Power Tools

Abstract

To provide an electric tool with the high durability of a seal member.SOLUTION: An electric tool 1 is equipped with an output shaft 2, a drive shaft 3, a transmission mechanism 4, a plurality of bearings 5, and a seal member 6. The output shaft 2 has a holding part 21 that holds a tip end tool B1. The drive shaft 3 is rotated by a driving part. The transmission mechanism 4 is provided between the drive shaft 3 and the output shaft 2, and transmits rotations of the drive shaft 3 to the output shaft 2. The plurality of bearings 5 are disposed so as to align in an axial direction D1 of the output shaft 2, and rotatably supports the output shaft 2. The seal member 6 has a through-hole 61 penetrated by the output shaft 2. The seal member 6 is provided so that an inner peripheral surface 610 of the through-hole 61 contacts with an outer peripheral surface 20 of the output shaft 2 in at least one of spaces sandwiched by the adjacent two bearings 5 of the plurality of bearings 5.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates generally to power tools and, more particularly, to power tools having an output shaft. [Background technology]

[0002] Patent Document 1 discloses a rotary impact tool having a drive unit with a motor, an output unit that outputs the rotational drive of the drive unit, and a striking unit that transmits the rotational drive of the drive unit to the output unit with a striking action. The striking unit is composed of a hammer that is rotated by the drive unit, an anvil that has a struck surface that is struck by the hammer and transmits the rotational drive to the output unit, and a buffer member that is attached to the anvil and has lower rigidity than the anvil. The buffer member protrudes from the struck surface in the rotational direction of the anvil. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 5525386 Summary of the Invention [Problem to be solved by the invention]

[0004] In a power tool such as the above-mentioned rotary impact tool, a seal member is often provided inside the power tool, and the seal member is required to have high durability.

[0005] An object of the present disclosure is to provide an electric power tool having a highly durable seal member. [Means for solving the problem]

[0006] An electric power tool according to one aspect of the present disclosure includes an output shaft, a drive shaft, a transmission mechanism, a plurality of bearings, a seal member, and Housing andThe output shaft has a holding portion that holds a tool tip. The drive shaft is rotated by a drive portion. The transmission mechanism is provided between the drive shaft and the output shaft, and transmits rotation of the drive shaft to the output shaft. The multiple bearings are arranged side by side in the axial direction of the output shaft, and rotatably support the output shaft. The seal member has a through hole through which the output shaft is inserted. The seal member is provided in at least one space between two adjacent bearings among the multiple bearings, such that an inner peripheral surface of the through hole contacts an outer peripheral surface of the output shaft. The housing accommodates at least a portion of the output shaft. The seal member is formed of an oil-absorbing material having oil absorption properties. The oil-absorbing material is felt. The housing has a protrusion located in the at least one space in which the seal member is provided. A gap is provided between the seal member and the protrusion. Effect of the Invention

[0007] According to the present disclosure, there is an advantage that the durability of the sealing member is high. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a cross-sectional view of a main part of a power tool according to this embodiment. [Diagram 2] FIG. 2 is an external perspective view of the electric power tool. [Diagram 3] FIG. 3 is an exploded perspective view of a main part of the power tool. [Figure 4] FIG. 4 is an exploded perspective view of a main part of the electric power tool. [Diagram 5] FIG. 5 is an enlarged cross-sectional view of a main part of the power tool. [Figure 6] FIG. 6 is a perspective view of a main part of the electric power tool. [Figure 7] FIG. 7 is an enlarged cross-sectional view of a main part of the electric power tool according to the above modified example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, electric power tools according to embodiments will be described with reference to the drawings. However, the following embodiment is merely one of various embodiments of the present disclosure. The following embodiment can be modified in various ways depending on the design, etc., as long as the object of the present disclosure can be achieved. Also, each figure described in the following embodiment is a schematic diagram, and the size and thickness ratios of each component in the figure do not necessarily reflect the actual dimensional ratios.

[0010] (1) Embodiment 1 (1-1) Overview Hereinafter, an overview of a power tool 1 according to a first embodiment will be described with reference to FIG.

[0011] 1, the power tool 1 according to the first embodiment includes an output shaft 2, a drive shaft 3, a transmission mechanism 4, a plurality of bearings 5, and a seal member 6. It is assumed that an operator uses the power tool 1 for fastening work in which a fastening part (screw, bolt, nut, etc.) is fastened to an object to be fastened (electrical appliance, furniture, etc.). The power tool 1 may also be used for removal work in which an operator loosens a fastening part from the object to be fastened.

[0012] The output shaft 2 has a holding portion 21 that holds the tool bit B1. The drive shaft 3 is rotated by a drive portion 8. The transmission mechanism 4 is provided between the drive shaft 3 and the output shaft 2, and transmits the rotation of the drive shaft 3 to the output shaft 2. The multiple bearings 5 ​​are arranged side by side in the axial direction D1 of the output shaft 2, and rotatably support the output shaft 2. The seal member 6 has a through hole 61 through which the output shaft 2 is inserted. The seal member 6 is provided such that an inner peripheral surface 610 of the through hole 61 contacts an outer peripheral surface 20 of the output shaft 2 in at least one of the spaces sandwiched between adjacent bearings 5 ​​among the multiple bearings 5.

[0013] In the power tool 1 of the first embodiment, the output shaft 2 is supported by a plurality of bearings 5, and therefore, when the output shaft 2 receives the rotation of the drive shaft 3 from the transmission mechanism 4 and rotates along the axial direction D1, movement in a direction intersecting the axial direction D1 can be reduced. In other words, the power tool 1 of the first embodiment can reduce rotational wobble when the output shaft 2 rotates along the axial direction D1.

[0014] Therefore, in the first embodiment, it is possible to prevent the output shaft 2 from being pressed against the seal member 6 provided in the space between adjacent bearings 5 ​​due to rotational wobble. As a result, the power tool 1 of the first embodiment has the effect of preventing wear of the seal member 6 caused by the output shaft 2. In other words, the power tool 1 of the first embodiment has the advantage that the seal member 6 has high durability. The "durability" here refers to the performance that indicates the extent to which deterioration such as wear over time when the power tool 1 is used can be prevented.

[0015] (1-2) Detailed configuration (1-2-1) Overall A detailed configuration of the power tool 1 of the first embodiment will be described below with reference to FIGS.

[0016] As shown in FIG. 1, the power tool 1 includes an output shaft 2, a drive shaft 3, a transmission mechanism 4, a plurality of bearings 5, a sealing member 6, a housing 7, a drive unit 8, a control unit 91, a planetary gear mechanism 92, and an operating unit 93.

[0017] In the following description, the axial direction D1 of the output shaft 2 is defined as the front-rear direction, the anvil 42 side as viewed from the hammer 41 is defined as the front, and the hammer 41 side as viewed from the anvil 42 is defined as the rear. In the following description, the direction in which a second portion 72 (described later) and a grip portion 74 (described later) are aligned is defined as the up-down direction (Y direction in FIG. 2), the second portion 72 side as viewed from the grip portion 74 is defined as the top, and the grip portion 74 side as viewed from the second portion 72 is defined as the bottom. In addition, a direction perpendicular to the front-rear direction and the up-down direction is defined as the left-right direction. However, these definitions are not intended to define the direction in which the power tool 1 is used.

[0018] (1-2-2) Housing 1, the housing 7 accommodates at least a part of the output shaft 2, the drive shaft 3, the transmission mechanism 4, a plurality of bearings 5, a seal member 6, a drive unit 8, a control unit 91, and a planetary gear mechanism 92. As shown in FIGS. 1 and 2, the housing 7 has a first portion 71, a second portion 72, a third portion 73, a grip portion 74, and a battery mounting portion 75.

[0019] (Part 1) As shown in Figs. 3 and 4, the first portion 71 has a first bottom portion 711 and a first side portion 712. The first bottom portion 711 is disk-shaped. The thickness direction of the first bottom portion 711 is along the front-rear direction. The first bottom portion 711 has a through hole 713 formed in the front-rear direction. The through hole 713 is provided in the center of the first bottom portion 711. The output shaft 2 is inserted through the through hole 713. The first side portion 712 protrudes rearward from the periphery of the first bottom portion 711.

[0020] (Second part) 3 and 4, the second portion 72 has a second bottom portion 721 and a second side portion 722. The second bottom portion 721 has an elliptical plate shape. The thickness direction of the second bottom portion 721 is aligned with the front-rear direction.

[0021] The second side portion 722 has a cylindrical shape. The second side portion 722 protrudes forward from the periphery of the second bottom portion 721.

[0022] 1, the front opening of the second side portion 722 is covered by the first portion 71. More specifically, the front opening of the second side portion 722 is covered by the first portion 71 such that the front portion of the inner surface of the second side portion 722 is in close contact with the outer surface of the first side portion 712 and the front end portion of the second side portion 722 is in contact with the peripheral portion of the first bottom portion 711.

[0023] 3 and 4, the second portion 72 has a plurality of ventilation holes 723 provided in the second side portion 722. More specifically, the second portion 72 has a plurality of ventilation holes 723 provided behind the second side portion 722.

[0024] (3rd part) 3 and 4, the third portion 73 has a main portion 731, a tubular portion 732, and a third side portion 733. The main portion 731 is an annular plate member. The thickness direction of the main portion 731 is aligned with the front-rear direction.

[0025] The shape of the tubular portion 732 is cylindrical with both ends open, as shown in Figures 3 and 4. The tubular portion 732 protrudes forward from the inner edge of the main portion 731. The tubular portion 732 of the first embodiment houses a plurality of bearings 5 ​​and a seal member 6, as shown in Figure 1. The output shaft 2 is inserted into the inside of the tubular portion 732.

[0026] 1 and 5, the cylindrical portion 732 supports the multiple bearings 5. In other words, the housing 7 supports the multiple bearings 5. The inner diameter of the cylindrical portion 732 is approximately the same as the outer shape of each of the multiple bearings 5, or is slightly larger than the outer shape of each of the multiple bearings 5. As a result, each of the multiple bearings 5 ​​is fitted inside the cylindrical portion 732, and the cylindrical portion 732 supports the multiple bearings 5.

[0027] As shown in FIG. 5, the cylindrical portion 732 has a protruding portion 76. In other words, the housing 7 has the protruding portion 76 in the cylindrical portion 732. The protruding portion 76 protrudes from the inner peripheral surface of the cylindrical portion 732 toward the output shaft 2. The protruding portion 76 extends around the inner peripheral surface of the cylindrical portion 732 in the circumferential direction of the cylindrical portion 732. That is, the protruding portion 76 is provided in an annular shape on the inner peripheral surface of the cylindrical portion 732. The protruding portion 76 is located in a space where the seal member 6 is provided, among the spaces sandwiched between two adjacent bearings 5 ​​among the multiple bearings 5. This configuration has the advantage that the gap between the two adjacent bearings 5 ​​can be easily maintained, making it easier to provide the seal member 6.

[0028] The third side portion 733 has a cylindrical shape as shown in Figures 3 and 4. The third side portion 733 protrudes rearward from the outer edge of the main portion 731. The third side portion 733 of the first embodiment accommodates at least a part of the drive shaft 3 and the transmission mechanism 4 as shown in Figure 1. The outer surface of the third side portion 733 is in close contact with the inner surface of the second side portion 722 of the second section 72 as shown in Figure 1.

[0029] The first part 71 is attached to the third part 73. More specifically, the first part 71 is attached to the third part 73 such that the front end of the tubular part 732 contacts the through hole 713 of the first bottom part 711 of the first part 71.

[0030] (Grip section) The grip portion 74 protrudes from the second portion 72. More specifically, the grip portion 74 protrudes downward from the second portion 72, as shown in Fig. 2. An operator can grasp the grip portion 74 to perform operations such as screw tightening.

[0031] (Battery compartment) The battery attachment section 75 is shaped like a substantially rectangular parallelepiped. As shown in FIG. 2, the battery attachment section 75 is connected to the lower end of the grip section 74. A rechargeable battery pack is removably attached to the battery attachment section 75. The power tool 1 operates using the battery pack as a power source. In other words, the battery pack is a power source that supplies a current that drives the drive section 8. The battery pack is not a component of the power tool 1. However, the power tool 1 may include a battery pack. The battery pack includes a battery pack configured by connecting multiple secondary batteries (e.g., lithium ion batteries) in series, and a case that houses the battery pack.

[0032] (1-2-3) Drive unit 1, the driving unit 8 is housed in the rear of the second section 72. The driving unit 8 includes a rotor 81 having a rotating shaft 811 and a permanent magnet, and a stator 82 having a coil. The rotor 81 rotates relative to the stator 82 due to electromagnetic interaction between the permanent magnet and the coil.

[0033] Moreover, the driving unit 8 is a servo motor. The torque and rotation speed of the driving unit 8 change according to the control by the control unit 91 (servo driver). More specifically, the control unit 91 controls the operation of the driving unit 8 by feedback control that controls the torque and rotation speed of the driving unit 8 so as to approach target values.

[0034] (1-2-4) Drive shaft The drive shaft 3 is connected to the rotating shaft 811 via the planetary gear mechanism 92. As a result, the drive shaft 3 rotates in conjunction with the rotating shaft 811 of the drive unit 8. That is, the drive shaft 3 is rotated by the drive unit 8.

[0035] The planetary gear mechanism 92 converts the rotation speed and torque of the rotating shaft 811 of the drive unit 8 into the rotation speed and torque required for the screw turning operation. The planetary gear mechanism 92 is a reduction gear. The torque of the rotating shaft 811 of the drive unit 8 is transmitted to the drive shaft 3 via the planetary gear mechanism 92.

[0036] (1-2-5) Transmission mechanism As shown in Fig. 1, the transmission mechanism 4 is accommodated in the third portion 73 of the housing 7. The transmission mechanism 4 of the first embodiment has an impact mechanism. That is, the power tool 1 of the first embodiment is an electric impact power tool that performs a tightening operation while performing an impact operation by the impact mechanism. In the impact operation, the impact mechanism generates an impact force based on the power of the drive unit 8, and the impact force acts on the tool bit B1.

[0037] 1, the transmission mechanism 4 of the first embodiment further includes a hammer 41, an anvil 42, an elastic member 43, and two spheres (first spheres) 47. The torque transmitted to the drive shaft 3 is transmitted to the hammer 41. This causes the hammer 41 to rotate. The torque of the hammer 41 is transmitted to the anvil 42. This causes the anvil 42 to rotate.

[0038] The hammer 41 moves relative to the anvil 42, and applies a striking force to the anvil 42 by receiving power from the drive unit 8. As shown in FIG. 6, the hammer 41 has a hammer body 410 and a plurality (two in this case) of hammer claws 411. The hammer body 410 has a cylindrical shape. The hammer 41 has a plurality of hammer claws 411 provided on the hammer body 410. The plurality of hammer claws 411 protrude from a surface of the hammer body 410 facing the anvil 42. The plurality of hammer claws 411 are disposed at approximately equal intervals in the circumferential direction of the hammer body 410. When viewed from the front side of the hammer 41, each of the plurality of hammer claws 411 has a fan-like shape.

[0039] 1, the hammer body 410 has a through hole 412 through which the drive shaft 3 is inserted. More specifically, the through hole 412 is fitted into the outer circumferential surface of the drive shaft 3 so as to be movable in the axial direction of the drive shaft 3 and rotatable in the rotational direction. That is, the hammer 41 is fitted into the outer circumferential surface of the drive shaft 3 so as to be rotatable and movable forward and backward.

[0040] The hammer body 410 has two grooves 413 on the inner peripheral surface of the through hole 412. The drive shaft 3 has two grooves 31 on its outer peripheral surface. The two grooves 31 may be connected. Two first spheres 47 are sandwiched between the two grooves 413 and the two grooves 31. The two grooves 413, the two grooves 31, and the two first spheres 47 form a cam mechanism. The hammer 41 is movable in the axial direction (front-rear direction) of the drive shaft 3 relative to the drive shaft 3 while the two first spheres 47 move in the grooves 413 and the grooves 31, and is rotatable relative to the drive shaft 3. As the hammer 41 moves toward the anvil 42 or away from the anvil 42 along the axial direction of the drive shaft 3, the hammer 41 rotates relative to the drive shaft 3.

[0041] The anvil 42 is mechanically connected to the output shaft 2. In the first embodiment, the anvil 42 is integrally formed with the output shaft 2 as shown in Figs. 1 and 6. The anvil 42 rotates together with the output shaft 2. As shown in Fig. 6, the anvil 42 has an anvil body 420 and a plurality (two) of anvil claws 421. The anvil body 420 has a circular ring shape. The anvil body 420 faces the hammer body 410 in the front-rear direction. The anvil claws 421 protrude from the anvil body 420 in the radial direction of the anvil body 420. The number of the anvil claws 421 is equal to the number of the hammer claws 411. The anvil claws 421 are engageable with the hammer claws 411.

[0042] When the impact mechanism is not performing an impact operation, the hammer 41 and the anvil 42 rotate together while the multiple hammer claws 411 and the multiple anvil claws 421 are in contact with each other in the rotation direction of the drive shaft 3. Therefore, at this time, the drive shaft 3, the hammer 41, the anvil 42, and the output shaft 2 rotate together.

[0043] As shown in Fig. 1, the elastic member 43 is sandwiched between the hammer 41 and the planetary gear mechanism 92. The elastic member 43 in this embodiment is a conical coil spring. The transmission mechanism 4 further includes a plurality of (two in Fig. 1) spheres (second spheres) 48 sandwiched between the hammer 41 and the elastic member 43, and a ring 49. This allows the hammer 41 to rotate relative to the elastic member 43. The hammer 41 receives a force from the elastic member 43 in a direction toward the output shaft 2 (forward) in the axial direction D1 of the output shaft 2.

[0044] Hereinafter, movement of the hammer 41 toward the output shaft 2 in the axial direction D1 of the output shaft 2 will be referred to as "the hammer 41 moves forward." Also, below, movement of the hammer 41 away from the output shaft 2 in the axial direction D1 of the output shaft 2 will be referred to as "the hammer 41 moves backward."

[0045] The impact mechanism performs an impact operation when a torque condition regarding the magnitude of the torque (hereinafter referred to as load torque) applied to the output shaft 2 is satisfied. The impact operation is an operation in which an impact force is applied from the hammer 41 to the anvil 42. In this embodiment, the torque condition is that the load torque is equal to or greater than a predetermined value. That is, when the load torque increases, the component of the force generated between the hammer 41 and the anvil 42 in the direction in which the hammer 41 retreats also increases. When the load torque exceeds a predetermined value, the hammer 41 retreats while compressing the elastic member 43. Then, as the hammer 41 retreats, the hammer claws 411 overcome the anvil claws 421, and the hammer 41 rotates. Thereafter, the hammer 41 advances by receiving a return force from the elastic member 43. Then, when the drive shaft 3 rotates approximately half a turn, the hammer claws 411 collide with the side surfaces of the anvil claws 421. In the impact mechanism, the multiple hammer claws 411 collide with the multiple anvil claws 421 every time the drive shaft 3 makes approximately a half rotation. In other words, the hammer 41 applies an impact force (rotational impact force) to the anvil 42 every time the drive shaft 3 makes approximately a half rotation.

[0046] In this way, in the impact mechanism, collisions occur repeatedly between the hammer 41 and the anvil 42. Due to the torque caused by these collisions, the parts to be fastened can be tightened more strongly than in the case where there is no collision.

[0047] (1-2-6) Output shaft The output shaft 2 has a cylindrical shape as shown in Fig. 6. The axial direction D1 of the output shaft 2 is the front-rear direction. The output shaft 2 protrudes forward from the anvil body 420.

[0048] The output shaft 2 is inserted through the through hole 713 of the first portion and the cylindrical portion 732 of the third portion 73. A front portion of the output shaft 2 protrudes from the through hole 713 of the first portion. In other words, the front portion of the output shaft 2 is exposed to the outside of the housing 7.

[0049] 1, the output shaft 2 has a holder 21 that holds the tool bit B1. The holder 21 is provided at an end of the output shaft 2 that protrudes from the through hole 713 of the first section. In other words, the holder 21 is provided at the front end of the output shaft 2. The output shaft 2 is rotated together with the tool bit B1 by the drive unit 8.

[0050] In this embodiment, the holding part 21 is provided with a tool tip B1 (see Figs. 1 and 2) that can be detachably attached via a chuck. The tool tip B1 may be directly provided on the holding part 21 so that it can be detachably attached. The tool tip B1 may also be formed integrally with the holding part 21. The tool tip B1 is, for example, a driver bit. When the tool tip B1 rotates while being fitted with a fastening part, it becomes possible to perform operations such as fastening or loosening the fastening part.

[0051] (1-2-7) Bearings The multiple bearings 5 ​​rotatably support the output shaft 2. In other words, the multiple bearings 5 ​​support the output shaft 2. More specifically, as shown in Fig. 5, the multiple bearings 5 ​​are fitted between the cylindrical portion 732 of the housing 7 and the output shaft 2, thereby rotatably supporting the output shaft 2.

[0052] In the first embodiment, there are two bearings 5. The two bearings 5 ​​are arranged side by side in the axial direction D1 (front-rear direction) of the output shaft inside the cylindrical portion 732 of the housing 7. In the first embodiment, the front bearing 5 is a ball bearing 51, and the rear bearing 5 is a plain bearing 52. The ball bearing 51 is arranged between the output shaft 2 and the inner surface of the cylindrical portion 732 on the front side of the convex portion 76. On the other hand, the plain bearing 52 is arranged between the output shaft 2 and the inner surface of the cylindrical portion 732 on the rear side of the convex portion 76.

[0053] 5, ball bearing 51 has inner ring 511, outer ring 512, and multiple spheres 513. Inner ring 511 and outer ring 512 are annular members. Inner ring 511 is provided inside outer ring 512. That is, the outer diameter of inner ring 511 is formed smaller than the inner diameter of outer ring 512.

[0054] The inner diameter of the inner ring 511 is formed to be approximately the same as the outer diameter of the output shaft 2 or slightly larger than the outer diameter of the output shaft 2. On the other hand, the outer diameter of the outer ring 512 is formed to be approximately the same as the inner diameter of the cylindrical portion 732 on the front side of the convex portion 76 or slightly smaller than the inner diameter of the cylindrical portion 732 on the front side of the convex portion 76.

[0055] A groove 5111 is formed along the circumferential direction on the outer side of the inner ring 511. Similarly, a groove 5121 is formed along the circumferential direction on the inner side of the outer ring 512. A plurality of spheres 513 are sandwiched between the groove 5111 of the inner ring 511 and the groove 5121 of the outer ring 512 at equal intervals.

[0056] As described above, when the output shaft 2 rotates, the inner ring 511 rotates integrally with the output shaft 2, and the plurality of spheres 513 roll between the groove portion 5111 of the inner ring 511 and the groove portion 5121 of the outer ring 512. On the other hand, even when the output shaft 2 rotates, the outer ring 512 does not rotate and is fixed to the cylindrical portion 732 of the housing 7. In other words, when the output shaft 2 rotates, the inner ring 511 rotates relative to the outer ring 512.

[0057] The plain bearing 52 is formed of a single annular member. The inner diameter of the plain bearing 52 is formed to be substantially the same as the outer diameter of the output shaft 2 or slightly larger than the outer diameter of the output shaft 2. On the other hand, the outer diameter of the plain bearing 52 is formed to be substantially the same as the inner diameter of the cylindrical portion 732 on the rear side of the convex portion 76 or slightly smaller than the inner diameter of the cylindrical portion 732 on the rear side of the convex portion 76. A lubricant such as grease or lubricating oil is applied between the plain bearing 52 and the output shaft 2. Even if the output shaft 2 rotates, the plain bearing 52 does not rotate and is fixed to the cylindrical portion 732 of the housing 7.

[0058] (1-2-8) Sealing material The seal member 6 is a disk-shaped plate member. As shown in FIG. 1, the seal member 6 has a through hole 61 through which the output shaft 2 is inserted. That is, the shape of the seal member 6 is annular, as shown in FIGS. 3 and 4. The inner diameter of the seal member 6 is formed to be substantially the same as the outer diameter of the output shaft 2. Therefore, the inner circumferential surface 610 of the through hole 61 of the seal member 6 contacts the outer circumferential surface 20 of the output shaft 2. On the other hand, the outer diameter of the seal member 6 is formed to be slightly smaller than the inner diameter of the protrusion 76. Therefore, a gap is provided between the seal member 6 and the protrusion 76 of the housing 7.

[0059] The seal member 6 of the first embodiment is made of an oil-absorbing material having oil absorption properties. The term "oil-absorbing property" here refers to the property of absorbing oil such as grease or lubricating oil. An example of the oil-absorbing material is felt. The seal member 6 made of felt has a function of trapping foreign matter that tries to pass through the seal member 6. The oil-absorbing material of the seal member 6 is not limited to felt, and may be nonwoven fabric, paper, woven fabric, or knitted fabric.

[0060] The seal member 6 is provided in at least one space between two adjacent bearings 5 ​​among the multiple bearings 5. In the first embodiment, the seal member 6 is provided in a space between a ball bearing 51 and a plain bearing 52 as shown in FIG. 1. More specifically, the seal member 6 is provided in the space between the ball bearing 51 and the plain bearing 52 as shown in FIG. 1 such that an inner peripheral surface 610 of the through hole 61 contacts an outer peripheral surface 20 of the output shaft 2. Therefore, the seal member 6 of the first embodiment rotates integrally with the output shaft 2. The seal member 6 may be fixed to the housing 7 without rotating integrally with the output shaft 2.

[0061] In the first embodiment, as shown in Fig. 5, the dimension of the seal member 6 in the axial direction D1 is smaller than the dimension of the convex portion 76 of the housing 7 in the axial direction D1. Therefore, the seal member 6 in the first embodiment is provided with a gap between it and each of the ball bearing 51 and the sliding bearing 52. That is, in the first embodiment, the seal member 6 is not compressed in the axial direction D1 by the ball bearing 51 and the sliding bearing 52. Therefore, the seal member 6 formed of a felt member has an advantage that it can efficiently absorb the lubricant that tries to pass through the seal member 6, or efficiently entangle foreign matter that tries to pass through the seal member 6.

[0062] The seal member 6 prevents foreign matter present outside the housing 7 from entering the housing 7. The "foreign matter" referred to here is, for example, dust such as iron powder, or liquid such as rainwater. This configuration has the advantage of reducing the possibility of the power tool 1 breaking down or malfunctioning due to foreign matter.

[0063] The seal member 6 prevents the lubricant present inside the housing 7 from leaking out of the housing 7. The "lubricant" here is grease, lubricating oil, or the like, and is applied between the sliding bearing 52 and the output shaft 2. The "lubricant" is not limited to being applied between the sliding bearing 52 and the output shaft 2, and may be applied to the transmission mechanism 4 or the drive unit 8. In other words, the "lubricant" is not limited to being applied to a location inside the housing 7. This configuration has the advantage of reducing the possibility that the object to be fastened or the fastened part will be contaminated by the lubricant.

[0064] (1-2-9) Operation section As shown in Figs. 1 and 2, the operating unit 93 protrudes from the grip portion 74. The operating unit 93 receives operations for controlling the rotation of the rotating shaft 811 of the drive unit 8. The drive unit 8 can be switched on and off by pulling the operating unit 93. In addition, the rotation speed of the rotating shaft can be adjusted by the pulling amount of the operating unit 93. The greater the pulling amount, the faster the rotation speed of the rotating shaft.

[0065] (1-2-10) Control section The control unit 91 rotates or stops the rotating shaft 811 of the drive unit 8 in accordance with the pulling amount of the operation of pulling the operating unit 93, and also controls the rotation speed of the rotating shaft.

[0066] The control unit 91 includes, for example, a microcontroller. The control unit 91 can change the rotation speed of the output shaft 2 and the tool tip B1 by changing the rotation speed of the rotation shaft 811. The control unit 91 changes the rotation speed of the rotation shaft 811 by, for example, changing the power supplied to the drive unit 8.

[0067] (1-3) Variations Below, we will list some variations of the above-mentioned embodiment 1. The following variations may be realized in appropriate combination.

[0068] In the above-described first embodiment, the front bearing 5 is a ball bearing 51, and the rear bearing 5 is a plain bearing 52. However, both of the two bearings 5 ​​may be ball bearings 51 or plain bearings 52.

[0069] In the above-described first embodiment, the sealing member 6 is made of felt, and therefore has both oil absorbency and a function of trapping foreign matter attempting to pass through the sealing member 6. However, the sealing member 6 may have only oil absorbency or only a function of trapping foreign matter.

[0070] In the above-described first embodiment, the seal member 6 is provided with a gap between it and each of the ball bearing 51 and the sliding bearing 52. However, the seal member 6 may be provided with a gap between it and one of the ball bearing 51 and the sliding bearing 52, and in contact with the other of the ball bearing 51 and the sliding bearing 52. In other words, the seal member 6 may be provided with a gap between it and at least one of the ball bearing 51 and the sliding bearing 52.

[0071] In the above-described first embodiment, the seal member 6 is not compressed in the axial direction D1 by the ball bearing 51 and the plain bearing 52, but may be compressed in the axial direction D1 by the ball bearing 51 and the plain bearing 52. In other words, the seal member 6 may be in contact with both the ball bearing 51 and the plain bearing 52.

[0072] In the above-described first embodiment, the outer diameter of the seal member 6 is formed to be slightly smaller than the inner diameter of the protrusion 76. However, the outer diameter of the seal member 6 may be formed to be substantially the same as the inner diameter of the protrusion 76. In other words, the seal member 6 may be in contact with the protrusion 76 of the housing 7.

[0073] In the above-described first embodiment, the first portion 71 and the third portion 73 of the housing 7 are separate members, but this is not essential. The first portion 71 and the third portion 73 may be formed from a single member.

[0074] (2) Embodiment 2 (2-1) Overview Hereinafter, a power tool 1a according to the second embodiment will be described with reference to Fig. 7. The same components as those in the first embodiment will be denoted by the same reference numerals and the description thereof will be omitted.

[0075] The power tool 1a of the second embodiment differs from the power tool 1 of the first embodiment in that a seal member 6a is made of a rubber material.

[0076] (2-2) Details The seal member 6a of the second embodiment is made of a rubber material. With this configuration, the seal member 6a has the effect of sealing between the cylindrical portion 732 of the housing 7 and the output shaft 2. Therefore, the seal member 6a has the advantage of being able to suppress the leakage of the lubricant present inside the housing 7 to the outside of the housing 7 and the intrusion of foreign matter present outside the housing 7 into the inside of the housing 7. The "rubber material" in this disclosure is a material that has the property (elasticity) of deforming in the direction of the applied force when a force is applied and returning to the shape before the force is applied when the force is removed. In other words, the "rubber material" is an elastic material.

[0077] The seal member 6a of the second embodiment is a disk-shaped plate member having a through hole 61 through which the output shaft 2 is inserted, similar to the seal member 6 of the first embodiment. That is, the shape of the seal member 6a is annular. The inner diameter of the seal member 6a is formed to be substantially the same as the outer diameter of the output shaft 2. Therefore, the inner circumferential surface 610 of the through hole 61 of the seal member 6a contacts the outer circumferential surface 20 of the output shaft 2. On the other hand, the outer diameter of the seal member 6a is formed to be slightly smaller than the inner diameter of the protrusion 76. Therefore, a gap is provided between the seal member 6a and the protrusion 76 of the housing 7.

[0078] In the second embodiment, the dimension of the seal member 6a in the axial direction D1 is equal to or larger than the dimension of the convex portion 76 in the axial direction D1. Therefore, the seal member 6a contacts each of the two adjacent bearings 5. Specifically, the seal member 6a in the second embodiment contacts each of the ball bearing 51 and the plain bearing 52 as shown in FIG. 7. That is, the seal member 6a is sandwiched between the ball bearing 51 and the plain bearing 52 along the axial direction D1. In a state where the seal member 6a is sandwiched between the ball bearing 51 and the plain bearing 52, the seal member 6a is compressed along the axial direction D1. More specifically, in a state where the seal member 6a is sandwiched between the ball bearing 51 and the plain bearing 52, the seal member 6a is compressed along the axial direction D1 so that the dimension of the seal member 6a in the axial direction D1 is approximately the same as the dimension of the convex portion 76 in the axial direction D1. According to this configuration, the seal member 6a has an effect of being able to better seal the gap between the cylindrical portion 732 of the housing 7 and the output shaft 2. Therefore, the sealing member 6a has the advantage of being able to better prevent the lubricant present inside the housing 7 from leaking out to the outside of the housing 7, and to better prevent foreign matter present outside the housing 7 from entering the inside of the housing 7.

[0079] (2-3) Modifications Below, we will list some variations of the above-mentioned embodiment 2. The following variations may be realized in appropriate combination.

[0080] The seal member 6a may rotate integrally with the output shaft 2, or may be fixed to the housing 7 without rotating integrally with the output shaft 2.

[0081] In the above-described second embodiment, similarly to the first embodiment, the front bearing 5 is a ball bearing 51 and the rear bearing 5 is a plain bearing 52, as shown in FIG. 6. However, both of the two bearings 5 ​​may be ball bearings 51 or plain bearings 52. When both of the two bearings 5 ​​are ball bearings 51, it is preferable that the seal member 6a rotates integrally with the output shaft 2. On the other hand, when both of the two bearings 5 ​​are plain bearings 52, it is preferable that the seal member 6a is fixed to the housing 7 without rotating integrally with the output shaft 2.

[0082] (summary) The electric power tool (1, 1a) of the first aspect of the embodiment includes an output shaft (2), a drive shaft (3), a transmission mechanism (4), a plurality of bearings (5), and a seal member (6, 6a). The output shaft (2) has a holder (21) that holds a tool bit (B1). The drive shaft (3) is rotated by a drive unit. The transmission mechanism (4) is provided between the drive shaft (3) and the output shaft (2) and transmits the rotation of the drive shaft (3) to the output shaft (2). The plurality of bearings (5) are arranged in the axial direction (D1) of the output shaft (2) and rotatably support the output shaft (2). The seal member (6, 6a) has a through hole (61) through which the output shaft (2) is inserted. The sealing members (6, 6a) are arranged so that the inner surface (610) of the through hole (61) contacts the outer surface (20) of the output shaft (2) in at least one of the spaces sandwiched between two adjacent bearings (5) among the multiple bearings (5).

[0083] This embodiment has the advantage that the seal members (6, 6a) have high durability.

[0084] The power tool (1, 1a) according to the second aspect of the embodiment is the same as the power tool (1, 1a) according to the first aspect, and further includes a housing (7) that accommodates at least a portion of the output shaft (2). The housing (7) supports a plurality of bearings (5).

[0085] According to this embodiment, there is an advantage that wear of the seal members (6, 6a) caused by the output shaft (2) can be further suppressed.

[0086] In the power tool (1, 1a) of the third aspect according to the embodiment, in the second aspect, the sealing member (6, 6a) prevents foreign matter present outside the housing (7) from entering the inside of the housing (7).

[0087] This embodiment has the advantage of reducing the possibility of the power tool (1, 1a) breaking down or malfunctioning due to foreign matter.

[0088] In the power tool (1, 1a) of the fourth aspect according to the embodiment, in the second aspect, the seal member (6, 6a) prevents the lubricant present inside the housing (7) from leaking out to the outside of the housing (7).

[0089] This aspect has the advantage that the possibility of the object or part being fastened being contaminated by the lubricant can be reduced.

[0090] In the electric power tool (1, 1a) according to a fifth aspect of the embodiment, in any one of the first to fourth aspects, the transmission mechanism (4) includes a hammer (41) and an anvil (42). The hammer (41) is fitted to the outer circumferential surface (20) of the drive shaft (3) so as to be rotatable and movable forward and backward, and is provided with a plurality of hammer claws (411). The anvil (42) includes a plurality of anvil claws (421) engageable with the plurality of hammer claws (411), and is mechanically connected to the output shaft (2).

[0091] According to this embodiment, there is an advantage that wear of the seal member (6, 6a) of the impact power tool can be suppressed.

[0092] In the power tool (1) of the sixth aspect according to the embodiment, in any of the first to fifth aspects, the seal member (6) is made of an oil-absorbent material having oil-absorbency.

[0093] This embodiment has the advantage that it is possible to suck up oil, such as grease or lubricating oil, present inside the housing (7).

[0094] In the power tool (1) of the seventh aspect according to the embodiment, in the sixth aspect, the oil-absorbent material is felt.

[0095] This embodiment has the advantage that foreign matter attempting to pass through the seal member (6) can be trapped.

[0096] The power tool (1) of an eighth aspect according to the present embodiment is the power tool of the seventh aspect, further including a housing (7) that accommodates at least a portion of the output shaft (2). The housing (7) has a protrusion (76) located in at least one space in which the seal member (6) is provided.

[0097] This embodiment has the advantage that the seal member (6) can be easily provided.

[0098] In the power tool (1) of the ninth aspect according to the embodiment, in the eighth aspect, the dimension of the seal member (6) in the axial direction (D1) is smaller than the dimension of the protrusion (76) in the axial direction (D1).

[0099] According to this embodiment, there is an advantage that the seal member (6) can efficiently absorb oil or efficiently trap foreign matter.

[0100] In the power tool (1a) of the tenth aspect according to the embodiment, in any one of the first to fifth aspects, the seal member (6a) is made of a rubber material.

[0101] This embodiment has the advantage that the seal member (6a) can seal between the housing (7) and the output shaft (2).

[0102] The power tool (1a) of an eleventh aspect according to the present embodiment is the power tool of the tenth aspect, further including a housing (7) that accommodates at least a portion of the output shaft (2). The housing (7) has a protrusion (76) located in at least one space in which the seal member (6a) is provided.

[0103] This embodiment has the advantage that the seal member (6a) can be easily provided.

[0104] The power tool (1a) of the twelfth aspect according to the embodiment is the power tool (1a) of the eleventh aspect, wherein the dimension of the seal member (6a) in the axial direction (D1) is equal to or greater than the dimension of the protrusion (76) in the axial direction (D1).

[0105] This embodiment has the advantage that the seal member (6a) can better seal the gap between the housing (7) and the output shaft (2).

[0106] In the power tool (1a) of the thirteenth aspect according to the embodiment, in the twelfth aspect, the seal members (6a) are in contact with each of the two adjacent bearings (5).

[0107] This embodiment has the advantage that the seal member (6a) can better seal the gap between the housing (7) and the output shaft (2).

[0108] The above-mentioned embodiment 1 and embodiment 2 are merely examples of the present invention. Therefore, the present invention is not limited to the above-mentioned embodiment 1 and embodiment 2, and it goes without saying that various modifications can be made according to the design and the like, even if they are other than the above-mentioned embodiment, as long as they do not deviate from the technical idea of ​​the present invention. [Explanation of symbols]

[0109] 1, 1a Power tools 2 Output shaft 20 Outer surface 21 Holding part 3 Drive shaft 31 Groove 4 Transmission mechanism 41 Hammer 411 Hammer Claw 42 Anvil 421 Anvil Claw 5 Bearings 51 Ball Bearing 52 Plain bearing 6, 6a Sealing material 61 Through hole 610 Inner surface 7. Housing 76 Convex B1 Tip tool D1 Axial direction

Claims

1. an output shaft having a holder for holding a tool tip; A drive shaft rotated by a drive unit; a transmission mechanism provided between the drive shaft and the output shaft, the transmission mechanism transmitting rotation of the drive shaft to the output shaft; a plurality of bearings arranged side by side in the axial direction of the output shaft and rotatably supporting the output shaft; a seal member having a through hole through which the output shaft is inserted, the seal member being provided such that an inner peripheral surface of the through hole comes into contact with an outer peripheral surface of the output shaft in at least one space between two adjacent bearings among the plurality of bearings; a housing that accommodates at least a portion of the output shaft, The sealing member is formed of an oil-absorbing material having oil-absorbing properties, the oil-absorbing material is felt; the housing has a protrusion located in the at least one space in which the seal member is provided, A gap is provided between the sealing member and the protruding portion. A power tool characterized by:

2. The housing supports the plurality of bearings. The power tool according to claim 1 .

3. The sealing member prevents foreign matter present outside the housing from entering the inside of the housing. The power tool according to claim 2 .

4. The seal member prevents the lubricant present inside the housing from leaking out to the outside of the housing. The power tool according to claim 2 .

5. The transmission mechanism includes: a hammer fitted to an outer circumferential surface of the drive shaft so as to be rotatable and movable forward and backward, the hammer having a plurality of hammer claws; an anvil having a plurality of anvil claws engageable with the plurality of hammer claws and mechanically connected to the output shaft; The power tool according to claim 1 .

6. A dimension of the sealing member in the axial direction is smaller than a dimension of the convex portion in the axial direction. The power tool according to claim 1 .

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