JP4132113B2 - Flexure meshing gear unit - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a flexure meshing gear provided with a cup-shaped or top hat-shaped flexible external gear, and is capable of avoiding an inappropriate meshing state of the gear caused by the coning of the flexible external gear. The present invention relates to a meshing gear device.
[0002]
[Prior art]
As shown in FIG. 2 (A), a cup-type flexibly meshing gear device 1 includes an annular rigid internal gear 2, a cup-shaped flexible external gear 3 disposed on the inside, and the gear. And a wave generator 4 having an elliptical shape fitted inside. The cup-shaped flexible external gear 3 includes a cylindrical body portion 31, an annular diaphragm 32 extending continuously inward in the radial direction from one end of the body portion 31, and the diaphragm 32. It has a shape including a thick boss 33 continuing to the inner peripheral end and a tooth portion 34 continuing to the other end of the body portion 31, and external teeth are provided on the outer peripheral surface of the tooth portion 34. 35 is formed.
[0003]
The elliptical wave generator 4 includes an elliptical contour rigid cam plate 41 and a wave bearing 42 fitted to the outer peripheral surface of the cam plate 41, and the inner periphery of the tooth portion 34 of the flexible external gear 3. The rigid cam plate 41 is rotatable with respect to the flexible external gear 3 by the wave bearing 42 in the state of being fitted into the surface. The side of the rigid cam plate 41 is connected to a motor shaft or the like and rotates at a high speed. When the rigid cam plate 41 rotates at a high speed, the meshing positions of the two gears 2 and 3 that are bent elliptically by the rigid cam plate 41 and meshed at both ends of the long axis of the ellipse move in the circumferential direction. . There are usually two differences in the number of teeth of the two gears 2 and 3, and accordingly, a rotation that is greatly reduced in accordance with the difference in the number of teeth is generated between the two gears 2 and 3. Usually, the reduced speed rotation is taken out from the side of the output shaft fixed to the rigid internal gear 2 side and connected to the boss 33 of the flexible external gear 3.
[0004]
As a flexible external gear, a top hat-shaped gear is also known. In the flexible external gear of this shape, a diaphragm that is continuous with a cylindrical body portion spreads outward in the radial direction, and a thick-walled boss is formed continuously on the outer peripheral end of the diaphragm. It becomes the composition.
[0005]
[Problems to be solved by the invention]
Here, in a flexure meshing gear device having a cup-shaped or top hat-shaped flexible external gear, the flexible external gear is transformed into a three-dimensional complex flexure state called coning by a wave generator. Become. That is, the cup-shaped or top-hat-shaped flexible external gear has its teeth on the opening end side bent in an elliptical shape by an elliptical wave generator fitted therein. Therefore, as shown in FIG. 2 (B), on the long axis side of the ellipse, the tooth portion of the flexible external gear and the trunk portion continuous thereto are deformed to open outward with respect to the central axis. The ellipse is deformed so that it narrows inward in the radial direction on the short axis side. Due to the deformation of the flexible external gear, that is, coning, the meshing center of both gears is on the open end side of the flexible external gear on the long axis, and the barrel is further toward the short axis side. Move to the club side. Further, when the transmission load increases, the tooth portion bends in the direction in which the cornering angle decreases, and the meshing center of both gears moves.
[0006]
Therefore, in the cup-type flexure meshing gear device, there is a problem that uneven wear tends to occur at the tooth portions of both gears due to the coning of the cup-shaped flexible external gear. Moreover, it is generally necessary to correct the tooth profile of both gears so that the meshing center of both gears is in an appropriate position.
[0007]
On the other hand, since the wave generator deforms the flexible external gear in a three-dimensionally complex manner as described above, the bearing reaction force acting thereon is large. From the viewpoint of durability and the like, it is desirable to reduce the bearing reaction force.
[0008]
An object of the present invention is to pay attention to such points, and by reducing the amount of bending of a three-dimensional complex flexible external gear by coning, an appropriate meshing state can be formed and a wave bearing can be formed. An object of the present invention is to propose a flexibly meshing gear device capable of reducing the acting bearing reaction force.
[0009]
[Means for Solving the Problems]
Referring to FIG. 1, the flexure meshing gear device 5 of the present invention has an annular rigid internal gear 6 and a cup shape or a top hat shape as a whole, and external teeth 75 are formed on the opening end side. A flexible external gear 7 having a toothed portion 74, and the flexible external gear 7 is bent in the radial direction and partially meshed with the rigid internal gear 6 and the meshing position is set. In the one having the wave generator 8 moved in the circumferential direction, the tooth width L of the external tooth 75 of the flexible external gear 7 is in the range of 5 to 14% of the pitch circle diameter PCD of the external tooth 75. It is characterized by the inside dimensions.
[0010]
In addition, in the flexibly meshing gear device 5 of the present invention, in addition to the above features, the flexible external gear 7 includes a cylindrical body 71 continuous to the teeth 74, and the body In the continuous portion of the portion 71 to the tooth portion 74, an annular thin portion 76 is formed so as to be smoothly continuous with respect to an adjacent portion, and the minimum thickness t (min) of the thin portion 76 is The thickness is 30 to 80% with respect to the maximum thickness t (max) of the body portion.
[0011]
In the flexure meshing gear device of the present invention, since the tooth width L of the external tooth 75 of the flexible external gear 7 is shortened, it is a three-dimensional complex due to the coning of the flexible external gear 7. Unstable meshing of both gears can be eliminated. In other words, the meshing failure of both gears can be eliminated. Therefore, compared with the conventional case where a flexible external gear having a wide tooth width is used, the degree of correction of the tooth profile can be reduced and uneven wear of the tooth portion can be reduced. Further, along with the shortening of the tooth portion 74 of the flexible external gear 7, the tooth portion of the rigid internal gear 6 where the internal teeth 65 are formed can be shortened, and the wave generator 8 is also thin. Can be a thing. As a result, there is an advantage that the axial length of the flexure meshing gear device can be shortened.
[0012]
In the present invention, since the thin portion 76 is formed in the body portion 71 adjacent to the tooth portion 74 of the flexible external gear 7, the tooth portion 74 can be easily deformed in the radial direction. Therefore, the tooth portion 74 of the flexible external gear 7 can be bent into an ideal shape by the wave generator. At the same time, the reaction force of the wave generator to the wave bearing 82 can be reduced. In addition to this, there is also an advantage that the rigidity in the low load region of the flexure meshing gear device can be improved.
[Brief description of the drawings]
FIG. 1A is a schematic configuration diagram showing a cross-sectional configuration of a cup-type flexibly meshing gear device to which the present invention is applied, and FIG. 1B is a partially enlarged view thereof.
2A is a schematic configuration diagram showing a cross-sectional configuration of a general cup-type flexure meshing gear device, and FIG. 2B is an explanatory diagram showing coning of the cup-shaped flexible external gear. .
[Explanation of symbols]
5 flexure meshing gear device 6 rigid internal gear 7 cup-shaped or silk hat-shaped flexible external gear 71 body 74 tooth 75 external tooth 76 thin portion 8 wave generator 82 wave bearing L tooth width PCD external tooth Pitch circle diameter

Claims (1)

An annular rigid internal gear, a flexible external gear having a cup-shaped or silk-hat-shaped overall and having teeth formed on the opening end side, and the flexible external gear In a flexure meshing gear device having a wave generator that flexes in a radial direction and partially meshes with the rigid internal gear and moves the meshing position in the circumferential direction.
The tooth width of the external teeth of the flexible external gear is a dimension within a range of 5 to 14% of the pitch circle diameter of the external teeth ,
The flexible external gear includes a cylindrical body continuous with the tooth,
The continuous portion to the tooth portion of the body portion, so as to be continuous smoothly respectively the tooth bottom portion of the partial and adjacent the tooth portion of the body portion adjacent these parts of the adjacent body portion and An annular thin part thinner than the root part is formed,
The minimum thickness of the thin portion is flexible meshing type gear device, characterized in that 30 to 80% of the maximum thickness of the trunk portion.

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