Hubs and electric vehicles

Abstract

A hub that is positioned in the center of a wheel, said hub having: a hub shaft that extends along a center axis; a hub body that is rotatably positioned on the hub shaft; a stator that has a coil; a rotor that has a rotor shaft extending along the center axis; and a lead wire that is electrically connected to a conductive wire. The rotor shaft is connected to the hub body. The hub shaft has a through-hole that penetrates from an end section on one side in the axial direction to an outer circumferential surface. The through-hole has a first opening that is formed in the outer circumferential surface of the hub shaft. The lead wire is positioned in the through-hole. An end section of the first opening on one side in the axial direction and an end section of the same on the other side in the axial direction are in different locations in a circumferential direction that is based on the center axis.

Description

[Technical Field]

[0001] The present invention relates to a hub disposed at the center of a wheel of an electric vehicle, and to an electric vehicle including the hub. [Background technology]

[0002] A conventional hub has a rotor and a stator with a coil. This type of hub has wiring connected to the coil. The hub also has a hub axle with a wiring passage that opens at its tip. The wiring passes through the wiring passage and is pulled out from the end of the hub axle. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication: JP 2005-75106 A Summary of the Invention [Problem to be solved by the invention]

[0004] In the above-described hub, the wiring must be routed through a wiring passage formed along the hub axle, which can make installation of the wiring difficult. Also, if the wiring is routed out from the end of the hub axle, the wiring route becomes long.

[0005] SUMMARY OF THE INVENTION An object of the present invention is to provide a hub to which leads can be easily attached. [Means for solving the problem]

[0006] An exemplary hub of the present invention is disposed at the center of a wheel. The hub includes a hub shaft extending along a central axis and protruding outward on one axial side; a cylindrical hub body extending in the axial direction and rotatably disposed on the hub shaft; a stator having a coil formed by winding a conductor and disposed inside the hub body; a rotor having a rotor shaft extending along the central axis, facing the stator in the radial or axial direction and disposed rotatably relative to the stator; and lead wires electrically connected to the conductor wires. The rotor shaft is connected to the hub body. The hub shaft has a through hole penetrating from an end on the other axial side to its outer circumferential surface. The through hole has a first opening formed in the outer circumferential surface of the hub shaft, and the lead wires are disposed in the through hole. The end on one axial side of the first opening and the end on the other axial side are at different circumferential positions relative to the central axis. [Effects of the Invention]

[0007] The exemplary hub of the present invention allows for easy attachment of lead wires. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a schematic diagram of an electric vehicle according to an embodiment of the present invention. [Figure 2] FIG. 2 is a perspective view of a hub attached to a front fork. [Figure 3] FIG. 3 is a cross-sectional view of the hub taken along a vertical plane and viewed from the front. [Figure 4] FIG. 4 is a perspective view of the right hub shaft as seen from below and in front. [Figure 5] FIG. 5 is a perspective view of the right hub shaft with the lead wires removed, as seen from below and in front. [Figure 6] FIG. 6 is a bottom view of the right hub shaft. [Figure 7] FIG. 7 is a rear view of the right hub shaft. [Figure 8] FIG. 8 is a view seen from the right side in the direction along the center axis of the right hub shaft. [Figure 9] FIG. 9 is a view seen from the left side along the center axis of the right hub shaft. [Figure 10] FIG. 10 is a perspective view of the right hub shaft of the first modified example, as viewed from below and in front. [Figure 11] FIG. 11 is a view seen from the right side in the direction along the center axis of the right hub shaft. DETAILED DESCRIPTION OF THE INVENTION

[0009] An exemplary embodiment of the present invention will be described in detail below with reference to the drawings. In the description of the hub 10, the direction parallel to the central axis J1 of the hub 10 shown in FIG. 1 will be referred to as the "axial direction." Furthermore, the direction perpendicular to the central axis of each rotatable shaft will be referred to as the "radial direction," and the direction along an arc centered on the central axis will be referred to as the "circumferential direction." Furthermore, the traveling direction of the electric vehicle 100 is defined as "forward F" when the hub 10 is mounted on the electric vehicle 100. Furthermore, one side of the direction along the central axis J1 with the hub 10 at the center will be defined as the right R, and the other side will be defined as the left L. Note that the directions in the following description are defined for ease of explanation and may not match the directions of the hub 10 when actually used.

[0010] Fig. 1 is a schematic diagram of an electric vehicle according to an embodiment of the present invention. In this embodiment, the electric vehicle 100 is an electrically assisted bicycle that assists the user in pedaling 106. As shown in Fig. 1, the electric vehicle 100 has a body 101, two wheels 102, a power transmission mechanism 103, and a power supply unit 104.

[0011] The body 101 includes a handlebar 107 and a saddle 108. Two wheels 102, a power transmission mechanism 103, and a power supply unit 104 are attached to the body 101. The two wheels 102 are attached to the front of the body 101 as a front wheel 102f and to the rear of the body 101 as a rear wheel 102r. The power transmission mechanism 103 is connected to the rear wheel 102r. A hub 10 is disposed in the center of the front wheel 102f.

[0012] The power transmission mechanism 103 includes a crank 105 attached to a crankshaft 105a, and pedals 106. The power transmission mechanism 103 also includes a drive gear, a driven gear attached to the rear wheel 102r, and a chain (none of which are shown) that connects the drive gear and the driven gear. The crank 105 is fixed to the crankshaft 105a that is rotatably attached to the vehicle body 101. Furthermore, a pedal 106 is rotatably attached to the tip of the crank 105.

[0013] The power supply unit 104 is attached to the vehicle body 101. The power supply unit 104 is, for example, a battery, and is built into the vehicle body 101 as shown in Fig. 1. However, the power supply unit 104 is not limited to this, and a wide variety of configurations can be adopted in which the power supply unit 104 is attached to the vehicle body 101 and can supply power to the hub 10.

[0014] In the electric vehicle 100, a user seated on a saddle 108 steps on pedals 106, which applies torque to the crankshaft 105a. The torque applied to the crankshaft 105a is transmitted to the rear wheel 102r via the power transmission mechanism 103. The transmitted torque rotates the rear wheel 102r, causing the electric vehicle 100 to travel.

[0015] In the electric vehicle 100, the hub 10 is attached to the lower end of a front fork Fk, which is part of the vehicle body 101 (see FIG. 2, which will be described later). The front fork Fk has a hub attachment portion Fk1 at its lower end, which is a concave hub attachment portion that opens downward. The hub 10 has a second shaft portion 112 of a hub shaft 11, which will be described later and which protrudes from both the left and right ends, disposed in the hub attachment portion Fk1. A nut Nt is then attached to and tightened onto a male thread (not shown) formed on the outer circumferential surface of the second shaft portion 112. This attaches the hub 10 to the front fork Fk (see FIG. 2, which will be described later).

[0016] Fig. 2 is a perspective view of the hub 10 attached to the front fork Fk. Fig. 3 is a cross-sectional view of the hub 10 cut along a vertical plane and viewed from the front F.

[0017] The hub 10 is disposed at the center of the front wheel 102f and is connected to an annular rim Rm (see FIG. 1) included in the front wheel 102f via spokes Sp (see FIG. 1). When power is supplied to the hub 10, the motor unit 20 housed therein is driven. The front wheel 102f is driven by the torque of the motor unit 20. In other words, in this embodiment, the hub 10 is a drive device for the electric vehicle 100.

[0018] The hub 10 is not limited to being disposed on the front wheel 102f, but may be disposed on the rear wheel 102r, or may be disposed on both the front wheel 102f and the rear wheel 102r. In other words, the hub 10 is disposed in the center of the wheel 102.

[0019] The hub 10 includes a hub shaft 11, a hub body 12, a motor unit 20, and a reduction mechanism 30. In the hub 10, the hub shaft 11 protrudes to the right R and left L in the axial direction.

[0020] The motor unit 20 is a DC brushless motor. The motor unit 20 is driven by power from the power supply unit 104. The motor unit 20 has a stator 21 and a rotor 25. The stator 21 and a portion of the rotor 25 are disposed inside the housing 50. The motor unit 20 is an inner rotor type motor in which the rotor 25 is disposed radially inward of the stator 21. Note that the motor unit 20 is not limited to an inner rotor type motor, and may also be an outer rotor type motor. Alternatively, the motor unit 20 may be a so-called axial gap motor in which the stator and rotor are disposed axially opposite each other.

[0021] The stator 21 has a stator core 22, a coil 23, and an insulator 24. The stator 21 is held in the housing 50. The stator core 22 has a core back 221 and a plurality of teeth 222. The core back 221 is annular. A radially outer surface of the core back 221 is fixed to the housing 50. The teeth 222 protrude from a radially inner surface of the core back 221 in a direction approaching the central axis J1. The plurality of teeth 222 are arranged at equal intervals in the circumferential direction. The insulator 24 covers at least the teeth 222. The insulator 24 has insulating properties. The coil 23 is formed by winding a conductive wire around the teeth 222 covered by the insulator 24. That is, the stator 21 has the coil 23 formed by winding a conductive wire.

[0022] The rotor 25 has a rotor shaft 26, a rotor core 27, and a rotor magnet 28. The rotor shaft 26 is generally cylindrical. As shown in FIG. 3, the rotor shaft 26 extends along the central axis J1. That is, the motor section 20 has the rotor shaft 26 extending along the central axis J1, and the rotor 25 arranged radially opposite the stator 21 and rotatably relative to the stator 21. The rotor shaft 26 is rotatable around the central axis J1.

[0023] The rotor shaft 26 is rotatably supported by the housing 50 via shaft bearings 261. The shaft bearings 261 are arranged at two locations spaced apart in the axial direction, and rotatably support the rotor shaft 26 at the two locations spaced apart in the axial direction. Here, the shaft bearings 261 are ball bearings, but are not limited to this. Any bearing structure that can smoothly and accurately support the rotor shaft 26 can be widely adopted.

[0024] The rotor 25 is fixed to the outer periphery of the rotor shaft 26. The rotor 25 has a rotor core 27 and a rotor magnet 28. The rotor 25 rotates about a central axis J1 that extends in the horizontal direction.

[0025] The rotor core 27 is formed by laminating thin electromagnetic steel plates. The rotor core 27 is a cylindrical body extending along the axial direction. The rotor core 27 may also be formed by sintering magnetic powder. A plurality of rotor magnets 28 are fixed to the rotor core 27. The plurality of rotor magnets 28 are arranged in the circumferential direction with their magnetic poles alternating.

[0026] As shown in Figures 2 and 3, the housing 50 is cylindrical. The housing 50 has a first housing portion 51 and a second housing portion 52. The first housing portion 51 is a bottomed cylindrical portion having a bottom 511 on the right side R in the axial direction and an opening on the left side L. In other words, it has an opening facing the left side L. The second housing portion 52 is a bottomed cylindrical portion having a bottom 521 on the left side L in the axial direction and an opening on the right side R. In other words, it has an opening facing the right side R.

[0027] The opening in the first housing part 51 holds the right end portion of the stator 21 in the axial direction. The opening in the second housing part 52 holds the left end portion of the stator 21 in the axial direction. The first housing part 51 and the second housing part 52 are arranged apart in the axial direction. More specifically, the first housing part 51 and the second housing part 52 are attached to the stator 21 at intervals in the axial direction.

[0028] More specifically, the rotor shaft 26 is rotatably supported by the bottom 511 of the first housing part 51 and the bottom 521 of the second housing part 52 via shaft bearings 261. The left end L of the rotor shaft 26 in the axial direction passes through a through-hole 522 formed in the bottom 521 of the second housing part 52. A sun gear part 31 (described later) of the reduction mechanism 30 is disposed in a part of the rotor shaft 26 that protrudes to the left L beyond the bottom 521 of the second housing part 52.

[0029] Auxiliary devices such as a bus bar 29 are attached to the right end R of the motor unit 20. The bus bar 29 is a conductive member to which the conductor wire of the coil 23 is connected. A lead wire 40 is connected to the bus bar 29. A current is supplied to the coil 23 from the power supply unit 104 via the lead wire 40 and the bus bar 29. In other words, the lead wire 40 is electrically connected to the conductor wire of the coil 23.

[0030] The motor unit 20 is driven by power supplied from the power supply unit 104. That is, when current is supplied from the power supply unit 104 to the coils 23, the coils 23 are excited. When the coils 23 are excited, a magnetic force is generated between the coils 23 and the rotor magnet 28 of the rotor 25. When the multiple coils 23 are excited at appropriate times, a torque is generated in the rotor 25 in the circumferential direction about the central axis J1. This torque causes the rotor shaft 26 to rotate around the central axis J1.

[0031] 3, the speed reduction mechanism 30 has a sun gear unit 31, a planetary gear unit 32, an internal gear unit 33, and a torque limiter 34. The speed reduction mechanism 30 uses a so-called planetary gear mechanism to reduce the speed of rotation of the rotor shaft 26 and transmit the rotation to the hub body 12.

[0032] As shown in FIGS. 3 to 5, the sun gear section 31 is disposed at the left end L of the rotor shaft 26 in the axial direction. The sun gear section 31 rotates integrally with the rotor shaft 26. Therefore, the sun gear section 31 may be formed as a single member together with the rotor shaft 26, or may be attached to the rotor shaft 26 and fixed by a fixing method such as adhesive, welding, screwing, caulking, or press fitting. Fixing methods other than these may also be used. Furthermore, a wide variety of fixing methods may be used that can fix the sun gear section 31 to be rotatable integrally with the rotor shaft 26.

[0033] As shown in FIG. 3 , the reduction mechanism 30 has a plurality of planetary gear portions 32. The number of planetary gear portions 32 can be, but is not limited to, three or four. The plurality of planetary gear portions 32 are arranged in the circumferential direction. The plurality of planetary gear portions 32 are arranged side by side at equal intervals in the circumferential direction. The planetary gear portions 32 mesh with the sun gear portion 31. Note that the reduction mechanism 30 of this embodiment has three planetary gear portions 32, but the number is not limited to three. It is sufficient that the reduction mechanism 30 has two or more planetary gear portions 32. The arrangement of the planetary gear portions 32 in the circumferential direction is not limited to equal intervals. In other words, the plurality of planetary gear portions 32 mesh with the sun gear portion 31 and are arranged in the circumferential direction.

[0034] The planetary gear unit 32 will be further described. The planetary gear unit 32 has a first planetary gear 321 and a second planetary gear 322. More specifically, the planetary gear unit 32 has a planet shaft 320, a first planetary gear 321, and a second planetary gear 322. The planetary shaft 320 extends along a planetary axis J2 that is parallel to the central axis J1. As shown in FIG. 3 , the right end of the planetary shaft 320 in the axial direction is fixed to the bottom portion 521 of the second housing portion 52. The upper end of the planetary shaft 320 is fixed to the left hub shaft 11L. In other words, the position of the planetary shaft J2 of the planetary gear unit 32 with respect to the central axis J1 is fixed.

[0035] The first planetary gear 321 and the second planetary gear 322 are rotatably supported on a planetary shaft 320. The first planetary gear 321 and the second planetary gear 322 are axially connected to each other. The second planetary gear 322 rotates integrally with the first planetary gear 321. In other words, the planetary gear unit 32 is a two-stage gear. However, the planetary gear unit 32 is not limited to a two-stage gear. The planetary gear unit 32 may be a multi-stage gear with three or more stages, or may be configured to have only a single diameter gear, i.e., a gear with a predetermined number of teeth. The first planetary gear 321 and the second planetary gear 322 may be formed from a single member, or may be combined in the axial direction and fixed using a fixing method such as adhesive, welding, or screwing.

[0036] The internal gear portion 33 is an annular 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. The internal gear portion 33 is cylindrical, and a torque limiter 34 is disposed at the end portion on the left side L in the axial direction. The torque limiter 34 comes into contact with the inner peripheral surface of the internal gear portion 33.

[0037] The torque limiter 34 has a torque limiter outer ring 341 and a torque limiter inner ring 342. The torque limiter outer ring 341 rotates integrally with the internal gear portion 33 around the central axis J1. The torque limiter inner ring 342 rotates integrally with the hub body lid portion 122 of the hub body 12. In the torque limiter 34, when the torque limiter inner ring 342 rotates in the rotation direction Rt of the front wheel 102f, the rotation of the torque limiter outer ring 341 is transmitted to the torque limiter inner ring 342.

[0038] In the hub 10 of this embodiment, a planetary gear mechanism is used as the reduction mechanism 30, but the present invention is not limited to this. A wide variety of configurations that can reduce the rotation of the motor unit 20 can be used. Furthermore, the rotor shaft 26 of the motor unit 20 may be connected to the hub body 12 directly or via a torque limiter. The rotor shaft 26 is connected to the hub body 12 directly or indirectly. That is, the rotor shaft 26 is connected to the hub body 12.

[0039] The hub 10 has two hub shafts 11. In the following explanation, the hub shaft 11 on the right side R will be referred to as the right hub shaft 11R, and the hub shaft 11 on the left side will be referred to as the left hub shaft 11L, as necessary. The centers of the hub shafts 11 overlap with the central axis J1. In other words, the hub shaft 11R extends along the central axis J1 and protrudes outward on one axial side.

[0040] First, the common structure of the right hub shaft 11R and the left hub shaft 11L will be described. The hub shaft 11 has a first shaft portion 111, a second shaft portion 112, and a flange portion 113. The first shaft portion 111 is cylindrical and centered on the central axis J1, and extends along the central axis J1. In other words, the hub shaft 11R has the columnar first shaft portion 111 that extends along the central axis J1.

[0041] The second shaft portion 112 has a cylindrical shape centered on the central axis J1. The outer diameter of the second shaft portion 112 is smaller than the outer diameter of the first shaft portion 111. The second shaft portion 112 extends along the central axis J1 from one side of the first shaft portion 111 in the direction along the central axis J1, that is, from the outer end face along the central axis J1 in FIG. 3. In other words, the hub shaft 11R has the columnar second shaft portion 112 that protrudes in the direction along the central axis J1 from one axial end of the first shaft portion 111. The second shaft portion 112 has a smaller diameter than the first shaft portion 111. A male thread (not shown) is formed on the outer peripheral surface of the second shaft portion 112.

[0042] The flange portion 113 extends radially outward from the other side of the first shaft portion 111 in the direction along the central axis J1, i.e., from the outer peripheral surface along the central axis J1 in FIG. 3. The flange portion 113 is annular. The motor portion 20 is fixed to the flange portion 113.

[0043] Both the right hub shaft 11R and the left hub shaft 11L have the configuration described above. The right hub shaft 11R and the left hub shaft 11L are integrally molded, but this is not limiting and some parts may be formed separately. For example, the second shaft portion 112 may be formed in a cylindrical shape and the first shaft portion 111 may be fixed by a fixing method such as press fitting. Other configurations are also possible. In the hub 10, the centers of the right hub shaft 11R and the left hub shaft 11L each coincide with the central axis J1. In other words, the right hub shaft 11R and the left hub shaft 11L have the same central axis J1 and are arranged apart in the direction of the central axis J1.

[0044] The flange portion 13 of the right hub shaft 11R is fixed to the bottom portion 511 of the first housing portion 51. The flange portion 13 of the left hub shaft 11L is fixed to the bottom portion 521 of the second housing portion 52 via the planetary shaft 320. In this way, the stator 21 of the motor portion 20 is fixed to the hub shaft 11.

[0045] Next, we will explain the configuration included only in the right hub shaft 11R. The hub 10 has a lead wire 40 that connects the motor unit 20 housed inside with an external control unit (not shown). As shown in FIG. 3, in the hub 10, the lead wire 40 is pulled out from the right side of the hub 10, i.e., from the right hub shaft 11R. Note that in the hub 10 of this embodiment, the lead wire 40 is pulled out from the right side, but this is not limited thereto and it may be pulled out from the left side. In this case, the right hub shaft 11R and the left hub shaft 11L are interchanged.

[0046] Fig. 4 is a perspective view of the right hub shaft 11R as seen from below and in front. Fig. 5 is a perspective view of the right hub shaft 11R with the lead wires removed as seen from below and in front. Fig. 6 is a bottom view of the right hub shaft 11R. Fig. 7 is a rear view of the right hub shaft 11R. Fig. 8 is a view of the right hub shaft 11R as seen from the right side in the direction along the center axis J1. Fig. 9 is a view of the right hub shaft 11R as seen from the left side in the direction along the center axis J1. In Fig. 8, part of the front fork Fk is indicated by a dashed line.

[0047] As shown in FIGS. 5 to 7, the right hub shaft 11R has a through hole 114 and a first protrusion 115. The first protrusion 115 protrudes rightward from the right end of the first shaft portion 111. As shown in FIG. 5, the first protrusion 115 connects to the outer peripheral surface of the second shaft portion 112. That is, the first protrusion 115 protrudes axially from one axial end of the first shaft portion 111 and is disposed on the radially outer peripheral side of the second shaft portion 112. In this embodiment, the first protrusion 115 is formed of a single member together with both the first shaft portion 111 and the second shaft portion 112. Note that the first protrusion 115 may be formed separately from the first shaft portion 111 or the second shaft portion 112 and fixed by a fixing method such as welding or screwing.

[0048] The through hole 114 penetrates from the left end of the right hub shaft 11R in the direction along the center axis J1 toward the outer circumferential surface. In other words, the hub shaft 11R has a through hole 114 that penetrates from the other axial end to the outer circumferential surface. In the hub 10, the lead wire 40 is disposed in the through hole 114.

[0049] The through hole 114 has a first opening 116 and a second opening 117 at both axial ends. That is, the through hole 114 has the first opening 116 formed in the outer peripheral surface of the hub shaft 11R.

[0050] 5 to 7, the first opening 116 is formed in the outer circumferential surface of the first shaft portion 111, the right end face along the central axis J1, and the outer circumferential surface of the second shaft portion 112. That is, parts of the first opening 116 are formed in the outer circumferential surfaces of the first shaft portion 111 and the second shaft portion 112, and the outer surface of the first protrusion 115.

[0051] The right hub shaft 11R has the first protrusion 115, which increases the rigidity of the right hub shaft 11R. Furthermore, because the first protrusion 115 is attached in contact with the front fork Fk, it is possible to prevent the hub 10 from shifting position relative to the front fork Fk. Furthermore, because the first opening 116 is formed in the first protrusion 115, it is possible to lengthen the through hole 114, which allows the lead wire 40 to be stably held.

[0052] 6, the right end 1162 and the left end 1163 of the first opening 116 in the direction along the central axis J1 are positioned at different circumferential positions. That is, the end 1162 on one axial side of the first opening 116 and the end 1163 on the other axial side are positioned at different circumferential positions relative to the central axis J1.

[0053] With this configuration, the first opening 116 can be made larger than when the opening through which the lead wire 40 is pulled out is formed along the axial direction. This makes it easier to pull out the lead wire 40. Furthermore, since the first opening 116 is larger, the range of movement of the lead wire 40 increases, making it easier to handle the pulled-out lead wire 40. As a result, it is possible to attach the hub 10 to front forks Fk of different shapes.

[0054] 8, the first protrusion 115 is located rearward of the first opening 116 in the rotational direction Rt of the wheel 102f. In the hub 10, the hub body 12 rotates in the rotational direction Rt due to the torque output from the motor unit 20. At this time, a reaction force acts on the right hub shaft 11R in the direction opposite to the rotational direction Rt.

[0055] At this time, the first protrusion 115 of the right hub shaft 11R is pressed against the hub mounting portion Fk1 of the front fork Fk. By providing the first protrusion 115 to the right hub shaft 11R, the rigidity of the portion of the right hub shaft 11R that comes into contact with the hub mounting portion Fk1 can be increased. This makes it possible to receive the reaction force generated when the wheel 102f rotates, and to firmly fix the right hub shaft 11R to the front fork Fk.

[0056] 8, a part of first opening 116 is formed at one axial end of first shaft portion 111, and the portion of first opening 116 formed in first shaft portion 111 has a curved portion 1161 that curves outward at the periphery. By having curved portion 1161 in this manner, lead wire 40 is less likely to be damaged when it comes into contact with curved portion 1161 of first opening 116.

[0057] The through hole 114 has a first opening 116 and a second opening 117 at both ends. The second opening 117 is formed at the end of the flange portion 113 on the left side L in the axial direction. In other words, the through hole 114 has the second opening 117 that opens to the other axial side of the hub shaft 11R.

[0058] 8, when viewed in a direction along the central axis J1, the first opening 116 has a portion that overlaps with the second opening 117 in the axial direction. With this configuration, when wiring the lead wire 40 in the through hole 114, the lead wire 40 can be checked and wired. Therefore, the lead wire 40 can be wired in the through hole 114 reliably.

[0059] 9, the second opening 117 is positioned radially offset with respect to the central axis J1. In other words, when viewed from the direction of the central axis J1, the center of the second opening 11 is at a different position from the central axis J1. This configuration makes it easy to connect the lead wires 40 to the bus bars 29 that connect the lead wires 40 to the coils 23 positioned radially outward of the rotor shaft 26. This makes it easier to manufacture the hub 10.

[0060] A part of the first opening 116 is formed in the outer peripheral surface of the first shaft portion 111. The length L1 from one axial end of the first opening 116 formed in the outer peripheral surface of the first shaft portion 111 to the other axial end thereof may be shorter than the axial length L2 of the first protrusion 115.

[0061] By increasing the axial length L2 of the first protrusion 115, it is possible to lengthen the guide for the lead wire 40. This allows the lead wire 40 to be stably routed along the right hub shaft 11R.

[0062] The hub body 12 is rotatably supported on the hub shaft 11 via a hub bearing Br. The hub body 12 is rotatably disposed on the hub shaft 11 and has a cylindrical shape extending in the axial direction. The hub body 12 has a case portion 121 and a hub body lid portion 122. The case portion 121 is cylindrical with a bottom and extends along the central axis J1.

[0063] The case portion 121 has a hub body tubular portion 123 and a hub body bottom portion 124. The hub body tubular portion 123 is cylindrical and centered on the central axis J1. The hub body bottom portion 124 extends radially inward from the right end of the hub body tubular portion 123 in the direction along the central axis J1. A bottom through-hole 125 that penetrates axially is formed in the radial center of the hub body bottom portion 124. The right hub shaft 11R passes through the bottom through-hole 125. The hub body bottom portion 124 is rotatably supported by the right hub shaft 11R via a hub bearing Br.

[0064] The case 121 also has two hub flanges 126 that extend radially outward from the outer circumferential surface. The two hub flanges 126 are spaced apart in the axial direction. The hub flanges 126 have spoke holes 127 into which the spokes Sp are inserted.

[0065] The hub body lid portion 122 is fixed to the left axial end L of the hub body cylindrical portion 123 of the case portion 121. The hub body lid portion 122 is disposed axially opposite the hub body bottom portion 124 of the case portion 121. By fixing the hub body lid portion 122 to the hub body cylindrical portion 123, an internal space 120 of the hub body 12 is formed.

[0066] The internal space 120 accommodates the motor section 20 and the reduction mechanism 30. That is, the stator 21 is disposed inside the hub body 12. The hub body cover section 122 is fixed to the hub body cylindrical section 123 by, for example, screwing. However, this is not limited to this, and fixing methods such as press fitting, adhesive bonding, and welding can also be used. Furthermore, a wide variety of methods other than these that can firmly fix the hub body cover section 122 to the hub body cylindrical section 123 can be used.

[0067] The hub body lid portion 122 is rotatably supported on the left hub shaft 11L via a hub bearing Br.

[0068] The coil 23 of the motor unit 20 disposed inside the hub body 12 is connected to a lead wire 40 via a bus bar 29. A current is supplied to the coil 23 via the lead wire 40. This excites the coil 23. This generates a magnetic force between the excited coil 23 and the rotor magnet 28. By generating this magnetic force at the right time, the rotor 25 rotates.

[0069] The rotation of the rotor 25 rotates the rotor shaft 26. The rotation of the rotor shaft 26 rotates the sun gear section 31. The rotation of the sun gear section 31 is transmitted to the planetary gear section 32, and then from the planetary gear section 32 to the internal gear section 33. This causes the internal gear section 33 to rotate. The internal gear section 33 is connected to the hub body lid section 122 of the hub body 12 via a torque limiter 34. When the internal gear section 33 rotates in the rotation direction Rt (see FIG. 8 ), the rotation of the internal gear section 33 is transmitted to the hub body lid section 122. The hub body 12 rotates relative to the hub shaft 11. The rim Rm is then rotated via spokes Sp attached to a hub flange section 126 of the hub body 12, causing the tire Ty attached to the rim Rm to roll on the ground, thereby driving the electric vehicle 100.

[0070] In this way, by accommodating the stator 21 and rotor 25 inside the hub 10, the structure can be simplified compared to a configuration that includes an electric drive unit that drives or assists the power transmission mechanism 103. Also, the motor unit 20 is provided inside the hub 10. Therefore, it can be attached to the front fork Fk, which increases the versatility of the electric drive unit.

[0071] Figure 10 is a perspective view of the right hub shaft 11R2 of the first modified example, as seen from below and in front. Figure 11 is a view of the right hub shaft 11R2 as seen from the right side in the direction along the center axis J1. The right hub shaft 11R2 of this modified example differs from the right hub shaft 11R shown in Figures 6, 8, etc. in that it has a first protrusion 115 and a second protrusion 118. In all other respects, it has the same configuration as the right hub shaft 11R. Therefore, in the right hub shaft 11R2, components that are substantially the same as those of the right hub shaft 11R are designated by the same reference numerals, and detailed description thereof will be omitted.

[0072] The right hub shaft 11R2 has a second protrusion 118 that is disposed in front of the first opening 116 in the rotation direction Rt of the wheel 102f. The circumferential width of the outer peripheral surface of the second protrusion 118 is narrower than the circumferential width of the outer peripheral surface of the first protrusion 115.

[0073] With this configuration, the circumferential width of the first protrusion 115 is made wider than the circumferential width of the second protrusion 118, thereby making it possible to increase the rigidity of the right hub shaft 11R2 while ensuring the size of the first opening 116. Furthermore, since the lead wire 40 is held by the first protrusion 115 and the second protrusion 118, the lead wire 40 can be held stably.

[0074] The first protrusion 115 has a first flat surface 1151 on the rear side in the rotation direction Rt of the wheel 102f. The second protrusion 118 has a second flat surface 1181 on the front side in the rotation direction Rt of the wheel 102f. The first flat surface 1151 and the second flat surface 1181 may be parallel to each other.

[0075] When the right hub shaft 11R2 is attached to the hub attachment portion Fk1 of the front fork Fk, rotation of the right hub shaft 11R2 is restricted. This allows the lead wire 40 to be positioned at the hub attachment portion Fk1. This allows the lead wire 40 to be wired to an accurate position relative to the front fork Fk.

[0076] In the above-described embodiment, the bicycle is a so-called power-assisted bicycle that has a power transmission mechanism 103 other than the hub 10, but the present invention is not limited to this. For example, the bicycle may be an electric vehicle that uses only the hub 10 as a power source.

[0077] In the above-described embodiment, a hub is described in which the motor unit 20 is used as a power source by supplying current from the power supply unit 104 to the coil 23, but the present invention is not limited to this. For example, it is possible to form a hub having a power generation mechanism in which the rotor 25 is rotated by the rotation of the wheel 102f to generate power in the coil 23, with the same configuration as the hub having the above-described power source.

[0078] Various modifications can be made to the various technical features disclosed in this specification without departing from the spirit of the technical creation. Furthermore, multiple embodiments and modifications shown in this specification can be combined to the extent possible.

[0079] The present invention can be used in electric vehicles that obtain driving force from electricity, such as power-assisted bicycles, electric scooters, and electric wheelchairs. It can also be used in generator hubs used in bicycles and the like. [Explanation of symbols]

[0080] 100 Electric Vehicles 101 Body 102 wheels 102f front wheel 102r rear wheel 103 Power transmission mechanism 104 Power supply section 105 crank 105a crankshaft 106 Pedals 107 Handle 108 Saddle 10. Hub 11 Hub shaft 11L left hub shaft 11R right hub shaft 111 First shaft section 112 Second shaft part 113 Flange 114 Through hole 115 1st protrusion 1151 1st plane 116 First Opening 117 Second Opening 11R2 right hub shaft 118 Second protrusion 1181 2nd plane 12 Hub body 120 Interior Space 121 Case part 122 Hub body cover 123 Hub body cylinder 124 Hub body bottom 125 Bottom through hole 126 Hub flange 127 spoke holes 13 Flange 20 Motor section 21 Stator 22 stator core 221 Coreback 222 Teeth 23 Coil 24 insulator 25 rotors 26 rotor shaft 261 Shaft bearings 262 Teeth 27 rotor core 28 rotor magnet 29 Bus Bar 30 Reduction mechanism 31 Sun gear section 32 Planetary gear section 320 planetary shaft 321 1st planetary gear 322 2nd planetary gear 33 Internal gear section 34 Torque limiter 341 Torque limiter outer ring 342 Torque limiter inner ring 40 lead wire 50 Housing 51 First housing section 511 Bottom 52 Second housing section 521 Bottom 522 Through hole Fk front fork Fk1 hub mounting part J1 center axis J2 planetary shaft Nt nut Rm rim Rt Rotation direction Sp spokes Ty Tires

Claims

1. A hub located in the center of the wheel, a hub shaft extending along a central axis and protruding outward from one axial side; a cylindrical hub body rotatably disposed on the hub shaft and extending in the axial direction; a stator having a coil formed by winding a conductive wire and disposed inside the hub body; a rotor having a rotor shaft extending along the central axis, facing the stator in a radial direction or an axial direction, and rotatably disposed relative to the stator; a lead wire electrically connected to the conductor wire, the rotor shaft is connected to the hub body; the hub shaft has a through hole that penetrates from the other axial end to the outer circumferential surface, the through hole has a first opening formed in the outer peripheral surface of the hub shaft, the lead wire is disposed in the through hole, A hub in which an end portion on one axial side of the first opening and an end portion on the other axial side are positioned at different circumferential positions relative to the central axis.

2. The hub shaft is a columnar first shaft portion extending along the central axis; a columnar second shaft portion that protrudes from one axial end of the first shaft portion along the central axis and has a smaller diameter than the first shaft portion; a first protruding portion that protrudes in the axial direction from one axial end of the first shaft portion and is disposed radially outward of the second shaft portion, The hub according to claim 1 , wherein a portion of the first opening is formed in an outer circumferential surface of the first shaft portion, an outer circumferential surface of the second shaft portion, and an outer surface of the first protrusion.

3. The hub according to claim 2 , wherein the first protrusion is disposed rearward of the first opening in the rotational direction of the wheel.

4. a second protrusion disposed in front of the first opening in the rotational direction of the wheel; The hub according to claim 3 , wherein a circumferential width on the outer circumferential surface of the second protrusion is narrower than a circumferential width on the outer circumferential surface of the first protrusion.

5. the first protrusion has a first flat surface on a rear side in a rotation direction of the wheel, the second protrusion has a second flat surface on a front side in a rotation direction of the wheel, The hub of claim 4 , wherein said first plane and said second plane are parallel.

6. a part of the first opening is formed at one axial end of the first shaft portion, 6. The hub according to claim 2, wherein a peripheral edge of the first opening formed in the first shaft portion is curved outward.

7. the through hole has a second opening that opens to the other axial side of the hub shaft, The hub according to claim 2 , wherein the first opening has a portion that overlaps with the second opening in the axial direction when viewed in a direction along the central axis.

8. The hub of claim 7 , wherein the second opening is radially offset relative to the central axis.

9. a portion of the first opening is formed in an outer circumferential surface of the first shaft portion, The length from one end of the first opening formed in the outer peripheral surface of the first shaft portion to the other end of the first opening in the axial direction is The hub according to claim 2 , wherein the axial length of the first protrusion is shorter than the axial length of the first protrusion.

10. 10. The hub according to claim 1, wherein the coil is supplied with current via the lead wire.

11. A hub according to claim 10; a power supply unit that supplies current to the coil.

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