DESCRIPTION
`
`Title of Invention
`
`MOTOR UNIT AND ELECTRIC BICYCLE
`
`Technical Field
`
`[0001] The present disclosure relates to motor units and electric bicycles, and specifically, to an
`
`electric bicycle and a motor unit including a substrate and a motor.
`
`Background Art
`
`[0002] Patent Literature 1 discloses a conventional motor drive unit. The motor drive unit
`
`described in Patent Literature 1 includes a motor and a substrate. The motoris attached to one
`
`side surface of a unit case. The substrate is attached to an inner side surface which is one of
`
`inner side surfaces of the unit case and whichis located on an opposite side of the motor.
`
`[0003] The substrate has a mounting surface facing the motor. The motor is connected to the
`
`substrate via a harness.
`
`[0004]
`
`In the motor unit described in Patent Literature 1, since the motor and the substrate are
`
`attached on the surfaces opposite to each other with respect to the unit case, downsizing ofthe
`
`motor unit is difficult.
`
`In the motor unit described in Patent Literature 1, the mounting surface
`
`on which the harness is mounted faces the motor. Therefore, even when the distance between
`
`the motor and the substrate is attempted to be reduced, the distance betweenthe substrate and the
`
`motoris difficult to be reduced.
`
`Citation List
`
`Patent Literature
`
`[0005] Patent Literature 1: WO 2014/009995
`
`Summary of Invention
`
`[0006]
`
`In view of the foregoing, it is an object of the present disclosure to provide a motor unit
`
`and an electric bicycle which are downsized by disposing a substrate close to the motor.
`
`[0007] A motor unit of one aspect according to the present disclosure includes a substrate, a
`
`

`

`motor, and at least one conductive member. The substrate has a first surface and a second
`
`surface in a thickness direction of the substrate. The motor includes at least one terminal and is
`
`disposed closer to the second surface than to the first surface in the thickness direction. The at
`
`least one conductive member is mounted on the first surface. The substrate has at least one
`
`through part which extends from the first surface through the second surface and in whichthe at
`
`least one terminal or the at
`
`least one conductive member is inserted.
`
`The at
`
`least one
`
`conductive memberis at least partially deformable and is connected to the at least one terminal.
`
`[0008] An electric bicycle of one aspect according to the present disclosure includes a frame,
`
`the motor unit attached to the frame, and a wheel. The wheel is attached to the frame andis
`
`configured to be rotated by power output from the motorunit.
`
`Brief Description of Drawings
`
`[0009]
`
`FIG. | is a side viewillustrating an electric bicycle according to one embodiment of the
`
`present disclosure;
`
`FIG. 2 is an enlarged view illustrating a motor unit of the electric bicycle;
`
`FIG.3 is a sectional view along line A-A of FIG.2;
`
`FIG. 4 is an exploded perspective view illustrating the motor, a first split body, and a
`
`substrate.
`
`FIG. 5 is an enlarged perspective view illustrating the substrate;
`
`FIG. 6 is a sectional view illustrating a state where a conductive memberis connected to
`
`a terminal on the substrate;
`
`FIG.7 is an enlarged viewillustrating portion B of FIG. 2;
`
`FIG.8 is an enlarged perspective view illustrating a substrate of a motor unit according
`
`to a first variation;
`
`FIG. 9 is a sectional view illustrating a state where a terminal and a conductive member
`
`of the motor unit according to the first variation are connected to each other;
`
`FIG. 10 is a sectional view illustrating a state where a terminal and a conductive
`
`memberof the motor unit according to a second variation are connected to each other;
`
`FIG. 11 is a sectional view illustrating a motor unit according to a third variation; and
`
`FIG. 12 is a sectional view illustrating a motor unit according to a fourth variation.
`
`

`

`Description of Embodiments
`
`[0010]
`
`(1) Embodiment
`
`(1.1) Schema
`
`Asillustrated in FIG. 6, a motor unit 5 according to the present embodiment includes a
`
`substrate 8, at least one conductive member 84, and a motor 7. The substrate 8 has a first
`
`surface 81 and a second surface 82 aligned in a thickness direction of the substrate 8. The
`
`conductive member 84 is a harness 85 including, for example, an electrical wire 851 and is
`
`mounted on thefirst surface 81 of the substrate 8. The motor 7 is disposed closer to the second
`
`surface 82 than to the first surface 81 of the substrate 8. The motor 7 includes a terminal 76
`
`connected to the conductive member 84.
`
`[0011] The substrate 8 has at least one through part 83 extending from the first surface 81
`
`through the second surface 82. The terminal 76 or the conductive member84is inserted in the
`
`through part 83. The conductive member 841s at least partially deformable.
`
`[0012] Thus, according to the motor unit 5 of the present embodiment, the substrate 8 may be
`
`disposed close to the motor 7, so that the motor unit 5 is downsized. Moreover, according to
`
`the motor unit 5 of the present embodiment, the substrate 8 may be disposed close to the motor
`
`7, but the substrate 8 is not fixed to the terminal 76 of the motor 7 with solder, and the terminal
`
`76 is thus not bound to the substrate 8. Thus, even when the substrate 8 and the motor 7
`
`vibrate, stress caused at the substrate 8 due to force applied by the terminal 76 is reduced.
`
`[0013]
`
`(1.2) Details
`
`The motor unit 5 of the present embodiment will be described below. As an example
`
`of the motor unit 5, a motor unit 5 for use in an electric bicycle 1 will be described below.
`
`However, this is one example of the motor unit 5 according to the present disclosure and is not
`
`intended to limit applications of the motor unit 5 according to the present disclosure to the
`
`electric bicycle 1.
`
`[0014]
`
`(1.2.1) Electric Bicycle
`
`The electric bicycle 1 is a bicycle configured to travel using electrical power.
`
`In the
`
`present embodiment, the electric bicycle 1
`
`is an electric-assist bicycle in which the motor 7
`
`assists force applied to a pedal by a user(also referred to as “pedal force”), but in the present
`
`disclosure, the electric bicycle 1 may be a bicycle that is configured to travel using only the
`
`motor 7.
`
`In sum,
`
`the electric bicycle 1 according to the present disclosure may be an
`
`electric-assist bicycle or may be a bicycle configured to travel using only the motor 7. As
`
`illustrated in FIG. 1, the electric bicycle 1 includes a frame 2, a plurality of wheels 4, a battery
`
`

`

`device 3, a handle 93, a saddle 94, crank arms 90, pedals 91, and the motor unit 5. The
`
`plurality of wheel 4 includes a front wheel 41 and a rear wheel 42.
`
`[0015] Here,
`
`in the present disclosure, a direction in which the electric bicycle 1
`
`travels is
`
`defined as a “front direction”, and a direction opposite to the front direction is defined as a “rear
`
`direction”. Moreover, two directions, namely,
`
`the front direction and the rear direction are
`
`defined as “forward/rearward directions”, and two directions orthogonal to the forward/rearward
`
`directions and extending along a horizontal plane are defined as “rightward/leftward directions”.
`
`Here, the horizontal plane is defined based on the electric bicycle 1 traveling on a horizontal
`
`surface.
`
`[0016] The frame 2 is a frame configured to hold at least, the front wheel 41, the rear wheel 42,
`
`and the battery device 3.
`
`In the present embodiment, the frame 2 is made of an aluminum alloy
`
`containing aluminum as a main component. Note that in the present disclosure, materials for
`
`the frame 2 are not limited to the aluminum alloy but may be, for example, carbon or a metal
`
`such as iron, chrome molybdenum steel, or high tensile strength steel, titanium.
`
`[0017] The frame 2 includes a plurality of tubes.
`
`In the present embodiment, the frame 2
`
`includes a down tube 20, a seat tube 21, a plurality of (in the present embodiment, two) chain
`
`stays 22, a plurality of (in the present embodiment, two) seat stays 23, a top tube 24, a head tube
`
`25, and a fork 26 as the plurality of tubes. The frame 2 further includes a bottom bracket 27.
`
`[0018] As used herein, a tube” means an elongated hollow member, and the shape ofits cross
`
`section is not particularly limited. Examples ofthe cross section ofthe tube include not only a
`
`circular cross section such as a precise circular cross section and oval-shaped cross section
`
`(including ellipse-shaped cross section) but also a polygonal cross section such as a square cross
`
`section, a rectangular cross section, and a hexagonal cross section.
`
`[0019] The bottom bracket 27 is a component to whichat least a lower end of the down tube 20
`
`and a front end of the chain stay 22 are connected.
`
`In the present embodiment, a lower end of
`
`the seat tube 21, in addition to the down tube 20 and the chain stay 22, is connected to the
`
`bottom bracket 27.
`
`In the present embodiment, the motor unit 5 is attached to the bottom
`
`bracket 27.
`
`[0020] The downtube 20 is a tube connecting the bottom bracket 27 to the head tube 25. The
`
`downtube 20 extends from a front end in the forward/rearward directions of the bottom bracket
`
`27 to the head tube 25, and in a longitudinal direction of the down tube 20, the down tube 20 is
`
`tilted upwardin the front direction.
`
`In the present embodiment, a battery pack 32 is detachably
`
`attached to the downtube 20.
`
`

`

`[0021] The seat tube 21 is a tube that holds the saddle 94.
`
`In the present embodiment, the seat
`
`tube 21 connects the bottom bracket 27 to the top tube 24.
`
`In the present embodiment, the seat
`
`tube 21 extends from an upper end of the bottom bracket 27 to a level higher than the top tube
`
`24, and in a longitudinal direction of the seat tube 21, the seat tube 21 is tilted upward in the rear
`
`direction. The seat tube 21 holds the saddle 94 such that the saddle 94 1s movable along the
`
`longitudinal direction of the seat tube 21.
`
`[0022] The plurality of chain stays 22 are tubes that connect the bottom bracket 27 to the seat
`
`stays 23. Each chain stay 22 extends from a rear end of the bottom bracket 27 to a rear end of a
`
`corresponding one of the seat stays 23.
`
`In the present embodiment, two chain stays 22 are
`
`provided to be apart from each other in the rightward/leftward directions, and the rear wheel 42
`
`is disposed between the two chain stays 22. The rear end of the chain stay 22 has a bearing 221
`
`to which a shaft (a rear wheel shaft 421) of the rear wheel 42 is to be attached. The rear wheel
`
`42 is rotatably attached to the bearing 221.
`
`[0023] The plurality of seat stays 23 are tubes connecting an upper end of the seat tube 21 to
`
`the chain stays 22. Each seat stay 23 extends from the upper end of the seat tube 21 to a rear
`
`end of the chain stay 22, and each seat stay 32 longitudinally tilted downward in the rear
`
`direction. The “upper end of the seat tube 21” mentioned herein means a portion having a
`
`certain region located to have a certain dimension extending downward from an uppertip end of
`
`the seat tube 21 along the longitudinal direction of the seat tube 21.
`
`In the present embodiment,
`
`two seat stays 23 are provided to be apart from each other in the rightward/leftward directions
`
`and are connected to the two chain stays 22 on a one-to-one basis.
`
`[0024] The top tube 24 is a tube that connects the head tube 25 to the seat
`
`tube 21.
`
`Specifically, the top tube 24 connects the head tube 25 to the upperend of the seat tube 21. A
`
`rear end in a longitudinal direction of the top tube 24 is connected to the upper end of the seat
`
`tube 21. The top tube 24 extends from the upper end of the seat tube 21 to the head tube 25,
`
`and in the longitudinal direction of the top tube 24, the top tube 24 is tilted upward in the front
`
`direction.
`
`In the present embodiment,
`
`the frame 2 includes a reinforcement tube 241 that
`
`connects the top tube 24 to the seat tube 21.
`
`[0025] The head tube 25 is a tube to which a front end of the top tube 24 and a front end ofthe
`
`downtube 20 are connected. The head tube 25 supports the fork 26 and the handle 93 rotatably
`
`about a central axis of the head tube 25.
`
`[0026] The fork 26 is a tube to whichthe front wheel 41 is to be attached. The front wheel 41
`
`is attached to the fork 26 rotatably about a shaft (a front wheel shaft 411) of the front wheel 41.
`
`

`

`The fork 26 includes a pair of legs 261 that support the front wheel shaft 411 and a steering
`
`column 262 that extends upward from an upper end of the legs 261 along the central axis of the
`
`head tube 25. The fork 26 is attached to the head tube 25 byfitting the steering column 262 in
`
`the head tube 25. The handle 93 is attached to an upperend of the steering column 262. Thus,
`
`when the handle 93 rotates about the central axis of the head tube 25, the fork 26 rotates about
`
`the central axis of the head tube 25, and the front wheel 41 rotates about the central axis of the
`
`head tube 25.
`
`[0027] The front wheel 41 is a front wheel 4 of the two wheels 4 aligned in the
`
`forward/rearward directions.
`
`In the present embodiment, the front wheel 41 is supported by the
`
`fork 26 rotatably about the front wheel shaft 411. A longitudinal direction of the front wheel
`
`shaft 411 is parallel to the rightward/leftward directions. Here, the longitudinal direction of the
`
`front wheel shaft 411 is parallel to the rghtward/leftward directions in a state where the electric
`
`bicycle 1 travels in the front direction.
`
`In the present embodiment, the front wheel 41 is a
`
`wheel 4 to which poweris not transmitted from the motor unit 5.
`
`[0028] The rear wheel 42 is a rear wheel 4 of the two wheels 4 aligned in the forward/rearward
`
`directions.
`
`In the present embodiment, the rear wheel 42 is supported by the two chain stays 22
`
`rotatably about the rear wheel shaft 421. A longitudinal direction of the rear wheel shaft 421 is
`
`parallel to the rightward/leftward directions.
`
`In the present embodiment, the rear wheel 42
`
`includes a rear sprocket 422 (here, a cassette sprocket) and is coupled to a drive sprocket 57 of
`
`the motor unit 5 via a power transmitter 92 (here, a chain). Thus, power of the motor unit 5 is
`
`transmitted to the rear wheel 42.
`
`[0029] The battery device 3 is a device for supplying electric power to the motor unit 5.
`
`However, in the present disclosure, the battery device 3 may be configured to supply electric
`
`power to an ON/OFFoperation section
`
`of the motor 7, the headlight, or the like in addition to
`
`the motor unit 5. The battery device 3 includes a battery pack 32 as a secondary battery for
`
`accumulating electrical energy and a battery applied part 31 via which the battery pack 32 is
`
`electrically connected to the motor7.
`
`[0030]
`
`(1.2.2) Motor Unit
`
`The motor unit 5 is a device configured to generate electrical power in the electric
`
`bicycle 1. The power generated by the motor unit 5 is transmitted via the power transmitter 92
`
`to the wheel 42. When the motor unit 5 receives pedal force from the pedals 91, the motor unit
`
`5 generates a drive assist output. Note that the “drive assist output” mentioned in the present
`
`disclosure means force that supplements the pedal force by using the motor 7.
`
`In the present
`
`

`

`embodiment, when the motor unit 5 receives the pedal force from the pedals 91 and the crank
`
`arms 90, the motor unit 5 detects an input value of the pedal force (here, the rotation speed and a
`
`torque of an input shaft 54), and based on the input value, the motor unit 5 outputs the drive
`
`assist output to the powertransmitter 92.
`
`[0031] Here, FIG. 2 is an enlarged view of the motor unit 5.
`
`In FIG. 2, the unit case 51 is
`
`partially cut out.
`
`FIG. 3 is a sectional view along line A-A of FIG. 2.
`
`Asillustrated in FIG.3,
`
`the motor unit 5 includes a unit case 51, the input shaft 54, an inputter 55, an outputter 56, a
`
`drive sprocket 57, one-way clutches 581 and 582, a deceleration mechanism 59, the motor 7, and
`
`the substrate 8.
`
`[0032] The unit case 51 accommodates apparatuses of the motor unit 5.
`
`In the present
`
`embodiment, the unit case 51 accommodates the input shaft 54, the inputter 55, the outputter 56,
`
`the one-way clutches 581 and 582, the deceleration mechanism 59, and the like.
`
`In the present
`
`embodiment, the unit case 51 is made of an aluminum alloy, but in the present disclosure, the
`
`unit case 51 may be made ofstainless steel, steel, carbon, a synthetic resin, or the like.
`
`In the
`
`present embodiment, the unit case 51 is formed by die casting.
`
`In the present embodiment, the
`
`unit case 51 includesa first split body 52 and a secondsplit body 53.
`
`[0033] The first split body 52 has a bottomed cylindrical shape having an opening surface
`
`facing in one direction (here, the right direction). The first split body 52 includesafirst side
`
`wall 521 anda first peripheral wall 525. The first side wall 521 is located on an opposite side
`
`(here on the left side) from the opening surface in the rightward/leftward directions.
`
`Thefirst
`
`peripheral wall 525 protrudes in the one direction (the right direction) from a peripheral edge of
`
`the first side wall 521.
`
`In the present embodiment, the first side wall 521 is integral with the
`
`first peripheral wall 525.
`
`[0034] The first side wall 521 has a first through hole 522, a motor through hole 523 (see FIG.
`
`4), and a terminal hole 524 (see FIG. 4). The input shaft 54 is to be inserted into the first
`
`through hole 522. An output shaft 74 of the motor 7 is to be inserted into the motor through
`
`hole 523. The terminal 76 of the motor 7 is to be inserted into the terminal hole 524. The
`
`motor7 is attached to an outer surface of the first side wall 521 (outer side surface of the motor
`
`unit 5) via a fixation member. That is, the motor 7 is attached to the unit case 51 in a state
`
`where the motor 7 is disposed along an outer surface of the unit case 51. When the motor7 is
`
`attached to the first side wall 521, the output shaft 74 of the motor 7 is inserted in the motor
`
`through hole 523, and the terminal 76 of the motor 7 is inserted in the terminal hole 524.
`
`[0035] The second split body 53 has a bottomed cylindrical shape having an opening surface
`
`

`

`facing in a direction (here, the left direction) opposite to the one direction. The second split
`
`body 53 includes a second side wall 531 and a second peripheral wall 533. The second side
`
`wall 531 is located on an opposite side (here on the right side) from the opening surface in the
`
`rightward/leftward directions. The second peripheral wall 533 protrudes in one direction (the
`
`left direction) from a peripheral edge of the second side wall 531.
`
`In the present embodiment,
`
`the second side wall 531 is integral with the second peripheral wall 533. The second side wall
`
`531 has a second through hole 532 concentric with the first
`
`through hole 522 in the
`
`rightward/leftward directions.
`
`[0036]
`
`In the unit case 51, an end surface ofthe first peripheral wall 525 and an end surface of
`
`the second peripheral wall 533 are in contact with each other, and the opening surface ofthefirst
`
`split body 52 and the opening surface of the second split body 53 are joined together.
`
`In this
`
`state, the first peripheral wall 525 is coupled to the second peripheral wall 533 via a fixation
`
`member. Thus, the first split body 52 and the second split body 53 are fixed to each other.
`
`With respect to the unit case 51, the input shaft 54 is inserted into the second through hole 532
`
`and the first through hole 522. That is to say, the input shaft 54 extends through the unit case
`
`51 in the rightward/leftward directions.
`
`[0037] The input shaft 54 is a shaft body which receives pedal force from the crank arms 90.
`
`In the present embodiment, the input shaft 54 is supported by a bearing 650 and a bearing 651.
`
`The bearing 650 is attachedto thefirst split body 52 to be concentric with the first through hole
`
`522. The bearing 651 is attached to the second split body 53 to be concentric with the second
`
`through hole 532. Thus, the input shaft 54 is rotatable about an axis 541 extending to the unit
`
`case 51 in the rightward/leftward directions.
`
`[0038] Here, as used herein, the “axis” meansa certain straight line as the center of the rotation
`
`movement of an object.
`
`In the present embodiment, the axis 541 (rotation axis) of the input
`
`shaft 54 is realized by a central axis of the input shaft 54 rotatably supported by the bearing 650
`
`attached to the first split body 52 and the bearing 651 attached to the second split body 53. The
`
`“bearing” according to the present embodimentis a ball bearing, but in the present disclosure,
`
`the bearing may be a rolling bearing, a sliding bearing, a fluid bearing, orthe like.
`
`[0039] The input shaft 54 has both ends to which the respective crank arms 90 are attached.
`
`Whenthe input shaft 54 receives pedal force about the axis 541 from the crank arms 90, the
`
`input shaft 54 rotates about the axis 541. The inputter 55 is attached to the input shaft 54.
`
`[0040] The inputter 55 is a memberfor transmitting rotative power of the input shaft 54 to the
`
`outputter 56. The inputter 55 and the input shaft 54 are coaxially provided, and the inputter 55
`
`

`

`is attached to an outer peripheral surface of the input shaft 54. The inputter 55 has a cylindrical
`
`shape having a central axis parallel to the rightward/leftward directions. At least part of an
`
`inner peripheral
`
`surface of the inputter 55 in the center axial direction (here,
`
`in the
`
`rightward/leftward directions) has a first connection section 551. On the other hand, part of the
`
`input shaft 54 in a longitudinal direction of the input shaft 54 has a second connection section
`
`542 to be coupled to the first connection section 551. The first connection section 551 and the
`
`second connection section 542 include, for example, a spline, a serration, or a key and a key
`
`groove. Thus, inputter 55 is fixed to the input shaft 54 so as not to rotate aroundat least the
`
`axis 541.
`
`In the present embodiment,
`
`the inputter 55 and the input shaft 54 are separated
`
`components (individual members) but may be integral with each other.
`
`[0041] The outputter 56 is a member for transmitting the rotative power received from the
`
`inputter 55 to the drive sprocket 57. The outputter 56 and the input shaft 54 are coaxisally
`
`disposed. The output shaft 74 is supported rotatably about the axis 541, coaxially with the
`
`inputter 55, by a bearing 652 and a bearing 651. The bearing 652 is attached to an outer
`
`peripheral surface of the inputter 55. The bearing 651 is attached to the secondsplit body 53 to
`
`be concentric with the second through hole 532. The outputter 56 includes an outputter 561 and
`
`a teeth part 562.
`
`In the present embodiment,
`
`the outputter 561 and the teeth part 562 are
`
`integral with each other.
`
`[0042] The outputter 561 is a portion to which the drive sprocket 57 is to be attached. When
`
`the drive sprocket 57 is attached to the outputter 561, the drive sprocket 57 is fixed to the
`
`outputter 561. The outputter 561 1s formed at an outer-side (here, right-side) end of the
`
`outputter 56 in the rightward/leftward directions and protrudes from the unit case 51.
`
`[0043] The teeth part 562 is connected to the deceleration mechanism 59.
`
`Specifically, the
`
`teeth part 562 engages a gear (a second transmission gear 62) of the deceleration mechanism 59.
`
`Thus, power input from the deceleration mechanism 59 to the outputter 561 is transmitted to the
`
`drive sprocket 57.
`
`[0044] Between the inputter 55 and the outputter 56, a one-way clutch 581 is provided. Here,
`
`one rotation direction about the axis 541 whenthe electric bicycle 1 is accelerated in the front
`
`direction is defined as an acceleration direction. On the other hand, one rotation direction about
`
`the axis 541 when theelectric bicycle 1 is decelerated in the front direction is referred to as a
`
`deceleration direction.
`
`[0045] When the inputter 55 rotates with respect to the outputter 56 in the acceleration
`
`direction, the one-way clutch 581 rotates the outputter 56 in the acceleration direction about the
`
`

`

`10
`
`axis 541 at the same angular velocity as the inputter 55. On the other hand, when the inputter
`
`55 rotates with respect to the outputter 56 in the deceleration direction, the one-way clutch 581
`
`interrupts transmission of the rotative power from the inputter 55 to the outputter 56. Thus,
`
`when powerinput from the deceleration mechanism 59 to the outputter 56 rotates the outputter
`
`56 with respect to the inputter 55 in the acceleration direction, that is, when the inputter 55
`
`rotates with respect to the outputter 56 in the deceleration direction, the one-way clutch 581
`
`interrupts transmission of the rotative power from the outputter 56 to the inputter 55.
`
`[0046] When rotative powerin the acceleration direction is applied from the crank arms 90 to
`
`the input shaft 54, the input shaft 54 rotates in the acceleration direction about the axis 541, and
`
`as the input shaft 54 rotates, the inputter 55 rotates in the acceleration direction. When the
`
`inputter 55 rotates in the acceleration direction about the axis 541, rotative power of the inputter
`
`is transmitted via the one-way clutch 581 to the outputter 56. Then, the inputter 55 rotates the
`
`outputter 56 in the acceleration direction about the axis 541 and rotates the drive sprocket 57 in
`
`the acceleration direction about the axis 541. At this time, the drive sprocket 57 rotates the rear
`
`sprocket 422 via the power transmitter 92, thereby rotating the rear wheel 42. Thus, the electric
`
`bicycle | travels in the front direction.
`
`[0047] The motor 7 receives driving electric power and outputs rotative power. As used
`
`herein, the “driving electric power” meanselectric power for driving the motor 7. The driving
`
`electric power is electric power supplied from a controller formed on the substrate 8. The
`
`controller is connected to the battery device 3. The motor 7 includes a metal cup 71, a stator
`
`72, arotor 73, and an output shaft 74.
`
`[0048] The metal cup 71 accommodates the stator 72 and the rotor 73. The metal cup 71 has a
`
`bottomed cylindrical shape having an opening surface facing in one direction (here, the right
`
`direction) and is to be attachedto the first split body 52. When the metal cup 71 is attached to
`
`the first split body 52, the opening surface of the metal cup 71 faces the outer surface ofthe first
`
`side wall 521.
`
`[0049] The stator 72 is attached to an inner side of the metal cup 71 and is fixed to the metal
`
`cup 71.
`
`In the present embodiment, the stator 72 has a cylindrical shape andis fit in an inner
`
`peripheral surface of the metal cup 71. The rotor 73 is disposed on an innerside ofthe stator 72
`
`and is rotatable with respect to the stator 72. The output shaft 74 is attached to the rotor 73.
`
`[0050] The output shaft 74 outputs the rotative power of the motor 7. The output shaft 74 is
`
`fixed to the rotor 73. When the metal cup 71 is attachedto the first split body 52, an opposite
`
`end of the output shaft 74 from the rotor 73 in the longitudinal direction is inserted in the unit
`
`

`

`11
`
`case 51 via the motor through hole 523 (see FIG. 4). The output shaft 74 is supported by a
`
`bearing 653 and a bearing 654 rotatably about an axis 741 extending in the rightward/leftward
`
`directions. The bearing 653 is attached to the metal cup 71. The bearing 654 1s attached to the
`
`second split body 53. The output shaft 74 has a portion which is to inserted in the unit case 51
`
`and which hasa teeth part 742 connected to the deceleration mechanism 59.
`
`[0051] The deceleration mechanism 59 receives the rotative power from the output shaft 74 of
`
`the motor 7 and transmits the rotative power to the outputter 56 such that the rotation speed of
`
`the outputter 56 is slower than the rotation speed of the output shaft 74.
`
`In the present
`
`embodiment, the deceleration mechanism 59 includes a transmission rotary shaft 60, a first
`
`transmission gear 61, and a second transmission gear 62.
`
`[0052] The transmission rotary shaft 60 is rotatable about an axis 601 extending in the
`
`rightward/leftward directions. The transmission rotary shaft 60 is supported by a bearing 655
`
`attachedto the first split body 52 and a bearing 656 attached to the second split body 53. The
`
`first transmission gear 61 and the second transmission gear 62 are coaxially attached to the
`
`transmission rotary shaft 60.
`
`[0053] The bearing 654 supporting the output shaft 74 is disposed to at least partially overlap
`
`the bearing 656 supporting the transmission rotary shaft 60 when viewed in a direction which is
`
`substantially orthogonal to the output shaft 74 and in which the transmission rotary shaft 60 and
`
`the output shaft 74 are aligned. Here, the bearing 654 supporting an opposite end of the output
`
`shaft 74 from the rotor 73 in a longitudinal direction of the output shaft 74 is desirably disposed
`
`to be farther away from the rotor 73 than the second transmission gear 62 is in the longitudinal
`
`direction of the output shaft 74. With this configuration, a long distance is secured between the
`
`bearing 653 andthe bearing 654 of the output shaft 74, and rotation of the output shaft 74 is thus
`
`stabilized. This improves tooth contact between the teeth part 742 of the output shaft 74 and
`
`the first transmission gear 61, thereby improving the durability of the motor unit 5.
`
`[0054] The first transmission gear 61 engages the teeth part 742 of the output shaft 74 of the
`
`motor 7. The first transmission gear 61 receives the rotative power of the output shaft 74
`
`rotating about the axis 741 and may rotate about the axis 601. Between the first transmission
`
`gear 61 and the transmission rotary shaft 60, a one-way clutch 582 is disposed. Whenthefirst
`
`transmission gear 61 rotates about the axis 601 in the acceleration direction with respect to the
`
`transmission rotary shaft 60, the one-way clutch 582 rotates the transmission rotary shaft 60 in
`
`the acceleration direction about the axis 601 at the same angular velocity as the first transmission
`
`gear 61. On the other hand, when the first transmission gear 61 rotates in the deceleration
`
`

`

`12
`
`direction about the axis 601 with respect to the transmission rotary shaft 60, the one-way clutch
`
`582 interrupts transmission of the rotative power betweenthefirst transmission gear 61 and the
`
`transmission rotary shaft 60. Thus, for example, while the transmission rotary shaft 60 rotates
`
`in the acceleration direction about the axis 601, the rotation of the output shaft 74 of the motor 7
`
`about the axis 741 may stop, and in this case,
`
`the first transmission gear 61 rotates in the
`
`deceleration direction about the axis 601 with respect to the transmission rotary shaft 60.
`
`In
`
`this case,
`
`the one-way clutch 582 interrupts the transmission of the power between the
`
`transmission rotary shaft 60 and thefirst transmission gear 61.
`
`[0055] The second transmission gear 62 engages the teeth part 562 of the outputter 56. The
`
`second transmission gear 62 is fixed to the transmission rotary shaft 60 and rotates about the axis
`
`601 at the same angular velocity as the rotation of the transmission rotary shaft 60 about the axis
`
`601.
`
`In the present embodiment, the second transmission gear 62 is a component (individual
`
`member) separated from the transmission rotary shaft 60, but the second transmission gear 62
`
`and the transmission rotary shaft 60 may be integral with each other.
`
`[0056] When the output shaft 74 of the motor 7 rotates in the acceleration direction about the
`
`axis 741, the first transmission gear 61 rotates in the acceleration direction about the axis 601.
`
`The rotative power of the first transmission gear 61 in the acceleration direction about the axis
`
`601 is transmitted via the one-way clutch 582 to the transmission rotary shaft 60 and rotates the
`
`outputter 56 in the acceleration direction. Moreover, as described above, power obtained from
`
`the pedal force input from the crank arms 90 is also transmitted to the outputter 56. Thus, in the
`
`outputter 56, force resulting from the pedal force and the drive assist output from the motor 7 are
`
`combined with each other.
`
`In sum, the motor unit 5 according to the present embodimentis a
`
`so-called one-shaft motor unit 5.
`
`[0057] Moreover, while the electric bicycle 1 travels in the front direction, the output from the
`
`motor 7 may stop, and in this case, the first transmission gear 61 rotates in the deceleration
`
`direction about the axis 601 with respect to the transmission rotary shaft 60. This interrupts the
`
`transmission of the power between the transmission rotary shaft 60 and the first transmission
`
`gear 61. For example, also when driving of the motor 7 is stopped, for example, when driving
`
`electric power supplied to the motor 7 is stopped, rotative power in the deceleration direction 1s
`
`suppressed from being a