JP3086233B2 - Friction transmission type harmonic transmission - Google Patents

Description

Description: BACKGROUND OF THE INVENTION [0001] The present invention relates to a harmonic transmission, and more particularly, to a friction transmission type harmonic transmission that performs a shifting operation by a friction transmission mechanism.

[Prior Art] As a transmission mechanism for reducing high-speed rotation output from a motor or the like and extracting it as low-speed rotation output, a gear transmission type harmonic transmission and a friction transmission type harmonic transmission are known. This friction transmission type harmonic transmission is generally provided with an annular rigid member, an annular elastic member disposed inside the annular rigid member, and capable of circumscribing the inner peripheral surface of the annular rigid member, and an annular rigid member arranged inside the annular elastic member. And a wave generator having an elliptical cam plate. The annular elastic member is bent into an elliptical shape by the wave generator, and portions located at both ends of the major axis thereof are brought into frictional contact with the annular rigid member. Then, the wave generator is rotated at a high speed by a motor or the like, and accordingly, the elliptical shape of the annular elastic member rotates, and the frictional contact position between the elastic member and the rigid member moves in the circumferential direction. Along with such a movement of the friction contact position, a relative rotation occurs between the elastic member and the rigid member in accordance with the difference between the outer peripheral length and the inner peripheral length. Therefore, if one of the elastic member and the rigid member is fixed and the other is set as the rotation output element, a reduced rotation output can be obtained from the rotation output element.

[Problems to be Solved by the Invention] However, in such a friction transmission type harmonic transmission, power transmission is performed by frictional contact between the outer peripheral surface of the elastic member and the inner peripheral surface of the rigid member. . The power transmission characteristics due to such frictional contact fluctuate in accordance with the contact pressure between the surfaces, but it is difficult to maintain such a contact pressure at a constant value. Easy to do. Further, the torque transmission force is smaller than that of a gear type harmonic transmission in which power transmission is performed by meshing between an elastic external gear and a rigid internal gear, so that the applicable range is narrow. Furthermore, if wear occurs in the frictional contact part due to long-term use, etc., the contact pressure between them will decrease,
Transmission force due to frictional contact between them also decreases.

In view of the foregoing, an object of the present invention is to realize a friction transmission-type harmonic transmission capable of reliably transmitting relatively high power.

[Means for Solving the Problems] In order to solve the above problems, in the friction transmission type harmonic transmission according to the present invention, the friction contact surface between the annular rigid member and the annular elastic member disposed inside the annular rigid member is conical. A configuration is adopted in which the annular rigid member is pressed in the axial direction by a pressing member such as a coil spring so that the annular rigid member is set in a shape or an hourglass shape, and is brought into contact with each other.

That is, the friction transmission type harmonic transmission according to the present invention is:
First and second annular rigid members arranged in parallel at a fixed interval in a coaxial state; and facing the second annular rigid member formed on an inner peripheral surface of the first annular rigid member. A first conical inner peripheral surface inclined outward in the radial direction, and a first conical inner peripheral surface formed on an inner peripheral surface of the second annular member.
A second conical inner peripheral surface inclined outward in the radial direction toward the side of the annular rigid member, and inside the first and second annular rigid members,
An annular elastic member arranged coaxially with these, and a circumscribed surface of the first conical inner peripheral surface formed at a portion of the outer peripheral surface of the annular elastic member facing the first conical inner peripheral surface. A possible first conical outer peripheral surface, and a portion formed on a portion of the outer peripheral surface of the annular elastic member facing the second conical inner peripheral surface, which can be circumscribed to the second conical inner peripheral surface. A second conical outer peripheral surface, disposed inside the annular elastic member, bending the annular elastic member outward in the radial direction so that the first and second conical outer peripheral surfaces face each other; A wave generator for bringing the first and second conical inner peripheral surfaces of the annular rigid member into contact with each other at a plurality of positions in the circumferential direction, and moving these contact portions in the circumferential direction; A second conical inner peripheral surface is provided on the first and second conical outer peripheral surfaces, respectively. The first annular rigid member, and a pressing member that presses the annular elastic members in their axial direction via the first annular rigid member so as to be in a pressed state; And the mean diameter of the second conical inner peripheral surface is different from each other.

Embodiment An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows a flat type harmonic transmission according to an embodiment of the present invention. The harmonic transmission 11 of this example has a configuration in which each component is incorporated in a cylindrical case 12. That is, the first rigid member 13 is fitted into the inner peripheral surface of the large-diameter cylindrical portion 12a of the case in a non-rotatable state via the rotation stopping member 16. On the side of the first rigid member 13 on the side of the small-diameter cylindrical portion 12c of the case, a second rigid member 23 is disposed coaxially at a predetermined interval.
The rigid member 23 is integrally formed on an outer peripheral portion of the disk member 24, and an output rotary shaft 25 is integrally formed on the other side of the disk member 24 coaxially. This output rotary shaft 25
Protrudes outward through the small-diameter cylindrical portion 12c of the case, and is rotatably supported on the side of the case via a ball bearing 17 at the small-diameter cylindrical portion 12c. The back side of the disk member 24 is supported via a bearing 26 on the side of an annular inner peripheral end face 12e formed between the large-diameter cylindrical portion 12a and the small-diameter cylindrical portion 12c of the case. .

Here, the inner peripheral surface of the first rigid member 12 is a first conical surface 13a that spreads toward the side of the second rigid member 23. On the other hand, the inner peripheral surface of the second rigid member 23 is a second conical surface 23a that expands toward the first rigid member 13.

Next, an elastic member 14 is disposed coaxially inside the first and second conical surfaces 13a and 23a. The outer peripheral surface of the elastic member 14 has a first conical surface 14 circumscribing the conical surface at a portion facing the first conical surface 13a.
a is formed. A portion facing the second conical surface 23a has a second conical surface circumscribing the conical surface.
14b is formed.

A wave generator 15 is arranged coaxially inside the elastic member 14. The wave generator 15 includes an elliptical rigid cam plate 15a, a ball bearing 15b fitted on the outer periphery thereof, and an input rotary shaft 15c integrally formed coaxially with the rigid cam plate 15a. I have. Input rotary shaft 15c
Is rotatably supported on the inner peripheral surface of the small-diameter cylindrical portion 12b of the case via a ball bearing 18. By the wave generator 15 having this configuration, the elastic member 14 is bent in a muddy circular shape, and the first and second conical surfaces 14a and 14b located at both ends in the long axis direction face each other. The rigid member is pressed against the first and second conical surfaces 13a and 23a with a constant force.

Here, a coil spring 19 is compressed between the annular end surface 13b of the first rigid member 13 on the side of the case small-diameter portion 12b and the annular end surface 12d of the case opposed thereto. It is arranged. By the coil spring 19, the first rigid member 13 is always pressed in the axial direction toward the second rigid member 23.

In the harmonic transmission 11 having this configuration, when the wave generator 15 rotates, the wave generator 15 rotates, and accordingly, the side of the elastic member with respect to the first and second conical surfaces 13a and 23a formed on the inner peripheral surface of the rigid member. The contact positions of the first and second conical surfaces 14a, 14b move in the circumferential direction. As a result, relative rotation occurs between these members, and reduced rotation is obtained from the output rotation shaft 25 integrally formed with the second annular elastic member 23.

The reduction ratio in the transmission of this example can be expressed by the following equation.

Ds1: average diameter of the first conical surface 13a of the rigid member Ds2: average diameter of the second conical surface 23a of the rigid member Df1: first conical surface 13a of the first conical surface 14a of the elastic member in a perfect circle state Average diameter of the contact portion with the second conical surface 14b of the elastic member in a perfect circle state Df2: average diameter of the contact portion of the elastic member with the second conical surface 23a in the perfect circular state The frictional contact with the elastic member 14 is formed by the conical surfaces 13a, 23a and 14a, 14b formed on both sides. Therefore, in the case of conventional cylindrical surfaces, a contact pressure is not generated even when a thrust force is applied from one side, but in the case of conical surfaces, when a thrust force is applied from one side, a contact pressure perpendicular to the conical surface is generated. Thereby, the frictional force between the conical surfaces increases, and a high transmission characteristic can be obtained. Further, in this example, the conical surfaces in contact with each other are constantly pressed with a constant force by the coil spring 19. For this reason, the parts of the two conical surfaces that are in contact are always kept in reliable contact. Therefore, stable power transmission characteristics can always be obtained. As described above, according to the harmonic transmission of this example, it is possible to transmit power more reliably and to obtain higher power transmission characteristics than in the related art.

In the above example, the elastic member is bent into an elliptical shape so that the elastic member comes into frictional contact with the rigid member at two portions in the circumferential direction. However, the elastic member may be deflected so as to make frictional contact with the rigid member at three or more portions. In general, when the number of contact points is increased, the contact pressure at each contact point is reduced. This is preferable because the equalization is performed and the inclination of the rigid member hardly occurs.

In the above example, the contact surface is a conical surface.
For example, a slightly curved tapered surface may be employed as the contact surface instead. Therefore, in this specification, when simply referring to a conical surface, it means a shape including these shapes.

[Effects of the Invention] As described above, in the present invention, the contact surface between the rigid member and the elastic member is a conical surface, and the conical surfaces are pressed by the pressing member in a direction in which they contact each other. Like that. Therefore, according to the present invention, the rigid member and the elastic member can be kept in a state of being always in reliable contact with each other, and a large power can be transmitted, as compared with the related art.

[Brief description of the drawings]

FIG. 1 is a schematic longitudinal sectional view showing a friction transmission type harmonic transmission according to an embodiment of the present invention. [Description of Signs] 11 Harmonic transmission 12 Cases 13 and 23 Rigid members 13a and 23a Conical surface 14 Elastic members 14a and 14b Conical surface 15 Wave generators 17 and 18 …… Ball bearing 19 …… Coil spring

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) F16H 13 / 08,13 / 10

Claims (1)

(57) [Claims] 1. A first and a second annular rigid member arranged in parallel at a predetermined interval in a coaxial state, and a second annular rigid member formed on an inner peripheral surface of the first annular rigid member. A first conical inner peripheral surface inclined outward in the radial direction toward the member side; and a first conical inner member formed on an inner peripheral surface of the second annular member. A radially outwardly inclined second conical inner peripheral surface, an annular elastic member disposed inside and coaxial with the first and second annular rigid members, and an annular elastic member. A first conical outer peripheral surface formed at a portion of the outer peripheral surface facing the first conical inner peripheral surface, the first conical outer peripheral surface being circumscribed to the first conical inner peripheral surface; and an outer periphery of the annular elastic member. The second conical inner peripheral surface is formed at a portion of the surface facing the second conical inner peripheral surface. A second conical outer peripheral surface that can be circumscribed, and an outer peripheral surface that is disposed inside the annular elastic member and that flexes the annular elastic member outward in the radial direction so that the first and second conical outer peripheral surfaces are bent. A wave generator configured to contact the first and second conical inner peripheral surfaces of the annular rigid member with each other at a plurality of positions in the circumferential direction, and to move these contact portions in the circumferential direction; The first and second conical inner peripheral surfaces are respectively the first and second conical inner peripheral surfaces.
And a pressure for pressing the first annular rigid member and the annular elastic member via the first annular rigid member in the axial direction thereof so as to be pressed against the second conical outer peripheral surface. A friction transmission type harmonic transmission comprising: a first member and a second conical inner peripheral surface having different average diameters;