des brevets
`
`Europisches
`Patentamt
`European
`Patent Gffice
`Office européen
`
`mc
`EP 2 671 788 A1
`
`(11)
`
`(12)
`
`EUROPEAN PATENT APPLICATION
`published in accordance with Art. 153(4) EPC
`
`(43) Date of publication:
`11.12.2013 Bulletin 2013/50
`
`(51) Int Cl:
`BE2M 6/65 (2970.01)
`
`B62M 6/45(2270.01)
`
`(21) Application number: 12741787.1
`
`(86) International application number:
`PCT/JP2012/000510
`
`(22) Date offiling: 27.01.2012
`
`(87) International publication number:
`WO 2012/105198 (09.08.2012 Gazette 2012/32)
`
`
`(84) Designated Contracting States;
`AL AT BE.BG CH CY CZ DE DK EE ES FIFRGB
`GR HR HU IE ISIT LILT LU LV MC MK MT NL NO
`PL PTRORS SE SISK SMTR
`
`(30) Priority: 31.01.2011 JP 2011018597
`
`(72) Inventor: SHIMAZU, Masahiro
`Moriguchi-shi, Osaka 570-8677 (JP)
`
`(74) Representative: Witte, Weller & Partner
`K6nigstrasse 5
`70173 Stuttgart (DE)
`
`(71} Applicant: Sanyo Electric Co., Ltd.
`Osaka 570-8677 (JP)
`
`
`(54)
`
`ELECTRIC BICYCLE
`
`An electric bicycle is provided to. suppress an
`(57)
`impact when pedals are pressed and a motor starts ro-
`tating a wheel in a coasting state. A pedal force applied
`to pedals 11 isdetected by asensor 12. In the case where
`the sensor detects thatthe pedal force is not smaller than
`a predetermined force, a control unit 75 rotates an output
`rotation unit 51 at least at a predeterminedfirst acceler-
`
`ation when the rotation speed of the output rotation unit
`51 is not lower than that of a front wheel 5. In the case
`
`where the rotation speed of the output rotation unit 51 is
`lower than that of the front wheel 5 in a coasting state,
`the control unit 75. rotates the output rotation unit 51 ata
`second acceleration lower than the first acceleration at
`
`least when a clutch 22 is engaged.
`
`
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`61
`
`ue
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`67
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`68
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`FIG. 3
`
`MANUAL OPERATION PART
`64
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`65
`
`_ 6
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`6I
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`WHEEL ROTATION
`INFORMATION UNIT.
`
`62
`Sry
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`63
`Le
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` 7
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`
`
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`BATTERY.
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`78
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`CHARGING/DISCHARGING CIRCUIT
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`3—
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`MOTOR
`
`SPEED DETECTING UNIT
`
`SENSOR
`
`GONTROL. UNIT
`
`
`
`
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`Printed by Jouve, 75001 PARIS (FR}
`
`EP2671788A1
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`EP 2 671 788 A1
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`Description
`
`1, Yohei Harada, declare that] am wellacquaint-
`[0001]
`ed with the Japanese and English languages and that
`the appended English translation is a true and faithful
`translation of
`
`PCT application No. PCT/JP2012/000510 filed
`[0002]
`on January 27, 2012 in Japanese language.
`
`Technical Field
`
`[0003] The present invention relates to an electric bi-
`cycle.
`
`Background Art
`
`[0004] Aknown electric bicycle includes a motor inthe
`hub of afront wheel or.a rear wheel (see Patent Literature
`1).
`in-
`[6005] An electric: bicycle in Patent Literature 1
`cludes. a moter in the hub of a front wheel. The motor
`includes a stator fixed on the front fork of the bicycle. An
`output rotation unit rotated by a rotor is connected to the
`front wheel via.a one-way clutch.
`[0006] When a rider pedals with human power on a
`rough road, 6.g., a hill,
`the: motor generates a driving
`force according to the pedal force (torque) of the rider to
`rotate the rotor. When the rotation speed (in other words,
`an angular velocity) of the output rotation unit rotated by
`the rotor exceeds the rotation speed of the front wheel
`(provided with the motor), the one-way clutch is. engaged
`to transmit the rotary force of the output rotation unit to
`the frant wheel via the one-way clutch. Thus, the frant
`wheel is assisted by the driving force of the motor so as
`to strongly rotate, allowing the rider to pedal under lighter
`load on a hill.
`
`Citation List
`
`Patent Literature
`
`Patent Literature 1: Japanese Patent Laid-
`[0007]
`Open No. 2009-12627
`
`Summaryof Invention
`
`Technical Problem
`
`[0008] A bicycle traveling at a high speed can coast
`substantially ata constant speed on a flat road without
`pedaling. In such a coasting state, a rider does not pedal
`the bicycle and thus motor driving (the rotations ofa rater
`and an output rotation unit) is stopped.
`[0009]
`In acoasting state, the rider may start pedaling
`to increase a traveling speed. in this case, motor driving
`is.started to start rotating the rotor in response to the start
`of pedaling. When the rotation speed of the output rota-
`tion unit exceeds the rotation speed of a front wheel, a
`
`one-way clutch is engaged to allow the motor to start
`rotating the front wheel (assisted driving).
`[0010]
`In a coasting state, the wheel is. substantially
`kept at a constant rotation speed. Thus,
`the rotation
`speed of the wheel hardly changes, and the angular ac-
`celeration of the. wheel is nearly zero. From when driving
`of the moter is started in a coasting state. to when the
`rotation speed of the output rotation unit rotated by the
`rotor exceeds the rotation speed of the front wheel, the
`rotation speed (angular velocity) of the output rotation
`unit increases at a high acceleration (angular accelera-
`tion).in a relatively rapid manner. Thus, when the rotation
`speed of the output rotation unit exceeds the rotation
`speed of the front wheel and the one-wayciutch is en-
`gaged to transmit the rotary force of the output rotation
`unit to the wheel, the electric bicycle may have an impact
`caused by a difference in angular acceleration between
`the output rotation unit and the wheel. This. makesit dif-
`ficult to. provide.a more comfortable ride, and the impact
`may excessively wear the parts (particularly, the clutch
`and so on) of the electric bicycle.
`[0011] Thepresentinvention has been devised against
`this backdrop. An object of the present invention is to
`provide an electric bicycle that can suppress an impact
`when pedaling in a coasting state allows a motor to start
`rotating a wheel.
`
`Solution to Problem
`
`[0072] An invention of afirst aspect is an electric. bicy-
`cle that. assists a driving force generated by rotating ped-
`als with human power, with an auxiliary driving force gen-
`erated by a motor,the electric bicycle including: a pedal
`force detector that detects a pedal force applied to the
`pedals; a motorincluding arotor, the motor rotating, when
`the pedal force detector detects that the pedal force is
`not smaller than a predetermined force, the rotor and an
`output rotation unit rotated by the rotor so as to. generate
`the auxiliary driving farce on a wheel; a clutch that is
`disengaged to interrupt power transmission between the
`output rotation unit and the wheel when the output rota-
`tion unit rotated by the rotor has a rotation speed lower
`tharnthe rotation speed of the wheel, and is engaged to
`transmit the auxiliary driving force to the wheel from the
`output rotation unitwhen the rotation. speed of the output
`rotation unit rises to the rotation speed of the wheel; a
`wheel speed detector that detects the rotation speed of
`the wheel; a rotation speed detector that detects a rota-
`tion speed of one of the output rotation unit and the rotor
`corresponding to the output rotation unit; and a rotation
`controller that rotates, when the pédal force detector de-
`tects that the pedal force is: not smaller than the prede-
`termined force, the output rotation unit.at least at a pre-
`determinedfirst acceleration if the rotation speed of the
`output retation unit is not lower than the rotation speed
`of the wheel based on detected values of the wheel speed
`detector and the rotation speed detector, and rotates, if
`the rotation speed of the output rotation unit is lowerthan
`
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`the rotation speed of the wheel, the output rotation unit
`at asecond acceleration lowerthan tie first acceleration
`when atleast the clutch is engaged.
`[0013] An invention of a second aspectis the electric
`bicycle, wherein in the case. where the pedal force de-
`tector detects that the pedal force is not smaller than the
`predetermined force, the rotation controller rotates, when
`the rotation speed of the output rotation unit is reduced
`from the rotation speed of the wheel at least by a prede-
`termined speed, the output rotation unit at a third accel-
`eration higher than the second acceleration untila speed
`difference between the rotation speed of the output ro-
`tation unit and the rotation speed of the wheel falls below
`the predetermined speed.
`
`Advantageous Effects of Invention
`
`[8014] According to the invention ofthe first aspect, in
`the electric bicycle, a driving force generated by rotating
`the pedals with human power is assisted by an auxiliary
`driving force generated by the motor.
`[9015] A pedal force applied to the pedals is detected
`by the pedal force detector. The motor includes the rotor.
`In the case where the pedal force detector detects that
`the pedal force is not smallierthan a predetermined farce,
`the rotor and the output rotation unit rotated by the rotor
`are rotated to generate the auxiliary driving force on the
`wheel.
`
`In the electric bicycle, when the rotation speed
`[0016]
`of the output rotation unit is lower than the rotation speed
`of the wheel, the clutch is disengaged to interrupt power
`transmission. between the. output rotation. unit and the
`wheel. When the rotation speed of the autput. rotation
`unit increases to the rotation speed of the wheel, the
`clutch is engaged to transmit the auxiliary. driving force
`from the output rotation unit to the wheel.
`[08017] The wheel speed detector detects the rotation
`speed of the wheel while the rotation speed detector de-
`tects the-rotation speed of the output rotation unit.
`[0018] When the pedal force detector detects that the
`pedal force is nat smaller than the predetermined force,
`the rotation controller rotates the output rotation unit at
`least at the predeterminedfirst acceleration ifthe rotation
`speed of the output rotation unit is not lower than the
`rotation speed of the wheel based on the detected values
`of the wheel speed detector and the rotation speed de-
`tector. Itis. expected that the rotation speed of the output
`rotation unit is not lower than that of the whéel in a typical
`(assisted) state where.an auxiliary driving force has been
`generated or in a stopped state wherethe rotation speeds
`of the output rotation unit and the wheel are 0.
`[0019] Whenthe rotation speed of the output rotation
`unit is lower than that of the wheel, the electric bicycle
`starts pedaling in a coasting state having not involved
`pedaling.
`In this case, at least when the clutch is en-
`gaged, the rotation controller retates the rotor at the sec-
`ond acceleration lower than the first acceleration. Thus,
`when the clutch is: engaged, the rotation speed of the
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`20
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`25
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`30
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`40
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`45
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`50
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`autput rotation unit less rapidly increases. to the rotation
`speed of the wheel than at the first acceleration. Thus,
`the auxiliary driving force can be smoothly transmitted
`from the output rotation unit to the wheel.
`[0020] As aresult, an impact can be suppressed when
`the pedals are pressed and the motorstarts rotating the
`wheel in a coasting state.
`[0021] According tothe invention of the second aspect,
`in the case where the pedal force detector detects that
`the pedal force is net smaller than the predetermined
`force, when the rotation speed of the output rotation unit
`is reduced from the rotation speed of the wheel at least
`by the predetermined speed, the rotation controller ro-
`tates the output rotation unitatthe third acceleration high-
`er than the second acceleration until a speed difference
`between the rotation speed of the output rotation unit and
`the rotation speed of the: wheel falls below the predeter-
`mined speed.
`[0022] Hence, the speed difference between the rota-
`tion speed of the output rotation unit and the rotation
`speed of the whee! fails below the predetermined speed
`earlier than at the secand acceleration. Accordingly, the
`rotation speed of the output rotation unit can rise to the
`rotation speed of the wheel (the clutch is engaged} in a
`shorter time. As a result, the transmission of an auxiliary
`driving force can be started earlier from the output rota-
`tion unitto the wheel(riding assisted by the auxiliary driv-
`ing force).
`
`Brief Description of Drawings
`
`[0023]
`
`[FIG. 1] FIG. 1 isaright'side view of anelectric bicycle
`1 accarding to an embodiment of the present inven-
`tion.
`
`
`
`[FIG. 2] FIG. 2 is a front cross-sectional view of a
`hub- unit 4,
`
`[FIG. 3] FIG. 3.is a control circuit block diagram of
`the electric bicycle 1.
`[FIG. 4] FIG. 4 is a flowchart showing an example of
`a control operation performed on the eleciric bicycle
`1.
`
`[FIG. 5] FIG. 5: is a graph for explaining a rotation
`speed change of an output rotation unit when the
`output rotation unit starts rotating in a coasting state.
`[FIG,. 6] FIG. 6 is a flowchart showing.a modification
`of the control operation performed on the electric bi-
`cycle 1.
`[FJG. 7] FIG: 7 is a graph for explaining a rotation
`speed changeof the output rotation unit in the mod-
`ification in which the output rotation unit starts rotat-
`ing in a coasting state.
`
`Description of Embodiments
`
`[0024] An embodimentof the present invention will be
`specifically described below with reference to the accom-
`
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`panying drawings.
`[0025]
`FIG. 1 is aright side view illustrating an electric
`bicycle 1 according to the embodiment of the present
`invention.
`
`In the following explanation, the directions of
`[6026]
`the electric. bicycle 1 are specified with respect to the
`front.side (the left side of FIG. 1) of the electric bicycle
`1. Thus, in FIG. 1, the left side indicated on the paper is
`the front side of the bicycle, the right side thereon is the
`rear side of the bicycle, the near side thereonis the right
`side of the bicycle, and the far side thereon is the left side
`of the bicycle.
`[0027] As shown in FIG. 1, in the-electric bicycle 1, a
`hub unit 4 containing a motor 3 is attached to the ends
`(lower ends) of a frant fork 2. A rim 6 of a wheel at-the
`front (front wheel) & is connected to the hub unit 4 via
`spokes 7. The electric bicycle further includes a battery
`10 mounted between a seat past 8 and a rear wheel 9.
`Moreover, theelectric bicycle 1
`includes a sensor 12
`(pedal force detectar) located at a position receiving a
`pressing force (pedal force) from pedals 11. The sensor
`12 detects the pedal force applied to the pedals 11. When
`the sensor 12.detects a predetermined pedal force, paw-
`er is applied to the moter 3 of the hub. unit 4 fram the
`battery 10, allowing the motor 3 io generate a driving
`force (will be called “auxiliary driving force") for the front
`wheel5. Since the front wheel5 is rotated by the auxiliary
`driving force, the electric bicycle 1 can be moved forward
`even by a small pedal force. In-other words, inthe electric
`bicycle 1, a driving force generated by rotating the pedals
`11 with human poweris assisted by an auxiliary driving
`farce generated by the motor3.
`[0028]
`FIG. 2 is a front.cross-sectional view of the hub
`unit 4.
`
`Referring to FIG. 2; the hub unit 4 includes a
`[0029]
`hub casing 20 serving as an outer case, the motor 3,.a
`speed reducing mechanism 21, and a clutch 22.
`[0030] The hub casing 20 is a hollow cylinder having
`a laterally extended central axis. On the outer surface of
`the hub casing 20, projections 23 are integrally formed
`irom the hub casing 20 in a radial direction so as to be
`spaced in a lateral direction and.a circumferential direc-
`tion. The projection 23 has a through hole 24 for locking
`the spoke 7 (see FIG. 1). The hub casing 20 can be lat-
`erally divided at the pasition of the right projection 23.
`The left and right parts of the hub casing 20 can be as-
`sembled with a screw 25. The left.and right side walls of
`the hub casing 20 are shapedlike discs, each having a
`central positian where a through hole 26 laterally pene-
`trating the side walls is formed.
`[0031] The motor 3 is located on the left side of the hub
`casing 20, The motor 3 includes a motor casing 27 serv-
`ing as. an outer case, a stator 28, and a rotor 29. The
`motor casing 27 is a hollow cylincer having a laterally
`extended central axis. The motor casing 27 has aleftend
`27A that is reduced in diameter. The left end 27Ais. in-
`
`serted from the right side into'the through hole 26 on the
`left side wall of the hub casing 20. A ring bearing 31 is
`
`interposed betweenthe left end 27A of the motor casing
`27 and the edge of the through hole 26 on the left. side
`wall of the hub casing 20. Thus, thé hub casing 20 and
`the motor casing.27 are.connected so asto rotate relative
`to each other. On the left end 27A of the motor casing
`27, a support shaft 32 is integrally provided so as to pro-
`trude from the circle center position of the left end 27A
`outwardlyto iheleft side. The right end face of the support
`shaft 32 faces the interior of the motor casing 27 and
`has. a recess 33 dented to the left. A ring bearing 34 is
`fit into the recess 33. The right side wall of the motor
`casing 27 is shaped like a disc having a through hole 35
`at the circle center position of the right side wall. The
`through hole-35 laterally penetrates the right side wall. A
`ring bearing 36is fit into the through hole 35. Further-
`mere, three shafts 37 protruding outwardly to the right
`side.are provided outside the through hole 35 in the radial
`direction and are located at regular intervals in a circum-
`ferential direction on the right side wall.
`[0032] The stator 28 is a ring stator having a central
`axis. extending in the. lateral direction. The stator 28 is
`accommodatedin the motor casing 27 and is fixed tothe
`motor casing 27 with a screw 38. The rotor 29 is:disposed
`in the hollow part of the stator 28 so as to be concentric
`with the stator 28. Moreover, a laterally protruding sup-
`port shaft 39 is integrally provided on the rotor 29 so as
`to be located at.the circle center position of the stator 28.
`The support shaft 39 is inserted into the hollow part of
`the bearing 36of the through hole 35 on the right side
`wall of the motor casing 27 and the hollow part of the
`bearing 34 of the support shaft 32 on the left end 27A of
`the motor casing 27. Thus, the rotar 29 is. rotatably sup-
`ported by the motor casing 27 through the bearing 36
`and the bearing 34. The right end of the support shaft 39
`protrudes. out of the right side wall of the motor casing
`27. Agear 40 is formed onthe outer surface of the support
`shaft 39.
`[6033] Thespeedreducing mechanism 21 is disposed
`on the right of the motor 3 in the hub casing 20. The
`speed reducing mechanism 21 includes three gears 45,
`arotary table 46, and a holder 44. FIG. 2 illustrates one
`of the gears 45.
`[0034] The.gear 45 is a cylinder having a laterally ex-
`tended central axis. One of the shafts. 37 on the right side
`wall of the motor casing 27 is inserted at the circle center
`of the.gear 45. The gear 45 is rotatably supported by the
`corresponding shaft 37. The gear 45 has a large-diam-
`eter part.45A on the left side and a small-diameter part
`45B. that is located integrally on the right of the large-
`diameter part 45A and is smatller in diameter than the
`large-diameter part 45A. A gear 47 is formed on each of
`the cuter surfaces.of the large-diameter part 45A.and the
`small-diameter part 45B. The gear 47 on the large-diam-
`eter part 454 of the gear 45. is engaged with the gear 40
`on the right end of the support.shaft 39 of the rotor 29.
`[0035] The rotary table 46 is disposed an the right of
`the gears 45. The rotary table 46 is circular when viewed
`in the lateral direction. The outer end of the rotary table
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`46 is entirely bent to the left. A gear 48 is formed on the
`inner surface of the bent part. The gear 48 is engaged
`with the gear 47 of the small-diameter part 45B of the
`gear 45. Thus, the.gear 40 serving as a sun gear on the
`support shaft 39 and the three gears 45 serving as plan-
`etary gears constitute a planetary gear mechanism.
`[0036] The holder 44 is a disc having a smaller diam-
`eter than the rotary table-46. The holder 44 is: disposed
`between the three gears 45 and the rotary table 46. in the
`lateral direction tna noncontact manner with the gears
`45 and the rotary table 46. The holder 44 has the three
`gears 45 facing the right side wall of the motor casing 27
`from the right, and supports the-right ends of the shafts
`37 on. the right side wall. The. holder 44 is fixed on the
`right side wall. of the motor casing.27 with a screw 49.A
`laterally extended support shaft 50 is inserted atthe circle
`center position of the holder:44.andis fixed.on the holder
`44, The support shaft 50 projects outwardly to the right
`from the holder 44.
`
`[9037] The clutch 22 in the hub casing 20 is disposed
`onthe right of the speed reducing mechanism 21 and on
`the left of the right side wall of the. hub casing 20. The
`clutch 22 is .a so-called one-way clutch including a first
`rotary table 51 acting as an output rotation unit rotated
`by the rotor 29 of the motor 3 via the speed reducing
`mechanism 21, and. a‘secondretary table 52.
`[0038]
`Thefirst rotary table 51 serving as an output
`rotation unit is an annular ring having a laterally extended
`central axis. The outer end of the first rotary table 51 is
`fixed to the rotary table 46 of the speed reducing mech-
`anism 21 with a screw 53. The inner-end of the first rotary
`table 51 projects to the. right side. Multiple ratchet claws
`54 are provided around the inner projecting end. The
`ratchet claws 54 elastically project to the outside in the
`radial direction while being oriented in one circumferen-
`tial direction ofthefirst rotary table 51 (specificaliy, in the
`same direction as the rotation direction of the front wheel
`5). A ring bearing 55 is fit at the hollow part of the first
`rotary table.51, and the support.shaft 50 of the holder 44
`is inserted into the hollow part of the bearing 55 fram the
`left. The support shaft 50 rotatably supports the first rotary
`table 51 through the bearing 55.
`[0039] The second rotary table 52 is an annular ring
`having a laterally extended central axis. The outer end
`of the second rotary table 59 is fixed toe the right side
`wallof the hub casing 20-with a screw 59. Multiple ratchet
`grooves 58 are formed over the inner surface of the sec-
`ond rotary table 52. The ratchet grooves 58 are dented
`to the outside in the radial direction while being oriented
`in one circumferential direction of the second rotary table
`52 (specifically, in the same direction as the rotation di-
`rection of the front wheel 5).
`[0040] A ring bearing 56isfit into the through hole 26
`onthe right side wall of the hub casing 20. The support
`shaft 50 is inserted into the hollow part of the bearing 56
`from the left. The support shaft 50 rotatably supports the
`hub easing 20 and the second rotary table 52 through
`the bearing 56. The right end of the support shaft 50
`
`projects out of the right side wall of the hub casing 20 to
`the right side.
`[0041] The ratchet claws 54 of the first rotary table51
`are located at the same positions as the ratchet grooves
`58 of the second rotary table 52 in the lateral direction
`and are located inside the ratchet grooves 58 in the radial
`direction.
`In the right side view,
`in the case where the
`first rotary table 51 and the second rotary table-52 rotate
`counterclockwise (the rotation direction of the frontwheel
`5), the ratchet claws 54 are engaged into the ratchet
`grooves 58 to combine the first rotary table 51 and the
`second rotary table 52 when the rotation speed of the
`first rotary table 51 serving as an output rotation unit ex-
`ceeds the rotation speed of the second rotary table 52.
`in this state, the clutch 22 is engaged.
`[0042] Whenthe rotation speedofthe first rotary table
`(output rotation unit) 51 falls below the rotation speed of
`the second rotary table 52, the ratchet claws 54 are dis-
`engaged from the ratchet grooves 58 to disconnect the
`first rotary table 51 and the secondrotary table-52. In this
`state, the clutch 22 is disengaged. When the clutch 22
`is disengaged while the first rotary table 51 and the sec-
`ond rotary table 52 are rotated, the ratchet claws 54 elas-
`tically retract inward in the radial direction of the first ro-
`tary table 51 and thus are not engaged wiih the ratchet
`grooves 58 in the rotation direction. Thus, the first rotary
`table 51 and the second rotary table 52 can smoothly
`rotate relative to each other.
`
`In the hub unit 4 configured thus, the support
`[0043]
`shafts 32 and 50 on‘the motor casing 27 are fixed to the
`ends of the front fork 2 (see FIG. 2). The spokes 7 (see
`FIG. 2) of the front wheel 5 are locked into the through
`holes 24 of the projections 23 on the outer surface of the
`hub casing 20. Hence, in the hub unit 4, at least the motor
`casing 27 and the stator 28 are fixed to the front. fork.2
`while the hub casing 20 and the second rotary table 52
`are fixed to the front wheel 5. Thus, the rotation speed
`of the front wheel 5-is equal to those of the hub casing
`20 and the second rotary table 52.
`[0044] When the motor 3,receives powerfrom the bat-
`tery 10 (see FIG. 1) through wires 57, the motor 3 rotates
`the rotor 29 concentrically with the front wheel 5 clock-
`wise in the right side view so as to generate the auxiliary
`driving force. The auxiliary driving force is transmitted to
`the rotary table-46 from the support shaft 39 of the rotor
`29 through the gears 45 of the speed reducing mecha-
`nism 21, rotating the rotary table 46 with thefirst rotary
`table. (output rotation unit) 51 of the clutch 22 counter-
`clockwise in the right side view.
`[0045]
`Since the speed reducing mechanism 21 is
`provided, the rotation speedofthe first rotary table (out-
`put rotation unit) 51 is lower than that of the rotor 29.
`Alternatively, the rotor 29 and the firstrotary table 51 may
`be directly connected to each other in the absence of the
`speed reducing mechanism 27. In this configuration, the
`rotation speed of the first rotary table 51 serving as an
`output rotation unit is equal to the rotation speed of the
`rotor 29. In the present embodiment, the speed reducing
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`mechanism 21 causes the first rotary table 51 serving as
`an output rotation unit and the rotor 29 to rotate in oppo-
`site directions.
`In the case where the roter 29 and the
`
`first rotary table 51 are directly connected to each other,
`the first rotary table 51 and the rotor 29 rotate in the same
`direction (counterclockwise in the right side view). Thus,
`in the case where the rotation speed of the first rotary
`table 51 is: proportionate to that of the retor 29, the rotation
`directions of the first rotary table 51 and the rotor 29 are
`not taken into consideration.
`
`Inthe case where the rotation speed ofthe first
`[0046]
`rotary table 51 is equal to or higher than that ofthe second
`rotary table 52 (front wheel 5), the first rotary table 571
`and the.second rotary table 52 are both rotated so as to
`engage the clutch 22 (the rotation speeds may be 0).
`Thus, the hub casing 20 fixed to the second rotary table
`52 rotates in the same direction (counterclockwise in the
`right side view) as the first rotary table 51, rotating the
`front wheel 5 (see FIG. 1) in the: same direction.
`[0047] Whenthe rotation speed ofthe first rotary table
`51 fails below the rotation speed of the second rotary
`table 52 (front wheel 5), the clutch 22 is disengaged.
`[0048]
`Specifically, when the rotation speed of the first
`rotary table 51 serving as an outpui rotation unit is lower
`than that-of the front wheel 5 (second rotary table 52),
`the clutch 22 is disengaged to interrupt power transmis-
`sion between the first rotary table 51 and the front wheel
`5. When the rotation speed of the first rotary table 51
`increases to that of the front wheel 5, the clutch 22 is
`engaged to transmit the auxiliary driving force from the
`first rotary table 51 to the front wheel 5. The clutch 22 is
`specifically disclosed in Patent Literature 1(Japanese
`Patent Laid-Open No. 2009-12627).
`[0049] Referring to FIG. 1, a manual operation part 61
`is attached to a handlebar 60 of the electric bicycle 1..A
`user can set output characteristics such as the auxiliary
`driving force of the motor 3 in response to traveling
`modes, e.g., a flat road mode and an uphill mode by
`operating the manual operation part 61.
`[0050]
`FIG. 3 is a control circuit black diagram of the
`electric bicycle 1.
`[0054] Referring to FIG. 3, the manual operation part
`61 includes a power supply switch 62, a mode setting
`switch 63, a light switch 64, a brake detecting unit 65, a
`wheel rotation information unit 66 (wheel velocity detec-
`tor), a battery life indicator 67, and a mode indicator 68.
`[0052] The power supply switch 62 is.a switch for turn-
`ing on/off the power supply of the electric. bicycle 1. The
`mode setting switch 63 is a switch for setting the traveling
`mode. The light switch 64 isa switch for turning on or off
`a light 69 (FIG. 1). The brake detecting unit 65 detects
`whether or not a brake lever 70.(FIG. 1) attached to the
`handlebar 60. has beén operated to apply a brake (not
`shown). During braking, an indicator lamp (net shown)
`of the manual operation part 61 may be turned on to
`indicate the braking. The wheel rotation information unit
`66 detects therotation speed of the front wheel 5 {in other
`words, the second rotary table 52 and the hub casing
`
`20). Precisely, in the wheei rotation information unit.66,
`a partfor actually detecting the rotation speedofthe front
`wheel 5 is attached near the front wheel 5. The battery
`life indicator 67 indicates the life of the battery 10. The
`modeindicator 68 indicates the current traveling mode.
`[0053] The electric bicycle 1 further includes a control
`unit 75(rotation controller) composed of a microcomputer
`or the like. In the electric bicycle 1, thé control unit 75 is
`elecirically connected to the manual operation part 61
`(the components including the wheelratation information
`unit 66 in the manual operationpart 61), a speed detect-
`ing unit 76 (rotation speed detector), the sensor 12, the
`battery 10, and the motor 3. The battery 10-and the motor
`3 are connected to the contro! unit 75 via a charging/
`discharging circuit 78.
`[0054] Thespeed detecting unit (rotation speed detec-
`tor) 76 detects: the rotation speed of the rotor 29 of the
`motor 3, and calculates the rotation speed of the first
`rotary table 51 based.on therotation speed and the speed
`reduction ratio of the speed reducing mechanism 21. The
`power of the battery 70:is supplied to the motor 3 threugh
`the charging/discharging circuit 78 under the control of
`the control unit 75. Instead of detecting the rotation speed
`of the rotor 29, the rotation speed ofthe first rotary table
`51 may be directly detected or the. rotation speed of the
`first rotary table 51 may be calculated from the speed of
`a rotation part on a powertransmission path fram the
`rotor 29 to the first rotary table 51.
`[0055]
`FIG. 4 is a flowchart showing an example of a
`control operation performed on the electric bicycle 1. FIG.
`Sis a graph for explaining a rotation speed change of the
`first rotary table (output rotation unit) 51 when the rotor
`and the first rotary table (output rotation unit) 51 start
`rotating ina coasting state.
`[0056] Referring to FIG. 4, the control unit 75 monitors
`whether or not the rotation speed of the front wheel 5
`(wheel) exceeds the rotation speed of the firstrotary table
`(output rotation unit) 51 based on the detection results
`of the wheel rotation information unit 66 and the speed
`detecting unit 76 (FIG. 3) (step S1). When the rotation
`speed of the wheel exceeds the rotation speedof the first
`rotary table (Gutput rotation unit) 51 (YES in step $1),
`typically, the electric bicycle 1 travels at a high speed and
`coasts at a.constant speed withouta strong press (coast-
`ing state) on the pedals 11 (FIG. 1}. Gonversely, when
`the rotation speed of the wheel 5 is net higher than that
`of the first rotary table (output rotation unit) 51 (NO in
`step $1), itis expected that-the rotation speedofthe first
`rotary table.(output rotation unit) 51 is not lower than that
`of the front wheel 5 in a typical assisted state where an
`auxiliary driving force has been already generated orin
`a stopped state where the rotation speeds: of the first
`rotary table (output rotation unit) 51 and the front wheel
`5 are 0. In other words, in step $1, the control unit 75
`decides whether the electric. bicycle 1
`is in a coasting
`state or not. The clutch 22 (FIG. 2).is engaged in an as-
`sisted state and a stopped state but is not engaged (dis-
`engaged).in a coasting state.
`
`10,
`
`20
`
`25
`
`30
`
`40
`
`45
`
`50
`
`55
`
`

`

`11
`
`EP 2 671 788 A1
`
`12
`
`[9057] The rotation speeds may be replaced with the
`angular velocities or roms of the front wheel 5 and the
`first rotary. table (output rotation unit) 51. Alternatively,
`the rotation speeds ofthe front wheel 5 and the first rotary
`table (output rotation unit) 51 may be converted to
`traveling speeds. for the electric bicycle 1. In this case,
`the whéel rotation infermation unit 66 (FIG. 3) detects a
`converted value selected from a retation speed, an