Impact rotary tool

Abstract

The present disclosure addresses the problem of further inhibiting noise generated by an impact rotary tool. An impact rotary tool (1) comprises: a hammer (5); an anvil (6); an output shaft (7); a bearing (first bearing 91); and an elastic member (100). The output shaft (7) receives a force in the rotational direction of the anvil (6) from the anvil (6), and rotates together with the anvil (6). The bearing is held by a housing (2), and rotatably supports the output shaft (7). The elastic member (100) is elastically deformed in a thrust direction along the rotational axis of the output shaft (7). The output shaft (7) has a fitting part (75) into which a tip tool (110) is fitted. The elastic member (100) is disposed between the tip tool (110) and the bottom section (76) of the fitting part (75).

Description

Impact rotary tool

[0001] The present disclosure generally relates to an impact rotary tool, and more particularly to an impact rotary tool provided with a hammer.

[0002] Patent Document 1 describes a connecting tool capable of achieving low noise while maintaining high versatility and an impact tool provided with the same.

[0003] In the impact tool in Patent Document 1, rotational driving force from a motor is transmitted to an impact mechanism portion through a speed reduction mechanism portion, and a connecting tool that intermittently transmits the rotational impact force generated in the impact mechanism portion to a tip tool is detachably attached to an anvil. A socket adapter (first adapter) and a bit adapter (second adapter) for detachably attaching the tip tool are fitted together, and an elastic body is provided between the fitting portions. Further, the elastic body is formed of an integrally molded bottomed cylindrical body and is provided in the axial direction and the rotational direction of the fitting portion between the socket adapter and the bit adapter.

[0004] The impact tool of Patent Document 1 can achieve low noise of the impact tool by providing an elastic body between the socket adapter and the bit adapter. By the way, it is desired to further suppress the noise generated by the impact tool.

[0005] Japanese Patent Application Laid-Open No. 2007-054934

[0006] In view of the above problems, the present disclosure aims to provide an impact rotary tool capable of further suppressing the noise generated by the impact rotary tool.

[0007] An impact rotary tool according to one aspect of the present disclosure comprises a hammer, an anvil, an output shaft, a housing, a bearing, and an elastic member. The hammer rotates by power from a motor. The anvil rotates by receiving an impact force from the hammer in the direction of the hammer's rotation. The output shaft rotates with the anvil by receiving a force from the anvil in the direction of the anvil's rotation. The housing houses the hammer and the anvil. The bearing is held in the housing and rotatably supports the output shaft. The elastic member is elastically deformable in the thrust direction along the rotation axis of the output shaft. The output shaft has a fitting portion into which a tool tip is fitted. The elastic member is positioned between the tool tip and the bottom of the fitting portion.

[0008] Figure 1 is a perspective view of an impact rotary tool according to an embodiment of the present disclosure. Figure 2 is a cross-sectional view of the same impact rotary tool. Figure 3 is a side view of the main part of the same impact rotary tool. Figure 4 is an exploded perspective view of the main part of the same impact rotary tool. Figure 5 is an exploded perspective view of the main part of the same impact rotary tool from a different angle. Figure 6 is a perspective view of the anvil and output shaft of the same impact rotary tool.

[0009] The embodiments and modifications described below are merely examples of the present disclosure, and the present disclosure is not limited to these embodiments and modifications. Various modifications are possible depending on the design, etc., as long as they do not depart from the technical concept of the present disclosure.

[0010] The figures described in this disclosure are schematic diagrams, and the ratios of the size and thickness of each component in each figure do not necessarily reflect the actual dimensional ratios. The arrows indicating directions in the drawings are examples only and are not intended to define the direction in which the impact rotary tool 1 is used. Furthermore, the arrows indicating directions in the drawings are merely for illustrative purposes and do not represent actual dimensions. More specifically, as shown in Figure 1, the direction in which the anvil 6 and the output shaft 7 are aligned is defined as the front-rear direction, with the side of the output shaft 7 being defined as the front when viewed from the anvil 6, and the side of the anvil 6 being defined as the rear when viewed from the output shaft 7. In addition, the direction in which the housing 21 and the grip 22, which will be described later, are aligned is defined as the up-down direction, with the side of the housing 21 being defined as the top when viewed from the grip 22, and the side of the grip 22 being defined as the bottom when viewed from the housing 21. Furthermore, the direction perpendicular to the front-rear direction and the up-down direction is defined as the left-right direction.

[0011] In this disclosure, the thrust direction refers to the direction along the rotation axis of the output shaft 7. In other words, the thrust direction is the direction along the front-rear direction.

[0012] (Embodiment) The impact rotary tool 1 according to this embodiment will be described below with reference to Figures 1 to 6.

[0013] (1) Overview An impact rotary tool 1 according to one aspect of the present disclosure, as shown in Figure 2, comprises a hammer 5, an anvil 6, an output shaft 7, a housing 2, a bearing (first bearing 91), and an elastic member 100. The hammer 5 rotates by obtaining power from a motor 3. The anvil 6 rotates by receiving an impact force from the hammer 5 in the direction of the hammer 5's rotation. The output shaft 7 rotates together with the anvil 6 by receiving a force from the anvil 6 in the direction of the anvil 6's rotation. The housing 2 houses the hammer 5 and the anvil 6. The bearing is held in the housing 2 and rotatably supports the output shaft 7. The elastic member 100 elastically deforms in the thrust direction along the rotation axis of the output shaft 7. The output shaft 7 has a fitting portion 75. A tip tool 110 is fitted into the fitting portion 75. The elastic member 100 is positioned between the tip tool 110 and the bottom portion 76 of the fitting portion 75.

[0014] This configuration makes it possible to further suppress the noise generated by the impact rotary tool 1.

[0015] (2) Configuration The impact rotary tool 1 of this embodiment will be described in detail below.

[0016] In this embodiment, the impact rotary tool 1 is a portable electric tool. As shown in Figures 1 and 2, the impact rotary tool 1 comprises a housing 2, a motor 3, a hammer 5, an anvil 6, an output shaft 7, a cushioning member 8, a first bearing 91, and an elastic member 100. Furthermore, the impact rotary tool 1 comprises a transmission mechanism 4, a second bearing 92, a first stopper 93, a second stopper 94, a drive circuit 11, a control circuit 12, and an operating unit 13.

[0017] (2.1) Housing The housing 2 houses the hammer 5 and the anvil 6. Furthermore, the housing 2 houses the motor 3, the transmission mechanism 4, the cushioning member 8, the first bearing 91, the second bearing 92, the first stopper 93, the second stopper 94, the drive circuit 11, and the control circuit 12. As shown in Figure 1, the housing 2 has a housing section 21, a grip section 22, and a mounting section 23.

[0018] The housing section 21 has a hollow cylindrical shape. As shown in Figure 1, the housing section 21 includes a first housing section 211 and a second housing section 212. As shown in Figure 2, the first housing section 211 is located in front of the second housing section 212. The first housing section 211 is connected to the second housing section 212. The first housing section 211 houses at least the hammer 5 and the anvil 6. The first housing section 211 holds the first bearing 91 and the second bearing 92. The first housing section 211 has a through hole 213 through which the output shaft 7 is inserted.

[0019] As shown in Figure 1, the grip portion 22 protrudes from the outer circumferential surface of the housing portion 21 in one direction along the radial direction of the housing portion 21. More specifically, the grip portion 22 protrudes from the second housing portion 212. This one direction is along the vertical direction. The grip portion 22 is formed in a hollow cylindrical shape that is elongated in this one direction. The worker can grasp the grip portion 22 and perform tasks such as tightening screws. The grip portion 22 is also equipped with an operating portion 13 that receives input from the worker.

[0020] The internal space of the grip portion 22 is connected to the internal space of the housing portion 21. The upper end of the grip portion 22 in the longitudinal direction is connected to the housing portion 21. The lower end of the grip portion 22 in the longitudinal direction is connected to the mounting portion 23.

[0021] A battery pack is detachably attached to the mounting section 23. The impact rotary tool 1 operates using the battery pack as its power source. That is, the battery pack is the power source that supplies the current to drive the motor 3. The battery pack is not a component of the impact rotary tool 1. However, the impact rotary tool 1 may be equipped with a battery pack.

[0022] (2.2) Motor As shown in Figure 2, the motor 3 is housed in the housing 21 of the housing 2. The motor 3 is, for example, a brushless motor. The motor 3 includes a rotor 31 having a rotating shaft 311 and permanent magnets, and a stator 32 having coils. Due to the electromagnetic interaction between the permanent magnets and coils, the rotor 31 rotates relative to the stator 32.

[0023] Furthermore, motor 3 is a servo motor. The torque and rotational speed of motor 3 change according to the control by control circuit 12. Control circuit 12 is a servo driver. Control circuit 12 controls the torque and rotational speed of motor 3 to approach target values. Control circuit 12 controls the operation of motor 3 by feedback control.

[0024] The operator operates the control unit 13. Specifically, the operator retracts the control unit 13. The control circuit 12 determines a target value for the rotational speed of the motor 3 according to the amount the control unit 13 is retracted. The greater the amount the control unit 13 is retracted, the higher the target value for the rotational speed of the motor 3 the control circuit 12 sets.

[0025] The drive circuit 11 includes a substrate and a plurality of electronic components mounted on the substrate. The plurality of electronic components include a plurality of power elements that form an inverter circuit. Each power element is, for example, a FET (Field Effect Transistor) element.

[0026] The control circuit 12 controls the motor 3 via the drive circuit 11. Specifically, the control circuit 12 controls the power supplied to the motor 3 via multiple power elements (inverter circuits) by switching the multiple power elements of the drive circuit 11 on and off.

[0027] (2.3) Transmission Mechanism As shown in Figure 2, the transmission mechanism 4 is housed in the housing section 21 of the housing 2. The transmission mechanism 4 transmits the power of the motor 3 to the hammer 5. The hammer 5 rotates as the transmission mechanism 4 transmits the power of the motor 3 to the hammer 5.

[0028] The transmission mechanism 4 includes a planetary gear mechanism 41, a drive shaft 42, a return spring 43, two first spherical bodies 44 (steel balls), two second spherical bodies 45 (steel balls), and a ring 46.

[0029] The planetary gear mechanism 41 converts the rotational speed and torque of the motor 3's rotating shaft 311 into a predetermined rotational speed and predetermined torque. The planetary gear mechanism 41 is a reduction gear. The torque of the motor 3's rotating shaft 311 is transmitted to the drive shaft 42 via the planetary gear mechanism 41. The torque of the drive shaft 42 is transmitted to the hammer 5. The hammer 5 rotates as a result of the torque of the drive shaft 42 being transmitted to the hammer 5. In other words, the hammer 5 rotates by obtaining power from the motor 3.

[0030] The return spring 43 in this embodiment is a conical coil spring. The return spring 43 applies a forward pushing force to the hammer 5. A ring 46 is positioned between the return spring 43 and the hammer 5. Two second spherical bodies 45 are sandwiched between the ring 46 and the hammer 5. Therefore, the hammer 5 is rotatable relative to the return spring 43.

[0031] (2.4) Hammer, Anvil and Output Shaft The impact rotary tool 1 of this embodiment is an electric impact driver that performs screw tightening while performing an impact operation. During the impact operation, the hammer 5 applies a striking force to the anvil 6. The striking force applied from the hammer 5 to the anvil 6 is transmitted to the tip tool 110 via the output shaft 7.

[0032] As shown in Figures 3 to 5, the hammer 5 includes a hammer body 51 and two hammer claws 52. The hammer body 51 is cylindrical in shape. The two hammer claws 52 protrude forward from the hammer body 51. The hammer body 51 has a through hole 510 through which the drive shaft 42 is inserted.

[0033] The hammer body 51 has two grooves 511 on the inner circumferential surface of the through hole 510. As shown in Figure 2, the drive shaft 42 has two grooves 421 on its outer circumferential surface. The two grooves 421 are connected. A corresponding first spherical body 44 is sandwiched between each groove 511 and the corresponding groove 421. The grooves 511, grooves 421 and the first spherical body 44 have a cam mechanism. As the first spherical body 44 moves in the grooves 511 and 421, the hammer 5 is movable relative to the drive shaft 42 in the axial direction (forward and backward direction) of the drive shaft 42 and is also rotatable relative to the drive shaft 42. As the hammer 5 moves forward or backward along the axial direction of the drive shaft 42, the hammer 5 rotates relative to the drive shaft 42.

[0034] The anvil 6 faces the hammer body 51 in the front-rear direction. As shown in Figures 3 to 5, the anvil 6 includes an anvil body 61, two anvil claws 62, and two first contact portions 63. The anvil body 61 is cylindrical in shape. The two anvil claws 62 protrude radially from the anvil body 61. The two first contact portions 63 protrude forward from the anvil body 61. In other words, the two first contact portions 63 protrude in the thrust direction from the anvil body 61. The two first contact portions 63 are arranged point-symmetrically with respect to the rotation axis of the output shaft 7.

[0035] As shown in Figure 5, the anvil body 61 has a first recess 611 on its rear surface into which the tip of the drive shaft 42 is inserted. Also, as shown in Figure 4, the anvil body 61 has a second recess 612 on its front surface into which the cushioning member 8 is inserted.

[0036] As the hammer 5 rotates, as shown in Figure 3, the two hammer claws 52 push the two anvil claws 62 in the direction of the hammer 5's rotation, causing the anvil 6 to rotate. In other words, the anvil 6 rotates due to the impact force from the hammer 5 in the direction of the hammer 5's rotation.

[0037] As shown in Figures 2 and 5, the output shaft 7 includes an output shaft body 71, two second contact portions 72, a holding portion 73, two steel balls 731, an adjustment portion 74, and a fitting portion 75.

[0038] The output shaft body 71 is cylindrical in shape. The output shaft body 71 is inserted through a through hole 213 in the housing 2, and the front end (tip) of the output shaft body 71 is exposed to the outside of the housing 2. In addition, as shown in Figure 1, a holding part 73 and an adjustment part 74 are provided at the front end of the output shaft body 71. Furthermore, a fitting part 75 is formed at the front end of the output shaft body 71. As shown in Figure 5, the output shaft body 71 has a recess 711 on its rear surface into which a cushioning member 8 is inserted. As shown in Figure 2, the output shaft body 71 has two tunnel sections 77 for arranging two iron balls 731, which will be described later. These tunnel sections are formed so as to penetrate from the outer circumferential surface of the output shaft body 71 to the fitting part 75 when viewed from above. Each of the two tunnel sections 77 is positioned point-symmetrically with respect to the rotation axis of the output shaft 7. The two tunnel sections 77 are carved in a circular shape when viewed from above.

[0039] The two second contact portions 72 protrude rearward from the output shaft body 71 along the thrust direction. The two second contact portions 72 are aligned in the rotational direction of the output shaft 7 so as to face each other. The two second contact portions 72 contact the two first contact portions 63. The two second contact portions 72 receive rotational force from the two first contact portions 63 that rotates the output shaft 7.

[0040] The holding portion 73 is formed in a hollow cylindrical shape. Furthermore, as shown in Figure 2, each of the two steel balls 731 is positioned point-symmetrically with respect to the rotation axis of the output shaft 7, so as to contact the inner circumferential surface of the holding portion 73. The two steel balls 731 are housed in two tunnel portions 77 provided in the output shaft body 71, as shown in Figure 2. The two steel balls 731 hold the tip tool 110 by gripping it. In other words, the holding portion 73 and the two steel balls 731 together have the function of holding the tip tool 110.

[0041] The adjustment part 74 is formed in a hollow cylindrical shape. As shown in Figures 3 to 5, the adjustment part 74 is formed to follow the entire circumference of the outer surface of the holding part 73. The adjustment part 74 has the function of adjusting the force that the holding part 73 applies to the output shaft 7 in the direction of the rotation axis. More specifically, by adjusting the force that the holding part 73 applies to the output shaft 7 in the direction of the rotation axis, the force with which the two steel balls 731 grip and hold the tip tool 110 can be adjusted. In other words, the adjustment part 74 makes it possible to attach and detach the tip tool 110 held by the holding part 73 by adjusting the force that the holding part 73 applies to the output shaft 7 in the direction of the rotation axis.

[0042] The fitting portion 75, when viewed from the front, is, for example, hexagonal in shape. As shown in Figure 2, the fitting portion 75 is formed at the front end of the output shaft body 71 as a groove into which the tip tool 110 is fitted along the thrust direction. That is, the tip tool 110 is fitted into the fitting portion 75. In the fitting portion 75, as shown in Figure 2, a tunnel portion 77 for fitting two steel balls 731 is formed at approximately the center position along the thrust direction. In the fitting portion 75, a space F1 is formed between the bottom portion 76 of the fitting portion 75 and the elastic member 100.

[0043] As shown in Figures 4 and 5, when the anvil 6 rotates, the two first contact points 63 of the anvil 6 push the two second contact points 72 of the output shaft 7 in the direction of the anvil 6's rotation, causing the output shaft 7 to rotate. The output shaft 7 rotates at the same rotational speed as the anvil 6. That is, the output shaft 7 receives a force from the anvil 6 in the direction of the anvil 6's rotation and rotates together with the anvil 6.

[0044] The rotation direction of the anvil 6 is the same as the rotation direction of the hammer 5. As shown in FIG. 6, the anvil 6 and the output shaft 7 are configured such that the concavities and convexities formed by the two first contact portions 63 mesh with the concavities and convexities formed by the two second contact portions 72.

[0045] Here, the tip tool 110 is, for example, a driver bit. The tip tool 110 is held by the output shaft 7 by being sandwiched between two iron balls 731 of the output shaft 7. The tip tool 110 is fitted to a screw (such as a bolt or a screw) of the work target. When the tip tool 110 rotates in a state where the tip tool 110 is fitted to the screw, operations such as tightening or loosening the screw become possible. In the present embodiment, the tip tool 110 is not a component of the impact rotary tool 1. However, the tip tool 110 may be a component of the impact rotary tool 1.

[0046] When the impact rotary tool 1 is not performing an impact operation, the hammer 5 and the anvil 6 rotate at the same rotational speed while the two hammer claws 52 and the two anvil claws 62 are in contact with each other in the rotation direction of the hammer 5. Therefore, when the impact rotary tool 1 is not performing an impact operation, the drive shaft 42, the hammer 5, the anvil 6, and the output shaft 7 rotate at the same rotational speed.

[0047] When the torque condition regarding the magnitude of the torque (hereinafter referred to as the load torque) applied to the output shaft 7 is satisfied, the impact rotary tool 1 performs an impact operation. The impact operation is an operation of applying an impact force from the hammer 5 to the anvil 6. In the present embodiment, the torque condition is that the load torque becomes a predetermined value or more. That is, as the load torque increases, among the forces generated between the hammer 5 and the anvil 6, the component force in the direction of retracting the hammer 5 also increases. When the load torque becomes a predetermined value or more, the hammer 5 retracts while compressing the return spring 43. Then, as the hammer 5 retracts, the two hammer claws 52 of the hammer 5 rotate over the two anvil claws 62 of the anvil 6 while the hammer 5 rotates. After that, the hammer 5 advances by receiving the return force from the return spring 43. Then, when the drive shaft 42 rotates approximately half a turn, the two hammer claws 52 of the hammer 5 collide with the side surface 620 of the two anvil claws 62 of the anvil 6. Every time the drive shaft 42 rotates approximately half a turn, the two hammer claws 52 of the hammer 5 collide with the two anvil claws 62 of the anvil 6. That is, every time the drive shaft 42 rotates approximately half a turn, the hammer 5 applies an impact force to the anvil 6.

[0048] As described above, in the impact rotary tool 1, the collision between the hammer 5 and the anvil 6 repeatedly occurs. Due to the torque caused by this collision, the screw can be tightened more strongly compared to the case where there is no collision.

[0049] (2.5) Buffer member As shown in FIGS. 2, 4, and 5, the buffer member 8 includes a first portion 81 and a second portion 82. The shapes of the first portion 81 and the second portion 82 are, for example, cylindrical.

[0050] The first portion 81 is an elastic body such as rubber. The first portion 81 elastically deform in the thrust direction (front-rear direction).

[0051] The second portion 82 is formed of, for example, metal as a material. The second portion 82 is formed separately from the anvil 6 and the output shaft 7.

[0052] The elastic modulus of the second portion 82 in the thrust direction is greater than that of the first portion 81 in the thrust direction. The first portion 81 and the second portion 82 are aligned in the thrust direction, as shown in Figure 4.

[0053] As shown in Figure 2, the buffer member 8 is sandwiched between the anvil 6 and the output shaft 7. More specifically, as shown in Figures 4 and 5, the second portion 82 is inserted into the second recess 612 of the anvil 6. The first portion 81 is inserted into the recess 711 of the output shaft 7. The first portion 81 is sandwiched between the second portion and the output shaft 7. The second portion 82 is sandwiched between the first portion 81 and the anvil 6.

[0054] The cushioning member 8 is sandwiched between the anvil 6 and the output shaft 7, thereby regulating the distance between the anvil 6 and the output shaft 7. In other words, because the cushioning member 8 is sandwiched between the anvil 6 and the output shaft 7, the distance between the anvil 6 and the output shaft 7 is determined by the length of the cushioning member 8 in the thrust direction.

[0055] The buffer member 8 is positioned on the rotation axis of the output shaft 7. Therefore, the stress acting on the anvil 6 and the output shaft 7 is likely to be distributed isotropically around the rotation axis of the output shaft 7. In other words, the buffer member 8 can suppress stress concentration between the anvil 6 and the output shaft 7.

[0056] (2.6) First and Second Bearings As shown in Figure 2, the first bearing 91 is held in the housing 2 and rotatably supports the output shaft 7. More specifically, the first bearing 91 is held in the first housing 211. The first bearing 91 is in contact with two first contact portions 63 and two second contact portions 72 and rotatably supports the anvil 6 and the output shaft 7.

[0057] The first bearing 91 is, for example, a needle bearing. By using a needle bearing for the first bearing 91, the possibility of thrust vibrations from the anvil 6 and output shaft 7 being directly transmitted to the first bearing 91 can be reduced. Therefore, the possibility of thrust loads concentrating near the contact points with the first bearing 91 on the anvil 6 and output shaft 7 can be reduced. In other words, the durability of the anvil 6 and output shaft 7 is improved.

[0058] As shown in Figure 4, the external shape of the first bearing 91 is annular. The first bearing 91 surrounds the two first contact portions 63 of the anvil 6 and the two second contact portions 72 of the output shaft 7. More specifically, the first bearing 91 surrounds the two first contact portions 63 from their front ends to their rear ends. The first bearing 91 also surrounds the two second contact portions 72 from their front ends to their rear ends.

[0059] The first bearing 91 rotatably supports the anvil 6 by contacting the two first contact portions 63 of the anvil 6 and the anvil body 61.

[0060] The first bearing 91 rotatably supports the output shaft 7 by contacting the two second contact portions 72 of the output shaft 7 and the output shaft body 71.

[0061] The second bearing 92 is positioned in front of the first bearing 91. The second bearing 92 is held in the housing 2. More specifically, the second bearing 92 is held in the first housing 211. The second bearing 92 rotatably supports the output shaft 7.

[0062] The second bearing 92 is, for example, a ball bearing. The external shape of the second bearing 92 is annular, as shown in Figure 4.

[0063] The second bearing 92 is in contact with the output shaft body 71 in order to rotatably support the output shaft 7. By providing the second bearing 92, the possibility of axial runout of the output shaft 7 can be reduced.

[0064] Furthermore, in order to suppress rattling in the front-rear direction of the first bearing 91 and the second bearing 92, a first stopper 93 and a second stopper 94 are provided, as shown in Figures 2 and 4.

[0065] The first stopper 93 has an annular shape. The first stopper 93 is positioned behind the first bearing 91. The first stopper 93 faces the first bearing 91.

[0066] The shape of the second stopper 94 is annular. The second stopper 94 is positioned in front of the first bearing 91. More specifically, the second stopper 94 is positioned between the first bearing 91 and the second bearing 92. The second stopper 94 faces both the first bearing 91 and the second bearing 92.

[0067] When the first bearing 91 attempts to move in the front-rear direction, its movement is restricted by contacting the first stopper 93 or the second stopper 94. Similarly, when the second bearing 92 attempts to move backward, its movement is restricted by contacting the second stopper 94.

[0068] (2.7) Elastic Member The elastic member 100 undergoes elastic deformation in the thrust direction along the rotation axis of the output shaft 7. The elastic member 100 is made of urethane. The elastic member 100 may be made of rubber or the like. Here, the hardness of the urethane is 50° or more and 95° or less. In this embodiment, the hardness of the urethane is Shore hardness (Hs). Shore hardness is an index of hardness. Specifically, for the hardness of a material for which plastic deformation is not appropriate (for example, the hardness of rubber), the repulsive force due to the elasticity of the material or the amount of elastic deformation is measured, and the result is expressed as Shore hardness. The elastic member 100 is cylindrical, as shown in Figures 4 and 5. The axis of the elastic member 100 is located on the rotation axis of the output shaft 7. The elastic member 100 is located near the bottom 76, as shown in Figure 2. More specifically, the elastic member 100 is positioned between the rear end 111 of the tip tool 110 and the bottom 76 of the fitting portion 75 when the tip tool 110 is held by the holding portion 73. That is, the elastic member 100 is positioned between the tip tool 110 and the bottom 76 of the fitting portion 75. Furthermore, the elastic member 100 is positioned so that at least a portion of the front surface of the elastic member 100 is in contact with the rear end 111 of the tip tool 110. Here, the elastic member 100 is positioned so that the entire front surface of the elastic member 100 is in contact with the rear end 111 of the tip tool 110. Since at least a portion of the front surface of the elastic member 100 is in contact with the rear end 111 of the tip tool 110, vibrations of the tip tool 110 are absorbed by the elastic member 100 when screwing with the impact rotary tool 1. As a result, noise can be suppressed even more than in the conventional method.

[0069] Furthermore, a space F1 is formed between the elastic member 100 and the bottom portion 76. The formation of the space F1 between the elastic member 100 and the bottom portion 76 makes it easier for the elastic member 100 to elastically deform in the thrust direction. In other words, the elastic member 100 becomes more adept at absorbing the noise (vibration of the tip tool 110) generated by the impact rotary tool 1.

[0070] (3) Advantages As described above, the impact rotary tool 1 according to this embodiment comprises a hammer 5, an anvil 6, an output shaft 7, a housing 2, a bearing (first bearing 91), and an elastic member 100, as shown in Figure 2. The hammer 5 rotates by obtaining power from the motor 3. The anvil 6 rotates by receiving an impact force from the hammer 5 in the direction of the hammer 5's rotation. The output shaft 7 rotates together with the anvil 6 by receiving a force from the anvil 6 in the direction of the anvil 6's rotation. The housing 2 houses the hammer 5 and the anvil 6. The bearing is held in the housing 2 and rotatably supports the output shaft 7. The elastic member 100 elastically deforms in the thrust direction along the rotation axis of the output shaft 7. The output shaft 7 has a fitting portion 75. The tip tool 110 is fitted into the fitting portion 75. The elastic member 100 is positioned between the tip tool 110 and the bottom portion 76 of the fitting portion 75.

[0071] This configuration allows for further suppression of noise generated by impact rotary tools.

[0072] (4) Modifications The following are examples of modifications. The modifications described below can be applied in appropriate combination with the above embodiments.

[0073] (4.1) Modification 1 In the above embodiment, as shown in Figure 2, a space F1 (gap) is formed between the elastic member 100 and the bottom portion 76, but the configuration is not limited to this.

[0074] A space F1 does not necessarily have to be formed between the elastic member 100 and the bottom 76. In other words, there does not need to be a gap between the elastic member 100 and the bottom 76. By having no gap between the elastic member 100 and the bottom 76, the elastic member 100 can absorb the noise generated by the impact rotary tool 1. In Modification 1, the noise suppression by the elastic member 100 is smaller than when a space F1 is formed between the elastic member 100 and the bottom 76. However, since the elastic member 100 absorbs the vibration of the tip tool 110, noise can be suppressed even further than in the conventional method. For this reason, the concept of Modification 1 is also included in this disclosure.

[0075] (4.2) Modification 2 In the above embodiment, the shape of the elastic member 100 is cylindrical as shown in Figures 4 and 5, but it is not limited to this configuration. The shape of the elastic member 100 can be any shape as long as it is possible for the elastic member 100 to elastically deform along the thrust direction. The shape of the elastic member 100 may be hexagonal prism or square prism. That is, the shape of the elastic member 100 may be polygonal prism. Alternatively, the shape of the elastic member 100 may be conical or pyramidal. Here, the tip of the conical elastic member 100 may be positioned in the forward direction or in the backward direction.

[0076] In other words, the shape of the elastic member 100 is such that it contacts the tip tool 110.

[0077] (Other Modifications of the Embodiment) The following lists other modifications of the embodiment. These modifications may be implemented in appropriate combinations. Furthermore, these modifications may be implemented in appropriate combinations with the modifications described above.

[0078] The number of hammer claws 52 and anvil claws 62 is not limited to two, but may be one or three or more.

[0079] The number of first contact portions 63 on the anvil 6 and the number of second contact portions 72 on the output shaft 7 are not limited to two, but may be one or three or more.

[0080] In this embodiment, the first portion 81 is positioned in front of the second portion 82. Alternatively, the second portion 82 may be positioned in front of the first portion 81.

[0081] The cushioning member 8 may include a plurality of first portions 81.

[0082] The cushioning member 8 may include a plurality of second portions 82.

[0083] In this embodiment, the first bearing 91 surrounds the first contact portion 63 of the anvil 6. Alternatively, the first bearing 91 may surround only a portion of the first contact portion 63.

[0084] In this embodiment, the first bearing 91 surrounds the second contact portion 72 of the output shaft 7. Alternatively, the first bearing 91 may surround only a portion of the second contact portion 72.

[0085] In the above embodiment, the first bearing 91 is configured to rotatably support the anvil 6 by contacting the two first contact portions 63 of the anvil 6 and the anvil body 61, but the configuration is not limited to this. The first bearing 91 may also rotatably support the anvil 6 by contacting the two first contact portions 63 without contacting the anvil body 61. That is, the first bearing 91 rotatably supports the anvil 6 by contacting at least the two first contact portions 63 of the anvil 6 and the anvil body 61.

[0086] In the above embodiment, the first bearing 91 is configured to rotatably support the output shaft 7 by contacting the two second contact portions 72 of the output shaft 7 and the output shaft body 71, but the configuration is not limited to this. The first bearing 91 may also rotatably support the anvil 6 by contacting the two second contact portions 72 without contacting the output shaft body 71. That is, the first bearing 91 rotatably supports the output shaft 7 by contacting at least two of the two second contact portions 72 of the output shaft 7 and the output shaft body 71.

[0087] The first bearing 91 is not limited to a needle bearing. The first bearing 91 may be, for example, a bushing, a ball bearing, or a double-row angular contact ball bearing.

[0088] The second bearing 92 is not limited to a ball bearing. The second bearing 92 may be, for example, a bushing, a needle bearing, or a double-row angular contact ball bearing.

[0089] The second portion 82 may be formed integrally with the anvil 6 or the output shaft 7.

[0090] The first part 81 and the second part 82 may be joined to each other by adhesive or other means.

[0091] The magnitude of the maximum load transmitted from the hammer 5 to the first part 81 may also be defined as being equal to the maximum spring force acting on the hammer 5 from the return spring 43.

[0092] (Summary) As described above, the impact rotary tool (1) of the first embodiment comprises a hammer (5), an anvil (6), an output shaft (7), a housing (2), a bearing (first bearing 91), and an elastic member (100). The hammer (5) rotates by obtaining power from a motor (3). The anvil (6) rotates by receiving an impact force from the hammer (5) in the direction of the hammer's rotation. The output shaft (7) rotates together with the anvil (6) by receiving a force from the anvil (6) in the direction of the anvil's rotation. The housing (2) houses the hammer (5) and the anvil (6). The bearing (first bearing 91) is held in the housing (2) and rotatably supports the output shaft (7). The elastic member (100) elastically deforms in the thrust direction along the rotation axis of the output shaft (7). The output shaft (7) has a fitting portion (75). The tip tool (110) is fitted into the mating portion (75). The elastic member (100) is positioned between the tip tool (110) and the bottom portion (76) of the mating portion (75).

[0093] This configuration further suppresses the noise generated by the impact rotary tool (1). Specifically, by placing the elastic member (100) between the tip tool (110) and the bottom (76) of the fitting portion (75), the noise generated by the impact rotary tool (1) can be reduced by several dB.

[0094] In the second embodiment of the impact rotary tool (1), the elastic member (100) is formed in a cylindrical shape, as in the first embodiment. The axis of the elastic member (100) is positioned on the rotation axis of the output shaft (7).

[0095] This configuration allows for the even distribution of collision noise caused by the anvil (6) and the output shaft (7). In other words, it is possible to further suppress the noise generated by the impact rotary tool (1).

[0096] In the third embodiment of the impact rotary tool (1), the elastic member (100) is made of urethane, as in the first or second embodiment.

[0097] With this configuration, since urethane is an elastic material with excellent wear resistance, the elastic member (100) can be made more resistant to friction and used for a longer period of time. In other words, because the elastic member (100) is made of urethane, the collision noise caused by the collision between the anvil (6) and the output shaft (7) can be further suppressed. That is, the noise generated by the impact rotary tool (1) can be further suppressed.

[0098] In the impact rotary tool (1) of the fourth embodiment, the hardness of the urethane (for example, the elastic member 100) is 50° or more and 95° or less, as in the third embodiment.

[0099] With this configuration, by setting the hardness of the urethane forming the elastic member (100) to 50° or more and 95° or less, the collision noise caused by the collision between the anvil (6) and the output shaft (7) can be further suppressed. In other words, the noise generated by the impact rotary tool (1) can be further suppressed.

[0100] 1. Impact rotary tool 2. Housing 3. Motor 5. Hammer 6. Anvil 7. Output shaft 75. Mating part 76. Bottom part 100. Elastic member 110. Tip tool

Claims

1. An impact rotary tool comprising: a hammer that rotates by obtaining power from a motor; an anvil that rotates by receiving an impact force from the hammer in the direction of the hammer's rotation; an output shaft that rotates together with the anvil by receiving a force from the anvil in the direction of the anvil's rotation; a housing that houses the hammer and the anvil; a bearing held in the housing and rotatably supporting the output shaft; and an elastic member that elastically deforms in the thrust direction along the rotation axis of the output shaft, wherein the output shaft has a fitting portion into which a tip tool is fitted, and the elastic member is positioned between the tip tool and the bottom of the fitting portion.

2. The impact rotary tool according to claim 1, wherein the elastic member is formed in a cylindrical shape, and the axis of the elastic member is positioned on the rotation axis of the output shaft.

3. The impact rotary tool according to claim 1 or 2, wherein the elastic member is made of urethane.

4. The impact rotary tool according to claim 3, wherein the hardness of the urethane is 50° or more and 95° or less.

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