JP2012127422A - Planetary gear mechanism - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a planetary gear mechanism which can stably support a shaft while being miniaturized in an axial direction.SOLUTION: The planetary gear mechanism includes: a sun gear; a plurality of planetary gears engaged with the sun gear; an inner gear engaged with the planetary gears; a carrier rotatably connected with the plurality of planetary gears thereto; the shaft fixed to the carrier; and a bearing for rotatably supporting the shaft. The inner gear includes: an inner tooth part; and an inner peripheral part. Each of the plurality of planetary gears includes: an outer tooth part; and an outer peripheral part. Each of the planetary gears rolls on the inner peripheral part while the outer tooth part is engaged with the inner tooth part and the outer peripheral part abuts on the inner peripheral part.

Description

  The present invention relates to a planetary gear mechanism.

  Conventionally, a planetary gear mechanism is known. The planetary gear mechanism is provided with a bearing for rotatably supporting a shaft connected to the carrier. Patent Document 1 discloses a technique related to such a planetary gear mechanism.

JP 2003-299310 A

  When the planetary gear mechanism is downsized in the axial direction, it is conceivable to shorten the shaft itself by reducing the number of bearings used or adopting a short bearing in the axial direction. Thereby, a short axis | shaft can be employ | adopted and size reduction in the axial direction of a planetary gear mechanism can be achieved. However, if the number of bearings is reduced or a bearing with a short axial length is used, the shaft may not be stably supported.

  Accordingly, an object of the present invention is to provide a planetary gear mechanism that can stably support a shaft and is miniaturized in the axial direction.

  The object is to provide a sun gear, a plurality of planetary gears meshing with the sun gear, an internal gear meshing with the planetary gears, a carrier in which the planetary gears are rotatably connected, and fixed to the carrier A shaft and a bearing that rotatably supports the shaft, wherein the internal gear has an inner tooth portion and an inner peripheral portion, and each of the plurality of planetary gears has an outer tooth portion and an outer peripheral portion. The plurality of planetary gears can be achieved by a planetary gear mechanism that rolls on the inner periphery while the outer teeth engage with the inner teeth and the outer periphery contacts the inner periphery.

  Thereby, a plurality of planetary gears and internal gears function as rolling bearings. Here, the plurality of planetary gears are rotatably connected to the carrier, and the shaft is connected to the carrier. Therefore, a plurality of planetary gears, carriers, and shafts can be regarded as an integral member. Since a plurality of planetary gears and internal gears function as rolling bearings, the number of bearings directly supporting the shaft can be reduced, or a bearing having a short axial length can be employed. Thereby, a short axis | shaft can be employ | adopted and the size reduction of an axial direction is attained.

  According to the present invention, it is possible to provide a planetary gear mechanism that can stably support a shaft and is miniaturized in the axial direction.

FIG. 1 is a perspective view of the planetary gear mechanism A according to the first embodiment. FIG. 2 is a cross-sectional view of the planetary gear mechanism. 3A and 3B are external views of the planetary gears. 4A and 4B are external views of the internal gear. 5 is a cross-sectional view taken along the line AA in FIG. 4B. 6A is a cross-sectional view taken along the line BB in FIG. 2, and FIG. 6B is a cross-sectional view taken along the line CC in FIG. FIG. 7 is a cross-sectional view of the planetary gear mechanism A1 according to the second embodiment. 8A to 8C are explanatory diagrams of planetary gears. 9A is a cross-sectional view taken along the line DD of FIG. 7, and FIG. 9B is a cross-sectional view taken along the line EE of FIG.

  A plurality of embodiments will be described below.

  FIG. 1 is a perspective view of the planetary gear mechanism A according to the first embodiment. FIG. 2 is a cross-sectional view of the planetary gear mechanism A. The planetary gear mechanism A includes a motor M, a printed circuit board P, a rotating shaft 10, a sun gear 20, a planetary gear 30, an internal gear 40, a carrier 50, an output shaft 60, and the like. The printed circuit board P is for supplying electric power to a coil (not shown) provided in the motor M. The rotating shaft 10 is an output shaft of the motor M. The rotating shaft 10 is rotatably supported by a bearing B3. The printed circuit board P is fixed to the support plate 11. A sun gear 20 is fitted to the rotary shaft 10. The sun gear 20 is in mesh with the three planetary gears 30. The planetary gear 30 is disposed in the internal gear 40 and meshes with the internal gear 40. A support plate 11 is fixed to the internal gear 40 on the proximal end side, and a support plate 13 is fixed on the distal end side. The carrier 50 is connected to a plurality of planetary gears 30. The carrier 50 has a plate shape. An output shaft 60 is connected to the carrier 50. A bearing B1 that rotatably supports the output shaft 60 is fixed to the support plate 13. The sun gear 20, the planetary gear 30, and the internal gear 40 are made of synthetic resin.

The operation of the planetary gear mechanism A will be described.
As the rotating shaft 10 of the motor M rotates, the sun gear 20 rotates. Accordingly, the plurality of planetary gears 30 revolve around the sun gear 20 while rotating. As the plurality of planetary gears 30 revolve, the carrier 50 rotates. As the carrier 50 rotates, the output shaft 60 rotates. Thereby, the rotational power of the motor M is decelerated and transmitted to the output shaft 60. Note that a support shaft 38 is fitted to the planetary gear 30. The support shaft 38 is supported by the carrier 50. The internal gear 40 is fixed to a device in which the planetary gear mechanism A is adopted. Therefore, the planetary gear mechanism A is a planetary type planetary gear mechanism.

  3A and 3B are external views of the planetary gear 30. FIG. 4A and 4B are external views of the internal gear 40. FIG. 5 is a cross-sectional view taken along the line AA in FIG. 4B. 6A is a cross-sectional view taken along line BB in FIG. 6B is a cross-sectional view taken along the line CC of FIG.

  As shown in FIGS. 3A and 3B, the planetary gear 30 has an external tooth portion 32 and an outer peripheral portion 34. The external tooth portion 32 meshes with the internal tooth portion 42 of the internal gear 40. The outer peripheral portion 34 abuts on the inner peripheral portion 44 of the internal gear 40. The diameter D34 of the outer peripheral portion 34 is smaller than the tip diameter D32 of the external tooth portion 32. The tip diameter of the external tooth portion 32 means the diameter of a circle passing through the tip of the external tooth portion 32. A support shaft 38 is rotatably fitted in the hole 37. As shown in FIG. 2, the external tooth portion 32 is located on the distal end side of the planetary gear mechanism A, and the outer peripheral portion 34 is located on the proximal end side of the planetary gear mechanism A. In other words, the external tooth portion 32 is close to the bearing B1, and the outer peripheral portion 34 is separated from the bearing B1. The outer peripheral portion 34 has a shape such that the tip of each tooth of the external tooth portion 32 is scraped off. Since the planetary gear 30 is made of synthetic resin, it is possible to form the planetary gear 30 having the external tooth portion 32 and the outer peripheral portion 34 by making the mold used in the manufacturing process into such a shape. it can.

  As shown in FIGS. 4A, 4 </ b> B, and 5, the internal gear 40 has an internal tooth portion 42 and an inner peripheral portion 44. Unlike the internal tooth part 42, the inner peripheral part 44 is not formed with teeth. As shown in FIGS. 2 and 5, the inner tooth portion 42 is located on the distal end side of the planetary gear mechanism A, and the inner peripheral portion 44 is located on the proximal end side of the planetary gear mechanism A. In other words, the inner tooth portion 42 is close to the bearing B1, and the inner peripheral portion 44 is separated from the bearing B1. As shown in FIG. 5, the diameter D44 of the inner peripheral portion 44 is larger than the tip circle diameter D42 of the inner tooth portion 42.

  As shown in FIG. 6A, the planetary gears 30 revolve around the sun gear 20 as the sun gear 20 rotates due to the engagement between the outer teeth 32 and the inner teeth 42. The external tooth portion 32 also meshes with the tooth portion of the sun gear 20. In FIG. 6A, the sun gear 20 is simplified.

  As shown in FIG. 6B, the outer peripheral portion 34 and the inner peripheral portion 44 are in contact with each other. Specifically, the plurality of (three in this embodiment) planetary gears 30 are arranged on the inner peripheral portion 44 while the outer tooth portion 32 is engaged with the inner tooth portion 42 and the outer peripheral portion 34 is in contact with the inner peripheral portion 44. Roll. Here, the plurality of planetary gears 30 are rotatably supported by a carrier 50, and an output shaft 60 is connected to the carrier 50. Therefore, the plurality of planetary gears 30, the carrier 50, and the output shaft 60 can be regarded as an integral member. Thereby, the plurality of planetary gears 30 and the internal gear 40 function as rolling bearings. Therefore, the output shaft 60 can be stably supported at two points together with the bearing B1. Therefore, the number of bearings directly supporting the output shaft 60 can be reduced, or a bearing having a short axial length can be employed. In the planetary gear mechanism A of the present embodiment, the output shaft 60 is directly supported by a single bearing B1. The planetary gear mechanism A employs a short output shaft 60 and is miniaturized in the axial direction.

  As described above, the outer tooth portion 32 and the inner tooth portion 42 are close to the bearing B1, and the outer peripheral portion 34 and the inner peripheral portion 44 are separated from the bearing B1. Accordingly, the bearing B1 that directly supports the shaft is separated from the inner peripheral portion 44 and the outer peripheral portion 34 that function as rolling bearings. Accordingly, the plurality of planetary gears 30, the carrier 50, and the output shaft 60 can be integrally supported at two points apart from the bearing B 1, the outer peripheral portion 34, and the inner peripheral portion 44. Thereby, even when only the single bearing B1 that directly supports the output shaft 60 is provided as in the planetary gear mechanism A of the present embodiment, the output shaft 60 can be stably supported.

  Further, the diameter D44 of the inner peripheral portion 44 is equal to the meshing pitch circle diameter D42 ′ of the inner tooth portion 42, and the diameter D34 of the outer peripheral portion 34 is equal to the meshing pitch circle diameter D32 ′ of the outer tooth portion 32. Here, the diameter of the outer peripheral portion 34 is the diameter of a circle that passes through the tips of the teeth of the outer peripheral portion 34. Thereby, it is suppressed that the outer peripheral part 34 slips on the inner peripheral part 44. FIG. Thereby, it can suppress that it becomes the resistance of rotation and revolution of the planetary gear 30 by the outer peripheral part 34 slipping on the inner peripheral part 44, and the smooth rotation of the planetary gear 30 in the internal gear 40 can be maintained.

  In the above embodiment, the diameter D34 of the outer peripheral portion 34 is substantially equal to the meshing pitch circle diameter D32 ′ of the outer tooth portion 32, and the diameter D44 of the inner peripheral portion 44 is equal to the meshing pitch circle diameter D42 ′ of the inner tooth portion 42. Almost equal. However, it is not limited to such a configuration. For example, the diameter D34 of the outer peripheral portion 34 may be larger than the meshing pitch circle diameter D32 ′, and the diameter D44 of the inner peripheral portion 44 may be larger than the meshing pitch circle diameter D42 ′. Conversely, the diameter D34 of the outer peripheral portion 34 may be smaller than the meshing pitch circle diameter D32 ′, and the diameter D44 of the inner peripheral portion 44 may be smaller than the meshing pitch circle diameter D42 ′.

  Next, the planetary gear mechanism of Example 2 will be described. In addition, about the part similar to Example 1, the same code | symbol is attached | subjected and the overlapping description is abbreviate | omitted. FIG. 7 is a cross-sectional view of the planetary gear mechanism A1 according to the second embodiment. 8A to 8C are explanatory diagrams of the planetary gear 30a. 9A is a cross-sectional view taken along the line DD of FIG. 7, and FIG. 9B is a cross-sectional view taken along the line EE of FIG.

  In the planetary gear 30a, the external tooth portion 32a and the outer peripheral portion 34a are separate parts. Although the outer peripheral part 34a is disk shape in which the tooth | gear is not formed, a cylindrical shape may be sufficient. The external tooth part 32a and the outer peripheral part 34a are made of synthetic resin. The external tooth portion 32a and the outer peripheral portion 34a are formed of the same material, but may be formed of different materials. Holes 37a and 38a are provided in the external tooth portion 32a and the outer peripheral portion 34a, respectively. The support shaft 38 is fitted into the holes 37a and 38a. Specifically, the external tooth portion 32 a and the outer peripheral portion 34 a are fitted to the support shaft 38 so as to be rotatable.

  Since the external tooth part 32a and the outer peripheral part 34a are separate parts, they can rotate independently of each other. Therefore, even if a difference in the rotation speed (rolling length) between the outer peripheral portion 34a and the outer tooth portion 32a occurs without matching the diameter D34a of the outer peripheral portion 34a with the meshing pitch circle diameter D32a 'of the outer tooth portion 32a, The part 34a and the external tooth part 32a can rotate independently of each other. Accordingly, the outer peripheral portion 34a can be prevented from slipping on the inner peripheral portion 44, and the smooth rotation of the planetary gear 30a within the internal gear 40 can be maintained.

  As shown in FIG. 8B, the diameter D34a of the outer peripheral portion 34a is substantially equal to the meshing pitch circle diameter D32a ′ of the outer tooth portion 32a, but is not limited thereto. Although not shown in the drawings, the diameter D44a of the inner peripheral portion 44a is substantially equal to the meshing pitch circle diameter D42a ′ of the inner tooth portion 42a, but is not limited thereto.

  Although the preferred embodiments of the present invention have been described in detail above, the present invention is not limited to such specific embodiments, and modifications and changes can be made within the scope of the gist of the present invention described in the claims. Is possible.

  Although the planetary planetary gear mechanism has been described as an example in the above embodiment, it may be a solar type planetary gear mechanism in which the sun gear is fixed and the internal gear is driven and the carrier is driven, or the carrier is It may be a star type planetary gear mechanism that is fixed and driven by the sun gear and driven by the internal gear.

  In the above embodiment, teeth are formed on the outer peripheral portion 34 of the planetary gear 30, but the shape is not limited to this. For example, the outer peripheral portion 34 may have a cylindrical shape in which teeth are not formed.

  In the above embodiment, the planetary gears 30 and 30a and the internal gear 40 are made of synthetic resin, but are not limited thereto, and may be made of metal, for example.

A, A1 Planetary gear mechanism B1, B3 Bearing M Motor P Printed circuit board 10 Rotating shaft 11, 13 Support plate 20 Sun gear 30, 30a Planetary gear 32, 32a Outer tooth part 34, 34a Outer part 40 Internal gear 42 Inner tooth part 44 Inner circumference 50 Carrier 60 Output shaft

Claims (6)

The sun gear,
A plurality of planetary gears meshing with the sun gear;
An internal gear meshing with the planetary gear;
A carrier in which the plurality of planetary gears are rotatably connected;
A shaft fixed to the carrier;
A bearing that rotatably supports the shaft,
The internal gear has an inner tooth portion and an inner peripheral portion,
Each of the plurality of planetary gears has an outer tooth portion and an outer peripheral portion,
The plurality of planetary gears is a planetary gear mechanism that rolls on the inner peripheral portion while the outer tooth portion is engaged with the inner tooth portion and the outer peripheral portion is in contact with the inner peripheral portion. The inner tooth portion and the outer tooth portion are close to the bearing,
The planetary gear mechanism according to claim 1, wherein the inner peripheral portion and the outer peripheral portion are separated from the bearing.   The planetary gear mechanism according to claim 1 or 2, wherein the external tooth portion and the outer peripheral portion are separate parts. The diameter of the inner peripheral portion is equal to the meshing pitch circle diameter of the inner tooth portion,
The planetary gear mechanism according to any one of claims 1 to 3, wherein a diameter of the outer peripheral portion is equal to a meshing pitch circle diameter of the outer tooth portion.   The planetary gear mechanism according to any one of claims 1 to 3, wherein a diameter of the outer peripheral portion is smaller than a meshing pitch circle diameter of the outer tooth portion. The planetary gear mechanism according to any one of claims 1 to 3, wherein a diameter of the outer peripheral portion is larger than a meshing pitch circle diameter of the outer tooth portion.

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