JPH07167226A - Reduction gear - Google Patents

Abstract

PURPOSE:To obtain required deflection property of an external gear without extending its length by forming cut-outs on the outer circumferential edge of the disc shape retaining base part of the flexible external gear. CONSTITUTION:A plurality of T shape cut-outs 2-5 and a plurality of long and narrow cut-outs 2-4 extending in the circumferential direction are formed and arranged approximately uniformly and alternately on the outer circumferential edge of the base part equivalent to the joint between the cylindrical gear forming part 2-2 of a cup shaped external tooth gear 2 on the rotating side and disc shape retaining base part 2-3. By lessening rigidity of the joints, these plurality of cut-outs 2-4, 2-5 facilitate deflection of the cylindrical external gear forming part 2-2, even if the cylindrical part is not extended in order to secure deflection property at the time when they engage with a fixed side internal gear 1-1 by means of the rotation of a wave generator 6. Thus required deflection property can be obtained, without extending the length of the flexible external gear 2, and may not detract from engaging accuracy.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a speed reducer in which an input shaft and an output shaft can be arranged coaxially.

[0002]

2. Description of the Related Art The contents of the prior art will be described with reference to FIGS. 4 and 5 are cross-sectional views of the essential parts of an example of a speed reducer in which a planetary gear mechanism and a harmonic drive mechanism are combined, as disclosed in JP-A-4-244637 previously filed by the applicant of the present application. And a cross-sectional view of the flexible rotary side external toothed wheel 2 of the harmonic drive mechanism used in this example, the details of which are omitted, but the planetary gear of the planetary gear mechanism that constitutes the input side as shown in FIG. 4 is omitted. An elliptical arm 6 that rotates in unison with 5 also serves as a wave generator 6 of a harmonic drive mechanism that constitutes the output side, and has a flexible rotation that is fixedly connected to the output shaft 3 by the rotation of the wave generator 6. The inner peripheral surface of the cylindrical portion of the side external tooth wheel 2 is sequentially pressed outward to form the outer tooth 2-1 of the rotating side outer tooth wheel 2 and the fixed side internal tooth formed on the housing or fixed to the housing. It is to be engaged with the wheel & pinion 1-1.

[0003]

SUMMARY OF THE INVENTION The conventional structure as described above is used as a means for realizing engagement between the fixed side internal tooth wheel 1-1 and the rotating side external tooth wheel 2-1. The spiral wheel 2-1 has rigidity in the circumferential direction and is premised on the radial deflection due to the rolling and pressing of the wave generator 6, and the outside of the rotation side is prevented so that the deflection does not impair the proper engagement of the gears. Toothed wheel 2-
There is a problem that the length of the cylindrical portion 2-2 of No. 1 has to be made large with respect to the length of the gear engaging portion, so that the size of the reduction gear device also becomes large.

[0004]

According to the speed reducer of the present invention, a flexible rotating outer toothed wheel 2-1 of a harmonic drive mechanism is provided with a cylindrical gear forming portion 2-2 and a disc-shaped holding member. The bottom surface portion 2-3 and the disk-shaped bottom surface portion 2-3 are integrally formed into a cup shape, and a plurality of cutout portions 2-4 extending in the circumferential direction are arranged in the vicinity of the outer peripheral edge of the disk-shaped bottom surface portion 2-3 substantially evenly or around the circumference. The cutout portions 2-4 extending in the direction and the T-shaped cutout portions 2-5 are arranged alternately.

[0005]

[Operation] In the above-described structure, when the cup-shaped rotating outer toothed wheel 2 is bent to engage with the fixed inner toothed wheel 1-1 by the rotation of the wave generator 6, the flexibility is provided. The cylindrical gear forming portion 2-2 can be easily bent without lengthening the cylindrical portion to ensure the size, so that there is an effect that size reduction and size reduction can be realized without impairing the engagement accuracy of the gear.

[0006]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a cross-sectional view of an essential part showing an embodiment according to the present invention.
The cutout portions 2-4 and 2-5 are formed on the outer peripheral edge of the disc-shaped holding bottom surface portion 2-3 of the external gear tooth 2 having flexibility as compared with the configuration according to the conventional technique shown in FIG. Only the points differ. 2 and 3 are a cross-sectional view and a front view seen from the bottom side of the external gear wheel shown in the example.

As shown in the front view of FIG. 3, a bottom surface corresponding to a joint between the cylindrical gear forming portion 2-2 of the cup-shaped outer rotating toothed wheel 2 and the disc-shaped holding bottom portion 2-3. On the outer peripheral edge,
In this example, six T-shaped cutouts 2-5 and six circumferentially extending elongated cutouts 2-4 are formed substantially evenly. As is clear with reference to FIG. 1, the plurality of cutout portions facilitates bending of the outer toothed wheel forming cylindrical portion 2-2 when the wave generator 6 turns by reducing the rigidity of the joint. To do.

[0008]

The speed reducer according to the present invention can obtain the required flexibility without extending the length of the outer toothed wheel having flexibility without increasing the cost, so that the same transmission can be achieved. Approximately 2/3 in length compared to prior art speed reducers with torque
It has the effect of realizing a small reduction gear of the order of magnitude.

[Brief description of drawings]

FIG. 1 is a sectional view of an essential part of an example of a speed reducer according to the present invention.

FIG. 2 is a cross-sectional view of the flexible external ratchet wheel of the example of FIG.

FIG. 3 is a front view of the example external gear wheel shown in FIG. 2 viewed from the bottom side.

FIG. 4 is a cross-sectional view of essential parts of an example of a speed reducer according to a conventional technique.

FIG. 5 is a cross-sectional view of the flexible external ratchet wheel of the example of FIG.

[Explanation of symbols]

 1 Casing with Inner Gears Formed on Inner Circumferential Surface of Cylindrical Section 1-1 Inner Teeth of Fixed Side Inner Gears 2 Flexible Rotating Outer Gears 2-1 Outside Outer Rotating Gears Teeth 2-2 Cylindrical portion forming external teeth 2-3 Disc-shaped holding bottom surface portion 2-4 Thin cutting portion extending in the circumferential direction 2-5 T-shaped cutting portion 3 Output shaft 4 Input shaft 5 Planetary gear 6 Wave generator

Claims (4)

[Claims] 1. A fixed-side internal toothed wheel having internal teeth and an external tooth having the same number of modules as the fixed-side internal toothed wheel and a small number of teeth are formed on an outer peripheral surface of a flexible cylindrical portion. A reduction gear device that includes a so-called harmonic drive mechanism composed of a rotation-side external toothed wheel, and in which the input shaft and the output shaft can be arranged coaxially, the rotation-side external toothed wheel having flexibility of the harmonic drive mechanism is The cylindrical gear forming portion and the disc-shaped holding bottom portion form an integral cup shape, and a plurality of cutting portions extending in the circumferential direction are arranged substantially evenly in the vicinity of the outer peripheral edge of the disc-shaped bottom portion. A speed reducer characterized by that. 2. A plurality of cutting portions near the outer peripheral edge of the disk-shaped bottom surface portion of a flexible rotating outer toothed wheel, wherein cutting portions extending in the circumferential direction and T-shaped cutting portions are alternately arranged. The reduction gear transmission according to claim 1, wherein the reduction gear transmission is provided. 3. A plurality of cutouts in the vicinity of the outer peripheral edge of the disc-shaped bottom surface portion of the flexible rotating outer toothed wheel are holes penetrating in the axial direction. The speed reducer according to 2. 4. A plurality of cutouts in the vicinity of the outer peripheral edge of the disk-shaped bottom surface portion of a flexible rotating outer toothed wheel, and a blind-shaped hole having a thin film portion at one end in the axial direction. The reduction gear transmission according to claim 1, wherein