JP2020197264A - Wave gear device - Google Patents

Abstract

To keep performance of a wave gear device itself by stably restraining a position shift of a bearing.SOLUTION: A wave gear device 100 comprises a cylindrical internal gear 110 comprising a plurality of internal teeth 111 on an inner peripheral surface, a cylindrical flexible external gear 120 comprising a plurality of external teeth 121 on an outer peripheral surface, and a wave generator 130 arranged inside the external gear 120, and for elliptically deflecting the external gear 120, engaging with the external teeth 121 in a long-diameter part with the internal teeth 111 of the internal gear 110, and moving an engagement position 101 in a circumferential direction. The wave generator 130 comprises an elliptical cam 136, a flexible bearing 131 arranged on an outer peripheral surface of the elliptical cam 136, and a first stopper 140 arranged in a short-diameter part of the elliptical cam 136, of which one end part 141 is brought into contact with the elliptical cam 136 from one side in an axial direction of the flexible bearing 131, and of which another end part 142 is brought into contact with the flexible bearing 131 from another side in the axial direction.SELECTED DRAWING: Figure 1

Description

The present invention relates to a strain wave gearing.

Conventionally, there is a wave gearing device as one of the gearing devices used as a speed reducer. This wave gear device has a cylindrical internal gear made of a rigid body, an external tooth that meshes with the internal tooth of the internal gear, and has a flexible tubular external tooth gear, and internal teeth and external teeth. Is provided with an elliptical wave generator that meshes the teeth at a predetermined position and rotates the meshing position along the internal gear (see, for example, Patent Document 1).

In such a wave gear device, in order to prevent the external gear of the bearing, which is a part of the wave generator, from falling inward, a stopper that regulates the axial movement of the bearing is continuously provided over the entire circumference. It is provided in.

Japanese Unexamined Patent Publication No. 11-351341

By the way, when a large axial load acts on the bearing, the bearing is pushed inward or outward in the axial direction of the external gear and is displaced in position, increasing the possibility of contact with the stopper. When the bearing comes into contact with the stopper that is continuous over the entire circumference, the stopper also comes into contact with the cage inside the bearing. As a result, the temperature of the bearing becomes high, and as a result, the efficiency is significantly deteriorated, the life of the grease is shortened, the oil burning of the bearing occurs, and the performance of the strain wave gearing itself is deteriorated.

An object of the present invention is to maintain the performance of the strain wave gearing itself by stably suppressing the displacement of the bearing.

In order to achieve the above object, the wave gear device according to the present disclosure includes a cylindrical internal gear having a plurality of internal teeth on the inner peripheral surface and a cylindrical flexibility having a plurality of external teeth on the outer peripheral surface. The external gear and the external gear are placed inside the external gear, and the external gear is bent in an elliptical shape to engage the external teeth of the long diameter part with the internal teeth of the internal gear to move the meshing position in the circumferential direction. A wave generator is provided, and the wave generator is arranged on an elliptical cam, a flexible bearing arranged on the outer peripheral surface of the elliptical cam, and a short-diameter portion of the elliptical cam, and one end thereof is a flexible bearing. It has a first stopper that abuts the elliptical cam from one side in the axial direction and the other end abuts the flexible bearing from the other side in the axial direction.

According to the present invention, the performance of the strain wave gearing itself can be maintained by stably suppressing the positional deviation of the bearing.

It is sectional drawing of the wave gear device which concerns on embodiment. It is sectional drawing which shows the part of the wave gear device which concerns on embodiment in an enlarged manner. It is sectional drawing which looked at the cross section including the line III-III in FIG. It is explanatory drawing which shows the schematic structure of the elliptical cam which concerns on embodiment. It is explanatory drawing which shows the schematic structure of the 1st stopper which concerns on embodiment. It is explanatory drawing which shows the schematic structure of the 2nd stopper which concerns on embodiment. It is explanatory drawing which shows the state at the time of assembling the 1st stopper, the elliptical cam and the 2nd stopper which concerns on embodiment.

Hereinafter, embodiments of the strain wave gearing according to the present invention will be described with reference to the drawings. It should be noted that all of the embodiments described below are comprehensive or specific examples. Numerical values, shapes, materials, components, arrangement positions of components, connection forms, etc. shown in the following embodiments are examples, and are not intended to limit the present invention. In addition, among the components in the following embodiments, the components not described in the independent claims indicating the embodiment according to the present disclosure will be described as arbitrary components. The embodiment of the present disclosure is not limited to the current independent claims, but may be expressed by other independent claims.

In addition, the drawings are schematic views in which emphasis, omission, and ratio are adjusted as appropriate to show the present invention, and may differ from the actual shape, positional relationship, and ratio.

In the following description and drawings, the axial direction of the strain wave gearing 100 is defined as the Z-axis direction, and the two directions orthogonal to each other on the plane orthogonal to the Z-axis direction are defined as the X-axis direction and the Y-axis direction. Define. In the following description, for example, the positive side in the Z-axis direction indicates the arrow direction side of the Z-axis, and the negative side in the Z-axis direction indicates the side opposite to the positive side in the Z-axis direction. The same applies to the X-axis direction and the Y-axis direction.

[Structure of strain wave gearing]
FIG. 1 is a cross-sectional view of the strain wave gearing according to the embodiment. FIG. 2 is an enlarged cross-sectional view showing a part of the strain wave gearing according to the embodiment. FIG. 3 is a cross-sectional view of the cross section including lines III-III in FIG. As shown in these figures, the wave gear device 100 includes an internal gear 110, an external gear 120, and a wave generator 130.

The internal gear 110 is a metal member having a structurally higher rigidity than the external gear 120 and having an inner peripheral surface of a cylinder, and is a member that is separated from the rotation of the input shaft body and the output shaft body and attached in a fixed state. is there. The internal gear 110 has a plurality of internal teeth 111 (see FIG. 2) formed on the inner peripheral surface. A plurality of through holes 112 arranged at predetermined intervals in the circumferential direction are formed on the outer peripheral portion of the internal gear 110. For example, a screw (not shown) is inserted into the plurality of through holes 112, and the wave gear device 100 is screwed to a fixing target to be fixed.

The external gear 120 is a tubular metal member that is structurally less rigid and more flexible than the internal gear 110. The external gear 120 is a member having a plurality of external teeth 121 (see FIG. 2) that mesh with the internal teeth 111 of the internal gear 110 on the outer peripheral surface of one end (the end on the negative side in the Z-axis direction in the drawing). is there. The external gear 120 includes a flange portion 122 and a boss portion 123. Here, "one end" means the input shaft body side (minus side in the Z-axis direction in the figure) with respect to the wave gear device 100 in the axial direction (Z-axis direction in the figure) of the external gear 120 or the wave generator 130. It is described as meaning the end of. For example, in the external gear 120, the external teeth 121 are arranged at one end. Further, "the other end", which is a synonym for "one end", means the output shaft body side (in the figure) with respect to the wave gear device 100 in the axial direction (Z-axis direction in the figure) of the external gear 120 or the wave generator 130. , Z-axis direction plus side), for example, in the external gear 120, the flange portion 122 is arranged at the other end. The "part" of the "one end" and "the other end" means a region near the end including the end.

In the external gear 120, when there is no load, specifically, when the external gear 120 is taken out from the strain wave gearing device 100 and no force is applied from the other, one end is opened and the flange portion 122 is arranged at the other end. It has a substantially bottomed cylindrical shape. The cylindrical portion of the external tooth gear 120 integrally includes a body portion 124 on which the external teeth 121 are arranged and an annular rim portion 125 extending from the body portion 124 toward the other end.

The flatness ratio, which is the ratio of the width W1 of the external gear 120 to the tip circle diameter D1 of the external gear 120 when no load is applied, is 0.25 or less. Here, the width W1 of the external gear 120 is the distance from one end of the external gear 120 to the other end (the other end of the boss 123 in the present embodiment). Due to such a flatness, the entire wave gear device 100 can be made thinner, and a compact reduction gear in which the input shaft body (not shown) and the output shaft body (not shown) are coaxially close to each other can be obtained. It can be realized. The tooth tip circle diameter D1 and width W1 of the external gear 120 are shown in FIG. 1, but in reality, the external gear 120 is taken out from the strain wave gearing device 100 and no force is applied from others. The dimensions in (1) shall be adopted. The flatness is preferably 0.15 or more. If the flatness is less than 0.15, the desired transmission efficiency cannot be achieved. Further, the flatness is preferably 0.2 or more and 0.25 or less. According to this, it becomes easy to realize a desired torque capacity as well as downsizing the wave gear device 100.

The flange portion 122 extends inward in the radial direction from the other end of the cylindrical portion of the external gear 120, and corresponds to the bottom of the external gear 120 that transmits rotation to the output shaft. The shape of the flange portion 122 is not particularly limited, but in the case of the present embodiment, the flange portion 122 has a thin plate-like ring shape, and the outer diameter corresponds to the diameter of the rim portion 125. , It extends integrally from the other end edge of the rim portion 125. The flange portion 122 is arranged in a plane that virtually includes the other end of the rim portion 125. In other words, the flange portion 122 is arranged flush with or substantially flush with the other end of the rim portion 125. Here, substantially flush with each other means that at least one of the other end of the rim portion 125, the flange portion 122, and the boss portion 123 is displaced in the axial direction as the external tooth gear 120 is deformed by pressing the wave generator 130. It is described as a meaning that includes an error of about the amount. That is, in order to prevent other members such as the output shaft body connected to the boss portion 123 and the bearing supporting the output shaft body from interfering with the other end of the rim portion 125 and the flange portion 122 due to the deformation of the external gear 120. Even if the flange portion 122 is provided with a dent, a protrusion, or the like within the range of the relief amount provided in the above range, the flange portion 122 is included in a substantially flush state within the range.

The wall thicknesses of the flange portion 122, the rim portion 125, and the body portion 124 are not particularly limited, and are determined by the characteristics of the materials constituting the external gear 120 and the like. In the present embodiment, the wall thicknesses of the flange portion 122 and the rim portion 125 are the same, and are thinner than the total tooth depth of the external teeth 121. Specifically, for example, when the tooth tip circle diameter D1 is 68.8 mm, the wall thickness of the flange portion 122 and the rim portion 125 is 0.5 mm or less and 0.2 mm or more. If the wall thickness of the flange portion 122 and the rim portion 125 is thicker than 0.5 mm, the deformation of the body portion 124 by the wave generator 130 is hindered and the desired transmission efficiency cannot be obtained. If the wall thickness of the flange portion 122 and the rim portion 125 is less than 0.1 mm, the desired torque capacity cannot be achieved.

The boss portion 123 is provided on the flange portion 122 in a state of projecting from the flange portion 122 to one end side, and is a portion connected to the output shaft body. The shape of the boss portion 123 is not particularly limited, but in the case of the present embodiment, the boss portion 123 has a plate-like ring shape thicker than the flange portion 122, and the outer periphery thereof is the flange portion 122. It is continuously connected to the outer circumference of. The surface portion on the other end side of the boss portion 123 is arranged flush with or substantially flush with the surface portion on the other end side of the flange portion 122. In the case of the present embodiment, the boss portion 123 slightly protrudes to the other end side from the flange portion 122. The protruding length of the boss portion 123 toward the other end is a length for avoiding interference with an output shaft body or the like attached to the boss portion 123, and the surface portion on the other end side of the boss portion 123 is a flange. It can be considered that the surface portion on the other end side of the portion 122 is substantially flush with the surface portion.

In the case of the present embodiment, a plurality of through holes 126 are formed in the boss portion 123 at predetermined intervals in the circumferential direction. A bolt 200 for fastening the output shaft body is inserted into each through hole 126.

The wall thickness of the boss portion 123, that is, the amount of protrusion of the boss portion 123 from the flange portion 122 to one end side is not particularly limited, and is determined by the mounting mode with the output shaft body and the like. In this embodiment, the boss portion 123 has a structure in which a bolt is pierced through a through hole 126 provided in the boss portion 123 from one end side and the boss portion 123 and the output shaft body are fastened using the bolt. , A wall thickness (protrusion amount) is adopted so that the bolt head does not interfere with the wave generator 130 or the like.

As described above, the flatness of the entire external gear 120 is reduced by arranging the boss portion 123 to protrude from the flange portion 122 to one end side and not to the other end side (excluding the protrusion for preventing interference). can do.

[Wave generator]
The wave generator 130 is arranged inside the external gear 120 that meshes from the inside of the internal gear 110, bends the external gear 120 to mesh the external tooth 121 with the internal tooth 111, and meshes with the internal tooth 111. It is a member that moves a position (meshing position 101: see FIG. 3) in the circumferential direction. In the case of the present embodiment, the wave generator 130 includes a flexible bearing 131, an elliptical cam 136, a first stopper 140, and a second stopper 150.

The flexible bearing 131 has flexibility. The flexible bearing 131 includes an inner ring 132 fixedly arranged on the outer peripheral surface of the elliptical cam 136, an outer ring 133 arranged radially inside the external gear 120, a plurality of balls 134, and a cage 135. It has. Of the inner ring 132 and the outer ring 133, at least the outer ring 133 has flexibility. An inner ring side raceway groove 1321 that fits into the ball 134 is formed on the outer peripheral surface of the inner ring 132. An outer ring side raceway groove 1331 is formed on the inner peripheral surface of the outer ring 133.

The ball 134 is interposed between the inner ring side raceway groove 1321 and the outer ring side raceway groove 1331. The balls 134 are sandwiched between the inner ring 132 and the outer ring 133 so as to rotate and revolve while being separated from each other by the cage 135.

In the case of the present embodiment, the flexible bearing 131 has a perfect circular shape when it is not fitted to the elliptical cam 136.

The elliptical cam 136 is an elliptical rigid body arranged radially inside the flexible bearing 131. FIG. 4 is an explanatory diagram showing a schematic configuration of the elliptical cam 136 according to the embodiment. Specifically, FIG. 4A is a plan view of the elliptical cam 136, and FIG. 4B is a sectional view of FIG. 4A looking at a cross section including the IVb-IVb line. is there.

The elliptical cam 136 shown in FIG. 4 has an elliptical outer shape with the Y-axis direction as the long axis and the X-axis direction as the short axis. Specifically, the elliptical cam 136 is formed in an elliptical ring shape, and the input shaft body (not shown) is press-fitted or screwed to the opening 137 to be fixed. The opening 137 of the elliptical cam 136 is a two-stage opening, and the negative side in the Z-axis direction is a circular small-diameter portion, and the positive side in the Z-axis direction is a circular large-diameter portion having a larger diameter than the small-diameter portion. ing. Further, on the bottom surface of the elliptical cam 136, a plurality of screw holes 138 for screwing the second stopper 150 are arranged at intervals in the circumferential direction.

A notch 139 is formed in each of the pair of minor axis portions of the elliptical cam 136. Each notch 139 is a concave portion recessed in a rectangular shape toward the central axis of the elliptical cam 136, and penetrates along the Y-axis direction. A first stopper 140 is fitted to each of the notches 139. In this state, the first stopper 140 is in contact with a pair of inner side surfaces forming the notch 139. That is, the first stopper 140 is sandwiched in the circumferential direction by a pair of inner side surfaces forming the notch 139.

[First stopper]
As shown in FIGS. 2 and 3, a pair of first stoppers 140 are provided. Each first stopper 140 is fitted to each of the pair of notches 139. That is, each first stopper 140 is individually arranged on the minor axis portion of the elliptical cam 136. In the following description, of the pair of first stoppers 140, one of the first stoppers 140 arranged above in the X-axis direction will be illustrated as an example, but the same applies to the other first stopper 140. Since it is the configuration of, the description thereof will be omitted.

FIG. 5 is an explanatory diagram showing a schematic configuration of the first stopper 140 according to the embodiment. Specifically, FIG. 5A is a top view of the first stopper 140, FIG. 5B is a side view of the first stopper 140, and FIG. 5C is a first stopper 140. It is a front view of.

As shown in FIG. 5, the first stopper 140 is a member having a substantially Z-shaped outer shape. The first stopper 140 may be formed by, for example, cutting out steel, or may be a sintered metal member or a sintered alloy member. Further, the first stopper 140 may be a metal member other than steel (for example, an aluminum member or a magnesium member) or a resin member as long as weight reduction is important. The first stopper 140 may have elasticity in the X-axis direction in terms of shape or material.

In the present embodiment, the first stopper 140, which is formed by carving out steel and has elasticity in the X-axis direction in shape, is illustrated. Specifically, one end 141 of the first stopper 140 extends to the minus side in the X-axis direction, and the other end 142 of the first stopper 140 extends to the plus side in the X-axis direction. Due to such a shape, the one end portion 141 and the other end portion 142 are easily bent around the base end thereof, and the first stopper 140 as a whole is elastically deformed in the X-axis direction. Further, the portion of the other end 142 on the minus side in the X-axis direction becomes an inclined surface 143 toward the plus side in the X-axis direction as it advances toward the plus side in the Z-axis direction.

As shown in FIG. 2, when the first stopper 140 is fitted to the notch 139 of the elliptical cam 136, the one end portion 141 is in a state of protruding from the notch 139 to the minus side in the Z-axis direction, and the flexible bearing. The elliptical cam 136 is in contact with the elliptical cam 136 from one side (minus side in the Z-axis direction) of the 131 in the axial direction (Z-axis direction). Further, the other end 142 of the first stopper 140 is in contact with the flexible bearing 131 from the other side in the axial direction (plus side in the Z axis direction) in a state of projecting from the notch 139 to the plus side in the Z axis direction. There is. As described above, one end 141 of the first stopper 140 is in contact with the elliptical cam 136 from one side in the axial direction, and the other end 142 is in contact with the flexible bearing 131 from the other side in the axial direction. Even if the flexible bearing 131 attempts to be displaced with respect to the elliptical cam 136 in the axial direction (plus side in the Z-axis direction), the first stopper 140 regulates the positional deviation. As a result, the positional deviation of the flexible bearing 131 with respect to the elliptical cam 136 in the axial direction (plus side in the Z-axis direction) can be stably suppressed by the first stopper 140.

Further, the other end 142 of the first stopper 140 is in contact with the inner ring 132 of the flexible bearing 131, and is arranged inward in the radial direction from the outer diameter of the inner ring 132. As a result, since the other end 142 of the first stopper 140 does not protrude outward from the inner ring 132, it is possible to suppress the interference between the other end 142 and the cage 135.

[Second stopper]
The second stopper 150 is fixed to the elliptical cam 136 so as to abut the flexible bearing 131 from one side in the axial direction (minus side in the Z-axis direction). The second stopper 150 is a circular rigid body arranged inside the flexible bearing 131 in the radial direction. FIG. 6 is an explanatory diagram showing a schematic configuration of the second stopper 150 according to the embodiment. Specifically, FIG. 6A is a plan view of the second stopper 150, and FIG. 6B is a cross-sectional view taken along the line VIb-VIb in FIG. 6A. Is.

The second stopper 150 shown in FIG. 6 has a circular outer shape. Since the second stopper 150 has a circular shape as described above, it can be manufactured at low cost while ensuring the stopper function. Specifically, the second stopper 150 includes a first annular portion 151 and a second annular portion 152 continuously provided with respect to the outer peripheral edge of the first annular portion 151 on the negative side in the Z-axis direction. Have.

A plurality of through holes 1511 for screwing the elliptical cam 136 are arranged in the first annular portion 151 at intervals in the circumferential direction. An input shaft body (not shown) is press-fitted or screwed into the opening 1512 of the first annular portion 151 to be fixed. The opening 1512 has the same shape as the small diameter portion of the opening 137 of the elliptical cam 136, and communicates with the small diameter portion.

The second annular portion 152 is concentric with the first annular portion 151. The outer shape of the second annular portion 152 is larger than that of the first annular portion 151. The opening 1521 of the second annular portion 152 is concentric with the opening 1512 of the first annular portion 151, and is formed in a circular shape larger than the opening 1512. As shown in FIGS. 1 and 2, the second annular portion 152 is in contact with the inner ring 132 of the flexible bearing 131 from the negative side in the Z-axis direction. As a result, the contact area between the second annular portion 152 and the inner ring 132 can be increased, and the inner ring 132 is less likely to be displaced in the circumferential direction. The outer peripheral edge of the second annular portion 152 is arranged inward from the outer diameter of the inner ring 132. As a result, since the outer peripheral edge of the second annular portion 152 does not protrude outward from the inner ring 132, it is possible to suppress interference between the second annular portion 152 and the cage 135.

Further, as shown in FIG. 6, notches 153 are formed at both ends of the second stopper 150 in the X-axis direction. Specifically, each notch 153 is formed at both ends of the first annular portion 151 and the second annular portion 152 in the X-axis direction. Each notch 154 is a concave portion recessed in a rectangular shape toward the central axis of the second stopper 150, and penetrates along the Y-axis direction. As shown in FIGS. 1 and 2, a first stopper 140 is fitted in each of the notches 153. In this state, the first stopper 140 is in contact with a pair of inner side surfaces forming the notch 153. That is, the first stopper 140 is sandwiched in the circumferential direction by a pair of inner side surfaces forming the notch 153.

[Assembly of the first stopper, elliptical cam and second stopper]
Next, the assembly of the first stopper 140, the elliptical cam 136, and the second stopper 150 will be described. FIG. 7 is an explanatory diagram showing a state when the first stopper 140, the elliptical cam 136, and the second stopper 150 according to the embodiment are assembled. Specifically, FIG. 7A is a cross-sectional view showing the time when the first stopper 140 is assembled, and FIG. 7B is a cross-sectional view showing the time when the elliptical cam 136 is assembled. (C) is a cross-sectional view showing when the second stopper 150 is assembled.

As shown in FIG. 7A, before assembling the first stopper 140, the operator first assembles the first stopper 140 at a predetermined position of the inner ring 132 of the flexible bearing 131. Next, as shown in FIG. 7B, the operator attaches the elliptical cam 136 to the inner ring 132 of the flexible bearing 131 from the positive side in the Z-axis direction. At this time, the operator pushes the elliptical cam 136 from the positive side in the Z-axis direction so that the first stopper 140 is inserted into the notch 139 of the elliptical cam 136. At this time, the elliptical cam 136 is guided along the inclined surface 143 of the first stopper 140. Further, since the first stopper 140 is elastically deformed when pushed in, the elliptical cam 136 can be smoothly assembled. The operator pushes the elliptical cam 136 until the elliptical cam 136 comes into contact with the one end portion 141 of the first stopper 140. Next, the operator attaches the second stopper 150 to the inner ring 132 of the flexible bearing 131 from the minus side in the Z-axis direction. At this time, the operator pushes the second stopper 150 from the minus side in the Z-axis direction so that the first stopper 140 is inserted into the notch 153 of the second stopper 150, and pushes the second stopper 150 into the elliptical cam 136. Make a contact. As a result, the first stopper 140, the elliptical cam 136, and the second stopper 150 are assembled. As a result, one end 141 of the first stopper 140 comes into contact with the elliptical cam 136 from one side (minus side in the Z-axis direction) of the flexible bearing 131 in the axial direction, and the other end 142 abuts on the other side (Z) in the axial direction. It is in contact with the flexible bearing 131 from the positive side in the axial direction). The elastic force of the first stopper 140 acts on the flexible bearing 131 in the negative direction in the Z-axis direction. As a result, the flexible bearing 131 is sandwiched in the Z-axis direction by the other end 142 of the first stopper 140 and the second annular portion 152 of the second stopper 150.

[Operation of strain wave gearing]
Next, the operation of the wave gear device 100 will be described. The inner ring 132 of the flexible bearing 131 is elliptically bent by the elliptical cam 136, and the outer ring 133 is elliptically bent by the inner ring 132 via the ball 134. As a result, the wave generator 130 bends the body portion 124 of the external gear 120 into a substantially elliptical shape, and at the same time, the external teeth 121 of the external gear 120 are bent at two meshing positions 101 corresponding to the elliptical major axis portion. The internal teeth 111 of the internal gear 110 mesh with each other (see FIG. 3). At this time, at the portion corresponding to the elliptical minor diameter portion, the external teeth 121 of the external gear 120 and the internal teeth 111 of the internal gear 110 are separated from each other and are not subjected to a radial load. That is, it is a portion that does not affect the elliptical deformation of the flexible bearing 131. As shown in FIGS. 1 and 2, a first stopper 140 is arranged at this location, but the first stopper 140 also does not affect the elliptical deformation of the flexible bearing 131.

In the above state, when the input shaft body rotates at a relatively high speed, it is bent into an elliptical shape by the wave generator 130 and meshes with the internal teeth 111 of the internal gear 110 at two points in the circumferential direction. The meshing position 101 of the outer teeth 121 of the tooth gear 120 moves in the circumferential direction. Since the external teeth 121 and the internal teeth 111 have different numbers of teeth, relative rotation corresponding to the difference in the number of teeth occurs between the external gear 120 and the internal gear 110. This rotation is significantly reduced compared to the input rotation speed. The deceleration rotation is output from the output shaft body. In the present embodiment, the external gear 120 is pressed by the ball 134 of the flexible bearing 131 toward the outer peripheral surface side via the outer ring 133 of the flexible bearing 131 at the meshing position 101 of the internal teeth 111 and the external teeth 121. ing. In this state, the meshing position 101 moves in the circumferential direction at a relatively high speed as the elliptical cam 136 rotates.

Here, when the axial load on the flexible bearing 131 increases during rotation, the flexible bearing 131 tends to be displaced in the axial direction (plus side in the Z-axis direction). As described above, in the first stopper 140, one end 141 abuts on the elliptical cam 136 from one side (minus side in the Z-axis direction) of the flexible bearing 131 in the axial direction, and the other end 142 abuts in the axial direction. The flexible bearing 131 is in contact with the flexible bearing 131 from the other side (plus side in the Z-axis direction). Therefore, even if the flexible bearing 131 tries to shift to the positive side in the Z-axis direction with respect to the elliptical cam 136, the first stopper 140 regulates the position shift. As a result, the displacement of the flexible bearing 131 with respect to the elliptical cam 136 in the positive side in the Z-axis direction can be stably suppressed by the first stopper 140.

Further, in the second stopper 150, the second annular portion 152 is in contact with the inner ring 132 of the flexible bearing 131 from the negative side in the Z-axis direction. Therefore, even if the flexible bearing 131 tries to shift to the negative side in the Z-axis direction with respect to the elliptical cam 136, the second stopper 150 regulates the position shift. As a result, the displacement of the flexible bearing 131 with respect to the elliptical cam 136 in the negative side in the X-axis direction can be stably suppressed by the second stopper 150.

Here, the flexible bearing 131 is sandwiched in the Z-axis direction by the second stopper 150 fixed to the elliptical cam 136 and the first stopper 140 fitted to the notches 139 and 153. .. Therefore, the flexible bearing 131 is less likely to be displaced in the circumferential direction. In particular, the second annular portion 152 of the second stopper 150 is in contact with the inner ring 132 of the flexible bearing 131 from the negative side in the Z-axis direction over substantially the entire circumference. Therefore, the contact area between the second stopper 150 and the inner ring 132 can be increased, and the flexible bearing 131 is less likely to be displaced in the circumferential direction.

[Effects, etc.]
As described above, the wave gear device 100 according to the present embodiment has a cylindrical internal gear 110 having a plurality of internal teeth 111 on the inner peripheral surface and a cylindrical internal gear 110 having a plurality of external teeth 121 on the outer peripheral surface. The flexible external gear 120 and the external gear 120 are arranged inside the external gear 120, and the external gear 120 is bent in an elliptical shape to mesh the external tooth 121 of the long diameter portion with the internal tooth 111 of the internal gear 110. A wave generator 130 for moving the meshing position 101 in the circumferential direction is provided, and the wave generator 130 includes an elliptical cam 136, a flexible bearing 131 arranged on the outer peripheral surface of the elliptical cam 136, and an elliptical cam. Arranged in the minor axis portion of 136, one end 141 abuts the elliptical cam 136 from one side of the flexible bearing 131 in the axial direction, and the other end 142 hits the flexible bearing 131 from the other side in the axial direction. It has a first stopper 140 in contact with it.

According to this, in the first stopper 140, one end 141 abuts on the elliptical cam 136 from one side (minus side in the Z-axis direction) of the flexible bearing 131 in the axial direction, and the other end 142 in the axial direction. It is in contact with the flexible bearing 131 from the other side (plus side in the Z-axis direction). Therefore, even if the flexible bearing 131 tries to shift to the other side with respect to the elliptical cam 136, the first stopper 140 regulates the misalignment. As a result, the displacement of the flexible bearing 131 with respect to the elliptical cam 136 to the other side can be stably suppressed by the first stopper 140. In this way, since the positional deviation of the flexible bearing 131 is stably suppressed, the performance of the strain wave gearing device 100 itself can be maintained.

Further, since the first stopper 140 is provided only on a part of the entire circumference of the flexible bearing 131, it is assumed that the first stopper 140 comes into contact with the cage 135 due to the positional deviation of the flexible bearing 131. However, the amount of contact is small. Therefore, it is possible to suppress the temperature rise of the flexible bearing 131 due to the contact.

Further, the strain wave gearing device 100 has a second stopper 150 fixed to the elliptical cam 136 so as to abut the flexible bearing 131 from one side in the axial direction.

According to this, since the second stopper 150 is in contact with the flexible bearing 131 from one side (minus side in the Z-axis direction), the flexible bearing 131 is moved to one side with respect to the elliptical cam 136. Even if the misalignment is attempted, the second stopper 150 regulates the misalignment. As a result, the positional deviation of the flexible bearing 131 with respect to the elliptical cam 136 to one side can be stably suppressed by the second stopper 150. Therefore, the axial misalignment of the flexible bearing 131 can be suppressed more reliably, and the performance of the strain wave gearing 100 itself can be more maintained.

Further, the flexible bearing 131 is sandwiched in the Z-axis direction by the second stopper 150 fixed to the elliptical cam 136 and the first stopper 140. Therefore, the positional deviation of the flexible bearing 131 in the circumferential direction can be suppressed.

Further, the second stopper 150 is arranged inward in the radial direction with respect to the outer diameter of the inner ring 132 provided in the flexible bearing 131.

According to this, since the second stopper 150 is arranged inward from the outer diameter of the inner ring 132 provided in the flexible bearing 131, the outer peripheral edge of the second stopper 150 does not protrude outward of the inner ring 132. Therefore, it is possible to suppress the interference between the second stopper 150 and the cage 135 of the flexible bearing 131.

Further, a pair of first stoppers 140 are provided, and are arranged for each of the pair of minor diameter portions of the elliptical cam 136.

According to this, since each first stopper 140 is arranged for each of the pair of minor axis portions of the elliptical cam 136, the positional deviation of the elliptical cam 136 at each minor diameter portion is caused by each first stopper 140. It can be suppressed. Therefore, the positional deviation of the elliptical cam 136 can be suppressed in a well-balanced manner.

Further, the other end 142 of the first stopper 140 is arranged inward of the outer diameter of the inner ring 132 provided in the flexible bearing 131.

According to this, since the other end 142 of the first stopper 140 is arranged inward in the radial direction from the outer diameter of the inner ring 132 provided in the flexible bearing 131, the other end 142 of the first stopper 140 Does not protrude outward of the inner ring 132. Therefore, it is possible to suppress the interference between the other end 142 of the first stopper 140 and the cage 135.

Further, the ratio (flatness) of the width W1 of the external gear 120 to the tooth tip circle diameter D1 of the external gear 120 when no load is applied is 0.25 or less.

Here, if the flatness of the external gear 120 is small, the entire wave gear device 100 can be made thin, but the axial load acting on the flexible bearing 131 also increases with the thinning. It will be. The increase in the axial load induces a displacement of the flexible bearing 131 in the positive side in the Z-axis direction. However, in the strain wave gearing device 100 according to the present embodiment, the displacement of the flexible bearing 131 on the positive side in the Z-axis direction is restricted due to the presence of the first stopper 140. Therefore, the first stopper 140 according to the present embodiment is suitable for the strain wave gearing device 100 having a flatness of 0.25 or less in which the axial load tends to increase.

Further, a notch 138 into which the first stopper 140 is fitted is formed in the short diameter portion of the elliptical cam 136.

According to this, the first stopper 140 can be assembled and fitted to the notch 138 of the short diameter portion of the elliptical cam 136. Therefore, the assembling property of the first stopper 140 can be improved. After assembly, the first stopper 140 elastically returns in the notch 138, so that the first stopper 140 can be pressed against the flexible bearing 131 and the elliptical cam 136 by its restoring force. Therefore, the misalignment of the first stopper 140 itself can be suppressed, and as a result, the misalignment of the flexible bearing 131 can be suppressed more reliably.

[Other]
The present invention is not limited to the above embodiment. For example, an embodiment of the present invention may be an embodiment of the present invention realized by arbitrarily combining the components described in the present specification and excluding some of the components. The present invention also includes modifications obtained by making various modifications that can be conceived by those skilled in the art within the scope of the gist of the present invention, that is, the meaning indicated by the words described in the claims. Is done.

For example, in the above embodiment, the case where the first stopper 140 is provided on each of the pair of minor diameter portions of the elliptical cam 136 is illustrated, but the first stopper is provided only on one minor diameter portion of the elliptical cam. It may be.

Further, in the above embodiment, the case where the first stopper 140 and the second stopper 150 are separate bodies is illustrated, but these may be integrally molded.

Further, in the above embodiment, the case where the second stopper 150 is annular is illustrated, but the second stopper does not have to be annular as long as it comes into contact with the flexible bearing from one side in the axial direction. In this case, the weight of the wave gearing device can be reduced. If weight reduction is prioritized, the second stopper may not be provided on the wave gearing device.

Further, in the external gear 120, the connection portion between the rim portion 125 and the flange portion 122 may be chamfered by R or C, or may not be chamfered.

The present invention can be used as a speed reducer or a speed increaser.

100 ... Strain wave gearing, 101 ... Mating position, 110 ... Internal gear, 111 ... Internal tooth, 112 ... Through hole, 120 ... External gear, 121 ... External tooth, 122 ... Flange, 123 ... Bolt, 124 ... Body, 125 ... rim, 126 ... through hole, 130 ... wave generator, 131 ... flexible bearing, 132 ... inner ring, 133 ... outer ring, 134 ... ball, 135 ... cage, 136 ... elliptical cam, 137 ... Opening, 138 ... screw hole, 139 ... notch, 140 ... first stopper, 141 ... one end, 142 ... other end, 143 ... inclined surface, 150 ... second stopper, 151 ... first annular portion, 152 ... second annular portion, 153 ... notch, 200 ... bolt, 1321 ... inner ring side raceway groove, 1331 ... outer ring side raceway groove, 1511 ... through hole, 1512 ... opening, 1521 ... opening, D1 ... tooth tip circle Diameter, W1 ... Width

Claims (6)

Cylindrical internal gear with multiple internal teeth on the inner peripheral surface,
Cylindrical flexible external gear with multiple external teeth on the outer peripheral surface,
Wave generation that is arranged inside the external gear and bends the external gear in an elliptical shape to mesh the external teeth of the long diameter portion with the internal teeth of the internal gear to move the meshing position in the circumferential direction. Equipped with a vessel
The wave generator
With an elliptical cam
Flexible bearings arranged on the outer peripheral surface of the elliptical cam,
Arranged in the minor axis portion of the elliptical cam, one end abuts on the elliptical cam from one side in the axial direction of the flexible bearing and the other end abuts on the flexible bearing from the other side in the axial direction. A wave gear device having a first stopper that abuts. The wave gear device according to claim 1, further comprising a second stopper fixed to the elliptical cam so as to abut the flexible bearing from one side in the axial direction. The wave gear device according to claim 2, wherein the second stopper is arranged inward in the radial direction with respect to the outer diameter of the inner ring provided in the flexible bearing. The wave gear device according to any one of claims 1 to 3, wherein a pair of the first stoppers is provided and arranged for each of the pair of the minor diameter portions of the elliptical cam. The wave gear device according to any one of claims 1 to 4, wherein the other end of the first stopper is arranged inward in the radial direction with respect to the outer diameter of the inner ring provided in the flexible bearing. The wave gear device according to any one of claims 1 to 5, wherein a notch in which the first stopper is fitted is formed in a short diameter portion of the elliptical cam.

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