JP7400591B2 - work equipment - Google Patents

Description

The present invention relates to a working machine having a cylinder, a piston provided inside the cylinder, and a striking portion provided inside the cylinder.

An example of a working machine having a cylinder, a piston provided inside the cylinder, and a striking part provided inside the cylinder is described in Patent Document 1. The impact working machine as a working machine described in Patent Document 1 includes a housing, a cylinder holder, a cylinder, a piston, an electric motor, a striking part, an intermediate, a mass body, and an elastic member. The housing has a motor case and a striking case, and the electric motor is provided within the motor case. The cylinder holder has a cylindrical shape, and is provided within the striking case. The cylinder is provided within a cylinder holder, and the piston and striking portion are provided inside the cylinder. A pressure chamber is provided inside the cylinder between the piston and the striking part. A breathing hole is provided radially through the cylinder. The breathing hole leads to the interior of the cylinder.

The mass body is provided inside the cylinder holder and outside the cylinder. The elastic member is provided inside the cylinder holder and outside the cylinder. Two elastic members are provided, and the mass body is provided between the elastic members.

In the impact working machine described in Patent Document 1, a piston is reciprocated by an electric motor, and the pressure in a pressure chamber changes. When the pressure in the pressure chamber increases, a striking force in the direction of the center line of the cylinder is applied to the striking part, and the striking force received by the striking part is transmitted to the intermediate. The mass body operates in the direction of the centerline of the cylinder, and vibrations of the housing are suppressed.

JP 2017-119329 Publication

The inventor of this application recognized the problem that if the range in which the mass body moves in the direction of the center line of the cylinder is restricted so that the mass body does not block the breathing hole, the ability of the mass body to reduce vibrations will be reduced. did.

SUMMARY OF THE INVENTION An object of the present invention is to provide a work machine that can suppress a decline in the vibration reduction function of a mass body.

An impact working machine according to one embodiment includes: a cylindrical cylinder; a piston provided inside the cylinder and reciprocated in a center line direction of the cylinder; a striking part operable in the centerline direction; a gas chamber provided between the piston and the striking part inside the cylinder and applying an operating force in the centerline direction to the striking part; A working machine having a breathing hole passing through the cylinder in a radial direction and connecting the inside of the cylinder and the outside of the cylinder, the mass being provided outside the cylinder and movable in the direction of the center line. an elastic member provided outside the cylinder to support the mass body so as to be movable in the direction of the center line, and to form the first gap in the radial direction between the mass body and the cylinder. and has.

In the impact working machine, the movement range of the mass body in the direction of the center line of the cylinder is not limited, and the mass body can be prevented from blocking the breathing hole. Therefore, it is possible to prevent the mass body from deteriorating in its ability to reduce vibrations.

FIG. 2 is a sectional view of the entire working machine viewed from the front. It is a part of a working machine, and is a sectional view of a state where a tip tool is in contact with a target object. FIG. 2 is a cross-sectional view of a part of the working machine in a state where the tip tool is separated from the object. FIG. 3 is a side cross-sectional view of the cylinder of FIG. 2 taken along line IV-IV. 3 is a sectional view showing a first specific example of the vibration reduction mechanism shown in FIG. 2. FIG. 6 is a sectional view showing a modification example of the mass body of the vibration reduction mechanism shown in FIG. 5. FIG. 3 is a sectional view showing a second specific example of the vibration reduction mechanism shown in FIG. 2. FIG. 3 is a sectional view showing a third specific example of the vibration reduction mechanism shown in FIG. 2. FIG. FIG. 3 is a sectional view showing a fourth specific example of the vibration reduction mechanism shown in FIG. 2;

DESCRIPTION OF THE PREFERRED EMBODIMENTS A hammer drill, which is an embodiment of a working machine, will be described in detail below with reference to the drawings. Among the configurations shown in each figure, the same configurations are designated by the same reference numerals.

The hammer drill 10 shown in FIG. 1 is an impact working machine that presses a tip tool 11 against an object 12 and applies impact force to the tip tool 11 to process the object 12, as shown in FIG. The object 12 may be made of concrete, brick, stone, or asphalt. Further, the processing performed on the object 12 includes crushing the object 12, scraping the surface of the object 12, cutting the object 12, and forming grooves in the object 12. The tip tool 11 has a shape suitable for the material of the object 12 and the treatment to be performed. In this embodiment, an example will be described in which concrete as a target object 12 is crushed by the tip tool 11. For this reason, the tip tool 11 shown in FIG. 1 is shown in a wedge shape for convenience.

The hammer drill 10 includes a housing 13, an electric motor 17, a handle portion 18, a controller 20, and a vibration reduction mechanism 54. The housing 13 includes a motor case 14, a striking case 15, and a gear case 16. Motor case 14, impact case 15, and gear case 16 are fixed to each other.

The handle portion 18 is connected to the motor case 14 and the gear case 16. The handle portion 18 is a portion that an operator grasps with his/her hand when using the hammer drill 10. A power cable 19 is attached to the handle portion 18. The power cable 19 is connected to a power source, for example, an AC power source. A trigger 21 and a trigger switch 22 are provided on the handle portion 18.

The controller 20 is provided inside the housing 13, for example inside the motor case 14. The controller 20 is connected to the power cable 19 by a lead wire, and is also connected to the electric motor 17 by a lead wire. The controller 20 is connected to a trigger switch 22 by a lead wire.

The electric motor 17 is a drive source, and the electric motor 17 is arranged inside the motor case 14. Electric motor 17 has a stator 23 and a rotor 24. When the operator grasps the handle part 18 and operates the trigger 21 to turn on the trigger switch 22, power from the power supply part is supplied to the electric motor 17, and the electric motor 17 rotates, specifically, the rotor 24 rotates. When the trigger switch 22 is turned off, the electric power from the power supply section is not supplied to the electric motor 17, and the electric motor 17 stops, specifically, the rotor 24 stops.

The rotor 24 is fixed to a rotating shaft 25. The rotating shaft 25 is provided within the motor case 14 and rotatably supported by a bearing 26 . The rotating shaft 25 is rotatable about the center line A2. The center line A2 is an engineering virtual line passing through the center of the rotating shaft 25. A gear 27 is provided on the outer periphery of the rotating shaft 25 . A crankshaft 28 and a connecting rod 29 are provided within the housing 13. The crankshaft 28 is rotatably supported by a bearing 30. The crankshaft 28 is rotatable about the center line A3. Center line A3 is an engineering imaginary line passing through the center of crankshaft 28. Center line A2 and center line A3 are arranged parallel to each other.

Further, a gear 31 fixed to the crankshaft 28 is provided, and the gear 31 meshes with the gear 27. The number of teeth of the gear 31 is greater than the number of teeth of the gear 27. The gears 27 and 31 serve as a speed reduction mechanism when transmitting the rotational force of the rotating shaft 25 to the crankshaft 28. Furthermore, the connecting rod 29 is rotatably connected to the crankshaft 28. The crankshaft 28 and the connecting rod 29 constitute a conversion mechanism 77.

The impact case 15 has a cylindrical shape, and a first end in the longitudinal direction of the impact case 15 is fixed to a gear case 16. The longitudinal direction of the striking case 15 is along the center line A1. A cylinder case 34 is provided inside the impact case 15. The cylinder case 34 has a cylindrical shape, and a cylinder 35 is provided inside the cylinder case 34 . The cylinder case 34 is made of metal, for example aluminum. The cylinder 35 is made of metal, for example steel. The cylinder case 34 and the cylinder 35 are arranged concentrically about the center line A1. Center line A1 is an imaginary line located at the center of cylinder case 34 and cylinder 35. In FIG. 1, which is a front view including center lines A1, A2, and A3, center line A1 intersects center lines A2 and A3 at a predetermined angle, for example, at an angle of 90 degrees.

A retainer sleeve 36 is arranged from the inside to the outside of the cylinder case 34. The retainer sleeve 36 has a cylindrical shape, and the retainer sleeve 36 is arranged concentrically with the cylinder 35. The cylinder case 34, the cylinder 35, and the retainer sleeve 36 are positioned relative to the striking case 15 in a direction along the center line A1. The cylinder case 34 is positioned in the radial direction with respect to the impact case 15. The retainer sleeve 36 has a cylindrical shape. The retainer sleeve 36 is a support member that supports the tip tool 11.

An intermediate member 42 is provided across the retainer sleeve 36 and the cylinder 35 . The meson 42 is movable in the direction along the center line A1 and is made of metal. The intermediate member 42 can come into contact with the tip tool 11 and move away from it. The meson 42 has a shaft shape and has a large diameter portion 43 . An annular tapered surface 39 is provided in the intermediate member 42, and when the large diameter portion 43 comes into contact with the tapered surface 39, the intermediate member 42 cannot move in the direction along the center line A1 toward the tip tool 11.

A piston 44 shown in FIG. 2 is provided inside the cylinder 35. The piston 44 can reciprocate in the direction along the center line A1. An O-ring 65 as a sealing member is attached to the outer surface of the piston 44. The O-ring 65 is made of rubber, and contacts the inner peripheral surface of the cylinder 35 to form a sealing surface. The piston 44 is connected to the connecting rod 29 as shown in FIG. When the rotational force of the rotating shaft 25 is transmitted to the crankshaft 28, the piston 44 reciprocates within the cylinder 35.

A striking portion 45 shown in FIG. 2 is provided within the cylinder 35. The striking portion 45 is arranged between the piston 44 and the intermediate member 42 in the direction along the center line A1. The striking part 45 is made of metal, and the striking part 45 is movable in the direction along the center line A1. An O-ring 46 as a sealing member is attached to the outer surface of the striking portion 45, and the O-ring 46 contacts the inner circumferential surface of the cylinder 35 to form a sealing surface.

A pressure chamber B1 is provided inside the cylinder 35. Pressure chamber B1 is located between striking portion 45 and piston 44. When the piston 44 operates and the pressure in the pressure chamber B1 increases, a biasing force in the direction along the center line A1, that is, a striking force is applied to the striking portion 45. When the striking part 45 operates, it strikes the intermediate element 42, and the impact force received by the intermediate element 42 is transmitted to the tip tool 11.

As shown in FIG. 5, a first breathing hole 47 and a second breathing hole 48 are provided to penetrate the cylinder 35 in the radial direction. Both the first breathing hole 47 and the second breathing hole 48 are connected to the inside of the cylinder 35 . Further, a space C1 is provided between the cylinder 35 and the cylinder case 34. The first breathing hole 47 and the second breathing hole 48 are connected to the space C1.

The first breathing hole 47 is provided to prevent "dry hitting" by the hitting section 45. The meaning of "dry hitting" by the hitting section 45 will be described later. The first breathing hole 47 is provided between the retainer sleeve 36 and the second breathing hole 48 in the direction along the center line A1. The planar shape of the first breathing hole 47 is circular. A plurality of first breathing holes 47 may be provided at intervals in the circumferential direction of the cylinder 35, as shown in FIG. The second breathing hole 48 plays a role in adjusting the air pressure in the pressure chamber B1. A plurality of second breathing holes 48 may be provided at intervals in the circumferential direction of the cylinder 35. The second breathing hole 48 has an opening 48A. The opening 48A is a portion of the second breathing hole 48 that is opened to the outer peripheral surface 35A of the cylinder 35. The inner surface of the opening 48A has a taper that increases as it approaches the outer peripheral surface 35A of the cylinder 35. The planar shape of the opening 48A is circular.

As shown in FIG. 2, a damper holder 49, a damper 50, and a washer 51 are provided within the cylinder case 34. The damper holder 49, the damper 50, and the washer 51 are provided between the cylinder 35 and the retainer sleeve 36 in the direction along the center line A1. The damper 50 is made of rubber, and the damper holder 49 and washer 51 are made of metal. The damper holder 49, the damper 50, and the washer 51 are all annular. A portion of the intermediate member 42 is arranged within a damper holder 49, a damper 50, and a washer 51. The damper 50 is arranged between the damper holder 49 and the washer 51 in the direction along the center line A1. The large diameter portion 43 of the intermediate member 42 is arranged between the washer 51 and the tapered surface 39 in the direction along the center line A1.

The operator can use the hammer drill 10 as follows. Here, an example will be described in which the hammer drill 10 is used in a state where the intermediate member 42 is located above the tip tool 11 in the direction in which gravity acts, that is, in the vertical direction. Note that the description will be made assuming that the center line A1 shown in FIGS. 1, 2, and 3 is arranged along the vertical direction. When the operator holds the hammer drill 10 by grasping the handle part 18 and presses the tip tool 11 against the object 12 as shown in FIG. The tip tool 11 and the intermediate member 42 are stopped by being pressed.

Further, when the tip tool 11 is pressed against the object 12, the position where the O-ring 46 contacts the inner peripheral surface of the cylinder 35 is located at the first breathing hole 47 in the direction along the center line A1, as shown in FIG. and the piston 44. Therefore, the O-ring 46 blocks off the pressure chamber B1 and the first breathing hole 47. Furthermore, the position where the O-ring 65 contacts the inner peripheral surface of the cylinder 35 is between the second breathing hole 48 and the crankshaft 28 in the direction along the center line A1, regardless of the position of the piston 44.

When the operator operates the trigger 21 to turn on the trigger switch 22 and the rotating shaft 25 of the electric motor 17 rotates, the piston 44 reciprocates in the direction along the center line A1. The conversion mechanism 77 converts the rotational force of the rotating shaft 25 into a reciprocating force of the piston 44. When the piston 44 moves away from the retainer sleeve 36, the pressure in the pressure chamber B1 becomes lower than the pressure in the space C1, and the air in the space C1 is sucked into the pressure chamber B1 through the second breathing hole 48. Further, the striking portion 45 separates from the retainer sleeve 36 later than the time when the piston 44 separates from the retainer sleeve 36 .

After the piston 44 reaches the farthest position from the retainer sleeve 36, that is, the top dead center, the piston 44 moves toward the retainer sleeve 36. During the stroke of the piston 44 approaching the retainer sleeve 36, a portion of the air in the pressure chamber B1 passes through the second breathing hole 48 and is discharged into the space C1. At the time when the O-ring 65 blocks off the pressure chamber B1 and the second breathing hole 48, the air pressure in the pressure chamber B1 is the initial pressure. As the piston 44 approaches the retainer sleeve 36 further, the air pressure in the pressure chamber B1 increases from the initial pressure.

The striking portion 45 moves toward the retainer sleeve 36 due to the increase in pressure in the pressure chamber B1, and the striking portion 45 applies a striking force to the meson 42. The impact force received by the intermediate member 42 is transmitted to the tip tool 11, and the tip tool 11 crushes the object 12. After the piston 44 reaches the position closest to the retainer sleeve 36, that is, the bottom dead center, the piston 44 moves away from the retainer sleeve 36. The maximum pressure in the pressure chamber B1 is determined by the amount of movement of the piston 44 from the time when the second breathing hole 48 is closed by the O-ring 65 until it reaches the bottom dead center, and in a plane perpendicular to the center line A1. It is determined according to the area of the pressure chamber B1. That is, the position of the second breathing hole 48 in the direction along the center line A1 is one of the factors that determines the maximum pressure of the pressure chamber B1. In that sense, the second breathing hole 48 plays a role in adjusting the pressure in the pressure chamber B1. While the rotating shaft 25 of the electric motor 17 is being rotated, the piston 44 is reciprocated in the direction along the center line A1, and the striking portion 45 intermittently applies striking force to the meson 42.

When the operator moves the tip tool 11 away from the object 12 as shown in FIG. 42 stops. Further, the striking portion 45 comes into contact with the intermediate member 42 due to the pressure in the pressure chamber B1 and stops. When the striking portion 45 stops at the position shown in FIG. 3, the O-ring 46 contacts the inner circumferential surface of the cylinder 35 between the first breathing hole 47 and the retainer sleeve 36 in the direction along the center line A1. Therefore, the pressure chamber B1 is connected to the first breathing hole 47.

If the pressure chamber B1 is connected to the first breathing hole 47, even if the electric motor 17 rotates and the piston 44 reciprocates, the air in the pressure chamber B1 will be discharged from the first breathing hole 47 to the space C1. be done. Therefore, the pressure in the pressure chamber B1 does not rise suddenly. Therefore, it is possible to prevent the striking part 45 from striking the intermediate member 42 while the tip tool 11 is separated from the object 12, that is, "dry striking".

When the operator presses the tip tool 11 against the object 12 as shown in FIG. 2 and the striking part 45 strikes the intermediate piece 42, the reaction force is generated by the washer 51, damper 50, damper holder 49, cylinder 35, and stopper ring. It is transmitted to the housing 13 via 53. Further, when the piston 44 reciprocates within the cylinder 35, the inertia force due to the reciprocating movement of the cylinder 35 is transmitted to the housing 13 via the connecting rod 29, pin 33, crankshaft 28, and bearing 30. Therefore, the housing 13 vibrates in the direction along the center line A1.

The vibration reduction mechanism 54 can suppress vibrations of the housing 13. The vibration reduction mechanism 54 is provided in the space C1. Space C1 is inside the cylinder case 34 and outside the cylinder 35. Specific examples of the vibration reduction mechanism 54 include the following.

(First specific example)
The vibration reduction mechanism 54 includes a mass body 55 and coil springs 56 and 57, as shown in FIGS. 2, 3, and 5. The coil springs 56 and 57 are both compression coil springs in which wire rods are spirally wound. The coil springs 56 and 57 are made of metal, for example steel. The coil springs 56 and 57 are arranged outside the cylinder 35 in the radial direction of the cylinder 35. That is, the coil springs 56 and 57 are arranged in a spiral shape surrounding the cylinder 35. The coil springs 56 and 57 can be expanded and contracted in the direction along the center line A1. The cross-sectional shape of the wire 56A constituting the coil spring 56 and the cross-sectional shape of the wire 56A constituting the coil spring 57 are both circular. For example, the diameter D1 of the wire 56A and the diameter D1 of the wire 57A are the same. The spring constants of the coil springs 56 and 57 are, for example, the same. The maximum inner diameter D2 of the opening 48A is larger than the diameter D1.

The mass body 55 is arranged outside the cylinder 35 in the radial direction centered on the center line A1. The mass body 55 is movable relative to the cylinder 35 in a direction along the center line A1. The mass body 55 is made of metal, for example steel. The mass body 55 has a cylindrical portion 58 and a protrusion 60 that protrudes inward from the inner surface of the cylindrical portion 58 . The protruding portion 60 is provided approximately at the center of the cylindrical portion 58 in the direction along the center line A1. The length L4 of a portion of the cylindrical portion 58 located on one side of the protrusion 60 in the direction along the center line A1 is greater than the length L5 of the protrusion 60. The protruding portion 60 is provided over the entire circumference of the cylindrical portion 58. Protrusion 60 can also be defined as an inwardly directed flange or rib. The inner diameter D3 of the inner peripheral surface 58A of the cylindrical portion 58 is larger than the inner diameter D4 of the protrusion 60. That is, the inner diameter D4 of the protrusion 60 is the smallest among the inner diameters of the mass body 55 in the radial direction of the cylinder 35. The length L6 of the protrusion 60 in the radial direction of the cylinder 35 is smaller than the diameter D1.

For example, the coil springs 56 and 57 have the same outer diameter D5. The inner diameter D3 of the cylindrical portion 58 is greater than or equal to the outer diameter D5 of the coil springs 56 and 57. The cylindrical portion 58 is provided outside the coil springs 56, 57 in the radial direction of the coil springs 56, 57. The inner diameter D4 of the protrusion 60 is smaller than the outer diameter D5 of the coil springs 56 and 57. The inner diameter D4 of the protrusion 60 is larger than the outer diameter D6 of the cylinder 35. The protrusion 60 is provided between the coil spring 56 and the coil spring 57 in the direction along the center line A1. That is, the coil spring 56 and the coil spring 57 are arranged at different positions in the direction along the center line A1. Coil springs 56 and 57 are pressed against protrusion 60. A gap 70 in the radial direction of the cylinder 35 is provided between the cylindrical portion 58 and the inner peripheral surface 34A of the cylinder case 34. The gap 70 is an annular space centered on the center line A1. The inner diameter D11 of the inner peripheral surface 34A is larger than the outer diameter D8 of the cylindrical portion 58.

A gap 66 is provided between the outer peripheral surface 35A of the cylinder 35 and the inner peripheral surface 60A of the protrusion 60. The gap 66 is an annular space centered on the center line A1. The gap 66 has a length L1 in the radial direction of the cylinder 35. The inner circumferential surface 58A of the cylindrical portion 58 and the outer circumferential ends of the coil springs 56 and 57 are arranged with a gap 67 in the radial direction of the cylinder 35 in between. The gap 67 has a length L2 in the radial direction of the cylinder 35. Length L1 is greater than length L2. Furthermore, gaps 69 are provided between the outer peripheral surface 35A of the cylinder 35 and the coil springs 56, 57, respectively. The gap 69 has a length L3 in the radial direction of the cylinder 35. The lengths L1, L2, L3 are
L1>L2+L3
There is a relationship between

Note that the coil springs 56 and 57 may be moved in the radial direction of the cylinder 35. Furthermore, there is a possibility that the mass body 55 is moved in the radial direction of the cylinder 35 with respect to the coil springs 56 and 57. Therefore, both lengths L1 and L2 may vary. In this case, the minimum value of length L1 is greater than the maximum value of length L2.

A snap ring 61 is attached to the inner periphery of the cylinder case 34, and the coil spring 56 is arranged between the protrusion 60 of the mass body 55 and the snap ring 61 in the direction along the center line A1. An annular plate 62 is provided within the cylinder case 34. The coil spring 57 is arranged between the protrusion 60 of the mass body 55 and the plate 62 in the direction along the center line A1. A ring 63 is arranged between the plate 62 and the damper holder 49. Both ends of the cylinder 35 in the direction along the center line A1 are arranged inside the stopper ring 53 and inside the ring 63, respectively. The cylinder 35 is positioned in the radial direction of the cylinder 35 by a stopper ring 53 and a ring 63.

The coil springs 56 and 57 are both placed in the space C1 while receiving a compressive force in the direction along the center line A1. The coil springs 56 and 57 are provided on both sides of the protrusion 60 of the mass body 55 in the direction along the center line A1. The coil spring 56 urges the mass body 55 toward the retainer sleeve 36 . Coil spring 57 urges mass body 55 away from retainer sleeve 36 .

The operation of the vibration reduction mechanism 54 will be explained. When the housing 13 is not vibrating in the direction along the center line A1, the mass body 55 is stopped at a predetermined position in the direction along the center line A1. When the housing 13 vibrates in the direction along the center line A1, the mass body 55 moves in a phase opposite to the direction in which the housing 13 vibrates. For example, when the housing 13 vibrates away from the object 12, the mass body 55 moves toward the retainer sleeve 36 against the urging force of the coil spring 57.

On the other hand, when the housing 13 vibrates toward the object 12, the mass body 55 moves away from the retainer sleeve 36 against the urging force of the coil spring 56. The direction in which the housing 13 vibrates is opposite to the direction in which the mass body 55 moves, and the vibration of the housing 13 is suppressed.

The cylindrical portion 58 of the mass body 55 is arranged outside the coil springs 56 and 57 in the radial direction of the cylinder 35. Further, the length L6 of the protrusion 60 is smaller than the diameter D1. Therefore, the cylindrical portion 58 and the protruding portion 60 of the mass body 55 can be prevented from coming into contact with the cylinder 35. In particular, the protrusion 60 and the outer peripheral surface 35A of the cylinder 35 are not in contact with each other over the entire circumference of the cylinder 35, so that a gap 66 is provided. Therefore, the mass body 55 can be prevented from blocking the first breathing hole 47 and the second breathing hole 48.

Furthermore, so that the mass body 55 does not block the first breathing hole 47 and the second breathing hole 48, there is no need to restrict the range in which the mass body 55 moves in the direction along the center line A1. Therefore, deterioration in the function of the vibration reduction mechanism 54 can be suppressed. Furthermore, there is no need to provide a member that restricts the range in which the mass body 55 moves in the direction along the center line A1. Therefore, an increase in the number of parts can be suppressed. Furthermore, since the gap 66 is provided, the mass body 55 can be prevented from sliding along the outer peripheral surface 35A of the cylinder 35. Therefore, at least one of the mass body 55 or the cylinder 35 can be prevented from being worn out, and generation of abnormal noise can be suppressed.

Furthermore, the maximum inner diameter D2 of the opening 48A and the inner diameter D10 of the first breathing hole 47 are larger than the diameter D1. Therefore, the coil springs 56, 57 can be prevented from blocking at least one of the opening 48A or the first breathing hole 47.

Furthermore, the coil spring 56 is positioned in the radial direction of the cylinder 35 by the frictional force at the contact point between the snap ring 61 and the coil spring 56. The coil spring 57 is positioned in the radial direction of the cylinder 35 by the frictional force at the contact point between the plate 62 and the coil spring 57. By the outer peripheral ends of the coil springs 56, 57 contacting the inner peripheral surface 58A of the cylindrical portion 58 of the mass body 55, the coil springs 56, 57 position the mass body 55 in the radial direction of the cylinder 35, for example, fix the mass body 55. are doing. Therefore, the mass body 55 is prevented from moving in the radial direction of the cylinder 35, and the gap 70 is secured. Therefore, the cylindrical portion 58 can be prevented from coming into contact with the inner circumferential surface 34A of the cylinder case 34.

FIG. 6 is an example in which a part of the mass body 55 shown in FIG. 5 is changed. The length L8 of a portion of the cylindrical portion 58 located on one side of the protrusion 60 in the direction along the center line A1 is smaller than the length L7 of the protrusion 60. Length L8 is smaller than diameter D1. The other configuration of the vibration reduction mechanism 54 shown in FIG. 6 is the same as the configuration of the vibration reduction mechanism 54 shown in FIG. 5. The vibration reduction mechanism 54 shown in FIG. 6 can obtain the same effect as the vibration reduction mechanism 54 shown in FIG. 5.

(Second specific example)
A second specific example of the vibration reduction mechanism 54 in FIG. 2 is shown in FIG. The mass body 55 has a cylindrical portion 58 and a protrusion 68 that protrudes from the outer peripheral surface 58B of the cylindrical portion 58. The cylindrical portion 58 is arranged between the cylinder 35 and the coil springs 56 and 57 in the radial direction of the cylinder 35. That is, the coil springs 56 and 57 are provided outside the cylindrical portion 58 in the radial direction of the cylinder 35.

The inner diameter D12 of the inner peripheral surface 58A of the cylindrical portion 58 is larger than the outer diameter D6 of the cylinder 35. The inner diameter D12 is the smallest inner diameter of the mass body 55. A gap 71 in the radial direction of the cylinder 35 is provided between the cylindrical portion 58 and the outer peripheral surface 35A of the cylinder 35. The gap 71 is an annular space centered on the center line A1. The protruding portion 68 protrudes from the outer surface of the cylindrical portion 58 and is provided over the entire circumference of the cylindrical portion 58 . The protruding portion 68 is provided at a midway portion of the cylindrical portion 58 in the direction along the center line A1. Protrusion 68 can be defined as an outwardly facing flange or rib. The length L9 of a portion of the cylindrical portion 58 located on one side of the protrusion 60 in the direction along the center line A1 is greater than the length L10 of the protrusion 60.

The outer diameter D7 of the protruding portion 68 is larger than the outer diameter D8 of the cylindrical portion 58. The outer diameter D8 of the cylindrical portion 58 is smaller than the inner diameter D9 of the coil springs 56 and 57. The outer diameter D7 of the protrusion 68 is larger than the inner diameter D9 of the coil springs 56, 57 and smaller than the outer diameter D5 of the coil springs 56, 57. The outer diameter D5 is smaller than the inner diameter D11. The protrusion 68 is provided between the coil spring 56 and the coil spring 57 in the direction along the center line A1. The coil springs 56 and 57 are pressed against the protrusion 68. A gap 72 is provided between the protrusion 68 and the inner peripheral surface 34A of the cylinder case 34. The gap 72 is an annular space centered on the center line A1.

The other configuration of the vibration reduction mechanism 54 shown in FIG. 7 is the same as the configuration of the vibration reduction mechanism 54 shown in FIG. 5. The vibration reduction mechanism 54 shown in FIG. 7 suppresses the vibration of the housing 13 based on the same principle as the vibration reduction mechanism 54 shown in FIG. 5. The coil spring 56 is restrained from moving in the radial direction of the cylinder 35 due to the frictional force at the contact point with the snap ring 61. The coil spring 57 is restrained from moving in the radial direction of the cylinder 35 due to the frictional force at the contact point with the plate 62.

The mass body 55 is positioned in the radial direction of the cylinder 35 by the inner circumferential ends of the coil springs 56 and 57 contacting the outer circumferential surface 58B of the cylindrical portion 58. The outer peripheral surface 35A of the cylinder 35 and the cylindrical portion 58 are not in contact with each other, and an annular gap 71 is provided between the outer peripheral surface 35A of the cylinder 35 and the cylindrical portion 58. Therefore, it is possible to prevent the mass body 55 from blocking at least one of the first breathing hole 47 and the second breathing hole 48 . Therefore, the same effect as the vibration reduction mechanism 54 of FIG. 5 can be obtained. Further, the cylindrical portion 58 of the mass body 55 is arranged inside the coil springs 56 and 57 in the radial direction of the cylinder 35. The outer diameter D7 of the protrusion 68 is less than the outer diameter D5 of the coil springs 56 and 57. The protruding portion 68 is not in contact with the inner circumferential surface 34A, and a gap 72 is provided. Therefore, the protruding portion 68 of the mass body 55 can be prevented from contacting the inner peripheral surface 34A of the cylinder case 34.

(Third specific example)
A third specific example of the vibration reduction mechanism 54 in FIG. 2 is shown in FIG. 8. The mass body 55 has a cylindrical portion 58 and a protruding portion 60 that protrudes from the cylindrical portion 58 . The protruding portion 60 is provided at a portion of the cylindrical portion 58 that is closest to the plate 62 in the direction along the center line A1. A holding groove 58C is provided on the inner peripheral surface 58A of the cylindrical portion 58. The holding groove 58C is provided in a spiral shape over the entire circumference of the inner peripheral surface 58A. A portion of the coil spring 56 is provided between the cylinder 35 and the cylindrical portion 58 in the radial direction of the cylinder 35. The outer peripheral end of the coil spring 56 is located in the holding groove 58C. The mass body 55 does not come off the coil spring 56. The end of the coil spring 56 that is closest to the plate 62 in the direction along the center line A1 is fixed so as not to move in the radial direction of the cylinder 35 and in the direction along the center line A1.

The vibration reduction mechanism 54 shown in FIG. 8 does not include the coil spring 57. The other configuration of the vibration reduction mechanism 54 shown in FIG. 8 is the same as the configuration of the vibration reduction mechanism 54 shown in FIG. 5. The vibration reduction mechanism 54 shown in FIG. 8 suppresses the vibration of the housing 13 based on the same principle as the vibration reduction mechanism 54 shown in FIG. 5 except for the action based on the coil spring 57. Therefore, the same effect as the vibration reduction mechanism 54 shown in FIG. 5 can be obtained.

(Fourth specific example)
A fourth specific example of the vibration reduction mechanism 54 in FIG. 2 is shown in FIG. The mass body 55 has a cylindrical portion 58 and a protruding portion 60 that protrudes from the cylindrical portion 58 . The protruding portion 60 is provided at a portion of the cylindrical portion 58 that is farthest from the plate 62 in the direction along the center line A1. A holding groove 58C is provided on the inner peripheral surface 58A of the cylindrical portion 58. The holding groove 58C is provided in a spiral shape over the entire circumference of the inner peripheral surface 58A. A portion of the coil spring 57 is provided between the cylindrical portions 58 in the radial direction of the cylinder 35 . The outer peripheral end of the coil spring 57 is located in the holding groove 58C. The mass body 55 does not come off the coil spring 57.

The end of the coil spring 57 that is closest to the ring 63 in FIG. 2 in the direction along the center line A1 is fixed so as not to move in the radial direction of the cylinder 35 and in the direction along the center line A1. . The vibration reduction mechanism 54 shown in FIG. 9 does not include the coil spring 56. The other configuration of the vibration reduction mechanism 54 shown in FIG. 8 is the same as the configuration of the vibration reduction mechanism 54 shown in FIG. 5. The vibration reduction mechanism 54 shown in FIG. 9 suppresses the vibration of the housing 13 based on the same principle as the vibration reduction mechanism 54 shown in FIG. 5 except for the action based on the coil spring 56. Therefore, the same effect as the vibration reduction mechanism 54 shown in FIG. 5 can be obtained.

[supplementary explanation]
An example of the technical meaning of the matters described in the embodiments is as follows. Hammer drill 10 is an example of a working machine. The cylinder 35 is an example of a cylindrical cylinder. The center line A1 is an example of the center line of the cylinder. The striking section 45 is an example of a striking section. Pressure chamber B1 is an example of a gas chamber. The first breathing hole 47, the second breathing hole 48, and the opening 48A are all examples of breathing holes. The mass body 55 is an example of a mass body. The coil springs 56 and 57 are examples of elastic members. The electric motor 17 is an example of a drive source. Piston 44 is an example of a piston. The cylinder case 34 is an example of a cylindrical case. The cylindrical portion 58 is an example of a cylindrical portion. Both protrusions 60 and 68 are examples of protrusions. The retainer sleeve 36 is an example of a tool holding section. The tip tool 11 is an example of a tool.

The gaps 66 and 71 are examples of first gaps. The lengths L4 and L8 are examples of "lengths in the center line direction of the cylindrical portion." The lengths L5 and L7 are examples of "the length of the protrusion in the center line direction." The gap 67 is an example of a second gap. The length L2 is an example of the length of the gap provided between the cylindrical portion and the elastic member. The gap 69 is an example of a third gap. The length L3 is an example of the length of the gap provided between the cylinder and the elastic member.

The inner circumferential surface 58A is an example of the inner circumferential surface of the cylindrical portion. The outer peripheral surface 35A is an example of the outer peripheral surface of the cylinder. The outer circumferential surface 58B is an example of the outer circumferential surface of the cylindrical portion. The first breathing hole 47 is an example of a first breathing hole. Wire rods 56A and 57A are examples of wire rods. The diameter D1 of the wire rods 56A and 57A is an example of the diameter of the wire rods. The inner diameter D10 is an example of the inner diameter of the first breathing hole. The second breathing hole 48 and the opening 48A are an example of the second breathing hole. The maximum inner diameter D2 is an example of the opening diameter of the second breathing hole. The protruding portion 60 is an example of a small diameter portion. The inner diameter D4 is an example of the inner diameter of the small diameter portion. The cylindrical portion 58 shown in FIG. 7 is an example of a small diameter portion. The inner diameter D12 is an example of the inner diameter of the small diameter portion.

The embodiment also discloses a work machine having the following configuration.

A housing, a cylindrical cylinder provided inside the housing, a piston provided inside the cylinder and reciprocated in the direction of the center line of the cylinder, and a drive provided inside the housing. a converting mechanism that converts the rotational force of the driving source into reciprocating force of the piston; a striking section provided inside the cylinder and movable in the direction of the center line; a gas chamber that is provided between the piston and the striking part and applies an operating force in the center line direction to the striking part; and a gas chamber that penetrates the cylinder in a radial direction and connects the inside of the cylinder and the outside of the cylinder. a breathing hole that connects the cylinder, a mass body that is provided outside the cylinder and is movable in the direction of the center line; A working machine, comprising: an elastic member that is movably supported in a linear direction and that forms the radial gap between the mass body and the cylinder.

The work machine is not limited to the above-described embodiment, and various changes can be made without departing from the spirit of the work machine. For example, the working machine may be one in which the tool holder does not rotate around the center line, as shown in FIG. 1, or one in which the tool holder is rotatable around the center line. An example of a working machine in which a tool holder can rotate around a center line is disclosed in Japanese Patent Application Laid-Open No. 2019-177459. The working machine may be either a hammer drill or a hammer driver. The work equipment is one in which the center line of the rotating shaft of the electric motor and the center line of the cylinder intersect with each other as shown in Figure 1, or the center line of the rotating shaft of the electric motor and the center line of the cylinder are may be arranged in parallel. An example of a working machine in which the center line of the rotating shaft of the electric motor and the center line of the cylinder are arranged in parallel is disclosed in JP-A-2019-177459. The conversion mechanism that converts the rotational force of the drive source into the reciprocating force of the piston may be a cam mechanism instead of the crank mechanism shown in FIG. An example of a conversion mechanism including a cam mechanism is described in Japanese Patent Application Laid-open No. 2019-177459.

The tool holding portion may be called a chuck, holder, box, extension, or anvil instead of the retainer sleeve.The elastic member may be a tension coil spring instead of the compression coil spring. The elastic member that positions the mass body in the radial direction of the cylinder is fixed within the case so as not to move in the radial direction of the cylinder.

Structures for fixing the elastic member include welding, soldering, and holders. The holders are provided in an annular shape or at intervals in the circumferential direction about the center line. The elastic member is prevented from moving in the radial direction of the cylinder by contacting the holder. The power supply unit that supplies power to the electric motor may be either an AC power supply or a DC power supply. The DC power source includes a battery pack that can be attached to and removed from the housing. As the drive source, a hydraulic motor, a pneumatic motor, or an engine can be used instead of the electric motor.

DESCRIPTION OF SYMBOLS 10... Hammer drill, 11... Tip tool, 17... Electric motor, 34... Cylinder case, 35... Cylinder, 35A... Outer peripheral surface, 36... Retainer sleeve, 44... Piston, 45... Hitting part, 47... First breathing hole, 48 ...Second breathing hole, 48A...Opening, 55...Mass body, 56, 57...Coil spring, 56A, 57A...Wire, 58...Cylindrical part, 58A...Inner peripheral surface, 58B...Outer peripheral surface, 60, 68...Protrusion Part, 66, 69, 71...Gap, A1...Center line, B1...Pressure chamber, D1...Diameter, D2...Maximum inner diameter, D4, D10, D12...Inner diameter, L1, L2, L3, L4, L5, L7, L8 …length

Claims (15)

a cylindrical cylinder,
a piston provided inside the cylinder and reciprocated in the direction of the center line of the cylinder;
a striking part provided inside the cylinder and operable in the direction of the center line;
a gas chamber provided inside the cylinder between the piston and the striking part and applying an operating force in the centerline direction to the striking part;
a breathing hole that radially penetrates the cylinder and connects the inside of the cylinder and the outside of the cylinder;
A work machine having
a mass body provided outside the cylinder and movable in the direction of the center line;
an elastic member provided outside the cylinder to support the mass body so as to be movable in the center line direction, and to form a first gap in the radial direction between the mass body and the cylinder;
has
The mass body has a small diameter portion having a minimum inner diameter in the radial direction,
A working machine, wherein the first gap in the radial direction is provided between the small diameter portion and the cylinder. The mass body has a cylindrical portion surrounding the outside of the cylinder in the radial direction,
The working machine according to claim 1, wherein the elastic member is provided between the cylinder and the cylindrical portion in the radial direction. a drive source that reciprocates the piston in the direction of the center line;
a cylindrical case including the mass body, the elastic member, and the cylinder therein;
The work machine according to claim 1, further comprising:. a cylindrical cylinder,
a piston provided inside the cylinder and reciprocated in the direction of the center line of the cylinder;
a striking part provided inside the cylinder and operable in the direction of the center line;
a gas chamber provided inside the cylinder between the piston and the striking part and applying an operating force in the centerline direction to the striking part;
a breathing hole that radially penetrates the cylinder and connects the inside of the cylinder and the outside of the cylinder;
A work machine having
a mass body provided outside the cylinder and movable in the direction of the center line;
an elastic member provided outside the cylinder to support the mass body so as to be movable in the center line direction, and to form a first gap in the radial direction between the mass body and the cylinder;
has
The mass body is
a cylindrical portion provided to surround the outer periphery of the cylinder;
a protrusion that receives a biasing force in the centerline direction from the elastic member;
has
In the work machine, the length of the cylindrical portion in the centerline direction is greater than the length of the protrusion in the centerline direction. The protruding portion protrudes inward in the radial direction from the inner circumferential surface of the cylindrical portion,
The working machine according to claim 4, wherein the elastic member is provided between an outer circumferential surface of the cylinder and an inner circumferential surface of the cylindrical portion in the radial direction. The first gap is provided between the protrusion and the cylinder,
a second gap provided between the cylindrical portion and the elastic member;
a third gap provided between the cylinder and the elastic member;
further comprising;
a length L1 of the first gap in the radial direction;
a length L2 of the second gap in the radial direction;
a length L3 of the third gap in the radial direction;
The relationship between
L1>L2+L3
The working machine according to claim 5. The protruding portion protrudes outward in the radial direction from the outer circumferential surface of the cylindrical portion,
The working machine according to claim 4, wherein the elastic member is provided outside the cylindrical portion in the radial direction. The working machine according to any one of claims 4 to 7, wherein the protruding portion is provided at an intermediate portion of the cylindrical portion in the direction of the center line. The working machine according to any one of claims 1 to 8, wherein the elastic member is a helical coil spring provided surrounding the outer periphery of the cylinder. The working machine according to claim 9, wherein the coil spring has a circular cross-sectional shape in a plane along the centerline direction. A tool holding part that holds a tool to which a striking force is transmitted from the striking part is further provided,
The breathing hole includes a first breathing hole that is blocked from the gas chamber when the tool is separated from the object;
The working machine according to claim 10, wherein the diameter of the wire constituting the coil spring is smaller than the inner diameter of the first breathing hole. The working machine according to any one of claims 1 to 11, wherein a plurality of the breathing holes are provided spaced apart in a circumferential direction of the cylinder. The breathing hole includes a second breathing hole that adjusts the pressure of the gas chamber,
The working machine according to claim 10, wherein the diameter of the wire constituting the coil spring is smaller than the opening diameter of the second breathing hole. The elastic member is configured such that the small diameter portion of the mass body and the cylinder are not in contact with each other over the entire circumference of the cylinder, so that the first gap is provided over the entire circumference of the cylinder. A working machine according to any one of claims 1 to 3 . a cylindrical cylinder,
a piston provided inside the cylinder and reciprocated in the direction of the center line of the cylinder;
a striking part provided inside the cylinder and operable in the direction of the center line;
a gas chamber provided inside the cylinder between the piston and the striking part and applying an operating force in the center line direction to the striking part;
a breathing hole that radially penetrates the cylinder and connects the inside of the cylinder and the outside of the cylinder;
A work machine having
a mass body provided outside the cylinder and movable in the direction of the center line;
an elastic member provided outside the cylinder to support the mass body so as to be movable in the center line direction, and to form a first gap in the radial direction between the mass body and the cylinder;
has
The mass body has a cylindrical portion surrounding the outside of the cylinder in the radial direction,
In the working machine, the elastic member is provided between the cylinder and the cylindrical portion in the radial direction.

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