JPH0577901B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field of the Invention The present invention relates to a planetary roller type power transmission device that transmits power by the frictional force of planetary rollers.

TECHNICAL BACKGROUND OF THE INVENTION As a conventional planetary roller type power transmission device of this type, one used as a speed reducer is known, for example, as disclosed in Japanese Utility Model Application Laid-Open No. 58-80659. This known structure includes a steel sun wheel directly connected to an input shaft that is rotationally driven, a steel fixed ring with a concave cross section fitted and fixed to the inner periphery of the housing, and an outer periphery of the sun wheel and an inner periphery of the fixed ring. It consists of a plurality of planetary rollers that come into contact with the output shaft, and a plurality of planetary shafts provided in the axial direction at the end of the output shaft. The fixed shaft, which has a concave cross section, is axially tightened from both sides and its inner diameter is crowned, so that the fixed ring, the plurality of planetary rollers, and the sun ring can mutually radially rotate. The rotational driving force from the input shaft is decelerated and transmitted to the output shaft by the friction force generated by this pressure contact.

Problems with the Background Art In conventional devices, the fixed ring, which has a concave cross section, has its inner diameter deformed in a crowning manner by tightening both sides, so the fixed ring comes into pressure contact with the planetary roller under tensile stress. Become. Therefore, during use of the device, the fixed ring is in a state of being extremely vulnerable to the repeated stress it receives from the pressure contact of the planetary rollers, and as a result, the fixed ring is prone to premature peeling due to fatigue on its inner peripheral surface. It has the disadvantage of shortening its lifespan.

OBJECT OF THE INVENTION The object of the present invention is to improve the life of fixed wheels in a planetary roller power transmission device.

Summary of the Invention In order to achieve the above object, the present invention has the following features:
A plurality of planetary rollers are arranged between the outer periphery of the sun ring provided on the first rotating shaft and the inner periphery of the fixed ring fitted and fixed to the aluminum die-cast housing, each abutting both circumferential surfaces. In a planetary roller type power transmission device in which each planetary roller is supported by a planetary roller support member fixed to a second rotating shaft, power is transmitted between the two rotating shafts, the following Take a configuration like this.

In the planetary roller type power transmission device of the present invention, the fixed ring has a multilayered shape by concentrically stacking a plurality of cylindrical rings, and the innermost cylindrical ring among the plurality of cylindrical rings is the outermost cylindrical ring. It is characterized by being polymerized so that it receives centripetal compressive stress only when it is tightened to the cylindrical ring, and that the outermost cylindrical ring is fixed internally so as not to apply tensile stress to the housing. has.

Embodiment of the Invention FIGS. 1 and 2 show an embodiment in which the present invention is used as a speed increaser.

1 is an input shaft, 2 is an output shaft, 3 is a sun ring provided at one end of the output shaft 2 by a key 7 or the like (of course, the sun ring 3 may be formed integrally with one end of the output shaft 2), Reference numeral 5 indicates a fixed ring which is fitted and fixed to the inner circumferential surface of the housing 4 and has a double shape of an inner cylindrical ring 5a and an outer inner cylindrical ring 5b; In this case, it is a planetary shaft screwed in the axial direction with 3 pieces). Thereby, the planetary shafts 6 are fixed to the input shaft 1 at equal intervals (three in this case) in the circumferential direction. Reference numeral 8 denotes a planetary roller, which is rotatably supported by each planetary shaft 6 via a floating bush 9, whose outer periphery corresponds to a circumferential groove for rolling the planetary roller formed on the inner periphery of the fixed ring 5 and the outer periphery of the sun ring 3. It comes into contact with the cylindrical bottom surface of 3a. In addition, the floating bush 9
is interposed between the peripheral stepped portion 6a of the planetary shaft 6 and the planetary roller 8, and is positioned in the axial direction by a side surface of the stepped portion 6a and a snap ring 10 fixed to the end of the planetary shaft 6. The fixed ring 5 is an inner cylindrical ring 5
By shrink-fitting the outer cylindrical ring 5b, which has an inner diameter slightly smaller than the outer diameter of the inner cylindrical ring 5a, onto the outer periphery of the inner cylindrical ring 5a, the inner cylindrical ring 5a is tightened to the outer cylindrical ring and centripetal. subject to compressive stress. Note that the inner cylindrical ring 5a is replaced by the outer cylindrical ring 5b.
It may be polymerized by cold fitting on the inner peripheral surface of the
Further, the fixed ring 5 is not limited to the double shape of the embodiment, but may be at least double shape or more.

In the planetary roller type power transmission device, which is a speed increaser with the above configuration, radial contact pressure is applied to the contact surfaces of the sun wheel 3, planetary rollers 8, and fixed wheel 5. , this causes input shaft 1
For example, when the output shaft 2 rotates in the direction of the X arrow in FIG. 2, the rotational force of the output shaft 2 is increased and the output shaft 2 rotates in the direction of the Y arrow.

Effects of the Invention This invention has the above configuration, and the repeated stress that the fixed ring receives due to the pressure contact of the planetary roller during use of the device is alleviated by the centripetal compressive stress applied to the fixed ring in advance. Therefore, premature peeling due to fatigue is less likely to occur on the inner circumferential surface of the fixed ring, and the life of the fixed ring can be improved.

There are also the following additional effects.

When damage occurs to the fixed ring, such as cracking, only the inner cylindrical ring needs to be replaced, and the inner cylindrical ring should be made of a highly fatigue-resistant material, while the outer cylindrical ring should be made of inexpensive material or heat treated. can be omitted, both of which lead to cost reductions.

In recent years, aluminum die-casting is often used for the housing into which the fixed ring is press-fitted, and the press-fitting allowance for the fixed ring cannot be made large. Since the rings are multi-layered and the outer cylindrical ring applies compressive stress to the inner cylindrical ring in advance, it is not affected by the housing material.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view of a main part of an embodiment of the present invention, and FIG. 2 is a sectional view taken along the line -- in FIG. DESCRIPTION OF SYMBOLS 1...Second rotating shaft, 2...First rotating shaft, 3...Sun wheel, 4...housing, 5...fixed ring, 5a...inner cylindrical ring, 5b...outer cylindrical ring, 6...planetary shaft , 8
... Planetary roller, 9... Floating button.

Claims (1)

[Claims] 1. Between the outer periphery of the sun wheel 3 provided on the first rotating shaft 2 or 1 and the inner periphery of the fixed shaft 5 fitted in the aluminum die-cast housing 4, there is a A plurality of planetary rollers 8 are disposed in contact with the respective surfaces, and each planetary roller 8 is supported by a planetary roller support member 6 fixed to the second rotating shaft 1 or 2, so that the two rotations are Axis 1, 2
In the planetary roller type power transmission device in which power is transmitted between the fixed shaft 5 and the plurality of cylindrical rings 5a and 5b concentrically superimposed, the fixed shaft 5 has a multilayered shape, and the most The inner cylindrical ring 5a is superimposed so as to receive centripetal compressive stress only by being tightened by the outer cylindrical ring 5b,
A planetary roller type power transmission device characterized in that the outermost cylindrical ring 5b is fitted and fixed to the housing 4 so as not to apply tensile stress.