JP2014004644A - Hammering tool - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hammering tool capable of preventing hammering action defects.SOLUTION: A hammer drill 1 includes: a piston 34 provided so as to be moved back and forth along an axial direction of a cylinder 31 inside the cylinder 31 by rotary drive power of a motor 21; an intermediate piston 35 provided so as to be moved back and forth along the axial direction of the cylinder 31 inside the cylinder 31 following the back and forth movement of the piston 34, and forming a first air chamber 37 together with the piston 34 and the cylinder 31; and a hammer provided so as to be moved back and forth along the axial direction of the cylinder 31 inside the cylinder 31 following the back and forth movement of the intermediate piston 35, and forming a second air chamber 38 together with the intermediate piston 35 and the cylinder 31. The intermediate piston 35 is configured so as not to be moved back and forth following the back and forth movement of the piston 34 in the state that a second breathing hole 31b is opened, and so as to be moved back and forth following the back and forth movement of the piston 34 in the state that the second breathing hole 31b is closed.

Description

  The present invention relates to a striking tool such as an electric hammer or a hammer drill, and more particularly to a striking tool that imparts a striking force to a tip tool.

  Conventionally, a striking tool that reciprocates a piston in a cylinder by the rotational driving force of a motor, reciprocates the striking element following the reciprocating movement of the piston, strikes the intermediate element, and crushes the work material with a tip tool Has been proposed (see, for example, Patent Document 1).

Japanese Patent No. 4556180

  However, in the above-described impact tool, although the piston is reciprocating, the impactor may not reciprocate following the piston, and the impact operation failure may occur where the tip tool does not perform the impact operation. It was.

  Accordingly, an object of the present invention is to provide a striking tool that solves the above-described problems of the prior art and prevents a striking operation failure.

  In order to achieve the above object, the present invention provides a housing, a motor housed in the housing and generating a rotational driving force, a cylinder housed in the housing and having a breathable hole that can be opened and closed, and the motor. A first piston provided in the cylinder so as to reciprocate along the axial direction of the cylinder by a rotational driving force, and follows the reciprocation of the first piston in the cylinder in the axial direction of the cylinder. A second piston that is reciprocally movable along the first piston and the cylinder to define a first air chamber, and follows the reciprocating motion of the second piston in the cylinder in the axial direction of the cylinder. And a striking element that is reciprocally movable along the second piston and the cylinder to define a second air chamber, and the breathing hole has a predetermined movement with respect to the cylinder. In position In the state, the second piston is formed closer to the first piston than the second piston, and the second piston does not reciprocate following the reciprocation of the first piston in the state where the breathing hole is opened. An impact tool configured to reciprocate following the reciprocation of the first piston in a state where the breathing hole is closed is provided.

  According to such a configuration, the second piston does not reciprocate following the reciprocation of the first piston in the state where the breathing hole is opened, and the reciprocation of the first piston in the state where the breathing hole is closed. Therefore, the striking element can be reliably reciprocated with respect to the reciprocating motion of the first piston, and a defective striking operation can be prevented.

  Here, the cylinder includes a movement restricting portion that restricts the movement of the second piston toward the striker, and the second piston moves from the state in contact with the movement restricting member toward the first piston. It is preferable that the predetermined position is a position where the second piston is in contact with the movement restricting portion.

  According to such a configuration, the second piston can be stopped at an appropriate position with respect to the first piston, and can be reciprocated from the stopped state. Therefore, the second piston can be reliably reciprocated following the reciprocation of the first piston, and a defective hitting operation can be prevented.

  The first piston is provided in the cylinder so as to reciprocate between the top dead center and the bottom dead center, and a striking force is applied to the tip tool by moving from the top dead center side to the bottom dead center side. The axial length of the cylinder of the first air chamber when the first piston is located at the bottom dead center and the second piston is located at the predetermined position is the second piston. Is preferably shorter than the length of the second air chamber in the cylinder axial direction when the striker is located at the initial strike position.

  According to this configuration, the second piston can easily follow the reciprocation of the first piston.

  Further, it is desirable that the second piston is lighter than the striker.

  According to this configuration, the second piston can easily follow the reciprocation of the first piston.

  Further, a tip tool which is driven by the reciprocating motion of the striker and configured to strike the workpiece, and a slide sleeve which is provided so as to be movable along the axial direction of the cylinder on the outer periphery of the cylinder The slide sleeve is configured to move from the striker side toward the first piston side by pressing the tip tool against the workpiece, and by moving the slide sleeve The breathing hole is preferably opened and closed.

  According to the present invention, it is possible to provide a striking tool capable of preventing a striking operation failure.

The whole perspective view which shows the whole impact tool by embodiment of this invention. Sectional drawing which shows the state which pressed the front-end tool against the cut material in the impact tool by embodiment of this invention. The impact tool by embodiment of this invention WHEREIN: The expanded sectional view of a part of cylinder. Sectional drawing which shows the state at the time of no load in the impact tool by embodiment of this invention. Sectional drawing which shows the striking operation state in the striking tool by embodiment of this invention. Sectional drawing which shows the striking operation state in the striking tool by embodiment of this invention.

  An impact tool according to an embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a perspective view showing an entire electric hammer 1 which is a typical striking tool, and a handle part 10, a motor housing 20, and an outer frame member 30 constitute a casing. A tool holding portion 60 that detachably holds the tip tool 50 is disposed on the side of the outer frame member 30 opposite to the handle portion 10. A side handle 40 is provided on the outer frame member 30 in the vicinity of the tool holding unit 60. In the following description, the side on which the tip tool 50 is provided will be referred to as the front side, the handle portion 10 side as the rear side, the extending direction of the motor housing 20 as the lower side, and the reverse as the upper side.

  A power cable 11 is attached to the handle portion 10 and a trigger 12 that can be operated by a user is attached. By connecting the power cable 11 to an external power source (not shown) and operating the trigger 12, the power supply can be switched between connection and disconnection.

  The motor housing 20 is provided in front of the handle portion 10. Although the handle portion 10 and the motor housing 20 have separate structures, they can be made of plastic and integrally molded. The outer frame member 30 is located above and in front of the motor housing 20.

  As shown in FIG. 2, a motor 21 is accommodated in the motor housing 20. The motor 21 includes a motor pinion shaft 22 and outputs a rotational driving force. A pinion 22 </ b> A is provided at the upper end of the motor pinion shaft 22. A crankshaft 23 extends in parallel with the motor pinion shaft 22 on the rear side of the pinion 22A. The crankshaft 23 is supported by the motor housing 20 via a bearing so as to be rotatable about its axis. A gear 24 that meshes with the pinion 22 </ b> A is coaxially fixed to the lower portion of the crankshaft 23.

  A motion conversion mechanism 25 that converts the rotational motion of the motor 22 into a reciprocating motion is provided at the upper end of the crankshaft 23. The motion conversion mechanism 25 includes a crank weight 25A, a crank pin 25B, and a connecting rod 25C. The crank weight 25 </ b> A is fixed to the upper end of the crankshaft 23. The crank pin 25B is fixed to the end of the crank weight 25A. A crankpin 25B is inserted at the rear end of the connecting rod 25C.

  A cylinder 31 extending in a direction orthogonal to the motor pinion shaft 22 is provided in the outer frame member 30. The cylinder 31 has a substantially cylindrical shape whose axial center extends in the front-rear direction, and a plurality of first breathing holes 31a and a plurality of second breathing holes 31b are formed. The 2nd breathing hole 31b which is a breathing hole is formed in the back side rather than the 1st breathing hole 31a. Further, the cylinder 31 is formed with a first adjustment hole 31c and a second adjustment hole 31d. The first and second adjustment holes 31c and 31d have a size that does not affect the hitting operation, but have a size that allows the air inside and outside the cylinder 31 to flow after use. Further, as shown in FIG. 3, the cylinder 31 is provided with a step portion 31E, and the inner diameter of the cylinder 31 in front of the step portion 31E is slightly smaller than the inner diameter of the rear cylinder 31. . The cylinder 31 has a flange portion 31 </ b> F that contacts the outer frame member 30, and the rearward movement of the cylinder 31 is restricted when the flange portion 31 </ b> F contacts the outer frame member 30.

  The front end of the cylinder 31 is gripped by the cylinder holder 32, and the movement of the cylinder 31 in the forward direction is restricted. The cylinder holder 32 is a resin molded product, and has three leg portions 32A (only one is shown in the figure) provided at equal intervals along the circumferential direction of the cylinder 31, and the leg portion 32A. The front end of this is in contact with the outer frame member 30. A tool holding portion 60 is provided in front of the cylinder 31, and a tip tool 50 is detachably attached.

  A slide sleeve 33 slidable in the front-rear direction is provided on the outer periphery of the cylinder 31. The slide sleeve 33 is provided so that the plurality of second breathing holes 31b can be opened and closed by the movement thereof. The slide sleeve 33 is urged forward by a spring 33A. The rear end of the spring 33A is located at a flange portion 31F provided at the rear end of the cylinder 31, and the outer diameter of the flange portion 31F is configured to be larger than the outer diameter of a rear end portion 33B described later of the slide sleeve 33. Yes. The slide sleeve 33 includes a rear end portion 33B, an intermediate portion 33C, and a front end portion 33D. The rear end portion 33B can open and close the second breathing hole 41b. The intermediate portion 33C faces the first breathing hole 31a, has a gap with the cylinder 31, and is configured not to close the first breathing hole 31a. The front end portion 33C is configured such that the outer diameter thereof is larger than the outer diameters of the rear end portion 33B and the intermediate portion 33C, the front end of the spring 33A abuts on the stepped portion formed by the difference in the outer diameter, and the slide sleeve 33 is Always biased forward.

  A piston 34 that is a first piston is provided inside the cylinder 31 so as to be slidable on the inner periphery thereof. The piston 34 has a piston pin 34A, and the piston pin 34A is inserted at the tip of the connecting rod 25C. The piston 34 is configured to reciprocate between a top dead center (most rear side) and a bottom dead center (front most side) by the motion conversion mechanism 25. In the state shown in FIG. 2, the piston 34 is located at the bottom dead center.

  An intermediate piston 35 as a second piston is provided on the front side of the piston 34 in the cylinder 31 so as to be slidable in the front-rear direction on the inner periphery of the cylinder 31. The intermediate piston 35 is positioned on the rear side of the step portion 31E, and the outer diameter of the intermediate piston 35 is slightly larger than the inner diameter of the cylinder 31 on the front side of the step portion 31E. Therefore, the movement of the intermediate piston 35 to the front side of the step portion 31E is restricted by the step portion 31E. The position where the intermediate piston 35 abuts on the step portion 31E (the position shown in FIGS. 2 and 4) corresponds to the predetermined position of the intermediate piston 35 that is the second piston. The second breathing hole 31 b that is a breathing hole is formed closer to the piston 34 than the intermediate piston 35 when the intermediate piston 35 is in a predetermined position with respect to the cylinder 31.

  A striker 36 is disposed on the front side of the intermediate piston 35 in the cylinder 31 so as to be slidable in the front-rear direction on the inner periphery of the cylinder 31. The outer peripheral surface of the striker 36 selectively opens and closes the first breathing hole 31a described above by sliding movement. A space surrounded by the piston 34, the intermediate piston 35, and the cylinder 31 is a first air chamber 37, and a space surrounded by the intermediate piston 35, the striker 36, and the cylinder 31 is a second air chamber 38. Further, the intermediate piston 35 is configured to be lighter than the striker 36.

  An intermediate element 39 is disposed in front of the striker 36 so as to be able to reciprocate in the front-rear direction. The rear end portion of the intermediate piece 39 can come into contact with the striker 36, and the strike force is transmitted to the intermediate piece 39 by the striker 36. The front end portion of the meson 39 can come into contact with the rear portion of the tip tool 50, and the striking force is transmitted from the tip portion of the meson 39 to the tip tool 50.

  A buffer member 40 and a buffer member holder 41 are provided on the outer periphery on the rear end side of the intermediate element 46. A hammer holder 42 that engages with the buffer member 40 is provided on the outer periphery of the rear end side of the intermediate element 39. The hammer holder 42 has three leg portions 42A (only one is shown in the figure) that extends toward the rear side on the outer side in the radial direction of the cylinder 31 and is provided at equal intervals along the circumferential direction of the cylinder 31. The rear end portion of the leg portion 42 </ b> A is in contact with the slide sleeve 33. The hammer holder 42 is provided so as to be slidable along the three legs 32A of the cylinder holder 32 and the inner periphery of the outer frame member 30, and is always moved forward by a spring 33A via a slide sleeve 33. It is energized.

  Further, the intermediate element 39 is always urged forward by the spring 33 </ b> A via the buffer member 40, the buffer member holder 41, the hammer holder 42, and the slide sleeve 33. In other words, when the intermediate element 39 moves rearward, the buffer member 40, the buffer member holder 41, the hammer holder 42, and the slide sleeve 33 move backward against the biasing force of the spring 33A.

  Next, the operation of the electric hammer 1 according to the first embodiment will be described. In the unloaded state of the electric hammer 1 shown in FIG. 4, the handle portion 10 is gripped by hand, the trigger 12 is pulled, and electric power is supplied to the electric motor 21 to be driven to rotate. This rotational driving force is transmitted to the crankshaft 23 through the pinion 22A and the gear 24. The rotation of the crankshaft 23 is converted into a reciprocating motion of the piston 34 in the cylinder 31 by the motion conversion mechanism 25 (crank weight 25A, crankpin 25B, and connecting rod 25C).

  Since the electric hammer 1 shown in FIG. 4 is in an unloaded state, the slide sleeve 33, the hammer holder 42, and the intermediate element 39 are positioned in the foremost position by the urging force of the spring 33A, and the hammer holder 42 is located behind the cylinder holder 32. Separated from the end. Further, in the state of the electric hammer 1 shown in FIG. 4, the rear end portion 33B of the slide sleeve 33 is located in front of the second breathing hole 31b, so the second breathing hole 31b is not closed, The first air chamber 37 is not sealed. Therefore, even if the piston 34 reciprocates, the pressure fluctuation in the first air chamber 37 does not occur and the action of the air spring does not occur, so the intermediate piston 35 does not reciprocate following the reciprocating motion of the piston 34. Therefore, no striking force is applied to the tip tool 50.

  Next, the tip tool 50 is pressed against a workpiece (not shown). Accordingly, the tip tool 50 and the intermediate piece 39 are pushed toward the rear end side, and the three leg portions 42A of the hammer holder 42 push the slide sleeve 33 toward the rear end side against the biasing force of the spring 33A. By the retraction of the slide sleeve 33, the second breathing hole 31b is closed by the rear end portion 33B, and the first air chamber 37 becomes a sealed space as shown in FIG. Further, by the rearward movement of the intermediate element 39, the striking element 36 is also moved rearward, the first breathing hole 31a is closed by the striking element 36, and the second air chamber 38 is sealed in the same manner as the first air chamber 37. It becomes space.

  As shown in FIG. 2, when the tip tool 50 is pressed against a workpiece (not shown), the intermediate element 39 moves to the rear end side until the hammer holder 42 contacts the rear end portion of the cylinder holder 32. The position of the striker 36 when the hammer holder 42 is in contact with the rear end of the cylinder holder 32 corresponds to the initial strike position of the striker 36. In the state shown in FIG. (The distance between the piston 34 located at the bottom dead center and the intermediate piston 35 located at a predetermined position) is the length of the second air chamber 38 in the front-rear direction (the intermediate piston 35 located at the predetermined position). It is configured to be shorter than the distance to the striker 36 located at the initial strike position.

  In this state, when the piston 34 reciprocates as shown in FIGS. 5 and 6, pressure fluctuation occurs in the first air chamber 37, and the intermediate piston 35 is moved by the action of the air spring in the first air chamber 37. The reciprocating motion is started following the reciprocating motion. When the intermediate piston 35 starts to reciprocate, pressure fluctuation occurs in the second air chamber 38, and the striker 36 reciprocates following the reciprocation of the intermediate piston 35 by the action of the air spring in the second air chamber 38. Start moving. As the striker 36 reciprocates, the striker 36 collides with the intermediate piece 39, and the strike force is transmitted to the tip tool 50. Thereby, a work material is crushed. Further, when the intermediate piston 35 moves to the front side during the reciprocating operation, the intermediate piston 35 comes into contact with the stepped portion 31C, and movement to the striker 36 side from the stepped portion 31C is restricted. Then, the intermediate piston 35 operates so as to reciprocate following the reciprocation of the piston 34 from the state where movement is restricted by the step portion 31C and once stopped. In other words, the intermediate piston 35 is configured to have a desired positional relationship with respect to the piston 34 by the step portion 31C.

  As described above, the intermediate piston 35 does not reciprocate following the reciprocation of the piston 34 in a state where the second breathing hole 31b is opened, and the piston 34 does not reciprocate in the state where the second breathing hole 31b is closed. It is configured to reciprocate following the reciprocating motion. Then, the striker 36 reciprocates following the reciprocation of the intermediate piston 35. Therefore, the intermediate piston 35 reciprocates following the reciprocation of the piston 34, and the striker 36 reciprocates following the reciprocation of the intermediate piston 35. Thus, the intermediate piston 35 is interposed between the piston 34 and the striker 36, the intermediate piston 35 is reciprocated following the reciprocation of the piston 34, and the reciprocation of the intermediate piston 35 is followed. Since the child 36 is reciprocated, the striking member 36 can be reliably reciprocated with respect to the reciprocating motion of the piston 34, and a bad striking operation can be prevented.

  5 shows a state where the piston 34 is moving from the bottom dead center to the top dead center, and FIG. 6 shows a state where the piston 34 is moving from the top dead center to the bottom dead center. Indicates a state of being compressed to the maximum. And since the cylinder 31 has the 1st air chamber 37 and the 2nd air chamber 38 which were divided by the intermediate piston 35, in the state shown in FIG. 6, the 1st air chamber 37 and the 2nd air chamber 38 were added. Since the air cushion acts on the striker 36, the maximum reaction force acting on the piston 34 is greatly reduced. Therefore, it can prevent that the rotation speed of the motor 21 falls.

  Further, the intermediate piston 35 is configured to reciprocate following the reciprocating motion of the piston 34 from a state where movement is restricted by the stepped portion 31C and once stopped. Thereby, the intermediate piston 35 can be stopped at an appropriate position with respect to the piston 34 and can be reciprocated from the stopped state. Therefore, the intermediate piston 35 can be reliably reciprocated following the reciprocating motion of the piston 34, and a bad hitting operation can be prevented.

  In the state shown in FIG. 2, the length of the first air chamber 37 in the front-rear direction is configured to be shorter than the length of the second air chamber 38 in the front-rear direction. As a result, the intermediate piston 35 can easily follow the reciprocation of the piston 34.

  Further, the intermediate piston 35 is configured to be lighter than the striker 36. As a result, the intermediate piston 35 can easily follow the reciprocation of the piston 34.

  Further, by pressing the tip tool 50 against a work material (not shown), the slide sleeve 33 moves backward, the second breathing hole 31b is closed by the rear end portion 33B, and the first air chamber 37 becomes a sealed space. In this manner, the second breathing hole 31b can be closed and the first air chamber 37 can be sealed with the pressing operation of the tip tool 50.

  In addition, the impact tool by this invention is not limited to embodiment mentioned above, A various change is possible in the range of the summary of the invention described in the claim. For example, although the impact tool is an electric hammer in the embodiment, it may be a hammer drill. Further, although the stepped portion 31C restricts the movement of the intermediate piston 35 toward the front side, it may be a protruding portion.

DESCRIPTION OF SYMBOLS 1: Hammer drill, 10: Handle part, 20: Motor housing, 21: Motor, 30: Outer frame member, 31: Cylinder, 31a: 1st breathing hole, 31b: 2nd breathing hole, 31E: Step part, 33: Slide Sleeve: 34: Piston, 35: Intermediate piston, 36: Strike child, 37: First air chamber, 38: Second air chamber, 39: Meson, 41: Slide sleeve, 50: Tip tool

Claims (5)

A housing;
A motor housed in the housing and generating a rotational driving force;
A cylinder housed in the housing and formed with an openable and closable breathing hole;
A first piston provided in a reciprocating manner along the axial direction of the cylinder by the rotational driving force of the motor;
A second piston that is configured to follow the reciprocating motion of the first piston and to reciprocate in the cylinder along the axial direction of the cylinder, and that defines a first air chamber together with the first piston and the cylinder; ,
A striking element provided so as to be able to reciprocate in the cylinder along the axial direction of the cylinder following the reciprocating movement of the second piston, and defining a second air chamber together with the second piston and the cylinder; With
The breathing hole is formed closer to the first piston than the second piston when the second piston is in a predetermined position with respect to the cylinder.
The second piston does not reciprocate following the reciprocation of the first piston when the breathing hole is open, and does not reciprocate the first piston when the breathing hole is closed. A striking tool characterized by being configured to reciprocate following. The cylinder includes a movement restricting portion that restricts movement of the second piston toward the striker,
The second piston is configured to move from the state in contact with the movement restricting member toward the first piston and reciprocate,
The impact tool according to claim 1, wherein the predetermined position is a position where the second piston abuts on the movement restricting portion. The first piston is provided so as to be able to reciprocate between the top dead center and the bottom dead center in the cylinder, and a striking force is applied to the tip tool by moving from the top dead center side to the bottom dead center side. Configured,
The length of the first air chamber in the axial direction of the cylinder when the first piston is located at the bottom dead center and the second piston is located at the predetermined position is such that the second piston is located at the predetermined position. The striking device according to claim 1 or 2, wherein the striking element is configured to be shorter than a length of the second air chamber in the cylinder axial direction when the striking member is located at a striking initial position. tool.   The impact tool according to any one of claims 1 to 3, wherein the second piston is lighter than the impactor. A tip tool driven by the reciprocating motion of the striker and configured to strike the workpiece;
A slide sleeve provided on the outer periphery of the cylinder so as to be movable along the axial direction of the cylinder;
The slide sleeve is configured to move from the striker side toward the first piston side by pressing the tip tool against the workpiece, and the breathing hole is opened and closed by the movement of the slide sleeve. The impact tool according to claim 1, wherein:

Images