Planetary gear mechanism

Abstract

To provide a planetary gear mechanism that can restrain friction between an internal gear and a housing, and restrain the generation of a collision sound caused by a collision between them.SOLUTION: A planetary gear mechanism 1 comprises a sun gear 10, an internal gear 20 arranged concentrically with the sun gear 10, a plurality of planetary gears 30 arranged between the sun gear 10 and the internal gear 20, and a housing 50 into which the internal gear 20 is fitted. An outer peripheral surface of the internal gear 20 is provided with a plurality of protrusions 22 protruding radially outward at intervals in a circumferential direction, and an inner peripheral surface of the housing 50 is provided with a plurality of fitting concave parts 51 into which the plurality of protrusions 22 can be loosely fitted respectively. Damper members 60 fitted into the fitting concave parts 51 are arranged between the plurality of protrusions 22 and the fitting concave parts 51 respectively.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a planetary gear mechanism. [Background technology]

[0002] Conventionally, planetary gear mechanisms have been known as mechanisms for changing the rotational speed of a drive shaft. The planetary gear mechanism is provided with an internal gear, and a known technology includes a housing into which the internal gear is fitted. In such technology, the planetary gears revolve as the sun gear rotates, creating a force that tends to rotate the internal gear, resulting in friction between the internal gear and the housing and the generation of impact noise. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2024-3287 Summary of the Invention [Problem to be solved by the invention]

[0004] The present invention provides a planetary gear mechanism that can suppress friction between an internal gear and a housing and also suppress the generation of impact noise due to collision between them. [Means for solving the problem]

[0005] The present invention employs the following means to solve the above problems.

[0006] That is, the planetary gear mechanism of the present invention is The sun gear and an internal gear arranged concentrically with the sun gear; a plurality of planetary gears disposed between the sun gear and the internal gear; a housing into which the internal gear is fitted; A planetary gear mechanism comprising: A plurality of protrusions protruding radially outward are provided at intervals in the circumferential direction on an outer peripheral surface of the internal gear, and a plurality of fitting recesses into which the plurality of protrusions can be loosely fitted are provided on an inner peripheral surface of the housing; The present invention is characterized in that damper members are disposed between the plurality of protrusions and the fitting recesses, respectively, and are fitted into the fitting recesses.

[0007] According to the present invention, the damper member is disposed between the protrusion provided on the internal gear and the fitting recess provided on the inner peripheral surface of the housing, thereby reducing friction between the internal gear and the housing and reducing the generation of impact noise due to collision between them. Furthermore, because the damper member is fitted into the fitting recess provided on the inner peripheral surface of the housing, it is possible to prevent the damper member from being displaced due to the influence of the internal gear.

[0008] The damper member may be fitted into the fitting recess so as to contact both side surfaces and a bottom surface of the fitting recess.

[0009] This makes it possible to further suppress displacement of the damper member.

[0010] The damper member may include a thin plate portion made of a thin metal plate, and rubber layers provided on both sides of the thin plate portion.

[0011] The above configurations may be combined as much as possible. [Effects of the Invention]

[0012] As described above, according to the present invention, it is possible to suppress friction between the internal gear and the housing, and also to suppress the generation of impact noise due to collision between them. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 1 is an external view of a planetary gear mechanism according to an embodiment of the present invention. [Figure 2]FIG. 2 is an external view of a damper member according to an embodiment of the present invention. [Figure 3] FIG. 3 is a diagram showing how the damper members according to the embodiment of the present invention are fitted together. [Figure 4] FIG. 4 is a diagram showing the state of fitting of the damper member according to the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0014] The following detailed description of the present invention will be given by way of example with reference to the accompanying drawings, although the dimensions, materials, shapes, relative positions, etc. of the components described in the examples are not intended to limit the scope of the present invention unless otherwise specified.

[0015] (Example) A planetary gear mechanism according to an embodiment of the present invention will be described with reference to FIGS. 1 to 4. FIG. 1 is an external view of a planetary gear mechanism according to an embodiment of the present invention, and is a front view of the planetary gear mechanism. FIG. 2 is an external view of a damper member according to an embodiment of the present invention, where (a) is a plan view of the damper member, (b) is a side view of the damper member (viewed in the V1 direction in (a)), and (c) is a front view of the damper member (viewed in the V2 direction in (a)). FIG. 3 is a view showing how damper members according to an embodiment of the present invention are fitted together, where (a) shows a state during fitting, and (b) shows a state after fitting has been completed, each shown as an enlarged partial view of the front view. FIG. 4 is a view showing how damper members according to an embodiment of the present invention are fitted together.

[0016] <Overall configuration of planetary gear mechanism> The planetary gear mechanism 1 includes a sun gear 10 mounted on a first shaft, an internal gear 20 arranged concentrically with the sun gear 10, and multiple planetary gears 30 arranged between the sun gear 10 and the internal gear 20. The sun gear 10 is configured to rotate together with the first shaft and is generally fixed to the first shaft. However, the sun gear 10 can also be integrally mounted on the first shaft (i.e., the first shaft and the sun gear 10 can be configured as a single component). The planetary gears 30 are arranged to mesh with both the teeth 11 of the sun gear 10 and the teeth 21 of the internal gear 20. Each of the multiple planetary gears 30 (three in this embodiment) is journaled to a carrier 42 mounted on a second shaft 41. The carrier 42 is configured to rotate together with the second shaft 41. The carrier 42 can be fixed to the second shaft 41, or they can be integrated into a single component. Each of the multiple planetary gears 30 is journaled to be rotatable relative to the carrier 42.

[0017] With the above configuration, when the first shaft is used as the input shaft, rotating the sun gear 10 together with the first shaft causes the multiple planetary gears 30 to revolve and the second shaft 41 to rotate via the carrier 42. In other words, the second shaft 41 becomes the output shaft. When the second shaft 41 is used as the input shaft, rotating the carrier 42 together with the second shaft 41 causes the multiple planetary gears 30 to revolve and the first shaft to rotate via the sun gear 10. In other words, the first shaft becomes the output shaft.

[0018] The planetary gear mechanism 1 according to this embodiment also includes a housing 50 into which the internal gear 20 is fitted. A plurality of protrusions 22 that protrude radially outward are provided at intervals in the circumferential direction on the outer peripheral surface of the internal gear 20, and a plurality of protrusions are provided on the inner peripheral surface of the housing 50. A plurality of fitting recesses 51 into which the projections 22 can be loosely fitted are provided at intervals in the circumferential direction.

[0019] In the planetary gear mechanism 1 according to this embodiment, damper members 60 are disposed between the respective projections 22 and the fitting recesses 51. The damper members 60 will be described in detail below.

[0020] <Damper material> The damper member 60 is composed of a thin plate portion 61 made of a thin metal plate and rubber layers provided on both sides of the thin plate portion 61. The rubber layers include a first rubber layer 62 and a second rubber layer 63. The damper member 60 can be obtained by providing rubber layers on both sides of a thin metal plate and then forming the desired shape using sheet metal processing. The rubber layers can be provided on both sides of the thin plate, for example, by applying rubber cement to the thin plate and then drying it. Alternatively, the rubber cement can be applied to the thin plate, drying it, and then vulcanizing it by heating. The rubber cement can be obtained, for example, by dissolving a high-damping IIR rubber material in toluene. The rubber cement can be applied to both sides of the thin plate to a thickness of approximately 1 mm or less and then dried, or dried and then heated to vulcanize it. The rubber cement can be applied by spraying or brushing. It is also preferable to apply an adhesive to both sides of the thin plate before applying the rubber cement to prevent the rubber cement from peeling off. The adhesive can be applied to both sides of the thin plate by spraying. When the rubber cement is dried and then vulcanized by heating, the damper member 60 to which the rubber cement has been applied can be placed in an oven at a temperature of 150°C to 250°C and baked for a period of 0.5 to 30 minutes.

[0021] The fitting recess 51 provided on the inner peripheral surface of the housing 50 has a pair of side surfaces 51a and a bottom surface 51b, and is configured as a U-shaped groove when viewed from the front. In this embodiment, the damper member 60 is fitted into the fitting recess 51 so as to contact both side surfaces 51a and the bottom surface 51b of the fitting recess 51. That is, the damper member 60 has flat plate-like portions 60a that contact the pair of flat side surfaces 51a, respectively, and a curved plate-like portion 60b that contacts the bottom surface 51b that is configured as a curved surface.

[0022] The damper member 60 configured as described above can be fixed by fitting it into the fitting recess 51. That is, by fitting the damper member 60 into the fitting recess 51 in the direction of the arrow in FIG. 3(a), the pair of flat plate-like portions 60a come into close contact with both side surfaces 51a of the fitting recess 51, and the curved plate-like portion 60b comes into close contact with the bottom surface 51b of the fitting recess 51. As a result, the damper member 60 is fixed to the fitting recess 51, as shown in FIG. 3(b). That is, the damper member 60 is fixed to the fitting recess 51 by an elastic restoring force generated by compression of the first rubber layer 62 covering the flat plate-like portions 60a. Note that the thin plate portion 61 may also be configured to elastically deform when the damper member 60 is fitted into the fitting recess 51, and by utilizing this restoring force, the fitting force can be further increased. In this embodiment, the entire surface of the first rubber layer 62 is configured to be in close contact with both side surfaces 51 a and the bottom surface 51 b of the fitting recess 51. However, it is not necessary for the entire surface of the first rubber layer 62 to be in close contact with both side surfaces 51 a and the bottom surface 51 b of the fitting recess 51, and a configuration in which a portion of the surface does not come into contact with the fitting recess 51 may be employed.

[0023] <Advantages of the planetary gear mechanism according to this embodiment> According to the planetary gear mechanism 1 of this embodiment, the damper member 60 is disposed between the protrusion 22 provided on the internal gear 20 and the fitting recess 51 provided on the inner circumferential surface of the housing 50. This reduces friction between the internal gear 20 and the housing 50, and also reduces the generation of impact noise due to collision between them. In the damper member 60 of this embodiment, a first rubber layer 62 and a second rubber layer 63 are provided on both sides of a metal thin plate portion 61, and the first rubber layer 6 2 is in close contact with the fitting recess 51, and the second rubber layer 63 is in close contact with the protrusion 22. These first rubber layer 62 and second rubber layer 63 absorb shocks and vibrations.

[0024] The damper member 60 is fitted into a fitting recess 51 provided on the inner circumferential surface of the housing 50, thereby preventing the damper member 60 from being misaligned due to the influence of the internal gear 20. This will be explained in more detail below. As the planetary gears 30 revolve in accordance with the rotation of the sun gear 10, a force acts to rotate the internal gear 20. This causes the protrusions 22 provided on the internal gear 20 to repeatedly vibrate in the circumferential direction relative to the fitting recess 51, which may cause friction and impact noise as described above, and may also have some effect on the damper member 60. However, in this embodiment, the damper member 60 is fitted into the fitting recess 51 provided on the inner circumferential surface of the housing 50, thereby preventing the damper member 60 from being affected by the internal gear 20.

[0025] This point will be explained with reference to a comparative example shown in Fig. 4. In this comparative example, a configuration is adopted in which a damper member 90 is fitted to the protrusion 22. Fig. 4(a) shows the state in which the damper member 90 is being fitted to the protrusion 22 in the direction of the arrow, and Fig. 4(b) shows the state in which the damper member 90 is fitted to the protrusion 22. When such a configuration is adopted, as described above, the protrusion 22 behaves in such a way that it repeatedly vibrates in the circumferential direction relative to the fitting recess 51, and it has been found that this causes the damper member 90 to shift outward in the radial direction, as shown by the arrow in Fig. 4(c), resulting in incomplete fitting or, depending on the dimensions and shape, causing the damper member 90 to fall off.

[0026] In contrast to this, by employing the configuration of this embodiment as described above, it is possible to suppress misalignment of the damper member 60. In this embodiment, the damper member 60 is fitted into the fitting recess 51 so as to be in contact with both side surfaces 51a and the bottom surface 51b of the fitting recess 51, so that misalignment of the damper member 60 can be further suppressed. [Explanation of symbols]

[0027] 1: Planetary gear mechanism 10: Sun gear 11: Teeth 20: Internal gear 21: Teeth 22: Protrusion 30: Planetary gear 41:Second axis 42: Career 50: Housing 51: Fitting recess 51a: Side 51b: Bottom 60: Damper material 60a: Planar part 60b: curved surface portion 61:Thin plate part 62: First rubber layer 63: Second rubber layer

Claims

1. The sun gear and an internal gear arranged concentrically with the sun gear; a plurality of planetary gears disposed between the sun gear and the internal gear; a housing into which the internal gear is fitted; A planetary gear mechanism comprising: A plurality of projections projecting radially outward are provided at intervals in the circumferential direction on an outer peripheral surface of the internal gear, and a plurality of fitting recesses into which the plurality of projections can be loosely fitted are provided on an inner peripheral surface of the housing; a planetary gear mechanism, characterized in that damper members are disposed between the plurality of projections and the fitting recesses, respectively, and are fitted into the fitting recesses.

2. 2. The planetary gear mechanism according to claim 1, wherein the damper member is fitted into the fitting recess so as to contact both side surfaces and a bottom surface of the fitting recess.

3. 3. The planetary gear mechanism according to claim 1, wherein the damper member comprises a thin plate portion made of a thin metal plate and rubber layers provided on both sides of the thin plate portion.

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