Planetary gear unit

Abstract

To provide a planetary gear device which has a compact size in its axial direction.SOLUTION: A planetary gear device (1) comprises a sun gear (5), a carrier (6), a plurality of planetary units (7) arranged at the carrier (6), and a ring gear (9). Each of the planetary units (7) comprises a first planetary gear (71) engaged with the sun gear (5), a second planetary gear (72) engaged with the ring gear (9), a first rotating body (73) arranged coaxially with the first planetary gear (71), a second rotating body (74) arranged coaxially with the second planetary gear (72), and a winding transmission body (75) wound on the first rotating body (73) and the second rotating body (74). The winding transmission bodies (75) of the plurality of planetary units (7) are arranged so as to be at least partially overlapped on one another in an axial direction when viewed from a direction orthogonal from the axial direction.SELECTED DRAWING: Figure 2

Description

[Technical Field]

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

[0002] A planetary transmission has been proposed that includes a casing, two sun gears, a planet carrier, two planet gears, a meshed wheel, and two toothed belts. Each of the two planet gears is formed by integrating a small diameter gear and a large diameter sprocket, and the large diameter sprockets of these planet gears are meshed with the meshed wheel.

[0003] In addition, one of the two toothed belts is wound around one of the two sun gears and the small diameter gear of one of the two planetary gears, and the other of the two toothed belts is wound around the other of the two planetary gears and the small diameter gear of the other of the two planetary gears. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Utility Model Application Publication No. 6-69494 Summary of the Invention [Problem to be solved by the invention]

[0005] The planetary transmission of Patent Document 1 can function as a reducer that outputs reduced rotation from the planet carrier by fixing the meshed gear and using the sun gear as an input, out of the three elements of the sun gear, planet carrier, and meshed gear. Also, by fixing the meshed gear and using the planet carrier as an input, it can function as a speed increaser that outputs increased rotation from the sun gear.

[0006] However, the planetary transmission of Patent Document 1 has two toothed belts that are offset in the direction of the rotation axis, which causes the axial length of the planetary transmission to become long. In particular, with this configuration, the greater the number of planet gears and toothed belts, the longer the axial length of the planetary transmission becomes.

[0007] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a planetary gear device that is compact in the axial direction. [Means for solving the problem]

[0008] One aspect of the present invention is a planetary gear device comprising: a sun gear; a carrier; a plurality of planetary units provided on the carrier; and a ring gear, each of the planetary units comprising: a first planetary gear meshed with the sun gear and rotatably supported by the carrier; a second planetary gear meshed with the ring gear and rotatably supported by the carrier; a first rotating body arranged coaxially with the first planetary gear; a second rotating body arranged coaxially with the second planetary gear; and a wound transmission body wound around the first rotating body and the second rotating body, wherein each of the wound transmission bodies of the plurality of planetary units is arranged so that at least a portion of them overlap each other in the axial direction when viewed from a direction perpendicular to the axial direction. [Effects of the Invention]

[0009] It is possible to provide an axially compact planetary gear device. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 2 is a front view showing the planetary gear device according to the embodiment with the carrier removed. [Figure 2] FIG. 2 is a cross-sectional view of the planetary gear device shown in FIG. 1 taken along line II-II. [Figure 3] 1A is a side view showing a planetary gear device according to a comparative example, and FIG. 1B is a side view showing the planetary gear device according to the present embodiment. [Figure 4] 4A and 4B are diagrams for explaining a tension adjustment mechanism for a planetary chain 75. [Figure 5] FIG. 10 is a front view showing a planetary gear device according to a modified example with the carrier removed. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0012] (Outline of chain-type planetary sprocket reducer) Fig. 1 shows a chain-type planetary sprocket reducer 1 as a planetary gear device according to this embodiment. As shown in Fig. 2, this chain-type planetary sprocket reducer 1 is disposed between an input shaft 2 as a first shaft to which input rotation is transmitted from a drive source (not shown), and an output shaft 3 as a second shaft whose axis is aligned with that of the input shaft 2, and is a reducer that reduces the input rotation input to the input shaft 2 and outputs it from the output shaft 3.

[0013] Specifically, the reducer 1 is configured to include a sun gear 5 provided on the input shaft 2, a carrier 6, a plurality of planetary units 7 (three in this embodiment) provided on the carrier 6, and a ring gear (internal gear) 9 provided on the output shaft 3. When the input shaft 2 is driven to rotate by a driving force from a driving source such as a motorbike, the sun gear 5 rotates integrally with the input shaft 2.

[0014] The carrier 6 is configured by a pair of circular flat plates 61, 62 connected at a predetermined axial distance by collar bolts 63 as fasteners, and a plurality of planetary units 7 are arranged between these flat plates 61, 62. In this embodiment, the carrier 6 is configured to be fixed to a fixing member (not shown).

[0015] The multiple planetary units 7 each include a first planetary gear 71 that meshes with the sun gear 5, a second planetary gear 72 that meshes with the ring gear 9, a first planetary sprocket 73, a second planetary sprocket 74, and a planetary chain 75 that is wound around the first planetary sprocket 73 and the second planetary sprocket 74.

[0016] The first planetary gear 71 is rotatably supported by the carrier 6 via a first planetary shaft 76. The first planetary shaft 76 is provided with the first planetary sprocket 73, and the first planetary sprocket 73 and the first planetary gear 71 are configured to rotate integrally. More specifically, the first planetary sprocket 73 is rotatably supported by the first planetary shaft 76, and the first planetary gear 71 is fixed to a hub portion 73a of the first planetary sprocket 73 that extends in the axial direction of the first planetary shaft 76.

[0017] The second planetary gear 72 has a larger diameter and has a greater number of teeth than the first planetary gear 71, and is rotatably supported by the carrier 6 via a second planetary shaft 77. The second planetary shaft 77 is provided with a second planetary sprocket 74 having a larger diameter than the first planetary sprocket 73, and the second planetary sprocket 74 and the second planetary gear 72 are configured to rotate integrally.

[0018] More specifically, the second planetary sprocket 74 and the second planetary gear 72 are rotatably supported on the second planetary shaft 77, and the second planetary sprocket 74 and the second planetary gear 72 are connected by a bolt 78 as a fastening member so as to rotate as a unit. The first planetary sprocket 73 and the second planetary sprocket 74 are drivingly connected by a planetary chain 75, thereby drivingly connecting the first planetary gear 71 and the second planetary gear 72. Furthermore, a tensioner roller (not shown) is disposed between the first planetary sprocket 73 and the second planetary sprocket 74, and applies an appropriate tension to the planetary chain 75 to prevent tooth skipping.

[0019] The ring gear 9 has a drum shape and includes a bottom portion 91 extending in the radial direction and a flange portion 92 extending in the axial direction from the outer peripheral edge of the bottom portion 91. The bottom portion 91 is fixed to a flange portion 3a of an output shaft 93 by fasteners 93 such as bolts. The flange portion 92 is formed separately from the bottom portion 91 and is fixed to the bottom portion 91 by fasteners 95 such as bolts. A tooth surface that meshes with the second planetary gear 72 is formed on the inner peripheral surface of the flange portion 92. The ring gear 9 has a larger diameter and has a larger number of teeth than the sun gear 5 and the first and second planetary gears 71 and 72.

[0020] With this configuration, when input rotation is input to the input shaft 2, the sun gear 5 rotates. When the sun gear 5 rotates, power is transmitted to each of the three planetary units 7 via the first planetary gear 71 meshing with the sun gear 5. Because the carrier 6 of each of these three planetary units 7 is fixed, when rotation is input from the sun gear 5, the rotating bodies 71, 72, 73, and 74 rotate on their axes without revolving. More specifically, because the second planetary sprocket 74 is a sprocket with a larger number of teeth than the first planetary sprocket 73, the rotation input from the sun gear 5 is reduced in speed and transmitted to the ring gear 9 by the second planetary gear 72. The ring gear 9 is rotated by the second planetary gear 72, and as a result, rotation slower than the rotational speed of the input shaft 2 is output from the output shaft 3 integrated with the ring gear 9.

[0021] (Axial length of chain-type planetary sprocket reducer) Next, we will explain the axial length of the chain-type planetary sprocket reducer 1. As described above, in this embodiment, the planetary unit 7 does not have the planetary chain 75 wound directly around the sun gear 5, but has the first planetary gear 71 as an intermediate gear, and this first planetary gear 71 is meshed with the sun gear 5.

[0022] Therefore, even if the reducer 1 of this embodiment has multiple planetary units 7, it is configured so that the axial positions of the first planetary sprocket 73, second planetary sprocket 74 and planetary chain 75 of each planetary unit 7 can be aligned by changing the phase of these planetary units 7.

[0023] When multiple planetary chains 75 are wound directly around the sun gear 51, each chain 75 must be offset in the axial direction to prevent interference. Therefore, when three planetary units are arranged, as in the comparative example shown in Figure 3(a), a width L3 equivalent to at least three chains is required.

[0024] 3(b), in this embodiment, the planetary chains 75 are arranged so that they overlap in the axial direction, so that even when three planetary units 7 are arranged, they can be arranged with a width L1 that is the same as that of one chain. Therefore, even if the allowable torque is the same between the reducer of the comparative example and the reducer 1 according to this embodiment, the reducer 1 according to this embodiment can be configured with a compact axial length.

[0025] 2, the gear trains of the sun gear 5 and first planetary gear 71 and the ring gear 9 and second planetary gear 72 are located radially inward of the tooth flank of the ring gear 9, while the drive train of the first planetary sprocket 73, second planetary sprocket 74, and planetary chain 75 are offset axially toward the input shaft with respect to the ring gear 9. As a result, the tooth tip position of the second planetary sprocket 74 is located radially outward of the tooth tip of the ring gear 9, making it possible to use planetary sprockets 73, 74 with larger diameters. This allows for greater design freedom and enables the gear ratio to be designed over a wide range.

[0026] (tension adjustment mechanism) Next, we will explain the tension adjustment mechanism for the planetary chain 75. In the tension adjustment mechanism according to this embodiment, the second planetary sprocket 74 can be attached in a plurality of different phases, thereby configuring the tension adjustment mechanism for the planetary chain 75.

[0027] 4, six mounting holes 741 to 743 for bolts 78 that secure the second planetary sprocket 74 to the second planetary gear 72 are formed on the side of the second planetary sprocket 74. These mounting holes 741 to 743 are arranged in sets of two diagonally positioned mounting holes, allowing the second planetary sprocket 74 to be mounted in three different phases that differ in the degree of engagement between the planetary chain 75 and the second planetary sprocket 74.

[0028] 4 are in different phases, and the second planetary sprocket 74 can be fixed to a first mounting position fixed by a first mounting hole 741, a second mounting position fixed by a second mounting hole 742, and a third mounting position fixed by a third mounting hole 743. The positions where imaginary lines 741L to 743L connecting the centers of the mounting holes 741 to 743 intersect with the tooth flanks between adjacent tooth tips are in different phases in the rotation direction of the second planetary sprocket 74 at these first to third mounting positions, and it can be seen that the first to third mounting positions are positions where the meshing between the planetary chain 75 and the second planetary sprocket 74 has progressed at different degrees.

[0029] As described above, the distance of the chain from the center of the sprocket changes depending on the degree of engagement with the sprocket. Therefore, by changing the fixed position of the second planetary sprocket 74 between these first to third mounting positions, it is possible to change the phase of the second planetary sprocket 74 relative to the first planetary sprocket 73, and the tension of the planetary chain 75 can be adjusted.

[0030] As described above, in this embodiment, the plurality of mounting holes 741-743 and the bolts 78 form a tension adjustment mechanism, which makes it possible to fix the second planetary sprocket 74 at a plurality of phase positions where the degree of meshing of the chain differs relative to the first planetary sprocket 73 at the first phase position, as shown in Fig. 4. Then, by changing the relative rotational phase relationship (rotational position relationship) between the first planetary sprocket 73 and the second planetary sprocket 74, it is possible to adjust the tension of the planetary chain 75.

[0031] <Summary> The planetary gear device (1) according to this embodiment has: Sangia (5) and Career (6) and a plurality of planetary units (7) provided on the carrier (6); a ring gear (9); Each of the planetary units (7) a first planetary gear (71) meshing with the sun gear (5) and rotatably supported by the carrier (6); a second planetary gear (72) meshing with the ring gear (9) and rotatably supported by the carrier (6); a first rotor (73) arranged coaxially with the first planetary gear (71); a second rotor (74) arranged coaxially with the second planetary gear (72); a winding transmission body (75) wound around the first rotor (73) and the second rotor (74), The wound transmission bodies (75) of the plurality of planetary units (7) are arranged so that at least a portion of them overlap each other in the axial direction when viewed from a direction perpendicular to the axial direction.

[0032] In this way, by arranging the wound transmission bodies 75 of the multiple planetary units 7 so that at least a portion of them axially overlap one another when viewed from a direction perpendicular to the axial direction, it is possible to configure the planetary gear device 1 in an axially compact manner. In particular, in the case of a motorcycle that uses a high-speed, low-torque motor as a drive source, the axial length of the motor is long, so it is necessary to shorten the axial length of the transmission. However, by using the planetary gear device 1 according to the present embodiment, it is possible to configure a transmission that is compact in the axial direction. Note that the drive source is not limited to a motor, but may be, for example, an engine, and the planetary gear device 1 according to the present embodiment can be used in transmissions for bicycles, automobiles, and other devices, not just motorcycles.

[0033] Furthermore, compared to a general gear-type planetary gear mechanism, the planetary gear device 1 according to this embodiment uses the wrapped power transmission body 75, which makes it easier to adjust backlash and reduces design and assembly costs. Furthermore, the allowable torque can be easily changed by changing the size and number of the wrapped power transmission body 75. In addition, since the number of planetary units 7 can be changed without changing the axial length of the planetary gear device 1, the allowable input value can be increased while keeping the planetary gear device 1 compact.

[0034] In the above-described embodiment, an example has been described in which the carrier 6 is fixed and the planetary gear device 1 is used as a reducer, but this is not limiting. The planetary gear device 1 can not only reduce speed, but also generate accelerated rotation or reverse rotation by changing the input, output, and fixation among the three elements of the sun gear 5, carrier 6, and ring gear 9. For example, by fixing the carrier, inputting the ring gear, and outputting the sun gear, it can function as a speed-up device.

[0035] In the above-described embodiment, a planetary chain 75 is used as the wrapped power transmission body, a first planetary sprocket 73 is used as the first rotating body, and a second planetary sprocket 74 is used as the second rotating body. However, the planetary chain 75 may be other types of chains rather than a roller chain. For example, as shown in FIG. 5, the planetary chain may be formed of a silent chain 751. Furthermore, the wrapped power transmission body does not necessarily have to be a chain, and may be, for example, a toothed belt, a flat belt, or a V-belt. Furthermore, the first rotating body and the second rotating body may be formed of pulleys or the like.

[0036] Furthermore, the first planetary gear 71 and the first planetary sprocket 73 may be provided integrally, and the second planetary gear 72 and the second planetary sprocket 74 may be provided integrally. Furthermore, the first planetary gear 71, the first planetary sprocket 73, the second planetary gear 72, and the second planetary sprocket 74 may be of any size. For example, the first planetary sprocket 73 and the second planetary sprocket 74 may be configured to have the same number of teeth. Furthermore, in the above-described embodiment, the second planetary sprocket 74 is configured to be attachable in a plurality of positions, thereby making it possible to change the relative rotational phase relationship (rotational position relationship) between the first planetary sprocket 73 and the second planetary sprocket 74. However, the first planetary sprocket 73 may be configured to be attachable in a plurality of positions. Furthermore, if the relative rotational phase relationship (rotational position relationship) between the first planetary sprocket 73 and the second planetary sprocket 74 can be changed, the position of the sprocket does not necessarily have to be fixed by bolts and mounting holes; for example, the position of the sprocket can be fixed by fitting of recesses and protrusions. [Explanation of symbols]

[0037] 1: Planetary gear device (chain-type planetary sprocket reducer) 5: Sun Gear 6: Career 7: Planetary Unit 9: Ring gear 71: First planetary gear 72: Second planetary gear 73: First rotating body (first planetary sprocket) 74: Second rotating body (first planetary sprocket) 75: Winding transmission element (planetary chain)

Claims

[Claim 1] Sungia and Career and a plurality of planetary units provided on the carrier; a ring gear; Each of the planetary units is a first planetary gear meshing with the sun gear and rotatably supported by the carrier; a second planetary gear that meshes with the ring gear and is rotatably supported by the carrier; a first rotor arranged coaxially with the first planetary gear; a second rotor arranged coaxially with the second planetary gear; a wound transmission body wound around the first rotating body and the second rotating body, The wound transmission bodies of the plurality of planetary units are arranged so that at least a portion of each of the wound transmission bodies overlaps with each other in the axial direction when viewed from a direction perpendicular to the axial direction. A planetary gear device characterized by:

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