JPS60157556A - Planetary roller type power transmission device - Google Patents

Abstract

PURPOSE:To extend the service life of a stationary ring by constructing the stationary ring in a form of multiple, superimposed cylindrical rings wherein the inner most cylindrical ring is tightened by the outer ring so as to centripetally receive the compressive stress. CONSTITUTION:An output shaft 2 has on its one end a sun ring 3 fixed by a key 7 etc. A stationary ring 5 is provided on the inner surface of a housing 4. Planetary shafts 6 are screwed into one end 1a of an input shaft 1 in the axial direction with an equal spacing in the circumferential direction. A planetary roller 8 is rotatably supported by each planetary shaft 6 through a floating bushing 9, and its outer circumference is engaged with the inner circumference of the stationary ring 5 and the bottom of a ringed groove formed in the outer circumference of the sun ring 3. In this instance, the stationary ring 5 is constructed in such a manner that an outer cylindrical ring 5b having an inner diameter slightly smaller than the outer diameter of an inner ring 5a is superimposed over the inner ring 5a so that the inner ring 5a may centripetally receive the compressive stress by being tightened by the outer ring 5b.

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 Publication No. 58-80659. This known structure is
A steel sun wheel directly connected to a rotationally driven input shaft, a steel fixed ring with a concave cross section fitted and fixed to the inner periphery of the housing, and a plurality of steel sun wheels that are in contact with the outer periphery of the sun wheel and the inner periphery of the fixed ring. It consists of a planetary roller and a plurality of planetary shafts provided in the axial direction at the end of the output shaft, and the planetary shafts rotatably support each planetary roller at equal intervals on the circumference and via needle roller bearings. By tightening the fixed ring having a concave cross section in the axial direction from both sides and crowning the inner diameter thereof, the fixed ring, the plurality of planetary rollers, and the sun ring are pressed against each other in the radial direction. , the rotational driving force from the input shaft is decelerated and transmitted to the output shaft by the M vibration force generated by pressure contact with the input shaft.

Problems with the Background Art In conventional devices, the fixed ring, which has a concave cross section, has its inner diameter deformed by crowning due to tightening on both sides. I will do it. 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. It has the disadvantage of making it shorter.

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

Summary of the Invention The present invention provides a planetary roller type power transmission device in which a fixed ring has a multiplex shape of a plurality of cylindrical rings, and the innermost cylindrical ring of the plurality of cylindrical rings is tightened by the outer cylindrical ring. It has a polymerized structure that allows it to undergo central compressive stress.

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

(1) is the input shaft, (2) is the output shaft, (31 is the output shaft (2)
) at one end of the sun ring (
Of course, the solar ring (3) may be formed integrally with one end of the output shaft (2). L (5) is the inner circumference 1n of the housing (4)
The fixed ring (6) is fitted and fixed to the end face (1a) of the input @ A11 (1) in the circumferential direction, and has a double shape of the inner I11 cylindrical ring (5a) and the outer cylindrical shaft (50). These are planetary shafts screwed in the axial direction at equal intervals (three in this case). As a result, the planetary shafts (6) are arranged at equal intervals in the circumferential direction (in this case, 3
) is fixed to the input shaft (1). (8) is a planetary roller, which is rotatably supported on each planetary shaft (6) via a floating bush (9), and its outer circumference is connected to the inner circumference of the fixed ring (5) and the outer circumference of the sun wheel (3). It comes into contact with the cylindrical bottom surface of the formed planetary roller rolling circumferential FC (3a). Further, the floating bush (9) is attached to a peripheral portion (6a) of the planetary shaft (6).
) and the planetary roller (8), and the stepped portion (6a
) is positioned in the axial direction by a snout ring (10) fixed to the end of the planetary shaft (6). By shrink-fitting the outer cylindrical shaft (5b) having an inner diameter slightly smaller than the outer diameter of the inner cylindrical ring (5aβ), the inner cylindrical ring (5a) is tightened to the outer cylindrical ring. It receives compressive stress centrally.In addition, the inner segmental ring (5a)
may be polymerized by cold fitting onto the inner circumferential surface of the outer first cylindrical ring (5b).Furthermore, the fixed ring (5) is not limited to the double shape of the embodiment, but has at least a double shape or more. Good to have.

In the planetary roller 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 roller (8), and fixed wheel (5). As a result, when the input shaft (1) rotates, for example, 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.

This invention has the above configuration, and the reversing stress that the fixed ring receives due to the pressure contact of the planetary roller during use of the device is applied in advance to the fixed ring. Since the stress is relaxed by the compressive stress in the center direction, early 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 exploding, only the inner cylindrical ring needs to be replaced.Furthermore, only the inner cylindrical ring is made of a highly fatigue-resistant material, and the outer cylindrical shaft is made of inexpensive material. Alternatively, heat treatment can be omitted, both of which lead to cost reduction.

■ In recent years, aluminum die-casting (5) 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 large, but in this invention, compressive stress is applied to the fixed ring by the press-fitting allowance for the housing. Instead, the fixed ring has a multilayered shape and the outer cylindrical shaft applies pressure I stress to the inner cylindrical ring in advance, so it is not affected by the material of the housing.

[Brief explanation of the drawing]

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. (1)...Second rotation axis (2)...First rotation axis (
3)...Solar ring (4)...Housing (5)...
・Fixed ring (5a)... Inner cylindrical ring (50) ・Outer cylindrical ring (6)... Planetary shaft (8)... Planetary roller (
9]...Floating Bran 2 Patent Applicant Figure 18 Figure 2

Claims (1)

[Claims] A plurality of planetary rollers are disposed between the outer periphery of the sun ring provided on the first rotating shaft and the inner periphery of the fixed ring fitted and identified in the housing, and each of the planetary rollers abuts between the two stations. In a planetary roller type power transmission device in which a roller is supported by a planetary roller support member fixed to a second rotating shaft to transmit power between the two rotating shafts, the fixed ring has a plurality of cylinders. A planetary roller type having multiple shafts, and characterized by the fact that the innermost cylindrical shaft of the plurality of cylindrical shafts is tightened by the outer cylindrical shaft and superimposed so as to centrally receive compressive stress. Power transmission device.