KR102133443B1 - Harmonic reducer - Google Patents

Abstract

The present invention relates to a harmonic speed reducer, is formed in a ring shape, a circular spline with internal teeth formed on the inner peripheral surface; An outer tooth is formed on an outer circumferential surface to engage the inner tooth of the circular spline, and a flex spline is formed; And a wave generator that fits into the hollow of the flex spline and is formed in a non-circular shape, such that a part of the external teeth engages the internal teeth. Including, the wave generator includes a long axis portion that makes the outer circumferential surface of the flex spline closest to the inner circumferential surface of the circular spline, and a shorter portion that makes it the most distant, and the inner tooth and the outer tooth, and the outer tooth located in the long axis portion It characterized in that the inner teeth are formed to be spaced apart from each other. Therefore, the engagement ratio can be increased, and the torque transmission rate can be further increased.

Description

Harmonic reducer {HARMONIC REDUCER}

The present invention relates to a reducer, and more particularly to a harmonic reducer.

Harmonic reducers (harmonic reducers) are a type of high-precision reducer that implements deceleration by using dimensional differences between a flex spline and a circular spline that are shape-deformed by waves generated by a wave generator. This harmonic reducer is used in an industrial field requiring a precise reduction ratio because of its small size, light weight, high reduction ratio, large transmission torque, and small backlash.

Generally, the harmonic reducer is composed of a wave generator, a flex spline, and a circular spline. The flex spline is deformed by the wave generated by the wave generator to perform harmonic motion (harmonic motion), so that some teeth of the flex spline and some teeth of the circular spline mesh with each other. Because the difference between the dimension (齒數) of the flex spline and the dimension (齒數) of the circular spline differs slightly from that of the flex spline, a reduction gear having a relatively large reduction ratio can be implemented due to the difference in the dimensions.

As a typical harmonic reducer, a harmonic reducer of the type with a circular spline in the shape of a cup or a "silk hat" is known.

1 is an exploded perspective view of a conventional harmonic reducer, and FIG. 2 is a cross-sectional view showing a state in which the opening of the flex spline of FIG. 1 is bent in an elliptical shape, wherein (a) is the state before deformation and (b) is the long axis of the ellipse. A cross section including a (major axis), (c) is a cross section including a minor axis, and FIG. 2 shows a “silk hat” shaped flex spline as a broken line.

As shown in these drawings, the conventional harmonic reducer 1 includes a ring-shaped circular spline 2 and a cup-shaped flex spline 3 arranged concentrically inside the circular spline 2. , A wave generator 4 having an elliptical contour inserted into the flex spline 3.

The cup-shaped flexible flex spline 3 has a cylindrical body 31, a ring-shaped diaphragm 32 continuous at one end thereof, and a ring-shaped boss integrally formed at the center of the diaphragm 32 (33; boss) and an outer tooth 35 formed on the outer circumferential surface of the opening 34 of the body 31.

The diaphragm 32A of the "silk hat" shaped flex spline 3A is an annular plate extending radially outward, as shown by the broken line in FIG. 2. An annular boss 33A is integrally formed along the outer circumferential edge of the diaphragm 32A.

The wave generator 4 is provided with an elliptical rigid cam plate 41 and a wave bearing 42 fitted to the outer circumferential surface of the cam plate 41.

The wave bearing 42 is composed of an inner race 42a, an outer race 42b, and a plurality of bearing balls 42c electrically mounted between the inner and outer races. . The inner and outer races 42a, 42b are flexible.

The flex spline 3 can be bent in an elliptical shape by the wave generator 4, and the outer teeth 35 of the flex spline 3 located on the elliptical long axis 3a are of the circular spline 2. It engages the corresponding part of the inner tooth 21.

That is, only the corresponding part of the outer tooth 35 of the flex spline 3 and the inner tooth 21 of the circular spline 2 positioned on the elliptical long axis 3a is engaged, and the tooth located at the short axis 3b ( 35, 31) are spaced apart from each other so that they do not mesh. As described above, the ratio of the engaging teeth to the total number of teeth is referred to as the engaging ratio. The higher the engaging ratio, the better the load transfer force, and the smaller the size of the individual teeth, which is advantageous for small and light weight.

As described above, in order to increase the intermeshing rate, there have been many researches and developments in the past, but there is a limit to raising the intermeshing rate to a certain degree.

1. U.S. Patent Publication No. 5,485,766 (released on January 23, 1996) 2. US Patent Publication No. 4,823,638 (published April 25, 1989) 3. Japanese Patent Publication No. 3132777 (released on 24 November 2000)

An object of the present invention devised in view of the above points is to provide a harmonic reducer capable of increasing the engagement ratio and increasing the power transmission effect.

In order to achieve the above object, the present invention is formed in a ring shape, a circular spline with an inner tooth formed on an inner peripheral surface; An outer tooth is formed on an outer circumferential surface to engage the inner tooth of the circular spline, and a flex spline is formed; And a wave generator that fits into the hollow of the flex spline and is formed in a non-circular shape so that a part of the tooth engages the inner tooth. The wave generator includes an outer peripheral surface of the flex spline on the inner peripheral surface of the circular spline. It provides a harmonic speed reducer, characterized in that it comprises a long axis portion to be closest and the shortest portion to be furthest away, and the inner tooth and the outer tooth are positioned such that the outer tooth and the inner tooth located in the long shaft portion are spaced apart from each other.

It is preferable that the inner teeth and the outer teeth are engaged with each other symmetrically with respect to the long axis in a force transmission region adjacent to the long axis.

The flex spline, one end is an opening, the other end is coupled with a coupling plate, and the force transmission region in which the inner tooth and the outer teeth are engaged, the more the direction toward the coupling plate from the opening, the longer the shaft portion to the shorter portion. What is formed to move is effective.

It is preferable that the pitch circle diameter of the flex spline is smaller than the pitch circle diameter of the circular spline.

According to the problem solving means of the present invention as described above, it is possible to expect a variety of effects, including the following. However, the present invention is not established when all of the following effects are exerted.

An embodiment of the present invention can provide a harmonic reducer having a high engagement ratio and a small angle transmission error.

In addition, in the case of a cup-type or silk-hat type flex spline, not only does not cause interference to the external teeth formed in the width direction, but also the external teeth and internal teeth are driven in engagement across the entire width direction, so power transmission efficiency is high.

1 is an exploded perspective view of a conventional harmonic reducer
FIG. 2 is a cross-sectional view showing a state in which the opening of the flex line of FIG. 1 is bent in an elliptical shape.
3 is a front view of a harmonic reducer according to the first embodiment of the present invention
Figure 4 is an enlarged front view of the external tooth of Figure 3
5 is a view showing the movement trajectory of the flex spline tooth of FIG. 4 according to the rotation of the elliptical wave generator of FIG. 3;
6A and 6B are front views showing the engagement of the external and internal teeth according to the change of the pitch circle.
7 is a side cross-sectional view of the flex spline of FIG. 5
8 is a conceptual view showing a movement trajectory of the external tooth portion A of FIG. 7;
FIG. 9 is a conceptual view showing a movement trajectory of the external teeth of part B of FIG. 7.
FIG. 10 is a conceptual view showing a movement trajectory of the C part external tooth of FIG. 7;

Hereinafter, a harmonic reducer according to an embodiment of the present invention will be described in more detail with reference to the accompanying drawings.

3 is a front view of a harmonic reducer according to an embodiment of the present invention.

As shown in FIG. 3, the harmonic reducer according to the embodiment of the present invention is formed in a ring shape, and the circular spline 100 having an inner tooth 110 formed on an inner circumferential surface, and the inner tooth 110 of the circular spline The outer tooth 210 is formed on the outer circumferential surface, and is fitted into the hollow of the flex spline 200 having a hollow and the flex spline 200, and is formed in a non-circular shape so that a part of the outer tooth engages the inner tooth. It includes a wave generator 300.

The wave generator 300 includes an elliptical rigid cam plate 310 and a wave bearing 320 fitted to the outer circumferential surface of the cam plate 310. The wave generator 300 includes a long axis portion 301 that allows the outer circumferential surface of the flex spline to be closest to the inner circumferential surface of the circular spline 100 and a shortened portion 302 that is farthest away.

The circular spline 100 is formed in a circular ring shape as described above, and an inner tooth 110 is formed on an inner peripheral surface.

The flex spline 200 may be formed of a cup-shaped flexible metal material, or may be formed in various shapes such as a “silk hat” shape or a circular band shape formed as a dotted line in FIG. 2. On the inner circumferential surface of the flex spline 200, an outer tooth 210 is formed to engage the inner tooth 110.

Since there is a slight difference between the dimension 齒數 of the external tooth 210 and the dimension 가 of the internal tooth 110, a reducer having a relatively large reduction ratio can be implemented.

4 is an enlarged front view of the external tooth of FIG. 3.

The external tooth 210 is formed in a symmetrical shape on the left and right sides based on the center line 214 of the tooth thickness, that is, a portion fixed to the flex spline 220, that is, a tooth root portion curved portion 213 formed of a curve adjacent to the tooth root of the outer tooth 210 ), a tooth-shaped curved portion 211 located at a region at the tip of the external tooth 210, and a side portion 212 connecting the tooth-shaped curved portion 213 and the tooth-shaped curved portion 211.

The curved end portion 211 is formed in a symmetrical shape as well as in a left-right symmetrical shape based on the tooth thickness center line 214 of the tooth. That is, this end of the curved portion 211 It includes a left distal end curved portion 211a located on the left side and a right distal end curved portion 211b located on the right side based on the tooth thickness center line 214, and left distal end curved portion 211a and right distal end curved portion 211b. Is formed so as to form part of one circle based on the center point 211c.

The radius r of the tip curve is preferably 80% or more and less than 100% of a value obtained by dividing the circumference P of the pitch circle of the flex spline by the number of teeth of the flex spline.

At a point where a straight line forming the side portion 212 and an arc forming the two-end curved portion 211 contact, the side portion and the two-end curved portion are connected. That is, the straight line forming the side portion 212 becomes the tangent of the arc forming the curved portion 211 of the end. In this way, the curved portion 211 and the side portion 212 are formed in a tangential line, so that a rapid change in inclination is eliminated. It is preferable that a tangential relationship is also formed between the root portion curved portion 211 and the side portion 212.

The angle θ between the side portion and the centerline of the tooth thickness is formed at an angle of 30 degrees or less and 3 degrees or more.

FIG. 5 is a view showing a movement trajectory of the flex spline tooth of FIG. 4 according to the rotation of the elliptical wave generator of FIG. 3.

As shown in FIG. 5, the tooth shape of the inner tooth 110 of the circular spline is the maximum formed by the outer line of the outer tooth 210 according to the movement trajectory of the outer tooth 210 generated by the wave generator 310. It is formed by connecting the outer line. In addition, when the point where the outermost line meets is an inflection point having a different slope, it is preferable that the tooth shape 110 of the internal teeth is curved by connecting an inflection point where each outermost line meets. That is, when the outermost line is continuously shown, it is formed in a smooth curve like the shape of the inner tooth 110 in FIG. 5, but since the position of the inner tooth cannot be continuously displayed, it is not possible between the outermost edges 120. The inflection point 121 is formed as shown in FIG. 5. At this time, the inflection point is curved, and correction is performed in the same manner as the shape of the inner tooth 110 of FIG. 4.

As described above, by forming the tooth shape of the internal teeth as the outermost line of the movement trajectory of the external teeth, the tooth root side hyoid curve portion 111 of the internal tooth bone is formed in an arc and is formed to mesh with the tooth-end curved portion 211. . When formed in the above-described method, the inner tooth and the outer tooth are formed of circular arcs interlocking with each other, and the inner tooth and the outer tooth located at the longest axis of the wave generator mesh with each other, thereby reducing vertical movement in the long axis direction of the wave generator, resulting in durability and vibration. There is an effect of reducing this. When the inner tooth and the outer tooth are formed in this way, as shown in FIG. 6A, the pitch circles PF and PC of the tooth shape of the outer tooth 210 and the inner tooth 110 are the same.

However, as shown in the enlarged view of FIG. 3, the inner teeth 110 and the outer teeth 210 adjacent to the long axis portion 301 are completely engaged with each other, but the amount of engagement is reduced while facing the short axis portion 302. That is, since the inner teeth and the outer teeth are centered around the long axis, the strain is likely to occur when a load is applied, an angle transmission error may occur, and the inner teeth 110 and the outer teeth 210 engage. There is a big limit to increasing the number.

There are various other methods of designing the tooth shape of the external tooth and internal tooth, and the present invention is not limited to the above-described method.

Another feature of the embodiment of the present invention, as shown in Figure 6A, after forming the tooth shape of the outer tooth 210 and inner tooth 110 in the same state as the flex spline and the circular spline as above, Figure 6B As shown in the above, the diameter of the pitch circle PF of the flex spline is smaller than the diameter of the pitch circle PC of the circular spline. As described above, forming the pitch circle diameter (PF) of the flex spline smaller than the pitch circle diameter (PC) of the circular spline (including forming the pitch circle diameter (PC) of the circular spline larger than the pitch circle (PF) of the flex spline) 6 ), as shown in FIG. 6, a gap is generated between the inner tooth 110 and the outer tooth 210 located near the long axis portion 301, but the tooth between the outer tooth 210 is narrowed, thereby making the outer tooth The force transmission region (FR) in which the internal teeth and the internal teeth engage is spaced apart from the long axis portion (301). That is, the external teeth 210 and the internal teeth 110 located in the long axis portion 301 are spaced apart from each other, but are symmetrical with respect to the long axis in the force transmission region FR adjacent to the long axis portion 301. Interlocked. As a result, the force is distributed and the torque transmission rate is increased, rather than the force transmission region FR being concentrated in the long axis. Moreover, as a result of reducing the diameter of the pitch circle (PF) of the external tooth by 0.05%, it was confirmed that the engagement ratio also increased.

7 is a side cross-sectional view of the flex spline of FIG. 5.

As shown in FIG. 7, the flex spline is formed in a cup shape (or silk hat shape). Flex spline 200 is composed of a cylindrical body portion 220, one end of the body portion 220 is an opening 221, the other end is coupled to the coupling plate 230. The coupling plate 230 includes a disk-shaped diaphragm 231 and a boss 232 formed on the diaphragm 231.

As described above, when the flex spline is formed in a cup shape or a silk hat shape, the body portion 220 of the flex spline is based on the corner point 11 where the body portion 220 and the coupling plate 230 meet by the wave generator. You will exercise similar to the cantilever rotational movement. Accordingly, the external teeth 210 form different motion trajectories along the longitudinal direction shown in FIG. 7. The shouting located at the point A closest to the opening 221 performs more movement up and down, as shown in FIG. 8, and the shouting located at the intermediate point b performs the movement as shown in FIG. 9, and the coupling plate 230 The shouting located at the closest point, c, will exercise as shown in FIG. 10.

That is, the trajectory of the external tooth shown in FIG. 10 is low and high, but the horizontal movement width of the external tooth is wide, and the trajectory of the external tooth shown in FIG. 8 is high, but the horizontal movement width is narrow. Therefore, the shape of the inner tooth 110 which does not cause interference with the same outer tooth 210 is different. That is, when the inner tooth is formed in accordance with FIG. 8, interference occurs in the width direction of the inner tooth, and when the inner tooth is formed in accordance with FIG. 10, the inner tooth in the portions of FIGS. 8 and 9 is formed. Interference occurs in the vertical direction of.

As a method of resolving this, a method of forming internal teeth so as not to interfere with all parts may be used. However, when the width or height of the inner tooth is formed to be the same so as not to cause interference in all parts, there is a problem that the engagement rate between the inner tooth and the outer tooth is lowered.

In the case of the embodiment of the present invention, when the pitch circle of the flex spline is reduced to the point C close to the coupling plate, at the point A close to the opening, the force transmission region FR is formed at a position adjacent to the long axis portion 301, The more toward the bonding plate, the pitch circle of the flex spline is automatically reduced, so that the force transmission region FR moves toward the shortening portion 302. That is, the force transmission region FR in which the inner tooth and the outer tooth engage is formed to move from the long axis portion 301 to the short axis portion 302 as the opening plate faces the coupling plate.

By forming in this way, not only does not interfere with the external teeth formed in the width direction even in the case of the cup-type or silk-hat type flex spline, and the external teeth and internal teeth are engaged and driven across the entire width direction, so power transmission efficiency is improved. high.

The above is merely a description of some of the preferred embodiments that can be implemented by the present invention, and as is well known, the scope of the present invention should not be construed as being limited to the above embodiments, and the present invention described above. It will be said that both the technical idea and the technical idea together with the fundamental are included in the scope of the present invention.

110: internal tooth 111: tooth root side hyoid curve
100: circular spline 120: outermost line
200: flex spline 210: tooth
213: curved part of the root part 211: curved part of the tooth end
212: side portion 214: center line
211a: left distal end curved portion 211b: right distal end curved portion
211c: center point 220: torso
221: opening 230: bonding plate
231: diaphragm 232: boss
240: central axis 300: wave generator
310: cam plate 320: wave bearing

Claims (4)

A circular spline formed in a ring shape and having internal teeth formed on an inner peripheral surface;
An outer circumference is formed on an outer circumferential surface to engage the inner teeth of the circular spline, and a flex spline is formed; And
A wave generator that fits into the hollow of the flex spline and is formed in a non-circular shape such that a portion of the external teeth engages the internal teeth;
Including,
The wave generator includes a long axis portion that makes the outer circumferential surface of the flex spline closest to the inner circumferential surface of the circular spline, and a shorter portion that makes it the most distant.
The internal teeth and the external teeth,
The external teeth and the internal teeth located in the long axis portion are formed to be spaced apart from each other, so that they are not completely engaged with each other, and the external teeth and the internal teeth are engaged with each other in a force transmission region adjacent to the major axis portion,
A harmonic reducer, characterized in that, in a circumferential direction in the force transmission region, the inner tooth engages with the inner tooth on a side facing the long axis of the outer tooth, and does not engage with the inner tooth on a side facing the short axis of the outer tooth.
According to claim 1,
The internal teeth and the external teeth,
Harmonic speed reducer, characterized in that engaged with each other symmetrically with respect to the long axis in the force transmission region.
According to claim 2,
The flex spline, one end is an open opening, the other end is coupled to the coupling plate,
The harmonic speed reducer according to claim 1, wherein the force transmission region in which the inner tooth and the outer tooth engage with each other is formed to move from the long axis portion to the short axis portion as it faces the malleable plate in the opening portion.
The method according to any one of claims 1 to 3,
The pitch splice diameter of the flex spline is smaller than the pitch splice diameter of the circular spline.

Images