JP2013212543A - Impact tool - Google Patents

Abstract

PROBLEM TO BE SOLVED: To shorten component arrangement space in a direction along a center line of an operation member as much as possible.SOLUTION: An impact tool includes a casing 13 supporting a tip tool 12, a piston 41 reciprocably provided in the casing 13, an electric motor 11 provided in the casing 13 and having an output shaft 21, a motion converting mechanism 45 provided in the casing 13, a bearing 24 provided in the casing 13 and supporting the output shaft 21, and a vibration reducing mechanism 47 provided in the casing 13. The bearing 24 and the vibration reducing mechanism 47 are arranged so as to at least partially overlap with each other in a direction along a center line C.

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 a striking tool includes a casing, a tip tool rotated by an electric motor provided in the casing, a striking element provided in the casing so as to be capable of reciprocating linearly, and a rotary motion of the electric motor. It has a motion conversion mechanism that converts it into reciprocating motion, and a striking element that transmits the striking force generated by the reciprocating motion of the piston to the tip tool. In this striking tool, the casing vibrates due to the reciprocating motion of the piston, the operation of striking the tip tool with the striking element, and the like. Then, the technique which can reduce the vibration of the casing in an impact tool is proposed, and the example is described in patent document 1. FIG.

  The striking tool described in Patent Document 1 has a hollow casing, and the inside of the casing is divided into a first storage chamber, a second storage chamber, and a third storage chamber by two partition walls. An electric motor is provided in the first storage chamber. The electric motor has an output shaft, and the electric motor is configured such that the output shaft rotates when power from an external power source is supplied.

  A bearing is attached to each of the two partition walls, and the first intermediate shaft is supported by the bearings so as to be rotatable about the first center line. The first intermediate shaft is disposed across the second storage chamber and the third storage chamber. The output shaft and the first intermediate shaft are arranged coaxially, and the output shaft and the first intermediate shaft are connected so as to rotate integrally. A first gear is provided at a portion of the first intermediate shaft located in the third storage chamber.

  The third storage chamber is provided with a second intermediate shaft, and the second intermediate shaft is supported by two bearings so as to be rotatable around the second center line. The second intermediate shaft is provided with a second gear, and the first gear and the second gear are engaged with each other. Further, the second intermediate shaft is provided with a gear portion. Further, the third storage chamber is provided with a cylindrical cylinder, and in the cylinder, the piston, the striker, the intermediate element, and the tip tool reciprocate in the direction along the third center line (center line) of the cylinder. Inserted as possible. A pneumatic chamber is formed between the piston and the striker inside the cylinder. The first center line, the second center line, and the third center line are all parallel. The tip tool is provided to rotate integrally with the cylinder, and the tip of the tip tool is exposed to the outside of the cylinder. A third gear is attached to the cylinder, and the third gear and the gear portion are meshed with each other. Further, a cylindrical sleeve is attached to the outer peripheral surface of the second intermediate shaft so as to be rotatable relative to the second intermediate shaft. A clutch for engaging and releasing the sleeve and the second intermediate shaft is provided in the third storage chamber. The clutch is configured to be switched in operation by operating a change lever. Furthermore, a motion conversion mechanism that converts the rotational motion of the sleeve into the reciprocating motion of the piston is provided in the third storage chamber.

  On the other hand, a vibration reducing mechanism is provided in the second storage chamber. The vibration reduction mechanism includes a support member fixed to the casing, and a counterweight attached to the support member via a leaf spring. The counterweight is provided with a shaft hole, and the second intermediate shaft is inserted into the shaft hole. Moreover, the handle | steering-wheel part is provided in the edge part on the opposite side to the attachment part of the front-end tool in a casing. The handle is provided with a trigger. Furthermore, the grip part is attached near the attachment part of the tip tool in the casing.

  In the impact tool described in Patent Document 1, the operator grips the handle portion with one hand, the grip portion with the other hand, and presses the tip tool against the object. And if a trigger is operated, electric power will be supplied to an electric motor and an output shaft will rotate. The torque of the output shaft is transmitted to the cylinder via the first intermediate shaft and the second intermediate shaft. The tip tool rotates with the cylinder.

  Here, when the drill mode is selected by operating the change lever, the clutch is released, the torque of the second intermediate shaft is not transmitted to the sleeve, and the second intermediate shaft and the sleeve rotate relative to each other. In this way, the tip tool rotates and is not struck by the striker.

  On the other hand, when the hammer drill mode is selected by operating the change lever, the clutch is engaged. For this reason, the torque of the second intermediate shaft is transmitted to the soave, and the second intermediate shaft and the sleeve rotate together. The rotational motion of the sleeve is converted into the reciprocating motion of the piston by the motion conversion mechanism. When the piston reciprocates in the cylinder, the air pressure in the pneumatic chamber rises rapidly and a striking force is generated. This striking force is transmitted to the tip tool via the striking element and the intermediate element.

  The impact tool described in Patent Document 1 generates vibration due to the reciprocating motion of the piston and the impact operation by the impact element, and the vibration is transmitted to the counterweight via the casing, the support member, and the leaf spring. . Then, it is said that the counterweight vibrates in the same direction as the reciprocating motion of the piston and in the opposite direction, and can reduce the vibration of the casing.

JP 2007-237301 A

  However, the impact tool described in Patent Document 1 is provided with two bearings in the direction along the first center line. The vibration reduction mechanism is provided between the two bearings in the direction along the first center line. The first center line is parallel to the third center line. For this reason, the striking tool has a problem of increasing in size in a direction along the third center line (center line) in which the striking element reciprocates.

  An object of the present invention is to provide a striking tool that can prevent the striking element from becoming large in a direction along a center line in which the striking element reciprocates.

  The present invention provides a casing that supports a tip tool, an operating member that is reciprocally movable in the casing and that generates a striking force that is transmitted to the tip tool, and is provided in the casing and has an output. An electric motor having a shaft, a motion conversion mechanism that is provided in the casing, 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 casing, and An impact tool comprising a bearing that supports an output shaft and a vibration reduction mechanism that is movably provided in the casing and that reduces vibrations of the casing, wherein the bearing and the vibration reduction mechanism are It is characterized in that at least a part is overlapped in the direction along the center line of the operating member.

  According to the present invention, the vibration reduction mechanism includes a support member fixed to the casing in a cantilever state so as to be swingable in a direction along the center line, and a weight attached to a free end of the support member. It is characterized by having.

  In the present invention, the electric motor includes a coil that forms a rotating magnetic field when energized, the motion conversion mechanism is disposed in parallel to the center line, and includes a rotatable power transmission shaft, and the output A first gear provided on the shaft and a second gear provided on the power transmission shaft are engaged with each other, and the vibration reduction mechanism is arranged in a direction along the center line in the direction along the center line. The vibration reduction mechanism has a hole or a recess penetrating in a direction along the center line, and the output shaft is inserted into the hole or the recess. .

  In the present invention, the casing has a cylindrical portion formed so as to surround the axis of the output shaft, the output shaft is inserted into the cylindrical portion, and the bearing is formed on an inner peripheral surface of the cylindrical portion. It is attached and the said output shaft is supported, The said cylindrical part is inserted in the said hole, It is characterized by the above-mentioned.

  The present invention is characterized in that the weight has a wide shape on the opposite side of the electric motor around the support member.

  The present invention includes an intermediate shaft that transmits the power of the output shaft to the tip tool, and the weight is disposed on the opposite side of the intermediate shaft across the output shaft.

  According to the present invention (Claim 1), it is possible to prevent the power tool from becoming large in the direction along the center line along which the striker reciprocates.

  According to the present invention (Claim 2), the vibration reducing mechanism vibrates in a direction along the center line with a portion fixed to the casing as a fulcrum. Therefore, it becomes easy to reduce the vibration of the casing.

  According to the present invention (claim 3), since the output shaft is inserted into the hole of the vibration reduction mechanism, it is possible to avoid contact between the output shaft and the vibration reduction mechanism when the vibration reduction mechanism vibrates.

  According to the present invention (Claim 4), when the vibration reducing mechanism vibrates, it is possible to avoid contact between the cylindrical portion and the vibration reducing mechanism.

  According to the present invention (Claim 5), the bearing can be arranged on the electric motor side without reducing the vibration reduction effect by the weight.

  According to the present invention (Claim 6), when the weight vibrates, the weight arrangement position can be optimized so that the weight and the intermediate shaft do not interfere with each other.

It is a longitudinal cross-sectional view which shows the impact tool which is embodiment of this invention. (A), (B), (C) is an expanded sectional view which shows 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 casing of the impact tool shown in FIG. It is a figure explaining the vibration system in the striking tool shown in FIG. It is sectional drawing which shows the principal part of the vibration reduction mechanism shown in FIG. It is sectional drawing in the VII-VII line of FIG. It is a side view which shows the structure of the plate provided in the impact tool shown in FIG. It is a striking tool which is an embodiment of the present invention, and is a longitudinal section showing other examples of a vibration reduction mechanism.

  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 the electric motor 11 to the tip tool 12 and rotates the tip tool 12, and the function of converting the rotational motion of the electric motor 11 into the impact force applied to the tip tool 12. Have The striking tool 10 has a casing 13, and the casing 13 has a housing 14 and a gear cover 15. The housing 14 includes 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 housing 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 casing 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 housing 14 and a rotor 20 that is rotatably provided. The rotor 20 is rotatable about the axis A, and the stator 19 is disposed outside the rotor 20 in the radial direction about the axis A. The axis 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 the direction along the axis A. The overhang portion 16c extends in the radial direction about the axis A. The inner cylinder part 16b has a cylindrical shape, and a bearing 24 is attached to the inner peripheral surface of the inner cylinder part 16b. 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 about the axis A. Thus, two bearings are arranged at two different locations in the direction along the axis 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.

  In the first storage chamber 17, a fan 27 is provided between the coil 22 and the inner cover 16 in the direction along the axis A. 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 has a plurality of blades 27d extending from the inside toward the outside in the radial direction centering on the axis A. .

  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 the direction along the axis A. The guide wall 27 b is fixed so as not to rotate with respect to the housing 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 with the axis A as the center.

  Further, on the outer peripheral side of the impeller 27a, for example, on the coupling portion between the housing 14 and the gear cover 15, a vent hole 28 is provided for communicating the inside and the outside of the casing 13 as shown in FIGS. . The vent hole 28 is provided to discharge the air guided by the fan 27 to the outside of the casing 13. The ventilation holes 28 are provided at two locations on the side and the lower side of the casing 13. The guide wall 27b is opened at two locations facing the vent hole 28 in the circumferential direction around the axis 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 provided coaxially 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 center line B. The two bearings 30 are attached to the gear cover 15. The center line B is parallel to the axis A, and the center line B is arranged non-coaxially with the axis A. A gear 31 is provided at the end of the intermediate shaft 29 that is closer to the overhanging portion 16c. This gear 31 is meshed with the output gear 23. Further, a 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 about the center line C. 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 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 housing 14 in the direction along the axis 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 center line C by the two bearings 38 and 39. The center line C is parallel to the axis A and the center line B, and the center line C is non-coaxial with the axis A and the center line B.

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

  The cylinder 33 is positioned and fixed in a direction along the center line C with respect to the gear cover 15. 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 to the outside of the casing 13. is there.

  The tip of the small diameter cylindrical portion 35 is exposed to the outside of the cylindrical portion 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 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 center line C with respect to the cylinder 33 based on the length of the groove 12a in the direction along the 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 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 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 large diameter cylindrical portion 34.

  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 the direction along the center line C, and the intermediate element 44 is movable in the direction along the center line C with respect to the cylinder 33. . 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 peripheral surface of the inner ring 45a has an arc shape in a plane including the center line B, and a groove (not shown) is formed on the outer peripheral 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 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 the direction along the center line B with respect to the intermediate shaft 29. When the clutch 46 moves toward the left side along the 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. In contrast, when the clutch 46 moves toward the right side along the 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. The movement, stop, and moving direction of the clutch 46 in the direction along the center line B are switched when the operator operates the mode switch. Note that the mode switch is provided on the outer surface of the casing 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 is within a predetermined angle range centered on the center point on the center line B. Swing with. 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 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 sealing member 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, 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 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 casing 13 via the cylinder 33 and the bearings 38 and 39, or is transmitted to the casing 13 via the motion conversion mechanism 45, the intermediate shaft 29, and the bearing 30. Then, the casing 13 vibrates. Here, an example of the vibration state of the casing 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 casing 13 and is perpendicular to the axis A. In FIG. 5, the center of gravity G of the casing 13 is represented on the axis A. Note that the vibration state of the casing 13 shown in FIG. 5 represents only one analysis example.

  The striking tool 10 of this embodiment has a vibration reduction mechanism 47 that reduces the vibration of the casing 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 integrally formed of a metal material. 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 and the mount member 50, and is fixed to the overhanging portion 16 c with screws 51. The support member 48 may be made of a metal material having spring elasticity. The fixing position J of the support member 48 by the screw 51 is located below the center line B. Further, a rubber member 52 is attached to the base 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 axis 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 axis A, the component piece 49b is disposed at a position closer to the protruding portion 16c than the component piece 49a. Further, the component piece 49b is thicker than the component piece 49a in the direction along the first center line. Therefore, with respect to the weight 49 as a whole, the width of the weight 49 in the direction along the axis A is the component piece 49b positioned on the side opposite to the electric motor 11 (the motion conversion mechanism 45 side). It is wider than 49a. In FIG. 5, the center of gravity H of the weight 49 is disposed above the center line C. A shaft hole 53 is provided between the weight 49 and the two arm portions 48 b in a plane perpendicular to the axis A. An inner cylinder portion 16b is disposed in the shaft hole 53. That is, the vibration reducing mechanism 47 is provided so as to surround the inner cylinder portion 16b in a plane perpendicular to the axis 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 reduction mechanism 47 having the above-described configuration, the casing 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 a direction opposite to the vibration direction of the casing 13 (opposite phase), thereby reducing and absorbing the vibration of the casing 13. . 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.

  Furthermore, the vibration reduction mechanism 47 and the fan 27 are arranged side by side in the direction along the axis 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 casing 13. The plate 54 has a shaft hole 54a penetrating in the direction along the axis A, and the bosses of the output shaft 21 and the impeller 27a are inserted into the shaft hole 54a. The inner peripheral end of the plate 54 is disposed between the fan 27 and the inner cylinder portion 16b in the direction along the axis A. The vibration reducing mechanism 47 is disposed in a space surrounded by the plate 54 and the inner cover 16.

  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 centering on the axis 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, 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 casing 13 in the circumferential direction about the axis 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 to the outside of the casing 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 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 casing 13 vibrates in an arc shape around the swing center D, the vibration trajectory of the casing 13 and the vibration trajectory of the weight 49 can be approximated as much as possible, and 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 centered on the center line C. Therefore, the vibration reduction mechanism 47 can effectively vibrate the weight, and the vibration reduction effect is improved.

  Further, the bearing 24 and the weight 49 overlap (overlap) at least a part of the arrangement position in the direction along the axis A. Further, the vibration reduction mechanism 47 is disposed outside the output gear 23 in the radial direction centered on the axis A. Further, the vibration reduction mechanism 47 and the output gear 23 are partially overlapped in the direction along the axis A. The axis A and the 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 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 around the axis 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 axis 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 casing 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 casing 13, or the lubricating oil in the second storage chamber 18 moves to the first storage chamber 17. It can prevent leakage. 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 axis 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.

  Next, another configuration example of the weight 49 of the impact tool 10 will be described with reference to FIG. The component piece 49a is provided with a hole 49c, and the component piece 49b is provided with a hole 49d. The hole 49c penetrates the component piece 49a in the direction along the axis A. The hole 49d penetrates the component piece 49b in the direction along the axis A. In the plane perpendicular to the axis A, the holes 49c and 49d are both arranged on the same circumference and arranged in the same phase. That is, the hole 49c and the hole 49d are connected. The striking tool 10 shown in FIG. 9 is the same as the striking tool 10 shown in FIG. 1 except for the weight 49.

  In the striking tool 10 shown in FIG. 9, a part of the air sucked by the fan 27 passes through the holes 49c and 49d of the weight 49 and goes to the overhanging portion 16c. That is, the holes 49c and 49d of the weight 49 serve to smooth the air flow.

  Here, the correspondence between the configuration described in the present embodiment and the configuration of the present invention will be described. The piston 41 corresponds to the operating member of the present invention, and the center line C corresponds to the center line of the present invention. The output gear 23 corresponds to the first gear of the present invention, the gear 32 corresponds to the second gear of the present invention, the shaft hole 53 corresponds to the hole of the present invention, and the inner cylinder portion 16b corresponds to the present invention. This corresponds to the cylindrical portion. In addition, since the axis A and the center lines B and C are all parallel, the direction along the axis A is the same as the direction along the center line B or the center line C, and the direction along the center line B is The direction along the center line C or the axis A is the same, and the direction along the center line C is the same as the direction along the center line B or the axis A.

  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, 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 air guide path provided in the weight includes notches, grooves and the like in addition to holes. Further, the impact tool can be used in any state of two centerlines and axes along the vertical direction, along the horizontal direction, or between the horizontal and vertical directions. it can. Furthermore, the reference for analyzing the vibration of the casing can use the center of gravity of the impact tool instead of the center of gravity of the casing. The center of gravity of the impact tool is the center of the total mass of the mass of the casing and the mass of the parts, mechanisms, elements, etc. provided in the casing. Furthermore, the striking tool may have a structure in which a battery for supplying electric power to the electric motor is housed in the casing, or a structure in which the battery is attached to the casing in a cassette structure. The hole provided in the vibration reduction mechanism 47 may be a recess.

DESCRIPTION OF SYMBOLS 11 Electric motor 12 Tip tool 13 Casing 16b Inner cylinder part 21 Output shaft 22 Coil 23 Output gear 24 Bearing 29 Intermediate shaft 31 Gear 45 Motion conversion mechanism 47 Vibration reduction mechanism 48 Support member 49 Weight 53 Shaft hole A Axis line C Center line

Claims (6)

A tip tool supported by the casing; an operating member provided in the casing so as to be capable of reciprocating; and generating a striking force transmitted to the tip tool; and provided in the casing and having an output shaft. An electric motor, a motion conversion mechanism that is provided in the casing, 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 casing and has the output shaft A striking tool comprising a bearing to be supported and a vibration reduction mechanism that is movably provided in the casing and that reduces vibration of the casing,
The impact tool according to claim 1, wherein the bearing and the vibration reduction mechanism are arranged so as to overlap at least partially in a direction along a center line of the operation member.   The vibration reduction mechanism includes a support member fixed to the casing in a cantilever state so as to be swingable in a direction along the center line, and a weight attached to a free end of the support member. The impact tool according to claim 1. The electric motor has a coil that forms a rotating magnetic field when energized,
The motion conversion mechanism is disposed in parallel with the center line and has a rotatable power transmission shaft,
A first gear provided on the output shaft and a second gear provided on the power transmission shaft are meshed;
The vibration reducing mechanism is disposed between the first gear and the coil in a direction along the center line;
The impact tool according to claim 2, wherein the vibration reduction mechanism has a hole or a recess that penetrates in a direction along the center line, and the output shaft is inserted into the hole or the recess.   The casing has a cylindrical portion formed so as to surround the axis of the output shaft, the output shaft is inserted into the cylindrical portion, and the bearing is attached to an inner peripheral surface of the cylindrical portion, and The impact tool according to claim 3, wherein the output shaft is supported, and the cylindrical portion is inserted into the hole.   The impact tool according to claim 2, wherein the weight has a wide shape on the opposite side of the electric motor with the support member as a center. An intermediate shaft that transmits the power of the output shaft to the tip tool;
6. The impact tool according to claim 5, wherein the weight is disposed on the side opposite to the intermediate shaft with the output shaft therebetween.

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