JPH0129308Y2 - - Google Patents

Description

[Detailed description of the invention] A. Purpose of the invention Industrial application field This invention relates to a transmission device used in rotating equipment that requires deceleration.

BACKGROUND ART At present, a transmission called a harmonic drive is known, and its outline is shown in FIGS. 7 and 8. This harmonic drive consists of a circular spline 1, a flexspline 2, and a wave generator 3. The circular spline 1 is a rigid body formed in the shape of a ring, and has spline-like teeth 1a carved on its inner peripheral surface. The flex spline 2 is made of an elastic material and is formed into a thin cup shape, and an even number of teeth 2a of the same pitch as the circular spline 2, for example, 2 teeth fewer than the teeth 1a of the circular spline 2, are carved on the outer peripheral surface of the flex spline 2. are doing. As shown in FIG. 8, the wave generator 3 is composed of an elliptical cam 4 and a ball bearing 5 fitted on the outer peripheral surface of the cam 4, and has an elliptical overall shape. When the flexspline 2 is fitted to the wave generator 3, the flexspline 2
Since it is an elastic body, it can be bent into an elliptical shape. Then, the long axis diameter of the ellipse formed by the pitch points of the teeth 2a of the flexspline 2 is made equal to the pitch circle diameter of the teeth 1a of the circular spline 1, and the teeth 1a of the circular spline 1 and the teeth 2a of the flexspline 2 are meshed. Ru.

In the above configuration, when the circular spline 1 is fixed and the wave generator 3 is rotated with the flex spline 2 on the output side, the flex spline 2 is elastically deformed, and the circular spline 1
The meshing position of the flexspline 2 and the flexspline 2 sequentially move, and as shown in FIGS. It rotates at a reduced speed in the opposite direction to the wave generator 3 by the difference in the number of teeth. Also, when the flexspline 2 is fixed and the wave generator 3 is rotated with the circular spline 1 on the output side, the circular spline 1 will move in the same direction as the wave generator 3 by the difference in the number of teeth with the flexspline 2. Rotate at a reduced speed.

Problems that the invention aims to solve By the way, the reduction ratio of harmonic drives currently on the market is around 1/50 to 1/300.
It is difficult to achieve a low reduction ratio of 1/50 or less.
For a low reduction ratio, use flexspline 2
Since the oblateness (ellipticity ratio) of This is because there is a limit to the low reduction ratio.

B. Means for solving problems in the structure of the invention This invention consists of a shaft, an elliptical shaft arranged coaxially with the shaft and having a bearing fitted on its inner circumference, and an elliptical shaft arranged on its inner circumference and arranged on its outer circumference. A wave generator integrally formed with an elliptical shaft with a bearing fitted on the surface with a phase shift of 90 degrees on the coaxial line, a case rotatably arranged around the shaft and the wave generator, and a flexible member. is formed into a thin cylindrical shape, one end of which is fixed to the inner periphery of the case, the other end of which is bent and fitted into the elliptical ring of the wave generator, and teeth are provided on the inner periphery of the wave generator. 1st to have
formed into a thin cup shape by a flex spline and a flexible member, one end of which is fixed to the shaft,
a second flexspline whose other end is bent into an elliptical shape and fitted to the elliptical axis of the wave generator, and has teeth on its outer peripheral surface that engage with the teeth of the first flexspline at two points opposite to each other; It is composed of the following.

Embodiment FIGS. 1 and 2 are drawings showing an embodiment of the transmission device of this invention.

1 and 2, 11 is a cylindrical case of this transmission, 12 is a shaft rotatably supported within the case 11 via two ball bearings 13, 14, and 15 is a cylindrical case of this transmission. A wave rotatably supported within the case 11 via two ball bearings 16 and 17 attached to the shaft 12 and a bearing metal 20 attached to a cover plate 19 fixed to the open end of the case 11 with bolts 18. In the generator, an elliptical ring 22 with a needle bearing 21 fitted on the inner peripheral surface and an elliptical ring 22 with a needle bearing 23 fitted on the outer peripheral surface.
2 and an elliptical shaft 24 coaxially with a phase shift of 90 degrees. Reference numeral 25 denotes a first flexspline made of a flexible member and formed into a thin cylindrical shape, one end of which is fixed to the case 11 with a bolt 26, and the other end is attached to the elliptical ring 22 of the wave generator 15 in an elliptical shape. It is bent and fitted, and spline-shaped teeth 25a are carved on the inner circumferential surface thereof. Reference numeral 27 denotes a second flexspline made of a flexible member and formed into a thin cup shape, one end of which is fixed to the shaft 12 with a bolt 28, and the other end is connected to the elliptical shaft 24 of the wave generator 15 in an elliptical shape. Teeth 2 of the same pitch as the teeth 25a of the first flexspline 25 are fitted on the outer circumferential surface of the first flexspline 25.
7a is engraved. Then, the diameter of the major axis of the ellipse formed by the pitch points of the teeth 27a of the second flexspline 27 and the teeth 25 of the first flexspline 25
The minor axis diameters of the ellipse formed by the pitch points a are made equal, and the teeth 25a of the first flexspline 25 and the teeth 27a of the second flexspline 27 are engaged at two opposing points.

Next, the operation of the transmission in the above configuration will be explained. When the case 11 is fixed and the wave generator 15 is rotated with the shaft 12 on the output side, the first flexspline 25 and the second flexspline 27 are elastically deformed, and the teeth 25a of the first flexspline 25 and The meshing position of the teeth 27a of the second flexspline 27 moves sequentially,
Due to the difference in the number of teeth between the two, as shown in FIGS. 3 to 6, when the wave generator 15 rotates once, the second flexspline 27 waves by the difference in the number of teeth from the first flexspline 25. It will decelerate and rotate in the opposite direction to the generator 15,
This rotation will be transmitted to the shaft 12.

As mentioned above, the reduction ratio when the rotation of the wave generator 15 is transmitted to the shaft 12 is as follows: If the number of teeth of the first flexspline 25 is Zo, and the number of teeth of the second flexspline 27 is Zi, then reduction ratio = The number of revolutions of the shaft 12/the number of revolutions of the wave generator 15 = Zo−Zi/Zi.

Furthermore, when the shaft 12 is fixed and the wave generator 15 is rotated with the case 11 on the output side,
The case 11 connects the first flexspline 25 and the second
The wave generator 15 rotates at a reduced speed in the same direction as the wave generator 15 by the difference in the number of teeth between the wave generator 15 and the flex spline 27 .

C. Effect of the invention According to this invention, as is clear from the above formula,
Without increasing the flatness of the flexspline (Zo
-Zi) can be increased and a low reduction ratio can be achieved, so it is possible to realize a transmission device that has a large allowable torque, is compact, and can obtain a low reduction ratio.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view showing the transmission of this invention;
Figure 2 is a cross-sectional view taken along line A-A in Figure 1;
Figures 6 to 6 are drawings showing the principle of deceleration of the transmission of this invention, Figure 7 is a longitudinal sectional view showing a conventional harmonic drive, and Figure 8 is a cross section taken along line B-B in Figure 7. 9 to 12 are diagrams showing the deceleration principle of a conventional harmonic drive. 11... Case, 12... Shaft, 15... Wave generator, 21... Needle bearing, 22...
...Elliptical ring, 23...Needle bearing, 24...Elliptical shaft, 25...First flex spline, 25a...
...first flexspline tooth, 27...second flexspline, 27a...second flexspline tooth.

Claims (1)

[Scope of utility model registration request] A shaft, an elliptical ring placed coaxially with the shaft and having a bearing fitted on its inner circumferential surface, and an elliptical shaft placed on its inner circumference and having a bearing fitted on its outer circumferential surface coaxially.
A wave generator integrally formed with a phase shift of 90 degrees, a case rotatably arranged around the shaft and the wave generator, and a flexible member formed into a thin cylindrical shape, one end of which is connected to the case. fixed to the inner periphery, and the other end is bent into an elliptical shape and fitted into the elliptical ring of the wave generator,
and a first flexspline having teeth on its inner circumferential surface and a flexible member formed into a thin cup shape, one end of which is fixed to the shaft, and the other end is elliptical to the elliptical shaft of the wave generator. A transmission comprising a second flexspline which is bent to fit into the second flexspline and has teeth on its outer circumferential surface that mesh with the teeth of the first flexspline at two points facing the teeth of the first flexspline.