiment, the first brake disc 71 and the second brake disc 72 are always pressed and frictionally engaged against each other by the force of the force-applying member 75, and rotate as a whole to transmit torque. In response to detecting a locked state, the limiting member 77 moves from a non-interference position to an interference position, stopping the rotation of the second brake disc 72, thereby braking the motor shaft 25 via the first brake disc 71. In this embodiment, a reasonable structure capable of braking the motor shaft 25 can be achieved simply by moving the limiting member 77 in response to the start of the solenoid 8. Additionally, on the second brake disc 72, two protrusions 725 are arranged diagonally (i.e., at equal intervals in the circumferential direction) that can interfere with the limiting member 77 located in the interference position. This suppresses imbalance during rotation and allows the second brake disc 72 to stop quickly via the limiting member 77.

[0099] The correspondence between the structure (features) of the second embodiment and the structure (features) of the present invention is shown below. However, the structure (features) of the embodiment are merely examples and do not limit the present invention or its structure (features). Furthermore, structures substantially the same as those of the first embodiment are omitted from description.

[0100] Hammer drill 1B is an example of a "power tool". Braking device 7 is an example of a "braking device". First brake disc 71 is an example of a "first rotating component". Second brake disc 72, force-applying component 75, and limiting member 77 are examples of a "second rotating component", "second force-applying component", and "limiting member", respectively. Force-applying component 75 is an example of a "disc spring". Protrusion 725 is an example of an "interference part".

[0101] Furthermore, the above embodiments are merely illustrative, and the power tools involved in this invention are not limited to the hammer drills 1A and 1B exemplified in the above embodiments. For example, non-limiting modifications illustrated below can be added. In addition, at least one of these modifications can be combined with at least a portion of the structure (feature) of the hammer drills 1A and 1B, or at least one of the structure (feature) described in the technical solution.

[0102] For example, in the above embodiments, hammer drills 1A and 1B, which are capable of both rotary and impact actions, are listed as specific examples of power tools having a final output shaft configured for rotary drive. However, the power tools according to the present invention can be implemented as electric drills capable only of rotary action or fastening tools capable of tightening nuts and bolts. Furthermore, hammer drills having both impact and rotary impact action modes can also be applied, for example.

[0103] Hammer drills 1A and 1B can also be configured to operate using electrical power supplied from a rechargeable battery instead of an external AC power source. In this case, for example, a battery mounting section for removable batteries can be provided at the lower end of the handle 17 to replace the power cord 179.

[0104] Motor 2 can also be configured such that the rotation axis A1 of motor shaft 25 intersects with the drive axis A2. In response to changes in the configuration of motor 2, the structure of tool body 10 can also be changed. For example, tool body 10 can also be formed in an L-shape. Furthermore, the internal space of tool body 10 does not need to be divided by partition wall 15; it can be divided at other locations. Additionally, within tool body 10, braking devices 6 and 7 are preferably disposed in spaces without lubricant.

[0105] The structure and configuration of the fan 27, the airflow path (inlet) within the tool body 10, and the configuration of the exhaust port may differ from the examples described in the above embodiments. For example, the fan 27 may be configured behind the motor body 20. Furthermore, for example, the fan 27 may be a fan capable of drawing in air from both axial directions (front and rear).

[0106] In the above embodiment, an example was described where the control circuit 51 of the controller 5 detects the occurrence of a locking state based on the acceleration detected by the accelerometer 53. However, the hammer drills 1A and 1B may also have other types of detectors (e.g., velocity sensors, angular velocity sensors, or angular acceleration sensors) capable of detecting the rotational state of the tool body 10 about the drive axis A2 instead of the accelerometer 53. Alternatively, the hammer drills 1A and 1B may have detectors that detect physical quantities different from the rotational state of the tool body 10 (e.g., the load acting on the tip tool 91), and the control circuit 51 may detect the occurrence of a locking state based on the detected physical quantity. In addition, the accelerometer 53 or other detectors may be provided separately from the controller 5 (control circuit 51). The control circuit 51 and the accelerometer 53 may also be provided within the tool body 10 instead of within the handle 17.

[0107] The structure of braking devices 6 and 7 (e.g., structural elements and the shape, quantity, and arrangement of each structural element) can be appropriately modified. Below are examples of modifications that can be used in braking devices 6 and 7.

[0108] On the braking component 63 of the braking device 6, multiple friction elements capable of frictionally engaging with the front surface 617 of the brake disc 61 may also be installed. Additionally, the braking component 63 may be configured to move radially along the brake disc 61, for example. Furthermore, the brake disc 61 and the braking component 63 may be configured such that, instead of surfaces orthogonal to the axis of rotation A1, they engage with each other through frictional contact, rather than through frictional contact between conical surfaces. The guiding structure of the braking component 63 may also be composed of a component different from the guide pin 151 (e.g., the inner wall portion of the tool body 10). The number of guide pins 151 may also be more than four.

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

[0110] The first brake disc 71 and the second brake disc 72 of the braking device 7 can also be configured such that their surfaces, which are not orthogonal to the axis of rotation A1, rub against each other, but rather their conical surfaces rub against each other. The second brake disc 72 can have one or more protrusions 725. However, to suppress imbalance during rotation of the second brake disc 72, it is preferable that the protrusions 725 are evenly spaced in the circumferential direction. Alternatively, the portion of the second brake disc 72 other than the protrusions can abut against the limiting member 77. For example, an arc-shaped groove can be formed on the disc-shaped second brake disc 72, and the limiting member 77 can engage with this groove to stop the rotation of the second brake disc 72.

[0111] The limiting member 77 can be any shape (e.g., prismatic) as long as it can interfere (abut) with the protrusion 725 at the interference position to stop the rotation of the second brake disc 72. The limiting member 77 can also be formed as a part of the connecting member 78. Alternatively, the limiting member 77 can be radially movable along the second brake disc 72 between the non-interference position and the interference position. The guiding structure of the limiting member 77 can also be formed by a part other than the partition wall 15 and the guiding member 16 (e.g., the inner wall of the tool body 10).

[0112] The connecting parts 68 and 78 may have shapes different from those described in the above embodiments, or they may be composed of multiple interconnected parts. Furthermore, the connection methods between the connecting part 68 and the pressing part 67, and between the connecting part 78 and the limiting member 77, may also differ from the examples described in the above embodiments.

[0113] The force-applying components 65 and 75 may also be springs of a different type than those in the examples described above (e.g., tension springs, torsion springs) or elastomers other than springs (e.g., thermoplastic elastomers). The number and arrangement of the force-applying components 65 and 75 may also differ from those in the examples described above.

[0114] The solenoid 8 may also be a push-type solenoid instead of a pull-type solenoid. In this case, for example, in the braking device 6, the braking member 63 (and the pressing member 67) can be positioned between the brake disc 61 and the solenoid 8 in the front-rear direction. Alternatively, in the braking device 7, the limiting member 77 may be initially positioned at the rearmost position where it does not interfere with the protrusion 725 of the second brake disc 72, and then moved to the foremost position where it can interfere with the protrusion 725 in response to the activation of the solenoid 8. Multiple solenoids 8 may also be provided.

[0115] Furthermore, in view of the spirit of the above embodiments and their variations, the present invention is constructed in the following manner. At least one of the following manner can be combined with the above embodiments and their variations, and at least one of the structures (features) described in each technical solution. [Method 1] The braking device described is a friction braking mechanism that exerts braking force through the frictional engagement between multiple components. [Method 2] At least the portion of the braking component that frictionally engages with the first rotating component is formed by a friction element. According to this method, the braking component can efficiently brake the first rotating component. Friction element 636 is an example of a "friction element". [Method 3] has at least one guide that guides the braking member to move linearly between a separation position and a contact position, wherein the separation position is the position where the second surface separates from the first surface of the first rotating member; and the contact position is the position where the second surface abuts against and rubs against the first surface. According to this method, the movement of the braking component can be stabilized. The guide pin 151 is an example of a "guide" in this method. [Method 4] The pressing component has a plurality of pressing protrusions that protrude toward the braking component and abut against the braking component. The pressing protrusion 673 is the "pressing protrusion" of this method. [Method 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, the transmission mechanism, and the lubricant are disposed, and the braking device is disposed in the second space. According to this method, the motor body and braking device can be reliably isolated from the lubricant by a partition wall. Partition wall 15 is an example of a "partition wall" in this method. The internal space of the rear receiving section 11 is an example of a "first space." The internal space of the front receiving section 13 is an example of a "second space." [Method 6] The partition wall is used to support the bearing, which supports the motor shaft in a rotatable manner. According to this method, a reasonable structure can be achieved that utilizes the partition wall dividing the first space and the second space as a support for the bearing. Bearing 251 is an example of the "bearing" in this method. [Method 7] The solenoid is disposed in the first space. According to this method, the braking device and solenoid are arranged together with the motor in a first space that does not require lubrication. Therefore, the connection between the solenoid and the braking device can be facilitated. [Method 8] The solenoid is arranged on a straight line orthogonal to the first rotation axis and passing through the motor body. According to this method, a solenoid is arranged radially outward of the motor body. Therefore, the solenoid and the braking device can be arranged relatively compactly in the extension direction of the first rotation axis (the rotation axis of the motor shaft). [Method 9] The solenoid has a working part configured to move linearly parallel to the first rotation axis and is operatively connected to the braking device. According to this method, the solenoid can be arranged relatively compactly in the radial direction of the motor body. The plunger 83 is an example of the "working part" of this method. [Method 10] The working part is configured to be operatively connected to the pressing member and to move the pressing member in response to actuation. [Method 11] The working part is configured to be operatively connected to the limiting member and to move the limiting member in response to actuation. [Method 12] The limiting member is configured to move in a straight line parallel to the extension direction of the first rotation axis. [Method 13] The detection device is configured to detect the locking state based on the rotational state of the tool body about the second rotation axis. When the final output shaft is locked, the tool body rotates about the second rotation axis. Therefore, according to this method, the detection device can properly detect the locked state. [Method 14] The power tool also has a detector that detects the rotational state of the tool body about the second rotation axis. Accelerometer 53 is an example of a "detector". [Method 15] The power tool also has a control device configured to start the solenoid in response to detecting the locked state. The control circuit 51 of the controller 5 is an example of the "control device" of this method. [Method 16] The first rotation axis is parallel to the second rotation axis.

Claims

1. A power tool, characterized in that, It includes: a motor, a final output shaft, a tool body, a detection device, and a braking device, among which, 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 the torque transmitted from the motor shaft; The tool body houses the motor and the final output shaft; The detection device is configured to detect the locking state of the final output shaft; The braking device is a mechanical braking device configured to directly act on the motor shaft in response to detecting the locked state, thereby braking the motor shaft. The braking device includes: (i) a first rotating component fixed to the motor shaft in a manner rotatable integrally with the motor shaft; (ii) a braking component; (iii) at least one first force-applying component that applies force to the braking component in a direction away from the first rotating component; and (iv) a pressing component. The pressing component is configured to rotate about a pivot point in response to detecting the locked state. At least a portion of the rotating pressing member presses the braking member. The pressed braking component overcomes the force of the at least one first force-applying component and is pressed against the first rotating component, thereby braking the motor shaft through frictional engagement with the first rotating component.

2. The power tool according to claim 1, characterized in that, It also includes a transmission mechanism configured to transmit the torque of the motor shaft to the final output shaft. The braking device is configured between the motor and the transmission mechanism in the power transmission path.

3. The power tool according to claim 1 or 2, characterized in that, It also includes a fan configured to be disposed between the motor body and the braking device in the extension direction of the first rotation axis, and to rotate integrally with the motor shaft. The fan is configured to generate an airflow for cooling the motor body and the braking device.

4. The power tool according to claim 1 or 2, characterized in that, It also includes a solenoid, which is operably connected to the braking device. The solenoid is configured to activate in response to the detection of the locked state, thereby engaging the braking device.

5. The power tool according to claim 1, characterized in that, The braking component has a second surface capable of frictionally engaging with the first surface of the first rotating component; The pressing member is configured such that the braking member moves linearly relative to the first rotating member while the first surface and the second surface are substantially parallel.

6. The power tool according to claim 1 or 2, characterized in that, The motor is a brushed motor.

7. A power tool, characterized in that, It includes: a motor, a final output shaft, a tool body, a detection device, and a braking device, among which, 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 the torque transmitted from the motor shaft; The tool body houses the motor and the final output shaft; The detection device is configured to detect the locking state of the final output shaft; The braking device is a mechanical braking device configured to directly act on the motor shaft in response to detecting the locked state, thereby braking the motor shaft. The braking device includes a first rotating component, which is fixed to the motor shaft in a manner that allows it to rotate integrally with the motor shaft. The braking device includes a second rotating component, at least one second force-applying component, and a limiting component, wherein... When the second rotating component is in frictional engagement with the first rotating component, it is able to rotate about the first rotation axis in response to the rotation of the motor shaft and the first rotating component. The at least one second force-applying component applies force to the second rotating component on the first rotating component, causing it to engage with the first rotating component through friction. The limiting member is configured to be positioned in a first position where it can never interfere with the second rotating component under normal conditions, and in response to detecting the locked state, it moves to a second position where it can interfere with the second rotating component, thereby stopping the rotation of the second rotating component.

8. The power tool according to claim 7, characterized in that, The at least one second force-applying component is at least one disc spring.

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

10. The power tool according to claim 7 or 8, characterized in that, The motor is a brushed motor.

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