CN111071030A

CN111071030A - Wheel drive device

Info

Publication number: CN111071030A
Application number: CN201910688612.7A
Authority: CN
Inventors: 田村光扩
Original assignee: Sumitomo Heavy Industries Ltd
Current assignee: Sumitomo Heavy Industries Ltd
Priority date: 2018-10-18
Filing date: 2019-07-29
Publication date: 2020-04-28
Anticipated expiration: 2039-07-29
Also published as: JP7362240B2; DE102019123061A1; JP2020063795A; CN111071030B

Abstract

The invention provides a wheel driving device capable of shortening the axial dimension. A wheel driving device (1) of the present invention is provided with: an internal gear member (33) having an internal gear; an external gear (35); a carrier (45) that synchronizes with the rotation component or revolution component of the external gear (35); main bearings (51A, 51B) disposed between the internal gear member and the wheel carrier; and a wheel (11) that rotates integrally with the internal gear member. The wheel carrier (45) has an extension (45B) disposed radially outward of the internal gear member, the main bearings (51A, 51B) are disposed between the extension (45B) and the internal gear member (33), and the outer peripheral portion of the wheel (11) is disposed radially outward of the extension (45B).

Description

Wheel drive device

The present application claims priority based on japanese patent application No. 2018-196339, applied on day 18, 10, 2018. The entire contents of this Japanese application are incorporated by reference into this specification.

Technical Field

The present invention relates to a wheel driving device.

Background

Fig. 1 of patent document 1 discloses a wheel driving device in which a speed reducer is incorporated in a wheel of an unmanned transport vehicle. The wheel driving device includes: an external gear 20 that oscillates by rotation of the eccentric body 19; an internal gear 23 connected to the wheel 12; and main bearings 15 and 16 disposed between the frame 13 and the wheel 12. The main bearings 15, 16 are provided on one side and the other side in the axial direction so as to sandwich the external gear 20.

Patent document 1: japanese laid-open patent publication No. 62-80324

The conventional wheel drive device with a built-in speed reducer has a problem of large axial dimension.

Disclosure of Invention

The invention aims to provide a wheel driving device capable of shortening the axial dimension.

A wheel driving device according to the present invention includes: an internal gear member having an internal gear; an outer gear; a carrier that synchronizes with a rotation component or a revolution component of the external gear; a main bearing disposed between the internal gear member and the carrier; and a wheel that rotates integrally with the internal gear member, wherein the wheel carrier has an extension portion disposed radially outward of the internal gear member, the main bearing is disposed between the extension portion and the internal gear member, and an outer peripheral portion of the wheel is disposed radially outward of the extension portion.

Another wheel driving device according to the present invention includes: an internal gear member having an internal gear; an outer gear; a carrier that synchronizes with a rotation component or a revolution component of the external gear; a main bearing disposed between the internal gear member and the carrier; and a wheel that rotates integrally with the carrier, wherein the carrier has an extension portion disposed radially outward of the internal gear, the main bearing is disposed between the extension portion and the internal gear, and an outer peripheral portion of the wheel is disposed radially outward of the extension portion.

According to the present invention, a wheel driving device with a reduced axial dimension can be provided.

Drawings

Fig. 1 is a partially cut-away side view showing a wheel driving device according to embodiment 1 of the present invention.

Fig. 2 is a view of the wheel drive device according to embodiment 1 as viewed from the side opposite to the motor in the axial direction.

Fig. 3 is a view of the wheel drive device according to embodiment 1 as viewed from the motor side in the axial direction.

Fig. 4 is a cross-sectional view showing a wheel drive device according to embodiment 2 of the present invention.

In the figure: 1. 101-wheel drive device, 11, 111-wheel, 11a, 111 a-rim portion (2 nd axial extension), 11b, 111 b-wheel disc portion (2 nd radial extension), 11c, 111 c-tire portion, 21, 121-motor, 23, 123-motor shaft, 25, 125-housing, 25a, 125 a-screw hole, 31, 131-reduction mechanism, 33, 133-internal gear member, 35, 135-external gear, 37, 137-eccentric body, 43, 143-internal pin, 45, 145-wheel carrier, 45 a-base portion (1 st radial extension), 145 a-1 st radial extension, 45 b-extension (1 st axial extension), 145 b-1 st axial extension, 45 f-flange portion, 45k, 125 k-notched portion, 51A, 51B, 151A, 151B-main bearings, 53A, 53B, 153-input bearings, O1-rotational axis (rotational center axis), G0-running surface (wheel running surface).

Detailed Description

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

(embodiment 1)

Fig. 1 is a partially cut-away side view showing a wheel driving device according to embodiment 1 of the present invention. Fig. 2 is a view of the wheel drive device according to embodiment 1 as viewed from the side opposite to the motor in the axial direction. Fig. 3 is a view of the wheel drive device according to embodiment 1 as viewed from the motor side in the axial direction. The cut-away portion of fig. 1 represents the section along the line of arrow a-a of fig. 2. In fig. 2 and 3, the wheel 11 is indicated by a two-dot chain line. In this specification, a direction along the rotation axis O1 is defined as an axial direction, a direction perpendicular to the rotation axis O1 is defined as a radial direction, and a direction rotating around the rotation axis O1 is defined as a circumferential direction.

The wheel driving device 1 of embodiment 1 is attached to, for example, a main body of an unmanned transport device (carriage) to constitute a wheel with a motor of the unmanned transport device. The wheel drive device 1 includes a wheel 11, a motor 21, and a reduction mechanism 31. Hereinafter, the direction from the speed reduction mechanism 31 to the motor 21 in the axial direction is referred to as a motor side, and the direction from the motor 21 to the speed reduction mechanism 31 is referred to as an opposite side to the motor.

The wheel 11 has a tire portion 11c provided on an outer peripheral portion, a rim portion 11a on which the tire portion 11c is mounted, and a wheel portion 11b that supports the rim portion 11 a. The tire portion 11c has elasticity, and the thickness thereof becomes smaller with use. The wheel disc portion 11b is provided extending in the radial direction on the side of the device opposite to the motor and is coupled to the reduction mechanism 31. The rim portion 11a has a cylindrical shape, and extends from the outer peripheral portion of the rim portion 11b toward the motor side in the axial direction. The rim portion 11b corresponds to an example of the 2 nd radially extending portion according to the present invention, and the rim portion 11a corresponds to an example of the 2 nd axially extending portion according to the present invention.

The motor 21 includes a motor shaft 23 that rotates about a rotation axis O1, a rotor (not shown), a stator, a brake unit, and a housing 25, and the motor 21 drives the motor shaft 23 to rotate by electric power. The housing 25 is provided with a screw hole 25a connected to the main body of the unmanned transport device.

The reduction mechanism 31 is an eccentric oscillating type reduction gear, and includes an internal gear member 33, an external gear 35, an eccentric body 37, an eccentric body bearing 41, an inner pin 43, a carrier 45, a cover 49, a main bearing 51A, a main bearing 51B, an input bearing 53A, an input bearing 53B, and a counter weight (counter weight) 55.

The external gear 35 has a plurality of internal pin holes 35a and a central hole provided at a plurality of locations on a circumference of the same radius, in addition to the external teeth.

The eccentric body 37 is connected to the motor shaft 23 by, for example, a key connection, and rotates integrally with the motor shaft 23. The eccentric body 37 is assembled to axially penetrate through a center hole of the external gear 35. An eccentric body bearing 41 is disposed between the eccentric body 37 and the external gear 35, and the eccentric body 37 is rotatable relative to the external gear 35 inside the external gear 35. The external gear 35 eccentrically oscillates by the rotation of the eccentric body 37.

The internal gear member 33 includes: an internal gear body 33a having a plurality of pin grooves formed in an inner peripheral portion thereof; a plurality of outer pins 33b rotatably supported by the plurality of pin grooves, respectively; and holding

members

33c and 33d coupled to the internal gear body 33a to hold the plurality of outer pins 33 b. The plurality of pin grooves are arranged in a circumferential direction. The ring gear main body 33a and the plurality of outer pins 33b function as a ring gear. The number of teeth of the internal gear member 33 (the number of outer pins 33 b) is different from that of the external gear 35 (for example, the difference in the number of teeth is 1). An external gear 35 is disposed inside the internal gear member 33, and the external teeth of the most eccentric portion of the external gear 35 mesh with the external pins 33b (internal teeth).

The

main bearings

51A and 51B are, for example, ball bearings, and rotatably support the internal gear member 33 about the rotation axis O1.

The carrier 45 is disposed on one side (motor side) in the axial direction of the external gear 35, and holds the plurality of inner pins 43. The plurality of inner pins 43 axially penetrate the plurality of inner pin holes 35a of the external gear 35, respectively. The wheel carrier 45 has: a base portion 45a integrated with the housing 25 of the motor 21; an annular holding frame 45c that holds the plurality of inner pins 43; and a cylindrical extension portion 45b extending from the base portion 45a toward the side opposite to the motor in the axial direction. The holding frame 45c is coupled to the base portion 45a by bolts or the like. The carrier 45 engages with the external gear 35 via the plurality of inner pins 43, and thereby the movement (including the stationary state due to the fixation) of the carrier 45 is synchronized with the rotation component of the external gear 35. The base portion 45a corresponds to an example of the 1 st radially extending portion of the present invention, and the extending portion 45b corresponds to an example of the 1 st axially extending portion of the present invention.

The balance weight 55 is keyed to the motor shaft 23, and when the motor shaft 23 rotates, the balance weight 55 rotates so as to generate a load opposite to a load generated based on the oscillation of the external gear 35. Specifically, the counterweight 55 has a center of gravity on the opposite side of the eccentric body 37 from the eccentric direction.

The

input bearings

53A and 53B rotatably support the motor shaft 23 on one side and the other side in the axial direction with respect to the external gear 35. One input bearing 53A is disposed between the carrier 45 and the motor shaft 23, and the other input bearing 53B is disposed between the cover 49 and the motor shaft 23. The cover 49 covers the motor shaft 23 and the side of the input bearing 53B opposite to the motor, and is coupled to the internal gear member 33. The motor-side end of the motor shaft 23 is rotatably supported by a bearing 27 provided in the motor 21, in addition to the

input bearings

53A and 53B of the reduction mechanism 31.

< deceleration action >

When the motor shaft 23 is rotated by driving of the motor 21, the eccentric body 37 is rotated to eccentrically oscillate the external gear 35. The balance weight 55 rotates with the rotation of the eccentric body 37, and generates a load in the opposite direction to the load generated by the eccentric oscillation of the external gear 35, thereby maintaining the rotational balance inside the speed reduction mechanism 31. The external gear 35 is connected to a carrier 45 via an inner pin 43, and the carrier 45 is fixed to the housing 25 of the motor 21. Therefore, the rotation component of the external gear 35 becomes zero in synchronization with the carrier 45, and the external gear 35 eccentrically swings and does not rotate (rotate).

On the other hand, the meshing position of the external teeth of the external gear 35 and the internal teeth of the internal gear member 33 changes in the circumferential direction as the external gear 35 eccentrically oscillates. Therefore, every 1 rotation of the eccentric body 37, the internal gear member 33 rotates (self-transmits) by an amount corresponding to the difference in the number of teeth (for example, 1 tooth) between the internal gear of the internal gear member 33 and the external gear 35. As a result, the rotational movement of the motor 21 is reduced in speed at a reduction ratio of 1/(the number of teeth of the internal gear) and then output to the wheel 11 integrated with the internal gear 33. The unmanned transport apparatus travels on the traveling surface G0 by the rotation of the wheels 11.

< extension Structure of parts >

The wheel carrier 45 and the wheel 11 that rotates integrally with the internal gear member 33 have a symmetrical extended structure. That is, the base portion (1 st radially extending portion) 45a of the carrier 45 extends radially outward from a portion (holding frame 45 c; may also be referred to as a carrier main body) that holds the plurality of inner pins 43 on one side (motor side: 1 st direction side) in the axial direction of the outer gear 35. The extending portion 45b (1 st axial extending portion) of the carrier 45 extends from the base portion 45a toward the other side in the axial direction (the side opposite to the motor). The extending portion 45b has a flange portion 45f extending radially outward on the motor side, and the flange portion 45f is coupled to the base portion 45a by a bolt or the like.

The disk portion (2 nd radially extending portion) 11b of the wheel 11 extends radially on the side opposite to the motor (the side opposite to the 1 st direction side) with respect to the external gear 35. Moreover, a rim portion (2 nd axially extending portion) 11a of the wheel 11 extends from an outer peripheral portion of the rim portion 11b toward the motor side in the axial direction.

By the extension structure of the carrier 45 and the extension structure of the wheel 11 integrated with the internal gear 33, the internal gear main body 33a, the

main bearings

51A and 51B, the extension portion (1 st axial extension portion) 45B of the carrier 45, the rim portion (2 nd axial extension portion) 11A of the wheel 11, and the tire portion 11c can be arranged in this order from the outer pin 33B of the internal gear 33 toward the radially outer side. The

main bearings

51A and 51B are disposed between (the inner periphery of) the extending portion 45B of the carrier 45 and (the outer periphery of) the internal gear member 33, thereby supporting the internal gear member 33 to be rotatable with respect to the carrier 45.

In this way, the

main bearings

51A and 51B can be arranged radially outward of the internal gear member 33, and thus the

main bearings

51A and 51B can be arranged without increasing the axial dimension of the speed reduction mechanism 31. Although not particularly limited, as a preferable example, the

main bearings

51A and 51B are disposed such that both ends in the axial direction of the

main bearings

51A and 51B are positioned more inward than both ends in the axial direction of the

input bearings

53A and 53B when viewed in the radial direction. Unlike the example of fig. 1, the

main bearings

51A and 51B may be arranged such that both ends of the

main bearings

51A and 51B in the axial direction are located inside both ends of the tire portion 11c in the axial direction. The two ends of the plurality of bearings refer to: the interval portion of the plurality of bearings is also regarded as a part of the bearing, and the plurality of bearings are regarded as both ends when they are integrated.

Further, as a preferable example, although not particularly limited, the two

main bearings

51A and 51B may be arranged such that at least a part of each main bearing overlaps the outer pin 33B when viewed in the radial direction. Further, as a preferable example, although not particularly limited, the two

main bearings

51A and 51B may be arranged such that at least a part of each main bearing overlaps with the external gear 35 when viewed in the radial direction.

Instead of the two

main bearings

51A and 51B, one main bearing (for example, a cross roller bearing or the like) may be used. In this case, as a preferable example, one main bearing is disposed such that both ends in the axial direction thereof are located more inward than both ends in the axial direction of the

input bearings

53A and 53B. Further, as a preferable example, one main bearing may be arranged such that at least a part thereof overlaps the outer pin 33b when viewed in a radial direction. Further, as a preferable example, at least a part of one main bearing may be arranged to overlap with the external gear 35 when viewed in a radial direction.

Further, although the configuration having one external gear 35 is shown in the example of fig. 1, a configuration in which a plurality of external gears are arranged in line in the axial direction may be adopted. In this case, as to whether or not the external gear overlaps the main bearing when viewed in the radial direction, it is sufficient to determine whether or not the main bearing overlaps the external gear when the plurality of external gears are regarded as one body (that is, when the interval portion of the plurality of external gears is also regarded as a part of the external gear).

< details of the extension of the wheel frame >

The extending portion 45b of the wheel carrier 45 extends to a position facing the inner periphery of the corner portion between the wheel disc portion 11b and the rim portion 11a of the wheel 11. An inclined surface S45 is provided on the outer peripheral surface of the distal end portion of the extending portion 45b, and the inclined surface S45 is inclined so that the diameter thereof becomes smaller toward the side opposite to the motor (the distal end side).

The wheel 11 has a thick wall portion 11v with a larger thickness for reinforcement on the inner periphery of the corner portion between the disc portion 11b and the rim portion 11 a. By adopting the inclined surface S45 at the tip end of the extending portion 45b, even if the wheel 11 and the carrier 45 are arranged close to each other in the axial direction, it is possible to suppress the interference between the thick portion 11v of the wheel 11 and the tip end of the extending portion 45b of the carrier 45.

The flange portion 45f of the extending portion 45b of the wheel carrier 45 is provided in a range overlapping with the tire portion 11c of the wheel 11 as viewed in the axial direction (refer to fig. 2 and 3). According to this configuration, when the wheel 11 is removed, the flange portion 45f is exposed on the side opposite to the motor, and the operability of coupling the flange portion 45f to the base portion 45a is improved. Further, as compared with the case where the flange portion 45f is provided radially inward, the radial dimension of the motor 21 or the reduction mechanism 31 can be increased, and the axial dimension can be shortened.

On the other hand, in the outermost peripheral portion (flange portion 45f) of the wheel carrier 45, a cutout 45k is provided in a range facing at least the traveling surface G0, in which the distance L1 from the rotation axis O1 is smaller than the outer radius L2 of the rim portion 11a of the wheel 11. The notch 45k prevents a part of the wheel frame 45 from contacting the running surface G0 even when the thickness of the tire portion 11c decreases as the wheel 11 is used, as the tire portion 11c decreases. The notch 45k is not limited to a surface parallel to the traveling surface G0, and may be formed of a curved surface, for example.

Further, the notch portions 45k, in which the distance L1 from the rotation axis O1 of the outermost peripheral portion (flange portion 45f) of the carrier 45 is smaller than the outer radius L2 of the rim portion 11a, are provided at a plurality of locations in the circumferential direction of the carrier 45 (for example, at four locations, i.e., at the upper, lower, left, and right in fig. 2 and 3). With this configuration, the degree of freedom of the mounting angle (circumferential angle) of the wheel drive device 1 when the wheel drive device 1 is mounted on the main body of the unmanned transport device can be improved. That is, the wheel drive unit 1 may be mounted at an angle at which the cutout portion 45k is located downward, so that even when the tire portion 11c is reduced in size, a part of the wheel frame 45 may not contact the traveling surface G0 by the cutout portion 45 k. Such a degree of freedom of the mounting angle can improve, for example, the workability of fixing and processing the wiring of the motor 21.

< effects of the embodiment >

As described above, according to the wheel drive device 1 of embodiment 1, the

main bearings

51A and 51B are disposed between the extension portion 45B of the carrier 45 and the internal gear member 33, and the outer peripheral portion of the wheel 11 is disposed radially outward of the extension portion 45B of the carrier 45. By adopting such an arrangement, the

main bearings

51A and 51B and the wheel 11 can be arranged so as to overlap the internal gear member 33 in the radial direction, and the axial dimension of the wheel drive device 1 can be shortened. The unmanned transport device may be mounted with a battery for storing electric power of the motor 21 at the same height as the wheel drive device 1. In this case, since the axial dimension of the wheel drive device 1 can be shortened, the mounting space for the battery is increased, and an effect that a larger battery can be mounted is obtained.

Further, according to the wheel drive device 1 of embodiment 1, the wheel carrier 45 has: a base portion 45a extending in the radial direction on one side (motor side) in the axial direction of the external gear 35; and an extension portion 45b extending from the base portion 45a toward the other side in the axial direction (the side opposite to the motor). The wheel 11 integrated with the internal gear member 33 includes: a disk portion 11b extending in the radial direction on the other side (the side opposite to the motor) in the axial direction of the outer gear 35; and a rim portion 11a extending from the disk portion 11b toward one side (motor side) in the axial direction. By adopting the above configuration, the above configuration of reducing the axial dimension can be realized, and a mechanism of relatively rotating the carrier 45 and the internal gear member 33 can be realized.

Further, according to the wheel drive device 1 of embodiment 1, the extending portion 45b of the carrier 45 has the flange portion 45f extending radially outward, and the flange portion 45f is coupled to the base portion 45 a. The flange portion 45f is arranged to overlap the tire portion 11c when viewed from the axial direction. This facilitates assembly of the

main bearings

51A and 51B and assembly of the carrier 45. Further, the axial dimension of the wheel drive device 1 can be reduced as compared with the case where the flange portion 45f extends radially inward.

(embodiment 2)

Fig. 4 is a cross-sectional view showing a wheel driving device 101 according to embodiment 2 of the present invention.

The wheel driving device 101 according to embodiment 2 is attached to, for example, a main body of an unmanned aerial vehicle, and constitutes a wheel with a motor of the unmanned aerial vehicle. The wheel driving device 101 includes wheels 111, a motor 121, and a speed reduction mechanism 131.

The wheel 111 has a tire portion 111c provided on an outer peripheral portion, a rim portion 111a on which the tire portion 111c is mounted, and a wheel portion 111b that supports the rim portion 111 a. The tire portion 111c has elasticity, and the thickness thereof becomes smaller with use. The wheel disk portion 111b is provided extending in the radial direction on the side of the apparatus opposite to the motor and is coupled to the reduction mechanism 131. The rim portion 111a has a cylindrical shape, and extends from the outer peripheral portion of the rim portion 111b toward the motor side in the axial direction.

The motor 121 includes a motor shaft 123 that rotates about a rotation axis O1, a rotor (not shown), a stator, a brake, and a housing 125, and the motor shaft 123 is driven to rotate by the motor 121 using electric power. The housing 125 is provided with a screw hole 125a connected to the main body of the unmanned transport device. The screw hole 125a is provided in a flange 125f extending radially outward from a part of the housing 125.

The reduction mechanism 131 is an eccentric oscillating type reduction gear, and includes an internal gear member 133, an external gear 135, an eccentric body 137, an eccentric body bearing 141, an inner pin 143, a carrier 145, a cover 149, a main bearing 151A, a main bearing 151B, an input bearing 153, and a balance weight 155.

The motor shaft 123, the eccentric body 137, the eccentric body bearing 141, the external gear 135, the inner pin 143, and the balance weight 155 have the same configurations as those of the motor shaft 23, the eccentric body 37, the eccentric body bearing 41, the external gear 35, the inner pin 43, and the balance weight 55 of embodiment 1. The inner pin holes 135a of the external gear 135 correspond to the inner pin holes 35a of embodiment 1.

The internal gear member 133 has the same configurations of the internal gear main body 133a and the plurality of outer pins 133b as those of the internal gear main body 33a and the outer pins 33b according to embodiment 1. The internal gear member 133 has holding

members

133c, 133d that hold the plurality of outer pins 133 b. The holding member 133c is coupled to the housing 125 of the motor 121 by a bolt or the like, whereby the internal gear member 133 is fixed.

The carrier 145 is disposed on one side (opposite side to the motor) in the axial direction of the outer gear 135, and holds a plurality of inner pins 143. The wheel carrier 145 has: a 1 st radially extending portion 145a extending radially outward from the portion holding the inner pin 143; and a 1 st axially extending portion 145b extending from the 1 st radially extending portion 145a toward the other side (motor side) in the axial direction. The 1 st radially extending portion 145a and the 1 st axially extending portion 145b are formed as separate members from each other, and are joined together by bolts or the like. The 1 st axially extending portion 145b is disposed radially outward of the internal gear member 133. The carrier 145 is, for example, configured such that a part of the 1 st radially extending portion 145a is coupled to the disc portion 111b of the wheel 111, and rotates integrally with the wheel 111. The 1 st axially extending portion 145b corresponds to an example of the extending portion according to the present invention.

The

main bearings

151A and 151B are tapered roller bearings, for example, and are disposed between the 1 st axially extending portion 145B of the carrier 145 and the internal gear member 133. Thus, the carrier 145 is supported rotatably about the rotation axis O1 with respect to the internal gear 133.

The input bearing 153 rotatably supports the motor shaft 123 on a side in the axial direction (a side opposite to the motor) of the external gear 135. The input bearing 153 is disposed between the cover 149 and the motor shaft 123. The cover 149 covers the motor shaft 123 and the side of the input bearing 153 opposite to the motor, and is coupled to the carrier 145 by bolts or the like.

< deceleration action >

When motor shaft 123 is rotated by driving of motor 121, eccentric member 137 is rotated to eccentrically oscillate external gear 135. As the eccentric body 137 rotates, the balance weight 155 rotates, and a load in the opposite direction to the load generated by the eccentric oscillation of the external gear 135 is generated, thereby maintaining the rotational balance inside the speed reduction mechanism 131. When the external gear 135 eccentrically oscillates, the meshing position between the external teeth of the external gear 135 and the internal teeth of the internal gear member 133 changes in the circumferential direction. Since the internal gear 133 is fixed to the housing 125 of the motor 121, the external gear 135 rotates (rotates) by the number of teeth difference (for example, 1 tooth) between the internal gear of the internal gear 133 and the external gear 135 per 1 rotation of the eccentric body 137.

The rotation component of the external gear 135 is output to the carrier 145 via the inner pin 143. As a result, the rotational movement of the motor 121 is reduced in speed by 1/(the number of teeth of the external gear 135) and output to the carrier 145, thereby rotating the wheel 111 integrated with the carrier 145. The unmanned transport apparatus travels on the traveling surface G0 by the rotation of the wheels 111.

< extended structure of wheel frame >

As described above, the carrier 145 has the 1 st radially extending portion 145a and the 1 st axially extending portion 145 b. By adopting this structure, the following structure can be realized: the carrier 145 holds the inner pin 143 inside the internal gear member 133, and the other part of the carrier (the 1 st axially extending portion 145b) is disposed radially outside the internal gear member 133.

According to the extension structure of the carrier 145, the

main bearings

151A and 151B can be disposed between the internal gear 133 and the 1 st axial extension 145B of the carrier 145. The outer pins 133B of the internal gear member 133, the

main bearings

151A and 151B, the 1 st axially extending portion 145B of the carrier 145, and the outer peripheral portion of the wheel 111 can be arranged in this order in the radial direction.

In this way, since the

main bearings

151A and 151B and the wheel 111 can be disposed radially outward of the outer pin 133B of the internal gear 133, the

main bearings

151A and 151B can be disposed without increasing the axial dimension of the reduction mechanism 131. Although not particularly limited, as a preferable example, both ends of the

main bearings

151A and 151B in the axial direction are located more inward than both ends of the tire portion 111c in the axial direction when viewed in the radial direction. Unlike the example of fig. 4, when the input bearing is provided on the motor side of the external gear 135, the

main bearings

151A and 151B may be arranged such that both ends of the

main bearings

151A and 151B in the axial direction are located inside both ends of the two input bearings 153. The two ends of the plurality of bearings refer to: the interval portion of the plurality of bearings is also regarded as a part of the bearing, and the plurality of bearings are regarded as both ends when they are integrated.

Further, as a preferable example, although not particularly limited, the

main bearings

151A and 151B may be arranged such that at least a part of each main bearing overlaps the outer pin 133B when viewed in the radial direction. Further, as a preferable example, although not particularly limited, the two

main bearings

151A and 151B may be arranged such that at least a part of each main bearing overlaps the external gear 135 when viewed in the radial direction.

In addition, instead of the two

main bearings

151A, 151B, one main bearing (for example, a cross roller bearing or the like) may be used. In this case, as a preferable example, one main bearing may be disposed such that both ends in the axial direction of the one main bearing are located inward of both ends in the axial direction of the tire unit 111 c. Further, as a preferable example, one main bearing may be arranged such that at least a part thereof overlaps the outer pin 133b when viewed in a radial direction. As a more preferable example, one main bearing may be disposed so that at least a part thereof overlaps with the external gear 135 when viewed in a radial direction.

Further, although the configuration having one external gear 135 is shown in the example of fig. 4, a configuration in which a plurality of external gears are arranged in the axial direction may be adopted. In this case, as to whether or not the external gear overlaps the main bearing when viewed in the radial direction, it is sufficient to determine whether or not the main bearing overlaps the external gear when the plurality of external gears are regarded as one body (that is, when the interval portion of the plurality of external gears is also regarded as a part of the external gear).

< relationship between member integrated with internal gear member and wheel >

The internal gear 133 is integrally coupled to the housing 125 of the motor 121. The housing 125 is disposed such that the flange portion 125f of the outermost peripheral portion thereof overlaps the tire portion 111c of the wheel 111 when viewed in the axial direction. In this way, since the outermost peripheral portion of the housing 125 projects outward in the radial direction to the position of the tire portion 111c, the axial dimension of the housing 125 can be reduced when the volume of the housing 125 is constant as compared with a structure that is further inward in the radial direction. Further, by using such a housing 125, the axial dimension of the motor 121, and hence the axial dimension of the wheel drive device 101, can be reduced as compared with a motor that can obtain the same power.

On the other hand, in the outermost peripheral portion of the case 125 integrated with the internal gear member 133, a cutout 125k is provided in a range facing at least the traveling surface G0, in which the distance L11 from the rotation axis O1 is smaller than the outer radius L12 of the rim portion 111a of the wheel 111. The notch 125k prevents a part of the housing 125 from contacting the tread G0 even when the thickness of the tire portion 111c decreases as the wheel 111 is used. As in the case of the plurality of cutout portions 45k (see fig. 2 and 3) of the wheel carrier 45 according to embodiment 1, a plurality of cutout portions 125k may be provided at a plurality of locations in the circumferential direction.

< effects of the embodiment >

As described above, according to the wheel drive device 101 of embodiment 2, the carrier 145 has the 1 st axially extending portion 145B disposed radially outward of the internal gear 133, and the

main bearings

151A and 151B are disposed between the 1 st axially extending portion 145B and the internal gear 133. The outer peripheral portion of the wheel 111 is disposed radially outward of the 1 st axially extending portion 145 b. By adopting such an arrangement, the

main bearings

151A and 151B and the wheel 111 can be arranged so as to overlap the internal gear 133 in the radial direction, and the axial dimension of the wheel drive device 101 can be shortened.

Further, according to the wheel drive device 101 of embodiment 2, the carrier 145 has: a 1 st radially extending portion 145a extending radially on one side in the axial direction of the outer gear 135; and a 1 st axially extending portion 145b axially extending from the 1 st radially extending portion 145 a. By adopting the above configuration, the above configuration of reducing the axial dimension can be realized, and a mechanism of freely rotating the carrier 145 and the internal gear 133 relative to each other can be realized.

Further, according to the wheel drive device 101 of embodiment 2, the outermost peripheral portion of the case 125 integrated with the internal gear 133 is arranged so as to overlap the tire portion 111c of the wheel 111 as viewed in the axial direction. Therefore, the housing 125 can be made flat, and the axial dimension of the motor 121 and thus the axial dimension of the wheel drive device 101 can be reduced.

Further, according to the wheel driving device 101 of embodiment 2, the cutout 125k is provided in the outermost peripheral portion of the case 125 integrated with the internal gear 133 at a portion facing the traveling surface G0. This can prevent a part of the casing 125 from contacting the tread G0 while the tire unit 111c is being reduced. Further, since the notches 125k are provided at a plurality of positions in the circumferential direction, the degree of freedom of the attachment angle (circumferential angle) when the wheel drive device 101 is attached to the main body of the unmanned aerial vehicle can be improved, and the operability of fixing and handling the wiring of the motor 121 can be improved.

The embodiments of the present invention have been described above. However, the present invention is not limited to the above embodiments. For example, the above-described embodiment shows an example in which a center crank type eccentric oscillating speed reducer is used as the speed reducing mechanism. However, as the speed reducing mechanism of the present invention, a so-called distributed eccentric oscillating type speed reducing device or a simple planetary speed reducer may be used in which two or more eccentric body shafts having eccentric bodies are disposed at positions offset from the axial center of the speed reducing device. When a simple planetary reduction gear is used, the carrier is a component synchronized with the revolution component of the external gear. Further, although the above embodiment has shown the configuration having two main bearings and one external gear, the main bearing may be one, and may have a configuration having a plurality of external gears.

In the above embodiment, the component integrally formed of a single member may be replaced with a component that is divided into a plurality of members and connected or fixed to each other. Further, a component formed by connecting a plurality of members may be replaced with a component formed by integrating a single member. In addition, the details specifically shown in the embodiments may be appropriately changed without departing from the spirit of the present invention.

Claims

1. A wheel driving device is provided with: an internal gear member having an internal gear; an outer gear; a carrier that synchronizes with a rotation component or a revolution component of the external gear; a main bearing disposed between the internal gear member and the carrier; and a wheel that rotates integrally with the internal gear member, characterized in that,

the wheel carrier has an extension portion disposed radially outward of the internal gear member,

the main bearing is disposed between the extension portion and the internal gear member,

the outer peripheral portion of the wheel is disposed radially outward of the extension portion.

2. The wheel drive apparatus according to claim 1,

the wheel carrier is provided with: a 1 st radially extending portion that extends radially on a 1 st direction side, which is one side in an axial direction of the external gear; and a 1 st axially extending portion extending axially from the 1 st radially extending portion,

the 1 st axial extension constitutes the extension.

3. The wheel drive apparatus according to claim 2,

the wheel that rotates integrally with the internal gear member has: a 2 nd radially extending portion that extends radially on a side of the external gear opposite to the 1 st direction side; and a 2 nd axial extension portion that extends in the axial direction from the 2 nd radial extension portion and is disposed radially outward of the 1 st axial extension portion.

4. The wheel drive apparatus according to claim 2 or 3,

the 1 st axially extending portion has a flange portion extending toward a radially outer side,

the flange portion is joined to the 1 st radially extending portion.

5. The wheel drive apparatus according to claim 4,

the flange portion overlaps with a tire portion of the wheel when viewed in an axial direction.

6. The wheel drive apparatus according to claim 3,

the outer peripheral surface of the 1 st axially extending portion is inclined with respect to the axial direction in a range opposed to the inner periphery of the corner portion between the 2 nd radially extending portion and the 2 nd axially extending portion.

7. The wheel drive apparatus according to any one of claims 1 to 6,

the distance from the center axis of rotation of at least a portion of the outermost periphery of the wheel carrier facing the wheel tread surface is smaller than the outer radius of the rim portion of the wheel.

8. The wheel drive apparatus according to claim 7,

the outermost peripheral portion of the wheel frame has a plurality of locations in the circumferential direction from the center axis of rotation smaller than the outer radius of the rim portion.

9. A wheel driving device is provided with: an internal gear member having an internal gear; an outer gear; a carrier that synchronizes with a rotation component or a revolution component of the external gear; a main bearing disposed between the internal gear member and the carrier; and a wheel that rotates integrally with the wheel carrier, the wheel driving device being characterized in that,

10. The wheel drive apparatus according to claim 9,

the wheel carrier is provided with: a 1 st radially extending portion that extends radially on a 1 st direction side, which is one side in an axial direction of the external gear; and a 1 st axially extending portion extending axially from the 1 st radially extending portion and disposed radially outward of the internal gear member,

the 1 st axial extension constitutes the extension.

11. The wheel drive apparatus according to claim 9 or 10,

the outermost peripheral portion of the internal gear member or the member integrated with the internal gear member overlaps with a tire portion of the wheel as viewed in the axial direction.

12. The wheel drive apparatus according to claim 11,

at least a portion of an outermost peripheral portion of the internal gear or a member integrated with the internal gear, which portion faces a wheel tread surface, is located at a distance from a rotation center axis of the internal gear, which is smaller than an outer radius of a rim portion of the wheel.

13. The wheel drive apparatus according to claim 12,

at a plurality of locations in a circumferential direction of an outermost peripheral portion of the internal gear or a member integrated with the internal gear, distances from a rotation center axis of the internal gear are smaller than an outer radius of a rim portion of the wheel.