JP2667209B2 - Harmonic gear device using permanent magnet - Google Patents

Description

Description: BACKGROUND OF THE INVENTION The present invention relates to a harmonic gear device, and more particularly, to a harmonic gear device utilizing an attractive force and a repulsive force by a permanent magnet.

[Conventional technology]

A typical harmonic gear device includes a rigid circular internal gear and an elliptical shape provided inside the circular internal gear so as to mesh with the circular internal gear at two places, and the number of teeth is smaller than the number of teeth of the circular internal gear. (H is a positive integer; hereinafter the same in the present specification). A small number of flexible external gears are fitted to the inside of the flexible external gears, and the flexible external gears are bent into an elliptical shape. The wave generator comprises an elliptical cam plate, and a ball bearing fitted on the outer periphery of the cam plate and deformed into an elliptical shape and bent. (The operating principle of the harmonic gear device is described in Japanese Patent Application No.
−316999).

In the harmonic gear device having such a configuration, when the input shaft provided on the cam plate of the wave generator is rotated, the elliptical shape of the flexible external gear is rotated. When the output shaft is provided relative to the circular internal gear or the flexible external gear, the output shaft rotates at a large reduction ratio with respect to the input shaft. As described above, the harmonic gear device is widely used for precision machines and the like because a large reduction ratio can be obtained with a small number of components.

As the harmonic gear device, a flexible external gear is formed into a cup shape to form a cup shape as a whole device, and two flat internal gears are arranged and arranged outside the annular external gear, There is a flat type as a whole, in which one internal gear has 2h more teeth than the external gear and the other internal gear has the same number of teeth as the external gear.

As the harmonic gear device, a rigid circular gear is used as an external gear and a flexible gear is used as an internal gear, and the operation principle is the same.

[Problems to be solved by the invention]

As described above, the wave generator includes an elliptical cam plate and a flexible ball bearing on the outer periphery thereof,
Thus, the flexible external gear is bent in an elliptical shape without directly rotating the flexible external gear, and only the elliptical shape is rotated to relatively rotate the circular internal gear and the flexible external gear. Have been. In the wave generator having this structure, a special flexible ball bearing is required on the outer periphery of the cam plate, so that the inertia mass of the entire apparatus is increased, the response characteristics are poor, and the price of the entire apparatus is expensive. . Furthermore, in this harmonic gear device, a flexible ball bearing determines the life of the device, and careful consideration is required for lubrication.

The limitation of the input rotation speed and the decrease in mechanical efficiency are largely due to the presence of the wave generator.

SUMMARY OF THE INVENTION An object of the present invention is to provide a harmonious structure in which a flexible gear can be held in an elliptical shape in a non-contact state by using a magnetic force of a permanent magnet in order to solve a problem caused by using a conventional wave generator. A gear device is to be realized.

[Means for solving the problem]

In order to achieve this object, in the harmonic gear device according to the present invention, instead of the wave generator, a flexible gear is formed into a desired shape by utilizing an attractive force generated between the same poles of the permanent magnet and a repulsive force generated between the different poles of the permanent magnet. It is made to transform into a shape. For this purpose, in the present invention, as shown in FIG.
Are continuously arranged at substantially equal intervals so that the N pole and the S pole are alternately arranged, and a rotor (concentrically arranged with the input shaft) arranged inside the flexible external gear 2 is provided. Disk-shaped thing)
Around the outer periphery of 5, permanent magnet pieces 4 are arranged continuously at substantially equal intervals so that N poles and S poles are alternately opposed to the permanent magnet pieces 3. The N and N poles or the S and S poles of the permanent magnet repel each other, and the N and S poles attract each other. For this reason, the permanent magnet pieces 3 and 4 are arranged so that the N pole and the N pole or the S pole and the S pole face each other at both ends in one diametric direction a of the rotor 5, and are orthogonal to the diametric direction a. If the permanent magnet pieces 3 and 4 are arranged so that the N pole and the S pole face each other at both ends in the diameter direction b, a repulsive force acts in the a direction and an attractive force acts in the b direction. As a result, the shape of the flexible external gear 2 can be changed to a substantially elliptical shape with the long axis in the direction a and the short axis in the direction b.

The deformation of the flexible external gear 2 into an elliptical shape needs to be maintained even when the rotor 5 rotates. Therefore, the number of magnets of the rotor 5 is 2n (n is a positive integer of 2 or more; the same applies hereinafter), and the number of magnets of the flexible external gear 2 is 2n-4 or 2n + 4.
If the N-pole and the N-pole or the S-pole and the S-pole face each other in one diameter direction even when the rotor 5 rotates, in the diameter direction orthogonal to the diameter direction, The north pole and the south pole can face each other. Under such an arrangement of magnetic poles, the rotor 5 rotates, and in one diametric direction e, the N pole and the N pole or the S pole and the S pole face each other, and in the diametric direction f orthogonal to the diametric direction e. If the N pole and the S pole face each other, the flexible external gear 2 has an elliptical shape with the long axis in the e direction and the short axis in the f direction,
The result is that the flexible external gear 2 itself does not rotate, but only the elliptical shape.

In this case, the rotation direction of the ellipse is the same as that of the rotor 5 when the number of magnets of the flexible external gear 2 is 2n-4,
When the number of magnets of the flexible external gear 2 is 2n + 4, the direction is opposite to that of the rotor 5.

In this way, the flexible external gear can rotate only the elliptical shape while maintaining the elliptical shape by the action of the repulsive force and the attractive force of the permanent magnet with the rotation of the rotor.

In this case, the rotation number T of the elliptical shape per one rotation of the rotor is n. If a large integer is selected for n, a small reduction ratio that cannot be obtained by the wave generator can be obtained.

The above is the case where the flexible gear is the external gear, the circular gear is the internal gear, and the rotor is disposed inside the flexible gear. Embodiments 1 and 2 described later take this case as an example, but the configuration of the present invention is not limited to this case. In addition to this case, the following three cases are also included in the configuration of the present invention.

(1) When the flexible gear is an external gear and the circular gear is an internal gear, and the rotor is arranged outside the flexible gear.

(2) A case where the flexible gear is an internal gear, the circular gear is an external gear, and the rotor is disposed inside the flexible gear.

(3) The case where the flexible gear is an internal gear and the circular gear is an external gear, and the rotor is arranged outside the flexible gear. A third embodiment described later takes this case as an example.

〔Example〕

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

As described above, the harmonic gear device includes a cup-type device and a flat-type device, but for convenience of explanation, the embodiment will be described for a cup-type device. Needless to say, it can be applied to a flat type.

(Embodiment 1) The embodiment 1 shown in FIGS.
A pole and a flexible external gear are provided with permanent magnet pieces of eight poles (corresponding to the case where n = 2 and the sign is +).

In FIG. 3 (a), since a magnet having the same polarity in the direction a and a different polarity in the direction b are opposed, the flexible external gear 2 has a long axis in the direction a, b
This shows a state in which the shape is deformed into an ellipse whose direction is a short axis. As shown in FIG. 3 (b), when the rotor rotates by 45 degrees, magnets having different polarities in the a-direction and magnets having the same polarity in the b-direction face each other. Deforms into an ellipse with the long axis in the direction b. Below, the rotor is 180 degrees, 270 degrees, 36
When rotated by 0 degrees, the elliptical shape is rotated as shown in FIGS. 3 (c), (d) and (e).

In this embodiment, the number of rotations of the elliptical shape per one rotation of the rotor is 2.

 The rotation direction of the elliptical shape is opposite to that of the rotor.

(Embodiment 2) Embodiment 2 shown in FIGS. 4 (a) and 4 (b)
A pole and a flexible external gear are provided with permanent magnet pieces of four poles (n = 4, corresponding to the case where the sign is-). This is an example in which the number of magnets of the rotor and the flexible external gear is replaced with that of the first embodiment.

In this embodiment, the number of rotations of the elliptical shape per one rotation of the rotor is 4.

 The rotation direction of the elliptical shape is the same as that of the rotor.

(Embodiment 3) Embodiment 3 shown in FIGS. 5 (a) and 5 (b)
A pole and a flexible external gear are provided with permanent magnet pieces of eight poles (corresponding to the case where n = 2 and the sign is +). In this embodiment, as described above, the flexible gear is an internal gear, the circular gear is an external gear, and the rotor is disposed outside the flexible gear as an example. The principle of operation is the same as in the previous two examples.

In this embodiment, the number of rotations of the elliptical shape per one rotation of the rotor is 2.

 The rotation direction of the elliptical shape is opposite to that of the rotor.

〔The invention's effect〕

According to the present invention, the use of a permanent magnet eliminates the need for a flexible ball bearing conventionally used for a wave generator, eliminates the problem of reduced response characteristics due to an increase in inertial mass, and reduces the cost of the entire apparatus. Down becomes possible.

In addition, since a wave generator becomes unnecessary and the flexible gear can be bent in an elliptical shape in a non-contact state, consideration for wear and oil lubrication of a wave bearing, which has been a problem in the past, becomes unnecessary. The life efficiency is improved, and problems such as the limitation of the rotation speed of the input shaft are eliminated.

Further, as described above, since a small reduction ratio that cannot be obtained by the wave generator can be obtained according to the number of magnets of the rotor and the flexible gear, the present invention is more applicable to a device than a case using a gear. Is improved. In addition, the flexible gear and the circular gear can be selected as either an external gear or an internal gear, and the rotor can be disposed inside or outside the flexible gear. Has contributed.

[Brief description of the drawings]

 1 is a front view of a harmonic gear device according to the present invention, FIG. 2 is a longitudinal sectional view of the harmonic gear device of FIG. 1, FIGS. 3 (a) to 3 (e) are front views of the first embodiment, 4A and 4B are front views of the second embodiment, and FIGS. 5A and 5B are front views of the third embodiment. [Description of Symbols] 1 ... Circular gear 2 ... Flexible gear 3 ... Permanent magnet piece (first permanent magnet group) 4 ... Permanent magnet piece (second permanent magnet group) 5 ... Rotator

Claims (4)

(57) [Claims] 1. A rigid circular gear, and a flexible ring-shaped gear meshable with the circular gear, wherein the flexible gear is deformed into an elliptical shape to partially form the circular gear. In the harmonic gear device, which meshes with each other and moves the meshing position of these two gears along the circumferential direction to cause relative rotation between the circular gear and the flexible gear in accordance with the difference in the number of these teeth, A rotor is arranged inside the flexible gear, and a first group of permanent magnets is N around the inside of the flexible gear.
The poles and the S poles are continuously attached at equal intervals so that the poles and the S poles are alternately arranged. Around the outer periphery of the rotor, a second group of permanent magnets is equidistantly arranged such that the N poles and the S poles alternate. On one axis on an orthogonal axis passing through the center of rotation of the rotor, magnets of the same polarity of the first and second permanent magnet groups face each other and are orthogonal to each other. Wherein the permanent magnets are arranged such that magnets of different polarities of the first and second permanent magnet groups face each other. 2. The permanent magnet piece included in the second permanent magnet group, wherein the number of permanent magnet pieces included in the first permanent magnet group is 2n ± 4 (n is a positive integer of 2 or more). The harmonic gear device according to claim (1), wherein the number is 2n. 3. A rigid circular gear, and a flexible ring-shaped gear meshable with the circular gear, and the flexible gear is deformed into an elliptical shape to partially form the circular gear. In the harmonic gear device, which meshes with each other and moves the meshing position of these two gears along the circumferential direction to cause relative rotation between the circular gear and the flexible gear in accordance with the difference in the number of these teeth, A rotor is arranged outside the flexible gear, and a first group of permanent magnets is N around the outside of the flexible gear.
The poles and the S poles are continuously attached at equal intervals so that the poles and the S poles are alternately arranged. Around the inside of the rotor, a second group of permanent magnets is equidistantly arranged such that the N poles and the S poles alternate. On one axis on an orthogonal axis passing through the center of rotation of the rotor, magnets of the same polarity of the first and second permanent magnet groups face each other and are orthogonal to each other. Wherein the permanent magnets are arranged such that magnets of different polarities of the first and second permanent magnet groups face each other. 4. The number of permanent magnet pieces included in the first permanent magnet group is 2n ± 4 (n is a positive integer of 2 or more), and the number of permanent magnet pieces included in the second permanent magnet group is The harmonic gear device according to claim 3, wherein the number is 2n.