JP7457489B2 - planetary gearbox - Google Patents

Description

The present invention relates to a planetary gear system.

BACKGROUND ART Conventionally, a speed reducer has been used to reduce the rotational speed of an output shaft of a drive source such as a motor. As a reduction gear, for example, a compound planetary gear device is known, which includes a sun gear, an internal gear, and a plurality of coaxial stages of planetary gears provided between the sun gear and the internal gear (see Patent Document 1). ).

JP 2002-221259 A

By the way, in planetary gear systems, helical gears are used to reduce noise emitted from the gears.

However, when a helical gear transmits power, component force is generated in the axial direction (thrust direction). For this reason, in planetary gear devices using helical gears, friction occurs between the end surfaces of the planetary gears and the end surfaces of the internal gears serving as the receiving surfaces thereof due to component forces in the thrust direction generated in the planetary gears. In conventional planetary gear systems that use helical gears, this friction can reduce efficiency, or the gears can wear out, leading to decreased durability, so it is not possible to reduce the component force in the thrust direction. It was wanted.

The present invention takes the above-mentioned problem as an example, and an object of the present invention is to provide a planetary gear device that can achieve both efficiency and longevity.

In order to achieve the above object, the planetary gear device according to the present invention comprises a first internal gear, a second internal gear spaced apart from the first internal gear in the axial direction, a plurality of first planetary gears meshing with the first internal gear, and a plurality of second planetary gears meshing with the second internal gear, and a plurality of planetary gear units connected in the axial direction so that a set of the first planetary gears and the second planetary gears rotate together, and the first internal gear, the first planetary gears, the second internal gear, and the second planetary gears are constituted by helical gears having a predetermined twist angle with respect to the axial direction, and the first internal gear and the first planetary gears are constituted by helical gears having a predetermined twist angle with respect to the axial direction. The direction of inclination of the helical gear relative to the axial direction and the direction of inclination of the helical gears constituting the second internal gear and the second planetary gear relative to the axial direction are the same, the twist angles of the helical gears constituting the first internal gear and the first planetary gear and the twist angles of the helical gears constituting the second internal gear and the second planetary gear are different, and the twist angles of the helical gears constituting the first internal gear and the first planetary gear and the twist angles of the helical gears constituting the second internal gear and the second planetary gear are determined based on the forces acting in the axial direction of the first internal gear and the first planetary gear and the second internal gear and the second planetary gear, respectively.

In a planetary gear device according to one aspect of the present invention, the second internal gear and the second planetary gear have a different number of teeth than the first internal gear and the first planetary gear, and the helical gears constituting the first internal gear and the first planetary gear and the helical gears constituting the second internal gear and the second planetary gear are set so that the forces acting in the axial direction of the first internal gear and the first planetary gear and the second internal gear and the second planetary gear are equal.

According to the planetary gear device according to the present invention, both efficiency and longevity can be achieved.

1 is a perspective view showing a schematic configuration of a drive unit including a planetary gear device according to an embodiment of the present invention; 1 is a cross-sectional view along an axial direction schematically showing the configuration of a planetary gear device. 2 is a sectional view taken along line AA of the planetary gear device shown in FIG. 1. FIG. 2 is a cross-sectional view taken along the line AA of FIG. 1 showing the sun gear, the planetary gear unit, the first internal gear, and the second internal gear provided in the planetary gear device shown in FIG. 1 . FIG. 2 is a plan view showing a first planetary gear and a first internal gear included in the planetary gear device shown in FIG. 1 . 2 is a plan view showing a second planetary gear and a second internal gear included in the planetary gear device shown in FIG. 1. FIG. 2 is a side view showing a sun gear, a planetary gear unit, and a carrier included in the planetary gear device shown in FIG. 1. FIG. FIG. 2 is a side view showing a planetary gear unit included in the planetary gear device shown in FIG. 1 . 2 is a schematic diagram showing component forces applied to a first planetary gear and a second planetary gear included in the planetary gear device shown in FIG. 1. FIG. FIG. 2 is a schematic diagram showing rotational directions of a sun gear, a second internal gear, and a second planetary gear included in the planetary gear device shown in FIG. 1 and a component force applied to the second planetary gear. FIG. 2 is a schematic diagram showing a component force applied to a planetary gear unit included in the planetary gear apparatus shown in FIG. 1 and a friction surface between the planetary gear unit and the planetary gear shaft. FIG. 2 is a schematic diagram showing a component force applied to a planetary gear included in the planetary gear device shown in FIG. 1. FIG. 2 is a schematic diagram showing forces acting on a planetary gear unit included in the planetary gear device shown in FIG. 1 . FIG.

Hereinafter, a planetary gear device according to an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a perspective view schematically showing the configuration of a drive device 1 including a planetary gear device 2 according to an embodiment of the present invention. As shown in FIG. 1, a drive device 1 includes a planetary gear device 2 according to an embodiment of the present invention and a motor 3 as a drive source.

[Structure of planetary gear device]
Next, the configuration of the planetary gear device 2 according to the present embodiment included in the drive device 1 will be described.

FIG. 2 is a cross-sectional view along the axial direction schematically showing the configuration of the planetary gear device 2. As shown in FIG. Further, FIG. 3 is a sectional view taken along the line AA of the planetary gear device 2. As shown in FIG.

Hereinafter, for convenience of explanation, in the planetary gear device 2, the output side (the side in the direction of the arrow a in FIG. 2) is referred to as the outside, and the input side (the side in the direction of the arrow b in FIG. 2) is referred to as the inside. Further, for convenience of explanation, each configuration of the planetary gear device 2 and the drive device 1 will be explained based on the axis x of the input shaft 20 in the planetary gear device 2 and the drive device 1. The gears constituting the planetary gear device 2 each have an axis.

As shown in FIGS. 2 and 3, the planetary gear device 2 according to the present embodiment includes a first internal gear 120 and a second internal gear provided apart from the first internal gear 120 in the axis x direction. 220, a plurality of first planetary gears 130, 140, 150, 160 meshing with the first internal gear 120, and a plurality of second planetary gears 230, 240, 250, 260 meshing with the second internal gear 220, A plurality of planetary gear units 310 in which a set of first planetary gears 130, 140, 150, 160 and second planetary gears 230, 240, 250, 260 are connected in the axis x direction so as to rotate together; 320, 330, and 340. The first internal gear 120, the first planetary gears 130, 140, 150, 160, the second internal gear 220, and the second planetary gears 230, 240, 250, 260 have a predetermined helix angle with respect to the axis x direction. It is composed of helical gears. The direction in which the helical gears constituting the first internal gear 120 and the first planetary gears 130, 140, 150, 160 are inclined with respect to the axis x direction, and the second internal gear 220 and the second planetary gears 230, 240, 250, 260 The helical gears constituting the two have the same inclination direction with respect to the axis x direction. The helix angle of the helical gears constituting the first internal gear 120 and the first planetary gears 130, 140, 150, 160 and the helical gears constituting the second internal gear 220 and the second planetary gears 230, 240, 250, 260 are The helix angles of helical gears are different. The helix angle of the helical gears constituting the first internal gear 120 and the first planetary gears 130, 140, 150, 160 and the helical angles constituting the second internal gear 220 and the second planetary gears 230, 240, 250, 260. The helix angle of the helical gear is determined by the force acting in the axis x direction of the first internal gear 120, the first planetary gears 130, 140, 150, 160, the second internal gear 220, and the second planetary gears 230, 240, 250, 260, respectively. It is determined based on. The configuration and operation of the planetary gear device 2 will be specifically described below.

The housing section 10 has an input side housing 11 that covers the input side (inside b) of the planetary gear device 2, and an output side housing 12 that covers the output side (outside a) of the planetary gear device 2. . The input-side housing 11 accommodates components, such as a part of the input shaft 20, that are arranged on the input side near the motor 3 among the components of the planetary gear device 2. The input side housing 11 is provided with an input side opening 13 at the input side end in the axis x direction so that the input end 21 of the input shaft 20 can be exposed. Output side housing 12 is a component arranged on the output side on the opposite side to motor 3 in the axis x direction among the components of planetary gear device 2, such as output section 40 and second internal gear 220. It accommodates. The output side housing 12 is provided with an output side opening 14 at the output side end in the axis x direction so that the output end 41 of the output section 40 can be exposed.

The housing section 10 accommodates the components of the planetary gear device 2 by abutting and joining an input side housing 11 and an output side housing 12. In the housing portion 10, a clamping rib 121 provided on the radially outer side of the first internal gear 120 is sandwiched between the input side housing 11 and the output side housing 12 in the axis x direction. The housing part 10 functions as a fixing member for the first internal gear 120 by butting and joining the input side housing 11 and the output side housing 12 with the holding ribs 121 in between.

The input shaft 20 is arranged so as to coincide or substantially coincide with the axis x inside the input-side casing 11 of the casing section 10 . The input shaft 20 receives rotational force from the motor 3 by having an input end 21 rotatably connected to the rotation shaft (not shown) of the motor 3 . The input shaft 20 is, for example, a hollow shaft in which a hollow portion 22 is provided at the center of the shaft on the inside in the radial direction. Note that the input shaft 20 is not limited to a hollow shaft, and may be a solid shaft without a cavity. The input shaft 20 has a sun gear 110 formed on the outside in the radial direction.

FIG. 4 is an AA sectional view showing the sun gear 110, the planetary gear units 310, 320, 330, 340, the first internal gear 120, and the second internal gear 220 included in the planetary gear device 2.

As shown in FIG. 4, the planetary gear device 2 is a 3K type compound planetary gear mechanism that is composed of a sun gear 110, planetary gear units 310, 320, 330, 340 having multiple stages of planetary gears, and multiple stages of internal gears. The multiple stages of planetary gears are, for example, first planetary gears 130, 140, 150, 160 and second planetary gears 230, 240, 250, 260. The multiple stages of internal gears are, for example, first internal gear 120 and second internal gear 220. Note that in this embodiment, the number of stages of the planetary gear mechanism is not limited to the example of the planetary gear device 2. Also, in this embodiment, the planetary gear mechanism may be a compound planetary gear mechanism such as a 2K-H type that does not have a sun gear.

As described above, the sun gear 110, the first internal gear 120, the first planetary gears 130, 140, 150, 160, the second internal gear 220, and the second planetary gears 230, 240, 250, 260 are all It is constituted by a helical gear having predetermined helix angles β1, β2 with respect to the axis x direction. In the following description, the first internal gear 120 and the first planetary gears 130, 140, 150, and 160, which are input-side gears in the planetary gear device 2, are used as the first-stage planetary gear mechanism of a plurality of stages of planetary gear mechanisms. (Hereinafter, it is also referred to as "first planetary gear mechanism 100."). In the following description, the second internal gear 220 and the second planetary gears 230, 240, 250, and 260 will be referred to as the second stage planetary gear mechanism (hereinafter referred to as "second planetary gear mechanism 200") of the multiple stage planetary gear mechanism. ).

The sun gear 110 is formed on the radially outer side of the input shaft 20. The sun gear 110 meshes with first planetary gears 130, 140, 150, 160 forming planetary gear units 310, 320, 330, 340. Therefore, in addition to the helix angle β1, the sun gear 110 has the same basic gear specifications such as module and pressure angle with the first internal gear 120 and the first planetary gears 130, 140, 150, and 160. It is a helical gear.

FIG. 5 is a plan view showing the first planetary gears 130, 140, 150, 160 and the first internal gear 120 included in the planetary gear device 2.

As shown in FIGS. 2 to 5, the first internal gear 120 is provided outside the input shaft 20 in the radial direction. The first internal gear 120 has a first internal gear main body 122 provided on the radially inner side facing the sun gear 110 and the first planetary gears 130, 140, 150, 160, , 160. For this reason, the first internal gear 120 has the sun gear 110 and the first planetary gear 130 in the first internal gear main body 122, in addition to the helix angle β1, the basic specifications of the gear such as the module and the pressure angle. , 140, 150, and 160 are configured with helical gears. The first internal gear 120 is fixed to the housing section 10 by being held by the housing section 10 by the clamping ribs 121 provided on the outside in the radial direction, as described above.

FIG. 6 is a plan view showing the second planetary gears 230, 240, 250, 260 and the second internal gear 220 included in the planetary gear device 2.

As shown in FIGS. 2 to 4 and 6, the second internal gear 220 is provided on the outside in the radial direction of the input shaft 20 and on the output side with respect to the first internal gear 120 in the axis x direction. ing. The second internal gear 220 faces the second planetary gears 230, 240, 250, 260 and meshes with the second planetary gears 230, 240, 250, 260. Therefore, the second internal gear 220 has, in addition to the helix angle β2, the basic specifications of the gear such as the module and the pressure angle on the radially inner side of the second planetary gears 230, 240, 250, and 260. A second internal gear main body 221, which is a common helical gear, is configured. In the second internal gear 220, a second internal gear shaft portion 222 is configured on the output side of a second internal gear main body 221. The second internal gear 220 is supported by a bearing 50 attached to the output side housing 12. The second internal gear 220 is supported by the bearing 50 and is configured to be rotatable according to the rotational force transmitted from the second planetary gears 230, 240, 250, and 260. The second internal gear 220 has an annular hole 223 centered on the axis x to form a through hole communicating in the direction of the axis x with the input shaft 20, which is a hollow shaft, at the position of the axis x. It is provided.

FIG. 7 is a side view showing the sun gear 110, the planetary gear units 310, 320, 330, 340, and the carriers 170, 270 included in the planetary gear device 2. Moreover, FIG. 8 is a side view for showing the planetary gear units 310, 320, 330, and 340 with which the planetary gear apparatus 2 is provided.

7 and 8, the multiple planetary gear units 310, 320, 330, 340 are arranged radially outside the sun gear 110 and radially inside the first internal gear 120 with an axis parallel to the axis x. The multiple planetary gear units 310, 320, 330, 340 are each configured with the first planetary gears 130, 140, 150, 160 on the input side in the axis x direction. The first planetary gears 130, 140, 150, 160 mesh with both the sun gear 110 and the first internal gear 120. For this reason, the first planetary gears 130, 140, 150, 160 are configured as helical gears that have the same specifications as the sun gear 110 and the first internal gear 120, such as the helix angle β1, module, and pressure angle, which are basic specifications of the gears. In addition, the planetary gear units 310, 320, 330, 340 are not particularly limited in terms of the difference in angle (phase difference) in the circumferential direction between the tooth positions of the first planetary gears 130, 140, 150, 160 and the tooth positions of the second planetary gears 230, 240, 250, 260. In addition, in the planetary gear units 310, 320, 330, 340, none of the units may have a designed phase difference between the first planetary gears 130, 140, 150, 160 and the second planetary gears 230, 240, 250, 260.

Further, the planetary gear units 310, 320, 330, and 340 each include second planetary gears 230, 240, 250, and 260 on the output side in the axis x direction. The second planetary gears 230, 240, 250, and 260 mesh with the second internal gear 220. Therefore, the second planetary gears 230, 240, 250, and 260 have in common with the second internal gear 220 the basic specifications of gears such as the helix angle β2, module, and pressure angle. Consists of helical gears.

As described above, in the planetary gear units 310, 320, 330, and 340, the helix angle β1 of the first planetary gears 130, 140, 150, and 160 is different from the helix angle β2 of the second planetary gears 230, 240, 250, and 260.

In the planetary gear units 310, 320, 330, 340, a bearing is provided between the planetary gear shaft portion 311, 321, 331, 341 and each planetary gear, and the first planetary gear 130, 140, 150, 160 , and the second planetary gears 230, 240, 250, and 260 rotate integrally with respect to the planetary gear shaft portions 311, 321, 331, and 341, respectively. That is, in the planetary gear units 310, 320, 330, 340, the first planetary gears 130, 140, 150, 160 and the second planetary gears 230, 240, 250, 260 work together to rotate. do.

The planetary gear units 310, 320, 330, and 340 are arranged at equal intervals in the circumferential direction, each at a predetermined angle θ. The angle θ is determined according to the number of planetary gear units 310, 320, 330, and 340. The planetary gear units 310, 320, 330, and 340 are rotatably supported by planetary gear shaft portions 311, 321, 331, and 341 fixed to the carrier 170, and rotate and revolve around the axis x by the rotational force transmitted from the sun gear 110.

Here, among the planetary gear units 310, 320, 330, and 340, the planetary gear unit 320 moves between the output end 321a of the planetary gear shaft 321 and the output side end 240a of the second planetary gear 240. A spacer section 322 functioning as a regulating section is provided. The spacer portion 322 eliminates the gap (play) that occurs between the output side end 170a of the carrier 170 and the end 240a of the second planetary gear 240 when the planetary gear unit 320 is supported by the carrier 170. are doing.

In the planetary gear unit 320, a spacer portion 323 functioning as a movement restriction portion is provided between the input end portion 321b of the planetary gear shaft portion 321 and the input side end portion 140b of the first planetary gear 140. The spacer portion 323 eliminates the gap (play) that occurs between the input side end 170b of the carrier 170 and the end 140b of the first planetary gear 140 when the planetary gear unit 320 is supported by the carrier 170. are doing.

In the planetary gear device 2, the planetary gear unit provided with the spacer portion is not limited to the planetary gear unit 310 described above, and may be provided in other planetary gear units 320, 330, and 340. Further, since the number of planetary gear units provided with a spacer portion may be at least one planetary gear unit, a plurality of planetary gear units 310, 320, 330, 340 may be provided with a spacer portion. .

Furthermore, in the planetary gear units 310, 320, 330, 340, the first planetary gears 130, 140, 150, 160, the second planetary gears 230, 240, 250, 260, and the planetary gear shafts 311, 321, 331, 341 may be made of separate members and assembled together, or may be integrally formed by cutting or the like. Further, in the planetary gear device 2, the number of planetary gear units 310, 320, 330, 340 mounted is not limited to the above-mentioned four, but can be selected as appropriate.

The output unit 40 is arranged so as to coincide or approximately coincide with the axis x inside the output side housing 12 of the housing unit 10. The output end 41 of the output unit 40 is connected to the output side end of the second internal gear shaft portion 222 of the second internal gear 220. The output end 42 of the output unit 40 is connected to be rotatable around the axis x in cooperation with the output side rotating shaft (not shown). Therefore, the rotational force from the motor 3 is output from the output end 42 of the output unit 40. The output unit 40 is, for example, a hollow shaft with a cavity portion 43 provided at the center of the shaft on the radial inner side. Note that the output unit 40 is not limited to a hollow shaft, and may be a solid shaft without a cavity portion. It is also possible to directly use the second internal gear shaft portion 222 of the second internal gear 220 as the output side rotating shaft without providing the output unit 40.

[Operation of planetary gear system]
Next, the operation of the planetary gear device 2 having the configuration described above will be explained.

In the planetary gear device 2, as shown in FIGS. 1 and 2, the input shaft 20 is rotated by the rotational force from the motor 3 because the input end 21 is connected to the rotation shaft (not shown) of the motor 3. do. In the plurality of planetary gear units 310, 320, 330, 340, the sun gear 110 formed on the radially outer side of the input shaft 20 and the plurality of first planetary gears 130, 140, 150, 160 mesh with each other. Rotation of the shaft 20 causes rotation between the sun gear 110 and the first internal gear 120.

Since the second internal gear 220 meshes with the second planetary gears 230, 240, 250, 260 of the planetary gear units 310, 320, 330, 340, the rotation of the planetary gear units 310, 320, 330, 340 causes Rotate. Here, the second internal gear 220 is a combination of the first planetary gears 130, 140, 150, 160 and the second planetary gears 230, 240, 250, 260 that are configured in the planetary gear units 310, 320, 330, 340. It rotates at a reduced speed due to the difference in the number of teeth. Since the output section 40 is configured to be rotatable together with the second internal gear 220, it rotates when the second internal gear 220 rotates.

The planetary gear device 2 has a helix angle β1 of the sun gear 110, the first internal gear 120, and the first planetary gears 130, 140, 150, and 160 that constitute the first planetary gear mechanism 100, and the second planetary gear. This is different from the helix angle β2 of the second internal gear 220 and the second planetary gears 230, 240, 250, and 260 that constitute the mechanism 200. In this way, by setting the torsion angle β1 of the first planetary gears 130, 140, 150, 160 and the torsion angle β2 of the second planetary gears 230, 240, 250, 260 to different angles, if there is a phase error, In addition, it is possible to reduce the amount of movement in the z-axis direction in order to obtain an appropriate meshing position. Furthermore, the planetary gear device 2 functions as a speed reducer that reduces the speed when the rotational force from the input shaft 20 is output from the output section 40 . Therefore, the number of teeth of the first planetary gears 130, 140, 150, 160 is greater than the number of teeth of the second planetary gears 230, 240, 250, 260.

FIG. 9 is a schematic diagram showing component forces applied to the first planetary gears 130, 140, 150, 160 and the second planetary gears 230, 240, 250, 260 included in the planetary gear device 2. Moreover, FIG. 10 shows the rotational directions of the sun gear 110, the second internal gear 220, and the second planetary gears 230, 240, 250, 260 provided in the planetary gear device 2, and the rotational directions of the second planetary gears 230, 240, 250, 260. FIG. 2 is a schematic diagram showing the component force applied to the

As shown in FIG. 9, the directions in which the helical gears constituting the first internal gear 120 and the first planetary gears 130, 140, 150, and 160 are inclined with respect to the axis x direction, and the second internal gear 220 and the second planetary gears The helical gears constituting the gears 230, 240, 250, and 260 have the same inclination direction (twisting direction) with respect to the axis x direction. Therefore, as shown in FIGS. 9 and 10, the planetary gear device 2 is configured such that the direction of the tangential component force (tangential load) Y1 applied to the first planetary gears 130, 140, 150, 160 and the second planetary gear 230 are , 240, 250, and 260 are in the opposite direction to the direction of the tangential load Y2. Further, in the planetary gear device 2, the rotational direction RP2 of the second planetary gears 230, 240, 250, 260 is opposite to the rotational direction RS1 of the sun gear 110 and the rotational direction R2 of the second internal gear 220. .

FIG. 11 shows component forces applied to the planetary gear units 310, 320, 330, 340 included in the planetary gear device 2, and the forces applied to the planetary gear units 310, 320, 330, 340 and the planetary gear shaft portions 311, 321, 331, 341. FIG. 3 is a schematic diagram showing the friction surface Fr of

As shown in FIGS. 9 and 11, the planetary gear device 2 has a force applied to the first planetary gears 130, 140, 150, and 160 in the direction of the axis x, that is, a component force in the thrust direction (thrust load) T1. The direction of the thrust load T2 applied to the second planetary gears 230, 240, 250, and 260 is opposite to the direction. Therefore, in the planetary gear units 310, 320, 330, 340 included in the planetary gear device 2, the contact surface Fr1 between the first planetary gear 130, 140, 150, 160 and the planetary gear shaft portion 311, 321, 331, 341 is , receives frictional force X1 due to thrust load T1. Furthermore, in the planetary gear units 310, 320, 330, 340, the contact surface Fr2 between the second planetary gear 230, 240, 250, 260 and the planetary gear shaft portion 311, 321, 331, 341 is affected by the friction force due to the thrust load T2. receive.

In the planetary gear device 2, the helix angle β1 of the first planetary gears 130, 140, 150, 160 of the planetary gear units 310, 320, 330, 340 and the helix angle β2 of the second planetary gears 230, 240, 250, 260. are different. Here, the torsion angles β1 and β2 are the thrust load T1 applied to the first internal gear 120 and the first planetary gears 130, 140, 150, 160 and the second internal gear 220 and the second planetary gears 230, 240, 250, 260. Based on the thrust load T2 applied to the thrust load T2, the thrust load T1 and the thrust load T2 are determined to be equal.

FIG. 12 is a schematic diagram showing component forces applied to the planetary gears included in the planetary gear device 2. As shown in FIG.

As described above, the planetary gears included in the planetary gear device 2 all use helical gears. As shown in FIG. 12, the helical gear has a helix angle β, so a thrust load T is generated.

Thrust load: T, radial load: S, tangential load: F, circumferential load: f, and load in the direction perpendicular to the tooth surface: V.
T=F・tanβ…(1)
S=F・tanαn/cosβ…(2)
f=F/cosβ…(3)
V=f/cosαn=F/(cosβ・cosαn)…(4)
There is a relationship between Here, it is assumed that the gear pressure angle is αn.

In addition, since helical gears normally transmit force without slipping between the gears, frictional forces X and TT1 can be ignored. However, when a difference in thrust load T occurs in a two-stage planetary gear, the following frictional forces X and TT1 must be taken into consideration.
X = TT1 · cosβ ... (5)
TT1=μV...(6)
Where μ is the friction coefficient

FIG. 13 is a schematic diagram showing the forces applied to the planetary gear units 310, 320, 330, and 340 included in the planetary gear device 2.

In the planetary gear device 2, the planetary gear units 310, 320, 330, 340 are two-stage helical gears each including a first planetary gear 130, 140, 150, 160 and a second planetary gear 230, 240, 250, 260. This is a planetary gear. In such planetary gear units 310, 320, 330, 340, the condition for not slipping in the axis x direction due to thrust loads T1 and T2 is that T1>T2 when considering frictional forces X1 and determined.

T1-T2≦X1+X2…(6)

Here, T1, T2, X1, and X2 are expressed by the following formulas (1) to (5):
T1 = F1 tan β1 ... (7)
T2 = F2 tan β2 ... (8)
X1=μ·F1/cosαn1 (9)
X2=μ·F2/cosαn2 (10)
It is.
Substituting these formulas (7) to (10) into formula (6), we get

F1·tanβ1−F2·tanβ2≦μ·F1/ _cosαn1 +μ·F2/cosαn2 (11)
It becomes.

Here, β1 is determined first, and the limit β2 that does not move in the thrust direction is determined. Specifically, it is obtained by transforming equation (11) into equation (12) below.

tanβ2≦F1/F2 (tanβ1−μ/cosαn1)−μ/cosαn2…( 12 )

By being configured to use helical gears with helical angles β1 and β2 that satisfy the relationship of equation (12) above, the planetary gear device 2 can handle thrust load T1 and thrust load T2 in the operating state. They can be made equal, and the directions of the thrust load T1 and the thrust load T2 can be made opposite in the axis x direction. In other words, the planetary gear device 2 can minimize the difference in the forces in the x-axis direction between the frictional forces X1 and X2, the thrust load T1, and the thrust load T2. In other words, according to the planetary gear system 2, the difference between the helix angle β1 of the helical gear that constitutes the first planetary gear mechanism 100 and the helix angle β2 of the helical gear that constitutes the second planetary gear mechanism 200 is expressed by the formula ( If the angle is less than or equal to the angle that satisfies the condition 12), movement of the planetary gear units 310, 320, 330, and 340 in the axis x direction can be suppressed. In addition, in the planetary gear device 2, if the helix angles β1 and β2 are selected to satisfy the relationship of equation (12), the angles can be set appropriately, so the selection range of the helix angles β1 and β2 is expanded, and the above-mentioned It is possible to easily design a planetary gear device that exhibits such an effect.

Therefore, the direction of inclination of the helical gears constituting the first internal gear 120 and the first planetary gears 130, 140, 150, 160 with respect to the axis x direction, and the direction in which the second internal gear 220 and the second planetary gears 230, 240, 250 . According to the planetary gear system 2 in which the helix angles β2 of the gears are different so as to satisfy the relationship of equation (12) above, by suppressing the movement of the planetary gear units 310, 320, 330, and 340 in the axis x direction, Since it is possible to prevent friction on the friction surfaces Fr1 and Fr2 and a reduction in transmission efficiency, it is possible to achieve both efficiency and longevity.

In addition, those skilled in the art can modify the present invention as appropriate based on conventionally known knowledge. As long as such modifications still have the structure of the present invention, they are, of course, included within the scope of the present invention.

DESCRIPTION OF SYMBOLS 1... Drive device, 2... Planetary gear device, 3... Motor, 10... Housing part, 11... Input side housing, 12... Output side housing, 13... Input side opening, 14... Output side opening, 20 ...Input shaft, 21...Input end, 22...Cavity, 30...Bearing, 31...Planetary gear shaft, 40...Output part, 41...Output end, 42...Output end, 43...Cavity, 100... First planetary gear mechanism, 110... Sun gear, 120... First internal gear, 121... Clamping rib, 122... First internal gear body, 130, 140, 150, 160... First planetary gear, 140b... End, 170 ...Carrier, 170a...End, 200...Second planetary gear mechanism, 220...Second internal gear, 221...Second internal gear main body, 222...Second internal gear shaft, 223...Hole, 230, 240, 250 , 260... Second planetary gear, 240a... End, 270... Carrier, 270b... End, 310, 320, 330, 340... Planetary gear unit, 311, 321, 331, 341... Planetary gear shaft, 321a... Output End part, 321b...Input end part, 322, 323... Spacer part

Claims (2)

a first internal gear;
a second internal gear provided apart from the first internal gear in the axial direction;
a plurality of first planetary gears that mesh with the first internal gear; and a plurality of second planetary gears that mesh with the second internal gear; one set of the first planetary gear and the second planetary gear are integrally formed; a plurality of planetary gear units connected in the axial direction so as to rotate together;
A planetary gear device comprising:
The first internal gear, the first planetary gear, the second internal gear, and the second planetary gear are configured by helical gears having a predetermined helix angle with respect to the axial direction,
A direction in which the helical gears constituting the first internal gear and the first planetary gear are tilted with respect to the axial direction, and a direction in which the helical gears constituting the second internal gear and the second planetary gear are tilted with respect to the axial direction. are the same,
The helix angles of the helical gears constituting the first internal gear and the first planetary gear and the helical gears constituting the second internal gear and the second planetary gear are different,
The helix angle of the helical gears constituting the first internal gear and the first planetary gear, and the helix angle of the helical gears constituting the second internal gear and the second planetary gear are the same as those of the first internal gear. and determined based on forces acting in the axial direction of each of the first planetary gear, the second internal gear, and the second planetary gear ,
The torsion angle of the first planetary gear with respect to the axial direction is β1, the torsion angle of the second planetary gear with respect to the axial direction is β2, the gear pressure angle of the first planetary gear is αn1, and the gear pressure angle of the second planetary gear is When αn2 and the friction coefficient are μ, the limit β2 that does not move in the thrust direction is calculated from the above-determined torsion angle β1 using the following formula.
tanβ2≦F1/F2 (tanβ1−μ/cosαn1)−μ/cosαn2
seek from ,
Planetary gear system. The second internal gear and the second planetary gear have a different number of teeth from the first internal gear and the first planetary gear,
The helix angle of the helical gears constituting the first internal gear and the first planetary gear, and the helix angle of the helical gears constituting the second internal gear and the second planetary gear are the same as those of the first internal gear. and the forces acting in the axial direction of the first planetary gear, the second internal gear, and the second planetary gear are set to be equal.
The planetary gear system according to claim 1.

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