Tool

Abstract

To suppress sound while a tool is operated.SOLUTION: A tool includes a motor, a sun gear 41, an output shaft, a plurality of planetary gears, a planetary carrier 44, and an internal gear 43. A tip tool is mounted on the output shaft, and rotation of the sun gear 41 is transmitted thereto. The internal gear 43 is held in a rotatable state. The internal gear 43 is fixed to a transmission body, and is rotated according to the rotation of the transmission body. The internal gear 43 has a first engagement part 432. The planetary carrier 44 has a second engagement part 442. The first engagement part 432 of the internal gear 43 and the second engagement part 442 of the planetary carrier 44 are relatively movable in the rotation direction of the transmission body, and are brought into contact with each other according to the rotation of the internal gear 43.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present disclosure relates generally to tools, and more particularly, to tools including motors. [Background technology]

[0002] Patent Document 1 discloses a rotary impact tool including an impact mechanism. In the rotary impact tool of Patent Document 1, the impact mechanism applies an impact shock to an output shaft. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2017-132021 A Summary of the Invention [Problem to be solved by the invention]

[0004] Incidentally, in a rotary impact tool such as that described in Patent Document 1, noise is generated when the impact mechanism applies a striking shock to the output shaft.

[0005] The present disclosure has been made in consideration of the above-mentioned circumstances, and aims to provide a tool that can suppress noise during operation. [Means for solving the problem]

[0006] A tool according to an embodiment of the present disclosure includes a motor, a sun gear, an output shaft, a plurality of planetary gears, a planet carrier, and an internal gear. The motor rotates a transmission body that transmits torque to another member. A tool tip is attached to the output shaft, and the rotation of the sun gear is transmitted to the output shaft. The plurality of planetary gears are arranged around the sun gear and mesh with the sun gear. The planet carrier supports the plurality of planetary gears so that they can rotate on their own axes, and rotates around the sun gear. The internal gear is arranged to surround the plurality of planetary gears, meshes with the plurality of planetary gears, and is held in a rotatable state. The internal gear is fixed to the transmission body and rotates in response to the rotation of the transmission body. The internal gear has a first engagement portion. The planet carrier has a second engagement portion. The first engagement portion of the internal gear and the second engagement portion of the planet carrier are relatively movable along the rotation direction of the transmission body, and come into contact with each other in response to the rotation of the internal gear. Effect of the Invention

[0007] The present disclosure has the advantage of being able to reduce noise during operation of the tool. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a side view of the tool according to the first embodiment. [Diagram 2] FIG. 2 is a side sectional view of a main part of the tool. [Diagram 3] FIG. 3 is a cross-sectional view taken along line III-III in FIG. [Figure 4] FIG. 4 is a cross-sectional view taken along line IV-IV in FIG. [Diagram 5] FIG. 5 is a cross-sectional view corresponding to line IV-IV in FIG. 2, and shows a later time point than FIG. [Figure 6] FIG. 6 is a cross-sectional view corresponding to line IV-IV in FIG. 2, and shows a later time point than FIG. [Figure 7] FIG. 7 is an exploded perspective view of the tool. [Figure 8] FIG. 8 is an exploded perspective view of the tool. [Figure 9] FIG. 9 is a block diagram showing the configuration of the tool. [Figure 10] FIG. 10 is a timing chart showing the operation of the tool. [Figure 11] FIG. 11 is a side cross-sectional view of a main part of a tool according to the second embodiment. [Figure 12] FIG. 12 is a cross-sectional view taken along line XII-XII in FIG. [Figure 13] FIG. 13 is a cross-sectional view taken along line XIII-XIII in FIG. [Figure 14] FIG. 14 is an exploded perspective view of the tool. [Figure 15] FIG. 15 is a side cross-sectional view of a main part of a tool according to the third embodiment. [Figure 16] FIG. 16 is an exploded perspective view of the tool. [Figure 17] FIG. 17 is a perspective view of a main part of the tool. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Preferred embodiments of the present disclosure will be described in detail below with reference to the drawings. In addition, common elements in each embodiment described below are given the same reference numerals, and duplicated explanations of common elements may be omitted. Each of the following embodiments is merely one of various embodiments of the present disclosure. Each embodiment can be modified in various ways depending on the design, etc., as long as the object of the present disclosure can be achieved. In addition, each embodiment (including each modified example) may be realized in appropriate combination.

[0010] Each figure described in this disclosure is a schematic diagram, and the ratio of the size and thickness of each component in each figure does not necessarily reflect the actual dimensional ratio. Note that the arrows indicating each direction in the figure are only examples and are not intended to specify the direction when using the tool. Also, the arrows indicating each direction in the figure are merely indicated for the purpose of explanation and do not have any substance.

[0011] In addition, "orthogonal (perpendicular)" in this disclosure does not only mean a state in which the angle between two things is strictly 90 degrees, but also includes a state in which two things intersect within a certain range of difference. In other words, the angle between two perpendicular things falls within a certain range of difference from 90 degrees (for example, 10 degrees or less). In other words, "orthogonal" in this disclosure includes cases in which the angle between two things is 80 degrees or more and 100 degrees or less.

[0012] (Embodiment 1) (1) Overview First, an outline of the configuration of a tool 1 according to the first embodiment will be described with reference to FIGS.

[0013] The tool 1 is, for example, a portable power tool. The tool 1 includes a motor 2, a planetary gear mechanism 4, and an output shaft 5.

[0014] The motor 2 rotates a transmission body (motor shaft 21) that transmits torque to other members.

[0015] The planetary gear mechanism 4 has a sun gear 41, a plurality of planetary gears 42 (five in the example of FIG. 3), an internal gear 43, and a planetary carrier 44.

[0016] A tool tip is attached to the output shaft 5. The tool tip is, for example, a driver bit, a socket bit, a drill bit, or the like. The driver bit and the socket bit are bits used to tighten or loosen a fastening member such as a bolt. The drill bit is a bit used to drill holes in materials such as wood or metal materials. Of various types of tool tips, a tool tip appropriate for the intended use is attached to the output shaft 5. The rotation of the sun gear 41 is transmitted to the output shaft 5. As a result, the tool tip rotates integrally with the output shaft 5.

[0017] In addition, a tool tip may be attached to the output shaft 5 via an adapter.

[0018] The plurality of planetary gears 42 are arranged around the sun gear 41 and mesh with the sun gear 41 .

[0019] The planetary carrier 44 rotatably supports the plurality of planetary gears 42. The planetary carrier 44 rotates around the sun gear 41.

[0020] The internal gear 43 is disposed so as to surround the plurality of planetary gears 42 and meshes with the plurality of planetary gears 42. The internal gear 43 is held in a rotatable state.

[0021] The internal gear 43 is fixed to the transmission body (motor shaft 21) and rotates in response to the rotation of the transmission body.

[0022] The internal gear 43 has a first engagement portion 432. The planetary carrier 44 has a second engagement portion 442. The first engagement portion 432 of the internal gear 43 and the second engagement portion 442 of the planetary carrier 44 are relatively movable along the rotational direction of the transmission body (motor shaft 21), and come into contact with each other in response to the rotation of the internal gear 43.

[0023] Next, an overview of the operation of the tool 1 of the first embodiment will be described with reference to Fig. 3 to Fig. 6. The overview of the operation of the tool 1 will be described on the assumption that a tool tip is attached to the output shaft 5 and the tool tip is set on a work object such as a screw or a bolt, that is, the tool tip is in contact with the work object. The overview of the operation of the tool 1 will be described on the assumption that the transmission body (motor shaft 21) is rotating in the first direction DR1 in Fig. 3.

[0024] As shown in FIG. 3, the rotation of the motor 2 is transmitted to the internal gear 43 via the transmission body, and the internal gear 43 rotates in the first direction DR1.

[0025] Since the tool tip attached to the output shaft 5 is in contact with the work target, a force that suppresses rotation is applied to the output shaft 5. Therefore, rotation of the sun gear 41 that transmits rotation to the output shaft 5 is suppressed. In other words, when the motor 2 initially starts to rotate, in the planetary gear mechanism 4, the sun gear 41 is stopped and the planetary gear 42, the internal gear 43, and the planetary carrier 44 are rotatable.

[0026] When the internal gear 43 rotates in the first direction DR1, the multiple planetary gears 42 supported by the planetary carrier 44 rotate in the first direction DR1 while revolving in the first direction DR1, as shown in Fig. 3. The planetary carrier 44 rotates in the first direction DR1. More specifically, the rotation of the internal gear 43 is decelerated to rotate the planetary carrier 44.

[0027] The rotation speed of the internal gear 43 is equal to the rotation speed of the planetary carrier 44 multiplied by a speed change ratio calculated by the following [Equation 1]. [Number 1] (Z a +Z c ) / Z c Here, Z a is the number of teeth of sun gear 41, and Z c is the number of teeth of the internal gear 43. The number of teeth of the internal gear 43 is greater than the number of teeth of the sun gear 41.

[0028] Since the internal gear 43 rotates faster than the planetary carrier 44, after a certain amount of time has elapsed while the motor shaft 21 is rotating, the first engagement portion 432 of the internal gear 43 comes into contact with the second engagement portion 442 of the planetary carrier 44, as shown in Fig. 6. Then, the planetary carrier 44 is pushed by the first engagement portion 432 of the internal gear 43 at the second engagement portion 442, and rotates in the first direction DR1 at the same speed as the internal gear 43. In addition, when the force rotating the sun gear 41 exceeds the force suppressing the rotation of the output shaft 5, the sun gear 41 rotates in the first direction DR1 so as to cancel out the speed difference between the internal gear 43 and the planetary carrier 44.

[0029] In this way, when the tool tip is in contact with the work object and when the first engagement portion 432 of the internal gear 43 is in contact with the second engagement portion 442 of the planetary carrier 44, the sun gear 41, the internal gear 43 and the planetary carrier 44 rotate in the same direction as the rotational direction (first direction DR1) of the transmission body (motor shaft 21).

[0030] When the sun gear 41 rotates, the rotation is transmitted from the sun gear 41 to the output shaft 5, and the tool bit rotates together with the output shaft 5. This allows the worker to perform work on the work object using the tool bit. The work is, for example, tightening a screw or the like on the work object.

[0031] The sun gear 41 and the output shaft 5 are rotated by the rotational energy (inertia torque) of the rotating body immediately before the first engagement portion 432 contacts the second engagement portion 442. The rotating body includes the internal gear 43, the planetary carrier 44, and the inertia body 3 (see FIG. 2) described later. Compared to the case where the rotational energy of the motor 2 is simply transmitted to the output shaft 5, the rotational speed of the output shaft 5 increases instantaneously when the first engagement portion 432 contacts the second engagement portion 442 (see timings T7 and T9 in FIG. 10). That is, a large rotational torque is generated. Therefore, a large rotational torque can be applied to the work object, similar to the case where the impact mechanism of a conventional impact rotating tool applies a striking impact to the output shaft. Therefore, a fastening operation or the like on the work object can be performed with a large rotational torque. In this way, according to the tool 1 of this embodiment, the output shaft 5 can be rotated by the inertia torque of the rotating body.

[0032] The relative speed (speed difference) between the first engagement portion 432 of the internal gear 43 and the second engagement portion 442 of the planetary carrier 44 is slower than the rotation speed of the transmission body (motor shaft 21). Therefore, the sound generated when the first engagement portion 432 of the internal gear 43 and the second engagement portion 442 of the planetary carrier 44 come into contact with each other is much smaller than the sound generated when the impact mechanism of the impact rotary tool applies a striking shock to the output shaft. Therefore, the sound can be suppressed compared to the case where a large torque is applied to the output shaft by the impact mechanism.

[0033] In addition, the impact generated when the first engagement portion 432 of the internal gear 43 and the second engagement portion 442 of the planetary carrier 44 come into contact with each other is much smaller than the impact generated when the impact mechanism of the impact rotary tool applies an impact shock to the output shaft. In other words, the tool 1 of this embodiment has a longer life than the impact rotary tool because wear on the output shaft 5 (or the anvil) is suppressed.

[0034] In addition, in conventional impact rotating tools, the internal gear of the planetary gear mechanism is generally fixed to the housing so as not to rotate. Therefore, in conventional impact rotating tools, when performing a fastening operation or the like, a reaction force is transmitted from the internal gear to the housing, and the reaction force is transmitted to the worker. On the other hand, according to the tool 1 of the present embodiment, the internal gear 43 of the planetary gear mechanism 4 is held in a rotatable state relative to the housing 10 (see FIG. 2), so that when performing a fastening operation or the like, the reaction force is unlikely to be transmitted from the internal gear 43 to the housing 10. In other words, according to the tool 1 of the present embodiment, it is possible to reduce the reaction force transmitted to the worker when performing the operation.

[0035] In addition, in a conventional impact rotary tool, after the hammer part of the impact mechanism hits the anvil, the hammer part moves in a vibrating manner along the axial direction of the motor shaft due to elastic force in order to release the engagement (contact) with the anvil, so that the entire impact rotary tool vibrates along the axial direction of the motor shaft. However, in the tool 1 of this embodiment, the internal gear 43 does not move along the axial direction of the motor shaft 21 (the movement in the axial direction is restricted), so that the entire tool 1 is suppressed from vibrating along the axial direction of the motor shaft 21.

[0036] As described above, according to the tool 1 of this embodiment, noise during operation can be suppressed.

[0037] (2) Details A detailed configuration of the tool 1 according to the first embodiment will be described below with reference to Figs. 1 to 10. In the following description, the direction from the motor shaft 21 of the motor 2 toward the output shaft 5 is referred to as the forward direction, and the direction from the output shaft 5 toward the motor shaft 21 is referred to as the rearward direction. In the following description, the forward direction and the rearward direction may be collectively referred to as the "front-rear direction". In the first embodiment, the rotation axis Ax1 (see Fig. 2) of the output shaft 5 is aligned along the front-rear direction. In the following description, the direction from the grip portion 102 of the housing 10 toward the body portion 101 of the housing 10 is referred to as the upward direction, and the direction from the body portion 101 toward the grip portion 102 is referred to as the downward direction. In the following description, the upward direction and the downward direction may be collectively referred to as the "vertical direction".

[0038] 1 and 2, the tool 1 includes a housing 10, a motor 2, an inertial body 3, a planetary gear mechanism 4, an output shaft 5, a battery pack 11, and a trigger switch 12. Note that the tool 1 does not necessarily include the battery pack 11. In addition, as shown in FIG. 9, the tool 1 further includes a storage unit 6, a control unit 7, and a torque sensor 14.

[0039] As shown in FIG. 1, the housing 10 has a body portion 101 , a grip portion 102 , and a mounting portion 103 .

[0040] The body portion 101 accommodates the motor 2, the inertial body 3, and the planetary gear mechanism 4.

[0041] The grip portion 102 protrudes downward from the body portion 101. The grip portion 102 in this embodiment is formed, for example, in a cylindrical shape with an open upper and lower base.

[0042] The mounting part 103 is provided at the tip (lower end) of the grip part 102. In other words, the body part 101 and the mounting part 103 are connected by the grip part 102. The mounting part 103 is configured so that the battery pack 11 can be removably attached thereto.

[0043] The battery pack 11 is a power source that supplies a current to drive the motor 2. The battery pack 11 includes an assembled battery configured by connecting a plurality of secondary batteries (for example, lithium ion batteries or all-solid-state batteries) in series, and a case that houses the assembled battery.

[0044] The trigger switch 12 protrudes from the grip portion 102. The trigger switch 12 is an operation unit that receives operations for controlling the rotation of the motor 2. The motor 2 can be switched on and off by pulling the trigger switch 12. The rotation speed of the motor 2 can be adjusted by the amount by which the trigger switch 12 is pulled. The greater the amount of pulling, the faster the rotation speed of the motor 2.

[0045] 9 is, for example, a magnetostrictive torque sensor capable of detecting torsional distortion. The torque sensor 14 is disposed at a position where it can detect torsional distortion of the output shaft 5. The torque sensor 14 detects a change in magnetic permeability corresponding to distortion of the shaft generated by application of torque to the output shaft 5 with a coil disposed in a non-rotating portion, and outputs a voltage signal proportional to the distortion to the torque detection unit 71. Note that the torque sensor 14 may be a strain gauge type torque sensor.

[0046] The storage unit 6 includes, for example, a Read Only Memory (ROM), a Random Access Memory (RAM), or an Electrically Erasable Programmable Read Only Memory (EEPROM). The storage unit 6 stores a control program executed by the control unit 7. The storage unit 6 also stores a set value (set torque) of the tightening torque, etc. Note that the "tightening torque" in this disclosure refers to a torque for tightening a work target, and is a concept that includes a torque applied to the tool tip, the output shaft 5, or the motor shaft 21 when the tool 1 is in operation.

[0047] The control unit 7 includes a computer system having one or more processors and a memory. At least a part of the functions of the control unit 7 is realized by the processor of the computer system executing a program recorded in the memory of the computer system. The program may be recorded in the memory, or may be provided via a telecommunication line such as the Internet, or may be provided by recording it on a non-transitory recording medium such as a memory card.

[0048] 9, the control unit 7 has a torque detection unit 71 and a drive control unit 72. Note that the torque detection unit 71 and the drive control unit 72 do not necessarily represent actual configurations, but represent functions realized by the control unit 7.

[0049] The torque detection unit 71 detects the tightening torque of the output shaft 5 based on the voltage signal output from the torque sensor 14 .

[0050] The drive control unit 72 controls the motor 2. The drive control unit 72 controls the motor 2 by, for example, vector control. In vector control, the drive control unit 72 decomposes the motor current, which is a current supplied to the motor 2, into a torque current (q-axis current) that generates torque and an excitation current (d-axis current) that generates magnetic flux, and controls each current component independently. Note that the method by which the drive control unit 72 controls the motor 2 is not limited to vector control, and a control method different from vector control may be used.

[0051] The drive control unit 72 controls the motor 2 so that the fastening torque measured by the torque detection unit 71 reaches a set torque previously stored in the storage unit 6. When the fastening torque measured by the torque detection unit 71 becomes equal to or greater than the set torque, the drive control unit 72 controls the motor 2 to stop the rotation of the motor shaft 21.

[0052] When the operator pulls the trigger switch 12, the drive control unit 72 controls the motor 2 to rotate the motor shaft 21, for example, in a first direction DR1 (see FIG. 3). After the tightening torque becomes large and the internal gear 43 and the output shaft 5 stop rotating together, the drive control unit 72 controls the motor 2 to rotate the motor shaft 21 in a second direction opposite to the first direction DR1 for a predetermined time or a predetermined angle. After rotating the motor shaft 21 in the second direction for a predetermined time or a predetermined angle, the drive control unit 72 controls the motor 2 to rotate the motor shaft 21 again in the first direction DR1. The drive control unit 72 repeats a series of controls until the tightening torque measured by the torque detection unit 71 becomes equal to or greater than the set torque. In the example of FIG. 3, the first direction DR1 is clockwise as viewed from the rear, and the second direction is counterclockwise as viewed from the rear, but the first direction DR1 may be counterclockwise as viewed from the rear, and the second direction may be clockwise as viewed from the rear.

[0053] The motor 2 is, for example, a brushless motor. As shown in Fig. 2, the motor 2 has a motor shaft 21. The motor 2 converts the power supplied from the battery pack 11 into a rotational driving force (torque) of the motor shaft 21. The motor shaft 21 functions as a transmission body that transmits the torque to other members. A front end of the motor shaft 21 is fixed to an internal gear 43.

[0054] The motor shaft 21 is rotatably supported by the housing 10. More specifically, the motor shaft 21 is supported by the housing 10 via a bearing 15. The bearing 15 is, for example, a ball bearing.

[0055] The inertial body 3 is disposed between the motor 2 and the planetary gear mechanism 4. More specifically, the inertial body 3 is disposed in front of the motor 2 and behind the planetary gear mechanism 4. The inertial body 3 is disposed between the motor 2 and a plurality of planetary gears 42. The inertial body 3 is also disposed between the motor 2 and an internal gear 43. The inertial body 3 is mechanically connected to the motor shaft 21, and rotates integrally with the motor shaft 21. The inertial body 3 is a so-called flywheel, and increases the inertial torque of the motor 2 (motor shaft 21).

[0056] The inertial body 3 has a disk-like shape. The thickness direction of the inertial body 3 is aligned along the front-rear direction.

[0057] The tool 1 further includes a fan 8 (see FIG. 2). The fan 8 is disposed between the motor 2 and the planetary gear mechanism 4. More specifically, the fan 8 is disposed in front of the motor 2 and behind the inertial body 3. The fan 8 is mechanically connected to the motor shaft 21, and rotates integrally with the motor shaft 21. The fan 8 increases the inertial torque of the motor 2 (motor shaft 21), similar to the inertial body 3.

[0058] As shown in FIGS. 3, 7 and 8, the planetary gear mechanism 4 includes a shaft holding member 40, a sun gear 41, a plurality of planetary gears 42 (five in the example of FIG. 3), an internal gear 43, and a planetary carrier 44.

[0059] The sun gear 41 is an external gear. The sun gear 41 has a main body 410 and a protrusion 412.

[0060] The main body 410 is formed in a cylindrical shape whose axial direction coincides with the front-rear direction, and a plurality of teeth are provided on the outer circumferential surface of the main body 410. The main body 410 may be formed in an annular shape whose axial direction (thickness direction) coincides with the front-rear direction.

[0061] The protrusion 412 protrudes forward from the front end (front surface) of the main body 410. The shape of the protrusion 412 is a triangular prism. When viewed from the front-rear direction, the protrusion 412 is formed in a triangular shape with a rounded apex. The outer shape of the protrusion 412 and the edge of the recess 50 (see FIG. 8) of the output shaft 5 generally match in shape and size. The protrusion 412 is fitted into the recess 50 of the output shaft 5. By fitting the protrusion 412 into the recess 50 of the output shaft 5, the output shaft 5 and the sun gear 41 rotate integrally.

[0062] The planetary gears 42 are arranged around the sun gear 41. The planetary gears 42 are arranged at equal intervals on a circumference centered on the central axis of the sun gear 41. The planetary gears 42 are external gears. Each of the planetary gears 42 meshes with the sun gear 41 and the internal gear 43. The planetary gears 42 are formed with a through hole 422 (see FIG. 3) that penetrates the planetary gear 42 along the front-rear direction. When viewed from the front-rear direction, the through hole 422 is formed at the center of the planetary gear 42 and is a circular hole. A columnar or cylindrical shaft 421 whose axial direction is along the front-rear direction is passed through the through hole 422. The planetary gears 42 can rotate around the shaft 421 with the shaft 421 as the center. In other words, the planetary gears 42 can rotate around the shaft 421 with the shaft 421 as the center. The shaft 421 of the planetary gear 42 may be passed through the through hole 422 via a bearing.

[0063] The shaft 421 of the planetary gear 42 is supported by the shaft holding member 40 and the planetary carrier 44. More specifically, a first end (front end) of the shaft 421 of the planetary gear 42 is inserted into a through hole 401 formed in the shaft holding member 40. In addition, a second end (rear end) of the shaft 421 of the planetary gear 42 is inserted into a through hole 4411 of the planetary carrier 44.

[0064] The shaft holding member 40 is a member that supports the shafts 421 of the multiple planetary gears 42. The shaft holding member 40 is formed in an annular shape. The shaft holding member 40 is disposed such that the central axis of the shaft holding member 40 and the central axis of the sun gear 41 are concentric when viewed from the front-rear direction.

[0065] A plurality of through holes 401 (five in the example of FIG. 8 ) are formed in the shaft holding member 40. The plurality of through holes 401 are arranged at equal intervals on a circumference centered on the central axis of the sun gear 41. The plurality of through holes 401 penetrate the shaft holding member 40 in the front-rear direction. A front end of a shaft 421 of the planetary gear 42 is inserted into each of the plurality of through holes 401.

[0066] The shaft holding member 40 is rotatably supported by the internal gear 43. More specifically, the shaft holding member 40 is supported by the internal gear 43 via a bearing 17. The bearing 17 is, for example, a ball bearing.

[0067] The planetary carrier 44 is a member that supports the shafts 421 of the multiple planetary gears 42. The planetary carrier 44 has a carrier portion 441 and multiple second engagement portions 442 (two in FIG. 8).

[0068] The carrier portion 441 is formed in a disk shape with a thickness direction along the front-rear direction. The planetary carrier 44 is arranged such that the central axis of the planetary carrier 44 and the central axis of the sun gear 41 are concentric when viewed from the front-rear direction.

[0069] A through hole 4410 is formed in the center of the carrier portion 441 .

[0070] A plurality of through holes 4411 (five in the example of FIG. 8 ) are formed in the carrier portion 441. The plurality of through holes 4411 are arranged at equal intervals on a circumference centered on the central axis of the sun gear 41. The plurality of through holes 4411 penetrate the carrier portion 441 in the front-rear direction. The rear end of the shaft 421 of the planetary gear 42 is inserted into each of the plurality of through holes 4411. In this way, the carrier portion 441 is connected to each of the shafts 421 of the plurality of planetary gears 42.

[0071] The two second engagement portions 442 protrude from the carrier portion 441 along a direction perpendicular to the rotation axis Ax1 of the output shaft 5. More specifically, the two second engagement portions 442 protrude outward from the outer edge of the disc-shaped carrier portion 441 along the radial direction of the carrier portion 441. The two second engagement portions 442 protrude in directions moving away from each other. The second engagement portion 442 protrudes from a part of the side surface of the carrier portion 441 and is formed in a rectangular parallelepiped shape.

[0072] The internal gear 43 is disposed around the multiple planetary gears 42. The internal gear 43 meshes with the multiple planetary gears 42. The internal gear 43 is supported by the housing 10 in a rotatable state. More specifically, the internal gear 43 of the first embodiment is supported by the housing 10 via multiple bearings 13 (two in FIG. 2 ) arranged side by side in the front-rear direction. The bearings 13 are, for example, ball bearings. The internal gear 43 may be supported by the housing 10 via one or three or more bearings 13.

[0073] The internal gear 43 has a main body portion 431, a plurality of first engagement portions 432 (two in the example of FIG. 8), and a plurality of coupling portions 433 (two in the example of FIG. 8).

[0074] The main body 431 is formed in a cylindrical shape with its axial direction aligned along the front-rear direction, and a plurality of teeth are provided on the inner peripheral surface of the main body 431. The number of teeth of the main body 431 is greater than the number of teeth of the sun gear 41. The main body 431 is disposed such that the central axis of the main body 431 and the central axis of the sun gear 41 are concentric when viewed from the front-rear direction. The main body 431 may be formed in an annular shape with its axial direction (thickness direction) aligned along the front-rear direction.

[0075] The multiple first engagement parts 432 protrude rearward from the rear end (rear surface) of the main body part 431. That is, the multiple first engagement parts 432 protrude from the main body part 431 along the rotation axis Ax1 of the output shaft 5. The first engagement parts 432 protrude from a part of the annular rear end of the main body part 431 and are formed in a rectangular parallelepiped shape curved according to the curvature of the rear end of the main body part 431. The two first engagement parts 432 of the first embodiment are disposed so as to face each other in a direction perpendicular to the front-rear direction. More specifically, the two first engagement parts 432 face each other so as to sandwich the rotation axis Ax1 of the output shaft 5 therebetween.

[0076] The first engagement portion 432 and the second engagement portion 442 in the first embodiment protrude in directions perpendicular to each other. Therefore, the tool 1 can be made more compact in the front-rear direction than when both the first engagement portion 432 and the second engagement portion 442 protrude in the front-rear direction.

[0077] The two connecting portions 433 correspond one-to-one to the two first engagement portions 432. Each connecting portion 433 protrudes from the corresponding first engagement portion 432. More specifically, when viewed from the rear, each connecting portion 433 protrudes from the corresponding first engagement portion 432 toward the center of the main body portion 431. The two connecting portions 433 face each other with a gap therebetween. The tip of each of the two connecting portions 433 is formed in an arc shape along the shape of the motor shaft 21. The motor shaft 21 is fixed between the two connecting portions 433 by press-fitting. This allows the rotation of the motor shaft 21 to be transmitted to the internal gear 43.

[0078] The output shaft 5 is disposed in front of the planetary gear mechanism 4. The output shaft 5 rotates about a rotation axis Ax1 in response to the rotation of the sun gear 41. The rotation axis Ax1 of the output shaft 5 is also the rotation axis of the motor shaft 21, the sun gear 41, the internal gear 43, and the planetary carrier 44.

[0079] The output shaft 5 has a recess 50. The recess 50 is formed at the rear end of the output shaft 5. The edge of the recess 50 has a triangular shape with a rounded apex. The protrusion 412 of the sun gear 41 is fitted into the recess 50.

[0080] A tool tip is attached to the front end of the output shaft 5.

[0081] The output shaft 5 is rotatably supported by the housing 10. More specifically, the output shaft 5 is supported by the housing 10 via a plurality of bearings 16 (two in FIG. 2 ) arranged side by side in the front-rear direction. The bearings 16 are, for example, ball bearings. The output shaft 5 may be supported by the housing 10 via one bearing 16 or three or more bearings 16.

[0082] (3) Tool operation Next, the operation of the tool 1 will be described with reference to Figures 3 to 6 and 10. Since the planetary carrier 44 is connected to the shaft holding member 40 (see Figure 3) via the shaft 421 of the planetary gear 42, the planetary carrier 44 rotates integrally with the shaft holding member 40.

[0083] For example, at timing T0 in Fig. 10, the operator pulls the trigger switch 12, for example, to the maximum, while the tip of the tool bit is in contact with a work target such as a screw. Here, it is assumed that at the time of timing T0, the second engagement portion 442 of the planetary carrier 44 is spaced apart from the first engagement portion 432 of the internal gear 43 by a certain distance or more in the rotation direction (first direction DR1) of the internal gear 43, as shown in Fig. 4 or 5. In other words, it is assumed that the internal gear 43 is rotatable relative to the planetary carrier 44 in the first direction DR1 until the first engagement portion 432 and the second engagement portion 442 come into contact with each other.

[0084] When the trigger switch 12 is pulled, the drive control unit 72 rotates the motor shaft 21 in the first direction DR1 (forward direction). In the following description, it is assumed that the worker keeps the trigger switch 12 pulled to the maximum until the fastening operation of the work object is completed (until timing T10 in FIG. 10). Note that the trigger switch 12 may perform a so-called alternate operation in which it is kept pulled to the maximum even when it is not operated by the worker.

[0085] When the motor shaft 21 rotates, the internal gear 43 fixed to the motor shaft 21 also rotates integrally with the motor shaft 21. That is, as shown in Figures 3 and 4, the internal gear 43 rotates in the first direction DR1 at the same rotational speed (or number of rotations [rpm]) as the motor shaft 21.

[0086] Furthermore, as a result of the internal gear 43 rotating, the planetary gears 42 meshing with the planetary gears 42 revolve in the first direction DR1 while rotating in the first direction DR1. In other words, the planetary carrier 44 rotates in the first direction DR1.

[0087] Here, the sun gear 41 is connected to the output shaft 5. Since the tool tip attached to the output shaft 5 is in contact with the work target, a force is applied to the output shaft 5 to suppress rotation. In other words, the rotation of the sun gear 41 is suppressed. More specifically, the sun gear 41 receives a force from the multiple planetary gears 42 that rotates the sun gear 41 in the second direction, but the sun gear 41 does not rotate before the first engagement portion 432 engages with the second engagement portion 442. Therefore, with the sun gear 41 fixed, the internal gear 43 and the planetary carrier 44 rotate in the first direction DR1. The rotation speed of the internal gear 43 is faster than the rotation speed of the planetary carrier 44.

[0088] Fig. 4 shows the state immediately before motor shaft 21 starts to rotate. Fig. 5 shows the state some time has passed since motor shaft 21 started to rotate in first direction DR1. Fig. 6 shows the state after motor shaft 21 has continued to rotate in first direction DR1 from the state shown in Fig. 5.

[0089] As shown in FIG. 5 and FIG. 6, the internal gear 43 rotates in the first direction DR1 relative to the planetary carrier 44, so that the first engagement portion 432 of the internal gear 43 approaches the second engagement portion 442 located at the end of the rotation direction. Then, for example, at timing T1 in FIG. 10, the side of the first engagement portion 432 of the internal gear 43 comes into contact with the side of the second engagement portion 442 of the planetary carrier 44 as shown in FIG. 6. In other words, the first engagement portion 432 of the internal gear 43 engages with the second engagement portion 442 of the planetary carrier 44. In the period between timing T0 and timing T1, the rotation speed of the motor shaft 21 becomes equal to or higher than a certain speed, so that the inertia torque of the motor shaft 21 increases to or higher than a certain value. In the following description, the period during which the rotation speed of the motor shaft 21 increases in the first direction DR1 is called a charge period. The charge period is the period during which the inertia torque of the motor shaft 21 increases.

[0090] When the side surfaces of the multiple first engagement portions 432 engage with the side surfaces of the multiple second engagement portions 442, the planetary carrier 44 is accelerated in the first direction DR1 by the force applied from the multiple first engagement portions 432 to the multiple second engagement portions 442. This increases the force rotating the sun gear 41 in the first direction DR1. Therefore, the sun gear 41 and the output shaft 5 connected to the sun gear 41 rotate in the first direction DR1. The rotation of the output shaft 5 tightens the work object.

[0091] More specifically, when the planetary carrier 44 is accelerated in the first direction DR1 by the force applied from the first engagement parts 432 to the second engagement parts 442, a force that tries to rotate in the second direction (opposite to the first direction DR1) acts on each of the planetary gears 42 as a reaction force from the sun gear 41. On the other hand, a force that rotates in the first direction DR1 acts on each of the planetary gears 42 due to the rotation of the internal gear 43 in the first direction DR1. Since both the force that rotates in the first direction DR1 and the force that rotates in the second direction are forces generated by the rotation of the internal gear 43 in the first direction DR1, the force that rotates in the first direction DR1 and the force that rotates in the second direction are antagonistic to each other. Therefore, each of the planetary gears 42 stops rotating (rotating) around the axis 421. As a result, the sun gear 41 rotates in the same direction as the internal gear 43 at the same speed.

[0092] Therefore, when the first engagement portion 432 and the second engagement portion 442 engage with each other, the planetary carrier 44, the internal gear 43, the multiple planetary gears 42, and the sun gear 41 stop rotating relative to each other. In other words, when the first engagement portion 432 and the second engagement portion 442 engage with each other, the planetary carrier 44, the internal gear 43, the multiple planetary gears 42, the sun gear 41, and the output shaft 5 are fixed to each other. When the planetary carrier 44, the internal gear 43, the multiple planetary gears 42, the sun gear 41, and the output shaft 5 are fixed to each other, the planetary carrier 44, the internal gear 43, the multiple planetary gears 42, the sun gear 41, and the output shaft 5 rotate integrally in the first direction DR1 around the rotation axis Ax1. Therefore, the rotation speed of the output shaft 5 becomes the same as the rotation speed of the motor shaft 21 at the timing T1 when the first engagement portion 432 and the second engagement portion 442 are engaged with each other.

[0093] In other words, the internal gear 43 rotates in the same direction as the transmission body (motor shaft 21) when the tool tip is in contact with the work target and when the first engagement portion 432 of the internal gear 43 and the second engagement portion 442 of the planetary carrier 44 are not in contact with each other. The internal gear 43 and the output shaft 5 rotate integrally with the transmission body when the tool tip is in contact with the work target and when the first engagement portion 432 of the internal gear 43 and the second engagement portion 442 of the planetary carrier 44 are in contact with each other.

[0094] At timing T2 in Fig. 10, the workpiece is seated. Here, "seated" means that when the workpiece is a screw or bolt, the head seat of the workpiece comes into contact with the mating member. Also, when the workpiece is a nut, it means that the workpiece comes into contact with the head seat of the mating member. When the workpiece is seated, the tool bit rotates against the frictional force generated between the workpiece and the mating member, so the tightening torque increases rapidly.

[0095] The drive control unit 72 of the present embodiment stops the power supply to the motor 2 in accordance with the magnitude or increase of the fastening torque detected by the torque detection unit 71.

[0096] The drive control unit 72 stops the power supply to the motor 2 at the timing (e.g., timing T2) when the torque detection unit 71 detects that the work object has seated on the counterpart member. The torque detection unit 71 is configured to detect that the work object has seated when, for example, the amount of increase in fastening torque per unit time reaches or exceeds a specified value.

[0097] Furthermore, the drive control unit 72 stops the power supply to the motor 2 at the timing when the magnitude of the fastening torque detected by the torque detection unit 71 becomes equal to or greater than a specified value (for example, at timing T7, T9).

[0098] After the power supply to the motor 2 is stopped, the output shaft 5 and the tool tip attached to the output shaft 5 continue to rotate by the inertial torque accumulated in the inertial body 3, etc., and tighten the work object. This makes it possible to reduce the reaction force that the worker receives from the tool 1 after the worker sits on the work object. In detail, when no power is supplied to the motor 2, no electromagnetic interaction occurs between the rotor and stator of the motor 2. Therefore, the reaction force transmitted from the output shaft 5 to the rotor is not transmitted to the stator, and the reaction force that the worker receives from the tool 1 can be reduced.

[0099] As the fastening torque increases, the inertia torque of the motor shaft 21 is consumed, and at timing T3, the rotation of the motor shaft 21 and the output shaft 5 stops. At timing T4 after timing T3 when the rotation of the motor shaft 21 and the output shaft 5 stops, the drive control unit 72 of the first embodiment controls the motor 2 to rotate the motor shaft 21 in the second direction (reverse direction) for a predetermined time or a predetermined angle.

[0100] When the motor shaft 21 rotates, the internal gear 43 also rotates integrally with the motor shaft 21. That is, the internal gear 43 rotates in the second direction at the same rotational speed (or number of rotations [rpm]) as the motor shaft 21.

[0101] Since the tool tip attached to the output shaft 5 is in contact with the work target, a force that suppresses the rotation is applied to the output shaft 5. In other words, the rotation of the sun gear 41 connected to the output shaft 5 is suppressed.

[0102] Therefore, when the motor shaft 21 rotates in the second direction, the planetary carrier 44, the planetary gears 42, and the internal gear 43 each rotate in a direction (second direction) opposite to the direction when the motor shaft 21 rotates in the first direction DR1 (in the case of FIG. 3). Since the rotation speed of the internal gear 43 is faster than the rotation speed of the planetary carrier 44, the first engagement portion 432 of the internal gear 43 and the second engagement portion 442 of the planetary carrier 44, which were in contact with each other, move away from each other. The predetermined time during which the motor shaft 21 rotates in the second direction is the time during which the first engagement portion 432 moving away from the second engagement portion 442 does not come into contact with the other second engagement portion 442 within the predetermined time. The predetermined angle (predetermined number of times) is the angle (amount of rotation) at which the first engagement portion 432 moving away from the second engagement portion 442 does not come into contact with the other second engagement portion 442 until the motor shaft 21 rotates by the predetermined angle (predetermined number of times).

[0103] The drive control unit 72 controls the motor 2 to stop the rotation of the motor shaft 21 at timing T5 when a predetermined time has elapsed from timing T4 or when the motor shaft 21 has rotated a predetermined angle.

[0104] At timing T6 after controlling the motor 2 to stop the rotation of the motor shaft 21, the drive control unit 72 controls the motor 2 to rotate the motor shaft 21 again in the first direction DR1. When the motor shaft 21 rotates in the first direction DR1, the internal gear 43 rotates in the first direction DR1 faster than the planetary carrier 44, as in the period between timing T0 and timing T1.

[0105] In other words, by the drive control unit 72 controlling the motor 2 to rotate the motor shaft 21 in the second direction, a charge period can be secured for increasing the inertia torque again, and the work object can be tightened again with the inertia torque.

[0106] After timing T6, the drive control section 72 repeats the control performed from timing T0 to timing T5 until the fastening torque becomes equal to or greater than the set torque. In the example of Fig. 5, timings T7 and T8 in the second control correspond to timings T2 and T3 in the first control, and timings T9 and T10 in the third control correspond to timings T2 and T3 in the first control. Since the work target is already seated in the first control, there is no period in the second and subsequent controls that corresponds to the period from timing T1 to timing T2 in the first control.

[0107] In the example of FIG. 10, a first period from timing T2 to timing T3 is longer than a second period from timing T7 to timing T8. The second period is longer than a third period from timing T9 to timing T10. The peak value of the fastening torque in the first period is smaller than the peak value of the fastening torque in the second period. Also, the peak value of the fastening torque in the second period is smaller than the peak value of the fastening torque in the third period. Also, the integrated value of the fastening torque in the first period, the integrated value of the fastening torque in the second period, and the integrated value of the fastening torque in the third period are equal.

[0108] As described above, in the tool 1 of the first embodiment, there are three operating states, a first operating state, a second operating state, and a third operating state, during the operation of the motor 2. The first operating state is an operating state in which the motor shaft 21 rotates in the first direction DR1 and the output shaft 5 does not rotate (stops) as in the period from timing T0 to timing T1 in FIG. 10. The second operating state is an operating state in which the motor shaft 21, the internal gear 43, the planetary carrier 44, and the output shaft 5 rotate integrally in the first direction DR1 as in the period from timing T1 to timing T2 in FIG. The third operating state is an operating state in which the motor shaft 21 rotates in the second direction and the internal gear 43 rotates in the second direction relative to the planetary carrier 44 as in the period between timing T4 and timing T5 in FIG. 10. During the fastening operation by the tool 1 of embodiment 1, the operating state of the tool 1 transitions from the first operating state to the second operating state, from the second operating state to the third operating state, and from the third operating state to the first operating state.

[0109] (4) Variations Modifications of the first embodiment are listed below.

[0110] The inertial body 3 may have multiple fins. For example, the multiple fins are provided on the rear surface of the inertial body 3. By providing multiple fins on the rear surface of the inertial body 3, the inertial body 3 also functions as a fan for cooling the motor 2. When the motor shaft 21 rotates, the inertial body 3 also rotates, and cooling air is generated from the multiple fins toward the motor 2 as the inertial body 3 rotates. In this case, the tool 1 does not need to include the fan 8 shown in FIG. 2.

[0111] In the first embodiment, the drive control unit 72 stops the power supply to the motor 2 when the torque detection unit 71 detects that the work target is seated on the mating member or when the magnitude of the fastening torque detected by the torque detection unit 71 becomes equal to or greater than a specified value. However, the drive control unit 72 may stop the power supply to the motor 2 when a predetermined time has elapsed since the torque detection unit 71 detects that the work target is seated on the mating member or when the magnitude of the fastening torque detected by the torque detection unit 71 becomes equal to or greater than a specified value. For example, the drive control unit 72 may stop the power supply to the motor 2 until the rotation speed of the output shaft 5 becomes zero after the torque detection unit 71 detects that the work target is seated on the mating member or after the magnitude of the fastening torque detected by the torque detection unit 71 becomes equal to or greater than a specified value. The drive control unit 72 may also stop the power supply to the motor 2 when the rotation speed of the motor shaft 21 or the output shaft 5 becomes equal to or greater than a specified value, regardless of the fastening torque detected by the torque detection unit 71. In other words, the drive control unit 72 may stop the power supply to the motor 2 when the rotational speed of the motor shaft 21 or the output shaft 5 reaches or exceeds a specified value, even if this is before the torque detection unit 71 detects that the work object has seated on the opposing member.

[0112] It is not essential that the tool 1 includes the torque sensor 14. If the tool 1 does not include the torque sensor 14, the torque detection unit 71 may detect that the work target has been seated on the mating member or that the magnitude of the fastening torque has reached a specified value or more, based on the rotation speed (or number of rotations [rpm]) of the motor shaft 21. The torque detection unit 71 may also calculate the fastening torque based on the amount of rotation (rotation angle) of the motor shaft 21 from the timing when the torque detection unit 71 detects that the work target has been seated on the mating member or the timing when the magnitude of the fastening torque detected by the torque detection unit 71 reaches a specified value or more, until the motor shaft 21 stops. The torque detection unit 71 may also calculate the fastening torque by calculating the inertia torque of the output shaft 5 of the motor shaft 21 based on the rotation speed of the motor shaft 21 and the mass of the inertial body 3, etc.

[0113] The tool 1 is not limited to a configuration in which the power source is the battery pack 11, but may be a configuration in which the power source is an AC power source (commercial power source). Furthermore, the tool 1 is not limited to an electric tool, but may be an air tool having an air motor (drive unit) that operates with compressed air (power) supplied from an air compressor as a power source.

[0114] (Embodiment 2) As shown in FIG. 11, a tool 1A according to the second embodiment differs from the tool 1 according to the first embodiment in that a planetary gear mechanism 4A has a multi-stage (two-stage) configuration.

[0115] (1) Composition Like the planetary gear mechanism 4 of the first embodiment, the planetary gear mechanism 4A has a sun gear 41, a plurality of planetary gears 42 (five in the example of FIG. 14), an internal gear 43, and a planet carrier 44. Hereinafter, the sun gear 41, the plurality of planetary gears 42, and the planet carrier 44 will be referred to as the first sun gear 41, the plurality of first planetary gears 42, and the first planet carrier 44, respectively.

[0116] As shown in FIGS. 11 to 14, the planetary gear mechanism 4A further includes a second sun gear 41S, a plurality of second planetary gears 42S (five in the example of FIG. 14), a second planetary carrier 44S, and a shaft holding member 45.

[0117] In the planetary gear mechanism 4A of the present embodiment, a second sun gear 41S, not a first sun gear 41, is fixed to the output shaft 5.

[0118] The second sun gear 41S has a main body 410S and a protruding portion 412S. The main body 410S and the protruding portion 412S have the same shapes as the main body 410 and the protruding portion 412 of the first sun gear 41, respectively, so a description of the shape of the second sun gear 41S will be omitted.

[0119] The second sun gear 41S is disposed so that the central axis of the second sun gear 41S and the central axis of the first sun gear 41 are concentric when viewed in the front-rear direction.

[0120] The second sun gear 41S is disposed between the first sun gear 41 and the output shaft 5 in the front-rear direction. A protruding portion 412S of the second sun gear 41S is fitted into a recessed portion 50 (see FIG. 8) of the output shaft 5. As a result of the protruding portion 412S being fitted into the recessed portion 50 of the output shaft 5, the output shaft 5 and the second sun gear 41S rotate integrally.

[0121] The second planetary gear 42S has a shape similar to that of the first planetary gear 42, and therefore a description of the shape of the second planetary gear 42S will be omitted.

[0122] The multiple second planetary gears 42S are disposed around the second sun gear 41S and mesh with the second sun gear 41S.

[0123] The second planetary carrier 44S is formed in a disk shape with its thickness direction aligned with the front-rear direction. The second planetary carrier 44S is arranged such that the central axis of the second planetary carrier 44S and the central axis of the first sun gear 41 are concentric when viewed from the front-rear direction. The second planetary carrier 44S is arranged between the multiple first planetary gears 42 and the multiple second planetary gears 42S.

[0124] An insertion hole 440S is formed at the center of the second planetary carrier 44S. The protrusion 412 at the front end of the first sun gear 41 is inserted into the insertion hole 440S. This allows the second planetary carrier 44S and the first sun gear 41 to be fitted together. In other words, the second planetary carrier 44S is fixed to the first sun gear 41 and rotates around the first sun gear 41 in response to the rotation of the first sun gear 41.

[0125] A plurality of through holes 441S (five in the example of FIG. 12) are formed in the second planetary carrier 44S. The plurality of through holes 441S are arranged at equal intervals on a circumference centered on the central axis of the first sun gear 41. The plurality of through holes 441S penetrate the second planetary carrier 44S along the front-rear direction. The rear end of the shaft 421S of the second planetary gear 42S is inserted into each of the plurality of through holes 441S. Therefore, as the second planetary carrier 44S rotates, the plurality of second planetary gears 42S rotate (revolve) around the central axis of the second planetary carrier 44S. The second planetary carrier 44S also supports the plurality of second planetary gears 42S rotatably via the shaft 421S.

[0126] The shaft holding member 45 is formed in a disk shape with its thickness direction aligned with the front-rear direction. A plurality of through holes 451 (five in the example of FIG. 14) are formed in the shaft holding member 45. The through holes 451 are arranged at equal intervals on a circumference centered on the central axis of the second sun gear 41S. The through holes 451 penetrate the shaft holding member 45 in the front-rear direction. A front end of the shaft 421S of the second planetary gear 42S is inserted into each of the through holes 451.

[0127] The first planetary carrier 44, the multiple first planetary gears 42, and the first sun gear 41 are disposed between the motor 2 and the multiple second planetary gears 42S. The first planetary carrier 44 supports the multiple first planetary gears 42 so that they can rotate about their axes. The multiple first planetary gears 42 are disposed around the first sun gear 41 and mesh with the first sun gear 41.

[0128] Similar to the first embodiment, the first planetary carrier 44 has a plurality of (two) second engagement portions 442.

[0129] The internal gear 43 is fixed to the motor shaft 21. The internal gear 43 is disposed so as to surround the multiple first planetary gears 42 and the multiple second planetary gears 42S. The internal gear 43 meshes with the multiple first planetary gears 42 and the multiple second planetary gears 42S.

[0130] The rotation axis Ax1 of the output shaft 5 is also the rotation axis of the motor shaft 21, the first sun gear 41, the second sun gear 41S, the internal gear 43, the first planetary carrier 44, and the second planetary carrier 44S.

[0131] (2) Tool operation Next, the operation of the tool 1A will be described.

[0132] For example, at timing T0 in Fig. 10, the operator pulls the trigger switch 12, for example, to the maximum, while the tip of the tool bit is in contact with a work target such as a screw. Here, it is assumed that at the time of timing T0, the second engagement portion 442 of the first planetary carrier 44 is spaced apart from the first engagement portion 432 of the internal gear 43 by a certain distance or more in the rotational direction of the internal gear 43 (first direction DR1) as shown in Fig. 4 or 5.

[0133] When the trigger switch 12 is pulled, the drive control unit 72 rotates the motor shaft 21 in the first direction DR1 (forward direction). In the following description, it is assumed that the worker keeps the trigger switch 12 pulled to the maximum until the fastening operation of the work object is completed (until timing T10 in FIG. 10). Note that the trigger switch 12 may perform a so-called alternate operation in which it is kept pulled to the maximum even when it is not operated by the worker.

[0134] When the motor shaft 21 rotates, the internal gear 43 fixed to the motor shaft 21 also rotates integrally with the motor shaft 21. That is, as shown in Fig. 12, the internal gear 43 rotates in a first direction DR1 at the same rotational speed (or number of rotations [rpm]) as the motor shaft 21. This causes the multiple first planetary gears 42 to rotate in the first direction DR1 while revolving in the first direction DR1. The planetary carrier 44 rotates in the first direction DR1.

[0135] The first sun gear 41, which meshes with the multiple first planetary gears 42, rotates in a first direction DR1.

[0136] The second planetary carrier 44S fixed to the first sun gear 41 rotates in the first direction DR1 integrally with the first sun gear 41. That is, the multiple second planetary gears 42S revolve in the first direction DR1 (see FIG. 13). At this time, the multiple second planetary gears 42S rotate on their axes in the first direction DR1.

[0137] A shaft holding member 45 to which front ends of the shafts 421S of the multiple second planetary gears 42S are connected rotates in the first direction DR1 together with the second planetary carrier 44S.

[0138] Here, the second sun gear 41S is connected to the output shaft 5. Since the tool attached to the output shaft 5 is in contact with the work target, a force that suppresses the rotation is applied to the output shaft 5. In other words, the rotation of the second sun gear 41S is suppressed. More specifically, the second sun gear 41S receives a force from the multiple second planetary gears 42S that rotates the second sun gear 41S in the second direction, but the second sun gear 41S does not rotate before the first engagement portion 432 engages with the second engagement portion 442. Therefore, with the second sun gear 41S fixed, the internal gear 43, the first planetary carrier 44, the first sun gear 41, and the second planetary carrier 44S rotate in the first direction DR1. The rotation speed of the internal gear 43 is faster than the rotation speed of the first planetary carrier 44.

[0139] Fig. 4 shows the state immediately before motor shaft 21 starts to rotate. Fig. 5 shows the state some time has passed since motor shaft 21 started to rotate in first direction DR1. Fig. 6 shows the state after motor shaft 21 has continued to rotate in first direction DR1 from the state shown in Fig. 5.

[0140] 5 and 6, when the internal gear 43 rotates in the first direction DR1 relative to the first planetary carrier 44, the first engagement portion 432 of the internal gear 43 approaches the second engagement portion 442 located further ahead in the rotation direction. Then, for example, at timing T1 in Fig. 10, the side surface of the first engagement portion 432 of the internal gear 43 comes into contact with the side surface of the second engagement portion 442 of the first planetary carrier 44 as shown in Fig. 6.

[0141] When the side surfaces of the first engagement portions 432 engage with the side surfaces of the second engagement portions 442, the first planetary carrier 44 is accelerated in the first direction DR1 by the force applied from the first engagement portions 432 to the second engagement portions 442. This increases the force that rotates the first sun gear 41 and the second planetary carrier 44S fixed to the first sun gear 41 in the first direction DR1. In other words, the force that revolves the second planetary gears 42S in the first direction DR1 increases. This causes the second sun gear 41S meshed with the second planetary gears 42S and the output shaft 5 connected to the second sun gear 41S to rotate in the first direction DR1. The rotation of the output shaft 5 tightens the work object.

[0142] More specifically, when the second planetary carrier 44S is accelerated in the first direction DR1 by the force applied from the first engagement parts 432 to the second engagement parts 442, a force that tends to rotate in the second direction acts on each of the second planetary gears 42S as a reaction force from the second sun gear 41S. On the other hand, a force that rotates in the first direction DR1 acts on each of the second planetary gears 42S due to the second planetary carrier 44S indirectly receiving a force from the motor shaft 21 and rotating in the first direction DR1. Both the force that rotates in the first direction DR1 and the force that rotates in the second direction are forces generated by the rotation of the second planetary carrier 44S in the first direction DR1, so the force that rotates in the first direction DR1 and the force that rotates in the second direction are antagonistic to each other. Therefore, each of the second planetary gears 42S stops rotating (rotating) around the shaft 421S. As a result, the second sun gear 41S rotates at the same speed as the internal gear 43 and in the same direction.

[0143] Since the first sun gear 41 is fixed to the second planetary carrier 44S, the first sun gear 41 also rotates at the same speed and in the same direction as the internal gear 43. Therefore, the multiple first planetary gears 42 meshed between the first sun gear 41 and the internal gear 43 stop rotating (spinning) about the axis 421.

[0144] Therefore, when the first engagement portion 432 and the second engagement portion 442 are engaged with each other, the first planetary carrier 44, the second planetary carrier 44S, the internal gear 43, the multiple first planetary gears 42, the multiple second planetary gears 42S, the first sun gear 41, and the second sun gear 41S stop rotating relative to each other. In other words, when the first engagement portion 432 and the second engagement portion 442 are engaged with each other, the first planetary carrier 44, the second planetary carrier 44S, the internal gear 43, the multiple first planetary gears 42, the multiple second planetary gears 42S, the first sun gear 41, and the second sun gear 41S are fixed to each other. When the first planetary carrier 44, the second planetary carrier 44S, the internal gear 43, the first planetary gears 42, the second planetary gears 42S, the first sun gear 41, and the second sun gear 41S are fixed to each other, the first planetary carrier 44, the second planetary carrier 44S, the internal gear 43, the first planetary gears 42, the second planetary gears 42S, the first sun gear 41, and the second sun gear 41S rotate integrally in the first direction DR1 about the rotation axis Ax1. Therefore, at the timing T1 when the first engagement portion 432 and the second engagement portion 442 engage with each other, the rotation speed of the output shaft 5 becomes the same as the rotation speed of the motor shaft 21.

[0145] As with the tool 1 of the first embodiment, the tool 1A has three operating states: the first operating state, the second operating state, and the third operating state described in the first embodiment.

[0146] Thus, the planetary gear mechanism 4A has a two-stage configuration including a first stage mechanism and a second stage mechanism provided in front of the first stage mechanism. The first stage mechanism includes a first sun gear 41, a plurality of first planetary gears 42, and a first planetary carrier 44. The second stage mechanism includes a second sun gear 41S, a plurality of second planetary gears 42S, and a second planetary carrier 44S. The first sun gear 41 is fixed to the second stage mechanism (second planetary carrier 44S). By configuring the planetary gear mechanism 4A as a two-stage mechanism, the speed difference between the rotation speed of the internal gear 43 and the rotation speed of the first planetary carrier 44 becomes smaller compared to the first embodiment in which the planetary gear mechanism 4 has a single stage configuration. More specifically, as the first sun gear 41 rotates in the same direction as the first planetary carrier 44 and the internal gear 43, the internal gear 43 slows down compared to embodiment 1, and the speed difference between the rotational speed of the internal gear 43 and the rotational speed of the first planetary carrier 44 becomes smaller.

[0147] By reducing the speed difference between the rotation speed of the internal gear 43 and the rotation speed of the first planetary carrier 44, the period of the first operating state (charge period) can be made longer. Therefore, the inertia torque of the motor shaft 21 can be sufficiently increased.

[0148] The planetary gear mechanism 4A may have a multi-stage configuration of three or more stages. By configuring the planetary gear mechanism 4A to have a multi-stage configuration of three or more stages, the period of the first operating state (charge period) can be made longer. The number of internal gears of the planetary gear mechanism 4A may be one regardless of the number of stages of the planetary gear mechanism 4A, or may be equal to the number of stages of the planetary gear mechanism 4A. When the planetary gear mechanism 4A has multiple internal gears held in a rotatable state, the multiple internal gears correspond one-to-one to the multiple planet carriers, and each internal gear meshes with the multiple planet gears supported by the corresponding planet carrier. Of the multiple internal gears, the first-stage internal gear has a first engagement portion 432 and is fixed to the motor shaft 21.

[0149] (Embodiment 3) (1) Main differences 15 to 17 show a tool 1B according to embodiment 3. In this embodiment, the configurations of an internal gear 43B and a planet carrier 44B of a planetary gear mechanism 4B are different from those of the internal gear 43 and the planet carrier 44 of embodiment 1.

[0150] (1.1) Internal Gear The internal gear 43B has a main body portion 431, a plurality of (two in the example of Figure 16) first engagement portions 432 protruding from the main body portion 431, and a plurality of (two in the example of Figure 16) third engagement portions 435 protruding from the main body portion 431.

[0151] The main body 431 is formed in a cylindrical shape with its axial direction aligned along the front-rear direction, and a plurality of teeth are provided on the inner peripheral surface of the main body 431. The number of teeth of the main body 431 is greater than the number of teeth of the sun gear 41B. The main body 431 is disposed such that the central axis of the main body 431 and the central axis of the sun gear 41B are concentric when viewed from the front-rear direction. The main body 431 may be formed in an annular shape with its axial direction (thickness direction) aligned along the front-rear direction.

[0152] The multiple first engagement parts 432 protrude rearward from the rear end (rear surface) of the main body part 431. That is, the multiple first engagement parts 432 protrude from the main body part 431 along the rotation axis Ax1 of the output shaft 5B. The first engagement parts 432 protrude from a part of the annular rear end of the main body part 431 and are formed in a rectangular parallelepiped shape curved according to the curvature of the rear end of the main body part 431. The two first engagement parts 432 are disposed so as to face each other in a direction perpendicular to the front-rear direction. More specifically, the two first engagement parts 432 face each other so as to sandwich the rotation axis Ax1 of the output shaft 5B therebetween.

[0153] The third engagement parts 435 protrude forward from the front end (front surface) of the main body 431. That is, the third engagement parts 435 protrude from the main body 431 along the rotation axis Ax1 of the output shaft 5B. The third engagement parts 435 protrude from a part of the annular front end of the main body 431 and are formed in a rectangular parallelepiped shape curved according to the curvature of the front end of the main body 431. The two third engagement parts 435 are disposed so as to face each other in a direction perpendicular to the front-rear direction. More specifically, the two third engagement parts 435 face each other so as to sandwich the rotation axis Ax1 of the output shaft 5B therebetween.

[0154] The direction in which the multiple third engagement portions 435 protrude from the main body portion 431 is opposite to the direction in which the multiple first engagement portions 432 protrude from the main body portion 431.

[0155] The multiple third engagement portions 435 correspond one-to-one to the multiple first engagement portions 432. Each third engagement portion 435 is aligned with the corresponding first engagement portion 432 in the front-rear direction.

[0156] (1.2) Transmission medium The tool 1B further includes a transmission body 941. The torque of the motor shaft 21 is transmitted via the transmission body 941 to the internal gear 43B.

[0157] The shape of the transmitting body 941 is a disk shape. The transmitting body 941 has a plurality of (two in FIG. 16) recesses 9410. The plurality of recesses 9410 are provided on the side surface of the transmitting body 941.

[0158] The first engagement portions 432 of the internal gear 43B correspond one-to-one to the recesses 9410. Each first engagement portion 432 is inserted into the corresponding recess 9410. This connects the transmission body 941 and the internal gear 43B (see FIG. 17). The transmission body 941 and the internal gear 43B rotate integrally.

[0159] A gap is provided in the front-rear direction between the transmission body 941 and the main body 431 of the internal gear 43B. A plurality of second engagement portions 442 and a first carrier portion 441, which will be described later, are disposed in this gap.

[0160] (1.3) Planet carrier The planetary gear mechanism 4B has a sun gear 41B, a plurality of planetary gears 42 (six in the example of FIG. 16), an internal gear 43B, and a planetary carrier 44B.

[0161] The planetary carrier 44B has a first carrier portion 441, a second carrier portion 46, a plurality (two in FIG. 16) of second engagement portions 442 protruding from the first carrier portion 441, and a plurality (two in FIG. 16) of fourth engagement portions 464 protruding from the second carrier portion 46.

[0162] The second carrier portion 46 has a configuration corresponding to the shaft holding member 40 of the first embodiment.

[0163] The planetary carrier 44B is disposed so that the central axis of the planetary carrier 44B and the central axis of the sun gear 41B are concentric when viewed from the front-rear direction.

[0164] The first carrier portion 441 is formed in a disk shape with its thickness direction aligned in the front-rear direction.

[0165] A through hole 4410 is formed in the center of the first carrier portion 441. In the through hole 4410, the center pin 95 is inserted.

[0166] A plurality of (six) through holes 4411 are formed in the first carrier part 441. Note that FIG. 15 illustrates only two of the six through holes 4411. The plurality of through holes 4411 are arranged at equal intervals on a circumference centered on the central axis of the sun gear 41B. The plurality of through holes 4411 penetrate the first carrier part 441 along the front-rear direction. A rear end (first end) of the shaft 421 of the planetary gear 42 is inserted into each of the plurality of through holes 4411. As a result, the first carrier part 441 is connected to the rear end (first end) of each of the shafts 421 of the plurality of planetary gears 42.

[0167] A plurality of through holes 461 (six in FIG. 16 ) are formed in the second carrier part 46. The plurality of through holes 461 are arranged at equal intervals on a circumference centered on the central axis of the sun gear 41B. The plurality of through holes 461 penetrate the second carrier part 46 along the front-rear direction. A front end of the shaft 421 of the planetary gear 42 is inserted into each of the plurality of through holes 461. As a result, the second carrier part 46 is connected to the front end (second end) of each of the shafts 421 of the plurality of planetary gears 42.

[0168] The second carrier portion 46 is disposed in front of the first carrier portion 441. The second carrier portion 46 faces the first carrier portion 441 in the front-rear direction. The multiple planetary gears 42 are disposed between the first carrier portion 441 and the second carrier portion 46.

[0169] The second carrier part 46 is rotatably supported by the housing 10. More specifically, the second carrier part 46 is supported by the housing 10 via a bearing 17.

[0170] The two second engagement portions 442 protrude from the first carrier portion 441 along a direction perpendicular to the rotation axis Ax1 of the output shaft 5B. More specifically, the two second engagement portions 442 protrude outward from the outer edge of the disk-shaped first carrier portion 441 along the radial direction of the first carrier portion 441. The two second engagement portions 442 protrude in directions moving away from each other. The second engagement portion 442 protrudes from a part of the side surface of the first carrier portion 441 and is formed in a rectangular parallelepiped shape.

[0171] The two fourth engagement portions 464 protrude from the second carrier portion 46 along a direction perpendicular to the rotation axis Ax1 of the output shaft 5B. More specifically, the two fourth engagement portions 464 protrude outward from the outer edge of the disk-shaped second carrier portion 46 along the radial direction of the second carrier portion 46. The two fourth engagement portions 464 protrude in directions moving away from each other. The fourth engagement portion 464 protrudes from a part of the side surface of the second carrier portion 46 and is formed in a rectangular parallelepiped shape.

[0172] The first carrier portion 441 and the second carrier portion 46 are connected via a plurality of shafts 421, so that the relative orientation of the second carrier portion 46 with respect to the first carrier portion 441 is fixed. The plurality (two) of fourth engagement portions 464 correspond one-to-one with the plurality (two) of second engagement portions 442. Each of the fourth engagement portions 464 is disposed in front of the corresponding second engagement portion 442. Each of the fourth engagement portions 464 faces the corresponding second engagement portion 442 in the front-rear direction.

[0173] As in embodiment 1, the multiple first engagement portions 432 of the internal gear 43B and the multiple second engagement portions 442 of the planetary carrier 44B are relatively movable along the rotational direction of the transmission body 941, and come into contact in response to the rotation of the internal gear 43B.

[0174] Furthermore, the multiple third engagement portions 435 of the internal gear 43B and the multiple fourth engagement portions 464 of the planetary carrier 44B are relatively movable along the rotational direction of the transmission body 941. When the multiple first engagement portions 432 of the internal gear 43B and the multiple second engagement portions 442 of the planetary carrier 44B come into contact with each other in response to the rotation of the internal gear 43B, the multiple third engagement portions 435 of the internal gear 43B come into contact with the multiple fourth engagement portions 464 of the planetary carrier 44B.

[0175] That is, similarly to the first embodiment, the rotational force of the internal gear 43B is transmitted to the planet carrier 44B via the first engagement portions 432 and the second engagement portions 442. Furthermore, the rotational force of the internal gear 43B is also transmitted to the planet carrier 44B via the third engagement portions 435 and the fourth engagement portions 464. In this manner, in the present embodiment, the rotational force of the internal gear 43B is transmitted to the planet carrier 44B in a more dispersed manner than in the first embodiment. Therefore, it is possible to suppress stress concentration in the internal gear 43B and the planet carrier 44B. By suppressing stress concentration, it is possible to extend the life of the tool 1B.

[0176] (2) Other differences Among the configurations of the tool 1B of this embodiment, those that differ from the tool 1 of the first embodiment are listed below. However, it is not essential that the tool 1B differs from the tool 1 of the first embodiment in the matters described below. The tool 1B may differ from the tool 1 of the first embodiment only in the matters described in "(1) Main differences", for example. Alternatively, the tool 1B may differ from the tool 1 of the first embodiment only in some of the matters described below.

[0177] (2.1) Sun gear and output shaft The sun gear 41B has a main body portion 410 and a protrusion portion 413.

[0178] The main body 410 is formed in a cylindrical shape with an axial direction along the front-rear direction, and a plurality of teeth are provided on the outer circumferential surface of the main body 410. The protruding portion 413 protrudes forward from the front end (front surface) of the main body 410. The shape of the protruding portion 413 is cylindrical. The inner circumferential surface of the protruding portion 413 is splined.

[0179] The output shaft 5B has a connecting portion 51. The connecting portion 51 is a rear end portion of the output shaft 5B. The connecting portion 51 has, for example, a cylindrical or columnar shape. The outer circumferential surface of the connecting portion 51 has a spline shape.

[0180] The connecting portion 51 of the output shaft 5B is connected to the protruding portion 413 of the sun gear 41B. That is, the connecting portion 51 is inserted into the inside of the protruding portion 413, and the connecting portion 51 and the protruding portion 413 are fitted together.

[0181] (2.2) Second planetary gear mechanism 15, the tool 1B further includes a second planetary gear mechanism 9. The second planetary gear mechanism 9 includes a sun gear 91, a plurality of planetary gears 92, an internal gear 93, a planet carrier 94, a center pin 95, and a holder 96.

[0182] The sun gear 91 is a member that is integral with the motor shaft 21 of the motor 2. The sun gear 91 is provided at the front end of the motor shaft 21.

[0183] The multiple planetary gears 92 are arranged around the sun gear 91 and mesh with the sun gear 91. Each of the multiple planetary gears 92 rotates about a corresponding shaft 921. The shaft 921 is supported by the planetary carrier 94. More specifically, the shaft 921 is fixed to the planetary carrier 94 by being inserted into a through hole formed in the planetary carrier 94.

[0184] Rotation of the sun gear 91 causes the multiple planetary gears 92 to revolve, and therefore the planetary carrier 94 to rotate.

[0185] The internal gear 93 is disposed so as to surround the plurality of planetary gears 92, and meshes with the plurality of planetary gears 92. The internal gear 93 is housed in a holder 96. The internal gear 93 is held by the holder 96.

[0186] The holder 96 is accommodated in the housing 10 of the tool 1B. The holder 96 is held by the housing 10. The holder 96 rotatably holds the planetary carrier 94 via a bearing 18.

[0187] The planetary carrier 94 has a transmission body 941 and a carrier portion 942. The carrier portion 942 is disk-shaped. The shafts 921 of the multiple planetary gears 92 are fixed to the carrier portion 942. The transmission body 941 is disk-shaped. The transmission body 941 protrudes forward from the carrier portion 942.

[0188] The transmission body 941 and the carrier portion 942 are concentric. The diameter of the transmission body 941 is larger than the diameter of the carrier portion 942.

[0189] The planetary carrier 94 has a through hole 943 at its center. A center pin 95 is inserted into the through hole 943. The center pin 95 is inserted into the sun gear 41B and the output shaft 5B.

[0190] The planet carrier 94 is an example of an inertial body 3 used as a flywheel.

[0191] The rotation of the motor shaft 21 is reduced in speed by the second planetary gear mechanism 9 and is then transmitted from the transmission body 941 to the internal gear 43B.

[0192] (summary) The above-described embodiments and the like disclose the following aspects.

[0193] The tool (1; 1A; 1B) according to the first embodiment includes a motor (2), a sun gear (41; 41B), an output shaft (5; 5B), a plurality of planetary gears (42), a planetary carrier (44; 44B), and an internal gear (43; 43B). The motor (2) rotates a transmission body (motor shaft (21; (941)) that transmits torque to another member. A tool tip is attached to the output shaft (5; 5B), and the rotation of the sun gear (41; 41B) is transmitted to the output shaft (5; 5B). The plurality of planetary gears (42) are disposed around the sun gear (41; 41B) and mesh with the sun gear (41; 41B). The planetary carrier (44; 44B) rotatably supports the plurality of planetary gears (42) and rotates around the sun gear (41; 41B). The internal gear (43; 43B) is disposed so as to surround the multiple planetary gears (42), meshes with the multiple planetary gears (42), and is held in a rotatable state. The internal gear (43; 43B) is fixed to the transmission body and rotates in response to the rotation of the transmission body. The internal gear (43; 43B) has a first engagement portion (432). The planetary carrier (44; 44B) has a second engagement portion (442). The first engagement portion (432) of the internal gear (43; 43B) and the second engagement portion (442) of the planetary carrier (44; 44B) are relatively movable in the rotation direction of the transmission body and come into contact with each other in response to the rotation of the internal gear (43; 43B).

[0194] According to the above configuration, the first engagement portion (432) and the second engagement portion (442) come into contact with each other, so that a large torque can be transmitted to the output shaft (5; 5B) based on the rotational energy of the planetary transmission mechanism (the sun gear (41; 41B), the planetary carrier (44; 44B), the plurality of planetary gears (42), and the internal gear (43; 43B)). The relative speed between the first engagement portion (432) of the internal gear (43; 43B) and the second engagement portion (442) of the planetary carrier (44; 44B) is slower than the rotational speed of the transmission body (the motor shaft (21; (941)). Therefore, the sound generated when the first engagement portion (432) and the second engagement portion (442) come into contact with each other is smaller than the sound generated when the impact mechanism applies an impact shock to the output shaft (5; 5B). Therefore, compared to the conventional case in which a large torque is applied to the output shaft (5; 5B) by an impact mechanism, noise generated during operation of the tool (1; 1A; 1B) can be suppressed.

[0195] In the tool (1; 1A; 1B) according to the second aspect, in the first aspect, the internal gear (43; 43B) rotates in the same direction as the transmission body (motor shaft (21; (941)) when the tool bit is in contact with the work target and when the first engagement portion (432) of the internal gear (43; 43B) and the second engagement portion (442) of the planetary carrier (44; 44B) are not in contact with each other. The internal gear (43; 43B) and the output shaft (5; 5B) rotate integrally with the transmission body when the tool bit is in contact with the work target and when the first engagement portion (432) of the internal gear (43; 43B) and the second engagement portion (442) of the planetary carrier (44; 44B) are in contact with each other.

[0196] According to the above configuration, the internal gear (43; 43B) rotates in the same direction as the transmission body (motor shaft (21); (941)) so that when the first engagement portion (432) and the second engagement portion (442) come into contact with each other, the inertia torque of the internal gear (43; 43B) can be converted into a torque to be transmitted to the output shaft (5; 5B), making it possible to transmit a large torque to the output shaft (5; 5B).

[0197] Moreover, the tool (1; 1A; 1B) according to the third aspect is the tool according to the first or second aspect, and further includes a control unit (7) that controls the motor (2). The control unit (7) controls the motor (2) to rotate the transmission body (motor shaft (21); (941)) in a first direction (DR1). After the integral rotation of the internal gear (43; 43B) and the output shaft (5; 5B) stops, the control unit (7) controls the motor (2) to rotate the transmission body in a second direction opposite to the first direction (DR1) for a predetermined time or a predetermined angle. After rotating the transmission body in the second direction for a predetermined time or a predetermined angle, the control unit (7) controls the motor (2) to rotate the transmission body in the first direction (DR1).

[0198] According to the above-described configuration, a period for increasing the inertia torque of the transmission body (motor shaft (21); (941)) can be secured, and the work object can be tightened again by the inertia torque.

[0199] In addition, in the tool (1; 1A; 1B) according to a fourth aspect, in any one of the first to third aspects, the internal gear (43; 43B) further includes a main body portion (431) formed in an annular or cylindrical shape and having a plurality of teeth on an inner peripheral surface. The planetary carrier (44; 44B) further includes a carrier portion (441) connected to each of the shafts of the plurality of planetary gears (42). The first engagement portion (432) of the internal gear (43; 43B) protrudes from the main body portion (431) along the rotation axis (Ax1) of the output shaft (5; 5B). The second engagement portion (442) of the planetary carrier (44; 44B) protrudes from the carrier portion (441) along a direction perpendicular to the rotation axis (Ax1).

[0200] According to the above configuration, the first engagement portion (432) and the second engagement portion (442) protrude in directions perpendicular to each other, so that the tool (1; 1A; 1B) can be made more compact than in the case where they protrude in the same direction, for example.

[0201] The tool (1B) according to a fifth aspect is any one of the first to fourth aspects, and further includes an internal gear (43B) having a main body (431) and a third engagement portion (435). The main body (431) is formed in an annular or cylindrical shape. A plurality of teeth are provided on an inner peripheral surface of the main body (431). The first engagement portion (432) and the third engagement portion (435) of the internal gear (43B) protrude from the main body (431). The planetary carrier (44B) further includes a first carrier portion (441) connected to a first end of each of the shafts (421) of the planetary gears (42), a second carrier portion (46) connected to a second end of each of the shafts (421) of the planetary gears (42), and a fourth engagement portion (464). The planetary gears (42) are disposed between the first carrier part (441) and the second carrier part (46). The second engagement part (442) of the planetary carrier (44B) protrudes from the first carrier part (441). The fourth engagement part (464) of the planetary carrier (44B) protrudes from the second carrier part (46). The third engagement part (435) of the internal gear (43B) and the fourth engagement part (464) of the planetary carrier (44B) are relatively movable along the rotation direction of the transmission body (941). When the first engagement part (432) of the internal gear (43B) and the second engagement part (442) of the planetary carrier (44B) come into contact with each other in response to the rotation of the internal gear (43B), the third engagement part (435) of the internal gear (43B) comes into contact with the fourth engagement part (464) of the planetary carrier (44B).

[0202] According to the above-described configuration, the rotational force of the internal gear (43B) is dispersed between the first carrier portion (441) and the second carrier portion (46) and is transmitted to the planetary carrier (44B). This makes it possible to prevent stress from being concentrated on the internal gear (43B) and the planetary carrier (44B).

[0203] In addition, in the tool (1B) according to the sixth aspect, in the fifth aspect, the first engagement portion (432) and the third engagement portion (435) of the internal gear (43B) protrude from the main body portion (431) along the rotation axis (Ax1) of the output shaft (5B). The second engagement portion (442) of the planetary carrier (44B) protrudes from the first carrier portion (441) along a direction perpendicular to the rotation axis (Ax1). The fourth engagement portion (464) of the planetary carrier (44B) protrudes from the second carrier portion (46) along a predetermined direction perpendicular to the rotation axis (Ax1).

[0204] According to the above configuration, since the first engagement portion (432) and the second engagement portion (442) protrude in directions perpendicular to each other, the tool (1B) can be made more compact than when they protrude in the same direction. Also, since the third engagement portion (435) and the fourth engagement portion (464) protrude in directions perpendicular to each other, the tool (1B) can be made more compact than when they protrude in the same direction.

[0205] In addition, the tool (1B) according to the seventh aspect is the tool according to the fifth or sixth aspect, wherein the internal gear (43B) has a plurality of first engagement portions (432) including the first engagement portion (432) and a plurality of third engagement portions (435) including the third engagement portion (435). The planetary carrier (44B) has a plurality of second engagement portions (442) including the second engagement portion (442) and a plurality of fourth engagement portions (464) including the fourth engagement portion (464).

[0206] According to the above-described configuration, it is possible to further prevent stress from being concentrated on the internal gear (43B) and the planetary carrier (44B).

[0207] The tool (1A) according to an eighth aspect is any one of the first to fourth aspects, and further includes a second sun gear (41S) separate from the first sun gear (41) as the sun gear (41), a plurality of second planetary gears (42S) separate from the plurality of first planetary gears (42) as the plurality of planetary gears (42), and a second planetary carrier (44S) separate from the first planetary carrier (44) as the planetary carrier (44). The second planetary carrier (44S) is fixed to the first sun gear (41) and rotates around the first sun gear (41) in response to the rotation of the first sun gear (41). The second planetary carrier (44S) supports the plurality of second planetary gears (42S) so that they can rotate about their own axes. The plurality of second planetary gears (42S) are disposed around the second sun gear (41S) and mesh with the second sun gear (41S). The internal gear (43) is disposed so as to surround the plurality of first planetary gears (42) and the plurality of second planetary gears (42S), and meshes with the plurality of first planetary gears (42) and the plurality of second planetary gears (42S).

[0208] According to the above-described configuration, the period until the first engagement portion (432) comes into contact with the second engagement portion (442) can be lengthened, and the inertia torque of the transmission body (the motor shaft (21)) can be more reliably maintained at or above a certain value.

[0209] In addition, the tool (1; 1A; 1B) according to a ninth aspect is any one of the first to fifth aspects, and further includes an inertial body (3). The inertial body (3) is disposed between the motor (2) and the internal gear (43; 43B) and rotates integrally with the transmission body (motor shaft (21); (941)).

[0210] According to the above configuration, the inertia torque of the transmission body (motor shaft (21); (941)) can be increased.

[0211] The configurations other than those of the first embodiment are not essential to the tool (1; 1A; 1B) and may be omitted as appropriate. [Explanation of symbols]

[0212] 1;1A;1B Tools 2 Motors 3 Inertial body 5;5B Output shaft 7 Control section 21 Motor shaft (transmission body) 41;41B Sun gear (first sun gear) 41S 2nd sun gear 42 Planetary gear (first planetary gear) 42S 2nd planetary gear 43;43B Internal gear 44;44B Planet carrier (first planet carrier) 44S 2nd planet carrier 46 2nd Carrier Section 421 Axis 431 Main body 432 First engagement part 435 Third engagement part 441 First Carrier Section (Carrier Section) 442 Second engagement part 464 Fourth engagement part 941 Transmission Body Ax1 Rotation axis DR1 1st direction

Claims

1. A motor that rotates a transmission body that transmits torque to another member; A sun gear and an output shaft to which a tool bit is attached and to which the rotation of the sun gear is transmitted; a plurality of planetary gears arranged around the sun gear and meshing with the sun gear; a planetary carrier that rotatably supports the planetary gears and rotates around the sun gear; an internal gear arranged to surround the plurality of planetary gears, meshing with the plurality of planetary gears, and held in a rotatable state; the internal gear is fixed to the transmission body and rotates in response to rotation of the transmission body; The internal gear has a first engagement portion, The planetary carrier has a second engagement portion, The first engagement portion of the internal gear and the second engagement portion of the planetary carrier are relatively movable along a rotation direction of the transmission body and come into contact with each other in response to rotation of the internal gear. tool.

2. the internal gear rotates in the same direction as the transmission body when the tool bit is in contact with a work object and when the first engagement portion of the internal gear and the second engagement portion of the planetary carrier are not in contact with each other, The internal gear and the output shaft rotate integrally with the transmission body when the tool bit is in contact with a work object and when the first engagement portion of the internal gear and the second engagement portion of the planetary carrier are in contact with each other. The tool of claim 1.

3. A control unit for controlling the motor is further provided. The control unit is Controlling the motor to rotate the transmission body in a first direction; After the internal gear and the output shaft stop rotating together, the motor is controlled to rotate the transmission body in a second direction opposite to the first direction for a predetermined time or by a predetermined angle, After rotating the transmission body in the second direction for the predetermined period of time or by the predetermined angle, the motor is controlled to rotate the transmission body in the first direction. The tool of claim 1.

4. The internal gear further includes a main body portion formed in an annular or cylindrical shape and provided with a plurality of teeth on an inner circumferential surface thereof, The planetary carrier further includes a carrier portion coupled to a shaft of each of the plurality of planetary gears, The first engagement portion of the internal gear protrudes from the main body along a rotation axis of the output shaft, The second engagement portion of the planetary carrier protrudes from the carrier portion along a direction perpendicular to the rotation axis. The tool of claim 1.

5. The internal gear is A main body portion formed in an annular or cylindrical shape and having a plurality of teeth on an inner circumferential surface thereof; A third engagement portion, the first engagement portion and the third engagement portion of the internal gear protrude from the main body portion, The planetary carrier is a first carrier portion coupled to a first end of a shaft of each of the plurality of planetary gears; a second carrier portion coupled to a second end of the shaft of each of the plurality of planetary gears; A fourth engagement portion, the plurality of planetary gears are disposed between the first carrier portion and the second carrier portion; The second engagement portion of the planetary carrier protrudes from the first carrier portion, The fourth engagement portion of the planetary carrier protrudes from the second carrier portion, the third engagement portion of the internal gear and the fourth engagement portion of the planetary carrier are relatively movable along a rotation direction of the transmission body, When the first engagement portion of the internal gear and the second engagement portion of the planetary carrier come into contact with each other in response to rotation of the internal gear, the third engagement portion of the internal gear and the fourth engagement portion of the planetary carrier come into contact with each other. The tool of claim 1.

6. the first engagement portion and the third engagement portion of the internal gear protrude from the main body portion along a rotation axis of the output shaft, The second engagement portion of the planetary carrier protrudes from the first carrier portion along a direction perpendicular to the rotation axis, The fourth engagement portion of the planetary carrier protrudes from the second carrier portion along a predetermined direction perpendicular to the rotation axis. The tool of claim 5.

7. The internal gear is A plurality of first engagement portions including the first engagement portion; a plurality of third engagement portions including the third engagement portion, The planetary carrier is A plurality of second engagement portions including the second engagement portion; and a plurality of fourth engagement portions including the fourth engagement portion. The tool of claim 5.

8. a second sun gear separate from the first sun gear as the sun gear; a plurality of second planetary gears different from the plurality of first planetary gears as the plurality of planetary gears; Further comprising a second planetary carrier separate from the first planetary carrier as the planetary carrier, The second planetary carrier is a rotor fixed to the first sun gear and rotating about the first sun gear in response to the rotation of the first sun gear; The second planetary gears are supported rotatably, the plurality of second planetary gears are disposed around the second sun gear and mesh with the second sun gear; the internal gear is disposed so as to surround the plurality of first planetary gears and the plurality of second planetary gears, and meshes with the plurality of first planetary gears and the plurality of second planetary gears; The tool of claim 1.

9. The transmission body further includes an inertia body disposed between the motor and the internal gear and rotating integrally with the transmission body. The tool of claim 1.

Images