JP2014042948A - Electric power tool - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electric power tool capable of improving a lifetime of shock-absorbing materials for moderating impact in a rotating direction of a deceleration mechanism part.SOLUTION: An impact driver includes: a motor being a driving source; a planet gear mechanism for decelerating a rotation of the motor; a striking mechanism for converting the rotation of the motor decelerated by the planet gear mechanism into a rotational striking force and transmitting it to a tip tool; and an inner cover 19 for holding a protrusion 15a extending from a ring gear 15 of the planet gear mechanism by interposing a shock absorbing material 20. The impact driver comprises: a spacer 21 interposed in a gap between the protrusion 15a extending from the ring gear 15 and the shock absorbing material 20.

Description

  The present invention relates to an electric power tool such as an impact driver that converts rotation of a driving source such as a motor into a rotational impact force and transmits the rotation to a tip tool.

  An electric power tool such as an impact driver converts a motor that is a driving source, a speed reduction mechanism that decelerates the rotation of the motor, and rotation of the motor decelerated by the speed reduction mechanism into a rotational impact force and transmits the rotation impact force to the tip tool. A striking mechanism. The rotational impact force transmitted to the tip tool also acts as a large load (rotational impact force) on the gear portion of the speed reduction mechanism. Therefore, the speed reduction mechanism part and the holding part that holds the speed reduction mechanism part may be damaged. In view of this, a technique has been proposed in which durability is improved by providing an impact relaxation material that cushions the impact in the rotational direction of the speed reduction mechanism and buffering the rotational impact force of the speed reduction mechanism (see, for example, Patent Document 1). ).

JP 2002-254336 A

  However, in the prior art, since a large impact load is applied in the rotation direction, it is necessary to increase the volume of the shock absorbing material as much as possible. There is a limit to the size due to restrictions. For this reason, the ridgeline of the contact portion of the speed reduction mechanism portion and the impact relaxation material come into contact with each other, the surface pressure is increased, and the life of the impact relaxation material is shortened.

  The present invention has been made in view of the situation as described above, and provides an electric tool that solves the above-described problems and can improve the life of an impact mitigating material that mitigates the impact in the rotational direction of the speed reduction mechanism. For the purpose.

The electric tool of the present invention includes a motor as a drive source, a planetary gear mechanism that decelerates the rotation of the motor, and converts the rotation of the motor decelerated by the planetary gear mechanism into a rotational impact force and transmits it to the tip tool. The planetary gear mechanism is an electric tool including a gear holding portion that holds a protrusion extending from a fixed gear of the planetary gear mechanism with an impact buffering material interposed therebetween, A spacer interposed between the projection extending from the gear and the shock absorbing material is provided.
Furthermore, in the electric tool of the present invention, a contact area between the spacer and the protrusion may be set larger than a contact area between the spacer and the shock absorbing material.
Furthermore, in the electric tool of the present invention, the spacer may be configured to be longer in the radial direction than the protrusion.
Furthermore, in the electric tool according to the present invention, the spacer may be made of a material having rigidity higher than that of the shock absorbing material.

  According to the present invention, since the contact area with the impact relaxation material is increased by the spacer and the impact load applied to the impact relaxation material is dispersed, the life of the impact relaxation material can be improved.

It is a sectional side view which shows the internal structure of embodiment of the electric tool which concerns on this invention. It is AA fragmentary sectional drawing shown in FIG. It is a disassembled perspective view which shows the structure of the ring gear and inner cover shown in FIG. It is a BB partial sectional view shown in FIG. It is explanatory drawing explaining the conventional impact relaxation operation | movement. It is explanatory drawing explaining the impact relaxation operation | movement in embodiment of the electric tool which concerns on this invention. It is a perspective view which shows the modification of the impact relaxation material and spacer shown in FIG.

Next, embodiments of the present invention will be specifically described with reference to the drawings.
The electric power tool according to the present embodiment is an impact driver 1 and includes a housing 2 and a hammer case 3 which are outer frames forming an outer shape as shown in FIG. The housing 2 includes a substantially cylindrical body portion 2a extending in the front-rear direction, and a handle portion 2b connected to the body portion 2a so as to form a substantially T shape in a side view. The body 2 a of the housing 2 accommodates a motor 4 that is a drive source and a planetary gear mechanism 5 that functions as a speed reduction mechanism that decelerates the rotation of the motor 4. Inside the hammer case 3 is housed a striking mechanism 6 that converts the rotation of the motor 4 decelerated by the planetary gear mechanism 5 into a rotational striking force and transmits it to a tip tool (not shown).

  The handle 2b of the housing 2 is provided with a switch 8 having a trigger 7 at the upper part and a battery receiving part 9 at the lower part. A battery BT, which is a rechargeable power source, is detachably attached to the battery receiving portion 9 at the lower end of the handle portion 2b.

  In the impact driver 1, when the operator turns on the trigger 7, the switch 8 is turned on and the motor 4 is activated. When the motor 4 is activated, the rotation of the output shaft 4a of the motor 4 is decelerated by the planetary gear mechanism 5 and transmitted to the spindle 10, and the spindle 10 is rotationally driven at a predetermined speed. Here, the spindle 10 is connected to the hammer 11 by a cam mechanism, and the spindle 10 and the hammer 11 connected by the cam mechanism function as the striking mechanism 6. The cam mechanism for connecting the spindle 10 and the hammer 11 includes a V-shaped spindle cam groove 10 a formed on the outer peripheral surface of the spindle 10, and a V-shaped hammer cam groove 11 a formed on the inner peripheral surface of the hammer 11. A ball 12 that engages with the spindle cam groove 10a and the hammer cam groove 11a, and a spring 13 are provided.

  The hammer 11 is always urged forward (forward) by a spring 13, and when stationary, the hammer 12 is engaged with the spindle cam groove 10 a and the hammer cam groove 11 a so as to be spaced from the end face of the anvil 14. is there. And the convex part is each formed in the symmetrical position in two places on the rotation plane where the hammer 11 and the anvil 14 oppose each other. The anvil 14 is a part where a not-shown tip tool is detachably mounted.

  As described above, when the spindle 10 is rotationally driven at a predetermined speed, the rotation of the spindle 10 is transmitted to the hammer 11 through the cam mechanism, and the protrusion of the hammer 11 is moved before the hammer 11 is rotated halfway. The anvil 14 is rotated by being engaged with the convex portion of the anvil 14. When the relative rotation occurs between the hammer 11 and the spring 13 by the engagement reaction force at that time, the hammer 11 is moved to the spindle of the cam mechanism. While the spring 13 is compressed along the cam groove 10a, it starts to move backward toward the motor 4 side.

  When the protrusion of the hammer 11 moves over the protrusion of the anvil 14 by the backward movement of the hammer 11 and the engagement between the two is released, the hammer 11 is elastically accumulated in the sling 13 in addition to the rotational force of the spindle 10. While being accelerated rapidly in the rotational direction and forward by the action of energy and the cam mechanism, it is moved forward, that is, toward the anvil 14 side by the biasing force of the spring 13, and the convex portion of the hammer 11 is again engaged with the convex portion of the anvil 14. Together they start to rotate as a unit. At this time, since a strong rotational impact force is applied to the anvil 14, the rotational impact force is transmitted to a screw (not shown) via a tip tool attached to the anvil 14. Thereafter, the same operation is repeated, and the rotational impact force is intermittently and repeatedly transmitted from the tip tool to the screw, and the screw is screwed into a material to be fastened such as wood.

  2, the planetary gear mechanism 5 meshes with the ring gear 15 that is a fixed gear, the pinion 16 (functioning as an input gear) formed at the end of the output shaft 4a of the motor 4, and the ring gear 15 and the pinion 16. And two planetary gears 17 (functioning as output gears) and an inner cover 19. Each planetary gear 17 is connected to the spindle 10 by a shaft 18. A step portion 15b is formed at the front end of the outer periphery of the ring gear 15, and the inner peripheral surface of the inner cover 19 is fitted to the outer peripheral surface excluding the step portion 15b. The inner peripheral surface of the hammer case 3 is fitted to the outer peripheral surface of the step portion 15 b of the ring gear 15 and the outer peripheral surface of the inner cover 19. Further, an O-ring 22 is fitted as a seal member on the outer periphery of the ring gear 15.

  The ring gear 15, which is a fixed gear, is held by an inner cover 19 that functions as a gear holding portion that holds the planetary gear mechanism 5, and the inner cover 19 is fixed in the body portion 2 a of the housing 2. Referring to FIG. 3, bag-like convex portions 19 a are integrally projected at two places on the rear end surface of the inner cover 19, and an impact relaxation material such as rubber is provided in the concave space formed in each convex portion 19 a. 20 are accommodated respectively. The impact relaxation material 20 is formed in a U-shaped cross section by a pair of impact relaxation portions 20a and a connection portion 20b connecting the pair of impact relaxation portions 20a, and is formed in the convex portion 19a from the connection portion 20b side. It is assembled in a concave space. In addition, referring to FIG. 1, a notch-shaped engaging recess 2c is formed at two locations on the inner periphery of the body portion 2a of the housing 2, and the protruding portion 19a of the inner cover 19 is engaged with the engaging recess 2c. By doing so, the inner cover 19 is prevented from rotating.

  Referring to FIG. 3, a flange 15 c for increasing the strength of the ring gear 15 is formed at the rear end of the ring gear 15. Two protrusions 15a extending from the flange 15c of the ring gear 15 in the direction of the inner cover 19 protrude from the two rear end surfaces of the flange 15c. The protrusion 15 a is inserted into a concave space formed in the convex portion 19 a of the inner cover 19, thereby preventing the ring gear 15 from rotating. As shown in FIG. 4, the protrusion 15 a is inserted and assembled into the gap between the pair of impact relaxation portions 20 a accommodated in the concave space formed in the convex portion 19 a of the inner cover 19 via the spacer 21. . The spacer 21 is configured in a U-shaped cross section with a pair of contact plates 21a that respectively contact the pair of impact relaxation portions 20a of the impact relaxation material 20 and a connection portion 21b that connects the pair of contact plates 21a. The connecting portion 21b is inserted and assembled into the gap between the pair of impact relaxation portions 20a accommodated in the concave space formed in the convex portion 19a. At least the contact plate 21a of the spacer 21 is made of a material such as a metal having higher rigidity than the impact relaxation portion 20a. In addition, the contact plate 21a of the spacer 21 is configured to be longer than the protrusion 15a of the ring gear 15 in the radial direction, and the contact plate 21a and the impact relaxation portion are larger than the contact area of the protrusion 15a and the contact plate 21a of the ring gear 15. The contact area with 20a is set larger. Furthermore, it is more preferable that the contact plate 21a is configured to have the same shape as the facing surface of the impact relaxation portion 20a or a shape larger than the facing surface of the impact relaxation portion 20a.

  The diameter R of the flange 15c provided with the protrusion 15a is set larger than the diameter of the flange 10b (see FIG. 2) of the spindle 10 in order to shorten the axial length of the impact driver 1. The protrusion 15a is configured to have the same length as the flange 15c in the radial direction so as not to hinder the rotation of the spindle 10. Therefore, the size in the radial direction of the protrusion 15a that prevents the ring gear 15 from rotating is limited. On the other hand, the impact relaxation portion 20a is configured to be longer than the protrusion 15a of the ring gear 15 in the radial direction in order to increase the volume as much as possible and reduce the impact load of the ring gear 15 as much as possible. Therefore, when the projection 15a of the ring gear 15 and the impact mitigating portion 20a are brought into contact with each other without the spacer 21, the projection 15a of the ring gear 15 and the impact mitigating material 20 are brought into contact as shown in FIG. The contact area is insufficient, the surface pressure is high with respect to the impact load in the rotational direction, and the life of the impact relaxation material 20 is shortened. Further, when the hammer 11 hits the anvil 14 and hits the maximum back in the axial direction, the ring gear 15 receives a force in the rotational direction, and the protrusion 15a of the ring gear 15 crushes the impact relaxation portion 20a, and stress is applied to the ridge 15aa of the protrusion 15a. Concentrates and the life of the shock absorbing material 20 is shortened.

  On the other hand, in the present embodiment, a contact plate 21a of the spacer 21 is provided between the protrusion 15a of the ring gear 15 and the impact relaxation portion 20a of the impact relaxation material 20. As shown in FIG. 6, the contact plate 21 a of the spacer 21 is configured to be longer than the protrusion 15 a of the ring gear 15 in the radial direction, and the contact plate is larger than the contact area of the protrusion 15 a and the contact plate 21 a of the ring gear 15. The contact area of 21a and the impact relaxation part 20a is larger. Since the impact load in the rotational direction applied to the projection 15a of the ring gear 15 is received by the entire contact surface between the contact plate 21a of the spacer 21 and the impact relaxation portion 20a via the projection 15a, the surface pressure against the impact load in the rotational direction is reduced. In addition, it is possible to relieve the concentrated stress applied to the impact relaxation portion 20a and to improve the life of the impact relaxation material 20.

  In the present embodiment, in order to improve the assemblability, the spacer 21 composed of the pair of contact plates 21a and the connecting portion 21b is used. However, only the pair of contact plates 21a is used as the spacer 21. May be. In the present embodiment, when the spacer 21 is assembled, the spacer 21 is assembled from the connection portion 21b side. However, the connection portion 21b may be assembled toward the inner side or the outer side in the radial direction. Furthermore, in order to improve the assemblability, the impact relaxation material 20 and the spacer 21 can be bonded in advance. In this case, as shown in FIG. 7A, only the impact relaxation portion 20a is bonded to the spacer 21, or only the contact plate 21a is attached to the impact relaxation material 20 as shown in FIG. 7B. It is possible to adopt a configuration for bonding. Alternatively, the spacer 21 and the impact relaxation material 20 shown in FIG. 3 can be bonded.

  Moreover, in the above description, although the example which applied this invention to the cordless impact driver 1 provided with a rechargeable battery was demonstrated, this invention can be applied similarly also to an impact driver with a cord. In addition, the present invention is not limited to application to electric tools such as impact drivers, but can be widely applied to various portable power tools including pneumatic tools such as air impact wrench. Of course.

  As described above, in the present embodiment, the motor 4 that is a drive source, the planetary gear mechanism 5 that decelerates the rotation of the motor 4, and the rotation of the motor 4 that is decelerated by the planetary gear mechanism 5 is used as the rotational impact force. The planetary gear mechanism 5 includes an inner cover 19 that holds a projection 15a extending from the ring gear 15 of the planetary gear mechanism 5 with an impact buffer 20 interposed therebetween. The impact driver 1 includes a spacer 21 interposed in a gap between a projection 15 a extending from the ring gear 15 and the shock absorbing material 20. With this configuration, the rotational impact load applied to the projection 15a of the ring gear 15 is received by the entire contact surface between the contact plate 21a of the spacer 21 and the impact relaxation portion 20a via the projection 15a. A surface pressure can be made low and the lifetime of the impact relaxation material 20 can be improved.

  Furthermore, in the present embodiment, the contact area between the spacer 21 (contact plate 21a) and the protrusion 15a is set to be larger than the contact area between the spacer 21 and the shock absorbing material 20 (impact mitigating portion 20a). . With this configuration, the surface pressure with respect to the impact load in the rotation direction can be further reduced, and the life of the impact relaxation material 20 can be further improved.

  Furthermore, in the present embodiment, the spacer 21 (contact plate 21a) is configured to be longer in the radial direction than the protrusion 15a. Further, the spacer 21 (contact plate 21a) is made of a material having higher rigidity than the shock absorbing material 20 (impact mitigating portion 20a). With this configuration, the concentrated stress applied to the impact relaxation portion 20a can be relaxed without the stress being concentrated on the ridge line 15aa of the protrusion 15a.

  The present invention has been described based on the embodiments. This embodiment is an exemplification, and it will be understood by those skilled in the art that various modifications can be made to combinations of these components and the like, and such modifications are within the scope of the present invention.

DESCRIPTION OF SYMBOLS 1 Impact driver 2 Housing 2a Body part 2b Handle part 2c Engagement recessed part 3 Hammer case 4 Motor 4a Output shaft 5 Planetary gear mechanism 6 Impact mechanism 7 Trigger 8 Switch 9 Battery receiving part BT Battery 10 Spindle 10a Spindle cam groove 10b １１ 11 Hammer 11a hammer cam groove 12 ball 13 spring 14 anvil 15 ring gear 15a protrusion 15aa ridge line 15b step 15c １６ 16 pinion 17 planetary gear 18 shaft 19 inner cover 19a convex part 20 impact mitigating part 20a impact mitigating part 20b connecting part 21 spacer 21 a spacer 21 Connection 22 O-ring

Claims (4)

A motor as a drive source, a planetary gear mechanism that decelerates the rotation of the motor, and a striking mechanism that converts the rotation of the motor decelerated by the planetary gear mechanism into a rotational striking force and transmits it to the tip tool, The planetary gear mechanism is an electric tool including a gear holding portion that holds a projection extending from a fixed gear of the planetary gear mechanism with an impact buffering material interposed therebetween,
A power tool comprising a spacer interposed in a gap between the projection extending from the fixed gear and the shock absorbing material.   The power tool according to claim 1, wherein a contact area between the spacer and the protrusion is set larger than a contact area between the spacer and the shock absorbing material.   The electric tool according to claim 1, wherein the spacer is longer in the radial direction than the protrusion.   The electric power tool according to claim 1, wherein the spacer has higher rigidity than the shock absorbing material.

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