JP2015047661A - Impact tool - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an impact tool capable of changing striking force easily and stably only by operation of an operation part.SOLUTION: An impact tool 10 comprises: a tool body 13 to which a tip end tool 12 is attached, the tip end tool 12 receives striking force; a motion conversion part 45 which is stored in the tool body 13, and converts rotation motion of an electric motor 11 into reciprocating motion of a piston 41 along an axial direction of the tool body 13; and an impact mechanism part 60 facing the piston 41 while sandwiching an air chamber 43 therebetween, and having a striking tool 42 for applying striking force to the tip end tool 12 by compression force of the air chamber 43. The volume of the air chamber 43 can be varied.

Description

  The present invention relates to an impact tool, and more particularly to an impact tool provided with an impact mechanism portion and a rotation transmission mechanism portion.

  As described in Patent Document 1, the conventional striking tool selects the rotation and striking mode, the rotation only mode, the striking only mode, etc., and the operation mode switching that can be transmitted to the tip tool according to the purpose of use. Equipment. This operation mode switching device transmits the rotational force of the motor to the intermediate shaft through the pinion and the first gear, and constantly transmits the rotational force to the second gear that meshes with the second pinion on the intermediate shaft. The rotational force was transmitted to the tip tool.

  On the other hand, the rotational force of the motor transmitted to the intermediate shaft is obtained by the engagement of the sleeve that is spline-engaged with the intermediate shaft and the motion conversion member that is loosely fitted on the intermediate shaft. Transmission to the motion converting member, reciprocating of the piston, and a striking force is generated in the tip tool by using pressure generated by compressing an air chamber formed by the piston and the striking element.

Japanese Patent No. 3695392

  However, in the hitting tool, when the work material is a brittle material such as a tile or brick that is easily broken, the hitting force is weakened by finely adjusting the rotation speed using the shift control of the trigger. . When the rotational speed of the motor is adjusted in this way, the rotational speed of the tip tool becomes slower in accordance with the adjustment of the striking force. In addition, the fine adjustment method at that time is a method in which an unstable trigger pull is finely adjusted, so it is necessary to maintain the trigger pull even during work, which is very troublesome. .

  The present invention has been made in consideration of the above circumstances, and the object of the present invention is not to adjust by an unstable trigger pulling force, but to apply the striking force in a simple and stable state only by operating the operation unit. It is to provide an impact tool that can be changed.

  The present invention provides a tool main body on which a tip tool to which a striking force is applied and a motion conversion that is accommodated in the tool main body and converts a rotary motion of an electric motor into a reciprocating motion of a piston along the axial direction of the tool main body. And a striking mechanism having a striking element facing the piston with an air chamber sandwiched between them and applying a striking force to the tip tool by the compression force of the air chamber, and provided on the tool body and operable from the outside A striking tool, wherein the volume of the air chamber is variable by the operation of the operation unit.

  It is preferable that the operation unit is capable of switching on / off of hammering transmission or rotation transmission to the tip tool.

  It is preferable that the motion conversion unit is movable in the axial direction of the tool body in order to change the volume of the air chamber.

  It is preferable that a spring for biasing the motion conversion unit toward the tip tool is provided between the motion conversion unit and the tool body.

  It is preferable that the operation unit changes a striking force by operating a position of the motion conversion unit against an urging force of the spring.

  It is preferable that a connection member for connecting the operation unit and the motion conversion unit is provided, and the connection member moves the motion conversion unit according to the position of the operation unit.

  It is preferable that the operation unit is provided with an operation unit that changes a striking force by operating a position of the motion conversion unit against an urging force of the spring.

  It is preferable that an intermediate element is provided between the tip tool and the striker, and the intermediate element is movable and adjustable in the axial direction of the tool body by an external operation to change the volume of the air chamber. .

  According to the present invention, it is possible to provide a striking tool capable of easily and stably changing the striking force only by operating the operation unit, not by an unstable trigger pulling adjustment.

It is a side view which shows the impact tool which is the 1st Embodiment of this invention. It is principal part sectional drawing which shows schematically the impact tool of normal impact mode. It is principal part sectional drawing which shows schematically the impact tool of weak impact mode. It is principal part sectional drawing which shows the impact tool of rotation mode. It is a side view which shows the normal impact mode of the impact tool which is the 2nd Embodiment of this invention. It is a side view which shows the weak impact mode of the impact tool which is the 2nd Embodiment of this invention. It is a side view which shows an example of the impact tool which is the 3rd Embodiment of this invention. It is principal part sectional drawing which shows schematically the impact tool of normal impact mode. It is principal part sectional drawing which shows schematically the impact tool of weak impact mode. It is principal part sectional drawing which shows roughly the rotation angle of the intermediate shaft in the normal hit | damage mode, and the positional relationship of a piston. It is principal part sectional drawing which shows schematically the relationship between the rotation angle of the intermediate shaft in a weak impact mode, and a piston.

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

  As shown in FIGS. 1 to 4 showing an example of a striking tool, the striking tool 10 is, for example, a hammer drill. The impact tool 10 in the illustrated example has a function of applying a rotational force to the tip tool 12 by the electric motor 11 and a function of selectively applying an axial impact force to the tip tool 12 in addition to this rotation function. ing. The impact tool 10 is provided on the tool main body 13, and a tip conversion tool 45 that converts the rotation of the electric motor 11 into a reciprocating motion in the axial direction of the tool main body 13 and a reciprocating motion converted by the motion converting portion 45. And a striking mechanism 60 for imparting striking force to the head.

  The tool body 13 of the impact tool 10 includes 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 impact tool 10 grasps the hand.

  An opening end 14c of the body portion 14a opposite to the handle portion 14b is connected to one opening end of the gear cover 15, and the housing 14 and the gear cover 15 are connected by a fastening member. The fastening member is not shown for convenience.

  The gear cover 15 is configured in 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 has a stator (not shown) fixed to the housing 14 and a rotor 20 that is rotatably provided. The rotor 20 is rotatable about the first center line A, and the stator is disposed outside the rotor 20 in the radial direction centered on the first center line A. The first center line A is arranged along the horizontal direction in FIG. 2 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 first center line A. The overhanging portion 16c extends in the radial direction about the first center line 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 (not shown) 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 the two bearings 24 so as to be rotatable about the first center line A. In this way, different bearings are arranged in the direction along the first center line 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 that is a power switch, 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, 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 and a guide wall 27b surrounding the outer peripheral side of the impeller 27a.

  The guide wall 27b is provided between the stator and the inner cover 16 in a direction along the first center line A that is an axis. 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 centering on the first center line A.

  Further, a vent hole 28 that communicates the inside and the outside of the tool main body 13 is provided at a joint portion between the housing 14 and the gear cover 15 on the outer peripheral side of the impeller 27a. 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 a and 30 b are coaxially provided in the second storage chamber 18. The intermediate shaft 29 is supported by two bearings 30a and 30b so as to be rotatable about the second center line B. The two bearings 30 a and 30 b 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 the 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 30a and 30b 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 third 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 and the second gear 32 are engaged with each other. 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 housing 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 62 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 a 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 from the first center line A. Is also positioned below. The first center line A that is an axis, the second center line B that is a center line, 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, the small diameter cylindrical portion 35 is provided with a holding hole 35a penetrating in the radial direction, and a steel 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 exposed to the outside of the cylindrical portion 37.

  The end cover 40 is configured to rotate integrally with the cylinder 33. The end cover 40 has a pressing member 40a that prevents the steel ball 55 from falling off the holding hole 35a. A part of the steel ball 55 held in the holding hole 35a is disposed in the groove 12a. That is, the steel 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 steel ball 55. That is, the torque of the cylinder 33 is transmitted to the tip tool 12 via the steel 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 steel ball 55 comes out of the holding hole 35a, so that the tip tool 12 can be replaced.

  A piston 41 as an operation member 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. In order to enable the striking movement of the striker, the cylindrical portion 41a and the large diameter cylindrical portion 34 are provided with vent holes 41c and 34a penetrating in the radial direction, and the striker 42 is provided in the cylindrical portion 41a. It is inserted so as to be slidable in the axial direction. The striker 42 is movable in the direction along the third center line C with respect to the piston 41, and an air chamber 43 is formed between the striker 42 and the bottom 41b in the cylindrical portion 41a.

  The volume of the air 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 cylindrical portion 41 a of 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 due to the pressure increase in the air 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 converting portion 45 that constitutes a striking mechanism portion 60 that generates a striking motion by converting the rotational motion of the intermediate shaft 29 into the reciprocating motion of the piston 41. The motion conversion unit 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 second center line B.

  Furthermore, a clutch 46 is provided in the second storage chamber 18. The clutch 46 is a mechanism for connecting and disconnecting the power transmission path between the inner ring 45a and the intermediate shaft 29. The clutch 46 rotates integrally with the intermediate shaft 29, is movable in the direction along the second center line B with respect to the intermediate shaft 29, and is urged by the spring 47 in a direction to engage with the inner ring 45 a. Yes. 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 connected. In this state, rotation is transmitted from the intermediate shaft 29 to the motion conversion unit 45 via the clutch 46, so that a striking force and a rotational force can be applied to the tip tool 12.

  On the other hand, when the clutch 46 moves toward the right side along the second center line B against the urging force of the spring 47 and stops as shown in FIG. 4, the intermediate shaft 29 and the inner ring 45a The power transmission path between them is interrupted. That is, the clutch 46 is released. In this state, since rotation is not transmitted to the motion conversion unit 45, reciprocation cannot be performed, and only the rotational force can be applied to the tip tool 12.

  On the other hand, the volume of the air chamber 43 formed by the piston 41 and the striking element 42 provided in the motion converting portion 45 is variable in order to make it possible to adjust the striking force that has been constant in the past. In order to change the volume of the air chamber 43, the motion converter 45 can be moved in the axial direction of the tool body 13 by an external operation. That is, the inner ring 45a of the motion converting unit 45 is loosely fitted to the intermediate shaft 29 and is slidable within a predetermined range in the axial direction of the intermediate shaft 29. Between the first gear 31 in the main body 13, a spring 48, which is an elastic member that urges the inner ring 45 a of the motion conversion unit 45 toward the tip tool 12, is provided. Further, the tool body 13 is provided with an operation portion 49 including a switching lever for changing the striking force by operating the position of the inner ring 45a of the motion converting portion 45 against the biasing force of the spring 48.

  The operation portion 49 is provided at the lower portion of the tool body 13 so as to be rotatable about a vertical axis, and an operation shaft 51 that engages with the annular groove 50 on the outer periphery of the clutch 46 at an eccentric position at the upper end portion of the operation portion 49. Is provided. As shown in FIG. 4, the clutch 46 is moved to the right along the intermediate shaft 29 by the rotation operation of the operation portion 49 to release the engagement with the inner ring 45 a, and the clutch 46 is As shown in FIG. 2, the second position moved to the left and engaged with the inner ring 45a (normal hitting, which is rotation and strong hitting), and the clutch 46 resists the biasing force of the spring 48 as shown in FIG. Further, it is possible to select any one of the third positions (rotation and weak impact) in which the inner ring 45a is brought into contact with the end portion of the first gear 31 by further moving to the left. In other words, in the present embodiment, the operation portion 49 can adjust the strength of the striking force and can switch on / off the striking transmission to the tip tool 12. When the operation part 49 is moved to the first position, one end of the inner ring 45a on the side opposite to the spring 48 comes into contact with the enlarged diameter part of the intermediate shaft 29 and further movement is prevented. In other words, the intermediate shaft 29 has a diameter-enlarged portion that is a contact portion that defines a rightward movement range of the motion converting portion 45.

  The operation unit 49 is provided with a notch mechanism 61 for positioning and holding at each of the first position to the third position. The notch mechanism 61 includes a notch member 64 that is urged radially outward via a spring 62 inside a circular operation portion 49, for example, and a plurality of recesses 63 corresponding to each position are formed on the peripheral surface, and a tool A pin 65 is provided on the main body 13 and selectively engaged with any one of the recesses 63 of the notch member 64 corresponding to each position.

  Next, the operation of the impact tool 10 having the above configuration will be described.

[Rotation and blow mode (normal blow)]
The case of the normal hit mode will be described with reference to FIG. 10A shows the case where the rotation position of the intermediate shaft 29 is 0 degree, FIG. 10B shows the case where it is 180 degrees, and FIG. 10C shows the case where it is 270 degrees.

  When the operation unit 49 is operated to the normal hitting position, the inner ring 45a of the motion converting unit 45 approaches the first gear 31 side, and the inner ring 45a and the clutch 46 are engaged. In this state, the rotational force of the electric motor 11 is transmitted to the clutch 46 via the second gear 32 of the intermediate shaft 29, and further transmitted from the clutch 46 to the inner ring 45a of the motion conversion unit 45, causing the piston 41 to reciprocate. As a result, by using the pressure generated by compressing the air chamber 43 formed by the piston 41 and the striker 42, the striker 42 is caused to collide with the intermediate element 44 to apply a strike force to the tip tool 12. it can.

  On the other hand, the movement converting unit 45 is biased toward the tip tool 12 by a spring 48 disposed at the rear end (on the electric motor 11 side), and the position thereof is determined. Therefore, the rotation of the electric motor 11 is transmitted from the second gear 32 of the intermediate shaft 29 to the tip tool 12 through the third gear 36 and the large diameter cylindrical portion 34 and the small diameter cylindrical portion 35 of the cylinder 33. Thereby, the rotation and impact mode which transmits rotational force and impact force to the tip tool 12 can be obtained.

[Rotation and impact mode (weak impact)]
The case of the weak hit mode will be described with reference to FIG. 11A shows a case where the rotational position of the intermediate shaft 29 is 0 degree, FIG. 11B shows a case where it is 180 degrees, and FIG. 11C shows a case where it is 270 degrees.

  From the state of the rotation and impact mode (normal impact), the motion conversion unit 45 is operated to move forward together with the clutch 46 together with the clutch 46 by the operation unit 49. Thereby, since the piston 41 approaches the intermediate element 44, the moving stroke of the striker 42 becomes small, and the volume of the air chamber 43 also decreases. That is, the air chamber 43 is determined by the position of the motion conversion unit 45 that has moved on the intermediate shaft 29. As a result, the pressure due to the reciprocating motion of the piston 41 is reduced, so that the impact force is reduced, and the weak impact mode of the rotation and impact modes can be obtained. Therefore, it is possible to reduce the striking force while maintaining the rotation speed of the intermediate shaft 29, that is, the rotation speed of the tip tool, and it is possible to make a hole quickly and without breaking a delicate work material such as a tile. it can. In addition, it is possible to easily and stably change the hitting force to weak hitting only by operating the operation unit 49, not by the adjustment by the pulling margin of the unstable trigger 26.

[Rotation only mode]
In FIG. 4, the clutch 46 is moved away from the motion conversion unit 45 by the operation unit 49 to release the engaged state from the above-described rotation and hitting mode (normal hitting) state. As a result, the rotation of the intermediate shaft 29 is not transmitted to the motion conversion unit 45, so that the striking motion is eliminated, and the rotation only mode in which only the rotational force is transmitted to the tip tool 12 can be obtained.

  In the above-described embodiment, the hitting tool only needs to be capable of giving hitting force to at least the tip tool, and the hitting tool is configured to be able to switch between three types: hammer-only mode, drill-only mode, and hammer-drill mode. May be. The hammer dedicated mode is a mode in which only the impact force is applied to the tool, the drill dedicated mode is a mode in which only the rotational force is applied to the tool, and the hammer drill mode is a mode in which the impact force and rotational force are applied to the tip tool. The tip tool may be a driver bit for tightening the screw member.

  5 and 6 are side sectional views showing a second example of the impact tool according to the embodiment of the present invention. The striking tool according to the second embodiment has the same basic configuration as that of the first embodiment. In the second embodiment, a slide plate 70 that is a moving member that moves back and forth in accordance with the rotational position of the operation unit 49 is provided. The rear end of the slide plate 70 is engaged with the motion conversion unit 45. The slide plate 70 corresponds to a connection member that connects the operation unit 49 and the motion conversion unit 45.

  A plate spring 71 is provided on the front end side of the slide plate 70. The slide plate 70 is urged rearward (motor side) by the plate spring 71.

  By operating the operation unit 49, the slide plate 70 can be moved to the first position on the rear end side and the second position on the front end side. As shown in FIG. 5, when the slide plate 70 is in the first position, the motion conversion unit 45 is located on the rear end side, and the normal hit mode is set. As shown in FIG. 6, when the slide plate 70 is in the second position, the motion conversion unit 45 is located on the front end side and enters the weak hit mode. Thus, by providing the slide plate 70 which is a moving member that moves by moving the motion conversion unit 45 forward, the slide plate 70 can receive a reaction force to the rear side applied to the motion conversion unit 45 at the time of striking. . Further, when the operation unit 49 is further rotated, the pin 51 is further moved to the front end portion, so that the engagement between the motion conversion unit 45 and the clutch 46 can be released and the drill mode can be set.

  FIG. 7 is a side sectional view showing a third example of the impact tool according to the embodiment of the present invention. Whereas the impact tool of the above embodiment includes a horizontal electric motor, the impact tool 10 of the embodiment of FIG. 7 includes the vertical electric motor 11 and the motion conversion portion 45 in front of the handle portion 14b. It is provided, but it does not have a drill mode that gives rotational force to the tip tool. The motion conversion unit 45 includes an intermediate shaft 29 having a first shaft 31 having a first gear 31 that meshes with an output gear 23 provided at an upper end portion of the output shaft 21 of the electric motor 11, and an upper end portion of the intermediate shaft 29. It is provided with a motion conversion unit 45 formed of, for example, a crankshaft, which is provided in the center and converts the rotational motion to the reciprocating motion of the piston 41. The handle portion 14b is provided with a tool main body 13 formed of a cylindrical casing extending forward, and a cylinder 33 is inserted into the tool main body 13.

  In the cylinder 33, the piston 41 and the striker 42 are fitted so as to be able to reciprocate with the air chamber 43 interposed therebetween. An end cover 40 is provided at the tip of the tool body 13 via a medium diameter cylindrical portion 73 and a small diameter cylindrical portion 35. The small diameter cylindrical portion 35 supports the intermediate element 44 and the tip tool 12 so as to be able to reciprocate.

  In order to change the volume of the air chamber 43, the intermediate element 44 can be moved in the axial direction of the tool body 13 by an external operation. The intermediate element 44 has a head portion 44a slidably fitted in the cylinder, and a shaft portion 44b extending from the head portion 44a toward the striker 42 and having a smaller outer diameter than the head portion 44a. Yes. A slide member 70 is slidably provided on the outer peripheral surface of the shaft portion 44b of the intermediate element 44, and a damper 71 and a washer 72 are mounted between the slide member 70 and the head portion 44a. A small-diameter cylindrical portion 35 is provided at the distal end of the tool body 13 via an intermediate-diameter cylindrical portion 73, and a spring 74 that biases the slide member 70 rearward between the intermediate-diameter cylindrical portion 73 and the slide member 70. Is installed. In order to change the striking force by operating the position of the intermediate element 44 against the urging force of the spring 74, the tool body 13 is provided with an operation portion 49 including a switching lever.

  The operation portion 49 is provided on the upper portion of the tool body 13 so as to be rotatable about a vertical axis, and an operation shaft that engages with the rear end portion 70 a of the outer periphery of the slide member 70 at an eccentric position at the lower end portion of the operation portion 49. 51 is provided. By rotating the operation portion 49, the intermediate element 44 is moved to the left as shown in FIG. 8 against the urging force of the spring 74 via the slide member 70, and between the striking element 42 and the piston 41. The volume of the air chamber 43 is reduced by moving the meson 44 to the right, which is the direction of the urging force of the spring 74, as shown in FIG. Any one of the second position (weak hit) can be selected. The operation unit 49 is provided with a notch mechanism (not shown) for positioning and holding at each of the first position and the second position.

  According to the striking tool 10 of the present embodiment having the above-described configuration, the striking force can be changed in a stable and simple state only by operating the operation unit 49, not by the adjustment by pulling the unstable trigger 26. The possible impact tool 10 can be obtained.

DESCRIPTION OF SYMBOLS 10 Impact tool 11 Electric motor 12 Tip tool 13 Tool main body 41 Piston 42 Impactor 43 Air chamber 44 Meson 45 Motion conversion part 48 Spring 49 Operation part 60 Impact mechanism part

Claims (7)

A tool body for mounting a tip tool to which a striking force is applied;
A motion converter that is housed in the tool body and converts the rotational motion of the electric motor into a reciprocating motion of a piston along the axial direction of the tool body;
A striking mechanism having a striking element that is opposed to the piston with an air chamber interposed therebetween and applies a striking force to the tip tool by the compression force of the air chamber;
An operation unit provided on the tool body and operable from the outside,
A striking tool in which the volume of the air chamber is variable by operation of the operation unit.   The impact tool according to claim 1, wherein the operation unit is capable of switching on / off of impact transmission or rotation transmission to the tip tool.   The striking tool according to claim 1 or 2, wherein the motion conversion unit is movable in the axial direction of the tool body in order to change the volume of the air chamber.   The impact tool according to claim 3, wherein a spring that urges the motion conversion unit toward the tip tool is provided between the motion conversion unit and the tool body.   The impact tool according to claim 4, wherein the operation unit changes an impact force by operating a position of the motion conversion unit against an urging force of the spring.   The striking tool according to claim 2, wherein a connection member that connects the operation unit and the motion conversion unit is provided, and the connection member moves the motion conversion unit according to a position of the operation unit.   2. An intermediate element is provided between the tip tool and the striker, and the intermediate element is movable in the axial direction of the tool body by an external operation to change the volume of the air chamber. The hitting tool described.

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