JPS60241550A - Deflection engagement type power transmission apparatus - Google Patents

Abstract

PURPOSE:To eliminate the necessity of high precision in working and assembly on the installation side by using a deflection external gear in thin cylindrical form which is incorporated onto the outer periphery of a wave generator and an internal gear meshed with the external gear. CONSTITUTION:An internal gear 8 is fixed onto a body side 19, and an internal gear 9 is fixed onto a trailing side 20, and a wave generator 16 is connected to an input shaft 21. A deflection external gear 10 is incorporated onto the outer peripheral part of the wave generator 16 and deflected in elliptical form, and meshed with the internal gears 8 and 9 in the direction of major axis. The gears 8 and 9 are revolved by the revolution drive of the input shaft, shifting each engagement point and making the differential revolution due to the difference of the number of teeth, and the trailing side 20 forms reduced-speed revolution for the body 19 side. Thus, the internal gears 8 and 9 having different number of teeth and the deflection external gear 10 can be meshed in optimum ways without utilizing the dislocation of gear.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a flexible mesh type power transmission device known by the trade name Harmonic Drive (registered trademark) and used as transmission power in various mechanical devices.

The structure of the conventional example and its problems In the conventional flexible mesh type power transmission device, Fig. 1 and Fig. 2
As shown in Figs. 3 and 3, the wave generator 1 has a ball bearing attached to the outer periphery of a cam with an elliptical outer periphery and a boss, and two internal gears with a slight difference in the number of teeth. 2, 3, and a thin cylindrical flexible external gear 4.

In its use, an internal gear 2 is fixed to the main body side 6, an internal gear 3 is fixed to the driven side 6. A wave generator 1 is fixedly connected to an input shaft 7, and an outer flexure that fits into the wave generator 1 on the inner circumference, is bent in an elliptical shape, and meshes with two internal gears 2 and 3 on the long axis side of the ellipse. It is assembled with gears 4.

In its operation, the wave generator 1 is driven by an input shaft 7 at N rpm, and a flexible external gear 4 and two internal gears 2 and 3 mesh with each other on the long axis side of the wave generator 1.
The rotational force is transmitted to the fixed side internal gear tooth number z4. In the driven side internal gear Z2, the driven side rotational speed N2 is reduced to the rotational speed expressed by the following formula.

However, in the above configuration, when the two internal gears 2 and 3 having different numbers of teeth mesh with the flexible external gear 4, one
In order to mesh with the wave generator 1 consisting of two cams, dislocation is used in the gears to achieve backlash-free meshing, so the gears wear and bank lash occurs, resulting in a short service life. It does not have an adjustment mechanism for concentric misalignment during assembly of the gears 2, 3 and the wave generator 1, which causes torque fluctuations of the input shaft and speed fluctuations of the output shaft during driving. Further, during driving, an axial force is generated against the flexible external gear 4, causing friction between the main body and the end face of the flexible external gear 4, which is a main cause of reduced efficiency.

purpose of invention In view of the above drawbacks, the present invention improves the processing accuracy on the mounting side.

The present invention provides a highly efficient flexible mesh power transmission device that does not require assembly precision, has a long life, and has little wear.

Composition of the Invention The flexible mesh power transmission device of the present invention is a wave gear transmission device that is composed of a boss that connects an input shaft, and two elliptical cams of different shapes that are attached to the boss and that have ball bearings attached to their outer peripheries. generator, a thin cylindrical flexible external gear built into the outer periphery of the wave generator and bent into an elliptical shape, and two minute numbers of teeth that mesh with the flexible external gear at two points on the long axis side of the elliptical cam. It is composed of internal gears with different differences.

The wave generator is rotated by driving the input shaft, and the flexible external gear and the two internal gears are rotated while moving their meshing points, and the two internal gears perform differential rotation due to the difference in the number of teeth. It is something that does.

At this time, the two elliptical cams have the most suitable shape for meshing with the flexural gear and the two internal gears, and have the unique effect of reducing tooth wear and high efficiency.

DESCRIPTION OF EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 4 shows an exploded view of a flexible mesh type power transmission device according to an embodiment of the present invention.

In Fig. 4, 8 and 9 are two internal gears with a slight difference in the number of teeth, 10 is a thin-walled cylindrical flexible external gear with a convex portion 10' on the inner circumference, and 11 is a flange surface with an angle. The grooved bosses 11a and 12b are two cams 13 having different oval shapes and having a ball bearing on the outer periphery and a square groove on the end surface.
Numerals a and 13b are ring-shaped joints having square projections perpendicular to both end faces, and together with the boss 11 and cams 13a and 13b constitute an Oldham joint. 14! L, 1 +b
The spacers 151L and 15b are retaining rings, and the boss 11 has joints 13a and 13b and cams 12a and 12b.
Spacers 14a, 14b retaining rings 1611L, 15
The boss 11 and the cam 12 are connected by b.
L.

12b, joints 13a, 13b, spacer 14&.

14b, retaining rings 15a, and 15b are called a wave generator 16. Wave Ze Generator 1
6 is the inner peripheral part of the flexible external gear 1o, and two cams 121L
, 12b has an outer diameter that fits into the inner diameter of the flexible external gear 1Q, so that the flexible external gear 10 is bent into an elliptical shape, and the inner circumferential convex portion is inserted between the outer diameter and the outer diameter of the flexible external gear 1Q.

The flexible external gear 1o, which is bent into an elliptical shape by two different shaped elliptical cams 12a and 12b, is connected to two internal gears 8. at two points on the long axis side. It meshes with S. Oval cam 12 at this time
The shapes of a and 12b are shown in FIG. In FIG. 6A, 16 is the reference pitch circle of the internal gear 8 with a large number of teeth.
Reference numeral 17 indicates a reference pitch circle for the internal gear 9 with a small number of teeth, and reference numeral 18 indicates a reference pitch circle for the flexible external gear teeth 10.
The reference pitch circle has the smallest diameter among the three gears.In order to mesh the reference pitch circle 18 of the flexible external gear 10 with the two internal gears 8.9, As shown in Figures 6B and 0, the cams 12a and 12b are bent in an elliptical shape, and the long axis thereof is the same size as the reference pitch circle of the internal gears 8 and 9, and the elliptical cams 12a and 12b are set in this way. It is something that exists.

Regarding the flexible mesh power transmission device configured as described above, its incorporation into an actual machine and its operation will be described below. 6th
In the figure, an internal gear 8 is fixed to the main body side 19, an internal gear 9 is fixed to the driven side 20, and a wave generator (boss 11, cams 12L, 12b, joint 13) is fixed to the input shaft 21.
2L, 13b) 16 are connected to each other, and the flexible external gear 10 is built into the outer circumference of the wave generator 16, is bent into an ellipse, and meshes with the internal gears 8 and 9 in the longitudinal direction. Due to the rotational drive of the input shaft, the internal gear 8,
9 are rotated while moving their meshing points, and differential rotation is performed due to the difference in the number of teeth, and the driven side 20 is caused to perform deceleration rotation with respect to the main body side 19.

In this way, two elliptical cams 12 &
, 12b, the internal gears 8, 9 having different numbers of teeth and the flexible external gear 1o can be optimally meshed without using gear dislocation, resulting in less gear wear and longer life.

In the above configuration, the cams 12&, 12b are connected to the input shaft 21 by an Oldham joint, and the input shaft 21
The torque fluctuations of the input shaft 21 are uniformized and reduced by automatically responding to misalignment of the internal gears 8 and 9, and furthermore, since the torque is transmitted at a constant angular velocity, speed fluctuations on the longitudinal side are avoided.

The convex portion 10' on the inner circumferential surface of the flexible external gear 10 is sandwiched between the bearings of the two cams 12L and 12b with a slight gap between them, thereby preventing the flexible external gear 10 from moving in the axial direction. This prevents friction of the end surface of the flexible external gear 10 against the main body side 19 and the driven side 2o, thereby reducing wear and torque loss.

As described above, two elliptical cams with different shapes are used,
Since the structure meshes an internal gear with a small difference in the number of teeth and a flexible external gear, the meshing of each gear can be optimized, resulting in a long service life and an Oldham coupling. This configuration eliminates torque unevenness and speed fluctuations caused by mounting accuracy and achieves high accuracy.

[Brief explanation of drawings]

Figure 1 is an exploded perspective view of a conventional flexible mesh power transmission device.
Fig. 2 is a diagram of the same engagement, Fig. 3 is a sectional view of the same, Fig. 4 is an exploded perspective view of an embodiment of the present invention, Fig. 6 is an explanatory diagram of the same engagement, and Fig. 6 is an illustration of the same engagement. FIG. 1 is a sectional view of a flexible mesh power transmission device according to an embodiment of the invention. 1...Wave Ze Generator, 2, 3...
・・Internal gear, 4・・Flexible external gear, 8, 9・
...Internal gear, 1o...Flexible external gear,
11...Boss, 12a. 12b...Cam, 131L, 13b...
・Joints. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 5 Figure 6

Claims (3)

[Claims] (1) A wave generator consists of a boss that connects the input shaft, two elliptical cams of different shapes with ball bearings attached to the outer periphery attached to the boss, and two cams with a slight difference in the number of teeth. A flexible mesh power transmission device comprising two internal gears and a thin-walled cylindrical flexible external gear. (2) The flexible mesh power transmission device according to claim 1, wherein the two elliptical cams are each connected to the boss through an Oldham joint via a 9-way pin. (3) The flexible mesh type power transmission device according to claim 1, wherein the flexible external gear has a convex portion on the inner circumferential portion to limit movement in the axial direction with respect to the wave generator.