WO2023153870A1

WO2023153870A1 - Harmonic reducer and power transmission system comprising same

Info

Publication number: WO2023153870A1
Application number: PCT/KR2023/002010
Authority: WO
Inventors: 박재흥; 유승빈; 김승연; 심재훈; 성은호
Original assignee: 서울대학교산학협력단
Priority date: 2022-02-14
Filing date: 2023-02-10
Publication date: 2023-08-17
Also published as: KR20230122350A; KR102605516B1

Abstract

A harmonic reducer according to one embodiment comprises: a wave generator that has a disk shape, has a groove portion formed along the outer circumference of the lower surface, and is configured to rotate around a first axis; a bearing member accommodated in the groove portion and including a bearing ball that is configured to be rotatable and displaceable on the basis of the rotation of the wave generator, and a cage that is configured to keep the bearing ball in the groove portion; a flexible flex spline contacting at least a portion of the bearing ball and configured to be rotatable about the first axis by means of the rotation and displacement, which are based on the rotation of the wave generator, of the bearing ball; and a circular spline having a disk shape and having an upper surface at least partially in contact with the outer circumferential portion of the lower surface of the flex spline.

Description

Harmonic reducer and power transmission system including the same

Embodiments of the present disclosure relate to a harmonic reducer and a power transmission system including the same. More specifically, by including a wave generator in which a groove is formed and a bearing ball accommodated in the groove, friction that may occur between the components (eg, the wave generator and the flex spline) is reduced, and based on the reduced friction It relates to a power transmission system including a harmonic reducer and a power transmission system that can increase efficiency by doing so.

As a reducer used in a conventional power transmission system or robot system, a harmonic reducer is used together with an RV reducer and a planetary gear. In particular, the harmonic reducer can obtain a reduced output by using the elasticity of metal, and can be smaller and lighter than conventional reducers (eg, gears). Based on these properties, harmonic reducers can be used in power systems with size and weight limitations.

In addition, the harmonic reducer can have the advantages of a high reduction ratio, high rotational precision, and zero backlash, so that it can be used in a precise power transmission system or robot joint system that requires a high reduction ratio, high rotational precision, and zero backlash.

Due to the characteristics of the above-described harmonic reducer, the harmonic reducer is widely used not only in industrial robot systems but also in walking robot systems. Since the robot joint is lighter in weight and easier to control as the volume is smaller, the harmonic reducer inserted into the robot joint needs to be lighter in weight and smaller in volume.

However, each component of the conventional harmonic reducer may have a generally cylindrical (cylindrical) housing. There was a disadvantage in that the volume of the conventional harmonic reducer increased due to each component having a cylindrical housing. In addition, the elliptical wave generator member of the conventional harmonic reducer has a structure in which deformation is continuously applied to bearing balls as well as a flex spline member for elastic deformation. Therefore, the life and accuracy of the bearing may be deteriorated. In addition, the wave generator of the existing harmonic reducer has disadvantages in that it is difficult to design a profile and the manufacturing process is complicated.

In order for the harmonic reducer to be applied to a power transmission system and a robot system that are being recently reduced in weight and precision, the harmonic reducer needs to be lightweight and have a small volume. In addition, it is necessary to increase the efficiency of the harmonic reducer by reducing the friction between each component.

The present disclosure provides a harmonic reducer according to an embodiment.

The harmonic reducer according to an embodiment aims to solve the disadvantages of the conventional harmonic reducer. More specifically, the harmonic reducer according to an embodiment improves the shape of the component to a disk shape, and the depth of the formed groove changes along the outer circumference of the lower surface, so that the flex spline and the circular spline at a specific point are engaged designed to control

The harmonic reducer according to the exemplary embodiments can be reduced in weight and reduced in volume based on a disk-shaped wave generator. Therefore, it is possible to solve the disadvantages of the conventional harmonic reducer having a large volume and heavy weight due to the cylindrical component.

In addition, the harmonic reducer according to an embodiment includes a wave generator in which a groove is formed and a bearing ball accommodated in the groove. By pressurizing the flex spline with rolling friction using bearing balls, it is possible to reduce friction that may occur between components of the harmonic reducer, and increase efficiency based on the reduced friction.

In addition, by separating the elastic deformation part and the power transmission part of the flex spline of the harmonic reducer according to an embodiment, manufacturing cost can be lowered and energy required for elastic deformation can be reduced. Based on the separable flex spline, the efficiency can be increased by preventing stress concentration that may occur in the flex spline and reducing the energy required for elastic deformation.

The present disclosure provides a power transmission system according to an embodiment.

A power transmission system according to an embodiment and a robot system according to an embodiment include a harmonic reducer according to an embodiment. Accordingly, the power transmission system according to one embodiment and the robot system according to one embodiment have a task to solve the disadvantages that may occur by including a conventional harmonic reducer. Since the disadvantages of the conventional harmonic reducer are as described above, a detailed description in the overlapping range will be omitted.

As a means for solving the above problems, a harmonic reducer according to an embodiment of the present disclosure is provided.

A harmonic reducer according to an embodiment has a disk shape, has a groove portion formed along an outer circumference of a lower surface, and includes a wave generator configured to rotate around a first axis; a bearing member including a bearing ball accommodated in the groove and configured to be rotatable and displaceable based on rotation of the wave generator, and a cage configured to hold the bearing ball in the groove; flex splines that contact at least a portion of the bearing balls, are configured to be rotatable about the first axis by rotation and displacement of the bearing balls based on rotation of the wave generator, and are flexible; and circular splines having an upper surface at least partially in contact with an outer circumferential portion of a lower surface of the flex spline and having a disk shape.

The vertical depth of the groove portion in which the bearing ball is accommodated changes along the outer circumference of the lower surface of the wave generator, and when the wave generator rotates, the bearing ball moves in the vertical direction based on the vertical depth change of the groove portion. can be transformed into

When the wave generator rotates, a portion of the flex spline is pressed from the bearing ball displaced in the up and down direction, and as a portion of the flex spline is pressed in the up and down direction by the bearing ball, the lower part of the flex spline An outer circumferential portion of the surface may contact at least a portion of the upper surface of the circular spline.

A first gear portion is formed along an outer circumference of the lower surface of the flex spline, a second gear portion configured to correspond to the first gear portion is formed on the upper surface of the circular spline, and as the wave generator rotates, The first gear unit and the second gear unit may be engaged with each other at a variable point.

The number of first gears of the first gear part and the number of second gears of the second gear part may be different from each other.

The bearing ball may include a plurality of ball members, and the cage may have a plurality of recessed portions, each of which is disposed and configured to retain the plurality of ball members in the groove portion.

As a means for solving the problem, a harmonic reducer according to an embodiment of the present disclosure is provided.

A harmonic reducer according to an embodiment includes a wave generator having a disk shape and configured to rotate around a first axis; a bearing member configured to rotate and displace based on rotation of the wave generator; flex splines contacting at least a portion of the bearing member and configured to be rotatable about the first axis by rotation and displacement of the bearing member based on rotation of the wave generator, the flex spline being flexible; and a circular spline having an upper surface at least partially in contact with an outer circumferential portion of a lower surface of the flex spline, configured to be rotatable about the first axis by contact with the flex spline, and having a disc shape. However, the flex spline is in contact with at least a portion of the bearing member, the elastic deformation portion is pressed and deformed by the rotation and displacement of the bearing member; and a power transmission unit coupled to the elastic deformation unit and configured to transmit power to the outside.

The elastic deformation part and the power transmission part may be separable from each other.

The elastically deformable portion has a disk shape, and a through hole opened in a vertical direction is formed at the center of the disk shape of the elastically deformable portion, and when the elastically deformable portion and the power transmission unit are coupled, the power transmission unit forms the through hole of the elastically deformable portion. It can be arranged to pass through.

The power transmission unit may include a first power transmission unit coupled to an upper side of the elastic deformation unit; and a second power transmission unit coupled to a lower side of the elastic deformation unit.

As a means for solving the problems, a power transmission system according to an embodiment of the present disclosure is provided.

The power transmission system includes a harmonic reducer according to an embodiment; a power unit configured to generate power and transmit the generated power to the harmonic reducer; and an output unit configured to receive power decelerated by the harmonic reducer.

The harmonic reducer according to an embodiment can be lightweight and have a reduced volume.

The harmonic reducer according to an embodiment is pressurized by rolling friction using bearing balls, thereby reducing friction that may occur between components of the harmonic reducer and increasing efficiency based on the reduced friction.

The harmonic reducer according to an embodiment may increase efficiency by reducing the amount of energy required for elastic deformation based on the separable flex spline.

1 is a perspective view when a harmonic reducer is coupled according to an embodiment.

Figure 2 is a longitudinal cross-sectional view of the harmonic reducer shown in Figure 1;

FIG. 3 is a perspective view of the wave generator shown in FIG. 2 viewed from a lower side.

FIG. 4 is a schematic diagram schematically showing the depth of a groove formed in the wave generator in FIG. 3 .

FIG. 5 is a cross-sectional perspective view of the wave generator and bearing member shown in FIG. 2 viewed from the lower side.

FIG. 6 is a schematic diagram schematically showing the height of the ball bearing of the bearing member according to the depth of the groove in FIG. 5 .

7 is a diagram showing the operation of the harmonic reducer according to an embodiment.

8 is a schematic diagram schematically illustrating an enlarged portion A in FIG. 7 .

9 is a perspective view when the flex spline shown in FIG. 2 is coupled;

10 is an exploded perspective view of the flex spline of FIG. 9 .

11 is a schematic diagram of a power transmission system according to an embodiment.

Embodiments of the present disclosure are illustrated for the purpose of explaining the technical idea of the present disclosure. The scope of rights according to the present disclosure is not limited to the specific description of the embodiments or these embodiments presented below.

All technical terms and scientific terms used in this disclosure have meanings commonly understood by those of ordinary skill in the art to which this disclosure belongs, unless otherwise defined. All terms used in this disclosure are selected for the purpose of more clearly describing the disclosure and are not selected to limit the scope of rights according to the disclosure.

Expressions such as "comprising", "including", "having", etc. used in this disclosure are open-ended terms that imply the possibility of including other embodiments, unless otherwise stated in the phrase or sentence in which the expression is included. (open-ended terms).

In the present disclosure, referring to FIG. 2, "upper and lower direction" may refer to a direction in which the wave generator 120 and the bearing member 140 are disposed side by side, and "upper", "upper", "upper", etc. It may mean a direction in which the wave generator 120 is viewed with respect to the member 140, and "down", "down", "down", etc. refer to the above-described "up", "upper", and "upper" directions. can mean the opposite direction.

Expressions in the singular form described in this disclosure may include plural meanings unless otherwise stated, and this applies equally to expressions in the singular form described in the claims.

Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. In the accompanying drawings, identical or corresponding elements are given the same reference numerals. In addition, in the description of the following embodiments, overlapping descriptions of the same or corresponding components may be omitted. However, omission of a description of a component does not intend that such a component is not included in an embodiment.

1 is a perspective view of a combined harmonic reducer 100 according to an embodiment. FIG. 2 is a longitudinal cross-sectional view of the harmonic reducer 100 shown in FIG. 1 .

Referring to FIGS. 1 and 2 , the harmonic reducer 100 according to an embodiment may include a wave generator 120 having a disk shape.

The harmonic reducer 100 may include an upper housing 110 surrounding the wave generator 120 on the upper side of the wave generator 120 . The harmonic reducer 100 may include a first cylinder bearing 171 between the upper housing 110 and the wave generator 120 . The first cylinder bearing 171 is disposed between the upper housing 110 and the wave generator 120 so that the wave generator 120 can rotate without friction with respect to the upper housing 110 .

The wave generator 120 may be connected to a power unit (not shown). The wave generator 120 may rotate by power generated by a power unit. The power unit may be, for example, a motor. The wave generator 120 may rotate around a predetermined axis. A predetermined axis around which the wave generator 120 rotates is assumed to be the first axis X1 and will be described below. Here, the first axis X1 may be the same as an axis to which power generated by the power unit is transmitted.

A groove 130 may be formed along the outer circumference of the lower surface of the wave generator 120 . The groove 130 is a portion concavely recessed upward from the lower surface of the wave generator 120 and may have a predetermined depth. The depth of the groove 130 may vary along the outer circumference of the lower surface of the wave generator 120, and the depth of the groove 130 will be described in more detail with reference to FIGS. 3 and 4 below.

The harmonic reducer 100 according to an embodiment may include a bearing ball 141 accommodated in the groove 130 of the wave generator 120 . The bearing ball 141 may contact the wave generator 120 . The bearing ball 141 may be configured to be rotatable and displaceable based on the rotation of the wave generator 120 .

The harmonic reducer 100 according to one embodiment may include a cage 142 configured to retain the bearing balls 141 in the grooves 130 . The cage 142 may be attached to a lower surface of the wave generator 120 . Cage 142 may be ring-shaped. The cage 142 is attached to the outer circumference of the lower surface of the wave generator 120 to hold the bearing balls 141 in the grooves 130 and prevent the bearing balls 141 from being separated from the grooves 130. can

The harmonic reducer 100 according to one embodiment may include a flex spline 150 in contact with at least a portion of the bearing ball 141 . Flex spline 150 may be flexible. That is, the flex spline 150 may include a flexible material whose shape is partially changed by an external force. A portion of the flex spline 150 pressed by the bearing ball 141 may be deformed. For example, a predetermined portion of the flex spline 150 may be pressed downward by the bearing ball 141 and deformed downward.

The flex spline 150 may be configured to be rotatable about the first axis X1 by rotation and displacement of the bearing ball 141 based on the rotation of the wave generator 120 . That is, when the wave generator 120 rotates around the first axis X1, the flex spline 150 also rotates around the first axis X1.

The flex spline 150 may include an elastic deformable part 151 and a power transmission part 152 coupled to the elastic deformable part 151 .

The harmonic reducer 100 may include a second cylinder bearing 172 between the wave generator 120 and the flex spline 150 . The second cylinder bearing 172 may be disposed between the wave generator 120 and the flex spline 150 to allow the flex spline 150 to rotate at a speed different from that of the wave generator 120.

The harmonic reducer 100 may include a circular spline 160 having an upper surface at least partially in contact with an outer circumference of the lower surface of the flex spline 150 . For example, a contact portion may be formed along a predetermined circumference on an upper surface of the circular spline 160 . The circular spline 160 may have a disk shape.

The circular spline 160 may be a rigid body. The circular spline 160 may contact a portion of the flex spline 150 that is deformed by being pressed by the bearing ball 141 . In the harmonic reducer 100, the reduction ratio may be determined based on contact between the flex spline 150 and the circular spline 160. A detailed description of the power transmission mechanism according to the reduction ratio of the harmonic reducer 100 will be described in more detail below.

The harmonic reducer 100 may include a third cylinder bearing 173 between the flex spline 150 and the circular spline 160 . The third cylinder bearing 173 is disposed between the flex spline 150 and the circular spline 160 so that the flex spline 150 can rotate at a speed different from that of the circular spline 160.

FIG. 3 is a perspective view of the wave generator 120 shown in FIG. 2 viewed from the bottom. And, FIG. 4 is a schematic diagram schematically showing the depth of the groove 130 formed in the wave generator 120 in FIG. 3 .

Referring to FIGS. 3 and 4 , the groove 130 formed on the lower surface of the wave generator 120 may have a predetermined vertical depth so that the bearing ball 141 can be accommodated therein. That is, based on the vertical depth of the groove 130 , the bearing ball 141 may be accommodated in the groove 130 .

The vertical depth of the groove 130 may vary along the outer circumference of the lower surface of the wave generator 120 . The vertical depth of the groove 130 may be formed symmetrically. For example, a location having the largest vertical depth of the groove 130 (eg, d1 in FIG. 4 ) may be symmetrically positioned with respect to the center of the wave generator 120 . In addition, a location having the smallest vertical depth of the groove 130 (eg, d2 in FIG. 4 ) may be symmetrically positioned with respect to the center of the wave generator 120 .

As the vertical depth of the groove 130 changes along the outer circumference of the lower surface of the wave generator 120, when the wave generator 120 rotates, the vertical depth of the groove 130 in contact with the ball bearing changes. can do. As the depth of the groove 130 in contact with the ball bearing changes, the ball bearing may be pressed in the vertical direction, which will be described in more detail below with reference to FIGS. 5 and 6 .

FIG. 5 is a sectional perspective view of the wave generator 120 and the bearing member 140 shown in FIG. 2 viewed from the lower side. And, Figure 6 is a schematic diagram schematically showing the height of the ball bearing of the bearing member 140 according to the depth of the groove portion 130 in Figure 5.

As shown in FIG. 5 , the bearing ball 141 may include a plurality of ball members 141a. A plurality of ball members may be disposed in the cage 142 , and a plurality of recessed portions 142a configured to hold the plurality of ball members in the groove portion 130 may be formed.

The bearing ball 141 may be held in the groove 130 of the wave generator 120 by the cage 142 . A plurality of ball members 141a of the bearing balls 141 may be disposed in the recessed portion 142a of the cage 142 . When the wave generator 120 rotates, the bearing ball 141 maintains contact with the groove 130 and can be rotated and displaced. Here, rotation and displacement of the bearing ball 141 may mean rotation and displacement of each ball member 141a of the bearing ball 141 . When the wave generator 120 rotates, the bearing ball 141 may be displaced in the vertical direction based on the change in the depth of the groove 130 in the vertical direction.

When the bearing ball 141 is displaced in the vertical direction, the bearing ball 141 can be displaced while being accommodated in the groove 130 while being pressurized by the wave generator 120 . For example, the bearing ball 141 may be pressed downward while being accommodated in the groove 130 at a location where the vertical depth of the groove 130 is the smallest (eg, d2 in FIG. 4 ). In addition, the bearing ball 141 is not pressed downward while being accommodated in the groove part 130 at a place where the vertical depth of the groove part 130 is the largest (for example, d1 in FIG. 4 ), or can be pressed more weakly. Here, the fact that the bearing ball 141 is weakly pressed at the place where the vertical depth of the groove 130 is the largest (eg, d1 in FIG. 4) means that the vertical depth of the groove 130 is the smallest (eg, For example, in d2) of FIG. 4 , it may mean that the bearing ball 141 is pressed smaller than the pressing force.

Referring to FIG. 6 , when the bearing ball 141 is pressed downward, the flex spline 150 contacting at least a portion of the bearing ball 141 may also be pressed downward. For example, at least a portion of the bearing ball 141 is pressed downward at a place where the vertical depth of the groove portion 130 is the smallest (eg, d2 in FIG. 4 ), and the bearing ball 141 pressed downward A portion of the flex spline 150 may contact. A portion of the flex spline 150 may be pressed downward by the bearing ball 141 pressed downward.

The flex spline 150 comprising a flexible material can be deformed by pressure. A portion of the flex spline 150 may be pressed downward by the bearing ball 141 and deformed downward. As a portion of the flex spline 150 is pressed by the bearing ball 141 and deformed downward, the outer circumferential portion of the lower surface of the flex spline 150 and at least a portion of the upper surface of the circular spline 160 come into contact. can

7 is a diagram showing the operation of the harmonic reducer 100 according to an embodiment. And, FIG. 8 is a schematic diagram schematically illustrating an enlarged portion A in FIG. 7 .

A first gear portion 151a may be formed along the outer circumference of the lower surface of the flex spline 150 of the harmonic reducer 100 according to an embodiment. The first gear portion 151a of the flex spline 150 may protrude downward.

A second gear portion 160a may be formed on an upper surface of the circular spline 160 of the harmonic reducer 100 . The second gear portion 160a of the circular spline 160 may protrude upward. The first gear portion 151a of the flex spline 150 and the second gear portion 160a of the circular spline 160 may be formed to correspond to each other. Here, the correspondence between the first gear portion 151a and the second gear portion 160a means that the first gear portion 151a and the second gear portion 160a are engaged with each other, and the flex spline 150 and the circular spline It means that 160 can rotate relative to each other, and it can further mean that the flex spline 150 can be decelerated by the circular spline 160.

The number of first gears of the first gear unit 151a and the number of second gears of the second gear unit 160a are different from each other. A reduced output can be delivered due to a difference between the number of first gears and the number of second gears.

As the wave generator 120 rotates, a portion of the flex spline 150 is pressed by the bearing ball 141 and rotates. Here, one part of the flex spline 150 (eg, the first gear portion 151a of the flex spline 150) and one part of the circular spline 160 (eg, the second gear portion 151a of the circular spline 160) The gear portions 160a may be meshed with each other at variable points. That is, the point where the flex spline 150 and the circular spline 160 meet may be changed according to the rotation of the wave generator 120 .

In more detail, the wave generator 120 is connected to a predetermined power unit (not shown). For example, by input power transmitted from the power unit, the wave generator 120 may rotate at a predetermined angular velocity in the R1 direction with the first axis X1 as the center.

Referring to FIG. 2 together, when the wave generator 120 rotates about the first axis X1, the groove 130 formed in the wave generator 120 can also rotate about the first axis X1. there is. As described above, when the wave generator 120 rotates, the bearing ball 141 accommodated in the groove 130 of the wave generator 120 rotates and is displaced in the vertical direction. A portion of the flex spline 150 is pressurized and deformed from the bearing ball 141 displaced in the vertical direction to form the first gear portion 151a of the flex spline 150 and the second gear portion 160a of the circular spline 160. Can be meshed at points where are variable with each other.

Here, since the number of teeth of the first gear unit 151a and the number of teeth of the second gear unit 160a are different from each other, the flex spline 150 is decelerated and the decelerated output can be rotated in the R2 direction. The decelerated output may be transmitted to the outside through an output unit (not shown) connected to the flex spline 150 .

The harmonic reducer 100 according to an embodiment improves the shape of the component to a disk shape, and changes the depth of the formed groove 130 along the outer circumference of the lower surface, so that the flex spline 150 and the circular It is designed to control the meshing point of the spline 160. Accordingly, the weight of the harmonic reducer 100 can be reduced, and the volume can be reduced.

In addition, the harmonic reducer 100 according to an embodiment includes a wave generator 120 having a groove 130 and a bearing ball 141 accommodated in the groove 130 . By pressing the flex spline 150 by rolling friction using the bearing balls 141, friction that may occur between components of the harmonic reducer 100 can be reduced, and efficiency can be increased based on the reduced friction. .

9 is a perspective view when the flex spline 150 shown in FIG. 2 is coupled. And, FIG. 10 is an exploded perspective view of the flex spline 150 of FIG. 9 .

Referring together with FIG. 2 , the flex spline 150 of the harmonic reducer 100 according to an embodiment may include an elastic deformation part 151 that contacts at least a portion of the bearing member 140 . The elastic deformation part 151 may be pressed and deformed by rotation and displacement of the bearing member 140 .

The flex spline 150 may include a power transmission unit 152 coupled to the elastic deformation unit 151 . The elastic deformation part 151 and the power transmission part 152 may be configured to be separable from each other. The power transmission unit 152 may be configured to transmit power to the outside. The power transmission unit 152 may be connected to an output unit (not shown) to transmit power to the output unit.

The elastic deformation part 151 and the power transmission part 152 of the flex spline 150 may include different materials to have different stiffness. For example, the elastic deformation part 151 of the flex spline 150 may include a material more flexible than the power transmission part 152 . That is, the elastic deformable part 151 includes a more flexible material than the power transmission part 152, so that it can be more easily deformed when an external force is applied.

The elastic deformation part 151 may have a disk shape. A through hole 1511 opened in a vertical direction may be formed at the center of the disk shape of the elastic deformation part 151 . When the elastic deformation part 151 and the power transmission part 152 are coupled, the power transmission part 152 may be disposed to pass through the through hole 1511 of the elastic deformation part 151 .

The power transmission unit 152 may include a first power transmission unit 152a and a second power transmission unit 152b. The first power transmission unit 152a may be coupled to an upper side of the elastic deformation unit 151 . The first power transmission unit 152a may contact the second cylinder bearing 172 . The second power transmission unit 152b may be coupled to the lower side of the elastic deformation unit 151 . The second power transmission unit 152b may contact the third cylinder bearing ( 173 in FIG. 2 ).

By separating the elastic deformation part 151 and the power transmission part 152 of the flex spline 150 of the harmonic reducer 100 according to an embodiment, it is possible to reduce manufacturing cost and save energy required for elastic deformation. Based on the separable flex splines 150, stress concentration that may occur in the flex splines 150 can be prevented and energy required for elastic deformation can be reduced, thereby increasing efficiency.

The harmonic reducer 100 according to an embodiment can reduce the energy required to elastically deform a predetermined portion (eg, the elastic deformable part 151) of the flex spline 150 through the separable flex spline 150. . In addition, the thickness of only a predetermined portion of the flex spline 150 can be selectively increased as needed, so that the stiffness in the rotational direction can be increased.

11 is a schematic diagram of a power transmission system 200 according to an embodiment.

The power transmission system 200 includes the harmonic reducer 100 according to the above-described embodiment. The power transmission system 200 includes a power unit 210 configured to generate power and transmit the generated power to the harmonic reducer 100 . The power unit 210 may be connected to the harmonic reducer 100. The power unit 210 may be, for example, a motor. The power unit 210 may generate rotational power and transmit it to the harmonic reducer 100 .

The power transmission system 200 includes an output unit 220 configured to receive power decelerated by the harmonic reducer 100 . The output unit 220 may be connected to the harmonic reducer 100. The output unit 220 may be, for example, an output gear. For example, when the power unit 210 is connected to the upper end of the harmonic reducer 100, the output unit 220 may be connected to the lower end of the harmonic reducer 100.

The above description is merely an example of the technical idea of the present invention, and various modifications and variations can be made by those skilled in the art without departing from the essential characteristics of the present invention. Therefore, the embodiments disclosed in the present invention are not intended to limit the technical idea of the present invention, but to explain, and the scope of the technical idea of the present invention is not limited by these embodiments. The protection scope of the present invention should be construed according to the claims below, and all technical ideas within the equivalent range should be construed as being included in the scope of the present invention.

100: harmonic reducer

110: upper housing

120: wave generator

130: groove

140: bearing member

141: bearing ball

141a: ball member

142a: depression

150: flex spline

151: elastic deformation part

151a: first gear unit

1511: through hole

152: power transmission unit

152a: first power transmission unit

152b: second power transmission unit

160: circular spline

160a: second gear unit

171: first cylinder bearing

172: second cylinder bearing

173: third cylinder bearing

200: power transmission system

210: power unit

220: output unit

Claims

a wave generator having a disk shape, having grooves formed along an outer circumference of a lower surface thereof, and configured to rotate around a first axis;

a bearing member including a bearing ball accommodated in the groove and configured to be rotatable and displaceable based on rotation of the wave generator, and a cage configured to hold the bearing ball in the groove;

flex splines that contact at least a portion of the bearing balls, are configured to be rotatable about the first axis by rotation and displacement of the bearing balls based on rotation of the wave generator, and are flexible; and

A circular spline having a disk shape and having an upper surface at least partially in contact with an outer circumferential portion of the lower surface of the flex spline;

harmonization reducer.
According to claim 1,

A vertical depth of the groove in which the bearing ball is accommodated varies along an outer circumference of the lower surface of the wave generator;

When the wave generator rotates, the bearing ball is displaced in an up and down direction based on a change in the depth of the groove in the up and down direction.

harmonization reducer.
According to claim 2,

When the wave generator rotates, a portion of the flex spline is pressed from the bearing ball displaced in an up and down direction;

As a portion of the flex spline is pressed in the vertical direction by the bearing ball, an outer circumferential portion of the lower surface of the flex spline and at least a portion of the upper surface of the circular spline contact,

harmonization reducer.
According to claim 3,

A first gear portion is formed along the outer circumference of the lower surface of the flex spline,

A second gear portion configured to correspond to the first gear portion is formed on the upper surface of the circular spline,

As the wave generator rotates,

The first gear unit and the second gear unit are meshed with each other at a variable point.

harmonization reducer.
According to claim 4,

The first gear number of the first gear part and the second gear number of the second gear part are different from each other.

harmonization reducer.
According to claim 1,

The bearing ball includes a plurality of ball members,

In the cage, the plurality of ball members are respectively disposed and a plurality of recesses configured to hold the plurality of ball members in the groove portion are formed,

harmonization reducer.
a wave generator having a disk shape and configured to rotate about a first axis;

a bearing member configured to rotate and displace based on rotation of the wave generator;

flex splines contacting at least a portion of the bearing member and configured to be rotatable about the first axis by rotation and displacement of the bearing member based on rotation of the wave generator, the flex spline being flexible; and

A circular spline having an upper surface at least partially in contact with an outer circumferential portion of a lower surface of the flex spline, configured to be rotatable around the first axis by contact with the flex spline, and having a disk shape; including, ,

The flex spline,

an elastic deformable portion that is in contact with at least a portion of the bearing member and is pressed and deformed by rotation and displacement of the bearing member; and

A power transmission unit coupled to the elastic deformation unit and configured to transmit power to the outside;

harmonization reducer.
According to claim 7,

The elastic deformation part and the power transmission part are separable from each other,

harmonization reducer.
According to claim 8,

The elastically deformable part has a disk shape, and a through hole opened in the vertical direction is formed at the center of the disk shape of the elastically deformable part.

When the elastic deformation part and the power transmission part are coupled, the power transmission part is disposed to pass through the through hole of the elastic deformation part.

harmonization reducer.
According to claim 8,

The power transmission unit,

a first power transmission unit coupled to an upper side of the elastic deformation unit; and

A second power transmission unit coupled to the lower side of the elastic deformation unit; including,

harmonization reducer.
The harmonic reducer according to any one of claims 1 to 10;

a power unit configured to generate power and transmit the generated power to the harmonic reducer; and

An output unit configured to receive power decelerated by the harmonic reducer;

power transmission system.