des brevets MATA
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`(11)
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`EP 2 604 499 A1
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`Europaisches
`Patentamt
`European
`Patent Office
`Office européen
`
`(1 9)
`
`(42)
`
`EUROPEAN PATENT APPLICATION
`
`(43) Date of publication:
`19.06.2013 Bulletin 2013/25
`
`(51) Int Cl:
`BG62M 6/45 (2610.01)
`
`(21) Application number: 12188771.5
`
`(22) Date offiling: 17.10.2012
`
`
`(84) Desigriated Contracting States:
`AL AT BE BG CH CY CZ DE DK EE ES FIFRGB
`GR HR HUIEISITLILT LU LV MC. MK MT NL.NGO
`PL PT RO RS SE SISK SMTR
`
`Designated Extension States:
`BA ME
`
`(30) Priority: 12.12:2011 JP 2011271586
`
`(71) Applicant: Honda Motor Co., Ltd.
`Tokyo 107-8556 (JP)
`
`(72) Inventor: Shinagawa, Masataka
`Saitama, 351-0193 (JP)
`
`(74) Representative: Beder, Jens
`Mitscherlich & Partner
`SonnenstraRe 33
`
`80331 Minchen (DE)
`
`
`(54)
`
`‘Electric powerassisted bicycle
`
`To obtain an electric power assisted bicycle ca-
`(57)
`ing arotational frequency of the crankshaftfrom the crank
`angle, and an assist amount contral section (10) for al-
`pable of efficiently applying an input torque by a motor
`lowing the motor (5) to generate a driving force assist
`to a pedaling force. [Means far solving the abject]
`amount configured relative to the pedaling force (a rota-
`An electric power assisted bicycle. comprises a pe-
`
`daling force sensor (2) for detecting the pedaling force tion torqué valuefof the crankshaft) detected by the pe-
`generated on a pedal, a motor (5) for assisting a driving
`daling force sensor (2),
`in response to. a phase of the
`force in response to an output of the pedaling force sen-
`crank angle detected by the crank angle sensor (4) when
`sor (2), a crank angle sensor (3) for detecting a crank
`the crank rotational frequency calculated through the
`angle of a crankshaft connected ta the pedal, a crank
`crank rotational frequency calculating means (14) is not
`rotational frequency calculating means (14) for calculat-
`
`less than a predetermined value.
`
`
`
`Printed by Jouve, 75001 PARIS (FR}
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`EP2604499A1
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`EP 2 604 499 A1
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`Description
`
`TECHNICAL FIELD
`
`[0001] Thepresentinvention relates to an electric pow-
`er assisted bicycle provided with a.motor for assisting a
`driving force based on a pedaling force in relation to the
`pedaling force generated when an operator works ped-
`als, and more particularly to the electric power assisted
`bicycle which allows an assist by the motor to be. effi-
`ciently provided at high rotation speeds of the pedals.
`
`BACKGROUND ART
`
`[0002] The electric power assisted bicycle is com-
`priséd of a pedaling force sensor for detecting the pedal-
`ing force generated at a pedal, a motor for assisting a
`driving, force.
`in response to an output of the pedaling
`force:sensor, a crank angle sensor for detecting an angle
`of a crankshaft connected te the pedal, and a crank ro-
`tational frequency sensor for detecting the rotational fre-
`quency of the.crankshaft.
`[9003] Asshown ina patentreference.1, for example,
`there is disclosed the structure that determinesa rotation
`
`cycle of the crankshait and generates assist torque ata
`value multiplying an inputted pedaling force by a prede-
`termined value so:as to prevent a loase feeling of torque
`in the vicinity of zero. pedaling farce by minimizing the
`cycle fluctuation of detected torque. and lowering a driving
`current. of the motor.
`
`PRIOR ART REFERENCE
`
`Patent reference 1: Japanese patent applica-
`[0004]
`tion laid apen publication No. 2004-314753.
`
`DISCLOSURE OF THE INVENTION
`
`PROBLEM TO BE SOLVED. BY THE INVENTION
`
`[9005] However, according ta the above structure,
`though the torque (input torque) applied to the pedaling
`force is provided in proportion to the rotation cycle, a
`phase difference develops between the rotation cycle
`and the input torque at the high rotation speeds or the
`like when the rotational frequency of the crankshaft is
`increased.
`
`For example, the pedaling of the bicycle in the case where
`the top dead center of a pedal relative to a crankshaft 71
`as shown in FIG; 7 is.0 (zero) degree has such a rela-
`tionship that at low rotation speeds of the crankshaft a
`human pedaling force (a vertical axis) relative to a hori-
`zontal axis showing a crank angle (a phase) indicates a
`peak value at 90 degrees, as shown in FIG. 8(a). On the
`other hand, at the high rotation speeds of the crankshaft
`71, the peak value of the pedaling force is.detected clase
`to 135 degrees. of the crank angle since the pedaling
`force that the human applies to the pedal has. atendency
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`to be delayed unconsciously at the high rotation speeds
`of the crankshaft 71, as shown in FIG. 8(b).
`[0006]
`Inthecasewherethe assistin the pedaling force
`in response to the rotation cycle is performed when the
`peak value of the pedaling force is delayed, the torque
`peak value based on a composition of the pedaling force
`and the assist-driving force is more. delayed than 90 de-
`grees. Therefore, ihere is the problem that the input
`torque by the motor is not able to be efficiently applied
`ta the pedaling force thereby ta decrease the pedal effi-
`ciency that assists the pedaling force.
`[6007] The present invention has: been made in view
`of the above described circumstances, anditis an object
`of the present invention to pravide an electric power as-
`sisted bicycle which has a mechanism for allowing input
`torque by a motor to be applied efficiently to a pedaling
`force even at the high rotation speeds of a crankshaft in
`the electric power assisted bicycle.
`
`MEANS FOR SOLVING THE PROBLEM
`
`Inorder to achieve the above object, according
`[0008]
`to claim 1, there is provided an electric power assisted
`bicycle comprising a pedaling force sensor(2) for detect-
`ing the pedaling force. generated at a pedal, a motor (5)
`for assisting a driving force in response to an output of
`the pedaling force sensor (2), a. crank angle sensor (3)
`fer detecting a crank angle of a crankshaft:connected to
`the pedai,.a crank rotational frequency calculating means
`(14) for calculating a rotational frequency of the crank-
`shaft from the crank:angle, and an assist amount control
`section (10) for allowing the motor (5) to generate a driv-
`ing force assist'amount configuredrelative to the pedal-
`ing force (a rotation torque value f of the crankshaft) de-
`tected by the pedaling force sensor(2), in response to a
`phase of the crank angle detected by the. crank angle
`sensor (3) when the crank rotational frequency calculated
`through the crank rotational frequency calculating means
`(14) is not less than a predetermined value (a second
`threshold value).
`[0G09] According to claim 2, in an electric power as-
`sisted bicycle as set forth in claim 1, the driving force
`assist amount provided for the pedaling force is config-
`ured such that composite torque of the driving force.assist
`amount and the pedaling. force causes a torque peak
`value in a phase of 90 degrees when a tep dead center
`of the pedal based on the crankshaft is 0 (zero) degree.
`[0010] According to claim 3,
`in an electric power as-
`sisted bicycle as set forth in claim 2, the. driving force
`assist amountis applied in such a candition of the driving
`force assist amount and the phase that in the case where
`an intermediate position between the top.dead center of
`the pedal and a bettom dead center of the pedal has a
`phase difference from the torque peak value when de-
`tecting a torque curve of the pedaling force in a previous
`rotation of the crankshaft, the torque peak value of the
`composite torque cancels the phase difference.
`[0011] According to claim 4,
`in an electric. power as-
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`EP 2 604 499 A1
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`sisted bicycle as set forth in claim 3, the assist amount
`control section continuously performs configuration of
`the driving force assist amount when there is. the afore-
`mentioned phase difference.
`[6012] According to claim 5, in an electric. power as-
`sisted bicycle as set farth in claim 2, the driving force
`assist amount is configured by a phase which is deter-
`mined in accordance with a map memorizing a relation-
`ship between the crank rotational frequency and the
`phase and bythe driving force which is calculated based
`on the pedaling ferce (the rotation torque value f of the
`crankshaft).
`[09013] According to claim 6, in an electric power as-
`sisted bicycle as set forth in claim 3, the assist amount
`cantrol section comprises.a means for verifying a misde-
`tection of the phase difference. At the time of verification
`of the misdetection, the driving force assist amount in
`proportion to the pedaling force calculated by the pedal-
`ing force sensor (forexample, asensor detected pedaling
`force or a pedaling force effective value) is generated in
`response to the phase of the crank angle detected by the
`crank angle sensor.
`in an. electric power as-
`[9014] According to claim 7,
`sisted bicycle as set forth in claim 1, the assist amount
`cantrol section generates the driving force assist amount
`in proportion to the pedaling force calculated by the pe-
`daling force sensor (forexample, a sensor detected pe-
`daling force or a pedaling force effective value) in re-
`sponse ta the phase of the crank angle detected by the
`crank angle sensor:
`
`EFFECTS OF THE INVENTION
`
`[0015] According to the structure of claim 1, since, at
`the high rotation speeds, the driving force assist amount
`configured for the pedaling force (the rotation torque val-
`ue fof the crankshaft) is applied in responseto the phase,
`a correction at the time of generation of the torque peak
`value is performed relative to the pedaling force so.as to
`eliminate the discrepancy in.a.cycle input, and the driving
`force providing. an direct feeling more can be applied rel-
`ative to an input of the assist amount at the low rotation
`speeds.
`[0016] According to the structure of claim 2, since the
`driving force assist amount is configured such that the
`composite torque of the driving force assist amount and
`the pedaling force causes the torque peak value at the
`phase of 90 degrées when the pedal top dead center
`based on the crankshaft is 0 (zero) degree, the torque
`peak value can be configured in the phase having the
`most need of the pedaling and the ideal assist of the
`driving force by the motor can be performed at the high
`rotation speeds.
`[0017] According tothe structure of claim 3, the driving
`force: assist amount is applied in such condition of the
`driving force assist amount. and the phasethat inthe case
`where the intermediate position between the pedal top
`dead center and the pedal bottem dead center has-the
`
`phase difference from the torque peak value when de-
`tecting the torque curve of the. pedaling force in the pre-
`vious rotation of the crankshaft, the torque peak value of
`the composite torque cancels the phase difference.
`Therefore, the ideal assist of the driving force by the mo-
`tor can be performed at the high ratation speeds of the
`crankshaft.
`
`[0018] According to the structure of claim 4, since an
`input of the assist amountis continuously executed when
`the phaseof the torque peak value of the pedaling force
`has the phasedifferencerelative to 90 degrees, itis pos-
`sible to approach the ideal assist of the driving force by
`the motor.
`
`[0019] According to the structure of claim 5, the driving
`ferce assist amount is configured by the phase which is
`determined in accordance with the map memorizing the
`relationship betweenthe crank rotational frequency and
`the phase and by the driving force whichis calculated
`based onthe pedaling force (the rotation torque value f
`of the crankshaft}. Therefore, the ideal assist of the driv-
`ing. force by the motor-can. be performed at the high ro-
`tation speeds of the crankshaft.
`[0020] According to the structure of claim 6, since the
`assist amount contro! section comprises the means for
`verifying the misdeteciion of the phase. difference, the
`assist of the driving force in a normal phase can be ap-
`plied at the time of the verification of the misdetection.
`[0021] According to the structure of claim 7, since the
`discrepancy between the cycle input and the ideal torque
`peak generation time is small ina region of the low crank
`rotational frequency, the driving force assist amount in
`proportion to the pedaling force calculated by the pedal-
`ing force sensor (for example, the sensor detected pe-
`daling force or the pedaling force effective value} is pro-
`vided in the assist amount control section. Therefore, the
`control can be carried out withoutimpairing such a feeling
`as to be assisted at the same time that the pedal
`is
`worked,
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`[0022]
`
`FiG. 1 is a side explanatory view of an electric power
`assisted bicycle;
`FIG. 2 is a block diagram of an assist driving force
`control device of the electric power assisted bicycle;
`FIG. 3 is a black diagram of a driving ferce assist
`amount configuration means. that makes up the as-
`sist driving force control device;
`FIG. 4 is a flow chart for explaining configuration
`steps with respect to an assist phase and an assist
`amount in the driving force assist amount configura-
`tion means;
`FIG. Sis a graph showing a relationship between a
`torque Curve of a pedaling force relative to a pnase
`of a crankshaft.and a torque curve of a4 driving force
`assist amount;
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`EP 2 604 499 A1
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`FIG. 6 is a flow chart showing verification steps in a
`phase difference misdetection verification means,
`wherein (a) corresponds ta a feed-forward. control
`and (b) corresponds to a feedback control;
`FIG. 7 is a model diagram for explaining the phase
`of the crankshaft; and
`FIG. 8(a) and (b) shaw a pedaling force torque curve
`relative to the phase of the crankshaft, wherein (a)
`is a graph at low rotation speeds and (b) is.a graph
`at high rotation speeds.
`
`BEST MODE FOR.CARRYING OUT THE INVENTION
`
`[0023] Hereinafter, one.of embodiments of an electric
`powerassisted bicycle according tothe presentinvention
`will be described with reference to the accompanying
`drawings. FlG.1 is a side view of the electric power as-
`sisted bicycle provided with an assist driving force contral
`device that is a distinguishing feature of the presentin-
`vention. The assist driving force cantrol device is a device
`for efficiently providing an assist of a driving force by a
`motor at high rotation speeds of a pedal, especially in
`such a situation as ta continue pedaling at the high rota-
`tion.
`
`[0024] The electric power assisted bicycle 50 has a
`head. pipe 51, located in a forward portion of a body, a
`down frame 52 extending rearward and downward from
`the head pipe 51, and a seat pipe 53 extending upward
`from a rear end of the down frame52. A downward ex-
`tending front fork 54 is connected to the head pipe 51 in
`a steerable manner. On a lower end ofthe front fork 54
`
`a front wheel WF is pivotally supported. The front wheel
`WF is provided with a vehicle speed sensor 1 for deteci-
`ing a speed of the electric power assisted bicycle 50. A
`handle 55 is mounted on an upper partion of the head
`pipe 51.
`[9025] On arear end of the down frame, there is. pro-
`vided a rearward extending rear fork 56 while on a rear
`end of this rear fork 56 a rear wheel WR is pivotally sup-
`ported. Moreover, between an upper portion of the seat
`pipe 53 and the rear end of the rear fork 56, there is
`provided a pair of left-and right stays 57.
`[0026] An assist drive unit 60. is supported on the down
`frame 52 and the rear fork 56. A seat post 59 having a
`seat 58 on an upper end thereofis fitted on the seat pipe
`53 in such a mannerthat the upper and lower positions
`of the seat 58 can be adjusted. On the rear side of the
`seat pipe 53, a battery 62 for supplying an électric power
`to the assist drive unit 60 is detachably mounted on the
`stays 63 of the seat pipe 53.
`[0027] Acrankshaft 71 passes through the assist drive
`unit 60 and a sprocket (an output section) 64 so as to
`extend in a cross direction of the body. On both ends of
`the crankshaft 71 there are attached a crank 73L having
`a pedal 72L and a crank 73R having a pedal 72R. When
`an operator works the pedals 72L, 72R, rotation torque
`(a power) is applied to the crankshaft 71. The sprocket
`64 is rotated by the rotation torque applied to the crank-
`
`shaft 71, and the rotation of the sprocket 64is transmitted
`through a chain 65 to a sprocket. 66 on the sideof the
`rear wheel WR thereby to rotate the rear wheel WR.
`[0028] A pedaling force sensor (a magneto-striction
`type torque sensor) 2 fordetecting arotation torque value
`f applied to the crankshaft 71 is provided on the crank-
`shaft 71. This pedaling force sensor 2 detects the rotation
`torque value f of the crankshaft 71 in a predetermined
`cycle.
`The pedaling force (the rotation torque value f) applied
`to the crankshaft 71 by the operatoris a component force
`in the rotational direction of the pedaling force F which
`is generated when the operator works the pedal 72, as
`shown in FIG. 7, and is different from the pedaling force
`(a pedaling force effective value) F which is actually ap-
`plied to the pedal by the operator. The rotation torque
`value f and the pedaling force F can be expressed by a
`relational formula: the rotation torque value f = the pe-
`daling force F x cos 8. When the operator works the ped-
`als 72L, 72R, the pedals: 72L, 72R are pressed in a ver-
`tical direction. Therefore, the direction of the pedaling
`force F is the vertical direction.
`
`Further, in the vicinity of the crankshaft 77 thereis fitted
`acrank angle sensor3 for detecting a crank angle of the
`crank: 73 connected to the crankshaft 71.
`
`[0029] The assist drive unit 60 is configured to integral-
`ly holds.within a casing a motor 5, a motordriving circuit
`(an operationdriver) 6 for driving the motor 5, an assist
`amount control section 10 for carrying outa PWM control
`of the motor driving circuit on the basis of the rotation
`torque value f detected by the pedaling force sensor 2,
`and an assist sprocket 61 whichis rotated by having the
`driving force transmitted from a motor driving shaft 67 of
`the motor 5. A chain 65 is attached to the assist sprocket
`61, whereby the assistdrive unit.60 transmits the driving
`force of the motor 5 to the aforementioned driving mech-
`anism.
`
`[G030] The assist control section 10 caries out the
`PWM contro! of the motor driving circuit (carries out an
`assist control) such that the motor 5 generates assist
`torque (an assist force) calculated based on the rotation
`torque value f detected by the pedaling force sensor 2.
`The assist torque (the assist force) is calculated in differ-
`ent steps relative to the rotation torque value f between
`the high rotation speeds and the low rotation speeds of
`the crankshaft. Namely, at the high rotation speeds of
`the crankshaft, the assist torque is calculated based on
`the rotation terque value f, while at the low rotation
`speeds, the pedaling force (the pedaling force effective
`value) F which is applied by the operator to the pedal in
`the vertical direction is calculated fram the rotation torque
`value f, so that the assist torque of a predetermined value
`relative to the pedaling force F is calculated. Particulars
`of the calculation steps with respect te the assist torque
`at the high rotation speeds and atthe low rotationspeeds
`of the crankshaft will be-described later.
`
`[0031] The assist torque generated by the motor 5 is
`transmitted through the assist sprocket 61 to the chain
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`EP 2 604 499 A1
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`65. Therefore, when the operator works the pedal 72L,
`72R, the rotation torque f (the driving power) applied to
`the crankshaft 71 and the assist torque generated by the
`motor 5 are transmitted through the chain 65.
`to the
`sprocket 66 on the rear wheel side, whereby the rear
`wheel WR is. rotated. By the way, behind the assist
`sprocket 61 there is provided an idler 68 for increasing
`a contact angle of the chain 65.
`[0032]
`Further, the assist drive unit 60 has a mecha-
`nism which allows the sprocket 64 to be rotated when
`the pedals 72L, 72R are worked in the direction (the for-
`ward direction) that the electric power assisted bicycle
`50. moves forward and which doesnot allows the. sprocket
`64 to be rotated when the pedals 72L, 72R are worked
`in the direction opposite to the farward direction.
`[0033] Next, the assist driving farce control device of
`the electric power assisted bicycle will be described with
`reference to the block diagramsin FIG. 2 and FIG. 3.
`Thistorque control device, as shown in FIG. 2, is com-
`prised of a speed sensor 1 for detecting a speed of the
`electric power assisted bicycle, the pedaling force sensor
`2 for detecting the pedaling force (the rotation torque val-
`ue) generated in the pedal, the crank angle sensor 3.for
`detecting the angie of the.crankshaft to which the pedals
`are connected, the mator 5 for assisting the driving force
`in response to an output of the pedaling force sensor 2,
`the assist amount control section 10 for controlling the
`assist amount of the driving force, and the motor driving
`circuit 6 for driving the motor 5 based ona driving signal
`from the assist amount control section 10.
`
`[0034] The assist amount control section 10 is. com-
`prised.of a speed and change amount calculating means
`41 for calculating a speed and a change amount of the
`speed based on a signal from the speed sensor 1, a pe-
`daling force effective value detecting means 12 for de-
`tecting the pedaling force effective value based on asig-
`nal from the pedaling force sensor 2, a crank angle de-
`tecting means 13 for detecting the crank angle based on
`a signal from the crank angle sensor 3, a crank rotational
`frequency and change amount calculating means. 14 for
`caiculating the crank rotational frequency and a change
`amount of the crank rotational frequency based on a sig-
`nal from the crank angle sensor 3, and. a driving force
`assist amount configuration means.20 for configuring the
`driving force assist amount based on the speed and the
`speed change amount from the speed and change
`amount calculating means 11, the rotation torque value
`and the pedaling force effective value from the pedaling
`force effective value detecting means 12, the.crank angle
`from the crank angle detecting means 13, the crank ro-
`tational frequency and the change amount of the crank
`rotational frequency from the crank rotational frequency
`and change amountcalculating means 14.
`[0035] The speed and change amount calculating
`means 11 inputs the:signal from the speed sensor 1 at
`intervals of a certain period to calculate the speed and
`calculates the change amount of speed at intervals of a
`certain time.
`
`The crank angle detecting means 13 inputs the signal
`from the crank angle sensor 3 at intervals of a certain
`period to detect the crank angle at the present moment.
`The crank rotational frequency and change amount cal-
`culating means. 14 inputs the signal from the crank angle
`sensor3 at intervals of a certain period to calculate the
`crank rotational frequency and calculates the change
`amount of crank rotational frequencyat intervals of a cer-
`tain time.
`
`[6036] The pedaling force effective value detecting
`means 12 estimates and detects the pedaling force ef-
`fective value F.(the pedaling forceactually applied by the
`operator to the pedals 72) that is the force operating
`downward in the vertical direction, from the pedaling
`ferce during traveling (the. rotation torque value f that op-
`erates in the vertical direction relative to the crankshaft)
`detected by the pedaling force sensor 2. By the way,
`without providing the pedaling force effective value de-
`tecting means 12, it is possible ta use simply an output
`value (a rotation torque value} of the pedaling force sen-
`sor 2.
`
`The driving force assist amount configuration means 20,
`in response to the phase of the crank angle, configures
`the driving force assist amount that is a predetermined
`value relative to the rotation torque value detected by the
`pedaling force sensor 2 orrelative to the pedaling force
`effective value calculated by the pedaling force effective
`value detecting means 12.
`[0037] The driving force assist amount configuration
`means 20 is provided with a pedaling force memory
`means 21 for memorizing the pedaling force effective
`value generated on the pedals (or the output value ofthe
`pedaling force sensor 2), an assist amount calculating
`means 22 for calculating the pedaling force assistamount
`based on the crank rotation frequency, the crank angle,
`the rotation torque value or the pedaling force effective
`value, a torque-electric current value calculating means
`23 for calculating an electric current value corresponding
`to the calculated driving force assist amount, a duty ratio
`calculating means 24 for calculating an dutyratio of the
`electric current value, and a phase difference misdetec-
`tion verification means 26 (FIG. 3). The driving force as-
`sistamount configuration means 20 is comprised of CPU,
`for example, and each of the aforementioned means. is
`executed based on a previously configured program or
`a hard circuit.
`
`[0038] The pedaling force memory means 21 memo-
`rizes sequentially at intervals of a certain period. the pe-
`daling force (the rotation tarque value) relative to.several
`cycles of the crankshaft:
`The assist amount calculating means 22, atthe high ro-
`tation speeds of the crankshaft, detects a torque curve
`from the pedaling force in.a previous rotation of the-crank-
`shaft, thereby calculating, in this torque curve, a phase
`difference of an intermediate position between a pedal
`top dead center and a pedal bottom dead center from a
`torque peak value, and calculates a working torque value
`necessaryfor the driving force assist amount (the driving
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`force assist amount thatis.a predetermined value relative
`to the pedaling force) from the pedaling force (the rotation
`torque value). Namely, this-working torque value is can-
`figured such that composite torque of the driving force
`assist amount and the pedaling force causes a torque
`peak value in.a phase of 90 degrees when the pedal top
`dead center based on the crankshaftis 0 (zero) degree.
`A specific method of the: calculation of the working torque
`value will be described hereunder.
`
`[8039] The torque-electric current calculating means
`23. inputs the werking torque value thereby. to calculate
`an electric current command value in response to the
`working torque value.
`The duty ratio calculating means 24 calculates a duty
`ratio af a driving pulse thereby to output it as a PWM
`output to the motor driving circuit 6.
`[0040]
`In the motordriving circuit'6, the tarque control
`is performed in response to the PWM output to drive the
`motor 5. The motor driving circuit 6 has each switching
`element of multiple phases (three phases of UVW), and
`the assist control section 10 performs ON/OFF control
`of each switching element of the UVW phase at.a pre-
`determined duty ratio thereby to PWM contral the motor
`driving circuit 6. Based on this PWM control, the motor
`driving circuit 6 converts a direct current power of the
`battery 62 to a three-phase alternating current powerand
`passes a three-phase alternating current through a U-
`phase stator coil, a V-phase stator coil and a w-phase
`stator coil of the motor 5 so as to rotate the motor driving
`shaft 67 of the motor 5.
`
`[0044] AMAP memory means 25 estimates and pro-
`vides an assist phase in the case.of applying the driving
`force. assist in the assist amount calculating means 22,
`and a map that previously configures a relationship be-
`tween the rotatianal frequency and the phase is memo-
`rized therein.
`
`[8042] The phase difference misdetection verification
`means 26 is configured te recagnize the misdetection of
`the phase difference when the estimated assist phase is
`a value that is theoretically impassible. The verification
`whether it is misdetectian or not is executed in such a
`
`way as to judge whether the phase difference of 90 de-
`grees or more develops in the assist phase relative to
`the detected phase of the crank angle, for example. Then,
`in the case where there is the phase difference of 90
`degrees or more, the misdetection is. recognized. In this
`case, the verification judgment may be made by setting
`the threshold value for the misdetection at 90 degreés.
`[0043] Next, the steps of configuring the driving force
`assist amount by the driving force assist amount config-
`uration means 20 will be described with reference to. FIG.
`4.
`
`When a mode of an assist traveling is selected at the
`time of traveling of the electric power assisted bicycle
`(step: 100), firstly the pedai rotational frequency change
`amount. inputted from the crank rotational frequency and
`change amount calculating means 14 or the speed
`change amount
`inputted from the speed and speed
`
`change amount calculating means 11 is compared with
`a first threshold value configured at the predetermined
`value (step 101). Since, when this value (change amount)
`is not less than the first threshold value, there is assumed
`the case wherethe pedals are not worked successively
`at the high rotation speed or the. case where the speed
`is reduced by the braking aperation, it is judged thatit is
`not suitable for the control at the high rotation speeds of
`the pedal, so that an assist control (a normal assist con-
`trol) under normal conditions.(at the low rotation speeds)
`is carried out.
`
`In the normal assist control, the pedaling force
`[0044]
`effective value is calculated (step 201), and the assist
`amount in proportion to the pedaling force effective value
`is calculated through a pedaling force. proportional control
`(step 202), so that the driving force (the working torque
`value) is applied at the torque peak value:in proportion
`ta the pedaling force effective value. Moreover,
`in the
`case of the normal assist control, whenonly the output
`value (the rotation torque value) of the pedaling sensor
`2 is used-without using the pedaling force effective value,
`the driving force (the working torque value) is applied at
`the torque peak value in proportion to the rotation torque
`value.
`
`Further, in the normal assist control, the assist amount
`may be calculated by the speed proportional contro! as
`a substitute for the pedaling force proportional control.
`[0045] On the other hand, when the pedal rotational
`frequency or the change amount of the. speedis less than
`the first threshold value, the pedaling force (the rotation
`torque value) detected by the pedaling force sensor 2 is
`stored inthe pedaling force memory means 21 (step 102).
`Next, the comparison is performed between the pedal
`rotational frequency (the crank rotational frequency)
`which is. sequentially inputted from the crank rotational
`frequency calculating means 14 and.a second threshold
`value (step 103). The second threshold value (a pedal
`rotational frequency) is set at 70 rotations per minute
`which does notoccur in the normal traveling, for example.
`[0046] Whenithe pedairotationalfrequency is lessthan
`the second threshold value, it is judged that the. pedals
`are not rotated at the. high rotation speed, so that the
`assist control at the time of the normal condition (at the
`low rotation speeds) is performed (steps 201 and 202).
`When the pedal rotational frequencyis not less than the
`second threshold value, it is judged that the pedals are
`rotated at the high rotation speed, so-thatfirst the crank
`angle at the present moment is. detected (step 104).
`Then, the crank rotational frequency is calculated (step
`1085).
`[0047] Next, the calculation of the phase (the assist
`phase) to apply the driving force, based on the detected
`crank angle and crank rotational frequency {step 106), a
`calling of the pedaling force (the rotation torque value) in
`the previous rotation (step 107) and the calculation of the
`assist amount (step 108) are carried out
`in serious
`processing.
`For example, in the case of feed forward control in which
`
`10,
`
`20
`
`25
`
`30
`
`40
`
`45
`
`50
`
`55
`
`

`

`11
`
`EP 2 604 499 A1
`
`12
`
`the assist phase is estimated by the map of the rotaticnal
`frequency-phase, for example, the assist phase corre-
`spanding to the crank rotational frequency is found by
`using the map of the MAP memory means 25, from the
`detected crank rotational frequency, thereby to find the
`assist amount of the driving force assist by a predeter-
`mined calculation formula. The assist phase and the as-
`sistamount in this case are configured such that the com-
`posite torque of the driving force assist amount and the
`pedaling force causes the torque peak value at the phase
`of 90 degrees (270 degrees) when the pedal top dead
`center based on the crank shaft. 71 is 0 (zero) degree.
`[0048]
`Further, in the case of the feedback control that
`the assist phase and the assist amount are determined
`in consideration.of the pedaling force (the rotation torque
`value) generated in the previous cycle, when the torque
`curve based on the pedaling force in the previous cycle
`(0-360: