JPH1030687A - Planetary type speed increasing/decreasing gear - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an increased life by reducing a normal force, applied on an external tooth gear and exerted toward a gear center, as the advantages of a trochoid planetary type speed increasing/decreasing gear are maintained, to reduce size and a cost, and to improve reliability. SOLUTION: A planetary type speed increasing/decreasing gear is formed such that an external tooth gear 13 having a trochoid tooth 13a revolvably and rotatably engaged with a high speed shaft through an eccentric body 12 and rotatably engaged in an interlocking state with a low speed shaft through a carrier is engaged with an internal tooth gear 11 having a circular tooth 11a arranged at a casing. In this case, notches 15 and 16 are formed in at least one of the tip part and the bottom part of the trochoid tooth 13a and the tip part of the circular tooth 11a.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a planetary speed reducer in which an external gear is meshed with an internal gear.

[0002]

2. Description of the Related Art As the planetary speed reducer, as shown in, for example, Japanese Patent Application Laid-Open No. 56-116947, the planetary speed reducer is engaged with a high-speed shaft via an eccentric body so as to be able to revolve and rotate and to be connected to a low-speed shaft. 2. Description of the Related Art There is known an external gear having trochoid teeth engaged with a carrier via a carrier so as to be interlockably rotatable with an internal gear having circular teeth provided on a casing.

In the trochoid type planetary speed reducer, a relatively high speed increase / reduction ratio can be obtained in spite of the small size, the tooth profile is smooth, there is no stress concentration on the tooth root, and the external gear and the internal gear can be used simultaneously. Since the number of meshing is large, low vibration and low noise are realized, and there is no damage even if overloaded or impacted,
It has advantages such as high efficiency.

[0004]

However, in the conventional trochoid type planetary gearbox, the trochoidal tooth exhibiting the trochoidal curve in the external gear is theoretically in contact with all the circular teeth in the internal gear. However, it is difficult to increase the processing accuracy for the purpose of realizing the above-mentioned full contact state of the two teeth. Reaction force of the load applied to the point of contact of the trochoid teeth with which the trochoid teeth are in contact with the tip of the trochoid tooth and the tooth surface near the circumferential direction of the tooth bottom,
That is, the normal force applied to the external gear toward the center of the external gear becomes extremely large, and an excessive load is applied to the bearing portion of the external gear on the eccentric body. This excessive load greatly shortens the life of the speed reducer, and in order to prevent such shortening of the life, a large-capacity bearing must be used or the load must be limited.

SUMMARY OF THE INVENTION An object of the present invention is to reduce the normal force applied to the external gear toward the center of the external gear while maintaining the advantages of the trochoid type planetary speed reducer, thereby enabling a long life and a small size. It is an object of the present invention to provide a cost-effective and reliable planetary speed reducer.

[0006]

SUMMARY OF THE INVENTION A planetary speed reducer according to the present invention is revolvably and rotationally engaged with a high-speed shaft via an eccentric body and is rotatable with a low-speed shaft via a carrier. An external gear having engaged trochoid teeth is meshed with an internal gear having circular teeth provided on a casing, and at the time of deceleration, an external gear generated due to a difference in the number of teeth between the external gear and the internal gear. Is transmitted to the low-speed shaft via the carrier, and at the time of speed increase, the revolution of the external gear caused by the difference in the number of teeth between the external gear and the internal gear is transmitted to the high-speed shaft via the eccentric body. In a planetary gearbox of the type described above, a notch is formed in at least one of the tip and bottom of the trochoid tooth and the tip of the circular tooth.

[0007] In the above configuration, since the portion other than the notch in the tooth tip portion and the tooth bottom portion is used for transmission and the notch portion is not related to the transmission, the meshing between the external gear and the internal gear is performed. In this case, interference of the tooth tip is eliminated, and the reaction force of the load applied to the contact point between the trochoid tooth and the circular tooth is concentrated in a direction substantially perpendicular to the radial direction of the external gear, and the normal acting on the center of the gear. The force is reduced, and trochoid teeth and circular teeth with a small pressure angle are formed as if they were involute teeth.

[0008] The notch may be formed at the tip and / or bottom of the trochoid tooth, preferably at both the tip and the bottom toward the radial inside of the external gear, Further, the tip of the circular tooth may be bored outward in the radial direction of the internal gear, and may be combined with the tip and / or bottom of the trochoid tooth and the tip of the circular tooth. It may be perforated.

Preferably, the notch is formed in a portion corresponding to a pressure angle of 70 degrees or more, and in this case, the notch corresponding to the pressure angle of 70 degrees or more in a tooth tip or a tooth bottom of each gear. The notch is not relevant to the transmission and therefore
The portion corresponding to the pressure angle less than degree will be used for transmission.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described below based on embodiments shown in the drawings. FIG. 1 is a cross-sectional view of a main part of a planetary speed reducer according to an embodiment of the present invention, FIG. 2 is a vertical cross-sectional view of the planetary speed reducer shown in FIG. 1, and FIG. FIG. 2 is a sectional view of a main part of an external gear and an internal gear in the machine.

1 to 3, a high-speed shaft 1 and a low-speed shaft 2 are arranged on a coaxial line, and the high-speed shaft 1 is provided with bearings 5, 6 at a front portion of a casing 3 and a carrier 4 integrated with the low-speed shaft 2, respectively. And the low-speed shaft 2 is supported at the rear of the casing 3 via bearings 7 and 8.

An internal gear 11 is provided on the ring body of the casing 3, and the internal gear 11 is composed of a large number of circular teeth 11a made of a cylindrical pin. Are eccentrically fixed with a phase difference of 180 degrees, and each eccentric body 12 has an external gear 1 having fewer teeth than the internal gear 11.
3 is supported via a bearing 14 and the external gear 13
Are composed of trochoid teeth 13a, and each external gear 13 is meshed with the internal gear 11 (only one eccentric body 12 and one external gear 13 are shown in FIG. 1). Notches 15 and 16 are formed at the tip and the bottom of the trochoid teeth 13a of the external gear 13 at portions corresponding to the pressure angle α of 70 degrees or more toward the radially inner side of the external gear 13. Have been. In the present invention, the pressure angle α
Is defined as an angle between a tangent line L at one point on the tooth surface and a radial line M passing from the center of each gear to the midpoint of the tooth tip or the tooth bottom.

A plurality of carrier pins 21 are implanted on the carrier 4 at equal angular intervals, and each carrier pin 2
1, a bush 22 is slidably fitted, and a hole 23 is formed in each external gear 13 at a position corresponding to the carrier pin 21.
Each carrier pin 21 is loosely fitted into each hole 23 of each external gear 13 via a bush 22.

In the above construction, when the high-speed shaft 1 is rotated at the time of deceleration, each eccentric body 12 causes each external gear 13 to revolve, and the teeth between the external gear 13 and the internal gear 11 are rotated. The rotation of the external gear 13 caused by the number difference is caused by the rotation of the low-speed shaft 2 via the carrier pin 21 and the carrier 4.
In this case, the portions of the notches 15 and 16 corresponding to the pressure angles of 70 degrees or more at the apex and the bottom of the trochoid teeth 13a are not related to the transmission, and the pressure of less than 70 degrees The portion corresponding to the corner will be used for transmission. In addition, when speeding up, contrary to the above,
The external gear 13 is rotated by the low-speed shaft 2 via the carrier 4, and the revolution of the external gear 13 caused by the difference in the number of teeth between the external gear 13 and the internal gear 11 causes the rotation of the external gear 13 via the eccentric body 12. 1 is transmitted.

FIG. 4 is a sectional view of a main part of an external gear and an internal gear in a planetary speed reducer according to another embodiment of the present invention.

In this embodiment, a notch 17 is formed in the tip of the circular tooth 11a of the internal gear 11 at a portion corresponding to a pressure angle α of 70 degrees or more toward the outside of the internal gear 11 in the radial direction. Has been established. The function of the notch 17 is the same as described above.

[0017]

Since the planetary speed reducer according to the present invention is constructed as described above, there is no tooth tip interference when the external gear and the internal gear mesh with each other, and the speed is relatively high despite the small size. The ratio is obtained, the tooth profile is smooth, there is no stress concentration on the tooth root, and the number of simultaneous meshing is large, so low vibration and low noise are realized and there is no damage even if overloaded or impacted, Maintains the advantages of the trochoid type planetary speed reducer such as high efficiency, and reduces the normal force applied to the external gear toward the center of the gear without applying high processing accuracy when processing the teeth. Enables long life.

If the notch is formed at the tip and / or the bottom of the trochoid tooth, the trochoid curve portion corresponding to the notch in the trochoid tooth is not required and the trochoid to be used. Since the teeth are easily shaped for gear cutting, it is possible to easily obtain high finishing accuracy with a general-purpose hobbing machine without using a special dedicated machine for machining trochoid teeth after hardening the external gear. Can be. Further, in the case where the notch is formed in the tip of the circular tooth, the notch processing of the circular tooth is easy,
This is applicable to non-rotating circular teeth.

In the case where the notch is formed in a portion corresponding to a pressure angle of 70 degrees or more, a normal force toward the center of the external gear that is applied to the external gear when the external gear and the internal gear mesh with each other is applied. It is surely reduced to promote the above-mentioned effects.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a main part of a planetary speed reducer according to an embodiment of the present invention.

FIG. 2 is a longitudinal sectional view of the planetary speed reducer shown in FIG.

FIG. 3 is a sectional view of a main part of an external gear and an internal gear in the planetary speed reducer shown in FIG. 1;

FIG. 4 is a cross-sectional view of a main part of an external gear and an internal gear in a planetary gearbox according to another embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 High-speed shaft 2 Low-speed shaft 3 Casing 4 Carrier 11 Internal gear 11a Circular tooth 12 Eccentric body 13 External gear 13a Trochoid tooth 15 Notch 16 Notch 17 Notch

Claims (4)

[Claims] An external gear having trochoid teeth engaged with a high-speed shaft via an eccentric body so as to be able to revolve and rotate while being interlocked with a low-speed shaft via a carrier is provided on a casing. It is meshed with an internal gear having circular teeth, and during deceleration, the rotation of the external gear caused by the difference in the number of teeth between the external gear and the internal gear is transmitted to the low-speed shaft via the carrier, In a planetary type speed reducer of the type in which the revolution of an external gear generated due to a difference in the number of teeth between the external gear and the internal gear at the time of speed increase is transmitted to a high speed shaft via an eccentric body, the tip of the trochoid tooth is provided. A notch is formed in at least one of a part, a tooth bottom part, and a tip part of the circular tooth. 2. The planetary speed reducer according to claim 1, wherein the notch is formed in a tip portion and / or a bottom portion of the trochoid tooth toward a radial inside of the external gear. 3. The planetary speed reducer according to claim 1, wherein the notch is formed in a tip portion of the circular tooth toward a radial outside of the internal gear. 4. The planetary speed reducer according to claim 1, wherein the notch is formed in a portion corresponding to a pressure angle of 70 degrees or more.