JPH0642010U - Detent structure for internal gear of electric power tool - Google Patents

Abstract

(57) [Summary] [Purpose] To enhance the rotation prevention function of internal gears. [Structure] The inside of each of the outer shell bodies 11a and 11b forming the casing 11 of the electric power tool is engaged with an internal gear 19 of a drive portion of the electric tool to prevent rotation of the internal gear. A rotation stopping portion 28 is provided. Coupling part 12 of outer shell
Is provided with a guide portion 30 that guides the internal gear while regulating the internal gear in a fixed direction at the time of attachment. The internal gear is provided with a guided portion 31 that is in sliding contact with the guide portion during the above-mentioned attachment. The rotation preventing portion and the guide portion prevent the internal gear from rotating.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a detent structure for holding an internal gear of an electric power tool so as not to rotate in a casing.

[0002]

[Prior art]

 Generally, reduction gears are used in electric tools, and one of the reduction gears is a planetary gear mechanism. In the planetary gear reduction mechanism, in order to reduce the number of rotations of the output shaft of the motor, it is necessary to fix the internal gear so as not to rotate. Conventionally, in order to keep the internal gear from rotating in the casing, as shown in FIGS. 3 and 4, a concave portion 2 is formed in the casing 1 and a convex portion 4 of the internal gear 3 is a concave portion. The structure inserted in 2 is adopted.

The casing 1 is composed of left and right outer shell bodies 1 a and 1 b, and the recess 2 is provided at the center of each of them. The outer shells 1a and 1b are adapted to receive the convex portions 4 of the internal gear 3 in the respective concave portions 2 when they are joined and to grip the internal gear 3 from the periphery thereof.

Further, as shown in FIGS. 5 and 6, the rotation preventing recesses 6 and 7 may be separately formed at the joint portions of the left and right outer shell bodies 5a and 5b. The left and right outer shell bodies 5a and 5b complete the recesses 6 and 7 at the same time as they are joined, and receive the protrusions 9 of the internal gear 8 in the recesses 6 and 7. As a result, the rotation of the internal gear 8 in the casing 5 is blocked.

[0005]

[Problems to be solved by the device]

 However, in the above-described conventional detent structure, in the former one, when the convex portion 4 of the internal gear 3 is made to coincide with the concave portion 2 in the casing 1, the concave portion 2 is hidden behind the internal gear 3. There was a problem that it became difficult and assembly was troublesome.

In the latter case, the areas of the surfaces 6a, 6b, 7a, 7b which are used to prevent the rotation of the recesses 6, 7 of the outer shells 5a, 5b are the same as those in the examples of FIGS. 3 and 4. In order to achieve this, it is necessary to lengthen the ribs or add meat to the entire body instead of the ribs.However, if the ribs are used, the ribs must be lengthened, resulting in a larger product. There was a problem. As shown in FIG. 6 (B), when the entire surface is fleshed, the surfaces 6a, 6b, 7a, 7b are partially thickened, and there is a problem that sink marks easily occur.

[0007]

[Means for Solving the Problems]

 In order to solve the above-mentioned problems, the present invention engages with the internal gear of the drive part of the electric tool inside each of the outer shells of the halves constituting the casing of the electric tool. In the rotation preventing structure of the internal gear of the electric tool, which is provided with the rotation preventing portion for preventing the rotation of the toothed gear, the internal gear is fixed to the fixed portion of the outer shell body at the time of the combination. A guide portion for guiding while regulating is provided, and the internal gear has a guided portion that is guided while slidingly contacting the guide portion at the time of attachment.

[0008]

[Action]

 Since the internal gear of the present invention engages with the rotation preventing portion inside the outer shell body and the guided portion thereof engages with the guide portion of the outer shell body, it is prevented from rotating by a plurality of means. Becomes Therefore, the detent function is improved.

Further, when the outer shell is assembled, the guide portion thereof is in sliding contact with 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]

【Example】

 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. The casing 11 can be assembled by joining the divided outer shells at the joining portion 12. In FIG. 1, only one outer shell 11a is shown, and the outer shell on one side is omitted.

A bit holder 13 for mounting a tool projects from the front part of the casing 11, and a driving part 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 so as to face forward. The rotation speed of the motor 14 is controlled by a power control element 15, and the power control element 15 is attached to a heat radiation block 16 provided in front of the motor 14.

A pinion 17 is fixed to the shaft 14 a of the motor 14. A planetary gear 18 meshes with the pinion 17, and an 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 the carrier 21 via a pin 20. A shaft 23 supported by a bearing 22 is fixed to the carrier 21, and the bit holder 13 is arranged 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 both. Further, the hammer 24 is constantly pressed forward by a spring 26 mounted on the shaft 23, and a claw portion 24b that can be engaged with and disengaged from the claw portion 13a of the bit holder 13 is formed in the front portion.

When using this electric tool, the ON / OFF switch 27 of the motor 14 is operated by the trigger 27a to drive the motor 14. The rotation of the shaft 14a of the motor 14 causes the pinion 17 to rotate. The planetary gear 18 that meshes with the pinion 17 also meshes with the internal gear 19 that is fixed in the casing 11, and therefore revolves around the pinion 17 while rotating. Therefore, the carrier 21 and the shaft 23 rotate.

The rotation of the shaft 23 is transmitted to the hammer 24 via the steel balls 25. When the tightening torque transmitted from the bit holder 13 side reaches a certain value, the hammer 24 is pulled leftward in FIG. 1 by the cam grooves 23a and 24a, and its claw portion 24b separates from the claw portion 13a of the bit holder 13. The movement of the hammer 24 increases the spring biasing force of the spring 26, biasing the rotational force of the hammer 24, and the hammer 24 moves to the right in FIG. 1, striking and engaging the claw portion 13a of the bit holder 13. To do. This causes the bit holder 13 to rotate and tighten or loosen the screw.

In order for the drive part of the power transmission tool to perform the above-described operation, it is necessary to prevent the internal gear 19 from rotating in the casing 11. However, as shown in FIG. A recess 28 is provided inside each of the two outer shell bodies 11a and 11b. The internal gear 19 is provided with a convex portion 29 which is inserted into the concave portion 28, and is adapted to be inserted into the concave portion 28 when the outer shell bodies 11a and 11b are combined.

The internal gear 19 is prevented from rotating in the casing 11 by contacting both side walls 29a of the convex portion 29 in the circumferential direction with the corresponding side walls 28a of the concave portion 28.

The casing 11 is assembled by joining the left and right outer shell bodies 11a and 11b at their joining portions 12, and at this time, the internal gear 19 is guided into the casing 11 in a fixed direction. Then, the convex portion 29 of the internal gear 19 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 the fixed direction of the internal gear 19 at the time of the attachment. A guided portion 31 is formed which is guided while slidingly contacting with the guide portion 30 at the time of attachment. The guide portion 30 is a smooth flat surface formed inside the joint portion 12 of the outer shell bodies 11a and 11b, and becomes flush when the joint portions 12 of the left and right outer shell bodies 11a and 11b are joined. Is formed on each outer shell 11a, 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 left and right outer shell bodies 11a and 11b are formed so as to come into contact with the flat surface of the guide portion 30 that is flush with the above when the joining portions 12 are joined.

In order to mount the internal gear 19 in the casing 11, first, the outer shell bodies 11a and 11b are opposed to each other so as to sandwich the internal gear 19 (FIG. 2 (A)). Next, the outer shell bodies 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 orientation.

As shown in FIG. 2A, half the length L of the guided portion 31 of the internal gear 19 is slightly larger than the height M of the side wall 29a of the convex portion 29 of the internal gear 19b. It is formed long. As a result, first, the guide portion 30 and the guided portion 31 can be engaged with each other, and then the convex portion 29 and the concave portion 28 can be engaged with each other, so that the casing 11 and the internal gear 19 can be easily assembled. You can do it.

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

The internal gear 19 stored in the casing 11 is rotated within the casing 11 by the engagement between the concave portion 28 and the convex portion 29 and the engagement between the guide portion 30 and the guided portion 31. Will be blocked.

[0024]

EFFECTS OF THE INVENTION According to the present invention, the internal gear of the electric power tool is engaged with the rotation preventing portion inside the outer shell, and the guided portion thereof is engaged with the guide portion of the outer shell. It is possible to more reliably prevent the rotation within the casing.

Further, since the guide portion of the outer shell is slidably contacted with the guided portion of the internal gear when the outer shell is assembled, the internal gear can be automatically engaged with the detent portion of the outer shell. . Therefore, even if the detent 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 drawings]

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

2A and 2B are cross-sectional views of a rotation preventing structure for an internal gear according to the present invention, where FIG. 2A is before assembly, FIG. 2B is during assembly, and FIG.

FIG. 3 is a cross-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 rotation preventing structure for an internal gear.

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

[Explanation of symbols]

 11 ... Casing 11a, 11b ... Outer shell 19 ... Internal gear 28 ... Recessed portion 12 ... Coupling portion 30 ... Guide portion 31 ... Guided portion

Claims (1)

[Scope of utility model registration request] 1. A detent portion that engages with an internal gear of a drive unit of the electric tool to prevent rotation of the internal gear inside each of the two outer shells that form the casing of the electric tool. In the rotation preventing structure of the internal gear of the electric tool provided with, the guide portion for guiding the internal gear while restricting the internal gear in a fixed direction at the time of the attachment is provided at the attachment portion of the outer shell body. A detent structure for an internal gear of an electric power tool, wherein the internal gear is formed with a guided portion that is guided while slidingly contacting the guide portion during the attachment.