Transmission device and vehicle

Abstract

This transmission device is attached to an attachment object having a hub shaft, and comprises a hub, a transmission mechanism, and a fixed shaft. The transmission mechanism transmits torque from a power source to the hub. The fixed shaft is formed in a hollow structure, supports the transmission mechanism, is fitted externally to the hub shaft, is unable to rotate with respect to the hub shaft, and includes a large diameter part and a small diameter part. An inner diameter of the large diameter part is larger than an inner diameter of the small diameter part, and a gap is formed between an inner peripheral surface of the large diameter part and an outer peripheral surface of the hub shaft. In an axial direction of the hub shaft, the small diameter part is arranged away from the hub in relation to the large diameter part, and the transmission mechanism is arranged radially outward of the large diameter part in such a manner that at least a part of the transmission mechanism overlaps with the large diameter part in the axial direction.

Description

Transmission and vehicle

[0001] The present invention relates to a transmission and a vehicle equipped with the transmission.

[0002] In recent years, with the implementation of the "double carbon" strategy and the rapid development of the new energy field, new energy vehicles are increasingly favored by consumers due to their convenience, environmental friendliness, and low price. In the field of electric vehicles, which are typical new energy vehicles, especially in the fields of electric bicycles and electric motorcycles, a planetary gear mechanism may be used as a transmission. In electric vehicles, different requirements for rotational speed and torque are required in different situations. For example, low rotational speed and high torque are required when starting, and high rotational speed and low torque are required when the vehicle is traveling at high speed.

[0003] In a typical electric vehicle, such as an electric bicycle or electric motorcycle, a motor serving as a power source is mounted in the longitudinal center of the vehicle body, i.e., midway between the front and rear wheels, and the power source transmits torque to the front or rear wheel via a transmission device (a chain, sprockets, or a transmission mechanism). In such an electric vehicle, a hub axle may be attached to a pair of support frames of a chassis so as to extend along the width of the vehicle, and a transmission mechanism may be attached to the hub axle.

[0004] However, when the above structure is used, there is a risk that the gear change mechanism may be affected if the hub axle is deformed (bent) due to a load.

[0005] The present invention has been made in consideration of the above circumstances, and aims to provide a transmission device that can suppress the effect on the transmission mechanism even if the hub axle is deformed, and also aims to provide a vehicle equipped with such a transmission device.

[0006] In order to achieve the above object, the present invention uses the following technical means.

[0007] According to one aspect of the present invention, a transmission device that is attached to an attachment object having a hub axle includes a hub, a speed change mechanism, and a fixed axle, wherein the speed change mechanism transmits torque from a power source to the hub, the fixed axle is formed with a hollow structure and supports the speed change mechanism, is fitted onto the hub axle and is non-rotatable relative to the hub axle, and includes a large diameter portion and a small diameter portion, the inner diameter of the large diameter portion is larger than the inner diameter of the small diameter portion, and a gap is formed between the inner surface of the large diameter portion and the outer surface of the hub axle, the small diameter portion is positioned away from the hub relative to the large diameter portion in the axial direction of the hub axle, and the speed change mechanism is positioned radially outward of the large diameter portion so that at least a portion of the speed change mechanism overlaps with the large diameter portion in the axial direction.

[0008] According to one aspect of the present invention, the gap can be utilized to absorb deformation of the hub axle, so even if the hub axle is deformed, the effect on the transmission mechanism can be reduced.

[0009] Fig. 1 is a schematic side view showing a vehicle according to an embodiment of the present invention. Fig. 2 is a schematic cross-sectional view showing a transmission according to an embodiment of the present invention. Fig. 3 is a speed diagram showing a planetary gear mechanism in the first gear stage of the transmission according to the present invention. Fig. 4 is a speed diagram showing a planetary gear mechanism in the second gear stage of the transmission according to the present invention. Fig. 5 is a schematic topology diagram when the input member stops driving and the vehicle is pushed forward by human power. Fig. 6 is a schematic topology diagram when the input member stops driving and the vehicle is pushed backward by human power. Fig. 7 is a schematic cross-sectional view showing the structure of a portion of a fixed shaft.

[0010] Hereinafter, exemplary embodiments of the present invention will be described with reference to the drawings. It should be understood that these specific descriptions are merely intended to teach those skilled in the art how to implement the present invention, and do not encompass all possible forms of the present invention or limit the scope of the present invention.

[0011] In this specification, "axial direction," "radial direction," and "circumferential direction" refer to the axial direction, radial direction, and circumferential direction of the hub. "Fixed connection" means that two members are connected so that there is no relative movement, and unless otherwise specified, includes both a direct fixed connection and an indirect fixed connection via another member. "Power transmission connection" means that two members are connected so that torque can be transmitted, and includes both a direct connection and an indirect connection. "Lock" includes both a direct lock and an indirect lock via another member. "Engaged state" means a state in which the clutch unit can transmit torque and rotation, and "disengaged state" means a state in which the clutch unit does not transmit torque and rotation. Note that a clutch unit in an engaged state does not necessarily transmit torque and rotation.

[0012] In this specification, the term "rotational speed" may refer to the number of times (number of rotations) that a rotating object rotates around its central axis within a unit of time, and for example, the unit may be rpm (revolutions per minute).

[0013] (Vehicle) Hereinafter, a vehicle 100 according to an embodiment of the present invention will be described with reference to FIG.

[0014] As shown in FIG. 1 , the vehicle 100 of this embodiment is an electric motorcycle. Specifically, the vehicle 100 is an electric bicycle including a front wheel 1, a rear wheel 2, pedals 3, a seat 4, and a chassis. The front wheel 1 and the rear wheel 2 are mounted on the chassis. A motor (not shown) serving as a drive source is provided near the pedal 3. The motor is attached to the chassis and is located between the front wheel 1 and the rear wheel 2 in the longitudinal direction of the vehicle 100. The output of the motor is transmitted to a transmission device 200 at the rear wheel 2 via a chain 5. The vehicle 100 may have the following three drive modes. Specifically, the vehicle 100 includes the following three drive modes:

[0015] In pure electric mode, no human power is involved and the motor is driven entirely by the battery of the vehicle 100. In assisted mode, both battery drive and human power are involved in cycling. In human-powered mode, cycling is purely human-powered, with the vehicle 100 moving by pedaling 3, just like a regular bicycle.

[0016] (Transmission) Hereinafter, a transmission 200 according to one embodiment of the present invention will be described with reference to FIG.

[0017] 2 , the transmission device 200 of this embodiment includes an input member 6, a hub T, and a speed change mechanism 7. The input member 6 transmits torque from a power source to the speed change mechanism 7. The speed change mechanism 7 transmits the torque from the input member 6 to the hub T. The torque output from the motor can drive the rear wheel 2 via the input member 6 and the planetary gear mechanism 20.

[0018] The vehicle 100 has a chassis fixed to the vehicle body. The chassis includes a pair of support frames 101. The hub axle O is attached to the pair of support frames 101 so as to extend along the width direction of the vehicle and is fixed non-rotatably to the support frames 101. The hub T is rotatable around the hub axle O. The hub T has an inner cylinder portion 11 provided on the radially inner side, an outer cylinder portion 12 provided on the radially outer side, and a connecting portion 13 connecting the inner cylinder portion 11 and the outer cylinder portion 12. The connecting portion 13 is plate-shaped and extends radially outward from the right end edge of the inner cylinder portion 11 to the center of the outer cylinder portion 12. The inner cylinder portion 11 extends from the radially inner edge of the connecting portion 13 toward the left in the axial direction of the hub axle O (the left-right direction in FIG. 2 ) and is attached to the hub axle O by a pair of bearings 14 arranged axially spaced apart. The outer tube portion 12 extends simultaneously from the radially outer edge of the connecting portion 13 to the left and right in the axial direction of the hub axle O, and the tire 10 of the vehicle 100 is attached to the outer peripheral surface of the outer tube portion 12.

[0019] The transmission device 200 further includes a hollow fixed shaft 8. The fixed shaft 8 is fitted onto the hub axle O and is unable to rotate relative to the hub axle O. The left end of the fixed shaft 8 extends to the vicinity of the connecting portion 13. A protrusion 81 is formed on the right end of the fixed shaft 8. The protrusion 81 has an outer shape that fits into an elongated hole formed in the support frame 101. By inserting the protrusion 81 into the elongated hole formed in the support frame 101, the fixed shaft 8 is unable to rotate relative to the support frame 101.

[0020] The input member 6 includes a sprocket 61 and a transmission sleeve 62. The transmission sleeve 62 is fitted onto the fixed shaft 8. The transmission sleeve 62 includes an integrally formed cylindrical portion 621 and flange portion 622. The cylindrical portion 621 extends along the axial direction of the hub axle O. The input member 6 is supported by and rotatable relative to the fixed shaft 8 by being attached to the fixed shaft 8 by a pair of bearings 16 arranged on the left and right. The flange portion 622 extends radially outward from the right end of the cylindrical portion 621. A through hole into which the connecting member 63 is inserted is formed in the flange portion 622, and a stepped portion 623 is formed extending rightward from the radially inner end of the flange portion 622. The sprocket 61 has a hollow disk shape, can be attached to the stepped portion 623, and is fixed to the transmission sleeve 62 by the connecting member 63. Chain teeth are formed on the outer periphery of the sprocket 61. The chain 5 is stretched over the sprocket 61 and the sprocket on the output shaft of the motor, and meshes with the chain teeth of these sprockets. When the chain 5 is driven by the pedals 3 and / or the motor to operate, the sprocket 61 rotates accordingly.

[0021] The transmission mechanism 7 is disposed between the coupling portion 13 and the input member 6 in the axial direction of the hub axle O. In other words, it is disposed on the side of the input member 6 closer to the hub T in the axial direction of the hub axle O. The transmission mechanism 7 includes a planetary gear mechanism 20. The planetary gear mechanism 20 is a single-row planetary gear mechanism and includes a ring gear 201, a sun gear 202, a planet carrier 203, planet gears 204, and a housing 205. The sun gear 202 serves as a power input end and is attached to the end of the cylindrical portion 621 opposite the sprocket 61, thereby achieving a power transmission connection with the input member 6 and being able to receive torque input from the motor. The housing 205 is fixed to the coupling portion 13 by a connecting member. The ring gear 201 serves as a power output end and is power transmission connected to the hub T. The planetary gears 204 are disposed radially between the ring gear 201 and the sun gear 202 and mesh with the ring gear 201 and the sun gear 202, respectively.

[0022] The transmission mechanism 7 further includes a first clutch unit 301, a second clutch unit 302, and a third clutch unit 70. When the first clutch unit 301 is in an engaged state, the planetary carrier 203 can be locked to the hub axle O by the first clutch unit 301 and is therefore unable to rotate. When both the second clutch unit 302 and the third clutch unit 70 are in an engaged state, the planetary carrier 203 can be locked to the ring gear 201, which serves as a power output component, by the second clutch unit 302 and the third clutch unit 70, and the planetary gear mechanism 20 rotates as a unit. The first clutch unit 301 can be selectively engaged, or the second clutch unit 302 and the third clutch unit 70 can be selectively engaged at different gear stages.

[0023] The first clutch unit 301, the second clutch unit 302, and the third clutch unit 70 are located axially of the hub axle O between the gear pair structure (ring gear 201, sun gear 202, and planet gears 204) of the planetary gear mechanism 20 and the connecting portion 13. The second clutch unit 302 is located radially outward from the first clutch unit 301. The third clutch unit 70 is located radially outward from the second clutch unit 302. The first clutch unit 301 is located radially inward from the planet carrier 203. The second clutch unit 302 and the third clutch unit 70 are located radially outward from the planet carrier 203. The first clutch unit 301, the second clutch unit 302, and the third clutch unit 70 overlap each other in the axial direction. That is, when viewed in a radial direction perpendicular to the axial direction, the first clutch unit 301, the second clutch unit 302, and the third clutch unit 70 are shielded from each other. In the axial direction, the first clutch unit 301 is disposed on the side closer to the hub T than the sun gear 202 .

[0024] The first clutch unit 301 and the second clutch unit 302 each have an inner ring and an outer ring. In an engaged state, the inner ring and the outer ring cannot rotate relative to each other, and in a disengaged state, the inner ring and the outer ring can rotate relative to each other. The first clutch unit 301 and the second clutch unit 302 are both one-way clutches. In this specification, a one-way clutch refers to a clutch in which one of the inner ring and the outer ring of the clutch is connected to the input member 6 as an active component and the other of the inner ring and the outer ring is a passive component, and the one of the inner ring and the outer ring is engaged only when the input member 6 rotates in one direction, allowing the one of the inner ring and the outer ring to transmit torque to the other, and disengaged when the input member 6 changes direction and rotates in the other direction, preventing the one of the inner ring and the outer ring from transmitting torque to the other.

[0025] The first clutch unit 301 is mounted on the fixed shaft 8. Specifically, the inner ring of the first clutch unit 301 is fixed to or formed integrally with the fixed shaft 8, and the outer ring is fixed to or formed integrally with the planet carrier 203. When the first clutch unit 301 is in an engaged state, the planet carrier 203 is locked to the fixed shaft 8 by the first clutch unit 301, and can also be locked to the hub axle O. The inner ring of the second clutch unit 302 is fixed to or formed integrally with the planet carrier 203. The outer ring of the second clutch unit 302 is fixed to or formed integrally with the inner ring (inner hub) of the third clutch unit 70. When the third clutch unit 70 is in an engaged state, the ring gear 201 and the outer ring of the second clutch unit 302 are power-transmittingly connected. When the first clutch unit 301 and the second clutch unit 302 are both in an engaged state, the third clutch unit 70 is disengaged, thereby interrupting the power transmission between the sun gear 202 and the ring gear 201. In this embodiment, the third clutch unit 70 is a friction clutch.

[0026] By using the above configuration, in this embodiment, when the input member 6 rotates toward one circumferential side, one of the first clutch unit 301 and the second clutch unit 302 is engaged, and the other is disengaged. On the other hand, when the input member 6 rotates toward the other circumferential side, one of the first clutch unit 301 and the second clutch unit 302 is disengaged, and the other is engaged. Typical one-way clutches include various known one-way clutches such as a sprag-type one-way clutch, a ratchet wheel-ratchet pawl-type one-way clutch, and a roller-type one-way clutch. The third clutch unit 70 may be any known clutch, for example, a one-way clutch or a two-way clutch.

[0027] As shown in Figure 3, when the transmission 200 is in first gear, the sun gear 202 is driven toward one side in the circumferential direction by the input member 6, the second clutch unit 302 is in a disengaged state, and the first clutch unit 301 is in an engaged state. This prevents the planetary carrier 203 from rotating, and the planetary gears 204 only rotate on their axes without revolving. This causes the ring gear 201 to output a rotational speed reduced relative to the sun gear 202. The ring gear 201 is decelerated to a preset reduction ratio (gear ratio), for example, 1.23. That is, the sun gear 202, which is the power input end, rotates toward the other side in the circumferential direction at a reduction ratio where the rotational speed of the sun gear 202 is 1.23 times the rotational speed of the ring gear 201, which is the power output end.

[0028] As shown in FIG. 4 , when the transmission 200 is in second gear, the sun gear 202 is driven toward the other circumferential side by the input member 6, the first clutch unit 301 is in a disengaged state, and the second clutch unit 302 and the third clutch unit 70 are in an engaged state. As a result, the planetary carrier 203 rotates integrally with the ring gear 201, the planetary gears 204 revolve without rotating on their axes, and the sun gear 202, planetary gears 204, planetary carrier 203, and ring gear 201 rotate integrally toward the other circumferential side. In this case, the reduction ratio (gear ratio) is 1. That is, the ring gear 201 outputs power at a constant speed relative to the sun gear 202. That is, the rotational speed of the sun gear 202, which is the power input end, is the same as the rotational speed of the ring gear 201, which is the power output end.

[0029] 5, when the driving of the input member 6 stops and the vehicle 100 is pushed forward by human power, the ring gear 201 rotates toward the other circumferential direction, the first clutch unit 301 and the second clutch unit 302 are in a disengaged state, and the third clutch unit 70 is in an engaged state. At this time, the ring gear 201 and the hub axle O are not locked. When driven by human power, the ring gear 201 drives the sun gear 202 to rotate.

[0030] 6, when the driving of the input member 6 stops and the vehicle 100 is pushed backward by human power, the ring gear 201 rotates toward one side in the circumferential direction, the first clutch unit 301 and the second clutch unit 302 are in an engaged state, and the third clutch unit 70 is in a disengaged state. At this time, the power transmission connection between the ring gear 201 and the second clutch unit 302 is released, and the ring gear 201 and the hub axle O are not locked. When driven by human power, the ring gear 201 drives the sun gear 202 to rotate.

[0031] The structure of the fixed shaft 8 will be further described below with reference to FIGS.

[0032] As shown in FIG. 2 , the fixed shaft 8 has a hollow structure and supports the input member 6 and the transmission mechanism 7. As shown in FIG. 7 , the fixed shaft 8 includes a large-diameter portion 8a having a larger inner diameter and a small-diameter portion 8b having a smaller inner diameter. The inner diameter of the large-diameter portion 8a is larger than the inner diameter of the small-diameter portion 8b. The large-diameter portion 8a is located to the left of the small-diameter portion 8b. That is, the small-diameter portion 8b is located axially farther from the hub T than the large-diameter portion 8a. One end (the right end in the figure) of the large-diameter portion 8a is connected to the small-diameter portion 8b via a stepped portion 8c. The other end (the left end in the figure) of the large-diameter portion 8a abuts against the inner ring of the bearing 14 for mounting the inner cylindrical portion 11 of the hub T. A protrusion 81 is formed on one end of the small-diameter portion 8b. The other end of the small-diameter portion 8b is connected to the large-diameter portion 8a via the stepped portion 8c. Preferably, the stepped portion 8c is formed in a frustum shape with an inner diameter that gradually narrows radially inward from the large diameter portion 8a to the small diameter portion 8b. There is almost no gap between the small diameter portion 8b and the outer peripheral surface of the hub axle O, and a gap having a constant radial dimension is formed between the inner peripheral surface of the large diameter portion 8a and the outer peripheral surface of the hub axle O. This gap may have the same radial dimension around the entire circumference. This radial dimension may be 0.20 mm or greater.

[0033] As shown in FIG. 2 , the speed change mechanism 7 is disposed radially outward of the large diameter portion 8a so that at least a portion of the speed change mechanism 7 overlaps with the large diameter portion 8a in the axial direction. For example, the sun gear 202 and the large diameter portion 8a are disposed so as to overlap with each other in the axial direction. In this embodiment, the entire speed change mechanism 7 is disposed radially outward of the large diameter portion 8a so as to overlap with the large diameter portion 8a in the axial direction. The first clutch unit 301 is disposed on the outer peripheral surface of the large diameter portion 8a so as to overlap with the large diameter portion 8a in the axial direction. Specifically, the inner ring 301a of the first clutch unit 301 is attached to the outer peripheral surface of the large diameter portion 8a by key fitting, for example, parallel key fitting or spline fitting, or may be fixedly connected to the large diameter portion 8a so as to be integral with each other, for example. The left-hand bearing 16 (the side closest to the hub T) of the pair of bearings 16 is positioned at the outer peripheral surface of the large diameter portion 8a in the axial direction, and the right-hand bearing 16 (the side farther from the hub T) of the pair of bearings 16 is positioned at the outer peripheral surface of the small diameter portion 8b in the axial direction.

[0034] Of the pair of bearings 16, the bearing 16 farthest from the hub T is attached to the outer peripheral surface of the small diameter portion 8 b. The sprocket 61 is disposed radially outward of the small diameter portion 8 b in the axial direction. As such, when viewed radially from the hub axle O, the sprocket 61, the bearing 16 farthest from the hub T, and the small diameter portion 8 b overlap one another.

[0035] The large diameter portion 8a may extend in the axial direction from an end of the fixed shaft 8 that is close to the hub T to a position that is farther from the hub T than the first clutch unit 301. The small diameter portion 8b may extend in the axial direction from an end of the fixed shaft 8 that is farther from the hub T to a position that is closer to the hub T than the sprocket 61. In other words, the step portion 8c formed between the large diameter portion 8a and the small diameter portion 8b is located between the first clutch unit 301 and the sprocket 61 in the axial direction. For example, the large diameter portion 8a may extend in the axial direction from an end of the fixed shaft 8 that is close to the hub T to near the right end of the first clutch unit 301 (imaginary plane S1 in FIG. 7 ). Preferably, the large diameter portion 8a may extend in the axial direction from an end of the fixed shaft 8 that is close to the hub T to near the left bearing 16 (the side closest to the hub T) of the pair of bearings 16 (imaginary plane S2 in FIG. 7 ). More preferably, the large diameter portion 8a extends in the axial direction from the end of the fixed shaft 8 close to the hub T to the vicinity of the right bearing 16 of the pair of bearings 16 (imaginary plane S3 in FIG. 7).

[0036] The configuration and effects of the present embodiment will now be described.

[0037] (1) A transmission device that is attached to an attachment object having a hub axle O, comprising: a hub T; a speed change mechanism 7 that transmits torque from a power source to the hub T; and a fixed shaft 8 that is formed into a hollow structure and supports the speed change mechanism 7, and is fitted onto the hub axle O and cannot rotate relative to the hub axle O, wherein the fixed shaft 8 has a large diameter portion 8a and a small diameter portion 8b, the inner diameter of the large diameter portion 8a is larger than the inner diameter of the small diameter portion 8b, a gap is formed between the inner surface of the large diameter portion 8a and the outer surface of the hub axle O, the small diameter portion 8b is positioned on the side away from the hub T relative to the large diameter portion 8a in the axial direction of the hub axle O, and the speed change mechanism 7 is positioned radially outward of the large diameter portion 8a so that at least a portion of the speed change mechanism 7 overlaps with the large diameter portion 8a in the axial direction.

[0038] According to this configuration, the gap can be used to absorb deformation of the hub axle O, so that even if the hub axle O is deformed, the effect on the speed change mechanism 7 can be suppressed.

[0039] (2) The transmission mechanism 7 includes a planetary gear mechanism 20, which has a sun gear 202, a plurality of planetary gears 204, a planetary carrier 203 connecting the plurality of planetary gears 204, and a ring gear 201, and the sun gear 202 and the large diameter portion 8a are arranged so as to overlap in the axial direction.

[0040] According to this configuration, when the sun gear 202 is attached to the large diameter portion 8a of the fixed shaft 8, the effect of deformation of the hub axle O on the sun gear 202 can be suppressed, and the probability of failure of the planetary gear mechanism 20 can be reduced.

[0041] (3) The transmission mechanism 7 further includes a first clutch unit 301 and a second clutch unit 302. When the sun gear 202 is driven to rotate in one circumferential direction, the first clutch unit 301 engages to lock the planet carrier 203 and the fixed shaft 8, and when the sun gear 202 is driven to rotate in the other circumferential direction, the second clutch unit 302 engages to rotate the planetary gear mechanism 20 integrally.

[0042] This configuration suppresses the effect of deformation of the hub axle O on the first clutch unit 301, thereby reducing the probability of the first clutch unit 301 failing.

[0043] (4) Further provided is an input member 6 supported on a fixed shaft 8 and transmitting torque from the power source to the transmission mechanism 7, the transmission mechanism 7 being arranged axially on the side closer to the hub T than the input member 6, the sun gear 202 being connected to the input member 6 in a transmission manner, and the ring gear 201 being connected to the hub T in a transmission manner.

[0044] This configuration suppresses the effect of deformation of the hub axle O on the input member 6, reducing the probability of failure of the input member 6. Furthermore, the space near the hub T can be utilized to house the transmission device 200, making the transmission device 200 smaller and more compact.

[0045] (5) The first clutch unit 301 is arranged on the side of the sun gear 202 closer to the hub T in the axial direction, and the first clutch unit 301 is arranged on the outer surface of the large diameter portion 8a so as to overlap with the large diameter portion 8a in the axial direction.

[0046] This configuration further reduces the effect of deformation of the hub axle O on the first clutch unit 301, thereby reducing the probability of the first clutch unit 301 failing.

[0047] (6) The input member 6 further includes a sprocket 61 and a transmission sleeve 62 fitted onto the fixed shaft 8, the sprocket 61 being fixed to the transmission sleeve 62, and the sprocket 61 and the small diameter portion 8b being arranged to overlap in the axial direction.

[0048] With this configuration, the fixed shaft 8 can be prevented from deflecting in the axial direction, and by supporting the transmission sleeve 62 with the small diameter portion 8b, the sprocket 61 can be limited to an appropriate position, preventing the chain 5 connected to the sprocket 61 from falling off the sprocket 61 or preventing torque from being transmitted improperly.

[0049] (7) The transmission sleeve 62 is attached to the fixed shaft 8 by a pair of first bearings 16, and of the pair of first bearings 16, the first bearing 16 farthest from the hub T is attached to the outer peripheral surface of the small diameter portion 8b.

[0050] This configuration can further suppress deflection of the fixed shaft 8 in the axial direction.

[0051] (8) The sprocket 61, the first bearing 16 located away from the hub T, and the small diameter portion 8b overlap with each other in the axial direction.

[0052] This configuration reliably suppresses deflection of the fixed shaft 8 in the axial direction, thereby reducing the probability of failure of the sprocket 61.

[0053] (9) The transmission sleeve 62 includes a cylindrical portion 621 and a flange portion 622 formed integrally, the cylindrical portion 621 extending along the axial direction, the sprocket 61 attached to the flange portion 622, and the sun gear 202 attached to the end of the cylindrical portion 621 opposite the sprocket 61.

[0054] This configuration suppresses the effect of deformation of the hub axle O on the sun gear 202, reducing the probability of failure of the planetary gear mechanism 20. In addition, there is no need to specially design the sun gear 202, allowing for the use of general-purpose components.

[0055] (10) The gap has the same radial dimension around the entire circumference, and the radial dimension is set to 0.20 mm or more.

[0056] With this configuration, deformation of the hub axle O can be reliably absorbed by utilizing the gap.

[0057] (11) The hub T has an inner tube portion 11 provided radially inward, an outer tube portion 12 provided radially outward, and a connecting portion 13 connecting the inner tube portion 11 and the outer tube portion 12, and the inner tube portion 11 is attached to the hub axle O by a second bearing 14, and the fixed shaft 8 abuts against the inner ring of the second bearing 14.

[0058] According to this configuration, deflection of the fixed shaft 8 in the axial direction can be suppressed, and the fixed shaft 8 can restrict the position of the second bearing 14 in the axial direction.

[0059] (12) The vehicle 100 comprises a transmission device 200, a chassis as an attachment object, and front wheels 1 and rear wheels 2 provided on the chassis, and the power source is attached to the chassis and positioned between the front wheels 1 and rear wheels 2 in the fore-and-aft direction of the vehicle 100, and the torque output from the power source can drive the front wheels 1 or rear wheels 2 via the transmission device 200.

[0060] According to this configuration, the fixed shaft 8 is formed with a hollow structure, supports the speed change mechanism 7, and is fitted onto the hub axle O so as to be unable to rotate relative to the hub axle O. The fixed shaft 8 includes a large diameter portion 8a and a small diameter portion 8b. The inner diameter of the large diameter portion 8a is larger than the inner diameter of the small diameter portion 8b. A gap is formed between the inner circumferential surface of the large diameter portion 8a and the outer circumferential surface of the hub axle O. In the axial direction of the hub axle O, the small diameter portion 8b is positioned on the side farther from the hub T than the large diameter portion 8a. The speed change mechanism 7 is positioned radially outward of the large diameter portion 8a so that at least a portion of the speed change mechanism 7 overlaps with the large diameter portion 8a in the axial direction. This allows deformation of the hub axle O to be absorbed by utilizing the gap, thereby limiting the impact on the speed change mechanism 7 even if the hub axle O is deformed and reducing the probability of the speed change mechanism 7 failing.

[0061] Although an embodiment of the present invention has been described above, the above embodiment merely shows one application example of the present invention, and is not intended to limit the technical scope of the present invention to the specific configuration of the above embodiment.

[0062] For example, in the specific embodiment described above, the vehicle 100 is an electric two-wheeled vehicle, but the present invention is not limited thereto. In another preferred technical means, the vehicle 100 may be an electric three-wheeled vehicle, in which case the front wheels may be drive wheels and a transmission may be provided on the front wheels.

[0063] In addition, in the above specific embodiment, the transmission device is a two-speed transmission device, but is not limited to this. In other preferred technical means, the transmission mechanism may be provided with three or more speeds, or may be provided with one speed.

[0064] In the specific embodiment described above, the reduction ratio is 1.23 in the first gear stage. However, it goes without saying that the reduction ratio can be adjusted by setting a different gear ratio.

[0065] REFERENCE SIGNS LIST 100 Vehicle 1 Front wheel 2 Rear wheel 3 Pedal 4 Seat 5 Chain 10 Tire 101 Support frame 200 Transmission device T Hub 11 Inner cylindrical portion 12 Outer cylindrical portion 13 Connecting portion 14 Bearing 16 Bearing O Hub shaft 6 Input member 61 Sprocket 62 Transmission sleeve 621 Cylindrical portion 622 Flange portion 623 Step portion 63 Connecting member 7 Transmission mechanism 20 Planetary gear mechanism 201 Ring gear 202 Sun gear 203 Planet carrier 204 Planetary gear 205 Housing 301 First clutch unit 302 Second clutch unit 70 Third clutch unit 8 Fixed shaft 81 Projection portion 8a Large diameter portion 8b Small diameter portion 8c Step portion S1 Virtual surface S2 Virtual surface S3 Virtual surface

Claims

1. A transmission device that is attached to an attachment object having a hub axle (O), comprising: a hub (T); a speed change mechanism (7) that transmits torque from a power source to the hub (T); and a fixed shaft (8) that is formed into a hollow structure and supports the speed change mechanism (7), and is fitted onto the hub axle (O) and cannot rotate relative to the hub axle (O), wherein the fixed shaft (8) has a large diameter portion (8a) and a small diameter portion (8b), the inner diameter of the large diameter portion (8a) is larger than the inner diameter of the small diameter portion (8b), a gap is formed between the inner peripheral surface of the large diameter portion (8a) and the outer peripheral surface of the hub axle (O), and the small diameter portion (8b) is located on the side of the large diameter portion (8a) that is farther from the hub (T) in the axial direction of the hub axle (O), The transmission device, wherein the speed change mechanism (7) is disposed radially outward of the large diameter portion (8a) so that at least a portion of the speed change mechanism (7) overlaps with the large diameter portion (8a) in the axial direction.

2. A transmission device according to claim 1, wherein the speed change mechanism (7) includes a planetary gear mechanism (20), the planetary gear mechanism (20) having a sun gear (202), a plurality of planetary gears (204), a planet carrier (203) connecting the plurality of planetary gears (204), and a ring gear (201), and the sun gear (202) and the large diameter portion (8a) are arranged to overlap in the axial direction.

3. A transmission device according to claim 2, wherein the speed change mechanism (7) further includes a first clutch unit (301) and a second clutch unit (302), and when the sun gear (202) is driven to rotate in one circumferential direction, the first clutch unit (301) engages to lock the planet carrier (203) and the fixed shaft (8), and when the sun gear (202) is driven to rotate in the other circumferential direction, the second clutch unit (302) engages to rotate the planetary gear mechanism (20) integrally.

4. A transmission device according to claim 3, further comprising an input member (6) supported on the fixed shaft (8) and transmitting torque from the power source to the speed change mechanism (7), the speed change mechanism (7) being disposed on the side of the input member (6) closer to the hub (T) in the axial direction, the sun gear (202) being connected to the input member (6) for transmission purposes, and the ring gear (201) being connected to the hub (T) for transmission purposes.

5. A transmission device according to claim 3 or 4, wherein the first clutch unit (301) is arranged on a side of the sun gear (202) closer to the hub (T) in the axial direction, and the first clutch unit (301) is arranged on the outer circumferential surface of the large diameter portion (8a) so as to overlap with the large diameter portion (8a) in the axial direction.

6. A transmission device according to claim 4, wherein the input member (6) further includes a sprocket (61) and a transmission sleeve (62) fitted onto the fixed shaft (8), the sprocket (61) is fixed to the transmission sleeve (62), and the sprocket (61) and the small diameter portion (8b) are arranged to overlap in the axial direction.

7. A transmission device according to claim 6, wherein the transmission sleeve (62) is attached to the fixed shaft (8) by a pair of first bearings (16), and the first bearing (16) of the pair of first bearings (16) that is farther from the hub (T) is attached to the outer circumferential surface of the small diameter portion (8b).

8. A transmission device according to claim 7, wherein the sprocket (61), the first bearing (16) remote from the hub (T), and the small diameter portion (8b) overlap each other in the axial direction.

9. A transmission device according to claim 6, wherein the transmission sleeve (62) includes an integrally formed cylindrical portion (621) and a flange portion (622), the cylindrical portion (621) extends along the axial direction, the sprocket (61) is attached to the flange portion (622), and the sun gear (202) is attached to the end of the cylindrical portion (621) opposite to the sprocket (61).

10. A transmission device according to any one of claims 1 to 3, wherein the gap has the same radial dimension over the entire circumference, and the radial dimension is set to 0.20 mm or more.

11. A transmission device according to any one of claims 1 to 3, wherein the hub (T) has an inner cylindrical portion (11) provided radially inward, an outer cylindrical portion (12) provided radially outward, and a connecting portion (13) connecting the inner cylindrical portion (11) and the outer cylindrical portion (12), wherein the inner cylindrical portion (11) is attached to the hub axle (O) by a second bearing (14), and the fixed shaft (8) abuts against the inner ring of the second bearing (14).

12. A vehicle comprising: a transmission device (200) according to any one of claims 1 to 11; a chassis as the mounting object; and front wheels (1) and rear wheels (2) provided on the chassis, wherein the power source is mounted on the chassis and positioned between the front wheels (1) and the rear wheels (2) in the fore-and-aft direction of the vehicle (100), and the torque output from the power source can drive the front wheels (1) or the rear wheels (2) via the transmission device (200).

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