Fastening structures for components and harmonic drive gears

Abstract

Provided is strain wave gearing (1), in which on a tightening surface between a boss (33) on an external spline gear (3) and a first end plate (8), formed are tapered tightening surfaces (331, 81), inclined with respect to an orthogonal plane that is orthogonal to a center axis (1a). Additionally, on a tightening surface between an internal spline gear (2) and a second end plate (10), tapered tightening surfaces (21, 101) are formed. Due to engagement of the tapered tightening surfaces (331, 81) and engagement of the tapered tightening surfaces (21, 101), a firm tightening state can be formed, and radially-directed displacement of the first and second end plates (8, 10) that arises due to radially-directed load can be reduced. Decentering between a wave generator (4) and support bearings (7, 9) originating in the radially-directed displacement can be prevented or controlled, and the acting of unnecessary radial force on the wave generator (4) can be averted.

Description

Technical Field

[0001] The present invention relates to a fastening structure for components in which a plurality of components are fastened and fixed axially by fastening bolts, and particularly to a fastening structure for components used when an internal gear or an external gear is fastened and fixed to an end plate on which a support bearing for supporting an input shaft of a harmonic gear device is mounted.

Background Art

[0002] A harmonic gear device includes, as basic components, a rigid internal gear, a flexible external gear, and a wave generator that deflects the external gear into an elliptical shape and meshes it partially with the internal gear. By rotating the wave generator, the meshing position of the external gear with respect to the internal gear moves in the circumferential direction, and a relative rotation corresponding to the difference in the number of teeth between the two gears occurs between the two gears. One of the gears is fixed so as not to rotate, and a decelerated rotation is output from the other gear to the load side.

[0003] As a harmonic gear device, there is known a configuration in which an input shaft is attached to a wave generator and the input shaft is supported by support bearings at positions on both axial sides of the wave generator (Patent Documents 1 to 3). The support bearing that supports one axial side of the input shaft is attached to a fixed-side end plate such as a device housing, and the support bearing that supports the other side of the input shaft is attached to an output-side end plate (output shaft) that outputs a decelerated rotation. Of the internal gear and the external gear, the fixed-side gear is fastened and fixed to the fixed-side end plate, and the output-side gear that outputs a decelerated rotation is fastened and fixed to the output-side end plate. A load-side component to be driven is connected to the output-side end plate.

[0004] In this type of harmonic drive gear, the load, such as the weight of the load-side component to be driven, is applied to the output-side end plate. The load applied to the output-side end plate acts on the support bearing attached to the output-side end plate. As a result, misalignment may occur between the support bearing and the wave generator connected to the input shaft supported by the support bearing. In the harmonic drive gear gear described in Patent Document 1, the input shaft is connected to the wave generator via an Oldham coupling, and such misalignment is absorbed by the Oldham coupling. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2014-74450 [Patent Document 2] Patent No. 5496426 [Patent Document 3] Japanese Patent Publication No. 2002-21948 [Overview of the project] [Problems that the invention aims to solve]

[0006] If a coupling such as an Oldham joint is not provided with the wave generator, there is a concern that the reliability of the wave drive gear system may be compromised due to radial forces acting on the wave generator as a result of misalignment, especially when the load acting from the load side is large. Such misalignment is caused by radial deformation (deformation in a direction perpendicular to the central axis) that occurs in the output end plate and fixed end plate supporting the support bearing due to the load acting from the load side.

[0007] However, in conventional harmonic drive gears, the fastening points using fastening bolts are designed based on torsional moment (load torque), and the fastening strength against radial forces at the fastening points is sufficient, so radial forces were not considered important. In other words, radial deformation was not given any consideration in the design of the fastening points.

[0008] In view of these points, the object of the present invention is to provide a fastening structure for components that can reliably fasten and fix multiple components from the axial direction using fastening bolts, so as to suppress radial deformation and displacement that occurs at the fastening point due to an externally applied load.

[0009] Furthermore, an object of the present invention is to provide a gear fastening structure for a harmonic drive gear that can fasten and fix one of the gears, either an external gear or an internal gear, to a fixed-side or output-side end plate from the axial direction using fastening bolts, in order to suppress radial deformation and displacement that occurs at the fastening point due to an external force applied from a direction perpendicular to the central axis.

[0010] Furthermore, an object of the present invention is to provide a harmonic drive gear device in which one of the gears, either an external gear or an internal gear, and a fixed or output end plate are fastened and fixed from the axial direction by fastening bolts, so as to suppress radial deformation and displacement that occurs at the fastening point due to an external force applied from a direction perpendicular to the central axis. [Means for solving the problem]

[0011] The present invention relates to a fastening structure for a component in which a first component and a second component are fastened and fixed together by fastening bolts from an axial direction, which is along the central axis. The aforementioned first component is, A first fastening surface formed on one end face in the axial direction, A first bolt hole opening into the first fastening surface and extending through in the axial direction, A first tapered fastening surface is formed on at least a portion of the first fastening surface and is inclined by the same angle at each position in the circumferential direction with respect to a perpendicular plane perpendicular to the central axis, It is equipped with, The second part is, A second fastening surface superimposed on the first fastening surface in a surface contact state from the axial direction, A second bolt hole opening into the second fastening surface and extending coaxially with the first bolt hole, A second tapered fastening surface is formed on at least a portion of the second fastening surface and has a shape complementary to the first tapered fastening surface, It is characterized by having the following features.

[0012] Here, by making the inclination angle of the first and second tapered fastening surfaces with respect to the orthogonal plane smaller than the friction angle of these fastening surfaces, slippage of the fastening surfaces caused by bolt axial force can be prevented. Furthermore, by making the portion surrounding the bolt hole in the first and second fastening surfaces an orthogonal fastening surface perpendicular to the central axis, slippage of the fastening surfaces caused by bolt axial force can be prevented.

[0013] The fastening structure for components of the present invention is suitable for fastening and fixing rigid internal gears and flexible external gears, which are components of a harmonic drive gear system, to a fixed end plate or an output end plate that outputs reduced rotation, which are also components of a harmonic drive gear system.

[0014] Next, the wave drive gear device of the present invention, A rigid internal gear, A flexible external gear, shaped like a cup or a top hat, is coaxially arranged inside the internal gear, A wave generator is coaxially positioned inside the external gear, The input shaft is coaxially attached to the aforementioned wave generator, A first end plate rotatably supports the first shaft portion of the input shaft, which extends from the wave generator to one side in the axial direction, via a first support bearing, A second end plate rotatably supports the second shaft portion of the input shaft, which extends from the wave generator to the other side in the axial direction, via a second support bearing, Multiple first fastening bolts fasten and fix the annular or disc-shaped boss formed on the external gear to the first end plate from the axial direction, The internal gear is fastened and fixed to the second end plate by a plurality of second fastening bolts from the axial direction, Equipped with, If the fastening surface formed between the boss of the external gear fastened by the first fastening bolt and the first end plate is defined as the first fastening surface, a bolt hole of the first fastening bolt extends through the first fastening surface, and at least a part of the first fastening surface is a first tapered fastening surface that is inclined by the same angle at each position in the circumferential direction with respect to an orthogonal plane perpendicular to the central axis. If the fastening surface formed between the internal gear fastened by the second fastening bolt and the second end plate is defined as the second fastening surface, a bolt hole of the second fastening bolt extends through the second fastening surface, and at least a part of the second fastening surface is a second tapered fastening surface that is inclined by the same angle at each position in the circumferential direction with respect to the orthogonal plane.

Advantages of the Invention

[0015] In the fastening structure of the parts of the present invention, first and second tapered fastening surfaces inclined with respect to an orthogonal plane perpendicular to the central axis are formed on the first fastening surface of the first part and the second fastening surface of the second part that are fastened and fixed by the fastening bolt. When an external force acts from a direction perpendicular to the central axis, since the first and second tapered fastening surfaces are mechanically engaged from the perpendicular direction, relative displacement of the first and second parts in the perpendicular direction is prevented or suppressed.

[0016] Also, in the harmonic gear device of the present invention, a tapered fastening surface inclined with respect to an orthogonal plane perpendicular to the central axis is formed on the fastening surface between the boss of the external gear and the first end plate, and a tapered fastening surface is also formed on the fastening surface between the internal gear and the second end plate. The tapered fastening surface can reduce the radial displacement of the first and second end plates caused by the radial load. Thereby, it is possible to prevent or suppress the misalignment between the wave generator and the support bearing caused by the radial displacement caused by the radial load acting from the load side, and it is possible to avoid the action of unnecessary radial force on the wave generator.

Brief Description of the Drawings

[0017] [Figure 1] (A) is a schematic longitudinal sectional view of a harmonic gear device to which the present invention is applied, (B) is an end view when viewed from the side of the first end plate which is a fixed side component thereof, and (C) is an end view when viewed from the side of the second end plate which is an output side component thereof. [Figure 2] It is a semi-longitudinal sectional view showing an enlarged harmonic gear device of FIG. 1. [Figure 3] It is an explanatory view showing another example of a fastening structure.

Embodiment for Carrying out the Invention

[0018] Hereinafter, a harmonic gear device according to an embodiment to which the present invention is applied will be described with reference to the drawings. The embodiments described below show an example of the present invention, and the present invention is not limited to the embodiments and can also be applied to a fastening structure of a plurality of components in a gear device other than a harmonic gear device.

[0019] Referring to FIG. 1 for explanation, a harmonic gear device 1 according to an embodiment includes a rigid internal gear 2 having an annular shape, a flexible external gear 3 that is coaxially disposed inside the internal gear 2 and can flex in the radial direction, and a wave generator 4 that is coaxially disposed inside the external gear 3. The wave generator 4 deflects the external gear 3 into a non-circular shape, in this example an elliptical shape, and meshes it partially with the internal gear 2, and moves the meshing positions of these two gears 2 and 3 in the circumferential direction.

[0020] The internal gear 2 and the external gear 3 are supported in a state of being relatively rotatable by a main bearing 5 made of, for example, a cross roller bearing. Further, an input shaft 6 for inputting rotation from a motor or the like (not shown) is coaxially attached to the wave generator 4. The wave generator 4 of this example includes a rigid cam plate 41 and a wave generator bearing 42 attached to the non-circular outer peripheral surface of the cam plate 41, in this example an elliptical outer peripheral surface. The cam plate 41 is integrally formed with the input shaft 6. The cam plate 41 may be manufactured as a separate component and coaxially fastened and fixed to the input shaft 6. The input shaft 6 is a hollow shaft but may also be a solid shaft.

[0021] In the input shaft 6, the portion extending from the cam plate 41 of the wave generator 4 to one side in the axial direction is designated as the first shaft portion 61, and the portion extending to the other side in the axial direction is designated as the second shaft portion 62. The first shaft portion 61 of the input shaft 6 is rotatably supported by the first end plate 8 via a first support bearing 7 made of a ball bearing or the like. The second shaft portion 62 of the input shaft 6 is rotatably supported by the second end plate 10 via a second support bearing 9 made of a ball bearing or the like. An internal gear 2, an external gear 3, a wave generator 4, and a main bearing 5 are arranged between the first and second end plates 8 and 10.

[0022] The external gear 3 is a so-called top hat shaped external gear, comprising a radially flexible cylindrical body 31, a diaphragm 32 extending radially outward from one end of the cylindrical body 31, an annular boss 33 integrally formed on the outer edge of the diaphragm 32, and external teeth 34 formed on the outer surface portion of the open end, which is the other end of the cylindrical body 31. The outer diameter of the boss 33 of the external gear 3 is larger than the outer diameter of the internal gear 2. A wave generator 4 is fitted inside the cylindrical body 31 on which the external teeth 34 are formed. The external teeth 34 of the external gear 3, which are bent into an elliptical shape by the wave generator 4, mesh with the internal teeth 2a of the internal gear 2 at the positions of both ends of the major axis of the ellipse.

[0023] The main bearing 5 is positioned to coaxially surround the portion of the cylindrical body 31 of the external gear 3 between the external teeth 34 and the diaphragm 32. The outer ring 51 of the main bearing 5 is coaxially fixed to the boss 33 of the external gear 3. In this example, the outer circumference portion of the first end plate 8, the boss 33 of the external gear 3, and the outer ring 51 are fastened and fixed together by multiple first fastening bolts 11 from the axial direction, which is along the central axis 1a. The inner ring 52 of the main bearing 5 is coaxially fixed to the internal gear 2. In this example, the outer circumference portion of the second end plate 10, the internal gear 2, and the inner ring 52 are fastened and fixed together from the axial direction by multiple second fastening bolts 12.

[0024] In the wave drive gear unit 1, when the wave generator 4 rotates due to the rotation input via the input shaft 6, the meshing position of the external gear 3 with respect to the internal gear 2 moves in the circumferential direction. A relative rotation reduced by a speed ratio determined by the difference in the number of teeth between the internal gear 2a and the external gear 34 occurs between the internal gear 2 and the external gear 3. In this example, the external gear 3 attached to the first end plate 8 (fixed end plate) is considered the fixed side, and the internal gear 2 attached to the second end plate 10 is considered the rotating side. The reduced rotation generated in the internal gear 2 is output from the second end plate 10 (output end plate), which functions as a reduced rotation output shaft, to a load-side component (not shown) attached to the second end plate 10.

[0025] In this example, the wave generator 4 of the wave drive gear unit 1 is not equipped with a coupling such as an Oldham joint, and the cam plate 41 of the wave generator 4 is integrally formed with the input shaft 6. A radial load acting from the load side to the output side component, the second end plate 10 (indicated by arrow A in Figure 1(A)), can cause misalignment between the first and second support bearings 7 and 9 mounted on the first and second end plates 8 and 10, and the wave generator 4. To reduce the radial deformation of the first and second end plates 8 and 10 that causes such misalignment, the fastening structure between the internal gear 2 and the second end plate 10 and inner ring 52 is appropriately set, and the fastening structure between the boss 33 of the external gear 3 and the first end plate 8 and outer ring 51 is also appropriately set.

[0026] (fastening structure) Figure 2 is a semi-longitudinal cross-sectional view showing an enlarged view of the harmonic drive gear 1 shown in Figure 1(A). The following explanation will refer to Figures 1 and 2.

[0027] First, the fastening structure between the external gear 3, the first end plate 8, and the outer ring 51 of the main bearing 5 will be described. The fastening surfaces formed between the boss 33 of the external gear 3 and the first end plate 8, and between the boss 33 and the outer ring 51, which are fastened by the first fastening bolts 11, are tapered fastening surfaces inclined by the same angle at each position in the circumferential direction with respect to a plane perpendicular to the central axis 1a. In this example, the longitudinal cross-sectional shape of the boss 33 of the external gear 3 when cut by a plane containing the central axis 1a is a trapezoid that tapers from the inner circumference to the outer circumference. As a result, the end faces on both sides of the boss 33 in the axial direction are tapered fastening surfaces 331 and 332 inclined by the same angle in opposite directions. The boss 33 has bolt holes 333 that extend through in the axial direction, and the bolt holes 333 open into the tapered fastening surfaces 331 and 332.

[0028] The end face portion of the first end plate 8 facing the tapered fastening surface 331 on the outer circumference is a tapered fastening surface 81 with a shape complementary to the tapered fastening surface 331, and the tapered fastening surfaces 331 and 81 are superimposed in a surface contact state from the axial direction. A bolt hole 82 extending axially through is formed in the outer circumference portion of the first end plate 8, and the bolt hole 82 opens into the tapered fastening surface 81. Similarly, the end face of the outer ring 51 of the main bearing 5 facing the other tapered fastening surface 332 of the boss 33 is a tapered fastening surface 511 with a shape complementary to the tapered fastening surface 332, and the tapered fastening surfaces 332 and 511 are superimposed in a surface contact state from the axial direction. A bolt hole 512 extending axially through is formed in the outer ring 51, and the bolt hole 512 opens into the tapered fastening surface 511.

[0029] The tapered fastening surfaces 331 and 332 of the boss 33 of the external gear 3 are superimposed axially on the tapered fastening surfaces 81 of the first end plate 8 and the tapered fastening surface 511 of the outer ring 51, respectively. These three components are fastened together by passing the first fastening bolt 11 through them. Here, the inclination angles of the tapered fastening surfaces 331 and 81 are set to angles that do not exceed the friction angle between them. Similarly, the inclination angles of the tapered fastening surfaces 332 and 511 are set to angles that do not exceed the friction angle between them. As a result, slippage does not occur between the tapered fastening surfaces 331 and 81, and between the tapered fastening surfaces 332 and 511, due to the bolt axial force during fastening. Furthermore, when a load is applied to these parts from the radial direction, the mechanical engagement between the tapered fastening surfaces 331 and 81, and the mechanical engagement between the tapered fastening surfaces 332 and 511 suppress radial displacement and misalignment between the three members (first end plate 8, boss 33 of the external gear 3, and outer ring 51 of the main bearing 5), thereby achieving a strong fastening state.

[0030] Next, the fastening structure between the internal gear 2, the second end plate 10, and the inner ring 52 of the main bearing 5 will be described. The fastening surfaces between the internal gear 2 and the second end plate 10, and between the internal gear 2 and the inner ring 52, which are fastened by the second fastening bolts 12, are tapered fastening surfaces that are inclined by the same angle at each position in the circumferential direction with respect to a plane perpendicular to the central axis 1a. In this example, the longitudinal cross-sectional shape of the internal gear 2 when cut by a plane containing the central axis 1a is a trapezoid that tapers from the inner circumference to the outer circumference, except for the inner peripheral edge portion where the internal teeth 2a are formed. As a result, tapered fastening surfaces 21 and 22 are formed on both axial end faces of the internal gear 2, except for their inner peripheral edge portions, inclined by the same angle in opposite directions. The internal gear 2 has bolt holes 23 that extend through in the axial direction, and the bolt holes 23 open into the tapered fastening surfaces 21 and 22.

[0031] The end face portion of the second end plate 10 facing the tapered fastening surface 21 on the outer circumference is a tapered fastening surface 101 with a shape complementary to the tapered fastening surface 21, and the tapered fastening surfaces 21 and 101 are superimposed in a surface contact state from the axial direction. A bolt hole 102 extending axially is also formed in the outer circumference portion of the second end plate 10, and the bolt hole 102 opens into the tapered fastening surface 101. Similarly, the end face of the inner ring 52 of the main bearing 5 facing the other tapered fastening surface 22 of the internal gear 2 is a tapered fastening surface 521 with a shape complementary to the tapered fastening surface 22, and the tapered fastening surfaces 22 and 521 are superimposed in a surface contact state from the axial direction. A bolt hole 522 extending axially is formed in the inner ring 52, and the bolt hole 522 opens into the tapered fastening surface 521.

[0032] The tapered fastening surfaces 21 and 22 of the internal gear 2 are superimposed axially on the tapered fastening surfaces 101 of the second end plate 10 and 521 of the inner ring 52, respectively. These three components are fastened together by passing the second fastening bolt 12 through them. Here, the inclination angles of the tapered fastening surfaces 21 and 101 are set to angles that do not exceed the friction angle between them. Similarly, the inclination angles of the tapered fastening surfaces 22 and 521 are set to angles that do not exceed the friction angle between them. As a result, slippage does not occur between the tapered fastening surfaces 21 and 101 and between the tapered fastening surfaces 22 and 521 due to the bolt axial force during fastening. Furthermore, when a load is applied to these parts from the radial direction, the mechanical engagement between the tapered fastening surfaces 21 and 101 and the mechanical engagement between the tapered fastening surfaces 22 and 521 suppresses radial displacement and misalignment between the three members (second end plate 10, internal gear 2, and inner ring 52 of the main bearing 5), thus providing a strong fastening state.

[0033] Thus, in the wave drive gear unit 1 of this example, the first end plate 8, the boss 33 of the external gear 3, and the outer ring 51 of the main bearing 5 are fastened and fixed by a robust fastening structure that prevents displacement under radial load, and the second end plate 10, the internal gear 2, and the inner ring 52 of the main bearing 5 are fastened and fixed by this structure. This suppresses radial deformation of the first and second end plates 8 and 10 caused by radial load acting from the load side. As a result, misalignment between the wave generator 4 and the first and second support bearings 7 and 9 caused by radial deformation can be prevented or suppressed, and excessive radial force acting on the wave generator 4 can be avoided.

[0034] (Another example of a fastening structure) Figure 3 is an explanatory diagram showing another example of the fastening structure of the second end plate 10, the internal gear 2, and the inner ring 52 of the main bearing 5 in the wave drive gear 1. In this example of the fastening structure, orthogonal fastening surfaces 211 and 221 perpendicular to the central axis 1a are formed on the fastening surfaces 210 and 220 formed on both axial end faces of the internal gear 2. On one fastening surface 210, a tapered fastening surface 212 inclined with respect to the central axis 1a is formed on the inner circumference side of the orthogonal fastening surface 211, except for the inner peripheral edge where the internal teeth 2a are formed. Similarly, on the other fastening surface 220, a tapered fastening surface 222 inclined with respect to the central axis 1a is formed on the inner circumference side of the orthogonal fastening surface 221. Bolt holes extending axially through the internal gear 2 are opened in the orthogonal fastening surfaces 211 and 221. In this example, the fastening surfaces 210 and 220 have a symmetrical shape.

[0035] A fastening surface 110 is formed on the outer end face of the second end plate 10, which is superimposed on the fastening surface 210 of the internal gear 2 in a surface contact state. An orthogonal fastening surface 111 is formed on this fastening surface 110 in a direction perpendicular to the central axis 1a, and a tapered fastening surface 112 is formed on its inner side, which is inclined with respect to the central axis 1a, with bolt holes opening in the orthogonal fastening surface 111.

[0036] Similarly, the end face of the inner ring 52 of the main bearing 5 has a fastening surface 525 that is superimposed on the fastening surface 220 of the internal gear 2 in a surface contact state. This fastening surface 525 has an orthogonal fastening surface 526 that extends in a direction perpendicular to the central axis 1a, and on its inner circumference side, a tapered fastening surface 527 that is inclined with respect to the central axis 1a is formed, and bolt holes are opened in the orthogonal fastening surface 526.

[0037] This fastening structure also allows for firm fastening and fixing of the second end plate 10, the internal gear 2, and the inner ring 52 of the main bearing 5, preventing or suppressing radial deformation and displacement of each component. In this case, it is also possible to set the inclination angle of the tapered fastening surface to an angle exceeding the friction angle.

[0038] The fastening structure of the other first end plate 8, the boss 33 of the external gear 3, and the outer ring 51 of the main bearing 5 in the wave drive gear unit 1 can also be a similar structure.

[0039] (Other embodiments) Furthermore, the fastening structure of the present invention can be similarly applied to fastening components other than the gears that make up a harmonic drive gear.

Claims

1. A fastening structure for a component in which a first component and a second component are fastened and fixed together by fastening bolts from an axial direction, which is along the central axis, The first component is, A first fastening surface formed on one end face in the axial direction, A first bolt hole opening into the first fastening surface and extending through in the axial direction, A first tapered fastening surface is formed on at least a portion of the first fastening surface and is inclined by the same angle at each position in the circumferential direction with respect to a perpendicular plane perpendicular to the central axis, It is equipped with, The second part is, A second fastening surface superimposed on the first fastening surface in a surface contact state from the axial direction, A second bolt hole opening into the second fastening surface and extending coaxially with the first bolt hole, A second tapered fastening surface is formed on at least a portion of the second fastening surface and has a shape complementary to the first tapered fastening surface, A fastening structure for components characterized by having the following features.

2. In claim 1, A fastening structure for a component in which the inclination angle of the first tapered fastening surface with respect to the orthogonal plane is smaller than the friction angle between the first and second fastening surfaces.

3. In claim 1, The first fastening surface is provided with a first orthogonal fastening surface perpendicular to the central axis, and the first bolt hole is opened in the first orthogonal fastening surface. The fastening structure of a component comprising a second fastening surface which is perpendicular to the central axis and has a second bolt hole opening in the second orthogonal fastening surface.

4. A gear fastening structure for a wave drive gear, The aforementioned wave drive gear device, A rigid internal gear, Flexible external gears, A fixed end plate located on one side in the axial direction relative to the internal gear and the external gear, An output end plate located on the other side in the axial direction of the internal gear and the external gear, which outputs a reduction rotation, The input shaft is supported in a rotatable state by support bearings attached to the fixed end plate and the output end plate, respectively. It is equipped with, One of the internal gear and the external gear is designated as the first component. If one of the fixed end plate and the output end plate is designated as the second component, A gear fastening structure for a wave drive gear, characterized in that the first part and the second part are fastened and fixed to each other by the fastening structure of the part described in any one of claims 1 to 3.

5. A rigid internal gear, A flexible external gear, shaped like a cup or a top hat, is coaxially arranged inside the internal gear, A wave generator is coaxially positioned inside the external gear, The input shaft is coaxially attached to the aforementioned wave generator, A first end plate rotatably supports the first shaft portion of the input shaft, which extends from the wave generator to one side in the axial direction, via a first support bearing, A second end plate rotatably supports the second shaft portion of the input shaft, which extends from the wave generator to the other side in the axial direction, via a second support bearing, Multiple first fastening bolts fasten and fix the annular or disc-shaped boss formed on the external gear to the first end plate from the axial direction, Multiple second fastening bolts fasten and secure the internal gear to the second end plate from the axial direction, Equipped with, In the boss and first end plate of the external gear fastened by the first fastening bolt, the boss has a boss-side first fastening surface, and the first end plate has a first end plate-side first fastening surface facing the boss-side first fastening surface, and the boss-side first fastening surface and the first end plate-side first fastening surface are superimposed in a surface contact state from the axial direction. The bolt hole of the first fastening bolt extends through the boss-side first fastening surface and the first end plate-side first fastening surface. At least a portion of the boss-side first fastening surface is a boss-side first tapered fastening surface that is inclined by the same angle at each position in the circumferential direction with respect to a plane perpendicular to the central axis, The portion of the first fastening surface on the first end plate side that faces the first tapered fastening surface on the boss side is a first tapered fastening surface on the first end plate side that has a shape complementary to the first tapered fastening surface on the boss side. In the internal gear and the second end plate fastened by the second fastening bolt, the internal gear has a second fastening surface on the internal gear side, and the second end plate has a second fastening surface on the second end plate side that faces the second fastening surface on the internal gear side, and the second fastening surface on the internal gear side and the second fastening surface on the second end plate side are superimposed in a surface contact state from the axial direction. The bolt hole of the second fastening bolt extends through the second fastening surface on the internal gear side and the second fastening surface on the second end plate side. At least a portion of the second fastening surface on the internal gear side is a tapered fastening surface on the internal gear side that is inclined by the same angle at each position in the circumferential direction with respect to a plane perpendicular to the central axis, The portion of the second fastening surface on the second end plate side that faces the second tapered fastening surface on the internal gear side has a shape complementary to the second tapered fastening surface on the internal gear side. A wave drive gear device characterized by the following features.

6. In claim 5, The inclination angle of the boss-side first tapered fastening surface with respect to the orthogonal plane is smaller than the friction angle between the boss-side first fastening surface and the first end plate-side first fastening surface. The inclination angle of the second tapered fastening surface on the internal gear side with respect to the orthogonal plane is smaller than the friction angle between the second fastening surface on the internal gear side and the second fastening surface on the second end plate side. Harsh drive gear system.

7. In claim 5, The boss-side first fastening surface comprises the boss-side first tapered fastening surface and the boss-side first orthogonal fastening surface parallel to the orthogonal plane, and the bolt hole of the first fastening bolt penetrates the boss-side first orthogonal fastening surface. The first fastening surface on the first end plate side comprises the first tapered fastening surface on the first end plate side and the first orthogonal fastening surface on the first end plate side parallel to the orthogonal plane, and the bolt hole of the first fastening bolt penetrates the boss-side first orthogonal fastening surface. The internal gear side second fastening surface comprises the internal gear side second tapered fastening surface and the internal gear side second orthogonal fastening surface parallel to the orthogonal plane, and the bolt hole of the second fastening bolt penetrates the internal gear side second orthogonal fastening surface. The second fastening surface on the second end plate side comprises the second tapered fastening surface on the second end plate side and the second orthogonal fastening surface on the second end plate side parallel to the orthogonal plane, with the bolt hole of the second fastening bolt passing through the second orthogonal fastening surface on the second end plate side. Harsh drive gear system.

8. In claim 5, It is equipped with a main bearing mounted between the boss of the internal gear and the external gear, The main bearing comprises a first raceway ring, which is one of the inner ring and the outer ring, and a second raceway ring, which is the other of the inner ring and the outer ring. The first end plate, the boss of the external gear, and the first raceway ring of the main bearing are fastened and fixed together by the first fastening bolt in an overlapping state from the axial direction. The second end plate, the internal gear, and the second raceway ring of the main bearing are fastened and fixed together by the second fastening bolt in an overlapping state from the axial direction. In the boss and first raceway of the external gear fastened by the first fastening bolt, the boss has a boss-side third fastening surface, and the first raceway has a first raceway-side third fastening surface facing the boss-side third fastening surface, and the boss-side third fastening surface and the first raceway-side third fastening surface are superimposed in a surface contact state from the axial direction. The bolt hole of the first fastening bolt extends through the boss-side third fastening surface and the first raceway-side third fastening surface. At least a portion of the boss-side third fastening surface is a boss-side third tapered fastening surface that is inclined by the same angle at each position in the circumferential direction with respect to a plane perpendicular to the central axis, and whose inclination direction is opposite to that of the boss-side first tapered fastening surface. The portion of the third fastening surface on the first raceway side that faces the third tapered fastening surface on the boss side is a third tapered fastening surface on the first raceway side that has a shape complementary to the third tapered fastening surface on the boss side. In the internal gear and the second raceway ring fastened by the second fastening bolt, the internal gear has an internal gear-side fourth fastening surface, and the second raceway ring has a second raceway ring-side fourth fastening surface facing the internal gear-side fourth fastening surface, and the internal gear-side fourth fastening surface and the second raceway ring-side fourth fastening surface are superimposed in a surface contact state from the axial direction. The bolt hole of the second fastening bolt extends through the fourth fastening surface on the internal gear side and the fourth fastening surface on the second raceway ring side. At least a portion of the fourth fastening surface on the internal gear side is inclined by the same angle at each position in the circumferential direction with respect to a plane perpendicular to the central axis, and is an internal gear side fourth tapered fastening surface facing the opposite direction to the second tapered fastening surface on the second end plate side. The portion of the fourth fastening surface on the second raceway side that faces the fourth tapered fastening surface on the internal gear side has a shape that is complementary to the fourth tapered fastening surface on the internal gear side. Harsh drive gear system.

9. In claim 8, The inclination angle of the boss-side first tapered fastening surface with respect to the orthogonal plane is set to a value smaller than the friction angle between the boss-side first fastening surface and the first end plate-side first fastening surface. The inclination angle of the second tapered fastening surface on the internal gear side with respect to the orthogonal plane is set to a value smaller than the friction angle between the second fastening surface on the internal gear side and the second fastening surface on the second end plate side. The inclination angle of the boss-side third tapered fastening surface with respect to the orthogonal plane is set to a value smaller than the friction angle between the boss-side third fastening surface and the first raceway-side third fastening surface. A harmonic drive gear in which the inclination angle of the fourth tapered fastening surface on the internal gear side with respect to the orthogonal plane is set to a value smaller than the friction angle between the fourth fastening surface on the internal gear side and the fourth fastening surface on the second raceway ring side.

10. In claim 8, The boss-side third fastening surface comprises the boss-side third tapered fastening surface and the boss-side third orthogonal fastening surface parallel to the orthogonal plane, and the bolt hole of the first fastening bolt penetrates the boss-side third orthogonal fastening surface. The third fastening surface on the first raceway side comprises a third tapered fastening surface on the first raceway side and a third orthogonal fastening surface on the first raceway side parallel to the orthogonal plane, and the bolt hole of the first fastening bolt penetrates the third orthogonal fastening surface on the first raceway side. The internal gear side fourth fastening surface comprises the internal gear side fourth tapered fastening surface and the internal gear side fourth orthogonal fastening surface parallel to the orthogonal plane, and the bolt hole of the second fastening bolt passes through the internal gear side fourth orthogonal fastening surface. The fourth fastening surface on the second raceway side comprises the fourth tapered fastening surface on the second raceway side and the fourth orthogonal fastening surface on the second raceway side parallel to the orthogonal plane, and the bolt hole of the second fastening bolt penetrates the fourth orthogonal fastening surface on the second raceway side.

Images