JP2014069292A - Impact tool - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an impact tool in which vibration reduction efficiency of a vibration reduction mechanism can be enhanced as much as possible.SOLUTION: An impact tool comprises: a tool body 13 for supporting a tip tool; an action member 41 which is so provided in the tool body 13 as to be able to perform reciprocating-motion and generates a striking force to be transmitted to the tip tool 13; a motor 11 having an output shaft 21; a motion conversion mechanism 45 for converting rotational motion of the output shaft 21 into reciprocating-motion and transmitting the reciprocating-motion to the action member 41; a bearing 24 for supporting the output shaft 21; and a vibration reduction mechanism 47 for reducing vibration of the tool body 13. The vibration reduction mechanism 47 includes: a support member 48 which is so attached to the tool body 13 as to be able to swing in a direction along a center line of the motion member 41; a weight 49 attached to the support member 48; and struck parts 63, 64 which abut to the tool body 13 through an elastic body 61 when the weight 49 reaches a predetermined vibration amplitude.

Description

  The present invention relates to a striking tool capable of applying a striking force to a tip tool, such as a hammer drill or a hammer driver.

  Conventionally, hitting tools such as hammer drills and hammer drivers can apply hitting force to the tip tool. Such an impact tool includes a tip tool that is rotated by an electric motor provided in a casing that forms an outer shell of the tool body, an impact tool that is linearly reciprocated in the casing, and an electric motor. It has a motion conversion mechanism that converts the rotational motion into the reciprocating motion of the piston, and a striker that transmits the striking force generated by the reciprocating motion of the piston to the tip tool. In this impact tool, the tool body vibrates due to the reciprocating motion of the piston, the operation of striking the tip tool with the impact element, and the like. Therefore, a technique capable of reducing the vibration of the tool main body in the impact tool has been proposed, and an example thereof is described in Patent Document 1.

  The impact tool described in Patent Document 1 is supported by a casing that forms the outer shell of the tool body as a vibration reduction mechanism, and a shaft portion that is oriented perpendicularly to the direction of reciprocation of the tip tool, and the shaft portion. A weight that is spaced apart, a support part that supports the weight part so as to be swingable about the shaft part, and a biasing means that biases the weight back to a predetermined position with respect to the casing in the swinging direction. And have.

JP 2008-272897 A

  However, in the impact tool described in Patent Document 1, since the point of action for transmitting the excitation force of the weight of the vibration reduction mechanism to the tool body is away from the impact axis, the vibration of the tool body generated on the impact axis is reduced. It was difficult to reduce effectively.

  An object of the present invention is to provide an impact tool capable of effectively reducing vibrations generated in a tool body.

  The present invention is provided in a tool body that supports a tip tool, an operation member that is reciprocally movable in the tool body, and that generates a striking force that is transmitted to the tip tool, and the tool body. A motor having an output shaft; a motion conversion mechanism provided in the tool body; and a motion conversion mechanism for converting the rotational motion of the output shaft into a reciprocating motion and transmitting the reciprocating motion to the operation member; An impact tool comprising: a bearing that supports the output shaft; and a vibration reduction mechanism that is swingably provided in the tool body and that reduces vibrations of the tool body. The mechanism includes a support member attached to the tool body so as to be swingable in a direction along a center line of the operation member, a weight attached to the support member, and the weight reaches a predetermined amplitude. When And having a struck portion formed to impinge on the tool body via sexual body.

  The hit portion is preferably provided on the hitting shaft or in the vicinity thereof.

  It is preferable that the elastic body is provided on the tip tool side of the weight in the hitting shaft direction.

  It is preferable that a second elastic body is provided on the anti-tip tool side in the hitting shaft direction of the weight.

  A fan that rotates by rotation of the motor; the vibration reduction mechanism and the fan are arranged side by side in the striking axis direction; and the elastic body or the second elastic body abuts on the weight It is preferable to prevent the weight from excessively swinging and coming into contact with the fan or a plate provided between the fan and the vibration reducing mechanism.

  It is preferable that the hit portion is formed in a planar shape perpendicular to the hitting axis direction.

  It is preferable that the elastic body is provided in the hit portion.

  It is preferable that the elastic body is made of a rubber member.

  The support member is preferably an elastic member.

  The support member is preferably a leaf spring.

  According to the present invention, it is possible to effectively reduce vibration generated in the tool body.

It is a longitudinal cross-sectional view which shows the impact tool which is embodiment of this invention. (A), (b) is sectional drawing for demonstrating the effect | action of the vibration reduction mechanism provided in the impact tool shown in FIG. It is sectional drawing which shows the structure of the fan provided in the impact tool shown in FIG. It is sectional drawing which shows the flow of the air discharged | emitted from the inside of the tool main body of the impact tool shown in FIG. 1 to the exterior. It is a figure explaining the vibration system in the striking tool shown in FIG. It is sectional drawing in the VI-VI line of FIG. It is a side view which shows the structure of the plate provided in the impact tool shown in FIG.

  Hereinafter, an embodiment of the present invention will be described in detail with reference to FIGS.

  The impact tool 10 shown in FIG. 1 is a hammer drill. That is, the impact tool 10 transmits the power of a motor, for example, the electric motor 11, to the tip tool 12, and converts the tip tool 12 into a function of rotating the tip tool 12 and a striking force applied to the tip tool 12. With functions. The impact tool 10 has a tool body 13, and the tool body 13 has a casing (including a housing) 14 and a gear cover 15. The casing 14 has a cylindrical body portion 14a and a handle portion 14b continuous with one end of the body portion 14a. The handle portion 14b is a place where an operator who uses the striking tool 10 grasps it by hand. The casing 14 and the gear cover 15 are fixed by a fastening member in a state where the opening end of the body portion 14a opposite to the handle portion 14b and one opening end of the gear cover 15 are in contact with each other. The fastening member is not shown for convenience.

  The gear cover 15 has a cylindrical shape, and an inner cover 16 is provided inside the gear cover 15. The inner cover 16 is made of a metal material having excellent thermal conductivity, such as aluminum. The inside of the tool body 13 is partitioned by an inner cover 16 into a first storage chamber 17 formed in the body portion 14 a and a second storage chamber 18 formed in the gear cover 15. That is, the inner cover 16 serves as a partition wall.

  The electric motor 11 is provided in the first storage chamber 17. The electric motor 11 includes a stator 19 fixed to the casing 14 and a rotor 20 that is rotatably provided. The rotor 20 is rotatable about a first center line A that is an axis, and the stator 19 is disposed outside the rotor 20 in a radial direction centered on the first center line A. The first center line A is arranged along the horizontal direction in FIG. 1 for convenience. Further, the rotor 20 has an output shaft 21 and a coil 22 attached to the output shaft 21. An output gear 23 is formed on the outer peripheral surface of the output shaft 21.

  The inner cover 16 has an outer cylinder part 16a and an inner cylinder part 16b provided coaxially with the outer cylinder part 16a. The inner cylinder part 16b is provided inside the outer cylinder part 16a. An O-ring 15 a as a sealing device is interposed between the outer peripheral surface of the inner cover 16 and the inner peripheral surface of the gear cover 15. Furthermore, the inner cover 16 has an overhanging portion 16c that connects the end portion of the outer cylinder portion 16a and the end portion of the inner cylinder portion 16b in a direction along the first center line A. The overhanging portion 16c extends in the radial direction about the first center line A. The inner cylinder portion 16b has a cylindrical shape, and a bearing 24 is attached to the inner peripheral surface of the inner cylinder portion 16b (see FIG. 2A). An O-ring 57 as a sealing device is attached between the inner peripheral surface of the inner cylinder portion 16 b and the outer ring of the bearing 24. The bearing 24 is a sealed bearing in which a sealing device (not shown) is attached between the inner ring and the outer ring.

  Further, a bearing (not shown) is provided at a location near the handle portion 14b in the first storage chamber 17. The bearing and the bearing 24 are arranged on the same axis, and the output shaft 21 is supported by two bearings so as to be rotatable around the first center line A. Thus, two bearings are arranged at two different locations in the direction along the first centerline A. One end of the output shaft 21 is disposed in the second storage chamber 18, and the output gear 23 is provided in a portion of the output shaft 21 disposed in the second storage chamber 18.

  The first storage chamber 17 is provided with a brush (not shown) that supplies power to the coil 22. A power cord 25 is attached to the handle portion 14b, and the power cord 25 is connected to an external power source (not shown). The handle portion 14b is provided with a trigger 26, and a control circuit (not shown) is provided inside the handle portion 14b. This control circuit performs control to supply power supplied via the power cord 25 to the brush. In the electric motor 11, when the trigger 26 is operated, electric power is supplied to the coil 22 via the power cord 25, a rotating magnetic field is formed between the rotor 20 and the stator 19, and the rotor 20 rotates.

  A fan 27 is provided between the coil 22 and the inner cover 16 in the direction along the first center line A in the first storage chamber 17. The fan 27 is a mechanism for forming a flow of air that cools the interior of the electric motor 11 and the second storage chamber 18, and the fan 27 of the present embodiment is configured by a centrifugal fan. The fan 27 has an impeller 27a attached to the output shaft 21 as shown in FIG. 3, and a guide wall 27b surrounding the outer peripheral side of the impeller 27a. The impeller 27a is configured to rotate integrally with the output shaft 21, and the impeller 27a includes a plurality of blades 27d extending from the inside toward the outside in the radial direction centered on the first centerline A. doing.

  The guide wall 27b is provided so as to surround the impeller 27a within a predetermined angle range. The guide wall 27 b is provided between the stator 19 and the inner cover 16 in a direction along the first center line A. The guide wall 27 b is fixed so as not to rotate with respect to the casing 14. The fan 27 has an intake passage 27c formed between the impeller 27a and the guide wall 27b. The intake passage 27c is formed from the inside to the outside in the radial direction centering on the first center line A.

  Further, on the outer peripheral side of the impeller 27a, for example, on the coupling portion between the casing 14 and the gear cover 15, a vent hole 28 is provided to communicate the inside and the outside of the tool body 13 as shown in FIGS. Yes. The vent hole 28 is provided to discharge the air guided by the fan 27 to the outside of the tool body 13. The vent holes 28 are provided at two locations on the side and bottom of the tool body 13. The guide wall 27b is opened at two locations facing the vent hole 28 in the circumferential direction around the first center line A.

  An intermediate shaft 29 is provided in the second storage chamber 18. The intermediate shaft 29 is a power transmission element that transmits the power of the output shaft 21 to the tip tool 12. Two bearings 30 are coaxially provided in the second storage chamber 18, and the intermediate shaft 29 is supported by the two bearings 30 so as to be rotatable about the second center line B. The two bearings 30 are attached to the gear cover 15. The second center line B is parallel to the first center line A, and the second center line B is arranged non-coaxially with the first center line A. A first gear 31 is provided at an end of the intermediate shaft 29 that is closer to the overhanging portion 16c. The first gear 31 is meshed with the output gear 23. Further, a second gear 32 is formed between the two bearings 30 in the intermediate shaft 29.

  Further, a cylinder 33 is provided in the second storage chamber 18. The cylinder 33 is an element that transmits the torque of the intermediate shaft 29 to the tip tool 12. The cylinder 33 has a large-diameter cylindrical portion 34 and a small-diameter cylindrical portion 35 that are provided coaxially with the third center line C as the center. The inner diameter of the large diameter cylindrical portion 34 is larger than the inner diameter of the small diameter cylindrical portion 35. A third gear 36 is attached to the outer peripheral surface of the large diameter cylindrical portion 34. The third gear 36 is provided so as to rotate integrally with the cylinder 33, and the third gear 36 is engaged with the gear 32. The second gear 32 and the third gear 36 are elements that transmit the torque of the intermediate shaft 29 to the cylinder 33.

  The gear cover 15 has a cylindrical portion 37 at a location opposite to the casing 14 in the direction along the first center line A. The inner diameter of the cylindrical portion 37 is larger than the outer diameter of the large diameter cylindrical portion 34 and the outer diameter of the small diameter cylindrical portion 35. A grip portion (not shown) is attached to the outer peripheral surface of the cylindrical portion 37, and a bearing 38 is attached to the inner peripheral surface of the cylindrical portion 37. A bearing 39 is attached to the inner peripheral surface of the inner cover 16. The two bearings 38 and 39 are arranged coaxially, and the large-diameter cylindrical portion 34 is rotatably supported by the bearing 39. The small diameter cylindrical portion 35 is rotatably supported by a bearing 38. That is, the cylinder 33 can rotate around the third center line C by the two bearings 38 and 39. The third center line C is parallel to the first center line A and the second center line B, and the third center line C is non-coaxial with the first center line A and the second center line B.

  FIG. 1 is a longitudinal sectional view including the third center line C. In FIG. 1, the first center line A is located below the third center line C, and the second center line B is the first center line A. It is in a lower position. The first center line A, the second center line B, and the third center line C are all parallel. The first center line A, the second center line B, and the third center line C may all be located on the same plane, or only two center lines are located on the same plane. Also good.

  The cylinder 33 is positioned and fixed with respect to the gear cover 15 in a direction along the third center line C. Further, a sealing device 56 is provided between the cylindrical portion 37 and the small diameter cylindrical portion 35. The sealing device 56 is configured by a known oil seal or the like, and the sealing device 56 is for preventing the lubricating oil sealed in the second storage chamber 18 from leaking outside the tool body 13. It is.

  The tip of the small diameter cylindrical part 35 is exposed to the outside of the cylindrical part 37. The tip tool 12 is inserted into the small diameter cylindrical portion 35. A groove 12 a having a length in the direction along the third center line C is provided on the outer peripheral surface of the tip tool 12. On the other hand, a holding hole 35a penetrating the small-diameter cylindrical portion 35 in the radial direction is provided, and a ball 55 is disposed in the holding hole 35a. An end cover 40 is attached to a portion of the small-diameter cylindrical portion 35 that is exposed to the outside of the cylindrical portion 37.

  The end cover 40 is configured to rotate integrally with the cylinder 33, and the end cover 40 includes a pressing member 40a that prevents the ball 55 from falling off the holding hole 35a. A part of the ball 55 held in the holding hole 35a is disposed in the groove 12a. That is, the ball 55 can roll in the groove 12a. The cylinder 33 and the tip tool 12 are prevented from rotating relative to each other by the engaging force of the ball 55. That is, the torque of the cylinder 33 is transmitted to the tip tool 12 via the ball 55, and the tip tool 12 rotates.

  Further, the tip tool 12 is movable in the direction along the third center line C with respect to the cylinder 33 based on the length of the groove 12a in the direction along the third center line C. The end cover 40 is configured to be attachable to and detachable from the cylinder 33. When the end cover 40 is operated, the ball 55 comes out of the holding hole 35a, so that the tip tool 12 can be replaced.

  A piston 41 is inserted into the large diameter cylindrical portion 34. The piston 41 is movable in the direction along the third center line C within the large diameter cylindrical portion 34. The piston 41 has a cylindrical portion 41a and a bottom portion 41b formed continuously with the cylindrical portion 41a. The opening part of the cylindrical part 41a is arrange | positioned at the small diameter cylindrical part 35 side. The cylindrical portion 41a is provided with a vent hole 41c penetrating in the radial direction, and a striker 42 is inserted into the cylindrical portion 41a. The striker 42 is movable in the direction along the third center line C with respect to the piston 41, and a pneumatic chamber 43 is formed between the striker 42 and the bottom 41b in the cylindrical portion 41a. The volume of the pneumatic chamber 43 is set so that the striking force generated by the reciprocating motion of the piston 41 becomes a target value. An O-ring 42 a is attached to the outer peripheral surface of the striker 42, and the O-ring 42 a maintains an airtight space between the striker 42 and the piston 41.

  In the cylinder 33, an intermediate element 44 is provided between the striker 42 and the tip tool 12. That is, the intermediate element 44 is disposed between the striker 42 and the tip tool 12 in a direction along the third center line C, and the intermediate element 44 is positioned in the direction along the third center line C with respect to the cylinder 33. It is movable. The intermediate element 44 is an element that transmits the striking force applied to the striking element 42 by the pressure increase in the pneumatic chamber 43 to the tip tool 12. The intermediate element 44 can contact or move away from the striker 42 and the tip tool 12.

  On the other hand, the second storage chamber 18 is provided with a motion conversion mechanism 45 that converts the rotational motion of the intermediate shaft 29 into the reciprocating motion of the piston 41. The motion conversion mechanism 45 has an inner ring 45a and an outer ring 45b. The inner ring 45 a is attached to the outer peripheral surface of the intermediate shaft 29. The inner ring 45a is rotatable relative to the intermediate shaft 29. The outer circumferential surface of the inner ring 45a has an arc shape in a plane including the second center line B, and a groove (not shown) is formed on the outer circumferential surface of the inner ring 45a. Corresponding to the phase change in the circumferential direction of the inner ring 45a, the position of the groove in the direction along the second center line B is different. A plurality of rolling elements 45c are interposed in the circumferential direction between the outer ring 45b and the inner ring 45a. The rolling element 45c can roll along the groove. The outer ring 45b is provided with a connecting rod 45d, and the connecting rod 45d is connected to the piston 41. For this reason, the outer ring 45b does not rotate around the center line B.

  Further, a clutch 46 is provided in the second storage chamber 18. The clutch 46 is a mechanism for connecting and disconnecting a power transmission path between the inner ring 45a and the intermediate shaft 29. The clutch 46 rotates integrally with the intermediate shaft 29 and is movable in a direction along the second center line B with respect to the intermediate shaft 29. When the clutch 46 moves toward the left side along the second center line B and stops, the power transmission path between the intermediate shaft 29 and the inner ring 45a is connected. That is, the clutch 46 is engaged. On the other hand, when the clutch 46 moves to the right side along the second center line B and stops, the power transmission path between the intermediate shaft 29 and the inner ring 45a is interrupted. That is, the clutch 46 is released. Note that the movement, stop, and moving direction of the clutch 46 in the direction along the second center line B are switched when the operator operates the mode switch. The mode change switch is provided on the outer surface of the tool body 13, but is not shown for convenience.

  When the intermediate shaft 29 rotates with the clutch 46 engaged, the rolling element 45c rolls along the groove, and the outer ring 45b has a predetermined angle around the center point on the second center line B. Swing within range. The center point is not shown for convenience. When the outer ring 45b swings within a predetermined angle range, the piston 41 reciprocates in the direction along the third center line C.

  The operation of the impact tool 10 configured as described above will be described. First, the operator grasps the handle portion 14b with one hand, grasps the grip portion with the other hand, presses the tip tool 12 against the object, and pulls the trigger 26. Then, electric power is supplied to the electric motor 11 to rotate the rotor 20, and the torque of the output shaft 21 is transmitted to the intermediate shaft 29 via the output gear 23 and the gear 31. The torque of the intermediate shaft 29 is transmitted to the cylinder 33 via the gear 32 and the third gear 36. The torque of the cylinder 33 is transmitted to the tip tool 12 via the ball 55.

  During the above operation, when the mode switch is operated and the driver mode is selected, the clutch 46 is released. For this reason, the rotational motion of the intermediate shaft 29 is not converted into the reciprocating motion of the piston 41. Accordingly, no striking force is applied to the tip tool 12. On the other hand, when the mode changeover switch is operated and the hammer driver mode is selected, the clutch 46 is engaged. For this reason, the rotational motion of the intermediate shaft 29 is converted into the reciprocating motion of the piston 41. When the O-ring 42a of the striker 42 is positioned closer to the tip tool 12 than the vent hole 41c, the pneumatic chamber 43 communicates with the outside of the piston 41 through the vent hole 41c. When the tip tool 12 is pressed against the work material as the object, the striker 42 moves to the left in FIG. Then, the vent hole 41 c is closed by the striker 42. Next, when the piston 41 moves to the right in FIG. 1, the pressure in the pneumatic chamber 43 rises and a striking force is generated. The generated striking force is transmitted to the tip tool 12 via the striking element 42 and the intermediate element 44.

  Therefore, the tip tool 12 is hit while rotating. When the striker 42 moves to the right in FIG. 1, the vent hole 41c is opened, the air pressure chamber 43 communicates with the atmosphere, and the pressure decreases. Accordingly, the striking force is reduced and the striker 42 stops. Thereafter, the above action is repeated as the piston 41 reciprocates.

  By the way, when the piston 41 repeats reciprocating motion, vibration in the direction along the third center line C is generated due to the reaction force when the impact force is generated, the operation of the piston 41, and the like. This vibration is transmitted to the tool body 13 via the cylinder 33 and the bearings 38 and 39, and is transmitted to the tool body 13 via the motion conversion mechanism 45, the intermediate shaft 29, and the bearing 30. Then, the tool body 13 vibrates. Here, an example of the vibration state of the tool body 13 will be described with reference to FIG. For example, it oscillates (oscillates) along an arcuate locus within a predetermined angle range around the oscillation center D. The swing center D is an intersection of the first line segment E and the second line segment F. The first line segment E passes through the tip of the tip tool 12 and the center point in the longitudinal direction of the handle portion 14b. The second line segment F passes through the center of gravity G of the tool body 13 and is perpendicular to the first center line A. In FIG. 5, the center of gravity G of the tool body 13 is represented on the first center line A. The vibration state of the tool main body 13 shown in FIG. 5 represents only one analysis example.

  The striking tool 10 of the present embodiment has a vibration reduction mechanism 47 that reduces the vibration of the tool body 13. The configuration of the vibration reducing mechanism 47 will be described with reference to FIGS. 1, 2, 5, 6, and 7. The vibration reducing mechanism 47 includes a support member 48 attached to the overhanging portion 16 c and a weight 49 supported by the support member 48. The support member 48 is formed of an elastic member, for example, a metal material having elasticity, preferably a leaf spring. The support member 48 includes a base portion 48a and two arm portions 48b that are bifurcated from the base portion 48a. Opposing portions of the two arm portions 48b are formed in an arc shape. The base 48 a is sandwiched between the overhanging portion 16 c of the inner cover 16 and the mount member 50, and is fixed to the overhanging portion 16 c with screws 51. The fixing position J of the support member 48 by the screw 51 is located below the second center line B. Further, a rubber member 52, which is an elastic member for absorbing vibration of the support member 48, is attached to the base portion 48 a of the support member 48.

  The weight 49 is attached to the free ends of the two arm portions 48b. The weight 49 is made of, for example, a metal material. The weight 49 has a C-shape in a plane perpendicular to the first center line A, and the inner peripheral surface of the weight 49 is formed in an arc shape. The weight 49 includes two component pieces 49a and 49b attached with the two arm portions 48b interposed therebetween. In the direction along the first center line A, the component piece 49b is disposed at a position closer to the protruding portion 16c than the component piece 49a. In the direction along the first center line A, the component piece 49b is thicker than the component piece 49a. Therefore, the width of the weight 49 as a whole along the first center line A with the support member 48 as the center is the width of the component piece 49b located on the side opposite to the electric motor 11 (the motion conversion mechanism 45 side). Is wider than the component piece 49a. In FIG. 5, the center of gravity H of the weight 49 is disposed above the third center line C. A shaft hole 53 is provided between the weight 49 and the two arm portions 48b in a plane perpendicular to the first center line A (see FIG. 6). An inner cylinder portion 16b is disposed in the shaft hole 53. That is, the vibration reduction mechanism 47 is provided so as to surround the inner cylinder portion 16b in a plane perpendicular to the first center line A.

  The natural frequency of the vibration reduction mechanism 47 is set to be the same as the number of hits during the drilling operation. The natural frequency of the vibration reducing mechanism 47 is determined by conditions such as the mass of the weight 49, the rigidity of the support member 48, and the length from the fixing position (fixed end) of the support member 48 to the center of gravity H of the weight 49. Further, when the support member 48 has spring elasticity, the spring constant of the support member 48 becomes a factor for determining the natural frequency. Further, the inner diameter of the shaft hole 53 is set to a value at which the vibration reducing mechanism 47 and the inner cylinder portion 16b do not come into contact when the support member 48 and the weight 49 are swung.

  In the vibration reducing mechanism 47 having the above-described configuration, the tool body 13 vibrates around the swing center D. Specifically, the support member 48 is elastically deformed with the fixed position J as a fulcrum and vibrates in the direction opposite to the vibration direction of the tool body 13 (reverse phase), thereby reducing the vibration of the tool body 13 and Absorb. Further, when the support member 48 and the weight 49 vibrate, the rubber member 52 is elastically deformed so as to be crushed by the mount member 50 and the support member 48 and absorbs the vibration.

  In particular, the vibration reducing mechanism 47 has a weight on or near the third center line C, which is a striking axis, as shown in FIGS. 2 (a) and 2 (b) in order to effectively reduce vibration at the time of striking. It has hit | damage parts (action point) 63 and 64 formed in the tool main body 13 so that 49 may hit through the elastic bodies 61 and 62 when a predetermined amplitude is reached. The elastic bodies 61 and 62 may be provided on the weight 49 on the movable side, but are preferably provided on the tool body 13 on the fixed side from the viewpoint of manufacturability and durability. Specifically, the hit portion 63 at the front portion in the striking axial direction is provided on the inner cover 16, and the hit portion 64 at the rear portion in the striking axial direction is provided on the guide wall 27 b of the fan 27.

  Moreover, it is preferable that these hit | damage parts 63 and 64 are formed in the planar shape orthogonal to a hit | damage axial direction in order to receive hit | damage force uniformly in a surface. The front portion of the front component piece 49b of the weight 49 is inclined so that the wall thickness decreases toward the front end side so as to be a surface parallel to the hit portion 63 when hitting the hit portion 63 via the elastic body 61. Is formed. The rear surface portion of the rear component piece 49a of the weight 49 is inclined so that the wall thickness decreases toward the front end side so as to be a surface parallel to the hit portion 64 when hitting the hit portion 64 via the elastic body 62. Is formed.

  The elastic body 61 at the front part in the striking axial direction is made of a flat rubber member, and is fixed to a planar hitting surface which is a hitting part 63 on the tip tool 12 side of the weight 49 in the striking axial direction by a fixing means such as an adhesive. It is attached. The elastic body 62 at the rear part in the striking axial direction is disposed so that the striking surface is retracted to the rear part in the striking axial direction in relation to the fan 27, so that a rod shaft-like rubber member having a predetermined length is filled to fill the space. And is attached to a flat hitting surface which is the hitting portion 64 by a fixing means such as an adhesive. The adhering means is not limited to the adhesive material, and may be a concave portion or a screw that restrains the elastic body.

  The vibration reduction mechanism 47 and the fan 27 are arranged side by side in the direction along the first center line A. For this reason, when the support member 48 and the weight 49 vibrate and the vibration width is large, the weight 49 may come into contact with the fan 27, specifically the impeller 27a. Therefore, the first storage chamber 17 is provided with a plate 54 that prevents the weight 49 from contacting the impeller 27a. The plate 54 is integrally formed of a metal plate, and the plate 54 is fixed to the tool body 13. As shown in FIG. 7, the plate 54 has a shaft hole 54a penetrating in the direction along the first center line A, and the boss portion of the output shaft 21 and the impeller 27a is inserted into the shaft hole 54a. . An inner peripheral end of the plate 54 is disposed between the fan 27 and the inner cylinder portion 16b in a direction along the first center line A. The vibration reducing mechanism 47 is disposed in a space surrounded by the plate 54 and the inner cover 16.

  The vibration reducing mechanism 47 and the fan 27 are arranged side by side in the striking axis direction. When the first elastic body 61 or the second elastic body 62 contacts the weight 49, the weight 49 excessively swings. Thus, it is possible to prevent the fan 27 or the plate 54 provided between the fan 27 and the vibration reducing mechanism 47 from coming into contact.

  The plate 54 is provided with a vent hole 54b at a location corresponding to the outer peripheral end of the impeller 27a. The vent hole 54b is provided in an arc shape centered on the first center line A. The vent hole 54b is a path for guiding the air flow formed by the rotation of the impeller 27a toward the inner cover 16. Further, the plate 54 is provided with a plurality of mounting holes 54c penetrating in the thickness direction.

  On the other hand, the inner cover 16 is provided with a plurality of locking claws 16e (see FIG. 6), and the locking claws 16e are inserted into the mounting holes 54c. With this structure, the plate 54 is positioned and fixed with respect to the tool body 13 in the circumferential direction around the first center line A. In the above embodiment, the bearings 24, 30, and 38 have a function of receiving both the thrust load and the radial load.

  On the other hand, a lubricated portion is provided in the second storage chamber 18. The lubricated portion includes a meshing portion between the output gear 23 and the gear 31, a meshing portion between the gear 32 and the third gear 36, a motion conversion mechanism 45, and a contact portion between the piston 41 and the cylinder 33. Lubricating oil for lubricating and cooling the lubricated part is sealed in the second storage chamber 18. The sealing device 56 prevents the lubricating oil in the second storage chamber 18 from leaking outside the tool body 13 via the space between the small diameter cylindrical portion 35 and the cylindrical portion 37. Further, the O-ring 15 a prevents the lubricating oil in the second storage chamber 18 from leaking to the first storage chamber 17 via the space between the inner cover 16 and the gear cover 15. Further, a sealing device (not shown) attached to the bearing 24 prevents the lubricating oil in the second storage chamber 18 from leaking to the first storage chamber 17.

  In the present embodiment, the fixing position J of the support member 48 is below the second center line B as shown in FIG. The support member 48 and the weight 49 vibrate with the fixed position J as a fulcrum, and the vibration locus of the weight 49 has an arc shape. That is, when the tool main body 13 vibrates in an arc shape around the swing center D, the vibration trajectory of the tool main body 13 and the vibration trajectory of the weight 49 can be approximated as much as possible, and the vibration reduction efficiency is improved. Further, the center line C and the center of gravity H of the weight 49 are set as close as possible in the radial direction centering on the third center line C. Therefore, the vibration reduction mechanism 47 can effectively vibrate the weight 49, and the vibration reduction effect is improved.

  Furthermore, the bearing 24 and the weight 49 overlap (overlap) at least a part of the arrangement position in the direction along the first center line A. Further, the vibration reducing mechanism 47 is disposed outside the output gear 23 in the radial direction centered on the first center line A. Further, the vibration reduction mechanism 47 and the output gear 23 partially overlap with each other in the direction along the first center line A. The first center line A and the third center line C are parallel. Therefore, the arrangement space of the bearing 24 and the vibration reduction mechanism 47 can be shortened as much as possible in the direction along the third center line C. Therefore, an increase in the size of the impact tool 10 can be suppressed.

  Further, the vibration reduction mechanism 47 is arranged on the outer side of the inner cylinder part 16b in the radial direction centering on the first center line A, and the output gear 23 is arranged on the inner side of the inner cylinder part 16b. Therefore, the output shaft 21 can be as short as possible from the portion supported by the bearing 24 to the end including the portion where the output gear 23 is formed. Therefore, the output shaft 21 can be supported by one bearing 24 on the output gear 23 side, and the number of parts can be reduced.

  In addition, since the output shaft 21 is inserted into the shaft hole 53 of the vibration reduction mechanism 47, it is possible to reduce the arrangement space of components in the direction along the first center line A. Further, even if the vibration reducing mechanism 47 vibrates, it can be avoided to contact the output shaft 21. Furthermore, even if the vibration reduction mechanism 47 vibrates, it can avoid contacting the cylindrical part 16d.

  The fan 27 in the present embodiment rotates by the torque of the rotor 20 of the electric motor 11 and sucks the air in the first storage chamber 17. In the first storage chamber 17, an air flow is formed by the rotation of the fan 27. The electric motor 11 exchanges heat with flowing air, and the temperature rise of the electric motor 11 is suppressed. The air in the first storage chamber 17 is guided outward in the radial direction through the intake passage 27c. The guided air passes through the vent holes 54 b of the plate 54 and flows between the plate 54 and the inner cover 16. The air flowing between the plate 54 and the inner cover 16 flows along the surface of the overhanging portion 16c of the inner cover 16, and then flows in the shaft hole 53 along the surface of the inner cylinder portion 16b.

  The heat in the second storage chamber 18 is transmitted to the inner cover 16. The heat transmitted to the inner cover 16 is transmitted to the air flowing along the inner cover 16, and the temperature of the air rises. The air whose temperature has risen passes through the vent hole 28 and is discharged to the outside of the tool body 13. Thus, the temperature rise in the second storage chamber 18 is suppressed.

  Therefore, the viscosity of the lubricating oil sealed in the second storage chamber 18 decreases and the lubricating oil leaks to the outside of the tool main body 13, or the lubricating oil in the second storage chamber 18 flows into the first storage chamber 17. Can be prevented from leaking. Further, it is possible to prevent the characteristics of the rubber member 52 attached to the support member 48 from changing or deteriorating. Furthermore, it is possible to prevent the striking force from deviating from the target value due to a change in the air pressure of the air pressure chamber 43 due to a temperature rise in the second storage chamber 18.

  Moreover, since the component piece 49b is wider than the component piece 49a, the bearing 24 can be disposed close to the electric motor 11 without reducing the vibration reduction effect. In particular, when the fan 27 is provided between the bearing 24 and the electric motor 11, the fan 27 and the bearing 24 can be arranged as close as possible in the direction along the first center A. Furthermore, since the weight 49 is disposed on the opposite side of the intermediate shaft 29 with the output shaft 21 therebetween, the weight 49 can be prevented from interfering with the intermediate shaft 29 when the weight 49 vibrates.

  Further, since the fixed position J for transmitting a force for reducing vibration to the tool body 13 when the weight 49 vibrates is close to the center of gravity G of the impact tool 10 in the direction along the center line C, the vibration is effectively vibrated. Reduction can be achieved. Further, the fixed position J is separated from the center of gravity G of the impact tool 10 from the center line C in the direction along the third center line C, and the weight 49 from the fixed position J in the radial direction centered on the first center line A. Therefore, the amount of vibration of the weight 49 can be increased.

  Further, the first center A of the output shaft 23 is arranged in parallel and non-coaxially with the third center line C. Therefore, the dimension of the striking tool 10 in the direction along the third center line C can be suppressed, and the center of gravity G of the striking tool 10 and the fixed position J of the weight 49 are brought closer in the direction along the third center line C. The generation of rotational moment due to the vibration of the weight 49 can be suppressed.

  In particular, the vibration reduction mechanism 47 includes a support member 48 attached to the tool main body 13 so as to be swingable in a direction along the third center line C of the operation member 41, and a weight 49 attached to the support member 48. When the weight 49 reaches a predetermined amplitude, the hit portion (operation point) formed so as to contact the tool body 13 via elastic bodies (also referred to as first elastic body and second elastic body) 61 and 62 ) 63 and 64, the vibration generated in the tool body 13 can be effectively reduced.

  Moreover, since the elastic bodies 61 and 62 are provided in the hit | damage parts 63 and 64, the improvement of productivity and durability can be aimed at rather than the case where it is provided in the weight 49. The hit portions 63 and 64 are provided on the front and rear portions in the hitting axial direction on or near the third center line C, which is the hitting shaft, in order to cancel the vibration in the hitting axial direction generated in the tool body 13. Therefore, it is possible to effectively reduce the vibration in the hitting shaft direction that occurs in the tool body 13. Since the hit parts 63 and 64 are formed in a plane perpendicular to the third centerline C direction as the hitting shaft, the elastic bodies 61 and 62 can be easily provided and the impact at the time of hitting is dispersed. And can be absorbed effectively. Since the elastic bodies 61 and 62 are made of a rubber member, the manufacturing can be facilitated and the cost can be reduced.

  It goes without saying that the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the scope of the invention. For example, it is preferable that the hit portion is provided on both the front and rear portions in the hitting axis direction on or near the hitting shaft in order to absorb the vibration in the hitting shaft direction generated in the tool body. On the other hand, for example, it may be provided only at the front part. Moreover, although the electric motor is illustrated as a motor, an air motor may be sufficient.

  In the above-described embodiment, the striking tool only needs to give a striking force to the tip tool, and the striking tool may have a configuration in which the tip tool cannot be rotated. Moreover, the structure which can switch 3 types, hammer exclusive mode, drill exclusive mode, and hammer drill mode may be sufficient as an impact tool. The hammer-only mode is a mode that gives only the striking force to the tip tool, the drill-only mode is a mode that gives only the turning force to the tip tool, and the hammer drill mode is a mode that gives the striking force and turning force to the tip tool. is there. Further, the tip tool may be a driver bit for tightening the screw member. Furthermore, the tip tool may be a drill bit for drilling and crushing concrete, stone or the like.

  Further, the fan provided in the casing may be an axial fan. The weight may be provided with a hole, a notch, a groove or the like for air to flow therethrough. Further, the impact tool should be used in any state of the first to third centerlines along the vertical direction, along the horizontal direction, and between the horizontal and vertical directions. You can also. Further, the reference for analyzing the vibration of the tool body can use the center of gravity of the impact tool instead of the center of gravity of the tool body. The center of gravity of the impact tool is the center of the total mass of the mass of the tool body and the masses of parts, mechanisms, elements, etc. provided inside the tool body. Furthermore, the striking tool may have a structure in which a battery for supplying electric power to the electric motor is housed in the tool body, or a structure in which the battery is attached to the tool body in a cassette structure.

DESCRIPTION OF SYMBOLS 11 Electric motor 12 Tip tool 13 Tool main body 21 Output shaft 27 Fan 41 Operation member 45 Motion conversion mechanism 47 Vibration reduction mechanism 48 Support member 49 Weight 54 Plate 61, 62 Elastic body 63, 64 Impacted part

Claims (10)

A tool main body for supporting the tip tool; an operating member provided in the tool main body so as to be capable of reciprocating; and generating a striking force transmitted to the tip tool; and an output shaft provided in the tool main body. A motor conversion mechanism that is provided in the tool body, converts a rotational motion of the output shaft into a reciprocating motion and transmits the reciprocating motion to the operation member, and is provided in the tool body, and A striking tool comprising a bearing that supports an output shaft, a vibration reduction mechanism that is swingably provided in the tool body, and that reduces vibration of the tool body,
The vibration reduction mechanism includes a support member attached to the tool body so as to be swingable in a direction along a center line of the operation member, a weight attached to the support member, and the weight having a predetermined weight. A striking tool having a striking part formed so as to hit the tool main body through an elastic body when the amplitude is reached.   The impact tool according to claim 1, wherein the hit portion is provided on or near the impact axis.   The impact tool according to claim 1, wherein the elastic body is provided on a tip tool side of the weight in the impact axis direction.   The impact tool according to claim 3, wherein a second elastic body is provided on the side opposite to the end tool in the impact axis direction of the weight. A fan that rotates by rotation of the motor;
The vibration reduction mechanism and the fan are arranged side by side in the hitting shaft direction, and the weight is excessively swung when the elastic body or the second elastic body abuts on the weight, so that the fan The striking tool according to claim 3, wherein the striking tool prevents contact with a plate provided between the fan and the vibration reduction mechanism.   The said hit | damage part is formed in the planar shape orthogonal to the said striking-axis direction, The striking tool of Claim 3 characterized by the above-mentioned.   The impact tool according to claim 1, wherein the elastic body is provided in the hit portion.   The impact tool according to claim 1, wherein the elastic body is made of a rubber member.   The impact tool according to claim 1, wherein the support member is an elastic member.   The impact tool according to claim 1, wherein the support member is a leaf spring.

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