Driving device and moving body

Abstract

A drive device has a motor section having a motor shaft, and a reduction mechanism connected to the motor shaft. The reduction mechanism has a sun gear section arranged on the motor shaft, a planetary gear section engaged with the sun gear section and arranged in a circumferential direction, a carrier that at least partially surrounds the planetary gear section, and an output section connected to the planetary gear section. The carrier has a first cylindrical section arranged on an outer side and an upper side of the sun gear section and extending in an axial direction. The first cylindrical section rotatably supports the output section via a bearing, at least a part of which is arranged on a radially inner side than a radially outer end of the planetary gear section.

Description

Technical Field

[0001] The present invention relates to a drive device and a mobile body having a drive device. Background Technology

[0002] Previously, drive devices using electric motors were known. Such drive devices are used, for example, in mobile bodies such as electric wheelchairs. The drive device has a motor, and uses a planetary gear mechanism to output the rotation of the motor to the outside (see, for example, Japanese Patent Publication No. 2021-504639). Summary of the Invention

[0003] In the aforementioned drive device, the bearing that rotatably supports the output part connected to the planetary gear is located on the radial outer side of the planetary gear, making it difficult to reduce the radial width.

[0004] The present invention provides a miniaturized drive device and a mobile body using the drive device.

[0005] An exemplary drive device of the present invention includes: a motor section having a motor shaft arranged along a central axis extending vertically; and a reduction mechanism connected to the upper part of the motor shaft. The reduction mechanism includes: a sun gear section disposed on the radially outer side of the motor shaft; a plurality of planetary gear sections meshing with the sun gear section and arranged circumferentially; a planet carrier at least partially surrounding the radially outer side of the planetary gear sections; and an output section connected to the planetary gear sections. The planet carrier has a first cylindrical section disposed radially outer and upper than the sun gear section, and extending along the central axis. The first cylindrical section rotatably supports the output section via a bearing, at least a portion of which is disposed radially inner than the radially outer end of the planetary gear section.

[0006] An exemplary mobile body of the present invention has a drive unit, a power supply unit that provides power to the drive unit, and wheels connected to the drive unit.

[0007] According to the exemplary present invention, it is possible to provide a drive device and a mobile body using the drive device that can be miniaturized without reducing output torque.

[0008] The above and other features, elements, steps, characteristics and advantages of the present invention will be more clearly understood with reference to the accompanying drawings, provided that the preferred embodiments of the present invention are described in detail below. Attached Figure Description

[0009] Figure 1 This is a schematic diagram of an electric wheelchair, which is an example of a mobile body according to an embodiment of the present invention.

[0010] Figure 2 This is a 3D view of the drive unit.

[0011] Figure 3This is an exploded perspective view of the drive unit.

[0012] Figure 4 This is a cross-sectional view of the drive unit.

[0013] Figure 5 It is a cross-sectional view cut by a plane orthogonal to the central axis of the deceleration mechanism.

[0014] Figure 6 It is a three-dimensional diagram of the planetary carrier.

[0015] Figure 7 It is an enlarged cross-sectional view of the area around the bearing of the drive unit.

[0016] Figure 8 This is a cross-sectional view of the drive device in the first modified example.

[0017] Figure 9 This is a cross-sectional view of the drive device in the second variation. Detailed Implementation

[0018] Exemplary embodiments of the present invention will now be described in detail with reference to the accompanying drawings. In this specification, when describing the drive device 10, the following will be used... Figure 2 The description is based on the state of the drive device 10 shown. In the drive device 10, the central axis J1 extends in the vertical direction. The direction in which the central axis J1 extends is called the "axial direction". The direction orthogonal to the central axis J1 is called the "radial direction", and the direction along the arc centered on the central axis J1 is called the "circumferential direction".

[0019] Furthermore, the directions described above are defined for ease of explanation and may differ from the actual direction of the drive unit 10 used. For example, when the drive unit 10 is mounted on the moving body 100, the central axis J1 of the drive unit 10 extends in a direction parallel to the horizontal direction. Hereinafter, in the description of the moving body 100, the forward direction of travel will be designated as forward F, and the rearward direction of travel will be designated as rearward R.

[0020] <100 Movements>

[0021] Figure 1 This is a schematic diagram of a mobile body 100 according to an embodiment of the present invention. In this embodiment, the mobile body 100 is used to transport an electric wheelchair of a user while the user is seated. The mobile body 100 includes a drive unit 10, a power supply 102, and wheels. Therefore, by having a structure for the drive unit 10 described later, miniaturization can be achieved without reducing the output torque. Thus, in the mobile body 100, miniaturization can be achieved in the installed drive unit 10 without reducing the output torque. In this embodiment, as... Figure 1As shown, the moving body 100 has a frame 101, a power supply 102, a drive device 10, a drive wheel 103, and a driven wheel 104.

[0022] The frame 101 is formed into a chair shape by combining rod-shaped metal parts. The frame 101 has a seat 105, a backrest 106, armrests 107, and a footrest 108. The seat 105 is generally horizontally arranged, and the upper surface of the seat 105 is the seat surface of the movable body 100.

[0023] The backrest 106 is positioned at the rear R of the seat 105. The backrest 106 extends upward from the rear R end of the seat 105. The backrest 106 supports the upper body, i.e., the back, of the seated user. The upper end of the backrest 106 may also have a push handle 109 protruding rearward R. The push handle 109 is used when pushed by someone other than the user (e.g., a caregiver). Alternatively, the push handle 109 may be omitted in any structure where pushing is not required.

[0024] Armrests 107 are positioned above the left and right sides of the seat 105. The armrests 107 are positioned to accommodate the portion of the user's elbows. Cushioning components are provided at the points of contact between the user and the seat 105, backrest 106, and armrests 107. Therefore, even if the user sits on the mobile body 100 for extended periods, they are less likely to experience pain. Furthermore, a user-operable control unit 1071 is located on the upper part of the armrests 107. The mobile body 100 is operated by manipulating the control unit 1071.

[0025] The footrest 108 is located at the front end of the frame extending downward from the front end F of the seat 105. The user's feet can be positioned on the upper part of the footrest 108. By positioning the feet on the upper part of the footrest 108, the user's feet can be prevented from contacting the ground when the moving body 100 moves.

[0026] Power source 102 is connected to drive unit 10 and provides power to drive unit 10. Power source 102 is a battery. Power source 102 is located on frame 101 below seat 105. Drive wheels 103 are disposed on the left and right sides of frame 101. Drive wheels 103 are fixed to output section 35 (described later). In this embodiment, drive wheels 103 are an example of wheels. Drive wheels 103 are fixed to output section 35 (described later) of drive unit 10 (see reference). Figure 2 Furthermore, the rotation center of the drive wheel 103 coincides with the central axis J1 of the drive unit 10. The drive wheel 103 is rotated by the drive unit 10.

[0027] Driven wheel 104 is located F in front of drive wheel 103. Driven wheel 104 is mounted on mounting frame 1041 extending in the vertical direction and is capable of rotating about a driven axis orthogonal to mounting frame 1041. In addition, driven wheel 104 is capable of rotating about the center line of mounting frame 1041.

[0028] The drive unit 10 is mounted on the frame 101. The drive unit 10 rotates the drive wheel 103 mounted on the output section 35. Details of the drive unit 10 will be described later.

[0029] In the mobile body 100, power is supplied from the power source 102 to the drive unit 10 by a user who sits on the seat 105, leans against the backrest 106, and places their feet on the footrest 108, operating the control unit 1071. This causes the output unit 35 to rotate, the drive wheels 103 to rotate via the output unit 35, and the mobile body 100 to move. In the mobile body 100, when the left and right drive wheels 103 rotate in the same direction and at the same speed, the mobile body 100 moves in a straight line forward (F) or backward (R). Furthermore, when the left and right drive wheels 103 rotate in opposite directions or at different speeds, the mobile body 100 turns to the left or right.

[0030] <Driver 10>

[0031] The drive device 10 will now be described in detail with reference to the accompanying drawings. Figure 2 This is a perspective view of the drive unit 10. Figure 3 This is an exploded perspective view of the drive unit 10. Figure 4 This is a cross-sectional view of the drive unit 10.

[0032] like Figures 2 to 4 As shown, the drive unit 10 has a motor unit 20 and a reduction mechanism 30.

[0033] <Motor Section 20>

[0034] Motor unit 20 is a DC brushless motor. Motor unit 20 is driven by electricity from power source 102. Motor unit 20 has a motor shaft 21, a rotor 22, and a stator 25. A portion of the motor shaft 21, the rotor 22, and the stator 25 are disposed inside the housing 50. Motor unit 20 is an inner rotor type motor in which the rotor 22 is disposed radially inside the stator 25. However, motor unit 20 is not limited to an inner rotor type motor and may also be an outer rotor type motor.

[0035] <Motor Shaft 21>

[0036] The motor shaft 21 is approximately cylindrical. For example... Figures 2-4As shown, the motor shaft 21 extends along a central axis J1 that extends in the vertical direction. That is, the motor unit 20 has a motor shaft 21 arranged along a central axis J1 that extends vertically. The motor shaft 21 is capable of rotating about the central axis J1. Figure 4 As shown, the upper end of the motor shaft 21 protrudes upwards from the housing 50.

[0037] The motor shaft 21 is rotatably supported on the housing 50 via shaft bearings 211. The shaft bearings 211 are located at two axially separated points, rotatably supporting the motor shaft 21 at these two axially separated points. The shaft bearings 211 are ball bearings in this case, but are not limited to this. A wide variety of bearing structures capable of smoothly and correctly supporting the motor shaft 21 can be employed.

[0038] <Rotor 22>

[0039] The rotor 22 is fixed to the outer periphery of the motor shaft 21. The rotor 22 has a rotor core 23 and a rotor magnet 24. The rotor 22 rotates about a central axis J1 extending in the horizontal direction.

[0040] The rotor core 23 is formed by stacking thin sheet-like electromagnetic steel plates. The rotor core 23 is a cylinder extending axially. Alternatively, the rotor core 23 can also be formed by sintering magnetic powder. Multiple rotor magnets 24 are fixed on the rotor core 23. The multiple rotor magnets 24 are arranged circumferentially with alternating magnetic poles.

[0041] <Stator 25>

[0042] The stator 25 has a stator core 26, a coil 27, and an insulator 28. The stator 25 is held by a housing 50. The stator core 26 has a core back 261 and a plurality of pole teeth 262. The core back 261 is annular. The radially outer surface of the core back 261 is fixed to the housing 50. The pole teeth 262 protrude from the radially inner surface of the core back 261 toward a direction close to the central axis J1. The plurality of pole teeth 262 are arranged at equal intervals in the circumferential direction. The coil 27 is formed by winding a wire around the pole teeth 262.

[0043] <Outer shell 50>

[0044] like Figure 2 , Figure 3 As shown, the outer casing 50 is cylindrical. The outer casing 50 has an upper casing portion 51 and a lower casing portion 52. The upper casing portion 51 is a covered cylindrical shape with a cover portion 511 in the upper part of the axial direction and an opening in the lower part. The lower casing portion 52 is a bottomed cylindrical shape with a bottom 521 in the lower part and an opening in the upper part.

[0045] The upper housing 51 is positioned above the lower housing 52. At this time, the opening of the upper housing 51 is axially opposite to the opening at the top of the lower housing 52. Furthermore, the upper housing 51 and the lower housing 52 are secured by fasteners such as screws Sc1. The fasteners are not limited to screws Sc1; a wide range of structures capable of securely securing the upper housing 51 and the lower housing 52 can be used. Inside the housing 50, screws Sc1 are also used to secure the stator 25.

[0046] The housing 50 has an internal space 500 surrounded by an upper housing portion 51 and a lower housing portion 52. The axially oriented intermediate portion of the motor shaft 21, the rotor 22, and the stator 25 are housed in the internal space 500.

[0047] To further explain, the motor shaft 21 passes through a through hole 512 formed in the cover portion 511 of the upper housing 51 and extends axially. Additionally, the motor shaft 21 passes through a through hole 522 formed in the bottom 521 of the lower housing 52 and extends axially. Furthermore, the motor shaft 21 is supported for rotation by shaft bearings 211 mounted in the through holes 512 and 522.

[0048] A bracket 53 is disposed on the upper surface of the cover portion 511 of the upper portion 51 of the housing. The bracket 53 is annular in shape extending upward from the upper surface of the cover portion 511 along the central axis J1. That is, the housing 50 surrounds the radially outer side of a portion of the motor shaft 21. In this embodiment, the bracket 53 surrounds the radially outer side of a portion of the motor shaft 21. Alternatively, the bracket 53 may be formed discontinuously with notches or the like in a circumferential portion.

[0049] <Other Structures of Motor Section 20>

[0050] Below the motor section 20 are accessories such as a base plate 291 and a busbar 292. A control circuit is mounted on the base plate 291 to control the current supplied to the coil 27. The busbar 292 is a conductive component connecting the control circuit mounted on the base plate 291 and the coil 27.

[0051] The motor unit 20 is driven by electricity supplied from the power source 102. Specifically, current from the power source 102 is supplied to coils 27, thereby energizing the coils 27. This energization of the coils 27 generates a magnetic force between them and the rotor magnets 24 of the rotor 22. By energizing the multiple coils 27 at appropriate timing, a circumferential torque is generated on the rotor 22 centered on the central axis J1. This torque causes the motor shaft 21 to rotate about the central axis J1.

[0052] <Speed ​​reduction mechanism 30>

[0053] Figure 5 This is a cross-sectional view of the deceleration mechanism 30 cut by a plane orthogonal to the central axis J1. (Example) Figure 4As shown, the reduction mechanism 30 includes a sun gear section 31, a planetary gear section 32, a planet carrier 34, and an output section 35. More specifically, the reduction mechanism 30 also includes an internal gear section 33. The reduction mechanism 30 uses a so-called planetary gear mechanism to reduce the rotation of the motor shaft 21.

[0054] <Seismic Gear Section 31>

[0055] like Figures 3-5 As shown, the sun gear portion 31 is disposed at the upper end of the motor shaft 21. The sun gear portion 31 is disposed on the radially outer side of the motor shaft 21. The sun gear portion 31 rotates integrally with the motor shaft 21. Therefore, the sun gear portion 31 can be formed as a single component with the motor shaft 21, or it can be mounted on the motor shaft 21 and fixed by methods such as bonding, welding, threading, riveting, or pressing. Other fixing methods can also be used. Furthermore, fixing methods that allow the sun gear portion 31 to be fixed in a manner that allows it to rotate integrally with the motor shaft 21 can be widely adopted.

[0056] <Planetary Gear Section 32>

[0057] like Figures 3-5 As shown, the reduction mechanism 30 has three planetary gear sections 32. The three planetary gear sections 32 are arranged circumferentially. Furthermore, the three planetary gear sections 32 are arranged at equal intervals in the circumferential direction. The planetary gear sections 32 mesh with the sun gear section 31. However, while the reduction mechanism 30 of this embodiment has three planetary gear sections 32, it is not limited to three. Having two or more planetary gear sections 32 is sufficient. Furthermore, the circumferential arrangement of the planetary gear sections 32 is not limited to equal intervals. That is, multiple planetary gear sections 32 mesh with the sun gear section 31 and are arranged circumferentially.

[0058] The planetary gear section 32 will be further described. The planetary gear section 32 has a first planetary gear 321 and a second planetary gear 322. More specifically, the planetary gear section 32 has a planetary shaft 320, a first planetary gear 321, and a second planetary gear 322. The planetary shaft 320 extends along a planetary axis J2 parallel to the central axis J1. Figure 4 As shown, the lower end of the planetary shaft 320 is fixed to the cover 511 of the upper part 51 of the outer casing. In addition, the upper end of the planetary shaft 320 is inserted into the planetary through hole 3402 provided on the planet carrier 34.

[0059] The first planetary gear 321 and the second planetary gear 322 are rotatably supported by the planetary shaft 320. Furthermore, the first planetary gear 321 and the second planetary gear 322 are axially connected. That is, the first planetary gear 321 and the second planetary gear 322 can rotate integrally about a planetary axis J2 parallel to the central axis J1.

[0060] like Figure 4 , Figure 5 As shown, the first planetary gear 321 meshes with the star gear section 31. The diameter of the second planetary gear 322 is smaller than the diameter of the first planetary gear 321. That is, the diameter of the second planetary gear 322 is smaller than the diameter of the first planetary gear 321, and the second planetary gear 322 is connected to the first planetary gear 321. That is, the number of teeth of the second planetary gear 322 is less than the number of teeth of the first planetary gear 321.

[0061] The second planetary gear 322 rotates integrally with the first planetary gear 321. That is, the planetary gear section 32 is a two-stage gear. However, the planetary gear section 32 is not limited to a two-stage gear. The planetary gear section 32 can be a multi-stage gear with three or more stages, or it can be a gear with only a single diameter, i.e., a specified number of teeth. In addition, the first planetary gear 321 and the second planetary gear 322 can be formed from a single component, or they can be combined axially and fixed using methods such as bonding, welding, or threaded fixing.

[0062] Since the planetary gear section 32 has a first planetary gear 321 that meshes with the star gear section 31 and a second planetary gear 322 with a diameter smaller than the first planetary gear 321, it is easy to realize a reduction mechanism 30 with a large reduction ratio.

[0063] <Internal Gear Section 33>

[0064] like Figure 5 As shown, the internal gear portion 33 is a ring-shaped gear. Internal teeth are formed on its radially inner surface. The internal gear portion 33 meshes with the second planetary gear 322 of the planetary gear portion 32. That is, the reduction mechanism 30 has a ring-shaped internal gear portion 33 that meshes with the planetary gear portion 32 on its radially outer side.

[0065] like Figure 4 As shown, the internal gear section 33 is fixed to the output section 35. In this way, by fixing the internal gear section 33 to the output section 35, a certain reduction ratio can be achieved with a simple structure, and the axial length of the drive device 10 can be shortened.

[0066] <Planet Carrier 34>

[0067] Figure 6 This is a perspective view of the planetary carrier 34. The planetary carrier 34 is positioned axially above the motor section 20. Figure 4 , Figure 6As shown, the planetary carrier 34 has a cover portion 340, a first cylindrical portion 341, a second cylindrical portion 342, a connecting portion 343, and a small shaft 344. The cover portion 340 is positioned axially above the second planetary gear 322. The cover portion 340 is orthogonal to the central axis J1. Furthermore, the second planetary gear 322 of the planetary gear portion 32 is housed inside the cover portion 340. At least a portion of the planetary carrier 34 surrounds the radially outer side of the planetary gear portion 32.

[0068] The cover portion 340 has an axially extending shaft hole 3401 in its central portion. A small shaft 344 is fixed in the shaft hole 3401. The center of the small shaft 344 coincides with the central axis J1. The cover portion 340 has three planetary through holes 3402. The three planetary through holes 3402 are equidistant from the central axis J1 and are arranged at equal intervals in the circumferential direction. The number of planetary through holes 3402 is not limited to three, and may be the same as or more than the number of planetary gear portions 32.

[0069] The upper end of the planetary shaft 320 of the planetary gear section 32 is housed inside the planetary through hole 3402. In the drive device 10 of this embodiment, a gap is formed between the planetary shaft 320 and the planetary through hole 3402. However, it is not limited to this; the planetary shaft 320 may be fixed in the planetary through hole 3402 of the cover section 340, or it may be supported so that it can rotate.

[0070] The planet carrier 34 has a first cylindrical portion 341. The first cylindrical portion 341 extends along the central axis J1. The first cylindrical portion 341 is positioned radially outward and upward compared to the sun gear portion 31. The first cylindrical portion 341 is positioned radially outward of the second planetary gear 322 of the planetary gear portion 32. Additionally, as... Figure 4 As shown, the first cylindrical portion 341 is positioned axially above the first planetary gear 321. Furthermore, the radially outer surface of the first cylindrical portion 341 is positioned radially inward than the radially outer end of the first planetary gear 321.

[0071] The planetary carrier 34 has a second cylindrical portion 342. That is, the planetary carrier 34 has a first cylindrical portion 341, a second cylindrical portion 342, and a connecting portion 343. The second cylindrical portion 342 extends along the central axis J1. The second cylindrical portion 342 is positioned radially outward and downward compared to the first cylindrical portion 341. The radially inner side of the axially lower end of the second cylindrical portion 342 contacts the radially outer side of the bracket 53. That is, the second cylindrical portion 342 is fixed to the housing 50. In other words, the planetary carrier 34 is fixed to the housing 50. Thus, the second cylindrical portion 342 is fixed to the upper part 51 of the housing. The outer diameter of the second cylindrical portion 342 is larger than the outer diameter of the first cylindrical portion 341. Furthermore, the second cylindrical portion 342 surrounds the radially outer side of the first planetary gear 321 of the planetary gear portion 32. Thus, the planetary carrier 34 and the housing 50 can be fixed, and therefore, the output portion 35 can be stably driven to rotate relative to the housing 50.

[0072] The lower axial end of the first cylindrical portion 341 and the upper axial end of the second cylindrical portion 342 are connected via a connecting portion 343. That is, the connecting portion 343 connects the first cylindrical portion 341 and the second cylindrical portion 342.

[0073] In addition, such as Figure 4 , Figure 6 As shown, the connecting portion 343 is an annular shape that extends in a direction orthogonal to the central axis J1. That is, the connecting portion 343 is an annular shape centered on the central axis J1.

[0074] This configuration improves the rigidity of the planet carrier 34. Furthermore, by making the connecting portion 343 annular, the outer diameter of the second cylindrical portion 342 can be increased while maintaining the rigidity of the planet carrier 34. Therefore, since the planet carrier 34 and the housing 50 are fixed as far outward as possible in the radial direction, the motor portion 20 and the reduction gear 30 can be stably and securely fixed.

[0075] like Figure 6 As shown, the connecting part 343 has a fixing hole 345 that extends through the axial direction. A screw Sc2 is inserted into the fixing hole 345 and screwed into the upper part 51 of the housing. Thus, the planet carrier 34 is fixed to the housing 50.

[0076] <Output Section 35>

[0077] The output section 35 is connected to the planetary gear section 32. An external device, such as..., is connected to the output section 35. Figure 1 The drive wheel 103 is shown. The output section 35 has a first region 351 and a second region 352. The first region 351 is cylindrical and extends along the central axis J1. The first region 351 extends along the central axis J1 and supports the radially outer side of the bearing Br. The second region 352 extends radially inward from the upper end of the first region 351. An internal gear section 33 is fixed at the output section 35. Specifically, the second region 352 and the internal gear section 33 are fixed by screws Sc3. Alternatively, the output section 35 and the internal gear section 33 can be formed and fixed from different parts, or they can be fixed by parts or mechanisms other than screws. Alternatively, the internal gear section 33 and the output section 35 can be formed from a single component.

[0078] Furthermore, a recess 353 is formed on the upper surface of the second region 352, which is recessed along the axial direction. That is, a recess 353 is formed in the second region 352. There are three recesses 353 in the second region 352. The three recesses 353 are arranged at equal intervals along the circumference. A fixing screw Lc for fixing the drive wheel 103 is disposed in the recess 353 (see reference). Figure 1For example, an internal thread is formed on the inner surface of the recess 353. The through hole (not shown) of the drive wheel 103 is axially aligned with the recess 353 of the output portion 35, and the fixing screw Lc is screwed into the recess 353. The drive wheel 103 is thus fixed to the output portion 35. With this configuration, a driven body such as a wheel can be mounted via the recess 353. Since the recess 353 is located inside the radially outer surface of the output portion 35, driven bodies with smaller mounting portions can also be mounted.

[0079] Furthermore, in the above structure, the drive wheel 103 is fixed to the output portion 35 by screwing the fixing screw Lc into the recess 353, but it is not limited to this. For example, the fixing screw Lc may be fixed to the recess 353 by pressing or other fixing methods, and a nut may be screwed into the fixing screw Lc from the outside of the drive wheel 103 for fixing.

[0080] In addition, such as Figure 4 As shown, the second region 352 of the output section 35 is rotatably supported on the small shaft 344 via the output bearing 354. The first region 351 of the output section 35 is rotatably supported on the first cylindrical section 341 via the bearing Br. That is, the output section 35 is rotatably supported on the planetary carrier 34 via the bearing Br and the output bearing 354.

[0081] <BearingBr>

[0082] The bearing Br rotatably supports the output section 35 on the planetary carrier 34. That is, the first cylindrical section 341 rotatably supports the output section 35 via the bearing Br. Furthermore, the radially outer surface of the second cylindrical section 342 is positioned radially outward than the radially outer end of the bearing Br. With this configuration, while keeping the radial position of the output section 35 constant, the second cylindrical section 342 can be positioned as radially outward as possible, thus providing more stable support for the output section 35.

[0083] Furthermore, by mounting the bearing Br to the first cylindrical portion 341, the radially inner surface of the bearing Br is positioned further radially inward than the radially outer end of the first planetary gear 321. Thus, a portion of the bearing Br is positioned further radially inward than the radially outer end of the first planetary gear 321. In other words, at least a portion of the bearing Br is positioned further radially inward than the radially outer end of the planetary gear portion 32.

[0084] With this configuration, the bearing Br overlaps axially with the planetary gear section 32, thus allowing the outer diameter of the planetary gear section 32 to be increased without increasing the radial width of the drive unit 10. Consequently, the torque transmitted from the sun gear section 31 to the planetary gear section 32 can be increased without increasing the radial width of the drive unit 10. In other words, a compact drive unit 10 capable of outputting high torque can be formed.

[0085] For example, such as Figure 1 As shown, when the drive device 10 is used to drive the mobile body 100, the mobile body 100 can be miniaturized. Furthermore, the proportion of the volume occupied by the drive device 10 in the mobile body 100 can be reduced. Therefore, a large-capacity power supply 102 can be installed without changing the size of the mobile body 100. Consequently, the continuous driving time of the mobile body 100 can be extended.

[0086] In detail, the bearing Br is supported on the radially outer side of the first cylindrical portion 341 of the planetary carrier 34. That is, the bearing Br is supported by the radially outer side of the first cylindrical portion 341. Therefore, the output portion 35 is supported concentrically with the motor shaft 21 and can rotate with high precision, and each planetary gear portion 32 meshes stably with the internal gear portion 33. As a result, torque can be stably transmitted to the output portion 35. In addition, the second cylindrical portion 342 of the planetary carrier 34 is positioned radially outer than the first cylindrical portion 341. Furthermore, by mounting the bearing Br on the outer side of the first cylindrical portion 341, the large diameter of the drive unit 10 can be suppressed.

[0087] The bearing Br is supported by the radially outer surface of the first cylindrical portion 341, thereby arranging the bearing Br and the connecting portion 343 opposite each other in the direction of the central axis J1. Furthermore, the bearing Br is positioned with a gap T between it and the connecting portion 343 in the direction of the central axis J1. The gap T between the bearing Br and the connecting portion 343 in the direction of the central axis J1 is shorter than the radial distance L1 between the radially outer surface of the second cylindrical portion 342 and the radially outer surface of the bearing Br.

[0088] This configuration prevents foreign objects such as dust from entering the interior of the bearing Br through the gap T between the bearing Br and the connecting part 343. As a result, the drive unit 10 can output driving force stably for a long time.

[0089] The radially outer surface of the bearing Br is fixed to the radially inner surface of the first region 351 of the output section 35. Since the output section 35 is held by the outer ring of the bearing Br, the reaction force from the driven body such as the drive wheel 103 connected to the output section 35 can be distributed to the entire drive unit 10. As a result, the burden acting on each unit area of ​​the output section 35 can be reduced (the effect of technical solution 9).

[0090] Refer to the attached diagram for detailed instructions on installing bearing Br. Figure 7 This is an enlarged cross-sectional view of the area around the bearing Br of the drive unit 10. (See image.) Figure 7 As shown, the upper axial end of the first cylindrical portion 341 is positioned lower than the upper axial end of the bearing Br. Because the axial length of the first cylindrical portion 341 is shorter, the axial length of the drive unit 10 can be reduced. Furthermore, the shorter axial length of the first cylindrical portion 341 allows for a lighter drive unit 10.

[0091] In addition, such as Figure 4 As shown, the lower axial end of the internal gear portion 33 is positioned below the upper axial end of the bearing Br. That is, a portion of the bearing Br overlaps with the internal gear portion 33 radially. Alternatively, the entire bearing Br may overlap with the internal gear portion 33 radially. That is, at least a portion of the bearing Br overlaps with the internal gear portion 33 radially. Therefore, compared to the case where the internal gear portion 33 is positioned above the bearing Br, the mounting position of the internal gear portion 33 can be positioned lower, thus reducing the axial length of the drive device 10.

[0092] <Operation of Drive Unit 10>

[0093] As described above, the drive unit 10 is connected to the power supply 102. Current from the power supply 102 is supplied to the motor section 20 of the drive unit 10. Specifically, current is supplied to the coil 27 of the motor section 20. As a result, the coil 27 is energized, and the rotor 22 and the motor shaft 21 fixed to the rotor 22 rotate around the central axis J1. That is, the sun gear section 31 disposed on the motor shaft 21 also rotates.

[0094] The torque generated by the rotation of the sun gear 31 is transmitted to the first planetary gear 321, which rotates about the planetary axis J2. Furthermore, in the drive unit 10, the planetary shaft 320 is fixed to the upper part 51 of the housing. Therefore, the planetary gear 32 does not move circumferentially around the sun gear 31.

[0095] Furthermore, the torque generated when the planetary gear section 32 rotates is transmitted from the second planetary gear 322 to the internal gear section 33. The internal gear section 33 is fixed to the output section 35, and the output section 35 is rotatably supported on the planet carrier 34 via bearing Br and output bearing 354. Since the planet carrier 34 is fixed to the housing 50 of the motor section 20, the output section 35 rotates relative to the motor section 20 about the central axis J1.

[0096] At this time, the output unit 35 is slowed down according to the gear ratio between the stellar gear unit 31 and the internal gear unit 33, in other words, the torque increases and it rotates.

[0097] <First Variation>

[0098] Figure 8 This is a cross-sectional view of the drive device 10a of the first modified example. Figure 8 In the drive unit 10a shown, the housing 50a, the planetary carrier 34a of the reduction mechanism 30a, and the output part 35a are... Figure 4The housing 50, planetary carrier 34, and output section 35 of the drive unit 10 shown are different. Except for these, the drive unit 10a has the same structure as the drive unit 10. Therefore, in the drive unit 10a, parts that are substantially the same as those in the drive unit 10 are labeled with the same symbols, and detailed descriptions of the same parts are omitted.

[0099] like Figure 8 As shown, the first cylindrical portion 341a of the planetary carrier 34a of the reduction mechanism 30a is a cylindrical section protruding upward from the upper surface of the upper portion 51a of the outer casing 50a. The bearing Br is supported by the radially inner side of the first cylindrical portion 341a. Furthermore, the radially outer side of the first region 351a of the output portion 35a is supported by the radially inner side of the bearing Br. Thus, the output portion 35a is rotatably supported on the first cylindrical portion 341a. With this configuration, the bearing Br is positioned radially inner on the first cylindrical portion 341a, thereby reducing the radial width of the drive unit 10a.

[0100] <Second Variation>

[0101] Figure 9 This is a cross-sectional view of the drive unit 10b in the second modified example. Figure 9 In the drive unit 10b shown, the planet carrier 34b and the output unit 35b are connected to... Figure 4 The planetary carrier 34 and output section 35 of the drive unit 10 shown are different. Furthermore, in the drive unit 10b, an external gear section 356 is provided instead of the internal gear section 33. Except for this, the drive unit 10b has the same structure as the drive unit 10. Therefore, in the drive unit 10b, the same reference numerals are used for parts that are substantially the same as those in the drive unit 10, and detailed descriptions of the same parts are omitted.

[0102] like Figure 9 As shown, the output section 35b includes an output shaft 355 and an external gear section 356. The output shaft 355 is positioned axially above the motor shaft 21. The output shaft 355 is rotatably mounted on the radially inner side of the first cylindrical portion 341b of the planetary carrier 34b via a bearing Brb. The output shaft 355 is the output section. Furthermore, the external gear section 356 is positioned on the radially outer side of the axially lower end of the output shaft 355. That is, the external gear section 356 is positioned on the radially outer side of the output shaft 355.

[0103] Furthermore, the external gear 356 meshes with the second planetary gear 322 radially inside it. The rotation of the planetary gear 32 is transmitted to the output shaft 355 via the external gear 356. As a result, the output shaft 355 rotates. In the drive unit 10b, the drive wheel 103 is fixed to the output shaft 355.

[0104] By configuring the drive unit 10b in this way, the internal gear section 33 can be omitted, thus reducing the radial width of the drive unit 10b. Furthermore, even a structure with a small number of planetary gear sections 32 can be driven. Therefore, the number of parts can be reduced.

[0105] Alternatively, the external gear portion 356 can be formed as a single component with the output shaft 355. Alternatively, the external gear portion 356 can be mounted on the output shaft 355 and fixed using methods such as welding, bonding, or pressing.

[0106] <Other variations>

[0107] In the drive unit 10, the reduction mechanism 30 is a so-called star-shaped planetary gear mechanism in which the planetary gear section 32 and the planet carrier 34 are fixed relative to the motor section 20, and the internal gear section 33 rotates. However, it is not limited to this; it can also be a so-called planetary gear mechanism in which the planetary gear section and the planet carrier rotate relative to the motor section, and the internal gear section is fixed. That is, the internal gear section is fixed to the motor section. As a result, a planetary gear section 32 with a simple structure can be used, and the axial length can be shortened.

[0108] In this structure, the small shaft fixed on the planetary carrier serves as the output section.

[0109] The various technical features disclosed in this specification can be modified in various ways without departing from the spirit of the technical inventiveness. Furthermore, the various embodiments and variations shown in this specification can be combined and implemented to the extent possible.

[0110] This invention can be used in mobile devices that obtain driving power through electricity, such as electric-assisted bicycles, electric scooters, electric wheelchairs, and delivery robots.

[0111] Figure Labels

[0112] 100 moving bodies

[0113] 101 Framework

[0114] 102 power supply

[0115] 103 drive wheels

[0116] 104 Driven wheels

[0117] 105 Seats

[0118] 106 Backrest

[0119] 107 Armrest Section

[0120] 1071 Operations Department

[0121] 108 Footrest

[0122] 109 Hand-operated handle

[0123] 10. Drive unit

[0124] 20 Motor Section

[0125] 21 Motor Shaft

[0126] 211 shaft bearing

[0127] 22 Rotors

[0128] 23 Rotor core

[0129] 24 Rotor Magnet

[0130] 25 stators

[0131] 26 Stator Core

[0132] 261 Iron core back

[0133] 262 Pole Teeth

[0134] 27 coils

[0135] 28 Insulators

[0136] 291 substrate

[0137] 292 busbar

[0138] 30. Reduction Mechanism

[0139] 31. Stellar Gear Section

[0140] 32 Planetary Gear Section

[0141] 320 planetary axis

[0142] 321 First Planetary Gear

[0143] 322 Second Planetary Gear

[0144] 33 Internal gear section

[0145] 34 Planetary Carrier

[0146] 340 cover

[0147] 3401 shaft hole

[0148] 3402 Planetary Through-hole

[0149] 341 First tube section

[0150] 342 Second tube section

[0151] 343 Connecting part

[0152] 344 small shaft

[0153] 345 Fixing Hole

[0154] 35 Output Section

[0155] 351 First District

[0156] 352 Second Area

[0157] 353 recess

[0158] 354 Output Bearing

[0159] 355 Output Shaft

[0160] 356 External Gear Section

[0161] 50. Outer shell

[0162] 500 interior spaces

[0163] 51 Upper part of the outer shell

[0164] 511 cover

[0165] 512 Through Hole

[0166] 52 Lower part of the outer casing

[0167] 521 Bottom

[0168] 522 Through Hole

[0169] 53 Brackets

[0170] 10a Drive Unit

[0171] 34a Planetary Carrier

[0172] 341a First tube section

[0173] 35a Output Section

[0174] 351a First Area

[0175] 50a casing

[0176] 51a Upper part of the outer casing

[0177] 10b drive unit

[0178] 34b Planetary Carrier

[0179] 341b First tube section

[0180] 35b Output Section

[0181] Br bearing

[0182] Brb bearings

[0183] F front

[0184] J1 central axis

[0185] J2 Planetary Axis

[0186] L1 radial distance

[0187] R behind

[0188] T-gap.

Claims

1. A driving device comprising: The motor section has a motor shaft arranged along a central axis extending vertically; and A speed reduction mechanism is connected to the upper part of the motor shaft. The deceleration mechanism has: A stellar gear portion, which is disposed on the radial outer side of the motor shaft; Multiple planetary gear sections that mesh with the star gear section and are arranged circumferentially; Planet carrier, at least a portion of which surrounds the radially outer side of the planetary gear assembly; and The output section is connected to the planetary gear section. The planetary carrier has a first cylindrical portion, which is positioned radially outward and upward compared to the star gear portion, and extends along the central axis. The planetary gear section has: A first planetary gear, which meshes with the star gear; as well as A second planetary gear, having a smaller diameter than the first planetary gear, is connected to the first planetary gear. The first cylindrical section supports the output section via bearings, enabling it to rotate. At least a portion of the bearing is positioned radially inward from the radially outer end of the first planetary gear and radially outward from the radially outer end of the second planetary gear.

2. The driving device according to claim 1, wherein, The motor unit has a housing that surrounds the radially outer side of a portion of the motor shaft, and the planetary carrier is fixed to the housing.

3. The driving device according to claim 1 or 2, wherein, The reduction mechanism has an annular internal gear portion that meshes with the planetary gear portion radially outward. The internal gear section is fixed to the output section.

4. The driving device according to claim 1 or 2, wherein, The reduction mechanism has an annular internal gear portion that meshes with the planetary gear portion radially outward. The internal gear section is fixed to the motor section.

5. The driving device according to claim 1 or 2, wherein, The output section has: An output shaft, which is disposed axially above the motor shaft; and An external gear section is disposed on the radially outer surface of the output shaft. The external gear portion meshes with the second planetary gear on the radially inner side of the second planetary gear.

6. The driving device according to claim 3, wherein, At least a portion of the bearing overlaps radially with the internal gear portion.

7. The driving device according to claim 4, wherein, At least a portion of the bearing overlaps radially with the internal gear portion.

8. The driving device according to claim 1 or 2, wherein, The upper axial end of the first cylindrical portion is configured to be lower than the upper axial end of the bearing.

9. The driving device according to claim 2, wherein, The planetary carrier has: The first cylindrical section; The second cylindrical portion is disposed radially outward and downward than the first cylindrical portion, extends along the central axis, and is fixed to the outer casing; as well as A connecting portion that connects the first cylindrical portion and the second cylindrical portion. The bearing is supported on the radial outer side of the first cylindrical section.

10. The driving device according to claim 9, wherein, The connecting part is in the shape of a ring centered on the central axis.

11. The driving device according to claim 9, wherein, The radially outer side of the second cylindrical portion is positioned radially outer than the radially outer end of the bearing.

12. The driving device according to claim 9, wherein, The bearing and the connecting part are arranged opposite to each other in the direction of the central axis. The gap between the bearing and the connecting part in the direction of the central axis is shorter than the radial distance between the radial outer side of the second cylinder and the radial outer side of the bearing.

13. The driving device according to claim 1 or 2, wherein, The output section has: A first region, extending along the central axis and supporting the radially outer surface of the bearing; and A second region extends radially inward from the upper end of the first region. A recess is formed in the second region.

14. The driving device according to claim 1 or 2, wherein, The bearing is supported on the radial inner side of the first cylindrical section.

15. A mobile body, comprising: The driving device according to any one of claims 1 to 14; A power source, connected to the drive unit and providing power to the drive unit; and A wheel, which is fixed to the output section.

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