CN115507155A - Two-stage planetary gear mechanism and wheel drive device - Google Patents

Abstract

The invention provides a two-stage planetary gear mechanism and a wheel driving device. The 1 st planetary gear device has a 1 st sun gear, a 1 st planetary gear, a 1 st carrier pin, a 1 st carrier, and a 1 st internal gear. The 1 st planetary gear has 1 st planetary external teeth meshing with the 1 st sun external teeth of the 1 st sun gear from the radially outer side. The 1 st carrier rotatably supports the 1 st planetary gear around the central axis line. The 1 st internal gear has 1 st internal teeth on an inner peripheral surface thereof, which mesh with the 1 st planetary external teeth from a radially outer side. The 2 nd planetary gear device has a 2 nd sun gear, a 2 nd planetary gear, a 2 nd carrier pin, a 2 nd carrier, and a 2 nd internal gear. The 2 nd planetary gear has a 2 nd planetary external tooth meshing with the 2 nd sun external tooth of the 2 nd sun gear from the radially outer side. The 2 nd internal gear has 2 nd internal teeth on an inner peripheral surface thereof, which mesh with the 2 nd planetary external teeth from a radially outer side. The 1 st internal gear is formed on the inner peripheral surface of the 2 nd carrier.

Description

Two-stage planetary gear mechanism and wheel drive device

Technical Field

The present invention relates to a two-stage planetary gear mechanism and a wheel drive device having the same.

Background

Conventionally, there has been known an unmanned wheel drive device for transporting a transported object such as a material in various places such as a production line of a factory, a hospital, and an office. The wheel drive device moves by rotating a tire while increasing output torque while decelerating a rotational motion obtained from a motor using a decelerator. In recent years, in accordance with the diversification of the demand in accordance with the use environment, there has been a demand for a reduction gear capable of obtaining a high reduction gear ratio and suppressing noise and vibration during rotation of the reduction gear. Accordingly, an apparatus for suppressing noise while achieving a high reduction ratio by performing two-stage deceleration is disclosed in japanese laid-open patent publication No. h 11-505309.

The two-stage planetary gear device of japanese laid-open patent publication No. 11-505309 has the following structure as the speed reduction mechanism of the 1 st stage: the 1 st planetary gear (13) engages with the inner peripheral surface of the 1 st ring gear (9) while meshing with the outer peripheral surface of the 1 st pinion (12), whereby the 1 st planetary gear (13) and the 1 st carrier (4) holding the 1 st planetary gear (13) rotate. In addition, as a 2 nd-stage reduction mechanism, a structure is provided in which the 2 nd planetary gear (7) meshes with the 2 nd ring gear (8) while meshing with the outer peripheral surface of the 2 nd pinion (14) that is a part of the 1 st carrier (4), whereby the 2 nd planetary gear (7) and the 2 nd carrier (3) that holds the 2 nd planetary gear (7) rotate. The 1 st ring gear (9) is fixed to the 2 nd carrier (3) via screws (10).

In recent years, due to the intense competition in the market, it is required to suppress the manufacturing cost in addition to the technology for realizing a higher reduction gear ratio, lower noise, and low vibration. Therefore, improvement of workability in assembling the two-stage planetary gear mechanism is a problem.

Disclosure of Invention

The invention aims to provide a technology which can improve the workability during assembly and restrain the manufacturing cost by changing the structure of components forming a two-stage type planetary gear mechanism.

An exemplary 1 st invention of the present application is a two-stage planetary gear mechanism including: a 1 st planetary gear device that converts an input rotation speed to an intermediate rotation speed lower than the input rotation speed; and a 2 nd planetary gear device that converts the intermediate rotation speed to an output rotation speed lower than the intermediate rotation speed, the 1 st planetary gear device having: a 1 st sun gear that rotates around a central axis at the input rotation speed; a 1 st planetary gear having a 1 st planetary external tooth meshing with a 1 st sun external tooth formed on an outer peripheral surface of the 1 st sun gear from a radially outer side; a 1 st carrier pin that supports the 1 st planetary gear so as to be rotatable about a 1 st rotation axis; a 1 st carrier to which the 1 st carrier pin is fixed, the 1 st carrier pin and the 1 st planetary gear being supported so as to be capable of revolving in a circumferential direction around the central axis, and rotating around the central axis at the intermediate rotational speed with the 1 st carrier pin and the 1 st planetary gear revolving together; and a 1 st internal gear disposed coaxially with the center axis and having 1 st internal teeth on an inner peripheral surface thereof to be engaged with the 1 st planetary external teeth of the 1 st planetary gear from a radially outer side, the 2 nd planetary gear device including: a 2 nd sun gear connected to the other axial side of the 1 st carrier and rotating together with the 1 st carrier around the central axis at the intermediate rotational speed; a 2 nd planetary gear having a 2 nd planetary external tooth meshing with a 2 nd sun external tooth formed on an outer peripheral surface of the 2 nd sun gear from a radially outer side; a 2 nd carrier pin that supports the 2 nd planetary gear so as to be rotatable about a 2 nd rotation axis; a 2 nd wheel carrier to which the 2 nd wheel carrier pin is fixed; and a 2 nd internal gear arranged coaxially with the center axis and having 2 nd internal teeth on an inner peripheral surface thereof, which mesh with the 2 nd planetary external teeth of the 2 nd planetary gear from a radially outer side, wherein one of the 2 nd carrier and the 2 nd internal gear is supported via a bearing by the other of the 2 nd carrier and the 2 nd internal gear so as to be relatively rotatable around the center axis and rotates around the center axis at the output rotation speed, and wherein the 1 st internal gear is formed on an inner peripheral surface of the 2 nd carrier.

An exemplary 2 nd invention of the present application is a wheel drive apparatus, characterized in that the wheel drive apparatus has: the two-stage planetary gear mechanism of claim 1; and the drive motor, this wheel drive device reduces the speed of the rotation of the said drive motor and transmits to the wheel, fix the said wheel on the said 2 nd internal gear.

According to an exemplary 1 st aspect of the present application, a 1 st internally toothed gear that meshes with a 1 st planetary gear of a 1 st planetary gear device from a radial outer side is formed on an inner peripheral surface of a 2 nd carrier that holds a 2 nd planetary gear of a 2 nd planetary gear device. This eliminates the need for fixing the 1 st internal gear and the 2 nd carrier, and therefore improves workability in assembly and reduces manufacturing costs. Further, the accuracy of the coaxiality of the 1 st internal gear and the entire 2 nd carrier including the 1 st internal gear can be improved, and noise and vibration can be further suppressed. In addition, it is possible to suppress the occurrence of a meshing failure of the 1 st planetary gear and the 1 st internal gear due to a step difference between the 1 st internal gear and the 2 nd carrier that may occur if the 1 st internal gear and the 2 nd carrier are separately formed and axially connected, respectively. Further, as compared with a case where the 1 st internal gear and the 2 nd carrier are separately formed and connected in the axial direction, the entire two-stage planetary gear mechanism including these can be made thinner in the axial direction. Further, according to the exemplary 2 nd aspect of the present invention, the rotational motion obtained from the drive motor can be transmitted to the wheel to rotate the wheel while the rotational motion is decelerated by the two-stage planetary gear mechanism.

The above and other features, elements, steps, features and advantages of the present invention will be more clearly understood from the following detailed description of preferred embodiments of the present invention with reference to the accompanying drawings.

Drawings

Fig. 1 is a longitudinal sectional view of a wheel drive device of embodiment 1.

Fig. 2 is a partial longitudinal sectional view of the wheel drive device of embodiment 1.

Fig. 3 is a cross-sectional view of the two-stage planetary gear mechanism of embodiment 1.

Fig. 4 is a cross-sectional view of the two-stage planetary gear mechanism of embodiment 1.

Fig. 5 is a longitudinal sectional view of the two-stage planetary gear mechanism of embodiment 2.

Detailed Description

Hereinafter, exemplary embodiments of the present application will be described with reference to the drawings. In the present application, a direction parallel to the center axes of the two-stage planetary gear mechanism and the wheel drive device of the present invention is referred to as an "axial direction", a direction perpendicular to the center axes of the two-stage planetary gear mechanism and the wheel drive device is referred to as a "radial direction", and a direction along an arc centered on the center axes of the two-stage planetary gear mechanism and the wheel drive device is referred to as a "circumferential direction". In the present application, the shape and positional relationship of each portion will be described with the axial direction as the left-right direction, the right side as the "one axial side", and the left side as the "other axial side" in fig. 1, 2, and 5. However, the directions of the two-stage planetary gear mechanism and the wheel drive device in the manufacturing and use of the present invention are not intended to be limited by the definition of the right-left direction. In the present application, the "parallel direction" also includes a substantially parallel direction. In the present application, the "vertical direction" also includes a substantially vertical direction.

< 1. Embodiment 1 >

The structure of a wheel drive device 100 including the two-stage planetary gear mechanism 1 according to embodiment 1 of the present invention will be described below. Fig. 1 is a longitudinal sectional view of a wheel drive device 100 of embodiment 1. Fig. 2 is a partial longitudinal sectional view of the wheel drive device 100 of embodiment 1. Fig. 3 isbase:Sub>A cross-sectional view of the two-stage planetary gear mechanism 1 as viewed frombase:Sub>A-base:Sub>A position in fig. 1. Fig. 4 is a cross-sectional view of the two-stage planetary gear mechanism 1 as viewed from a position B-B in fig. 1.

The wheel drive device 100 of the present invention is a device that moves a carriage frame (not shown) on which a material to be transported such as a material and a component is placed in various places such as a production line of a factory, a hospital, and an office, for example. The wheel drive device 100 includes a drive motor (not shown), the two-stage planetary gear mechanism 1, wheels 6, tires 7, and a housing. The wheel drive device 100 transmits the rotational motion obtained from the drive motor to the wheel 6 while decelerating the rotational motion using the two-stage planetary gear mechanism 1, and moves by rotating the tire 7.

The drive motor has: a stationary portion including a stator; and a rotating portion that rotates about a motor center axis 20 extending in a horizontal direction (left-right direction in fig. 1) with respect to the stationary portion. The other axial end of the rotating shaft, which is a part of the rotating portion, is fixed to the cap 22. The outer peripheral surface of the cap 22 extends cylindrically along the motor center axis 20.

Next, a detailed configuration of the two-stage planetary gear mechanism 1 will be described. The two-stage planetary gear mechanism 1 is disposed along a central axis 90 extending in the axial direction. In the present embodiment, the central axis 90 and the motor central axis 20 of the drive motor coincide with each other. The two-stage planetary gear mechanism 1 is a device that converts a rotational motion at an input rotation speed N1 into a rotational motion at an output rotation speed N3 lower than the input rotation speed N1 and increases an output torque. In the present embodiment, the rotation speed of the drive motor is the input rotation speed N1. However, the drive motor and the two-stage planetary gear mechanism 1 may be indirectly connected via a pulley or the like. In this case, the rotation speed of the drive motor may be different from the input rotation speed N1. The two-stage planetary gear mechanism 1 includes a flange portion 5, a 1 st planetary gear device 30, and a 2 nd planetary gear device 40.

The flange 5 is a member extending in a ring plate shape radially outward of the rotation shaft of the drive motor. The flange portion 5 of the present embodiment is fixed to the housing of the wheel drive device 100. Therefore, the flange portion 5 itself does not rotate, and moves only in the horizontal direction in accordance with the rotation of the tire 7. Further, a stationary portion of the drive motor is fixed to the housing. That is, the flange portion 5 is indirectly fixed to the stationary portion of the drive motor via the housing. However, the flange portion 5 may be directly fixed to the stationary portion of the drive motor.

As shown in fig. 1 and 2, the flange portion 5 is provided with a through hole 50. The through hole 50 penetrates a part of the flange 5 in the axial direction. Further, the flange portion 5 is provided with a socket portion 52. The socket portion 52 is a cylindrical portion that protrudes axially toward the other side with the center axis 90 as the center at the end surface on the other axial side of the flange portion 5.

A 1 st bearing 23 is disposed radially between the flange portion 5 and the cap portion 22. As shown in fig. 2, the 1 st bearing 23 includes an inner race 231, a plurality of balls 232, and an outer race 233. The inner ring 231 is fixed to the outer peripheral surface of the cap 22. A plurality of balls 232 are interposed between the inner ring 231 and the outer ring 233. The outer race 233 is fixed to the inner peripheral surface of the flange portion 5. Thereby, the cap 22 is supported together with the rotation shaft of the drive motor via the 1 st bearing 23 so as to be rotatable about the motor center axis 20 with respect to the flange portion 5. Thus, the 1 st bearing 23 uses a ball bearing. However, instead of the ball bearing, a bearing of another type such as a roller bearing may be used.

The 1 st planetary gear device 30 is a device that converts a rotational motion at an input rotation speed N1 into a rotational motion at an intermediate rotation speed N2 lower than the input rotation speed N1. As shown in fig. 1 and 2, the 1 st planetary gear device 30 includes a 1 st sun gear 31, a plurality of (3 in the present embodiment) 1 st planetary gears 32, a plurality of (3 in the present embodiment) 1 st carrier pins 33, a 1 st carrier 34, and a 1 st internal gear 35. The 1 st planetary gear device 30 transmits power by rotating the 1 st sun external teeth 311 of the 1 st sun gear 31, which will be described later, with the 1 st planet external teeth 321 of the plurality of 1 st planetary gears 32 and the 1 st internal teeth 351 of the 1 st internal gear 35 while meshing with each other.

The 1 st sun gear 31 is a gear disposed substantially coaxially with the central axis 90. The 1 st sun gear 31 is fixed to the other axial side of the cap 22 so as not to be rotatable relative to each other. Thus, the 1 st sun gear 31 receives the rotation of the drive motor and rotates together with the rotation shaft and the cap 22 around the central axis 90 at the input rotation speed N1. However, the 1 st sun gear 31 and the rotation shaft or the cap 22 may be formed of one member. That is, the 1 st sun gear 31 may be connected to a rotating portion of the drive motor. This enables the rotation of the drive motor to be transmitted to the 1 st planetary gear device 30. The 1 st sun gear 31 has a plurality of external teeth (hereinafter referred to as "1 st sun external teeth 311") on the outer peripheral surface. Each of the 1 st sun external teeth 311 protrudes outward in the radial direction. The plurality of 1 st sun external teeth 311 are arranged at a constant pitch in the circumferential direction.

The 1 st planetary gear 32 is disposed along the 1 st rotation axis 91 around the 1 st sun gear 31. In the present embodiment, the 1 st rotation axis 91 is substantially parallel to the center axis 90. In addition, the 1 st planetary gear 32 of the present embodiment uses a helical gear. This improves the transmission efficiency between the 1 st sun gear 31 and the 1 st planetary gear 32. As shown in fig. 3, in the present embodiment, 31 st planetary gears 32 are disposed around the 1 st sun gear 31 at equal intervals. However, the number of the 1 st planetary gears 32 of the 1 st planetary gear device 30 may be 2, or 4 or more. Each of the 1 st planetary gears 32 has a plurality of external teeth (hereinafter referred to as "1 st planetary external teeth 321") on an outer peripheral surface. The 1 st planetary outer teeth 321 protrude outward.

The 1 st planetary external teeth 321 of each 1 st planetary gear 32 mesh with the 1 st sun external teeth 311 of the 1 st sun gear 31 from the radially outer side. Thus, when the 1 st sun gear 31 rotates about the central axis 90, the 1 st planetary gears 32 receive the power from the 1 st sun gear 31 and rotate about the 1 st rotation axis 91 in the direction opposite to the rotation direction of the 1 st sun gear 31. In addition, each 1 st planetary gear 32 has a through hole 320. Each through hole 320 penetrates the 1 st planetary gear 32 along the 1 st rotation axis 91.

The 31 st carrier pins 33 are members for supporting the 1 st planetary gears 32 so as to be rotatable, respectively. For example, a columnar member extending along the 1 st rotation axis 91 is used for each 1 st wheel carrier pin 33. The 1 st carrier pin 33 is inserted into the through hole 320 of the 1 st planetary gear 32. Further, a 2 nd bearing 325 is inserted between the 1 st carrier pin 33 and the 1 st planetary gear 32. The 2 nd bearing 325 of the present embodiment uses a needle bearing. Thereby, the 1 st planetary gear 32 is supported by the 1 st carrier pin 33 so as to be rotatable about the 1 st rotation axis 91.

Further, as shown in fig. 2, a washer 36 (2 nd washer) is disposed between the 1 st planetary gear 32 and the 1 st carrier pin 33 and the flange portion 5 in the axial direction. The 1 st planetary gear 32 and the 1 st carrier pin 33 are in contact with the other axial side of the flange portion 5 via a washer 36. Thereby, the 1 st planetary gear 32 and the 1 st carrier pin 33 can slide with respect to the flange portion 5, and the load applied to these components at the time of sliding can be suppressed. In the adjustment stage in the middle of assembling the double planetary gear mechanism 1, the washer 36 is interposed between the 1 st planetary gear 32 and the 1 st carrier pin 33 and the flange 5 in the axial direction. The number of the washers 36 may be 1 or more. The number of the washers 36 may be 0 (i.e., not sandwiched). This makes it possible to easily adjust the positions of the 1 st planetary gear 32 and the 1 st carrier pin 33 in the axial direction of the flange 5. Instead of disposing the washer 36, a gasket or the like may be disposed. Further, grease may be present between the 1 st planetary gear 32 and the 1 st carrier pin 33 and the flange portion 5 in the axial direction, in addition to the washer 36, the washer, and the like.

The 1 st carrier 34 is a member that extends in a circular plate shape around the center axis 90. As shown in fig. 2, the 1 st carrier 34 has a plurality of (3 in the present embodiment) through holes 340. Each through hole 340 penetrates the 1 st carrier 34 along the 1 st rotation axis 91 at a position radially outward of the center axis 90. The 3 through holes 340 are provided at intervals of substantially 120 degrees in the circumferential direction around the central axis 90. Also, the 31 st carrier pins 33 are inserted into the through holes 340 at the other axial side portions, respectively. In the present embodiment, each of the 1 st carrier pins 33 is fixed to the 1 st carrier 34 by bonding, press fitting, or the like in the through hole 340. Thus, the 1 st carrier pins 33 are fixed to the 1 st carrier 34 at positions radially outward of the center axis 90 so as not to rotate relative to each other. When the 1 st carrier 34 rotates about the central axis 90, the 31 st carrier pins 33 fixed to the 1 st carrier 34 and the 1 st planetary gear 32 supported by the 1 st carrier pins 33 revolve in the circumferential direction about the central axis 90.

As shown in fig. 2, a washer 37 (1 st washer) is disposed between the 1 st carrier 34 and a projecting portion 447 of a 2 nd carrier 44 described later in the axial direction. The 1 st carrier 34 is in contact with one axial side of the projecting portion 447 of the 2 nd carrier 44 via a washer 37. Thus, the projecting portions 447 of the 1 st carrier 34 and the 2 nd carrier 44 can slide relative to each other, and the load applied to these members during sliding can be suppressed. In the adjustment stage in the middle of assembling the double planetary gear mechanism 1, the washer 37 is interposed between the 1 st carrier 34 and the 2 nd carrier 44 in the axial direction of the projecting portion 447. The number of the washers 37 may be 1 or more. The number of the washers 37 may be 0 (i.e., not sandwiched). This makes it possible to easily adjust the axial position of the 1 st carrier 34 with respect to the projecting portion 447 of the 2 nd carrier 44. Instead of disposing the washer 37, a gasket or the like may be disposed. Further, grease may be present between the 1 st carrier 34 and the 2 nd carrier 44 in the axial direction, in addition to the gasket 37, the washer, and the like.

As described above, the 1 st carrier 34 is in contact with the axial one-side end surface of the projecting portion 447 of the 2 nd carrier 44 via the washer 37. Further, one axial end portion of the 31 st carrier pins 33 fixed to the 1 st carrier 34 is in contact with the other axial end surface of the flange portion 5 via a washer 36. Thus, the 31 st carrier pins 33 and the 1 st carrier 34 are stably arranged without being vibrated in the axial direction. In the 1 st carrier 34, 31 st carrier pins 33 are fixed at intervals of substantially 120 degrees in the circumferential direction, and each 1 st carrier pin 33 supports the 1 st planetary gear 32, and further, the 1 st planetary external teeth 321 of the 1 st planetary gear 32 mesh with the 1 st sun external teeth 311 of the 1 st sun gear 31 from the radially outer side, and mesh with the 1 st internal teeth 351 of the 1 st internal gear 35 from the radially inner side, as will be described later. Thus, the 1 st carrier 34 is stably arranged without being vibrated in the radial direction and stably rotates in the circumferential direction around the center axis 90.

The 1 st internal gear 35 is arranged substantially coaxially with the center axis 90. The 1 st internal gear 35 is a member that expands in an annular cylindrical shape with the center axis 90 as the center. Further, a plurality of 1 st internal teeth 351 are formed on the inner peripheral surface of the 1 st internal gear 35. The 1 st internal teeth 351 each protrude radially inward. The plurality of 1 st internal teeth 351 are arranged at a constant pitch in the circumferential direction. Further, the 1 st internal teeth 351 of the 1 st internal gear 35 mesh with the 1 st planetary external teeth 321 of each of the 31 st planetary gears 32 from the radially outer side. As will be described later, the 1 st internal gear 35 of the present embodiment is fixed to the flange portion 5 so as not to be relatively rotatable, and therefore is configured not to rotate about the center axis 90.

When the 1 st sun gear 31 rotates around the center axis 90 at the input rotation speed N1, the 31 st planetary gears 32 meshing with both the 1 st sun gear 31 and the 1 st internal gear 35 rotate around the 1 st rotation axis 91. Each of the 31 st planetary gears 32 revolves around the center axis 90 at the intermediate rotation speed N2 together with the 1 st carrier pin 33 by meshing with the 1 st sun gear 31 and the 1 st internal gear 35 while rotating around the 1 st rotation axis 91. Thereby, the 1 st carrier 34 that fixes the 31 st carrier pins 33 rotates around the central axis 90 at the intermediate rotation speed N2. That is, the 1 st carrier 34 supports the 31 st planetary gears 32 and the 1 st carrier pins 33 so as to be able to revolve around the central axis 90 in the circumferential direction, and rotates around the central axis 90 at the intermediate rotation speed N2 as the 31 st planetary gears 32 and the 1 st carrier pins 33 revolve around.

The 2 nd planetary gear device 40 is a device that converts the rotational motion at the intermediate rotational speed N2 into the rotational motion at the output rotational speed N3 lower than the intermediate rotational speed N2. As shown in fig. 1 and 2, the 2 nd planetary gear device 40 includes a 2 nd sun gear 41, a plurality of (3 in the present embodiment) 2 nd planetary gears 42, a plurality of (3 in the present embodiment) 2 nd carrier pins 43, a 2 nd carrier 44, and a 2 nd internal gear 45. The 2 nd planetary gear device 40 transmits power by rotating the 2 nd sun external teeth 411 of the 2 nd sun gear 41, which will be described later, and the 2 nd planet external teeth 421 of the plurality of 2 nd planetary gears 42 while meshing with the 2 nd internal teeth 451 of the 2 nd internal gear 45.

The 2 nd sun gear 41 is a gear disposed substantially coaxially with the central axis 90. The 2 nd sun gear 41 is fixed to the other axial side of the 1 st carrier 34 so as not to rotate relative to each other. Thereby, the 2 nd sun gear 41 rotates together with the 1 st carrier 34 around the central axis 90 at the intermediate rotation speed N2. However, the 2 nd sun gear 41 and the 1 st carrier 34 may be formed of one member. That is, the 2 nd sun gear 41 may be connected to the other axial side of the 1 st carrier 34. The 2 nd sun gear 41 has a plurality of external teeth (hereinafter referred to as "2 nd sun external teeth 411") on the outer peripheral surface. Each of the plurality of 2 nd sun external teeth 411 protrudes outward in the radial direction. The plurality of 2 nd sun outer teeth 411 are arranged at regular intervals in the circumferential direction.

The 2 nd planetary gear 42 is disposed along the 2 nd rotation axis 92 around the 2 nd sun gear 41. In the present embodiment, the 2 nd rotation axis 92 is substantially parallel to the center axis 90. The 2 nd rotation axis 92 is located radially outward of the 1 st rotation axis 91. The 2 nd planetary gear 42 of the present embodiment uses a helical gear. This improves the transmission efficiency between the 2 nd sun gear 41 and the 2 nd planetary gear 42. As shown in fig. 4, in the present embodiment, 32 nd planetary gears 42 are disposed around the 2 nd sun gear 41 at equal intervals. However, the number of the 2 nd planetary gears 42 included in the 2 nd planetary gear device 40 may be 2, or 4 or more. Each of the 2 nd planetary gears 42 has a plurality of external teeth (hereinafter referred to as "2 nd planetary external teeth 421") on the outer peripheral surface. The plurality of 2 nd planetary outer teeth 421 protrude outward, respectively.

The 2 nd planetary external teeth 421 of each 2 nd planetary gear 42 are meshed with the 2 nd sun external teeth 411 of the 2 nd sun gear 41 from the radially outer side. Thus, when the 2 nd sun gear 41 rotates about the center axis 90, the 2 nd planetary gears 42 receive the power from the 2 nd sun gear 41 and rotate about the 2 nd rotation axis 92 in the direction opposite to the rotation direction of the 2 nd sun gear 41. In addition, each 2 nd planetary gear 42 has a through hole 420. Each through hole 420 penetrates the 2 nd planetary gear 42 along the 2 nd rotation axis 92.

The 32 nd carrier pins 43 are members for supporting the 1 nd 2 nd planetary gear 42 to be rotatable, respectively. For example, a columnar pin extending along the 2 nd rotation axis 92 is used for each 2 nd carrier pin 43. The 2 nd carrier pin 43 is inserted into the through hole 420 of the 2 nd planetary gear 42. Further, a 3 rd bearing 425 is inserted between the 2 nd carrier pin 43 and the 2 nd planetary gear 42. The 3 rd bearing 425 of the present embodiment uses a needle bearing. Thereby, the 2 nd planetary gear 42 is supported by the 2 nd carrier pin 43 so as to be rotatable about the 2 nd rotation axis 92.

The 2 nd carrier 44 has a 2 nd carrier circular ring portion 441, a 2 nd carrier circular bottom portion 442, and a 2 nd carrier connection portion 443. The 2 nd carrier annular portion 441 extends annularly around the center axis 90 at a position on the axial side of the 2 nd sun gear 41. The 2 nd carrier circular bottom portion 442 radially expands like a circular plate around the center axis 90 at the other axial side than the 2 nd sun gear 41. The 2 nd carrier connection portion 443 extends in the axial direction at a position radially outward of the 2 nd sun gear 41. The 2 nd carrier joint portion 443 connects the 2 nd carrier circular ring portion 441 and the 2 nd carrier circular bottom portion 442 in the axial direction. However, the 2 nd carrier connection portion 443 is located at a position different from the 2 nd planetary gear 42 and the 2 nd carrier pin 43 in the circumferential direction, and does not contact the 2 nd planetary gear 42 and the 2 nd carrier pin 43.

The 2 nd wheel carrier annular portion 441 is provided with a plurality of (3 in the present embodiment) through holes 444. The through-holes 444 are continuous with the through-holes 420 of the 2 nd planetary gears 42 while penetrating the 2 nd carrier annular portion 441 in the axial direction. In addition, a plurality of (3 in the present embodiment) holes 445 are provided in the 2 nd wheel frame round bottom portion 442. The hole 445 is recessed from an end surface of the 2 nd carrier round bottom portion 442 on one axial side toward the other axial side, and is continuous with the through hole 420 of the 2 nd planetary gear 42. The 2 nd carrier pin 43 is inserted into the hole 445 of the 2 nd carrier circular bottom portion 442 while passing through the through hole 444 of the 2 nd carrier annular portion 441 and the through holes 420 of the 2 nd planetary gear 42, and is fixed by press-fitting into the hole 445.

The 2 nd carrier annular portion 441 is provided with a screw hole 446. The screw hole 446 is recessed from an end surface of the 2 nd carrier annular portion 441 on one side in the axial direction to the other side in the axial direction at a position different from the through hole 444 in the circumferential direction, and is continuous with the through hole 50 of the flange portion 5. The 2 nd carrier 44 is fixed to the flange portion 5 so as not to be relatively rotatable by fastening bolts 51 inserted through the through holes 50 of the flange portion 5 to the screw holes 446 of the 2 nd carrier annular portion 441.

The socket portion 52 of the flange portion 5 is fitted to the outer peripheral surface of the axial end portion of the 2 nd wheel carrier annular portion 441. This makes it possible to relatively easily position the flange portion 5 and the 2 nd carrier 44. Further, the accuracy of the coaxiality of the flange portion 5 and the 2 nd carrier 44 can be improved, and noise and vibration can be further suppressed when the respective portions rotate. In the present embodiment, the flange portion 5 and the 2 nd carrier 44 may be formed of one member. In addition, the 2 nd wheel carrier circular portion 441 has a protruding portion 447. The projecting portion 447 projects radially inward over the entire circumference at the other axial end of the 2 nd carrier annular portion 441 (near the boundary with the 2 nd carrier coupling portion 443).

The 1 st internal gear 35 of the 1 st planetary gear device 30 is formed on the inner peripheral surface of the 2 nd carrier annular portion 441 at a position on the one axial side of the projecting portion 447. Further, the 2 nd carrier 44 including the 1 st internal gear 35 is constituted by a single member. The 1 st internal gear 35 is formed on the inner peripheral surface of the 2 nd carrier 44 by, for example, gear shaping or rotational scraping. Thus, the work of fixing the 1 st internal gear 35 and the 2 nd carrier 44, which may be generated on the assumption that the 1 st internal gear 35 and the 2 nd carrier 44 are separately formed and connected, respectively, is not required. As a result, the number of members such as bolts for fixing them can be reduced, and workability in assembling the two-stage planetary gear mechanism and the wheel drive device 100 can be improved, which contributes to reduction in manufacturing cost. Further, the accuracy of the coaxiality of the 1 st internal gear 35 and the 2 nd carrier 44 including the 1 st internal gear 35 can be improved, and noise and vibration during rotation can be further suppressed. In addition, it is possible to further suppress the occurrence of the meshing failure of the 1 st planetary gear 32 and the 1 st internal gear 35 at the time of rotation due to the step difference between the 1 st internal gear 35 and the 2 nd carrier 44, which may occur in the case where the 1 st internal gear 35 and the 2 nd carrier 44 are separately formed and axially connected, respectively.

Further, by having the above-described configuration, the entire two-stage planetary gear mechanism 1 including the 1 st internal gear 35 and the 2 nd carrier 44 can be made thinner in the axial direction, as compared with a case where these are separately formed and connected in the axial direction. In particular, the 2 nd carrier pin 43 of the present embodiment is disposed radially outward of the 1 st planetary gear 32. This makes it possible to further reduce the thickness of the entire two-stage planetary gear mechanism 1 including these components in the axial direction.

The position where the 1 st internal gear 35 is formed is not limited to the inner circumferential surface of the 2 nd carrier annular portion 441. The 1 st internal gear 35 may be formed on at least a part of the inner circumferential surface of the 2 nd carrier 44. Chromium molybdenum steel is used as the material of the 2 nd carrier 44 including the 1 st internal gear 35 of the present embodiment. This improves the wear resistance of the 1 st internal teeth 351. However, other materials may be used for the 2 nd wheel carrier 44.

The 2 nd internal gear 45 is arranged substantially coaxially with the central axis 90. The 2 nd internal gear 45 is a member that expands in an annular cylindrical shape centering on the central axis 90. Further, a plurality of 2 nd internal teeth 451 are formed on the inner peripheral surface of the axial center portion of the 2 nd internal gear 45. The plurality of 2 nd internal teeth 451 each protrude radially inward. The plurality of 2 nd internal teeth 451 are arranged at regular intervals in the circumferential direction. Further, the 2 nd internal teeth 451 of the 2 nd internal gear 45 mesh with the 2 nd planetary external teeth 421 of each of the 32 nd planetary gears 42 from the radially outer side.

A 4 th bearing 46 is disposed between the 2 nd internal gear 45 and the 2 nd carrier 44 in the radial direction. As shown in fig. 2, the 4 th bearing 46 includes an inner race 461, a plurality of balls 462, and an outer race 463. The inner race 461 is fixed to the outer peripheral surface of the 2 nd carrier 44. A plurality of balls 462 are interposed between the inner race 461 and the outer race 463. The outer ring 463 is fixed to the inner peripheral surface of the 2 nd internal gear 45. Thereby, the 2 nd internal gear 45 is rotatably supported on the outer peripheral surface of the 2 nd carrier 44 via the 4 th bearing 46. Thus, the 4 th bearing 46 uses a ball bearing. However, instead of the ball bearing, a bearing of another type such as a roller bearing may be used.

When the 2 nd sun gear 41 rotates together with the 1 st carrier 34 about the central axis 90 at the intermediate rotation speed N2, the 3 nd 2 nd planetary gears 42 meshing with both the 2 nd sun gear 41 and the 2 nd internally toothed gear 45 rotate about the 2 nd rotation axis 92, respectively. However, as described above, the 2 nd carrier pins 43 that support the 2 nd planetary gear 42 so as to be rotatable are fixed to the 2 nd carrier 44, and the 2 nd carrier 44 is fixed to the flange portion 5 so as not to be relatively rotatable. Further, the flange portion 5 is fixed to the housing of the wheel drive device 100, and therefore does not rotate. Therefore, even if each of the 32 nd planetary gears 42 rotates about the 2 nd rotation axis 92, it does not revolve about the central axis 90. As a result, the 2 nd internal gear 45 rotates about the central axis 90 at the output rotation speed N3 as the 2 nd planetary gear 42 rotates about the 2 nd rotation axis 92. That is, in the present embodiment, the 2 nd internal gear 45 located radially outermost in the double-stage planetary gear mechanism 1 is configured to rotate around the central axis 90 at the output rotation speed N3. This reduces the number of components of the double-stage planetary gear mechanism 1 and improves workability in assembly.

As shown in fig. 1, the 2 nd internal gear 45 is further provided with a screw hole 450. The screw hole 450 is recessed from the end surface on the other axial side of the 2 nd internal gear 45 toward the one axial side.

The wheel 6 has a tire support portion 61 and a connecting portion 62. The tire support portion 61 has an outer peripheral surface that expands cylindrically in the axial direction along the center axis 90 on the radially outer side of the 2 nd internal gear 45. The tire 7 is fixed to the outer peripheral surface of the tire support portion 61. The connecting portion 62 is a disc-shaped portion that covers the other axial end of the tire support portion 61. The connection portion 62 has a through hole 620. The through hole 620 extends axially through a portion near the outer peripheral portion of the connecting portion 62 and is continuous with one axial side of the screw hole 450 of the 2 nd internal gear 45. The wheel 6 is fixed to the 2 nd internal gear 45 so as not to be relatively rotatable by fixing the bolt 63 penetrating the through hole 620 of the connecting portion 62 to the screw hole 450 of the 2 nd internal gear 45.

When the wheel drive device 100 is used, the wheel 6 and the tire 7 rotate together with the 2 nd internal gear 45 around the central axis 90 at the reduced output rotation speed N3. Thereby, the wheel drive device 100 can move at a low speed in the horizontal direction (the near-forward or depth direction in fig. 1).

< 2 > embodiment 2

Next, the structure of the two-stage planetary gear mechanism 1B according to embodiment 2 of the present invention will be described. In the following description, differences from embodiment 1 will be mainly described, and the same portions as embodiment 1 will not be partially described in a redundant manner. Fig. 5 is a longitudinal sectional view of the two-stage planetary gear mechanism 1B according to embodiment 2.

As shown in fig. 5, the double-pinion planetary gear mechanism 1B includes a flange portion 5B, a 1 st planetary gear device 30B, and a 2 nd planetary gear device 40B.

The flange portion 5B is a member that extends radially outward in an annular plate shape from the rotation shaft of the drive motor. The flange portion 5B of the present embodiment has substantially the same configuration as the flange portion 5 of embodiment 1. However, the flange portion 5B of the present embodiment is provided with a socket portion 52B at a position different from that of embodiment 1. The socket portion 52B is a cylindrical portion that protrudes axially toward the other side with the center axis 90B as the center on the outer peripheral portion of the flange portion 5B. In addition, the flange portion 5B of the present embodiment is provided with a plurality of through holes 50B. Each through hole 50B axially penetrates a portion near the outer peripheral portion of the flange portion 5B.

The 1 st planetary gear device 30B of the present embodiment has substantially the same configuration as the 1 st planetary gear device 30 of the 1 st embodiment. When the 1 st sun gear 31B rotates around the central axis 90B at the input rotation speed N1, the 31 st planetary gears 32B meshing with both the 1 st sun gear 31B and the 1 st internal gear 35B rotate around the 1 st rotation axis 91B. Further, each of the 31 st planetary gears 32B revolves around the center axis line 90B at the intermediate rotation speed N2 together with the 1 st carrier pin 33B by meshing with the 1 st sun gear 31B and the 1 st internal gear 35B while rotating around the 1 st rotation axis 91B. Thereby, the 1 st carrier 34B to which the 31 st carrier pins 33B are fixed rotates around the central axis 90B at the intermediate rotation speed N2. That is, the 1 st carrier 34B supports the 31 st planetary gears 32B and the 1 st carrier pins 33B so as to be able to revolve in the circumferential direction around the central axis 90B, and rotates around the central axis 90B at the intermediate rotation speed N2 with the revolution of the 31 st planetary gears 32B and the 1 st carrier pins 33B.

The 2 nd planetary gear device 40B has a 2 nd sun gear 41B, a plurality of 2 nd planetary gears 42B, a plurality of 2 nd carrier pins 43B, a 2 nd carrier 44B, and a 2 nd internal gear 45B. The 2 nd sun gear 41B, the plurality of 2 nd planetary gears 42B, and the plurality of 2 nd carrier pins 43B according to the present embodiment have substantially the same configurations as the 2 nd sun gear 41, the plurality of 2 nd planetary gears 42, and the plurality of 2 nd carrier pins 43 according to embodiment 1, and therefore, redundant description is omitted.

The 2 nd wheel frame 44B of the present embodiment has substantially the same structure as the 2 nd wheel frame 44 of the 1 st embodiment. The 2 nd carrier pin 43B is inserted into the hole 445B of the 2 nd carrier 44B while passing through the through hole 444B of the 2 nd carrier 44B and the through hole 420B of the 2 nd planetary gear 42B, and is fixed to the hole 445B by press fitting. However, the 2 nd carrier 44B of the present embodiment is not provided with a portion corresponding to the screw hole 446 of the 1 st embodiment. The 2 nd carrier 44B of the present embodiment is not fixed to the flange portion 5B, and can rotate relative to each other. The 2 nd carrier 44B is rotatably supported on the inner peripheral surface of the 2 nd internal gear 45B via 2 4 th bearings 46B arranged so as to be axially spaced apart. The socket portion 52B of the flange portion 5B is fitted to the outer peripheral surface of the 4 th bearing 46B located on one axial side of the 2 4 th bearings 46B. This makes it possible to relatively easily position the flange portion 5B and the 4 th bearing 46B. The 2 nd carrier 44B supports the 32 nd planetary gears 42B so as to be rotatable about the 2 nd rotation axis 92, respectively, and also supports the 32 nd carrier pins 43B and the 32 nd planetary gears 42B so as to be revolvable about the central axis 90B in the circumferential direction.

Similarly to embodiment 1, the 1 st internal gear 35B of the 1 st planetary gear device 30B is formed on the inner peripheral surface of the 2 nd carrier 44B. The 2 nd carrier 44B including the 1 st internal gear 35B is formed of a single member. Thus, the work of fixing the 1 st internal gear 35B and the 2 nd carrier 44B, which may be generated on the assumption that the 1 st internal gear 35B and the 2 nd carrier 44B are separately formed and connected, respectively, is not required. As a result, the number of members such as bolts for fixing them can be reduced, and workability in assembling the two-stage planetary gear mechanism can be improved, which contributes to reduction of manufacturing cost.

The 2 nd internal gear 45B of the present embodiment has substantially the same configuration as the 2 nd internal gear 45 of the 1 st embodiment. As described above, the 2 nd carrier 44B is rotatably supported on the inner peripheral surface of the 2 nd internal gear 45B via the 4 th bearing 46B. However, the 2 nd internal gear 45B of the present embodiment is provided with a plurality of screw holes 450B. Each screw hole 450B is recessed from one axial end surface of the 2 nd internal gear 45B to the other axial end surface, and is continuous with the through hole 50B of the flange portion 5B. The 2 nd internal gear 45B is fixed to the flange portion 5B so as not to be able to rotate by fastening bolts 51B, which penetrate through the through holes 50B of the flange portion 5B, to the screw holes 450B by bolts.

When the 2 nd sun gear 41B rotates together with the 1 st carrier 34B around the center axis line 90B at the intermediate rotation speed N2, the 32 nd planetary gears 42B meshing with both the 2 nd sun gear 41B and the 2 nd internal gear 45B each rotate around the 2 nd rotation axis line 92B. Further, the 32 nd planetary gears 42B revolve together with the 2 nd carrier pin 43B around the central axis line 90B at the output rotation speed N3 by meshing with the 2 nd sun gear 41B and the 2 nd internal gear 45B. Thus, the 2 nd carrier 44B rotates around the center axis 90B at the output rotation speed N3 according to the revolution of the 2 nd carrier pin 43B and the 2 nd planetary gear 42B. That is, in the present embodiment, the output rotation can be taken out from the 2 nd carrier 44B.

< 3. Modification example >

The present invention is not limited to the above-described embodiments, but may be embodied in many different forms.

As disclosed in embodiment 1 and embodiment 2 above, the two-stage planetary gear mechanism of the present invention may have the following structure: one of the 2 nd carrier and the 2 nd internal gear is supported via a bearing so as to be relatively rotatable about the center axis by the other of the 2 nd carrier and the 2 nd internal gear, and rotates about the center axis at an output rotation speed.

The detailed shapes of the two-stage planetary gear mechanism and the wheel drive device may be different from those shown in the drawings of the above embodiments.

The present invention can be used in, for example, a two-stage planetary gear mechanism and a wheel drive device.

Claims (13)

1. A two-stage type planetary gear mechanism having:

a 1 st planetary gear device that converts an input rotation speed to an intermediate rotation speed lower than the input rotation speed; and

a 2 nd planetary gear device that converts the intermediate rotation speed to an output rotation speed lower than the intermediate rotation speed,

the 1 st planetary gear device includes:

a 1 st sun gear that rotates around a central axis at the input rotation speed;

a 1 st planetary gear having a 1 st planetary external tooth meshing with a 1 st sun external tooth formed on an outer peripheral surface of the 1 st sun gear from a radially outer side;

a 1 st carrier pin that supports the 1 st planetary gear so as to be rotatable about a 1 st rotation axis;

a 1 st carrier to which the 1 st carrier pin is fixed, the 1 st carrier pin and the 1 st planetary gear being supported so as to be capable of revolving in a circumferential direction around the central axis, and rotating around the central axis at the intermediate rotational speed with the 1 st carrier pin and the 1 st planetary gear revolving together; and

a 1 st internal gear disposed coaxially with the center axis and having 1 st internal teeth on an inner peripheral surface thereof to mesh with the 1 st planetary external teeth of the 1 st planetary gear from a radially outer side,

the 2 nd planetary gear device has:

a 2 nd sun gear connected to the other axial side of the 1 st carrier and rotating together with the 1 st carrier around the central axis at the intermediate rotational speed;

a 2 nd planetary gear having a 2 nd planetary external tooth meshing with a 2 nd sun external tooth formed on an outer peripheral surface of the 2 nd sun gear from a radially outer side;

a 2 nd carrier pin that supports the 2 nd planetary gear so as to be rotatable about a 2 nd rotation axis;

a 2 nd carrier to which the 2 nd carrier pin is fixed; and

a 2 nd internal gear disposed coaxially with the center axis and having a 2 nd internal gear on an inner peripheral surface thereof meshing with the 2 nd planetary external gear of the 2 nd planetary gear from a radially outer side,

one of the 2 nd carrier and the 2 nd internal gear is supported by the other of the 2 nd carrier and the 2 nd internal gear via a bearing so as to be relatively rotatable around the central axis and rotates around the central axis at the output rotation speed,

it is characterized in that the preparation method is characterized in that,

the 1 st internal gear is formed on an inner peripheral surface of the 2 nd carrier.

2. The dual stage planetary gear mechanism as in claim 1,

the input rotational speed is the rotational speed of the drive motor,

the 1 st sun gear rotates around the central axis line at the input rotation speed upon receiving rotation of the drive motor.

3. The two-stage planetary gear mechanism according to claim 1 or 2,

the 2 nd wheel carrier is formed of a single member.

4. The two-stage planetary gear mechanism according to claim 2,

the double-stage planetary gear mechanism has a flange portion extending radially outward and directly or indirectly fixed to a stationary portion of the drive motor,

the 2 nd carrier is fixed to the flange portion in a non-rotatable manner,

the 2 nd internal gear is rotatably supported on the outer peripheral surface of the 2 nd carrier via the bearing, and rotates about the central axis line at the output rotation speed as the 2 nd planetary gear rotates about the 2 nd rotation axis line.

5. The dual stage planetary gear mechanism as in claim 2,

the double-stage planetary gear mechanism has a flange portion extending radially outward and directly or indirectly fixed to a stationary portion of the drive motor,

the 2 nd internal gear is fixed to the flange portion so as not to be able to rotate,

the 2 nd carrier is rotatably supported via the bearing on an inner peripheral surface of the 2 nd internal gear, and supports the 2 nd carrier pin and the 2 nd planetary gear so as to be capable of revolving in a circumferential direction around the center axis, and rotates around the center axis at the output rotation speed as the 2 nd carrier pin and the 2 nd planetary gear revolve around the center axis.

6. The two-stage planetary gear mechanism according to claim 4,

the flange portion has a cylindrical socket portion fitted to the outer peripheral surface of the 2 nd wheel frame.

7. The two-stage planetary gear mechanism according to any one of claims 1 to 6,

the 1 st wheel carrier is in contact with one axial side of the 2 nd wheel carrier via 1 or more 1 st washers.

8. The two-stage planetary gear mechanism according to claim 4 or 5,

the 1 st planetary gear is in contact with the other axial side of the flange portion via 1 or more 2 nd washers.

9. The two-stage planetary gear mechanism according to any one of claims 1 to 8,

the 2 nd carrier pin is disposed radially outward of the 1 st planetary gear.

10. The two-stage planetary gear mechanism according to any one of claims 1 to 9, wherein a material of the 2 nd carrier including the 1 st internal gear is chrome molybdenum steel.

11. The dual stage planetary gear mechanism as in any one of claims 1 to 10,

the 1 st planetary gear is a helical gear.

12. The two-stage planetary gear mechanism according to any one of claims 1 to 11,

the 2 nd planetary gear is a helical gear.

13. A wheel driving device is characterized in that,

the wheel driving device comprises:

the dual-stage planetary gear mechanism of claim 4; and

the drive motor is arranged on the upper side of the frame,

the wheel driving means decelerates and transmits the rotation of the driving motor to the wheels,

the wheel is fixed to the 2 nd internal gear.

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