Planetary gear mechanism

Abstract

Provided is a planetary gear mechanism that can obtain a wide range of reduction ratios from a low reduction ratio to a high reduction ratio, has a good power transmission efficiency, and has a structure that is thin in the axial direction. A planetary gear mechanism (1) includes a sun gear (2), a first planetary gear (3), a first ring gear (4) fixed to a housing (15), a second planetary gear (6) linked to the first planetary gear (3) via a link shaft (5), a carrier (7) that rotatably supports the link shaft (5), and a second ring gear (8) that meshes with the second planetary gear (6). The carrier (7) is a ring-shaped carrier disposed between the first planetary gear (3) and the second planetary gear (6). The sun gear (2) includes a support shaft (9) that rotatably supports the carrier (7).

Description

Technical Field

[0001] This invention relates to planetary gear mechanisms. This application claims priority to Japanese Patent Application No. 2024-054801, filed on March 28, 2024, the contents of which are incorporated herein by reference. Background Technology

[0002] As a conventional planetary gear mechanism, there is a known structure in which a planet carrier is used as an input element, and a first planetary gear and a second planetary gear supported on the planet carrier are respectively meshed with a first sun gear and a second sun gear fixed to the housing, thereby using the second sun gear as an output element (for example, see Patent Document 1).

[0003] The planetary gear mechanism described in Patent Document 1 is also known as the 2K-HII type planetary gear mechanism, which can obtain a wide range of reduction ratios from low to high reduction ratios and has a thinner structure in the axial direction.

[0004] However, there is room for improvement in the power transmission efficiency of the planetary gear mechanism described in Patent Document 1.

[0005] On the other hand, as other conventional planetary gear mechanisms, there is a known structure in which the sun gear is used as an input element, and the first planetary gear and the second planetary gear supported on the planet carrier mesh with the first internal gear and the second internal gear fixed to the housing, respectively, thereby using the second internal gear as an output element (for example, see Patent Document 2).

[0006] The planetary gear mechanism described in Patent Document 2, also known as the 3K type planetary gear mechanism, can achieve a wide range of reduction ratios from low to high, and its power transmission efficiency is improved compared to the 2K-HII type planetary gear mechanism.

[0007] Existing technical documents

[0008] Patent documents

[0009] Patent Document 1: Japanese Patent Application Publication No. 2010-144839

[0010] Patent Document 2: Japanese Patent Application Publication No. 2023-150298 Summary of the Invention

[0011] The problem that the invention aims to solve

[0012] However, there is room for improvement in the planetary gear mechanism described in Patent Document 2 in terms of forming a thinner structure in the axial direction.

[0013] The purpose of this invention is to provide a planetary gear mechanism that can achieve a wide range of reduction ratios from low to high, has good power transmission efficiency, and has a thin structure in the axial direction.

[0014] Methods for solving problems

[0015] (1) The present invention is a planetary gear mechanism comprising: a sun gear, which is either an input rotating element or an output rotating element; a first planetary gear meshing with the sun gear; a first internal gear meshing with the first planetary gear and fixed to a housing; a second planetary gear connected to the first planetary gear via a connecting shaft; a planet carrier rotatably supporting the connecting shaft; and a second internal gear meshing with the second planetary gear and being the other of the input rotating element and the output rotating element, wherein the planet carrier is an annular planet carrier disposed between the first planetary gear and the second planetary gear, and the sun gear having a support shaft rotatably supporting the planet carrier.

[0016] (2) In the planetary gear mechanism of (1) above, preferably, one end of the connecting shaft is integrally disposed in either the first planetary gear or the second planetary gear, and the other end of the connecting shaft is fitted into a fitting hole disposed in the other of the first planetary gear and the second planetary gear.

[0017] (3) In the planetary gear mechanism of (2) above, preferably, the outer surface shape of the other end of the connecting shaft and the inner surface shape of the fitting hole respectively include a plane and a curved surface, the plane extending in the axial direction and the curved surface extending in the axial direction and protruding radially outward.

[0018] (4) In the planetary gear mechanism of (3) above, it is preferred that the outer surface shape of the other end of the connecting shaft and the inner surface shape of the fitting hole each have two planes and two curved surfaces, the two planes are arranged at a position opposite to each other across the central axis of the fitting hole, and the two curved surfaces are arranged in a manner connected between the two planes.

[0019] The effects of the invention

[0020] According to the present invention, a planetary gear mechanism is provided that can achieve a wide range of reduction ratios from low to high, has good power transmission efficiency, and has a thin structure in the axial direction. Attached Figure Description

[0021] Figure 1 This is a schematic cross-sectional view of a planetary gear mechanism as one embodiment of the present invention.

[0022] Figure 2 It is a graph showing the transmission efficiency relative to the tooth surface efficiency of the 3K type planetary gear mechanism calculated for each reduction ratio.

[0023] Figure 3 It is a graph showing the transmission efficiency relative to the tooth surface efficiency of the 2K-HII type planetary gear mechanism calculated for each reduction ratio.

[0024] Figure 4 It is a schematic representation from the direction of the axis. Figure 1 A schematic diagram of the assembly state of the first planetary gear and the second planetary gear involved in the planetary gear mechanism.

[0025] Figure 5 It is a schematic representation from the direction of the axis. Figure 1 A schematic diagram of another assembly state of the first planetary gear and the second planetary gear involved in the planetary gear mechanism. Detailed Implementation

[0026] Hereinafter, the planetary gear mechanism according to embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0027] In addition, unless otherwise specified, the meanings of the terms are defined as follows in the following description.

[0028] For example, "axial direction" refers to the direction in which the axis extends. "Input side" refers to one side of the axial direction. "Output side" refers to the other side of the axial direction. Furthermore, "circumferential" refers to the direction around the axis. Moreover, "radial" refers to the direction orthogonal to the axis. Specifically, "radial inner side" refers to the side closer to the axis. Furthermore, "radial outer side" refers to the side farther from the axis.

[0029] Figure 1 The diagram schematically illustrates a planetary gear mechanism 1 as one embodiment of the present invention.

[0030] The planetary gear mechanism 1 includes: a sun gear 2, which is either an input rotary element or an output rotary element; a first planetary gear 3, which meshes with the sun gear 2; a first internal gear 4, which meshes with the first planetary gear 3 and is fixed to a housing 15; a second planetary gear 6, which is connected to the first planetary gear 3 via a connecting shaft 5; a planet carrier 7, which rotatably supports the connecting shaft 5; and a second internal gear 8, which meshes with the second planetary gear 6 and is the other of the input rotary element and the output rotary element. The planet carrier 7 is an annular planet carrier disposed between the first planetary gear 3 and the second planetary gear 6. The sun gear 2 includes a support shaft 9 that rotatably supports the planet carrier 7.

[0031] Reference numeral O1 indicates the central axis of the planetary gear mechanism 1. In this embodiment, the planetary gear mechanism 1 connects the input shaft 11 and the output shaft 12. In this embodiment, the input shaft 11 and the output shaft 12 are coaxially arranged with the same central axis O1 (hereinafter also simply referred to as "axis O1") of the planetary gear mechanism 1. The input shaft 11 and the output shaft 12 are rotation axes that rotate circumferentially about axis O1.

[0032] In this embodiment, the sun gear 2 is an external gear that serves as an input rotation element. In this embodiment, the sun gear 2 is connected to the input shaft 11.

[0033] In this embodiment, the sun gear 2 and the support shaft 9 are included in the sun gear component 20. In this embodiment, the sun gear component 20 includes the sun gear 2, the support shaft 9, and the connecting portion 21.

[0034] In this embodiment, the connecting part 21 is integrally formed on the input side of the sun gear 2. In this embodiment, the input shaft 11 is fixed to the connecting part 21. In this embodiment, the connecting part 21 fixes the input shaft 11 by externally fitting it into the connecting part. However, for example, the input shaft 11 can also be internally fitted into the connecting part 21. That is, the connecting part 21 can be fixed by various methods such as bolt fastening.

[0035] In this embodiment, the support shaft 9 is disposed on the output side of the sun gear 2. In this embodiment, the planet carrier 7 is supported on the support shaft 9 via an annular bearing 13a. In this embodiment, the support shaft 9 has an outer peripheral surface F2 with the axis O1 as its central axis.

[0036] The planet carrier 7 has a through hole A7 extending through in the axial direction. In this embodiment, the planet carrier 7 has an annular rim 7a and a sleeve 7b. In this embodiment, the sleeve 7b is provided on the output side of the rim 7a. In this embodiment, the inner circumferential surface of the through hole A7 is formed by an rim-side inner circumferential surface F71 on the rim 7a side and a sleeve-side inner circumferential surface F72 on the sleeve 7b side. In this embodiment, the annular bearing 13a supports the outer circumferential surface F2 of the support shaft 9 and the rim-side inner circumferential surface F71 of the planet carrier 7. That is, in this embodiment, the annular bearing 13a rotatably supports the sun gear component 20 and the planet carrier 7.

[0037] In this embodiment, the inner circumferential surface F71 on the edge side and the inner circumferential surface F72 on the sleeve side are inner circumferential surfaces with the same diameter in the axial direction. Therefore, in this embodiment, the inner circumferential surface of the planet carrier 7 forms a straight cylindrical inner circumferential surface extending in the axial direction. However, the inner circumferential surface F71 on the edge side and the inner circumferential surface F72 on the sleeve side can also be inner circumferential surfaces with different diameters. In this case, the inner circumferential surface of the planet carrier 7 forms an inner circumferential surface with steps.

[0038] The planetary carrier 7 has mounting holes h7 for mounting the connecting shaft 5. In this embodiment, the mounting hole h7 is a through hole formed in the edge 7a. In this embodiment, the connecting shaft 5 is rotatably supported on the edge 7a via an annular bearing 13b disposed in the mounting hole h7. Thus, in this embodiment, the connecting shaft 5 can rotate circumferentially relative to the planetary carrier 7 about the planetary gear central axis O5. In this embodiment, the connecting shaft 5 is supported on the planetary carrier 7 via two annular bearings 13b spaced apart in the axial direction. However, at least one annular bearing 13b may be provided. In this embodiment, the planetary carrier 7 has a plurality of mounting holes h7. The plurality of mounting holes h7 are spaced apart circumferentially about the axis O1.

[0039] One end of the connecting shaft 5 may be integrally formed in either the first planetary gear 3 or the second planetary gear 6. In this case, the other end of the connecting shaft 5 may be fitted into the fitting hole A1 of the other of the first planetary gear 3 and the second planetary gear 6.

[0040] In this embodiment, the input end (one end) of the connecting shaft 5 is integrally formed on the first planetary gear 3. The output end (the other end) of the connecting shaft 5 is pressed into and fitted into the fitting hole A1 provided on the second planetary gear 6. In this embodiment, the first planetary gear 3 and the second planetary gear 6 are arranged on the same planetary gear central axis O5 (hereinafter also simply referred to as "axis O5").

[0041] In this embodiment, the first planetary gear 3 meshes with the sun gear 2 on the radially inner side and with the first internal gear 4 on the radially outer side.

[0042] In this embodiment, the first internal gear 4 is an internal gear fixed to the housing 15. The housing 15 is, for example, a fixed part such as the housing of a planetary gear device that does not rotate around an axis. Thus, the first planetary gear 3 can rotate by input from the sun gear component 20, rotating on its own axis O5 along the inner side of the first internal gear 4, and revolving around the axis O1 along the inner side of the first internal gear 4 along the internal teeth of the first internal gear 4.

[0043] The second planetary gear 6 is connected to the first planetary gear 3 via a connecting shaft 5. Thus, the second planetary gear 6 can also rotate on its own axis O5 and revolve around its own axis O1. In this embodiment, the second planetary gear 6 meshes with the second internal gear 8 on its radially outer side. Therefore, the second internal gear 8 can also rotate circumferentially around its own axis O1.

[0044] In this embodiment, the second internal gear 8 is an internal gear that serves as an output rotating element. In this embodiment, the second internal gear 8 is connected to the output shaft 12.

[0045] In this embodiment, the second internal gear 8 is included in the internal gear component 80. In this embodiment, the internal gear component 80 includes the second internal gear 8, the connecting portion 81, and the connecting wall 82.

[0046] In this embodiment, the connecting wall 82 is a wall that connects the second internal gear 8 to the connecting portion 81. In this embodiment, the connecting wall 82 connects the output side of the second internal gear 8 to the output side of the connecting portion 81. In this embodiment, the internal gear component 80 is rotatably supported on the housing 15 via the ring bearing 13d.

[0047] In this embodiment, the output shaft 12 is fixed to the connecting portion 81. In this embodiment, the connecting portion 81 fixes the output shaft 12 by incorporating it. However, the connecting portion 81 can also be provided on the output side of the connecting wall 82, thereby allowing the output shaft 12 to be incorporated or externally fitted. That is, the connecting portion 81 can be fixed using various methods such as bolt tightening. Therefore, in this embodiment, the output shaft 12 can rotate circumferentially about the axis O1 by the input rotation from the second internal gear 8.

[0048] In this embodiment, the connecting portion 81 is a sleeve for fixing the output shaft 12. In this embodiment, the planetary carrier 7 is supported on the connecting portion 81 via an annular bearing 13c. In this embodiment, the connecting portion 81 has an outer peripheral surface F8 with the axis O1 as its central axis. In this embodiment, the annular bearing 13c supports the inner peripheral surface F72 of the planetary carrier 7 on the sleeve side and the outer peripheral surface F8 of the connecting portion 81 of the internal gear component 80. That is, in this embodiment, the annular bearing 13c rotatably supports the planetary carrier 7 and the second internal gear 8.

[0049] According to the planetary gear mechanism 1, by using the sun gear 2 as an input element, the first planetary gear 3 and the second planetary gear 6 supported on the planet carrier 7 respectively mesh with the first internal gear 4 fixed to the housing 15 and the second internal gear 8 supported relative to the housing 15 via the ring bearing 13d, thereby enabling the second internal gear 8 to function as an output element. That is, the planetary gear mechanism 1 functions as a 3K type planetary gear mechanism.

[0050] here, Figure 2 This is a graph showing the transmission efficiency relative to the tooth surface efficiency of the 3K type planetary gear mechanism calculated for each reduction ratio. Figure 2 The curve is the result calculated by using the planetary gear mechanism 1 of this embodiment as a model of the 3K type planetary gear mechanism.

[0051] exist Figure 2In the diagram, the horizontal axis represents the overall tooth surface efficiency η1 and η2 of the planetary gear mechanism 1. The vertical axis represents the transmission efficiency (power transmission efficiency) of the planetary gear mechanism 1. Figure 2 The curve represents the transmission efficiency relative to the tooth surface efficiency when the reduction ratio is fixed.

[0052] exist Figure 2 The graph shows four cases: a reduction ratio of 50, a reduction ratio of 100, a reduction ratio of 150, and a reduction ratio of 200. Furthermore, the calculation results were obtained by using the sun gear 2 as the input rotating element and the second internal gear 8 as the output rotating element.

[0053] like Figure 2 As shown, the planetary gear mechanism 1 can achieve a wide range of reduction ratios from low to high, with good transmission efficiency. In particular, even at high reduction ratios (e.g., the highest reduction ratio of 200), the minimum transmission efficiency exceeds 0.40.

[0054] then, Figure 3 This is a graph showing the transmission efficiency relative to the tooth surface efficiency of the 2K-HII type planetary gear mechanism calculated for each reduction ratio. Figure 3 In the diagram, the horizontal axis represents the overall tooth surface efficiency η2 of the 2K-HII planetary gear mechanism. The vertical axis represents the transmission efficiency (power transmission efficiency) of the 2K-HII planetary gear mechanism. Figure 3 The curve was calculated using the planetary gear mechanism described in Patent Document 1 as a model of the 2K-HII type planetary gear mechanism.

[0055] exist Figure 3 The graph also shows four cases: a reduction ratio of 50, a reduction ratio of 100, a reduction ratio of 150, and a reduction ratio of 200. Furthermore, the calculation results were obtained by using the planetary carrier as the input rotating element and the second sun gear as the output rotating element.

[0056] like Figure 3 As shown, although a wide range of reduction ratios, from low to high, can be obtained, there is room for improvement in power transmission efficiency. In particular, even at low reduction ratios (e.g., the lowest reduction ratio of 50), the transmission efficiency of the planetary gear mechanism 1 is less than 0.40. As for high reduction ratios (e.g., the highest reduction ratio of 200), the lowest value of the transmission efficiency is less than 0.10.

[0057] from Figure 2 The curve and Figure 3The comparison results of the curves clearly show that, compared with the 2K-HII planetary gear mechanism, the 3K type planetary gear mechanism can obtain a wide range of reduction ratios from low to high, and has good transmission efficiency.

[0058] On the other hand, the conventional 3K-type planetary gear mechanism described in Patent Document 2 holds the planetary gears by having planet carriers spaced apart in the axial direction. Therefore, there is room for improvement in the conventional 3K-type planetary gear mechanism in terms of forming a thinner structure in the axial direction.

[0059] In contrast, the planetary gear mechanism 1 of this embodiment rotatably supports the connecting shaft 5 connecting the first planetary gear 3 and the second planetary gear 6 via a planet carrier 7 disposed between the first planetary gear 3 and the second planetary gear 6. In other words, the planetary gear mechanism 1 rotatably supports both the first planetary gear 3 and the second planetary gear 6 via a single planet carrier 7. That is, according to the planetary gear mechanism 1, one of the two planet carriers that are spaced apart in the axial direction in the conventional 3K type planetary gear mechanism can be eliminated. Therefore, compared with the conventional 3K type planetary gear mechanism, the planetary gear mechanism 1 becomes a planetary gear mechanism with a thinner structure in the axial direction. Furthermore, since only one planet carrier 7 is needed to include in the planetary gear mechanism 1, even compared with the conventional 2K-HII type planetary gear mechanism described in Patent Document 1, this planetary gear mechanism 1 can maintain the same thinness as the conventional 2K-HII type planetary gear mechanism.

[0060] Therefore, according to the planetary gear mechanism 1, a planetary gear mechanism can be provided that can obtain a wide range of reduction ratios from low to high reduction ratios, has good power transmission efficiency, and has a thin structure in the axial direction.

[0061] Furthermore, in this embodiment, the first planetary gear 3 and the second planetary gear 6 are assembled in such a way that the input end of the connecting shaft 5 is integrally formed with the first planetary gear 3, and the output end of the connecting shaft 5 is fitted into the fitting hole A1 of the second planetary gear 6. Alternatively, the first planetary gear 3 and the second planetary gear 6 can also be assembled in such a way that the output end of the connecting shaft 5 is integrally formed with the second planetary gear 6, and the input end of the connecting shaft 5 is fitted into the fitting hole A1 of the first planetary gear 3. In these cases, the assembly of the first planetary gear 3 and the second planetary gear 6 can be easily performed. However, the assembly of the first planetary gear 3 and the second planetary gear 6 can also be performed in such a way that the input end of the connecting shaft 5 is fitted into the fitting hole A1 of the first planetary gear 3, and the output end of the connecting shaft 5 is fitted into the fitting hole A1 of the second planetary gear 6.

[0062] Figure 4 The assembly state of the first planetary gear 3 and the second planetary gear 6 is schematically shown along the axial direction. Furthermore, Figure 5 The diagram schematically illustrates another assembly state of the first and second planetary gears involved in the planetary gear mechanism 1 from the axial direction.

[0063] For example, Figure 5 The exemplified fitting hole A1 is square when viewed along the axial direction. In this case, the inner surface F1 of the fitting hole A1 is formed by four planes F11 arranged at equal intervals around the axis OA. Therefore, when the output end of the connecting shaft 5 is also set to the same square cross-sectional shape, there are four identical options for fitting the output end of the connecting shaft 5 into the fitting hole A1. In this case, each time the output end of the connecting shaft 5 is rotated 90 degrees around the axis OA, it can be fitted into the shape of the fitting hole A1 in the same way. Therefore, when the shape of the output end of the connecting shaft 5 and the shape of the fitting hole A1 are both square, the probability of assembly with the desired circumferential relative positional relationship between the positions of the teeth of the first planetary gear 3 and the teeth of the second planetary gear 6 is 1 / 4.

[0064] On the other hand, the planetary gear mechanism 1 of this embodiment is a planetary gear reduction mechanism. Therefore, in the planetary gear mechanism 1, the number of teeth of the first planetary gear 3 is different from the number of teeth of the second planetary gear 6. Therefore, when assembling the first planetary gear 3 and the second planetary gear 6, it is necessary to ensure that the phase difference between the phase of the teeth of the first planetary gear 3 and the phase of the teeth of the second planetary gear 6 is consistent. For example, as... Figure 5As shown, in this embodiment, the first planetary gear 3 has more teeth than the second planetary gear 6. Therefore, when assembling the first planetary gear 3 and the second planetary gear 6, in order to ensure that the phase difference between their teeth is consistent, it is necessary to establish a desired circumferential relative positional relationship between the predetermined positions of the teeth of the first planetary gear 3 and the predetermined positions of the teeth of the second planetary gear 6. Therefore, in this embodiment, when assembling the first planetary gear 3 and the second planetary gear 6, special attention needs to be paid to the positions of the teeth of the first planetary gear 3 and the teeth of the second planetary gear 6 in order to ensure that the phase difference between their teeth is consistent.

[0065] Furthermore, in the planetary gear mechanism 1, when the shape of the fitting hole A1 is square, for example, when the output end of the connecting shaft 5 provided on the first planetary gear 3 is made into a square cross-section and the output end of the connecting shaft 5 is pressed and fixed into the square fitting hole A1 provided on the second planetary gear 6, it is difficult to minimize the coaxiality (the degree of offset between the central axis of the first planetary gear 3 and the central axis of the second planetary gear 6) between the first planetary gear 3 and the second planetary gear 6. That is, when the shape of the fitting hole A1 is a square like the fitting hole A1 in the figure, when the output end of the connecting shaft 5 provided on the first planetary gear 3 is pressed and fixed into the fitting hole A1 provided on the second planetary gear 6, it is difficult to assemble the first planetary gear 3 and the second planetary gear 6 on the same central axis.

[0066] In contrast, the outer surface shape of the output end of the connecting shaft 5 and the inner surface shape of the fitting hole A1 can respectively include a plane F11 extending in the axial direction and a curved surface F12 extending in the axial direction and protruding radially outward. In this case, the outer surface shape of the output end of the connecting shaft 5 and the inner surface shape of the fitting hole A1 are formed with a surface F1 of similar shape. In this embodiment, the surface F1 includes the plane F11 and the curved surface F12. That is, in this embodiment, the outer surface shape of the output end of the connecting shaft 5 and the inner surface shape of the fitting hole A1 respectively include the corresponding plane F11 and curved surface F12. Therefore, when the outer surface shape of the output end of the connecting shaft 5 is set to be the same as the inner surface shape of the fitting hole A1, which includes the plane F11 and the curved surface F12, in order to fit the output end of the connecting shaft 5 into the fitting hole A1 in the same way, it is only necessary to match the plane F11 (curved surface F12) of the fitting hole A1 with the corresponding plane F11 (curved surface F12) provided on the output end of the connecting shaft 5. Therefore, when the inner surface shape of the fitting hole A1 is set to include the plane F11 and the curved surface F12, as long as the shape of the output end of the connecting shaft 5 is also set to include the plane F11 and the curved surface F12, the number of options for fitting the output end of the connecting shaft 5 into the fitting hole A1 can be reduced compared to the square case. Therefore, when the shape of the output end of the connecting shaft 5 and the shape of the fitting hole A1 are respectively set to include the plane F11 and the curved surface F12, the probability of assembly with the desired circumferential relative positional relationship between the specified position of the first planetary gear 3 and the specified position of the second planetary gear 6 is higher than that of the square case.

[0067] In this embodiment, the outer surface shape of the output end of the connecting shaft 5 and the inner surface shape of the fitting hole A1 each have two planes F11 and two curved surfaces F12. The two planes F11 are positioned opposite each other across the central axis OA (hereinafter also simply referred to as "axis OA") of the fitting hole A1. In this embodiment, axis OA is the same central axis as axis O5. Furthermore, the two curved surfaces F12 are respectively arranged between the two planes F11. In this embodiment, the two curved surfaces F12 are, for example, arc-shaped curved surfaces that bulge radially outward.

[0068] In other words, in this embodiment, such as Figure 5 As shown, when viewed along the axial direction, the contour shapes of the two planes F11 are each formed by a straight contour shape L1 that is separated by the axis OA and parallel to each other. Furthermore, in this embodiment, as... Figure 4 As shown, when viewed along the axial direction, the contour shapes of the two curved surfaces F12 are formed by the radially outward convex curve contour shape L2.

[0069] According to this embodiment, by providing two planes F11, separated by the axis OA and opposite to each other, on the outer surface shape of the output end of the connecting shaft 5 and the inner surface shape of the fitting hole A1, the shape of the fitting hole A1 can be given a fixed directionality relative to the circumferential direction. For example, as Figure 4 As shown, when the shape of the fitting hole A1 is set to include two planes F11 and two curved surfaces F12, if the shape of the output end of the connecting shaft 5 is also set to include two planes F11 and two curved surfaces F12 respectively, then compared with the square case, the selection schemes for fitting the output end of the connecting shaft 5 into the fitting hole A1 are reduced to the same two. Therefore, when the outer surface shape of the output end of the connecting shaft 5 and the inner surface shape of the fitting hole A1 are set to include two planes F11 and two curved surfaces F12 respectively, the probability of assembly with the desired circumferential relative positional relationship between the specified position of the first planetary gear 3 and the specified position of the second planetary gear 6 is 1 / 2. Therefore, as Figure 5 As shown, if the outer surface shape of the output side end of the connecting shaft 5 and the inner surface shape of the fitting hole A1 are set to include two planes F11 and two curved surfaces F12 respectively, then the probability of assembly with the desired circumferential relative position relationship between the specified position of the first planetary gear 3 and the specified position of the second planetary gear 6 is higher than that of the square case.

[0070] That is, if the outer surface shape of the output end of the connecting shaft 5 and the inner surface shape of the fitting hole A1 are respectively set to include two planes F11 and two curved surfaces F12, then when the connecting shaft 5 is pressed and fixed in the fitting hole A1, the two planes F11 can serve as phase matching references to ensure that the phase difference between the phase of the first planetary gear 3 and the phase of the second planetary gear 6 is consistent. Therefore, by giving the fitting hole A1 directionality, it is not necessary to ensure that the phase of the first planetary gear 3 and the phase of the second planetary gear 6 are consistent, thus preventing the misassembly of the first planetary gear 3 and the second planetary gear 6 due to incorrect assembly, thereby reducing the failure rate. Furthermore, after the connecting shaft 5 is pressed and fixed in the fitting hole A1, the two planes F11 function as anti-rotation elements around the axis OA.

[0071] Furthermore, according to this embodiment, by providing two planes F11 and two curved surfaces F12, separated by an axis OA and facing each other, on the outer surface shape of the output end of the connecting shaft 5 and the inner surface shape of the fitting hole A1, respectively, when the connecting shaft 5 is pressed in, the deformation of the connecting shaft 5 caused by the contact between the two planes F11 on the output end of the connecting shaft 5 and the two planes F11 on the fitting hole A1 can be released to the two curved surfaces F12 on the fitting hole A1. This easily minimizes the coaxiality of the first planetary gear 3 and the second planetary gear 6. That is, when the connecting shaft 5 is pressed and fixed in the fitting hole A1, the first planetary gear 3 and the second planetary gear 6 can be easily assembled on the same central axis. This prevents a decrease in transmission efficiency caused by axial misalignment between the first planetary gear 3 and the second planetary gear 6. Furthermore, since the two curved surfaces F12 provided in the fitting hole A1 have the function of releasing the deformation of the connecting shaft 5 when it is pressed in, the pressing load required when pressing in the connecting shaft 5 can be reduced. As a result, the effects caused by the deformation of the first planetary gear 3 or the second planetary gear 6 that may occur when pressing in the connecting shaft 5 can be reduced, and consequently, the reduction in transmission efficiency can be prevented.

[0072] As in this embodiment, if the outer surface shape of the output end of the connecting shaft 5 and the inner surface shape of the fitting hole A1 are formed by two opposing planes F11 and a curved surface F12 connecting these planes, respectively, it is possible to achieve both phase matching (matching the phase difference) and fixation of the first planetary gear 3 and the second planetary gear 6 through a simple assembly method. Furthermore, by releasing the deformation of the connecting shaft 5 during pressing by the two curved surfaces F12 provided in the fitting hole A1, the pressing load can be reduced. Additionally, the outer surface shape of the output end of the connecting shaft 5 and the inner surface shape of the fitting hole A1 can be, for example, as... Figure 4 As shown, examples can be listed of shapes with chamfered edges on both sides when viewed in the axial direction, achieved by cutting off both ends of the circular hole.

[0073] However, the outer surface shape of the output end of the connecting shaft 5 and the inner surface shape of the fitting hole A1 only need to include the corresponding plane F11 and curved surface F12, respectively, wherein the plane F11 extends in the axial direction and the curved surface F12 extends in the axial direction and protrudes radially outward. For example, such a shape can be exemplified by the end of the connecting shaft 5 and the fitting hole, which are D-shaped when viewed in the axial direction; that is, the end of the connecting shaft 5 and the fitting hole after D-shaped cutting. In this case, the phase matching (making the phase difference consistent) of the first planetary gear 3 and the second planetary gear 6, as well as their fixation, can be achieved through a simple assembly method. Furthermore, in this case, the deformation of the connecting shaft 5 during pressing can be released by a curved surface F12, thereby reducing the pressing load.

[0074] The above description only illustrates exemplary embodiments relating to the present invention, and various modifications can be made according to the scope of the claims.

[0075] Explanation of reference numerals in the attached figures

[0076] 1: Planetary gear mechanism

[0077] 2: Sun Gear

[0078] 3: First Planetary Gear

[0079] 4: First internal gear

[0080] 5: Connecting shaft

[0081] 6: Second planetary gear

[0082] 7: Planetary Carrier

[0083] 7a: Edge section

[0084] 7b: Sleeve

[0085] 8: Second internal gear

[0086] 9: Support shaft

[0087] 11: Input axis

[0088] 12: Output shaft

[0089] 13a, 13b, 13c: Annular bearings

[0090] 15: Casing

[0091] 20: Sun gear component

[0092] 21: Connecting part

[0093] 80: Internal gear components

[0094] 81: Connecting part

[0095] 82: Connecting Wall

[0096] A1: Fitting hole

[0097] A7: Through hole

[0098] F1: Inner surface of the fitting hole

[0099] F11: Plane

[0100] F12: Surface

[0101] F2: Outer circumferential surface of the support shaft

[0102] F71: Inner circumferential surface of the edge of the planetary carrier

[0103] F72: Inner circumferential surface of the sleeve side of the planetary carrier

[0104] F8: Outer circumferential surface of the connecting part of the internal gear component

[0105] h7: Mounting hole

[0106] L1: Straight profile shape

[0107] L2: Curve profile shape

[0108] O1: Central axis of the planetary gear mechanism

[0109] O5: Central axis of planetary gears

[0110] OA: Central axis of the fitting hole

Claims

1. A planetary gear mechanism comprising: a sun gear, which is either an input rotary element or an output rotary element; a first planetary gear meshing with the sun gear; and a first internal gear meshing with the first planetary gear and fixed to a housing; The second planetary gear is connected to the first planetary gear via a connecting shaft; A planetary carrier that rotatably supports the connecting shaft; and a second internal gear that meshes with the second planetary gear and is the other of the input rotary element and the output rotary element. The planet carrier is an annular planet carrier disposed between the first planetary gear and the second planetary gear. The sun gear has a support shaft that rotatably supports the planet carrier.

2. The planetary gear mechanism according to claim 1, wherein, One end of the connecting shaft is integrally disposed on either the first planetary gear or the second planetary gear, and the other end of the connecting shaft is fitted into a fitting hole disposed on the other of the first planetary gear and the second planetary gear.

3. The planetary gear mechanism according to claim 2, wherein, The outer surface shape of the other end of the connecting shaft and the inner surface shape of the fitting hole respectively include a plane and a curved surface, the plane extending in the axial direction and the curved surface extending in the axial direction and protruding radially outward.

4. The planetary gear mechanism according to claim 3, wherein, The outer surface shape of the other end of the connecting shaft and the inner surface shape of the fitting hole respectively have two planes and two curved surfaces. The two planes are positioned opposite each other, separated by the central axis of the fitting hole. The two surfaces are respectively arranged in a manner that connects the two planes.

Images