Impact rotary tools

Abstract

This invention provides an impact rotary tool that can reduce noise generated from the housing due to impact vibrations. [Solution] The impact rotary tool 1 comprises a drive shaft 6, a hammer 8, and an anvil 9. The drive shaft 6 rotates by obtaining power from a motor. The hammer 8 rotates in accordance with the rotation of the drive shaft 6. The anvil 9 rotates by receiving an impact force from the hammer 8. The elastic member 11 is elastically deformable in the thrust direction DR1 along the rotation axis AX1 of the drive shaft 6. The drive shaft 6 has a first opposing portion 6A facing the motor 3 in the thrust direction DR1, and a second opposing portion 6B facing the anvil 9 in the thrust direction DR1. The elastic member 11 is disposed on at least one of the first opposing portion 6A and the second opposing portion 6B.

Description

Technical Field

[0001] The present disclosure relates to an impact rotary tool. More specifically, the present disclosure relates to an impact rotary tool including a hammer and an anvil.

Background Art

[0002] Patent Document 1 discloses a rotary impact tool. This rotary impact tool includes a hammer rotated by a motor and an anvil struck by the hammer. The anvil is divided into two components: a rotary impact member that receives impact energy from the hammer, and a tip tool mounting member that receives the force in the rotational direction of the rotary impact member to tighten and loosen a screw. In this rotary impact tool, a buffer material is interposed in the axial gap between the rotary impact member and the tip tool mounting member to reduce the noise generated from the clamped member by the axial force generated during impact.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the rotary impact tool of Patent Document 1, it was not possible to reduce the noise generated from the case (housing) of the rotary impact tool by the axial force generated during impact.

[0005] An object of the present disclosure is to provide an impact rotary tool capable of reducing the noise generated from the housing due to the vibration of impact.

Means for Solving the Problems

[0006] An impact rotary tool according to one aspect of the present disclosure comprises a drive shaft, a hammer, an anvil, an output shaft, a housing, and an elastic member. The drive shaft rotates powered by a motor. The hammer rotates in accordance with the rotation of the drive shaft. The anvil rotates upon receiving a striking force from the hammer in the direction of the hammer's rotation. The output shaft is capable of mounting a tool tip and rotates in accordance with the rotation of the anvil. The housing accommodates the drive shaft, the hammer, and the anvil. The elastic member is elastically deformable in the thrust direction along the rotation axis of the drive shaft. The drive shaft has a first opposing portion facing the motor in the thrust direction and a second opposing portion facing the anvil in the thrust direction. The elastic member is disposed on at least one of the first opposing portion and the second opposing portion of the drive shaft. [Effects of the Invention]

[0007] According to this disclosure, it is possible to provide an impact rotary tool that can reduce noise generated from the housing due to impact vibrations. [Brief explanation of the drawing]

[0008] [Figure 1] Figure 1 is a cross-sectional view of a key part of an impact rotary tool according to one embodiment of the present disclosure. [Figure 2] Figure 2 is a side view of the same impact rotary tool. [Figure 3] Figure 3 is a side view of the drive shaft of the impact rotary tool described above. [Figure 4] Figure 4 is a perspective view of the main components of the impact rotary tool shown above. [Modes for carrying out the invention]

[0009] The impact rotary tool according to the embodiment will be described in detail below with reference to the drawings. However, the figures described in the following embodiments are schematic diagrams, and the dimensional ratios of the size of each component do not necessarily reflect the actual dimensional ratios. Furthermore, the configuration described in the following embodiments is merely one example of the disclosure. The disclosure is not limited to the following embodiments, and various modifications are possible depending on the design, etc., as long as the effects of the disclosure can be achieved.

[0010] (Embodiment) (1) Overview As shown in Figures 1 to 4, the impact rotary tool 1 of this embodiment comprises a drive shaft 6, a hammer 8, an anvil 9, an output shaft 10, a housing 2, and an elastic member 11.

[0011] The drive shaft 6 rotates by obtaining power from the motor 3.

[0012] Hammer 8 rotates in accordance with the rotation of drive shaft 6.

[0013] Anvil 9 rotates as it receives a striking force from Hammer 8 in the direction of Hammer 8's rotation.

[0014] The output shaft 10 can be fitted with the tip tool T1 and rotates in accordance with the rotation of the anvil 9.

[0015] Housing 2 houses the drive shaft 6, the hammer 8, and the anvil 9.

[0016] The elastic member 11 is elastically deformable in the thrust direction DR1 along the rotation axis AX1 of the drive shaft 6.

[0017] The drive shaft 6 has a first opposing portion 6A that faces the motor 3 in the thrust direction DR1, and a second opposing portion 6B that faces the anvil 9 in the thrust direction DR1.

[0018] An elastic member 11 is positioned on at least one of the first opposing portion 6A and the second opposing portion 6B of the drive shaft 6.

[0019] Here, the rotation axis AX1 of the drive shaft 6 is the center of rotation when the drive shaft 6 rotates, and the drive shaft 6 rotates about the rotation axis AX1. Attaching the tip tool T1 to the output shaft 10 means that the tip tool T1 may be directly attached to the output shaft 10, or the tip tool T1 may be attached to the output shaft 10 via another member. Note that in FIG. 2, the illustration of the tip tool T1 is omitted, and the tip tool T1 is shown by a two-dot chain line.

[0020] Also, although the output shaft 10 rotates in response to the rotation of the anvil 9, the anvil 9 and the output shaft 10 may be configured as separate parts, or the anvil 9 and the output shaft 10 may be configured as one part.

[0021] Also, although the first opposing portion 6A of the drive shaft 6 faces the motor 3 in the thrust direction DR1, the first opposing portion 6A and the motor 3 do not have to directly face each other, and one or more members may be interposed between the first opposing portion 6A and the motor 3. Further, although the second opposing portion 6B of the drive shaft 6 faces the anvil 9 in the thrust direction DR1, one or more members may be interposed between the second opposing portion 6B and the anvil 9. Note that in the thrust direction DR1, the first opposing portion 6A is closer to the motor 3 than the second opposing portion 6B, and the second opposing portion 6B is closer to the anvil 9 than the first opposing portion 6A.

[0022] When the elastic member 11 is not disposed on the first opposing portion 6A and the second opposing portion 6B of the drive shaft 6, if the hammer 8 strikes the anvil 9 and vibration in the thrust direction DR1 is applied to the drive shaft 6, and the drive shaft 6 contacts other members, noise may occur. In the impact rotary tool 1 of the present embodiment, when vibration in the thrust direction DR1 is applied to the drive shaft 6, the noise generated by the elastic deformation of the elastic member 11 disposed between at least one of the first opposing portion 6A and the second opposing portion 6B and another part can be reduced. Therefore, according to the present embodiment, it is possible to realize the impact rotary tool 1 capable of reducing the noise generated from the housing 2 due to the vibration of the impact.

[0023] In the embodiments described below, elastic members 11 are arranged on both the first opposing portion 6A and the second opposing portion 6B of the drive shaft 6. In the following, the elastic member 11 arranged on the first opposing portion 6A may be referred to as the first elastic member 11A, and the elastic member 11 arranged on the second opposing portion 6B may be referred to as the second elastic member 11B.

[0024] (2) Details The impact rotary tool 1 according to this embodiment will be described in detail below with reference to Figures 1 to 4, etc. In the following description, the X-axis direction (the direction in which the output shaft 10 protrudes from the housing 2 of the impact rotary tool 1) is defined as the front-to-back direction, the Y-axis direction as the left-to-right direction, and the Z-axis direction as the up-and-down direction in Figure 1, etc. Furthermore, the positive direction in the X-axis direction is defined as the front, the positive direction in the Y-axis direction as the right side, and the positive direction in the Z-axis direction as the top. However, these directions are merely examples and are not intended to limit the direction in which the impact rotary tool 1 can be used. Also, the arrows indicating each direction in the drawings are for illustrative purposes only and do not represent actual objects.

[0025] (2.1) Configuration The impact rotary tool 1 of this embodiment is a portable power tool. The impact rotary tool 1 is used, for example, to perform tasks such as tightening or loosening fastening members such as bolts or screws.

[0026] As described above, the impact rotary tool 1 of this embodiment comprises a drive shaft 6, a hammer 8, an anvil 9, an output shaft 10, a housing 2, and an elastic member 11. The impact rotary tool 1 also further comprises a motor 3, a control circuit 4, and a reduction mechanism 5. In this mechanism, the reduction mechanism 5 reduces the rotation of the motor rotation shaft 31 (see Figure 1) of the motor 3 and transmits it to the drive shaft 6. Furthermore, the hammer 8 and anvil 9, etc., rotate the hammer 8 in accordance with the rotation of the drive shaft 6, causing the hammer 8 to strike the anvil 9, thereby forming an impact mechanism 7 that applies impact force to the output shaft 10.

[0027] (2.1.1) Housing The housing 2 accommodates the motor 3, the reduction mechanism 5, the drive shaft 6, the impact mechanism 7, the output shaft 10, and the elastic member 11 (see Figures 1 and 2).

[0028] Housing 2 is composed of a right case 21 (see Figure 1), a left case 22 (see Figure 2), and a front case 23 (see Figures 1 and 2). When the right case 21, left case 22, and front case 23 are combined, housing 2 has a storage section 2A, a grip section 2B, and a mounting section 2C (see Figure 2).

[0029] The housing section 2A has a hollow cylindrical shape. The housing section 2A houses the motor 3, reduction mechanism 5, drive shaft 6, impact mechanism 7, output shaft 10, etc. The motor 3 is located at the rear of the housing section 2A. The reduction mechanism 5 and impact mechanism 7 are arranged in a front-to-back direction in front of the motor 3. The output shaft 10 is located in front of the anvil 9, and the tip portion (front end) of the output shaft 10 protrudes to the outside of the housing 2 through an opening 25 provided on the front surface of the front case 23.

[0030] The grip portion 2B protrudes from the outer circumferential surface of the housing portion 2A in one direction along the radial direction of the housing portion 2A. This one direction is, for example, along the vertical direction (see Figure 2). The grip portion 2B is formed in a hollow cylindrical shape with the above-mentioned one direction as the longitudinal direction. The worker can grasp the grip portion 2B and perform tasks such as tightening screws. An operating portion 24 that receives input from the worker is provided on the grip portion 2B.

[0031] The internal space of the grip portion 2B is connected to the internal space of the housing portion 2A. The first end of the grip portion 2B in the longitudinal direction is connected to the housing portion 2A, and the second end of the grip portion 2B in the longitudinal direction is connected to the mounting portion 2C.

[0032] The battery pack BP1 is detachably attached to the mounting section 2C. Note that the battery pack BP1 is not shown in Figure 2, and is represented by a dashed line. The impact rotary tool 1 operates using the battery pack BP1 as its power source. That is, the battery pack BP1 is the power source that supplies the current to drive the motor 3. The battery pack BP1 is not a component of the impact rotary tool 1. However, the impact rotary tool 1 may be equipped with the battery pack BP1.

[0033] (2.1.2) Motor Motor 3 is housed in the housing section 2A of the housing 2. Motor 3 is, for example, a brushless motor.

[0034] The torque and rotational speed of motor 3 are controlled, for example, by a control circuit 4 (see Figure 2). The control circuit 4 is housed, for example, in the grip section 2B.

[0035] When an operator uses the impact rotary tool 1, the operator operates the control unit 24 located on the grip section 2B. For example, the control unit 24 is a so-called trigger switch, and the operator pulls the control unit 24 in. The control circuit 4 determines a target value for the rotational speed of the motor 3 according to the amount the control unit 24 is pulled in. The greater the amount the control unit 24 is pulled in, the higher the target value for the rotational speed of the motor 3 the control circuit 4 sets. The housing 2 contains a drive circuit that drives the motor 3, and the drive circuit rotates the motor 3 at a rotational speed corresponding to the control signal input from the control circuit 4.

[0036] (2.1.3) Reduction mechanism The reduction mechanism 5 transmits the rotation of the motor shaft 31 of the motor 3 to the drive shaft 6. The reduction mechanism 5 converts the rotational speed and torque of the motor shaft 31 of the motor 3 into a predetermined rotational speed and predetermined torque and transmits them to the drive shaft 6.

[0037] The reduction mechanism 5 is a planetary gear mechanism that includes, for example, a sun gear 51 connected to the motor rotation shaft 31 of the motor 3, a plurality of planetary gears 52 arranged around the sun gear 51, and an internal gear (not shown) arranged to surround the plurality of planetary gears 52. The planetary gear mechanism is, for example, a reduction device that reduces the rotation of the motor rotation shaft 31 of the motor 3 and transmits it to the drive shaft 6.

[0038] (2.1.4) Drive shaft The drive shaft 6 is formed from, for example, a metal material.

[0039] The drive shaft 6 has a cylindrical shaft body 61 with the front-rear direction as its central axis (see Figures 1 and 3).

[0040] A support portion 62 is provided at the rear of the shaft 61 to support a plurality of planetary gears 52 in a rotatable state. The support portion 62 is formed in a cylindrical shape with a larger diameter than the shaft 61. Multiple openings are provided on the circumferential surface of the support portion 62 to expose each of the plurality of planetary gears 52 supported by the support portion 62. In addition, a cylindrical portion 64 is provided at the rear of the support portion 62 into which the sun gear 51 attached to the motor rotation shaft 31 of the motor 3 is inserted.

[0041] Here, the multiple planetary gears 52 supported by the support portion 62 mesh with the sun gear 51 inserted into the cylindrical portion 64, and with the internal gears arranged around the multiple planetary gears 52. When the motor rotation shaft 31 of the motor 3 rotates, and the sun gear 51 rotates together with the motor rotation shaft 31, the multiple planetary gears 52 rotate on their own axes and revolve around the sun gear 51, causing the shaft body 61 to rotate together with the support portion 62 that supports the multiple planetary gears 52. As a result, the rotation of the motor rotation shaft 31 of the motor 3 is transmitted to the drive shaft 6 via the reduction mechanism 5.

[0042] Furthermore, a cylindrical projection 63, which has a smaller diameter than the shaft body 61, is integrally provided at the front end of the drive shaft 6.

[0043] Furthermore, two grooves 65 are provided on the circumferential surface of the drive shaft 6. The two grooves 65 are formed in a spiral shape and are connected. A portion of a steel ball (not shown) is inserted into each of the two grooves 65.

[0044] In this configuration, the rear surface of the support portion 62 of the drive shaft 6 becomes the first opposing portion 6A facing the motor 3. A cylindrical portion 64 protrudes from the center of the rear surface of the first opposing portion 6A toward the rear, and the first elastic member 11A is attached to the cylindrical portion 64. The first elastic member 11A is, for example, an O-ring, and by fitting the first elastic member 11A around the cylindrical portion 64, the first elastic member 11A is positioned on the first opposing portion 6A.

[0045] Furthermore, the front surface of the drive shaft 6 (more specifically, the front surface of the shaft body 61) becomes a second opposing portion 6B that faces the anvil 9. A projection 63 protrudes forward from the center of the front surface of the drive shaft 6, and a second elastic member 11B is attached to the projection 63. The second elastic member 11B is, for example, an O-ring, and by fitting the second elastic member 11B around the projection 63, the second elastic member 11B is positioned on the second opposing portion 6B.

[0046] (2.1.5) Impact Mechanism The impact mechanism 7 applies striking force to the anvil 9 by having a hammer 8, rotated by the drive shaft 6, strike the anvil 9.

[0047] The impact mechanism 7 comprises a hammer 8, an anvil 9, a retaining cylinder 83, and a return spring 84 (see Figures 1 and 4).

[0048] The hammer 8 is formed of, for example, a metal material. The hammer 8 includes a hammer body 81 and two hammer claws 82. The shape of the hammer body 81 is, for example, cylindrical. The hammer body 81 is provided with a through hole 85 into which the drive shaft 6 is inserted. The center of the through hole 85 coincides with the rotation axis AX1 of the drive shaft 6.

[0049] The two hammer claws 82 protrude forward from the front surface of the hammer body 81. When viewed from the front, each of the two hammer claws 82 is shaped like a sector with respect to the rotation center of the hammer body 81. The two hammer claws 82 are positioned symmetrically with respect to the center of the through hole 85 (the rotation axis AX1 of the drive shaft 6).

[0050] The hammer body 81 has two grooves 86 on the inner circumferential surface of the through hole 85. As described above, the drive shaft 6 also has two grooves 65 on its outer circumferential surface, and steel balls are sandwiched between the two grooves 86 of the hammer body 81 and the two grooves 65 of the drive shaft 6. Here, the grooves 86 of the through hole 85, the grooves 65 of the drive shaft 6, and the steel balls constitute a cam mechanism. As the steel balls move within the grooves 86 of the through hole 85 and the grooves 65 of the drive shaft 6, the hammer 8 can move in the axial direction (forward and backward direction) of the drive shaft 6 and can also rotate relative to the drive shaft 6. As the hammer 8 moves forward or backward along the axial direction of the drive shaft 6, the hammer 8 rotates relative to the drive shaft 6.

[0051] The retaining cylinder 83 is formed in a cylindrical shape, and the hammer 8 is positioned inside the retaining cylinder 83. The hammer 8 is positioned in the retaining cylinder 83 so as to be able to move forward and backward along the rotation axis AX1 of the drive shaft 6. A return spring 84, which is a conical coil spring, is positioned between the rear surface of the hammer 8 and the inner flange provided at the rear of the retaining cylinder 83. The return spring 84 applies a forward pushing force to the hammer 8. A ring formed in the shape of an annular ring from a metal material is positioned between the return spring 84 and the hammer 8, and the hammer 8 is positioned so as to be rotatable relative to the return spring 84.

[0052] The anvil 9 faces the hammer body 81 in the front-rear direction. As shown in Figures 1 and 4, the anvil 9 is formed of, for example, a metal material. The anvil 9 includes an anvil body 90 and two anvil claws 91. The anvil body 90 is cylindrical in shape. The two anvil claws 91 project from the anvil body 90 in opposite directions along the radial direction of the anvil body 90.

[0053] Multiple engagement recesses 92 are provided on the front surface of the anvil body 90, arranged at equal intervals in the circumferential direction of the anvil body 90. Additionally, a recess 94 into which an adjustment member 16 is inserted is provided on the front surface of the anvil body 90. The adjustment member 16 is made of, for example, a metal material. In the assembled state, the adjustment member 16 inserted into the recess 94 of the anvil body 90 and the elastic body 15 inserted into the recess 104 of the output shaft 10 (described later) are aligned in the thrust direction DR1. The elastic modulus of the adjustment member 16 in the thrust direction DR1 is greater than the elastic modulus of the elastic body 15 in the thrust direction DR1. The adjustment member 16 is used to adjust the size of the gap between the elastic body 15, located in the recess 104 of the output shaft 10, and the anvil 9. Since the elastic body 15 and the adjustment member 16 are positioned between the anvil 9 and the output shaft 10, vibrations transmitted from the anvil 9 to the output shaft 10 can be reduced.

[0054] Furthermore, the rear surface of the anvil body 90 is provided with a round hole 93 into which the projection 63 at the tip of the drive shaft 6 is inserted.

[0055] (2.1.6) Output shaft The output shaft 10 is formed in a cylindrical shape, for example, from a metal material (see Figures 1 and 4).

[0056] A rectangular prism-shaped mounting portion 103 is provided at the front end of the output shaft 10. A tip tool T1 (see Figure 2) can be attached to the mounting portion 103. A holder for attaching and detaching the tip tool T1 may be attached to the mounting portion 103, or the tip tool T1 may be attached to the mounting portion 103 via the holder. Alternatively, the tip tool T1 may be directly attached to the mounting portion 103.

[0057] A connecting portion 101 for connecting to an anvil 9 is provided at the rear end of the output shaft 10. The connecting portion 101 is formed in a cylindrical shape. The diameter of the connecting portion 101 is larger than the diameter of the output shaft 10 in front of the connecting portion 101.

[0058] On the rear surface of the connecting portion 101, a plurality of engaging protrusions 102 projecting backward are provided at equal intervals along the outer circumferential surface of the connecting portion 101. With the plurality of engaging protrusions 102 inserted into the plurality of engaging recesses 92 of the anvil 9, the anvil 9 and the output shaft 10 are connected, and the anvil 9 and the output shaft 10 rotate as a single unit.

[0059] Here, the rear surface of the connecting portion 101 is provided with a recess 104 for inserting an elastic body 15 such as rubber, at a position opposite to the recess 94 of the anvil 9.

[0060] (2.1.7) Elastic members In this embodiment, elastic members 11 (first elastic member 11A and second elastic member 11B) are arranged on the first opposing portion 6A and the second opposing portion 6B of the drive shaft 6, respectively.

[0061] The elastic member 11 is, for example, an O-ring. The elastic member 11 is made of, for example, urethane. The elastic member 11 may also 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.

[0062] In this embodiment, the elastic member 11 includes a first elastic member 11A disposed on the first opposing portion 6A and a second elastic member 11B disposed on the second opposing portion 6B.

[0063] More specifically, the first elastic member 11A is positioned between the first opposing portion 6A of the drive shaft 6 and the bearing 13 that rotatably supports the cylindrical portion 64 of the drive shaft 6. The second elastic member 11B is positioned between the second opposing portion 6B of the drive shaft 6 and the annular metal plate 14 positioned between the second opposing portion 6B and the hammer 8.

[0064] If elastic members 11 are not positioned on the first opposing portion 6A and the second opposing portion 6B of the drive shaft 6, the hammer 8 striking the anvil 9 will apply a thrust vibration DR1 to the drive shaft 6, and when the drive shaft 6 comes into contact with the bearing 13 or the metal plate 14, noise may be generated. In the impact rotary tool 1 of this embodiment, when a thrust vibration DR1 is applied to the drive shaft 6, the first elastic member 11A positioned between the first opposing portion 6A and the bearing 13, or the second elastic member 11B positioned between the second opposing portion 6B and the metal plate 14, undergoes elastic deformation, thereby suppressing the generation of noise.

[0065] Here, with the first elastic member 11A and the second elastic member 11B placed on both the first opposing portion 6A and the second opposing portion 6B of the drive shaft 6, noise was measured at a distance of 1m from the housing 2, and the noise was reduced by 3.7dB compared to when the elastic member 11 was not present. Furthermore, with the first elastic member 11A placed only on the first opposing portion 6A of the drive shaft 6, noise was measured at a distance of 1m from the housing 2, and the noise was reduced by 4.3dB compared to when the elastic member 11 was not present. Furthermore, with the second elastic member 11B placed only on the second opposing portion 6B of the drive shaft 6, noise was measured at a distance of 1m from the housing 2, and the noise was reduced by 4.3dB compared to when the elastic member 11 was not present. Thus, in the impact rotary tool 1 of this embodiment, noise generated from the housing 2 could be reduced by placing the elastic member 11 on one or both of the first opposing portion 6A and the second opposing portion 6B.

[0066] Furthermore, the noise reduction effect is greater when the elastic member 11 is placed on only one of the first opposing part 6A and the second opposing part 6B compared to when the elastic member 11 is placed on both the first opposing part 6A and the second opposing part 6B. When the elastic member 11 is placed on both the first opposing part 6A and the second opposing part 6B, the gap between the drive shaft 6 and the bearing 13, and the gap between the drive shaft 6 and the metal plate 14 are smaller compared to when the elastic member 11 is placed on only one of the first opposing part 6A and the second opposing part 6B. Therefore, vibrations applied to the drive shaft 6 are more easily transmitted to the housing 2. On the other hand, when the elastic member 11 is placed on only one of the first opposing part 6A and the second opposing part 6B, the gap between the drive shaft 6 and the bearing 13, or between the drive shaft 6 and the metal plate 14, becomes larger, making it more difficult for vibrations applied to the drive shaft 6 to be transmitted to the housing 2. Therefore, noise generation can be further suppressed.

[0067] (2.2) Operation Instructions The operation of the impact rotary tool 1 of this embodiment will be described below.

[0068] The operation of the impact rotary tool 1 will be explained using the example of a user performing a tightening operation using the impact rotary tool 1 to fasten fastening parts (e.g., bolts) to an object. When the operator pulls in the operating section 24 of the impact rotary tool 1, the control circuit 4 determines a target value for the rotational speed of the motor 3 according to the amount the operating section 24 is pulled in, and outputs a control signal to the drive circuit. The drive circuit rotates the motor shaft 31 of the motor 3 by controlling the power supplied to the motor 3 according to the control signal from the control circuit 4.

[0069] When the motor shaft 31 of motor 3 rotates, the reduction mechanism 5 reduces the rotation of the motor shaft 31 and transmits it to the drive shaft 6, causing the drive shaft 6 to rotate.

[0070] Here, if the torque condition regarding the magnitude of the torque applied to the output shaft 10 (hereinafter referred to as load torque) is not met, the hammer 8 and anvil 9 will rotate at the same speed while the two hammer pawls 82 and the two anvil pawls 91 are in contact in the direction of rotation of the hammer 8. The torque condition is, for example, that the load torque is greater than or equal to a predetermined value. That is, if the load torque is less than the predetermined value, the drive shaft 6, hammer 8, anvil 9, and output shaft 10 will rotate at the same speed.

[0071] As the fastening component is screwed into the object, the load torque increases, and when the torque condition related to the magnitude of the load torque is met, the impact mechanism 7 performs an impact operation. The impact operation is the operation of applying a striking force from the hammer 8 to the anvil 9. As the load torque increases, the component of the force generated between the hammer 8 and the anvil 9 that moves the hammer 8 backward also increases. When the load torque exceeds a predetermined value, the hammer 8 moves backward while compressing the return spring 84. As the hammer 8 moves backward, the two hammer claws 82 of the hammer 8 move over the two anvil claws 91 of the anvil 9, and the hammer 8 rotates. After that, the hammer 8 moves forward, receiving the return force from the return spring 84. Then, when the drive shaft 6 has rotated approximately half a turn, the two hammer claws 82 of the hammer 8 collide with the sides of the two anvil claws 91 of the anvil 9. Each time the drive shaft 6 rotates approximately half a turn, the two hammer claws 82 of the hammer 8 collide with the two anvil claws 91 of the anvil 9. In other words, each time the drive shaft 6 rotates approximately half a turn, the hammer 8 applies a striking force to the anvil 9.

[0072] Thus, in the impact rotary tool 1, collisions between the hammer 8 and the anvil 9 occur repeatedly. The torque resulting from these collisions allows for stronger tightening of the fastening components compared to when there are no collisions.

[0073] When the impact rotary tool 1 performs an impact operation, the hammer jaws 82 of the hammer 8 strike the anvil jaws 91 of the anvil 9, which may cause vibration in the thrust direction DR1 to be applied to the drive shaft 6. When the drive shaft 6 vibrates in the thrust direction DR1, the vibration of the drive shaft 6 is suppressed by the elastic deformation of one or both of the first elastic member 11A, which is positioned between the first opposing part 6A and the bearing 13, and the second elastic member 11B, which is positioned between the second opposing part 6B and the metal plate 14. As a result, the vibration of the drive shaft 6 is transmitted to the housing 2, which reduces the noise transmitted from the housing 2 to the outside, and thus provides an impact rotary tool 1 that can reduce the noise generated from the housing 2 by the vibration of the impact.

[0074] (3) Variant The above embodiments are merely one of many embodiments of this disclosure. The above embodiments can be modified in various ways depending on the design, etc., as long as they achieve the objectives of this disclosure.

[0075] The number of hammer claws 82 and anvil claws 91 is not limited to two, but may be one or three or more.

[0076] An elastic body 15 and an adjustment member 16 are positioned between the anvil 9 and the output shaft 10, but the elastic body 15 and the adjustment member 16 are optional. Also, although the anvil 9 and the output shaft 10 are composed of two parts, the anvil 9 and the output shaft 10 may be composed as a single part.

[0077] The configuration of the impact mechanism 7 is not limited to the configuration described in the above embodiment and can be modified as appropriate.

[0078] In the above embodiment, the reduction mechanism 5 includes a planetary gear mechanism, but the reduction mechanism 5 is not limited to including a planetary gear mechanism, and the configuration of the reduction mechanism 5 can be changed as appropriate. Furthermore, in the impact rotary tool 1, the reduction mechanism 5 is not an essential component and can be omitted as appropriate.

[0079] The first elastic member 11A is positioned between the first opposing portion 6A of the drive shaft 6 and the bearing 13, but it may also be positioned between a component other than the bearing 13 and the first opposing portion 6A, or between a part of the housing 2 and the first opposing portion 6A.

[0080] The second elastic member 11B is positioned between the second opposing portion 6B of the drive shaft 6 and the metal plate 14, but it may also be positioned between a component other than the metal plate 14 and the second opposing portion 6B, or between a part of the housing 2 and the second opposing portion 6B.

[0081] In the above embodiment, the elastic member 11 is made of urethane, but it may also be made of an elastic material other than urethane (for example, nitrile rubber, butyl rubber, etc.). In the above embodiment, the hardness of the urethane forming the elastic member 11 is 50° or more and 95° or less, but the hardness of the urethane can be changed as appropriate as long as a noise reduction effect is obtained. Furthermore, if the elastic material forming the elastic member 11 is other than urethane, the hardness of the elastic material can be changed as appropriate depending on the type of elastic material forming the elastic member 11.

[0082] The elastic member 11 only needs to be formed in an annular shape from an elastic material. In this embodiment, the elastic member 11 is an O-ring with a circular cross-section, but it may also be a packing with a rectangular cross-section, or a V-packing with a V-shaped cross-section, etc.

[0083] (summary) Based on the embodiments described above, the following aspects are disclosed.

[0084] The impact rotary tool (1) in the first embodiment comprises a drive shaft (6), a hammer (8), an anvil (9), an output shaft (10), a housing (2), and an elastic member (11). The drive shaft (6) rotates powered by a motor (3). The hammer (8) rotates in accordance with the rotation of the drive shaft (6). The anvil (9) rotates by receiving an impact force from the hammer (8) in the direction of the hammer's rotation. The output shaft (10) can accommodate a cutting tool (T1) and rotates in accordance with the rotation of the anvil (9). The housing (2) houses the drive shaft (6), the hammer (8), and the anvil (9). The elastic member (11) is elastically deformable in the thrust direction (DR1) along the rotation axis (AX1) of the drive shaft (6). The drive shaft (6) has a first opposing portion (6A) facing the motor (3) in the thrust direction (DR1) and a second opposing portion (6B) facing the anvil (9) in the thrust direction (DR1). An elastic member (11) is disposed on at least one of the first opposing portion (6A) and the second opposing portion (6B) of the drive shaft (6).

[0085] In this case, if elastic members (11) are not positioned on the first opposing portion (6A) and the second opposing portion (6B) of the drive shaft (6), when the hammer (8) strikes the anvil (9), thrust vibration (DR1) is applied to the drive shaft (6), and when the drive shaft (6) comes into contact with other members, noise may be generated. According to this embodiment, when thrust vibration (DR1) is applied to the drive shaft (6), the noise generated by the elastic deformation of the elastic member (11) positioned between at least one of the first opposing portion (6A) and the second opposing portion (6B) and other parts can be reduced. Therefore, an impact rotary tool (1) capable of reducing noise generated from the housing (2) due to impact vibration can be realized.

[0086] In the second embodiment of the impact rotary tool (1), elastic members (11) are arranged on both the first opposing portion (6A) and the second opposing portion (6B) of the drive shaft (6), as in the first embodiment.

[0087] According to this embodiment, similar to the first embodiment, an impact rotary tool (1) can be realized that can reduce the noise generated from the housing (2) by the vibration of impact.

[0088] In the third embodiment of the impact rotary tool (1), the elastic member (11) is an O-ring, in the first or second embodiment.

[0089] According to this embodiment, an impact rotary tool (1) capable of reducing noise can be realized using readily available O-rings.

[0090] In the fourth embodiment of the impact rotary tool (1), in any of the first to third embodiments, the elastic member (11) is made of urethane.

[0091] With this configuration, since urethane is an elastic material with excellent wear resistance, the wear resistance of the elastic member (11) can be improved.

[0092] In the fifth embodiment of the impact rotary tool (1), the hardness of the urethane is 50° or more and 95° or less, as in the fourth embodiment.

[0093] With this configuration, by setting the hardness of the urethane forming the elastic member (11) to 50° or more and 95° or less, the noise generated by the drive shaft (6) colliding with other parts can be further reduced.

[0094] The configurations relating to the second to fifth aspects are not essential to the impact rotary tool (1) and can be omitted as appropriate. [Explanation of Symbols]

[0095] 1. Impact rotary tool 2 Housing 3 motors 6 drive shafts 6A 1st opposing part 6B 2nd opposing part 8 Hammer 9 Anvil 10 Output shaft 11 Elastic members AX1 Rotation axis DR1 Thrust direction T1 tip tool

Claims

1. A drive shaft that rotates by obtaining power from a motor, A hammer that rotates in accordance with the rotation of the aforementioned drive shaft, An anvil that rotates upon receiving a striking force from the hammer in the direction of the hammer's rotation, An output shaft to which a cutting tool can be attached and which rotates in accordance with the rotation of the anvil, A housing that accommodates the drive shaft, the hammer, and the anvil, The drive shaft comprises an elastic member that is elastically deformable in the thrust direction along the rotation axis of the drive shaft, The drive shaft has a first opposing portion facing the motor in the thrust direction and a second opposing portion facing the anvil in the thrust direction. The elastic member is arranged on at least one of the first opposing portion and the second opposing portion of the drive shaft. Impact rotary tool.

2. The elastic members are arranged on both the first opposing portion and the second opposing portion of the drive shaft. The impact rotary tool according to claim 1.

3. The elastic member is an O-ring. The impact rotary tool according to claim 1.

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

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

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