JPH06262413A - Power switching mechanism in rotary tool - Google Patents

Abstract

PURPOSE:To smoothly execute the switching operation by suppressing the shock of engagement of a clutch member with a gear or the like in a power transmission mechanism, and maintain excellent assembling accuracy with a simple structure. CONSTITUTION:A bottomed hole where the upper side is open is cut in a body 31 of a change lever 30 to be fitted to the lower part of a gear housing 7, and a pushing piece 25 where symmetrical inclined surfaces 27, 28 are formed on its head part is freely fitted through a spring 29. Tapered surfaces 22a, 22b are formed on each side wall of a recessed groove 22 of a clutch 21. This constitution allows the pushing piece 25 to absorb the load by the retreat of the inclined surface 27 along the tapered surface 22a of the recessed groove 22 even when the clutch 21 is not smoothly engaged with a second gear 8, and also allows the maintenance of the condition where the clutch 21 is energized to the second gear 8 side by the energizing of the spring 29 and the turning operation of the change lever 30. Thus, a clutch claw is immediately engaged with a biting claw 8a and the condition where both claws are not engaged with each other does not continue.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power switching mechanism for switching rotational speeds and operating modes in rotary tools such as hammer drills and driver drills.

[0002]

2. Description of the Related Art A power switching mechanism for a rotary tool employs a clutch mechanism including a power transmission member loosely fitted to an intermediate shaft and a clutch member having a clutch pawl that meshes with a meshing pawl of the power transmission member. It For example, in a hammer drill in which the striking and rotation modes can be arbitrarily selected, the clutch member is spline-coupled to an intermediate shaft that transmits power from a motor to a bit or a cylinder, and both sides of the clutch member have a striking action transmitting side. The boss and the second gear on the rotational action transmitting side are arranged. Then, the clutch member is moved by the operation of the switching lever or the like, and the clutch claws formed at both ends of the clutch member are disengaged from the meshing claws provided on the boss and the second gear, respectively. A power transmission mechanism capable of switching between the striking mode and the rotating mode is configured. However, at the time of switching the above modes, when switching from the impact mode to the rotation + percussion mode or from the rotation mode to the rotation + percussion mode, the clutch pawls of the clutch member and the meshing pawls may not be smoothly engaged. If the above problem occurs during switching when the motor is stopped, if the motor is started the engagement position is corrected by the rotation of the clutch member and the meshing immediately occurs.However, when switching when the motor is operating, the clutch member rotates. Since it tries to mesh with the second gear, it is difficult for the rotating clutch claw and the meshing claw to smoothly engage with each other, and the claws collide with each other so that the switching is not smoothly performed. Therefore, the applicant of the present invention has filed a prior application, Japanese Patent Application No. 5-2, to solve the above problems.
No. 3766, elastic means for urging the clutch member in the engagement direction, specifically, the elastic member in the bottomed hole 43 of the switching lever 42 into which the eccentric pin 41 fitted to the clutch member 40 is loosely fitted as shown in FIG. By interposing an O-ring 44 or the like, the clutch pawls 40a, 40b and the engaging pawls 45, 4
Disclosed is an invention in which even if 6 does not engage with each other, the load is absorbed and the two are immediately engaged.

[0003]

However, in applying the elastic means, for example, in the case of the above-mentioned prior application in which an eccentric pin is mounted by an O-ring, the number of parts is increased, and
Due to variations in the dimensions of the O-ring itself, it was difficult to make the assembly accuracy of the switching mechanism uniform, and there was a case where the clutch members could not be switched smoothly. Further, there has been a problem that permanent deformation occurs in the O-ring due to long-term use and its elasticity deteriorates.

[0004]

SUMMARY OF THE INVENTION Therefore, the present invention reduces the number of parts to simplify the construction, uniform the assembling accuracy, and also eliminates the stress concentration in the fitting portion to smoothly perform the clutch switching operation. (EN) Provided is a power switching mechanism that can be carried out, in which a clutch member is provided with a fitting groove having a side wall formed into a tapered surface, and the fitting groove is formed between the switching lever and the clutch member. It is characterized in that a connecting member having an inclined surface that matches the taper surface and biased toward the fitting groove is interposed.

[0005]

When the switching lever is operated to slide the clutch member toward the power transmission member, if the two do not mesh smoothly, the connecting member is pushed by the taper surface provided in the fitting groove of the clutch member and once Retreat and absorb load. After that, the clutch member and the power transmission member are engaged with each other by the urging force, and the connecting member quickly returns to the original position. Thus, the stress of the fitting portion with the clutch member is dispersed by the connecting member that moves back and forth perpendicularly to the sliding direction of the clutch member, and an unreasonable burden is not applied to the clutch member and the connecting member.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to a hammer drill will be described below with reference to the drawings. FIG. 1 is a partial vertical cross-sectional view of a hammer drill 1. The rotational force of a motor 3 incorporated in a motor housing 2 is transmitted through a pinion 5a of a motor shaft 5 supported by an intermediate casing 4 and a first gear 6. The bit B is transmitted to the intermediate shaft 7, transmitted to the third gear 9 meshing with the pinion 8b of the second gear 8 loosely fitted to the intermediate shaft 7, and rotates the bit B via the tool holder 10. The rotational force transmitted to the intermediate shaft 7 is applied to the boss 1 by the clutch mechanism 20.
1 to be converted into reciprocating motion of the piston cylinder 13 via the piston arm 12, and utilizing the air spring action between the air chamber 14 and the striker 15, the striking force is applied from the striker 15 to the bit via the striker 16. Be transmitted as.

As shown in FIGS. 1 and 2, the clutch mechanism 20 for transmitting the power from the intermediate shaft 7 to the second gear 8 or the boss 11 has the same structure as that described in the prior art. The clutch 21 is spline-engaged so as to be slidable in the axial direction of the intermediate shaft 7, and a concave groove 22 having both side surfaces machined into tapered surfaces 22a and 22b is formed in the outer peripheral substantially center thereof. Clutch pawls 23 and 24 are provided at both ends of the clutch 21 so as to project therefrom.
It is also possible to mesh with the meshing claws 11a and 8a provided on the second gear 8. In the clutch mechanism 20, the clutch pawls 23 and 24 of the clutch 21 are constantly engaged with each other,
8a, the sliding position is changed between the boss 11 and the second gear 8 so as to mesh with either one or both of them, and the power transmission mode is determined. The change lever 30 is installed in the mounting hole 17a provided in the lower portion of the gear housing 17.
Is rotatably fitted, and the change lever 30 is made of a synthetic resin in which a columnar main body 31, a disk 32, and a knob portion 33 are integrally molded, and a groove portion 35 around which an O-ring 34 is mounted is formed in the lower portion of the main body 31. A groove 36 is provided around the circumference of the main body 31, and the tip of the screw 18 is fitted in the upper part of the main body 31 to prevent the change lever 30 from rotating and coming off. The disk 32 has three circular recesses 32a, 32
b and 32c are provided, and the ball 19 urged by the spring 19a provided in the ball hole 17b of the gear housing 17 is engaged with and disengaged from the circular recesses 32a to 32c by the rotation of the change lever 30.
You can check the mode switching. Further, the change lever main body 31 is provided with a bottomed hole 37 having an open upper surface, and the pressing element 25 is inserted into the bottomed hole 37 via a spring 29.
Is loosely fitted. The pusher 25 has an inclined surface 27 in which the head is left and right symmetrically cut out leaving a flat top 26.
28 is formed. Therefore, when the change lever main body 31 is assembled, as shown in FIG.
8 is the tapered surface 22a, 22b, and the top portion 26 is the bottom surface 22c.
, And the presser 25 is fitted into the groove 22 of the clutch 21. Further, since the center of the bottomed hole 37 is not aligned with the center of the main body 31, when the change lever 30 is fitted into the gear housing 17 and rotated, the bottomed hole 37 is formed.
The pusher 25 supported by the above draws an arcuate locus about the center of the main body 31 and moves back and forth with respect to the axial direction of the intermediate shaft 7.

In the power switching mechanism configured as described above, when the knob portion 33 of the change lever 30 is rotated from, for example, the striking mode (FIG. 3) to the rotation + striking mode side, the pusher 25 is rotated along with the rotation. The clutch 21 in which the pressing element 25 is fitted also slides toward the second gear 8 side while moving to the second gear 8 side, and the clutch claw 24 tries to mesh with the meshing claw 8a of the second gear 8. However, since the rotating clutch claw 24 and the stopped meshing claw 8a mesh with each other, the pressing element 2
In some cases, the two collide against each other against the movement of No. 5 and the meshes do not mesh smoothly. At this time, the force for rotating the change lever 30 is applied most to the pusher 25, but the pusher 25 has the inclined surface 27 on the rotation direction side retracted along the tapered surface 22a of the concave groove 22 as shown in FIG. The load 25 absorbs the load, and the pusher 25 urges the clutch 21 toward the second gear 8 by the biasing of the spring 29 and the rotating operation of the change lever 30 so that the inclined surface 27 pushes the tapered surface 22a. As shown in FIG. 1, the clutch claw 24 and the meshing claw 8a immediately mesh with each other, and the pusher 25 also advances and fits into the recessed groove 22, as shown in FIG. Switch to rotation + batting mode. Further, when the switching operation is performed or a problem occurs, the fitting portion between the pusher 25 and the groove 22 is most stressed, but the pusher 25 using the tapered surface is perpendicular to the sliding direction of the clutch 21. By moving back and forth, the stress is dispersed and the load on the clutch 21 and the presser 25 can be reduced. When the change lever 30 is further rotated while the clutch 21 and the second gear 8 are meshed with each other, the clutch 21 is moved to the left by the pressing element 25, and the ball 19 is fitted into the circular recess 32a to rotate the change lever 30. The movement is blocked, and the mode is switched to the rotation mode as shown in FIG. The above operation rotates from rotation mode +
The same applies to the case of switching to the striking mode side, as shown in FIG. 6, the sliding direction of the clutch and the rotating direction of the change lever are opposite to the above, and the inclined surface 28 of the pressing element 25 and the tapered surface 22b of the concave groove 22 are formed. Therefore, the same effect as described above is obtained. Even when the knob 33 of the change lever 30 is rotated from the striking mode to the rotation + striking mode or from the rotation mode to the rotation + striking mode while the motor 3 is stopped, the clutch pawl is moved as the pressing element 25 moves. 24 and the meshing claw 8a or the clutch claw 23 and the meshing claw 11a do not mesh, the pusher 25 retreats along the tapered surface 22a or 22b of the groove 22 in the same manner as described above, and the pusher 25 disengages the clutch 21. Since the energized state is always maintained, the clutch pawls 23 and 24 are automatically engaged with each other when the clutch 21 is rotated by driving the motor 3.
, And the mode can be switched smoothly.

In the above embodiment, the pressing means 25 and the concave groove 22 of the clutch 21 are engaged with each other by forming two inclined surfaces 27 and 28 corresponding to the tapered surfaces 22a and 22b of the concave groove 22, respectively. However, the present invention is not limited to the above-mentioned embodiment as long as it has an inclined surface that abuts the tapered surface of the concave groove and can be retracted while urging the clutch at the time of switching. As shown in FIG. 7, the bottom surface 22 of the groove 22
The head is formed into a conical shape, leaving the circular top portion 26a corresponding to c, and the tapered surfaces 22a and 22b of the concave groove 22 are formed into the inclined side surfaces 2.
There is no problem even if it is configured to be pressed by 7a. Further, the above-mentioned embodiment is applied to a switching mechanism for operating modes of striking and rotating, but in the case of a rotary tool using a clutch mechanism, for example, a switching mechanism that can change the rotation speed of the motor by the clutch mechanism is provided. It is also applicable to rotating tools.

[0010]

As described above, according to the present invention, in the power transmission mechanism employing the clutch mechanism, the switching operation can be smoothly performed, the wear and heat generation of the member due to the operation can be suppressed, and the rotation speed and the operation mode can be reduced. Trouble during switching can be reliably prevented. Further, by simplifying the structure, it is possible to reduce the labor and cost of assembling, and it is possible to mass-produce tools with uniform assembling accuracy and good durability.

[Brief description of drawings]

FIG. 1 is a partial vertical sectional view of a hammer drill of the above embodiment.

FIG. 2 is a perspective view showing a power transmission mechanism of the above embodiment.

FIG. 3 is an explanatory diagram showing an operating state of the power transmission mechanism of the above embodiment.

FIG. 4 is an explanatory diagram showing an operating state of the power transmission mechanism of the above embodiment.

FIG. 5 is an explanatory diagram showing an operating state of the power transmission mechanism of the above embodiment.

FIG. 6 is an explanatory diagram showing an operating state of the power transmission mechanism of the above embodiment.

FIG. 7 is an explanatory view showing another embodiment of the power transmission mechanism.

FIG. 8 is an explanatory diagram showing a conventional power transmission mechanism.

[Explanation of symbols]

1 ... Hammer drill, 2 ... Motor housing, 3 ...
・ Motors 4 ・ ・ Intermediate casings 5 ・ ・ Motor shafts 6
..First gear, 7 ... Intermediate shaft, 8 ... Second gear, 8a
・ Mating claws, 9 ・ ・ 3rd gear, 10 ・ ・ Tool holders, 11 ・ ・ Boss, 11a ・ ・ Mating claws, 12 ・ ・ Piston arms, 13 ・ ・ Piston cylinders, 14 ・ ・ Air chambers, 15 ・ ・ Strikes , 16 ... striker, 17 ...
Gear housing, 18 ・ ・ screw, 19 ・ ・ ball, 20
..Clutch mechanism, 21..Clutch, 22..Concave groove,
22a, 22b ··· Tapered surface, 23, 24 · · Clutch pawl, 25 · · Presser, 26 · · Top, 27, 28 · · Inclined surface, 29 · · Spring, 30 · · Change lever, 31 ·
・ Main body, 32 ・ ・ Disc, 33 ・ ・ Knob part, 34 ・ ・ O
Rings, 35, 36 ... Grooves, 37 ... Bottomed holes.

Claims (2)

[Claims] 1. An intermediate shaft, which is axially supported by a housing and to which drive rotation from a motor is transmitted, and an intermediate shaft that rotates integrally with the intermediate shaft and is slidably mounted in the axial direction. A rotary tool including a clutch member, a power transmission member that is loosely fitted to the intermediate shaft so as to face the clutch member, and has a meshing claw that meshes with the clutch claw, and a switching lever that operates the clutch member to move in the axial direction. In the power switching mechanism, the clutch member is provided with a fitting groove having a side wall formed into a tapered surface, and an inclined surface adapted to the tapered surface of the fitting groove is provided between the switching lever and the clutch member. A power switching mechanism in a rotary tool, characterized by interposing a connecting member urged toward the fitting groove side. 2. The power transmission member is a bit rotating member and a striking member which are loosely fitted to the intermediate shaft with the clutch member interposed therebetween, and the fitting groove of the clutch member has tapered side walls. At the same time, the connecting member is formed with inclined surfaces adapted to both tapered surfaces of the fitting groove, and the operation mode is only rotation, only striking, due to engagement / disengagement of the clutch member and the power transmission member with the operation of the switching lever. Is a hammer drill in which rotation and impact are switched respectively.
The power switching mechanism according to item.