Speed reducer and traveling vehicle

Abstract

The invention provides a speed reducer and a traveling vehicle. The speed reducer is provided with a shaft, a cylindrical shell, a stator, a rotor, a sun gear, a planetary gear, a planetary shaft and a wheel carrier. The housing is fixed to the shaft and extends in the axial direction. The stator is fixed to the housing. The planetary gear meshes with the sun gear from the outside in the radial direction and can rotate around the rotation axis. The carrier is disposed above the planetary gear and supports the planetary shaft. The housing has an internally toothed gear engaged from the outside in the radial direction of the planetary gear. The wheel carrier is provided with a first area expanding in the radial direction and a cylindrical second area extending downwards from the radial inner end of the first area. A part of the second region is supported by the shaft via a bearing on the inside of the sun gear in the radial direction.

Description

Technical Field

[0001] The invention relates to a speed reducer and a traveling vehicle. Background Art

[0002] In the past, there are known compact vehicles such as scooters for the elderly and three-wheeled electric vehicles that travel at a medium speed of about 10 km to 30 km per hour. Such devices are equipped with a motor and a reducer for driving tires, and the reducer is used to reduce the rotational motion obtained from the motor so that the tires rotate at the reduced speed. For example, such a vehicle is disclosed in Japanese Patent Publication No. 2015-110382.

[0003] Patent Document 1: Japanese Patent Application Publication No. 2015-110382

[0004] The wheel drive device of the above-mentioned publication has a motor and a reducer that reduces the rotation of the motor, and drives a wheel formed by mounting a tire on the outer periphery of the internal gear of the reducer. The reducer has: a sun gear that is coaxially arranged with the rotation axis of the motor; a plurality of planetary gears that mesh with the sun gear and are arranged at intervals in the circumferential direction; a wheel carrier that supports each planetary gear so that it can rotate around the center of each planetary gear; and the above-mentioned internal gear that meshes with each planetary gear. In addition, the internal gear is supported by a rolling bearing so that it can rotate relative to the wheel carrier on the same axis as the rotation axis of the motor. In addition, the wheel carrier is fixed to the motor housing with bolts.

[0005] Therefore, in the wheel drive device of the above-mentioned publication, the load applied to the wheel frame or the wheel during driving acts on the motor housing. Therefore, the strength of the motor housing must be further improved, and it is difficult to achieve thinning and lightening. In addition, the motor and the reducer may be enlarged and cannot be arranged on the inner side of the wheel, which does not meet the product requirements. Summary of the invention

[0006] An object of the present invention is to provide a technology capable of achieving a reduction in thickness and weight of the entire speed reducer including a motor case by studying components and structures on which a load applied to a wheel carrier and a wheel during driving acts.

[0007] An exemplary embodiment of the present application is a speed reducer, which has a shaft, a cylindrical housing, a stator, a rotor, a sun gear, a planetary gear, a planetary shaft and a wheel carrier. The shaft is arranged along a central axis, and the central axis extends up and down. The housing is fixed to the shaft and extends in the axial direction. The stator is fixed to the housing. The rotor can rotate around the central axis relative to the stator. The sun gear can rotate around the central axis together with the rotor. The planetary gear meshes with the sun gear from the radial outside and can rotate around the rotation axis parallel to the central axis. The planetary shaft axially supports the planetary gear. The wheel carrier is arranged at a position above the planetary gear and supports the planetary shaft. The housing has an internal gear meshing from the radial outside of the planetary gear. The wheel carrier has a first region extending in the radial direction and a cylindrical second region extending downward from the radial inner end of the first region. At least a part of the second region is supported on the shaft via a bearing at a position radially inward than the sun gear.

[0008] According to an exemplary embodiment of the present application, the wheel carrier is supported by a shaft via a bearing, so that the load applied to the wheel carrier during driving can be suppressed from acting on the housing. As a result, the housing can be made thinner and lighter. In addition, by arranging the lower portion of the wheel carrier radially inward of the sun gear, the axial length of the entire reducer can be further suppressed compared to the case where the entire wheel carrier is adjacent to the upper side of the sun gear.

[0009] The above and other features, elements, steps, characteristics and advantages of the present invention will be more clearly understood from the following detailed description of the preferred embodiments of the present invention with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 It is a longitudinal section view of a moving vehicle.

[0011] Figure 2 It is a partial longitudinal section view of a moving vehicle.

[0012] Figure 3 It is a cross-sectional view of the reducer. DETAILED DESCRIPTION

[0013] Hereinafter, an exemplary embodiment of the present application will be described with reference to the accompanying drawings. In addition, in the present application, the direction parallel to the central axis extending up and down of the reducer and the traveling vehicle of the present invention is referred to as the "axial direction", the direction perpendicular to the central axis is referred to as the "radial direction", and the direction along the arc centered on the central axis is referred to as the "circumferential direction". In addition, in the following description, Figures 1 to 3 In the example, the radial direction is represented by r1. Figure 3 In the diagram, the “circumferential direction” is represented by “c1”.

[0014] In the present application, the direction of the central axis of the speed reducer and the traveling vehicle and the direction of the rotation axis of the planetary gear described later are defined as the vertical direction. Figure 1 and Figure 2 The right side is set as "upper" and the left side is set as "lower", and the shape and position relationship of each part are explained. Figure 1 and Figure 2 In the specification, "above" is represented as "a1" and "below" is represented as "a2". However, this definition is not intended to limit the orientation of the reducer and the traveling vehicle of the present invention during manufacture and use. In addition, in the present application, the "parallel direction" is not limited to the situation that is strictly parallel in geometry. That is, a direction that is roughly parallel to a certain direction can be used as long as it is roughly parallel to the extent that the effect of the invention is achieved. In addition, in the present application, the "vertical direction" is not limited to the situation that is strictly perpendicular in geometry. That is, a direction that is roughly perpendicular to a certain direction can be used as long as it is roughly perpendicular to the extent that the effect of the invention is achieved.

[0015] <1. Structure of the speed reducer and the traveling vehicle>

[0016] Hereinafter, the structure of the traveling vehicle 100 including the speed reducer 1 according to one embodiment of the present invention will be described. Figure 1 It is a longitudinal sectional view of the traveling vehicle 100 . Figure 2 It is a partial longitudinal sectional view of the traveling vehicle 100 . Figure 3 is from Figure 1 The cross-sectional view of the reducer 1 when viewed from the AA position. In addition, in order to avoid the complexity of the figure, Figure 1 to Figure 3 In the figure, some hatching lines indicating cross sections are omitted. Figure 3 In FIG. 1 , internal teeth 54 of the housing 5 , external teeth 71 of the sun gear 7 , and external teeth 811 of the planetary gear 81 , which will be described later, are shown by two-dot chain lines.

[0017] The traveling vehicle 100 of the present invention is used as a compact mobile vehicle that travels at a medium speed of about 10 km to 30 km per hour, such as a scooter for the elderly, an electric step board, or a three-wheeled electric vehicle. The traveling vehicle 100 has a reducer 1, a tire support portion 2, and a tire 3. In addition, the traveling vehicle 100 uses the reducer 1 to reduce the rotational motion obtained from the drive motor 6 while transmitting it to the wheel frame 11 and the tire support portion 2 described later, and moves by rotating the tire 3. In addition, in the present embodiment, the drive motor 6 is included in the reducer 1. However, the drive motor 6 can also be provided separately from the reducer 1.

[0018] The reducer 1 and the traveling vehicle 100 are arranged along a central axis 90 extending vertically. In addition, the reducer 1 has a shaft 4, a housing 5, a stator 61 and a rotor 62 included in a driving motor 6, a sun gear 7, a planetary gear 81 and a planetary shaft 82 included in a planetary gear device 8, a wheel carrier 11, a partition plate portion 55, and bearings 41, 57, 58.

[0019] The shaft 4 is arranged along the central axis 90. The shaft 4 is fixed to a frame provided on the traveling vehicle 100 in a non-rotatable manner, for example. In addition, a cavity 40 is provided inside the shaft 4. The cavity 40 opens near the position where the drive motor 6 is arranged when the reducer 1 is assembled. Figure 2 As shown, external threads 431, 432 are formed on the outer circumferential surface of the shaft 4. The external threads 431, 432 are arranged to be separated from each other in the axial direction.

[0020] The housing 5 is fixed to the shaft 4 and is a cylindrical member extending in the axial direction. The housing 5 is manufactured, for example, by stamping an iron plate. The housing 5 holds the stator 61. In addition, the housing 5 supports the rotor 62 and the sun gear 7 through bearings 57 and 58. The housing 5 has a cylindrical portion 51, a bottom plate portion 52, and a boss portion 53.

[0021] The cylindrical portion 51 is a portion extending in a cylindrical shape around the central axis 90 substantially coaxially with the central axis 90. Figure 1 and Figure 2 As shown, the tubular portion 51 includes a first tubular portion 511 , a connecting portion 512 , and a second tubular portion 513 .

[0022] The first cylindrical portion 511 is a portion extending in a cylindrical shape in the axial direction at the uppermost position of the cylindrical portion 51. An internal gear 514 composed of a plurality of internal teeth 54 is formed on the inner circumferential surface of a portion of the first cylindrical portion 511 slightly below the upper end. The plurality of internal teeth 54 protrude radially inward, respectively. In addition, the plurality of internal teeth 54 are arranged at a constant pitch along the circumferential direction. The housing 5 and the internal gear 514 of the present embodiment are formed by one component. Thus, the number of components of the entire reducer 1 including the housing 5 and the internal gear 514 can be reduced. However, the housing 5 and the internal gear 514 may also be formed by different components.

[0023] The connecting portion 512 is a portion extending radially outward from the lower end of the first cylindrical portion 511. The second cylindrical portion 513 is a portion extending downward from the radially outer end of the connecting portion 512. The second cylindrical portion 513 extends in a cylindrical shape in the axial direction at the lowest position of the cylindrical portion 51. The stator 61 is fixed to the inner circumferential surface of the second cylindrical portion 513.

[0024] The bottom plate portion 52 is a portion extending radially inward from the lower end of the second cylindrical portion 513. The bottom plate portion 52 extends in a circular plate shape centered on the central axis 90. The bottom plate portion 52 forms the lower end of the housing 5. In addition, a through hole 520 is provided in the bottom plate portion 52. The through hole 520 penetrates the bottom plate portion 52 in the axial direction near the position where the stator 61 is arranged.

[0025] The boss portion 53 is a portion extending upward from the radially inner end portion of the bottom plate portion 52. The boss portion 53 extends in a cylindrical shape substantially coaxially with the center axis 90 at a position slightly radially outward of the shaft 4. The shaft 4 is fixed to the radially inner side of the boss portion 53 by, for example, press-fitting. In addition, the inner circumferential surface of the boss portion 53 is fixed to the outer circumferential surface of the shaft 4 in a manner that is non-rotatable relative to each other, for example, using a key 45 extending in the axial direction. However, the shaft 4 may be fixed to the boss portion 53 in a manner that is non-rotatable relative to each other, using other methods such as bonding.

[0026] A cavity 530 is provided inside the boss portion 53. The cavity 530 opens near the location where the drive motor 6 is disposed and communicates with the opening of the cavity 40 of the shaft 4 when the speed reducer 1 is assembled.

[0027] In addition, if Figure 2 As shown, a partition plate portion 55 is fixed by threaded fastening or the like at a position adjacent to the connecting portion 512 and radially inward of the second cylindrical portion 513 below the connecting portion 512. The partition plate portion 55 is a component that extends in the shape of an annular plate centered on the central axis 90 radially inward of the second cylindrical portion 513 and radially outward of the sun gear 7. That is, the partition plate portion 55 extends radially inward from the inner circumferential surface of the outer shell 5. However, the partition plate portion 55 may also be formed by one component together with the outer shell 5.

[0028] The drive motor 6 has a stator 61 and a rotor 62. As described above, the stator 61 is fixed to the housing 5. The stator 61 is the stator of the drive motor 6. The stator 61 has a stator core 611 and a plurality of coils 612. The stator core 611 is formed of a magnetic body such as laminated steel plates. The stator core 611 has a plurality of teeth protruding radially inward. The plurality of teeth are arranged at equal intervals in the circumferential direction. The coil 612 is composed of a conductive wire wound around the teeth. The conductive wire 613 led out from the coil 612 is wired while passing through the cavity 530 provided inside the above-mentioned boss portion 53 and the cavity 40 provided inside the shaft 4 or the through hole 520 of the housing 5. Thus, the conductive wire 613 led out from the coil 612 can be led out to the outside of the reducer 1 and connected to a power supply device or the like.

[0029] The rotor 62 is the rotor of the drive motor 6. The rotor 62 extends in a cylindrical shape radially inwardly of the stator 61 and approximately coaxially with the center axis 90. That is, the drive motor 6 of the present embodiment is an inner rotor type motor. In addition, the rotor 62 has a magnet serving as a permanent magnet. The magnet is arranged in a circular ring shape centered on the center axis 90 in a manner that the N pole and the S pole are alternately arranged in the circumferential direction. The radially inner end face of the teeth of the stator 61 and the radially outer end face of the magnet are radially opposed to each other with a small gap therebetween. However, the drive motor 6 may also be an outer rotor type motor in which the rotor 62 is arranged radially outwardly of the stator 61. In addition, the drive motor 6 may also be an induction motor.

[0030] As described in detail later, the rotor 62 is fixed to the sun gear 7. The sun gear 7 is supported by the housing 5 via bearings 57 and 58 so as to be rotatable about the central axis 90. Thus, the rotor 62 is rotatable about the central axis 90 together with the sun gear 7.

[0031] When the drive motor 6 is driven, a drive current is supplied to the plurality of coils 612 of the stator 61 via the conductive wire 613. As a result, a rotating magnetic field is generated in the stator core 611. Furthermore, due to the magnetic attraction and repulsion between the stator core 611 and the plurality of magnets of the rotor 62, a circumferential torque is generated between the stator 61 and the rotor 62. As a result, the rotor 62 rotates at the input speed N1, which is the speed before deceleration, with the center axis 90 as the center.

[0032] The sun gear 7 is a gear arranged substantially coaxially with the central axis 90. The sun gear 7 is fixed to the radially inner end surface of the rotor 62 in a manner that the sun gear 7 cannot rotate relative to the rotor 62. Figure 2 and Figure 3 As shown, a plurality of external teeth 71 are formed on the outer surface near the upper end of the sun gear 7. The plurality of external teeth 71 are arranged above the rotor 62. The plurality of external teeth 71 protrude radially outward. In addition, the plurality of external teeth 71 are arranged at a constant pitch along the circumferential direction.

[0033] In addition, a bearing 57 is sandwiched between the radial inner end of the partition plate portion 55 and the radial outer peripheral surface of the sun gear 7. The bearing 57 is equivalent to the "third bearing" in the present invention. A ball bearing is used for the bearing 57, for example. The inner ring of the bearing 57 is fixed to the outer peripheral surface of the sun gear 7 slightly below the plurality of external teeth 71. The outer ring of the bearing 57 is fixed to the radial inner end of the partition plate portion 55. A plurality of balls are sandwiched between the inner ring and the outer ring of the bearing 57. Thus, the sun gear 7 is supported on the partition plate portion 55 together with the rotor 62 via the bearing 57 in a manner that allows rotation around the center axis 90. However, other types of bearings may also be used for the bearing 57.

[0034] By configuring the partition plate portion 55 and the bearing 57, the space on the drive motor 6 side and the space on the planetary gear device 8 side inside the housing 5 can be separated. That is, by configuring the partition plate portion 55 and the bearing 57, the space below the partition plate portion 55 where grease is not applied and the space above the partition plate portion 55 where grease is applied can be separated. In addition, the bearing 57 has a seal between the outer circumferential surface of the inner ring and the inner circumferential surface of the outer ring. Thus, the space without grease and the space with grease can be completely separated.

[0035] In addition, a bearing 58 is sandwiched between the outer circumferential surface of the boss portion 53 and the inner circumferential surface of the sun gear 7 in the radial direction. A ball bearing is used as the bearing 58, for example. The inner ring of the bearing 58 is fixed to the outer circumferential surface of the boss portion 53. The outer ring of the bearing 58 is fixed to the inner circumferential surface near the lower end of the sun gear 7. A plurality of balls are sandwiched between the inner ring and the outer ring of the bearing 58. Thus, the sun gear 7 is supported on the boss portion 53 together with the rotor 62 via the bearing 58 in a manner that allows rotation around the center axis 90. However, other types of bearings may also be used for the bearing 58.

[0036] Thus, in the present embodiment, when the rotor 62 rotates about the central axis 90, the sun gear 7 can be rotated about the central axis 90 while being stably supported and fixed to the rotor 62 via the bearings 57 and 58. However, in the speed reducer 1, only one of the bearings 57 and 58 may be provided.

[0037] The planetary gear device 8 is a device that converts the rotational motion of the input speed N1 into the rotational motion of the output speed N2 which is slower than the input speed N1. Figure 1 to Figure 3 As shown, the planetary gear device 8 has one or more planetary gears 81, one or more planetary shafts 82, and one or more bearings 83. In the present embodiment, the planetary gear device 8 has five planetary gears 81, five planetary shafts 82, and five bearings 83.

[0038] The planetary gear 81 is arranged around the upper end of the sun gear 7. Figure 3 As shown, in the present embodiment, five planetary gears 81 are arranged at equal intervals around the sun gear 7. However, the number of planetary gears 81 possessed by the reducer 1 may be 1 to 4, or may be 6 or more. In addition, the five planetary gears 81 are respectively arranged along the axis of rotation 91. The axis of rotation 91 is substantially parallel to the center axis 90. Each planetary gear 81 has a plurality of external teeth 811 on the outer side surface. In addition, the plurality of external teeth 811 protrude outward, respectively. In addition, the plurality of external teeth 811 are arranged at a constant pitch.

[0039] In addition, the multiple external teeth 811 of each planetary gear 81 mesh with the external teeth 71 of the sun gear 7 from the radial outside. That is, the planetary gear 81 meshes with the sun gear 7 from the radial outside. Therefore, when the sun gear 7 rotates around the central axis 90, each planetary gear 81 receives power from the sun gear 7 and rotates around the rotation axis 91 in the direction opposite to the rotation direction of the sun gear 7. That is, each planetary gear 81 can rotate around the rotation axis 91 parallel to the central axis 90 as the sun gear 7 rotates. In addition, each planetary gear 81 has a through hole 810. Each through hole 810 penetrates each planetary gear 81 along the rotation axis 91.

[0040] Here, as described above, an internal gear 514 is formed on the inner circumferential surface of the first cylindrical portion 511 of the housing 5 at a position slightly below the upper end. The internal gear 514 is annular centered on the central axis 90. In addition, the internal gear 514 has a plurality of internal teeth 54. The plurality of internal teeth 54 mesh with the external teeth 811 of each of the five planetary gears 81 from the radial outside. That is, the housing 5 has the internal gear 514 meshed from the radial outside of each planetary gear 81.

[0041] The planetary shaft 82 is a component extending in a columnar shape along the rotation axis 91. The planetary gear device 8 of this embodiment has five planetary shafts 82. Each planetary shaft 82 is inserted into the through hole 810 of one planetary gear 81 along the direction of the rotation axis 91. Moreover, each planetary shaft 82 axially supports one planetary gear 81. In addition, a bearing 83 is inserted between each planetary shaft 82 and each planetary gear 81. For example, a needle bearing is used for the bearing 83. Thus, each planetary gear 81 is supported on one planetary shaft 82 in a manner that it can rotate around the rotation axis 91.

[0042] A portion of the wheel carrier 11 is disposed above the five planetary gears 81, and the wheel carrier 11 is a component that supports the five planetary shafts 82. That is, the wheel carrier 11 is disposed above the planetary gears 81 and supports the planetary shafts 82. More specifically, Figure 2 As shown, the wheel carrier 11 has a plurality of recesses 110. In the present embodiment, the wheel carrier 11 has five recesses 110. The five recesses 110 are arranged at equal intervals in the circumferential direction. In addition, the five recesses 110 are respectively recessed upward. The upper end portion of a planetary shaft 82 is inserted into each recess 110, and is fixed to each recess 110 in a non-rotatable manner, for example, by being pressed into the planetary shaft 82. However, the planetary shaft 82 may also be fixed to each recess 110 by bonding, threaded fastening, or the like.

[0043] In addition, the wheel carrier 11 has a first region 111 and a second region 112. The first region 111 and the second region 112 are formed by one component. In addition, the axial width of the first region 111 is larger than the plate thickness of the housing 5. The first region 111 is a portion that extends in a circular ring shape with the center axis 90 as the center on the radial outside of the shaft 4. That is, the first region 111 extends radially. The first region 111 forms the upper end of the wheel carrier 11. In addition, the recess 110 for fixing the above-mentioned planetary shaft 82 is provided on the lower surface of the first region 111. The second region 112 is a tubular portion that extends downward from the radial inner end of the first region 111. The second region 112 extends in a tubular shape approximately coaxially with the center axis 90 on the radial inside of the sun gear 7.

[0044] In addition, in the present embodiment, the lower end of the second region 112 is arranged at a position lower than each planetary gear 81. In addition, the lower end of the second region 112 is arranged at a position lower than the upper end of the stator 61 of the drive motor 6. In this way, the space radially inward of the sun gear 7 in the reducer 1 is effectively utilized, the second region 112 is arranged in the space, and the entire wheel carrier 11 including the second region 112 is further arranged below, thereby further suppressing the axial length of the entire reducer 1 including the wheel carrier 11 compared to the case where the entire wheel carrier 11 is adjacent to the upper side of the sun gear 7.

[0045] In addition, a bearing 41 is inserted between the outer circumferential surface of the shaft 4 and the inner circumferential surface of the second region 112 in the radial direction. The bearing 41 includes a first bearing 411 and a second bearing 412. The first bearing 411 and the second bearing 412 use, for example, a pair of radial thrust ball bearings. Moreover, the pair of first bearings 411 and the second bearings 412 are arranged in opposite directions with a gap therebetween in the axial direction. The first bearing 411 supports the upper end of the second region 112 of the wheel carrier 11. The second bearing 412 supports the lower end of the second region 112 of the wheel carrier 11.

[0046] More specifically, the inner ring of the first bearing 411 and the inner ring of the second bearing 412 are respectively fixed to the outer peripheral surface of the shaft 4. The outer ring of the first bearing 411 and the outer ring of the second bearing 412 are respectively fixed to the inner peripheral surface of the second region 112. A plurality of balls are sandwiched between the inner ring and the outer ring of each of the first bearing 411 and the second bearing 412. Thus, the wheel carrier 11 including the second region 112 is supported on the shaft 4 together with the planetary gear device 8 via the first bearing 411 and the second bearing 412 in a manner that allows rotation around the central axis 90. That is, in the present embodiment, at least a portion of the second region 112 is supported on the shaft 4 via the bearing 41 at a position radially inward of the sun gear 7. In addition, the inner ring of the second bearing 412 is adjacent to the upper side of the boss portion 53.

[0047] In addition, in this embodiment, the load applied to the wheel carrier 11 including the second region 112 when the reducer 1 and the traveling vehicle 100 are driven can be supported via the two bearings 411 and 412. As a result, the loads acting on the reducer 1 and the driving motor 6 can be suppressed, thereby suppressing the occurrence of adverse conditions caused by excessive loads applied thereto.

[0048] In addition, in the present embodiment, the second bearing 412 is arranged below each planetary gear 81. In this way, the space in the reducer 1 that is radially inward of the sun gear 7 is effectively utilized, the second region 112 is arranged in the space, and the second bearing 412 that supports the lower end of the second region 112 is arranged, thereby further suppressing the axial length of the entire reducer 1 including the wheel carrier 11.

[0049] Here, if Figure 2 As shown, external threads 431 and 432 are formed on the outer peripheral surface of the shaft 4. More specifically, the external thread 431 is formed on the outer peripheral surface of the shaft 4 just above the position where the inner ring of the first bearing 411 is fixed. In addition, the external thread 432 is formed on the outer peripheral surface of the shaft 4 just below the position where the boss portion 53 of the housing 5 is fixed.

[0050] In addition, nuts 46 and 47 are respectively arranged around the positions where the external threads 431 and 432 of the shaft 4 are formed. The nut 46 is a component that extends in a circular ring shape around the shaft 4 with the central axis 90 as the center. The nut 46 is located above the first bearing 411. In addition, the nut 46 has an inner diameter that is substantially the same as the outer diameter of the shaft 4. An internal thread 461 is formed on the inner peripheral surface of the nut 46. Moreover, the external thread 431 of the shaft 4 is screwed with the internal thread 461 of the nut 46. Thus, the axial position of the nut 46 relative to the shaft 4 can be adjusted. Furthermore, by the axial contact between the nut 46 and the inner ring of the first bearing 411, the axial position of the first bearing 411 relative to the shaft 4 can be adjusted.

[0051] In addition, the nut 47 is a component that extends in a circular ring shape around the shaft 4 with the central axis 90 as the center. The nut 47 is located below the boss portion 53 of the housing 5. In addition, the nut 47 has an inner diameter that is substantially the same as the outer diameter of the shaft 4. An internal thread 471 is formed on the inner peripheral surface of the nut 47. Moreover, the external thread 432 of the shaft 4 is screwed with the internal thread 471 of the nut 47. Thus, the axial position of the nut 47 relative to the shaft 4 can be adjusted. Furthermore, by the axial contact between the nut 47 and the boss portion 53, the axial position of the second bearing 412 adjacent to the upper side of the boss portion 53 relative to the shaft 4 can be adjusted.

[0052] In addition, as described above, a pair of radial thrust ball bearings are used for the first bearing 411 and the second bearing 412. Moreover, the pair of first bearings 411 and the second bearing 412 are arranged opposite to each other in the axial direction. Moreover, in the present embodiment, by adjusting the axial positions of the bearings 411 and 412 using nuts 46 and 47, the axial positions of the wheel carrier 11, the planetary gear device 8, and the housing 5 relative to the shaft 4 can be adjusted. In addition, by using nuts 46 and 47, the displacement and falling off of the bearings 411 and 412, the key 45 inserted into the boss portion 53, and the housing 5 fixed using the key 45 can be suppressed.

[0053] In addition, a bearing 115 is inserted between the outer peripheral surface of the first region 111 and the inner peripheral surface of the cylindrical portion 51 of the housing 5 in the radial direction. A ball bearing is used as the bearing 115, for example. The inner ring of the bearing 115 is fixed to the outer peripheral surface of the first region 111. The outer ring of the bearing 115 is fixed to the inner peripheral surface near the upper end of the first cylindrical portion 511 of the housing 5. A plurality of balls are sandwiched between the inner ring and the outer ring of the bearing 115. Thus, the wheel carrier 11 including the first region 111 supports the housing 5 via the bearing 115 in a manner that allows relative rotation around the central axis 90. In this way, by providing the bearing 115, the housing 5 is more stably supported by the boss portion 53 and the bearing 115. However, other types of bearings may be used for the bearing 115. In addition, it is not necessary to provide the bearing 115. In addition, an oil seal may be arranged at the position of the bearing 115.

[0054] As described above, when the drive motor 6 is driven, the sun gear 7 rotates at the input speed N1 together with the rotor 62 of the drive motor 6 about the central axis 90. Then, the five planetary gears 81 meshing with the sun gear 7 from the radial outside respectively rotate about the rotation axis 91. In addition, the five planetary gears 81 respectively rotate about the rotation axis 91 while meshing with the internal gear 514 of the housing 5, thereby revolving together with the planetary shafts 82 about the central axis 90 at the output speed N2. As a result, the wheel carrier 11 to which the five planetary shafts 82 are fixed rotates about the central axis 90 at the reduced output speed N2. That is, the reducer 1 converts the rotation of the sun gear 7 at the high speed input speed N1 into the revolution about the central axis 90 of the planetary gears 81, and outputs the revolution from the wheel carrier 11, thereby being able to output the rotation at the reduced output speed N2.

[0055] Here, as described above, the wheel carrier 11 of this embodiment is not fixed to the housing 5, but supported by the shaft 4 via the bearings 411 and 412. Therefore, when the reducer 1 and the traveling vehicle 100 are driven, the load (including the transmission torque after deceleration) applied to the wheel carrier 11 and the tire 3 described later can be suppressed from acting on the housing 5. As a result, the required value required as the strength of the housing 5 can be suppressed, and the housing 5 can be made thinner. Therefore, as Figure 1 and Figure 2 As shown, the housing 5 of this embodiment has a plate thickness smaller than the axial width of the first region 111 of the carrier 11. As a result, the entire speed reducer 1 including the housing 5 can be further reduced in weight, and the manufacturing cost can be reduced.

[0056] Furthermore, a plurality of spokes 21 are connected to the radially outer end of the first region 111 of the wheel carrier 11. Each spoke 21 is a columnar portion that radially extends outward from the shaft 4 with the central axis 90 as the center. Furthermore, the tire support portion 2 is arranged in such a manner that the radially outer ends of the plurality of spokes 21 are connected in the circumferential direction.

[0057] The tire support portion 2 is a member extending in a cylindrical shape substantially coaxially with the central axis 90 at a position radially outward from the cylindrical portion 51 of the housing 5. The radially outer surface of the tire support portion 2 extends in a cylindrical shape substantially coaxially with the central axis 90. In addition, a tire 3 is fixed to the radially outer surface of the tire support portion 2.

[0058] The radially outer ends of the plurality of spokes 21 are fixed to the upper end of the tire support portion 2. In addition, the plurality of spokes 21 are respectively connected to the first region 111 of the wheel frame 11. That is, the upper end of the tire support portion 2 is fixed to the wheel frame 11 via the plurality of spokes 21. As a result, the air permeability in the direction of the center axis 90 is improved, and the cooling effect of the reducer 1 and the drive motor 6 is improved.

[0059] In addition, in the present embodiment, the position of the lower end of the housing 5 is arranged at a position higher than the position of the lower end of the tire support portion 2. In addition, as described above, the first region 111 of the wheel frame 11 forms the upper end of the wheel frame 11. That is, in the present embodiment, when the reducer 1 is mounted on the traveling vehicle 100, the entire reducer 1 including the housing 5 and the wheel frame 11 becomes a structure arranged radially inward of the tire support portion 2. Thereby, the axial thinning of the entire traveling vehicle 100 including the reducer 1 can be achieved. However, in the traveling vehicle 100, the entire reducer 1 does not have to be arranged completely at a position higher than the position of the lower end of the tire support portion 2, and may be slightly extended downward than the position of the lower end of the tire support portion 2 within a range that meets product requirements.

[0060] In addition, in the present embodiment, before the reducer 1 is mounted on the traveling vehicle 100, no components such as a wheel drive device are provided at the lower portion of the traveling vehicle 100, and the traveling vehicle 100 is provided with a structure open downward. Therefore, when the various components of the reducer 1 are mounted on the traveling vehicle 100, the workability when performing maintenance on them is improved.

[0061] <2. Modifications>

[0062] Although exemplary embodiments of the present invention have been described above, the present invention is not limited to the above embodiments. Some of the elements in the above embodiments may be deleted or known elements may be added without departing from the gist of the present invention.

[0063] Furthermore, the shapes of the detailed parts of the speed reducer and the traveling vehicle may be different from the shapes shown in the respective drawings of the above-mentioned embodiments.

[0064] <3. Conclusion>

[0065] In addition, the present technology can adopt the following structures.

[0066] (1) A reducer comprising: a shaft arranged along a central axis extending up and down; a housing fixed to the shaft and in the shape of a tube extending in the axial direction; a stator fixed to the housing; a rotor rotatable about the central axis relative to the stator; a sun gear rotatable about the central axis together with the rotor; planetary gears meshing with the sun gear from the radial outside and rotatable about an axis of rotation parallel to the central axis; a planetary shaft axially supporting the planetary gears; and a wheel carrier arranged above the planetary gears and supporting the planetary shafts, the housing having an internal gear meshing with the planetary gears from the radial outside, the wheel carrier having: a first region extending in the radial direction; and a second region in the shape of a tube extending downward from the radial inner end of the first region, at least a portion of the second region being supported on the shaft via a bearing at a position radially inward of the sun gear.

[0067] (2) The speed reducer according to (1), wherein a lower end of the second region is disposed below the planetary gear.

[0068] (3) The speed reducer according to (1) or (2), wherein a lower end of the second region is arranged below an upper end of the stator.

[0069] (4) A reducer according to any one of (1) to (3), wherein the bearing comprises: a first bearing that supports an upper end portion of the second region; and a second bearing that supports a lower end portion of the second region, the second bearing being arranged at a position lower than the planetary gear.

[0070] (5) The speed reducer according to any one of (1) to (4), wherein the housing and the internal gear are formed of one component.

[0071] (6) A reducer according to any one of (1) to (5), wherein the reducer further comprises: a partition plate portion extending radially inward from the inner circumferential surface of the housing; and a third bearing sandwiched between the outer circumferential surface of the sun gear and the radial inner end of the partition plate portion.

[0072] (7) The speed reducer according to any one of (1) to (6), wherein a plate thickness of the housing is smaller than an axial width of the first region of the wheel carrier.

[0073] (8) A traveling vehicle comprising a reducer as described in any one of (1) to (7), a tire and a tire support portion, wherein the tire support portion is cylindrical, the upper end portion of the tire support portion is fixed to the wheel frame, the tire is fixed to the radially outer surface of the tire support portion, and the lower end portion of the shell is arranged at a position above the lower end portion of the tire support portion.

[0074] The present application can be utilized in, for example, a speed reducer and a traveling vehicle.

Claims

1. A reducer, comprising: a shaft disposed along a central axis extending up and down; A housing, which is fixed to the shaft and is in the shape of a cylinder extending in the axial direction; a stator fixed to the housing; a rotor rotatable relative to the stator about the central axis; a sun gear rotatable with the rotor about the central axis; a planetary gear meshing with the sun gear from the radial outside and rotatable about an axis of rotation parallel to the central axis; a planet shaft that supports the planetary gear; and a wheel carrier, which is arranged above the planetary gears and supports the planetary shafts, The housing has an internal gear meshing with the planetary gear from the radial outside. It is characterized in that The wheel frame has: a first region extending radially; and The second region is cylindrical and extends downward from the radial inner end of the first region. At least a portion of the second region is supported by the shaft via a bearing at a position radially inward of the sun gear.

2. The reducer according to claim 1, characterized in that: The lower end of the second region is arranged below the planetary gear.

3. The reducer according to claim 1 or 2, characterized in that: The lower end of the second region is arranged below the upper end of the stator.

4. The reducer according to claim 1 or 2, characterized in that: The bearing has: a first bearing that supports an upper end portion of the second region; and a second bearing supporting a lower end portion of the second region, The second bearing is arranged below the planetary gear.

5. The reducer according to claim 1 or 2, characterized in that: The housing and the internally-toothed gear are formed from one component.

6. The reducer according to claim 1 or 2, characterized in that: The reducer also features: a partition plate portion extending radially inward from the inner peripheral surface of the housing; and The third bearing is interposed between the outer peripheral surface of the sun gear and the radial inner end portion of the partition plate portion.

7. The reducer according to claim 1 or 2, characterized in that: The plate thickness of the housing is smaller than the axial width of the first region of the carrier.

8. A traveling vehicle, characterized in that: The traveling vehicle comprises the speed reducer according to claim 1 or 2, a tire, and a tire support portion. The tire support portion is cylindrical, The upper end of the tire support portion is fixed to the wheel frame, The tire is fixed to the radially outer surface of the tire support portion. The position of the lower end portion of the casing is arranged above the position of the lower end portion of the tire supporting portion.

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