Impact tool

Abstract

To provide an impact tool with an air spring which can improve an air vent structure from an accommodation space of a striking mechanism.SOLUTION: An impact tool comprises: a motor with a motor shaft in which a first bevel gear is fixed; a striking mechanism which is operably connected through a second bevel gear engaged with the first bevel gear to the motor shaft; a body housing which accommodates the motor and the striking mechanism; and an inner housing which is arranged in the body housing. A closed accommodation space is defined in the body housing to accommodate the striking mechanism and lubricant. The inner housing defines at least partially the accommodation space. The inner housing has an air vent hole formed including an inlet port facing the inside of the inner housing and an outlet port facing the outside of the inner housing. The inlet port is arranged at an inner side in a radial direction relative to an inner peripheral end of a gear tooth in one radial direction of the first bevel gear and the second bevel gear.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present disclosure relates to an impact tool, and more particularly to an impact tool configured to linearly drive a tool tip by striking the tool tip with an air spring. [Background technology]

[0002] There is known an impact tool that uses the action of an air spring to strike the tool tip with an impact element, thereby driving the tool tip linearly and performing processing. In such an impact tool, when the temperature of the storage space in which the impact mechanism is disposed together with the lubricant increases with the driving of the impact mechanism, and the internal pressure also increases, there is a possibility that the air spring will not operate normally. Therefore, the impact tool may be provided with an air vent hole that communicates the inside and outside of the storage space of the impact mechanism. On the other hand, it is not preferable for the lubricant in the storage space to leak to the outside through the air vent hole. Therefore, for example, Patent Document 1 discloses a structure that prevents the lubricant from reaching the entrance of a pressure adjustment passage (air vent hole). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2006-334725 A Summary of the Invention [Problem to be solved by the invention]

[0004] The structure disclosed in Patent Document 1 employs a stop ring that rotates with the rotating shaft and uses centrifugal force to splash the lubricant radially outward. This structure is relatively complex and leaves room for improvement.

[0005] In view of the above-mentioned circumstances, one non-limiting object of the present disclosure is to provide an improvement in a structure for venting air from an accommodation space of a striking mechanism in an impact tool that utilizes an air spring. [Means for solving the problem]

[0006] According to a non-limiting aspect of the present disclosure, there is provided an impact tool including a motor, an impact mechanism, a main housing, and an inner housing. The motor has a motor shaft to which a first bevel gear is fixed. The impact mechanism is operably connected to the motor shaft via a second bevel gear meshing with the first bevel gear. The impact mechanism is configured to linearly drive the tool bit along the drive shaft by utilizing the action of an air spring. The main housing accommodates the motor and the impact mechanism. The inner housing is disposed inside the main housing. A closed accommodation space is defined inside the main housing to accommodate the impact mechanism and the lubricant. The inner housing is configured to at least partially define the accommodation space. The inner housing is formed with an air vent hole having an inlet facing the inside of the inner housing and an outlet facing the outside of the inner housing. The inlet of the air vent hole is disposed radially inward of the inner circumferential end of the gear teeth in the radial direction of one of the first bevel gear and the second bevel gear.

[0007] In the impact tool of this embodiment, the impact mechanism and the lubricant are accommodated in an accommodation space defined inside the main housing. The accommodation space is a closed space defined at least in part by the inner housing, but air can circulate through the air vent hole of the inner housing. Therefore, even if the internal pressure of the accommodation space increases due to heat generated by the operation of the impact mechanism, the internal pressure is adjusted by the air flowing out of the accommodation space through the air vent hole, and the possibility of malfunction of the air spring can be reduced.

[0008] In addition, the inlet of the air vent hole is disposed radially inward from the inner circumferential end of the gear teeth of one of the first bevel gear and the second bevel gear. Therefore, when the impact mechanism is driven, one of the first bevel gear and the second bevel gear rotates, effectively preventing the lubricant from reaching the inlet of the air hole. The first bevel gear and the second bevel gear are components used to transmit power from the motor to the impact mechanism. Therefore, according to the configuration of this aspect, the first bevel gear or the second bevel gear can be utilized to effectively reduce the possibility of lubricant leakage without increasing the number of components. [Brief description of the drawings]

[0009] [Figure 1] FIG. [Diagram 2] FIG. [Diagram 3] FIG. 3 is a partially enlarged view of FIG. [Figure 4] FIG. [Diagram 5] FIG. 2 is a perspective view of a support body and a drive mechanism to which an inner housing is attached. [Figure 6] FIG. 3 is another partially enlarged view of FIG. 2. [Figure 7] FIG. 7 is a cross-sectional view taken along line VII-VII in FIG. [Figure 8] FIG. 2 is a perspective view of a counterweight supported by a support body. [Figure 9] FIG. 1 is a perspective view of the drive mechanism with the support and counterweight attached. [Figure 10] FIG. 3 is yet another partially enlarged view of FIG. 2. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] In a non-limiting embodiment of the present disclosure, the inlet of the air vent hole may be disposed radially inward of the inner circumferential end of the gear teeth of the second bevel gear in the radial direction of the second bevel gear. According to this embodiment, the air vent hole can be formed relatively easily in the inner housing. Generally, the second bevel gear has a larger diameter than the first bevel gear for speed reduction. Therefore, in this case, by providing the air vent hole corresponding to the second bevel gear, the flow path from the radial outside of the second bevel gear to the inlet of the air vent hole can be made longer than in the case of the first bevel gear. Therefore, when the second bevel gear is a gear having a larger diameter than the first bevel gear, it is preferable that the air vent hole be provided corresponding to the second bevel gear.

[0011] In addition to or instead of the above embodiment, the inlet of the air vent hole may be located on the rotation axis of the second bevel gear. According to this embodiment, the inlet can be located at a position that is most difficult for the lubricant to reach.

[0012] In addition to or instead of the above embodiment, the impact tool may further include an intermediate shaft operably connected to the motor shaft. The intermediate shaft may be rotatable about a rotation axis extending parallel to the drive shaft. The impact mechanism may include a motion conversion mechanism. The motion conversion mechanism may be partially disposed on the intermediate shaft and configured to convert a rotational motion of the intermediate shaft into a linear motion in an extension direction of the drive shaft for driving the tool bit. The second bevel gear may be fixed to the intermediate shaft. According to this embodiment, the second bevel gear of the intermediate shaft on which a part of the motion conversion mechanism is provided can be used to effectively characterize the leakage of the lubricant from the accommodating space.

[0013] In addition to or instead of the above embodiment, the impact tool may further include a bearing supported by the inner housing and rotatably supporting the second bevel gear. The intermediate shaft may be rotatably supported via the second bevel gear. According to this embodiment, the intermediate shaft can be made shorter than in a configuration in which a portion of the intermediate shaft is directly supported by the bearing.

[0014] In addition to or instead of the above embodiment, the inner housing may have a protrusion protruding toward one of the first bevel gear and the second bevel gear. The air vent hole may penetrate the protrusion, and the inlet of the air vent hole may be at the tip of the protrusion. The protrusion may extend at least to the inside of one of the first bevel gear and the second bevel gear in the axial direction of one of the first bevel gear and the second bevel gear. In this case, typically, one of the first bevel gear and the second bevel gear, or the intermediate shaft, is provided with a recess extending in the axial direction from the tip, and the tip of the protrusion (the inlet of the air vent hole) is disposed within this recess. According to this embodiment, a passage is formed that extends from the tip of one of the first bevel gear and the second bevel gear, or the intermediate shaft, to the inlet of the air vent hole, and a change of direction is required to enter the air vent hole from the passage. This makes it possible to more reliably reduce the possibility of leakage of the lubricant.

[0015] In addition to or instead of the above embodiment, the impact tool may further include a rotating shaft rotatable around an axis extending in the front-rear direction of the impact tool. The second bevel gear may be fixed to a rear end of the rotating shaft. The rear end of the second bevel gear may be located rearward of the rear end of the rotating shaft. The protruding portion of the inner housing may protrude forward from the inner housing and extend to the inside of the rotating shaft. According to this embodiment, a passage is formed that passes through the inside of the second bevel gear and the inside of the rotating shaft and extends to the inlet of the air vent hole. Therefore, for example, it is possible to design the part of this passage that is inside the second bevel gear and the part that is inside the rotating shaft separately.

[0016] In addition to or instead of the above embodiment, the distance between the tip of the gear tooth of one of the first bevel gear and the second bevel gear and the inner surface of the inner housing may be smaller than the tooth height of the gear tooth. In this case, the distance between the tip of the gear tooth of one of the first bevel gear and the second bevel gear and the inner surface of the inner housing may be substantially constant. According to this embodiment, it is possible to make it difficult for the lubricant to pass between the tip of the gear tooth of one of the first bevel gear and the second bevel gear and the inner surface of the inner housing.

[0017] A hammer drill 1 according to a representative and non-limiting embodiment of the present disclosure will be described below with reference to Figs. 1 to 10. The hammer drill 1 is a power tool capable of performing an impact operation. The impact operation is an operation in which a removably held tip tool 91 is struck and linearly reciprocated along a drive shaft DX. In other words, the hammer drill 1 is an example of a reciprocating tool and an example of an impact tool. The hammer drill 1 can also perform a rotation operation simultaneously with the impact operation or independently of the impact operation. The rotation operation is an operation in which the tip tool 91 is rotationally driven around the drive shaft DX.

[0018] First, there will be described a schematic configuration of the hammer drill 1. As shown in Figures 1 and 2, the outer shell of the hammer drill 1 is formed by a main body housing 10 and a handle 17 connected to the main body housing 10.

[0019] The main body housing 10 is a hollow body also referred to as a tool body or an outer shell. The main body housing 10 of the present embodiment includes a first housing portion 11 and a second housing portion 15.

[0020] As shown in Fig. 2, the first housing portion 11 mainly accommodates the spindle 40, which is a tool tool holding member, and the drive mechanism 4 for the tool tool 91. The spindle 40 is a long cylindrical member. One end of the spindle 40 in the longitudinal direction is configured as a tool holder 41 that removably holds the tool tool 91. The longitudinal axis of the tool holder 41 (spindle 40) defines the drive axis DX of the tool tool 91.

[0021] The first housing part 11 extends along the drive axis DX. One end of the first housing part 11 in the extending direction of the drive axis DX is formed in a cylindrical shape, and the tool holder 41 is accommodated in this part (also called a barrel part 111). The remaining part of the first housing part 11 is tubular and larger than the barrel part 111, and one end opposite to the barrel part 111 defines an opening 113. A metal inner housing 20 is fitted into the end of the first housing part 11 that defines the opening 113, and closes the opening 113. This defines a first space 101 surrounded by the inner housing 20 and the first housing part 11. The spindle 40 and the drive mechanism 4 are arranged in this first space 101. Therefore, it may be said that the first housing part 11 and the inner housing 20 as a whole form one housing (so-called gear housing) that accommodates the spindle 40 and the drive mechanism 4.

[0022] The second housing portion 15, which mainly houses the motor 31, is connected to one end of the first housing portion 11 and extends in a direction intersecting (more specifically, roughly perpendicular to) the drive shaft DX. The main housing 10 including the first housing portion 11 and the second housing portion 15 is formed into an L-shape as a whole. A part of the second housing portion 15 covers the inner housing 20 from the outside.

[0023] The handle 17 is a U-shaped hollow member, and both ends of the handle 17 are connected to the main housing 10 (the second housing portion 15). The handle 17 includes a grip portion 171 that is gripped by a user. The grip portion 171 extends in a direction intersecting the drive axis DX (specifically, in a direction generally perpendicular to the drive axis DX). The grip portion 171 is provided with a trigger 173 that is pressed by a user. A switch 175 is accommodated in the grip portion 171. A controller 30 that controls the operation of the hammer drill 1 is accommodated in the lower end of the handle 17. A battery 93 is removably attached to the lower end of the handle 17. When the switch 175 is turned on in response to the pressing of the trigger 173, the controller 30 starts driving the motor 31, and the drive mechanism 4 drives the tip tool 91.

[0024] The detailed configuration of the hammer drill 1 will be described below. In the following description, for convenience, the extending direction of the drive shaft DX is defined as the front-rear direction of the hammer drill 1. In the front-rear direction, the tip side of the tool holder 41 (the side into which the tool tip 91 is inserted) is defined as the front side of the hammer drill 1, and the opposite side is defined as the rear side. In addition, a direction perpendicular to the drive shaft DX and roughly corresponding to the extending direction of the second housing part 15 (which is also the extending direction of the grip part 171) is defined as the up-down direction of the hammer drill 1. In the up-down direction, the direction toward the first housing part 11 is defined as the upward direction, and the direction away from the first housing part 11 is defined as the downward direction. Furthermore, a direction perpendicular to the front-rear direction and the up-down direction is defined as the left-right direction.

[0025] First, the detailed configurations of the main housing 10 and the inner housing 20 will be described.

[0026] As described above, the first housing portion 11 is a cylindrical member as a whole, and the opening 113 at the rear end portion is closed by the inner housing 20. As shown in Figs. 3 to 5, the inner housing 20 is a hollow body having an opening 201 and an internal space 200. The inner housing 20 is disposed so that the opening 201 faces forward, and is fitted into the rear end portion of the first housing portion 11 that defines the opening 113. More specifically, the inner housing 20 includes a cylindrical peripheral wall portion 202 that defines the opening 201, and a rear wall portion 203 that is continuous with the peripheral wall portion 202. The internal space 200 is a space that is open forward, surrounded in the circumferential direction around the drive shaft DX by the peripheral wall portion 202, and closed at the rear by the rear wall portion 203.

[0027] An annular groove 204 is formed in an annular region of the outer surface of the peripheral wall portion 202 that extends in the circumferential direction adjacent to the opening 201. An annular seal member 28 is attached to the groove 204 of the inner housing 20. The seal member 28 is, for example, made of an annular elastic body (for example, a rubber O-ring). The seal member 28 is disposed in a compressed state between the inner surface of the rear end portion of the first housing portion 11 and the outer surface of the peripheral wall portion 202 of the inner housing 20, and closes the gap between the first housing portion 11 and the inner housing 20. As a result, a first space 101 closed by the first housing portion 11 and the inner housing 20 is defined. The first space 101 accommodates the spindle 40 and the drive mechanism 4 together with a lubricant (for example, grease).

[0028] As shown in Figs. 1 and 2, the second housing portion 15 is a hollow body that is connected to the rear end portion of the first housing portion 11 and extends in the up-down direction. An upper half portion 151 of the second housing portion 15 is connected to the rear end portion of the first housing portion 11 by a screw. In this embodiment, the second housing portion 15 is formed by connecting two half bodies divided in the left-right direction to each other by a screw. An inner housing 20 that is fitted into the rear end portion of the first housing portion 11 is disposed inside the upper half portion 151 of the second housing portion 15. A motor 31 is accommodated in a lower half portion 153 of the second housing portion 15 (i.e., a portion extending downward from the accommodation portion of the inner housing 20).

[0029] With the above-described configuration, two spaces are formed inside the main housing 10, partitioned by the inner housing 20: a first space 101 that houses the spindle 40 and the drive mechanism 4 together with a lubricant, and a second space 102 that mainly houses the motor 31. It may be said that the first space 101 and the second space 102 are isolated from each other by a seal member 28 disposed between the inner housing 20 and the main housing 10 (first housing portion 11).

[0030] The elements (configuration) arranged inside the main body housing 10 will be described below.

[0031] First, the motor 31 will be described. As shown in FIG. 2, the motor 31 is accommodated in the lower half 153 of the second housing portion 15. The motor 31 includes a motor body 310 including a stator and a rotor, and a motor shaft 315. The motor shaft 315 is a shaft that can rotate around the motor axis MX integrally with the rotor, and protrudes from the rotor. In this embodiment, the motor 31 is disposed such that the motor axis MX extends slightly obliquely with respect to the vertical direction of the hammer drill 1 and obliquely intersects with the drive axis DX. However, the motor 31 may be disposed such that the motor axis MX and the drive axis DX extend in the vertical direction at right angles to each other.

[0032] A first bevel gear 33 is connected to the upper end of the motor shaft 315. The first bevel gear 33 rotates integrally with the motor shaft 315. The motor shaft 315 is rotatably supported by two bearings 321, 323. The upper bearing 321 is supported by the lower rear end of the inner housing 20 and rotatably supports the upper end of the motor shaft 315. The teeth portion of the first bevel gear 33 is disposed inside the inner housing 20. The teeth portion is a portion of the first bevel gear 33 where the gear teeth 331 (see FIG. 3) are formed. The lower bearing 323 is supported by the second housing portion 15 and rotatably supports the motor shaft 315 below the motor main body portion 310.

[0033] A fan 35 for cooling the motor 31 is fixed to the lower end of the motor shaft 315 (a portion extending downward beyond the bearing 323). The fan 35 rotates integrally with the motor shaft 315 to generate an air flow (cooling air) that flows into the main body housing 10 from the intake port 105, passes through the motor 31, and flows out of the main body housing 10 from the exhaust port 107.

[0034] As shown in Figs. 1 and 2, in this embodiment, the intake port 105 is formed in the upper end portion (upper wall portion) of the second housing portion 15. More specifically, the intake port 105 is disposed rearward of the seal member 28 in the front-rear direction and forward of the rear end of the inner housing 20. In other words, the intake port 105 is disposed directly above the inner housing 20. The exhaust port 107 is formed in the lower end portion of the second housing portion 15. More specifically, the exhaust port 107 is disposed in the lower ends of the left and right sides of the second housing portion 15.

[0035] By arranging the intake port 105 and the exhaust port 107 in this manner, an air flow path is defined in the second space 102. Specifically, air drawn from the intake port 105 into the upper half 151 of the second housing part 15 by the rotational drive of the fan 35 flows downward along the inner housing 20 between the inner surface of the second housing part 15 and the outer surface of the inner housing 20. This air further passes between the stator and rotor of the motor 31 arranged in the lower half 153, and reaches the fan 35. The air sent out from the fan 35 flows out from the exhaust port 107 to the outside of the second housing part 15.

[0036] In this embodiment, as shown in Fig. 3, a guide rib 106 is provided inside second housing part 15 adjacent to intake port 105. Guide rib 106 is configured to direct air that has flowed into second housing part 15 through intake port 105 forward. Specifically, a lower part of guide rib 106 is inclined forward as it extends downward. Therefore, air that has flowed in from intake port 105 is guided toward the portion where seal member 28 is attached.

[0037] The spindle 40 will now be described.

[0038] As shown in FIG. 3, the spindle 40 of this embodiment is a long stepped cylindrical member, and is supported in the upper half of the first space 101 so as to extend in the front-rear direction.

[0039] The front half of the spindle 40 constitutes the tool holder 41. The tool tip 91 is inserted from an opening 410 at the front end of the tool holder 41 so that its long axis coincides with the drive axis DX, and is held in a state in which axial movement relative to the tool holder 41 is permitted and rotation around the axis is restricted. The rear half of the spindle 40 constitutes a cylinder 42 that slidably holds a piston 57. In this embodiment, the spindle 40 is a single member in which the tool holder 41 and the cylinder 42 are integrally formed. However, the spindle 40 may be formed by connecting a plurality of separate members to each other.

[0040] The spindle 40 is rotatably supported around the drive axis DX via two bearings 401, 402. The front bearing 401 is fitted and supported within the front end portion (barrel portion 111) of the first housing portion 11, and rotatably supports the front end portion (tool holder 41) of the spindle 40. The rear bearing 402 is supported by the support body 22, and rotatably supports the rear end portion of the spindle 40 (cylinder 42).

[0041] As shown in Fig. 5, the support 22 is an annular (ring-shaped) member as a whole. The support 22 is made of metal. As shown in Fig. 3, the bearing 402 is fitted inside the support 22. The support 22 is connected to the front end of the upper half of the inner housing 20, and fitted into the upper part of the first housing part 11. With this configuration, the rear end of the spindle 40 is supported by the first housing part 11 via the bearing 402 and the support 22.

[0042] The driving mechanism 4 will now be described.

[0043] 3, the drive mechanism 4 is operably connected to the motor 31 (motor shaft 315) and is configured to be driven by the power of the motor 31. The drive mechanism 4 of this embodiment includes a striking mechanism 5 for striking operation and a rotation transmission mechanism 6 for rotating operation. The striking mechanism 5 includes a motion conversion mechanism 51 and a striking element 58.

[0044] As shown in Fig. 3 and Fig. 6, the motion conversion mechanism 51 is operably connected to the motor shaft 315. The motion conversion mechanism 51 is configured to convert the rotational motion of the motor shaft 315 into linear motion (specifically, linear motion of the piston 57) along the drive axis DX for driving the tool tip 91. In this embodiment, a swing-type motion conversion mechanism is used as the motion conversion mechanism 51. The motion conversion mechanism 51 includes a rotor 54 and a swing member 55 provided on the intermediate shaft 52, and a piston 57 arranged in the spindle 40 (cylinder 42).

[0045] The intermediate shaft 52 is supported rotatably around a rotation axis RX parallel to the drive axis DX (i.e., extending in the front-rear direction) in the lower half of the first space 101. A second bevel gear 53 is connected to the rear end of the intermediate shaft 52. The second bevel gear 53 rotates integrally with the intermediate shaft 52.

[0046] The second bevel gear 53 includes a cylindrical mounting portion 533 and a tooth portion on which gear teeth 531 are formed. The mounting portion 533 is fixed to the periphery of the rear end portion of the intermediate shaft 52. The rear end (rear end of the tooth portion) of the second bevel gear 53 is located rearward of the rear end of the intermediate shaft 52. In other words, a part of the second bevel gear 53 protrudes rearward from the rear end of the intermediate shaft 52. The second bevel gear 53 meshes with the first bevel gear 33 provided on the motor shaft 315, and is rotated integrally with the intermediate shaft 52 in response to the rotation of the motor shaft 315. The first bevel gear 33 and the second bevel gear 53 are configured as a gear reducer, and the gear teeth 531 of the second bevel gear 53 have a larger diameter than the gear teeth 331 of the first bevel gear 33.

[0047] The intermediate shaft 52 is rotatably supported by two bearings 521, 522. The front bearing 521 is fitted onto the outer periphery of the front end portion of the intermediate shaft 52, and is supported by the front end portion of the main housing 10 (first housing portion 11). The rear bearing 522 is fitted onto the outer periphery of the mounting portion 533 of the second bevel gear 53, and is supported by a bearing support member 23 fixed to the inner housing 20. That is, in this embodiment, the rear end portion of the intermediate shaft 52 is rotatably supported via the second bevel gear 53. With this configuration, the intermediate shaft 52 can be made shorter than in a configuration in which a portion of the intermediate shaft 52 is directly supported by a bearing.

[0048] The bearing support member 23 is a member separate from the inner housing 20, and is disposed inside the inner housing 20 and fixed to the inner housing 20 with screws. The bearing support member 23 is formed so as to cover the outer periphery and front end of the teeth of the second bevel gear 53. The second bevel gear 53 is accommodated in a space between the rear wall portion 203 of the inner housing 20 and the bearing support member 23. An opening 230 is provided in the bearing support member 23 on the radial outside of the gear teeth 531 of the second bevel gear 53. The opening 230 communicates between the internal space of the bearing support member 23 in which the second bevel gear 53 is accommodated and the space outside the bearing support member 23.

[0049] The rotating body 54 is provided on the intermediate shaft 52 (around the intermediate shaft 52) ​​and can rotate integrally with the intermediate shaft 52. Although detailed description is omitted because this is a well-known configuration, the rotating body 54 is switched between a state in which it rotates integrally with the intermediate shaft 52 and a state in which it rotates idly with respect to the intermediate shaft 52 by a mode switching mechanism according to a selected operation mode. The rotating body 54 rotates integrally with the intermediate shaft 52 only when an operation mode in which a striking operation is performed is selected. The oscillating member 55 is operably connected to the rotating body 54 and configured to oscillate in response to the rotation of the rotating body 54. The rotating body 54 and the oscillating member 55 are well-known components collectively referred to as swash bearings, wobble bearings, etc.

[0050] The swinging member 55 of this embodiment includes an annular ring portion 550 connected to the periphery of the rotating body 54 via a rolling body, and a swinging arm 551 and a protrusion 552 that protrude radially outward from the ring portion 550. The swinging arm 551 protrudes upward from the ring portion 550 in the vertical direction, and swings in the front-rear direction in response to the rotation of the rotating body 54. The swinging arm 551 is operably connected to the piston 57. The protrusion 552 is disposed coaxially (in a straight line) with the long axis of the swinging arm 551, and protrudes from the ring portion 550 in the opposite direction to the swinging arm 551. Therefore, the protrusion 552 swings in the opposite direction to the swinging arm 551 in the front-rear direction in response to the rotation of the rotating body 54. The protrusion 552 is connected to the counterweight 7. The counterweight 7 and its support structure will be described in detail later.

[0051] The piston 57 is a cylindrical member with a bottom, and is disposed in the cylinder 42 (the rear half of the spindle 40) so as to be slidable along the drive shaft DX. A rear end portion 571 of the piston 57 is operatively connected to the swing arm 551 of the swing member 55 via a connecting pin 573. The piston 57 reciprocates in the front-rear direction in response to the swing of the swing arm 551 of the swing member 55.

[0052] The inner housing 20 of this embodiment is configured to accommodate a part of the motion converting mechanism 51 of the striking mechanism 5. More specifically, the inner housing 20 is configured so that most of the rotating body 54 and the oscillating member 55 provided on the intermediate shaft 52 are accommodated in the internal space 200 of the inner housing 20. In other words, most of the rotating body 54 and the oscillating member 55 are surrounded by the peripheral wall portion 202 and the rear wall portion 203 of the inner housing 20.

[0053] As shown in FIG. 3, the striking element 58 is configured to move linearly in response to the reciprocating motion of the piston 57 to impart a striking force to the tool tip 91, thereby driving the tool tip 91 linearly along the drive axis DX. In this embodiment, the striking element 58 includes a striker 581 and an impact bolt 583. The striker 581 is disposed in the bottomed cylindrical piston 57 so as to be slidable along the drive axis DX. The internal space of the piston 57 behind the striker 581 (the space between the striker 581 and the bottom of the piston) is defined as an air chamber 59 that functions as an air spring. The impact bolt 583 is disposed in the tool holder 41 in front of the striker 581 and is slidable along the drive axis DX. The space in front of the striker 581 communicates with the first space 101 via a through hole formed in the tool holder 41.

[0054] As the piston 57 reciprocates in the cylinder 42, the air pressure in the air chamber 59 fluctuates, and the striker 581 slides in the front-rear direction in the piston 57 due to the action of the air spring. More specifically, when the piston 57 moves forward, the striker 581 is pushed forward at high speed by the action of the air spring and strikes the impact bolt 583. The impact bolt 583 transmits the kinetic energy of the striker 581 to the tool tip 91. As a result, the tool tip 91 is driven linearly along the drive shaft DX. On the other hand, when the piston 57 moves backward, the striker 581 is pulled backward. The tool tip 91 is pressed against the workpiece and moves backward together with the impact bolt 583. In this way, the striking action is repeated by the striking mechanism 5.

[0055] As shown in FIG. 3, the rotation transmission mechanism 6 is operably connected to the motor shaft 315 and configured to transmit the rotation of the motor shaft 315 to the tool holder 41 (spindle 40). The rotation transmission mechanism 6 includes a drive gear 61 provided at the front end of the intermediate shaft 52, and a driven gear 63 fixed to the outer periphery of the cylinder 42 of the spindle 40 and meshing with the drive gear 61. The drive gear 61 and the driven gear 63 configure a gear reducer. The drive gear 61 is switched by the above-mentioned mode switching mechanism between a state in which it rotates integrally with the intermediate shaft 52 and a state in which it rotates idly relative to the intermediate shaft 52. The drive gear 61 rotates integrally with the intermediate shaft 52 only when an operation mode in which a rotation operation is performed is selected.

[0056] The drive gear 61 rotates integrally with the intermediate shaft 52 in response to the rotation of the motor shaft 315, thereby rotating the spindle 40 integrally with the driven gear 63, and the tool tip 91 held by the tool holder 41 is rotated about the drive axis DX. In this manner, the rotation transmission mechanism 6 performs the rotational operation.

[0057] The counterweight 7 and its support structure will be described below.

[0058] 6 and 7, the counterweight 7 is supported by the support body 22 so as to be able to swing within the first space 101 surrounded by the first housing portion 11 and the inner housing 20. As described above, the support body 22 is a member separate from the inner housing 20, and is connected to the front end portion of the upper half of the inner housing 20.

[0059] More specifically, as shown in Figures 8 and 9, the counterweight 7 of this embodiment is configured as an annular (ring-shaped) member that is long in the vertical direction. The counterweight 7 is made of metal. The support body 22 includes an annular main body portion 221 and two arm portions 223 that protrude rearward from an upper portion of the main body portion 221.

[0060] As described above, the main body 221 is an annular portion that supports the rear end of the spindle 40 (cylinder 42) via the bearing 402 (see FIG. 6). The main body 221 is fixed to the front end of the inner housing 20 with a screw in a state in which an abutment surface set at the rear end of the main body 221 abuts against an abutment surface set at the front end of the inner housing 20. The main body 221 is located above the rotor 54 arranged on the intermediate shaft 52 in the up-down direction.

[0061] The two arm portions 223 extend from a portion of the main body portion 221 that is above the rear end portion 571 (the portion connected to the swing arm 551) of the piston 57 into the internal space 200 of the inner housing 20. The arm portions 223 are provided at substantially the same position in the up-down direction and spaced apart in the left-right direction, and extend substantially parallel to each other in the front-rear direction. The rear end of each arm portion 223 is located directly above the rotating body 54 and the ring portion 550 of the swing member 55. As shown in FIG. 6 and FIG. 7, the upper end of the counterweight 7 is provided with a support hole 71 extending in the left-right direction. A support shaft 225 is inserted through this support hole 71. The rear ends of the two arms 223 support both ends of the support shaft 225. More specifically, the rear end of the arm 223 is formed with a support hole 224 penetrating the arm 223 in the left-right direction. Both ends of the support shaft 225 are inserted through the support holes 224 of the two arms 223 and supported. With this configuration, the counterweight 7 is supported by the support body 22 via the support shaft 225 so as to be able to swing. The swing axis PX of the counterweight 7 extends in the left-right direction above the rear end 571 of the piston 57.

[0062] In the vertical direction, the upper half of the inner region of the ring of the counterweight 7 is located in a position corresponding to the rear end 571 of the piston 57, and the lower half is located in a position corresponding to the ring portion 550 of the swinging member 55. The shape of the counterweight 7 is set so that the rear end 571 of the piston 57 and the ring portion 550 of the swinging member 55 can move in the inner region without interfering with the counterweight 7 during a striking operation.

[0063] As shown in Figs. 6 and 9, the counterweight 7 is operably connected to the swinging member 55. More specifically, an engagement hole 73 is provided at the lower end of the counterweight 7. The projection 552 of the swinging member 55 is inserted into the engagement hole 73 with some play. Therefore, when the swinging member 55 is swung in response to the rotation of the intermediate shaft 52, the counterweight 7 is driven by the projection 552 and swings around the swing axis PX. As described above, the projection 552 protrudes in the opposite direction to the swinging arm 551 on the same axis, so that the lower end of the counterweight 7 moves in the opposite direction to the piston 57 and the striking element 58. This allows the counterweight 7 to reduce periodic vibration in the forward and backward directions that occurs during a striking operation.

[0064] As described above, in this embodiment, the counterweight 7 is supported not by the inner housing 20 but by the support 22, which is a separate member from the inner housing 20. Therefore, the inner housing 20 can be optimally designed without being restricted by the support structure of the counterweight 7. For example, the shape of the inner housing can be simplified compared to known configurations in which the counterweight is supported by the inner housing. In addition, since it is easy to provide the arm portion 223 on the support 22, it is also advantageous in terms of the processing cost of the support structure. In addition, in this embodiment, the support 22 also serves as a member that supports the rear end of the spindle 40, so a rational support structure for the counterweight 7 and the spindle 40 is realized without increasing the number of parts.

[0065] In addition, in the above-mentioned known configuration, the portion (support portion) that supports the counterweight via the support shaft protrudes forward from the peripheral wall portion of the inner housing because the support shaft is passed through the support hole of the support portion during assembly. This support portion and the counterweight, together with the drive mechanism and the lubricant, are disposed in a space sealed by a seal member attached to the outer periphery of the peripheral wall portion. On the other hand, because the counterweight needs to be driven by the swinging member, there is a limit to how far the support shaft can be disposed forward from the swinging member. For this reason, in the above-mentioned known configuration, there is a limit to how far the peripheral wall portion of the inner housing can be extended forward and the position of the seal member can be moved forward.

[0066] In contrast, in this embodiment, the support body 22 supports the support shaft 225 in the internal space 200 of the inner housing 20. Therefore, without such restrictions, the inner housing 20 can be extended further forward than in known configurations, and the seal member 28 can be disposed at the front end of the inner housing 20. Therefore, a wider area of ​​the inner housing 20 can be effectively cooled by the air flowing through the second space 102 along the above-mentioned flow path.

[0067] Hereinafter, a configuration for adjusting the pressure in the first space 101 will be described.

[0068] As described above, the first space 101 defined by the inner housing 20 and the first housing part 11 contains a lubricant. For this reason, the first space 101 is made a closed space so that the lubricant does not leak out. On the other hand, if the first space 101 is made an airtight space, a problem may occur in which the striking element 58 does not operate normally. Specifically, when the striking mechanism 5 generates heat as it is driven, the temperature and pressure in the first space 101 rise, and the pressure in the space in front of the striker 581 in the spindle 40 also rises. As a result, the pressure balance between this space and the air chamber 59 functioning as an air spring is lost, and the striker 581 may not operate normally in a straight line.

[0069] Therefore, the hammer drill 1 of this embodiment is provided with a configuration for adjusting the pressure in the first space 101 by allowing the air in the first space 101 to flow out (i.e., to the second space 102). Specifically, as shown in Fig. 10, the inner housing 20 is provided with an air vent hole 24 that connects the inside and outside of the first space 101. On the other hand, it is undesirable for the lubricant to leak out from the first space 101 to the outside through the air vent hole 24. Therefore, in this embodiment, the air vent hole 24 and its surrounding area are configured to suppress leakage of the lubricant.

[0070] The air vent hole 24 is provided in a position of the rear wall portion 203 of the inner housing 20 corresponding to the center of the second bevel gear 53 fixed to the intermediate shaft 52. More specifically, a portion of the rear wall portion 203 of the inner housing 20 corresponding to a region radially inward from the inner circumference (radially inner end) of the gear teeth 531 of the second bevel gear 53 has a protrusion 205 that protrudes forward. The air vent hole 24 is a hole that linearly penetrates the protrusion 205 in the front-rear direction along the rotation axis RX of the second bevel gear 53. The air vent hole 24 has an inlet 241 that is an opening facing the inside of the inner housing 20 and an outlet 242 that is an opening facing the outside of the inner housing 20.

[0071] On the other hand, the second bevel gear 53 and the intermediate shaft 52 are provided with a recess (bottomed hole) 25 for receiving the protrusion 205 of the inner housing 20. As described above, the second bevel gear 53 is fixed to the outer periphery of the intermediate shaft 52 with its rear end protruding rearward from the rear end of the intermediate shaft 52. The recess 25 has an opening 251 on the rear end surface of the second bevel gear 53, passes through the center of the teeth of the second bevel gear 53, and extends forward through the center of the intermediate shaft 52. The diameter of the recess 25 is larger than the diameter of the protrusion 205. The protrusion 205 is inserted into the recess 25 from the opening 251 with a gap between the outer surface of the protrusion 205 and the surface that defines the recess 25. The tip of the protrusion 205 (the inlet 241 of the air vent hole 24) is spaced rearward from the bottom surface of the recess 25. The air vent hole 24 is in communication with the internal space of the recess 25.

[0072] This configuration defines an air flow path that passes from the opening 251 through the inside of the recess 25, via the air vent hole 24, and out of the inner housing 20. In other words, this air flow path is configured to turn back (reverse the flow direction) midway.

[0073] The recess 25 in this embodiment is formed by a through hole formed in the center of the tooth portion of the second bevel gear 53, and a recess (bottomed hole) that communicates with the through hole and is recessed forward from the rear end surface of the intermediate shaft 52. Since the diameter of the through hole of the second bevel gear 53 is larger than the diameter of the recess of the intermediate shaft 52, it becomes easier to insert the protrusion 205 into the recess 25 during assembly.

[0074] 4 and 10, a cylindrical portion 207 is provided on the outer surface of the rear wall portion 203 of the inner housing 20 so as to surround the air vent hole 24. A filter 208 is fitted into the cylindrical portion 207. The filter 208 is made of a material (e.g., felt, sponge) that allows air to pass through while absorbing and retaining lubricant.

[0075] Furthermore, the portion of the rear wall 203 of the inner housing 20 facing the gear teeth 531 of the second bevel gear 53 has a shape conforming to the tooth portion. The distance between the inner surface of the portion of the inner housing 20 facing the gear teeth 531 and the tip of the gear teeth 531 is set to be smaller than the tooth height of the gear teeth 531 (the distance from the tooth tip to the tooth bottom at the outer circumferential end of the gear teeth 531). Therefore, the distance between the tip of the gear teeth 531 and the inner housing 20 is very small. This makes it possible to reduce the amount of lubricant itself that enters this gap. Moreover, this distance is substantially constant in the radial direction of the second bevel gear 53.

[0076] Similarly, the distance between the inner surface of the portion of the inner housing 20 facing the gear teeth 331 of the first bevel gear 33 and the tip of the gear teeth 331 is set to be smaller than the tooth height (the distance from the tooth tip to the tooth bottom) of the gear teeth 331. Therefore, the distance between the tip of the gear teeth 331 and the inner housing 20 is very small. Moreover, this distance is substantially constant in the radial direction of the first bevel gear 33.

[0077] In this embodiment, the bearing 522 that supports the rear end of the intermediate shaft 52 is supported by the bearing support member 23 inside the inner housing 20, not by the rear wall portion 203. Therefore, as described above, the rear wall portion 203 of the inner housing 20 can be formed in a shape that is effective for forming an air flow path through which the lubricant does not easily pass.

[0078] When the striking mechanism 5 is driven, the striking mechanism 5 generates heat, and the air in the first space 101 expands and the internal pressure rises, the air in the first space 101 flows out through the air vent hole 24 into the second space 102, which has a lower pressure. Specifically, air enters the inside of the bearing support member 23 (the space between the bearing 522 and the rear wall portion 203) mainly through the opening 230 from the outside of the bearing support member 23. This air passes through the gap between the second bevel gear 53 and the inner surface of the inner housing 20 and the gap between the first bevel gear 33 and the inner surface of the inner housing 20 to reach the opening 251 of the recess 25. The air that has entered the recess 25 from the opening 251 passes forward through the gap between the outer surface of the protruding portion 205 and the surface that defines the recess 25, enters the air vent hole 24 from the inlet 241, and flows out through the outlet 242 and the filter 208 into the second space 102.

[0079] On the other hand, leakage of the lubricant from the first space 101 to the second space 102 is effectively suppressed. Specifically, when the striking mechanism 5 is driven, the second bevel gear 53 rotates, and the lubricant in the gap between the gear teeth 531 of the second bevel gear 53 and the inner surface of the inner housing 20 is sent out radially outward by centrifugal force. Since the bearing support member 23 has an opening 230, the lubricant can flow out of the bearing support member 23 through the opening 230. In this way, in this embodiment, by utilizing the second bevel gear 53, which is a part of the driving mechanism 4, it is possible to reduce the possibility that the lubricant will reach the opening 251 of the recess 25, which is provided in the center of the second bevel gear 53 and leads to the air vent hole 24. In particular, since the second bevel gear 53 has a larger diameter than the first bevel gear 33, a longer flow path can be secured from the outer circumferential end (the radially outer end) of the gear teeth 531 to the center. Also, it becomes easier to form the recess 25 capable of receiving the protrusion 205. In this regard, there is an advantage to using the second bevel gear 53.

[0080] Furthermore, as described above, the flow path from the opening 251 of the recess 25 to the outlet 242 of the air vent hole 24 is configured to extend forward and then turn back backward. This can further reduce the possibility of leakage of the lubricant. Also, if the lubricant leaks from the outlet 242 of the air vent hole 24, the filter 208 fitted in the cylindrical portion 207 absorbs and retains the lubricant, and can suppress the lubricant from diffusing within the second space 102.

[0081] It should be noted that the above embodiment is merely an example, and the impact tool according to the present disclosure is not limited to the illustrated hammer drill 1. For example, non-limiting modifications as exemplified below may be made. Furthermore, at least one of these modifications may be adopted in combination with the hammer drill 1 illustrated in the embodiment and any of the inventions described in the claims.

[0082] For example, the impact tool according to the present disclosure may be embodied as an impact tool (e.g., an electric hammer (demolition hammer, scraper)) configured to perform only an impact action. In addition, the configurations and / or arrangements of the main body housing, inner housing, motor, and impact mechanism in the impact tool may be appropriately changed from the examples of the above-mentioned embodiments.

[0083] In the above embodiment, the inlet 241 of the air vent hole 24 is provided to correspond to the center (rotation axis RX) of the second bevel gear 53 fixed to the intermediate shaft 52, and therefore the inlet 241 is preferably located at a position where the lubricant is least likely to reach. However, the inlet 241 can be changed to any position in the radial direction of the second bevel gear 53 that corresponds to an area radially inward from the inner circumferential end of the gear teeth 531. In addition, the air vent hole 24 may extend linearly at an angle to the rotation axis RX, or may be bent or curved. In addition, the protrusion 205 of the inner housing 20 and the recesses 25 of the second bevel gear 53 and the intermediate shaft 52 may be omitted, and the inlet 241 of the air vent hole 24 may face the rear end surface of the second bevel gear 53.

[0084] In the above embodiment, since the second bevel gear 53 has a larger diameter, and taking the above-mentioned advantages into consideration, the air vent hole 24 is provided to correspond to the second bevel gear 53. However, it is not excluded that the air vent hole 24 may be provided to correspond to the first bevel gear 31.

[0085] Furthermore, in consideration of the spirit of the present invention, the above-mentioned embodiment and its modified examples, the following aspects are constructed. At least one of the following aspects may be adopted in combination with the above-mentioned embodiment and its modified examples, and at least one of the inventions described in each claim. [Aspect 1] The diameter of the second bevel gear is larger than the diameter of the first bevel gear. [Aspect 2] The first bevel gear is disposed in the accommodation space. [Aspect 3] At least one of the second bevel gear and the intermediate shaft has a recess formed therein and extending along the rotation axis of the intermediate shaft, The protruding portion of the inner housing protrudes into the recessed portion, The air vent hole communicates with the internal space of the recess. [Aspect 4] the bearing is formed separately from the inner housing and is supported in the accommodation space by a bearing support member attached to the inner housing, The second bevel gear is disposed between the inner housing and the bearing support member. [Explanation of symbols]

[0086] 1: hammer drill, 10: main housing, 101: first space, 102: second space, 105: intake port, 106: guide rib, 107: exhaust port, 11: first housing part, 111: barrel part, 113: opening, 15: second housing part, 150: rear wall part, 151: upper half part, 153: lower half part, 17: handle, 171: grip part, 173: trigger, 175: switch, 20: inner housing, 200: internal space, 201: opening, 20 2: peripheral wall portion, 203: rear wall portion, 204: groove, 205: protrusion portion, 207: cylindrical portion, 208: filter, 22: support body, 221: main body portion, 223: arm portion, 224: support hole, 225: support shaft, 23: bearing support member, 230: opening, 24: air vent hole, 241: inlet, 242: outlet, 25: recess, 251: opening, 28: seal member, 30: controller, 31: motor, 310: motor main body portion, 315: motor shaft , 321: bearing, 323: bearing, 33: first bevel gear, 331: gear teeth, 35: fan, 4: drive mechanism, 40: spindle, 401: bearing, 402: bearing, 41: tool holder, 410: opening, 42: cylinder, 5: impact mechanism, 51: motion conversion mechanism, 52: intermediate shaft, 521: bearing, 522: bearing, 53: second bevel gear, 531: gear teeth, 533: mounting portion, 54: rotating body, 55: Oscillating member, 550: Ring portion, 551: Oscillating arm, 552: Protrusion, 57: Piston, 571: Rear end portion, 573: Connecting pin, 58: Impact element, 581: Striker, 583: Impact bolt, 59: Air chamber, 6: Rotation transmission mechanism, 61: Driving gear, 63: Driven gear, 7: Counterweight, 71: Support hole, 73: Engagement hole, 91: Tip tool, 93: Battery, DX: Driving shaft, MX: Motor shaft, PX: Oscillating shaft, RX: Rotating shaft

Claims

1. It is a striking tool, A motor having a motor shaft to which a first bevel gear is fixed, A striking mechanism operably connected to the motor shaft via a second bevel gear that meshes with the first bevel gear, the striking mechanism configured to drive the tip tool linearly along the drive shaft using the action of an air spring, A main body housing that houses the motor and the striking mechanism, It comprises an inner housing disposed inside the main housing, Inside the main housing, there is a closed storage space for housing the striking mechanism and lubricant. The inner housing is configured to define the accommodation space at least partially, The inner housing is provided with an air vent having an inlet facing the inside of the inner housing and an outlet facing the outside of the inner housing. The striking tool is characterized in that the inlet of the air vent hole is positioned radially inward from the inner circumferential end of the gear teeth in the radial direction of one of the first bevel gear and the second bevel gear.

2. The striking tool according to claim 1, The striking tool is characterized in that the inlet of the air vent hole is positioned radially inward from the inner circumferential end of the gear teeth of the second bevel gear in the radial direction of the second bevel gear.

3. The striking tool according to claim 2, The striking tool is characterized in that the inlet of the air vent hole is located on the rotation axis of the second bevel gear.

4. A striking tool according to claim 2 or 3, The motor shaft is operably connected to the motor shaft and further comprises an intermediate shaft that is rotatable around a rotation axis extending parallel to the drive shaft, The striking mechanism includes a motion conversion mechanism partially positioned on the intermediate shaft and configured to convert the rotational motion of the intermediate shaft into linear motion in the extending direction of the drive shaft for driving the tip tool, The striking tool is characterized in that the second bevel gear is fixed to the intermediate shaft.

5. The striking tool according to claim 4, The inner housing further comprises a bearing that is supported and rotatably supports the second bevel gear, The striking tool is characterized in that the intermediate shaft is rotatably supported via the second bevel gear.

6. A striking tool according to any one of claims 1 to 3, The inner housing has a projection that protrudes toward one of the first bevel gear and the second bevel gear, The aforementioned air vent hole penetrates the aforementioned protruding portion, The aforementioned entrance is located at the tip of the protruding portion, The striking tool is characterized in that the protrusion extends at least into the interior of the first bevel gear and the second bevel gear in the axial direction of one of the first bevel gears and the second bevel gear.

7. The striking tool according to claim 6, The striking tool further comprises a rotating shaft that is rotatable around an axis extending in the front-rear direction, The second bevel gear is fixed to the rear end of the rotating shaft, The rear end of the second bevel gear is located behind the rear end of the rotating shaft. The striking tool is characterized in that the protruding portion extends forward from the inner housing and into the interior of the rotating shaft.

8. A striking tool according to any one of claims 1 to 3, A striking tool characterized in that the distance between the tip of one of the gear teeth of the first bevel gear and the second bevel gear and the inner surface of the inner housing is smaller than the tooth height of the gear tooth.

9. The striking tool according to claim 8, A striking tool characterized in that the distance between the tip of one of the gear teeth of the first bevel gear and the second bevel gear and the inner surface of the inner housing is substantially constant.

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