KR102033409B1 - Wave generator for reducer of harmonic drive structure - Google Patents

Abstract

According to the present invention, a wave generator for a reducer of a harmonic drive structure is disclosed. According to an embodiment of the present invention, the reducer of a harmonic drive structure comprises: a ring-shaped circular spline; a flex spline installed inside the circular spline and engaged with at least three teeth formed on an inner circumferential surface of the circular spline to rotate; and a wave generator installed insideeee the flex spline, and including a circular cam plate, wherein a protrusion is formed in at least three points of an outer circumferential surface of the circular cam plate for the protrusion formed on an outer circumferential surface of the cam plate to elastically deform at least three points at an internal side of the flex spline.

Description

WAVE GENERATOR FOR REDUCER OF HARMONIC DRIVE STRUCTURE}

The present invention relates to a harmonic drive, and more particularly to a wave generator for a reducer of a harmonic drive structure.

Harmonic drives are widely used in industrial robots, NC machine tools, and semiconductor manufacturing equipment. They are small, light weight, have high transmission torque, high reduction ratios, extremely low backlash, and excellent angle transmission and rotation. .

Conventional harmonic drives consist of wave generators, flex splines, and circular splines. The wave generator includes a plug therein, and the plug has an elliptic shape and is connected to the input shaft of the drive system to transmit rotational movement, and elastically deforms the thin cup-shaped flex spline by the shape of the plug of the wave generator. The flex spline is responsible for causing the deceleration rotation in the opposite direction.

The wave generator rotates by the rotational force from the input shaft of the drive system, and the flex spline changes to the shape of the plug, i.e., elliptical, so that its position of engagement with the circular spline in the long axis portion of the ellipse moves sequentially. When the wave generator rotates one full revolution, the flex spline rotates in the opposite direction by the number of teeth, and due to this rotation in the opposite direction, deceleration occurs.

Harmonic drives operate with this symmetrical bite structure in the elliptical long axis, and this problem often occurs even if the meshing state of the ratcheting shock is excessively assembled or the external force is momentarily disengaged.

Publication No. 10-2011-0112027, published October 12, 2011

SUMMARY OF THE INVENTION An object of the present invention is to provide a wave generator for a reducer of a harmonic drive structure, which has a structure in which teeth engage and rotate in three or more positions at the same time.

However, the object of the present invention is not limited to the above objects, and may be variously expanded within a range without departing from the spirit and scope of the present invention.

In order to achieve the object of the present invention, a harmonic drive structure according to one aspect of the present invention, the reducer is a ring-shaped circular spline; A flex spline installed inside the circular spline and engaged with at least three teeth formed on an inner circumferential surface of the circular spline; And a protruding portion provided on the inner side of the flex spline, the cam plate having a circular shape, and protruding portions formed on at least three points of the outer circumferential surface of the circular cam plate, and the protruding portion formed on the outer circumferential surface of the cam plate at least inside the flex spline. And a wave generator that elastically deforms three points.

The wave generator may further include a cam plate including a protruding portion formed at at least three points of a circular central portion and an outer circumferential surface of the central portion; It may include a ball bearing formed on the outside to surround the cam plate, the ball bearing elastically deformed by the protrusion formed on the outer peripheral surface of the cam plate.

In addition, the radius R2 of the different circles including each of the protrusions formed at the at least three points are all the same, and the relationship between the radius R2 and the radius R1 of the center portion is defined by the formula (R2 = k × R1), k is a proportional constant with a value within the range of 0.6 to 0.8.

Further, the proportional constant k is 0.7.

In addition, the protrusions formed at the at least three points may be formed at regular intervals about the rotation axis of the wave generator.

In addition, the flex spline may have teeth formed on an outer circumferential surface thereof, and may be elastically deformed by the shape of the wave generator so that the teeth of the elastically deformed portion may be engaged with the teeth formed on the inner circumferential surface of the circular spline.

As described above, the present invention includes three or more protrusions at regular intervals on the outer circumferential surface of the circular wave generator, and the teeth of the flex spline in which the three or more protrusions are positioned are engaged with the teeth of the circular spline at the same time. This can help prevent this condition.

In addition, the present invention can significantly increase its bite rate when compared with the class reduction gear, and can greatly improve the speed reduction performance items such as rated torque and peak torque.

However, the effects of the present invention are not limited to the above effects, and may be variously extended within a range without departing from the spirit and scope of the present invention.

1 is a view showing a harmonic drive according to an embodiment of the present invention.
2A to 2C are views illustrating the shape of the wave generator shown in FIG. 1.
3 is a diagram illustrating a state in which the wave generator of FIG. 1 is installed on a flex spline.
FIG. 4 is a view illustrating a state in which the flex spline shown in FIG. 3 is installed on the circular spline.
5 is a view for explaining the driving principle of the reducer according to an embodiment of the present invention.

DETAILED DESCRIPTION The following detailed description of the invention refers to the accompanying drawings that show, by way of illustration, specific embodiments in which the invention may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the invention. It should be understood that the various embodiments of the present invention are different but need not be mutually exclusive. For example, certain shapes, structures, and characteristics described herein may be embodied in other embodiments without departing from the spirit and scope of the invention with respect to one embodiment. In addition, it is to be understood that the location or arrangement of individual components within each disclosed embodiment may be changed without departing from the spirit and scope of the invention. The following detailed description, therefore, is not to be taken in a limiting sense, and the scope of the present invention, if properly described, is defined only by the appended claims, along with the full range of equivalents to which such claims are entitled. Like reference numerals in the drawings refer to the same or similar functions throughout the several aspects.

Hereinafter, a wave generator for a reducer of a harmonic drive structure according to an exemplary embodiment of the present invention will be described with reference to the accompanying drawings. In particular, the present invention proposes a new structure in which three or more protrusions are provided on the outer circumferential surface of the circular wave generator at regular intervals, and the teeth of the flex spline in which the three or more protrusions are positioned are engaged with the teeth of the circular spline at the same time. .

1 is a view showing a harmonic drive according to an embodiment of the present invention, Figures 2a to 2c is a view showing the shape of the wave generator shown in FIG.

Referring to FIG. 1, a harmonic drive according to an embodiment of the present invention may include a wave generator 100, a flex spline 200, and a circular spline 300. have.

The wave generator 100 may be formed in a triangular shape as a whole, and may be connected to an input shaft and rotate. The wave generator 100 is installed inside the flex spline 200 to elastically deform the flex spline 200 so that the flex spline 200 causes a slow rotational motion in the opposite direction.

2A to 2B, the wave generator 100 according to an embodiment of the present invention has a ball bearing 120 formed outside the cam plate 110 and the cam plate 110 to surround the cam plate 110. ).

The cam plate 110 has crescent-shaped protrusions 110a, 110b, and 110c formed at at least three points on the circular center portion 111 and the outer circumferential surface of the central portion 111, and can be connected to the input shaft and rotate. . The crescent-shaped protrusions 110a, 110b, and 110c are formed at regular intervals at at least three points to correspond to vertices of a triangle as a whole. The cam plate 110 may be formed of a rigid material that does not deform in shape.

The ball bearing 120 may be formed on the outside such that a plurality of balls 130 surround the cam plate 110 in a ring shape. The inner side of the ball bearing 120 may contact the outer side of the cam plate 110, and a portion of the outer side of the ball bearing 120 may contact the inner portion of the flex spline 200.

Since the ball bearing 120 is elastically deformed by the shape of the cam plate 110, protrusions 120a, 120b and 120c may be formed on the outer circumferential surface corresponding to each of the protrusions 110a, 110b and 110c of the cam plate 110. . The protrusions 120a, 120b, and 120c formed at at least three points corresponding to the protrusions 110a, 110b, and 110c of the cam plate 110 may be formed at regular intervals and may correspond to vertices of a triangle as a whole.

The protrusions 120a, 120b, 120c of the ball bearing 120 elastically deform the flex spline 200 such that at least three points of the flex spline 200 contact the inside of the circular spline 300, and at three points in contact therewith. At the same time the teeth can be engaged.

As described above, since the crescent-shaped protrusion is formed at at least three points of the outer circumferential surface of the circular cam plate 110, the flex spline 200 and the circular spline 300 coupled thereto may be simultaneously engaged at three points. .

The flex spline 200 is formed in a cup shape, and the wave generator 100 may be installed inside. A tooth may be formed on an outer circumferential surface of the flex spline 200.

Referring to Figure 2c, each of the protrusions (110a, 110b, 110c) formed on the outer peripheral surface of the central portion 111 of the circular shape is included in three different circles to form part of the circle, the diameter of the three different circles All may be formed identically.

The radius R2 of the three circles including each of the protrusions 110a, 110b, and 110c is smaller than the radius R1 of the central portion 111 of the circular shape, and the relationship is defined as in Equation 1 below.

[Equation 1]

R2 = k × R1

Here, k is a proportional constant, which is within the range of 0.6 to 0.8, k = 0.7 is most preferred. When k <0.6, since the overall shape of the cam plate 110 is not a circular shape, the ball 130 is not smoothly moved, which may cause a problem in rotation. On the other hand, if k> 0.8, since the overall shape of the cam plate 110 is almost circular, there is a problem in that the portion where the teeth engage at three points is too wide.

3 is a diagram illustrating a state in which the wave generator of FIG. 1 is installed on a flex spline.

Referring to FIG. 3, the flex spline 200 may be formed of a metal elastic body, and a wave generator 100 may be installed therein to be elastically deformed by the shape of the wave generator 100.

Among the elastically deformed portions of the flex spline 200, the elastically deformed portions by the protrusions 120a, 120b, and 120c of the wave generator may contact the inner side of the circular spline 300 to engage the teeth to rotate the circular spline 300. have.

The circular spline 300 may be formed in a ring shape, and the flex spline 200 may be installed inside. The circular spline 300 may be formed of a rigid material that is not deformed in shape so that teeth engaging with the teeth of the flex spline 200 may be formed on an inner circumferential surface thereof.

The number of teeth formed on the inner circumferential surface of the circular spline 300 may be designed to be larger than the number of teeth formed on the outer circumferential surface of the flex spline 200 for the reduction ratio.

FIG. 4 is a view illustrating a state in which the flex spline shown in FIG. 3 is installed on the circular spline.

Referring to FIG. 4, the wave generator may be installed inside the circular spline having the ring shape so that the flex spline may be interlocked with at least three points A1, A2, and A3. The teeth formed on the outer circumferential surface of the flex spline elastically deformed by the shape of the wave generator can be engaged with the teeth formed on the inner circumferential surface of the circular spline.

The teeth formed on the outer circumferential surface of the flex spline are engaged with the teeth formed on the inner circumferential surface of the circular spline at three different points at regular intervals. Here, even this month state refers to a state in which the engagement thereof is driven to one side when causing the ratcheting phenomenon or assembling the parts by force. The ratcheting phenomenon refers to a state in which the engagement between the flex spline and the cooler spline is momentarily displaced, although the flex spline is not damaged when excessive shock torque is applied during operation.

5 is a view for explaining the driving principle of the reducer according to an embodiment of the present invention.

Referring to FIG. 5, (a) the flex spline 200 is elastically deformed by the wave generator 100, and teeth 210 positioned at three points are formed on the teeth 310 formed on the inner circumferential surface of the circular spline 300. Interlocking, and in other areas the teeth are completely separated.

(b) When the circular spline 300 is fixed and the wave generator 100 is rotated 90 degrees clockwise, the flex spline 200 elastically deforms and the engagement of the teeth with the circular spline 300 sequentially moves.

(c) When the wave generator 100 rotates clockwise by 180 degrees, the flex spline 200 moves counterclockwise.

(d) When the wave generator 100 rotates 360 degrees, the flex spline 200 moves counterclockwise. At this time, the flex spline 200 moves counterclockwise by the difference between the number of teeth of the flex spline 200 and the number of teeth of the circular spline 300.

Features, structures, effects, etc. described in the above embodiments are included in one embodiment of the present invention, and are not necessarily limited to one embodiment. Furthermore, the features, structures, effects, and the like illustrated in the embodiments may be combined or modified with respect to other embodiments by those skilled in the art to which the embodiments belong. Therefore, contents related to such combinations and modifications should be construed as being included in the scope of the present invention.

In addition, the above description has been made with reference to the embodiment, which is merely an example, and is not intended to limit the present invention. It will be appreciated that various modifications and applications are possible. For example, each component specifically shown in the embodiment can be modified. And differences relating to such modifications and applications will have to be construed as being included in the scope of the invention defined in the appended claims.

100: wave generator
110: campan
120: ball bearing
130: ball
200: flex spline
300: circular spline

Claims (6)

Ring-shaped circular splines;
A flex spline installed inside the circular spline and engaged with at least three teeth formed on an inner circumferential surface of the circular spline; And
A protruding portion provided on the inner side of the flex spline, the protruding portion being formed on at least three points of the outer circumferential surface of the circular cam plate, the protruding portion formed on the outer circumferential surface of the cam plate; A wave generator for elastically deforming the point;
Radius R2 of the different circles including each of the protrusions formed at the at least three points are all the same, and the relationship between the radius R2 and the radius R1 of the center portion is defined by the formula (R2 = k × R1), where k is 0.6 Reducer of harmonic drive structure, which is a proportional constant with a value in the range of ~ 0.8. The method of claim 1,
The wave generator,
A cam plate including a central portion of a circular shape and a protrusion formed at at least three points on an outer circumferential surface of the central portion;
And a ball bearing formed on an outer side to surround the cam plate and elastically deformed by a protrusion formed on an outer circumferential surface of the cam plate. delete delete The method of claim 1,
The protrusion formed at the at least three points is formed at regular intervals about the axis of rotation of the wave generator, reducer of the harmonic drive structure. The method of claim 1,
The flex spline has teeth formed on an outer circumferential surface thereof, and is elastically deformed by the shape of the wave generator so that the teeth of the elastically deformed portion mesh with and rotate with teeth formed on the inner circumferential surface of the circular spline.

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