JP2015074075A - Impact tool - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an impact tool which can adjust an impact force of a tip tool by a simple operation.SOLUTION: In impact tool includes: a housing 2; a motor 3 disposed in the housing 2; a reciprocating-motion conversion part 43 which is disposed in the housing 2 and converts rotation of the motor 3 disposed in the housing 2 into a reciprocating-motion; a cylinder 7 supported in the housing 2; a piston 8 which is connected to the reciprocating-motion conversion part 43 and is so disposed in the cylinder 7 as to be capable of reciprocating in an axial direction of the cylinder 7; and a striking element 91 which is disposed in the cylinder 7 and defines an air chamber 9a between itself and the piston 8. In the impact tool, the cylinder 7 which is so supported as to be movable in an axial direction and has a configuration such that a moving range of the striking element 91 in an axial direction during striking is changed according to a position in the axial direction of the cylinder 7, and the housing 2 is provided with a cylinder moving mechanism which moves the cylinder 7 in the axial direction.

Description

  The present invention relates to an impact tool.

  Conventionally, an impact is provided with an intermediate shaft that is rotated by the rotational force of a motor, a rotation transmission mechanism and a reciprocating motion conversion mechanism provided on the intermediate shaft, and the operation mode of the tip tool can be switched according to the purpose of use. Tools are known. For example, as the operation mode of the tip tool, there is a “rotation impact mode” in which the rotational force of the intermediate shaft is transmitted to the rotation transmission mechanism and the reciprocating motion conversion mechanism, and the rotation force and impact force are generated to the tip tool. “Rotation mode” that transmits the rotational force of the shaft and generates only the rotational force to the tip tool, and “Blow mode” that transmits the rotational force of the intermediate shaft only to the reciprocating motion conversion mechanism and generates only the impact force to the tip tool Japanese Patent Application Laid-Open No. H10-228688 discloses a striking tool including

Japanese Patent Laid-Open No. 2003-71745

  With conventional hitting tools, the hitting force is constant in any operation mode that generates hitting force on the tip tool, so when drilling a brittle material, the hitting force is too strong and the work material is cracked. There was a problem such as. On the other hand, when drilling a hard material, if the impact force is weak, there is a problem that the drilling speed is lowered and the working efficiency is lowered. In addition, when the impact force is adjusted by changing the motor speed, the rotational force and impact force of the tip tool change simultaneously in the rotational impact mode, resulting in insufficient rotational force and excessive impact force. There is a problem that it is difficult to obtain an appropriate rotational force and striking force according to the purpose.

  Then, an object of this invention is to provide the impact tool which can change the impact force of a front-end tool by simple operation.

  In order to solve the above-described problems, the present invention provides a housing, a motor disposed in the housing, a reciprocating motion conversion unit disposed in the housing for converting the rotation of the motor into a reciprocating motion, and supported by the housing. A cylinder connected to the reciprocating motion converter, a piston disposed in the cylinder so as to be capable of reciprocating in the axial direction of the cylinder, and an air chamber disposed between the piston and the piston. The cylinder is supported by the housing so as to be movable in the axial direction, and the cylinder during the striking operation is responsive to the axial position of the cylinder. Provided is a striking tool characterized in that the range of movement of the striker in the axial direction changes, and the housing is provided with a cylinder moving mechanism for moving the cylinder in the axial direction. .

  According to such a configuration, since the cylinder can be moved in the axial direction, the volume of the air chamber defined between the striker disposed in the cylinder and the piston can be changed. Since the volume of the air chamber is one of the elements that determine the impact force of the impact tool, the impact force can be adjusted by moving the cylinder in the axial direction and changing the volume of the air chamber. For this reason, when drilling or the like in a fragile work material, the volume of the air chamber is reduced to reduce the impact force, while in the case of a hard material, the air chamber is maintained while maintaining the rotational force of the tip tool. It is possible to achieve a striking force suitable for the purpose of use such as increasing the striking force to increase the striking force, and the work width is widened and work efficiency is improved.

  In the above configuration, the cylinder is supported by the housing so as to be rotatable about its own axis, and transmits a rotation of the motor to the cylinder so as to rotate the cylinder about the axis. It is preferable to have.

  According to such a configuration, an impact tool having an impact force and a rotational force is realized. Further, the striking force can be adjusted without changing the rotational speed of the cylinder.

  Further, the cylinder has a tip portion capable of holding a tip tool, the cylinder moving mechanism is positioned on the tip portion side, and the cylinder moving mechanism is rotated, so that the cylinder moves in the axial direction. It is preferable to move.

  According to such a configuration, the striking force can be changed simply by rotating the cylinder moving mechanism. Therefore, the striking force suitable for the purpose of use can be realized easily and work efficiency is further improved. .

  The cylinder moving mechanism is positioned on the inner peripheral surface side of the cylindrical member, which is fixed to the housing so as not to move and rotate and has a first threaded portion formed on the inner peripheral surface thereof. A holder that rotatably supports the cylinder, is movable in the axial direction together with the cylinder, and has a second threaded portion that engages with the first threaded portion on an outer peripheral surface; and the holder And a grip for rotating the holder by a rotating operation.

  According to such a configuration, since the first screw portion formed on the cylindrical member and the second screw portion formed on the holder are screwed together, the impact received by the cylinder and the holder at the time of impact is first. Can be received by the entire screwed portion of the screw portion and the second screw portion. For this reason, an intensity | strength rises with respect to the impact at the time of impact, and the lifetime of an impact tool becomes long. Moreover, since the cylinder and the holder can be moved in the axial direction only by a simple and simple operation of rotating the grip, the working efficiency is further improved.

  Further, a tool holding means for detachably holding the tip tool on the tip portion and an urging means for maintaining the state where the tool holding means holds the tip tool are provided, and the grip is It is provided so as to be able to rotate together with the holder and to be movable in the axial direction with respect to the holder, and to be engageable with the cylindrical member. The grip is urged in a direction toward the position where the engagement is maintained, and the grip is moved against the urging force of the urging means to disengage the grip from the cylindrical member. Is preferred.

  According to such a configuration, the urging means is used as a tool holding means and also as a means for urging the grip to the cylindrical member. Therefore, it is necessary to provide another member as a means for urging the grip. In addition, the number of parts can be reduced. For this reason, cost can be suppressed in the manufacturing process of the impact tool.

  The rotation transmission mechanism includes a drive pinion that rotates by rotation of the motor and has a predetermined length in the axial direction, and a driven gear that meshes with the drive pinion and can rotate integrally with the cylinder. The predetermined length of the drive pinion is preferably a length that can maintain meshing with the driven gear even when the cylinder moves in the axial direction.

  According to such a configuration, it is possible to prevent the engagement of the drive pinion and the driven gear from being released due to the movement of the cylinder in the axial direction.

  The cylinder is provided with a flange portion having a contact surface, and the driven gear is provided with a sliding surface that contacts the corresponding contact surface and transmits the rotation of the driven gear to the cylinder. It is preferable that a slip clutch mechanism is constituted by the surface and the corresponding contact surface, and the driven gear is biased in a direction in which the slide surface comes into contact with the corresponding contact surface.

  According to such a configuration, when an excessive load is applied to the cylinder holding the end tool, the transmission of rotation from the driven gear to the cylinder is interrupted by the slip clutch, thereby suppressing an excessive load on the motor or the like. can do.

  Moreover, it is preferable that a trigger for controlling the rotation speed of the motor is provided according to the pulling amount.

  According to such a configuration, the striking force can be changed by the pulling amount of the trigger in addition to changing the striking force by moving the cylinder in the axial direction, so that a wider striking force adjustment is performed. be able to. For this reason, the user can obtain a striking force more suitable for the work purpose, and the workability and convenience are improved.

  The present invention further includes a housing, a motor disposed in the housing, a tip portion movably supported by the housing and holding a tip tool, and an enlarged cylindrical portion having an inner diameter larger than the tip portion. A cylinder part, a cylinder moving mechanism for moving the cylinder part in the axial direction of the cylinder part, a reciprocating motion converting part arranged in the housing for converting the rotation of the motor into a reciprocating motion, and the reciprocating motion conversion A piston disposed in the enlarged cylindrical portion so as to be capable of reciprocating in the axial direction, and a striker disposed in the enlarged cylindrical portion and defining an air chamber between the piston and the piston. And an intermediate element that is located in front of the striker and transmits a striking force to the tip tool, and an intermediate support member that is provided at a front portion of the enlarged-diameter cylindrical portion and has an abutting portion that comes into contact with the intermediate element, Stroke characterized by having To provide a tool.

  According to such a configuration, since the cylinder portion can be moved in the axial direction, the volume of the air chamber defined between the striking element and the piston arranged in the enlarged diameter cylindrical portion can be changed. it can. Since the volume of the air chamber is one of the elements that determine the striking force of the striking tool, the striking force can be adjusted by moving the cylinder portion in the axial direction and changing the volume of the air chamber. For this reason, when drilling or the like in a fragile work material, the volume of the air chamber is reduced to reduce the impact force, while in the case of a hard material, the air chamber is maintained while maintaining the rotational force of the tip tool. It is possible to achieve a striking force suitable for the purpose of use such as increasing the striking force to increase the striking force, and the work width is widened and work efficiency is improved.

  According to the striking tool of the present invention, it is possible to provide a striking tool that realizes the striking force of the tip tool suitable for the purpose of use and improves workability and convenience.

It is a partial cross section side view which shows the impact tool by embodiment of this invention. It is an enlarged view of the partial cross section side view which shows the position of the normal cylinder of the impact tool by embodiment of this invention. It is an enlarged view of a partial cross-sectional side view showing the position of the cylinder moved backward by the impact tool according to the embodiment of the present invention. It is an enlarged view of the partial cross section side view which shows the state which pulled out the grip of the impact tool by embodiment of this invention. It is a block diagram which shows control of the impact tool by embodiment of this invention.

  A striking tool according to an embodiment of the present invention will be described with reference to FIGS.

  As shown in FIG. 1, a hammer drill 1 which is a striking tool according to an embodiment of the present invention includes a housing 2, a motor 3, a drive transmission unit 4, a cylinder 7, a piston 8, a striking mechanism unit 9, and a grip. 14 and is used in a state where a tip tool (not shown) is attached to the output unit 10. The operation mode includes a rotation hitting mode in which the tip tool rotates and hits and a rotation mode in which only the rotation is performed. In the following description, the direction in which the output unit 10 is provided for the motor 3 is defined as the front direction, and the reverse direction is defined as the rear direction. The direction in which the piston 8 is provided with respect to the drive transmission unit 4 is defined as an upward direction, and the reverse direction is defined as a downward direction. Further, in FIG. 1, the right when the hammer drill 1 is viewed from the rear direction is defined as the right direction, and the reverse direction is defined as the left direction.

  The housing 2 forms an outline of the hammer drill 1, and includes a motor housing 21 and a gear housing 22.

  The motor housing 21 includes a motor housing portion 21A and a handle portion 21B, and is a resin molded product, for example.

  The motor accommodating portion 21A has a substantially cylindrical shape extending in the front-rear direction, and accommodates the motor 3 therein. The motor 3 has a rotating shaft 31 protruding forward from the main body, and the rotating shaft 31 is rotatably supported by a ball bearing 31A supported by the motor housing 21 and a ball bearing 31B supported by the gear housing 22. A pinion gear 33 is provided at the front portion of the rotating shaft 31. A fan 32 is coaxially fixed to the rotating shaft 31.

  The handle portion 21B is a portion that is gripped when the user uses the hammer drill 1, and extends downward from the lower rear side of the motor housing portion 21A. A power cable 21C is attached to the handle portion 21B, and a switch mechanism 21D, a trigger switch 21F, and a forward / reverse switching lever 21G are provided.

  The power cable 21C extends from the lower end of the handle portion 21B and is configured to be electrically connectable to a commercial power source (not shown). The switch mechanism 21D is accommodated in the handle portion 21B and is electrically connected to the motor 3 via the connection line 21E. The trigger switch 21F is provided on the upper front side of the handle portion 21B, and the rotation speed of the motor changes depending on the pulling amount of the trigger switch 21F. The forward / reverse switching lever 21G is provided above the trigger switch 21F, and the rotation direction of a tip tool (not shown) can be selected by operating the forward / reverse switching lever 21G.

  The gear housing 22 has a substantially cylindrical shape extending in the front-rear direction, and is provided in front of the motor housing portion 21A. The gear housing 22 includes a change lever 22A. The gear housing 22 accommodates the drive transmission unit 4, the cylindrical member 5, the holder 6, the cylinder 7, the piston 8, and the striking mechanism unit 9.

  The change lever 22A has a substantially circular shape when viewed from the bottom, is provided below the gear housing 22, and includes an eccentric pin 22B. The eccentric pin 22B protrudes into the gear housing 22 from the upper part of the change lever 22A.

  The drive transmission unit 4 includes an intermediate shaft 41, a sleeve 42, and a reciprocating motion conversion unit 43.

  As shown in FIGS. 2 to 4, the intermediate shaft 41 extends in the front-rear direction substantially parallel to the rotation shaft 31, and is rotatably supported by the ball bearing 41 </ b> C and the ball bearing 41 </ b> D supported by the gear housing 22. Yes. The intermediate shaft 41 includes a second gear 41A and a second pinion 41B.

  The second gear 41 </ b> A is provided at the rear end portion of the intermediate shaft 41 and meshes with the pinion gear 33 of the rotating shaft 31. The rotational force of the rotary shaft 31 is transmitted to the intermediate shaft 41 via the pinion gear 33 and the second gear 41A.

  The second pinion 41B corresponding to the drive pinion is provided from approximately the center in the front-rear direction of the intermediate shaft 41 to the front part, and includes an enlarged diameter part 41E and a ring 41F. The enlarged diameter portion 41E is formed by expanding the front portion of the second pinion 41B, and has a certain length in the front-rear direction. The ring 41F is provided at the rear end portion of the enlarged diameter portion 41E.

  The sleeve 42 has a substantially cylindrical shape extending in the front-rear direction, and is provided on the second pinion 41B of the intermediate shaft 41 so as to be movable by a certain amount in the front-rear direction and not rotatable relative to the intermediate shaft 41. It has a configuration that allows for circulation. An engagement claw 42a that can be engaged with the reciprocating motion converting portion 43 is formed at the rear end portion of the sleeve 42, and a recess portion 42b is formed over the entire outer circumference at the approximate center in the front-rear direction. The eccentric pin 22B of the change lever 22A is located in the recess 42b, and the sleeve 42 moves in the front-rear direction as the eccentric pin 22B moves in the front-rear direction. Further, a spring 4A is provided between the sleeve 42 and the ring 41F, and urges the sleeve 42 rearward.

  The reciprocating motion conversion unit 43 includes a first conversion member 44 and a second conversion member 45.

  The first conversion member 44 includes a substantially spherical cam portion 44A and a substantially cylindrical engaging portion 44B, and is loosely fitted on the intermediate shaft 41 so as to be relatively rotatable with respect to the intermediate shaft 41. . On the surface of the cam portion 44A, a groove 44a intersecting with the intermediate shaft 41 is formed over the entire circumference of the spherical surface. The engaging portion 44B is formed integrally with the cam portion 44A, and extends forward from the front portion of the cam portion 44A. A claw portion 44b that can engage with the engagement claw 42a of the sleeve 42 is formed at the front end portion of the engagement portion 44B. In a state where the first conversion member 44 and the sleeve 42 are engaged, the first conversion member 44 is configured to rotate with the sleeve 42, and the rotational force of the intermediate shaft 41 causes the second pinion 41 </ b> B and the sleeve 42 to rotate. To the reciprocating motion conversion unit 43. On the other hand, in a state where the engagement between the first conversion member 44 and the sleeve 42 is released, the rotational force of the intermediate shaft 41 is not transmitted to the reciprocating motion conversion unit 43.

  The second conversion member 45 includes a ring part 45A and an arm part 45B. The ring portion 45A has a substantially annular shape, and includes a plurality of balls 45C that engage with the grooves 44a of the cam portion 44A, and is attached to the cam portion 44A via the plurality of balls 45C. The arm part 45B protrudes upward from the upper part of the ring part 45A, and is connected to the piston 8. The arm portion 45 </ b> B reciprocates in the front-rear direction as the first conversion member 44 rotates about the axis of the intermediate shaft 41. The arm portion 45B is configured to reciprocate once by the first conversion member 44 rotating once.

  The tubular member 5 has a substantially cylindrical shape extending in the front-rear direction, and is fixed to the front inner peripheral surface of the gear housing 22 so as not to rotate and to move with respect to the gear housing 22. A female screw 5a that is a first screw portion is formed on the inner peripheral surface of the cylindrical member 5, and an engaging claw 5b that can engage with the grip 14 is formed on the front end portion.

  The holder 6 has a substantially cylindrical shape extending in the front-rear direction, and is located on the radially inner side of the cylindrical member 5. The holder 6 is provided with a male screw 6A as a second screw portion, a protruding portion 6B, and a stop paring 6C, and an engagement groove 6a is formed.

  The male screw 6 </ b> A is formed from the rear part of the outer peripheral surface of the holder 6 to substantially the center, and is screwed with the female screw 5 a of the cylindrical member 5. For this reason, the holder 6 can be moved in the front-rear direction with respect to the tubular member 5 by rotating the holder 6. In addition, as long as the cylindrical member 5 and the holder 6 can be relatively moved in the front-rear direction, a connection method other than the screw portion may be used. For example, one of the cylindrical member 5 and the holder 6 may be provided with a vertical groove and a horizontal groove continuous to the vertical groove, and the other may be provided with a protrusion that matches the vertical groove and the horizontal groove. In any connection method, the connecting portion between the cylindrical member 5 and the holder 6 has a plurality of contact portions, and has strength to withstand impacts in the front-rear direction. In this respect, forming both the cylindrical member 5 and the holder 6 in a cylindrical shape is advantageous in achieving both operability and strength.

  The protrusion 6 </ b> B is formed so as to protrude radially inward from the inner peripheral surface of the holder 6. The stopper ring 6C is provided on the inner peripheral surface of the holder 6 and behind the protrusion 6B, and supports the ball bearing 7A so as not to move in the front-rear direction with respect to the holder 6 in cooperation with the protrusion 6B. . The engaging groove 6 a is formed on the outer peripheral surface of the front portion of the holder 6 so as to extend in the front-rear direction, and is engaged with the grip 14. Further, a stopper 6D for preventing the engagement between the grip 14 and the engagement groove 6a is provided at the front portion of the engagement groove 6a.

  The cylinder 7 is positioned above the drive transmission unit 4, has a substantially cylindrical shape extending in parallel with the intermediate shaft 41, and includes a distal end portion 71 and an enlarged diameter cylindrical portion 72. The enlarged diameter cylindrical portion 72 is continuous to the rear of the distal end portion 71 and has a larger outer diameter than the distal end portion 71. Therefore, the front end portion of the enlarged diameter cylindrical portion 72 forms a step portion between the enlarged diameter cylindrical portion 72 and the tip end portion 71. The outer surface of the front end portion of the enlarged diameter cylindrical portion 72 forms a contact surface of a ball bearing 7A described later. Similarly, the enlarged diameter cylindrical portion 72 has an inner diameter larger than that of the distal end portion 71. The inner surface of the front end portion of the enlarged diameter cylindrical portion 72 forms an abutting surface of an intermediate member supporting member 72E described later. The cylinder 7 is rotatable about its own axis with respect to the holder 6 and the gear housing 22 by a ball bearing 7A that abuts the front end portion of the enlarged cylindrical portion 72, a bearing member 7B, and a metal bearing 7C. It is supported by. The distal end portion 71 and the enlarged diameter cylindrical portion 72 of the cylinder 7 are formed of a single member. However, in order to facilitate parts processing and assembly, a plurality of parts may be appropriately combined. Regardless of whether it is a single component or a combination of a plurality of components, a portion having the tip portion 71 and the enlarged diameter cylindrical portion 72 integrally is defined as a cylinder portion. In the following description, the cylinder 7 corresponds to a cylinder part.

  The tip portion 71 is a portion that holds a tip tool (not shown), includes a stopper ring 71A, and has a holding hole 71a. The stopper ring 71 </ b> A is provided substantially in the front-rear direction center of the outer peripheral surface of the tip end portion 71, and sandwiches the ball bearing 7 </ b> A and the bearing member 7 </ b> B in cooperation with the front end portion of the diameter-enlarged cylindrical portion 72. For this reason, the cylinder 7 cannot move in the front-rear direction (axial direction) with respect to the ball bearing 7A and the bearing member 7B, and moves in the front-rear direction together with the holder 6 as the holder 6 moves in the front-rear direction. The holding hole 71a is formed in front of the stopper ring 71A.

  The enlarged diameter cylindrical portion 72 is a portion whose diameter is larger than that of the distal end portion 71 and is formed integrally with the distal end portion 71. The enlarged diameter cylindrical portion 72 includes a flange portion 72A, a cylinder gear 72B, a spring seat 72C, a spring 72D, and an intermediate support member 72E.

  The flange portion 72A is a portion that is radially outwardly expanded from the outer peripheral surface of the enlarged-diameter cylindrical portion 72, and is constituted by a thick portion and a thin portion, and the rear end surface is in contact with the cylinder gear 72B. A contact surface 72F is defined.

  The cylinder gear 72B corresponding to the driven gear is provided to be slidable in the front-rear direction on the outer peripheral surface of the enlarged diameter cylindrical portion 72 and behind the flange portion 72A. The cylinder gear 72B meshes with the enlarged diameter portion 41E of the second pinion 41B. ing. A sliding surface 72G that contacts the contact surface 72F is defined on the surface of the flange portion 72A that faces the contact surface 72F.

  The spring seat 72C is provided behind the cylinder gear 72B, and between the spring seat 72C and the cylinder gear 72B, a spring that urges the cylinder gear 72B forward (direction in which the sliding surface 72G contacts the contact surface 72F). 72D is provided.

  During normal rotation of the hammer drill 1, the cylinder gear 72B is urged to the flange portion 72A by the spring 72D, and the cylinder gear 72B and the cylinder 7 rotate integrally with the contact surface 72F and the sliding surface 72G in contact with each other. The rotation of the shaft 41 is transmitted to the cylinder 7 via the second pinion 41B and the cylinder gear 72B. In this manner, the rotation transmission mechanism that transmits the rotation of the intermediate shaft 41 to the cylinder 7 is configured by the cylinder gear 72B and the second pinion 41B.

  When there is a sudden load change such as an unillustrated tip tool biting into an unillustrated work material, the cylinder gear 72B moves backward against the biasing force of the spring 72D, and the thick portion of the flange portion 72A Since the sliding surface 72G slips with respect to the contact surface 72F over the vehicle, the cylinder gear 72B is idled with respect to the cylinder 7, and it is possible to suppress a sudden load on the motor 3 and the like. . Thus, the slip gear mechanism is constituted by the cylinder gear 72B and the flange portion 72A.

  The meson support member 72E is provided at the front portion inside the enlarged diameter cylindrical portion 72. The meson support member 72E has a substantially cylindrical shape. A striker 91 and an intermediate 92, which will be described later, can be inserted into an opening provided in the center of the intermediate support member 72E. On the striking element 91 side of the opening, an enlarged-diameter portion that receives the convex portion of the striking element 91 and an O-ring are provided. The O-ring is configured to hold the striker 91 in a state where an unillustrated tip tool is not pressed against the work material. An oil seal (O-ring) that can contact the outer periphery of the intermediate element 92 is provided on the intermediate element 92 side of the opening. By having the meson 92 and the oil seal, the impact force can be transmitted to the tip tool while preventing oil leakage between the reciprocating motion conversion unit side and the tip tool side. The meson 92 side of the opening has a portion where the outer (medium 92 side) diameter is increased. Further, the front end portion of the meson support member 72E can come into contact with a contact surface provided on the inner surface of the front end portion of the enlarged diameter cylindrical portion 72. Therefore, the position of the meson support member 72E changes according to the position of the cylinder 7.

  The piston 8 is integrally formed of a cylinder portion 81A, a lid portion 81B, and a connection portion 81C, and is provided in the cylinder 7 so as to be slidable in the front-rear direction. The cylinder portion 81A has a substantially cylindrical shape with a front end opened and a rear end closed by a lid portion 81B. The connection portion 81C is provided to protrude rearward from the rear end surface of the lid portion 81B, and is connected to the arm portion 45B of the reciprocating motion conversion portion 43. The piston 8 reciprocates in the front-rear direction in the cylinder 7 in conjunction with the reciprocating motion of the arm portion 45B.

  The striking mechanism unit 9 is configured by a striking member 91, an air chamber 9 a, and an intermediate 92. The striker 91 has a substantially cylindrical shape, and is provided in the piston 8 so as to be slidable in the front-rear direction. The air chamber 9a is defined by the rear end surface of the striker 91, the inner peripheral surface of the cylinder portion 81A of the piston 8, and the front surface of the lid portion 81B. The intermediate element 92 has a substantially cylindrical shape and is positioned in front of the striker 91. In the cylinder 7, it is supported by the meson support member 72E so as to be slidable by a predetermined amount in the front-rear direction. A tip tool (not shown) is positioned in front of the intermediate element 92. The meson support member 72E side of the meson 92 has a portion that is substantially the same diameter as the inner diameter of the oil seal (O-ring), and an enlarged diameter portion (meson that is larger in diameter than the inner diameter of the oil seal (O-ring)) Abutting portion). The rear end position of the meson 92 is defined by the contact between the enlarged diameter portion of the meson 92 and the meson support member 72E. That is, the position of the meson 92 during the striking operation (a state in which a not-shown tip tool is pressed against the work material) varies depending on the position of the meson support member 72E.

  The output unit 10 is provided in front of the gear housing 22. Inside the output unit 10, there are a holding ball 11 and a ball support member 12 corresponding to a tool holding unit, and a support spring 13 corresponding to a biasing unit. And a grip 14 at the rear end. The holding ball 11 is disposed across the holding hole 71a of the cylinder 7 and the recess formed in the tip tool in a state where the tip tool (not shown) is held by the tip portion 71 of the cylinder 7, Can be moved by a certain amount in the front-rear direction (axial direction) and is not rotatable relative to the cylinder 7. The ball support member 12 is located at the rear portion of the holding ball 11 and supports the holding ball 11. The support spring 13 is provided between the ball support member 12 and the grip 14 positioned behind the ball support member 12, and biases the ball support member 12 forward and biases the grip 14 backward. Yes. When the ball support member 12 is urged forward, the holding ball 11 is disposed across the holding hole 71 a of the cylinder 7 and the recess formed in the tip tool, and holds the tip tool (not shown) in the cylinder 7. doing.

  The grip 14 includes a base portion 14A and a cylindrical portion 14B. The base portion 14A is formed in a substantially annular shape with a certain width in the radial direction of the cylinder 7, and has a cylindrical member engaging claw 14a and a holder engaging claw 14b. Further, a cylindrical portion 14B extends forward from the outer peripheral portion of the base portion 14A.

  The tubular member engaging claw 14 a is formed on the inner peripheral portion of the rear end surface of the base portion 14 </ b> A, and can be engaged with the engaging claw 5 b of the tubular member 5. The holder engaging claw 14b is formed in the inner peripheral portion of the base portion 14A and in front of the cylindrical member engaging claw 14a, and is spline-engaged with the engaging groove 6a of the holder 6. For this reason, the grip 14 can rotate together with the holder 6 and can move in the front-rear direction (the axial direction of the cylinder 7) with respect to the holder 6.

  Usually, since the grip 14 is urged rearward by the support spring 13, the cylindrical member engaging claw 14 a and the engaging claw 5 b are in an engaged state, and the grip 14 cannot rotate with respect to the cylindrical member 5. It is. On the other hand, when the grip 14 is moved forward against the urging force of the support spring 13, the engagement state between the cylindrical member engaging claw 14 a and the engaging claw 5 b is released, and the grip 14 is connected to the cylindrical member 5. And can rotate together with the holder 6.

  As shown in FIG. 4, the user pulls the grip 14 forward against the urging force of the support spring 13 and rotates the grip 14 in the direction of arrow A, whereby the grip 14 and the holder 6 are rotated. The holder 6 moves in the direction of arrow B with respect to the cylindrical member 5, that is, forward. As the holder 6 moves forward, the cylinder 7 that moves in the front-rear direction together with the holder 6 also moves forward. When the grip 14 is rotated in the direction opposite to the direction of the arrow A, the cylinder 7 moves in the direction opposite to the direction of the arrow B, that is, backward. In this way, the grip 14, the cylindrical member 5, and the holder 6 constitute a cylinder moving mechanism. By rotating the grip 14, the cylinder 7 is moved relative to the cylindrical member 5 and the gear housing 22. It can be moved in the front-rear direction (the axial direction of the cylinder 7).

  As the cylinder 7 moves in the front-rear direction with respect to the cylindrical member 5 and the gear housing 22, the meson support member 72 </ b> E, the meson 92, the striker 91, and the cylinder gear 72 </ b> B provided in the cylinder 7 also move in the front-rear direction together with the cylinder 7. Moving. That is, according to the position of the cylinder 7 in the axial direction, the movement range in the axial direction of the striker 91 during the hitting operation is changed. On the other hand, even when the cylinder 7 moves in the front-rear direction with respect to the cylindrical member 5 and the gear housing 22, the lid portion 81 </ b> B of the piston 8 does not move with respect to the cylindrical member 5 and the gear housing 22. For this reason, the distance between the lid portion 81B of the piston 8 and the rear end surface of the striker 91 changes as the cylinder 7 moves, and the volume of the air chamber 9a also changes in proportion to the distance. Further, the length of the enlarged diameter portion 41E in the front-rear direction is set to the cylinder 7 in order to prevent the engagement between the enlarged diameter portion 41E of the second pinion 41B and the cylinder gear 72B due to the movement of the cylinder gear 72B in the longitudinal direction. Designed to be longer than the maximum travel distance.

  The state shown in FIG. 2 is a case where the cylinder 7 is located in the forefront, and the distance between the lid portion 81B and the rear end surface of the striker 91 is designed to be about 12 mm. When the grip 14 is rotated in the direction opposite to the arrow A in FIG. 4 from the state of FIG. 2, the cylinder 7 is retracted to be in the state of FIG. Further, when the grip 14 is rotated in the direction opposite to the arrow A from the state shown in FIG. 3, the cylinder 7 is positioned at the rearmost position. When the cylinder 7 is located at the rearmost position, the distance between the lid 81B and the rear end surface of the striker 91 is designed to be about 8 mm.

  Next, the control of the motor 3 will be described based on FIG. The hammer drill 1 includes a full-wave rectifying and smoothing circuit 210, a switching circuit 220, and a control board 300, and is configured to be able to control the number of rotations of the motor 3 and the like.

  In the embodiment of the present invention, the motor 3 is a three-phase brushless DC motor and includes a rotor 34 and a coil 35. The permanent magnet of the rotor 34 includes a plurality of sets (two sets in this embodiment) of N poles and S poles, and the coil 35 includes three-phase coils U, V, and W that are star-connected. The energization direction and time for the coils U, V, and W are controlled based on the position detection signal from the hall element 34A arranged to face the permanent magnet.

  The full-wave rectifying / smoothing circuit 210 rectifies and smoothes the AC power from the commercial power source 200 and outputs it to the switching circuit 220.

  The switching circuit 220 is composed of six switching elements Q1 to Q6 connected in a three-phase bridge format. The gates of the six switching elements Q1 to Q6 that are bridge-connected are connected to the control signal output unit 230, and the drains or sources of the six switching elements Q1 to Q6 are connected to the star-connected coils U, V , W. As a result, the six switching elements Q1 to Q6 perform a switching operation by the switching element driving signals (driving signals such as H4, H5, and H6) input from the control signal output unit 230, and the full-wave rectifying and smoothing circuit 210 performs the switching operation. Power is supplied to the stator windings U, V, and W as full-wave rectified DC voltages as three-phase (U-phase, V-phase, and W-phase) voltages Vu, Vv, and Vw.

  Of the switching element drive signals (three-phase signals) for driving the gates of the six switching elements Q1 to Q6, the three negative power supply side switching elements Q4, Q5, Q6 are converted into pulse width modulation signals (PWM signals) H4, H5 and H6 are supplied, and the control unit 240 adjusts the power supply amount to the motor 3 by changing the pulse width (duty ratio) of the PWM signal based on the detection signal of the operation amount (stroke) of the trigger switch 21F. Then, the start / stop of the motor 3 and the rotation speed are controlled. That is, the striking force of a tip tool (not shown) can be adjusted by controlling the rotation speed of the motor 3 according to the pulling amount of the trigger switch 21F.

  Here, the PWM signal is supplied to one of the positive power supply side switching elements Q1 to Q3 or the negative power supply side switching elements Q4 to Q6 of the switching circuit 220, and the switching elements Q1 to Q3 or the switching elements Q4 to Q6 are operated at high speed. By switching, the power supplied to the coils U, V, W from the DC voltage of the full-wave rectifying / smoothing circuit 210 is controlled.

  The control board 300 includes a control signal output unit 230, a control unit 240, a current detection circuit 250, an applied voltage setting circuit 260, a rotation direction setting circuit 270, a rotor position detection circuit 280, and a rotor angle detection circuit. 290. Although not shown, the control unit 240 is a central processing unit (CPU) for outputting a drive signal based on a processing program and data, a ROM for storing the processing program, control data, various threshold values, and the like, And a RAM for temporarily storing data.

  Control unit 230 forms a drive signal for alternately switching predetermined switching elements Q <b> 1 to Q <b> 6 based on the output signal of rotor position detection circuit 280, and outputs the control signal to control signal output unit 230. As a result, the predetermined windings of the coils U, V, and W are alternately energized to rotate the rotor 34 in the set rotational direction. In this case, the drive signal applied to the negative power supply side switching elements Q4 to Q6 is output as a PWM modulation signal based on the output control signal of the applied voltage setting circuit 260. The current value supplied to the motor 3 is measured by the current detection circuit 250, and the value is fed back to the control unit 240, thereby adjusting the set drive power and current. The PWM signal may be applied to the positive power supply side switching elements Q1 to Q3. The control unit 240 detects the number of rotations of the motor 3 based on the signal from the rotor position detection circuit 280 and the signal from the rotor angle detection circuit 290.

  The applied voltage setting circuit 260 outputs a control signal to the control unit 240 based on the operation of the trigger switch 21F. Further, a switching signal from the forward / reverse switching lever 21G is detected and output to the control unit 240.

  Next, the operation mode and operation of the hammer drill 1 will be described. The operation mode of the hammer drill 1 is provided with two types of rotation hit mode and rotation mode.

  As shown in FIGS. 1 to 4, the rotation hit mode is such that the engagement claw 42 a of the sleeve 42 and the claw portion 44 b of the first conversion member 44 are engaged, and the first conversion member 44 and the sleeve 42 are engaged. It is in a state to be accompanied.

  When the user sets the rotation hitting mode, grips the handle portion 21B, and pulls the trigger switch 21F while pressing a tip tool (not shown) against a workpiece (not shown), electric power is supplied to the motor 3 to rotate The shaft 31 rotates, and the rotational force of the rotating shaft 31 is transmitted to the intermediate shaft 41 via the pinion gear 33 and the second gear 41A.

  As the intermediate shaft 41 rotates, a rotational force is transmitted to the cylinder 7 via the second pinion 41B and the cylinder gear 72B, and a tip tool (not shown) rotates. Further, the rotation of the intermediate shaft 41 causes the sleeve 42 to rotate around the intermediate shaft 41, and the first conversion member 44 engaged with the sleeve 42 also rotates at the same rotational speed as the intermediate shaft 41, so that the second conversion is performed. The arm portion 45B of the member 45 reciprocates in the front-rear direction.

  When the arm portion 45B starts to reciprocate and the piston 8 connected to the arm portion 45B suddenly moves to the rear portion, the distance between the rear end surface of the striker 91 and the lid portion 81B suddenly increases, so the air chamber 9a The air inside expands and the pressure drops rapidly. At this time, since the pressure in the space defined between the striker 91 and the intermediate piece 92 is higher than the pressure in the air chamber 9a, the striker 91 moves rapidly backward.

  At the next moment, the piston 8 starts to move forward due to the reciprocating motion, but the striking element 91 is moving backward, so the air in the air chamber 9a is rapidly compressed, and the striking element 91 is compressed air in the air chamber 9a. Is expanded forward to strike the intermediate element 92, and a striking force is applied to the tip tool (not shown) via the intermediate element 92. Then, the piston 8 suddenly moves to the rear again due to the reciprocating motion, and the striker 91 moves to the rear.

  In this way, the arm portion 45B reciprocates, the piston 8 reciprocates, the air in the air chamber 9a repeatedly compresses and expands, and the striker 91 reciprocates in the front-rear direction. The striking force is transmitted to a tip tool (not shown).

  Here, the relationship between the volume of the air chamber 9a and the striking force of a tip tool (not shown) will be described. As described above, since the striker 91 strikes the meson 92 while being accelerated forward by the expansion of the air in the air chamber 9a after moving to the rear portion, the stroke from the start of acceleration to hitting the meson 92 is longer. The speed of the striker 91 at the moment of hitting the intermediate piece 92 increases, and the energy of the striker 91 increases. Therefore, when the diameter of the piston 8 is considered to be constant, when the volume of the air chamber 9a is large, the stroke becomes long and the striking force applied to the tip tool (not shown) by the striking element 91 via the intermediate element 92 becomes large. Specifically, when the air chamber 9a at the position of the cylinder 7 shown in FIG. 2 is compared with the air chamber 9a at the position of the cylinder 7 shown in FIG. 3, the position of the cylinder 7 shown in FIG. The striking force applied to the tip tool is increased. That is, the striking force is increased by moving the cylinder 7 forward, and the striking force is weakened by moving the cylinder 7 rearward.

  As described above, in the rotary impact mode, the work material is processed by rotating and striking a tip tool (not shown).

  The rotation mode is a state in which the engagement between the sleeve 42 and the first conversion member 44 is released. In this state, the sleeve 42 and the first conversion member 44 are separated from each other and are not engaged. When the operation mode is changed from the rotation hitting mode to the rotation mode, the change lever 22A is operated to move the eccentric pin 22B forward, and the sleeve 42 is moved forward by moving the eccentric pin 22B forward.

  When the user sets the rotation mode and pulls the trigger switch 21F, the rotation shaft 31 rotates, and the rotational force of the rotation shaft 31 is transmitted to the intermediate shaft 41 via the pinion gear 33 and the second gear 41A.

  As the intermediate shaft 41 rotates, a rotational force is transmitted to the cylinder 7 via the second pinion 41B and the cylinder gear 72B, and a tip tool (not shown) rotates.

  Here, the rotation of the intermediate shaft 41 causes the sleeve 42 to rotate around the intermediate shaft 41, but the first conversion member 44 is separated from the sleeve 42 and is not engaged. 1 is not transmitted to the conversion member 44.

  As described above, in the rotation mode, the rotational force of the intermediate shaft 41 is not transmitted to the first conversion member 44, and transmission of the rotational force of the intermediate shaft 41 to the reciprocating motion conversion unit 43 is prevented. The impact force is not applied to the cutting tool. That is, in the rotation mode, the tip tool (not shown) only rotates.

  With the configuration as described above, the cylinder 7 can be moved in the axial direction, so that the volume of the air chamber 9a defined between the striker 91 and the piston 8 disposed in the cylinder 7 is changed. be able to. Since the volume of the air chamber 9a is one of the elements that determine the impact force of a tip tool (not shown), the tip (not shown) is moved by moving the cylinder 7 in the axial direction and changing the volume of the air chamber 9a. The impact force of the tool can be adjusted. Further, the striking force of the tip tool (not shown) can be adjusted without changing the rotational speed of the tip tool (not shown). For this reason, when drilling or the like in a fragile work material, the impact force is weakened by reducing the volume of the air chamber 9a while maintaining the rotational force of the tip tool (not shown). In this case, the rotational force and impact force suitable for the purpose of use, such as increasing the volume of the air chamber 9a and increasing the impact force while maintaining the rotational force of the tip tool (not shown), can be realized, and the range of work is widened. At the same time, work efficiency is improved.

  In addition, since the impact force of the tip tool (not shown) can be changed simply by rotating the cylinder moving mechanism, the rotational force and impact force suitable for the purpose of use can be realized easily and efficiently. Will be improved.

  Specifically, since the female screw 5a formed on the cylindrical member 5 and the male screw 6A formed on the holder 6 are screwed together, the impact received by the cylinder 7 and the holder 6 at the time of striking with the male screw 6A. It can be received by the entire threaded portion with the female screw 5a. For this reason, an intensity | strength rises with respect to the impact at the time of impact, and the lifetime of the hammer drill 1 becomes long. Further, since the cylinder 7 and the holder 6 can be moved in the axial direction only by a simple and simple operation of rotating the grip 14, the working efficiency is further improved.

  Since the support spring 13 is used as a tool fixing means and is also used as a means for urging the grip 14 against the cylindrical member 5, it is not necessary to provide another member as a means for urging the grip 14, and the number of parts is reduced. Can be reduced. For this reason, in the manufacturing process of the hammer drill 1, cost can be suppressed.

  Further, it is possible to prevent the meshing between the second pinion 41B and the cylinder gear 72B due to the movement of the cylinder 7 in the axial direction.

  In addition, when an excessive load is applied to the cylinder 7 holding the tip tool (not shown), the transmission of rotation from the cylinder gear 72B to the cylinder 7 is interrupted by the slip clutch, so an excessive load is applied to the motor 3 and the like. Can be suppressed.

  Specifically, in addition to changing the striking force by moving the cylinder 7 in the axial direction, the striking force can be changed by the pulling amount of the trigger switch 21F. It can be carried out. For this reason, the user can obtain a striking force more suitable for the work purpose, and the workability and convenience are improved.

  The impact tool according to the present invention is not limited to the above-described embodiments, and various modifications are possible within the scope of the gist of the invention described in the claims. For example, the present invention can be applied even when a crank mechanism is provided as the reciprocating motion conversion unit.

1 .. Hammer drill 2 .. Housing 3 .. Motor 4 .. Drive transmission part 5 .. Cylindrical member 5 a .. Female screw 5 b .. Engagement claw 6 .. Holder 6 A .. Male screw 6 B. 6a ··· engaging groove 7 · · cylinder 8 · · piston 9 · · impact mechanism 9a · · air chamber 10 · · output portion 11 · · holding ball 12 · · ball support member 13 · · holding spring 14 · · grip 14a ·· Tubular member engaging claw 14b ·· Holder engaging claw 21F ·· Trigger switch 22 ·· Gear housing 22A ·· Change lever 31 ·· Rotating shaft 41 ·· Intermediate shaft 41B ·· Second pinion 41E ·· Expanded Diameter portion 42 ··· Sleeve 42a · · Engagement claw 42b · · Indentation portion 43 · · Reciprocating motion conversion portion 71 · · Tip portion 72 · · Expanded cylindrical portion 72A · · Flange portion 72 · Shirindagiya 72E · mesons supporting member 72F ... abutment surface 72G ... sliding surface 91 .. striker 92 · mesons 240 ... control unit 260 ... applied voltage setting circuit

Claims (9)

A housing;
A motor disposed within the housing;
A reciprocating motion conversion unit disposed in the housing for converting the rotation of the motor into a reciprocating motion;
A cylinder supported by the housing;
A piston connected to the reciprocating motion conversion unit and arranged in the cylinder so as to be capable of reciprocating in the axial direction of the cylinder;
A striking tool having a striking element disposed in the cylinder and defining an air chamber with the piston,
The cylinder is supported by the housing so as to be movable in the axial direction, and the axial movement range of the striker during a striking operation changes according to the axial position of the cylinder. And
A striking tool, wherein the housing is provided with a cylinder moving mechanism for moving the cylinder in the axial direction. The cylinder is supported by the housing so as to be rotatable about its own axis.
2. A striking tool according to claim 1, further comprising: a rotation transmission mechanism that transmits rotation of the motor to the cylinder and rotates the cylinder about the axis. The cylinder has a tip that can hold a tip tool;
The cylinder moving mechanism is located on the tip side,
The impact tool according to claim 1 or 2, wherein the cylinder moves in the axial direction when the cylinder moving mechanism is rotated. The cylinder moving mechanism is fixed to the housing so as to be immovable and non-rotatable.
Positioned on the inner peripheral surface side of the cylindrical member, the cylinder is rotatably supported, is movable in the axial direction together with the cylinder, and is screwed with the first screw portion on the outer peripheral surface. A holder formed with two screw portions;
The impact tool according to claim 3, further comprising a grip that engages with the holder and rotates the holder by a rotation operation. Tool holding means for detachably holding the tip tool on the tip portion;
Biasing means for maintaining the state in which the tool holding means holds the tip tool, and
The grip is provided so as to be rotatable with the holder and movable in the axial direction with respect to the holder, and to be engageable with the cylindrical member,
The urging means urges the grip in a direction toward the position where the grip maintains engagement with the cylindrical member, and moves the grip against the urging force of the urging means. 5. The impact tool according to claim 4, wherein the engagement between the grip and the tubular member is released. The rotation transmission mechanism is rotated by the rotation of the motor and has a drive pinion having a predetermined length in the axial direction;
A driven gear that meshes with the drive pinion and can rotate integrally with the cylinder;
The impact tool according to claim 2, wherein the predetermined length of the drive pinion is a length capable of maintaining the meshing with the driven gear even when the cylinder is moved in the axial direction. The cylinder is provided with a flange portion having a contact surface,
The driven gear is provided with a sliding surface that contacts the corresponding contact surface and transmits the rotation of the driven gear to the cylinder, and the slip surface and the corresponding contact surface constitute a slip clutch mechanism,
The impact tool according to claim 6, wherein the driven gear is biased in a direction in which the sliding surface comes into contact with the corresponding contact surface.   The electric tool according to any one of claims 1 to 7, further comprising a trigger for controlling a rotation speed of the motor according to a pulling amount. A housing;
A motor disposed within the housing;
A tip portion that is movably supported by the housing and holds a tip tool, and a cylinder portion having an enlarged cylindrical portion having an inner diameter larger than the tip portion;
A cylinder moving mechanism for moving the cylinder part in the axial direction of the cylinder part;
A reciprocating motion conversion unit disposed in the housing for converting the rotation of the motor into a reciprocating motion;
A piston connected to the reciprocating motion conversion unit and disposed in the enlarged cylindrical portion so as to be capable of reciprocating in the axial direction;
An impactor disposed within the enlarged cylindrical portion and defining an air chamber with the piston;
An intermediate element that is located in front of the striker and transmits a striking force to the tip tool;
An impact tool comprising: an intermediate support member provided at a front portion of the enlarged diameter cylindrical portion and having an abutting portion that comes into contact with the meson.

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