JP2594244Y2 - Non-rotating structure of internal gear of power tool - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a non-rotating structure for holding an internal gear of an electric power tool from rotating in a casing.

[0002]

2. Description of the Related Art In general, a reduction gear mechanism is used in an electric power tool. One of the reduction gear mechanisms is a planetary gear mechanism. In the planetary gear reduction mechanism, in order to reduce the rotation speed of the output shaft of the motor, the internal gear needs to be fixed so as not to rotate. Conventionally, as shown in FIGS. 3 and 4, a concave portion 2 is formed in a casing 1 and a convex portion 4 of the internal gear 3 is held in order to hold the internal gear so as not to rotate in the casing.
Is inserted into the recess 2.

The casing 1 comprises left and right outer shells 1a and 1b.
Is provided. The outer shells 1a and 1b are adapted to receive the projections 4 of the internal gear 3 in the respective recesses 2 and to grip the internal gear 3 from around the respective outer shells 1a and 1b.

As shown in FIGS. 5 and 6, left and right outer shells 5a, 5b
May be formed separately at the joint portion. Left and right outer shell 5
a and 5b complete the concave portions 6 and 7 simultaneously with the joining, and receive the convex portions 9 of the internal gear 8 into the concave portions 6 and 7. Thus, the rotation of the internal gear 8 in the casing 5 is prevented.

[0005]

However, in the above-mentioned conventional anti-rotation structure, when the projection 4 of the internal gear 3 is made to coincide with the depression 2 in the casing 1, the depression 2 However, there is a problem that it is difficult to see because it is hidden by the internal gear 3 and assembly is troublesome.

In the case of the latter, the outer shell 5
Surfaces 6a and 6 that serve to prevent rotation of concave portions 6 and 7 of a and 5b
In order to make the areas of b, 7a and 7b equal to those of the examples of FIGS. 3 and 4, the ribs must be lengthened or the whole ribs must be formed instead of the ribs. Since the length has to be increased, there is a problem that the product becomes large. As shown in FIG. 6 (B), when the whole body is filled, the surfaces 6a, 6b, 7a and 7b become partially thick,
There was a problem that sink marks tended to occur.

[0007]

In order to solve the above-mentioned problems, the present invention provides an electric power tool having a casing (11) provided inside a left and right split outer shells (11a, 11b). Rotation preventing portion (2 ) that engages with the internal gear (19) of the drive portion of the motor to prevent rotation of the internal gear (19).
8) In the structure for preventing rotation of the internal gear of the electric tool provided with 8) , the upper and lower joint portions of the outer shells (11a, 11b).
(12) has the above detent part (28) at the time of joining.
Said internal gear (19) to engage with said internal gear (19);
A guide portion (30) is provided for guiding the helical gear in a fixed direction, and the guided portion guided to the internal gear (19) while sliding on the guide portion (30) at the time of the attachment.
(31) adopts a configuration formed corresponding to each guide portion .

[0008]

The internal gear of the present invention engages with the detent portion inside the outer shell and the guided portion engages with the guide portion of the outer shell, so that rotation is prevented by a plurality of means. Will be done. Therefore, the detent function is improved.

Further, when the outer shell is assembled, the guide portion slides on the guided portion of the internal gear, so that the internal gear automatically engages with the detent portion of the outer shell. Therefore, even if the concave portion is hidden by the internal gear and becomes difficult to see, it can be easily assembled.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. This power tool includes a casing 11 as shown in FIG. This casing 11
The two outer shells are assembled by being joined together at the joint 12. In FIG. 1, only one outer shell 11a is shown, and one outer shell is omitted.

A bit holder 13 for attaching a tool projects from a front portion of the casing 11, and a driving portion having the following structure for driving the bit holder 13 is provided inside the casing 11. .

A motor 14 is provided at the rear of the casing 11.
Is provided facing forward. The rotation speed of the motor 14 is controlled by a power control element 15. The power control element 15 is attached to a heat radiation block 16 provided in front of the motor 14.

A shaft 14a of the motor 14 has a pinion 17
Has been fixed. This pinion 17 has a planetary gear 1
The internal gear 19 meshes with the planetary gear 18. The internal gear 19 is fixed in the casing 11 so as not to rotate. The planetary gear 18 is supported by a carrier 21 via a pin 20. A shaft 23 supported by bearings 22 is fixed to the carrier 21, and the bit holder 13 is disposed at the tip of the shaft 23.

An impact mechanism is interposed between the shaft 23 and the bit holder 13. That is, the hammer 24 is fitted into the shaft 23, and the steel ball 25 is inserted so as to straddle the cam groove 23a and the cam groove 24a respectively formed in the sliding contact portions of the two. Also,
The hammer 24 is constantly pressed forward by a spring 26 mounted on the shaft 23, and a claw portion 24 b is formed at the front portion of the hammer 24. The claw portion 24 b is detachable from the claw portion 13 a of the bit holder 13.

When this electric tool is used, the motor 14
Operate the ON / OFF switch 27 with the trigger 27a.
The motor 14 is driven. The rotation of the shaft 14a of the motor 14 causes the pinion 17 to rotate. Since the planetary gear 18 meshing with the pinion 17 also meshes with the internal gear 19 fixed in the casing 11, the planetary gear 18 revolves around the pinion 17 while rotating. For this reason, the carrier 21 and the shaft 23 rotate.

The rotation of the shaft 23 is made of a steel ball 25.
Through the hammer 24. When the tightening torque transmitted from the bit holder 13 reaches a certain value, the hammer 24 is pulled leftward in FIG. 1 by the cam grooves 23a and 24a.
The claw portion 24b separates from the claw portion 13a of the bit holder 13. By the movement of the hammer 24, the spring urging force of the spring 26 increases, and the rotational force of the hammer 24 is urged. The hammer 24 moves rightward in FIG. I do. Thereby, bit holder 1
3 rotates and tightens or loosens the screw.

In order for the drive unit of the transmission tool to perform the above operation, the rotation of the internal gear 19 in the casing 11 must be prevented, but as shown in FIG. The recess 28 has a split outer shell 11a, 1
1b. The internal gear 19 is provided with a convex portion 29 that enters the concave portion 28, and the concave portion 2 is formed when the outer shells 11a and 11b are combined.
8.

In the internal gear 19, the side walls 29a of the convex portion 29 in the circumferential direction are formed by the corresponding side walls 28a of the concave portion 28.
, Rotation in the casing 11 is prevented.

The casing 11 includes left and right outer shells 11.
a and 11b are assembled by being joined together at their joints 12, and the internal gear 19 is guided into the casing 11 in a fixed direction, and the projection 29 of the internal gear 19 is formed.
Is guided into the concave portion 28 of the casing 11. That is, the joint portion 12 of the outer shells 11a and 11b is provided with a guide portion 30 for guiding the internal gear 19 while regulating it in a fixed direction at the time of the joint. A guided portion 31 is formed to be guided while sliding on the guide portion 30 when worn. Guide part 30
Is a smooth plane formed inside the joint portion 12 of the outer shells 11a and 11b, and each outer surface is flush with each other so that the joint portions 12 of the left and right outer shells 11a and 11b are flush with each other. Shell 11
a, 11b. On the other hand, the guided portion 31 is a flat smooth surface formed on the outer peripheral surface of the internal gear 19. The joint portions 12 of the left and right outer shells 11a and 11b are formed so as to come into contact with the flat surface of the guide portion 30 which is flush when the joint portions 12 are joined.

Thus, the internal gear 1 is placed in the casing 11.
First, the outer shells 11a and 11b are opposed to each other so as to sandwich the internal gear 19 (FIG. 2A).
Next, the outer shells 11a and 11b are brought close to each other so that the guide portion 30 contacts the end of the guided portion 31 (FIG. 2).
(B)). The guide portion 30 and the guided portion 31 are in sliding contact with each other, and guide the internal gear 19 to a predetermined position in the casing 11 while holding the internal gear 19 in a fixed posture and direction.

As shown in FIG. 2A, half the length L of the guided portion 31 of the internal gear 19 is equal to the internal gear 1.
9b is formed to be slightly longer than the height M of the side wall 29a of the projection 29. Thereby, after the guide part 30 and the guided part 31 are first engaged, the convex part 29 and the concave part 28 can be engaged, and the assembly of the casing 11 and the incorporation of the internal gear 19 can be simplified. I can do it.

When the sliding contact between the guide portion 30 and the guided portion 31 is completed, the assembly of the casing 11 is completed, and the convex portion 29 of the internal gear 19 enters the concave portion 28 of the casing 11.

The internal gear 1 stored in the casing 11
9 is a casing 11 formed by engaging the concave portion 28 with the convex portion 29 and engaging the guide portion 30 with the guided portion 31.
Rotation in the inside is prevented.

[0024]

According to the present invention, the internal gear of the power tool is engaged with the detent portion inside the outer shell and the guided portion is engaged with the guide portion of the outer shell. Rotation in the casing can be more reliably prevented.

Further, when assembling the outer shell, the guide portion is brought into sliding contact with the guided portion of the internal gear, so that the internal gear can be automatically engaged with the detent portion of the outer shell. .
Therefore, even if the rotation preventing portion is hidden by the internal gear and becomes difficult to see, the internal gear can be easily assembled in the casing.

[Brief description of the drawings]

FIG. 1 is a partially cutaway side view showing a power tool having a rotation preventing structure for an internal gear according to the present invention, with one outer shell removed.

FIGS. 2A and 2B are cross-sectional views of the rotation preventing structure of the internal gear according to the present invention, wherein FIG. 2A shows a state before assembling, FIG. 2B shows a state during assembling, and FIG.

FIG. 3 is a sectional view showing a conventional rotation preventing structure for an internal gear.

FIG. 4 is a sectional view taken along line IV-IV in FIG.

FIG. 5 is a cross-sectional view showing another conventional anti-rotation structure of an internal gear.

FIG. 6 is a view taken along line VI-VI in FIG. 5;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 ... Casing 11a, 11b ... Outer shell 19 ... Internal gear 28 ... Concave part 12 ... Joining part 30 ... Guide part 31 ... Guided part

──────────────────────────────────────────────────続 き Continued on the front page (58) Fields surveyed (Int. Cl. ⁶ , DB name) B23B 45/00 B25F 5/02 B25B 21/00

Claims (1)

(57) [Scope of request for utility model registration] An inner gear of a drive unit of the power tool is engaged with each of inner left and right outer shells constituting a casing of the power tool. In the detent structure of the internal gear of the electric tool provided with a detent part for preventing rotation, the upper and lower joint parts of the outer shell body are provided with
A guide portion is provided to guide the internal gear while restricting the internal gear in a fixed direction so that the detent portion engages with a predetermined portion of the internal gear. in the guided portion which is guided while sliding on the guide portion each guide portion during wear
A detent structure for an internal gear of an electric tool, which is formed correspondingly .