Impact rotary tools

Abstract

The objective of this disclosure is to further suppress the noise generated by impact rotary tools. [Solution] The 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 rotates with the anvil 6 by receiving a force from the anvil 6 in the direction of the anvil 6's rotation. 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 into which the tip tool 110 is fitted. The elastic member 100 is positioned between the tip tool 110 and the bottom portion 76 of the fitting portion 75.

Description

Technical Field

[0004] , , , , ,

[0006] , , , ,

[0005] , , , , ,

[0001] The present disclosure generally relates to impact rotary tools, and more particularly to impact rotary tools equipped with hammers.

Background Art

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

[0003] In the impact tool of Patent Document 1, rotational power from a motor is transmitted to an impact mechanism portion through a speed reduction mechanism portion, and a connection tool that intermittently transmits the rotational impact force generated in the impact mechanism portion to a tip tool is configured by fitting a socket adapter (first adapter) detachably attached to an anvil and a bit adapter (second adapter) detachably attaching the tip tool, and an elastic body is interposed in the fitting portion. Further, the elastic body is configured as an integrally formed bottomed cylindrical body and is interposed in the axial direction and the rotational direction of the fitting portion of the socket adapter and the bit adapter.

Prior Art Documents

Patent Documents

[0004] i

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] The impact tool of Patent Document 1 can achieve low noise of the impact tool by interposing an elastic body between the socket adapter and the bit adapter. However, it is desired to further suppress the noise generated by the impact tool.

[0006] This disclosure is made in view of the above-mentioned problems and aims to provide an impact rotary tool that can further suppress the noise generated by the impact rotary tool. [Means for solving the problem]

[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 powered by 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. [Effects of the Invention]

[0008] According to this disclosure, the noise generated by impact rotary tools can be further suppressed. [Brief explanation of the drawing]

[0009] [Figure 1] Figure 1 is a perspective view of an impact rotary tool according to an embodiment of the present disclosure. [Figure 2] Figure 2 is a cross-sectional view of the same impact rotary tool. [Figure 3] Figure 3 is a side view of the main part of the impact rotary tool shown above. [Figure 4] Figure 4 is an exploded perspective view of the main components of the impact rotary tool shown above. [Figure 5] Figure 5 is an exploded perspective view of the main components of the same impact rotary tool, seen from a different angle. [Figure 6] Figure 6 is a perspective view of the anvil and output shaft of the same impact rotary tool. [Modes for carrying out the invention]

[0010] 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.

[0011] 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 illustrative 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-to-back direction, with the output shaft 7 side being defined as the front when viewed from the anvil 6 and the anvil 6 side 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 housing 21 side being defined as the top when viewed from the grip 22 and the grip 22 side being defined as the bottom when viewed from the housing 21. Furthermore, the direction perpendicular to the front-to-back direction and the up-and-down direction is defined as the left-to-right direction.

[0012] 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.

[0013] (Embodiment) The impact rotary tool 1 according to this embodiment will be described below with reference to Figures 1 to 6.

[0014] (1) Overview An impact rotary tool 1 according to one aspect of the present disclosure includes 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 FIG. 2. The hammer 5 rotates by obtaining power from a motor 3. The anvil 6 rotates by receiving an impact force in the rotation direction of the hammer 5 from the hammer 5. The output shaft 7 rotates together with the anvil 6 by receiving a force in the rotation direction of the anvil 6 from the anvil 6. The housing 2 houses the hammer 5 and the anvil 6. The bearing is held by 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 fitting portion 75 is fitted with a tip tool 110. The elastic member 100 is disposed between the tip tool 110 and the bottom portion 76 of the fitting portion 75.

[0015] According to this configuration, the noise generated by the impact rotary tool 1 can be further suppressed.

[0016] (2) Configuration Hereinafter, the impact rotary tool 1 of the present embodiment will be described in detail.

[0017] In the present embodiment, the impact rotary tool 1 is a portable electric tool. As shown in FIGS. 1 and 2, the impact rotary tool 1 includes a housing 2, a motor 3, a hammer 5, an anvil 6, an output shaft 7, a buffer member 8, a first bearing 91, an elastic member 100, and the like. Further, the impact rotary tool 1 includes 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 operation unit 13.

[0018] (2.1) Housing The housing 2 houses the hammer 5 and the anvil 6. Further, the housing 2 houses the motor 3, the transmission mechanism 4, the buffer 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 FIG. 1, the housing 2 has a housing portion 21, a grip portion 22, and a mounting portion 23.

[0019] The shape of the accommodating part 21 is a hollow cylindrical shape. As shown in FIG. 1, the accommodating part 21 includes a first accommodating part 211 and a second accommodating part 212. As shown in FIG. 2, the first accommodating part 211 is provided in front of the second accommodating part 212. The first accommodating part 211 is connected to the second accommodating part 212. The first accommodating part 211 accommodates at least a hammer 5 and an anvil 6. A first bearing 91 and a second bearing 92 are held in the first accommodating part 211. The first accommodating part 211 has a through hole 213 through which the output shaft 7 is inserted.

[0020] As shown in FIG. 1, the grip part 22 protrudes in one direction along a diameter direction of the accommodating part 21 from the outer peripheral surface of the accommodating part 21. More specifically, the grip part 22 protrudes from the second accommodating part 212. The above-mentioned one direction is along the vertical direction. The grip part 22 is formed in a hollow cylindrical shape that is long in the above-mentioned one direction. An operator can hold the grip part 22 and perform operations such as screwing. In addition, the grip part 22 is provided with an operation part 13 that receives the operation of the operator.

[0021] The internal space of the grip part 22 is connected to the internal space of the accommodating part 21. The accommodating part 21 is connected to the upper end in the longitudinal direction of the grip part 22, and the mounting part 23 is connected to the lower end.

[0022] A battery pack is detachably attached to the mounting part 23. The impact rotary tool 1 operates using the battery pack as a power source. That is, the battery pack is a power source that supplies a current for driving the motor 3. The battery pack is not a component of the impact rotary tool 1. However, the impact rotary tool 1 may be provided with a battery pack.

[0023] (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.

[0024] 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. The operation of motor 3 is controlled by feedback control.

[0025] The operator operates the control unit 13. Specifically, the operator pulls in 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 pulled in. The greater the amount the control unit 13 is pulled in, the higher the target value for the rotational speed of the motor 3 the control circuit 12 sets.

[0026] 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.

[0027] 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.

[0028] (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 power from the motor 3 to the hammer 5. This causes the hammer 5 to rotate.

[0029] 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.

[0030] 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. As a result, the hammer 5 rotates. That is, the hammer 5 rotates by obtaining power from the motor 3.

[0031] 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. This allows the hammer 5 to rotate relative to the return spring 43.

[0032] (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, a striking force is applied from the hammer 5 to the anvil 6, and this striking force is transmitted to the tip tool 110 via the output shaft 7.

[0033] 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 passes.

[0034] 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.

[0035] 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.

[0036] 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.

[0037] 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.

[0038] 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.

[0039] 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 formed therein for arranging two iron balls 731, which will be described later, so that they 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.

[0040] 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 forces from the two first contact portions 63 that cause the output shaft 7 to rotate.

[0041] 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.

[0042] 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. 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.

[0043] 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. As shown in Figure 2, the fitting portion 75 has a tunnel portion 77 formed at approximately the center along the thrust direction for fitting two steel balls 731. 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.

[0044] 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. In other words, 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.

[0045] The rotation direction of the anvil 6 coincides with the rotation direction of the hammer 5. As shown in Figure 6, the anvil 6 and the output shaft 7 are configured such that the protrusions and recesses consisting of two first contact portions 63 and the protrusions and recesses consisting of two second contact portions 72 interlock.

[0046] Here, the tip tool 110 is, for example, a screwdriver bit. The tip tool 110 is held on the output shaft 7 by being gripped by two steel balls 731 on the output shaft 7. The tip tool 110 engages with the screw (bolt or screw, etc.) to be worked on. By rotating the tip tool 110 while it is engaged with the screw, it becomes possible to tighten or loosen the screw. In this 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.

[0047] When the impact rotary tool 1 is not performing an impact operation, the hammer 5 and anvil 6 rotate at the same speed while the two hammer jaws 52 and the two anvil jaws 62 are in contact in the direction of rotation of the hammer 5. Therefore, at this time, the drive shaft 42, the hammer 5, the anvil 6, and the output shaft 7 rotate at the same speed.

[0048] The impact rotary tool 1 performs an impact operation when the torque condition related to the magnitude of the torque applied to the output shaft 7 (hereinafter referred to as load torque) is met. The impact operation is an operation in which a striking force is applied from the hammer 5 to the anvil 6. In this embodiment, the torque condition is that the load torque is equal to or greater than a predetermined value. That is, as the load torque increases, the component of the force generated between the hammer 5 and the anvil 6 that causes the hammer 5 to retract also increases. When the load torque is equal to or greater than a predetermined value, the hammer 5 retracts while compressing the return spring 43. As the hammer 5 retracts, the two hammer claws 52 of the hammer 5 move over the two anvil claws 62 of the anvil 6, and the hammer 5 rotates. After that, the hammer 5 moves forward by receiving the return force from the return spring 43. Then, when the drive shaft 42 has rotated approximately half a turn, the two hammer claws 52 of the hammer 5 collide with the sides 620 of the two anvil claws 62 of the anvil 6. Each 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. In other words, each time the drive shaft 42 rotates approximately half a turn, the hammer 5 applies a striking force to the anvil 6.

[0049] In this way, impact rotary tool 1 repeatedly collides with the hammer 5 and the anvil 6. The torque generated by these collisions allows the screw to be tightened more strongly than in the absence of collisions.

[0050] (2.5) Cushioning material As shown in Figures 2, 4, and 5, the cushioning 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.

[0051] The first part 81 is an elastic material such as rubber. The first part 81 undergoes elastic deformation in the thrust direction (forward-backward direction).

[0052] The second part 82 is formed from, for example, metal. The second part 82 is formed separately from the anvil 6 and the output shaft 7.

[0053] The elastic modulus of the second part 82 in the thrust direction is greater than that of the first part 81 in the thrust direction. The first part 81 and the second part 82 are aligned in the thrust direction, as shown in Figure 4.

[0054] 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, and 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.

[0055] 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.

[0056] 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, stress concentration in the anvil 6 and the output shaft 7 can be suppressed.

[0057] (2.6) First bearing and second bearing 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.

[0058] 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. This reduces the possibility of thrust loads concentrating near the contact points with the first bearing 91 on the anvil 6 and output shaft 7, thereby improving the durability of the anvil 6 and output shaft 7.

[0059] The external shape of the first bearing 91 is annular, as shown in Figure 4. 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.

[0060] 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.

[0061] 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.

[0062] 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.

[0063] 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.

[0064] 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.

[0065] 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.

[0066] The first stopper 93 has an annular shape. The first stopper 93 is located behind the first bearing 91. The first stopper 93 faces the first bearing 91.

[0067] 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.

[0068] When the first bearing 91 attempts to move in the forward or backward direction, its movement is restricted by contact with either the first stopper 93 or the second stopper 94. Similarly, when the second bearing 92 attempts to move backward, its movement is restricted by contact with the second stopper 94.

[0069] (2.7) Elastic members 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. However, 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. As shown in Figures 4 and 5, the elastic member 100 is cylindrical. The axis of the elastic member 100 is located on the rotation axis of the output shaft 7. As shown in Figure 2, the elastic member 100 is located near the bottom 76. 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.

[0070] 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.

[0071] (3) Advantages As described above, the impact rotary tool 1 according to this embodiment, 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 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.

[0072] This configuration allows for further suppression of noise generated by impact rotary tools.

[0073] (4) Variations (modified version) The following are examples of modifications. These modifications can be applied in appropriate combinations with the above embodiments.

[0074] (4.1) Variation 1 In the above embodiment, as shown in Figure 2, there is a space F1 between the elastic member 100 and the bottom 76, but the invention is not limited to this configuration. The space F1 between the elastic member 100 and the bottom 76 may be completely filled with the elastic member 100. By completely filling the space F1 with the elastic member 100, 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 less than when the space F1 is formed, but since it absorbs the vibration of the tip tool 110, it can suppress noise even more than the conventional invention. Therefore, 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. In other words, the shape of the elastic member 100 may be polygonal prism. Alternatively, the shape of the elastic member 100 may be conical or pyramidal. In this case, 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 two 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 parts 81.

[0082] The cushioning member 8 may include a plurality of second parts 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 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 fitting portion (75) into which the tip tool (110) is fitted. The elastic member (100) is positioned between the tip tool (110) and the bottom portion (76) of the fitting 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 axis of rotation of the output shaft (7).

[0095] This configuration allows for the even distribution of impact noise caused by the collision between the anvil (6) and the output shaft (7). In other words, it further reduces 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, allowing for longer use, and further suppressing the collision noise caused by the anvil (6) and output shaft (7) colliding. In other words, 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 forming the elastic member (100) is 50° or more and 95° or less, as in the first to third embodiments.

[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. [Explanation of symbols]

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

Claims

1. A hammer that rotates using power from a motor, An anvil that rotates upon receiving a striking force from the hammer in the direction of the hammer's rotation, An output shaft that receives a force from the anvil in the direction of the anvil's rotation and rotates together with the anvil, A housing for housing the hammer and the anvil, A bearing held in the housing and rotatably supporting the output shaft, The output shaft comprises an elastic member that elastically deforms in the thrust direction along the rotation axis of the output shaft, The output shaft has a fitting portion into which a cutting tool is fitted, The elastic member is positioned between the tip tool and the bottom of the fitting portion. Impact rotary tool.

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

3. The elastic member is made of urethane. The impact rotary tool according to claim 1.

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

Images