Impact tools

Abstract

To release a pressure increased in a driving mechanism housing area by heat generation of a driving mechanism effectively.SOLUTION: A hammer drill 1, in the housing 2, has a motor, a cylindrical tool holder 23, in which a bit may be attached to a front end, a driving mechanism 30, which may strike the bit, a first intermediate shaft 80, which is provided at the driving mechanism 30 and rotated by rotation of an output shaft of the motor, and a driving mechanism housing area T, which houses the driving mechanism 30 in the housing 2 in a sealed state. An air release passage 77 for releasing air in the driving mechanism housing area T to the outside of the driving mechanism housing area T is formed within the first intermediate shaft 80. Further, a through hole 80a serving as an inlet of the air release passage 77 is formed on an outer peripheral surface of the first intermediate shaft 80.SELECTED DRAWING: Figure 13

Description

[Technical field]

[0001] The present invention relates to an impact tool such as a hammer drill. [Background technology]

[0002] An impact tool such as a hammer drill holds a tool holder, to the tip of which a bit can be attached, inside a housing. An inner housing that supports the tool holder and the output shaft of a motor is provided inside the housing, and houses in a sealed state a drive mechanism that strikes the bit. As disclosed in Patent Document 1, a known drive mechanism includes a piston (including a piston cylinder) that reciprocates back and forth, a striker that is linked to the reciprocating motion of the piston via an air chamber, and a power conversion mechanism that converts the rotation of the output shaft into the reciprocating motion of the piston. In such an impact tool, when the driving mechanism heats up due to impact operation, the pressure in the driving mechanism housing area rises. This can cause a pressure imbalance between the driving mechanism housing area and the air chamber, resulting in a striker malfunction in which the striker does not move normally in a straight line. In order to prevent such strike malfunctions, Patent Document 1 employs a pressure adjustment passage. This pressure adjustment passage is formed by inserting a cylindrical member into a bottomed hole provided at the rear end of the rotating shaft. The inlet of the pressure adjustment passage is formed inside the inner housing between the rear end of the rotating shaft and the cylindrical member. The outlet of the pressure adjustment passage is formed at the tip of the cylindrical member and protrudes to the outside of the inner housing. Therefore, when the air in the inner housing expands and the internal pressure rises, the air in the inner housing is discharged to the outside of the inner housing through the pressure adjustment passage, thereby releasing the pressure. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 4461062 Summary of the Invention [Problem to be solved by the invention]

[0004] In the impact tool of Patent Document 1, the inlet of the pressure adjustment passage is formed in a narrow space between the bearing and retaining ring that support the rotating shaft and the inner surface of the inner housing. Therefore, if grease gets into this space, there is a risk that the pressure adjustment passage will be blocked and air will not be able to escape to the outside.

[0005] Therefore, an object of the present disclosure is to provide an impact tool that can effectively release pressure that has increased in a drive mechanism accommodating area due to heat generation from the drive mechanism. [Means for solving the problem]

[0006] In order to achieve the above object, the present disclosure provides a housing having: A motor; A cylindrical tool holder on the front end of which a bit can be attached; A drive mechanism capable of striking the bit; The drive mechanism is provided hand Rotates due to the rotation of the output shaft of the motor , for striking the bit and / or for transmitting rotation to the tool holder A rotation axis; a drive mechanism accommodating region that hermetically accommodates the drive mechanism within the housing, An air escape passage is formed inside the rotating shaft to allow air in the drive mechanism housing area to escape to the outside of the drive mechanism housing area, and an inlet of the air escape passage is provided on the outer circumferential surface of the rotating shaft. A through hole passing through the rotation shaft perpendicularly It is characterized in that it is formed. In order to achieve the above object, another configuration of the present disclosure includes: A motor; A cylindrical tool holder on the front end of which a bit can be attached; A drive mechanism capable of striking the bit; a rotating shaft for striking the bit and / or transmitting rotation to the tool holder, the rotating shaft being provided in the drive mechanism and rotated by rotation of the output shaft of the motor; a drive mechanism accommodating region that hermetically accommodates the drive mechanism within the housing, The rotating shaft is formed with a spline portion to which a clutch for switching operating modes is slidably connected, and an air escape passage is formed inside the rotating shaft to allow air within the drive mechanism accommodating area to escape to the outside of the drive mechanism accommodating area, and the inlet of the air escape passage is located in the spline portion. Effect of the Invention

[0007] According to the present disclosure, since the inlet of the air release passage is formed on the outer circumferential surface of the rotating shaft, centrifugal force makes it difficult for grease in the drive mechanism housing area to enter the air release passage, and therefore pressure built up in the drive mechanism housing area due to heat generation by the drive mechanism can be effectively released. In particular, since the entrance to the air escape passage is formed by a through hole that penetrates the rotation shaft perpendicularly, air can enter from both ends of the through hole, and even if one end is clogged with grease, air can still enter from the other end. According to another configuration of the present disclosure, a spline portion is formed on the rotating shaft to which a clutch for switching operating modes is slidably coupled, and the inlet of the air escape passage is disposed in the spline portion, so that the grease is splashed away by the rotating spline teeth, and the ingress of grease into the inlet is preferably prevented. [Brief description of the drawings]

[0008] [Figure 1] FIG. 2 is a rear perspective view of the hammer drill. [Diagram 2] FIG. 2 is a central vertical cross-sectional view of the hammer drill. [Diagram 3] FIG. 3 is an enlarged view of a drive mechanism portion in FIG. [Figure 4] FIG. 4 is a cross-sectional view taken along line AA in FIG. [Diagram 5] FIG. 2 is an exploded perspective view of an outer housing, a motor housing, and an inner housing. [Figure 6] FIG. [Figure 7] FIG. 4 is a cross-sectional view taken along line BB in FIG. [Figure 8] 4 is an enlarged front view of the inner housing and the motor housing with the outer housing omitted. FIG. [Figure 9] FIG. [Figure 10] FIG. 9 is a cross-sectional view taken along line FF in FIG. 8 (with outer housing). [Figure 11] 4 is a cross-sectional view taken along line CC in FIG. [Figure 12] 8 is a cross-sectional view taken along line DD in FIG. 7. [Figure 13] 8 is a cross-sectional view taken along line EE in FIG. 7. [Figure 14] FIG. 4 is an exploded perspective view of a first intermediate shaft portion. [Figure 15] 12 is a cross-sectional view taken along line GG in FIG. 11. [Figure 16] FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] In one embodiment of the present disclosure, a bearing for supporting the rotating shaft may be provided in the drive mechanism accommodating area, and the outlet of the air escape passage may be formed on the opposite side of the drive mechanism accommodating area to the bearing in the axial direction of the rotating shaft. With this configuration, the air escape passage can be formed over a short distance in the axial direction of the rotating shaft. In one embodiment of the present disclosure, the bearing may be a sealed bearing, which reduces the risk of grease leaking from the bearing into the air escape passage. In one embodiment of the present disclosure, the inlet of the air release passage may be disposed at a middle portion in the axial direction of the rotating shaft. With this configuration, it becomes even more difficult for grease in the drive mechanism accommodating area to enter through the inlet.

[0010] In one embodiment of the present disclosure, the drive mechanism accommodating area is formed by an inner housing having a retaining recess provided within the housing for retaining the bearing, and a ring-shaped peripheral wall protruding toward the drive mechanism accommodating area may be formed around the retaining recess. With this configuration, it is difficult for grease to enter the retaining recess along the inner surface of the inner housing. In one embodiment of the present disclosure, the rotating shaft may be provided with a gear adjacent to the peripheral wall portion in the axial direction. With this configuration, the grease is blown away by the rotating gear, and the intrusion of the grease into the gap between the gear and the peripheral wall portion can be suitably prevented. In one embodiment of the present disclosure, the drive mechanism has a rotation operating part that rotates the tool holder, and also has a rotation shaft for transmitting rotation to the tool holder and a rotation shaft for striking the bit, and the rotation shaft in which the inlet of the air release passage is formed may be the rotation shaft for transmitting rotation. With this configuration, the air release passage can be easily formed. EXAMPLES

[0011] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. (Outline of the hammer drill) Fig. 1 is a perspective view showing an example of a hammer drill, Fig. 2 is a central vertical cross-sectional view of the hammer drill, Fig. 3 is an enlarged view of a drive mechanism portion in Fig. 2, and Fig. 4 is a cross-sectional view taken along line AA in Fig. 3. The hammer drill 1 has a housing 2 that forms an outer shell. The housing 2 has an outer housing 3 on the front side, a motor housing 4 behind it, and a handle housing 5 behind it. The motor housing 4 has a connecting portion 6 on the front side that is rectangular in front view, and a cylindrical motor accommodating portion 7 on the rear side. As shown in Fig. 5, the connecting portion 6 is connected to the outer housing 3 at the four corners in front view from the front by four screws 8, 8.... A motor 9 is accommodated in the motor accommodating portion 7 with its output shaft 10 facing forward. The handle housing 5 is fitted from the rear side to the motor accommodating portion 7 and is relatively movable in the front-rear direction. The handle housing 5 is biased to the retracted position via a vibration-proof mechanism using a coil spring 11.

[0012] A handle 12 extending downward is formed at the rear end of the handle housing 5. A switch 13 with a trigger 14 protruding forward is housed inside the handle 12. A power cord 15 is connected to the switch 13. The power cord 15 is pulled out from the lower end of the handle 12. A plurality of air intakes 16, 16... extending in the front-rear direction are formed on the left and right side surfaces of the handle 12, respectively. The left and right air intakes 16 are arranged to face each other with the axis of the output shaft 10 in between. An output shaft 10 of the motor 9 passes through the connecting portion 6 and protrudes into the outer housing 3. A pinion 17 is formed at the front end of the output shaft 10. A fan 18 is fixed to the output shaft 10 within the connecting portion 6. A baffle plate 19 is fixed within the connecting portion 6 behind the fan 18. A plurality of rear exhaust ports 20, 20... are formed on the lower surface and right side surface of the connecting portion 6 radially outside the fan 18.

[0013] The outer housing 3 has a front tubular portion 21 and a rear tubular portion 22. The front tubular portion 21 is tubular with a circular cross section that extends forward. The rear tubular portion 22 is tubular with a larger diameter than the front tubular portion 21 and has a hexagonal shape when viewed from the front. The front tubular portion 21 is disposed at an eccentric position above the rear tubular portion 22. A cylindrical tool holder 23 is coaxially housed within the front cylindrical portion 21. The front end of the tool holder 23 protrudes forward from the front cylindrical portion 21. A bearing 24 that supports the front part of the tool holder 23 is held at the front end of the front cylindrical portion 21. An oil seal 25 that seals between the front cylindrical portion 21 and the tool holder 23 is provided in front of the bearing 24. An operation sleeve 26 is provided at the front end of the tool holder 23 protruding from the front cylindrical portion 21. The operation sleeve 26 is provided for attaching and detaching the bit B at the front end of the tool holder 23. A side grip 27 is attached to the front end of the front cylindrical portion 21.

[0014] A drive mechanism 30 is provided inside the outer housing 3. The drive mechanism 30 has a rotation / impact operating section 31 and a rotation / impact switching section 32 behind the rotation / impact operating section 31. The rotation / impact operating unit 31 has a tool holder 23, a piston cylinder 33, a striker 34, and an impact bolt 35. The piston cylinder 33 has an open front end and is housed at the rear of the tool holder 23 so as to be movable back and forth. The striker 34 is housed in the piston cylinder 33 via an air chamber 36 so as to be movable back and forth. The impact bolt 35 is housed in front of the striker 34 in the tool holder 23 so as to be movable back and forth. The tool holder 23 communicates with the inside of the front tubular portion 21 through a plurality of through holes 37, 37. The rear of the tool holder 23 protrudes into the rear tubular portion 22. A gear 38 with a torque limiter is provided on the outer periphery of the tool holder 23 in the rear tubular portion 22. An inner housing 40 is housed within the connecting portion 6 and the rear cylindrical portion 22. The inner housing 40 supports the rear portion of the tool holder 23 on the rear side of the gear 38. A rotation / impact switching unit 32 is housed within the inner housing 40. The rotation / impact switching unit 32 switches operation modes and transmits the rotation of the output shaft 10 to the rotation / impact operating unit 31 by operating a switching knob 116 provided on the underside of the rear cylindrical portion 22.

[0015] (Inner housing explanation) The inner housing 40 is divided into two parts, a front housing 41 made of metal and a rear housing 42 made of resin. As shown in FIG. 6, the front housing 41 includes a front bearing holder 43 and a rear body portion 44. The bearing retaining portion 43 has a hexagonal shape when viewed from the front and is slightly smaller than the rear cylindrical portion 22. As shown in Fig. 7, the bearing retaining portion 43 has an upper through hole 45 at the center in the left-right direction at the upper portion. The rear portion of the tool holder 23 is inserted into the upper through hole 45. A bearing metal 46 that supports the rear portion of the tool holder 23 is held inside the upper through hole 45. A lower through hole 47 having a smaller diameter than the upper through hole 45 is formed on the lower left side of the upper through hole 45. A groove 48 is formed around the entire circumference of the outer circumferential surface of the bearing holder 43, radially outside the bearing metal 46. An O-ring 49 is held in the groove 48. The O-ring 49 presses against the inner circumferential surface of the rear tubular portion 22 to seal between the rear tubular portion 22 and the bearing holder 43. Thus, the space between the outer housing 3 and the inner housing 40 is divided into front and rear portions by the O-ring 49. The front of the space between the tool holder 23 and the outer housing 3 in front of the O-ring 49 is sealed by the oil seal 25.

[0016] An inner rib 50 is formed on the front surface of the bearing holder 43 facing forward. As shown in FIG. 8, the inner rib 50 is formed in an arc shape in front view so as to surround from below the lower half of the gear 38 of the tool holder 23 protruding from the upper through hole 45. The front end of the inner rib 50 overlaps the gear 38 in the radial direction. However, the left side of the inner rib 50 is a semicircular part 51 that surrounds the lower through hole 47 from the outside. The inner rib 50 divides the front surface of the bearing holder 43 surrounded by the O-ring 49 into upper and lower parts. The left and right ends of the inner rib 50 are inclined parts 50a, 50a that recede as they go upward. The front end of the middle part of the inner rib 50 is located furthest forward from the bearing holder 43. On the other hand, in the outer housing 3, an outer rib 52 is formed on the front inner surface of the rear tubular portion 22, as shown in Fig. 9, which protrudes rearward in opposition to the inner rib 50 of the bearing holder 43. The outer rib 52 protrudes below the gear 38 when the inner housing 40 is assembled, and is pressed against the front end of the inner rib 50, causing its rear end to deform, thereby forming a rib that comes into close contact with the inner rib 50 (a so-called crushed rib). The outer rib 52 has a mirror finish on the front and rear sides compared to the inner rib 50. Symmetric The outer rib 52 has a semicircular portion 53 on the left side that faces the semicircular portion 51. Upper ends 52a, 52a on both left and right ends of the outer rib 52 protrude forward and come into contact with the front surface of the bearing holder 43, as shown in FIG. ,52a The rear edge of the inner rib 50 has an inclined shape that advances as it goes downward, and matches the inclined portions 50 a, 50 a at both left and right ends of the inner rib 50 .

[0017] 10, when the inner housing 40 is assembled to the outer housing 3, the outer rib 52 and the inner rib 50 butt against each other to form a partition wall 54. Therefore, the space in front of the O-ring 49 inside the outer housing 3 is divided into upper and lower spaces by the partition wall 54. The upper side of the partition wall 54 becomes a front grease chamber 55 that is divided by the oil seal 25 and the O-ring 49. The front grease chamber 55 communicates with a rear grease chamber 56 in the inner housing 40 via the lower through-hole 47, etc. The front grease chamber 55 and the rear grease chamber 56 form a drive mechanism accommodating area T (hereinafter abbreviated as "accommodating area").

[0018] The body portion 44 is a cylinder having a hexagonal shape when viewed from the front, which is slightly smaller than the bearing holding portion 43. A plurality of heat dissipation fins 57, 57·· are provided on the left and right side surfaces of the body portion 44. Each heat dissipation fin 57 is formed to extend in the up-down direction and is provided at a predetermined interval in the front-rear direction. The outer edge of each heat dissipation fin 57 is close to the inner surface of the rear cylindrical portion 22, as shown in FIG. 11. A plurality of front exhaust ports 58, 58·· extending in the front-rear direction are formed on the left and right side surfaces of the rear cylindrical portion 22 on the outside of the protruding direction of the heat dissipation fin 57. The left and right front exhaust ports 58 are arranged to face each other across the axial direction of the output shaft 10 in a plan view. A front flange 59 having a rectangular shape when viewed from the front is formed at the rear end of the body portion 44. Four semicircular notches 60, 60... are formed at the four corners of the front flange 59.

[0019] 3 and 11, the rear housing 42 has a rear through-hole 65 in approximately the center. The output shaft 10 passes through the rear through-hole 65. A bearing 66 that supports the output shaft 10 is held in the rear portion of the rear through-hole 65. An oil seal 67 is provided in front of the bearing 66. A rear flange 68 having a rectangular shape in front view, the same as the front flange 59 of the body portion 44, is formed at the front end of the rear housing 42. Four semicircular notches 69, 69... are also formed at the four corners of the rear flange 68. The front flange 59 and the rear flange 68 are sandwiched between the rear tubular portion 22 of the outer housing 3 and the connecting portion 6 of the motor housing 4 in a front-to-rear overlapping state. As shown in Figures 5, 7 and 9, the rear end of the rear tubular portion 22 is formed with four screw fastening portions 70, 70... that protrude from the four corners in a front view. The rear surface of each screw fastening portion 70 is formed with a circular screw boss 71 that protrudes rearward. On the other hand, as shown in Fig. 5 and Fig. 8, four female threaded portions 72, 72... having female threaded holes are formed at the four corners of the connecting portion 6, corresponding to the screw fastening portions 70. A circular recess 73 into which the screw boss 71 fits is formed on the front surface of each female threaded portion 72. That is, as shown in Fig. 12, each screw boss 71 is fitted into the circular recess 73 in a screw fastening state by the screw 8, forming a spigot connection.

[0020] The front flange 59 and the rear flange 68 are sandwiched between the screw fastening portion 70 and the female screw portion 72 with the notches 60, 69 at the four corners engaging with the outer periphery of the screw boss 71 from the inside. In this state, the screw fastening portions 70 and the female screw portions 72 are screwed from the front with the screws 8, 8.... This completes the connection between the outer housing 3 and the motor housing 4, and the front flange 59 and the rear flange 68 are pressed from both the front and rear sides and assembled. At this time, the rear end faces of the screw fastening portions 70 and the front end faces of the female screw portions 72 are not in contact with each other. In this manner, the inner housing 40 is positioned at the rear of the outer housing 3. In this positioned state, a gap S is formed on the upper side between the rear tubular portion 22 and the front and rear flanges 59, 68, as shown in Figures 3 and 11. Therefore, the inside of the connecting portion 6 in which the fan 18 is housed communicates with the gap S behind the O-ring 49. The gap S communicates with the space between the rear tubular portion 22 and the front housing 41, and communicates with the front exhaust port 58 through the heat dissipation fins 57. 6, a groove 74 is formed around the entire periphery of the front surface of the rear flange 68 where it abuts against the front flange 59. An O-ring 75 is held in the groove 74. The O-ring 75 abuts against the rear surface of the front flange 59 when the inner housing 40 is assembled to provide a seal between the front flange 59 and the rear flange 68.

[0021] (Explanation of rotation / impact switching section) 6, 7, 11 and 13, the rotation / impact switching unit 32 is provided with first and second intermediate shafts 80, 81 on the left and right sides below the tool holder 23. The first and second intermediate shafts 80, 81 are arranged parallel to each other and to the tool holder 23. As shown in FIG. 14, the rear end of the left first intermediate shaft 80 is rotatably supported by the rear housing 42 via a bearing 82. The front end of the first intermediate shaft 80 passes through the lower through-hole 47 of the front housing 41 and extends forward. The front end of the first intermediate shaft 80 is rotatably supported by the front inner surface of the rear cylindrical portion 22 via a bearing 83. A first gear 84 that meshes with the pinion 17 of the output shaft 10 is rotatably mounted on the rear portion of the first intermediate shaft 80. A washer 84a is mounted on the exterior between the bearing 82 and the first gear 84. A gear side engagement portion 85 consisting of a plurality of claws is formed on the outer periphery of the front portion of the first gear 84.

[0022] A second gear 86 is formed on the front portion of the first intermediate shaft 80, forward of the lower through-hole 47. The second gear 86 meshes with the gear 38 of the tool holder 23. A washer 86a is fitted between the second gear 86 and the bearing 83. A first spline portion 87 is formed on the first intermediate shaft 80 in front of the first gear 84. A first clutch 88 is spline-connected to the first spline portion 87. The first clutch 88 is provided so as to be rotatable integrally with the first intermediate shaft 80 and movable back and forth, and includes a rear engagement portion 89 and a front engagement portion 90 each composed of a plurality of pawls. When the first clutch 88 is in the retracted position shown in FIG. 13, the rear engagement portion 89 engages with the gear side engagement portion 85 of the first gear 84. Thus, the rotation of the first gear 84 is transmitted to the first intermediate shaft 80 via the first clutch 88.

[0023] A lock ring 91 is held in the lower through hole 47 of the front housing 41 in front of the first clutch 88. The lock ring 91 has four anti-rotation pieces 92, 92... arranged at equal intervals in the circumferential direction on its outer periphery. The rear end of each anti-rotation piece 92 forms a claw 92a that protrudes rearward beyond the rear end surface of the lock ring 91. Four grooves 47a, 47a... are formed on the inner surface of the lower through hole 47 with which the four anti-rotation pieces 92 engage. Thus, the lock ring 91 is held in a state in which its rotation is restricted within the lower through hole 47. In this state, the cylindrical inner circumferential surface 47b of the lower through hole 47 excluding the grooves 47a evenly holds the outer circumferential surface of the lock ring 91 around the axis of the first intermediate shaft 80. A coil spring 93 is housed in front of the lock ring 91 inside the lower through-hole 47. The lock ring 91 is biased rearward by the coil spring 93. A stop ring 94 against which the claws 92a abut is held behind the lock ring 91. Thus, the lock ring 91 is biased to a retracted position in which it abuts against the stop ring 94.

[0024] The front engagement portion 90 of the first clutch 88 has eight pawls 90a, 90a... which is more than the four pawls 92a of the lock ring 91. In the forward position, the first clutch 88 is separated from the first gear 84, and the pawls 90a of the front engagement portion 90 engage with the pawls 92a of the lock ring 91 in the rotational direction. Therefore, the rotation of the first gear 84 is not transmitted to the first intermediate shaft 80, and the rotation of the first intermediate shaft 80 together with the first clutch 88 is locked. When the rotation of the first intermediate shaft 80 is locked in this manner, the rotation of the tool holder 23 is also locked via the gear 38 that meshes with the second gear 86 of the first intermediate shaft 80 . However, when the first clutch 88 is in an intermediate position between the forward position and the reverse position, it is not engaged with either the first gear 84 or the lock ring 91.

[0025] In the first intermediate shaft 80, a through hole 80a is formed in the first spline portion 87 behind the lock ring 91. The through hole 80a has a circular cross section and is formed penetrating the first spline portion 87 in the radial direction. A shaft center hole 80b is formed in the shaft center of the first intermediate shaft 80. The shaft center hole 80b has a circular cross section with a smaller diameter than the through hole 80a, and its front end communicates with the through hole 80a. The rear end of the shaft center hole 80b opens into the rear end face of the first intermediate shaft 80. A retaining recess 42a that retains the bearing 82 is formed on the front surface of the rear housing 42. A relief hole 76 is formed through the rear housing 42 behind the retaining recess 42a. The relief hole 76 is tapered toward the rear. The relief hole 76 communicates with the rear end of the shaft hole 80b via the bottom of the retaining recess 42a. The bearing 82 is a sealed bearing, with both the front and rear axial surfaces sealed. A ring-shaped peripheral wall portion 42b is formed around the holding recess 42a and protrudes forward beyond the bearing 82. The front end of the peripheral wall portion 42b is adjacent to the rear surface of the first gear 84. Thus, inside the inner housing 40, air escape paths 77 are formed that extend from the inlets at both ends of the through hole 80a, through the axial hole 80b and the bottom of the holding recess 42a, to the exit at the rear end of the escape hole 76. Therefore, the inside of the inner housing 40 communicates with the outside of the inner housing 40 through the air escape path 77. An absorbent material 78 such as a sponge that closes the rear end of the escape hole 76 is held on the rear surface of the rear housing 42.

[0026] The right second intermediate shaft 81 has a rear end rotatably supported by the rear housing 42 via a bearing 95. The front end of the second intermediate shaft 81 is rotatably supported by the bearing holder 43 of the front housing 41 via a bearing 96. A third gear 97 meshing with the pinion 17 of the output shaft 10 is fixed to the rear part of the second intermediate shaft 81 so as to be rotatable together with the second intermediate shaft 81. A boss sleeve 98 is separately rotatably mounted on the second intermediate shaft 81 in front of the third gear 97. A swash bearing 99 with an inclined axis is provided on the boss sleeve 98. An arm 100 is provided on the outer ring of the swash bearing 99 so as to protrude upward. The tip of the arm 100 is connected to the rear end of the piston cylinder 33. A coil spring 101 is interposed between the rear end of the piston cylinder 33 and the rear housing 42. The coil spring 101 biases the piston cylinder 33 to a forward position in a drill mode to be described later. A boss side engagement portion 102 is formed at the front portion of the boss sleeve 98 .

[0027] A second spline portion 103 is formed on the second intermediate shaft 81 in front of the boss sleeve 98. A second clutch 104 is splined to the second spline portion 103. The second clutch 104 is provided so as to be rotatable integrally with the second intermediate shaft 81 and movable back and forth, and has a clutch-side engaging portion 105 at its rear. When the second clutch 104 is in the retracted position, the clutch-side engaging portion 105 engages with the boss-side engaging portion 102 of the boss sleeve 98. Thus, the rotation of the second intermediate shaft 81 is transmitted to the boss sleeve 98 via the second clutch 104. When the second clutch 104 moves forward, the clutch-side engaging portion 105 moves away from the boss-side engaging portion 102, and the rotation of the second intermediate shaft 81 is no longer transmitted to the boss sleeve 98.

[0028] A mode switching mechanism 109 is provided below the first and second intermediate shafts 80, 81. The mode switching mechanism 109 has two rods, first and second rods 110, 111 on the left and right, and a switching knob 116, as shown in FIG. The first and second rods 110, 111 are provided parallel to each other and parallel to the first and second intermediate shafts 80, 81. The first rod 110 has a rear end supported by the rear housing 42 and a front end supported by the bearing holder 43 of the front housing 41. The first rod 110 includes a first plate 112. The first plate 112 is a strip whose middle portion extends parallel to the first rod 110. Both front and rear ends of the first plate 112 are bent toward the first rod 110 and penetrated by the first rod 110. Thus, the first plate 112 can move forward and backward along the first rod 110. The front end of the first plate 112 engages with the outer periphery of the first clutch 88. A coil spring 113 is fitted to the first rod 110 in front of the first plate 112. The coil spring 113 biases the first plate 112 to a retreated position where the first plate 112 abuts against the front surface of the rear housing 42. This retreated position is the retreated position of the first clutch 88 which retreats together with the first plate 112.

[0029] The second rod 111 has a rear end supported by the rear housing 42 and a front end supported by the bearing holder 43 of the front housing 41. The second rod 111 includes a second plate 114. The second plate 114 is a strip whose middle portion extends parallel to the second rod 111. Both front and rear ends of the second plate 114 are bent toward the second rod 111 and penetrated by the second rod 111. Thus, the second plate 114 can move forward and backward along the second rod 111. The front end of the second plate 114 engages with the outer periphery of the second clutch 104. A coil spring 115 is fitted to the second rod 111 in front of the second plate 114. The coil spring 115 biases the second plate 114 to a retreated position where it abuts against the rear housing 42. This retreated position is the retreated position of the second clutch 104 which retreats together with the second plate 114.

[0030] The positions of the first and second plates 112, 114 can be changed by a switching knob 116. The switching knob 116 is rotatably provided on the underside of the rear cylindrical portion 22, as shown in Fig. 16. The switching knob 116 protrudes into the inner housing 40 through a bottom through-hole 117 provided on the underside of the body portion 44 of the front housing 41, as shown in Figs. 3 and 11. Two first and second eccentric pins 118, 119 are provided on the protruding end surface of the switching knob 116. The first eccentric pin 118 engages with the front end of the first plate 112 from the rear, and the second eccentric pin 119 engages with the middle portion of the second plate 114. Engage from the rear is doing. Therefore, by rotating the switching knob 116, the front and rear positions of the first and second plates 112, 114 can be switched via the first and second eccentric pins 118, 119. In other words, the operation mode can be switched between drill mode, hammer drill mode, hammer mode (rotation locked), and hammer mode (neutral).

[0031] (Explanation of how the hammer drill works) The switch knob 116 is switched to the drill mode. Then, the first eccentric pin 118 is in the most rearward position, and the first clutch 88 is in the rearward position together with the first plate 112. Therefore, the rotation of the first gear 84 is transmitted to the first intermediate shaft 80 via the first clutch 88. Then, the rotation of the first intermediate shaft 80 is transmitted to the tool holder 23 via the second gear 86 and the gear 38. On the other hand, the second eccentric pin 119 is in the most forward position, and the second clutch 104 is in the forward position together with the second plate 114. Therefore, the rotation of the second intermediate shaft 81 transmitted from the output shaft 10 is not transmitted to the boss sleeve 98. Therefore, when the trigger 14 is pressed to turn on the switch 13, the motor 9 is driven to rotate the output shaft 10. Then, the tool holder 23 rotates via the first intermediate shaft 80, causing the bit B at the tip to rotate.

[0032] Next, the switch knob 116 is switched to the hammer drill mode, whereupon the first eccentric pin 118 remains in the most retracted position, and the first plate 112 and the first clutch 88 remain in the retracted position. On the other hand, the second eccentric pin 119 retracts from the most forward position to the intermediate position, and the second clutch 104 is in the retracted position together with the second plate 114. Therefore, the rotation of the second intermediate shaft 81 is transmitted to the boss sleeve 98 via the second clutch 104. Therefore, when the trigger 14 is depressed to drive the motor 9, the tool holder 80 is driven via the first intermediate shaft 80. 23 rotates, rotating the bit B at the tip. At the same time, the boss sleeve 98 rotates, causing the arm 100 to swing back and forth, causing the piston cylinder 33 to reciprocate. As a result, the striker 34 reciprocates, striking the bit B via the impact bolt 35.

[0033] Next, the switching knob 116 is switched to hammer mode (rotation locked). Then, the first eccentric pin 118 is in the most forward position. The first clutch 88 is in the forward position together with the first plate 112 and engages with the lock ring 91. Therefore, the rotation of the first gear 84 is not transmitted to the first intermediate shaft 80, and the rotation of the tool holder 23 together with the first intermediate shaft 80 is locked. On the other hand, the second eccentric pin 119 is in the most retracted position, and the second clutch 104 remains in the retracted position. Therefore, the rotation of the second intermediate shaft 81 is transmitted to the boss sleeve 98 via the second clutch 104. Therefore, when the trigger 14 is depressed to drive the motor 9, the piston cylinder 33 reciprocates with the rotation of the tool holder 23 locked, and the bit B is struck by the striker 34 via the impact bolt 35. When the first clutch 88 moves forward, the front surface of the pawl 90a of the front engagement portion 90 may come into contact with the rear surface of the pawl 92a of the lock ring 91, resulting in no engagement in the rotational direction. In this case, however, the lock ring 91 moves forward against the bias of the coil spring 93, allowing the first clutch 88 to move forward. Therefore, when the first intermediate shaft 80 rotates due to friction with the first gear 84 and the first clutch 88 rotates, the lock ring 91 retreats at a phase where the pawl 90a engages with the pawl 92a and engages with the first clutch 88. Therefore, the rotation of the first intermediate shaft 80 is locked.

[0034] Next, the switching knob 116 is switched to hammer mode (neutral). Then, the first eccentric pin 118 retracts from the most forward position to the intermediate position. The first clutch 88 retracts together with the first plate 112 and moves away from the lock ring 91. However, the first clutch 88 is in the intermediate position where it is not engaged with the first gear 84. Therefore, the rotation of the first gear 84 is not transmitted to the first intermediate shaft 80, and the tool holder 23 together with the first intermediate shaft 80 are free to rotate. On the other hand, the second eccentric pin 119 advances from the most rearward position to the intermediate position, and the second clutch 104 moves to the rearward position together with the second plate 114. Therefore, the rotation of the second intermediate shaft 81 is transmitted to the boss sleeve 98 via the second clutch 104. Therefore, when the trigger 14 is depressed to drive the motor 9, the piston cylinder 33 reciprocates in a state in which the tool holder 23 is free to rotate, and the bit B is struck by the striker 34 via the impact bolt 35.

[0035] When the hammer drill 1 operates in each operation mode, the fan 18 rotates due to the rotation of the output shaft 10. Then, outside air is sucked into the motor accommodating section 7 of the motor housing 4 from the rear air intake 16, and moves forward to cool the motor 9. This cooling air flows into the connecting section 6, and a part of it is discharged to the outside from the rear exhaust port 20. The other part moves forward inside the connecting section 6, and flows into the rear cylindrical section 22 through the gap S between the rear cylindrical section 22 and the front and rear flanges 59, 68. Then, the cooling air passes through the outer space of the inner housing 40 and is discharged from the front exhaust port 58. At this time, the cooling air comes into contact with the front housing 41, thereby suppressing a temperature rise of the front housing 41 due to heat generated by the drive mechanism 30. In particular, since the cooling air flows along the heat dissipation fins 57, the heat of the front housing 41 is effectively dissipated. On the other hand, the storage area T is filled with grease. In particular, the front grease chamber 55 in the front tubular portion 21 is a narrow space with no wasted space due to the partition wall 54, so that the filling rate of the grease in the front grease chamber 55 is high. Therefore, the grease scattered from the rotating / impacting portion 31 is likely to reattach to the gear 38 and the like.

[0036] Heat generated by the drive mechanism 30 may cause the air to expand, increasing the pressure in the accommodation region T. As a result, the air in the rear grease chamber 56 enters the air release passage 77 from both ends of the through hole 80a of the first intermediate shaft 80. The air then passes through the through hole 80a, the axial hole 80b, the bottom of the holding recess 42a, and the release hole 76 to be discharged to the outside of the inner housing 40. As a result, the pressure in the rear grease chamber 56 is released. At this time, the through hole 80a, which serves as the entrance to the air release passage 77, is located on the circumferential surface of the first intermediate shaft 80, so that the centrifugal force generated when the first intermediate shaft 80 rotates makes it difficult for the grease in the rear grease chamber 56 to enter through the through hole 80a. In particular, since the through hole 80a is formed in the first spline portion 87, the grease is splashed off by the rotating spline teeth, and the intrusion of the grease into the through hole 80a is suitably prevented. In addition, since the peripheral wall portion 42b is formed at the opening of the holding recess 42a, it is difficult for grease to enter the holding recess 42a along the front surface of the rear housing 42. In particular, since the peripheral wall portion 42b is adjacent to the first gear 84, the grease is blown away by the rotating first gear 84, and the grease is also suitably prevented from entering the gap between the first gear 84 and the peripheral wall portion 42b. Even if the grease climbs over the peripheral wall portion 42b, the sealed bearing 82 prevents the grease from flowing into the bottom of the holding recess 42a.

[0037] (Effects of the invention related to the air escape path) The hammer drill 1 (impact tool) of the above embodiment has, within a housing 2, a motor 9, a cylindrical tool holder 23 to which a bit B can be attached at its front end, and a drive mechanism 30 capable of striking the bit B. The hammer drill 1 also has a first intermediate shaft 80 (rotating shaft) that is provided in the drive mechanism 30 and rotates by rotation of an output shaft 10 of the motor 9, and an accommodation region T that accommodates the drive mechanism 30 in a sealed state within the housing 2. The hammer drill 1 has an air escape passage 77 formed inside the first intermediate shaft 80 to allow air within the accommodation region T to escape to the outside of the accommodation region T, and a through hole 80a serving as an entrance of the air escape passage 77 formed in the outer circumferential surface of the first intermediate shaft 80. According to this configuration, the centrifugal force of the first intermediate shaft 80 makes it difficult for the grease in the rear grease chamber 56 to enter through the air release passage 77. Therefore, the pressure that has increased in the accommodation area T due to heat generation of the drive mechanism 30 can be effectively released.

[0038] The inlet of the air release passage 77 is formed by a through hole 80a that perpendicularly penetrates the first intermediate shaft 80. Therefore, air can enter from both ends of the through hole 80a, and even if one end is clogged with grease, air can still enter from the other end. A bearing 82 that supports the first intermediate shaft 80 is provided within the accommodation region T, and the outlet of the air escape passage 77 is formed on the opposite side of the accommodation region T across the bearing 82 in the axial direction of the first intermediate shaft 80. Therefore, the air escape passage 77 can be formed over a short distance in the axial direction of the first intermediate shaft 80. The bearing 82 is a sealed bearing, which reduces the risk of grease flowing from the bearing 82 into the air escape path 77. The through hole 80a is disposed in an axially intermediate portion of the first intermediate shaft 80. This makes it even more difficult for the grease in the rear grease chamber 56 to enter through the through hole 80a. The first intermediate shaft 80 is formed with a first spline portion 87 (spline portion) to which a first clutch 88 (clutch) for switching operation modes is slidably coupled, and the through hole 80a is disposed in the first spline portion 87. Therefore, the grease is splashed away by the rotating spline teeth, and the intrusion of the grease into the through hole 80a is suitably prevented.

[0039] The accommodation area T is formed by the inner housing 40 having a retaining recess 42a that is provided in the housing 2 and retains the bearing 82, and a ring-shaped peripheral wall portion 42b that protrudes toward the accommodation area T is formed around the retaining recess 42a. This makes it difficult for grease to enter the retaining recess 42a along the inner surface of the inner housing 40. A first gear 84 (gear) adjacent to the peripheral wall portion 42b in the axial direction is provided on the first intermediate shaft 80. Therefore, the grease is blown away by the rotating first gear 84, and it is also possible to suitably prevent the grease from entering the gap between the first gear 84 and the peripheral wall portion 42b. The drive mechanism 30 has a rotation / impact operating unit 31 (rotation operating unit) that rotates the tool holder 23, as well as a first intermediate shaft 80 (rotation shaft) for transmitting rotation to the tool holder 23 and a second intermediate shaft 81 (rotation shaft) for striking the bit B, and the rotation shaft in which the through hole 80a is formed is the first intermediate shaft 80 for transmitting rotation. Therefore, the air escape path 77 can be easily formed.

[0040] In addition, the invention relating to the air escape path can be modified as follows. The position of the inlet of the air release passage is not limited to the middle part of the intermediate shaft as in the above embodiment. The inlet may be located near the front end or rear end as long as it is on the outer circumferential surface of the rotating shaft. The inlet does not have to be provided in the spline portion. The inlet does not have to be a through hole. For example, the inlet may be formed as a bottomed hole having one end that opens to the circumferential surface of the rotating shaft and the other end that remains inside the rotating shaft. The through hole and the bottomed hole may be formed so as to be inclined toward the axial direction of the rotating shaft rather than being formed in the radial direction of the rotating shaft. The size and shape of the cross-sectional area of ​​the air release passage are not limited to the above. As long as it is in the above-mentioned form, the axial hole may be the same diameter as the through hole or may be larger in diameter than the through hole. The cross section of the air release passage does not have to be circular. The air escape passage may be provided in the intermediate shaft for impact. If there is only one intermediate shaft, the air escape passage may be provided in that intermediate shaft. The air escape passage may be provided in other rotating shafts, not limited to the intermediate shaft for switching between rotation and impact. The present invention is not limited to application to a hammer drill, but may also be applied to other impact tools such as an electric hammer. The impact tool is not limited to a structure in which a piston cylinder is reciprocated by an intermediate shaft (which may be one shaft) and a rotation conversion member. For example, the impact tool may be an impact tool that employs a crank mechanism and reciprocates a piston cylinder with a connecting rod.

[0041] (Tool holder lock ring (Effects of the invention related to The hammer drill 1 of the above embodiment includes, within a housing 2, a motor 9, a rotatable cylindrical tool holder 23 with a bit B attached to its front end, and a drive mechanism 30 capable of rotating the tool holder 23 and / or striking the bit B. The hammer drill 1 also includes a mode switching mechanism 109 that switches the operation mode of the drive mechanism 30 between at least a hammer mode in which only the striking action of the bit B is performed, and a hammer drill mode in which the tool holder 23 is rotated and the bit B is struck. The drive mechanism 30 also includes a first intermediate shaft 80 (rotation transmission shaft) for transmitting the rotation of the output shaft 10 of the motor 9 to the tool holder 23, and the first intermediate shaft 80 is provided with a first clutch 88 (rotation transmission member) for transmitting the rotation to the tool holder 23. A lock ring 91 (lock member) is disposed on the axis of the first intermediate shaft 80, with which the first clutch 88 engages to restrict rotation of the tool holder 23. The lock ring 91 is held evenly around the axis of the first intermediate shaft 80 by the front housing 41 within the housing 2, via the lower through-hole 47. According to this configuration, the lock ring 91 is disposed on the axis of the first intermediate shaft 80, which saves space and leads to a more compact housing 2. Furthermore, even if a rotational force is applied from the tool holder 23 side when restricting rotation, twisting and tilting of the lock ring 91 is suppressed. Therefore, it is possible to restrict rotation of the tool holder 23 in a space-saving manner and at low cost.

[0042] The lock ring 91 is ring-shaped, and therefore can be installed in a space-saving manner around the first intermediate shaft 80. In addition, twisting and tilting are less likely to occur. The rotation transmission member is a first clutch 88 (clutch) that is provided on the first intermediate shaft 80 and switches the rotation transmission to the tool holder 23. Therefore, the rotation of the tool holder 23 can be easily restricted by using the first clutch 88. In accordance with a switching operation by the mode switching mechanism 109, the first clutch 88 slides on the axis of the first intermediate shaft 80 to engage and disengage with the lock ring 91. Therefore, the first clutch 88 can be engaged and disengaged in a state facing the lock ring 91, and twisting or tilting is less likely to occur in the lock ring 91 when the rotation restriction is switched. The lock ring 91 is provided so as to be movable in the axial direction of the first intermediate shaft 80, and is biased by a coil spring 93 (elastic member) to a position where the first clutch 88 can be engaged. Therefore, even if the first clutch 88 collides without being able to engage with the lock ring 91, the lock ring 91 can move in the axial direction to release the impact, and when the lock ring 91 is able to engage with the first clutch 88, it returns to its original position to ensure reliable engagement. In particular, the coil spring 93 is disposed on the same axis as the lock ring 91, so that the movement of the lock ring 91 is smooth.

[0043] The lock ring 91 has a rotation-preventing piece 92 (rotation-preventing portion) that engages with the groove 47a of the lower through-hole 47 of the front housing 41, and the rotation-preventing piece 92 also serves as an engaged portion of the first clutch 88. Therefore, the shape of the lock ring 91 is not complicated, resulting in a rational configuration. The lower through-hole 47 (holding portion for the lock ring 91) of the front housing 41 has an inner peripheral surface 47b (circumferential surface) that comes into sliding contact with the outer surface of the lock ring 91 around the axis of the first intermediate shaft 80. This allows the lock ring 91 to be held evenly and increases durability. In addition, the axial movement of the lock ring 91 is also smoothly guided. The engaged portion of the first clutch 88 in the lock ring 91 and the front engagement portion 90 (engagement portion) of the first clutch 88 with the lock ring 91 are formed by different numbers of pawls 90a and pawls 92a. This makes it easier for the first clutch 88 to engage with the lock ring 91. The drive mechanism 30 has first and second intermediate shafts 80, 81 parallel to the tool holder 23. The first intermediate shaft 80 is a rotation transmission shaft, and the second intermediate shaft 81 is for striking the bit B. Therefore, the lock ring 91 can be easily disposed on the axis of the first intermediate shaft 80.

[0044] In addition, the invention relating to the lock ring of the tool holder can be modified as follows. The number of claws on the lock ring can be increased or decreased. The shape of the claws can also be changed. The claws do not have to function as anti-rotation parts for the lock ring. The rotation transmission member that is engaged with and disengaged from the lock ring is not limited to a clutch. For example, the rotation transmission member may be a gear that is provided on a rotating shaft and meshes with the tool holder, and the gear may be slid to engage and disengage with the lock ring. The lock ring does not have to be slidable in the axial direction. The locking member is not limited to the ring-like shape described above, and may be modified in shape, for example, into a cross shape in which two plates intersect. In the hammer drill, the selectable operation modes are not limited to four. As long as at least the hammer mode and the hammer drill mode can be selected, the present invention is applicable. The structure of the mode switching mechanism and the switching knob can also be modified as appropriate.

[0045] Modifications common to each invention will be described below. The orientation of the motor is not limited to the front-rear direction and can be changed as appropriate. The motor is not limited to a brushed motor, but a brushless motor can also be used. The power source may be a battery pack rather than a commercial power source. The impact action may be achieved not by a piston cylinder but by a structure in which a piston reciprocates within a fixed cylinder, or by a structure in which a striker directly impacts the bit without an impact bolt. [Explanation of symbols]

[0046] 1 hammer drill, 2 housing, 3 outer housing, 4 motor housing, 5 handle housing, 6 connection portion, 7 motor housing portion, 8 screw, 9 motor, 10 output shaft, 21 front cylinder portion, 22 rear cylinder portion, 23 tool holder, 30 drive mechanism, 31 rotation / impact operating portion, 32 rotation / impact switching portion, 33 piston cylinder, 34 striker, 40 inner housing, 41 front housing, 42 rear housing, 42a retaining recess, 42b peripheral wall portion, 43 bearing retaining portion, 44 body portion, 45 upper through hole, 46 bearing metal, 47 lower through hole, 47a groove, 47b inner peripheral surface, 49 O-ring, 50 inner rib, 52 ·Outer rib, 54·Partition wall, 55·Front grease chamber, 56·Rear grease chamber, 58·Front exhaust port, 59·Front flange, 60, 69·Notch, 68·Rear flange, 70·Screw fastening portion, 71·Screw boss, 72·Female thread portion, 73·Circular recess, 76·Relief hole, 77·Air relief path, 80·First intermediate shaft, 80a·Through hole, 80b·Shaft center hole, 81...second intermediate shaft, 84...first gear, 86...second gear, 88...first clutch, 90...front engagement portion, 90a...claw, 91...lock ring, 92...anti-rotation piece, 92a...claw, 97...third gear, 98...boss sleeve, 104...second clutch, 109...mode switching mechanism, 116...switching knob, T...drive mechanism accommodating area, B...bit.

Claims

1. In the housing, A motor; A cylindrical tool holder on the front end of which a bit can be attached; A drive mechanism capable of striking the bit; a rotating shaft for striking the bit and / or transmitting rotation to the tool holder, the rotating shaft being provided in the drive mechanism and rotated by rotation of the output shaft of the motor; a drive mechanism accommodating region that hermetically accommodates the drive mechanism within the housing, an air escape passage is formed inside the rotating shaft to allow air within the drive mechanism accommodating area to escape to the outside of the drive mechanism accommodating area, and an inlet of the air escape passage is formed by a through hole that penetrates the rotating shaft perpendicularly on the outer circumferential surface of the rotating shaft.

2. Within the housing, A motor; A cylindrical tool holder on the front end of which a bit can be attached; A drive mechanism capable of striking the bit; a rotating shaft for striking the bit and / or transmitting rotation to the tool holder, the rotating shaft being provided in the drive mechanism and rotated by rotation of the output shaft of the motor; a drive mechanism accommodating region that hermetically accommodates the drive mechanism within the housing, an impact tool characterized in that the rotating shaft is formed with a spline portion to which a clutch for switching operating modes is slidably connected, an air escape passage is formed inside the rotating shaft to allow air within the drive mechanism accommodating area to escape to the outside of the drive mechanism accommodating area, and an inlet of the air escape passage is located in the spline portion.

3. The impact tool according to claim 1 or 2, characterized in that a bearing supporting the rotating shaft is provided within the drive mechanism accommodating area, and an outlet of the air escape passage is formed on the opposite side of the drive mechanism accommodating area to the bearing in the axial direction of the rotating shaft.

4. 4. The impact tool according to claim 3, wherein the bearing is a sealed bearing.

5. 5. The impact tool according to claim 1, wherein the inlet is disposed at a middle portion in an axial direction of the rotating shaft.

6. The impact tool according to claim 3 or 4, characterized in that the drive mechanism accommodating area is formed by an inner housing having a retaining recess provided within the housing to hold the bearing, and a ring-shaped peripheral wall portion protruding toward the drive mechanism accommodating area is formed around the retaining recess.

7. The impact tool according to claim 6, wherein the rotating shaft is provided with a gear adjacent to the peripheral wall portion in the axial direction.

8. 8. The impact tool according to claim 1, wherein the drive mechanism has a rotation operating unit that rotates the tool holder, and also has a rotation shaft for transmitting rotation to the tool holder and a rotation shaft for striking the bit, and the rotation shaft in which the inlet is formed is the rotation shaft for transmitting rotation.

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