WO2015133198A1

WO2015133198A1 - Striking tool

Info

Publication number: WO2015133198A1
Application number: PCT/JP2015/051866
Authority: WO
Inventors: 駒崎　義一
Original assignee: 日立工機株式会社
Priority date: 2014-03-03
Filing date: 2015-01-23
Publication date: 2015-09-11

Abstract

Provided is a striking tool that can stabilize the striking force during a strike regardless of the magnitude of the repelling force applied to the striking element during the previous strike. A striking tool (10) that reciprocally moves a piston (28) along an axis line (A1) and that strikes with a striking element (29) using the pressure of an air chamber (C1) comprises: a cylinder (27) that movably accommodates the piston (28) and the striking element (29); an intermediate striking element (37) that moves along the axis line (A1) by the transmission of the striking force from the striking element (29) and that transmits a striking force to a distal end tool (43); an air hole (45) that is provided in the cylinder (27) and that allows air to enter and exit the air chamber (C1) in response to the movement of the piston (28); and a pressure receiving surface (46) that is provided on the striking element (29) and that receives the air pressure. The pressure receiving surface (46) abutting the intermediate striking element (37) is in the area where the air hole (45) is disposed in a direction along the axis line (A1) when the intermediate striking element (37) is in the position nearest the striking element (29) in the direction of the axis line (A1).

Description

Impact tool

The present invention relates to a striking tool used for crushing roads and buildings, and in particular, reciprocating a piston in a direction along an axis to increase the pressure of a fluid chamber formed between the piston and the striking element. The present invention relates to a striking tool that applies striking force to the striking element.

Conventionally, there has been known a striking tool that reciprocates the piston in the direction along the axis, and increases the pressure of the fluid chamber formed between the piston and the striking element to apply a striking force to the striking element. A tool is described in Patent Document 1. The striking tool described in Patent Document 1 has a cylindrical crankcase and a cylindrical cylinder case, and the crankcase and the cylinder case are concentrically connected and fixed. A cylindrical cylinder is provided in the crankcase and the cylinder case, and the piston is accommodated in the cylinder so as to be movable in the direction along the axis. Moreover, the motion conversion part which converts the rotational force of a power source into a reciprocating motion force is provided, and the piston is connected with the motion conversion part. *

Further, a striker is provided in the cylinder, and the striker is movable in the direction along the axis within the cylinder. In the cylinder, a fluid chamber is formed between the piston and the striker. In addition, a breathing hole that penetrates the cylinder in the radial direction and communicates with the fluid chamber is provided. Furthermore, a cylindrical tool holder is provided from the inside to the outside of the cylinder case. The tool holder is arranged concentrically with the cylinder, and an intermediate striker is provided in the tool holder. The intermediate striker is movable in a direction along the axis, and a tip tool is attached to the tool holder. *

In the impact tool described in Patent Document 1, the rotational force of the power source is converted into the reciprocating force of the piston. The piston moves in a direction away from the striker, and the breathing hole becomes negative pressure. Then, the striker moves in a direction approaching the piston, and the breathing hole is closed by the striker. Next, when the piston moves in a direction approaching the striker, the pressure in the air chamber increases, and an impact force is applied to the striker. This striking force is transmitted to the tip tool via the intermediate striking element. When the striker strikes the intermediate striker, the breathing hole is opened and the pressure in the fluid chamber decreases. Thereafter, the piston and the striker move in a direction away from the intermediate striker in preparation for the next strike. Thus, in the impact tool described in Patent Document 1, the striker opens and closes the breathing hole to adjust the pressure of the fluid chamber, and the striker descends to strike the intermediate striker, After the previous hit, the operation of raising the striker in preparation for the next hit is switched.

JP 2002-127043 A

In the impact tool described in the above-mentioned Patent Document 1, if the repulsive force at the first impact is different, the amount by which the impactor rises in the direction along the axis changes after the first impact. That is, if the repulsive force at the time of the first impact is different, the air pressure of the air chamber is also different when the striker is subsequently raised. Then, when the piston is lowered and the second impact is performed, the amount of the impactor descending at the second impact is different, and the impact force applied to the intermediate impactor is also different. *

However, the impact tool described in Patent Document 1 has the breathing hole fully opened at the time of the second impact, and therefore the pressure of the air chamber after the second impact, that is, the residual pressure, is also different. Thereafter, the position where the piston and the striker rise and the striker rises depends on the residual pressure in the air chamber. This is because the residual pressure in the air chamber becomes a force that prevents the striker from rising. As a result, when the piston descends to perform the third impact, the air pressure in the air chamber is different, and the impact force may become unstable. *

An object of the present invention is to provide a striking tool capable of obtaining a stable striking force regardless of the striking force at the time of the previous striking.

One embodiment is a striking tool that reciprocates a piston in an axial direction to increase a pressure of a fluid chamber formed between the piston and the striking element to apply a striking force to the striking element, A cylinder that accommodates the piston and the striking element so as to be movable in the axial direction, and a striking force is transmitted from the striking element to operate in the axial direction, and the striking force is transmitted to a tip tool that contacts the object. An intermediate striker, a breathing hole provided in the cylinder and allowing fluid to enter and exit from the fluid chamber according to the operation of the piston; a pressure receiving surface provided in the striker and receiving the pressure of the fluid chamber; The pressure receiving surface of the striker that is in contact with the intermediate striker is in the axial direction in a state where the intermediate striker is positioned at a position closest to the striker in the axial direction. Position of breathing hole Located within.

According to the striking tool of the present invention, when the pressure of the fluid chamber is different at the previous striking and the amount of movement of the striking member at the previous striking is different, the opening area of the breathing hole opened by the striking member changes. For this reason, the pressure in the fluid chamber after the previous strike is the same, and when the striker is moved after the previous strike, the striker moves to the same position in the direction along the axis, and the impact force generated at the next strike Is stable.

It is front sectional drawing of the striking tool in Embodiment 1 of this invention. It is a partial front sectional view of the impact tool shown in FIG. It is a partial front sectional view of the impact tool shown in FIG. It is a partial front sectional view of the impact tool shown in FIG. It is a partial front sectional view of the impact tool shown in FIG. It is a partial front sectional view of the impact tool shown in FIG. (A) is an expanded sectional view which shows the principal part of FIG. 3, (B) is an expanded sectional view which shows the principal part of FIG. FIG. 2 is a front cross-sectional view illustrating an action of preventing an impact of the impact tool shown in FIG. 1. It is front sectional drawing which shows the example of a change of the breathing hole provided in the cylinder of the impact tool shown in FIG. It is a partial front sectional view of an impact tool of a comparative example. It is a partial front sectional view of an impact tool of a comparative example. It is a partial front sectional view of an impact tool of a comparative example. It is a partial front sectional view of an impact tool of a comparative example. (A) is a time chart which shows the behavior of the impact tool of this invention, (B) is a time chart which shows the behavior of the impact tool of a comparative example. (A) is a time chart which shows the behavior of the impact tool of this invention, (B) is a time chart which shows the behavior of the impact tool of a comparative example. It is front sectional drawing of the impact tool in Embodiment 2 of this invention. FIG. 17 is a partial front sectional view of the impact tool shown in FIG. 16.

(Embodiment 1) Hereinafter, an impact tool to which the present invention is applied will be described in detail with reference to the drawings. Note that components having the same function are denoted by the same reference symbols throughout the drawings for describing the first embodiment, and the repetitive description thereof will be omitted.

A striking tool 10 shown in FIG. 1 includes a housing 11 and a cylinder case 12 continuous with the housing 11. An electric motor 13 is provided in the housing 11. The electric motor 13 is a power source that converts electric energy into kinetic energy of the output shaft 14. A pinion gear 15 is provided on the output shaft 14 of the electric motor 13. An intermediate shaft 16 is provided in the housing 11, and a first gear 17 and a second gear 18 are provided on the intermediate shaft 16. The number of teeth of the first gear 17 is larger than the number of teeth of the pinion gear 15 and the number of teeth of the second gear 18. The first gear 17 meshes with the pinion gear 15. A crankshaft 19 is provided in the housing 11, and the crankshaft 19 has a third gear 20. The number of teeth of the third gear 20 is larger than the number of teeth of the second gear 18, and the third gear 20 meshes with the second gear 18. The crankshaft 19 has a pin 21 at a position eccentric from the rotation center line.

Two handles 22 and 23 are concentrically fixed to the outer wall of the housing 11, and a lever 24 is provided on one handle 23. The lever 24 is operated by an operator. A power cable 25 is connected to the handle 23, and the power cable 25 is connected to a commercial power source. When the lever 24 is operated, power is supplied to the electric motor 13 via the power cable 25, and the output shaft 14 rotates. The rotational force of the output shaft 14 is transmitted to the third gear 20 via the first gear 17 and the second gear 18, and the crankshaft 19 rotates.

When the reduction gear 26 is configured by the first gear 17, the second gear 18, and the third gear 20, and the rotational force is transmitted from the output shaft 14 to the crankshaft 19, the rotational speed of the crankshaft 19 is the rotational speed of the output shaft 14. And the rotational force is amplified.

The cylinder case 12 has a cylindrical shape, and a cylindrical cylinder 27 is provided in the cylinder case 12. The cylinder 27 is made of metal, and the cylinder case 12 and the cylinder 27 are arranged concentrically. In the front view of the impact tool 10, the axis A 1 of the cylinder case 12 and the cylinder 27 is orthogonal to the rotation center line B 1 of the output shaft 14 of the electric motor 13. A piston 28 is accommodated in the cylinder 27, and the piston 28 is operable in a direction along the axis A1. A connecting rod 48 is connected to the piston 28, and the connecting rod 48 is rotatably connected to the pin 21. For this reason, when the crankshaft 19 rotates, the piston 28 reciprocates in the cylinder 27 in the direction along the axis A1.

Further, a striker 29 is provided in the cylinder 27, and the striker 29 is movable in a direction along the axis A1. An air chamber C 1 is formed in the cylinder 27 between the end face 28 a of the piston 28 and the striker 29. Further, the holder 30 is fixed to the end of the cylinder case 12 opposite to the housing 11 in the direction along the axis A1. The holder 30 is fixed to the cylinder case 12 using a screw member 31 that is a fixing element. The holder 30 has a support hole 32, and the holder 30 is disposed concentrically with the cylinder 27.

A sleeve 33 is provided from the support hole 32 of the holder 30 to the inside of the cylinder case 12. The sleeve 33 is made of metal, and the sleeve 33 includes a cylindrical portion 34 and a flange portion 35 projecting outward from the outer peripheral surface of the cylindrical portion 34 in the radial direction of the cylindrical portion 34. The flange portion 35 is disposed in the support hole 32 of the holder 30, and the cylinder portion 34 is disposed in the cylinder case 12. In addition, a damper 36 is interposed between the flange portion 35 and the cylinder case 12 in a direction along the axis A1. The damper 36 is integrally formed of a rubber-like elastic material. The sleeve 33 is movable in a direction along the axis A 1 within a range where the damper 36 is elastically deformed.

An intermediate striker 37 is provided from the cylinder 27 to the holder 30. The intermediate striker 37 is made of metal, and the intermediate striker 37 includes a columnar small-diameter portion 38 and a large-diameter portion 39 that is continuous with the small-diameter portion 38. The outer diameter of the large diameter portion 39 is larger than the outer diameter of the small diameter portion 38, and the small diameter portion 38 is disposed in the cylinder portion 34 and the cylinder 27. The large diameter portion 39 is disposed in the support hole 32 of the holder 30. The outer diameter of the large diameter portion 39 is larger than the inner diameter of the cylindrical portion 34. The intermediate striker 37 is movable in the direction along the axis A1 with respect to the sleeve 33. When the intermediate striker 37 moves toward the inside of the cylinder case 12, the large diameter portion 39 comes into contact with the flange portion 35. The sleeve 33 stops. *

On the other hand, a stopper 40 is provided at the end of the holder 30 opposite to the cylinder case 12, and a chuck 41 is attached to the stopper 40. The chuck 41 is cylindrical. The stopper 40 is provided with a shaft hole 42, and the inner diameter of the shaft hole 42 is smaller than the inner diameter of the support hole 32 of the holder 30. When the intermediate striker 37 moves in the direction along the axis A 1 so as to approach the chuck 41, the large diameter portion 39 comes into contact with the stopper 40 and the intermediate striker 37 stops.

Further, the chuck 41 holds a tip tool 43. The tip tool 43 is formed by molding a metal material into a rod shape, and the tip tool 43 is arranged from the inside of the support hole 32, the shaft hole 42 and the chuck 41 to the outside of the chuck 41. An end 44 on the outside of the chuck 41 in the tip tool 43 has a wedge shape. The tip tool 43 is movable in the direction along the axis A 1, and the portion of the tip tool 43 disposed in the support hole 32 contacts the intermediate striker 37.

Further, a plurality of breathing holes 45 penetrating the cylinder 27 in the radial direction are provided. A space D1 is formed between the cylinder 27 and the cylinder case 12, and the breathing hole 45 connects the space D1 and the air chamber C1. The breathing hole 45 is a passage through which air as a fluid enters and exits the air chamber C1. The space D1 communicates with the outside of the cylinder case 12. The opening size of the breathing hole 45 in the direction along the axis A 1 is longer than the opening size in the circumferential direction of the cylinder 27. That is, when the breathing hole 45 is unfolded in a front view, the breathing hole 45 has an elliptical shape or a track shape, the major axis of the breathing hole 45 is arranged in the direction along the axis A1, and the minor axis of the breathing hole 45 is the circle of the cylinder 27. Arranged along the circumferential direction. The plurality of breathing holes 45 have the same dimension in the direction along the axis A1 and the same arrangement area in the direction along the axis A1. *

Further, the striker 29 has a cylindrical shape, and the striker 29 is provided with a pressure receiving surface 46 that forms an air chamber C1. The pressure receiving surface 46 is an end surface perpendicular to the axis A1, and the pressure receiving surface 46 receives the pressure of the air chamber C1. The striker 29 has a flat end surface 29 a on the side opposite to the pressure receiving surface 46. The end surface 29a is at a position opposite to the pressure receiving surface 46 in the direction along the axis A1. Further, in a state where the intermediate striker 37 is located closest to the striker 29 in the direction along the axis A1 and the striker 29 is in contact with the intermediate striker 37, the pressure receiving surface 46 is along the axis A1. It is located in the arrangement area of the breathing hole 45 in the direction. *

Here, “the intermediate striker 37 is positioned closest to the striker 29 in the axial direction” means the position of the intermediate striker 37 where the large-diameter portion 39 is in contact with the flange portion 35 and stopped. To do. And the pressure receiving surface 46 is located in the arrangement | positioning area | region of the breathing hole 45 in the direction along the axis A1 in the state which the pressure of the air chamber C1 raised and the striker 29 struck the intermediate striker 37. That is, the breathing hole 45 is partially opened in the direction along the axis A1 and is not fully opened.

The striking tool 10 according to the present embodiment has the axis A1 so that the pressure receiving surface 46 is located in the arrangement region of the breathing hole 45 in the direction along the axis A1 when the striking element 29 strikes the intermediate striking element 37. Standards such as the size of the intermediate striker 37 in the direction along the axis, the size of the striker 29 in the direction along the axis A1, and the size of the arrangement region of the breathing hole 45 in the direction along the axis A1 are set. Note that whether or not the pressure-receiving surface 46 is located within the arrangement region of the breathing hole 45 in the direction along the axis A1 is related to the hardness of the object W1 in addition to the above conditions. Set the above standards. *

Next, an example in which the worker uses the impact tool 10 will be described. First, when the end portion 44 of the tip tool 43 is pressed against the object W1 and the lever 24 is operated, the output shaft 14 of the electric motor 13 rotates and the piston 28 reciprocates in the cylinder 27 in the direction along the axis A1. . That is, the rotational force of the output shaft 14 is converted into the reciprocating power of the piston 28.

When the piston 28 rises, the pressure in the air chamber C1 becomes lower than the pressure in the space D1, and the air in the space D1 passes through the breathing hole 45 and is sucked into the air chamber C1, and the striker 29 rises. . The movement of the piston 28 means that the piston 28 moves in a direction along the axis A1 so as to approach the crankshaft 19. Raising the striker 29 means moving in a direction away from the intermediate striker 37 in the direction along the axis A1. *

When the striker 29 rises, the breathing hole 45 is closed by the striker 29 and air is not sucked into the air chamber C1. When the piston 28 reaches the top dead center and the piston 28 descends from the top dead center, the pressure in the air chamber C1 rises and a striking force is applied to the striker 29 according to the pressure in the air chamber C1. . For this reason, the striker 29 descends in a direction approaching the intermediate striker 37, and the striker 29 collides with the intermediate striker 37. The striking force applied to the intermediate striking element 37 is transmitted to the object W1 via the tip tool 43, and the object W1 is crushed. *

The breathing hole 45 is opened immediately before the striker 29 strikes the intermediate striker 37, and until the piston 28 reaches the bottom dead center, the air in the air chamber C1 passes through the breathing hole 45 and is discharged into the space D1. The When the striking force is transmitted from the intermediate striker 37 to the tip tool 43 and the piston 28 reaches the bottom dead center, the piston 28 moves from the bottom dead center toward the top dead center. Thereafter, while the output shaft 14 of the electric motor 13 is rotating, the piston 28 is repeatedly raised and lowered, and the striker 29 is raised and lowered. Therefore, the striking force of the striker 29 is intermittently transmitted to the tip tool 43 via the intermediate striker 37.

By the way, if the striker 29 strikes the intermediate striker 37 in a state where the tip tool 43 is pressed against the object W1, a repulsive force is generated. For this reason, the amount that rises after the striker 29 strikes the intermediate striker 37 for the first time is an amount corresponding to the pressure of the air chamber C1 and the repulsive force. Specifically, the greater the repulsion force when the striker 29 strikes the intermediate striker 37 for the first time, the greater the amount that the striker 29 rises after hitting the intermediate striker 37. *

For example, when the hardness of the strike surface of the object W1 is the reference value, the striker 29 strikes the intermediate striker 37 for the first time, and then the end surface 29a reaches the reference position E0 as shown in FIG. To rise. On the other hand, when the hardness of the striking surface of the object W1 is higher than the reference value, the striking element 29 strikes the intermediate striking element 37 for the first time, and then the end surface 29a is above the reference position E0. The first position E1 is reached. Both the reference position E0 and the first position E1 are positions in the direction along the axis A1. The first position E1 is closer to the piston 28 at the top dead center by the difference dy than the reference position E0.

When the striker 29 is lowered and the second strike is performed after the first strike, the pressure in the air chamber C1 when the striker 29 with the end face 29a at the first position E1 is lowered is the end face 29a. It becomes higher than the pressure of the air chamber C1 when the striker 29 at the reference position E0 is lowered. This is because the compression rate due to the lowering of the piston 28 increases as the striker 29 stops at a position closer to the piston 28. For this reason, the striking force when the striker 29 with the end face 29a at the first position E1 descends to perform the second strike is the second strike of the striker 29 with the end face 29a at the reference position E0. It becomes larger than the striking force when performing the hit. *

As a result, when the striker 29 is lowered and the second blow is performed as shown in FIG. 3, the area where the breathing hole 45 is opened is the striker 29 having the end surface 29 a at the first position E1. The case becomes larger than the case where the striker 29 having the end surface 29a at the reference position E0 is lowered.

For this reason, the amount of air discharged from the air chamber C1 to the space D1 is lower when the striker 29 with the end surface 29a at the first position E1 is lowered when the striker 29 with the end surface 29a at the reference position E0 is lowered. More than if you did. Accordingly, the pressure in the air chamber C1 after the second impact is made when the striker 29 whose end face 29a is at the first position E1 is lowered and when the striker 29 whose end face 29a is at the reference position E0 is lowered. It will be the same as the case. *

Then, after the second impact is finished, the piston 28 rises from the bottom dead center shown in FIG. 3, the air chamber C1 becomes negative pressure, and the striker 29 operates in a direction approaching the piston 28. Then, before the second impact, regardless of whether the end face 29a of the impactor 29 shown in FIG. 2 is at the reference position E0 or the first position E1, the impactor 29 rising after the second impact is As shown in FIG. 4, the end face 29a reaches the same reference position E0. That is, the pressure in the air chamber C1 before the third impact is the same regardless of the position of the striker 29 before the second impact. Therefore, regardless of the previous impact, that is, the second impact performed by the lowering of the piston 28 shown in FIG. The hitting force is stabilized.

Further, the operation of the impact tool 10 when the hardness of the impact surface of the object W1 is lower than the reference value will be described with reference to FIGS. For example, when the hardness of the striking surface of the object W1 is lower than the reference value, when the striker 29 strikes the intermediate striker 37 for the first time, the end face 29a is below the reference position E0 as shown in FIG. The second position E2 is reached. The second position E2 is also a position in the direction along the axis A1. In FIG. 5, the second position E2 is far from the reference position E0 by the difference dy with respect to the piston 28 at the top dead center. This is because the repulsive force when the hardness of the striking surface of the target object W1 is lower than the reference value is smaller than the repulsive force when the hardness of the striking surface of the target object W1 is the standard value.

Next, when the piston 28 shown in FIG. 5 descends from the top dead center and performs the second impact, the pressure in the air chamber C1 when the striker 29 with the end face 29a at the second position E2 descends is the end face. This is lower than the pressure in the air chamber C1 when the striker 29 with 29a at the reference position E0 descends. This is because the longer the distance between the piston 28 and the striker 29, the lower the compression ratio due to the movement of the piston 28. *

For this reason, as shown in FIG. 6, when the striker 29 is lowered and the second strike is performed, the striker 29 having the end surface 29a at the second position E2 is lowered before the second strike. The striking force is smaller than the striking force generated when the striking element 29 whose end face 29a is at the reference position E0 is lowered before the second striking. As a result, the area where the striker 29 descends and the breathing hole 45 is opened at the time of the second strike is the case where the striker 29 whose end face 29a is at the second position E2 is lowered before the second strike. This is narrower than the case where the striker 29 whose end face 29a is at the reference position E0 is lowered before the second strike.

For this reason, the amount of air discharged from the air chamber C1 to the space D1 at the time of the second blow is the case where the striker 29 whose end surface 29a is at the second position E2 descends before the second blow. This is less than the case where the striker 29 whose end face 29a is at the reference position E0 descends before the second strike. Therefore, the pressure of the air chamber C1 after the striker 29 strikes the intermediate striker 37 for the second time is the same as when the striker 29 with the end face 29a at the second position E2 is lowered and when the end face 29a is at the reference position E0. This is the same as when the striker 29 in the lower position is lowered.

Then, after the second impact, when the piston 28 rises from the bottom dead center in FIG. 6 in preparation for the third impact, the air chamber C1 becomes negative pressure. Further, in preparation for the third hit, when the striker 29 moves in a direction approaching the piston 28, the end surface 29a of the striker 29 in FIG. 5 is moved to the reference position E0 or the second position E2 before the second strike. In any case, the striker 29 that rises in preparation for the third strike reaches the same reference position E0 with the end face 29a as shown in FIG. Therefore, when the piston 28 descends at the time of the third impact, the compression rate of the air chamber C1 becomes the same, and the impact force applied from the impactor 29 to the intermediate impactor 37 at the time of the third impact is stabilized.

Here, see FIG. 7 for the relationship between the opening area of the breathing hole 45 when the striker 29 is in the position of FIG. 3 and the opening area of the breathing hole 45 when the striker 29 is in the position of FIG. To explain. 7A shows the main part of FIG. 3, and FIG. 7B shows the main part of FIG. The position E3 of the pressure receiving surface 46 of the striker 29 shown in FIG. 7A in the direction along the axis A1 is more distant from the piston 28 than the position E4 of the pressure receiving surface 46 of the striker 29 shown in FIG. 7B. It is far away by the difference dy1 minutes. In addition, in the direction along the axis A1, the opening length L1 of the breathing hole 45 shown in FIG. 7A is longer than the opening length L2 of the breathing hole 45 shown in FIG. That is, the opening area of the breathing hole 45 in FIG. 7A is wider than the opening area of the breathing hole 45 in FIG.

However, when the piston 28 shown in FIG. 7 (A) is raised and the striker 29 is raised, the piston 28 shown in FIG. 7 (B) is raised and the striker 29 is raised. However, when the piston 28 reaches the top dead center, the end face 29a of the striker 29 reaches the reference position E0 as shown in FIG. In this way, the striking tool 10 can make the striking force applied from the striking element 29 to the intermediate striking element 37 during the third striking regardless of the repulsive force applied to the striking element 29 during the first striking.

(Impact prevention action of striking tool) Next, the idling prevention action of the striking tool 10 will be described with reference to FIGS. The striking tool 10 shown in FIG. 8 is in a state where the axis A 1 is vertical and the piston 28 is positioned above the striking element 29. When the end 44 of the tip tool 43 is not pressed against the object W1, the intermediate striker 37 is lowered by its own weight, and the large diameter portion 39 of the intermediate striker 37 comes into contact with the stopper 40 and stops. Further, the striker 29 is also lowered by its own weight, and the striker 29 comes into contact with the intermediate striker 37 and stops. That is, the pressure receiving surface 46 of the striker 29 is in a position along the axis A 1 and deviated from the arrangement region of the breathing holes 45, and the plurality of breathing holes 45 are fully opened.

For this reason, even if the output shaft 14 of the electric motor 13 shown in FIG. 1 is transmitted to the piston 28 and the piston 28 rises, it is possible to prevent the pressure in the air chamber C1 from rising. That is, the difference between the pressure in the air chamber C1 and the pressure in the space D1 does not increase, and the striker 29 does not rise. Further, even if the piston 28 descends from the top dead center toward the bottom dead center, the pressure in the air chamber C1 does not rise. In this way, the striking force is not applied to the striker 29. Therefore, it is possible to prevent striking force from being applied to the striker 29 in a state where the tip tool 43 is not pressed against the object W1, that is, idling. Thus, the breathing hole 45 also serves to prevent idle shots.

(Change Example of Impact Tool) Next, a modification of the breathing hole provided in the cylinder 27 of the impact tool 10 will be described with reference to FIG. In the front view of the impact tool 10 shown in FIG. 9, the breathing hole 45 is circular. Further, the breathing holes 45 are partially different from each other in the arrangement region in the direction along the axis A1, and are different in part. For this reason, in the state where the large diameter portion 39 of the intermediate striker 37 is in contact with the flange portion 35 of the sleeve 33 and the striker 29 is in contact with the intermediate striker 37, the pressure receiving surface 46 has the axis A1. Is located in the arrangement region of at least one breathing hole 45 in the direction along *

When the striking force is applied to the striking element 29 and the end 44 of the tip tool 43 bites into the object W1, and the large diameter portion 39 moves away from the flange portion 35, the total opening area of the opened breathing holes 45 increases. To do. Thus, while the striker 29 is moving, the pressure receiving surface 46 of the striker 29 is located in the arrangement region of at least one breathing hole 45 in the direction along the axis A1.

Even if the breathing hole 45 of the striking tool 10 shown in FIG. 1 is changed to the breathing hole 45 shown in FIG. 9, the same operational effects as those of the striking tool 10 shown in FIG. 1 can be obtained.

(Comparison example impact tool) The comparison example impact tool will be described with reference to FIGS. In the striking tool 200 of the comparative example, the same components as those of the striking tool 10 of the embodiment are denoted by the same reference numerals. The striking tool 200 is provided with a breathing hole 245 and an idling prevention hole 47 in the cylinder 27. The empty shot prevention hole 47 penetrates the cylinder 27 in the radial direction, and the opening diameter of the empty shot prevention hole 47 is larger than the opening diameter of the breathing hole 245. A plurality of idling prevention holes 47 are arranged in the circumferential direction of the cylinder 27. The idle hit prevention hole 47 is provided between the sleeve 33 and the breathing hole 245 in the direction along the axis A1. In the breathing hole 245, as shown in FIG. 11, the tip tool 43 is pressed against the object W1, the large-diameter portion 39 of the intermediate striker 37 contacts the flange portion 35 of the sleeve 33, and the intermediate striker 37 stops. In the state where the striker 29 is in contact with the intermediate striker 37 and is stopped, it is fully opened. That is, the pressure receiving surface 46 is located between the breathing hole 245 and the idling prevention hole 47 in the direction along the axis A1. Specifically, the pressure receiving surface 46 is at a position that is out of the region where the breathing hole 245 is disposed in the direction along the axis A1. *

The operation of the impact tool 200 in the comparative example will be described. For example, when the hardness of the striking surface of the object W1 is the reference value, the striking element 29 strikes the intermediate striking element 37 for the first time, and then the end surface 29a reaches the reference position E0 as shown in FIG. To rise. On the other hand, when the hardness of the striking surface of the object W1 is higher than the reference value, the striking element 29 strikes the intermediate striking element 37 for the first time, and then the end surface 29a is above the reference position E0. The first position E1 is reached. Both the reference position E0 and the first position E1 are positions in the direction along the axis A1. As shown in FIG. 10, the first position E1 is closer to the piston 28 at the top dead center by the difference dy than the reference position E0. *

Next, the piston 28 shown in FIG. 10 is lowered and the striker 29 is lowered, and the second strike is performed as shown in FIG. Then, before the second impact, the striker 29 with the end surface 29a at the first position E1 descends, and the pressure in the air chamber C1 when the second impact is made is the same as before the second impact. In addition, the striker 29 with the end face 29a at the reference position E0 descends and becomes higher than the pressure in the air chamber C1 when the second strike is performed. This is because the compression rate due to the lowering of the piston 28 is high. For this reason, before the second impact, the striker 29 with the end face 29a at the first position E1 descends, and the impact force when performing the second impact is the end face before the second impact. The striking element 29 having 29a at the reference position E0 descends and becomes larger than the striking force when performing the second striking.

However, in the striking tool 200, as shown in FIG. 11, the area where the striking element 29 descends and the breathing hole 245 is opened at the second striking is such that the end face 29a is at the first position E1 before the second striking. This is the same when the striker 29 at the lower position is lowered and when the striker 29 whose end face 29a is at the reference position E0 is lowered before the second strike. That is, the breathing hole 45 is fully opened as shown in FIG. 11 regardless of the striking force applied from the striker 29 to the intermediate striker 37 during the second strike.

For this reason, at the time of the second impact, the amount of air discharged from the air chamber C1 to the space D1 is the case where the striker 29 with the end surface 29a at the first position E1 descends before the second impact, This is the same as when the striker 29 whose end face 29a is at the reference position E0 is lowered before the second strike. Therefore, the pressure of the air chamber C1 when the striker 29 strikes the intermediate striker 37 is such that the striker 29 with the end surface 29a at the first position E1 descends before the second strike, and the second strike. Is higher than the case where the striker 29 whose end face 29a is at the reference position E0 descends and performs the second strike before the second strike.

Further, as shown in FIG. 11, when the piston 28 at the bottom dead center is raised in preparation for the third blow, the air chamber C1 becomes negative pressure and the striker 29 is raised.

Here, before the second strike, the end face 29a of the striker 29 is at the first position E1, and the striker 29 that rises after the second strike has the end face 29a as shown in FIG. It rises to a position that becomes the second position E2. On the other hand, before the second impact, the end face 29a of the impactor 29 is at the reference position E0, and the impactor 29 that rises after the second impact is raised to a position where the end face 29a becomes the reference position E0. . That is, the position of the striker 29 differs by the difference dy in the direction along the axis A1. *

This is because the pressure in the air chamber C1 after the second impact is such that the striker 29 with the end face 29a at the reference position E0 is lowered when the striker 29 with the end face 29a at the first position E1 is lowered. This is because it has a higher force than the case where the striker 29 is prevented from rising. Therefore, when the piston 28 descends from the top dead center in FIG. 12 and performs the third impact, the impact force generated when the striker 29 whose end surface 29a is at the second position E2 descends is based on the end surface 29a. The striking force is unstable because the striking element 29 at the position E0 is lower than the striking force generated by the lowering.

Furthermore, an operation when the hardness of the striking surface of the object W1 is lower than the reference value will be described with reference to FIGS. 10, 12, and 13. FIG. When the hardness of the striking surface of the target object W1 is lower than the reference value, when the striking element 29 that strikes the intermediate striking element 37 for the first time rises, the end face 29a is below the reference position E0 as shown in FIG. To the second position E2. Both the reference position E0 and the second position E2 are positions in the direction along the axis A1. The second position E2 is far from the reference position E0 by the difference dy with respect to the piston 28 at the top dead center.

Next, when the second blow is performed, the pressure of the air chamber C1 in the case where the striker 29 having the end surface 29a at the second position E2 descends and performs the second blow is performed before the second blow. Is lower than the pressure of the air chamber C1 when the striker 29 having the end surface 29a at the reference position E0 descends before the second strike, and the second strike is performed. This is because as the volume of the air chamber C1 between the piston 28 and the striker 29 is larger, the compression rate due to the lowering of the piston 28 is lower.

For this reason, at the time of the second impact, before the second impact, the impact force generated when the impactor 29 whose end surface 29a is at the second position E2 descends is the end surface 29a before the second impact. Becomes smaller than the striking force generated when the striking element 29 at the reference position E0 descends. However, in the striking tool 200, the area where the striking element 29 descends and the breathing hole 245 is opened at the time of the second striking is the case where the striking element 29 whose end face 29a is at the second position E2 is lowered and the end face 29a. Is the same as when the striker 29 at the reference position E0 is lowered. FIG. 13 shows a state in which the striker 29 having the end surface 29a at the second position E2 descends, strikes the intermediate striker 37, and the breathing hole 245 is opened. *

On the other hand, when the striker 29 whose end face 29a is at the reference position E0 descends and the second strike is performed, the pressure receiving surface 46 becomes lower than the pressure receiving surface 46 shown in FIG. Fully open. For this reason, the amount of air discharged from the air chamber C1 to the space D1 at the time of the second impact is such that the striker 29 with the end surface 29a at the second position E2 is lowered and the end surface 29a is at the reference position E0. This is the same as when the striker 29 is lowered. Therefore, the pressure in the air chamber C1 after the second impact is such that the striker 29 with the end face 29a at the reference position E0 is lowered when the striker 29 with the end face 29a at the second position E2 is lowered. Lower than the case.

Further, in preparation for the third impact, when the piston 28 rises from the bottom dead center shown in FIG. 13, the air chamber C1 becomes negative pressure, and the striker 29 also rises. Here, before the second strike, the end face 29a of the striker 29 is in the second position E2 as shown in FIG. 12, and the striker 29 that rises after the second strike is as shown in FIG. The end surface 29a rises to a position where it becomes the first position E1. On the other hand, before the second impact, as shown in FIG. 12, the end face 29a of the impactor 29 is at the reference position E0, and the impactor 29 that rises after the second impact is as shown in FIG. The end surface 29a rises to a position where it becomes the first position E1. That is, the position of the striker 29 differs by the difference dy in the direction along the axis A1. *

This is because the pressure in the air chamber C1 after the second hit is the second hit when the striker 29 whose end face 29a is at the second position E2 is lowered before the second hit. This is because the force that prevents the striker 29 from rising after the second strike is weaker than when the striker 29 whose end surface 29a is at the reference position E0 is lowered. Therefore, when the second impact force changes, the third impact force becomes unstable.

Further, in a state where the end portion 44 of the tip tool 43 is pressed against the object W1, the striker 29 starts from any position of the reference position E0, the first position E1, and the second position E2. Even if the ball falls and strikes the intermediate striker 37, the pressure receiving surface 46 does not reach the arrangement region of the idling prevention hole 47 in the direction along the axis A1. That is, the blanking prevention hole 47 is closed.

In the impact tool 200 of the comparative example, when the end portion 44 of the tip tool 43 is not pressed against the object W1, the intermediate striker 37 is lowered by its own weight, and the large diameter portion 39 of the intermediate striker 37 is the stopper 40. Touch to stop. Further, the striker 29 also descends by its own weight, and the striker 29 comes into contact with the intermediate striker 37 and stops. That is, the blanking prevention hole 47 is fully opened. *

For this reason, in the impact tool 200 of the comparative example, even if the piston 28 rises, the difference between the pressure in the air chamber C1 and the pressure in the space D1 does not increase, and the striker 29 does not rise. Further, even if the piston 28 descends from the top dead center toward the bottom dead center, the pressure in the air chamber C1 does not rise. Therefore, it is possible to prevent striking force from being applied to the striker 29 in a state where the tip tool 43 is not pressed against the object W1, that is, idling.

(Contrast of Embodiment and Comparative Example) Next, the difference between the impact tool 10 in the embodiment and the impact tool 200 of the comparative example will be described with reference to FIG. The time chart of FIG. 14 shows the displacement of the piston 28, the displacement of the striker 29, the pressure of the air chamber C1, and the strike energy. The displacement of the piston 28 is a change with time of the position of the piston 28 in the direction along the axis A1. The position of the piston 28 can be grasped with reference to the end face 28a, for example. The displacement of the striker 29 is a change with time of the position of the striker 29 in the direction along the axis A1. The position of the striker 29 can be grasped on the basis of the end surface 29a, for example. The impact energy is a value determined from the pressure of the air chamber C1, the area of the pressure receiving surface 46, and the like. FIG. 14A corresponds to the impact tool 10 of the embodiment, and FIG. 14B corresponds to the impact tool 200 of the comparative example.

Of the displacement of the striker 29 in the impact tool 10, the position a1 corresponds to the position of the impactor 29 in FIG. 2, the position b1 corresponds to the position of the impactor 29 in FIG. 3, and the position c1 corresponds to FIG. This corresponds to the position of the striker 29 at. In the striking tool 10 in the embodiment, the position where the striking element 29 rises before the next striking is the same regardless of the position of the striking element 29 before the previous striking.

Further, there is a difference S1 between the position of the striker 29 before the previous strike and the position of the striker 29 before the next strike. Further, there is a difference P1 between the pressure of the air chamber C1 before the previous hit and the pressure of the air chamber C1 before the next hit. There is a difference J1 between the impact energy at the previous impact and the impact energy at the next impact.

Of the displacement of the striker 29 in the impact tool 200 of the comparative example, the position a3 corresponds to the position of the striker 29 in FIG. 10, the position b3 corresponds to the position of the striker 29 in FIG. This corresponds to the position of the striker 29 in FIG. When the position of the striker 29 before the previous strike is different in the impact tool 200 in the comparative example, the position where the striker 29 ascends after the previous strike is different.

For this reason, there is a difference S2 between the position of the striker 29 before the previous strike and the position of the striker 29 before the next strike. Further, there is a difference P2 between the pressure of the air chamber C1 before the previous hit and the pressure of the air chamber C1 before the next hit. Further, there is a difference J2 between the impact energy at the previous impact and the impact energy at the next impact.

The difference S1 is smaller than the difference S2, the difference P1 is smaller than the difference P2, and the difference J1 is smaller than the difference J2. Therefore, it can be seen that the striking force of the striking tool 10 of the embodiment is more stable than the striking force of the striking tool 200 of the comparative example. *

Next, when the repulsive force at the time of impact is small, the behavior of the impact tool 10 of the embodiment is compared with the behavior of the impact tool 200 of the comparative example with reference to FIG. FIG. 15A corresponds to the impact tool 10 of the embodiment, and FIG. 15B corresponds to the impact tool 200 of the comparative example. *

Of the displacement of the striker 29 in the impact tool 10, the position a2 corresponds to the position of the impactor 29 in FIG. 5, the position b2 corresponds to the position of the impactor 29 in FIG. 6, and the position c2 corresponds to FIG. This corresponds to the position of the striker 29 at. In the striking tool 10 in the embodiment, the position where the striking element 29 rises after the previous striking is the same regardless of the position of the striking element 29 before the previous striking.

Further, there is a difference S3 between the position of the striker 29 before the previous strike and the position of the striker 29 before the next strike. Further, there is a difference P3 between the pressure of the air chamber C1 before the previous hit and the pressure of the air chamber C1 before the next hit. Then, there is a difference J3 between the impact energy at the previous impact and the impact energy at the next impact. *

Of the displacement of the striker 29 in the impact tool 200 of the comparative example, the position a4 corresponds to the position of the striker 29 in FIG. 12, the position b4 corresponds to the position of the striker 29 in FIG. This corresponds to the position of the striker 29 in FIG. When the position of the striker 29 before the previous strike is different in the impact tool 200 in the comparative example, the position where the striker 29 ascends after the previous strike is different.

For this reason, there is a difference S4 between the position of the striker 29 before the previous strike and the position of the striker 29 before the next strike. Further, there is a difference P4 between the pressure of the air chamber C1 before the previous hit and the pressure of the air chamber C1 before the next hit. Further, there is a difference J4 between the impact energy at the previous impact and the impact energy at the next impact. *

The difference S3 is smaller than the difference S4, the difference P3 is smaller than the difference P4, and the difference J3 is smaller than the difference J4. Therefore, it can be seen that the striking force of the striking tool 10 of the embodiment is more stable than the striking force of the striking tool 200 of the comparative example.

(Embodiment 2) Embodiment 2 of the impact tool of the present invention is shown in FIG. 16 and FIG. The impact tool 110 is also called a hammer drill, and the tip tool T is detachably attached thereto. A rotational force and a striking force are applied to the tip tool T. The striking tool 110 is used for drilling a target such as concrete or stone.

The striking tool 110 has a cylindrical cylinder housing 114, and a cylindrical cylinder 111 is provided in the cylinder housing 114. The cylinder 111 is arranged around the axis A 2, and a cylindrical tool holder 112 is provided concentrically with the cylinder 111. The cylinder 111 and the tool holder 112 are connected so as to be integrally rotatable, and the tool holder 112 is rotatably supported by a bearing 115. A tip tool T is mounted in the tool holder 112, and the rotational force of the cylinder 111 is transmitted to the tip tool T. *

The tool holder 112 has a cylindrical small-diameter portion 112a and a cylindrical large-diameter portion 112b, and the inner diameter of the small-diameter portion 112a is smaller than the inner diameter of the large-diameter portion 112b. A part of the large-diameter portion 112 b is attached to the outer peripheral surface of the cylinder 111. A metal intermediate striker 116 is provided from the tool holder 112 to the cylinder 111.

The intermediate striker 116 can reciprocate in the direction along the axis A2, and the intermediate striker 116 has a small diameter part 116a and a large diameter part 116b having a larger diameter than the small diameter part 116a. The large diameter portion 116 b of the intermediate striker 116 is disposed in the small diameter portion 112 a of the tool holder 112. The small diameter portion 116 a of the intermediate striker 116 is disposed from the large diameter portion 112 b to the cylinder 111.

On the inner surface of the tool holder 112, an annular step 112c is formed between the small diameter portion 112a and the large diameter portion 112b. In the large diameter portion 112b, an annular stopper 190, an annular damper 191 and an annular plate 192 are disposed between the step portion 112c and the end of the cylinder 111. In the direction along the axis A2, the annular damper 191 is disposed between the annular stopper 190 and the annular plate 192. The annular damper 191 is integrally formed of a rubber-like elastic material, and the annular stopper 190 and the annular plate 192 are each formed of a metal material. The small diameter portion 116 a of the intermediate striker 116 is disposed from the annular annular stopper 190, the annular damper 191, and the annular plate 192 to the cylinder 111.

The inner diameter of the annular annular stopper 190, the inner diameter of the annular damper 191 and the inner diameter of the annular plate 192 are the same, and the outer diameter of the large diameter portion 116b is the inner diameter of the annular annular stopper 190, The inner diameter of the damper 191 is larger than the inner diameter of the annular plate 192.

In the cylinder 111, a striker 117 that applies a strike force to the intermediate striker 116 is provided. The striker 117 can reciprocate in the direction along the axis A2. Further, a piston 118 is provided in the cylinder 111 so as to be reciprocally movable in a direction along the axis A2. An air chamber 119 is provided between the striker 117 and the piston 118. When the piston 118 moves from the top dead center toward the bottom dead center, the air in the air chamber 119 is compressed and the striker 117 is in the middle. It moves in a direction approaching the striker 116. When the striker 117 collides with the intermediate striker 116, the strike force of the striker 117 is transmitted to the tip tool T via the intermediate striker 116.

A breathing hole 111a that penetrates the cylinder 111 in the radial direction is provided. A plurality of breathing holes 111 a are provided in the circumferential direction of the cylinder 111. A space 193 is formed between the cylinder 111 and the cylinder housing 114, and the space 193 communicates with the outside of the cylinder housing 114. The breathing hole 111 a connects the air chamber 119 and the space 193.

The opening size of the breathing hole 111a in the direction along the axis A2 is longer than the opening size in the circumferential direction of the cylinder 111. That is, the breathing hole 111a has an elliptical shape and a track shape in a plan view of the impact tool 110, the major axis of the breathing hole 111a is arranged in the direction along the axis A2, and the minor axis of the breathing hole 111a is the circle of the cylinder 111. Arranged along the circumferential direction. The plurality of breathing holes 111a shown in FIG. 17 have the same arrangement area along the axis A2.

Further, an air chamber 119 is formed between the end surface 118a of the piston 118 and the pressure receiving surface 117a of the striker 117, and the pressure of the air chamber 119 is applied to the pressure receiving surface 117a. The pressure receiving surface 117a is a flat surface perpendicular to the axis A2. When the tip tool T is pressed against the object, the large diameter portion 116b of the intermediate striker 116 comes into contact with the stopper 190, and the intermediate striker 116 stops. Further, in a state where the striker 117 is in contact with the stopped intermediate striker 116, the pressure receiving surface 117a is located in the arrangement region of the breathing hole 111a in the direction along the axis A2. That is, the air chamber 119 is connected to the space 193 via the breathing hole 111a, but the breathing hole 111a is not fully opened. The striker 117 has an end surface 117b, and the end surface 117b contacts the small diameter portion 116a. The end surface 117b is a striker 117, and is formed on the side opposite to the pressure receiving surface 117a.

On the other hand, a gear housing 114b is provided at the rear end of the cylinder housing 114, and a motor housing 114c is attached to the gear housing 114b. A handle 128 is provided on the motor housing 114c. *

The electric motor 131 is driven by electric power supplied from a commercial power source, and a power cable 158 is attached to the handle 128. A lever 159 is provided on the handle 128 for switching between a state in which the electric motor 131 is driven and a state in which the electric motor 131 is stopped.

An electric motor 131 is accommodated in the motor housing 114c. The output shaft 134 of the electric motor 131 is rotatable about the axis B2. In front view of the impact tool 110, the axis A2 and the axis B2 are at right angles.

In order to convert the rotational force of the output shaft 134 of the electric motor 131 into the reciprocating force of the piston 118, a crankshaft 141 is rotatably provided in the gear housing 114b. The crankshaft 141 is parallel to the output shaft 134, and a driven gear 142 provided on the crankshaft 141 is engaged with a drive gear 134 a provided on the outer periphery of the output shaft 134. A crankpin 144 is attached to the crankshaft 141 at a position eccentric from the rotation center of the crankshaft 141.

One end of a connecting rod 145 is rotatably connected to the crank pin 144, and the other end of the connecting rod 145 is connected to a piston 118. Therefore, when the rotational force of the output shaft 134 is transmitted to the crankshaft 141, the rotational force of the crankshaft 141 is converted into the reciprocating motion force of the piston 118 by the connecting rod 145. The top dead center of the piston 118 is the position where the piston 118 is closest to the crankshaft 141 in the direction along the axis A2, and the bottom dead center of the piston 118 is the direction where the piston 118 is along the axis A2 This is the position farthest from the axis 141.

Next, a mechanism for converting the rotational force of the output shaft 134 into the rotational force of the cylinder 111 will be described. A rotational force transmission shaft 151 is rotatably provided in the gear housing 114b, and a driven gear 153 is provided for the rotational force transmission shaft 151. The driven gear 153 meshes with the drive gear 134a. For this reason, the rotational force of the output shaft 134 is transmitted to the rotational force transmission shaft 151. Further, a bevel gear 155 is provided on the rotational force transmission shaft 151. *

On the other hand, a cylindrical sleeve 154 is fixed to the outer peripheral surface of the cylinder 111, and a bevel gear 156 is provided on the sleeve 154. Bevel gear 156 meshes with bevel gear 155. Further, the sleeve 154 is rotatably supported by the cylinder housing 114 via a bearing 160. For this reason, the rotational force of the rotational force transmission shaft 151 is transmitted to the cylinder 111 via the

bevel gears

155 and 156.

Next, a usage example of the impact tool 110 will be described. First, when the tip tool T is pressed against the object and the lever 159 is operated to rotate the output shaft 134 of the electric motor 131, the piston 118 reciprocates in the cylinder 111 in the direction along the axis A2. That is, the rotational force of the output shaft 134 is converted into the reciprocating power of the piston 118.

When the piston 118 rises, the pressure in the air chamber 119 becomes lower than the pressure in the space 193, and the air in the space 193 passes through the breathing hole 111a and is sucked into the air chamber 119, and the striker 117 rises. The piston 118 is moved up in a direction along the axis A2 so as to approach the crankshaft 141. Raising the striker 117 means moving in a direction away from the intermediate striker 116 in the direction along the axis A2. *

When the striker 117 rises, the breathing hole 111a is closed by the striker 117, and air is not sucked into the air chamber 119. Further, after the piston 118 reaches the top dead center, the piston 118 descends from the top dead center toward the bottom dead center, and the pressure in the air chamber 119 increases. Then, the striker 117 descends in a direction approaching the intermediate striker 116, and the striker 117 strikes the intermediate striker 116. The striking force applied to the intermediate striker 116 is transmitted to the object via the tip tool T, and the object is crushed. *

During the above operation, the breathing hole 111a is opened immediately before the descending striker 117 strikes the intermediate striker 116, and until the piston 118 reaches the bottom dead center, the air in the air chamber 119 is breathed through the breathing hole 111a. And is discharged into the space 193. When the intermediate striker 116 strikes the tip tool T and the piston 118 reaches the bottom dead center, the piston 118 moves from the bottom dead center toward the top dead center. Thereafter, while the output shaft 134 of the electric motor 131 is rotating, the striker 117 reciprocates in the cylinder 111 and the striker 117 strikes the intermediate striker 116 intermittently.

On the other hand, the rotational force of the output shaft 134 of the electric motor 131 is transmitted to the cylinder 111 via the driven gear 153, the rotational force transmission shaft 151, and the

bevel gears

155 and 156, and the cylinder 111 rotates. The rotational force of the cylinder 111 is transmitted to the tip tool T via the tool holder 112. Thus, the impact tool 110 transmits the impact force and the rotational force to the tip tool T.

By the way, when the tip tool T is pressed against the object and the striker 117 strikes the intermediate striker 116, a repulsive force is generated. For this reason, the amount that rises from the position where the striker 117 strikes the intermediate striker 116 is an amount corresponding to the pressure of the air chamber 119 and the repulsive force. Specifically, the greater the repelling force when the striker 117 strikes the intermediate striker 116, the greater the amount by which the striker 117 rises. *

Also in the impact tool 110 in Embodiment 2, the opening area of the breathing hole 111a becomes larger as the descending amount of the impactor 117 at the previous impact is larger. That is, the pressure of the air chamber 119 when the striker 117 rises is the same regardless of the pressure of the air chamber 119 at the time of the previous hit.

For this reason, regardless of the striking force at the time of the previous striking, the position in the direction along the axis A2 of the striker 117 that rises after striking is the same. Therefore, the impact force generated at the next impact is stabilized. *

The arrangement positions of the plurality of breathing holes 111a provided in the cylinder 111 may be the same as the arrangement positions of the plurality of breathing holes 45 shown in FIG. That is, the arrangement positions of the plurality of breathing holes 111a are arranged at different positions in the direction along the axis A2, and the arrangement positions of the breathing holes 111a in the direction along the axis A2 are partially overlapped. *

In the impact tool 110 of the second embodiment, when the impactor 117 strikes the intermediate impactor 116, the axis A2 is positioned so that the pressure receiving surface 117a is located in the arrangement region of the breathing hole 111a in the direction along the axis A2. Standards such as the size of the intermediate striker 116 in the direction along the axis A, the size of the striker 117 in the direction along the axis A, and the size of the arrangement region of the breathing hole 11a in the direction along the axis A2 are set. Note that whether or not the pressure receiving surface 117a is located in the arrangement region of the breathing hole 111a in the direction along the axis A2 is related to the hardness of the object in addition to the above conditions, and therefore, experimental simulation or the like is performed in advance. Set the above standards.

(Improvement of the impact of the impact tool) Next, the impact of the impact of the impact tool 110 will be described. The striking tool 110 is in a state where the axis A2 is vertical and the piston 118 is positioned above the striking element 117. When the tip tool T is not pressed against the object, the intermediate striker 116 stops at a position where it is lowered by its own weight, and the striker 117 also descends by its own weight and comes into contact with the intermediate striker 116 and stops. Here, the pressure receiving surface 117a of the striker 117 is in a position along the axis A2 and is out of the arrangement area of the breathing holes 111a, and the plurality of breathing holes 111a are fully opened. *

Therefore, even if the power of the output shaft 134 of the electric motor 131 is transmitted to the piston 118 and the piston 118 moves up, the difference between the pressure in the air chamber 119 and the pressure in the space 193 does not increase, and the striker 117 Does not rise. Further, even if the piston 118 descends from the top dead center toward the bottom dead center, the pressure in the air chamber 119 does not rise. Thus, the striker 117 is not hit. Therefore, it is possible to prevent striking force from being applied to the striker 117 in a state where the intermediate striker 116 is not pressed against the object, that is, idling. Thus, the breathing hole 111a also serves to prevent idle shots. In addition, the impact tool in Embodiment 2 can also be used for a hammer driver in addition to a hammer drill.

Here, the correspondence between the configuration described in the first and second embodiments and the configuration of the present invention will be described. The

pistons

28 and 118 correspond to the piston of the present invention, and the axes A1 and A2 are The air chamber C1, 119 corresponds to the axis of the present invention, the fluid chamber of the present invention, and the

strikers

29, 117 correspond to the striker of the present invention. The

cylinders

27 and 111 correspond to the cylinder of the present invention, the

intermediate strikers

37 and 116 correspond to the intermediate striker of the present invention, the breathing holes 45 and 111a correspond to the breathing holes of the present invention, The

pressure receiving surfaces

46 and 117a correspond to the pressure receiving surfaces of the present invention. In the striking tool 10 of the first embodiment, the state where the large diameter portion 39 of the intermediate striking member 37 is in contact with the flange portion 35 is the “intermediate striking member is located at a position closest to the striking member in the axial direction”. Corresponds to “the state of being performed”. Further, in the impact tool 110 of the second embodiment, the state where the large diameter portion 116b of the intermediate impactor 116 is in contact with the stopper 190 indicates that the “intermediate impactor is closest to the impactor in the axial direction” of the present invention. Corresponds to “positioned state”. *

Further, in the impact tool 10 of the first embodiment, as shown in FIG. 8, the state in which the intermediate striker 37 is in contact with the stopper 40 is “the intermediate striker is farthest from the striker in the axial direction of the present invention. This corresponds to “a state where the vehicle is stopped at the position”.

The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the scope of the invention. For example, the impact tool of the present invention includes a structure for supplying the electric power of the storage battery to the electric motor in addition to the structure for supplying the electric power of the commercial power source to the electric motor. The storage battery is detachable from the impact tool, and the storage battery includes a battery pack that houses a plurality of battery cells. In the impact tool of the present invention, the power source that generates the rotational force for reciprocating the piston includes an electric motor, a hydraulic motor, a pneumatic motor, an internal combustion engine, and the like.

In addition to the structure for transmitting the driving force of the electric motor so as to strike the tip tool as in the above embodiment, the hammer drill has a structure for transmitting the driving force of the electric motor to rotate the tip tool. May be.

10, 110 ... impact tool, 27, 111 ... cylinder, 28, 118 ... piston, 29, 117 ... striker, 37, 116 ... intermediate striker, 43, T ... tip tool, 45, 111a ... breathing hole, 46, 117a ... pressure receiving surface, 119, C1 ... air chamber, A1, A2 ... axis, W1 ... object.

Claims

A striking tool for reciprocating a piston in an axial direction and increasing a pressure of a fluid chamber formed between the piston and the striking element to apply a striking force to the striking element, the piston and the striking element being A cylinder that is movably accommodated in the axial direction, an intermediate striking member that operates in the axial direction when a striking force is transmitted from the striking member, and transmits a striking force to a tip tool that contacts the object; A breathing hole that is provided in the cylinder and allows fluid to enter and exit from the fluid chamber according to the operation of the piston; and a pressure receiving surface that is provided in the striking element and receives the pressure of the fluid chamber. In a state where the striker is located at a position closest to the striker in the axial direction, the pressure receiving surface of the striker that is in contact with the intermediate striker is within the region where the breathing holes are arranged in the axial direction. Located in the撃工 tool.
The striking tool according to claim 1, wherein an opening dimension of the breathing hole in the axial direction is larger than an opening dimension of the breathing hole in a direction perpendicular to the axial direction.
The breathing hole discharges fluid from the fluid chamber when the piston operates toward the striker while the intermediate striker is stopped at a position farthest from the striker in the axial direction. And the impact tool of Claim 1 or 2 which suppresses that the pressure of the said fluid chamber raises.
The impact tool according to claim 1, wherein a plurality of the breathing holes are provided in a circumferential direction of the cylinder.
The impact tool according to claim 4, wherein the plurality of breathing holes are partially overlapped with an arrangement region in the axial direction.
In a state where the intermediate striker is located at a position closest to the striker in the axial direction, the pressure receiving surface of the striker that is in contact with the intermediate striker is at least of the plurality of breathing holes. The striking tool according to claim 5, which is located in a region where one breathing hole is arranged.