Hammer drill

Abstract

To provide a hammer drill that is configured so that operation modes can be selected in accordance with front and rear positions of a tool holder, which enables a retreat restriction position for the tool holder to be stabilized even when push-in force to the tool holder increases so as to improve reliability in an only-rotation mode.SOLUTION: A hammer drill 1 is brought into a hammer drill mode in which rotation of a tool holder 35 and striking operation by a striking part 50 can be performed simultaneously accompanying retreating of the tool holder 35 to a retreat position in a first switch state of a restriction plate 71, and is brought into a drill mode or a clutch mode in which the tool holder 35 is restricted from retreating from an advancing position and only rotation of the tool holder 35 can be performed in a second switch state of the restriction plate 71. The restriction plate 71 is arranged closer to a rear side than a change plate 43 in a striking axis line L direction, in which two restriction parts 76 and 76, which contact the change plate 43 to restrict the change plate 43 from retreating, are arranged so as to be positioned respectively at left and right regions opposing to each other with the striking axis line L as a center.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present disclosure relates to a hammer drill in which an operating mode can be selected depending on the forward / backward position of a tool holder that holds a tool bit. [Background technology]

[0002] Known hammer drills include a tool holder, which holds a tool bit at its front end, that is movable back and forth along the impact axis, allowing the operating mode to be selected depending on the forward or backward position of the tool holder. For example, a hammer drill disclosed in Japanese Patent No. 6735118 (Patent Document 1) has a tool holder that houses a striking part that is movable back and forth and biased to a forward position. This hammer drill also has an intermediate shaft that transmits rotation from a motor and is disposed parallel to the tool holder. The intermediate shaft is provided with a gear that transmits rotation to the tool holder and a rotation conversion part (a boss sleeve and a clutch) that converts the rotation of the intermediate shaft into operation of the striking part. This hammer drill allows the drill mode to be selected by operating a mode selector lever to restrict the retraction of the tool holder to a position where the clutch does not engage with the boss sleeve. The hammer drill mode can also be selected by operating the mode selector lever to allow the retraction of the tool holder to a position where the clutch engages with the boss sleeve. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 6735118 Summary of the Invention [Problem to be solved by the invention]

[0004] In this hammer drill, the tool holder's retraction is restricted in drill mode by an eccentric pin on the mode selector lever that engages orthogonally from the side with a plate attached to the tool holder. However, the eccentric pin has a cantilevered support structure that protrudes from the mode selector lever, which fits into the side of the housing. Therefore, if the backward pushing force transmitted from the tool bit to the tool holder increases in drill mode, the eccentric pin may become deformed or tilted. In this case, the tool holder's retraction restriction position becomes unstable, and the clutch, which retracts along with the tool holder, may engage with the boss sleeve, causing an unexpected impact.

[0005] Therefore, an object of the present disclosure is to provide a hammer drill that allows the operating mode to be selected depending on the forward or backward position of the tool holder, and that can stabilize the retraction restriction position of the tool holder and improve reliability in the rotation-only mode even if the pressing force on the tool holder increases. [Means for solving the problem]

[0006] In order to achieve the above object, the present disclosure provides a hammer drill, comprising: a motor; a cylindrical tool holder capable of holding a tool bit at its front end, accommodating an impact part of the tool bit inside, and being rotatable and movable back and forth coaxially with the impact axis of the impact part, and being biased to protrude forward; an intermediate shaft that is provided parallel to the tool holder and to which rotation of the motor is transmitted and that transmits the rotation to the tool holder; a rotation conversion unit provided on the intermediate shaft and configured to convert rotation of the intermediate shaft into a striking motion of the striking unit; a mode switching member that moves back and forth integrally with the tool holder, and that deactivates the rotation conversion unit when the tool holder is in an advanced position and activates the rotation conversion unit when the tool holder is in a retracted position; a restricting member capable of restricting the retraction of the mode switching member at the forward position of the tool holder; The control member includes an operating member that can switch the restriction member between a first switching state in which the mode switching member is not restricted from moving backward and a second switching state in which the mode switching member is restricted from moving backward. When the regulating member is in a first switching state by the operating member, the hammer drill enters a first operating mode in which the tool holder is retracted to the retracted position, allowing simultaneous rotation of the tool holder and impact operation of the impact section, and when the regulating member is in a second switching state by the operating member, the tool holder is restricted from retracting from the forward position, and enters a second operating mode in which the tool holder is only able to rotate. The regulating member is positioned rearward of the mode switching member in the direction of the impact axis, and the regulating member is provided with a plurality of regulating portions that abut against the mode switching member to regulate the retreat of the mode switching member, with at least one regulating portion located in each of two regions facing each other around the impact axis. [Effects of the Invention]

[0007] According to the present disclosure, in the second operation mode, the mode switching member is received in a well-balanced manner by the plurality of restriction portions provided on the restriction member, thereby restricting retraction of the tool holder. Therefore, even if the pressing force on the tool holder increases, the retraction restriction position of the tool holder can be stabilized, thereby improving reliability in the second operation mode. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 2 is a rear perspective view of the hammer drill (hammer drill mode). [Figure 2] FIG. 2 is a central longitudinal cross-sectional view of the hammer drill (hammer drill mode). [Figure 3] FIG. 3 is an enlarged view of the rotating / impacting mechanism portion in FIG. 2. [Figure 4] FIG. 4 is a cross-sectional view taken along line AA in FIG. [Figure 5] FIG. 2 is an exploded perspective view of the mode switching unit as seen from the front. [Figure 6] FIG. 2 is an exploded perspective view of the mode switching unit from the rear. [Figure 7] FIG. 4 is a cross-sectional view taken along line BB in FIG. 3. [Figure 8] FIG. 10 is a rear view of the operating lever portion with the main body housing omitted (hammer drill mode). [Figure 9] FIG. 10 is a rear view of the operating lever portion with the main body housing omitted (rotation only mode). [Figure 10] FIG. 4 is an explanatory view showing a state in which the tool holder in FIG. 3 is retracted. [Figure 11] FIG. 11 is a cross-sectional view taken along line CC in FIG. [Figure 12] FIG. 4 is an enlarged view of the rotation / impact mechanism portion in FIG. 3 in the rotation-only mode. [Figure 13] FIG. 13 is a cross-sectional view taken along the line DD in FIG. 12. DETAILED DESCRIPTION OF THE INVENTION

[0009] In one embodiment of the present disclosure, two restricting portions may be provided on the left and right of the striking axis. According to this configuration, the retraction restriction position of the tool holder can be stabilized with a minimum number of restriction portions. In one embodiment of the present disclosure, the regulating member may be movable back and forth in the direction of the impact axis, and in the first switching state, may retreat in accordance with the retreat of the mode switching member, and in the second switching state, may move forward to regulate the retreat of the mode switching member. According to this configuration, even if the restricting member is provided behind the tool holder, it does not interfere with use in the first operation mode. In one embodiment of the present disclosure, a cam mechanism may be provided that allows the regulating member to move backward in the first switching state and moves the regulating member forward in the second switching state. According to this configuration, the restriction member can be easily switched between forward and backward movement in a space-saving manner.

[0010] In one embodiment of the present disclosure, the cam mechanism may be provided with a biasing member that biases the tool holder forward. According to this configuration, the tool holder can be protruded to the forward position by utilizing the biasing member provided in the cam mechanism. In one embodiment of the present disclosure, the cam mechanism may include a front cam that is arranged behind the regulating member and is movable back and forth, and a rear cam that is arranged behind the front cam and changes its position between a first position that allows the front cam to retract in response to operation of the operating member and a second position that regulates the retraction of the front cam forward. The biasing member may be a conical spring that is provided between the front cam and the rear cam and biases the restricting member and the mode switching member forward together with the front cam. According to this configuration, the conical spring, which is resistant to buckling, can apply a biasing force in the direction of the striking axis without loss.

[0011] In one embodiment of the present disclosure, the restricting member, the cam mechanism, and the operating member may be disposed on the striking axis. According to this configuration, the tool holder and the mode switching member can be smoothly moved back and forth on the impact axis to switch modes. In one embodiment of the present disclosure, the restricting member may be provided with a strike preventing member that prevents the rotation converting portion from operating in the second operating mode. According to this configuration, it is possible to effectively prevent an unexpected striking action in the second operation mode. In one embodiment of the present disclosure, the striking portion may include a piston cylinder that is housed in the tool holder from the rear so as to be movable back and forth, and a striking member that is housed in the piston cylinder and moves in conjunction with the back and forth movement of the piston cylinder. The rotation conversion unit may include a conversion member that is mounted on the intermediate shaft and to which the mode switching member is engaged and disengaged, and a rod that is connected to the rear end of the piston cylinder and swings back and forth as the conversion member rotates. The impact prevention member may be a member that restricts the swinging of the rod by contacting the rear end of the piston cylinder that retracts together with the rod. According to this configuration, by restricting the swinging of the rod of the rotation conversion part, it is possible to easily prevent an unexpected striking action in the second operation mode. In one embodiment of the present disclosure, the impact prevention member may be integrally formed with the restriction member. According to this configuration, the impact prevention member can be reliably positioned behind the piston cylinder by utilizing the restricting member. [Example]

[0012] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. Fig. 1 is a rear perspective view showing an example of a hammer drill. Fig. 2 is a central longitudinal cross-sectional view of the hammer drill. Fig. 3 is an enlarged view of the rotation / impact mechanism portion in Fig. 2. Fig. 4 is a cross-sectional view taken along line AA in Fig. 3. All of these are in hammer drill mode. The hammer drill 1 has housings that form the outer shell, which are a main housing 2 and a front housing 3. The main housing 2 is formed by screwing together left and right half housings 2a and 2b. The front housing 3 is connected to the upper front part of the main housing 2. The main body housing 2 houses a motor housing 4 in its lower front section. The main body housing 2 houses an inner housing 5 spanning its upper front section and the front housing 3. A motor 6 is held within the motor housing 4 with its rotating shaft 7 facing upward. The inner housing 5 is fastened to the motor housing 4 with screws. The front housing 3 has a rear tubular portion 8 and a front tubular portion 9. The rear tubular portion 8 is screwed to the inner housing 5. The rear tubular portion 8 expands toward the rear and is joined to the upper front portion of the main housing 2 while being screwed to the inner housing 5. The front tubular portion 9 is integrally formed on the front side of the rear tubular portion 8. A side handle (not shown) can be attached to the base of the front tubular portion 9. A rotation / impact mechanism portion 10 is housed within the inner housing 5 and the front housing 3.

[0013] A grip portion 11 is formed in the vertical direction at the rear of the main body housing 2. The grip portion 11 is loop-shaped and connected to the main body housing 2 at its upper and lower ends. A switch 12 is housed in the upper part of the grip portion 11. The switch 12 is equipped with a trigger 13 that protrudes forward. A forward / reverse switch button 14 for switching the rotation of the motor 6 is provided above the trigger 13. A battery pack 15, which serves as a power source, is detachably attached to the lower rear part of the main body housing 2 below the grip portion 11. A controller 16 is housed between the motor 6 and the battery pack 15. The controller 16 is equipped with a control circuit board 17. Well-known elements such as a CPU, RAM, and ROM are mounted on the control circuit board 17, and a motor control circuit and a power supply circuit are formed on the board. An operation panel 18 is provided on the front inner peripheral surface of the loop-shaped portion above the controller 16. Three buttons 19A to 19C are provided on the operation panel 18. The upper button 19A corresponds to the hammer drill mode, the lower left button 19B corresponds to the drill mode, and the lower right button 19C corresponds to the clutch mode.

[0014] As shown in Figures 5 and 6, the inner housing 5 has an elliptical shape in a front view that is open at the front and extends in the vertical direction. The inner housing 5 has an upper plate portion 20, a middle tubular portion 21, and a lower tubular portion 22. The upper plate portion 20 is a rectangular dish-like portion in a plan view that extends in the front-to-rear direction at the top of the inner housing 5. Support pins 23, 23 that protrude outward to the left and right are formed on the left and right rear sides of the upper plate portion 20. A rubber ring 24 is attached to each support pin 23. As shown in Figure 7, each rubber ring 24 is held by a boss 25 that protrudes toward the center from the inner surface of the left and right half housings 2a, 2b. Therefore, the upper part of the inner housing 5 is elastically held to the main housing 2 via the rubber rings 24, 24. The middle cylinder portion 21 extends in the front-rear direction below the upper plate portion 20. As shown in Figure 4, protruding portions 26, 26 are formed on the left and right sides of the middle cylinder portion 21, protruding outward to the left and right and extending forward. A guide recess 27 is formed within each protruding portion 26, with its front end opening. The rear portion of the middle cylinder portion 21 forms a small-diameter portion 28 whose outer diameter is smaller than that of the front portion.

[0015] An inner support 30 is screwed to the front side of the middle cylindrical portion 21 from the front. The inner support 30 is a short cylinder having a central hole 31 that is coaxial with the middle cylindrical portion 21. The central hole 31 has a two-stage diameter, with the front portion having a larger diameter than the rear portion. A metal bearing 32 is press-fitted and held in the front portion of the central hole 31. Guide grooves 33, 33 that penetrate in the front-rear direction outside the metal bearing 32 are formed on the left and right inner surfaces of the central hole 31. The guide grooves 33, 33 are continuous with guide recesses 27, 27 provided in the middle cylindrical portion 21. The lower cylindrical portion 22 is a bottomed cylindrical portion that opens forward below the middle cylindrical portion 21. The upper end of the rotating shaft 7 of the motor 6 passes through the upper part of the motor housing 4 and the lower part of the inner housing 5. A first gear 34 is provided at the upper end of the rotating shaft 7, protruding into the inner housing 5 below the lower cylindrical portion 22.

[0016] The rotating / impacting mechanism 10 includes a tool holder 35 and an intermediate shaft 36 . The tool holder 35 is held by a metal bearing 32 of the inner support 30 and a bearing 37 held in the front cylindrical portion 9 of the front housing 3. The tool holder 35 is rotatable and movable back and forth with its axis, which is the striking axis L, oriented in the front-to-rear direction. The front end of the tool holder 35 protrudes forward from the front cylindrical portion 9. An operating sleeve 38 for attaching and detaching a bit B is provided at the front end of the tool holder 35. The bit B is an example of an end tool of the present disclosure. A fourth gear 40 is mounted on the outer periphery of the rear portion of the tool holder 35 so as to be rotatable integrally with the tool holder 35. A stopper ring 41 is fixed between the fourth gear 40 and the bearing 37 on the outer periphery of the tool holder 35. The forward movement of the tool holder 35 is restricted at the position shown in FIGS. 2 to 4 where the stopper ring 41 abuts against the inner ring of the bearing 37. A washer 42 and a change plate 43 are mounted on the outer periphery of the tool holder 35 between the fourth gear 40 and the metal bearing 32. As shown in FIGS. 5 and 6 , the change plate 43 is a ring-shaped plate with outward-facing receiving portions 44, 44 formed on both the left and right sides. A semicircular locking portion 45 that widens downward is formed on the lower part of the change plate 43. The backward movement of the tool holder 35 is restricted at the position where the change plate 43 abuts against the metal bearing 32. The change plate 43 is an example of a mode switching member of the present disclosure.

[0017] A striking unit 50 is provided inside the tool holder 35. The striking unit 50 includes a piston cylinder 51, a striker 52, and an impact bolt 53. The piston cylinder 51 is cylindrical and open at the front, and is housed at the rear side of the tool holder 35 so as to be movable back and forth on the striking axis L. The striker 52 is housed within the piston cylinder 51 via an air chamber 54 so as to be movable back and forth on the striking axis L. The striker 52 is an example of a striking member of the present disclosure. The impact bolt 53 is accommodated in front of the striker 52 so as to be movable back and forth on the impact axis L. The impact bolt 53 is capable of abutting against the rear end of the bit B inserted into the front end of the tool holder 35.

[0018] The intermediate shaft 36 is disposed below the tool holder 35 and parallel to the striking axis L. The front end of the intermediate shaft 36 is supported by a front bearing 55 provided in the rear cylindrical portion 8 of the front housing 3. The rear end of the intermediate shaft 36 is supported by a rear bearing 56 provided in the lower cylindrical portion 22 of the inner housing 5. A second gear 57 is fixed to the rear portion of the intermediate shaft 36, forward of the rear bearing 56. The second gear 57 is engaged with the first gear 34 provided on the rotating shaft 7. Therefore, the intermediate shaft 36 rotates at a reduced speed via the first gear 34 and the second gear 57, due to the rotation of the rotating shaft 7 caused by the drive of the motor 6. A rotation conversion portion 58 is provided on the intermediate shaft 36 in front of the second gear 57. The rotation conversion portion 58 includes a boss sleeve 59, a swash bearing 60, a rod 61, and a clutch gear 62. The boss sleeve 59 is rotatably mounted on the intermediate shaft 36 between a stopper 63 provided in the middle portion of the intermediate shaft 36 and the second gear 57. A boss-side engagement portion 64 is provided on the front surface of the boss sleeve 59. The boss sleeve 59 is an example of a conversion member of the present disclosure. The swash bearing 60 is provided on the outer periphery of the boss sleeve 59 and is tilted relative to the axis of the boss sleeve 59. The rod 61 protrudes radially upward from the outer ring of the swash bearing 60. The tip of the rod 61 is connected to the rear end of the piston cylinder 51 via a connecting pin 65.

[0019] The clutch gear 62 is mounted on a spline portion 66 formed on the intermediate shaft 36 in front of the stopper 63. The clutch gear 62 is coupled to the intermediate shaft 36 so as to be rotatable integrally with the intermediate shaft 36 and slidable in the axial direction. A gear-side engaging portion 67 protrudes rearward from the rear surface of the clutch gear 62. The gear-side engaging portion 67 engages with the boss-side engaging portion 64 of the boss sleeve 59 in the rotational direction when the clutch gear 62 is in the retracted position. A third gear 68 is formed on the front portion of the clutch gear 62. The third gear 68 meshes with the fourth gear 40 provided on the tool holder 35. A locking groove 69 is formed in the circumferential direction in the middle portion of the third gear 68. The locking portion 45 of the change plate 43 locks into the locking groove 69 from above. Therefore, the clutch gear 62 moves forward and backward following the forward and backward movement of the change plate 43. When the change plate 43 is in the forward position, the clutch gear 62 moves to a front position where the gear-side engaging portion 67 is separated from the boss-side engaging portion 64. When the change plate 43 is in the backward position, the clutch gear 62 moves to a rear position where the gear-side engaging portion 67 engages with the boss-side engaging portion 64.

[0020] A mode switching unit 70 is provided in the center cylindrical portion 21 of the inner housing 5 behind the tool holder 35. The mode switching unit 70 includes a regulating plate 71, a cam mechanism 72, an operating lever 73, and a mode detection switch 74. The regulating plate 71 has a base end portion 75 and a pair of regulating portions 76, 76. The base end portion 75 is a circular plate when viewed from the front, and has a through hole 77 formed in the center thereof, which is concentric with the striking axis L. The regulating plate 71 is an example of a regulating member of the present disclosure. A rubber plate 78 is provided coaxially on the front surface of the base end portion 75. The rubber plate 78 is integrally molded with the base end portion 75 of the iron regulating plate 71. The rubber plate 78 is a ring plate with a slightly smaller diameter than the base end portion 75, and its center hole has a larger diameter than the through hole 77 of the base end portion 75. A pair of stoppers 79, 79 that protrude forward are provided on the left and right sides of the front surface of the rubber plate 78. The rubber plate 78 is an example of an impact prevention member of the present disclosure.

[0021] The restricting portions 76, 76 are strip-shaped plates that extend outward from the left and right sides of the base end portion 75 and then project forward in parallel. The restricting portions 76, 76 are arranged symmetrically so that one is located in each of the left and right regions that face each other about the impact axis L. The restricting portions 76, 76 are an example of a restricting portion of the present disclosure that is provided so that at least one is located in each of two regions that face each other about the impact axis L. The restricting portions 76, 76 fit into the left and right guide recesses 27, 27 of the middle cylinder portion 21 and extend forward. Front portions of the restricting portions 76, 76 pass through the left and right guide grooves 33, 33 of the inner support 30, respectively. Therefore, the restricting plate 71 is held movable back and forth in the direction of the impact axis L while its rotation is restricted within the middle cylinder portion 21 and the inner support 30. The receiving portions 44, 44 of the change plate 43 are located in front of the restricting portions 76, 76 that pass through the guide grooves 33, 33 of the inner support 30.

[0022] The cam mechanism 72 includes a front cam 80, a rear cam 81, and a conical spring 82, each of which is concentric with the impact axis L. The front cam 80 is disk-shaped and has approximately the same diameter as the base end 75 of the regulating plate 71, with a through-hole 83 formed in its center. Four front cam claws 84, 84... are provided on the rear surface of the front cam 80, projecting rearward on the top, bottom, left, and right. A pair of engagement pieces 85, 85 that protrude outward to the left and right are formed on the left and right sides of the front cam 80. The engagement pieces 85, 85 engage with the left and right guide recesses 27, 27 of the middle cylindrical portion 21. Therefore, the front cam 80 is held by the guide recesses 27, 27 so as to be able to move back and forth in the direction of the impact axis L while its rotation is restricted within the middle cylindrical portion 21.

[0023] The rear cam 81 is rotatably housed within the middle cylinder portion 21 behind the front cam 80. The rear cam 81 is disk-shaped and has the same diameter as the front cam 80, and a front shaft portion 86 that protrudes forward is formed in its center. The front shaft portion 86 passes through the through-hole 83 of the front cam 80 and the through-hole 77 of the base end portion 75 of the regulating plate 71. Four rear cam claws 87, 87... are circumferentially equally spaced and protrude forward from the front surface of the rear cam 81 around the front shaft portion 86. A receiving washer 88 that abuts against the front surface of the front shaft portion 86 is provided on the front surface of the base end portion 75 through which the front shaft portion 86 passes within the center hole of the rubber plate 78. The receiving washer 88 has a larger diameter than the front shaft portion 86 and is fixed perpendicular to the front shaft portion 86 by a flat head screw 89 that passes through the receiving washer 88 from the front and is screwed into the front shaft portion 86. The receiving washer 88 prevents the base end portion 75 and the front cam 80 from coming off forward from the front shaft portion 86.

[0024] A rear shaft portion 90, which is inserted into the small diameter portion 28 of the central cylindrical portion 21, is formed coaxially on the rear surface of the rear cam 81. An O-ring 91 is fitted to the rear shaft portion 90 to seal the gap between it and the small diameter portion 28. A fitting groove 92 extending in the diameter direction is formed on the rear surface of the rear shaft portion 90. In rear view, the fitting groove 92 is located between the rear cam claws 87, 87 that are adjacent in the circumferential direction. A threaded hole 93 extending forward is formed within the fitting groove 92. With the fitting groove 92 oriented in the up-down direction, the threaded hole 93 is located at a position slightly eccentric to the downward direction of the impact axis L as shown in FIG. 7. Two locking recesses 94A, 94B are formed radially on the rear surface of the rear cam 81, radially outward of the rear shaft portion 90. One of the locking recesses 94A is formed in the same phase as the diameter of the fitting groove 92 in rear view. The other locking recess 94B is located to the circumferential left of the locking recess 94A in rear view. The locking recess 94B is located rearward of the rear cam claw 87.

[0025] The conical spring 82 is mounted on the front shaft portion 86 between the front cam 80 and the rear cam 81. The conical spring 82 is a tapered coil spring whose diameter decreases as it extends forward. The conical spring 82 is located inside each of the front cam claws 84 of the front cam 80 and each of the rear cam claws 87 of the rear cam 81, and urges the front cam 80 forward. Therefore, the regulating plate 71, which the front cam 80 abuts, is also urged forward together with the front cam 80. The advanced regulating plate 71 abuts the front ends of the left and right regulating portions 76, 76 against the receiving portions 44, 44 of the change plate 43. Therefore, the tool holder 35 is urged to the advanced position shown in FIGS. 3 and 4 , where the stopper ring 41 abuts against the bearing 37. At this time, the front cam 80 is pressed against the base end 75 by the biasing force of the conical spring 82 at a position where the rear ends of the front cam claws 84 are slightly forward of the front ends of the rear cam claws 87 of the rear cam 81. The conical spring 82 is an example of a biasing member of the present disclosure.

[0026] The operating lever 73 includes a disk portion 100 and a lever portion 101. The disk portion 100 has an outer diameter larger than the outer diameter of the small diameter portion 28 of the middle cylinder portion 21. A front portion 102 of the disk portion 100 has the same diameter as the rear shaft portion 90 of the rear cam 81 and is fitted into the small diameter portion 28 from the rear. Two protrusions 103, 103 are formed in the diameter direction on the front surface of the front portion 102. The protrusions 103, 103 are fitted into fitting grooves 92 of the rear cam 81. The disk portion 100 is connected to the rear cam 81 by threading a screw 104 that passes through the center from the front into a screw hole 93 of the rear cam 81. A notch 105 is formed on the outer periphery of the disk portion 100, diametrically above where the protrusions 103, 103 extend in rear view. At the left end of the notch 105, a pressing portion 106 having a curved peripheral surface is formed. Lever portion 101 protrudes radially outward from disc portion 100. The protruding direction of lever portion 101 is the radially downward direction from which protrusions 103, 103 extend on the opposite side from notch 105. A notch 107 that allows protrusion of lever portion 101 is formed on the lower left side of small diameter portion 28. Operating lever 73 is an example of an operating member of the present disclosure.

[0027] 8 shows a first operating position of the operating lever 73 in which the lever portion 101 protrudes directly downward as viewed from behind. In this first operating position, the rear cam 81 is in a first rotational position in which the rear cam claws 87 are alternately shifted in the circumferential direction relative to the front cam claws 84 of the front cam 80. This first rotational position is an example of a first attitude of the rear cam in the present disclosure. Therefore, the front cam 80 and the regulating plate 71 are in the first switching state in which they are allowed to move rearward. Therefore, the tool holder 35, together with the change plate 43, is also allowed to move backward. 9 shows the second operating position of the operating lever 73 in which the lever portion 101 protrudes to the lower left when viewed from behind. In this second operating position, the rear cam 81 is in a second rotational position in which the rear cam claws 87 are positioned vertically and horizontally. This second rotational position is an example of the second posture of the rear cam disclosed herein. Therefore, the rear cam claws 87 are in phase with the front cam claws 84 of the front cam 80 and are positioned immediately behind the front cam claws 84. As a result, the front cam 80 and the regulating plate 71 enter a second switching state in which rearward movement is restricted. Accordingly, the receiving portions 44, 44 of the change plate 43 come into contact with the regulating portions 76, 76 of the regulating plate 71, and therefore the tool holder 35 is also restricted from moving backward.

[0028] As shown in FIG. 3, a bottomed hole 110 that opens forward is formed on the upper side of the small diameter portion 28. A coil spring 111 and a ball 112 that is urged forward by the coil spring 111 are housed inside the bottomed hole 110. When the rear cam 81 is in the first rotation position, the ball 112 is engaged with the locking recess 94A located in the front. When the rear cam 81 is in the second rotation position, the ball 112 is engaged with the locking recess 94B located in the front. Therefore, a click action occurs when the operating lever 73 is switched between the first and second operating positions. A cover portion 113 is provided above the operation panel 18 on the front inner peripheral surface of the loop-shaped portion of the main housing 2. The cover portion 113 covers almost the entire disk portion 100 of the operation lever 73, and allows the lower portion of the disk portion 100 and the lever portion 101 to protrude from an opening 114 provided at the bottom.

[0029] The mode detection switch 74 is screwed to the rear surface of the top plate 20 of the inner housing 5, above the disk portion 100 of the operating lever 73. The mode detection switch 74 is a microswitch that turns ON when a protruding plunger 115 is pressed by a lever plate 116. The mode detection switch 74 is attached to the rear surface of the top plate 20 with the lever plate 116 facing downward and the plunger 115 to the right. In this state, the lever plate 116 is positioned above the disk portion 100. In the first operating position of the operating lever 73 shown in Fig. 8, the notch 105 faces upward, and the lever plate 116 is positioned within the notch 105. Therefore, the lever plate 116 and plunger 115 are not pushed in, and the mode detection switch 74 is not turned on. On the other hand, in the second operating position of the operating lever 73 shown in Fig. 9, the pressing part 106, which has rotated to the right in rear view, comes into contact with the lever plate 116 and pushes it upward. Therefore, the plunger 115 is pushed into the lever plate 116, and the mode detection switch 74 is turned on.

[0030] In the hammer drill 1 configured as described above, the lever portion 101 of the operating lever 73 is grasped and operated to the first operating position shown in Fig. 8. This causes the rear cam 81 to move to the first rotation position, and the hammer drill mode is entered, in which a rotation / impact action is obtained as the tool holder 35 moves backward. The hammer drill mode is an example of the first operating mode of the present disclosure. First, when the operator presses the bit B attached to the front end of the tool holder 35 against the workpiece, a pushing force is applied to the tool holder 35. In the first operating position, as described above, the front cam 80 and the regulating plate 71 are in the first switching state and are allowed to move rearward. Therefore, as shown in FIGS. 10 and 11 , the tool holder 35, together with the regulating plate 71 and the front cam 80, moves back to the retracted position via the change plate 43 against the bias of the conical spring 82. Then, the change plate 43, which moves back together with the tool holder 35, retracts the clutch gear 62. When the tool holder 35 is in the retracted position, the clutch gear 62 engages the gear-side engaging portion 67 with the boss-side engaging portion 64 of the boss sleeve 59 while maintaining the meshing state between the third gear 68 and the fourth gear 40.

[0031] In this state, when the trigger 13 is pressed to turn on the switch 12, the controller 16 illuminates the hammer drill mode button 19A and drives the motor 6. This rotates the rotary shaft 7, causing the first gear 34 to rotate with the rotary shaft 7 and the intermediate shaft 36 to rotate at a reduced speed via the second gear 57. Therefore, the boss sleeve 59 of the rotation conversion unit 58, which is engaged with the clutch gear 62 and activated, rotates with the intermediate shaft 36. When the boss sleeve 59 rotates, the rod 61 swings back and forth via the swash bearing 60, causing the piston cylinder 51 of the striking unit 50 to move back and forth along the striking axis L. This causes the striker 52 to reciprocate along the striking axis L via the air chamber 54, indirectly striking the bit B via the impact bolt 53. At the same time, the rotation of the third gear 68 of the clutch gear 62 is transmitted to the tool holder 35 via the fourth gear 40. This causes the tool holder 35 to rotate, thereby rotating the bit B.

[0032] Next, the lever portion 101 of the operating lever 73 is grasped and operated to the second operating position shown in FIG. 9. This places the rear cam 81 in a second rotation position, as shown in FIGS. 12 and 13. The regulating plate 71 is also in a second switching state, in which its retraction is restricted by the front cam 80 abutting against the rear cam 81. Therefore, the rearward movement of the tool holder 35 is restricted by the abutment of the change plate 43 against the restricting portions 76, 76. Therefore, even if the bit B attached to the front end of the tool holder 35 is pressed against the workpiece, the tool holder 35 does not retract, and neither does the clutch gear 62. Therefore, the rotation conversion unit 58 is inactive. When the motor 6 is driven to rotate the intermediate shaft 36, the rotation from the clutch gear 62 is transmitted to the tool holder 35, resulting in a rotation-only mode. In this rotation-only mode, the pressing portion 106 of the disk portion 100 of the operating lever 73 presses the lever plate 116 of the mode detection switch 74 to turn on the mode detection switch 74. Then, the controller 16 lights up the drill mode button 19B and the clutch mode button 19C on the operation panel 18.

[0033] Here, the operator selects the drill mode and presses button 19B. This causes the controller 16 to switch to the drill mode, which drives the motor 6 so that the rotary shaft 7 rotates at a predetermined speed. This allows the bit B attached to the tool holder 35 to rotate, enabling drilling. Meanwhile, the operator selects the clutch mode and presses button 19C. The controller 16 then drives the motor 6 so that the rotary shaft 7 rotates at a slower speed than in drill mode, transitioning to clutch mode. Clutch mode is an electronic clutch that stops the motor 6 when the current to the motor 6 reaches a preset value, i.e., a torque setting. Therefore, if a bit B with a driver bit attached to the tip is attached to the tool holder 35 and a screw is tightened, the tightening of the screw will finish at the torque setting, which increases as the screw tightening progresses. Furthermore, by operating the forward / reverse switch button 14 to reverse the rotation of the tool holder 35, a tightened screw can also be loosened. The drill mode and clutch mode, which are rotation-only modes, are examples of the second operating mode of the present disclosure.

[0034] In both the drill mode and the clutch mode, when the bit B is pressed against the workpiece, a backward pushing force is applied to the tool holder 35. Therefore, a pushing force is also applied to the regulating plate 71, which regulates the backward movement of the tool holder 35 via the change plate 43. However, as shown in Figure 13, the restricting portions 76, 76 of the restricting plate 71 are arranged symmetrically about the striking axis L, and equally support the left and right receiving portions 44 of the change plate 43. Therefore, even if the pushing force increases, the restricting plate 71 will not deform or tilt. This stabilizes the retracted positions of the change plate 43 and tool holder 35, and ultimately stabilizes the advanced position of the clutch gear 62. Therefore, the boss sleeve 59 does not engage with the clutch gear 62 in either the drill mode or the clutch mode, and the inactive state of the rotation converting portion 58 is maintained.

[0035] On the other hand, in both the drill mode and the clutch mode, friction occurs between the inactive boss sleeve 59 and the rotating intermediate shaft 36. This friction may cause the boss sleeve 59 to rotate following the rotation, causing the rod 61 to swing. However, a rubber plate 78 is provided on the front surface of the base end 75 of the restricting plate 71. Therefore, when the rod 61 swings rearward and the piston cylinder 51 retracts, the rear end of the piston cylinder 51 abuts against the left and right stoppers 79, 79 of the rubber plate 78, preventing the piston cylinder 51 from retracting any further. Therefore, rotation of the boss sleeve 59 is restricted via the rod 61, preventing unexpected impact action.

[0036] As described above, the hammer drill 1 of the above embodiment includes the motor 6, the tool holder 35, the intermediate shaft 36, the rotation converter 58, the change plate 43, the regulating plate 71, and the operating lever 73. Furthermore, when the restricting plate 71 is in a first switching state by the operating lever 73, the hammer drill 1 is in a hammer drill mode in which the tool holder 35 is retracted to the retracted position, allowing the tool holder 35 to rotate and the striking unit 50 to perform a striking action simultaneously. Furthermore, when the restricting plate 71 is in a second switching state by the operating lever 73, the hammer drill 1 is in a drill mode or clutch mode in which the tool holder 35 is restricted from retracting from the forward position and the tool holder 35 is only allowed to rotate. The regulating plate 71 is positioned rearward of the change plate 43 in the direction of the impact axis L, and the regulating plate 71 has two regulating portions 76, 76 that abut against the change plate 43 and regulate the backward movement of the change plate 43, which are provided symmetrically on the left and right sides so that one regulating portion is located in each of the left and right regions facing each other around the impact axis L.

[0037] According to this configuration, in the drill mode and the clutch mode, the two left and right restriction portions 76, 76 provided on the restriction plate 71 can receive the change plate 43 in a balanced manner and restrict the retraction of the tool holder 35. Therefore, even if the pressing force on the tool holder 35 increases, the retraction restriction position of the tool holder 35 can be stabilized, improving reliability in the drill mode and the clutch mode.

[0038] The two restricting portions 76, 76 are provided on the left and right of the impact axis L. Therefore, the retraction restriction position of the tool holder 35 can be stabilized with a minimum number of restriction portions 76, 76. The regulating plate 71 is movable back and forth in the direction of the impact axis L, and in the first switching state, it moves back as the change plate 43 moves back, and in the second switching state, it moves forward to regulate the backward movement of the change plate 43. Therefore, even if the restricting plate 71 is provided behind the tool holder 35, it does not interfere with use in the hammer drill mode. A cam mechanism 72 is provided which allows the regulating plate 71 to move backward in the first switching state and moves the regulating plate 71 forward in the second switching state. Therefore, the restriction plate 71 can be easily switched between forward and backward movement in a space-saving manner.

[0039] The cam mechanism 72 is provided with a conical spring 82 that biases the tool holder 35 forward. Therefore, the tool holder 35 can be protruded to the forward position by utilizing the conical spring 82 provided in the cam mechanism portion 72. The cam mechanism 72 includes a front cam 80 that is arranged behind the regulating plate 71 and is movable back and forth, and a rear cam 81 that is arranged behind the front cam 80 and changes its posture between a first rotation position that allows the front cam 80 to move backward in response to operation of the operating lever 73 and a second rotation position that regulates the forward movement of the front cam 80. The biasing member is a conical spring 82 that is provided between the front cam 80 and the rear cam 81 and biases the front cam 80 together with the regulating plate 71 and the change plate 43 forward. Therefore, the conical spring 82, which is resistant to buckling, can apply a biasing force in the direction of the impact axis L without loss.

[0040] The regulating plate 71, the cam mechanism 72, and the operating lever 73 are arranged on the impact axis L. Therefore, the tool holder 35 and the change plate 43 can be smoothly moved back and forth on the impact axis L to switch modes. The restricting plate 71 is provided with a rubber plate 78 that prevents the rotation conversion part 58 from operating in the drill mode and the clutch mode. Therefore, it is possible to effectively prevent unexpected striking operations in the drill mode and the clutch mode. The striking section 50 includes a piston cylinder 51 housed in the tool holder 35 from the rear so as to be movable back and forth, and a striker 52 housed in the piston cylinder 51 and linked to the back and forth movement of the piston cylinder 51. The rotation conversion unit 58 includes a boss sleeve 59 that is attached to the intermediate shaft 36 and can rotate together with the intermediate shaft 36 when switched to active by the change plate 43, and a rod 61 that is connected to the rear end of the piston cylinder 51 and swings back and forth as the boss sleeve 59 rotates. The rear end of the piston cylinder 51, which has retreated together with the rod 61, comes into contact with the rubber plate 78, thereby restricting the swinging of the rod 61, thereby indirectly preventing the boss sleeve 59 from rotating. Therefore, by restricting the swinging of the rod 61 of the rotation conversion part 58, it is possible to easily prevent unexpected striking operations in the drill mode and the clutch mode. The rubber plate 78 is integrally formed with the regulation plate 71 . Therefore, the rubber plate 78 can be reliably positioned behind the piston cylinder 51 by utilizing the restriction plate 71.

[0041] Modifications of the present disclosure will be described below. The restriction portions of the restriction member are not limited to the above embodiment, in which two restriction portions are provided on the left and right of the impact axis. One restriction portion may be provided in each of two upper and lower regions facing each other about the impact axis, or one restriction portion may be provided in each of two diagonal regions facing each other about the impact axis. The number of restriction portions may be three or more. In this case, one or more restriction portions may be allocated to each of two regions that face each other with the impact axis as the center. The restricting portion is sufficient as long as it can restrict the retraction of the mode switching member so as not to tilt. Therefore, the restricting portions do not need to be arranged at equal intervals in the circumferential direction, and they do not need to be arranged on concentric circles centered on the impact axis. The restricting portion may be an arc-shaped plate that is long in the circumferential direction, instead of a strip-shaped plate as in the above embodiment.The restricting portion may be a rod-shaped portion instead of a plate-shaped portion. The shape of the restricting member may also be changed as appropriate. The base end to which the restricting portion is connected may not be circular as in the above embodiment, but may be other shapes such as a square or polygon. The base end may not be a flat plate, but may be a curved plate or a spherical plate, for example. The mode switching member can also be modified as appropriate to match the shape of the restricting portion of the restricting member. For example, the number and position of the receiving portions can be changed, or the receiving portions can be eliminated so that the entire ring surface receives multiple restricting portions.

[0042] The impact prevention member does not have to be molded integrally with the regulating member like the rubber plate in the above example. The shape of the impact prevention member can be modified as needed. For example, the size and shape of the stopper portion can be changed. The impact prevention member does not have to be the piston cylinder of the striking portion, but may be something that abuts against, for example, the rod of the rotation conversion portion. There may be a plurality of impact prevention members, or the impact prevention member may be omitted. The shapes of the front and rear cams of the cam mechanism can also be changed as needed. For example, the number and shape of the front and rear cam claws can be changed. The front cam can be provided integrally with the regulating member. The biasing member does not have to be a conical spring. Multiple biasing members may be used. For example, two coil springs with different diameters may be arranged in duplicate, or multiple coil springs may be arranged evenly in the circumferential direction around the striking axis. The operating member does not have to be lever-shaped as in the above embodiment. The operating member may be, for example, dial-shaped. The operating position may be reversed between hammer drill mode and rotation-only mode. The operating member does not have to be located behind the cam mechanism. For example, the operating member may be provided on the outer periphery of the rear cam and protrude from the side or top of the housing so as to be operable.

[0043] In the above embodiment, the drill mode and clutch mode can be selected as the second rotation-only operation mode, but the second operation mode may be the drill mode only. In this case, the mode detection switch and operation panel can be omitted. As disclosed in the above-mentioned Patent Document 1, a hammer mode may also be selected by switching the gear (third gear 68 in the above-mentioned embodiment) between a position where it is engaged with the intermediate shaft and a position where it is not engaged with the intermediate shaft. The motor is not limited to one with an upward rotation shaft, and may be one with an inclined rotation shaft. The grip portion is not limited to a loop shape. The hammer drill may be an AC machine that is not powered by a battery pack. [Explanation of symbols]

[0044] 1 hammer drill, 2 main body housing, 3 front housing, 4 motor housing, 5 inner housing, 6 motor, 7 rotating shaft, 10 rotating / impact mechanism, 12 switch, 16 controller, 18 operation panel, 27 guide recess, 30 inner support, 32 metal bearing, 35 tool holder, 36 intermediate shaft, 43 change plate, 44 receiving part, 50 striking part , 51··Piston cylinder, 52··Striker, 58··Rotation conversion section, 59··Boss sleeve, 61··Rod, 62··Clutch gear, 70··Mode switching section, 71··Regulating plate, 72··Cam mechanism section, 73··Operating lever, 74··Mode detection switch, 75··Base end section, 76··Regulating section, 80··Front cam, 81··Rear cam, 82··Conical spring, 100··Disc section, 101··Lever section, L··Impact axis.

Claims

1. A motor; a cylindrical tool holder capable of holding a tool bit at its front end, accommodating an impact portion of the tool bit therein, and being rotatable and movable back and forth coaxially with an impact axis of the impact portion, and being biased to project forward; an intermediate shaft that is provided parallel to the tool holder, to which rotation of the motor is transmitted and that transmits the rotation to the tool holder; a rotation conversion unit provided on the intermediate shaft and configured to convert rotation of the intermediate shaft into a hitting motion of the hitting unit; a mode switching member that moves back and forth integrally with the tool holder, and that makes the rotation converting unit inactive when the tool holder is at an advanced position and makes the rotation converting unit active when the tool holder is at a retracted position; a restricting member that restricts the retraction of the mode switching member when the tool holder is at an advanced position; an operating member that can switch the restricting member between a first switching state in which the mode switching member is not restricted from moving backward and a second switching state in which the mode switching member is restricted from moving backward, a hammer drill in which, when the regulating member is in the first switching state by the operating member, a first operation mode is established in which rotation of the tool holder and an impact action of the impacting section are simultaneously possible as the tool holder is retracted to a retracted position, and when the regulating member is in the second switching state by the operating member, retraction of the tool holder from an advanced position is restricted and a second operation mode is established in which the tool holder is only capable of rotating, a plurality of regulating portions that abut against the mode switching member to regulate the retraction of the mode switching member, the regulating member being provided with at least one regulating portion located in each of two regions that face each other about the impact axis;

2. The hammer drill according to claim 1, wherein two of the restricting portions are provided on the left and right of the striking axis.

3. 3. The hammer drill according to claim 1, wherein the regulating member is movable back and forth in the striking axis direction, and in the first switching state, moves back in conjunction with the retraction of the mode switching member, and in the second switching state, moves forward to regulate the retraction of the mode switching member.

4. 4. The hammer drill according to claim 3, further comprising a cam mechanism that allows the regulating member to move backward in the first switching state and moves the regulating member forward in the second switching state.

5. 5. The hammer drill according to claim 4, wherein the cam mechanism is provided with a biasing member that biases the tool holder forward.

6. the cam mechanism includes a front cam that is disposed rearward of the regulating member and is movable forward and backward, and a rear cam that is disposed rearward of the front cam and changes its position between a first position that allows the front cam to retract in response to operation of the operating member and a second position that regulates the retraction of the front cam forward, 6. The hammer drill according to claim 5, wherein the biasing member is a conical spring provided between the front cam and the rear cam and biases the restricting member and the mode switching member forward together with the front cam.

7. 7. The hammer drill according to claim 4, wherein the restricting member, the cam mechanism, and the operating member are arranged on the striking axis.

8. 8. The hammer drill according to claim 1, wherein the regulating member is provided with a striking prevention member that prevents the rotation conversion portion from operating in the second operating mode.

9. the striking portion includes a piston cylinder housed in the tool holder from a rear side so as to be movable back and forth, and a striking member housed in the piston cylinder and moving in conjunction with the back and forth movement of the piston cylinder, the rotation conversion unit includes: a conversion member that is attached to the intermediate shaft and that is rotatable together with the intermediate shaft when the mode switching member switches to active mode; and a rod that is connected to a rear end of the piston cylinder and swings back and forth in accordance with the rotation of the conversion member, 9. The hammer drill according to claim 8, wherein the impact prevention member restricts swinging of the rod by contacting the rear end of the piston cylinder that has retreated together with the rod.

10. 10. The hammer drill according to claim 8, wherein the impact prevention member is integrally formed with the regulating member.

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