JP2021085509A - Planetary gear train - Google Patents

Abstract

To achieve both of efficiency and service life.SOLUTION: In a planetary gear train 2, a direction in which helical gears constituting a first internal gear 120 and a first planetary gear 130,140,150,160 are inclined in the axis x direction is the same as a direction in which helical gears constituting a second internal gear 220 and a second planetary gear 230,240,250,260 are inclined in the axis x direction. A torsion angle of the helical gears constituting the first internal gear 120 and the first planetary gear 130,140,150,160 and a torsion angle of the helical gears constituting the second internal gear 220 and the second planetary gear 230,240,250,260 are defined based on the power acting in the axis x direction for each of the first internal gear 120 and the first planetary gear 130,140,150,160, and the second internal gear 220 and the second planetary gear 230,240,250,260.SELECTED DRAWING: Figure 2

Description

The present invention relates to a planetary gear device.

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

Japanese Unexamined Patent Publication No. 2002-221259

By the way, in planetary gears, helical gears are used in order to reduce noise generated from the gears.

However, in the helical gear, when transmitting power, a component force is generated in the axial direction (thrust direction). Therefore, in the planetary gear device using the helical gear, friction is generated on the end face of the planetary gear and the end face of the internal gear which is the receiving surface thereof due to the component force in the thrust direction generated in the planetary gear. In a conventional planetary gear device using helical gears, this friction may reduce efficiency, or the gears may wear and lead to a decrease in durability, so that the component force in the thrust direction can be reduced. I was asked.

The present invention is an example of the above-mentioned problems, and an object of the present invention is to provide a planetary gear device capable of achieving both efficiency and life.

In order to achieve the above object, the planetary gear device according to the present invention includes a first internal gear, a second internal gear provided apart from the first internal gear in the axial direction, and the first internal gear. It has a plurality of first planetary gears that mesh with the second internal gear and a plurality of second planetary gears that mesh with the second internal gear, so that a set of the first planetary gear and the second planetary gear rotates integrally. The first internal gear, the first planetary gear, the second internal gear, and the second planetary gear are provided with a plurality of planetary gear units connected in the axial direction to the axial direction. It is composed of helical gears having a predetermined torsion angle, and the direction in which the first internal gear and the helical gear constituting the first planetary gear are inclined with respect to the axial direction, and the second internal gear and the second planet. The direction of inclination of the helical gears constituting the gears with respect to the axial direction is the same, and the torsion angles of the helical gears constituting the first internal gear and the first planetary gear, the second internal gear, and the second internal gear are the same. The torsion angles of the helical gears constituting the planetary gears are different, and the torsion angles of the first internal gear and the helical gears constituting the first planetary gear, the second internal gear, and the second planet are different. The torsional angle of the helical gear constituting the gear is determined based on the forces acting in the axial directions of the first internal gear, the first planetary gear, the second internal gear, and the second planetary gear. ..

In the planetary gear device according to one aspect of the present invention, the second internal gear and the second planetary gear have different numbers of teeth from the first internal gear and the first planetary gear, and the first internal gear and the first internal gear have different numbers of teeth. The torsion angle of the helical gear constituting the first planetary gear and the torsion angle of the second internal gear and the helical gear constituting the second planetary gear are the first internal gear and the first planetary gear. The forces acting in the axial directions of the second internal gear and the second planetary gear are set to be equal to each other.

According to the planetary gear device according to the present invention, both efficiency and life can be achieved at the same time.

It is a perspective view which shows typically the structure of the drive device which comprises the planetary gear device which concerns on embodiment of this invention. It is sectional drawing along the axis direction which shows the structure of the planetary gear device schematicly. FIG. 5 is a sectional view taken along the line AA of the planetary gear device shown in FIG. FIG. 5 is a cross-sectional view taken along the line AA for showing the sun gear, the planetary gear unit, the first internal gear, and the second internal gear included in the planetary gear device shown in FIG. It is a top view for showing the 1st planetary gear and the 1st internal gear provided in the planetary gear device shown in FIG. 1. It is a top view for showing the 2nd planetary gear and the 2nd internal gear provided in the planetary gear device shown in FIG. 1. It is a side view for demonstrating the sun gear, the planetary gear unit, and a carrier included in the planetary gear apparatus shown in FIG. It is a side view for demonstrating the planetary gear unit provided in the planetary gear device shown in FIG. It is a schematic diagram for showing the component force applied to the 1st planetary gear and the 2nd planetary gear provided in the planetary gear apparatus shown in FIG. It is a schematic diagram for showing the rotational direction of the sun gear, the 2nd internal gear, and the 2nd planetary gear, and the component force applied to the 2nd planetary gear, which the planetary gear apparatus shown in FIG. 1 has. It is a schematic diagram for showing the component force applied to the planetary gear unit provided in the planetary gear device shown in FIG. 1, and the friction surface between the planetary gear unit and the planetary gear shaft portion. It is a schematic diagram for showing the component force applied to the planetary gear provided in the planetary gear device shown in FIG. It is a schematic diagram for demonstrating the force applied to the planetary gear unit included in the planetary gear device shown in FIG.

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

FIG. 1 is a perspective view schematically showing a 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, the 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.

[Configuration of planetary gears]
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 taken along the axial direction schematically showing the configuration of the planetary gear device 2. Further, FIG. 3 is a cross-sectional view taken along the line AA of the planetary gear device 2.

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

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 x-axis direction. It has 220, a plurality of first planetary gears 130, 140, 150, 160 that mesh with the first internal gear 120, and a plurality of second planetary gears 230, 240, 250, 260 that mesh 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 x-axis direction so as to rotate integrally. It is a planetary gear device including 320, 330, 340. The first internal gear 120, the first planetary gear 130, 140, 150, 160, the second internal gear 220, and the second planetary gear 230, 240, 250, 260 have a predetermined twist 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 direction of inclination of the helical gear with respect to the axis x direction is the same. The torsion angles of the helical gears constituting 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 are configured. The twist angles of the helical gears are different. The torsion angle of the helical gears that make up the first internal gear 120 and the first planetary gears 130, 140, 150, 160 and the spirals that make up the second internal gear 220 and the second planetary gears 230, 240, 250, 260. The torsion angle of the helical gear is the force acting on the axis x direction of the first internal gear 120 and the first planetary gear 130, 140, 150, 160 and the second internal gear 220 and the second planetary gear 230, 240, 250, 260, respectively. It is determined based on. Hereinafter, the configuration and operation of the planetary gear device 2 will be specifically described.

The housing portion 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 of the planetary gear device 2, such as a part of the input shaft 20, which are arranged on the input side close to the motor 3. The input-side housing 11 is provided with an input-side opening 13 so that the input end 21 of the input shaft 20 can be exposed at the end on the input side in the axis x direction. The output-side housing 12 is a component of the planetary gear device 2, such as the output unit 40 and the second internal gear 220, that is arranged on the output side opposite to the motor 3 in the axis x direction. Is housed. The output side housing 12 is provided with an output side opening 14 so that the output end 41 of the output unit 40 can be exposed at the end on the output side in the x direction of the axis.

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

The input shaft 20 is arranged inside the input-side housing 11 of the housing portion 10 so as to coincide with or substantially coincide with the axis x. The input shaft 20 is rotatably connected to the input shaft 21 in cooperation with the rotation shaft (not shown) of the motor 3, so that the rotational force from the motor 3 is input. The input shaft 20 is, for example, a hollow shaft provided with a hollow portion 22 at the center of the shaft on the inner side in the radial direction. The input shaft 20 is not limited to the hollow shaft, and may be a solid shaft having no hollow portion. The input shaft 20 has a sun gear 110 formed on the outer side in the radial direction.

FIG. 4 is a cross-sectional view taken along the line AA for 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 composed of a sun gear 110, planetary gear units 310, 320, 330, 340 having a plurality of stages of planetary gears, and a plurality of stages of internal gears. It is a compound planetary gear mechanism. Specifically, the multi-stage planetary gears are, for example, the first planetary gears 130, 140, 150, 160 and the second planetary gears 230, 240, 250, 260. Specifically, the multi-stage internal gears are, for example, the first internal gear 120 and the second internal gear 220. In the present embodiment, the number of stages of the planetary gear mechanism is not limited to the example of the planetary gear device 2. Further, in the present embodiment, the planetary gear mechanism may be a compound planetary gear mechanism such as a 2KH type that does not have a sun gear.

As described above, the sun gear 110, the first internal gear 120, the first planetary gear 130, 140, 150, 160, the second internal gear 220, and the second planetary gear 230, 240, 250, 260 are all included. It is composed of helical gears having predetermined torsion angles β1 and 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, 160, which are the input side gears in the planetary gear device 2, are the first stage planetary gear mechanism among the plurality of stage planetary gear mechanisms. (Hereinafter, it is also referred to as "first planetary gear mechanism 100".). Further, in the following description, the second internal gear 220 and the second planetary gears 230, 240, 250, 260 are referred to as the second stage planetary gear mechanism among the plurality of stage planetary gear mechanisms (hereinafter, "second planetary gear mechanism 200". ".) Also called.

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

FIG. 5 is a plan view for 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 on the outer side in the radial direction of the input shaft 20. In the first internal gear 120, the first internal gear body 122 provided on the inner side in the radial direction faces the sun gear 110 and the first planetary gears 130, 140, 150, 160, and the first planetary gears 130, 140, 150. , 160 meshes. Therefore, in the first internal gear 120, the specifications of the first internal gear body 122, the torsion angle β1, the module, the pressure angle, and other basic specifications of the gear are the sun gear 110 and the first planetary gear 130. , 140, 150, 160 have common helical gears. The first internal gear 120 is fixed to the housing portion 10 by sandwiching the holding rib 121 provided on the outer side in the radial direction in the housing portion 10 as described above.

FIG. 6 is a plan view for 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 radial side of the input shaft 20 and on the output side in the axis x direction with respect to the first internal gear 120. 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, in the second internal gear 220, in addition to the torsion angle β2, the specifications such as the module and the pressure angle, which are the basic specifications of the gear, are the second planetary gears 230, 240, 250, 260. The second internal gear body 221 which is a common helical gear is configured. The second internal gear 220 has a second internal gear shaft portion 222 configured on the output side of the second internal gear main body 221. The second internal gear 220 is supported by a bearing 50 attached to the output side housing 12. Since the second internal gear 220 is supported by the bearing 50, the second internal gear 220 is configured to be rotatable according to the rotational force transmitted from the second planetary gears 230, 240, 250, 260. The second internal gear 220 has an annular hole portion 223 centered on the axis x in order to form a through hole communicating with the input shaft 20 which is a hollow shaft at the position of the axis x in the axis x direction. It is provided.

FIG. 7 is a side view for 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. Further, FIG. 8 is a side view for showing the planetary gear units 310, 320, 330, 340 included in the planetary gear device 2.

As shown in FIGS. 7 and 8, the plurality of planetary gear units 310, 320, 330, 340 are radially outside the sun gear 110 and radially outside the first internal gear 120 with an axis parallel to the axis x as the axis. It is located inside. The plurality of planetary gear units 310, 320, 330, 340 are configured with the first planetary gears 130, 140, 150, 160 on the input side in the axis x direction, respectively. The first planetary gears 130, 140, 150, 160 mesh with both the sun gear 110 and the first internal gear 120. Therefore, the first planetary gears 130, 140, 150, 160 have the same specifications as the sun gear 110 and the first internal gear 120, in addition to the torsion angle β1, which are the basic specifications of the gear such as the module and the pressure angle. A helical gear is constructed. The planetary gear units 310, 320, 330, 340 have the circumference of 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. The difference in angle (phase difference) in the direction is not particularly limited. Further, the planetary gear units 310, 320, 330, 340 have a design phase difference between the first planetary gears 130, 140, 150, 160 and the second planetary gears 230, 240, 250, 260. It is not necessary to have.

Further, in the planetary gear units 310, 320, 330, 340, second planetary gears 230, 240, 250, 260 are configured on the output side in the axis x direction, respectively. The second planetary gears 230, 240, 250, 260 mesh with the second internal gear 220. Therefore, the second planetary gears 230, 240, 250, 260 have the same specifications as the second internal gear 220, such as the torsion angle β2, the module, and the basic specifications of the gear such as the pressure angle. A helical gear is configured.

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

In the planetary gear units 310, 320, 330, 340, bearings are provided between the planetary gear shafts 311, 321, 331, 341 and each planetary gear, and the first planetary gears 130, 140, 150, 160. , And the second planetary gears 230, 240, 250, 260 rotate integrally with the planetary gear shafts 311, 321, 331, 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 cooperate with each other to rotate. To do.

The planetary gear units 310, 320, 330, and 340 are arranged at equal intervals with predetermined angles θ in the circumferential direction. The angle θ is determined according to the number of planetary gear units 310, 320, 330, 340. The planetary gear units 310, 320, 330, 340 are rotatably supported with respect to the planetary gear shafts 311, 321, 331, 341 fixed to the carrier 170, and are rotatably supported by the rotational force transmitted from the sun gear 110. It rotates and revolves around the axis x.

Here, among the planetary gear units 310, 320, 330, 340, the planetary gear unit 320 moves between the output end portion 321a of the planetary gear shaft portion 321 and the output side end portion 240a of the second planetary gear 240. A spacer portion 322 that functions as a regulating portion is provided. The spacer portion 322 eliminates the gap (play) generated 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. doing.

The planetary gear unit 320 is provided with a spacer portion 323 that functions as a movement restricting portion between the input end portion 321b of the planetary gear shaft portion 321 and the end portion 140b on the input side of the first planetary gear 140. The spacer portion 323 eliminates the gap (play) generated between the end 170b on the input side 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. 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, 340. Further, since the number of planetary gear units provided with spacer portions may be at least one planetary gear unit, spacer portions may be provided in a plurality of planetary gear units 310, 320, 330, 340. ..

Further, 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 and 331. The 341 may be assembled from separate members, or may be integrally molded by cutting or the like. Further, the number of planetary gear units 310, 320, 330, 340 mounted on the planetary gear device 2 is not limited to the above four, and can be appropriately selected.

The output unit 40 is arranged inside the output-side housing 12 of the housing unit 10 so as to coincide with or substantially coincide with the axis x. In the output unit 40, the output end portion 41 is connected to the output side end portion of the second internal gear shaft portion 222 of the second internal gear 220. In the output unit 40, the output end portion 42 is rotatably connected around the axis x in cooperation with a rotation shaft (not shown) on the output side. 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 provided with a hollow portion 43 at the center of the axially inner shaft. The output unit 40 is not limited to the hollow shaft, and may be a solid shaft having no hollow shaft. Further, it is also possible to directly use the second internal gear shaft portion 222 of the second internal gear 220 as the rotation shaft on the output side without providing the output unit 40.

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

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. To do. The plurality of planetary gear units 310, 320, 330, 340 are input because the sun gear 110 formed on the radial outer side of the input shaft 20 and the plurality of first planetary gears 130, 140, 150, 160 are meshed with each other. As the shaft 20 rotates, it rotates 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 planetary gear units 310, 320, 330, 340 rotate. 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, which are configured in the planetary gear units 310, 320, 330, 340. It slows down and rotates due to the difference in the number of teeth. Since the output unit 40 is configured to be rotatable together with the second internal gear 220, the output unit 40 rotates when the second internal gear 220 rotates.

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

FIG. 9 is a schematic diagram for showing the 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. Further, FIG. 10 shows the rotation directions of the sun gear 110, the second internal gear 220, and the second planetary gears 230, 240, 250, 260 and the second planetary gears 230, 240, 250, 260 included in the planetary gear device 2. It is a schematic diagram for showing the component force applied to.

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

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

As shown in FIGS. 9 and 11, the planetary gear device 2 has a force acting in the axis x direction applied to the first planetary gears 130, 140, 150, 160, that is, the direction of the component force (thrust load) T1 in the thrust direction. The direction of the thrust load T2 applied to the second planetary gears 230, 240, 250, 260 is opposite to that of the thrust load T2. 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 gears 130, 140, 150, 160 and the planetary gear shafts 311, 321, 331, 341 is formed. , Receives frictional force X1 due to thrust load T1. Further, in the planetary gear units 310, 320, 330, 340, the contact surface Fr2 between the second planetary gears 230, 240, 250, 260 and the planetary gear shafts 311, 321, 331, 341 is a frictional force due to the thrust load T2. Receive.

In the planetary gear device 2, the torsion angles β1 of the first planetary gears 130, 140, 150, 160 and the torsion angles β2 of the second planetary gears 230, 240, 250, 260 included in the planetary gear units 310,320,330,340. Is 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, the second internal gear 220, and the second planetary gears 230, 240, 250, 260. The thrust load T1 and the thrust load T2 are set to be equal to each other based on the thrust load T2 applied to the gear.

FIG. 12 is a schematic diagram for showing the component force applied to the planetary gear included in the planetary gear device 2.

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

Thrust load: T, radial load: S, tangential load: F, circumferential load: f, and load 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. Here, the gear pressure angle: αn.

Since helical gears normally transmit forces without slipping between gears, frictional forces X and TT1 can be ignored, but if there is a difference in thrust load T in a two-stage planetary gear, the following frictional forces X, Consider TT1.
X = TT1 · cosβ ... (5)
TT1 = μV ... (6)
Here, μ: friction coefficient

FIG. 13 is a schematic diagram for showing the forces applied to the planetary gear units 310, 320, 330, 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 gears composed of the first planetary gears 130, 140, 150, 160 and the second planetary gears 230, 240, 250, 260. For example, it is a planetary gear. In such planetary gear units 310, 320, 330, 340, the condition that the thrust loads T1 and T2 do not slip in the axis x direction is T1> T2 in consideration of the frictional forces X1 and X2, according to the following equation (6). It is decided.

T1-T2 ≤ X1 + X2 ... (6)

Here, T1, T2, X1, and X2 are derived from equations (1) to (5).
T1 = F1 · tanβ1 ... (7)
T2 = F2 ・ tanβ2 ... (8)
X1 = μ · F1 / cosαn1 ... (9)
X2 = μ · F2 / cosαn2 ... (10)
Is.
Substituting these equations (7) to (10) into equation (6),

F1, tanβ1-F2, tanβ2 ≤ μ, F1 / cosαn ₁ + μ, F2 / cosαn2 ... (11)
Will be.

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

tanβ2 ≦ F1 / F2 (tanβ1-μ / cosαn1) −μ / cosαn2… (8)

Since the helical gears having torsion angles β1 and β2 satisfying the relationship of the above equation (12) are used, the planetary gear device 2 makes the thrust load T1 and the thrust load T2 in use. It can be made equal, and the directions of the thrust load T1 and the thrust load T2 can be opposite in the axis x direction. That is, the planetary gear device 2 can minimize the difference between the frictional forces X1, X2, the thrust load T1, and the thrust load T2 in the x-axis direction. That is, according to the planetary gear device 2, the difference between the torsion angle β1 of the helical gears constituting the first planetary gear mechanism 100 and the torsion angle β2 of the helical gears constituting the second planetary gear mechanism 200 is the equation ( If the angle is equal to or less than the angle satisfying the condition of 12), it is possible to prevent the planetary gear units 310, 320, 330, 340 from moving in the axis x direction. Further, since the planetary gear device 2 can appropriately set the helix angles β1 and β2 by selecting the helix angles β1 and β2 so as to satisfy the relationship of the equation (12), the selection range of the helix angles β1 and β2 is widened, and the above-mentioned It is possible to easily design a planetary gear device that exerts such an action.

Therefore, 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 have the same inclination direction with respect to the axis x direction of the helical gears, and the helical gears constituting the first planetary gear mechanism 100 have a torsion angle β1 and the second planetary gear mechanism 200 has a spiral gear. According to the planetary gear device 2 in which the twist angle β2 of the false gear is different so as to satisfy the above equation (12), the movement of the planetary gear units 310, 320, 330, 340 in the axis x direction is suppressed. Since it is possible to prevent friction on the friction surfaces Fr1 and Fr2 and a decrease in transmission efficiency, it is possible to achieve both efficiency and life.

In addition, those skilled in the art can appropriately modify the present invention according to conventionally known knowledge. As long as the modification still has the constitution of the present invention, it is, of course, included in the category of the present invention.

1 ... Drive device, 2 ... Planetary gear device, 3 ... Motor, 10 ... Housing, 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, 41 ... Output end, 42 ... Output end, 43 ... Cavity, 100 ... 1st planetary gear mechanism, 110 ... sun gear, 120 ... 1st internal gear, 121 ... holding rib, 122 ... 1st internal gear body, 130, 140, 150, 160 ... 1st planetary gear, 140b ... end, 170 ... carrier, 170a ... end, 200 ... second planetary gear mechanism, 220 ... second internal gear, 221 ... second internal gear body 222 ... second internal gear shaft, 223 ... hole, 230, 240, 250 , 260 ... 2nd 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, 321b ... Input end, 322, 323 ... Spacer

Claims (2)

With the first internal gear
A second internal gear provided apart from the first internal gear in the axial direction,
It has 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, and a set of the first planetary gear and the second planetary gear is integrally formed. Multiple planetary gear units connected in the axial direction so as to rotate
It is a planetary gear device equipped with
The first internal gear, the first planetary gear, the second internal gear, and the second planetary gear are composed of helical gears having a predetermined torsional angle with respect to the axial direction.
The direction of inclination of the helical gears constituting the first internal gear and the first planetary gear with respect to the axial direction, and the direction of inclination of the helical gears constituting the second internal gear and the second planetary gear with respect to the axial direction. Are the same,
The torsion angles of the helical gears constituting the first internal gear and the first planetary gear and the torsion angles of the helical gears constituting the second internal gear and the second planetary gear are different.
The torsion angle of the helical gear constituting the first internal gear and the first planetary gear and the torsion angle of the helical gear constituting the second internal gear and the second planetary gear are determined by the first internal gear. And, it is determined based on the forces acting in the axial directions of the first planetary gear, the second internal gear, and the second planetary gear.
Planetary gear device. The second internal gear and the second planetary gear have different numbers of teeth from the first internal gear and the first planetary gear.
The torsion angle of the helical gear constituting the first internal gear and the first planetary gear and the torsion angle of the helical gear constituting the second internal gear and the second planetary gear are determined by the first internal gear. And the forces acting in the axial directions of the first planetary gear, the second internal gear, and the second planetary gear are defined to be equal.
The planetary gear device according to claim 1.

Images