Wave gear device

Abstract

A wave gear device (1) is provided with an inner tooth gear (2) of an inner ring integrated type. A bolt hole (27) is formed in the inner tooth gear (2), and the bolt hole (27) is provided with a bolt through hole portion (28) and a screw hole portion (29) that is continuous with the bolt through hole portion (28) and extends in the direction of an axis (1a). The screw hole portion (29) in which a bolt fastening connection force acts is formed at a position that is deviated in the direction of the axis (1a) from a position adjacent to the outer side in the radial direction with respect to an inner tooth (20). Deformation of a portion in which the inner tooth (20) is formed at the time of bolt fastening connection can be reduced, and disadvantages such as a decrease in meshing accuracy or assembly accuracy of the inner tooth gear (2) and an outer tooth gear (3) due to deformation can be suppressed.

Description

Technical Field

[0001] The present invention relates to a wave gear device that uses bearings to support a rigid internal gear and a flexible external gear in a state where they can rotate relative to each other, and more specifically, to a wave gear device of an internal gear having an inner ring integrally formed with the bearing and the internal gear. Background Technology

[0002] Regarding wave gear devices with bearings, from the perspectives of miniaturization and flattening, sometimes an internal gear with an integral inner ring (or an inner ring with an integral inner ring) is used, where the inner ring of the bearing is integrally formed with the internal gear. For example, Patent Document 1 describes a wave gear device with an integral inner ring internal gear.

[0003] Regarding the internal gear with an integrated inner ring, internal teeth are formed on its inner circular circumferential surface, and a track groove for the inner ring side of the bearing is formed on its outer circular circumferential surface. In addition, a threaded hole with an opening on one of its annular end faces is formed on the internal gear, and the internal gear is mounted to a fixed side component (device housing) or an output component that outputs speed reduction rotation by fastening with screws or bolts.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent Application Publication No. 9-291983 Summary of the Invention

[0007] Regarding the integrated internal gear of the wave gear device, if the screw hole for installation is located near the internal gear forming part, the internal gear part will deform when the internal gear is fastened to other parts using bolts (screws), which may result in drawbacks such as reduced meshing accuracy and assembly accuracy with the external gear.

[0008] In view of this, the object of the present invention is to provide a undulating gear device having an inner ring integral type internal gear capable of suppressing deformation of the internal tooth portion caused by bolt (screw) fastening connection.

[0009] The wave gear device of the present invention comprises: a rigid internal gear; a flexible external gear; a wave generator that causes the external gear to flex into a non-circular shape and partially mesh with the internal gear, and causes the meshing position of the external gear relative to the internal gear to move in the circumferential direction; and a bearing that supports the internal gear and the external gear in a state capable of relative rotation. The internal gear is an integral type gear formed with the inner ring of the bearing. The internal gear comprises: a circular outer circumferential surface having an inner ring side track groove of the bearing; a circular inner circumferential surface having internal teeth; and an annular end face with bolt holes opening on the annular end face. The bolt holes are arranged at predetermined intervals in the circumferential direction and extend in the axial direction.

[0010] Regarding the inner ring integral type internal gear of the wave gear device of the present invention, when viewed along the axial direction, its internal teeth are biased towards the annular end face relative to the inner ring side track groove. Furthermore, the bolt hole formed in the internal gear includes: a bolt through-hole portion that opens at the annular end face; and a threaded hole portion that extends continuously along the axial direction relative to the bolt through-hole portion. When viewed along the axial direction, the threaded hole portion of the bolt hole is biased towards the opposite side of the annular end face relative to the internal teeth.

[0011] The effects of the invention

[0012] Regarding the inner ring integral type internal gear of the wave gear device of the present invention, the bolt (screw) fastening connection force is exerted in the screw hole portion at a position offset from the inner tooth in the axial direction from the position adjacent to the outer side in the radial direction. Therefore, it is possible to suppress the disadvantages such as the decrease in meshing accuracy or assembly accuracy of the internal gear and the external gear caused by the deformation of the portion where the inner tooth is formed during bolt (screw) fastening connection. Attached Figure Description

[0013] Figure 1 (a) is a schematic longitudinal sectional view showing an example of the wave gear device of the present invention. Figure 1 (b) is its outline end view.

[0014] Figure 2 (a) is a schematic longitudinal sectional view of an internal gear with an integral inner ring. Figure 2 (b) is its outline end view. Detailed Implementation

[0015] Hereinafter, embodiments of the wave gear device applying the present invention will be described with reference to the accompanying drawings. Furthermore, the embodiments described below represent one example of the present invention and are not intended to limit the present invention to these embodiments.

[0016] like Figure 1As shown, the wave gear device 1 includes: a rigid internal gear 2; a flexible external gear 3, which is formed in the shape of a top hat; a wave generator 4; and a bearing 5, which supports the internal gear 2 and the external gear 3 in a state where they can rotate relative to each other. The wave generator 4 is configured such that the portion of the external gear 3 with external teeth 30 is bent into an elliptical shape and partially meshes with the internal teeth 20 of the internal gear 2. If the wave generator 4 is driven to rotate using a motor or the like (not shown), the meshing position of the external gear 3 relative to the internal gear 2 moves in the circumferential direction. As a result, a relative rotation is generated between the two gears 2 and 3 corresponding to the difference in the number of teeth between the internal gear 2 and the external gear 3. For example, if the internal gear 2 is fixed to a fixed-side member (not shown) and supported in a non-rotating manner, relative rotation is generated from the external gear 3 side as a deceleration rotation output.

[0017] In this example, bearing 5 is a crossed roller bearing, and its outer ring 6 is fastened and fixed to the annular boss 31 of the external gear 3. The inner ring of bearing 5 is integrally formed with the internal gear 2. That is, the internal gear 2 is an integral type internal gear formed with the inner ring of bearing 5. The internal gear 2 includes: a circular outer circumferential surface 22, which forms the inner ring side track groove 21 (V-groove) of bearing 5; a circular inner circumferential surface 24, which forms internal teeth 20; and a first annular end face 25 formed on one side in the direction of axis 1a and a second annular end face 26 formed on the other side. Bolt holes 27 are formed in the internal gear 2 for fastening and fixing to a fixed side component (not shown).

[0018] Bolt holes 27 are arranged at equal angular intervals along the circumferential direction, opening on the first annular end face 25 and extending from the first annular end face 25 along the axis 1a. Each bolt hole 27 includes: a bolt through hole portion 28 (plain hole) opening on the first annular end face 25; and a threaded hole portion 29 continuously extending relative to the bolt through hole portion 28 along the axis 1a. The bolt through hole portion 28 is a portion having a circular inner circumferential surface, and the threaded hole portion 29 is a portion with threads cut into the circular inner circumferential surface.

[0019] Here, when viewed along axis 1a, the internal teeth 20 of the internal gear 2 are formed on the inner circumferential surface portion of the circular inner circumferential surface 24 on the side of the first annular end face 25. The inner ring side track groove 21 is formed on the outer circumferential surface portion of the circular outer circumferential surface 22 on the side of the second annular end face 26. That is, when viewed along axis 1a, the internal teeth 20 are formed at a position offset towards the first annular end face relative to the inner ring side track groove 21.

[0020] Furthermore, the bolt through-hole portion 28 of the bolt hole 27 is formed on the outer side of the internal teeth 20 in the radial direction, and the screw hole portion 29 is formed at a position offset from the internal teeth 20 in the direction of the axis 1a. In other words, when viewed in the direction of the axis 1a, the screw hole portion 29 of the bolt hole 27 is formed at a position offset relative to the internal teeth 20 towards the opposite side of the first annular end face 25.

[0021] Thus, regarding the integral inner gear 2, the threaded portion 29 of the bolt hole 27 is formed at an offset position in the direction of axis 1a relative to the portion where the internal teeth 20 are formed. When the internal gear 2 is fastened to the fixed side component (not shown), the bolted portion 29 where the bolt fastening force is applied is offset in the direction of axis 1a relative to the internal teeth 20 from a position near the outer side in the radial direction. Therefore, during bolt fastening, deformation occurring in the portion where the internal teeth 20 of the internal gear 2 are formed can be suppressed or reduced. As a result, the reduction in meshing accuracy or assembly accuracy caused by deformation can be suppressed.

Claims

1. A wave gear device, comprising: Rigid internal gears; Flexible external gears; A wave generator that causes the external gear to flex into a non-circular shape and partially mesh with the internal gear, and causes the meshing position of the external gear relative to the internal gear to move circumferentially; and A bearing that supports the internal gear and the external gear in a state where they can rotate relative to each other. The internal gear is an integrally formed gear with the inner ring of the bearing. The internal gear comprises: a circular outer circumferential surface having an inner ring side raceway groove for the bearing; a circular inner circumferential surface having internal teeth; and an annular end face having bolt holes opening on the annular end face. The bolt holes are arranged at predetermined intervals along the circumferential direction and extend from the annular end face along the axial direction. Its features are, When viewed along the axis, the internal teeth of the internal gear are offset toward the annular end face relative to the inner ring side groove. The bolt hole includes: a bolt through-hole portion that opens on the annular end face; and a threaded hole portion that extends continuously relative to the bolt through-hole portion and along the axis. When viewed along the axis, the entire bolt hole portion of the bolt hole is located offset from the internal teeth toward the opposite side of the annular end face.

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