JPH09273609A - Silk hat-type flexible meshing-type gear device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To alleviate stress concentration in a case where a flexible external gear having the short length and the small outside diameter is used in a silk hat-type flexible meshing-type gear device. SOLUTION: A silk hat-type flexible meshing-type gear device is constituted of a body part 22, a diaphragm 23, and a boss 25. The body part 22 and the diaphragm 23 are gently connected to each other through a bent part 26. The thickness t(26) of the bent part 26 is larger than the thickness t(22) of the body part and the thickness t(23) of the diaphragm. Stress to be generated on it can be alleviated by using this flexible external gear. Moreover, fatigue strength and buckling strength of the flexible external gear can be improved. Accordingly, the flexible external gear in which the axial length and the outside diameter dimension are remarkably decreased in comparison with the conventional one can be used.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a top hat type flexible meshing gear device incorporating a top hat-shaped flexible external gear. For more information,
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a top hat type flexural mesh type gear device in which stress concentration of a top hat-shaped flexible externally toothed gear is alleviated, and its axial length and outer diameter dimension can be reduced.

[0002]

2. Description of the Related Art As a flexible mesh type gear device, a type in which a flexible external gear has a top hat shape is known. In this specification, this type of device is referred to as a top hat flex-meshing gear. FIG. 6 shows a vertical cross section (axial cross section) obtained by cutting the flexible external gear of the top hat type flexural meshing gear device along a plane including the device axis. As shown in this figure, a flexible external gear 1 includes a cylindrical body portion 2, an annular diaphragm 3 having an inner peripheral end portion continuous with the base end side opening end,
The diaphragm 3 is provided with an annular thick boss 5 which is continuous with the outer peripheral end of the diaphragm 3. External teeth 4 are integrally formed on the outer peripheral portion of the front end side open end of the body portion 4 in the circumferential direction.

This type of device is convenient when the rotating member and various wirings are arranged through the device. That is, since the diaphragm 3 of the flexible external gear extends radially outward from the end of the body 2, the inner space of the body 3 can be effectively used.

[0004]

In recent years, there has been an increasing demand for miniaturization of mechanisms such as speed reducers incorporated therein in response to the demand for miniaturization of robots and the like. In order to meet this demand, it is conceivable to shorten the shaft length also in the top hat type flexural mesh type gear device. For that purpose, it is necessary to shorten the axial length of the top hat-shaped flexible external gear, which is a component that defines the dimensions of the device.

The ratio of the axial length of the external gear to the pitch circle diameter of the external gear is about 1: 1 in the external gear generally used in the past. If the axial length is made shorter than this, the coning angle of the external gear also increases accordingly. FIG. 5 shows how the coning angle θ of the flexible externally toothed gear 1 increases according to the axial length. As a result, the inner end portion 3a of the diaphragm 3 and its outer end portion 3b
In some cases, excessive stress concentration may occur.

On the other hand, shear stress due to the transmission torque is also generated in the inner end portion 3a and the outer end portion 3b of the diaphragm 3. Furthermore, stress is generated due to the mounting error of each component.

Therefore, when the axial length of the flexible external gear is shortened, excessive stress concentration is likely to occur on the diaphragm 3. In order to relax the stress concentration, it is necessary to increase the outer diameter of the diaphragm. However, in the top hat type flexural mesh type gear device, the outer diameter dimension is also determined by the outer diameter dimension of the flexible external gear. Therefore, if the outer diameter of the diaphragm is increased, the outer diameter of the device is correspondingly increased. This is an obstacle to making the device small and compact.

In view of this point, the object of the present invention is to alleviate the stress generated in the diaphragm of the flexible external gear without increasing the axial length and outer diameter of the diaphragm of the flexible external gear. It is to propose a structure that can be done.

[0009]

In order to achieve the above object, the present invention provides an annular rigid internal gear, a flexible external gear on the inside, and an external tooth arranged on the inside. While flexibly bending the gear in the radial direction and partially meshing with the rigid internal gear, it has a wave generator that moves these meshing positions in the circumferential direction, the flexible external gear, A cylindrical body with external teeth formed on the outer peripheral surface on one opening end side, an annular diaphragm whose inner peripheral end is continuous to the other open end of the body, and an outer peripheral end of this diaphragm. In a top hat type flexural meshing type gear device having a top hat shape having an annular boss continuously formed in a portion, between the body and the diaphragm of the flexible external gear. The thickness of the curved part that is smoothly continuous It adopts a configuration which is set larger than both and the thickness of the diaphragm.

[0010]

Embodiments of the present invention will be described below with reference to the drawings.

1 and 2 show the overall construction of a top hat type flexural mesh type gear device to which the present invention can be applied. As shown in these figures, a flex meshing type gear device 11 includes an annular rigid internal gear 12, a top hat-shaped flexible external gear 13, and an internal rigid internal gear 12.
It is composed of an elliptical wave generator 14 fitted inside this. The flexible external gear 13 has a cylindrical body 2
2, an annular diaphragm 23 having an inner peripheral end portion 23A continuous with the base end opening thereof, and a thick annular boss 25 continuously formed integrally with the outer peripheral end portion 23B of the diaphragm 23. . External teeth 24 are integrally formed in the outer peripheral portion of the open end of the body portion 22 in the circumferential direction. The annular boss 25 is for attachment to another member (not shown), and the body 22 and the diaphragm 23 are supported in a cantilever state by the boss 25.

On the other hand, the wave generator 14 includes a hollow hub 14a.
And an elliptical rigid cam plate 14b fitted on the outer periphery thereof and a ball bearing 14c fitted on the outer periphery thereof. By the wave generator 14, the portion of the body portion 22 in which the external teeth 24 of the flexible external gear are formed is bent into an elliptical shape, and the two external tooth portions located at both ends of the elliptical major axis are separated. The rigid internal gear 12 meshes with the internal teeth 12a. In this state, when the wave generator 14 rotates about the device axis 11a, the meshing positions of these rotate in the circumferential direction.
By this rotation, relative rotation is generated between the flexible external gear 13 and the rigid internal gear 12 according to the difference in the number of teeth between the external teeth and the internal teeth. Therefore, for example, if the rigid internal gear 12 is fixed and the wave generator 14 is used as a high-speed rotation input element, the external gear 13 becomes a deceleration rotation output element, and a decelerated rotation output is obtained from this. .

FIG. 3 shows a sectional shape when the diaphragm unevenness 23 and the body portion 22 of the flexible external gear 13 are cut along a plane including the apparatus axis 11a. As shown in this figure, the body portion 22 extending in the axial direction and the diaphragm 23 extending in the direction orthogonal to the axial line are smoothly continuous by the curved portion 26.

The curved portion 26 is defined by arcs 26a and 26b that are convex outwards on both the inner peripheral side and the outer peripheral side. Both ends 26c and 26d of the arc 26a on the inner peripheral side are
Each of them is smoothly continuous with the straight lines 22a and 23a defining the inner peripheral side of the body portion 22 and the inner peripheral side of the diaphragm 23. Similarly, both ends 26e and 26f of the arc 26b on the outer peripheral side are straight lines 22b defining the outer peripheral side of the body portion 22 and the outer peripheral side of the diaphragm 23, respectively.
23b is smoothly continuous.

In the present specification, the range of the curved portion 26 is used to mean the range defined by the arc 26a on the inner peripheral side, that is, the range from points 26c to 26d in the figure.

In this example, the relationship between the thickness t (26) of the curved portion 26, the thickness t (22) of the body portion 22 and the thickness t (23) of the diaphragm 23 is defined as follows. There is.

T (26)> t (22) t (26)> t (23) Further, in this example, the thickness t (26) of the curved portion 26 is the thickest at the center of the curved portion, and the thickness t (26) is from the central portion. The taper gradually decreases toward the body and diaphragm.

An experiment was conducted on the top hat type flexural gear device 11 having the above-mentioned structure. As a result, the stress generated in the flexible external gear 13 (bending stress due to the wave generator, shear stress due to torque transmission, It was confirmed that the stress generated due to the mounting error can be relaxed. It was also confirmed that the fatigue strength and the buckling strength of the flexible external gear 13 were increased. Therefore, by adopting the configuration of this example, a flexible external gear having a short shaft length and a small outer diameter can be realized. By using this flexible external gear, it is possible to manufacture a small and compact flexible meshing gear device.

(Other Embodiments) FIG. 4 shows another example of the flexible external gear 13. The cross-sectional shape of the external gear 13A including the shaft is as follows. First,
The diaphragm 23 that is continuous to the inner peripheral side of the curved portion 26
The side of is defined by a straight line 231 extending in a direction (radial direction) orthogonal to the apparatus axis 11a. This straight line 2
An arc 233 defining the outer peripheral side of the curved portion 26 is smoothly continuous to the inner end 232 in the radial direction of 31.
The other end of the arc 233 is at the point 234 at the body 22.
Is smoothly continuous with a straight line 221 extending in the direction of the apparatus axis 11a that defines the inner peripheral side of. On the other hand, the radial outer end 235 of the straight line 231 is smoothly continuous with the arc 236, and the arc 236 is smoothly continuous with the boss 25 side.

On the other hand, on the side of the diaphragm 23 which is continuous with the outer peripheral side of the curved portion 26, the first convex arc 240, the concave arc 250 and the second convex arc 26 are provided.
Basically defined by 0. More specifically, the first convex arc 240 is an arc centered on the point O1, and its outer end 241 in the radial direction is a straight line 242.
In succession. The other end of the straight line 242 is continuous with the boss 25 side.

Radial inner end 2 of the first convex arc 240
43 smoothly continues to the concave arc 250. The concave arc 250 is an arc centered on the point O2. The inner end 251 of the concave arc 250 in the radial direction is the second convex arc 2
It is smoothly continuous to 60. This second convex arc 26
0 is an arc centered on the point O3. This convex arc 26
The radial inner end 261 of 0 is smoothly continuous to the circular arc 262 defining the inner peripheral side of the curved portion 26. The other end of the arc 262 of the curved portion 26 is smoothly continuous with a straight line 222 extending in the direction of the apparatus axis 11a defining the outer peripheral side of the body portion 22.

Here, the curvature of the first convex arc 240 is
It is slightly smaller than the second convex arc 260. On the other hand, the curvature of the concave arc 250 is equal to that of the convex arcs 240 and 26.
Significantly larger than zero.

Also in the flexible external gear 13 of this example, the thickness t (26) of the curved portion 26 is equal to the thickness t (2 of the body portion 22.
2) and the thickness t (23) of the diaphragm 23 are set to be thicker. The thickness t (23) of the diaphragm 23 is the thickness at the boundary between the curved portion 26 and the diaphragm 23, that is, the point 261.
Is the thickness.

A flexible external gear 13 having such a shape
When A is used, the same effect as that of the flexible external gear 13 described above can be obtained, and the diaphragm 23 is used.
It has been confirmed that the stress generated in the above, especially the stress generated in the inner peripheral end 23A and the outer peripheral end 23B can be relieved significantly.

[0025]

As described above, in the top hat type flexural meshing type gear device of the present invention, by flexibly setting the cross-sectional shape of the diaphragm in the top hat-shaped flexible external gear, the flexible top gear The stress generated in the external gear can be relaxed, and a gentle stress distribution can be obtained as a whole. Further, the fatigue strength and buckling strength of the flexible external gear can be increased.

Therefore, according to the present invention, it is possible to obtain a flexible external gear which is shorter than the conventional one and does not require an increase in the outer diameter dimension. Therefore, by using the flexible external gear according to the present invention, a top hat type flexural mesh type gear device can be constructed in a much smaller size and in a more compact size than the conventional one.

[Brief description of drawings]

FIG. 1 is a schematic vertical sectional view of a top hat type flexural mesh type gear device according to an embodiment of the present invention.

FIG. 2 is a schematic front view of the device of FIG. 1 viewed from the direction of the arrow.

3 is an axial cross-sectional view of a portion of the top hat flexible external gear of the apparatus of FIG.

FIG. 4 is a partial shaft-containing sectional view showing another example of a flexible external gear.

FIG. 5 is an explanatory diagram showing an increase in a coning angle by shortening the axial length of a flexible external gear.

FIG. 6 is an explanatory diagram for explaining a problem of a conventional top hat type flexural meshing gear device.

[Explanation of symbols]

 11 ... Top hat type flexural meshing gear device 11a ... Device axis 12 ... Rigid internal gear 13 ... Top hat flexible external gear 14 ... Wave generator 22 ... Body 23 ... Diaphragm 24 ... External teeth 25 ... Boss 26 ... Curved portion t (22) ... Body thickness t (23) ... Diaphragm thickness t (26) ... Curved Thickness of the part 240 ... 1st convex arc 250 ... concave arc 260 ... 2nd convex arc

Claims (2)

[Claims] 1. A ring-shaped rigid internal gear, a flexible external gear inside thereof, and a flexible internal gear arranged inside thereof to bend the external gear in a radial direction to partially part the rigid internal gear. The flexible external gear has a cylindrical shape with external teeth formed on the outer peripheral surface on one opening end side, as well as meshing with each other and a wave generator for moving these meshing positions in the circumferential direction. Silk having a body part, a ring-shaped diaphragm whose inner peripheral end is continuous to the other open end of the body, and a ring-shaped boss continuously formed at the outer peripheral end of the diaphragm. It has a hat shape, and the thickness of the curved portion of the flexible externally toothed gear that is smoothly continuous between the body and the diaphragm is equal to the thickness of the body and the thickness of the diaphragm. Top hat flexible meshing teeth characterized by being thicker than either Apparatus. 2. The top hat according to claim 1, wherein the thickness of the curved portion is thickest at the central portion of the curved portion and gradually decreases toward the body and the diaphragm. Type flexible meshing gear device.